https://ntrs.nasa.gov/search.jsp?R=20110004260 2019-08-30T14:31:18+00:00Z In space: lookitW back to look forward. What can the nature and origin oj the universe tell us about the Juture oj Earth? To help answer that question, we make craft and instruments Jor traveling billions oj miles in space and seeing as Jar as is billion years back in time. Martin Marietta was the integrator and builder of two Viking landers, which sent back remarkable photos of the surface of Mars, examined soil samples, and studied Martian weather and seismic activity For the Voyagers we provided instrumentation that Altimeter anlet1l1a reported on electromagnetic activity near jupiter and Saturn-Voyager 2 went on to Uranus, some 2 billion miles Jrom Earth. That was nine years after launch; next destination, Neptutte, in 1989. These are but a few results oj Martin Mariettas ability to create survivable, mystery- solVing craft and their in strum en ts-Jrom concept through mission completion. ~MaPPing Tr •• smit to Earlb) ~~ Orbit aniorientation Solar panel Mission: map Venus. From orbit, Magellans radar will penetrate the planets thick, gaseous cloud cover and send back photo-like images oj nearly 90% of its surface. Our role: design, integrate, build and test the craft. Hubble Skace Telesco~ Viewing the infant universe. For the Hubble Space Telescope we are providing the Faint Object Spectro- graph (Fa S), which will see objects up to 15 billion light-years away Since the universe is estimated to be 18-20 billion years old, astrotlomers will witness events close to its birth. Satellite The fine points of fine pointing. Beam expander '- _____ Fine Pointing Simulator Mastenninding tomorrows technologies Precisely controlled, space- spanning energy delivery and collection systems create difficult pointing and retargeting challenges, which we can now simulate, This new lab is working toward the precision to zero in on a football-size object 3,000 miles away. in support of the Strategic Defense Initiative research program, WlARTIN WlARIETTA 6801 Rockledge Drive, Bethesda, Maryland 20817, USA INVESTING IN THE GENIUS OF THE MIND A simple discovery can unlock a secret that leaps millennia, to open riches of information that amaze the world . . .. . The Rosetta StOne, found in the Nile Delta by one of Napoleon's Engineer Officers, held the key to the ancient Egyptian hieroglyphics: fragments of three identical texts, one in a known language. The lost knowledge of the pharaohs sprang to life. . . . . Most discovery needs more than luck. An orderly process of observation and analysis-plus the genius of the mind to reach conclusion .. . .. At the David Sarnoff Research Center, the genius of the mind has been at work for nearly half a century, making discoveries for corporate and government clients around the world ..... This reservoir of accumulated experience and knowledge of superconductivity, surface emitting diode lasers, high-definition TV systems and allied disciplines, continues to make significant advances for our clients .... . General David Sarnoff saw us as a force to "Amaze the world!" using the powers of the mind to bring the best of technology to the service of industry and government. As a result, we often find our heads in the clouds, our feet on the ground -and some amazing solutions for the problems of our clients ..... For information call: Market Develop- ment, David Sarnoff Research Center, CN 5300, Princeton, NJ 08543-5300 (609) 734-2553. When you want to discover something amazing .... . DAVID SARNOFF RESEARCH CENTER Subsidiary of S RI J nternational Circle Reader Action No. 604 A Tool For The Left Brain For every concept that works, many others fail. That's creative concept development. Until now, the only way you isolated the best concept, was to develop, model or prototype all of them. That cost can cripple your concept's success and restrict your company's performance. IGRIP'" CAD/Simulation Software is a better idea for idea development ... A tool that simulates your concepts on a graphics screen in full 3·0 smooth shaded animation. The act of creation is fast, allowing you the leisure to develop multitudes of graphically animated pro- totypes for evaluation. If you can imag- ine it, IGRIP can simulate it. IGRIP can design and simulate any device, even complex anthropomorphic models. It can assemble and verify static and dynamic forms and functions, and even detect collisions in real time. Part changes, modifications and updates can also be quickly redesigned and immediately proved-out. In fact, the same software can be used for off-line system programming in manufacturing environments. IGRIP is a versatile, creative tool for the left brain, but programmed for the real world. The software is simple to use and logical. It can communicate with other data bases, and is user configurable. Your engineers need IGRIP, so does your budget. New concepts start somewhere_ Some- times, even with a phone call: (313) 689-7763 IGRIP Simulation/Animation Software Lets Your Concepts Take Off • Most user friendly and interactive software on the market. You can con- figure it to your needs, goals and un- derstand i ng. • 3-D smooth shaded animation of mul- tiple, concurrently operated devices. • It allows you to create articulated devices with unlimited degrees of freedom that you can jog by links or move with specific, generic or user developed kinematics. • High level IGRIP/GSL'" language features: Device choreography, dis· play mode and view pOint control , bi · directional external process .commu· nication, and inter-device I/O com· munication. (Perfect for Telero- botics) • Automatic and exact collision and near miss detection doesn't take minutes. Simulation on screen in real time. • Complete Dynamic Viewing: User de· finable viewpoint selection including our unique viewpoint attachment to moving objects. • Elegant CAD package completely in- tegrated with the simulation system. Allows automatic updating of part and multiple part revisions, bundled with other smart CAD operators. • Allows data conversions with other CAD formats, ie., IGES, MOVIE.BYU, CATIA, Wavefront Technologies or custom translators. • Produces Key Frame files for anima- tion renderers. (Mot ion scripting) • Video synchronization utility for final production. Deneb Robotics, Inc. LEADING THE EDGE 1120 E. Long Lake Rd. Ste. 200 Troy, MI 48098-4960 (313) 689-7763 Circle Reader Action No. 446 \ \ - -- \ - ., NJ\SI\ Tech Briefs Transferring Technology to American Industry and Government JANUARY 1990 Volume 14 Number 1 SPECIAL FEATURES NASA's Mission To Planet Earth .12 Mission Accomplished ......... 86 TECHNICAL SECTION ~~ New Product Ideas ......... 10 NASA TU Services . 16 ~ Electronic Components and Circuits ......... .18 • ,., Electronic Systems ........ 26 Physical Sciences Materials ....... . Computer Programs Mechanics Machinery .......... . I I Fabrication Technology G Mathematics and .34 .42 .45 .48 .60 .62 ~ Information Sciences ....... 67 ~ ~ Life Sciences ............. 74 o Subject Index ............. 80 Researchers at NASA's Jet PropulsIon Laboratory are usIng the Mark 11/ Hyp.rcube computer to analyze the scatt.rlng of e/ectromagn.tlc waves. Th. above Imag. shows the magnltud.s of the total current. Induced on the surfece of a perfectly conductIng 1.0 x 1.0 x 1.0 m.ter cub. scatt.rer. See page 33. DEPARTMENTS On The Cover: A satelllt. Image of .ea .urface temperature In the w •• t.rn North AtlantIc during Jun. 1984. Warmer hu.s denote warmer t.mp.ratur ••• NASA I. now plannIng a long·t.rm r.mot ••• n.'ng mIssIon call.d EOS (page 12) to .tudy the oc.ans, land ma .... and atmo.ph.re, theIr Interectlons, and how the Earth'. syst.m I. changIng. Thl. res.arch holds the k.y to under.tandlng global warmIng and other envIronmental problem •• (Photo courtesy Brown, Evans and Carle, University of Miami Rosenstiel School of Marine and Atmospheric Science) A n.w machIne vIsIon technIque called D SIght'"" ,; detect. and magnm.s ~ mInute .urface flaws. lil Th ... photo. show a car 8 door vIewed under normal ~ light (top) and with the t: D Sight system. Turn to 8 page 86. ~ Q. New on the Market .. 77 New Literature .. 79 Advertisers Index ....... 84 This document was prepared under the sponsorship of the National Aeronautics and Space Administration. Neither Associated Business Publications Co., Ltd . nor anyone acting on behalf of Associated Business Publications Co. , Ltd. nor the United States Government nor any person acting on behalf of the United States Government assumes any liabi lity resulting from the use of the information contained in this document, or warrants that such use will be free from privately owned rights. The U.S. Government does not endorse any com- mercial product, process, or activity identified in this publication. 6 Permissions: Aulhortzatlon to photocopy lIems for (n18m" or peraonal use, or the Internal or persona! use of specific cllents,ls granted by Associated Business Publications, provided that the flat fee of $3.00 per copy Is paid directly to the Copydght Cloarance Center (21 Cong"' .. St., Salem, MA 01970). For those organizations thlt have been gnooted. photocopy license by CCC, a separate system of payment has been annonged. The fee code for u .... of the T","oactionai Reporting Seovlce Is; ISSN 0145-319X19O $3.00 + .00 ~:;~~e;~~1~~~u~~~~1~~i~~~~i ¥:c~ ~~'f~7~'h~g~~r::~~~~,= IbyUN~S,:.p~3N~~~ ~.~~~~~r~~~~I:~':tc?r~~l~~'~SnP::,~,'~;~t~~~ ~'4~~~' ;:r!et2~:!tYONr:~NYYO~~~.Ws~ ~s~:~~~1Ig~~~~~~~~~~~r:r~ ~~~~~~~S'~'~I~:~~m~~c~6~:;:: ;~:C~P~1~:~~~~OUI!~~O~t~O~1~t't~~58~e~~:~i~r:~~/r~~~.Y~~'~~~'~~Of~~ :.~~: ~~I~~~cf~~';;o~~~~·:g:Jt: .~r~=e:~~s~.~~~Z~~~~,~~~rn:11~~ s:n?ce:s~ POSTMASTER: Ill •••••• nd addr ••• ch.ng •• to NASA Tach Brl.f., 41 E. 42nd Str •• t , Suit. 921 , N.w York, NY 10017-5391 , NASA Tech Briefs , January 1990 YOU'RE LOOKING AT SOME OF THE MOSTVAWED REFERENCE BOOKS IN YOUR INDUSTRY. When it comes to the best-known, high-performance, heat and corrosion resisting high-nickel alloys, we wrote the books. If you want more information on MONEL, INCONEL, !NCOLOY, INCa , NILO, BRIGHTRAY, or NIMONIC alloys, let us know. We're the only source for these products. And we have them available in the widest range of forms and sizes in the industry. All with the proven ability to save you money in repair, replace- ment and downtime. Others may imitate our products, use our books for reference and guidance, and even use our numbering system; but they cannot use our trademarks. And they can't match the range of alloys and forms Inco Alloys International offers . Start your own reference library. Get our "Quick Reference Guide" free just by writing us. Inco Alloys International, Inc ., Huntington, West Virginia 25720. Or, for a quicker reply, FAX us at (304) 526-5441. MONEL, INCO EL, INCOLOY. INCO, NILO, BRIGHTRAY and NIMONIC are trade- marks of the lnco family of • INCO ALLOYS .. INTERNATIONAL Circle Reader Action No. 569 Inco Alloys International distributors in the USA: Castle Metals, Metal Goods, Tubesales, and Williams & Co. In Canada: Atlas AlIvys and Dnmlmond McCall Inc. 8 RealTime Video On Workstation Displays i ii. .-• • • • • • . 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CA 94710 TEL: (415) 848-0180 FAX: (415) 848-0971 Circle Reader Action No. 467 NI\S/\ Tech Briefs NatIOnal AeronautICS and Space Administration NASA Tech Briefs: Published by ................... AssociMed Bu.ln.n PubllcMlon. Edltor·ln-ChleIlPublisher ........ . ................. Bill Schnlrrtng Associate Publisher .............................. Frank Noth.tt Editor ................................... Joseph T. Pr.mberg.r Managing Editor ...................................... R. J.LHr Assistant Editor ............................... Th.r ... M. Detko Technical Advisor ................... ..... Dr. Robert E. WMtrm.n Production Manager ................................ RIt. Nothatt Traffic Manager ................................. J.m .. E. Cobb Circulation Director ............................. Anlt. W.lnm.n Advertising Coordination Manager .......•............. M.y. F.ltk Telecommunications Specialist ... .. ........•........ Evelyn M.r. Reader Service Manager ..... . .................... Sylvl. V.I.ntln Brl.,. , Supporting Ut.rMur.: Provided to National Aeronautics and Space Administration by Internatlonal Computers' T.ltcOmmunlcMlon., Inc., NY, NY with assistance from Loglcll TechnlCiI StrvIc.., NY, NY Technical/Managing Editor ...................... . .... Ted Stllnlky Art Director .................................... Emest Glllttple Administrator ........................... . ... . .. Elizabeth Texel,. Chief Copy Editor ............. . ......... . .......... Lorn. Bullen Staff Writers/Editors . . ...•.... Dr. J.m .. Boyd, Dr. Ltrry Grunberg", Dr. Theron Cole, Jorcltn Rend)elovlch, Georg. WMson, Oden Brownl Graphics .............. . •......... Lui. Mlrtln.z, Vem.ld GlUmln, Chlries Stmmlrteno Editorial & Production .. . ..........•. ... .. Bill Uttll, Ivonnl Vlldts, frink Ponce, Su .. n Rnelll NASA: NASA Tech Briefs are provided by the National Aeronautics and Space Administration, Technology Utilization DiviSion, Washington, DC: Administrator ........ . .... . .......... . ... . ...... Richerd H. Truly Assistant Administrator for Commercial Programs ..... J.m .. T. Rose Deputy Assistant Administrator (Programs) ...... . .... Henry J. Clerks Deputy Director TU Division (Publications Manager) ... Leonerd A. Ault Manager, Technology Utilization Office, NASA Scientific and Technology Information Facility .. .. .. ........ W.lt" M. Helland Associated Bus/ntIS Publication. 41 Etat 42nd Street, Suit. 921, New York, NY 10017·5391 (212) 4110·3999 FAX (212) 986·7864 President ..... . ...... .. ............ . ... .. ..... ... Bill Schnlrr1ng Executive Vice President .. . . ....................... Frank Nothatt Vice President .. . .... . ................. . ... Dom.nlc A. Mucchll1l Operations Manager . . ......... . ... . ................. Rltl Nothatt Controller ........................................ Felecll Lah.y Adv.rtlslng: New York OffICI: (212) 490·3999 FAX (212) 988·7864 National Sales Manager ....................... Jam .. G. McGarry Regional Sales Manager (Mld·Atlantlc) ............. Michelle Lar .. n Account Executive .... .... .. . ... . ... Debby Cr.n. at (201) 967-9838 Account Executive (Midwest, Northwest) ........ P.ul Lasher, C.B.C. at (708) 501-4140 Account Executive (South-Central) ... . ...... . ..... Dougl •• Sh.ller at (212) 490-3999 Account Executives (Eastern MA, NH, ME, RI) ........ P.ul GIII.spl. at (508) 429-8907; Bill Doucll1e at (508) 429-9861 Account Executives (Western MA, CT, VT) .. . ... . ..•.. Georg. WII1. or D.vld HIIIgll1 at (413) 253-9881 Account Executives (Southeast) ................ . Nlwton Collinson or Jonath.n KIg.r or Lawr.nc. MllChlk at (404) 939·8391 Account Executives (Calif., AZ, NV, NM) ......................... . for Area Codes 81812131805 - Thom •• Stlllm.n and for Area Codes 6191714 -Klr.n Mock at (213) 372-2744 NTBM-R .... rch Cent.r Account Supervisor ........... . ..... . ......... Lourdes Del V.II. NASA Tech Briefs, January 1990 Here are a few off-the-wall applications for ,engineering film. A 3-mllIyIr of PVF 11m replaces cos1Iy, heavy glass previously used tar the top an this solar coIector. Mobay In-lne laminates the top and bottom PVF layers to EVA during the extrusion process, further reducing cost by elmlnlllng twa hand lay-up steps. /3 mil PVF The laser-engraved media inside this optical memory card can store up to 800 pages of type-written data. Mobay supplies the 10 -mil while substrate, a 2-mH clear carrier and a 15-mil clear hard-coated surface - aH of Makrofol polycarbonate film. This disposable thermoformed tray of FDA-grade Makrofol resists loss of clarity and structural integrity from autoclave, gamma radiation and high heat sterifization. Now, let's hear one of yours. Mobay f ilm technology is advancing to meet a universe of new applications. At production facilities on two continents, our on-going and vigorous R&D efforts focus the talents of resin chemists and extrusion engineers on tomorrow's products. For existing applications, we're a reliable source of consistently high quality engineering film. For emerging applications, were anxious to provide powerful technical assistance. Call us! Plastics and Rubber Division Mobay Corporation Moba\/ e 245 New Park Drive -7 I : , Berlin, CT 06037 Telephone: (203) 828-4100 TOLL FREE 1-800-423-6471 Telex: 643514. Fax: (203) 828-7819 A Bayer USA INC. COMPANY lew ProduCllde8S New Product Ide .. are Just a few of the meny Innovlltlons dnCribeclln this laue of NASA T.ch 8"m and h."lng promising commerclel eppllcatlons. bc:h Is discussed furth ... on the ref ... enced page In the appro- prillte HCtlon In this laue. If you are Int ... med In d."eloplng a product from th ... or other NASA Innovlltlon .. you can raeelve fur· ther tschnlcallnformlltlon by r. qumlng the TSP r ..... enced lit the end of the full· length article or by writing the Tschnology Utilization OftIce of the sponsoring NASA cent ... ,aM page 11). NAlA's plltent-llcenalng program to encourage comm ... • clal d."elopment Is deacrlbecl on page 11. Generating Weighted Test Patterns for VLSI Chips An Improved built-in self-testing circuit for very-large-scale integrated dig~al clrcu~s is based on a version of the weighted-test- pattern"generation concept. The approach applied to a commercially-available com- binational circu~ resutted in 12 weighted test patterns that detected all of the stuck-at- one and stuck-at-zero faults. Ballistic-Electron- Emission Microscope Buried interfaces such as between semi- conductor and a thin metal film can be in- vestigated with high spatial resolution by a ballistic-€Iectron-€mission microscope that employs scanning tunneling-microscopy methods. 10 Need prototype rubber parts in ajiffy? Call your fast friends at Syntex. We design and manufacture stamped and molded rubber parts in any material. We'll work from a blueprint or sketch to provide prototype samples. Our personal attention and design review capability assure highest quality. With one day cost estimates! For proto- type parts or for orders of any size at ~I""':"'::"!!r'll f',(,llmpetitive prices, call now (See page 30) assistance. Or send for. catalog. • Circle Reader Action No. 515 (See page 34) Isomeric Trisaryloxycyclo- triphosphazene Polymer Precursors The presence of the phosphazene moi- ety in cyclotriphosphazene-based mono- mers and polymer precursors is expected to impart special properties in high-perform- ance materials containing inorganic back- bones. The substances produced are useful for obtaining heat- and fire-resistant poly- mers for composites, adhesives, molding powders, and coating laminates. (See page 42) Tester Detects Steady- Short or Intermittent- Open Circuits A simple, portable, lightweight testing cir- cuit sounds a long-duration alarm when it detects a steady short circuit or a momen- tary open circuit in a coaxial cable or other twcrconductor transmission line. The tester is sensitive to discontinuities that last 10 IJS or longer. (See page 18) Welding-Current Indicator A simple, inexpensive display circuit in- dicates when the 3,OOD-A welding current flows in a welding gun. A light flashes on to indicate high current. (See page 24) Articulated Suspension Without Springs Wheels negotiate bumps and holes with minimal tilting of the vehicle body thanks to a spring less suspension. In the new sus- pension, a wheel can climb an obstacle as high as 1 Y2 times its diameter without ex- cessive tilting of the chassis. (See page 60) NASA Tech Briefs, January 1990 Introducing DADiSP 2.0 I DADiSP. The Big Picture in Signal Processing DADiSP - interactive graphics and data analysis soft- ware for scientists and engineers. DADiSP 2.0 delivers unprecedented power, through easy-to-use menus. Choose from hundreds of analysis functions and graphic views - from tables to 3-D. Simultaneously display multiple windows, each with different data or analyses, for unlimited perspective on your toughest data analysis problems. Build your own analysis worksheets - build and display an entire signal processing chain, without programming. And DADiSP's powerful graphic spreadsheet automati- cally recalculates and updates the entire chain if you change your data or a processing step. Do serious signal processing ..