https://ntrs.nasa.gov/search.jsp?R=20110004116 2019-08-30T14:27:57+00:00Z r~_-'t While the engineering and architec- I-:-----:!t tural disciplines have always prized the elegant solution, there are times when brute strength is imperative. Introducing the Apple" Macintosh" QuadraN 700 and So much power in so little space. The Quadra 900 Quadra 900 computers. is just 18.6" high and fits Awesomely powerful. comfortably next to your . . desk. The Quadra 700 fits FeroCIOusly fast. But each IS comfortably on top a/it. still very much a Macintosh. Up to twice as swift as any of their forebears, they're the first Macintosh computers to be built around the Motorola 68040, rated at 20 MIPS and running at 25 MHz. A highly inte- grated deSign, the 040 combines the processor, math coprocessor, memory controller, and cache memory all onto one chip. More important than merely technical mea- surements, the Macintosh Quadra computers are totally harmonized systems. The hardware architecture, operating system, interface, periph- erals, and networking were all designed from the start to optimize the 040's power and work together smoothly as a single integrated system. Anyone using compute-intensive applica- tions -like 3-D modeling and stress analysis- will immediately appreciate the difference. Popular software packages like Infini-D, MicroStation Mac, and Virtus WalkThrough per- form more nimbly and Big just got bigger. The new Macintosh 21" Color Display gives you more drawing board to work on. Colors are vivid, focus is crisp,,, :.;; ~.:<: ' •. ~.;;,.; • •• . ~ . brightness and contrast are high. • ·U·bii ddRfJ StI/lJOrl for up '" 16" mtJndon; 8biJ I'lIteo SU/1JOrl for up '" 21' m()ndors. "7bere are 1.0 ""l' "1'1)' In tiJ il. Simply (l(kJ an IIlifJ1icalkm calM SojIPC. or I",eoj I/JJ() card; from Orange ,II"",. /he Mac21i6 or Orange3116. © 1991 -'(JfJIe OmI{JUre, I"~ AM", /he Virlus Corp camera I 'ml1/(e uYJS I:rIJ(IIa:/ m Injim-D; lIr}im /J ~ a /rrUIem",; ojS{>ecultJr Inlenllllimroi. lid Orbder Imoge UYJS muled u'lih MicroSIIdion Mac: MicroSIalr»l L'I a nr,rslered trtufernari oj 8eP/lley SysJems In~ . an IIllergrapli .!filiale. ORACLE if. reg£!rDru~ an> _a,ks 0{ A{IfIIe Compu,", Ino Fr",dJ lillO' screen u{~ aw,leti a'lib hrll" ~11"7'brougb. I'm,,, ~"I;'IIIroU!ib IS a 1""1",,,,,i 0{ /rlukmllrl o{Orack Cnl/""'!<)II Fa,1illE +IMac IS a rtgISltorer/ /rrIllemJ,,; 0{ Fox Sojhmrt. lllc, C".,I PiaIlIS". rtgISltml lrilllN'llIrt 0{ C"",I PkllllS .'ic/la .. ,.. 1110 MHJOIi IlIId 1'tJU'l!rPoml art rtRI '" i -;: 0.13 :. al ~ 0.12 15 ~ 0.11 <.l (/) (; E 0.10 C> Q; J: 0.09 0.08 6 8 10 Reverse Bias, V 0.14 .~ Oi al 0.12 0.10 0.08 L-_--' __ .....J. __ -..I.. __ ...... __ ...... _~ o 8 12 Reverse Bias, V Figure 2. The Heights of Schottky Barriers as functions of reverse bias were determined by activation-energy analysis. NASA Tech Briefs, December 1991 PRINCIPLES OF QUAllTY MEASUREMENT: SECOND IN A SERIES. SIMULTANEOUS MULTIPLE MEASUREMENTS. It will last an instant and happen exactly once. The more data you can extract from that single event, the more confident you can be. Two channels or twenty - when it's your project, they're all critical. You can't sacrifice accuracy, no matter what the channel count. You won't accept less than total synchronization between channels. And you haven't got the time to wrestle with racks of scopes or one-off configurations that turn measurements into a mess. You need results you can trust from a system that sets up in minutes, not months. A maSSively parallel architecture that won't load down as the channel count goes up. And most aU, a system designed to let you data on your own terms. At Nicolet, we see things the same way. Our oscilloscopes, multi- channel systems, probes and accessories are designed for scientists and engineers with no tolerance for error. Our specifications are valid for your world, not a hypothetical "best case"- and they don't change as you add channels. The ~icolet user interface gives you such close and responsive control over your measurement that it's Ivirtually; transparent. When you need to see all the data in a I single dritical event, 100kuA Nicolet. The new Nicolet MultiPro delivers multichard results with oscilloscope ease of use and absolute data integrity, a configuration right for your mea urements - circle the nu ber or caU 1 rightn w. Circle Reader Action No. 697 sources. The thickness of the deposit is about 50 A. The substrate is heated to a temperature between 200 and 500 °C or between 680 and 800 °C for the deposi- tion of IrSi or IrSi3, respectively. The IrSi or IrSi3 is then patterned by ion milling. Aluminum contacts are then deposited on the silicide and substrate. Experimental devices fabricated by this process have been characterized by current-vs.-voltage measurements and activation-energy analysis. In addition, the cutoff wavelength of an Si/lrSi3 detector was determined independently by measur- ing its photoresponse. For SillrSi3, the measured heights of the Schottky barriers ranged from 0.138 eV to 0.089 eV as the reverse bias voltage ranged from -1 to -10 V; this represents a range of cutoff wavelengths from 9 to 14 m. Similar results were obtained for SillrSi (see Figure 2). This oork was done by True-Lan Un of Gaitech for NASA's Jet Propulsion lab- oratory. For further information, Circle 122 on the TSP Request Card. In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be ad- dressed to Edward Ansell Director of Patents and Ucensing Mail Stop 305-6 Gaiifornia Institute of Technology 1201 East California Boulevard Pasadena, CA 91125 Refer to NPQ-18027 and NPQ-17946, volume and number of this NASA Tech Briefs issue, and the page number. Characterization of Electrical Response of Photodetector Fourier analysis of input and output yields electrical frequency response. Goddard Space Flight Center, Greenbelt, Maryland Fourier analysis is the basis of a method of characterizing the electrical frequency or time response of a photodetector. In this method, the detector is stimulated by an optical input Signal, the intensity of which is modulated with a square wave or other repetitive waveform of known frequency spectrum, and the output of the detector is recorded. The electro-optical transfer function , which characterizes the frequen- cy response of the detector, is then com- puted as the ratio between the discrete Fourier transforms of the output and input waveforms (see figure). The real and imaginary components of the discrete Fourier transform S(k) at the kth point in frequency space are given by N-l S (k)real = hE X(i) cos (2~ik) i = 0 N-l S(k)imaginary = h 1; X(i) sin (2~ik) i = 0 where N is the number of samples, k can be any integer from 0 through N -1 , and X(i) is the instantaneous amplitude of the Signal in question at the time of the ith sample. The sampling period, ~ , must be an integral submultiple of the period of the waveform, and the reciprocal of the sampling period must be at least twice the highest frequency present in the waveform. The frequency resolution, M, becomes finer as the number of samples increases: At = 1/N~ The method has been applied success- fully to Golay-cell and bolometer detectors and is applicable to any detector system, the ac component of the electrical re- sponse of which is linear. The principal ad- vantage of this method is speed; because the input waveform contains many fre- quencies spanning the entire spectral range of interest, one set of measurements serves to characterize the response of the detector at all of these frequencies. On the other hand, in the traditional method, the frequency response of a detector is meas- ured by exciting it with a sinusoidally mod- ulated signal , one frequency at a time, and measuring the output with a lock-in am- plifier or spectrum analyzer. This is a time- consuming and tedious process in which accuracy depends on stability in both the output of the modulated source and the sensitivity of the detector. Changes in either the source or the detector (e.g., tempera- ture dependence of the sensitivity of a bolometer) during a series of measure- ments can render the calibration invalid. In one instance of the method, a Golay cell was illuminated by an infrared light- Light-Emitting Diode The Electrical Fre- quency Response of a Photodetector can be determined quickly from a single measurement by use of the discrete Fourier transform to analyze the input and output waveforms. Digital OscUlo$COpe or Other Oat.AcQulsltlon Unit Computer Running Discrete-Fourier· Transform Algorithm Output Data: Electrical Frequency Response of PhotOdeteclor emitting diode powered by square wave with a period of 2.048 s. A digital oscil- loscope sampled the input and output waveforms at 4,096 equal intervals (1/2 ms) during one cycle. The waveform data were transferred to a computer, where they were processed via an algorithm that first com- puted a modified binary Fourier transform, then computed the electro-optical transfer function by taking the ratio between the nonzero terms of the discrete Fourier trans- forms of the output and input waveforms. This oork was done by John G. Hagopian and William Eichorn of Goddard Space Flight Center. For further information, Cir- cle 156 on the TSP Request Card. GSC-13349 ~JAutomatic Rejection of Multimode Laser Pulses Characteristic modulation is detected, enabling the rejection of multimode signals. NASA's Jet Propulsion Laboratory, Pasadena, California A monitoring circuit senses multiple longitudinal mode oscillation of a trans- versely excited, atmospheric-pressure (TEA) CO2 laser. This facility was speci- fically developed for inclusion into a co- herent detection laser radar (LiDAR) sys- tem. However, the circuit described would be of use in any experiment where it is desirable to record data only when the laser operates in a single longitudinal 24 mode. In the case of the LlDAR applica- tion for which this device was originally conceived, received signals, derived from multimode transmitted pulses, exhibit a much broader frequency bandwidth than that of the receiver electronics in a typical heterodyne (coherent) detection configura- tion. They, therefore, contribute little or nothing to the detected signal. Although control circuitry usually enforces single' mode operation, the subject laser can oc- caSionally revert to multimode operation. When this occurs, the monitoring circuit causes the data-acquisition system to ig- nore the incoming signal , thereby optimiz- ing the signal-to-noise ratio in a Signal averaging situation. Multimode oscillation causes the laser pulse to be strongly amplitude-modulated at the frequency of separation between the NASA Tech Briefs, December 1991 1 2 3 A APPLICATIONS EXAMPLE. While the following example is for air- craft, it could apply to any air, land, sea or space system. SEQUENCE 0 E: The four-pushbutton display reads "ENGI E START," "BAT- TERY OK," '"FUEL OK," OXYGEN OK." The operator selects "ENGINE START." SEQUE CE TWO: The four - pushbutton display now changes to read " ENGINE OK ," "HYDRLC OK ," "POWER OK ,I' "CHECK LlST." The oper- ator selects "CHECK UST." SEQUENCE THREE: The four - pushbutton display now reads "CHECK ICE ," " CHECK FLAPS ," " CHECK BRAKE," "SYSTEM OK ." In this man- ner, the designer can program in as many sequences as required. longitudinal modes. This intermode-sepa- ration frequency is the reciprocal of the period required by light to make one round trip within the laser cavity, so that the mod- ulation is easily detectable as long as the laser pulse duration exceeds this round- trip period. The monitoring circuit (see fig- ure) senses this modulation and processes it to determine whether the detected data should be rejected. A low-reflectivity beam splitter samples a portion of the subject laser beam and directs it onto an HgCdTe photoresistor. The output of this photoresistor is band- pass-filtered at the intermode-separation frequency (63 M Hz in the original applica- tion). The resultant filtered signal is then amplified and sent to a radio-frequency switch controlled by the laser trigger via a delay circuit. The switch blocks the burst of broadband excitation noise that occurs before the laser pulse and that can trig- ger a false multimode-operation alarm. The switch passes the signal during the time window containing the main part of the laser pulse, then shuts off to block the "tail" of the pulse, which occasionally con- tains modulation that could also trigger a false multimode alarm. After passing through the switch, the signal is enveloP9'letected, amplified, and fed to a comparator. If the signal exceeds a preset value, the comparator sends a pulse to an AND gate. The other input to From PhotOf'lllltOf Rom ...... o---f T_ Amplitude Modulation at the Intermode-Separation Frequency during the laser pulse causes this circuit to suppress the data system trigger. the AND gate is derived from the laser trig- ger, but delayed so as to render it syn- chronous with the output of the com- parator. The AND gate is configured so that if a multi mode laser pulse has been de- tected, then the data system trigger (the output from the AND gate) is inhibited and the multi mode data thus rejected . This work was done by David M. Tratt and Robert T. Menzies of Caltech and Carlos Esproles of Ball Systems for NASA's Jet Propulsion Laboratory. For further information, Circle 109 on the TSP Request Card. NPO-17777 ... ~ Two-Period Gratings for Surface-Emitting Lasers More light is reflected back into the lasers. NASA's Jet Propulsion Laboratory, Pasadena, California Solid-state lasers of the type that emit light perpendicularly to their broad sur- faces can be made more efficient by use of two-period surface diffraction gratings. Heretofore, a typical device of this type has been made with two gratings, both of which have a single spatial period equal to the wavelength of the light. couple out only a small fraction. It is dif- ficult to fabricate a Single-period grating in such a way as to attain the desired ratio of output coupling to reflection; as a result, the proportion coupled out is too large, the proportion reflected back in is too small, and consequently the single-period de- vices tend to exhibit low efficiencies and In such a device with a single-period grating, the same gratings serve both to couple light out from the surface and to reflect light back into the laser resonator (see Figure 1). To obtain high efficiency and low threshold current, it is necessary to reflect most of the light back inside and Figure 2. Grating Surfaces That Have Two Spatial Periods can be tai- lored to obtain the desired propor- tions of output cou- pling and inward re- flection . Figure 1. In a Surface-Emitting laser With Single-Period Gratings, the same gratings both couple light out and reflect light back inside. 26 - II-spatial Perlod = 1 Wavelength Spatial Period = Spatial Period = Half Wavelength / FUliwavelength ~ H 'or lr Ii rr.:t t:!J FIRST VERSION Spatial Period Between Alternate Average Spatial Period = Spatial Period = Identical Ridge. = Half Wavelength Half Wavelength ........... Full Wavelength I ............. 1 / ;'rlf] JHt----J r \. Reflected Light Reflected Light SECOND VERSION NASA Tech Briefs, December 1991 WE.lUST CUTYOUR MASS STORAGE PROBLEMS DOWN TO SIZE. Imagine taking all the data from 412 industry-standard 3490E written cartridges and putting them on just one cartridge. That's like shrinking the entire red area above into the little gray box in the corner. But that's the extraordinary increase in data density you can achieve with the new Ampex TeraStore'" system. With it, you can store a full terabyte of data in just six cartridges a little larger than this page. Or, with our new TeraAccess™ Automated Cartridge Library, you can store 6.4 terabytes in just 21 square feet- a volumetric efficiency of more than 100:1 over any other robotic system on the market today. And both systems deliver an unprecedented transfer rate ofl5 Mbytes per second sustained, 20 Mbytes per second burst. The simple fact is, TeraStore and TeraAccess can help you cut the mass storage problems of the 90's down to size today. For more information, call or write us today. Or see these revolution- ary systems in person at Booth 417 at the NASA Technology 2001 Show in San Jose from December 3-5, 1991. AMPEX Circle Reader Action No. 595 Ampex Data Systems Corporation 401 nroadllKJy, MS 3·23 Redwood Dty, CA 94063-3199 (800) 562·3621 Q 1991 Ampex Corporallon high threshold currents. Figure 2 illustrates two versions of a rec- tangular two-period-grating surface-emit- ting laser. In the first version, one of the gratings is divided into two adjacent parts: an output part in which the spatial period is equal to or slightly less than the wave- length and a reflecting part in which the spatial period is half the wavelength. By separating the output-coupling portion from the reflecting portion, one can tailor each independently of the other to opti- mize the structure of the device to obtain low threshold current. This device has been demonstrated to give a 40 percent reduc- tion in threshold current compared to con- ventional devices. In the second version, the grating on the reflecting (only) surface has a spatial period of half the wavelength, while the grating on the output surface has a single pattern characterized by two spatial peri- ods. The average distance between adja- cent ridges is half the wavelength. The even- and odd-numbered ridges have slightly different shapes and/or are dis- placed toward or away from each other by a small fraction of the wavelength; this amounts to a slight perturbation in the half- wavelength pattern, with a spatial period equal to the full wavelength. The strength of the output coupling from this grating increases with the amount of full-wave- length perturbation from the half-wave- length pattern. The same principle should also be ap- plicable to an annular-Bragg-reflector-grat- ing surface-emitting laser described in NASA Tech Briefs Vol. 14, No. 10 (1990), page 20 (NPO-17912). In this case, the annular grating would be divided into two parts: an inner first-order grating (with radi- al period =: half the wavelength) for reflec- tion and an outer second-order grating (with radial period =: the wavelength) for output coupling. This work was done by Robert J. Lang of Galtech for NASA's Jet Propulsion Laboratory. For further information, Cir- cle 131 on the TSP Request Gard. This invention is owned by NASA, and a patent application has been filed. In- quiries concerning nonexclusive or ex- clusive license for its commercial develorr ment should be addressed to the Patent Counsel, NASA Resident Office-JPL [see page 20). Refer to NPO-18054. ~~ Rugged Direct-Current Transducer The solid core withstands mechanical and thermal shocks. NASA's Jet Propulsion Laboratory, Pasadena, California A direct-current transducer withstands thermal and mechanical shocks. It oper- ates from a single, nominally 15-V power supply and is nearly insensitive to both large variations in temperature and varia- tions of as much as ±5 V in the supply voltage. Its output voltage is a highly linear function of the sensed current, with a full- scale value of about 3 Vdc and an offset of about 0.1 Vdc at 0 sensed current. The ruggedness of the transducer is due in large part to the novel magnetic core, which is machined from a solid block of a nickelliron high-permeability, low-hyster- esis alloy. This kind of core can withstand more mechanical and thermal abuse than can the tape-wound and sintered cores used in older transducers. The core in- cludes mounting tabs and a gap that ac- commodates a Hall-effect sensor (see Fig- ure 1). The wire carrying the current to be sensed is wrapped around part of the core. The Hall-effect sensor is connected to an instrumentation amplifier (see Figure 2). This sensor puts out a voltage propor- tional to the current to be sensed and to the constant current Ie that is supplied to it. Ie is generated by part of the instrumen- tation amplifier; namely, the combination of Zener diode CR2, constant-current diode CR1, and operational amplifier UA, which is part of a quad operational amplifier that also includes operational amplifiers UB' Uc' and UD. The output voltage VH from the Hail-ef- fect sensor is fed to UB and Uc. The out- puts of UB and Uc are fed to UD, which serves as the output amplifier. Resistor R13 is selected to provide the desired out- put-voltage offset, and R14 is selected in conjunction with the number of turns in the coil on the core to provide the desired gain. Three units were built, 1 turn for 20 A, 2 turns for 10 A, and 20 turns for 1 A. 28 This work was done by Colonel W. T. McLyman of Galtech for NASA's Jet Pro- pulsion Laboratory. For further informa- tion, Circle 92 on the TSP Request Gard. In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be ad- dressed to Edward Ansell Director of Patents and Licensing Mail Stop 305-6 California Institute of Technology 1201 East California Boulevard Pasadena, CA 91125 Refer to NPO-17957, volume and number of this NASA Tech Briefs issue, and the page number. r~, ___ ~---1 : ' , , I I • I I -II-e:-.::.,.II-----· .. ~ _____l ~O.!O\tI Figure 1. The Magnetic Core is machined from a solid block of high-permeability nickel/ iron alloy. Cl: O.l.,F, 50 V C2: 0.1 ~F, 50 V CR1 : lN5295 A1 : l6.9K Ag: lOOK RNC60J R,a: 196K RNC60J A,, : 158t< RNC60J R, 2: 324K RNC60J U: lM 124 Quad Operational Amplifier +15V Hall·Elfecl Sentor CirCUit - -IC F Wile" - +IC CR2: 1 N4566A A2: 3.16K R3=200Q R,.: 487 Q As: 1.43K Ae: lOOK A7: lOOK RNC60J AS: 100K RNCOOJ + 15 Y Model GH..:IO ----: + + Hall GeneralOr YH >-_____ ~ lor Equl~alent) - - -L.----, __ ~___I R,~ Between LOOK and 10.0K (To 8e Selecled) R14: Selween 10.00K and 750K (To Be Selected To External Inslrument for 14 Monllortng Figure 2. The Transducer Circuit excites a Hall-effect sensor and puts out a voltage that varies linearly with the sensed current. NASA Tech Briefs, December 1991 Mathcad 3.0 gives you the only kind of power you need. Try new Mathcad 3.0 for yourself with a free demo disk. Mathcad gives you a com- plete set of tools to solve vir- tually any math or technical problem. It handles everyday functions like sums, products, tables, and scatter plots. 