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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

The Advanced On-board Processor (AOP)

The goal of the Advanced On-Board Processor (AOP) development program is to design, build, and flight qualify a highly reliable, moderately priced, digital computer for application on a variety of spacecraft. Included in this development program is the preparation of a complete support software package which consists of an assembler, simulator, loader, system diagnostic, operational executive, and many useful subroutines. The AOP hardware/software system is an extension of the On-Board Processor (OBP) which was developed for general purpose use on earth orbiting spacecraft with its initial application being on-board the fourth Orbiting Astronomical Observatory (OAO-C). Although the OBP possesses the significant features that are required for space application, however, when operating at 100% duty cycle the OBP is too power-consuming for use on many smaller spacecraft. Computer volume will be minimized by implementing the processor and input/output portions of the machine with large scale integrated circuits. Power consumption will be reduced through the use of plated wire and, in some cases, semiconductor memory elements.

Hartenstein, R. G.↗
NASA NTRS1972

Flow field analysis of aircraft configurations using a numerical solution to the three-dimensional unified supersonic/hypersonic small disturbance equations, part 1

The unified small disturbance equations are numerically solved using the well-known Lax-Wendroff finite difference technique. The method allows complete determination of the inviscid flow field and surface properties as long as the flow remains supersonic. Shock waves and other discontinuities are accounted for implicity in the numerical method. This technique was programed for general application to the three-dimensional case. The validity of the method is demonstrated by calculations on cones, axisymmetric bodies, lifting bodies, delta wings, and a conical wing/body combination. Part 1 contains the discussion of problem development and results of the study. Part 2 contains flow charts, subroutine descriptions, and a listing of the computer program.

Gunness, R. C., Jr.↗
NASA NTRS1972

Computerized multilevel analysis for multilayered fiber composites

A FORTRAN 4 computer code for the micromechanics, macromechanics, and laminate analysis of multilayered fiber composite structural components is described. The code can be used either individually or as a subroutine within a complex structural analysis/synthesis program. The inputs to the code are constituent materials properties, composite geometry, and loading conditions. The outputs are various properties for ply and composite; composite structural response, including bending-stretching coupling; and composite stress analysis, including comparisons with failure criteria for combined stress. The code was used successfully in the analysis and structural synthesis of flat panels, in the buckling analysis of flat panels, in multilayered composite material failure studies, and lamination residual stresses analysis.

Chamis, C. C.↗
NASA NTRS1972

Constrained Chebyshev approximations to some elementary functions suitable for evaluation with floating point arithmetic

Approximations which can be evaluated with precision using floating-point arithmetic are presented. The particular set of approximations thus far developed are for the function TAN and the functions of USASI FORTRAN excepting SQRT and EXPONENTIATION. These approximations are, furthermore, specialized to particular forms which are especially suited to a computer with a small memory, in that all of the approximations can share one general purpose subroutine for the evaluation of a polynomial in the square of the working argument.

Manos, P.↗
NASA NTRS1971

Iterative computation of generalized inverses, with an application to CMG steering laws

A cubically convergent iterative method for computing the generalized inverse of an arbitrary M X N matrix A is developed and a FORTRAN subroutine by which the method was implemented for real matrices on a CDC 3200 is given, with a numerical example to illustrate accuracy. Application to a redundant single-gimbal CMG assembly steering law is discussed.

Steincamp, J. W.↗
NASA NTRS1972

STEEP32 computer code

A manual is presented as an aid in using the STEEP32 code. The code is the EXEC 8 version of the STEEP code (STEEP is an acronym for shock two-dimensional Eulerian elastic plastic). The major steps in a STEEP32 run are illustrated in a sample problem. There is a detailed discussion of the internal organization of the code, including a description of each subroutine.

Goerke, W. S.↗
NASA NTRS1971

Transpiration and film cooling boundary layer computer program. Volume 2: Computer program and user's manual

A finite difference turbulent boundary layer computer program which allows for mass transfer wall cooling and equilibrium chemistry effects is presented. The program is capable of calculating laminar or turbulent boundary layer solutions for an arbitrary ideal gas or an equilibrium hydrogen oxygen system. Either two dimensional or axisymmetric geometric configurations may be considered. The equations are solved, in nondimension-alized physical coordinates, using the implicit Crank-Nicolson technique. The finite difference forms of the conservation of mass, momentum, total enthalpy and elements equations are linearized and uncoupled, thereby generating easily solvable tridiagonal sets of algebraic equations. A detailed description of the computer program, as well as a program user's manual is provided. Detailed descriptions of all boundary layer subroutines are included, as well as a section defining all program symbols of principal importance. Instructions are then given for preparing card input to the program and for interpreting the printed output. Finally, two sample cases are included to illustrate the use of the program.