• the way you always pictur.ed it! FITs, digital filter design, convolutions, waterfall plots, and more - all at the press of a key. Let your instruments do the talking - use DADiSP- 488 to bring data from your instruments directly into a DADiSP window for immediate viewing and analysis. Flexible, expandable, customizable - annotate your graphs and send them to printers, plotters, or publishing packages. Create your own macros, automate routine tasks, and run any program written in any language from within DADiSP. DADiSP even lets you build your own menus. A proven standard - already used by thousands of engineers and scientists world- wide, in a whole range of applications like medical research, chemistry, vibration analysis, communications, manufacturing quality control, test & measurement, and more. DADiSP supports the mM PC and PS/2, SUN, DEC VAX, HP 9000 and Concurrent families of personal computers and workstations. GET THE PICTURE! CALL TODAY 617·577·1133 Ask for our Evaluation Disk. For more information, write to DSP Development Corporation, One Kendall Square, Cambridge, MA 02139, or FAX: 617-577-8211. DSP Development Corporation Australia-Interworld Electronics, 03 521-2952; England-Adept Scientific, (0462) 683355; Biosoft, (0223) 68622; Finland-Turion, 0-372-144; France-SM2I, (1) 34810178; Sacasa, 69077802; West Germany-Datalog, (02166) 46082; Stemmer Electronik, 089-809 02-0; Israel-Racom Electronics, 03-491-922; Italy-BPS Computers, (02) 61290221; Japan-Astrodesign, 044-751-1011; Netherlands-Computer Engineering Roosendaal, 01650-57417; New Zealand-GTS Engineering, (09) 392 464; Sweden-Systek, 013 110140; Switzerland-Urech & Harr AG, 61 611325; Taiwan-Advantech, 2-351-2117 Circle Re.der Action No. 852 NASA's ission To Planet Earth A new urgency is driving our need for understanding the Earth and how it works. Humans are no longer mere observers in the events of global change; our industrial and agri- cultural activities contribute significantly to the Earth's physical condition. During the next century, the current worldwide population of 5.3 billion is expected to grow to 14 billion. Our successful tech- nology will spread across every conti- nent, with vast engineering projects in building roads, clearing forests, and changing waterways. We are no longer surviving in habitable places, we are engineering our planet. How delicate is our biosphere? Our life support system? We simply do not know. For years we have been a.....,are of our ability to pollute the atmosphere, dump toxic wastes into the water sup- ply, and drive wildlife to extinction . Recently, we have realized that the changes brought on by these activities may be irreversible and may seriously affect our own survival. Scientific con- ferences have been held to assess the changing Earth and numerous research- ers have made predictions about the coming changes. While there is some agreement about the qualitative nature of these changes, there is little agree- ment about their degree. The difficulty lies in sorting the natural changes from those caused by mankind. We lack a sufficient database to understand the climatic changes on a decade to century scale that are due to forces of nature such as variances in the sun's output, the wobble of the Earth, volcanism, or ocean circulation. Records revealing the ice ages, crustal plate movements, and past concentrations of trace gases in the atmosphere help put into context the changes we are considering today, but the more subtle changes - a 2° to SoC rise in 'global temperature, 50 percent depletion of ozone over Antarctica, or loss of large wooded regions due to acid rain - require more refined measure- ments over a long, continuous period in order to determine the predictive conse- quen~es . These grave global phenomena have attracted worldwide attention, not only by climatologists but also by social sci- entists, politicians, and economists. A global warming of 4° C would alter the lives of most of the Earth's inhabitants. Due to the secondary effects of evapo- ration over the land and oceans and evapotranspiration above the rain for- ests, the cloud patterns, rain, and snow in the hydrological cycle would be af- fected. Some areas would be hotter and possibly drier, others wetter or colder. The annual depletion of ozone over the poles has alarmed world health organizations. Ozone in the stratosphere is a shield against the sun's harmful ultraviolet rays. The penetration of this radiation is likely to have a dire effect on both the humans who are exposed and by Dr. Gerald A. S~ffen the flora and fauna who cannot take steps to cope with the new environment. Many scientists believe the ozone de- pletion is caused by traces of chlo- rofluorocarbon gas released into the atmosphere, and their concomitant chemical interaction. Acid rain is another result of atmos- pheric contamination. In this case the air is cleansed by rain, but the resulting acidified sulfur and nitrogen compounds damage the soil and trees. Vast wooded areas have disappeared in recent years and much larger regions of the Earth are believed to be vulnerable. Perhaps the most serious irrevers- ible change caused by humans is in the Earth's biodiversity. The genetic pool is the result of four-and-a-half billion years of natural selection and evolution . The world's biological state is the net result of changes of nature prescribed by both chance and biological order. Now hu- mans are removing large tracts of for- ests for industry, and hunting and fish- The first truly global view of the Earth 's biosphere, combining years of data from the Nimbus 7 and NOAA 7 spacecraft, shows Earth teeming with life on both land and sea. Rain forests and other highly productive biological areas appear as dark green, deserts yellow. The concentration of photoplankton, a primary Indicator of ocean productivity, is represented by a scale that runs from red (highest) to orange, yellow, green, blue, and purple (lowest). Photo courtesy NASA ing with technological efficiency that can destroy a species without intent. One problematic aspect of this is that we have no way of assessing the degree of biological damage. We do not know how many species of life exist on the planet. Some biologists believe there are ten million, others say there are 50 million. We do not understand if we are destroy- ing important species or just perturbing nature slightly. These and other global problems have forced world leaders to organize international studies. The Earth is now viewed as a system composed of vari- ous elements. Scientists who previously specialized in a single field such as oceanography or atmospheric dynam- ics now realize the importance of inter- disciplinary studies. Understanding global warming and other environmental prob- lems will require new interactions among scientists, as well as more data, long- term observations, and advances in sensor and computation technologies. NASA's Role NASA has an important role to play and several things to offer. The agency has a powerful research effort in the Earth Sciences and has flown many scientific observatories. It has the world's most advanced civilian program in in- strument development and the compu- tational power to support today's best models. NASA's Earth Sciences program is called Mission To Planet Earth. It has several components: a ground segment using laboratories, balloons, aircraft, field operations , and theoretical studies ; spacecraft such as payloads attached to the shuttle or space station Freedom; geostationary platforms; and large po- lar platforms. The Earth Observing System (EOS) is a scientific mission using polar-orbit- ing platforms slated for operation in the late 1990s and into the early part of the next century. The goal is to advance knowledge of the Earth system on a global scale by developing a deeper understanding of the parts of the sys- tem, the interaction among them, and how the system is changing. The EOS mission will create an integrated ob- serving system which will enable mul- tidisciplinary study of the Earth's atmos- phere, oceans, land surface, polar re- gions, and biosphere. The key science areas are the hy- drological cycle, the biogeochemical cycles, and the climatological and geo- physical processes. Scientists hope to quantify the processes of precipitation , evaporation , evapotranspiration , and runoff on a global basis, and to under- stand the biogeochemical cycling of carbon, nitrogen, phosphorus, sulphur, and trace metals. Further, they want to assess the influence of sea and land ice cover on global climate and determine the coupling between the lower and upper atmosphere. These are but a few of the many scientific questions now being formulated. The measurements needed to answer them will be made by NASA Tech Briefs, January 1990 a variety of instruments, many of which are now under development. Current plans call forfive EOS space- craft: two from the United States, two from the European Space Agency (ESA), and one from Japan. Other partners include the National Oceanic and At- mospheric Administration (NOAA) and Canada. The NASA spacecraft will be carried into orbit by a. Titan IV launch vehicle in late 1997. They will be in sun- synchronous orbits at 705 km altitude with a 1 :30 p.m. equator crossing time in the ascending node. The ESA's Colum- 1l bus spacecraft will be launched on the 5 o Ariane and will be sun-synchronous at 8 an altitude of 700 to 850 km with equa- ~ torial crossing times of 0930-1 030 ~ (descending) and 1330-1430 (ascend- ~ ing) . ~ Instruments will be shared among the partners, and in some cases one agency's instrument may be launched on another's spacecraft. The agreement calls for all of the data to be available to any qualified research scientist. This "open data" policy is vital to the success of EOS. The strategy of combining measure- ments and observations from the vari- ous platforms requires an elaborate plan for covering the Earth . For certain measurements the direction of pointing or field of view is critical. In some cases observations of the same region must be made by several spacecraft simulta- neously, while in other cases the time of day or changing season is important. Each class of instrument has a particu- lar set of requirements and this has to be worked into a pattern that will opti- mize the combined results of all the missions. From the position of a satellite look- ing down on the Earth, a main consid- eration of what can be measured is the transmission of the various wavelengths of the electromagnetic spectrum through the Earth's atmosphere, which is opaque to most of the spectrum. This opacity is due mainly to molecular, aerosol, or water absorption . Radiation bfeaks through in the optical region, certain bands in the infrared (IR), and in the microwave region beyond 0.1 cm wave- length. Hence, EOS instruments will operate selectively in two bands : the optical-IR and the microwave. Instruments NASA is considering for its polar-orbiting platforms include: MODIS - moderate-resolution imag- ing spectrometer for surface and cloud imaging in the visible and infrared 0.4- 2.2 nm, 3-5 /-Lm , 6-14 /-Lm resolution vary- This artist's concept highlights the sci- ence instruments of an EOS polar-orbit- These Southern Hemisphere plots illus- trate the total ozone distribution for Sep- tember 22 over the last four years. They show that the areas of lowest ozone (purple shades) In 1986 and 1988 covered significantly less area than the ozone holes observed In 1987 and 1989, which covered nearly the entire Antarctic continent. The Total Ozone Mapping Spectrometer (TOMS) instrument on NASA 's Nimbus 7 satellite captured this data. ing from 10 nm to 0.5 /-Lm . Two of these are planned, one pointed in the nadir to look at the land surface, and the other in a tilt mode to observe the ocean at differ- ent sun glint angles. HIRIS - high-resolution imaging spectrometer for surface imaging 0.4- 2.2 nm, 10-20 nm spectral resolution . This instrument will use 192 channels to obtain detailed 30m resolution maps of selected areas of the Earth. Volcanolo- gists, geochemists, and biologists are particularly interested. AIRS-AMSU - atmospheric infrared sounder will observe atmospheric tem- perature profiles and other properties. Its field of view is 15-50 km. CERES (clouds and the Earth's radi- ant energy) - Based on the ERBE scanners, CERES will measure radia- tion at the top of the atmosphere and at the Earth's surface. It will provide data on cloud coverage, altitude, condensed water density, and optical depth. HIMSS - high-resolution microwave spectrometer sounder will feature a rotating 2m parabolic antenna operat- ing at 90-6.6 GHz which will measure precipitation, sea surface temperature, and snow cover depth . TES - tropospheric emission spec- trometer is a high-spectral-resolution infrared Fourier transform spectrome- ter that will enable researchers to moni- tor many of the minor constituents of the lower atmosphere. The nucleus of EOS is the Data and Information System and the scientists who will handle the data. EOS data will be transmitted by the Tracking and Data Relay Satellite System and distributed around the world to thousands of scien- (continued on page 81) 13 "When Interleaf's software runs on D!gital's powerful worKstations, you see the full potential of electronic publishing:' "Interleaf's leadership position in electronic publishing is based on the view that information is most useful when it can be shared by the whole organization. Digital gives us what we need to make that a reality. "In Digital's DEC station;" UNIX®-based RISC workstations and VAXstation'" workstations, we have excellent vehicles for our software. They offer high performance and a choice of robust operating systems- ULTRlX'" and VMS:" And they bring Digital's well-known networking and multi-vendor integration into play. For example, Digital's CDA'" (Com- pound Document Architecture) can provide users with the means to share all types of data-text, charts and graphics - between applications and across operating systems. "With the speed, flexibility and comprehensiveness of what we offer together, customers are beginning to see how all-encompassing electronic publishing can be." The rewards of working together. Digital's high-performance work- stations offer a unique combination of power and networking capability for turning information into a shared resource. And, we back them with worldwide service and support. Today, with a full line of worksta- tions, Digital gives you an elegantly simple way for your people to work together more productively, more creatively, more efficiently, more competitively. To learn more, call 1-800-842-5273 ext. 625. Or call your local Digital sales office. A way to work together like never before. Digital has . It now. HOW YOU CAli BEIIEFIT I f you 're a regular reader of TECH BRIEFS, thEn you 're already making use of one of the low· and nOoCost services provided by NASA's Technology Utilization (TU) Network. But a TECH BRIEFS subscription represents only a fraction of the technical information and applicationslengineering services offered by the TU Network as a whole. In fact, when all of the components of NASA's Technology Utilization Network are considered, TECH BRIEFS represents the proverbial tip of the iceberg. FROM IIASA's TECHIIOLOGY UTlUZAnOIL SERVICES We've outlined below NASA's TU Network-named the part icipants, described their services, and listed the individuals you can contact for more information relating to your specific needs. We encourage you to make use of the information, access, and applications services offered by NASA's Technology Utilization Network. How You Can Utilize NASA's Industrial Applications Centers-A nationwide network offering a broad range of technical services, including computerized access to over 100 million documents worldwide. YOU can contact NASA's network of Industrial Applications Centers (lACs) for assistance In solving a specif ic technical problem or meeting your Information needs. The " user friendly" lACs are staffed by technology transfer experts who provide computerized Information retrieval from one of the world 's largest banks of technical data. Nearly 500 computerized data bases, ranging from NASA's own data base to Chemical Abstracts and INSPEC, are accessible through the ten lACs located throughout the nation. The lACs also offer technical consultation services andlor linkage with other experts in the field . You can obtain more Information about these services by calling or writing the nearest lAC. Useffees are charged for lAC information services. Aerospace Research Research Triangle Park, NC 27709 NASA/UK Technology NASA Industrial Applications Applications H. Lynn Reese, Director Applications Program Center Center (ARAC) (919) 549·0671 University of Kentucky University of Southern California Indianapolis Center for Advanced NASA Industrial Applications 109 Kinkead Hall Research Annex Research Ctr. 823 William Pitt Union Lexington, KY 40506·0057 3716 South Hope Street 611 N. Capitol Avenue University of Pittsburgh William R. Strong, Director Los Angeles, CA 90007·4344 Indianapolis, IN 46204 Pittsburgh, PA 15260 (606) 257·6322 Robert Stark, Director Dr. F. Timothy Janis, Director Dr. Paul A. McWilliams, NERAC, Inc. (213) 743-6132 (317) 262·5036 Exec. Director One Technology Drive (800) 642·2872 (CA only) Central IndustrIal Applications (412) 648·7000 Tolland, CT 06084 (800) 872·7477 (toll·free US) CenterlNASA (CIAC) NASA/Southern Technology Dr. Daniel U. Wilde, President NASA/SU Industrial Applications Rural Enterprises, Inc. ApplicatIons Center (203) 872·7000 Center p. O. Bo:'! 