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Circle Reader Action No. 682 Electronic Systems Hardware, Techniques, and Processes 36 Wideband Phase-Locked Angle Modulator Computer Programs 30 Altering Interline Transfer in a CCO To Reduce Saturation 31 Knowledge-Based Flight- Status Monitor 48 Estimating Rain Attenuation in Satellite Communication Links 48 Neural-Network Simulator Altering Interline Transfer in a CCO To Reduce Saturation Charges accumulated during part of a frame period would be dumped. NASA's Jet Propulsion Laboratory, Pasadena, California In a proposed interline-transfer timing scheme for a charge-coupled·device (ceO) video imaging array, the charges ac- cumulated during some fraction of a frame period would be read out in the usual way, while the charges accumulated during the remaining fraction of a frame period would be swept out and dumped to prevent over- loading and saturation in intensely illumi- nated photosites. The excess charges would be swept out at the highest possi- ble rate, while the charges used for imag- ing would be read out at a rate that was lower but that was nevertheless the high- est rate that would provide complete trans- fer of charge on the array and that could be handled by subsequent signal-proc- essing equipment. In the typical operation of an interline ceo, the charges accumulated in the pho- tosites (picture elements) are periodically transferred from rows of photosites into columns of optically masked ceo transfer gates. These charges are sequentially stepped along the columns into a row shift register so that information on the image can be extracted as a series of charges in rows of picture elements. In interlaced scanning (to which the proposed scheme applies), the complete scene is read out in frames, each of which consists of two fields. The first field consists of the odd- numbered lines; the second, of the even- numbered lines. Figure 1 illustrates two of several ver- sions of the proposed timing scheme. Let F denote the frame period, and let the zero of time be denoted as the leading edge of a pulse that would mark the beginning of readout of the odd field . A similar pulse would mark the be9inning of readout of the even field at Ff2. An interval of Fj4 would be devoted to the readout of each field. In the first version of the timing scheme, the charges would be swept out of the odd (or even) field at some time dur- ing the interval of Fj4 between the end of readout of that field and the beginning of readout of the subsequent even (or odd) field . In the second version, the charges would be swept out of each field at some time during the interval of Fj4 that would 30 ~Fleld Perloo ____ -,-_-:c'n Even-Field Period Readout of Sweepoul of n - Odd Rows Odd Rows ! ~miiiiiillirfillIrllllllIlllll~ FIRST VERSION go E i= Readout of Odd Rows ~--------~~~~ Sweepout 01 Readout of Even Rows Even Ron ---... .. ~\ SECOND ~ { ~ Sweepout of Readout of VERSION I ~ e'<'en Rows n Even Rows J -----' "1/_ ~ ·j lrimiiii __ L ___ 1 I- __ I F14 Time FI2 3Ft. Figure 1. These Timing Signals for Interline Transfer of charges in a CCD would be used in two versions of the proposed scheme. In still other versions, the frame period, F, could be broken into intervals of FIB or less. Figure 2. This Control System would vary the time of beginning of the last sweepout period for each field in such a way as to prevent or reduce the incidence of both overexposure and underexposure. immediately precede the readout of that field . In both versions, the last sweepout of a field during each frame period would have to commence no later than one sweepout period before the beginning of the readout to follow. Provided that each such last sweepout occurred as late as possible and that the sweepout period was much shorter than Fj4, the first version could dispose of as much as 1/4 the charges integrated during the frame period, F, allowing an overexposure of 4/3 the saturation intensity. The second ver- sion could allow a much greater overex- posure because it would limit the charge- integration time to the time required to gain access to the photodetectors and sweep out the excess charges. Figure 2 illustrates a scheme to control the time of the beginning of the last sweep- out in response to the amount and loca- tion of overload in a scene. The readout charges would be passed from the ceo to a video detector and line clamp. The detector would filter the noise component out of the signal, while the clamp would fix the signal at a minimum dc reference level. A voltage comparator would indicate any picture elements in which the charge exceeded a reference level just below the saturation level of the ceO. NASA Tech Briefs, December 1991 The output of the comparator would be integrated over a frame period to produce a signal indicative of the fraction of the CCD array that was saturated, if any. The integration could be weighted to empha- size the center or any other portion of the array. The output of the integrator would be applied to a pair of hysteretic voltage comparators, which would define a range of acceptable exposure. The comparators would drive the " up" and "down" control lines of a bidirectional counter, the output of which would determine the beginning of the last sweepout period. If overex- posure were signaled, the counter would decrement by one count per frame until the exposure was sufficiently short or un- til the minimum integration time was reached. If underexposure were signaled, the counter would increment one count per frame to boost the signal. When cor- rect exposure was signaled, no counting would occur. This work was done by Edward M. Rentsch of General Electric Co. for NASA's Jet Propulsion Laboratory. For further information, Circle 163 on the TSP Request Card. NPO-17935 Knowledge-Based FI ight·Status Monitor Telemetered data from advanced aircraft would be processed automatically to detect failures. Ames Research Center, Moffett Field, California A conceptual digital computing system is intended to monitor and interpret tele- metered data on the health and status of a complicated avionic system in an ad- vanced experimental aircraft. When fully developed, the monitor would be pro- grammed with expert-system software to interpret the data in real time. The soft- ware would include a rule-based model of the failure-management system of the aircraft that would process fault-indicating signals from the avionic system to give timely advice to human operators in the mission-control room on the ground. A pro- totype of the expert-system software was developed via the MUSE system, which is a software toolkit for the development of real-time applications of artificial intelligence. In the flight-status monitor (see Figure 1), the telemetered data would be trans- lated into digital words, then fed into the NASA Tech Briefs, December 1991 Rack Your Brain. Elastomeric Shock Mounts PrOVide controlled shock and vibration levels. Two Inches of sway space allows Improved air flow over foam captivated systems Molded-In Tongue-In- groove Gasketed Parting line Resil ient polyethylene shell absorbs brutal Impact without deformation. Superior to metal parting lines. Patented "lid lock" Prevents lid separation from base on impact. MInimizes stress on hardware. Rotational 11"r..-__ Molding For extra strength where Impact most often occurs. corners and edges are 10·20% thicker than flat walls. One piece stress·free molded lid and base. No fragile aluminum to bend and leak. Trust your sensitive electronic 'brain' to a Hardigg 19" rack. To find out more about 19· rackmount shipping containers, call for your free brochure: Choosing the Proper Shipping Container - A Gu ide to Container Size and Cushioning 1-800-843-2687 ", TM HARDIGG™ CASES HARD/GG A Division 0' Hsrdigg Industries, Inc_ 393 N. Main Street PD Box 201 South Deerfield, MA 01373 (413)665-2163 FAX: (413) 665-8061 Circle Re.der Action No. 492 expert system, which would determine whether any changes in the data had oc- curred since the previous sample. The ex- pert system would evaluate the effects of any such changes. A data-driven fore- ground loop would determine the state of the system and inform the user - in this case the systems engineer - of the changes and consequences. If a failure were detected, a warning or caution would be issued along with corrective or emer- gency procedures, when required. As a part of this evaluation, the expert system might ask the user questions on the state of the aircraft. A background task would allow the user to query the monitor for in- formation on the state of the flight-control system or the rationale used to reach its conclusions. The expert system would in- terrupt the background task, when neces- sary, to evaluate new data, but if the state of the flight-control system had not changed between inputs, the expert system would not reevaluate that state. The knowledge base would contain both rules specific to the aircraft and metarules, which are the rules that the systems en- gineer uses to determine the correct re- sponse to a failure. The flight-status mon- itor would use these rules to model the failure-detection subsystem of the flight- control system and compare the modeled state with that of the aircraft. If the conclu- sions of the monitor disagreed with the state of the aircraft, a warning would be issued, and the user could ask the system to resolve the conflict. The conflict would be resolved as part of the background task so as not to interfere with the higher-priority task of evaluating the aircraft data as they were received. The prototype software consists of sev- eral separate expert systems, each with its own inference mechanism. The inter- nal structure of the flight-status monitor, as represented in the software, is shown in Figure 2. The inference mechanisms involve predominantly forward-chaining, data-driven processes. The aircraft sensor- and-failure-management (ASFM) expert system uses a forward-chaining logic mechanism to model the failure-manage- ment system of the aircraft and to deduce conditions of concern or danger based on the failure-indicator information. A meta- monitor expert system deduces situations of concern based on knowledge of de- ductions from the ASFM expert system and the failure-management system. The situations of concern deduced by the metamonitor are analyzed by a fault-iso- lation expert system that deduces prob- able causes of conflicts, recommends cor- rective actions, and issues warnings. 31 ~. . . '/ I. • . . '. . ... . . -, - --c . , New Event Timing Controller The latest Innovation from Guide Technology is the GT 401 Real-TIme Event Controller Now you can easily control and monitor external events. An on-board Intel 8OS1 controller handles real-time processing Without burdening your PC with timing tasks. The GT 401 IS a precision tool, with 50,000 times the resolution of the DOS clock in your PC. o TIming ResolutJon 1 microsecond o Four channels can be used as pulse outputs or time-tagging Inputs with 400 nanosec. resolution. o Three 10MHz counter/timers can be synchron- ized to the real-time clock. o Various time formats implemented in hardware. o Entirely software-controlled , using software included free with each GT 401 board . . 16T 401 Event Timing Controller ........................ $995 100 Low-Cost 100MHz Universal Counter ... $995 New DataCommander~ Serial Port Multi- plexers operate independently of your host PC. Achieve high-speed data collection and communi- cations from many sources without taxing your PC's main processor. On-board 2S0K memory buffer (upgradeable to 4MB) and on-board micro- processor make the DataCommander~ a powerful acquisition tool. Your PC can be executing other tasks while the unit spools up to 4MB of Incoming data. Ports on these units use DB 2S-pin connectors. Custom configurations are available fea- turing RS-422 (long distance) lines, RJ-ll / RJ-4S connectors, and parallel port options. I OCOM 600 6-Port RS-232 DataCommander'" ....... $995 I OCOM 1000 10-Port RS-232 DataCommander'" ... $1495 I OCOM 1610 16-Port RS-232 DataCommander" ... $1995 Arnet Intelligent Serial Boards Your PC is no longer limited to 2 serial portsl Multi-port serial boards from Arnet let your DOS- based PC support up to 66 serial ports. All Arnet boards come complete with DOS Driver Software and an external 2S-pin 'D' connector box. o Intelligent units offer on-board 80186 micro- processor and dual-ported RAM buffer. o Free DOS driver software lets DOS recognize up to 66 COM: ports o SurgeBlock~ on all ports protects your PC from killer voltage spikes. o 'Rock-Solid' lifetime Warranty. t COMH 104 4-Port Intell igent Serial Board ....... $595 t COMH 108 8-Port Intelligent Serial Board ....... $995 I COMH 116 16-Port Intelligent Serial Board ... $1895 13Z 32-Port Intelligent Serial Board o E B P 00 CT SE PC Products lor SCientists & Engineers 1-800-"86-8800 Toll-Free Hotline • Free Application Engineering ~ lZl SOFTWARE NEW Snap-Master Soltware : Data Acquisition for Windows Discover Snap-Master - the only Windows- based data acquisition and analysis software to achieve high-speed. real-time data acquisition with multiple simultaneous AID boards. Snap-Master lets you define your own custom instruments using icons and easy-to-understand flow charts. A pre-defined database of sensors is integrated with the data acquisition system. I HOS ZOO Snap-Master Acquisition Module ...... $995 #HOS Zl 0 Snap-Master Analysis Module .. ........ $495 LabWindows 2.0 Menu-Driven Instrumentation Soltware With LabWindows 2.0 you get the best of both worlds: the ease·ol-use 01 a menu-driven package combined with the flexibility possible only when you write your own code. The menu interface takes you step-by-step through the process of configuring the data acquisition, analYSiS, and display portions of your system. It then compiles your setup into C or QuiclcBASIC code. This IS the easiest way to create data acquisition and analysis programs! I NIS 473 LabWindows 2.0 Software ...... .. ........ $695 I NIS 474 LabWindows Advanced Analysis ....... $195 INIS 475 LabWin. Acquis. + Analysis (both) .. $1395 PC SYSTEMS Elma Rack-Mount Keyboards II you use a standard keyboard with your rack- mounted system, you know what a nuisance and a hazard it can be. These new industrial key- boards are designed to fit easily into any EIA 19' rack. Rugged and reliable, these keyboards are made in the U.S.A. by a Swiss company and demonstrate classic Swiss craftsmanship. o Full 10 l-key layout. o Full-travel construction with excellent tactile leel lor touch-typing . o OIX 3010 keyboard is set in a drawer (not shown). o OIX 6010 keyboard slides out w/ a locking door. o Occupies only 1 rack space (1.7S· high). I OIX 3010 Rack-Mount Keyboard wN-lrist Rest $295 I OIX 6010 Rack-Mount Industrial Keyboard .... $3115 NEW! Rack-Mount PC's with built-in VGA Monitors CyberResearch carries the broadest line of rack- mount and industrial computers. Now we've added new models with built-in VGA monitors. You get a compact unit with '386 power and a color display. o Built-In 10' VGA Color Monitor & VGA Card o 4 Megabytes of RAM (2MB for the VAC 386-16S) o Enhanced 101-Key Keyboard o 1.2 MB Floppy Drive (or 1.44/3.S' if preferred) o 2 Serial RS-232 Ports & 1 Parallel Printer Port o DOS 3.3 Software (or DOS S.O, il prelerred) IVHC 31&-16S VGA Rack·MI. PC, 80386sx, 16MHz 515 IVHC 386-33 VGA Rack-Mt. PC, 80386, 33MHz..$4115 IVHC 486·33E VGA Rack-Mt. EISA, '486, 33MHz..$8115 1 MHz 12-Bit ComputerScope Offers Unique Advantages The ComputerScope High-Speed Data Acquisition System from RC Electronics Includes a 1 MHz NO board , a BNC Terminal Panel , and Digital Oscilloscope Software. A specially-designed series of software modules provides tightly- integrated real-time performance Call us for detailed information on the EGAA software system. • Sixteen 12-blt Analog Input Channels. • 64K-Sample Buffer for Maximum Performance. • Supports Pretriggering Sample Mode. • Comes complete with ComputerScope Software. t lNST 601 1 MHz ComputerScope System ..... $2495 t lNST 605 EGAA Multi-Tasking Software ......... $795 I INST 615 Electronic Chart Recorder & AutoDisk Data Logging Software Modules ... $1195 ------ Directly Interface to Any TYpe of Transducer Signal When you need to measure several types of inputs, but your budget won't support the high cost of signal conditioning modules, there is only one solution: The new UPC series of Direct Sensor Input Cards from Validyne Engineering" • Directly connects to Thermocouples, Strain Gauges, RTD 's, LVDT's , RVDT's , Voltage Sources, and Resistance Devices. • Sixteen Analog Inputs with 14-Bit Resolution. • Data Acquisition at up to 20,000 samples/sec. • Perfect for Portable PC DAS Systems. • Comes complete with Easy Sense Software, Software Drivers, and a Screw Terminal Panel. I UPC 601 20KHz Direct Sensor Input Card .. ..... $1795 808 20KHz AID with 2 D/A's & 16 DIO's .$2395 Berry Fast: 200 KHz for just $a95 from Strawberry Tree The new WorkMate data acquisition board combines ease-of-use With blinding speed . Entirely software configured and controlled , the new WMPC 200 makes data acquisition on a PC simple, without sacrificing performance. Each WorkMate board comes with a free copy of Quick- LogPC, an icon-driven data acquisition program. For the ultimate in easy-ta-use NO software, WorkBench PC combines an icon-driven interface with powerful acquisition & analysis capabilities. I WMPC 200 WorkMate 200KHz AID Board ....... 95 I FlPC 1000 16-Channel, lMHz AID Board ...... $1995 I FLPC /j00 flash 1 MHz/400KHz AID Board .. $1295 050 SAVE 30% OR MORE With Melrabyte-Compatibles Our new series of CYDAS Metrabyte-Compatible data acquisition and control boards offer both much lower cost and valuable added features; yet they maintain guaranteed 100% Metrabyte-Compatibility. Metrabyte Cyber Our Part I Price Price #CYOAS 16F 100KHz, 16-Ch. AID Bd. $1165 SIS. , CYOAS 16 50KHz, 16-Ch. AID Bd. $999 $7119 I CYOAS 8 20KHz, 8-Chan. AID Bd. $425 $219 ICYOAS 8PS 20KHz AID w/Prog. Gain $599 $349 I CYOAC 02 2-Chan. 12-Bit D/A Board $299 I CYOOA 06 6-Chan. 12-Bit D/A Board $650 ICYOIO 24 24-Ch. (PIO-12) TTL I/O $130 #GYOIO 24H 24-Ch. (PIO-24) Dig. I/O $185 #GYCTM 05 5-Ch. CounterlTimer Bd. $325 #CYCTM 10 2 CYCTM 05's on 1 board $650 I CYMUX 16 16-Ch. Multiplexer Panel $399 I CYMUX 32 2 CYMUX 16's on 1 board $798 t CYSSH 04 4-Chan. Simul. Sampling $450 16 16-Ch. Simul. Sampling $1800 Redlake TapeCaster VGA to Video Converter Redlake 's TapeCaster converts VGA screen output to video for applications such as animation and creating training tapes. The TapeCaster is extremely easy to use: no base addresses, no interrupts, no software - just plug and play. • True, precise NTSC or PAL video timing. • Simultaneous VGA and video display. • Composite Video & Y -C (SuperVHS) output for use with equipment ranging from an inexpensive VCR to broadcast-quality professional video. I NTSC 200 TapeCaster - NTSC Video Output ....... $750 I PAL 200 TapeCaster - PAL (Europe) Video Out. ... $750 I NTSC 100 Spectrum-NTSC Video Digitizer and VGA Overlay Controller with software ....... $1650 MOTIDN CONTROL SYSTEM Makes motor control easy. PC-based motion control may seem like science fiction to many people. Here at CyberResearch, it's one of our specialties. It can also cost a lot less than you think. Shown here is our CMCS 222A complete motor control system, which includes: • Technology 80 2-Axis Intelligent Stepping Motor Controller board complete with software. • Oriental Motors High-Torque Stepping Motors, Size 23, 1.8"/Step (QIy 2) • IMS 40V, 3.5A Bipolar Chopper Drivers (QIy 2) • Electrostatics Regulated DC Power Supply • Terminal Panel and Cabling NCMCS 222A High Torque, Dual-Motor, PC-based Stepping Motor Control System .............. $1595 34 E Sl's highly table, transponable Resistance Standards allow routine calibration in the laboratory or in the field. The SRI resistance standards offer 0.005% long- tenn accuracy for most values from In to lOMn. Dekabox DB877 Coaxial Dial and DB62 In-line Decade Resistors provide additional linearity check- ing capability with vinually continuous resistance between o.om and 12Mn at 0.02% accuracy. Call us toll-free (800) 547-1863. In Oregon, (503) 641-4141. EleclfO Scientific Induslries . Inc. 13900 NW Science Park Drive ' Portland. OR 97229 Circle Reader Action No. 625 Circle Reader Action No. 510 Figure 1. The Flight-Status Monitor would alert the flight-systems engineer to the need for corrective action in the event of a failure during flight. Information on Health and Statusr--------. of the Aircraft AJrCfaft $ensor,and- ====~ Failure-Management (ASFM) Expert System • Indicator Rules • Multfple-Elamen,t Indicator Rules • Fllght'System Rules Flight· ~==:::::J System L.:===~> Englneer<;====::J Figure 2. The Internal Structure of the Flight-Status Monitor, as envisioned in its software, includes several different representations of expert-system rules. These expert systems provide detailed information on the status of the aircraft systems and perform a function compa- rable to that of an expert in flight systems. The system-operability expert system uses knowledge of the effectiveness of the system and the detailed data on the status of the system to provide a high-level assessment of the ability of the flight-control system to control the aircraft, com- plete a specific mission, or function in a given mode. This assessment is performed by a backward-chaining mechanism, using hypotheses in an order established by the user. The order of the hypotheses is important because it provides a means forthe expert system to determine priorities; the system uses this knowledge of priorities to determine the highest level at which the system is operable and provides this information to the user. The system-operability rules are also used to establish the worst consequences of any additional failure. This work was done by E. L. Duke of Ames Research Center, J.D. Disbrow of PRC Systems Services, Inc. , and G. F. Butler of the Royal Aerospace Establishment. Further information may be found in NASA TM-1 0171 0 {N90-13995], "A Knowledge Based Flight Status Monitor for Real-Time Application in Digital Avionics Systems." Copies may be purchased {prepayment required] from the National Technical Information Service, Springfield, Virginia 22161, Telephone No. (703) 487-4650. Rush orders may be placed for an extra fee by calling (800) 336-4700. ARC-12712 NASA Tech Briefs, December 1991 Signal creation and analysis enters a new domain: the real world. WaveForm DSpTM closes the loop from lab to math model to the outside world. It is a data acquisition, signal analysis, and waveform creation tool, all in an easy-ta-use Microsoft Windows~ based program. Waveforms can be acquired or created many different ways. Draw them, build them with the library, input math formulas , share data from programs like Excel~, or even get a real signal from a digitizing storage oscilloscope. WaveForm DSP also has powerful math functions for combining, concatenating and O Copyright 1992 Wavetek Corporation. Wavetek and Waveform IN' are trademarIcs 01 Wavetek Corporation. manipulating signals, with options for signal filtering and much more. Accuracy is assured because calculations are done in double precision (64 bit) math. The signals you create can be used to drive an arbitrary function generator capable of reproducing any imaginable waveform. Or they can be out- put to printers, plotters, or saved as files for other applications. Multiple windows can be open at once, and they can all be interactive. Imagine being able to change a waveform in the frequency domain and see MIcrosoft. Microsoft Wmdows and MIcrosoIt Exce\ are trademarks of MIcrosoIt Corporat\oo. Circle Reader Action No. 448 For Literature ('Ir.