Gloss, R. J.↗
NASA NTRS1972

Theoretical prediction of interference loading on aircraft stores. Part 3: Programmer's manual

A FORTRAN program is described for predicting interference loading on aircraft stores. An analysis of the program is presented from a programmer's point of view, including program organization, subroutine explanations, and FORTRAN variable definitions. This information is intended for use in any program modification, extension, or troubleshooting efforts. This manual is supplementary to the separately documented program theory and user information.

Danfernandes, F.↗
NASA NTRS1972

Conjugate gradient optimization programs for shuttle reentry

Two computer programs for shuttle reentry trajectory optimization are listed and described. Both programs use the conjugate gradient method as the optimization procedure. The Phase 1 Program is developed in cartesian coordinates for a rotating spherical earth, and crossrange, downrange, maximum deceleration, total heating, and terminal speed, altitude, and flight path angle are included in the performance index. The programs make extensive use of subroutines so that they may be easily adapted to other atmospheric trajectory optimization problems.

Powers, W. F.↗
NASA NTRS1971

The application of generalized, cyclic, and modified numerical integration algorithms to problems of satellite orbit computation

Generalized, cyclic, and modified multistep numerical integration methods are developed and evaluated for application to problems of satellite orbit computation. Generalized methods are compared with the presently utilized Cowell methods; new cyclic methods are developed for special second-order differential equations; and several modified methods are developed and applied to orbit computation problems. Special computer programs were written to generate coefficients for these methods, and subroutines were written which allow use of these methods with NASA's GEOSTAR computer program.

Chesler, L.↗
NASA NTRS1972

Extended precision software packages

A description of three extended precision packages is presented along with three small conversion subroutines which can be used in conjunction with the extended precision packages. These extended packages represent software packages written in FORTRAN 4. They contain normalized or unnormalized floating point arithmetic with symmetric rounding and arbitrary mantissa lengths, and normalized floating point interval arithmetic with appropriate rounding. The purpose of an extended precision package is to enable the user to use and manipulate numbers with large decimal places as well as those with small decimal places where precision beyond double precision is required.

Phillips, E. J.↗
NASA NTRS1972

The NASTRAN contour plotter

The NASTRAN contour plotter, a group of subroutines and modifications to the NASTRAN plot module, enables contour lines to be superimposed on the plot of the structural model or on an outline of the structural model. The NASTRAN contour plotter can be incorporated into NASTRAN version 12. Consistent with the NASTRAN computer program, it is operational on the IBM 360, the CDC 6000, and the Univac 1108 computers on a variety of plotter hardware.

Kelly, B. M.↗
NASA NTRS1972

Theoretical determination of cesiated work functions

A computer program based on the theoretical work of Gyftopoulos, Steiner, and Levine on bimetallic systems and using a modified version of Wilkins' SIMCON subroutine SURFAS was written for the Univac 1108. This program, WFGSL, accepts the operating conditions and the physical parameters pertinent to the substrate and adsorbate, and outputs the field-free work function, electron current (Richardson equation), ion current (Saha equation), and fractional substrate coverage by the adsorbate. A brief description of the theory is presented together with a program description and listing. An application of the program to a bimetallic system of cesium (adsorbate) and rhenium (substrate) is also described.

Szejn, R. M.↗
NASA NTRS1972

Computerized multilevel analysis for multilayered fiber composites.

A FORTRAN IV computer code for the micromechanics, macromechanics, and laminate analysis of multilayered fiber composite structural components is described. The code can be used either individually or as a subroutine within a complex structural analysis/synthesis program. The inputs to the code are constituent materials properties, composite geometry, and loading conditions. The outputs are various properties for ply and composite; composite structural response, including bending-stretching coupling; and composite stress analysis, including comparisons with failure criteria for combined stress. The code was used successfully in the analysis and structural synthesis of flat panels, in the buckling analysis of flat panels, in multilayered composite material failure studies, and lamination residual stresses analysis.

Chamis, C. C.↗
NASA NTRS1972

Spectral factorization in periodically time-varying systems and application to navigation problems.

Spectral factorization has been used previously to derive the steady-state solution of Kalman filtering equations without iteration for constant coefficient systems. The present work extends the spectral factorization algorithm to time-varying systems having periodic coefficient matrices for cases of both discrete and continuous systems. Time-consuming, expensive iterations of sequential covariance equations are not required to reach the final solution since this is an algebraic algorithm employing existing eigenvalue, eigenvector subroutines. The computer program incorporating the algorithm is suitable for sensitivity studies in formulating navigation and guidance strategies of low-thrust interplanetary missions. The determination of an optimum tracking pattern from an earth station is examined as an example.

Nishimura, T.↗