1335 Box 24 Technology Application Center Southern University Department Durant, OK 74702 Progress Ctr., One Progress Blvd. (TAC) of Computer Science Dickie Deel, Director Alachua, FL 32615 University of New Mexico P. O. Box 9737 (405) 924·5094 J. Ronald Thornton, Director Albuquerque, NM 87131 Baton Rouge, LA 70813·9737 North Carolina Science and (904) 462·3913 Dr. Stanley A. Morain, Director Dr. John Hubbell, Director Technology Research Center (800) 354·4832 (FL only) (505) 277·3622 (504) 771·6272 (NC/STRC) (800) 225·0308 (toll·free US) Post Office Box 12235 If you represent a public sector organization with a particular need, you can contact NASA's Application Team for technology matching and problem solving assistance. Staffed by profeSSional engineers from a variety of disciplines, the Application Team works with public sector organizations to identify and solve critical problems with existing NASA technology. Technology Application Team, Research Triangle Institute, P. O. Box 12194, Research Triangle Park, NC 27709. Oorls Rouse, Director, (919) 541·6980 How You Can Access Technology Transfer Services At NASA Field Centers: Technology Utilization Officers & Patent Counsels-Each NASA Field Center has a Technology Utilization Officer (TUO) and a Patent Counsel to facilitate technology transfer between NASA and the private sector. If you need further information about new technologies presented in NASA Tech Briefs, request the Technical Support Package (TSP). lf a TSP is not available, you can contact the Technology Utilization Officer at the NASA Field Center that sponsored the research . He can arrange for assistance in applying the technology by putting you in touch with the people who developed it. If you want Information about the patent status of a technology or are interested in licensing a NASA invention, contact the Patent Counsel at the NASA Field Center that sponsored the research . Refer to the NASA reference number at the end of the Tech Brief. Ames Research Ctr. Technology Utilization Officer: Laurance Milov Mail Code 223·3 Moffett Field, CA 94035 (415) 694·4044 Patent Counsel: Darrell G. Brekke Mail Code 200·11 Moffett Field, CA 94035 (415) 694·5104 Lewis Research Center Technology Utilization Officer: Anthony F. Ratajczak Mail Stop 7·3 21000 Brookpark Road Cleveland,OH 44135 (216) 433·5568 Patent Counsel: Gene E. Shook Mail Code 301·6 21000 Brookpark Road Cleveland,OH 44135 (216) 433·5753 John C. Stennis Space Center Technology Utilization Officer: Robert M. Barlow CodeGA·OO Stennis Space Center, MS 39529 (601) 688·1929 John F. Kennedy Space Center Technology Utilization Officer: Thomas M. Hammond Mail Stop PT·PMO·A Kennedy Space Center, FL 32899 (407) 867·3017 Patent Counsel: James O. Harrell Mail Code PT· PAT Kennedy Space Center, FL 32899 (407) 867·2544 Langley Research Ctr. Technology Utilization Officer: John Samos Mall Stop 139A Hampton, VA 23665 (804) 864·2484 Patent Counsel: George F. Helfrich Mail Code 279 Hampton, VA 23665 (804) 864·3523 Goddard Space Flight Center Technology Utilization Officer: Donald S. Friedman Mall Code 702.1 Greenbelt, MD 20771 (301) 286·6242 Patent Counsel: R. Dennis Marchant Mail Code 204 Greenbelt, MD 20771 (301) 286·7351 A Shortcut To Software: COSMIC<&"'- For software developed with NASA funding, contact COSMIC, NASA's Computer Software Manage· ment and Information Center. New and updated programs are announc· ed in the Computer Programs section . COSMIC publishes an annual software catalog. For more information call or write: COSMIC~ 382 East Broad Street, Athens, GA 30602 John A. Gibson, Dir., (404) 542·3265 16 Jet Propulsion Lab. NASA Resident Office Technology Utilization Officer: Gordon S. Chapman Mail Stop 180·801 4800 Oak Grove Drive Pasadena, CA 91109 (818) 354·4849 Patent Counsel: Paul F. McCaul Maii Code 180·801 4800 Oak Grove Drive Pasadena, CA 91109 (818) 354·2734 Technology Utilization Mgr. for JPL: Dr. Nor· man L. Chalfin Mail Stop 156·211 4800 Oak Grove Drive Pasadena, CA 91109 (818) 354·2240 George C. Marshall Space Flight Center Technology Utilization Officer: Ismail Akbay CodeAT01 Marshali Space Flight Center, AL 35812 (205) 544·2223 Fax (205) 544·3151 Patent Counsel: Bill Sheehan Mail Code CC01 Marshall Space Flight Center, AL 35812 (205) 544·0021 Lyndon B. Johnson Space Center Technology Utilization Officer: Dean C. Glenn Mail Code IC-4 Houston, TX 77058 (713) 483·3809 Patent Counsel: Edward K. Fein Mail Code AL3 Houston, TX 77058 (713) 483·4871 NASA Headquarters Technology Utilization Officer: Leonard A. Ault Code CU Washington, DC 20546 (202) 453·8377 Assistant General Counsel for Patent Matters: Robert F. Kempf, Code GP Washington, DC 20546 (20<:) 453·2424 If You Have a Question .. . NASA ScIentific & Technlcallnfor- matlon Facility can answer questions about NASA's Technology Utilization Network and its services and documents. The STI staff sup· plies documents and provides referrals. Call , write or use the feedback card in this issue to contact: NASA Scientific andTechnlcallnforma· tlon Facility, Technology Utilization Office, P.O. Box 8757, Baltimore, MD 21240-0757. Walter M. Heiland, Manager, (301) 859·5300, Ext. 242, 243 NASA Tech Briefs, January 1990 LABTEC NOTEBOOK: for DOS, OS/2, and the Macintosh LABTECH NOTEBOOK has been the accepted standard for data acquisition and control software since we introduced NOTEBOOK for MS-DOS. Now, we've taken the next step into the future with NOTEBOOK for OS/2 and the Macintosh. LABTECH NOTEBOOK now gives you a choice of platfonns - The IBM® PCIXT/ AT, PS/2, compatibles, and the Apple® Macintosh. Setups and configurations are compatible - configure your system on one platform and run the same setup on another. LABTECH NOTEBOOK collects data from multiple channels, displays the data graphically and stores it to disk in real-time. It features user defined acquisition, control and display setups; real-time mathe- matical, statistical and signal processing; sophisticated triggering; data replay; and continuous data collection while you work in other programs. Many input types, including analog, digital , thermocouple, RTD, strain and pressure gages, resistance, counters and frequency, are supported by NOTEBOOK. The DOS version supports foregroundlback- ground operation and, as an option, expanded memory. The OS/2 version takes advantage of OS/2's multitasking capability and protected memory support. NOTEBOOK for the Macintosh works under Multifmder and follows the Macintosh menu and icon conventions. LABTECH NOTEBOOK, with an installed base of 10,000 systems, supports hundreds of board-level data acquisition interfaces and distributed 110 systems from more than 30 manufacturers. NOTEBOOK can be found in most Fortune 500 companies, as well as in smaller enterprises. For more information call your local LABTECH dealer, your hardware 110 manufacturer, or call us directly at (508) 657-5400. l(!Ij LABTECH Laboratory Technologies Corporation· 400 Research Drive· Wilmington, MA 01887·508-657-5400· FAX 508-658-9972 IBM is a registered trademark and IBM XT, AT and PS/2 are trademarks of the International Business Machines Corporation. Apple is a registered trademark of Apple Computer, Inc. and Macintosh is a trademark licensed to Apple Computer, Inc. Circle Re.der Action No. 423 Electronic Components and Clrculls ~I Hardwar., Technlqu •• , and 23 Asymmetric Memory Proc..... Circuit Would Reslat Soft 18 Teater Detects Steedy-Short or Intermlttent-Open Circuits 22 Anomelous Polerlzetlon Mey Improve Infrered Detectors 22 Celculetlng s.cond-Order Effects In MOSFET's Errors 24 Weldlng-Current Indlcetor Tester Detects Steady-Short or Intermittent-Open Circuits ~~ Momentary open circuits or steady short circuits trigger a buzzer. Marshall Space Flight Center, Alabama A simple, portable, lightweight testing cir- cuit sounds a long-duration alarm when it detects a steady short circuit or a momen· tary open circuit in a coaxial cable or other twcrconductor transmission line. The test- er is sensitive to t:liscontinuities that last 10 /.IS or longer. Previously, there was no sim- ple, portable instrument to detect momen- tary shorts or discontinuities. Such con- ventional instruments as ohmmeters and lamp- or buzzer-type continuity checkers give visible or audible indications of steady open or closed circuits only. To detect an intermittent open circuit in a coaxial cable, the far end of the cable is shorted by a jumper, and the tester is con- nected as shown in the upper portion of the figure, with the switch in position B. If the cable is in good condition, the high-side terminal remains grounded, the silicon controlled rectifier remains off, and the buzzer does not sound. If an opening oc- curs in the center conductor or shield of the coaxial cable, the current from the high-side terminal to the low·side terminal that would otherwise be shunted by the cable flows into and triggers the silicon controlled rectifier and thereby turns on the buzzer. Even if the coaxial cable starts to conduct again, the buzzer remains on until the silicon controlled rectifier is reset by turning the switch to position A An inter- mittent discontinuity in a single wire (or an internal discontinuity in the tester) can be detected in this manner if no coaxial cable is connected and the wire or jumper is con- nected as shown in dashed lines. To detect a steady short circuit, the jumper is removed. If the buzzer does not sound, there is a steady short circuit be- tween the inner and outer conductors. If the buzzer does sound, then the cable is either good or open. The tester is used extensively for detect- ing intermittent open shorts in accelerome- ter and extensometer cables. The tester can also be used as an ordinary .buzzer- type continuity checker to detect steady short or open circuits. For this purpose, the switch is set at position A and the probe leads are connected as shown by dashed 18 680Q .=-9V 2N1777 270Q Coaxial Cable Under Test Shorting Jumper HlghSlde , O~----o Low Side ~~--------~~-----------4----~ ; A Alternative: Single Wire Under Test or Jumper To Test Internal Continuity of Tester DETECTION OF INTERMITTENT DISCONTINUITIES OR STEADY SHORTS Circuit Under Test ! [P~ ~ -'" : • B A L""i / -::- y / - - 1'\ 1'\ CONTINUITY BUZZER The Tester Detects Intermittent Discontinuities (above) or shorts (below, right connections). It can also be used as an ordinary continuity buzzer (below, left connections). lines in the lower portion of the figure. In this case, the silicon controlled'rectifier is not part of the circuit, and the buzzer re- mains on only so long as the circuit under test provides a conducting path. This 'MJrk was done by Bobby L Mderoon of Rockwell International Corp. for Mar- shall Space Flight Center. No further documentation is available. MFS-29466 NASA Tech Briefs, January 1990 40.08 A basic element in any solution is IBM. It's mM scientific computing for chemistry: unbeatable combinations of products, applications, service and support that can help chemists in virtually any discipline work more productively. IBM' chemistry solutions offer a wide range of system choices with the diverse applications, powerful graphics capabilities and development tools chemists need to improve information quality and reduce job turnaround time. These versatile mM solutions provide powerful support at every step of the process: instrument data acquisition and control, laboratory information systems, access to CIBM 1988 local and remote data bases, mathematical and statistical analysis, highly specialized graphics and technical reporting, and more. Plus, IBM connectivity allows you to put processing power and vital information where you need it today, while providing an unbroken growth path to your future system requirements. From computational chemistry to genetic engineering, technical office automation to imaging, workstations to supercomputer -IBM is your chemical solution. For more information, or to arrange to have an IBM Marketing Representative contact you, simply call1-800-IBM-2468, Ext. 39. ~ =~_~® - - - --- -- - , - Anomalous Polarization May Improve Infrared Detectors New configurations are proposed for quantum-well devices. NASA's Jet Propulsion Laboratory, Pasadena, California AIl anisotropic quantum effect that has been overlooked until OON may simplify the alignment, increase the sensitivity, and open up more possibilities in the design of quantum-well detectors of infrared radia- tion. Heretofore, it has been thought nec- essary to illuminate such a device at Brevvster's angle (see figure) to maximize the absorption of light by channeling, into the waveguide structures defined by the quantum-well planes, as much as possible of the component of incident radiation that is polarized perpendicularly to these planes. However, a device made accord- ing to the newer concept could be illumi- nated directly on its front side; no special waveguide structures would be required. The behavior of a quantum-well device can be analyzed via the effective-mass ap- proximation. Such an analysis shows that if the device material has an isotropic effec- tive mass, then the component of incident radiation polarized in the quantum-well plane (y-z plane) does not induce a transi- tion of an electron between different sub- band energy states; that is, the transition is quantum-mechanically forbidden. Thus, radiation incident along the x axis or other- wise polarized in the y-z plane is not ab- sorbed and no photocurrent is generated. To effect a transition in the isotropic de- vice, the radiation must have a component polarized along the x axis, and this gives rise to the need for the Brewster's-anglel waveguide scheme. The planes of the quantum wells are perpendicular to the direction of growth (x axis). The quantum theory shows that if the material has an anisotropic effective-mass tensor and if the direction of growth is not a principal crystalline axis of the device material, then nonzero off-diagonal (xy and yz) matrix elements arise between sub- band energy states, even when the light is incident along the x axis (polarized in the x-z plane). These matrix elements repre- Proposed Scheme: Front-Surface illumination Front Surface x Conventional Scheme: Angle of Incidence = Brewster's Angle for Maximum Absorption of Component of Light Polarized in Plane of InCidence (x-z Plane) In a Quantum·Well Detector made according to current practice, the edges of the quantum- well layers should be illuminated at Brewster's angle to maximize the absorption of light po- larized in the planeof incidence. In a detector made according to the proposed concept, light Incident broadside on the front surface would be absorbed. sent an anomalous polarization effect that causes the absorption of light incident along the x axis. This effect can be exploited to increase the sensitivity of an infrared detector by il- luminating the front surface broadside (light incident along the x axis) to take ad- vantage of its large surface area, which Gan be of the order of 1 cm2. The sensitivity of a device could be maximized by the choice of suitable material and by orienta- tion of the crystalline axes along directions that maximize the anomalous polarization effect. This work was done by Chan-Lon Yang of Caltech and Dee-Son Pan of UCLA for NASA's Jet Propulsion Laboratory. For further information, Orele 113 on the TSP Request Card. NPO-17450 Calculating Second·Order Effects in MOSFET's These effects become important as dimensions shrink to a micron. NASA's Jet Propulsion Laboratory, Pasadena, California A collection of mathematical models in- cludes second-order effects in n-channel, enhancement-mode, metal-oxide-semi- conductor field-effect transistors (MOS- FET's). When dimensions of circuit ele- ments were relatively large, these effects could be neglected safely. However, as the 22 very-large-scale integration of microelec- tronic circuits leads to MOSFET's shorter or narrower than 214Tl, these effects be- come significant in design and operation. Such computer programs as the widely- used "Simulation Program With Integrated Circuit Emphasis, Version 2" (SPICE 2) in- clude many of these effects. The first-order equations for the thresh- old voltage and drain current are derived from basic equations of electrostatics and the physics of semiconductors, with simpli- fying assumptions regarding the distribu- tions of charges, currents, and electrosta- tic potentials. The second-order equations, which provide partial corrections for these NASA Tech Briefs, January 1990 assumptions, are grouped into four cate- gories. One category includes equations for the effects of shortness and narrowness of the channel on the threshold voltage. The sec- ond-order equation for the short-channel effect is derived by representing the side- view cross section of the gate-depletion region as a trapezium or trapezoid, to ac- count for the encroachment of the junc- tion.<:Jepietion regions on the rectangular gate.<:Jepletion region of the first-order model. The second-order equation of the narrow-channel effect accounts for the fact that the gate depletion includes an ap- proximately-wedge-shaped bulge beyond the sides of the metal gate (see figure). This category also includes the static feedback effect, alternatively called drain-induced barrier lowering, which accounts for the ef- fect of the drain-te-source voltage on the threshold voltage. The next category involves equations for the drain-te-source current. The effects of shortness, narrowness, and drain-in- duced barrier lowering are taken into ac- count to obtain a more precise equation for the drain current. Of particular interest are the equations for saturation and subthres- hold (leakage) drain currents. This cate- gory also includes an equation for the shortening of the effective channel length that occurs when the drain-to-source voltage exceeds the saturation value. The models of the third category ac- count for the decrease of the drift mobility of electrons at the surface of the channel. Such quantities as the drain current and the propagation delay depend strongly on the mobility. Transverse electric fields af- fect the mobility by driving electrons into the Si/Si02 interface, while longitudinal electric fields affect mobility via the drift velOCity. The effect of both fields combined can be expressed in a Single equation as a 1------ Length of Gate - - ----l'1 / n + Source / n+ Drain / AL------->o.,_---"'-,/_// ~ Second-Order '-'-_______ ,-______ ----') Second-Order Depletion V Depletion Second-Order Additions First-Order Gate Depletion Region P Bulk CROSS SECTION LOOKING ACROSS CHANNEl t----- Width of Gate ----'~I Flrst-Order Depletion Region CROSS SECTION LOOKING ALONG CHANNEL Second-Order Additions In the Second-Order Models of an n-channel, enhancement-mode MOSFET, the first-order gate-depletion region Is diminished by triangular-cross-section deletions on the end and augmented by circular-wedge-cross-section bulges on the sides. function of the drain-te-source voltage. equations for the gate/source- and gatel The last category includes equations for drain-oopletion capacitances. capacitance and the conservation of elec- This v-.ork was done by Reuben Benumof, tric charge. For this purpose a MOSFET is John A. Zoutendyk, and James R. Coss of represented by an assembly of capacitors Caltech for NASA's Jet Propulsion lab- with appropriate series and parallel con- oratory. For further information, Circle 31 nections. Equations for the input capaci- on the TSP Request Card. tance under saturated and unsaturated NPO-17395 conditions are derived from the basic Asymmetric Memory Circuit Would Resist Soft Errors Some nonlinear error-correcting codes are more efficient in the presence of asymmetry. NASA's Jet Propulsion Laboratory, Pasadena, California A combination of circuit-design and coding concepts is expected to make inte- grated-circuit random-access memories more resistant to "soft" errors (temporary bit errors, also called "single-event upsets" due to ionizing radiation). An integrated cir- cuit of the new type would be made deliber- ately more susceptible to one kind of bit er- ror than to the other, and the associated error-correcting code would be adapted to exploit this asymmetry in error probabili- ties. A random-access memory can be re- garded as a communication channel with a long delay, in which the writing and read- ing operations correspond to transmitting NASA Tech Briefs, January 1990 and receiving, respectively. In a binary symmetric communication channel, the probability of an erroneous transition from o to 1 equals the probability of an errone- ous transition from 1 to O. Unear error-cor- recting codes for binary symmetriC chan- nels are well developed; such codes can be applied to data written into symmetric random-access memories, and decoding and error correction can take place during the subsequent reading operation. The error-correcting capability of such a code increases with the apportionment of more bits within fixed-length code words as parity-check bits. Thus, as the error-cor- recting ability increases, less information can be stored and retrieved, and vice ver- sa. In a random-access-memory cell, the probability P(01) or P(10) of an erroneous