-I., R.,~rf.,r A,..tinn Nn 44Q ~nr Ii nAmn the results in a time domain plot on the same screen - with just the click of a mouse. Or change a signal going to a test and see a graphic display of the analyzed results. If you haven't been comfortable with digital signal processing before, you will be now. And if you never thought of using arbitrary generators before, get ready for a whole new spectrum of possibilities. To try WaveForm DSP, call 1-800-223-9885. Wideband Phase-Locked Angle Modulator The modulator can be designed independently of the phase-locked loop. NASA's Jet Propulsion Laboratory, Pasadena, California A modified configuration for a phase- locked angle modulator circuit makes it possible to design the filters in the mod- ulating portion of the circuit independent· Iy of the filter in the phase-locked-loop por- tion (the "loop filter"). The bandwidth of the phase- or frequency-modulated output is not limited by the low-pass nature of the loop filter, as it is in a typical conventional phase-locked angle modulator. The figure illustrates the conventional and modified phase-locked angle modula- tors. In the conventional circuit, the phase- or frequency-modulating signal, whichever the case may be, is applied at one of the two baseband positions of the feedback arm of the phase-locked loop. These are, respectively, the position immediately pre- ceding or the position immediately follow- ing the loop filter. In the modified circuit, the modulating signal is applied through modulation filters to both baseband posi- tions, so that the design of the modulator can be freed of the constraints that would otherwise be imposed by ' the loop filter. An analYSis of the transfer functions of the modified circuit shows that an appro- Reference Oscillator Input Phase- Modulating Signal Output .... --------' priate choice of the mod.dation filters makes the output phase or frequency modulation independent of the transfer function of the loop filter. For phase modulation, this choice is P(s) = s/KcJlarization signatures can be saved in either a PICT format or a text file contain- ing A:>stScript commands and can be printed on any QuickDraw output device. The associated Stokes matrices can be stored in a text file. The only computers on which Mac- Multiview can be executed are those of the Macintosh II family that are equipped with 8-bit video (gray shades or color). The program also requires a minimum con- figuration of System 6.0, Finder 6.1, and 1 megabyte of memory. Macintosh Pro- grammer's Workshop and Macintosh Pro- grammer's Workshop C (version 3.0) are required for recompiling and relinking. The program is written in C and was developed in 1989. This program was written by Lynne Norikane and Howard Zebker of Caltech for NASA's Jet Propulsion Laboratory. For further information, Circle 108 on the TSP Request Card. NPQ-18048 Calculating Thermophysical Properties of 12 Fluids Properties are expressed via equations of state. MIPROPS is a set of computer pro- grams that gives the thermophysical and transport properties of selected flu ids. Although these programs are written in FORTRAN 77 for implementation on mi- crocomputers, they are direct translations of interactive FORTRAN IV programs that were originally developed for large main- frame computers. MIPROPS calculates the properties of fluids in both the liquid and vapor states over a wide range of temperatures and pressures. The fluids in- cluded are helium, hydrogen, nitrogen, ox- ygen, argon, nitrogen trifluoride, methane, ethylene, ethane, propane, isobutane, and normal butane. All of the programs except the helium program incorporate the same equation of state. A separate program was necessary for helium, as the mathematical model for the thermodynamic surface of helium is of a different form. The input variables are any two of pressure, density, or temper- ature for the single-phase regions, and either pressure or temperature for the saturated-liquid or saturated-vapor states. The output is pressure, density, tempera- ture, internal energy, enthalpy, entropy, specific heat capacities, and speed of sound. In addition, viscosity, thermal con- ductivity, and dielectric constants are calculated for most of the fluids. The user can select either a single point or a table of output values for a specified tempera- ture range, and can display the data in either engineering or metric units. This machine-independent FORTRAN 77 program was implemented on an IBM PC XT computer with an MS-DOS 3.21 operating system. It has a memory re- quirement of approximately 100K bytes. The program was developed in 1986. This program 'MiS written by T. F Cleghorn and R. D. McCarty of Johnson Space Center. For further information, Circle 88 on the TSP Request Card. MSC-21664 o MeChanics Program Calibrates Strain Gauges Time required for acceptance tests of hardware is reduced. Strain data are required for the proces- Sing of such pieces of aerospace hard- ware as the three bolts used to attach the external fuel tank to the Space Shuttle or- biter. The acquisition of these data has traditionally required a time-consuming and inefficient manual process that in- cludes setting up a strain-gauge indicator, reading and recording strain data, and tabulating and plotting strain data versus a load or other parameter. The time and personnel requirements of the traditional method led researchers to develop a com- puter program to increase the efficiency of the acceptance test performed on these bolts. The data-acquisition system reads the output from a Wheatstone full·bridge strain- gauge circuit and calculates strain by use of the shunt calibration technique. The pro- gram nearly instantaneously tabulates and plots strain data against load-cell outputs, thus saving hours of manual work per test run. The comparative speed and efficien- cy of this technique was empirically pro- ven by a calibration test of one of the ex- ternal-tank/orbiter attachment bolts. The use of the program dramatically reduced personnel and time requirements. Re- NASA Tech Briefs, December 1991 Finally, get perform-ance, flexibility, and ease of use in a single data acquisition package. Without programming. Without compromising. Awaken your 386/486. VIEWDAC lets you ex- plore the full power of your 386/386SX/486. Become more productive with less effort. Acquire, analyze, and graph huge arrays. Run multiple acquisitions concurrently. Even set up new applications while running others. VIEWDACls user- friendly windowing environment lets you do it all with ease. User power that's not just for the power user. With VIEWDAC, you donlt have to write code to get performance. Integrated applications with custom front panels, simultaneous real-time calculations and display, and user input are just mouse clicks away. Your wake-up call: 1-800-348-0033. Data acquisition for your 386/486 is no longer a dream. Itls real. Itls VIEWDAC. Call today. Key VI EWDAC acquisition tools: • Vary acquisition rates on any channel during a run • Mix high- and low-speed acquisition over any combina- tion of channels in the same application • Enjoy built-in specialized acquisition and control tasks (thermocouples, PID control, pulse output, etc.) • Use up to 20 acquisition boards simultaneously - even with all channels active • Select hardware from a broad range of suppliers • GPIB and RS-232 ' KeyVlEWDAC analysis/graphics tools: • Time and frequency domain processing • Arbitrary wave form generation • Curve fitting , • Basic statistical reporting • Interactive graphics, including bar charts Be sure to ask about our other software products: ASYS'P", ASYSTANT®, and EASYES'f®. Thirty-day money-back guarantee on all Keithley Asyst software. KEITHLEY ASYST Asyst Software Technologies, Inc . • A subsidiary of Keithley Instruments. Inc . • 100 Corporate Woods · Rochester, NY 14623 • 1·8()()'348-oo33 • 71&-272·0070 • FAX: 71&-272·0073. VIEWDAC. A VSf, ASVSfANT. and EASYESf are trademarks of Asyst Software Technologies, Inc. Copyright e A yst Software Technologies. Inc. 1990 386, 386SX and 486 are trademarks of Intel Corporation Circle Reader Action No. 44'1 Quiet! Listen to what they're saying! I put 8 oz. Tufoil in my wife's 1977 Mercury and didn't teU her. A week later she asked me why her car was idling faster and had more pep. I told her about the Tufoil and she was pleased. (8.8. Az) Recently while driving, my car lost oil pressure due to a defective oil plug. The service station owner stated the car's engine was saved from damage due to your fme pro- duct. Thanks! (G.R. New Jersey) You have invented a masterpiece! Your product surpasses aU my ex- pectations! (C.B. New York) One 8 oz. - $ 17.75 (ship. incl.) Two 8 oz. - 29.00 (ship. incl.) 1 Quart - 38.95 (ship. incl.) 1 Gallon - 131.00 (ship. incl.) 1-800-922-0075 ORDER TODAY ------------~ Fluoramlcs, Inc. N1291 .:J 18 Industrial Avenue Mahwah, NJ 07430 My check or money order for $ __ is enctosad. Charge my credil card: o Am. Express O Masler Card 0 Visa Card No. _________ _ Exp. Dale _________ _ Phone No. _________ _ Name Address C;ty p Slale _____ Zip ____ _ (N.J. residents please edd 7% sales lax). ..... -------------~ 54 Circle Reader Action No. 364 searchers verified the accuracy and in- tegrity of the program by comparing its output strain data to those of a calibrated strain-gauge indicator formerly used in the manual method. The program can also be modified to acquire strain data for other specimens wherever full-bridge strain- gauge circuits are used. The program was developed in 1985 on a Hewlett Packard 9845B Microcomputer. It is written in HP BASIC and is available as a listing only. This program was written by Gary D. Okazaki of Rockwell International Corp. for Johnson Space Center. For further infor- mation, Circle 38 on the TSP Request Card. MSC-21399 Integrated Analysis Capability Program This modular software system facilitates multidisciplinary analyses of structures and other systems. The Integrated Analysis Capability (lAC) software system is intended to provide a highly effective, interactive analysis tool for the integrated design of large structures. With the goal of supporting the unique needs of engineering analysis groups con- cerned with interdisciplinary problems, lAC was developed to serve as a software in- terface between computer programs from the fields of structures, thermodynamics, controls, and the dynamics of systems on the one hand and an executive software system and data base on the other hand to yield a highly efficient multi-disciplinary system. Special attention is given to such users' requirements as handling data and online assistance with operational features and the ability to add new modules of the user's choice at a future date. lAC contains an executive software sys- tem, a data base, general software utilities, interfaces to various engineering pro- grams, and a software framework for build- ing interfaces to other programs. lAC has shown itself to be effective in the auto- matic transfer of data among analysis programs. lAC 2.5, deSigned to be com- patible as far as possible with level 1.5, contains a major upgrade in executive and data-base management system capabili- ties and includes interfaces to enable an- alyses of thermal problems, structures, optics, and the dynamics of control inter- actions. The lAC software system is modular: (1) The executive module contains an input command processor, an extensive data- management system, and driver code to execute the application modules. (2) Technical modules provide "stand-alone" computational capability as well as sup- port for various solution paths or coupled analyses. (3) Graphics and model-genera- tion interfaces are supplied for building and viewing models. Advanced graphics cap- abilities are provided within such analysis modules as INCA and NASTRAN. (4) In- terface modules provide for the required flow of data between lAC and other modules. (5) User modules can be ar- bitrary executable programs or job-control- language procedures with no predefined relatfonship to lAC. (6) Special-purpose modules are included: for example, MIMIC (Model Integration via Mesh Interpolation Coefficients), which transforms field values from one model to another; LINK, which simplifies incorporation of user-specific modules into lAC modules; and DATAPAC, a statistical-analysis package of the Na- tional Institute of Standards and Tech- nology (formerly, the National Bureau of Standards). The lAC data base contains structured files that provide a common basis for com- munication between modules and the ex- ecutive system and can contain such un- structured files as NASTRAN checkpoint files, DISCOS plot files, object code, and the like. The user can define groups of data and relations between them. A full data- manipulation and query system operates with the data base. The current interface modules comprise five groups: 1. Structural Analysis - lAC contains a NASTRAN interface for stand-alone anal- ysis or certain structural/controllthermal combinations. lAC provides enhanced structural capabilities for normal-vibra- tional-mode and static-deformation anal- ysis via special DMAP sequences. lAC 2.5 contains several specialized inter- faces from NASTRAN in support of mUl- tidisciplinary analysis. 2. Thermal Analysis - lAC supports finite- element and finite-difference techniques for steady-state or transient analysis. There are interfaces for the NASTRAN thermal analyzer, SINDAISINFLD, and TRASYS II. There is also an interface be- tween the lAC data base and FEMNET, which converts finite-element structural- analysis models to finite-difference ther- mal-analysis models. 3. System Dynamics - There is a full inter- face between the lAC data-management capability and the DISCOS simulation program, which allows for either non- linear time-domain analysis or linear fre- quency-domain analysis. 4. Control Analysis - Interfaces for the ORACLS, SAMSAN, NBOD2, and INCA programs provide for a wide range of techniques for the analysis and synthe- sis of control systems. Level 2.5 includes EIGEN, which provides the capability to obtain the eigenvalues of systems of large order, and BOPAGE, which provides geometric capabilities and capabilities for finite-element analysis in the case of NASA Tech Briefs, December 1991 a nonlinear material. Also included in lAC level 2.5 is SAMSAN 3.1, an engineering analysis program that contains a general- purpose library of over 600 subroutines for numerical analysis. 5. Graphics - The graphics package IPL0T is included in lAC. IPL0T generates vector displays of tabular data in the form of curves, charts, correlation tables, and the like. Either DI3000 or PLOT-10 graphics software is required for full graphic capability. In addition to these analysis software tools, lAC 2.5 contains an IGES interface, which enables the user to read arbitrary IGES files into an lAC data base and to edit and put out new IGES files. lAC is available by license for 10 years to approved U.S. licensees. The licensed program product includes one set of sup- porting documentation. Additional copies may be purchased separately. lAC is written in FORTRAN 77 and has been implemented on a DEC VAX-series computer operating under VMS. lAC can be executed by multiple concurrent users in batch or interactive mode. The program is structured to enable users to delete easi- ly those program capabilities and "how- to" examples they do not want, to reduce the size of the program. The basic central- memory requirement for lAC is approx- imately 750 KB. The following programs are also available from COSMIC as sepa- rate packages: NASTRAN, SINDAISINFLO, TRASYS II, DISCOS, ORACLS, SAMSAN, NBOD2, and INCA. The development of level 2.5 of lAC was completed in 1989. This program was written by R. G. Vos, 0. L. Beste, and J. Greg. of Boeing Aero- space Corporation and H. P. Frisch of Goddard Space Flight Center. For fur- ther information, Circle 7 on the TSP Re- quest Card. GSC-13341 Mathematics and Information SCiences Library of Subprograms in FORTRAN 77 Subprograms can be called upon as needed to perform specific computations. MATH77, Release 3.17, is a library of 412 FORTRAN 77 subprograms for use in numerical computation. Researchers at the Jet Propulsion Laboratory developed the library to facilitate scientific and engi- neering computation. The wide variety of computers used to perform numerical computation in scien- tific laboratories requires a collection of mathematical subprograms that is porta- ble among a significant number of com- puting environments. The MATH 77 library provides this portability. Subprograms that provide machine and system characteristic parameters make the library operational on any computer system that supports the full FORTRAN 77 standard. The portability of the library and the high quality of its sub- programs and user's manual make MATH77 an extremely versatile and valuable tool for all numerical computation applications. The library contains subprograms that perform such tasks as the computation of speCial functions, the generation of pseu- dorandom numbers, linear least-squares analysis, singular-value analysis, the solu- tion of equations, minimization, curve fit- ting, Hermite cubic interpolation, quadra- ture, ordinary differential equations, finding the roots of polynomials, fast Fourier trans- forms, special arithmetic propagating de- rivative values, basic statistics, and printer plotting. The library, demonstration drivers, and test drivers are stored in compressed form and are expandable with a program included in the package. MATH77 was developed during 1980-89. It is written in FORTRAN 77 and is suitable for use on any computer system that sup- ports the full FORTRAN 77 standard. The program and documentation are copy- righted products of the California Institute of Technology. This program was written by Charles L. Lawson, Fred T Krogh, William Van Snyder, and Stella Y. Chiu of Caltech for NASA's Jet Propulsion Laboratory. For further information, Circle 119 on the TSP Request Card. NPO-18120 Software for Depiction of Three·Dimensional Objects This program enables the user to build, manipulate, and display hierarchical three-dimensional objects. The use of hierarchy in a mathematical modeling environment is critical for effec- tive simulation of real objects. For a model that involves a combination of several moving parts, hierarchy is necessary to establish the network of dependent rela- tionships that govern the movements of the parts and the model as a whole. HME (the Hierarchical Modeling Environment) is a three-dimensional computer-graphics The Fotonic™ Solution For high-precision • Submicroinch resolution ' Frequency response to 200 kHz noncontact vibration/ displacement measurement Introducing the MTI-2000 Fotonic™ Sensor for noncontact measurement of vibration and displacement...featuring the latest advancements in electronic design and providing an unbeatable combination: affordability and unmatched performance • Digital readout in engineering units • Interchangeable probe modules • RS-232 interface and G-l0Voutpuf • Target size as small as .002 in. • Dual-channel design MTllnstruments 968 Albany-Shaker Road · Latham, NY 12110 · (518) 785-2464 Telex: 685-4572 MTILATMUW · FAX (518) 785-2806 From MTI: the pioneer in fiber-optic sensor tech- nology for over 25 years. 1-800-342-2203 NASA Tech Briefs, December 1991 Circle Reader Action No. 365 55 software system designed to give the user complete access to the total hierarchical mathematical model. HME enables the user to build, manipu- late, and display hierarchical three-dimen- sional objects dynamically. The program also includes created polygons in the hierarchy. The window-oriented user inter- face enables the manipulation of objects by use of the mouse, windows, menus, buttons, and sliders. A hierarchy window depicts the hierarchy of the mathematical model environment. The user can point at any node on the hierarchy and use a powerful set of standard options to edit, copy, create, or save that portion of the hierarchical environment. With HME, it is easy to establish and edit the proper coor- dination of eye points, sources of light, and connectivity of the model necessary for accurate depiction of the model. HME is written in C language for Silicon Graphics IRIS workstations supporting the 4Sight windowing software system and at least version 3.1 of the operating system. The program requires approximately 650 KB of memory and was developed in 1989. This program was written by Frank Taylor and Debbi Boettger of McDonnell Douglas Corp. for Johnson Space Center. For further information, Circle 93 on the TSP Request Card. MSC-21708 Aid for Simulating Digital Flight Control Systems A computer program translates descriptions of systems into programs for simulation. The DIVERS translator is a computer pro- gram to convert descriptions of digital flight- control systems (DFCS) into a computer program written in the C language. DIVERS is language developed to represent design charts of DFCS. The DIVERS translator converts DIVERS source code into an easi- ly transportable language, while mini- mizing the probability that the results will be affected by the interpretation of the pro- grammer. The final translated program can be used as a standard of comparison to verify the operation of actual flight-control systems. DIVERS is applicable to the simu- lation of other control systems; for exam- ple, electrical circuits and logic processes. The DIVERS language is designed to cor- respond directly to DFCS diagrams. The keywords (filter, summer, limiter, etc.) cor- respond to physical components. The sig- nals (volts, flap elevation, temperature, time, etc.) are variables corresponding to lines that connect the components. The DIVERS keywords are subroutines imple- mented in C and stored in a dictionary and are defined by the user in terms of input 56 signals, outputs, and lists of parameters. This enables each component to be thoroughly tested and verified before being used in an actual system. The enforced modularity reduces the risk of program- mer-introduced errors. A list of parameters to each keyword can include constants and conditional expressions. Signals are declared in terms of units, maximum and minimum values, type (real, integer, Boolean), and computer-memory requirements. The DIVERS code is trans- lated into a C program that can be run with input signals from the terminal or an existing data file. The program cycles through a control system, prompting for input, and displaying all signals declared as "test vari- abies". The user can alter a signal or retain its current value for the next cycle. The DCHART program is included in the DIVERS package. Its purpose is to read DIVERS source code and make a diagram of the data flowing between components. The output is used to compare the DIVERS specifications with the original DFCS chart. DIVERS is written in C for batch execu- tion and is available for two different com- puters. The DEC VAX version has been im- plemented on a VAX 11/780 computer operating under VMS 4.2. The UNIX ver- sion has been implemented on a DEC PDP 11/60 with ISl1 UNIXand a central-memory requirement of approximately 99K. This program was developed in 1985. . This program was written by Richard M. Hartman of InformatiCS, Inc., for Ames Research Center. For further information, Circle 144 on the TSP Request Card. ARC-117101ARC-11711 I Software for Simulation of Development of Software Personnel, resources, errors, and other realistic factors are represented in the simulation. SOFTREL is a prototype software pack- age that simulates creation, detection, and repair of defects and faults during a soft- ware-development project. The user initi- ates the process by entering the staff and resource schedules. The factors consid- ered in SOFTREL include (1) construction, integration, inspection, and correction of documentation; (2) construction, integra- tion, inspection, and correction of code; (3) preparation and conduct of tests; (4) identification and repai r of faults; (5) valida- tion of repairs; and (6) retesting. Param- eters include rates of building of new, re- used, deleted, and added components of documentation and code; rates of genera- tion of defects; rates and adequacies of inspections; rates and adequacies of cor- rections; and adequacies of validations. SOFTREL is available in executable form only for the IBM PC under DOS 3.3 or high- er. The program was developed in 1990. SOFTREL is a copyrighted work with all copyright vested in NASA. This program was written by Robert C. Tausworthe of Caltech for NASA's Jet Propulsion Laboratory. For further infor- mation, Circle 26 on the TSP Request Card. NP0-18295 Tracing and Control of Engineering Requirements Requirements and progress of an engineering project can be documented in systematic manner. TRACER (Tracing and Control of En- gineering Requirements) is a data-basel word-processing software system created to document and maintain the order of both requirements and descriptions as- sociated with an engineering project. For a project, there is normally generated a set of hierarchical documents in which the requirements of the documents of higher level levy requirements on the documents of the same or lower level. Traditionally, the requirements have been handled almost entirely by manual paper methods. One disadvantage of a typical