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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Analyzing Millimeter-Wave Mixers

Series of computer programs developed to serve as tool in understanding behavior and subsequent optimization of millimeter-wave mixers. Major program in collection is general mixer-analysis program that performs complete large- and small-signal analysis of mixer with known diode and mount characteristics. Primary objective behind programs to gain better understanding of factors that affect performance of room-temperature, single-ended Schottky-diode mixers operating above 100 GHz.

Siegel, P.↗
NASA NTRS1967

A modal combination computer program for dynamic analysis of structures

Computer program determines the response of a composite linear structure to sinusoidal base motion of a restrained structure or sinusoidal forces of a free structure. This program is applied to problems of testing practices and closed-loop stability of autopilot controlled space vehicles. It is written for the IBM 7094 in FORTRAN 4 language.

Bamford, R. M.↗
NASA NTRS1981

Deep anistropic shell program for tire analysis

A finite element program was constructed to model the mechanical response of a tire, treated as a deep anisotropic shell, to specified static loads. The program is based on a Sanders Budiansky type shell theory with the effects of transverse shear deformation and bending-extensional coupling included. A displacement formulation is used together with a total Lagrangian description of the deformation. Sixteen-node quadrilateral elements with bicubic shape functions are employed. The Noor basis reduction technique and various type of symmetry considerations serve to improve the computational efficiency.

Andersen, C. M.↗
NASA NTRS1982

Track train dynamics analysis and test program: Methodology development for the derailment safety analysis of six-axle locomotives

The operational safety of six axle locomotives is analyzed. A locomotive model with corresponding data on suspension characteristics, a method of track defect characterization, and a method of characterizing operational safety are used. A user oriented software package was developed as part of the methodology and was used to study the effect (on operational safety) of various locomotive parameters and operational conditions such as speed, tractive effort, and track curvature. The operational safety of three different locomotive designs was investigated.

Marcotte, P. P.↗
NASA NTRS1981

The Aerospace Vehicle Interactive Design system

The aerospace vehicle interactive design (AVID) is a computer aided design that was developed for the conceptual and preliminary design of aerospace vehicles. The AVID system evolved from the application of several design approaches in an advanced concepts environment in which both mission requirements and vehicle configurations are continually changing. The basic AVID software facilitates the integration of independent analysis programs into a design system where the programs can be executed individually for analysis or executed in groups for design iterations and parametric studies. Programs integrated into an AVID system for launch vehicle design include geometry, aerodynamics, propulsion, flight performance, mass properties, and economics.

Wilhite, A. W.↗
NASA NTRS1981

The Aerospace Vehicle Interactive Design system

The Aerospace Vehicle Interactive Design (AVID) is a computer-aided design system that was developed for the conceptual and preliminary design of aerospace vehicles. The AVID system evolved from the application of several design approaches in an advanced concepts environment in which both mission requirements and vehicle configurations are continually changing. The basic AVID software facilitates the integration of independent analysis programs into a design system where the programs can be executed individually for analysis or executed in groups for design iterations and parametric studies. Programs that have been integrated into an AVID system for launch vehicle design include geometry, aerodynamics, propulsion, flight performance, mass properties, and economics.

Wilhite, A. W.↗
NASA NTRS1973

NASTRAN postprocessor program for transient response to input accelerations

The description of a transient analysis program for computing structural responses to input base accelerations is presented. A hybrid modal formulation is used and a procedure is demonstrated for generating and writing all modal input data on user tapes via NASTRAN. Use of several new Level 15 modules is illustrated along with a problem associated with reading the postprocessor program input from a user tape. An example application of the program is presented for the analysis of a spacecraft subjected to accelerations initiated by thrust transients. Experience with the program has indicated it to be very efficient and economical because of its simplicity and small central memory storage requirements.

Wingate, R. T.↗
NASA NTRS1972

DORCA 2 computer program. Volume 1: User's guide

The Dynamic Operational Requirements and Cost Analysis Program (DORCA 2) is described. The computer program provides a top level analysis tool for NASA and relies on a man machine interaction to optimize results based on external criteria. The computer program relies heavily on outside sources to provide cost information and vehicle parameters. Given data describing mission, vehicles, payloads, containers, space facilities, schedules, cost values, and costing procedures, the program computes flight schedules, cargo manifests, vehicle fleet requirements, acquisition schedules, and cost summaries. The program is designed to consider earth orbit, lunar, interplanetary, and automated satellite missions.