zero-to-one or one-to-zero transition, re- spectively, can be increased by enlarging those circuit elements that are more sus- ceptible to one of these types of error (see figure). Nonlinear group-theoretical error- correcting codes can be adapted to exploit the asymmetry of an ideal binary asym- metric channel, in which only one kind of erroneous transition occurs [e.g., P(10) = 0]. In practice, it is not necessary to have an ideal binary asymmetric channel as long as the ratio of transition probabilities is 23 Draln·Supply· Voltage Line O Thin Oxldel Di ffusion • Contact Bit Ground Line line ~Jpwell o Metal I I I Word Line ____ J Draln·Supply·Voltage Line Bit Line o Polycrystalline r--, + Silicon ' , p L_..J ~ Drains for " Zero" State ~ Drains for " One" State The Drains of 8 Random·Access-Memory Cell that are susceptible to single-event upsets are indicated by crosshatching. Those for the "zero" state are greater than those for the "one" state. Thus, erroneous zero·to-one transitions are more probable than are erroneous one-to-zero transitions in this circuit. sufficiently large [e.g., P(01)/P(10) > the length of a codeword] and as long as the greater transition probability [in this exam- ple P(01)] is less than one-half. For a given fixed codeword length and error-correcting capability, the number of distinct code words in a group-theoretical code for a binary asymmetric channel often exceeds the number of code words in a code for a binary symmetric channel. Equivalently, for the same codeword length and error-correcting ability, a binary asym- metric channel can carry more bits of data - or use less overhead. In an error- correcting asymmetric random-access memory based on this concept, the pro- portion of an integrated-circuit chip de- voted to the correction of errors can thus be made smaller than in a symmetric ver- sion. Alternatively, for the same error-cor- recting proportion, the error-correcting capability of the asymmetric version can be greater. This work was done by Martin G. Buehler and Marvin Perlman of Caltech for NASA's Jet Propulsion Laboratory. For further information, Circle 130 on the TSP Request Card. This invention is owned by NASA, and a patent application has been filed. Inquiries concerning nonexclusive or exclusive license for its commercial development should be addressed to the Patent Counsel, NASA Resident Office-JPL [see page 16J. Refer to NPO-17394. Welding-Current Indicator ~J A light flashes on to indicate high current. Marshall Space Flight Center, Alabama A simple, inexpensive display circuit in- dicates when the 3,OOO-A welding current fl:h import, and pOJtScript rmtput. MathCAD is fur and away the best-selling math package in the world. Because it lets you perform engineering and scientific calcula- tions in a way that's faster, more natural and less error-prone than the way you're doing them now- whether you're using a scratchpad, calculator, spreadsheet or program that you wrote yourself. And now we've made the best even better. MathCAD 2.5 is a dra- matically improved version that in- cludes three-dimensional plotting, enhanced numerical analysis, and the ability to import HPGL files from most popular CAD programs, includingAutoCAD~ And now you can print on PostScript- compatible printers. And like before, MathCAD's live document interface" lets you enter equations anywhere on the screen, add text to support your work, and graph the results. Then print your analysis in presentation-quality documents. It has over UO commonly used functions built right in, for handling equations and formulas, as well as exponentials, differentials, cubic splines, FFfs and matrices. No matter what kind of math you do, MathCAD 2.5 has a solution for you. 10 fact, it's used by over 60,000 engineers and scientists, including electrical, industrial, and mechanical engineers, physicists, biologists, and economists. r;;~;;;;:;;;1 But don't take our word for it; just ask the experts. PC Magazine recently described MathCAD as "everything you have ever dreamed ofin a mathemat- ical toolbox." And for Macintosh- MarchI", 1989i.ssuc. Best of '88 Best of '87 users, we present MathCAD 2.0, rewritten to take full advantage of the Macintosh interface. Entering operators and Greek letters into equations is pure simplicity! Look for MathCAD 2.5 at your local software dealer, or give us a call. For more information, a free demo disk, or upgrade information, dial1-800-MATHCAD (in MA, 617-577-1017) . Available for IBM- compatibles and Macintosh computers. TM and ® signifjr manufuctUn:r's trademark or manufactUrer's rcg;sn:n:d tradcm2r1t n:spcctivcly. MatheA MathSoft, Inc. One Kendall Square, Cambridge, MA U.K.: Adept Scientific 0462-480055; France: I ECEGOS 1-46092768; Germany: Softline07802-4036; Japan: CRC03-665-9768. PE Circle Reader Action No. 628 of the ring may indicate the width of the back bead. The monitoring and analyzing subsys- tems could be integrated into the overall control system of a robotic welder. The control system would set the welding pa- rameters (current, vertical position, speed, and the like) to adapt to changing condi- tions, maintaining the surface contour that gives the desired pattem of reflections. This function could be combined with the developmental through-the-torch seam- tracking function, which can derive feed- back signals from the same coaxial vifNJ. This work was done by Stephen S. Gordon and David A. Gutowof Rockwell In- ternational Corp. for Marshall Space Flight Center. No further documentation is available. MFS-29450 VLSI Architecture for Viterbi Decoder Circuits of reasonable size can process convolutional codes of large constraint lengths. NASA's Jet Propulsion Laboratory, Pasadena, California A "pipeline" architecture has been de- veloped for very-large-scale integrated (VLSI) Viterbi decoding circuits for binary convolutional codes of large constraint lengths. In this scheme, a single sequential processor computes the path metrics in the trellis diagram (the diagram in which the paths and nodes represent the possible sequences of code states and in which the metrics indicate the relative likelihoods of the sequences). The systolic-array method is used to store the path information as well as to choose the path with the best metric. The basic Viterbi decoding algorithm processes the received message in an iterative manner. At each step, it compares the metrics of all paths entering each de- coder state and stores the path with the largest metric (the "survivor" path), along with its metric. The number of possible de- coder states and, consequently, the com- plexity of a conventional decoding circuit increase exponentially with K, the con- straint length of the code. For example, with K = 14, the number of states is2K- 1 = 213 = 8,192: This is too large for implemen· tation on a single VLSI circuit chip, and heretofore, the practical limitation on the number of input/output pins on a chip has made it difficult to partition a decoder into multiple chips. The new decoder architecture executes a modified Viterbi algorithm in which the path memory of the decoder is truncated and the message is, in effect, decoded in pieces 5K long, rather than as a whole. The decoding functions are performed by a data-rearrangement unit, a metric-compu- tation-and-path-decision unit, a data-multi- plexing unit, and a data-storage-and-path- selection unit (see figure). The data-rearrangement unit contains shift registers of length 2K -2. This unit. changes the sequences and correspond- ingly rearranges the partial path metrics of data fed back serially from the data-mUlti- plexing unit. The Shift-register cycle is n times as fast as the master-clock cycle of the system (where n is the number of code bits needed to transmit 1 uncoded informa- tion bit). The metric-computation-and-path-deci- 28 Rearranged Part ial Path Metrics (n Parallel Data) Coded Input Informat ion Bits, Paths, and Path Metrics (n Parallel Data) Data· Rearrangement Unit Metrlc·Computation·and· Path·Declsion Unit Data· Multiplexing Unit Node Metrics (Serial Data) Information Bits and Paths (Serial Data) Comparisons of Path Metric s Oata·Storage·and· L--_____ ~ Path·Selection Unit Decoded Output This VLSI Vlterbl·Decoder Architecture is a compromise between speed and complexity. The size of the decoding circuit increases approximately linearly with the constraint length of the code, and additional circuit chips can be added with moderate numbers of interconnec- tions. sion unit computes the new partial metrics of all the paths entering a state by adding the computed branch metrics entering that state to the metric of the connecting sur- vivor at the preceding time unit. The partial path metrics of all paths entering each state are compared, and the survivor and its metrics are selected while other paths and rnetrics are eliminated. The data-multiplexing unit changes the n parallel outputs of the metric-computa- tion-and-path-decision unit to sequential order. This can be done by use of a switch operating n times as fast as the master clock so that the two output data from the metric-computation-and-path-decision unit can be sampled adequately. The data-storage-and-path-selection unit stores both the surviving paths and the estimated information bits. The decoding decision is made after 5K periods. The in- formation bits stored in the data-storage subunit are then read out sequentially, yielding the most-likely estimated informa- tion contained in the received coded mes- sage. The new decoder architecture is an en- gineering compromise between complexi- ty and computing speed. In the new ar- chitecture, the complexity increases only linearly with K, and consequently a moder- ate-constraint-Iength decoder can be built on a single VLSI circuit chip by current fab- rication techniques. Where K is too large for a single-chip implementation, the new architecture makes it possible to partition a Viterbi decoder with relative ease into sev- eral chips with a moderate number of inter- connections. This work was done by In-Shek Hsu and Trieu-Kie Truong of Galtech and I. S. Reed and J. Sun of the University of Southern California for NASA's Jet Propulsion Laboratory. For further information, Circle 100 on the TSP Request Gard. This invention is owned by NASA, and a patent application has been filed. Inquiries concerning nonexclusive or exclusive license for its commercial development should be addressed to the Patent Counsel, NASA Resident Office.JPL [see page 16]. Refer to NPO-1731o. NASA Tech Briefs, January 1990 Generating Weighted Test Patterns for VLSI Chips ~~ Built-in self-testing circuitry is based on probabilistic fault-detection concepts. NASA 's Jet Propulsion Laboratory, Pasadena, California Improved built-in self·testing circuitry for very-large-scale integrated (VLSI) digital circuits is based on a version of the weight- ed-test-pattern-generation concept, in which ones and zeros in pseudorandom test pattems occur with probabilities that are weighted to enhance the detection of certain kinds of faults. In comparison with previouS built-in testing circuitry, the im- proved circuitry requires fewer test pat- terns and less computation time and oc- cupies less area on circuit chips. In the new approach, functional test pat- terns ordinarily used to verify designs are also used to derive the desired weights. Because it is customary to generate such patterns in any event, this involves no addi- tional cost. It is also necessary to simulate the logic of the circuit to be tested to 0b- serve the outputs that should occur upon application of each functional test pattern or set of patterns. It is easy to relate the switching activity in the outputs with the fault~tection activity by use of probabilis- tic fault~tection techniques. The steps of the new approach are as follows: 1. Generate a set of functional test patterns for the circuit to be tested. 2. Simulate faults in the circuit to be tested, and record the faults that are detectable via changes in the outputs. 3. Count the frequencies of recurrence of ones and zeros. 4. Correlate the number of faults detected with the frequencies detel\Tlined in step 3. 5. Use the signal probabilities from the preceding steps to weight the pseudoran- 00m pattems generated by the linear- feed:>ack shift register (which is the part of the built-in test circuit that generates the test patterns). Inp;)ts This Four-Bit Arlthmetlc-and·Loglc Unit, the RCA CD40181 (or equivalent), has been used widely to test test-pattern-generatlon concepts. 6. Simulate faults to determine whether ad- ditional faults can be detected. The new approach was applied to a commercially-available combinational cir- cuit (see figure). The result was 12 weight- ed test patterns that detected all of the stuck-at-one and stuck-at-zero faults. This "WOrk was done by Fardad Siavoshi of Caltech for NASA's Jet Propulsion LaboratOlY. For further information, Orele 66 on the TSP Request Card. NPO-17514 Portable High-Frequency Data-Acquisition System ~~A compact unit would be made of readily available solid-state components. Lyndon B. Johnson Space Center, Houston, Texas A proposed system for the a~uisition of rapidly changing data would be self-<:on- tained and portable. The system was con- ceived for monitoring such aerodynamic effects as flutter, vibration, shock, sound, and pressure. It offers precise and fast ac- quisition of data and large data-storage capacity: it would have a maximum sam- pling rate of 125 kHz, an access time of 15 30 ns, and a 1-mililon-bit memory. The system would measure time with a "smart" (microprocessor-controlled) watch that could maintain calendar time for more than 10 years without external power. It would provide standby power from a "smart" battery that could furnish up to 1 ampere-hour of charge if power from the main batteries were lost. A silicon transducer would send an ana- log signal representing the dynamic phe- nomenon being monitored to an integrated analog-todigital (NO) package (see figure). There, the signal would first be processed through a low-noise, fast operational amplifier. An antialiasing filter would re- move some unwanted noise and eliminate false signals caused by the convolution of NASA Tech Briefs, January 1990 AT&T DSPs, packed with powerful telecom capabilities, give you the design flexibility you need to tum product dreams into marl{et realities. Whatever your application-PBX, modem, central office equipment-we can help you make it work. With the fastest flXed point chip on the market- our 2Sns DSP16A With the multi- functional architecture of our floating point DSP32132C. And with application notes to help complete your solution. Our DSPs let you implement up to 32 Dual Tone Multi-Frequency receivers (DTMFs) on a Single chip. Build in echo cancellation for superior long-distance transmission. Or implement a full duplex CCIlT-standard ADPCM trans- coder, to double the data on a n line. Plus, /IT&T DSPs permit a glue-free interface with all ATBif codecs. Design time? Our application notes will get you by every snag. We offer Simulators, assemblers, and linkers for our full DSP line. A C-compiler for our floating point devices. An application library with math, FFT and filter func- tions. And Hewlett Packard is developing an emulator for our DSP32C. You'll also have the full support of /IT&T's Field Application Engineers, Technical Support Group, and /ITBif Bell Laboratories' DSP deSigners. For more on the DSPs designed for design-in success, just call /IT&T Microelectronics at 1800 372-2447. the input-signal spectrum with the spec- trum of the output pulse train. A sample- and-hold circu~ would store brief (2·BiAS) samples of the filtered signal. Rnally, an AID converter would dig~ize the sample to 12 ~s at a rate up to 125 kHz. An electronically erasable and program- mable read-only memory (EEPROM)would store the dig~ized signal. A central proces- sing unit (CPU) would control the EEPROM as well as retrieval of the stored data through e~er direct serial electrical out- put or a radio transmitter. Uthium batteries or an optional extemal source would provide power. The "smart" battery would take over if the main I~hium batteries or the external source were to fail. The voltages of all power sources would be regulated. A clock would synchronize the system and operate an ~alog trigger, which would start and stop the acquis~ion of data. 0p- tionally, an external trigger could be used for this purpose. The "smart" watch would keep time in hundredths of seconds, hours, days, months, and years. It would monitor the main power supply and, if it found the voltage going low, would switch to ~s own lithium battery so that it could keep run- ning. This work was done by Roy W. Mustain ware and full compUter cabtIoL I I EId8mII Trigger Analog Clock Trigger I J y .---- Central Processing Unit Radio Transmitter and Receiver Serial Output LIthium Batteries Silicon Analog Sensor " Smart" Watch _I L Analog·to-Dlgltal Package Operational Amplifier ---- --~ Antlallaslng Filter ----- Sample·and·Hold Circuit ------- Analog·to-Dlgltat Converter EEPROM "Smart" Battery t Voltage Regulator t T Optional Extemal Power The Integrated Analog-to-Dlgltal Package Is essential to the conceptual data-acquisition system. A commercial component, the package offers high speed and precision. Data could be retrieved directly through a serial output port or remotely via a radio transmitter. of Rockwell International Corp. for John· son Space Center. For further informa- tion, Circle 13 on the TSP Request card. MSC-21521 simultaneous data collection and analysis, 100 samples or 100 positions on a single sample can be analyzed without operator intervention. The 3S-R10 is equipped for reliable, unattended operations. a 10 l'Ost • S Co Graber Road, Box 310 Middleton, Wisconsin 53562-0310 Thl. 608/831-7600 • Thlex 26-5430 • Fax 60812564103 32 Circle Reader Action No. 630 NASA Tech Briefs, January 1990 Books and Reports These reports, studies, handbooks are available from NASA as Technical Support Packages (TSP's) when a Re- quest Card number is cited; otherwise they are available from the National Technical Information Service. Hypercube·Computer Analysis of Electromagnetic Scattering The capabilities of hypercube and parallel processing are demonstrated. A report describes the use of the Mark III Hypercube computer to analyze the scat- tering of electromagnetic waves. The pur- pose of this study was to assess the utility of parallel computing in such computation- intensive problems as those of large.scale electromagnetic scattering. Two electro- magnetic codes based on different algo- rithms were converted to run on the Mark III Hypercube. The first code implements a finit&dif- ference, time«>main solution of Maxwell's curl equations. This code can simulate the propagation of an electromagnetic wave Into a volume that contains a dielectric or conducting object. The incident wave is tracked as it propagates by executing the flnit&difference version of the curl equa- tions in each cell In a thre&dimensionallat- tlce in which the scattering object Is em- bedded. The relative independence of the finite- difference iteration in each cell in the lat- tice enables a decomposition of the prob- lem over the spatial domain. The parallel code uses the same global lattice as that constructed by the corresponding sequen- tial code but divides the lattice Into blocks of nearly equal dimensions. Neighlx>ring blocks are assigned to nodes that are di- rectly connected. This decomposition scheme assures that each node performs its discrete field updates either with resi- dent information or with information com- municated by a node directly connected to it. The second code is the Numerical Elec- tromagnetlcs Code (NEC-2), which embod- ies a frequency-domain method and was developed to analyze the electromagnetic responses of antennas and other metallic structures .. This code uses integral equa- tions to compute the currents Induced on a structure by sources or incident fields. It combines an integral equation for smooth surfaces with one specialized for wires to provide for the mathematical modeling of a wide range of structures. The use of these equations with Ix>undary-condltion equa- tions on the surface produces a general In- NASA Tech Briefs, January 1990 tegral equation in which the unknowns are the longitudinal currents on segments of wires and the two perpendicular compo- nents of the surface currents on patches. These equations are solved numerically by a technique based on the method of m0- ments. The solution requires the Inversion of a matrix, the size of which increases with the size of the scattering object in relation to the wavelength. In the parallel Implementation, the inver- sion Is performed by a factorization of the matrix into a right triangular matrix by a series of orthogonal Householder transfor- mations. Since the computations within one column of the matrix are independent of those in others, the matrix to be factored is distributed to the nodes of the hypercube computer by columns. At each step of the transformation, one more column of the working matrix becomes inactive. To as- sure optimum balance of the computation- alload, the assignment of columns is per- formed in card unit cells; on the Mark III Hypercube wi~ 32 active nodes, the largest lattice con- tains about 2,048,000 unit cells. This work was done by J. E. Patterson, P. C. Uewer, R. H. CalaIo, and F. Manshadi of CaJtech for NASA', Jet Propuilion lab- oratory. To obtain a copy of the report, "Electromagnetic Scattering Analysis on a Hypercube Parallel Architecture," Circle 59 on the TSP Request Card. NPO-17551 Circle Reader Action No. 303 33 Physical SCiences H.rd •• r., Technlqu •• , .nd Proc ..... 