paper system is that requirements written and changed continuously in different areas lead to mis- understandings and noncompliance. The purpose of TRACER is to automate the capture, tracing, review, and manage- ment of requirements for an engineering project. The engineering project still re- quires communications, negotiations, in- teractions, and iterations among people and organizations, but TRACER promotes succinct and precise identification and treatment of real requirements separate from the descriptive prose in a document. TRACER enables the documentation of the requirements and progress of an engineer- ing project in a logical, controllable, trace- able manner. The attributes of TRACER include the presentation of current requirements and status from any linked computer terminal and the ability to differentiate headers and descriptive material from the require- ments. Related requ irements can be linked and traced. The program also en- ables the printing of portions of docu- ments, individual approval and release of requirements, and the tracing of require- ments down into the specification of equip- ment. Requirement "links" can be made "pending" and invisible to others until the pending links are made " binding." Indi- viduals affected by linked requirements can be notified of significant changes with acknowledgement of the changes re- quired. An unlimited number of documents can be created for a project, and an ASCII- NASA Tech Briefs, December 1991 import feature enables the incorporation of existing documents. TRACER can auto- matically renumber section headers when inserting or deleting sections of a docu- ment and can generate signoff forms for any approval process as well as a table of contents. TRACER is implemented on an IBM PC under PC-DOS. The program requires 640 KB of random-access memory, a hard disk, and PC-DOS version 3.3 or higher. It was written with CLIPPER. The execut- able program is also provided with the distribution. IBM PC and PC-DOS are registered trademarks of International Business Ma- chines. CLIPPER is a trademark of Nan- tucket Corp. This program was written by Philip R. Turner, Richard L. Stoller, Ted Neville, and Karen A. Boyle of Caltech for NASA's Jet Propulsion Laboratory. For further infor- mation, Circle 87 on the TSP Request Card. NPO-18215 Software-Design- Analyzer System CRiSP-gO provides the soft- ware designer with a medium that facilitates alterations. The CRISP-go software-design-analyzer system, an update of CRISP-BO, is a set of computer programs that constitute a software tool for the design and documen- tation of other software and that support top-down, hierarchical, modular, structured methodologies for design and program- ming. The quality of a computer program can often be influenced significantly by the design medium in which the program is developed. The medium must foster the expression of the programmer's ideas easily and quickly, and it must enable flex- ible and facile alterations of, additions to, and deletions from these ideas as the de- sign evolves. The CRISP-go software-de- sign-analyzer system was developed to provide the programmer with such a de- sign medium. The design of a program in the CRISP- 90 medium consists of short, English-like textual descriptions of data, interfaces, and procedures that are embedded in a simple, structured, modular syntax. The display is formatted into two-dimensional, flow-chart- like segments for a graphical presentation of the design. lbgether with a good interac- tive full-screen editing or word-processing program, CRISP-90 becomes a powerful software tool for the programmer. In addition to being a text formatter, the CRISP-90 system prepares material, the manual extraction of which would be tedious and prone to error; examples of NASA Tech Briefs, December 1991 such material include a table of contents, a module directory, a structure (tier) chart, cross-references, and a statistical report on the characteristics of the design. Ref- erenced modules are marked by schemat- ic logic symbols to show conditional, itera- tive, and/or concurrent invocation in the program. A keyword-usage profile can be generated automatically and glossary defi- nitions inserted into the output documen- tation. Another feature is the capability to detect changes that were made between versions. Thus, "change bars" can be placed in the output document along with a list of changed pages and a version- history report. Also, items can be marked as " to be determined," and each appears on a special table until the item is supplied. The CRISP-go software-design-analyzer system is written in Microsoft QuickBasic. The program requires an IBM-Pecom- patible computer with a hard disk, 128K of random-access memory, and an ASCII printer. The program operates under MS- DOS/PeDOS 3.10 or later. The program was developed in 1983 and updated in 1990. Microsoft and MS-DOS are registered trademarks of Microsoft Corp. IBM PC and PeDOS are registered trademarks of In- ternational Business Machines Corp. This program was written by Robert C. Tausworthe of Caltech for NASA's Jet Propulsion Laboratory. For further infor- mation, Circle 125 on the TSP Request Card. Inquiries concerning rights for the com- mercial use of this invention should be ad- dressed to the Patent Counsel, NASA Resi- dent Office-JPL [see page 20). Refer to NPQ-18212. Numerical- Optimization Program The ADS computer program is suitable for such applications as minimum-weight design. The Automated Design Synthesis (ADS) computer program is a general-purpose numerical-optimization program for de- sign engineering. Significant applications have already been found for this program in the synthesis of structures (minimum- weight design). ADS provides a wide range of options for the solution of constrained and un- constrained function minimization prob- lems. The user makes choices at each of three software levels to tailor the method of solution to fit the particular minimiza- tion problem. The three basic software levels are Strategy, which represents the W·VlS·IR SPECTROSCOPY' OPTICAl.. IR SUPERCONDUCTOR UHV RESEARCH Liquid Transfer Systems Closed Cycle Refrigerators Multiple Pin Leadless Carrier Dewars Pourfill Dewars Custom Systems Engineering/Design Support Equipment Rental Temperature Cycling Cryogenic Instrumentation and Sensors R.G. HANSEN & ASSOCIATES 631 Chapala Street Santa Barbara. CA 93101 1805) 564-3388 FAX (805) 963-0733 Clrcl. R.ader Action No. 688 57 overall minimization strategy; Optimizer, which represents the particular minimi- zation algorithm; and One-Dimensional Search, which represents the method of applying the minimization technique. ADS relies on the user to formulate the problem and make appropriate selections from the solution options. Strategy options in ADS include sequen- tial unconstrained minimization using the exterior-penalty-function method; sequen- tial unconstrained minimization using the linear-, quadratic-, or cubic-extended-interi- or-penalty-function method; the augment- ed Lagrange-multiplier method; sequential linear programming; the method of centers (method of inscribed hyperspheres); and sequential quadratic programming. Opti- mizer options include the Fletcher-Reeves algorithm for unconstrained minimization, either the Davidon-Fletcher- Powell (DFP) or Broydon-Fletcher-Goldfarb-Shanno (BFGS) variable-metric method for uncon- strained minimization, and the regular or modified method of feasible directions (MFD) for constrained minimization. One- Dimensional Search options include con- strained or unconstrained function min- imization using only a golden-section method or a golden-section method fol- lowed by polynomial interpolation, and constrained or unconstrained function minimization using polynomial interpola- tion and/or extrapolation with or without first finding bounds on the solution. ADS is invoked by a calling program supplied by the user. ADS returns control to the calling program when information on a function or gradient is needed. This provides considerable flexibility in capa- bilities for organizing programs and re- starting execution of them. ADS can be used in four principal modes: (1) default control parameters and finite-difference gradients, (2) override default parameters (use finite-difference gradients) (3) default parameters and gradients supplied by the user, and (4) override default parameters and gradients supplied by the user. These options provide the user more control over the problem-solving procedure than would otherwise be available. The ADS program is written in FOR- TRAN 77 and developed on a CDC CYBER 170-series computer. The program re- qui res approximately 155K (octal) of 60-bit- word memory. The CDC version of ADS was developed in 1984 and updated in 1985. The VAX version is a port of the. 1985 CDC version. This program was written by Garret N. Vanderplaats of the Naval Postgraduate School for Langley Research Center. For further information, Circle 32 on the TSP Request Card. LAR-14S00 58 NASA Software Update For a quarter century, NASA's Computer Software Management and Information Center (COSMIC) has served as the central distribution point for all software developed under NASA funding. Although computer technology has evolved rapidly over the years, the center's mission has remained constant: to ensure that programs written by NASA and NASA-contracted scientists and engineers are made available for reuse in the private sector. Many of the programs created for NASA R&D projects have outstanding transfer potential. A program that calculates stress in the space shuttle also can calculate stress in an offshore drilling rig. Software that NASA Structural Analysis System (NASTRAN) This program has been continually maintained by NASA since its development in the 1960s. It has aided in the structural design of a wide range of objects, from high-impact printer parts to turbine engine blades, and is fully validated. Since the source code is included, NASTRAN can be modified or enhanced for new applica- tions. It runs on IBM mainframe, CDC, and DEC computers. Circle 70 on the TSP Request Card. GSC-12600 Systems Improved Numerical Dif- ferencing Analyzer and Fluid Inte- grator (SINDA '85/FLUINT) This gen- eral thermal analysis program handles both simple and extremely complex heat transfer problems, including those with both solid and fluid components. Available for DEC and Sun computers, the program yields NASTRAN-compat- ible output. Circle 71 on the TSP Re- quest Card. MSC-21528 Thermal Radiation Analysis System (TRASVS) Designed for solar heating design, TRASYS can handle partial shading of one surface by another, and translucent surfaces. It runs on a DEC computer and generates output com- patible with SINDA '85/FLUINT.Circ/e 72 on the TSP Request Card. MSC- 21030 C Language Integrated Production System (CLIPS) A tool for developing expert systems, CLIPS makes deci- sions in the same way a human expert would. The latest update incorporates a feature called COOL, the CLIPS Object-Oriented Language. Versions measures the pressure of air flowing over an aircraft wing can be modified to measure the pressure of water flowing over a fin_ A program that determines the optimal design for a communication laser also will determine the optimal design for a surgical laser. Before a program is offered to the public, it is reviewed by NASA's Center for New Technology Assess- ment. Once approved, most programs are made available within the US with few or no restrictions_ In addition to producing new programs, NASA continually updates and enhances existing software. Programs updated in the past year include: are available forthe IBM PC, the Macin- tosh, and UNIX workstations. Circle 73 on the TSPRequestCard. MSC-21208 Transportable Application Environ- ment (TAE Plus) A programmer's tool for fast and easy development of user interfaces, TAE Plus allows applica- tions to be moved from one computer to another without affecting the end user. It is based on X-Windows and Motif, and runs on DEC and Sun com- puters. Circle 74 on the TSP Request Card. GSC-13276 Long-Term Orbit Predictor (LOP) Designed for use on an IBM PC, this program is suited for lifetime analysis of orbiting spacecraft. Circle 75 on the TSP Request Card. NPO-17052 Chemical Equilibrium and Transport (CET) This powerful , machine-indepen- dent program calculates theoretical thermodynamic properties of chemical systems. It can aid in the design of compressors, turbines, engines, heat exchangers, and chemical processing equipment. Circle 76 on the TSP Re- quest Card. LEW-14166 Semi-Markov Unreliability Range Evaluator (SURE) and Pade Approxi- mation With Scaling and Scaled Taylor Exponential Matrix (PAWSI STEM) Together, these programs form a "reliability workbench," offering sev- eral theoretical approaches to the de- sign of redundant systems used in situ- ations where failure could be cata- strophic. They run on DEC computers. Circle 77 on the TSP Request Card. LAR-13789 and LAR-14165 NASA Tech Briefs, December 1991 Mechanics 62 Dynamic Analyses Including 69 Joints of Truss Structures 63 Lock for Valve Stem Processing Particle-Streak Imagery on a Personal Computer 74 Methods of Simulation of Incompressible Flow Hardware, Techniques, and Processes 59 Reducing WaterlHuil Drag by Injecting Air Into Grooves 64 Lightweight Valve Closes Duct Quickly 70 Computed Hypersonic Viscous Flows Over Delta Wings Navier-Stokes Computations 66 Numerical Simulation of Flow 71 Through an Artificial Heart Books and Reports 75 Computations of Impulsively Started Viscous Flow 76 New Sensors for Flow Velocity and Acoustics on Zonal Grids 59 A General-Coordinate Formulation for Boundary- Layer Flow 60 Two Techniques for Suppressing Vibrations in Structures 67 Mathematical Models of Turbulence in Hypersonic Flow 72 Experiments on Schemes for Adaptive-Wall Wind Tunnels 73 Artificial Intelligence in Computational Fluid Dynamics 73 Frequency-Domain Identi- fication of Aeroelastic Modes 76 Direct Finite-Difference Simulations of Turbulent Flow Computer Programs 52 Program Calibrates Strain Gauges 68 Investigation of Tapered Tension/Torsion Strap 54 Integrated Analysis Capability Program Reducing Water/Hull Drag by Injecting Air Into Grooves A proposed method would require much less air than does the microbubble-injection method. Langley Research Center, Hampton, Virginia The concept of reducing the drag on a water vehicle by placing air in the bound- ary layer between the vehicle and the water is not new but has been unworkable because of the difficulty of stabilizing a lay- er of air on the surface of the hull. Attempt- ed solutions to the air-stability problem re- quired changes in the basic configuration of the hull to trap air - an approach not practical for most oceangoing vessels. Previous work has shown that air in the boundary layer of a waterflow can, indeed, greatly reduce the skin friction. One tech- nique consisted of the injection of micro- bubbles through a porous plate into a boundary layer. Although this technique has reduced friction by as much as 80 per- cent, the required flow of air is so large that it negates the drag-reduction benefits in practical situations. The disadvantage of microbubbles is that they are easily dis- persed and fill the entire boundary layer. In theory, only the portion of air nearest the wall acts as a drag-reduction agent. Therefore, most of the air injected in the microbubble technique is wasted. A proposed technique for the reduction of friction drag on a hydrodynamic body involves the use of grooves and combina- tions of surfactants to control the motion of a layer on the surface of such a body. The surface would contain many rows of side-by-side, evenly spaced, longitudinal grooves. These grooves would be general- ly triangular, with tip-to-tip spacing be- tween 0.040 in. (1.0 mm) and 0.010 in. (0.25 mm) and depth from 0.10 in. (2.5 mm) to 0.010 in. (0.25 mm). The dimensions of grooves and sharpnesses of tips in a specific case would depend on the con- ditions of flow about the vessel. Air-injection ports would be either drilled holes in the valleys of the grooves or thin slots, each reaching across several valleys to distribute air more evenly. Air injectors would be angled as tangentially to the sur- face as possible. Injection of air would be repeated downstream several unit lengths, depending on the particular type of vessel. The ribbed surface would be roughened deliberately during fabrication or coated before use with an antiwetting surfactant to enhance its air-trapping ability. Fblytetra- fluoroethylene is the most-desirable coat- ing material , although such other antiwet- ting agents as those based on hydrocar- bons would also be effective. In operation, the air would be injected continuously through the ports. The ribs would act to hold the injected air in a con- necting sheet that would fill the grooves via transverse surface tension forces. The depth and spacing of the ribs would alter the interfacial tension at the surface, fa- vorably controlling the gas phase, or air sheet, by holding a thin sheet of air at the wall , where it is most likely to be effective in reducing drag. At slow speeds of vessels through water, this technique would likely require approximately one-tenth or less of the amounrof air required in the injection of microbubbles. This work was done by Jason C. Reed of Old Dominion University and Dennis M. Bushnell and Leonard M. Weinstein of Langley Research Center. For fur- ther information, Circle 150 on the TSP Request Card. This invention is owned by NASA, and a patent application has been filed. In- quiries concerning nonexclusive or ex- clusive license for its commercial develop- ment should be addressed to the Patent Counsel, Langley Research Center [see page 20}. Refer to LAR-14078. A General·Coordinate Formulation for Boundary-Layer Flow The general coordinates need not be orthogonal. Ames Research Center, Moffett Field, California A formulation for the solution of the equa- tions of boundary-layer flow in general body- fitted curvilinear coordinates retains the velocities in Cartesian coordinates. This formulation may increase the stability of nu- merical simulations by avoiding coordinate source terms. Moreover, in this formulation, the curvilinear coordinates do not have to be orthogonal, and much of the software (including that for grids and boundary con- ditions) developed previously for use in nu- merical simulations of flow based on the NASA Tech Briefs, December 1991 Curvilinear Coordinates are fitted to a body (e.g., an aircraft or a turbine blade) on which boundary-layer flow is to be computed . The coordinates ~ and I; lie on the surface of the body, while n runs perpendicularly to the surface of the body. Thus, the surface of the body is a sUrfact of constant n. 59 Navier- Stokes equations can be used. The equations in the new formulation ex- press the conservation of momentum along and perpendicular to the surface, the con- servation of energy, and the conservation of mass, and include an equation of state for a perfect gas that has a constant ratio of specific heats. For example, the equa- tion for the conservation of momentum per- pendicular to the surface is Pl1 = 0, while the equations for the conservation of mo- mentum along the surface are Put+PU u~+PV u." +PW ut + (~xP~+l1xP." + SxPt) = Ja'f) (J-l [}tm 1u." + (p./3)m 2 l1xll PVt+PUv~+PV v'f) +PWv j + (~yP~+l1yP." + syPt) = Ja." (J-l [}tml v." + (pJ3)m2 l1y]) PWt+PUw~+PVw." +PWw j + (~zP~+l1zPf/ + SzPt) = Ja." (r1 [}tm1 wf/ + (p.l3)m2 l1z]) In these equations, the curvilinear coordi- nates are t 11 and s; P denotes density; u, V. and W denote the Cartesian com- ponents of velocity along the x, Yo and z axes, respectively; P denotes pressure, 1L denotes viscosity; subscripts denote par- tial derivations with respect to the coor- dinates they represent; m1 = ,fx + ify + ifz; m2 = l1xU'f) + l1yVf/ + l1zWf/ J is the transformation Jacobian and U. V. and Ware contravariant velocities given by These six equations can be used to deter- mine p, u, W. the specific total enthalpy H, P' and v. Generally, P is uncoupled and determined from P = 0 and an outer-edge boundary conditiori so that P = Pe¢;Je along 11 coordinates. In more general cases, pressure is weakly coupled and can be determined from Sf/+Vl1 ° (V~P~+Vl1P.,,+VSPt) = 0 using the same outer-edge condition with the source term defined as sf/ = - pU (Ua~71x+va~71y+W a~71z) - pV (Ua.,,71x+VaT/71y+W aT/71z) = - pW (Uat71x+Vat71y+W at71z) where the overbar denotes scaling of met- rics, e.g., ~x = ~x/~~+~ +~ In this case, pressure varies throughout the boundary layer. This v-.ork was done by Joseph L Steger, William R. Van Dalsem, Argyris G. Panaras, and K. V. Rao of Ames Research Center. Further information may be found in NASA TM-1fXXJ79[N88-24600], '~Formulation for the Boundary-Layer Equations in General Coordinates.' , Copies may be purchased [prepayment requiredjfrom the National Technicallnfor- mation Service, Springfield, Virginia 22161, Telephone No. (703)487-4650. Rush orders may be placed for an extra fee by calling (BOO) 336-4700. ARC-12465 Two Techniques for Suppressing Vibrations in Structures The techniques are based on bridge feedback and a criterion for placement of actuators. NASA's Jet Propulsion Laboratory, Pasadena, California Two techniques intended to be used to- gether to suppress vibrations in a large, complicated truss structure involve a com- bination of active and passive damping. Research continues to develop a system that would use these and other techniques to suppress vibrations in, and help control the shape of, a truss structure in outer space that would support the precise, segmented reflector of a communication antenna. On Earth, the develqlmental tech- niques should be applicable to the sup- preSSion of vibrations in bridges and tall buildings. In addition to or in place of ordinary structural members, the truss or other structure includes active and passive damping members. Each active member includes a piezoelectric or other actuator collocated with a force sensor and a vibra- tional-velocity sensor (see figure). The first of the two new techniques calls for the use of the active damping members (which, by itself, is not new) in a bridge-feedback control scheme (which is new in this ap- plication). This soheme involves the con- cept of mechanical impedance of a mem- ber, defined as the Laplace transform of the ratio between the axial force applied to the member and the difference between the velocities of its ends. The mechanical impedance of an active member is anal- ogous to the electrical output impedance of an amplifier. In this scheme, local feedback is used 60 Part of a Truss Structure contains an active damping member, which is a stainless- steel tube 8 in. (20.3 cm) long and 1 in. (2.5 cm) in diameter with an embedded stack of concentric piezoelectric wafers, an eddy-current differential proximity sensor, and a strain-gauge force sensor. to control the mechanical impedance, lm' of each active member in such a way as to effectively make it less stiff (and possibly more or less damping). The mem- ber could dissipate incident vibrational energy maximally if its mechanical im- pedance were the complex conjugate of mechanical impedance, lL' of the rest of the structure. Uncertainties in the knowl- edge of the structure make the use of the complex conjugate impractical, and in- stead, the control system synthesizes a suboptimal lm' the real (damping) part of which equals IlLl, the modulus of the im- pedance of the rest of the structure. The second of the two new techniques is a scheme for the placement of the ac- tive and passive damping members. The problem of where to place each member of each type is one of combinatorial op- timization. The criterion for