Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “input data”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Rain scavenging of solid rocket exhaust clouds

An explicit model for cloud microphysics was developed for application to the problem of co-condensation/vaporization of HCl and H2O in the presence of Al2O3 particulate nuclei. Validity of the explicit model relative to the implicit model, which has been customarily applied to atmospheric cloud studies, was demonstrated by parallel computations of H2O condensation upon (NH4)2 SO4 nuclei. A mesoscale predictive model designed to account for the impact of wet processes on atmospheric dynamics is also under development. Input data specifying the equilibrium state of HC1 and H2O vapors in contact with aqueous HC1 solutions were found to be limited, particularly in respect to temperature range.

Dingle, A. N.↗
NASA NTRS1978

Conceptual design for spacelab pool boiling experiment

A pool boiling heat transfer experiment to be incorporated with a larger two-phase flow experiment on Spacelab was designed to confirm (or alter) the results of earth-normal gravity experiments which indicate that the hydrodynamic peak and minimum pool boiling heat fluxes vanish at very low gravity. Twelve small sealed test cells containing water, methanol or Freon 113 and cylindrical heaters of various sizes are to be built. Each cell will be subjected to one or more 45 sec tests in which the surface heat flux on the heaters is increased linearly until the surface temperature reaches a limiting value of 500 C. The entire boiling process will be photographed in slow-motion. Boiling curves will be constructed from thermocouple and electric input data, for comparison with the motion picture records. The conduct of the experiment will require no more than a few hours of operator time.

Lienhard, J. H.↗
NASA NTRS1978

Paneling techniques for use with the VORLAX computer program

A method is presented for determining the geometric input data required by the VORLAX computer program in order to accurately model an aircraft configuration. Techniques are described for modeling each of the major components of a configuration and for joining these individual components into a complete configuration. The effects of trailing vortex filaments and methods of avoiding their intersection with downstream panels are also discussed. The methods presented here are applicable to most conventional aircraft configurations.

Martin, G. L.↗
NASA NTRS1978

User's Guide for a Modular Flutter Analysis Software System (Fast Version 1.0)

The use and operation of a group of computer programs to perform a flutter analysis of a single planar wing are described. This system of programs is called FAST for Flutter Analysis System, and consists of five programs. Each program performs certain portions of a flutter analysis and can be run sequentially as a job step or individually. FAST uses natural vibration modes as input data and performs a conventional V-g type of solution. The unsteady aerodynamics programs in FAST are based on the subsonic kernel function lifting-surface theory although other aerodynamic programs can be used. Application of the programs is illustrated by a sample case of a complete flutter calculation that exercises each program.

Desmarais, R. N.↗
NASA NTRS1978

A wide bandwidth CCD buffer memory system

A prototype system was implemented to demonstrate that CCD's can be applied advantageously to the problem of low power digital storage and particularly to the problem of interfacing widely varying data rates. CCD shift register memories (8K bit) were used to construct a feasibility model 128 K-bit buffer memory system. Serial data that can have rates between 150 kHz and 4.0 MHz can be stored in 4K-bit, randomly-accessible memory blocks. Peak power dissipation during a data transfer is less than 7 W, while idle power is approximately 5.4 W. The system features automatic data input synchronization with the recirculating CCD memory block start address. System expansion to accommodate parallel inputs or a greater number of memory blocks can be performed in a modular fashion. Since the control logic does not increase proportionally to increase in memory capacity, the power requirements per bit of storage can be reduced significantly in a larger system.

Siemens, K.↗
NASA NTRS1978

JPL Energy Consumption Program (ECP) documentation: A computer model simulating heating, cooling and energy loads in buildings

The engineering manual provides a complete companion documentation about the structure of the main program and subroutines, the preparation of input data, the interpretation of output results, access and use of the program, and the detailed description of all the analytic, logical expressions and flow charts used in computations and program structure. A numerical example is provided and solved completely to show the sequence of computations followed. The program is carefully structured to reduce both user's time and costs without sacrificing accuracy. The user would expect a cost of CPU time of approximately $5.00 per building zone excluding printing costs. The accuracy, on the other hand, measured by deviation of simulated consumption from watt-hour meter readings, was found by many simulation tests not to exceed + or - 10 percent margin.

Lansing, F. L.↗
NASA NTRS1978

An improved computational procedure for determining helicopter rotor blade natural modes

An existing computer program, used for predicting the natural frequencies and mode shapes of helicopter rotor blades, was refined to improve program accuracy and versatility. The program is based on the Holzer-Myklestad approach adapted for rotating beams. Coupled vertical (out-of-plane), horizontal (in-plane), and torsional mode characteristics were determined for a variety of hub and blade configurations. The resulting program is documented by presenting the recursion equations and techniques for determining natural frequencies and mode shapes, input data requirements, and descriptions of various program outputs. The accuracy of the program is demonstrated by comparing computed results with exact solutions to classical problems and experimental data.

Weller, W. H.↗
NASA NTRS1977

Spectral interpolation - Zero fill or convolution

Zero fill, or augmentation by zeros, is a method used in conjunction with fast Fourier transforms to obtain spectral spacing at intervals closer than obtainable from the original input data set. In the present paper, an interpolation technique (interpolation by repetitive convolution) is proposed which yields values accurate enough for plotting purposes and which lie within the limits of calibration accuracies. The technique is shown to operate faster than zero fill, since fewer operations are required. The major advantages of interpolation by repetitive convolution are that efficient use of memory is possible (thus avoiding the difficulties encountered in decimation in time FFTs) and that is is easy to implement.