34 WldH=leld, Two-Stage Optleel System 38 Acoustophor .. ls - A New s.paretlon Concept Computer prog,.m. 48 Computing Orbltel Viewing Parameters 34 Balllstlc-Electron-Emlsslon Microscope 38 Compect, Broadband Infrared Spectrometer Wide-Field, Two-Stage Optical System r j Wide-field, triple-Schmidt optics correct errors in large primary mirror. ~ is applied to remove wavefront errors NASA's Jet Propulsion Laboratory, Pasadena, California A proposed telescope would offer a wide field of view, yet be relatively inexpen· sive to manufacture. The design, in the form of three Schmidt cameras, offers a 1(}degree strip field of view, a single large- diameter collecting aperture, four SI11erica1 mirrors, and tv.o diamcn:Humed aspheric mirrors in a relatively compact configura· tion. The uniqueness of this design (see figure) is twofold. First, the large-diameter Schmidt corrector plate, normally located at the center of curvature of the large spherical primary mirror, is relayed to a subaperture Schmidt corrector plate to be shared by all three Schmidt cameras. This FIRST STAGE t - - - - l SECOND STAGE Plane of Aperture Stop No.2 Spherical / Mirror reduces the number of large-diameter 0p- tics to just the primary mirror. Second, another subaperture diamond·turned cor· rector is located at the conjugate to the pri· mary mirror for the purpose of removing the effects of fabrication errors on the pri- mary mirror surface. In a conventional telescope, a mirror of large aperture is difficult and costly to manufacture to the tolerances needed for high-acuity imaging because of its large mass and surface area. In the new tele- scope, the image of the large primary spherical mirror is relayed onto a smaller mirror surface, where a phase correction Schmidt Plate caused by the imperfect primary mirror. The primary mirror therefore need not be of the high quality that would otherwise be required. This concept enables cost-effec- tive implementation of large-diameter 0p- tics by relaxing fabrication requ~ements. The design described is an fl3 triple- Schmidt with one large-diameter optic and is the first wide-field optical system ~o in- corporate the theory of two-stage optics. This 'NOrk was done by Paul K. ¥.anhart, Apostolis A Oeslis, Steve A Maeenka, and James B. Breeklnridge of Calteeh for NASA's Jet Propulsion Laboratory. For further information, Orele 29 on the TSP Request Card. NPO-17392 Corrector (Image of Primary Mirror) Primary Mirror No.1 Spherical Mirror Transference of the Larg.Olarneter Schmidt Corrector Plate to a smaller element makes this wide-field optical system suitable for the appll· cation of the two-stage optics theory. II Ballistic-Electron-Emission Microscope . ~~ Buried interfaces are investigated with high spatial resolution. NASA's Jet Propulsion Laboratory, Pasadena, California The ballistic-electron-emission micro- scope (SEEM) erT'4)loys scanning tunneling- microscopy (STM) methods for the nonde- structive, direct electrical investigation of buried interfaces, such as the interface be- tween a semiconductor and a thin metal film. With the STM system, an emitting elec- trode in the form of a sharp tip is held within 34 a few angstroms of the surface of a sample and scanned piezoelectrically along the surface, while the current of electrons tun- neling quantum-mechanically between the tip and the sample is measured. A comput- er uses the measured current as a funcfion of position to produce a topographic image of the surface of the specimen in the form of a contour, false-coior, or other map. In the SEEM (see Figure 1), there are at least three electrodes: the emitting tip, a biasing electrode, and the collecting elec- trode, which receives the current that crosses the interface under investigation. A signal-processing device amplifies the electrode signals and converts them into a form usable by the computer. Uke the STM, the SEEM can produce spatial im- ages of the surface by scanning the tip; in addition, it can provide high-resolution im· ages of the buried interface under investi- gation. Spectroscopic information may also be extracted by measuring the collect- NASA Tech Briefs, January 1990 TAILORED OPTICAL POWER -- BB.30 dBm -22.8 - 1 From The Laboratory To The Field ... Choose The Fit That's Best For You • Highest Accuracy, Stability, Linearity • Interchangeable Optical Connectors • Power Range: -100 dBm to +10 dBm • Wavelength: 380 nm to 1800 nm • Automatic Wavelength Correction Accurate, reliable and repeatable optical power measurement is assured with Anritsu. Featuring a broad range of possible configurations, Anritsu offers the total solution for all your optical power measurement requirements. Tailor your optical power with: the dual channel ML910B or single channel ML9001A in the lab and match the same performance in the field with the ML9002A. Suit yourself ... for a demo, literature or application assistance, contact ... Anritsu America, Inc., 15 Thornton Road, Oakland, NJ 07436. Call 800-255-7234 or (in NJ) 201·337·1111. FAX 201·337·1033. IInritsu Circle Reader Action No. 492 I , dBm - ing-electrode current as a function of one of the interelectrode voltages. For example, Rgure 2 shO\AIS measure- ments taken with the tip positioned just above the surface of a gold layer deposited on negatively doped silicon. The left plot shows collector-electrode current as a function of the voltage between the base and emitter electrodes. The voltage of the transition from region A to region B is cor- related with the height of the energy barrier at the interface between the gold and the silicon. The slope of region B is determined by both the thickness of the gold and the quality of the interface between the gold and the silicon. The right plot shc1Ns col- lector-electrode current as a function of emitter-electrode current for several val- ues of emitter-base tunneling voltage. The plot shows the linear dependence of col- lector current on emitter current. This work was done by William J. Kaiser and L Douglas Bell of Caltech for NASA's Jet Propulsion Laboratory. For further in- formation, Circle 14 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 Msell Director of Patents and Ucensing Mail Stop 301-6 ~ c ::> ~ ~ € ~ c: ~ '" () II> ~ &i iii a .E j 0 () I· A ·1 •••••••••••••• • I -- -- ~;;;-T~LI~IC;;;;;- I I I SYSTEM I I PIezoelectric Scanning PoeItIoI.- of Mlcroac:ope System L __ --I Emitting -l------~~ L.C-- Electrode I Signal-Proceealng DevIce I I I I I I I I _..I...J.-_I Computer I L.: __ ~ Figure 1. The Ballistic-Electron-Emission Microscope is a scanning tunneling microscope equipped with extra electrodes and signal-processing equipment to extract additional infor- mation about the specimen. California Institute of Technology 1201 East California Boulevard Pasadena, CA 91125 • • • • c: ~ '" () II> • ~ 13 II> • iii B a c: 13 • .!! • 0 () • • • • • • • • Refer to NPO-17384, volume and number of this NASA Tech briefs issue, and the page number. 150 A ~ • :r. • • • • • • • V1 • • • • • • • • • V2 • • • • • • • • • V3 Applied Potential Between Biasing and Emltting·Electrode Current Emitting Electrodes, Arbitrary Units Figure 2. These Measurements Were Taken on a gold-silicon diode structure in an apparatus like the one shown schematically In Figure 1. These plots reveal properties of the gold layer and the gold/silicon Interface. 36 NASA Tech Briefs, January 1990 real-time computing n computer ~ci. 1. DetertninistiC response to real- t1me events. 2. }ligh I/O tbroughput of acC\.uir ed data. 3. Simultaneous d~ta acC\.uisition, digital signal processlng, graphiCS display, data storage and communications. real-time computers n computer.S ci . 1. Concurrent Computer Corpor~tlon. 2. Standards-based multiprocessmg systemS from 3-160 M1P s . r--------I Concurrent Com - - - - -I Communicali pule' Cmpo.ati - - - -I New Je.sey 00;'2; 06 Apple s,,~~i ~,po.ale ' O y • inIon Falls I I es. please hel . solution. p me define my' I I re~~~ ''''' computing I I I W' I - I efine your real-tima~ ~~8~O-6.31-2154 to I ADDRESS ----- I d rite or call us I '0'"'' putlng solution. I '''' I I fE!!!J I PHONE NO STATE - ZIP I Concur, I "' """.,m. I COm rent I !pUter Corporation L - - - - I __ I ----- ___ NT- 1 .J --- Defining the standard . C In real r-lrele Reader Action N- {me computing. 0.581 Acoustophoresis - A New Separation Concept Ultrasound separates chemical species. Langley Research Center, Hampton, Virginia A concept under development may ex- pand the technology of chemical separa- tion to include ultrasonic-radiation pres- sure. When an ultrasonic wave passes through a medium, it carries energy and momentum: the loss of energy by the wave is accompanied by a transfer of momen- tum to the substance that carries the energy. For example, since molecular chains have different nonlinear properties and absorb ultrasonic energy through such mechanisms as resonance relaxa- tion, the forces on these chains depend on the frequency of the sound. Therefore, by selecting a specific frequency, one can "tune in" to a selected chemical proper- ty - acoustic absorption - and separate chemical species (with different absorp- tion coefficients) that may be impossible to separate by other means. For the separation of particles, the choice of acoustic wavelength will change the acoustic scattering process and thus the force imparted to the suspended par- ticles. As the frequency is varied from low to high, the larger particles (those with higher scattering cross section) will scatter the sound first, followed by the smaller par- ticles. Thus, the larger suspended particles will be swept from the liquid first by the transferred momentum. As shown in the figure, the feed source supplies the liquid medium containing the desired species in mixture with other spe- cies. The liquid is fed into the separation container. An ultrasonic transducer con- nected to an ultrasonic driver sends an ultrasonic wave into the liquid, exerting on the desired species an acoustic-radiation force that depends on the absorption of the UltralOl1lc Driver Separated Species Separating Ultrasonic Transducer Separation Container Antlstreamlng Ultruonlc Transducer The New Technique separates species of particles according to their ultrasonic properties. acoustic wave and on nonlinear interac- tions. Thus, the propagation results in a separation based on the absorption (or scattering) of the acoustic wave. The separated species are removed se- quentially by a pump and placed in dif- ferent compartments (a,b,c,d). If the ab- sorption in the different species is nearly equal, then acoustic streaming may mix the liquid, preventing separation. To mini- mize that effect by counteracting the streaming, a second transducer is driven by an antistreaming device. In effect, the second acoustic wave can be tuned to a frequency different from that of the first, and to a different amplitude, thereby pro- ducing a high-resolution "shearing" of the liquid into its separate species. The acoustophoresis concept can uti- lize not only bulk compressional waves but also surface waves or boundary waves between a solid (or liquid) container wall and the subject liquid. The free surface of the subject liquid acts as a waveguide that contains the input acoustic energy. This work was done by Joseph S. Heyman of Langley Research Center. For further information, Circle 43 on the TSP Request Card. This invention is owned by NASA, and a patent application has been filed. Inquiries concerning nonexclusive or exclusive license tor its commercial development should be addressed to the Patent Counsel, Langley Research Center (see page 16]. Refer to LAR-13388 Compact, Broadband Infrared Spectrometer ~JAdouble-pass Schmidt optical system is stable and light in weight. NASA's Jet Propulsion Laboratory, Pasadena, California A large-aperture, wide-angle, broad- band infrared spectrometer is compact and light in weight. It is based on a double- pass version of the Schmidt optical system that acts as both a collimator and a cam- era. Because the optical system is con- tained in a piece of solid glass, it is me- chanically and thermally stable. Radiation in the wavelength range of 850 to 2,500 nm is fed from optical fibers into the spectrometer through a flat en- trance surface. (As shown in the figure, the 38 cable of optical fibers appears to coincide with an array of PbS detectors and to face a blocking filter in front of the array but in fact is displaced from the array out of the page.) Because of the high index of refrac- tion of the glass relative to that of air, the angle of divergence of the marginal rays in the glass is Significantly less than it is before it enters. This is one of the reasons the instrument can be made to operate at the relatively-large numerical aperture of 0.51. The diverging rays are roughly colli- mated by the primary mirror surface, which is coated with aluminum protected by a black epoxy paint overcoat. A narrow stripe across the center is left uncoated by aluminum to prevent reflection of the in- coming radiation from this stripe directly back onto the array of detectors. The roughly collimated rays are turned about 90° by total internal reflection at the folding surface, then pass out of the glass optical system through an aspherical Schmidt NASA Tech Briefs, January 1990 It's easy. How to improve your station in life. From now untilJune 30,1990, just trade in your VAXstation'" 2000 workstation and Digital will give you $2,000 off the purchase price of our VAXstation 3100 workstation. When you do, you're getting a lot more than just money off. The VAXstation 3100 workstation delivers 3 to 4X the performance of the 2000. The VAXstation 3100 workstation lets you run DECwindows'" software. It gives you a consistent user interface for accessing applications on your net- VUPs Memory Disk Capacity Resolution Planes VAXstation 2000 VAXstation 3100 work whether they're running VMS;"UNJX®/ ULTRIX"" or MS- DOS~ You choose what you want 1 4 6-14MB 8-32MB 70-1.3 GB 1,024 x 864 1,4,8 104-1.3 GB 1,024 x 864 1,8 and it shows up on screen the way you want. And,even though the VAXstation 3100 worksta- tion is an upgrade, you can use all the same software you've been using on the 2000. With no rewriting. Take the all-important first step toward improving your station in life. Call 1-800-343-4040, ext. 874 to take advantage of this special $2,000 offer. Digital lias it now. corrector surface that makes the roughly collimated beam well collimated. A diffraction grating then disperses the radiation angularly according to wave- length and reflects it back through the opti- cal system to the array of PbS detectors. Functioning as a camera on the retum pass, the optical system focuses the spec- trum on the array, where wavelength is read as a function of position (picture- element number). The spectral range is covered by 45 picture elements. The optical system is made of water- free fused silica to minimize absorption of infrared radiation. Although In principle it could have been made from a single, solid piece, In practice it has to be made in two pieces that are then cemented together. Fabrication muld be easier and simpler if even more cemented surfaces could be used so that each optical surface could be ground and polished like a single lens ele- ment. However, more cemented surfaces are not used because optical cements ab- sorb in the infrared. This work was done by Norman A. Page and Mary L White of CaJtech for NASA's Jet Propulsion Laboratory. For further in- formation, Qrc/e 17 on the TSP Request card. This invention is owned by NASA, and a patent application has been filed. Inquiries Infrared Radiation Grating Folding Surface Flat Entrance Surface Primary Mirror I The Double-Pass Design makes this spectrometer compact. Because most of the optical system lies within a solid piece of fused-silica glass (actually, two pieces cemented together), the instrument is rugged. concerning nonexclusive or exclusive license for its commercial development should be addressed to the Patent Counsel, NASA's Resident Office.JPL [see page 16]. Refer to NPO-17562 TEAC's compact airborne videocassette recorders are in operational use on over a dozen types of high performance jet aircraft. We built the first air- borne videocassette recorder. And with over seven- teen years of experience to back us up, we are the undisputed leader in airborne videocassette record- ing. We've been on board all US. Space Shuttle flights. Over 15,000 TEAC airborne video recorders are in use around the world today. And TEAC guarantees sup- port of its designs for the life of your program. Our recorders are designed for operation in the harsh environment of shock, vibration, high g-load- ing, high altitude, and wide temperature variations. The units meet or exceed MIL-STD-810C, MIL- STD-46IB/462, and MIL-STD-704C. TEAC's flexible signal formatting capability and extreme adaptability are the world standards for high performance airborne video recording. Anything else could leave you grounded. TEAC8 AIRBORNE VIDEO PRODUCTS DMSION © 1989 TEIIC AMERICA. INC. (213) 726-0303 FAX: (213) n7·7621 40 Circle Reader Action No. 344 NASA Tech Briefs, January 1990 We've all heard old timers say that. Often, it's the right philosophy. More often, it is not. Machines wear out too! Sometimes it's Dot a matter of a machine breakiDg, but working as well as it could- or should. • Do your machines wear out too fast? • Sticky operation? • Consume too much power? • Require too much breakout 'torque? Usually it's not a matter of a machine breaking down, but of workinf as weIr as it could, or should. ICyour machines are Dot "broke" but areD't WOrkiDg quite right, call us. We've saved miliioDs for OEM s in highly specialized lubricatioDjobs iD the last few years. THESE SEM PHOTOS SHOW