optimization is maximization of a weighted sum of the passive-damping and active-damping con- tributions to the rate of dissipation of vibra- tional energy. The weighting factors are selected on the basis of design require- NASA Tech Briefs, December 1991 NEW FROM INCO SPP. .. ULTRA FINE NICKEL POWDER Inco Type 210 Nickel Powder JUST ADD YOUR IMAGINATION SEND FOR YOUR FREE SAMPLE TODAY INca spp Park 80 West-Plaza Two, Saddle Brook, NJ 07662 Shin-Muromachi Building, 4-3 Nihonbashi-Muromachi 2-Chome, Chuo-ku , Tokyo 103 Japan 1-3 Grosvenor Place, London SW1X7EA England 15/FI Wilson House, 19-27 Wyndham Street Central, Hong Kong ments and engineering experience. In this technique, one seeks a suboptimal solu- tion by use of a simulated-annealing al- gorithm, which is one of class of heuristic, iterative algorithms that have been used in other optimation problems and that are named to reflect the fact that some as- pects of them resemble some aspects of a mathematical model of annealing. In simulated annealing, one accepts nonim- proving solutions according to probabilities determined from the Boltzmann function in the hope of escaping from or avoiding local optima and approaching the global optimum. This work was done lYf Gun-Shing Chen, John A. Garba, and Ben K. Wada of Cal- tech for NASA's Jet Propulsion labora- tory. For further information, Circle 159 on the TSP Request Card. NPO-17889 Dynamic Analyses Including Joints of Truss Structures A straightforward method is used to determine stiffness and damping coefficients. Lang/ey Research Center, Hampton, Virginia Space structures larger than 300 ft (91 m) in diameter, such as the hoop-col- umn antenna and proposed Space-Station structures (see figure), are being designed. These include truss substructures to span large distances because trusses provide high stiffness with low mass. The designs of many of these structures require ac- curate, dynamic analyses for prediction of loads, stability, shape control, and accur- acy of orientation. The designs of truss structures proposed for use in outer space specify jOints that enable the erection or deployment of the truss members. Unlike in civil engineer- ing structures, the designs of joints for space structures include finite tolerances between mating surfaces to enable the joints to rotate or to be latched. A tolerance results in a dead band within which a jOint can be made to move with nearly zero ap- plied force. The dead bands of jOints are believed to affect the vibrational response of truss structures significantly, and de- tailed mathematical modeling may be necessary to incorporate these effects in the overall, or global, analysis. The joints influence the dynamic response of a truss in two major ways: first, by redUCing the effective stiffness of the truss; and second, by introducing additional damping beyond that of a structure in which the members are rigidly connected but that is otherwise identical. Therefore, a method for mathe- matically modeling joints to assess the in- fluences of joints on the dynamic response of truss structures was developed in a study. Only structures with low-frequency oscillations were considered in this study; thus, only Coulomb friction and viscous damping were included in the analysis. The focus of this effort was to obtain finite-element mathematical models of joints that exhibited 10ad-vs . .SAP computer progams to predict the modes by use of mathematical models of the air- craft. Estimates of frequency and damping were plotted and compared with values predicted by both CAMRAD and />SAP. From the results of the measurements and analyses, the authors conclude that the combination of frequency-sweep exci- tation with frequency-domain analysis pro- vides a reliable and efficient method for the determination of the aeroelastic modes of the XV-15 aircraft from flight data. Because of its good analytical results and its re- duced flight time in comparison with other methods, the frequency-sweep method has been chosen to support flight tests of the aircraft equipped with the new com- posite blades. This work was done by C. W Acree, Jr. , and Mark B. Tischler of Ames Research Center. Further information may be found in NASA TM-101021 [N9(}21756], "Identifi- cation of XV-15 Aeroelastic Modes USing Frequency-Domain Methods." Copies may be purchased [prepayment required] from the National Technical In- formation Service, Springfield, Virginia 22161, Telephone No. (703) 487-4650. Rush orders may be placed for an extra fee by calling (800) 3364700. ARC-12407 Methods of Simulation of Incompressible Flow Numerical techniques for the solution of the Navier-Stokes equations are discussed. A report discusses methods for the nu- merical solution of the Navier-Stokes equations of viscous, incompressible flow, with emphasis on the pseudocompressi- bility method. Viscous, incompressible flows are encountered in many realistic en- gineering problems in aerodynamics and hydrodynamics. The advanced computa- tional techniques reviewed here contribute to improved deSigns by rapidly providing detailed information about conditions at all points in the flow fields of proposed de- signs. The approach taken in this study is to use a primitive-variable formulation of the Navier-8tokes equations in generalized curvilinear coordinates and to solve the equations numerically by a finite-differ- ence technique. The lack of a pressure term in the equation of continuity for in- compressible flow poses an obstacle to the solution. The oldest and most common- ly encountered method for satisfying the equation of continuity is to use Poisson 's equation to find the pressure, in an iterative relaxation scheme in which the diver- gence-free condition is approaChed. Another method is the fractional-step method. In the most common version of this method, one first solves for an auxiliary NASA Tech Briefs, December 1991 velocity field by use of a form of the m0- mentum equation in which the pressure- gradient term can be computed from the pressure in the previous time step or can be excluded entirely. In the next step, the pressure is computed and used to map the auxiliary velocity onto a velocity field free of divergence. In the pseudocompressibility method, the equation of continuity is modified by the addition of a derivative of pressure with respect to time, resulting in 2 aP + au, = 0 {J at ax, where~is the pseudocompressibility, P = pressure, ui = theith componentofveloci- ty, XI = the ith spatial coordinate, and t = time. Together with the equations of con· servation of momentum in unsteady flow, this forms a hyperboliclparabolic type of time-dependent system of equations. Solu- tions can be obtained through fast, implicit schemes developed for compressible flows, such as the approximate-factoriza· tion scheme by Beam and Warming or Briley and McDonald. The report describes a finite-oifference scheme for the simulation of flow in ar- bitrary three-dimensional coordinates, based on the pseudocompressibility meth- od. A computer program that implements this scheme is used to calculate the flow in the hot"9as manifold of the Space Shuttle main engine. The results of the computa- tion are found to compare favorably with data from tests and to offer information not readily available from experiments. This work was done by O. Kwak of Ames Research Center, J. L. C. Chang and R-J Yang of Rockwell International COrp., and S. E. Rogers of Sterling Federal Systems. Further information may be found in NASA TM-100038 [N90-20333], "Numerical Simulation Methods of Incom- pressible Flows and an Application to the Space Shuttle Main Engine. " Copies may be purchased [prepayment required] from the National Technical In- formation Service, Springfield, Virginia 22161, Telephone No. (703) 487-4650. Rush orders may be placed for an extra fee by calling (BOO) 336-4700. ARC-12199 computations of Impulsively Started Viscous Flow Progress in understanding a commonly studied flow is discussed. A report discusses the computation of the impulsively started flow of a viscous fluid about a circular cylinder. This and similar flow problems are studied quite commonly because they involve simple geometries and such important phenom- ena as the separation of flow, viscous NASA Tech Briefs, December 1991 drag, unsteady wakes, and vorticity. The validation of methods for the computation of these phenomena is an important step in the development of the ability to simu- late flows in more complicated geome- tries; for example, in the design of airfoils. The cylinder model also has practical im- plications for such engineering problems as interactions of winds and currents with cylindrical structural members. The report begins with an introduction that includes a brief history of the use of the Navier-Stokes equations to simulate impulsively started flows about circular cylinders. It describes the present study, which involves the combination of an an- alytic short-time solution with a predictor- corrector algorithm to march the unsteady Navier-Stokes equations forward in time. Unlike in previous solutions, a uniformly valid initial flow that satisfies the Navier- Stokes equations is used to start the cal- culation. The algorithm is very simple, using an implicit Euler forward integration scheme with an upwind biased, third-order approximation for the convection term. The initial development of the symmetric flow field is calculated up to a nondimensional time of about 7, based on the free-stream velocity and the radius of the cylinder. The results of the computations are pre- sented for three combinations of grid spac- The Hollow- Shaft Encoder for High-Performance Applications Any diameter up to 1.26" ---' • Internal flexible coupling to absorb installation misalignment and shaft runout • Simplifies your shaft design - no tapped holes, no shoulders, no critical length requirement • Accepts any shaft diameter up to 1.26" • (32 mm) • Up to 900,000 counts/rev at 4 MHz • Face-mount, synchro-cleat or square-flange base options Call now for FREE information or applications assistance 800-759-1844 Toll-free from all 50 states and Canada "-',,"TELE>YNE GURLEY 514 Fulton Street· Troy, NY 12181 518/272-6300· FAX 518/274-0336 Circle Reader Action No. 620 75 ing and outer-boundary location. The re- sults show that the stagnation pressure at the nondimensional time of 0.1 after the impulsive start, as computed in this study, agrees well with that computed by an analytic approximation in a previous study. At later times, the pressures computed in the two studies diverge. The stagnation pressure computed in this study initially differs from, but then converges with, the stagnation pressure computed for a similar but inviscid flow. A detailed analysis of the force-density and acceleration vectors of the Navier- Stokes equations is presented in graphical form to make apparent the relative impor- "Incredibly Easy to Use" ! Jrnl or QUlllily TeshnoloKY, V19, 13, p131 DESIGN YOUR OWN EXPERIMENTS! Powerful programs for your PC. Optimize your process or product. NEW IMPROVED - VERSION 21 DESIGN-EASE~ software: 2-level factorial, Plackett-Burman, and one-variable designs •.... ($395) DESIGN-EXPER1'* version 2 software for response surface and mixture designs .•....•. .. •. .... 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These vectors indicate a strong balance between diffusion and un- steady effects in the direction parallel to the surface of the cylinder, and between convection and the gradient of pressure perpendicular to the surface of the cylin- der. This verifies the essential uncoupling of the viscous, rotational flow field and the inviscid, irrotational flow. This oork was done IYy Sanford S. Davis of Ames Research Center. Further infor- mation may be found in NASA TM-101037 [N89-21190], "Computational Studies of an Impulsively Started Viscous Flow." Copies may be purchased [prepayment required] from the National Technical In- formation Service, Springfield, Virginia 22161, Telephone No. (703) 487-4650. Rush orders may be placed for an extra fee by calling (800) 336-4700. ARC-12382 New Sensors for Flow Velocity and Acoustics Development programs promise more accurate measurements. A paper describes two sensor-develop- ment programs at the Fluid Mechanics l..aI:r oratory at NASA Ames Research Center. One of the programs, for digital image vel- ocimetry (DIY) sensors, is in progress. The other program, for advanced acoustic sen- sors for wind tunnels, has just been started. DIV measures, in real time, the instan- taneous velocity fields of time-varying flow or of a collection of objects moving with vary- ing velocities. DIV uses high-speed video photography, image processing, and digital Fourier transformation to create an image of seed particles or moving objects from linearly superposed frames taken at fixed intervals. The velocities of the particles or Clrcl. R •• der Action No. 534 76 objects are determined from the separations between subsequent images of them. DIV ciffers from dher techniqJes br meas- uring the velocity fields of fluids (such as particle-image velocimetry and laser- speckle velocimetry) in that its single-expos- ure images can be isolated from the com- bined image. Single-exposure images can be used to eliminate uncertainties caused by overlaps and undesirable distributions of particles. The advanced acoustic sensors for wind tunnels are being developed to reduce the effects of interference from wind noise, noise from interactions between flows and sen- sors, flow-induced vibrations of sensors. de- flections of acoustic waves by boundary layers induced by sensors, and reflections from walls and sensor supports. The ad- vanced sensors include adaptive arrays of optical fibers in which signal processors automatically adjust the sensitivities of the arrays to enhance directivities and spectral responses. A representative array includes a source of light, optical-fiber interferometers, and a photodetector connected to a signal proc- essor. Sound modulates the phase of the light in the fibers. The modulated light is c0m- bined with unmodulated reference light, and the resulting interference signal is detected and sent to the signal processor, which ex- tracts information about the acoustic signal. This oork was done IYy Y. C. Cho of Ames Research Center. To obtain a copy of the report, "Sensor Development Program at NASA Ames Research Genter," Circle 64 on the TSP Request Card. ARC-12577 Direct Finite-Difference Sim- ulations of Turbulent Flow An upwind finite-difference scheme is compared with other numerical-integration schemes. A report discusses the use of an up- wind-biased finite-difference numerical-in- tegration scheme to simulate the evolution of small disturbances and fully developed turbulence in the three-dimensional flow of a viscous, incompressible fluid in a channel. In contrast with simulations in- volving approximate mathematical models of turbulence, direct simulation involves the use of a computational grid sufficient- ly fine to resolve the motion of the fluid at all relevant length scales. This study was motivated partly by the need to simu- late turbulent flows bounded by complicat- ed shapes and partly by the observation that the main advantage of finite-difference schemes over the highly accurate spec- tral methods lies in the relative ease with which finite-difference schemes can be applied to complicated shapes. The pur- pose of this study was to demonstrate the superior performance of high-order-ac- NASA Tech Briefs, December 1991 curate upwind-biased finite-difference nu- mericaHntegration schemes in simulating turbulent flows and accurately predicting the higher-order statistics of such flows. The main text begins by presenting the Navier-Stokes equations of flow and an upwind-biased finite-difference scheme for solving them. The scheme uses a stag- gered grid and is a variant of a partially implicit, fractional-step scheme used in a previous study. The accuracy of the in- tegration method is first tested by com- puting the evolution of small-amplitude dis- turbances in channel flow. The scheme is then used to compute fully . developed channel flow at a Reynolds number of 180 (based on wall shear velocity and the half width of the channel). The results of these calculations are compared with experi- mental data and with spectral calculations of the same flow in a previous study, and the agreement is found to be good. The dissipative nature of the upwind-biased scheme is found to control aliasing error without unduly affecting the accuracy of the solution for grids of reasonable size. The results of simulations using a second-order-accurate central-difference numerical-integration scheme are also pre- sented. The inadequacy of the second- order accuracy of the scheme (for the grid size chosen) is demonstrated using the test cases mentioned above. An additional limitation of this scheme is that its stabili- ty is ensured only because it conserves kinetic energy. Deviations in the differen- cing technique that retained second-order accuracy but not the energy-conservation principle resulted in unstable solutions. The report ends by stating several con- clusions, including the following: While the shortcoming of the upwind method (nu- merical dissipation) can be overcome by use of additional grid points, the limitations of the spectral method are more funda- mental in nature. The use of central-dif- ference schemes depends on whether general-purpose aliasing-error-control pro- cedures can be found. The upwind-differ- ence code requires approximately the same amount of computing time per grid point for each substep in the Runge-Kulla numerical-integration scheme as spectral simulations do. At present, it appears that the high-order-accurate upwind-biased method is a good candidate for direct sim- ulations of turbulent flows associated with complicated shapes. This oork was done by Man Mohan Rai of Ames Research Center and Parviz Moin of Stanford University. Further infor- mation may be found in AIM paper 89A- 25312, "Direct Simulations of Turbulent Flow Using Finite-Difference Schemes." Copies may be purchased [prepayment required] from AIM Technical Information Service Ubrary, 555 West 57th Street, New York, New York 10019, Telephone No. (212) 247-6500. ARC-12463 NASA Tech Briefs , December 1991 High Voltage Pulsed Energy Maxwell Laboratories has the high voltage products you need for pulsed power systems - • Power supplies • Trigger generators • Capacitors • Marx generators • Capacitor banks • and more • Switches Call today for FREE application and selection guides, or for more information on how our know-how can help you. Maxwell is dedicated to worldwide leadership in innovative applications of pulsed power and high voltage electronics. Laboratories, Inc. MAXWELL -----------------4 Call (800) 854-1505. Ask for the Sales Department. In California, call (619) 576-7545 8888 Balboa Ave., San Diego, CA 92123 . FAX (619) 279-1554 Machinery Hardware, Techniques, and Processes 78 Direct-Link Prehensor 78 Monitoring Bearing 79 Monitoring Engine 80 Dynamic Tester for Vibrations and Spectrum Rotor Seals and Vibrations for Signs of Damage of Exhaust Bearings ~~ Direct·Link Prehensor An operator-powered mechanical hand gives protection, dexterity, and proximity to the work. Ames Research Center, Moffett Field, California A mechanical prehensor replicates the movements of an operator's hand and fin- gers just a few centimeters from the hand. Because it encloses the operator's hand in a protective shroud, the prehensor enables the operator to grasp, hold, and manipulate nearby objects in a hostile or hazardous en- vironment. The operator moves the prehen- sor through direct mechanical linkages; no electric motors or electronic circuits are needed. The prehensor has a "ring" finger, an " in- dex" finger, and a thumb, mounted on a sup- porting frame (see figure). The ring and in- dex fingers consist of three jointed links each, and the thumb consists of two jointed links. The thumb is positioned opposite the fingers in an anthropomorphic arrangement. A palm assistor - a disk projecting from the support frame - helps the mechanical fingers to hold objects, much like the palm of a human hand. The shroud is made of a rigid, gas-im- permeable material such as aluminum or molded fiberglass. It is joined to the support- ing frame by welding, bonding, or other means that produce a gas-tight seal. At its wrist end, the shroud is joined to a sleeve of the operator's protective suit by a seal. Within the shroud, rings engage the vari- ous phalanges of the operator's fingers. The operator's middle and ring fingers are used in tandem to move the mechanical ring finger of the prehensor, and the operator's index finger and thumb are used indepen- dently to move the mechanical index finger and thumb, respectively, of the prehensor. A Shroud Encloses the Operator's Hand , protecting it from vacuum, high pressure, or hazard- ous materials. The external mechani- cal fingers are made of materials com- patible with the ex- ternal environment. Distal Finger Link When the operator moves part of a finger, the movement is translated by mechanical linkages into similar movement of the cor- responding part of the mechanical prehen- sor. For example, when the operator rotates the distal phalange of the thumb about its joint, the distal-control link rotates about the distal-control joint on the thumb mechanism. This actuates a distal-control push rod, the action of which rotates the distal thumb link about the distal link joint on the mechanical thumb. The ratio of motion of the mechanical fin- ger links to the corresponding control links is 1 to 1.1. With this ratio, the mechanical links can reach useful positions that would otherwise result in collisions between com- ponents of the control linkages. This v.ork was done by John W Jameson of Ames Research Center. For further in- formation, Circle 99 on the TSP Request Card. In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to Stanford University Office of Technology Ucensing 350 Cambridge Avenue, Suite 250 Palo Alto, CA 94306 Refer to ARC-11666, volume and number of this NASA Tech Briefs issue, and the page number. Monitoring Bearing Vibrations for Signs of Damage Real-time spectral analysis is performed to detect telltale changes in vibrations. Marshall Space Flight Center, Alabama Real-time spectral analYSis of vibrations is being developed for use in monitoring the conditions of critical bearings in ro- tating machinery. The underlying concept is simple and fairly well established: the appearance and growth of vibrations at fre- quencies associated with the rotations of various parts of a bearing system indicate wear, damage, and imperfections of man- 78 ufacture. These frequencies include the fundamental and harmonics of the fre- quency of rotation of the ball cage, the fre- quency of passage of the balls, and the frequency of rotation of the shaft. Vibrations that originate in a ball-bearing assembly can be sensed by strain gauges mounted on the outer race. Heretofore, the outputs of strain gauges have been record- ed and analyzed after testing the ma- chinery. In the developmental technique, the output of a strain gauge is processed by commercially available spectrum-ana- lyzing equipment to obtain a power spec- tral density plot of the vibrations in real time (see figure). A change in the plot - typically, an in- crease in amplitude at a particular frequen- cy - indicates a particular type of damage. NASA Tech Briefs, December 1991 Once this concept is developed into a re- liable technique for the detection of incip- ient failures, it may become permissible to disassemble the machinery less fre- quently for inspection and/or replacement of bearings. - 10.