Computer program for the design of toroidal transformers

Program relieves designer of most of the computational details, while he maintains control over most engineering decisions. Number of specifications that must be supplied by user allows for considerable flexibility and for exercise of engineering judgment. Speed of program makes it possible to run many cases, economically determining effect of various parameter changes

Design of a multistage depressed collector for the F-16 radar dual mode transmitter tube

The design of a multistage depressed collector (MDC) for use with the F-16 radar dual mode transmitter tube is described. The methods employed and the rationale on which the design is based are presented

System efficiency of a microwave power tube with a multistage depressed collector

The efficiencies of a microwave power tube with a multistage depressed collector and of the power supply driving the tube are computed. An analytical expression for the collector efficiency, which includes the effect of secondary emission and the radial component of velocity, is derived for a hypothetical current probability distribution function. In addition, collector efficiency is calculated with the aid of a digital computer for a specific current distribution. The efficiency of the power supply required to operate the tube in a space environment is estimated by using a simple parallel inverter system

Toroidal transformer design program with application to inverter circuitry

Estimates of temperature, weight, efficiency, regulation, and final dimensions are included in the output of the computer program for the design of transformers for use in the basic parallel inverter. The program, written in FORTRAN 4, selects a tape wound toroidal magnetic core and, taking temperature, materials, core geometry, skin depth, and ohmic losses into account, chooses the appropriate wire sizes and number of turns for the center tapped primary and single secondary coils. Using the program, 2- and 4-kilovolt-ampere transformers are designed for frequencies from 200 to 3200 Hz and the efficiency of a basic transistor inverter is estimated

Three-axis electron-beam test facility

An electron beam test facility, which consists of a precision multidimensional manipulator built into an ultra-high-vacuum bell jar, was designed, fabricated, and operated at Lewis Research Center. The position within the bell jar of a Faraday cup which samples current in the electron beam under test, is controlled by the manipulator. Three orthogonal axes of motion are controlled by stepping motors driven by digital indexers, and the positions are displayed on electronic totalizers. In the transverse directions, the limits of travel are approximately + or - 2.5 cm from the center with a precision of 2.54 micron (0.0001 in.); in the axial direction, approximately 15.0 cm of travel are permitted with an accuracy of 12.7 micron (0.0005 in.). In addition, two manually operated motions are provided, the pitch and yaw of the Faraday cup with respect to the electron beam can be adjusted to within a few degrees. The current is sensed by pulse transformers and the data are processed by a dual channel box car averager with a digital output. The beam tester can be operated manually or it can be programmed for automated operation. In the automated mode, the beam tester is controlled by a microcomputer (installed at the test site) which communicates with a minicomputer at the central computing facility. The data are recorded and later processed by computer to obtain the desired graphical presentations

Reports of injury risks and reasons for choice of sleep environments for infants and toddlers

OBJECTIVE: Compare mothers\u27 reports of injuries for infants and toddlers sleeping with crib-bumpers/mesh-liners/no-barriers and reasons for these sleep environment choices. METHODS: A cross-sectional survey of mothers subscribing to a parenting magazine and using crib bumpers (n = 224), mesh liners (n = 262), and no barriers (n = 842). Analyses of four possible injuries (face-covered, climb-out/fall, slat-entrapment, hit-head) including multivariate logistic regression adjusted for missing data/demographics and Chi squared analyses of reasons for mothers\u27 choices. RESULTS: Maternal reports of finding infants/toddlers with face covered had 3.5 times higher adjusted odds (aOR) for crib bumper versus mesh liner use. Breathing difficulties and wedgings were reported for infants/toddlers using crib bumpers but not mesh liners. Climb-outs/falls showed no significant difference in aORs for crib bumpers versus no-barriers and mesh liners versus no barriers. Reports of slat-entrapment were less likely for mothers using crib bumpers and mesh liners than using no barrier (aOR = .28 and .32). Reports of hit-heads were less likely for crib bumpers vs no barrier (aOR = .38) with no significant difference between mesh liners versus no barrier use. Mothers using crib bumpers and mesh liners felt their choice prevented slat-entrapment (89%, 91%); 93.5% of crib bumper users felt their choice prevented hit-heads. Significantly more mesh liner than crib bumper users chose them because There is no suffocation risk (64.1% vs. 40.6%), while 83.6% of no-barrier users chose them because I was concerned about suffocation risk. CONCLUSIONS FOR PRACTICE: Mothers appeared to be more concerned about preventing minor risks than suffocation. Understanding reasons for mothers\u27 use of barriers/no-barriers is important in tailoring counseling for mothers with infants/toddlers

Preliminary Canopy Removal Experiments in Algal Dominated Communities Low on the Shore and in the Shallow Subtidal on the Isle of Man

The algal dominated communities immediately above and below the low-water spring level on a moderately exposed Manx shore were investigated by canopy removal experiments. Fucus serratus, Laminaria digitata and L. hyperborea were removed. Competition was shown to be important in determining the zonation of L. digitata and the distribution along the wave exposure gradient of other species such as Alaria esculenta, Desmarestia aculeata and D. viridis, and L. saccharina. Many species of algal epiphytes were early colonizers of canopy removal areas suggesting that competition from canopy algae usually restricts them to an epiphytic habit. The results indicate that interactions between macrophytes are much more important than grazing in structuring these communities

Powder Mountain Bike Resort Master Plan

In the last decade ski resorts worldwide have developed mountain bike specific recreational facilities in an effort to increase summer revenues. Their success has been mixed, with some becoming quite profitable, but others closing summer operations after only a few low revenue years. With minimal information regarding bike park design currently available, the planning and design of these facilities remains largely a grassroots effort. This thesis project develops a methodology that approaches the creation of mountain bike resorts on ski mountain terrain based on landscape architectural best practices, sustainable trail construction techniques, and site-specific requirements. For this project, the terrain of Powder Mountain, a privately owned ski resort above Eden, UT, was selected due to the management’s interest in the study’s relevance to expanding recreational summer offerings, and the proximity to Utah State University. This research analyzes the Powder Mountain landscape and infrastructure to develop a Master plan, outlining trail corridors, feature placement, and terrain suitability for future trail development. The basis for these design decisions were analyses from site visits, case studies, and GIS analyses. In addition, a worldwide survey of mountain bike park user experiences was conducted to further understanding of the elements of an ideal mountain bike resort. Throughout the process, these findings were augmented by consultation with professional mountain bike park designers and refined through an iterative design process to create a Master plan based on landscape architectural best practices that will guide the development of summer mountain bike recreation facilities on Powder Mountain

Experimental verification of the multistage depressed collector design procedure for a high-perveance, helix-type, traveling-wave tube

The validity of a computational procedure for the design of multistage depressed collectors (MDC's) is demonstrated for a traveling wave tube (TWT) with a perveance of .00000123. The MDC is used with spent-beam refocusing to improve substantially the efficiency of the TWT. Reports on this subject have verified, under a variety of operating conditions, the MDC design procedure for TWT's with lower perveance. The design procedure is based on two computer programs that create a mathematical model of the electric and magnetic fields of the TWT refocuser MDC system and its electron beam. The two principal outputs of the analysis are a description of the radiofrequency (RF) performance of the TWT and the trajectories of representatives groups of charges from the input of the TWT to their points of interception on the MDC electrodes