WHY TUFOIL IS SO IMPORTANT TO THE UFE OF YOUR MACHINESI At Fluoramics, we specialize iD pateDted lubricatioD techDology, using very fine colloids of "Teflon@ or F1uon@". The U.s. Government has awarded us 6 patents so far, so have Germany, EDgiand, France aDd Canada. Tufoil@ has a surface frictiOD of .029 according to a major U.s. Govern- ment laboratory. That's slipperier than the Handbook data for TefloD Why use lubricants that were developed in the horse and buggy era in your modern machines? Use Tufail! FUJON 10- TEFlON DUPONT- lUFOIL FUJORAMICS- Circle Reader Action No. 364 If you want your machiDes to last lODger and ruD smoother, cooler aDd use less energy, call us.We develop speciallubricaDts for jobs where all others have failed. Our LubricatioD Pack will give you a variety of Tufoil products for just about aDY applicatioD! You'll get one each of Tufoil for EDgines, In- dustrial Tufoil, GUD-Coat, Lubit-8, Lox-8 Grease, Lox-8 Paste, Formula 8, UghtDing Grease aDd Compu- Lube. See For Yourself! There's sure to be one that's just the right solutioD for you! Just send $50.00 (the price includes shippiDg) aDd we'll process your order immediately! Or place your order using our TOLL-FREE num- berbelow! ORDER NOW! 1-800-922-0075 (In N.J.) 201.a25-8110 FAX: 201-825-7035 ~ Fluoramlcs, Inc . .:J 103 Pleasant Avenue Upper Saddle River. N.J. 07458 Malerlals Hard.are, Techniques, and Proc .... s 42 Isomeric Trluryloxycyclotrlphos- phazene Polymer Precursors Books and Reports 42 Survey of Infrared- Absorbing Coatings 44 Electrochemical Study of Corrosion of Painted Steel Isomeric Trisaryloxycyclotriphosphazene Polymer Precursors ~ These substances are useful for making heat- and fire-resistant polymers. Langley Research Center, Hampton, Virginia One goal in the synthesis of high-per- formance thermoplastic polymers for ad- hesives and graphite-reinforced ~ ites is to de-Jeq:> ~es with enhanced properties, including toughness, thennal stability, and meltprocessability. Cyclotri- phosphazene{)ased monomers and pol- ymer precursors have led to the devel- opment of high-temperature materials. Cyclotriphosphazene-derived monomers, polymer precursors, and polymers are be- coming important from both industrial and scientific points of view. The presence of the phosphazene moi- ety in cyclotriphosphaze~sed mono- mers and polymer precursors is expected to impart special properties in desired high- performance materials containing inor- ganic backbones for aerospace applica- tions. The initial phase of research on these materials has been devoted to the develop- ment of various cyclotriphosphazene.oo- rived monomers and polymer precursors, including halo-, nitro-, and amino-deriva- tives, which are potentially useful for mak- ing various polymers. EffICient procedures for the synthesis of isomeric novel amine- and nitro-tenninated trisaryloxycyclotriphosphazenes [espe- cially tris(4-nitrophenoxy)trls(phenoxy)cy- clotriphosphazenes and tris(4-aminophen- oxy)tris(phenoxy)cyclotrlphosphazenes] from hexachlorocyclotriphosphazene were developed for various reaction conditions. Chemical characterizations were per- formed by use of Fourier-transform in- frared spectroscopy, nuclear magnetic resonance, mass spectrometry, and ele- mental analysis. Tris(4-nitrophenoxy)tris(phenoxy)cyclo- triphosphazenes with melting points of 111 to 112"Cand 133 to 135 °Cwere obtained. 00 Electronic Shearography System 42 Circle Reader Action No. 629 A process was developed to separate these COI'T'pOUnds from the reaction prod- ucts, resulting in isomers that had sharpty- defined melting temperatures. The low- pressure hydrogenation of the separated nitro COI'T'pOUnds in the presence of plati- num oxide catalyst reduced the nitro grou~ to the corresponding tris(4-amino- phenoxy)tris(phenoxy)cyclotriphospha- zenes that had melting temperatures of 131 to 133 "C and 105 to 106 "C, respec- tively. The substances produced are useful for obtaining heat- and fire-resistant polymers for composites, adhesives, molding pow- ders, and coating laminates. These com- pounds might also be used in structures (e.g., secondary structures in aircraft), in the construction of spacecraft, and in the electronics and computer industries. This 'WOrk was done by Terry L St. Oair and Devendra Kumar of Langley R. search Center. For further information, Orcle 44 on the TSP Request Card. This invention is owned by NASA, and a patent application has been filed. Inquiries concerning nonexclusive or exclusive license for its commercial development should be addressed to the Patent Counsel, Langley Research Center [see page 16]. Refer to LAR-13819 Books and Reports These reports, studies, handbooks are available from NASA as Technical Support Packages (TSP's) when a Re- quest Card number is cited; otherwise they are available from the National Technicallnfonnation Service. Survey of Infrared· Absorbing Coatings Carbon black and silicon carbide grit are low reflectance additives A report presents the results of a sur- vey of candidate materials for use as at- tenuators of stray radiation in far-infra- red telescopes. More than 40 reflectance spectra at 1r incidence, in the wave- length range from 20 to 500 ~. were 0b- tained from a variety of coatings, binders, and additives. NASA Tech Briefs. Janllarv 1QQ() Coating specimens were prepared on optically flat pieces of 6064-TS aluminum, 2.5 by 2.5 by 0.32 cm. Uquid coatings were applied in drops, then smoothed to uniform thickness with a modified razor blade. Powder coatings were chopped or fluffed with a razor blade, then spread with a broad blade. Some solid coatings (glass microballoons and SiC grit) could be spread smoothly by surface tension of a few drops of propanol. Each solid coating was bound to the substrate with a thin, dilute insulating varnish that produced no detectable infrared absorption in the amount used. The thicknesses of the coatings were measured with a microscope and a com- parator. Roughnesses were measured 0p- tically and with a profilometer. A Fourier- transform interferometer was equipped with three beam splitters, two light sources, and two photodetectors to measure over- lapping reflectance spectra that, together, covered the full spectral range. Some additives alone or in combination with certain binders exhibited specular reflectances less than 0.1 at all wave- lengths of interest: these include carbon black; No. 180 SiC grit; No. 80 SiC grit; Black Suede binder conSisting of black iron oxide in polyurethane, with carbon black and No. 80 SiC grit; Chemglaze Z-306 bind- er consisting of carbon-black-pigmented polyurethane, with No. 80 SiC grit; and ECP-2200 binder consisting of jagged sili- ca particles in a silicone binder containing a proprietary black dye, with carbon black and No. 80 SiC grit. The SiC particles are believed to enhance attenuation by impart- ing roughness to the surface and by scat- tering the incident radiation into the bulk of the coating, thereby increasing the optical path length. Other coating materials that were test- ed include an electroless nickel plate with nitric acid etch, a graded-index-of-refrac- tion polyurethane coating, nylon flock, and TIBr powder. In addition, DeSoto Black (or equivalent) carbon-black-pigmented poly- urethane shows promise as a binder, pos- sibly as a replacement for Black Velvet (or equivalent). This work was done by Sheldon M. Smith of Ames Research Center and Richard V. Howitt of Teletrac, Inc. Further information may be found in NASA TM- 88204 [N88-28757]. "Survey of Material for an Infrared-Gpaque Coating. " 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. Inquiries concerning rights for the commercial use of this Invention should be addressed to the Patent Counsel, Ames Research Center [see page 16]. Refer to ARC-1176Z NASA Tech Briefs, January 1990 NEW' ... Precision ffighVoltage Solid State Anlplifiers up to +20kV and +20ntA. Four-Quadrant Capability Input: t-t---+---20V Peak to Peak r+tt+-+++++t'1lr+-+-....j-...t1t~-- Output: 40kV Peak to Peak Frequency: 1380 Hz If you need High Voltage, High Speed Precision Amplifiers, TREK has the products for you. A complete line of High Voltage Solid State Operational Amplifi- ers and Power Supplies for: ~ -' " , .. - ",. - .. ! I .LiJ - -:: :: . ~- • I .:-;. - - --- - - - - I I I ', ~ _ . - - __ ~~R .. , $ \ - - 40,000 V Peak to Peak ! Piezoelectric Research. Polymer Characterization. Ceramic Research. Laser Modulation • Electrophoresis. Ion Deflec- tion • Electrostatics. Closed Loop Charge Control. 20/20 HV Precision Amplifier: ± 20kV, ± 20mA. Slew Rate 600 V/j.IS. 610C HV Supply-Ampllfler-Controller: ± 10kV, ± 2mA. Slew Rate 35 V/j.IS. Constant Current or Voltage feed- back circuit. 6098-6 HV Research Amplifier: ± 4kV, ± 20mA. Slew Rate 100 V/j.IS. 6018 HV Plezo Driver: lkV, ± 10mA. Slew Rate 35 VIpS. 668A Reference/Power Supply: o to ± 3kV, ± 10mA Accuracy 0.01 % of full scale. Other HV Amplifiers available including custom designs. For more information CALL 1-800-FOR-TREK outside New York. ~• TREK, INC. 3932 Salt Works Road , P.O. Box 231 Medina, NY 14103 Phone: (716) 798-3140 TLX: 752278 FAX: (716) 798-3106 Circle Reader Action No. 319 43 Electrochemical Study of Corrosion of Painted Steel Resistor -and-capacitor ci rcuit models represent evolving properties of coated specimens. Electrochemical experiments on the corrosion of painted 4130 steel are de- scribed in a report. This study is part of a 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 $3.00 postage. NY residents add sales tax . Name ________ _ Address _______ _ City ________ _ State Zip __ Total enclosed: ____ _ for __ Jet videos. Send check or money order to: NASA Tech Briefs, Dept. F 41 East 42nd St., New York, NY 10017 general'development of the ac-impedance method for measurement of the properties of coated metals. Specimens of the bare or painted steel were exposed for 30 to 60 days to an aqueous solution of 3.5 percent NaO buff- ered at pH 5.4. Every 2 days, the ac im- pedance of each specimen in the solution was measured as a function of frequency from 1 mHz to 90 kHz. The de polarization resistance was also measured. Two equivalent circuits developed as mathematical models of the ac electrical properties of the corroding metal/paint system consist of fairly simple combina- tions of resistors and capacitors. By a least-squares procedure, values of the resistances and capacitances were fitted to the impedance-versus-frequency data for each specimen at each measurement interval, so that the evolution of the proper- ties of each corroding surface could be characterized. Two different types of specimen were tested during each of three phases of the study. In phase I, the steel was coated with zinc-rich primer 0.8 mil (0.02 mm) thick or red lead oxide primer 0.6 mil (0.015 mm) thick. In phase II , the coat was either 0.6 mil zinc-rich primer with 0.7 mil (0.018 mm) epoxylpolyamide topcoat or 0.5 mil (0.013 mm) red lead oxide primer with 0.7 mil top- coat. In phase III, the coat was either 1.6 mils (0.04 mm) zinc-rich primer with 2.3 mils (0.06 mm) topcoat or 1.9 mils (0.05 mm) red lead oxide primer with 2.6 mils (0.07 mm) topcoat. For comparison, an un- coated specimen was also tested. The ac-impedance method proved ef- fective in the evaluation of specimens in all three phases. The dc method was useful for the specimens of phase I (primer only) and correlated well with the ac method for those specimens. The de method did not work well for specimens of phase III. The newer and more complicated one of the two equivalent·drcuit models gave an ex- ceptional fit to the impedance data, and the value of one of the capacitors in this model was found to be directly proportional to the rate of corrosion. In phase I, the zinc-rich primer gave the best protection. In phase II, the specimens with the zinc-rich primer failed first: hydro- gen evolved in the primer, causing blisters in the topcoat. In phase III, both combina- tions of primer and topcoat continued to protect the steel adequately during the en- tire time of immerSion, though both lost electrical resistance 0ndicating some de- terioration). CNerall, it appears that both primerltopcoat combinations are ade- quate and neither is preferred over the other, as long as the primer and topcoat have adequate thicknesses. This work was done by M. H. Mendrek, R. H. Higgins, and M. D. Danford of Mar· shall Space flight Center. For further in- formation, Circle 36 on the TSP Request Card. MFS-27213 The Fotonic™ Solution For high-precision noncontact vibration measurement IntrodUCing the MTI-2000 FotonicN Sensor for noncontact measurement of vibration and displacement. .. featuring the latest advancements in electronic design and providing an unbeatable combination : affordability and unmatched performance. • Submicroinch resolution • Frequency response to 200 kHz From MTI : the pioneer in fiber-optic sensor tech- nology for over 25 years. Call toll free for information: 44 • Digital readout in engineering units • Interchangeable probe modules • RS-232 interface and 0-10V output • Target size as small as .002 in. • Dual-channel design MTI Instruments 968 Albany-Shaker Road· Latham, NY 12110 • (518) 785-2211 Telex : 685-4572 MTILATMUW· FAX: (518) 785-2806 Circle Reader Action No. 365 1·800·342·2203 .. EDMSION~==OF;:;::::MECHANICAl='='::::: TECHNOlOGY INC. , NASA Tech Briefs, January 1990 Computer Programs IT'S NEW! 45 Estimation of Interference In s.telUte/Ground Communications IT'S HERE! 48 Computing Orbital Viewing Paramaters COSMIC: Transferring NASA Software COSMIC, NASA's Computer Software Manage- ment and Information Center, distributes software developed with NASA funding to industry, other government agencies and academia COSMIC's inventory is updated regularly; new programs are reported in Tech Briefs. For addition· al Information on any of the programs described here, circle the appropriate TSP number. If you don't find a program In this issue that meets your needs, call COSMIC directly for a free review of programs in your area of interest. You can also purchase the annual COSMIC Software Catalog, containing descriptions and ordering In· formation for avallable software. COSMIC is part of NASA's Technology Utiliza- tion Network COSMIC® - John A. Gibson, Director, (404) 542·3265 The University of Georgia, 382 East Broac1 Street, Athens, Georgia 30602 OUR 1990 SOFTWARE CATALOG -------------------------------------------,- i:t Use Your PC or PC-LAN to Search by Keyword. or Hardware Type Diskettes _ ... $30.00 Computer Programs These programs may be obtained at a very reasonable cost from COSMIC, a facility sponsored by NASA to make computer programs available to the public. For information on program price, size, and availability, circle the reference number on the TSP and COSMIC Request Card in this issue. Estimation of Interference in Satellite/Ground Communications The relative strengths of desired and interfering signals are computed for known orbits. In the late seventies, the number of communication satellites in service in- creased, and interference has become an increasingly important consideration in designing satellite/ground-station com- munication systems. The Satellite Inter- ference Analysis and Simulation Using Personal Computers (AKSATINT) comput· er program calculates the interference experienced by a generic satellite com- munications receMng station from an In- terfering satellite. Both the desired and the interfering satellites are considered to be in elliptical orbits. The simulation contains computa- tion of the orbital positions of both satellites by use of classical orbital elements, calcu- lation of the look angles of the satellite antennas for both satellites and the eleva- tion angles at the desired·satellite ground- station antenna, and computation of the Doppler effect caused by motions of the satellites and the rotation of the Earth. AKSATINT also computes the interfer- ence-to-signal-power ratio, taking into ac- NASA Tech Briefs, January 1990 count losses suffered by the links. i:t Softbound version After computing the interference-to-sig- nal-power ratio, the program computes the statistical quantities. The statistical formu- lation of the interference effect is present- ed in the form of a histogram of the interfer- ence-to-desired-signal-power ratio. The program includes a flow chart, a sample run, and results of that run. AKSATINT is expected to be of general use to designers of systems and managers of frequencies in selecting the proper frequencies under in- terference scenarios. 1200 programs described & fully indexed Printed ..... $25.00 i:t Both Postpaid from COSMIC The AKSATINT program is written in BASIC. It was designed to operate on the NASA SOFTWARE 382 East Broad Street Athens, Georgia 30602 (404) 542-3265 Circle Reader Action No. 334 Get The Most Reliable Statistics Package Available Professionals need a statistics package with the depth to get the job done. That's why BMDP is the statistician's choice While other packages offer only general procedures to cover the variety of advanced techniques, BMDP provides dedicated programs that quickly and reliably test even the most strenuous multivariate models. No matter what software you're currently using for database management or graphics. if you 're doing real-life research. BMDP is your statistical edge! Our group testing programs, for example. are simply the best-including a repeated measures ANOVA & ANCOVA that accepts cases with missing trials. Call today to order, or for complete program descriptions. BMDP the statistician's choice . the researcher's edge! BMDP Statistical Software, Inc. (213) 479-7799 Circle Reader Action No. 421 45 Write For Your Free Edmund Scientific 172 Page Catalog. • LENSES • PRISMS • MIRRORS • FIBER OPTICS • OPTICS • LASERS • MAGNETS • MAGNIFIERS • MOTORS/PUMPS • TELESCOPES • MICROSCOPES • POSITIONING EQUIPMENT • COMPARATORS Features over 7,000 products! Our new, full color catalog describes one of the largest and most diversified lines in the nation of precision lenses, optics and optical instruments plus many hard-to-find scientific and technical products used in science, industry and by researchers. 