---~-----r----~---.r---~----'-----r----' This Instantaneous Power Spectral Density was com- puted from the output of a vibration-sensing strain gauge in a high- pressure oxygen turbopumpofthetype used in the Space Shuttle. The spectrum includes vibrations synchronous with the rotation of a similar nearby machine-a high-pressure fuel turbopump. This v.ork was done by Carol L Martinez of Rockwell International Corp. for Mar· shall Space Aight Center: For further in- formation, Circle 15 on the TSP Request Card. Fundamental Frequency of Rotation of Similar Nearby Machine Second Harmonic I Frequency of ~ : Inquiries concerning rights for the com- mercial use of this invention should be ad- dressed to the Patent Counsel. Marshall Space Flight Center [see page 20). Refer to MFS-29734. Rotation of Cage ':'.J -~0~----1~25-----25O~---3~75~~~~~~-6~~----~~L-L-~~ Frequency, Hz Monitoring Engine Vibrations and Spectrum of Exhaust Vibration- and emission-spectrum "signatures" indicate the condition of the engine. Marshall Space Flight Center, Alabama Real-time computation of the intensities of peaks in the visible-light emission spec- trum of exhaust has been combined with real-time spectral analysis of vibrations into a developmental monitoring technique that provides up-to-the-second information on the conditions of critical bearings in an engine. The technique was conceived to monitor the conditions of bearings in a tur- bopump that supplies oxygen to the Space Shuttle main engine and is based on pre- vious observations that both vibrations in the bearings and the intensities of visible light emitted at specific wavelengths by the exhaust plume of the engine can indicate wear and incipient failure of the bearings. The concept may be applicable to monitor- ing the "health" of other machinery (e.g., automotive engines and industrial furnac- es) via the spectra of vibrations and elec- Histories of Intensities of Peaks at two frequencies in each of two spectra indicate the "health" of a turbopump bearing in a rocket engine. Displays like these can be produced on the screen of a personal computer in real time from the output of an emission spec- trometer and vibration-analyzing equipment. No further modification of the engine under test is required. O.a. ,-----------------------------------------, 0.035 0.03 > 0.025 t E 0.02 J 0.015 0.01 0.005 20 19 18 17 16 15 14 .. 13 c: ::> 12 ~ 11 i! 10 € 9 « 8 ,;. 'iii c ~ 4 3 1 rms Amplitude of Strain-Gauge Vibration Signal at Frequency of Rotation ~ ~ ~ a m ~ m ~ m 250 m ~ Time, Seconds VIBRATION HISTORY Intensi ty of Emission by OH Radicals at Wavelength 0' 309 nm Intensity of Emiss ion by CaOH Radicals at Wavelength of 623 nm, Shifted Upward by 3 Arbitrary Intensity Units make quality plastic tubing connections. Vacuum or pressure, seal to 120 psi for air, gas or liquid_ Hose barb, pipe thread, or ferruless fittings. In- line or panel mounts. ~~SSEi Respond to this ad Ii; for a Trial Size Coupling Coupon and our catalog_ Select a Delrin coupling . -. for 1/16" to 3/8" tubing- ..... return coupon and $3.00 for shipping. Coupling _ ... ~.-_ will be sent promptly_ 0 0 ~ 100 1~ ~ Time, Seconds EXHAUST·EMISSIONoSPECTRUM HISTORY 250 ~ CPc'MCOLDER PRODUCTS CO. 1001 Westgate Drive· 5t. Paul. MN 55114· Call 612-645·0091 NASA Tech Briefs, December 1991 Circle Reader Action No. 517 79 tromagnetic emissions from exhausts. This monitoring concept is related to the one described in the preceding article, " Monitoring Bearing Vibrations for Signs of Damage" (MFS-29734). In this case, however, instead of displaying the broad vibrational spectrum at a given instant, one displays plots that provide an up-te-the- second history of the intensities in (a) two narrow bands of the spectrum of vibrations and (b) two narrow bands of the emission spectrum of the exhaust (see figure). The frequency bands are selected on the basis of previous experience as being indicative of the condition of the engine: The appearance of certain anomalous wave- lengths in the exhaust can be correlated with the appearance of certain frequen- cies of vibration. By observing the evolu- tion of the plots, a test engineer can deter- mine when damage has become severe enough to warrant turning the machinery off or disassembling the machinery to in- spect or replace the bearings. This work was done IYy Carol L Maronez, Michael R. Randall, and John W Reinert of Rockwell International Corp. for Mar· shall Space Flight Center. For further in- formation, Circle 161 on the TSP Request Card. Inquiries concerning rights for the com- mercial use of this invention should be ad- dressed to the Patent Counsel, Marshall Space Flight Center [see page 20). Refer to MFS-29733. !~ Dynamic Tester for Rotor Seals and Bearings A simplified apparatus measures performance under vibration. Marshall Space Flight Center, Alabama A testing apparatus measures some of the dynamic parameters of rotor seals and bearings. It tests damping seals, damping bearings, conventional seals (such as laby- rinth seals), and conventional bearings (such as ball bearings). It can be used with a variety of pumped liquids, from water to liquid oxygen or hydrogen. Designed primarily to test the bearings and seals of turbopumps, the tester rotates the shaft at high speed while liquid flows much as it would in a real turbopump. Meanwhile, the tester subjects the bear- ings and seals to vibration. It measures pressures at various points to determine leakage and dynamic parameters that de- pend on pressure. It also measures the deflections of the components. The version illustrated in the figure con- tains a set of four damping seals and two damping bearings to be tested. The liquid enters a hollow shaft under high pressure from both ends. The liquid flows out of the shaft along several paths, including through a reaction turbine, which generates a torque that drives the shaft without axial thrust. Small discharges of liquid at opposite ends of the shaft negate any residual axial load. The four damping seals to be tested are formed by the liquid that flows between the shaft and a grooved bushing that sur- rounds the shaft. The liquid flows into the damping seals through radial holes in the shaft. A pair of rods tangent to the bushing ~only one is shown in the figure) vibrates the seals at frequencies different from the rotational frequency. Strain gauges on the rods measure the forces applied by the vibrator and the torque on the test seals from fluid-rotation drag. Pairs of orthogonal proximity probes on OPPOSite ends of the shaft measure the deflections and vibrations of the shaft. Similar pairs of probes on opposite ends of the bushing measure the vibrations and deflections of the seal. An array of pressure gauges at critical locations measures inlet and discharge pressures. The back pressure in cavity A controls the shaft speed. The back pres- 80 sure in cavity B controls the pressure drop across the test seals. Flowmeters measure the discharge of liquid from cavities A, B, and C, which are separated by labyrinth seals. The flow from chamber A is used to calculate the turbine torque. The flows from chambers Band C are used to determine the leakage through the damping seals and the damp- ing bearings. Because the tester contains no rolling- element bearings, it is highly reliable at high speeds. The shortness of its shaft eliminates resonances in the testing- speed range. It is simpler than previous testers were: it uses only one liquid; it has no gears, drive motors, or quill shafts; a single back-pressure valve controls shaft speed. Instrumentation is inserted from outside for ease of access and mainte- nance; electrical connectors are outside the housing, away from the test liquid. Be- cause it produces no axial thrust, rubbing is eliminated and special hydrostatic thrust bearings are unnecessary. The bearings can be machined off- center in the bushing to determine the ef- fects of eccentricity. Because four bear- ings are mounted, their eccentricities can be arranged symmetrically with respect to the midsection of the bushing; this elimi- nates excessive loads on the damping bearings. This work was done by George L. von Pragenau of Marshall Space Flight Cen· ter. For further information, Circle 22 on the TSP Request Card. Inquiries concerning rights for the com- mercial use of this invention should be ad- dressed to the Patent Counsel, Marshall Space Flight Center [see page 20). Refer to MFS-28493. High-Pressure Liquid Flows by diverse routes through the tester. Flow through the reaction turbine drives the hollow shaft. Flow through the radial holes in the shaft to the inner surface of the bushing forms the damping bearings . Flows at the ends of the shaft balance residual axial thrust. NASA Tech Briefs, December 1991 Reader Service No. 402 To Receive Literature Reader Service No. 405 Extraordinary runner. Like the cheetah, the Balzers 520M magnetically suspended turbopump runs silently and swiftly. You can rely on it for the smoothest operation over the longest run because it purrs along on two permanent-magnet radial bearings and an active axial magnetic bearing, monitored by electronic sensors. Our patented oil-free magnetic bearings assure low-vibration, clean operation in any mounting position ... with no maintenance and no lubrication required. The 520M is your sensible solution for HV and UHV applications demanding ultimate clean vacuum performance, such as mass spectrometry, surface analysis, electron microscopy, high-energy physics and semiconductor processing. Contact us today for details on how our extraordinary runner can optimize your process. BALZERS To Have A Sales Rep. 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Box 231 Medina, NY 14103 Phone: (716) 798·3140 FAX: (716) 798-3106 82 Circle Reader Action No. 319 Fabrication Technology Hardware, Techniques, and Processes 82 Trailing Shield for Welding on Pipes 82 Smaller Coaxial· View Welding Torch Trailing Shield for Welding on Pipes ~~ Weld beads remain covered with inert gas until safely cooled.~ Marshall Space Flight Center, Alabama A trailing shield ensures that a layer of inert gas covers the hot, newly formed bead between two tubes or pipes joined by plasma arc welding. The inert gas pro- tects the weld bead from oxidation by the air until it is cooler and less vulnerable to oxidation. The trailing shield is intended especially for use on nickel-base alloy pipes, on which weld beads remain hot enough to oxidize after the primary inert- gas purge from the welding-torch cup has passed. Unlike previous shields, the new shield does not require a silicone-cloth skirt to keep outside air from entering the gap be- tween the edges of the shield and the workpiece. Instead, the internal contour of the shield creates a steady flow of inert gas to the bead so that no air can reach it. It provides better protection against ox- idation than does a skirted shield. The new shield is a segment of curved, The Tubular Shield Partially Encircles a pair of pipes at a weld jointbetweenthem_ln- ert gas diffuses into the shield through a porous tube, covering the hot weld joint. The shield follows the welding torch as it ad- vances. Trailing Shield Sintered Stainless-Steel Tube. 0.250 In. (6.35 mm) OutSide Diameter ~ SECTION A-A open-walled aluminum pipe that trails the welding-torch cup (see figure)_ The seg- ment is contoured to match the circum- ference of the pipes to be welded while maintaining a uniform O.1 2S-in. (3.2-mm) gap. The inert gas enters the shield through a sintered stainless-steel tube. The cross section of the shield is shaped to direct the gas to the workpiece in tight turbulent swirls. The gas leaves the shield through the gaps at the edges, excluding exterior air. This work was done by John B Coby, Jr. , and Kenneth J. Gangl of Rockwell Interna- tional Corp. for Marshall Space Flight Center. No further documentation is avail- able. Inquiries concerning rights for the com- mercial use of this invention should be ad- dressed to the Patent Counsel, Marshall Space Flight Center [see page 20). Refer to MFS-29743. Inert·Gas Inlet of Trailing Shield Smaller Coaxial·View Welding Torch This torch resembles an ordinary torch without optics. Marshall Space Flight Center, Alabama A coaxial-view torch for gas/tungsten arc welding has only two-thirds the length and width of its predecessor. The shape and size of the new torch are similar to those of a commercial arc-welding torch (Linde HW-27 or equivalent), even though it contains a lens system (see Figure 1). In addition, the collet that holds the elec- trode has unique design that allows greater passage of light than earlier designs did. Because the redesigned torch is so much smaller, it can be used in small NASA Tech Briefs. December 1991 Figure 1. The Optics in the Welding Torch are concentric with the electrode. The prin- cipal virtue of this design is its relative smallness. spaces that were previously inaccessible. In addition, because it is so like the com- mercial version, it can be introduced into production welding operations with a mini- mum of disturbance. The torch, mounted on a welding robot (see Figure 2), forms an image of the weld seam and of the molten pool around the electrode axis. The image is used for re- mote monitoring by an operator or for closed-loop computer control of the robot. The optical components in the torch are self-aligning, standard-sized parts. These components can be changed easily to ob- tain different magnifications. This work was done by Kenneth J. Gangl of Rockwell International Corp. for Mar· shall Space Flight Center. No further documentation is available. Inquiries concerning rights for the com- mercial use of this invention should be ad- dressed to the Patent Counsel, Marshall Space Flight Center [see page 20}. Refer to MFS-29744. Figure 2. The Welding Torch, with its integral optical system, is mounted on one end of a welding robot. NASA Tech Briefs. December 1991 Convert Any Hiuh-Res Video to TV Formatsl Monitor We Can Convert Anyone With over 20 years experience, Folsom Research has built a worldwide reputation jor superior products and leading-edge technology. Our products are currently used by most Fortune 500 companies. Several models are available. Product features include • Video frame grab. • Digital frame buffer access. • uppOIt for multiple workstations. • On-board V-LAWM for controlling single-frame recorders, videodisks, and editing systems. • Medical, video, and radar products available. Call Us to Find Out Which Product Will Convert You! ~ Folsom 526 East Bidwell Street Folsom, CA 95630 • E I I •• c • tel: 916983.1500 lax: 916.983.7236 Circle Reader Action No. 648 85 tJ Mathematic .. s !!,,~,~!!~On 56 S~~~~~~m"'",;O" of Manipulator Inverse Dynamics Development of Software Computer Program 56 Trac ing and Control of Hardware,Techniques and Processes 55 Library of Subprograms in Engineering Requirements 86 Generation of Surface Grids From Data Points FORTRAN n 57 Software-Design-Analyzer 55 Software for Depiction of System 86 Algorithm Reveals Sinusoidal 56 Component of Noisy Signal Three-Dimensional Objects 57 Numerical-Optimization Program Aid for Simulating Digital Flight Control Systems Generation of Surface Grids From Data Points Grids are constructed by interpolation and blending of patches. Ames Research Center, Moffett Field, California A computational procedure generates grids on complicated three-dimensional surfaces (e.g., those of airplanes) from sets of data pOints (e.g., those generated by computer-aided design systems) that lie on and specify those surfaces. Such grids are needed to compute flows over the sur- faces. Starting with grouping of possibly sparse surface points into lines and/or patches, the procedure involves interpola- tion within and blending of lines and/or patches and possibly the redistribution and reassembly of patches to obtain a finished system of zonal patch grids that match at the boundaries between them. The procedure can be semiautomated via a computer program that performs all steps except the selection of patches and interpolation points, which are left to the discretion of the user. The original data on the surface points cannot usually he used in raw form and must be preprocessed. For example, a fu- selage might be represented by sets of points that vary widely among different cross sections, wing/fuselage intersections may be undefined, and there may not be enough points to represent the surface ac- curately in areas of large curvature. In ad- dition, it is necessary to group the data in- to the network of patches, which is to serve later as the basis for a global block structure. To perform the necessary pre- processing, the procedure includes an al- gorithm, called the "geometry data proc- essor," which acts like a data editor in that it provides for the insertion, deletion, and redistribution of surface data points. It can also smooth a sectional curve by interpo- The Curve of Inter- section of a vertical surface grid of 8 by 5 points with a horizon- tal surface grid of 21 by 5 points is initially unknown. An iterative procedure finds the curve of intersection. Additional grid points and lines are then inter- polated and matched at the intersection. lating and segmenting it into any number of pieces. These functions are all per- formed in conjunction with interpolation between data points on curves via piece- wise parametric cubic polynomials. Once the initial geometric data have been preprocessed, an algorithm called the " surface grid generator" interpolates each patch to a grid of m by n points with distribution functions on its boundaries (m, n, and the distribution functions are speci- fied by the user). Here, the interpolation technique of the geometry data preproc- essor is extended to bicubic parametric interpolation. The surface grid generator also finds the intersection of two surfaces via a parametriC equation, based on the in- terpolation scheme, for the intersection of INITIAL SURFACE GRIDS: INTERSECTION UNKNOWN INTERSECTION FOUND GRIDS ENRICHED AND MATCHED AT INTERSECTION one surface with a curve in the other sur- face (see figure). The equation is solved by the Newton-Raphson method; conver- gence is usually obtained within three to four iterations. This work was done by Raymond Ching- Chung Luh of Ames Research Center. Further information may be found in NASA TM-101046 [N89-13747]. "Surface Grid Generation for Complex Three-Dimen- sional Geometries." Copies may be purchased [prepayment required] from the National Technical In- formation Service, Springfield, Virginia 22161, Telephone No. (703) 487-4650. Rush orders may be placed for an extra fee by calling (800) 336-4700. ARC-12481 Algorithm Reveals Sinusoidal Component of Noisy Signal The product of the analysis is presented in easy-to-interpret graphical form. Marshall Space Flight Center, Alabama An algorithm performs a simple statisti- cal analysis of a noisy signal to yield a pre- liminary indication of whether or not the signal contains a sinusoidal component. The algorithm is suitable for the preproc- eSSing or preliminary analysis of vibrations, 86 fluctuations in pressure, and other signals that include large random components. The algorithm is implemented on a per- sonal computer by an easy-to-use program. The success and utility of the algorithm depend on several assumptions. One is that the signal has been digitized at a sampling rate high enough to capture any sinusoidal component, and preferably con- siderably higher than the frequency of oscillation of the sinusoidal component. The second assumption is that the prob- NASA Tech Briefs, December 1991 Imagine having thepower to experiment ... Imagine having more time to ponder the abstract, rather than having to derive the solution. With MACSYMAGP symbolic math sollware you can! No other software today packs the computa- tional power, versatility, and reliability of MACSYMA. MACSYMA can tackle any mathematical application you may have, whether in algebra, calculus, trigonometry, or practically any other branch of higher mathematics. It gives you problem-solving tools such as Laplace and Fourier transforms, Taylor and Poisson series, solution of first and second order differential equations, solu- tions to integrals, and more. It gives you sophisticated 2-D and 3-D graphics, and can convert your equations into Fortran or 'C' for optimal numeric performance, or T EX for inclusion in publications. MACSYMA provides unequalled accuracy too, with your choice of exact or arbitrary precision arithmetic, and gives you results at speeds from 10 to 100 times faster than traditional methods. All this power is remarkably easy to use. With the help of the User's Guide, extensive on-line docu mentation, executable examples and demon- strations, and the Quick Reference Card, a beginning MACSYMA user can quickly become proficient, tackling problems that might otherwise have been too difficult or time-consuming. Whatever your application - engineering, science, economics or pure math - your work is too important to trust to any other math software. You ' deserve MACSYMA. More than just a system for doing mathemat- ics by computer, it's the power tool for mathematics. CallI-800-MACSYMA* about our newest release, featuring: • reduced prices • ports to more RIse platforms • expanded features, including graphics for X windows symbolics. Inc. MACSYMA Division 8 New England Executive Park East, Burlington, MA 01803, USA. 1-800-MACSYMA; ·in Massachusetts, 617-221-1250 MACSYMA Is a registered trademark of Symbolics, Inc. TEX Is a trademark of the American Mathematical Society. Circle Reader Action No. 524 88 LABTECH® Opens Windows NOTEBOOK '" and CONTROL'" Run Under Windows and X-Windows Now ... LABTECH NOTEBOOK, our general- purpose data acquisition, analysis, and control software, along with LT{CONTROL, the process monitoring and control software from our Industrial Products Division, supports both Microsoft Wmdows'" and X-Wmdows"'. With this advance, LABTECH lets you take advantage of all the features of Wmdows software, including multitasking, whether you are using a PC or a UNIX or VMS workstation. Our software is available for the widest selection of operating environments and I/O devices. LABTECH is dedicated to cross- platform compatibility. If you change com- puters, you can also transfer your LABTECH software. Opening Wmdows while maintaining that compatibility ... another example of our commit- ment to protecting your software investment Of course, LABTECH software is still available for MS-DOS and OS(2. For more information, call or fax: I1ILABTECH 400 Research Drive WUmington, MA 01887 Tel.: 508/657-5400 Fax: 508/658-9972 The prodocu mentioned above ate trade.masts of their respective companies.. Circle Reader Action No. 423 Minimum Excursion of Sinusoid Number of Occurrences, StatistlcaJ Frequency, or Probability Density Mean Amplitude RANDOM DISTRIBUTION WITH SINGLE PEAK Number of Occurrences, Statistical Frequency, or Probability Density ~Mean I Amplitude DOUBLE·PEAKED DISTRIBUnON Maximum ExcurSion of SinuSOid Amplitude Amplitude Figure 1. These Statistical Distributions are easily distinguishable. Thus even a non-expert user can examine the output of the algorithm and draw a preliminary conclusion as to whether or not a signal contains a sinusoidal component. 3. 11(1)OO'"...------'-----.,.,~---....I...-~~..:.....,,1L.40:-----.