Wray, S. T., Jr.↗
NASA NTRS1983

Ad Hoc modeling, expert problem solving, and R&T program evaluation

A simplified cost and time (SCAT) analysis program utilizing personal-computer technology is presented and demonstrated in the case of the NASA-Goddard end-to-end data system. The difficulties encountered in implementing complex program-selection and evaluation models in the research and technology field are outlined. The prototype SCAT system described here is designed to allow user-friendly ad hoc modeling in real time and at low cost. A worksheet constructed on the computer screen displays the critical parameters and shows how each is affected when one is altered experimentally. In the NASA case, satellite data-output and control requirements, ground-facility data-handling capabilities, and project priorities are intricately interrelated. Scenario studies of the effects of spacecraft phaseout or new spacecraft on throughput and delay parameters are shown. The use of a network of personal computers for higher-level coordination of decision-making processes is suggested, as a complement or alternative to complex large-scale modeling.

Silverman, B. G.↗
NASA NTRS1991

Characterization of slow and fast phase nystagmus

A current literature review of the analog and digital process of vestibular and optical kinetic nystagmus reveals little agreement in the methods used by various labs. The strategies for detection of saccade (fast phase velocity component of nystagmus) vary between labs, and most of the process have not been evaluated and validated with a standard database. A survey was made of major vestibular labs in the U.S. that perform computer analyses of vestibular and optokinetic reflexes to stimuli, and a baseline was established from which to standardize data acquisition and analysis programs. The concept of an Error Index was employed as the criterium for evaluating the performance of the vestibular analysis software programs. The performance criterium is based on the detection of saccades and is the average of the percentages of missed detections and false detections. Evaluation of the programs produced results for lateral gaze with saccadic amplitude of one, two, three, five, and ten degrees with various signal-to-noise ratios. In addition, results were obtained for sinusoidal pursuit of 0.05, 0.10, and 0.50 Hz with saccades from one to ten degrees at various signal-to-noise ratios. Selection of the best program was made from the performance in the lateral gaze with three degrees of saccadic amplitude and in the 0.10 Hz sinusoid with three degrees of saccadic amplitude.

Lessard, Charles S.↗
NASA NTRS1990

Data quality analysis at the National Transonic Facility

The data quality analysis program that was developed at Langley Research Center's National Transonic Facility is described. The program provides a computer driven systematic analysis of data taken during calibrations of the high speed digital data acquisition system. Five distinct checks that are performed on the calibration data are outlined. The five checks are for non-linearity, noise, short term drift, long term drift, and the proper functioning of the calibrator. The program has established a standard set of evaluation guidelines.

Stewart, Pamela N.↗
NASA NTRS1984

Conceptual design for scaled truss antenna flight experiment

The conceptual design for a scaled truss antenna structures experiment program (STASEP) is presented. The hardware analysis of the scaled truss antenna structure (STAS) was performed by interactive design and evaluation of advanced spacecraft (IDEAS) computer aided, interactive, design and analysis program. Four STAS's were designed to be launched by the Shuttle, tested by using the space technology experiments platform (STEP) and space transportation system (STS), and then free flown in short lifetime orbits. Data were gathered on deployment, structural characteristics, geometric accuracies, thermal performance, and drag and lifetime as an orbiting spacecraft. Structural and thermal properties were determined for the STAS, including mass properties, thermal loading, structural natural frequencies, and mode shapes. The necessary analysis, scaling, and ground testing are discussed.

Lee, W. H.↗
NASA NTRS1972

Computer program for the transient analysis of radioisotope thermoelectric generators.

A computer program is described which represents a comprehensive analytical tool providing the capability for predicting the output power and temperature profile of an arbitrary radioisotope thermoelectric generator (RTG) design in the presence of time-dependent operating conditions. The approach taken involves the merging of three existing computer programs - namely, an RTG weight optimization design program, a thermoelectric analysis program, and a nodal heat-transfer computer program. A total of seven transient conditions are included in the computer program as the principal transients affecting long- and short-term performance characteristics of RTGs. This computer program is unique in that it designs an optimum RTG, generates a thermal model or analog and performs heat-transfer analysis of the RTG under user-specified transient conditions.

Eggers, P. E.↗
NASA NTRS1967

Master control data handling program uses automatic data input

General purpose digital computer program is applicable for use with analysis programs that require basic data and calculated parameters as input. It is designed to automate input data preparation for flight control computer programs, but it is general enough to permit application in other areas.

Alliston, W.↗
NASA NTRS1974

A Study of the Effect of Adhesive and Matrix Stiffnesses on the Axial, Normal, and Shear Stress Distributions of a Boron-epoxy Reinforced Composite Joint

The mechanical properties of a symmetrical, eight-step, titanium-boron-epoxy joint are discussed. A study of the effect of adhesive and matrix stiffnesses on the axial, normal, and shear stress distributions was made using the finite element method. The NASA Structural Analysis Program (NASTRAN) was used for the analysis. The elastic modulus of the adhesive was varied from 345 MPa to 3100 MPa with the nominal value of 1030 MPa as a standard. The nominal values were used to analyze the stability of the joint. The elastic moduli were varied to determine their effect on the stresses in the joint.

Howell, W. E.↗