11_ Serving Industry Since 1942 _ Edmund Scientific Co. Dept.1OB1 , N922 Edscorp Bldg., Barrington, NJ 08007 T81 .1-609-573-6250 • Fax. 1-609-573-6295 • Telex 831-564 Circle Reader Action No. 641 IBM Personal Computer AT or compatibles and has been implemented under MS DOS 3.2. AKSATINT was developed in 1987. This program was written by Anil V. Kanta}( of CaJtech for NASA's Jet Propul. slon Laboratory. For further information, Circle 11 on the TSP Request Card. NPO-17500 Computing Orbital Viewing Parameters A program yields data on the times of visibility of celestial objects. The QUIKVIS computer program cal- 'culates the times during an orbit around the Earth when geometric requirements are satisfied for observing celestial ob- jects. The observed objects may be fixed (e.g., stars) or moving (Sun, Moon, planets). QUIKVIS Is useful for preflight analysis by those needing information on the availabili- ty of celestial objects to be observed. QUIKVIS performs two types of analy- ses: One is used when specific objects are known, the other when targets are un- Two Outstanding Ways to Save. you can get our top-of-the-line LP4000'" pen loaded with 46 extras for just $4,995; or you can get the same package, and our PlotServr Plus'· me server, for only $5,495. Think of it, a complete plotting solution for about half of what you might otherwise pay. I 0 LIN E" This unique offer ends soon, so act now. Thlk to your local Ioline dealer or call us at ~OTTING SYSTEMS (206) 821-2140 for details. A GleaIRelumm'tflJr111l-eS/nm/'" IOUNE CORPORATION 12020 - 113TH AVE. NE KIRKlAND, WA 98034 (206),821-2140 Circle Reader Action No. 351 known and potentially useful regions of the sky must be identified. The results are use- ful in selecting candidate targets, examin- ing the effects of observation require- ments, and doing gross assessments of the effects of the right ascension of the as- cending node (RAAN) of the orbit. The re- sults are not appropriate when high accu- racy is needed (e.g., for scheduling actual mission operations). The duration of an observation is calcu- lated as a function of date, RAAN, and geo- metric requirements. The RAAN can be varied to account. for the effects of an un- certain launch time. The semimajor axis and inclination of the orbit are constant throughout the run, A circular orbit is as- sumed, but a simple modification of the program will permit the use of eccentric or- bits. The geometric requirements that can be processed are (1) the minimum angle between the line of sight to the object and the horizon of the Earth, (2) the minimum angle between the line of sight to the object and the velocity vector of the spacecraft, (3) the maximum angle between the line of sight to the object and the zenith direction, . and (4) the presence of the spacecraft in the shaoo.v of the Earth. The user must supply a date or range of dates, the altitude and inclination of the spacecraft, up to 700 observation targets, and any geometric re- quirements to be met. The primary output is the duration per orbit when conditions are satisfied for in- dividual targets. Options create printer-plot maps of potentially useful regions of the sky and bar graphs showing when indMdu- al and composite requirements are satis- fied, Line-printer output is presented in visually convenient formats. Data-file out- put is available for use by post-processing programs, such as plotters and observa- tion scheduling programs. QUIKVlS is written in FORTRAN 77 for batch or interactive execution and ha~ been implemented on a DEC VAX. 111780 computer operating under VMS with a cen- tral-memory requirement of approximately 500K of 8-bit bytes. QUIKVIS was devel- oped in 1986 and revised in 1987. This program was written by Char/es Petruzzo of Goddard Space Right Cen· ter. For further information, Circle 116 on the TSP Request Card, GSC-13083 WIKft an you find - Astronaut Ice CreamJ - luild-it-Younelf SpaceshipsJ - OffIcIal NASA 'atchesl Only ill the new aift catalOi fftHn NASA Tech Briefs. Circle Hum_ 700 for your free copy. NASA Tech Briefs, January 1990 TAKE CONTROL WITH MA TRIXx. Only one family of products offers a streamlined software environ- ment for each phase of control system development - the lSI Product Family. For aerospace, automotive, computer peripherals, industrial control, and material processing. Build a complex graphical system model. Analyze the system and design a controller. Run real-time animated simulations. Plot the results. Refine the design. Generate real-time Fortran, C, or Ada code. Download it into a target proces- sor. Run it in real-time. 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MATRIXx is the least expensive engineering analysis product avail- able today - from $595 for Pes and $4000 for workstations. ·15+ engineering bloclcs • 6 Integration algonthms ElplaillIIIIIIIIa: • Interacti'le Animation • Remote Simulation • Simulation Accelerator • Automatic Oocumentation • Project Database ReaJ:rirr¥ Code Generation Au1DCodeM : • AutomatiC Code Generation in Ada, C, or fOOran Imp/Bmentation and resting AC-1IJO'": • Real·time multi-processor system • "Hantware-In-the-Ioop" control Engineering professionals worldwide continue to rely on lSI's products to streamline con- trol system design. Now it's your tum. Call 408-980-1500 for infor- mation and a complete set of Data Sheets. ~~~egrated ~emslnc. Integrated Systems Inc. 2500 Mission College Blvd. Santa Clara, California 9SOS4 Fax: #408--980-0400 Circle Reader Action No. 557 DESIGN· SIMULATION· CODE GENERATION· IMPLEMENTATION Mechanics Hardware, Techniques, and Processes 48 Post Clamp WIth Attach.d Collar 54 Improv.d Coupl.d fluId/Structural DynamIcal Mod.1 Books and Reports 58 Mor. About Multlpl. BoundaryoCondltlon TestIng 53 M.a.urlng Dlam.t.r. of Lara· V .... I• 54 U.lng Ruby aall. a. FiducIal Marks 56 PredIctIng Pr.ssur. Drop In Porous Mat.rlals 57 Det.rmlnlng SpatIal Coordlnat.s by Las.r RangIng Post Clamp With Attached Collar 59 ComputatIonal fluId DynamIcs for Helicopter. The collar makes adjustment of optical components easier and faster. Lewis Research Center, Cleveland, Ohio A new clamp for optical posts can re- duce the time required to set up optical components. Uke earlier clamps, the new clamp joins a pair of perpendicular posts supporting a laser, lens, reflector, or other optical component and enables the posts to be rotated in perpendicular planes so E-Type Retaining Ring that the orientation and position of the component can be adjusted. The new clamp can be adjusted with only half the number of steps required by older clamps and separate post collars. Inasmuch as ad- justments have to be made again and again for many components in an optical E-Type Retaining Ring Post-Clamp Collar COMPONENTS setup, the reduction in the number of steps adds up to a significant reduction in setup time. Moreover, the new clamp, unlike some older ones, does not tend to mar a post. The post-damp body retains post·damp collars with E-type retaining rings (see ASSEMBLY The Principal Advantage oftha N.w Post Clamp Is conferred by Its E-type retaining rings, which hold the post-clamp collars to the post-clamp body. A collar can be tightened around a post to prevent movement along a post while allowing the clamp to turn around that post. Quarter- turn screws on the body and collars tighten the parts on posts. 48 NASA Tech Briefs, January 1990 ARCHITEC Multibus®II's Architetc,tur,al SIMPLE Multibus II brings more than just power to your application. It brings simplicity that speeds development and eliminates risk. Without compromising performance or economy. The spec itself (IEEE 1296) is clean, complete, disciplined. It defines a bus that is synchronous and highly deterministic. Multibus II is supported by the Multibus II Systems Architecture (MSA)- an extensive system-level open standard, MSA implements advanced functions so you don't have to. And supports standard transport protocol to simplify complex systems. MSA even includes firmware for system configuration and self-test. Choosing Multibus II can cut months off your development cycle. And zeros off your budget. Multibus II helps you re- duce costs in all the places you'd expect. Plus quite a few you wouldn' t. . Initially, Multibus II speeds develop- ment by increasing on-board functionality, and simplifying system integration. Which doesn't just reduce costs, it helps you recover them faster by getting to market sooner. _ A range of bus interface silicon economically meets the needs of high -end multi processor systems, low-cost single-CPU applications, and everything in between . • Assembly, test and maintenance costs are reduced by features like jumperless board configura- tion, and built-in self test and diagnostics. For the life of your system, • Architectural DiSCipline increases your choices, Of applications you can solve . And ways to solve them . • The Message PaSSing Coprocessor (MPC) and two new lower cost slave interface chips let you build systems ranging from high bandwidth to low-speed I/O. Economically. With full compatibility . • You have com- plete freedom of processors and software. 80x86s, 680xOs and 88000s. Running iRMX~ DOS, OS/2~ UNIX~ FlexOS* and VRTX*. In the same box. At the same time . • iSBX~ iLBX*II, MIX and OME allow vast memory expansion and custom I/O .• And, Multi- bus II's unused P2 connector opens a world of possibilities, Like AT Bus on P2 that's avail- able now. And other buses on P2 that are planned . • INTEROPERABLE Nowhere is the virtue of Architectural Discipline more apparent than in the superior interoperability of Multibus II. • All Multi bus II boards from all manufacturers work to- gether. Right out of the box . • Problematic issues like interrupt line assignments, dual-port memory allocations and slot dependence simply don't exist. • You can even mix message passing and shared memory communica- tions methods. Or migrate from one to the other with ease . • This makes unipro- cessor systems simpler to integrate, and multiprocessor systems a practical reality. And restores the original idea behind open bus architec- tures -" mix-and-match" computing . • of new products make RELIABLE Multibus II's unique advanced features make your application more reliable and easier to maintain . • Like synchronous operation with full parity error detection/correction. Built-in self test and diagnostic capa- bilities. The freedom to plug any board into any slot. And the system's ability to auto- matically configure each board without jumpers or DIP switches . • And, naturally, Multibus II uses only DIN connectors for all backplane and 110 connections . • All these features are designed into the architecture itself, as well as all Multibus II boards, backplanes, chassis and other products . • Multibus II's Architectural Discipline means reliability you can depend on . • SCALABLE Only Multibus II provides a virtually linear increase in performance as the number of boards grows. For scalable performance across your com- plete systems architecture . • Multibus II supports simple applications with low-cost "dumb" 110 boards, and shared memory communi- cations. At the high end, Multibus II's cohesive struc- ture for multiprocessing operates like a 40 Mb/sec. Local Area Network. With backplane protocols tha t can extend to Ethernet or fiber- based LANs . • Ofal1 the buses available today, only Multibus II is capable of efficiently handling the full range of applications - from simple single-processor systems, to very complex multiple-CPU applications . Just about anywhere a PC is not enough . • Today, Multibus II is • CENTRAL DATA • MICRO MEMORY INC. • supported by a wide range of 800'482'0315 FAX 217·359'6904 818·998·0070 FAX 818·998'4459 products. Including impor- Contact: Mark Decker Contact: Mos<' Jadon Family of high performance intelligent boards Full line of high density memory modules tant recent announcements including single· and dual·channel SCSI up to 128M bytes in a single ca rd slot. Single that open new avenues of host adapters, 80386 SBC, communicationsl and dual ports (iPSB/iLBX), Dynamicand terminal controller, and SBX motherboard . non-volatile CMOS RAM memories . opportunity for engineering • CONCURRENT TECHNOLOGIES • MICROBAR SYSTEMS teams designing for the next 217·356·7004 FAX 217·356·6238 408·720·9300 FAX 408·773·9475 decade, and beyond .• The Contact: Jerry Hoffman Contact: Alex London Full line of high performance 386 and 186 CPU Reduces board development cycles to 12 Multibus Manufacturers boards, analog and digital VO, communica- weeks w hile meeting your application-specific Group (MMG) members who tions, Ethernet, Cheapernet, and 16-channel requirements through our design library based terminal controllers. on 8OX86 or 680XO processors. sponsored this ad invite you • DIGITAL RESEARCH INC. el PLX TECHNOLOGY, INC. to send for their all-new 1990 408·982'0700 FAX 408·982·0715 800·759·3753 FAX 415·960·0479 Multibus 11 Product Data Book. Contact: Director of OEM Sales Contact: Gaylord Galiher Full-featured systems software OEM products Low-cost, high drive current, bus interface It's full of information on their including 186, 286 and 386 FlexOS operating specialists. Programmable and off-the-shelf complete lines of Multibus II systems, Token Ring and TCpnp network soft- interface chips for Multibus II and all other ware, and new XlGEM graphics user interface. high performance buses. boards, systems, software and • HEURIKON CORP. • SIEMENSAG • • bus interface chips. And it's • 800·356·9602 FAX 608·831-4249 • AdvertiSing Dept., 333 State Bridge Road available free to qualified Contact: Jeremy Wright 0 Alpharetta, GA 30201 Range of quality CPU boards and systems. A complete range of CPU, memory and 110 engineers and managers . • The most recent introduction is a 68030-based cards, including local buses as OME, AMS, SBC with on-card Ethernet. SMP, and AT, from the leading European board To request your copy just • INTEL supplier for industrial automation. send your business card to • • THE WOLLONGONG GROUP • 800'548'4725 the MMG. Or call our special D Comprehensive Multibus II solutions: UNIX:t 415·962·7200 FAX 415'969'5547 toll free number today: iRMX based System 520, new i486 CPU, new Contact: Douglas Ambort 80386-based modular 110, and new low cost TCPIIP and NFS protocol su ites on Multibus BOD 44B 9&02. IU.S.andCanada) MPI-based liD. computers running the UNIX System V • MICRO INDUSTRIES Release 3.2 operating system supported on Discover a world of design • the 186/530 and 186/622A. freedom made possible by • 614·895·0404 FAX 614'882·6357 • XYLOGICS, INC. Contact: Susan Lawton the Architectural Discipline of Complete line of MuItibus I and 11 products 617·272·8140 FAX 617-273·5392 Multibus II. For large, complex for industrial control, office automation, tele- Contact: Dave Padley communications, military and aerospace. Full line of very high performance, applications. And small, multichannel peripheral controllers under simple ones. Just about any- development, supporting such interfaces as ESDI, IPI and SCSI. where a PC is not enough .• Legend: • Boards • Systems • Software Bus Interface Silicon PD. Box 6208, Aloha, Oregon 97007 503'6%·7155 "1989 MuniDus MarlJfacturers Group. Multibus. IRMX. iLBXand ISBXare trademarksof Intel Corp. UNIX Isa trademark of AT&T. FIexOS is a trademarkof DIgital Research, Inc. VRTX is a trademar1 body. Quarter-turn screws in the collar and body are tightened to reduce the diameters of the holes and thereby grip the post. A sec- ond post is inserted in the other hole in the body (at a right angle to the first post) and clamped in the same way. To translate and rotate the clamp on a post, a user follows this procedure: • Loosen the quarter-tum screws on the body and collar that secure the clamp as- sembly to the post. Slide the clamp along the post to the desired axial position. Tlght- en the scrfm in the post-clamp collar. • Rotate the clamp on the post to the de- sired angular positicrl. Tighten the scrfm in the post-clamp body. One of the advantages of the nfm clarll> ing assembly is that the loosened body can even be suspended on, and rotated about, the tightened collar. Thus, for example, the user can rotate the body on a vertical post without supporting it from belO'N with a separate collar or by hand to prevent it from failing along the post. This conven- ience is not offered by older clamps. The new collar makes contact with the post uniformly around its Circumference, thus distributing the gripping force evenly. In some older types of collar, in contrast, it is necessary to drive a thumbscrfm direct- ly into contact with the post to secure it, ap- Measuring Diameters of Large Vessels ~J A computerized apparatus produces accurate results quickly. plying a concentrated force on a small area of the post. If excessive torque is ap- plied to these thumbscrews, it is possible to mar or scratch the post if the thumbscrew is made of a harder material than the post, making subsequent readjustments of the clamp at the same spot even more difficult. This oork was done by John Karl Ramsey and Erwin H. Meyn of lewis Research Center. For further information, Circle 115 on the TSP Request Card. Inquiries concerning rights for the com- mercia/ use of this invention should be ad- dressed to the Patent Counsel, Lewis Research Center {see page 16}. Refer to LEW-14862 tracts to follow the wall contour, generating an electrical signal that represents the radius at any instant. The signal is fed ______________________________ through a cable to a computer and printer Marshall Space Flight Center, Alabama An apparatus measures the diameter of a tank or other large cylindrical vessel, with- out a priori knowledge of the exact location of the cylindrical axis. The apparatus pro- duces a plot of the inner circumference, an estimate of the true center of the vessel, data on the radius, the diameter of a best-fit circle, and the negative and positive devia- tions of the radius from the circle at closely spaced points on the circumference. It eliminates the need for time-consuming Radius Cable for Power and error-prone manual measurements. A crossbeam assembly is bolted to the vessel by brackets (see figure). Suspended from the center of the crossbeam assem- bly is a movable radius arm. A servomotor and gear train rotate the arm so that it pivots about an axis at the intersection of the crossbeams. As the arm rotates, an electronic linear gauge at the end of the arm is spring-loaded against the inner wall of the vessel. The gauge extends and re- Crossbeams Servomotor and Gear Train on a cart. The circumferential speed of the meas- uring tip is about 5 in./s (12.7 cm/s). An angle resolver on the shaft that rotates the radius arm generates an electrical Signal that represents the rotational position of the arm. This signal is also fed to the com- puter. The computer thus obtains data on the length of the arm as a function of the angular position of the arm as it sweeps around the vessel. From the data, the com- puter calculates the radii, diameter, true Housing Containing Angle Resolver The Intersection of the Crossbeams need not be positioned exactly at the center of the vessel. The time required to set up the apparatus for measurements is therefore much shorter than It would be for manual measurements of the radii from a precisely determined center. The com- puter processes the data from the automatic measurements to find the center. NASA Tech Briefs, January 1990 53 center, and deviations from true circularity. The computer also controls the operation of the apparatus by turning the power switch on and off to start and stop the measurements. This work was done by James R. OJrrie, Ralph R. Kissel, Charles E. Oliver, Earnest C. Smith, John W Redmon, Sr., Charles C. Wallace, and Charles P. Swanson of Mar· shall Space Aight Center. For further in- formation, Orcle 82 on the TSP Request Card. This invenuon is owned by NASA, and a patent application has been filed. Inquiries Using Ruby Balls as Fiducial Marks concerning nonexclusive or exclusive license for its commercial development should be addressed to the Patent Counsel, Marshall Space Flight Center [see page 16]. Refer to MFS-2828Z ~~A combination of basic and advanced techniques yields a new capability for inspection. Marshall Space Flight Center, Alabama A technique for the measurement of small flaws on the surfaces of bearings in- volves the use of ruby balls as standards of length. Heretofore, styluses with ruby balls 54 Circle Reader Action No. 500 at their tips have been used, but in a tactile method in which probes are moved across suspect areas in attempts to detect de- fects by feeling them. In the new technique, a surface is first inspected with fluorescent penetrant dye to reveal flaws. A ruby ball of known diame- ter is placed near a flaw that has to be measured. The flaw and ball are observed through a magnifying video system that can "freeze" the image. When the scene is illuminated with a fil- tered borescope light, the ruby ball ema- nates a distinct glow that can be seen on the video monitor. Two lines are drawn on the monitor screen to enclose the image of the ball. The distance between the lines is measured in picture elements, and the known diameter of the ball is divided by the distance in elements to obtain the scale length (true distance