-J TIme Alter Starl of Tes!. s 300.0 r---------------------------------------------~ 250.0 '" g 200.0 ~ " 8150.0 ~ §100.0 Z 50.0 O.OL_L~...L.._...I_ _ _L. _ __.l.. _ __L_.::~~~r:_:~ -80 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 Pressure About Zeroed Mean. pSia Figure 2. The Raw Signal Data of the upper plot were processed by the algorithm to obtain the statistical distribution of the lower plot. NASA Tech Briefs, December 1991 ability distribution (statistical frequency vs. amplitude) of the random (noisy) compo- nent of the signal has only one peak at a mean amplitude (e.g., a Gaussian distribu- tion). The third assumption is that only one sinusoidal or approximately sinusoidal com- ponent is present. The algorithm begins by scanning all the samples in the time series to identify the maximum and minimum signals. Then it divides the amplitude interval between the maximum and minimum signals into subintervals (statistical bins), the number of which is specified by the user. Next, the algorithm creates a crude probability dis- tribution by sorting the samples into bins according to their amplitudes . Th is distribution is presented graphically as a histogram. If many data are available, the histogram can be fairly fine-grained , approaching a smooth probability distribution. Figure 1 illustrates how to interpret the graphical output. If the signal oscillates randomly about a single mean, then the plot shows a single (e.g., Gaussian) peak. If a sinusoidal component is present, then there are two peaks - one at each of the two extremes of the sinusoidal oscillation. Figure 2 illustrates an application to real data. The upper plot represents sampled measurements of pressure in the combus- tion chamber of a rocket engine during a test firing . The data in the upper plot were processed by the algorithm to obtain the lower plot. The lower plot has only one main peak, suggesting that the pressure signal contains little or no sinusoidal component. This work was done by Lloyd C. Kwok of Rockwell International Corp. for Mar- shall Space Flight Center. For further in· formation, Circle 153 on the TSP Request Card. MFS-29688 Fast Parallel Computation of Manipulator Inverse Dynamics Multilevel parallelism is exploited by an MIMD-SI~D special-purpose parallel architecture. NASA's Jet Propulsion Laboratory, Pasadena, California A method for fast parallel computation of the inverse dynamics problem, which is essential for real-time dynamic control and simulation of robot manipulators, is undergoing development. The method en- ables the exploitation of a high degree of parallelism and, hence, the achievement of a significant computational efficiency, while minimizing various communication and synchronization overheads as well as the complexity of the required computer architecture. Unlike previous methods de- veloped for this purpose, this one does not represent an attempt to exploit the possibly The Universal Real-Time Robotic Controller and Simulator (URRCS) consists of an internal host processor and several SIMD processors with a ring topology. The archi· tecture is modular and expandable: more SIM D processors can be added to match the size of the problem. The SI MD processors can operate asynchronously and in a MIMD fash ion. suboptimal capabilities of any specific parallel computing architecture for the problem. Instead, this method first starts by analyzing parallelism at several com- putationallevels in the Newton-Euler form- ulation of the inverse dynamics problem and by designing algorithms for efficient explOitation of parallelism. A special- purpose parallel architecture is then designed and developed for efficient im- Left· THE URRCS ARCHITECTURE Pipeline Registers ...----- Control Bus I===:H:=-==~~~~=~ Right· Neighbor Interface '--_..L-_..L-_..L-_.....L-_~ __ Clock AF: Address Field, IF: Instruction Field. CF: Control Field, PE: Processing Element. THE SIMD PROCESSOR ARCHITECTURE NASA Tech Briefs, December 1991 HIGH PERFORMANCE ROTARY CONTACTS THERMOCOUPLES, RTD's, L VDT's STRAIN GAUGES, 1 to 100 contacts! 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CAuFORNIA 94010 TEL (415) 347-9953 FAX (415) 347-9536 Circle Reader Action No. 406 plementation of the algorithms. A hierarchical graph-based approach is proposed to study parallelism at several computational (or, abstraction) levels, the algorithm and the architecture for exploita- tion of the algorithm, the relationships bet- ween various algorithmic and architectural features, and efficient design tradeoffs. At each level, an algorithm is regarded as the application of a parallel model of computa- tion that transforms the computation into a graph. Each node of the graph repre- sents an operation or a set of operations on a subset of data, and the directed arcs represent the data dependencies among the nodes. The graph is then mapped on an abstract parallel architecture wherein the nodes represent the processors and the arcs represent the communication structure of the architecture . The mapping process is continued by proceeding through levels of increasing detail , further refining the features of the abstract architecture by making efficient algorithmic/architectural design tradeoffs at each level. The behaviors of the algo- rithms are described in terms of the flow of data through the graph, which defines the computation time and the sequencing of the abstract architecture. The exact features of the target architecture are de- fined by optimizing the abstract architec- ture for maximum exploitation of the prop- erties of the algorithms while minimizing the architectural complexities. This approach has led to the successful development and implementation of the Universal Realiime Robotics Controller and Simulator (URRCS), which is an algo- rithmically specialized, highly parallel MIMO/SIMO architecture (see figure), where MIMO and SIMO stand for "multi- ple-instruction/multiple-data" and "single- instruction/multiple-data" types of parallel architecture. The practical implementation of the Newton-Euler formulation for a six- degree-of-freedom (OOF) general (i.e., with no optimization) robot manipulator has shown that the inverse dynamics can be computed in 187 p.s. The increase in com- putation time for each additional OOF is 23 p.s, which leads to a computation time of less than 500 p.s, even for a 12-00F re- dundant robot manipulator. Such a per- formance enables the implementation of the most advanced dynamics-control schemes with a sampling rate greater than 1 kHz. The approach of this work has also been applied for the development of the Robot Mathematics Processor (RMP), which is a faster and more elaborate suc- cessor to the URRCS. This work was done by Amir Fijany and Antal K. Bejczy of Ca/tech for NASA's Jet Propulsion Laboratory. For further infor- mation, Circle 5 on the TSP Request Card. NPO-1BOBO NASA Tech Briefs, December 1991 91 Instrument Measures Ocular Counterrolling 92 Capillary-Effect Root-Environment System Instrument Measures Ocular Counterrolling A compact, battery-powered, noninvasive unit replaces several pieces of equipment and an operator. Lyndon B. Johnson Space Center, Houston, Texas An instrument that looks like a pair of goggles with a small extension box meas- ures ocular counterrotation, which is the torsional motion of the eye in the direc· tion opposite that of the tilt of the head relative to the ground andlor caused by muscle-stretch receptors in the neck. The instrument, called the "otolith tilt-transla- tion reinterpretation" (OnR) goggles, is used in studies of space motion sickness. The instrument was developed to test the OnR theory, which suggests that, after the central nervous system has adapted to microgravity, otolith signals elicited by tilts of the head in normal Earth gravity are in- terpreted as indications of linear transla- tion. The OnR goggles can also be adapt- ed to use on Earth and determine the extent of impairment in patients who may have impaired otolith functions. Excluding mounting suctions cups and the face mask that make contact with test subject or patient, the main part of the in- strument is contained in a box 10.5 by 5.5 by 2 in. (26.7 by 14 by 5.1 cm). It measures the torsion of the eye by measuring the relative motion of an afterimage briefly im- printed on the retina by a flash of light. Previously, such measurements had to be performed in a darkened laboratory by one or two operators in addition to the test sub- ject, who was restrained on a large tilt table. Assorted photographic equipment on test stands was employed. The new instrument contains electron- ics, flash, target, display, and mechanical components in a single unit. It is mounted on a wall or cabinet with suction cups and operated by the test subject alone. The subject presses against the face mask to close out ambient light. A strap encircling the subject's head helps to maintain a tight fit (see figure). The subject turns on the angIe-indicat- ing display in the goggles and sets a target to 0° (that is, perpendicular). The display is then turned off. Next, a cue light in the middle of the target is turned on; the sub- ject focuses on this light and presses the flash button. The flash imprints the image of the target on the retina. Thereafter, a light is strobed twice per second to main- tain the afterimage. The subject stralght- NASA Tech Briefs, December 1991 SUBJECT SELF·ADMINISTERING TEST INSTRUMENT ALONE, SHOWING SOME COMPONENTS The Compact, Battery-Powered Instrument enables a subject to self-administer tests for ocular counterrolling . ens the head and rotates the target until it becomes aligned with the afterimage. The subject turns on the display once more and records its position. This pro- cedure is done for initial head angles of 0°, 15°, 30°, and 45°. This work was done by Barry M. Levitan and Millard F Reschke of Johnson Space Center and Lawrence N. Spector of Krug International. For further information, Cir- cle 50 on the TSP Request card. MSC-21711 91 Capillary-Effect Root-Environment System Capillary forces in a membrane prevent excess flow. John F Kennedy Space Center, Florida The capillary-effect root-environment system (CERES) is an experimental appa- ratus for gro.ving plants in nutrient solu· tions. Although the apparatus was con- ceived for use in the microgravity of space, it may also find terrestrial application in germinating seedlings, because it can pro- tect them from extremes of temperature, moisture, and soil pH and from overexpo- sure to fertilizers and herbicides. The CERES includes a plastic screen in a recess in a plastic plate (see figure). A porous membrane is placed over the screen and sealed at the edges of the recess. Root hairs are placed on the membrane. Nutrient Solut ion Circulating at Pressure Slightly Less Than Atmospheric Hydroponic water solution flows from a container through the interstices of the screen, beneath the membrane. Aperistal- tic pump returns the solution to the con- tainer. Where a root touches the mem- brane, its adsorptive attraction draws the solution through the membrane so that it forms a film around the root. A slight ten- sion in the flowing water prevents exces- sive accumulation on the outside surface of the membrane. Nutrient Solution Is Circulated at a slight tension in a cavity filled with plastic screen and covered by a porous plastic membrane. By adsorptive attraction, the root draws solution through the membrane. Root hair was strongly developed and roots were healthily branched. The roots are thus supplied continuous- ly with water and nutrients as well as with air, while the flow of the solution is con- trolled. Capillary forces in the membrane help to regulate the flow. Tomato plants grown in a prototype of the apparatus were similar in size and shape to those grown in a more conventional hydroponic trough with a thin film of flOWing nutrient solution. This work was done by Bruce D. Wright of Colorado State University for Kennedy Space Center. For further information, Circle 68 on the TSP Request Card. KSC-11350 92 ~~~~~~~~~z~~;onia Fibe .... Based Materials offer Umitless possibilities When you need exceptionally high tempera- tures, low thermal conductivity orresistance to chemical attack, choose one of Zirear's Zirconia fiber-based materials. Bulk fibers, flexible textiles, rigid boards or cylinders: nobody knows how to take Zirconia to the limit like Zirear! ~~) Z!:!:!?u~r. P.O. Box 458, Florida, NY 10921 Tel: (914) 651-4481 Fax: (914) 651-3192 Circle Reader Action No. 323 SpaCial Ollar Celebrate Amer- ica's return to space with this high-quality sweatshirt from NASA Tech Briefs. Striking four-color design of shuttle Atlantis on white cotton blend shirt. Available in adult sizes: S, M. L. or XL. $16.95 each + $3.50 postage and handl- ing. (NY residents add sales tax.) Special Bonus: Order now and recilvi a FrM Full-Color NASA Spece Poster! --------------------------- Rush me Atlantis sweatshirt(s) in the following size(s): (please circle) S M L XL Total Enclosed: $, _______ _ Name Company ________________ __ Address City _______ State. ___ Zip _____ _ Men to: NASA Tech Brief., Dept. F, 41 Eest 42 St., New York, NY 10017 Remember: Order now and you will receive a free NASA poster with your order! NASA Tech Briefs, December 1991 New on the Market ,Tsun Microsystems, Mountain View, I CA, has introduced the SPARC-en- gine® IPX'M, the first single-board computer to include built-in graph- ics along with a RISC processor and networking. Powered by a 40 MHz microprocessor, the SPARCengine IPX offers 24.2 SPECmarks perform- ance. It supports the OpenWin- dows 'M environment, which fea- tures the intuitive OPEN LOOK® graphical user interface and 15 DeskSet'M productivity tools. Pictured above is a new pre-engi- neered construction system from Crystal Mark Inc., Glendale, CA, that produces rigid frameworks using extruded aluminum frame members and aluminum diecast corners fastened by concealed bolts. Complex enclosures can be created from over 50 angled extru- sions and matching corner castings. Circle Reader Action Number 790. Virtual Prototypes Inc., Montreal, Quebec, has released version 2.0 or VAPS (Virtual Applications Proto- typing System), a pictorial software tool for user-interface prototyping, automatic code generation, real- time simulation, and training. Suited for de ign of avionics and console displays, VAPS rapidly creates and animates display console using graphical objects. An advanced communications package enables its virtual prototypes to interface with other software programs. VAPS 2.0 runs on Iris 40, Indigo, RS/6000, SPARCstation, and HP 9000 Series 700 computers. Circle Reader Action Number 800. BeamGrabber, a new laser beam diagnostic system from Photon Inc., Santa Clara, CA, quickly and cost- dfe lively tunes lase, avilie~ :;::';:'""3":.:-"""'" Unilsb Regul.ted Work Aru s. Cltl/ 816-796-2900 HEMCO CORPORATION 111 N. Powell Independence, MO 64056 USA Circle Reader Action :.:Nc::o-'-• ...:4.=6.=3 _____ --i Probably not to us! We offer such a rare combinaflon of non· metallic materiats expertise and fabrication capabilities, that to us, most unusual requests are not surprising. From non·sparking fin covers for the Tomahawk cruise mlssle to vibration·tested, static·protectlve shipping containers for high value computer chips to non-adhesive laminated components for hazardous waste containment, we've produced thousands of die-cut. laminated, machined or molded products. In fact, our list of capabilities reads like an industrial directory. And our materials knowledge IS considered a valued resource by many of our customers. If you have a requirement which seems unusual, or even impossible, give us a call. We can help you. And we promise not to be surprised. • INDUSTRIAL CUSTOM PRODUCTS,Ltd. 5200 Quincy Street· Mounds View, MN 55112 (612) 785-2266· Toll-free (800) 654-0886 • FAX (612) 785-1577 Circle Reader Action No_ 412 New on the Market Maxwell Laboratories Inc., San Diego, CA, has devetoped a tine of miniature doubte-ended capacitors for use in putsed etectronic circuits of high-power lasers. Constructed of foil polypropylene, the capacitors have up to 25 times the capacitance of ceramics and exhibit a smaller temperature coefficient of capaci- tance. Additional applications in- clude filters for high-voltage DC power supplies, electrostatic copy- ing machines, electron micro- scopes, and CRT power supplies. Circle Reader Action umber 716. Photometrics, Tucson, AZ, has pro- duced a digital, cooled CCD cam- era integrated with powerful image (---------------i processing software running under A video optical inspection system designed by Flexbar Machine Corp., Islandia, Y, enables users to view surface finishes at the macro or micro level, to determine deviations from standard dimensions, and to verify to lerances. It incorporates a compact video camera, micro- zoom or macro-zoom lenses, and a video monitor. An optional video micrometer superimposes a cali- brated screen on the monitor for accurate and repeatable mea ure- ments of distances and dimensions. Circle Reader Action Number 718. The Light Brigade, Renton, WA, has produced a series of fiber optics training videos. The first in the series, Introduction to Fiber Optics, covers optical theory and fiber structure. Other tapes describe fiber optic cable and preparation, splic- ing and characterization, testing and troubleshooting, lasers and de- tectors, and applications. Circle Reader Action Number 728. Windows 3. The model ATC200 camera provides 12, 14, or 16 bits/ pixel over spatial resolutions from 512 x 512 to 2048 x 2048 pixels. It is suited for applications requiring low-light imaging, low contrast de- tection, or wide dynamic range . Circle Reader Action Number 724. A 5-GHz fiber optic transmitter introduced by Ortel Corp., Alham- bra, CA, uses a distributed feedback laser with a single optical line to make dispersive effects virtua ll y nonexistent, improving transmis- sion quality over long distances. The model 3540A transmitter is equipped with an optical isolator that reduces overall loss in the fiber optic link by 10 Db. The device transmits analog microwave signals over Single-mode fiber at 1300 nm optical wavelength. Circle Reader Action Number 726. ---------j Ariel Corp., Highland Park, J, has The Video/1 product family from Psitech Inc., Fountain Valley, CA, provides high-speed compression, decompression, and display for real -time video applications. A JPEG proce sing card, accepting any RS-170, NTSC, Pal, or Secam signal, captures an image frame and stores up to 8 MB of local memory. It supports compression ratios of up to 200:1 . An image display card de- compresses and displays images on a high-resolution buffer at 30 frames per second for full motion or still video capabili ties. Circle Reader Action Number 722. introduced the V-C40, a VMEbus coprocessor board that delivers twice the processing power and four times the input and output bandwidth of current 6U VMEbus coprocessor cards. Its four TMS- 320C40 DSP chips deliver process- ing power of 1.1 BOPS and data movement of 1 .3 Gbytes/sec. Each chip has two independent 32-bit address buses and six 20-MB/sec parallel interprocessor communica- tion ports. Applications include speech and pattern recogni tion, simulation, and virtual rea lity. Circle Reader Action Number 720. NASA Tech Briefs, December 1991 New Literature Dynamic Pressure Measurement Technology, a new textbook from Enclevco Corp., San Juan Capis- trano, CA, emphasizes applications and practical techniques for meas- uring dynamic pressure phenom- ena. Featuring over lS0 illustra- tions, the text reviews the basics of pressure transducer selection, in- stallation, signal conditioning, and calibration. Circle Reader Action Number 710. Rexroth Corp., Rockford, IL, has re- leased a catalog of pneumatic servo systems and components. The 20- page publication describes fea- tures, specifications, dimensions, and appl ications, as well as pro- gramming capabilities and configu- rations. The systems provide posi- tioning accuracy up to ±.0004" and speeds up to 11 .S ft/sec using modu- lar NC-controlled linear actuators, which serve as building blocks for custom multi-axis systems. Circle Reader Action Number 708. A six-page optical table specifica- tions guide is available from Kinetic Systems Inc., Roslindale, MA. The publication details the performance characteristics and configurations of the VIBRAPLA E line of optical tables and describes isolated and nonisolated support systems. Circle Reader Action Number 714. A catalog from Mechanical Prod- ucts Inc., Jackson, MI, features high- precision circuit breakers in con- figurations from O.OSA to 200A. The new Series 24 switchable circuit breaker offers single- and two-pole protection and a lighted power switch or optional toggle handle. Circle Reader Action Number 702. A full-color brochure describes pre- cision machining services available from Westinghouse Electric Corp.'s Electro-Mechanical Division, Pitts- burgh, PA. The firm's automated flexible machining cells machine f----------------J parts up to 2500 pounds at toler- ances of 0.0001 inches. Operators are experienced in machining nu- clear-grade components and work with a variety of materials including Inconel, carbon steels, and many grade of stainless steel. Circle Reader Action Number 706. Principles of Temperature Control, a 24-page tutorial, is offered free of charge by West Instruments, East Greenwich, RI. The booklet's four sections discuss the control system, load characteristics, control modes, I and process control characteristics. Circle Reader Action Number 704. A four-color brochure from Hobart _ • • Tafa Technologies Inc., Concord, NH, describes HAWCS II, an inno- vative robotic motion and process control system. The hardware and software system enables complete control of robotic thermal spray or welding cells from a single console. HAWCS II can be incorporated into turnkey systems for thermal spray- ing (plasma, electric are, HVOF, or combustion), welding (VPPA, MIG, Dabber, TIG, or PTA), and waterjet stripping of metal coatings. Circle Reader Action Number 712. NASA Tech Briefs, December 1991 FOCUSED FIELD ROTARY TRANSFORMERS ~r----"'-~"'----, Non-contact Stationary-to-Rotary links for Power Transfer Measurement Signals o Zero Wear. o Zero Friction. o Zero Maintenance. o 20,000+ RPM. o Single or Multiple Channels. o Use with Variable Resistance Transducers: • Strain Gages • Thermistors • RTO's • Potentiometers o Power to 4S0W {@220VAC, 60HzJ By eliminating all physical contact between rotating and stationary components. the new Focused Field Rotary Transformers provide stable electncal connections which are unaffected by high rotating speeds and/or continuous operation. meridian laboratory ~~~;n~~ ;3562 800-837-6010, or 608-836-7571 (FAX60a..aJ1.0JOOI Circle Reader Action No. 344 LOOKING FOR A RUGGED, RELIABLE MASS SPECTROMETER LEAK DETECTOR? LOOK TO AMETEK'S 1120H * Easy to e maintain, easy to operate unit with unique Diatron-4 T. detector element can sense helium leaks in pres- surized or evacuated parts and ra~;t-alctln,a 1.5 second response time. The Model 1120He with electronics is sensi- tive enough to detect one part of helium in 10 million parts of air. Minimum detectable leak rate: 5 x 10" atm cc/sec of helium. Units also available for argon detection. For technical literature, contact AMETEK, Process & Analytical Instruments Division, 150 Freeport Road, Pittsburgh, PA 15238. Tel: 412-828-9040. Fax: 412-826-0399. AMETEK • Pre\'1OUSly marketed as DuPont 12OSSA; krts fo< UpdatIng unrts wrth soIid·state elec- troOlCS available. PROCESS & ANAlYTtCAl INSTRUME TS DIVIStON Circle Reader Action No. 436 Q5 96 MARKETPLACE QAP I QulkkJ Array Processor FINAllY, A DSP SOLUTION TO GENERAL PURPOSE COMPUTING APPUCATIONS I r¥ 25 MFlOP performance using the OSP32C and up fo a megabyte of fast dedicated memory Q" Un1Que onboord software system (QAPOS) makes the QAPI a stond olone OSP computer. reody to taclde your most complex applications - and you won't hove fa write 0 &Ingle line of 0SP32C code W The ESSENTIAL COMBINATION ~ complete hardwore and software system with 256K RAM - $1000 IT Colt or write for more Information and brochures TU C K ER · DA VIS TECHN O LOG I ES 4647 N.W. ¢th Street. Gainesville. Fl 32609 Phone: (\Q4) 375 · 1623 'al" (904) 375 · 4523 Circle Reader Action No. 444 SMALL PROFILE, BIG FEAlURES!! The Super Slim (0.65") 0.9 degree step motor is light weight and designed for high performance motion applications. Serviceable dual·ball bearings and a stainless ,~ steel case insure exceptional long life. Holding torque is 9 oz·in. The torque curve, which is remarkably flat, can be increased 1.4 times if an adequate cooling surface is provided to the mounting face. Although the motor is NEMA 16, the mounting holes match standard NEMA 17 frames. Available in single or double shaft. Four lead wires are standard. MOTION PRODUCTS PO Box 4585, Mountain View, CA 94040 800·424·STEP Circle Reader Action No. 409 Imagine it with superior EMIIRFIIESD shielding, electrical and heat transfer properties. Imagine a lightweight metal foil with a mesh·like, single·unit structure that eliminates the unraveling and contact resistance of woven mesh. PEM" SELF-CLINCHING & BROACHING FASTENERS • strong, quality threads in metal and P.C. boards too thin to be tapped. • variations include free- running, self- locking, floating and blind hole types meeting Unified, ISO and MIL standards. • Available in steel, stainless steel and aluminum. For your FREE condensed catalog, circle the number below. However, for a complete fastener specifications & deS~ndata cata- log, call 1-800-237-4736. Or /l:X us at 215-766-0143. 