Forman, M. L.↗
NASA NTRS1977

Applications of pilot scanning behavior to integrated display research

The oculometer is an electrooptical device designed to measure pilot scanning behavior during instrument approaches and landing operations. An overview of some results from a simulation study is presented to illustrate how information from the oculometer installed in a visual motion simulator, combined with measures of performance and control input data, can provide insight into the behavior and tactics of individual pilots during instrument approaches. Differences in measured behavior of the pilot subjects are pointed out; these differences become apparent in the way the pilots distribute their visual attention, in the amount of control activity, and in selected performance measures. Some of these measured differences have diagnostic implications, suggesting the use of the oculometer along with performance measures as a pilot training tool.

Waller, M. C.↗
NASA NTRS1978

On the calculation of squaring loss in Costas loops with arbitrary arm filters

Specific numerical results for the squaring loss in Costas loop tracking are discussed for cases when the input data were biphase-L, and the Costas loop arm filters were of the n-pole Butterworth type. It is pointed out that a simple scientific calculator may be used for the computations, provided the transfer function of the arm filter has simple poles. The technique can also be used to compute the squaring loss in other modulation forms, such as unbalanced quadriphase-shift-keying (QPSK).

Simon, M. K.↗
NASA NTRS1977

Computer assistance for the structural chemist

A description is presented of the approaches used to modify the molecular structure generator program, CONGEN. The CONGEN program for constructing structures under constraints has been discussed by Carhart et al. (1975). The modifications reported are to lead to a more efficient structure generation on the basis of a translation of structural data input to the program. From an algorithmic standpoint, CONGEN is successful if it can, in a reasonable amount of time and without exhausting storage resources, produce a list of candidate structures satisfying the chemist's constraints. However, this list is often quite large, and it remains for the chemist to discriminate among the candidates, eventually reducing the possibilities to just one structure. Ways are studied for providing computer assistance in examining and further constraining lists of structural candidates.

Carhart, R. E.↗
NASA NTRS1979

Dynamic simulation and stability analysis

Dynamic Interaction Simulation of Controls and Structure (DISCOS) program was developed for dynamic simulation and stability analysis of passive and actively controlled spacecraft. Program is written in FORTRAN IV for batch execution and requires access to finite-element structures program as NASTRAN for flexible-body input data.

Frisch, H. P.↗
NASA NTRS1980

Coupled-cavity traveling-wave tubes

Computer program is developed for analysis of coupled cavity traveling waves tubes (TWT's) which are used in variety of radar and communications applications. Programmers can simulate tubes of arbitrary complexity such as input and output couplers and other features peculiar to one or few cavities which may be modeled by correct choices of input data.

Connolly, D. J.↗
NASA NTRS1978

A vortex model for transport in the polar stratosphere

A semi-empirical model based on a Gaussian vorticity distribution was developed for determining eddy diffusivity and wind transport distributions in the polar stratosphere. The model uses as input data pressure surface heights measured at periods of the year when the stratospheric polar vortex exhibits nearly circular patterns around the pole. The components of the polar wind velocities that result from a Prandtl eddy viscosity distribution are found to be in general agreement with those obtained by other investigators.

Eberstein, I. J.↗
NASA NTRS1978

Optimum dry-cooling sub-systems for a solar air conditioner

Dry-cooling sub-systems for residential solar powered Rankine compression air conditioners were economically optimized and compared with the cost of a wet cooling tower. Results in terms of yearly incremental busbar cost due to the use of dry-cooling were presented for Philadelphia and Miami. With input data corresponding to local weather, energy rate and capital costs, condenser surface designs and performance, the computerized optimization program yields design specifications of the sub-system which has the lowest annual incremental cost.

Chen, J. L. S.↗
NASA NTRS1978

Analytical studies of separated vortex flow on highly swept wings

A subsonic potential flow mathematical model of the flow past slender aerodynamic surfaces with sharp edges and separated vortex flow is reported. Comparisons with experimental data are presented for overall forces and pressure distributions for a series of thin, low aspect ratio wings, including both flat and conically cambered ones. A discussion is presented of the limitations of the current theory, and some suggestions are made as to how the theory might be improved. Details of program data input modifications for three-dimensional geometry are described in an appendix.

Kuhlman, J. M.↗
NASA NTRS1978

Results of piloted simulator studies of fighter aircraft at high angles of attack

The experience gained at the NASA Langley Research Center during the application of simulator techniques to high angle of attack flight conditions for several current fighters is discussed. The discussion includes (1) the simulator hardware, (2) requirements for static and dynamic aerodynamic data inputs, (3) evaluation procedures, (4) correlation with flight, and (5) the effects of dynamic stability parameters. Results obtained with the simulator technique have correlated well with flight test experience, resulting in early identification of potential problems, identification of critical flight conditions, and solutions to various deficiencies in stability and control characteristics. Dynamic stability parameters, results indicate that certain parameters can have a large influence on the flying qualities and tactical effectiveness of fighters at high angles of attack.

Chambers, J. R.↗
NASA NTRS1977

Development of a moderately sized finite element program for nonlinear structural analysis

AGGIE 1 is a computer program for predicting the linear and nonlinear, static and dynamic structural response of two- and three-dimensional continuum solids. The program is based on isoparametric finite elements and allows for 2-D plane stress, plane strain, and axisymmetric analyses and general 3-D analyses. Large strain kinematics is based on the total Lagrangian formulation. Materially nonlinear models include several elastic-plastic work-hardening models as well as an incompressible Mooney-Rivlin model. Included in this report is a brief description of the theoretical bases of the program, the material models used, the element library and the overall program organization. Instructions for data input preparation are given in detail. Several sample problems are given along with the required program input and program generated solutions.

Haisler, W. E.↗