per picture element) of the image. Then lines are drawn to en- close the flaw, the distance between these lines is measured in picture elements, and this distance is multiplied by the scale length to obtain the size of the flaw. This work was done by Nance M. Painter of Rockwell International Corp. for Mar· shall Space Aight Center. No further documentation is available. MFS-29394 Improved Coupled Fluid/Structural Dynamical Model Calculations of damping or instability are made more accurate. Marshall Space Flight Center, Alabama · AA improved algorithm has been devel- oped for the simulation of coupled motions of fluids and structures. This is a topic of widespread interest because coupling can convert the kinetic energy of a fluid into mechanical vibration and can cause insta- bility in some ranges of flow. AA example of this plienomenon that can be observed in NASA Tech Briefs, January 1990 External Forces Applied to Forces on Structure + Structure + Fluid Forces at Interface Mobility of Structure Impedance of Fluid Velocity at Interface ~ spect to force) and the impedance of the fluid system (the partial derivative of force with respect to velocity), the estimate of ve- locity can be corrected to the value that re- sults in compatible forces and velocity at the interface at the end of the time step. Then using the corrected velocity, the equations of the fluid system can be re- solved for the correct change in the force at the interface. A new value for modal displacement can also be found (for use in the structural-transient block). The Interactions Between the Fluid and the Structure are represented by coupled mathe- matical models. The forces and velocity at the Interface are constrained to be compatible In both models at each time step. The use of this algorithm greatly im- proves the computational stability. Some residual error is caused by the assumption many homes is the vibration of a loosely- mounted water pipe at some faucet set- tings. Simulation requires great care in the treatment of damping (or resonant gains), frequency being a less important consider- ation. The fluid in contact with the structure causes some mass loading of the structure and some reduction of vibrational frequen- cy relative to that of the unloaded struc- ture. It is difficult to couple the mathematical models of the structure and fluid because they involve different types of equations. The nonl inearities of the fluid model usually require numerical solutions in the time de- main, using finite time steps. The usual ap- proach -is to alternate the solution between the fluid and structure and to choose very small time steps. This approach results in a phase shift, which leads to erroneous values of damping, even though errors in frequency are small. A minimum requirement for correct sim- ulation of damping is that the forces and velocities at the interface be compatible in the models of the structure and fluid at each time step. The improved algorithm, which conforms to this requirement, in- volves a fluid-transient model, a structural modal/transient model, and an algebraic impedance/coupling subalgorithm. The velocity of the structure at the end of each time step is computed, based on the initial position, velocity, modal force, and change in modal force during the time step. The change in modal force has two parts, one of which is a function of time and would occur with no change in the velocity at the interface. The second part is the change in force due to a change in the ve- locity at the interface. The interaction between the mathemati- cal models of the fluid and structure are il- lustrated in the figure. Solving the equa- tions of the fluid subsystem with constant velocity, one obtains the forces at the inter- face. These are added to externally-ap- plied structural forces to compute the modal force and obtain an estimate of modal velocity. Using the structural mobili- ty (the partial derivative of velocity with re- NASA Tech Briefs, January 1990 With ,.1il ~ you get. .. ... simultaneous X Windows capabil ity within Microsoft Windows, .. . system responsiveness approaching expensive workstations, ., .graphic communications between MS-DOS and UNIX computers, ... the freedom to switch displays to suit your application, and ... full X11 Release 3 functionality while retaining the use of your desktop 2868 or 3868 PC. Priced at $395 To Order your copy, CALL (714) 978-6201 FAX (714) 939-0746 s-~ Integrated _ ___ Inference =-- 7' = Machines X1 1/AT Is a trademark of Integrated Inlerence Machines. Inc. 1468 E. Katelia Avenue. Anaheim. CA 92805. 286 and 386 are trademarks of Intel Corporation. Microsoft is a trademark of Microsoft Corporation. Circle Reader Action No. 307 that during each time step, the correction to force and velocity is a linear function of time. The errors appear in the solution as errors in the frequency of the system rather than as errors in the damping of the system. This work was done by James R. Fenwick of Rockwell International Corp. for Mar· Predicting Pressure Drop in Porous Materials Methodology to predict flow under Shuttle Orbiter tiles is applicable to other porous and fibrous materials. Langley Research Center, Hampton, Virginia The therrnal-protection system (TPS) of the Space Shuttle Orbiter includes a strain- isolation pad (SIP) between the tiles and the underlying surface. The SIP material is a thin mat made of very small fibers primarily aligned either parallel or normal to the 56 Now you can buy full-size drafting plotters from an industry leader at prices as low as $3,295. Call for our complete guide to plotters, scanners, and graphics digitizers. 1-800-444-3425 512-835-0900 Circle Re.der Action No. 550 HOUSTON INSTRUMENT • OMSOONOfAM.TI!K Floating Point Array Processor • Dramatically increases the dynamic range and peed of de ktop computing with IBM PC. XT. AT and other com- patibles. • Ideal for image processing. neural networks. seismic analy- sis. surface defect detection and vibration analysis. • Saves time wri ting pro- grams. Includes 'Tool Box ' Library of 473 powerful mi- cro-coded functions and pre- wrillen support routine . • Accelerate compute-bound C. Fortran or Pascal programs with a processing rate of 12.5 MF!op perPL1250 ... Runtime software supports up to eight PL 1250s running in parallel within a Single PC providing 100 MFlops perfomlance. • ThePL1250withsoftware ... $2.695. 6~g~ ~ 1247 Tamarisk Lane Boulder City, NV 89005 1·800·888-1119 Circle Reader Action No. 675 shall Space flight Center. For further in- formation, Orele 15 on the TSP Request Card. MFS-29439 structural shell of the orbiter. The flow rate of air through the TPS is a critical parame- ter In the TPS design. On ascent, the flow characteristics of the SIP determine the venting rate of the SIP, which partially de- termines the forces on the thermal tiles. The venting rate is especially important during the transonic portion of the ascent, when the normal shock can rapidly pass over a tile. The large drop in pressure across the shock imposes maximum dependence on the venting capabilities of the TPS. The difference in pressure may tear the tile from the orbiter If the SIP cannot vent quickly enough. During descent, some parts of the Orbit- er experience large local pressure gradi- ents that are constant for significant peri- ods of time. These local gradients produce flow through the SIP. The flow character- istics of the SI P is one element In determin- ing how much hot air will circulate under the TPS. Evaluation of the performance of the SIP requires a knowledge of the pres- sure drop in the fibrous SIP material. Overall , the engineering aspects of flows in porous media are not well under- stood. In critical applications, the designer must rely heavily on experimental data. There has been a program at Langley to provide reliable experimental data on rep- resentative portions of the TPS. The data were used in a mathematical model to pre- dict the internal flows for various TPS con- figurations. However, the data on flow in the SIPwere not adequate for all situations. There were no data on the effects of changes In ambient pressure or of changes in the thickness of the SIP due to vertical movements of the tile . .Accordingly, an experimental program to provide additional data was initiated. The new data includes the effects of both large changes in ambient pressure and limited vertical movement of the tile. The pressure drop through a sample of SIP material at conditions covering most of its operating envelope was measured. The experiment simulated the flow of air beneath a tile ex- posed to a strong surface pressure gradi- ent. The pressure across the SIP was varied from nearOto 1.38X104Pa(2~ia). Testing was at constant levels of ambient density from atmospheric to 13.6 percent of the at- mospheric value. A theory was developed to predict the drop in pressure based on the drag of the individual fibers. A simple correlation method for the data was also developed. The methodology developed will help in predicting the flow characteristics of the many SIP flow geometries in the Shuttle NASA Tech Briefs, January 1990 Orbiter tile system. It will help in predicting venting characteristics of tile assemblies during ascent and the leakage of hot gas under the tiles during descent. The predic- tive philosophy developed should be useful in the study of the mechanics of flows through fibrous and porous media, and the procedures should be applicable to purged fiberglass insulation, dialysis filters, and other fibrous and porous media. This work was done by Pierce L Lawing of Langley Research Center. For further information, Orc/e 51 on the TSP Request Card. LAR-14105 Determining Spatial Coordinates by Laser Ranging Three range-measuring lasers arranged in a triangle measure the location of a point. NASA's Jet Propulsion Laboratory, Pasadena, California A proposed method for the determina- tion of the coordinates of an object uses three laser rangefinders arranged in a right angle so that they define a coordinate sys- tern. A set of three measurements of the distances (ranges) of a retrorefiector on the object from the three rangefinders pro- vides sufficient information to calculate the coordinates of the retroreflector in the c0- ordinate system defined by the rangefind- ers. If at least three noncoilinear retrore- flectors are attached to the object, the orientation of the object can also be deter- mined. Potential applications include the observation and control of large struc- tures, robotics, and machine vision. The calculation of the coordinates from the ranges is based on the law of cosines from trigonometry and the Pythagorean theorem. Using the variables defined in the figure, the angle a x between the X-axis and the measured range vector R a from the ori- gin to the object is given by ax = cos-1[(R~+a2-R~)/2aRa1 The X-coordinate of the retroreflector is given by x = Ra cos(ax) Similarly, the angle ay between the Y-axis and range vector Ra IS given by ay = cos-1[(R~+c2-R~/2cRa] The Y-coordinate of the retrorefiector is given by y = Ra cos(ay) The Z-coordinate of the retroreflector is given by z = (R~-x2_y2)V. If the object carries three or more suita- bly placed retroreflectors, the orientation of the object can also be determined by measuring the coordinates of each of the retroreflectors in the same manner. For ac- curate results, the distances between the retroreflectors must be large compared to the range resolution of the rangefinders. Furthermore, care must be taken that the various range measurements are correct- ly assigned to the various retroreflectors. This work was done by Larry L. Schumacher of Caltech for NASA's Jet Propulsion Laboratory. For further infor- mation, Orele 5 on the TSP Request Card. In accordance with Public Law 9&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 Numerical Algorithms Group NAG Fortran Library products enable you to spend your time and talents on genuine problem solving, not software development 200 experts, recognized worldwide as the leaders in their fields, create the solutions in the NAG Library_ The accuracy, perfor- mance, and total capabilities of NAG software are unmatched in the industry. Take advantage of NAG's expertise in any of these fine products: NAG FORTRAN LffiRARY More than 700 user-level routines covering the principal areas of mathematics and statistics. Available on over 90 different computers from PC's to supercomputers. NAG GRAPHICAL SUPPLEMENT A convenient and versatile means for display- ing numerical results generated by the Library. A facility not available with other libraries. NAG ONLINE SUPPLEMENT An interactive query system enabling the user to make maximum use of the NAG Library. The Online system provides hints on choice of routines, syntax assistance, and other forms of help. An interactive CASE tool for vectorizing and parallelizing Fortran programs. Attain perfor- mance improvements beyond what optimizing compilers may provide. Ideal for "rejuvenating" older applications. NAG Ada Library The first commercially available math library designed and written completely in Ada. Shor- tens the development cycle for embedded math operations in Ada programs. GENSTAT and GLIM Interactive statistical analysis systems used for data exploration, linear modelling, time series analysis ... useful applications in statistical qual- ity control and product survival analYSis. THE NAG PRODUCT liNE OFFERS NUMERICAL AND GRAPIDCAL ALGORITHMS FOR MANY SCIENTIFIC AND ENGINEERING APPLICATIONS I CLUDING: • SIGNAL PROCESSING • COMPUTATIONAL CHEMISTRY • OPERA TIO S RESEARCH • ECONOMETRIC MODELS • APPLICATIONS DEVELOPMENT • STATISTICAL ANALYSIS NUMERICAL ALGORITHMS GROUP 1400 Opus Place, Suite 200 Downers Grove, IL 60515-5702 (708) 971 -2337 FAX: (708) .971-2706 NASA Tech Briefs, January 1990 Circle Reader Action No_ 377 . 57 • Has no moving pa1s, bearings orspri'lgs • Withstands more than 10,000 Gshock • Operational 40 milseconds after power on • Infinite 'resolution, no hysteresis New miniaturized series of rate sensors weigh less than 37 grams and when used with an electronics support card can provide an output voltage that linearly represents angular velocities up to 5000° per second are now available for space- saving applications. Two- or three- axis sensor packages can be provided. 58 CALL OR WRITE FOR SUMMARY CATALOG Humphrey, Inc. 9212 Balboa Ave., Dept. NTBl90 San Diego, California 92123 U.S.A. Phone: (619) 565·6631 TWX: (910) 335-2001 FAX: (619) 565·6873 Ine. Circle Reader Action No. 626 Retroreflector --::\ J-~~---"Y X The Spatial Coordinates of a retroreflector can be determined from a set of three range measurements taken simultaneously by three laser rangefinders. Director of Patents and Ucensing Mail Stop 305-6 California Institute of Technology 1201 East California Boulevard Books and Reports These reports, studies, handbooks are available from NASA as Technical Support Packages (TSP's) when a Re- quest Card number is cited; otherwise they are available from the National Technical Information Service. More About Multiple- Boundary-Condition Testing Measured shapes of vibrational modes are used to update mathematical models. A report extends the discussion of the multiple-boundary-condition vibrational test- ing technique described in a recent issue of NASA Tech Briefs. As its name implies, this technique involves the vibrational testing of a complicated structure under various combinations of boundary condi· tions, each of which yields eXPerimental data on a different part or parts of the mathematical model of the structure. With proper choices of the multiple boundary conditions, the technique enables the ex- perimental validation of the structural mathematical model for structures that can be ground tested by current "stat!X>f- the-art" techniques due to the influence of the terrestrial environment, namely air and gravity. In the previous literature on multiple· boundary-condition vibrational testing, only Pasadena, CA 91125 Refer to NPO-17436, volume and number of this NASA Tech Briefs issue, and the page number. the eigenvalues (in effect, the frequencies of the vibrational modes) have been used in the correlation and update of the mathe- matical model. In this report, the emphasis is on further refinement of the mathemati- cal model by use of the differences be- tween the measured eigenvectors (I.e., the displacements of various places on the structure in the vibrational modes) and the eigenvectors predicted by the model that Is to be so refined. The structure is represented by a finite- element mathematical model of mass ma- trix M and stiffness matrix K. The vibration· al modes (eigenmodes of the model) are characterized by the eigenvalue matrix L and the eigenvector matrix P. From the basic matrix.vector equations of motion and the orthogonality of Pwith respect to K and M, the authors derive the following two equations for the relationships among small changes in K, L, M, and P, ignoring second· and higher-order differential terms: dL = pT(dK)P - LpT(dM)P and (K - LM)dP = L(dM)P- [LpT(dM)P]MP - (dK)P + [pT(dK)P]MP where T denotes the transpose. The inter- mediate objective is then to solve these equations simultaneously to obtain dK and dM; that is, to update the parameters K and M of the mathematical model on the basis of the difference dP between the meas· NASA Tech Briefs, January 1990 ured and assumed eigenvectors. The ultimate objective is to update the estimates of the physical parameters of the structure (areas, moments of inertia, and the like), rather than the elements of the mathematical model, which are more numerous. For a model of N degrees of freedom, these matrix equations provide N + 1 equations for each eigenvector and corresponding eigenvalue. Thus, the sys- tem is overdetermined, resulting in multiple estimates of the desired parameters. This overdetermination provides the leeway for the selection of boundary conditions. The authors present a numerical exam- ple in which multiple-boundary-condition test data are used to make the approxi- mate parameters of a mathematical model of a flexible beam of four different cross sections converge toward the correct val- ues. The effects of several different bound- ary conditions are illustrated. Issues for future research include the choice of prop- er subsets of information for the estimation of the parameters of interest and the selec- tion of the boundary conditions that will yield the correct data. This work was done by Chin-Po Kuo and Ben K. Wada of Caltech for NASA's Jet Propulsion Laboratory. To obtain a copy of the report, "Multiple f30undary Condition Test (MBCT): Identification With Mode Shapes," Circle 16 on the TSP Request Card. NPO-17574 Computational Fluid Dynamics for Helicopters Powerful computer codes are undergoing development. A report reviews the develop'nent of c0m- putational fluid dynamics (CFD) for the pre- diction of airflow around the rotary wings of helicopters. CFD computer codes, devel- oped during the past 15 years, are now widely applied in industry. With them, it is roN practical to make complete rotor com- putations, including transonic unsteady and three-dimensional effects, without resorting to empiricism and extensive li- braries of data. There is now no lack of codes, the report notes. The smallmpresslon." 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 tee by calling (BOO) 3364700. LAR-13814 the deveIq:rnent of a thorough understanc} ing of the interrelationships among various welding parameters. This involved experi- ments to acquire data on the following: • The effects of the rate of flow of shielding gas on the voltage, plasma pressure, and heat imparted to the wor1

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