104 e 1991 Circle Reader Action No. 340 ARE YOU STILL TRYING TO MEASURE VERY THIN GAPS THE HARD WAY? Capacitec HPS Series of thin (back to back) sensors c an measure gaps as small as 0.010"(.254mm) inboard 84 " (2133.6mm) with accuracies of 0.0003" (7.6",m), without scratch ing delicate surfaces. ;: Capacitec P.O. Box 819, 87 Fitchburg Rd ., Ayer, MA 01432 U.S.A. Tel. (508) 772·6033 • Fax (508) 772·6036 Circle Reader Action No. 385 RELIABILITY - AND MAINTAINABILITY PREDICTION AND fMECA ANALYSIS SOfTWARE Hundreds have used this leading computer-aided engineering software since 1982. Powertronic Systems offers software to predict Reliability and Maintainability and for Failure Modes Effects and Criticality Analysis. Hundreds of users have selected from PSI's large, versatile and integrated software family for military and industrial equipment and for both electrical and mechanical systems. And. these programs are either interactive or can Oe input from batch modes from existing CAE or database programs. Programs implement MIL·STD·1629; MIL·HDBK·217 including E Notice 1; and MIL-HDBK·472. I PSI I Powertronic Systems, Inc. P.O. Box 29109 New Orleans 70189 (504) 254-Q383 FAX (504) 254·0393 Circle Reader Action No, 560 490-3999 Airborne DAS Records Data on Videocassette ME980/990 Data Acquisition Encoder! Decoder system com· bines 2000 to 590,000 data with composite video on standard VCR format. Merlin 1888 Embarcadero Road Palo Alto, California 94303 (415) 856-0900 • FAX 415/858-2302 Circle Reader Action No. 339 FREE! 130 Page Catalog "Optics for Industry" Fre~ 130 page product catalog from Rolyn, world's largest supplier of "Off·the-Shelf" optics. 24·hour delivery of simple or compound lenses, filters, prisms, mirrors, beamsplitters, reticles objectives, eyepieces plus thousands of othe; stock items. Rolyn also supplies custom prod· ucts and coatings in prototype or production quantities. ROL YN OPTICS Co., 706 Arrowgrand Circle, Covina, CA 91722-2199, (818)915- 5707, FAX (818)915·1379 Circle Reader Action No. 551 DATA ACQUISITION PRODUCTS for the PC Filled with applications information, competitive comparisons, waveform analysis techniques, hardware and software specifications, and DEMO DISK! We manufacture the industry's fastest dala acquiSITion hardware and software designed for applications that demand a true real time display with simultaneous disk ~a~lI.u~s ~at~ ... . ~ .... _ i:t·t.'{jlt.Ief_ DA TAQ INSTRUMENTS, INC 825 SweilZer Avenue Akron. Ohio 44311 Tel(216)434' 4284 Fax(216) 434 ·5551 Circle Reader Action No. 489 NASA Tech Briefs , December 1991 -------------------------------~------------~--------------------------------------------- MARKETPLACE To Advertise-Call Build Your Own Space Shuttle Fuzzy logic • ~ MS Windows·based tool CublCalc for non-programmers Simulate system response using built-in expression interpreter or apply fuzzy rules to file data Plot results or log numerically CubiCalc RTC for programmers includes run-time compiler and deployable modules INTRODUCING RACK MOUNT AND RUGGED Also available ... The OWL Neural Network Library SUN SPARC WORK STATION Standard Features Include: HyperLoglc Corporation • Spar1< Engine 2 CPU with 16MB RAM This 1m scale model of the space shuttle Discovery features a huge 13" wingspan and in· cludes engraved tile detail, movable rudder and flap, authentic NASA decals, adjustable manipulator arm, opening cargo bay doors, and detailed Spacelab payload. Molded in white. KIts are $7A.95 each + $4.00 postage and handling. (NY residents IKId sales tax.) Send check or money order to: I'IA8A Tech BrIef., 1855 East Valley Parkway, Suite 210 Escondido, Caiifornia 92027 • 207 MB Hard Disk, 150MB Tape Drive • 644 MB CDROM, Removable Hard Disk • 1.44 MB Floppy, 2 R5-232 and S Bus Ports Tel 619f746-2765 Fax 619f746-4089 Dept. F, 41 East 42nc1 SL, I'tew York, /'tY 10017. For crecllt card call (BOO) 258·0201 (/'tY ablte: • SCSI-2 and Ethernet Interface • 16-inch Rack Mount Color Monitor • Keyboard, Mouse and SunOS 4.1 For further details contact: IBI Systems Inc., 6842 NW 20M Ave., Ft Lauderdale, FL 33309, 305-978-9225, Fax: 305-978-9226 Circle Reader Action No. 660 Climb aboard the world's best fighter air- craft-the F·16 Falcon, F·15 Eagle, and F·111-for high flying adventure! This action· packed VHS videotape features real combat footage. $19.95 each plus $4.50 postage. NY residents Get AutoCAT Name Address City add sales tax. for only $295.00 and save $200.00 before January I, 1992! Don't mISS the bus! Software for IBMTM or compatible computers to Automate Computer Aided Ie ts. Performs lab measurements and production test . Interfaces with IEEE-488, RS232 devices. Mouse, pull-down menus, on-line help. CERAMIC SCISSORS Designed to cut Kevlar· cloth and yarn. Zirconia blades mounted in reinforced nylon frames. • Excellent for general laboratory use • Lightweight, sharp and durable • Easily Sterilized • Non-magnetic and non-conductive State Zip __ No programming knowledge required. • Gift boxed Total enclosed: _____ _ for ___ Jet videos. Send check or money order to: NASA Tech Briefs, Dept. F 41 East 42nd St., New York, NY 10017 ~ Subject ~ Index !---~"--" A ACOUSf1C MEASUREMENT New sensors tot b ...eklcIry and acoos;llCS page 76 AACl2571 AfAO£lASIICITY F~.a;,malf'l~ life8hon ci &efl)8taS11C modes page 73 AfC..124()7 ALGORITHMS --- .......-""""""",,,, """"- page 86 MFS29688 ..... AlYSIS (MATHEMATICSl Integrated analySIS ~poogD page 31 AFC-12712 NASA Tech Briefs, December 1991 NEDSI 44 I 5B Enterprise Court. Melbourne, FL 32934 Phone: (407) 259-2090 Fax: (407) 255-0274 B BAll BEARINGS Monttorlng bearing vb .. 1000b S9'1S0I - page 78 MFS29734 BAlLOONS UghtweighI valve closeS """'_ page 64 MFS28S11 BEARINGS t>,onamc IeSteI b rob sealS and bearlOgS pogo 80 MF5-""'93 MonIlOIlng t:leaIlnQ Ybfa- IlOnSlotSlgl"lSoI - page 78 MfS.29734 MonIlOrf'lg engtne 'libra tOll lor spec:tnIn 01 - page 79 MFS29733 BLOOD PUMPS NI.meOcaI smJIabon 01 fbNtJ'vouVIananlCl8l -. page 66 Af&12.78 BOLDMETERS Q'IiIraclenlahon ci etec· Ircal response 01 - page 2. GS(;t3349 BOUNDARY LAYER FIDW A general-coordlna1e lor· t1'IU&all()'l lor boundary _!\ow page 59 Af&12~ BOUNDARY LAYERS ReclJcng waterlbJl ci"ag bV InfeCting all' V'IIO - page 59 LAA·I4()78 c CALCIUM CARBONATES lr'r'pegnetlf"lQ coal wnn caIcun camona .. page 46 NP().I7696 CAU8RAT1NQ Program calibrates strain - page 52 MSC21399 CARBON DtOXJOE LASERS Automatic re,ect1Ol'l 01 """""""' ........... page 2. NP().lnn CHARGE COUPLED DEVICES Ahemg IfltetWlelra"lSlet lnaCXOtDreciJce .....,"" C»g8 30 NPQ.I1935 CIRCUrTS AulOmlle retecuon 01 trultlfnOde Iasef pJIses page 2. NP().lnn Widet:lrd phase-Iocked angle rnoOJIoIor PIgS 36 Np()'181)47 COAL ~8g\811f'1Q coal WIth calcun carbonate a:-ge 46 NPQ.17696 COMMUNtcATlOH SATElUTES Estrnaung rain 81tenoa hon In sa"le com- mncat"'" inks PIoe ~ lEW 1.979 COMPOSITE MATERIALS ~_. page •• lAA--'·'59 COMPVTATtoN l1ltarycf~ In FOR1'RAN 77 page 55 Np()'18120 COMPUTATtoNAl FLUID DYNAMICS Arltfcallf'llellgence In CXlt'f1)UtIIIOI'Wt IUd "'""'"'"' page 73 AF!C1244S c.onv.rta'ICQi 01 m- pulslvely starled vtscous now page 75 ARC-12382 COMPUTATIONAL GRIDS GeneI~bon 01 surtace gnds fr()'1'l data jXlIf'ItS page 86 ARC-120681 COMPUTER AIDED IlESION --"'" p'ogIQINEERING IIAHAo(lEMEHT bcr4I_c:cnIRlI '" ~Iflgrequeremeru page 56 Np()'18215 EOUATlONS OF STATE CobAaIong - . -"-'" 12 ..... _ 52 MSC21664 EYE MOVEIoIENTS ........................ oaJiat~ page 91 MSC21711 F ",. .... RCRAFT --""'1'U'O-tIOfW; on zonal "lOs page 71 AFC12447 ANITE DlFFEI\ENCE THEORY Ov8C1 Inl&dtlefence sin.Aahcr. of tu'bAant IIOw pegs 76 ARC-12463 FlIGHT COHTROl ..., .. omAaIong_ IligIlIcxnr",..-no pege 56 N&117m FUGHT MANAGe. MEHT SYSTEMS _'IigIlI. slalus morYIDr page 31 AfC.12712 AERo=a.J AEROSPACE CONTRACT MANUFACTURERS Where Buyers Have it Made! February 19, 20 & 21, 1992 Long Beach Convention Center, Long Beach, California SERVING: Air Transport, Space, Military, Ground Support, Civil Aviation, Interior/Exterior Furnishings & Supplies, Overhaul & Maintenance and Avionics. EXHIBITORS Aerospace-qualifuu/ job shop, and contract mtuJu/actlUers with expert capabilitie' ill A "wnic" Metal Working, Plastics, ComposiUs, Rubber and suppliers 0/ Components, Parts, Test Equipment and Materials. FOR INFORMATION TO EXHIBIT OR ATTEND FAX 1-313-643-0856 or CALL 1-800-635-9885. AJJW EOUAT1ONS _.. - .. ~ -- ~5Q AAC-12.t65 -"""""'" "" ""'n..........., - pege ff1 AAC-12fi09 AJJW VISUAUZAT10N -....-... rNgery CIl • perscnaI ~ _ ee "':;'12267 FUJlD DnWIICS ArtIfIClilf neIigence ., ...,..- ..... - page 73 NC-12.u5 FOfITAAH lbwy"'-n FORTAAN n page 55 NP().18120 FOUAlEII TRAHSfOAMIJ1ON a.r.cterll3ton of eIee· tfCaI resp:qe of ..-.. page 2' GSCl3349 FUB. CEllS -............ - page 38 MF&28S15 G GAS lMEIIS AuklmaIIC re+ectm 01 .,..,..--..- page 24 Nf'O.177n GAS TUNOSTEN ARC WELDING SmaJIor """""'- _""ch page 82 MF&29744 GEIIMtNAT10N CapiIaty-eIted rOOl- -- page 92 J<9:..11350 GOLAY OETECIOA CElLS a.ac1efIl3bQn of e6Bc "leal response ci -"""" page 24 GSCl33d9 r - - - - -*Co!'2.~'!!l' !!£.ke~.,!!i~IeJ2rs...uaIJ!i~_ .. ~d~. _____ , I CMEIAEROCON 92 Dexhlblt Dattend I I NAME I I COMPANY I I I I ADD~ I I CITY, STAlE, ZIP I I PHONE &. FAX I L____________________ __~ 98 Circle Reader Action No. 636 GIWlNGS I$PECTRAI --~ 38 NPC).18011 -"",_ .. ...---- _26 NP018OS4 GROUND BASED CONTROl -1IqoI- ............ ~31 NCt21t2 H HAND !ANATOMY) 0._"- PIQI! 78 NCll666 HEART N",nencal~oI now 1hn:u;t1.-. artlflO8l ~ page 66 NJC, 12478 HYPERSOHlC FlOW Con1>Uted hypeIv"OI """"eel"""""'" page 22 ~18m'I17946 J JOINTS \/UNCTlONSj --'" eWing ..... "'1ruOs stn.octues c-ge 62 LAR-14306 L LARGE SPACE STRUCTURES __ In- eWing ..... "'''''''' SIn>C1uOS page 62 lAA 143)6 lASER MODES .AueomatICre,ectlOnot .......--..- page 24 NPQ.lm7 lASEI\S _.,.Iongsloo- _ , page 26 NPCH~ lJOIIDS CaIcWIong .... _..-", 12 ...... page 52 M&:;.21664 lDCKS (FASTENEI\.S! Lock lor vaNe llem page 63 MFS-2976o' M ...... AGEMEHT lacll"lg .-d contrd Of engreerng feQI.Wernencs PlOt 56 NP(H8215 MAHIPUlAlORS OwecHn prehenaot page 78 AfC.11666 MATHEIIA1ICAl. MODElS GenonIJon '" _ ---- ~86 N&12~1 _ .. -.on" ........ , .. _'"- _55 MSC211D8 MEASURING tNSTRUMEHTS --... - c:.ge 38 MfS.28S1S _VEIMAGERY -- "-' page "2 NP().17'094 N NAVlEA-SroICES EOWmON " genetak:oordinMe lot _ .. """""""'- ...... -page 59 AAC-12465 Carc>uIatoono '" .... ---page 75 AACI2382 CuIed~ VISCOUS tIows 0tIef delta - page 70 AAC-t2179 Owect r~ence SomJIaIIOrlS 01 tt.WtlUenl ""'" page 76 Af4';.,2463 Wett'ods of si'nJlatO'l of ............... -page 741 AACl2199 --"""""'"" ~onZO'\algrds page 71 AA:;t2 .... 7 Nt.mefcal smuiallOl'l 01 now ftwoI..9\ an arutic1al heart page 66 AFC,2.t78 NEURAL NETS -- _... MSC21638 NUMEJUCAL ANAlYSIS Generaoon at su1ace grids from page :K) Nf'O.l7935 SOliD STATE LASERS 'JM>pet1Od gralngll lOr ...-ng ....... page 26 NP().18054 SPACE AlIAPTATION SYNDROME Instn.rnenl measures 0CI.00r counIetectS page 76 AF&12463 page ro AAC-12179 .. _ page 56 MSC2170B Methods 01 sirrulallOfl at _eo NPC).17889 V """"",....,."Iow Till ROfOR AIRCRAFT page 74 AAC12199 SUBSONIC WIND F'~ TUNNElS damtcatO"lol VALVES VOIl'AGE Experrneoll on schemes 88I'OEKaStlC modeS --.-. CONVERTERS lOractapt....-walWl"lCf page 73 AAC-124()7 """"'" -- (DC lO DC) pogon AACl2116 page 54 UF&28511 ~dIrec1<_ page 28 NP().17957 SYNTHETlC ~"""" page 63 "'FS-2976< APERTURE RADAR page 82 MF&29744 W _ Processes SAA VAPORS cOl .. lORSION Colcutal"ll """"""*" page 52 NPC).l8048 InYestlgatlOf"l at lapefed cal pt'opertl8S at 12 flIkX I9t'1S1Ct\fk)rSlOl'lStf~ page 52 MSC2166< WATER vatlCtES T page 68 AAC-12480 AeciIcng waler/tlA \:Wag VlBRATtON I:PJ W1feet1ng air fto TRANSONIC FWN Hgor~ r8Y981s - TB..ECOMMUNICATtON NIM8f~CQI'TClUta- .......,....,,,,,,,,,,,,,,,,,,, pogo 59 lAR-l.t078 E.strnm1g ran atten..e- bOnI on zonal grOs ,.,..,- bon In sateIIi1e can- _71 AfC,12u7 _86 MFS-29688 WElDING .....-.on ..... ~-_48 LEW-14979 TRUSSES VIBRATION o.\MPING ~"""" --'" "" tecInQueS tor ...,. page 82 UF&29744 TEST EOUIPMENT ckdng joInla at truss pressing vb'a11OllS In [)ynamIc lester lor roIOf .,_ structures WIND TUNNElS seals and bearings pogo 82 LAR-14306 _eo NP().17889 New sensors lor flow page eo UF5-28493 ""te<:Itnq.Ms""'" WIOclty and aooustJCS VIBRATION page 76 "'::'12577 THERMAL AHAlYSlS pres5lOQ 'o'baticl'll 11 MEASUREMENT 1n1egcpemons .., --page 54 GS:;.13341 TURBINE PUMPS - tor __ wrd pogo 78 MFS29734 IUMOIs THERMAL RADlATION ()ynamic tester tor rt*)f -"II """"" vin· _n AfCl2116 Scr(Jt·&ictcw fTWldeting at seoIsand_ hons tor apectnnI 01 page eo MFS-28493 abscIq:lClOf"Iln. SOlar exI1aUSI X ''''''''''''' TURBULENCE page 79 UF5-29733 page 40 NPC).18)18 Malhamalical modets 01 turbulence In hyperlilOl"lC VISCOUS FII1W THERMOPHYSlCAl ~tabon.oIlT"pj. XV-iS AIRCRAfT PROPERTIES llow F_idon-pogo fir "'::'12609 SIVI.!if s&an9d WIOCIa bY Ca6cula11l"lg thermoptYyst- page 75 "'::'12382 tlficallOl'lolaeroelastic calpropertesoll2~ ...... page 52 MSC21664 pogo 73 AAC1Z4()7 Editor's note: A subject index of all tech briefs published in 1991 will appear in next month's issue. NASA Tech Briefs, ISSN 0145-319X. USPS 750-070, copynghtC 1991 in U.S., is published monthly by Associated Business PublICations Co., Ltd., 41 E. 42nd St., New Yorl<, NY l0017-539t. Tha copynghted Information does not include tha (U.S. rights to) individual tech brlefs which are supplied by NASA. EdHorial, sales, production and circulation offices at 41 East 42nd Street, New Yorl<, NY 10017-5331 . SubscriptIOn for non-qualified subscribers In the U.S. , Panama Canal Zone, and Puerto Rico, $75.00 for 1 year, $125.00 lor2 years; $200.00 for 3 years. Single copies $10.00. Foreign subscript"",s one-year U.S. Funds$150.00. Remit by check, draft, postal, express orders or VISA, MasterCard, and Amencan Exprass. Othar remittances at sende(s risk. Address all communications lor subscriptions or circulation to NASA Tech Briels, 41 East 42nd Street, New Yori<, NY 10017-539t . Second-class postage paid at New Yori<, NY and additional mailing offices. POSTMASTER: pl •••••• nd .dd .. ss ch.ng •• to NASA T.ch B,I.f., 41 h.t 42nd Street, Suit. 921. N.w York. NY 10017-5391 NASA Tech Briefs, December 1991 99 We do Windows And floors. And walls. Use Plot-IT to turn complicated ideas mto comprehensive graphs. QUickly and easily. [, (1II11 1 II \\ \ • Over 60 graph types including 3D • Ultra sharp graphics In full color • Perform spreadsheet tasks with Plot-IT Worksheet • User-customized FORTRAN functions support • WordPerfect® and Ventura® compatible And remember. we do Wmdows. Microsoft Windows® operating system. that IS. And IBM OS/2 For a free brochure describing all the Plot-IT features. write or call now Scientific Programming Enterprises POBox 669 Haslett. Michigan 48840 (517) 339-9859 · FAX 1517) 339-4376 ~ Plo·-IT f~J[_SlS II Circle Reader Action No. 408 • Temperatures to 5750 F • Low friction, wear resistant materials • Unlimited shelf life - permanent elasticity • .pressure ratings from vacuum to 60,000 PSI • Diameters from 1/16 to 150 inches .~AMERICAN E\.T VARISEAL p.D. Box 1479 Broomfield, CO 80038 (BOO) 466-1727 FAX: (303) 469-4874 A division 01 W.S. Sham ban & Co. Turcite is a registered trademark 01 W.S. Shamban & Co. 100 Circle Reader Action No. 486 Pru!TENTS Over the past three decades, NASA has granted more than 1000 patent licenses in virtually every area of technology. Sales of licensed inventions exceed $10 million, and royalties paid to NASA approach $1 million. The Space Agency has a portfolio of 3000 domestic and foreign patents and pending applications available now for license by busi- nesses and individuals, including these re- cently patented inventions: Real-Time Data Compression of Broadcast Video Signals (US Patent No_ 5,057,917) Inventors: Mary Jo W_ Shalkauser, Wayne A. Whyte, and Scott P_ Barnes A new cost-efficient system digitally codes and decodes broadcast video signals in real time using differential pulse-code modulation. It employs nonuniform quantization and mUl- tilevel Huffman coding to substantially reduce the biVpixel ratio, and a nonadaptive predictor to improve the edge encoding performance. Circle Reader Action Number 741 . Process for Application of Powder Particles to Filamentary Materials (US Patent No. 5,057,338) Inventors: Robert M_ Baucom, John J . Snoha, and Joseph M. Marchello A novel process uniformly and continuously applies polymer powder particles to a filamen- tary material to produce a uniform composite prepreg. A tow is fed under controlled tension into a spreading unit and spread pneumati- cally into a band_ It then is coated with polymer particles from a fluidized bed and fused prior to take-up on a package. The process does not impose severe stress on the filamentary material, nor require long, high-temperature residence times for the polymer. Circle Reader Action Number 743_ Mechanized Fluid Connector and Assembly Tool System with Ball Detents (US Patent No_ 5,058,929) Inventors: Ronald C. Zentner and Steven A_ Smith A versatile fluid connector and powered as- semblytool is easily operable using one hand . It features a self-aligning structure for quick and accurate attachment and removal of the tool from a modified plumbing union used to join pipe segments, and an electric drive motor that enables control of speed, torque, and direction of rotation. Circle Reader Action Number 745_ Regenerative CulLa Zeolite-Supported Desulfurizing Sorbents (US Patent No. 5,057,473) Inventors: Gerald E_ Voecks and Pramod K_ Sharma The inventors have produced metal ion- exchanged zeolites that remove more than 50 percent of the organosulfur compounds from diesel fuel and other fluid hydrocarbons at moderate temperatures, resulting in cleaner emissions_ The zeolites can be repeatedly regenerated without loss of activity, providing an efficient desulfurization system for use in petroleum refining, natural gas processing, utilities, and chemical processing plants. Circle Reader Action Number 747_ Brominated Graphitized Carbon Fibers (US Patent No. 5,059,409) Inventor: Ching-Cheh Hung Bromination of graphitized carbon fibers re- sults in a three-fold increase in their electrical conductivity. Mr. Hung's process employs low-cost, high break elongation carbon fibers that have a low degree of graphitization. The fibers, which are inert to bromine at room or higher temperature, are brominated at _7° to 20°C and then debrominated at ambient tem- perature. Repetition of this process can bring the bromine content to 18 percent. Circle Reader Action Number 749_ Rapidly QuantifYing the Relative Distention of a Human Bladder (US Patent No. 5,058,591) Inventors: John A _ Companion, Joseph S. Heyman, Beth A. Mineo, Albert R. Cavalier, and Travis N. Blalock A small , inexpensive bladder monitor ad- dresses incontinence problems in mentally retarded persons and can assist those who have lost bladder control as the result of diabetes, cerebral palsy, advanced age, or other reasons. An ultrasonic transducer worn near the bladder is excited by a microproces- sor-controlled pulser to launch an acoustic wave. The wave interacts with the bladder walls and is reflected back to the transducer for processing. The resulting signal is digi- tized and stored in data memory. Software determines the relative distention of the blad- der based on the subject's past history and can transmit a signal to sound an alarm. Circle Reader Action Number 751 . Passivation of High-Temperature Superconductors (US Patent No. 5,059,581) Inventor: Richard P. Vasquez Mr. Vasquez has developed a technique for passivating high-temperature superconduc- tors without degrading their superconducting properties. The surface of a superconductor such as YB~Cup7_x is passivated by react- ing native Y, Ba, and Cu metal ions with an anion such as sulfate or oxalate to form a surface film that has a solubility in water of no more than 10-3 M. The passivating surface layer can be formed by wet chemical techniques, by gas-phase reaction, or by deposition. Circle Reader Action Number 753. For more information about the inventions described above, including licensing proce- dures, circle the corresponding number on the Reader Action Request Form (page 83). NASA Tech Briefs, December 1991 liME AlilitW RKS 'RODUCES Block Diagram Software for Nonlinear Simulation of Dynamic Systems ntroducing SIMULAB, the next genera- tion software for modelling, analyzing, and simulating nonlinear systems. SIMU- LAB delivers a combination of flexibility, ease of use, and speed in a single package. • A complete set of tools for constructing and analyzing models of dynamic systems, including \jnear, nonlinear, discrete, contin- uous, and hybrid systems. • The ability to describe models either in Block Diagram form or as sets of differen- tial equations. • A design, analysis, and simulation environ- ment that is seamlessly integrated with MATLAB'" and the MATLAB Toolboxes. • An intuitive graphical u er interface based on the industry-standard X WindowlMotif and Macintosh windowing systems. Circle Reader Action No. 503 SIMULAB provides you with the tools for constructing and analyzing block diagram models interactively using a mouse and pull- down menus. You can explore the behavior of systems during a simulation and interac- tively see how the model's behavior changes as you change its parameters. SIMULAB includes a comprehensive set of built-in blocks for creating models. In ad- dition, SIMULAB lets you extend its func- tionality by creating your own tools. Cus- tomize built-in SIMULAB blocks or create your own as C, Fortran, or MATLAB code. SIMULAB delivers the flexibility to meet your needs. SIMULAB is available for a wide range of computers, including UNIX workstations and the Apple Macintosh. For more information on how SIMULAB can address your applica- tions, contact The Math Works today for a free information packet. • - I -- --- - - 0 . " ~ . ... . , (', i· r\ \ " ' ,- ',i '\ . 'I - \'1 " . \.1 Control Panel ..... E .. W..- SWI MT i"""" ....................• Pomnet"'" F-14 model ~~ (Top) Use the Scope block to see the "real·time" response of this F-14 model during the simula- tion; (Center) Specify simulation parameters via dialog boxes or the MA TLAB command line; (Bot/om) SIMULAB takes full advantage of the X/Motif and Macintosh windowing systems. The MATH WOR~ ~ Cochituate Place 24 Prime Park Way, Natick, MA 01760 Tel: (508) 653- 1415 Fax: (508) 653-2997 Telex: 910-240-5521 Email : info@mathworks.com

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