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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 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Formal verification of mathematical software

Methods are investigated for formally specifying and verifying the correctness of mathematical software (software which uses floating point numbers and arithmetic). Previous work in the field was reviewed. A new model of floating point arithmetic called the asymptotic paradigm was developed and formalized. Two different conceptual approaches to program verification, the classical Verification Condition approach and the more recently developed Programming Logic approach, were adapted to use the asymptotic paradigm. These approaches were then used to verify several programs; the programs chosen were simplified versions of actual mathematical software.

Sutherland, D.↗
NASA NTRS1987

Development of an emulation-simulation thermal control model for space station application

Many features were added to the Thermal Control System (TCS) program to increase its user-friendliness. Several apparent inconsistencies were identified. In some instances, these have led to modifications to the source programs. With the summary line-sizing information, the user can more readily compare the TCS program results with other available data. Two mathematical models were completed: one deals with sizing and analysis of bus heat exchangers and the other provides a means of analyzing a variety of heat pipe radiator designs. A generic heat pipe model was added to the TCS Analysis Program.

Colwell, Gene T.↗
NASA NTRS1976

Flight flutter testing technology at Grumman

Analysis techniques used in the automated telemetry station (ATS) for on line data reduction are encompassed in a broad range of software programs. Concepts that form the basis for the algorithms used are mathematically described. The control the user has in interfacing with various on line programs is discussed. The various programs are applied to an analysis of flight data which includes unimodal and bimodal response signals excited via a swept frequency shaker and/or random aerodynamic forces. A nonlinear response error modeling analysis approach is described. Preliminary results in the analysis of a hard spring nonlinear resonant system are also included.

Perangelo, H. J.↗
NASA NTRS1990

Design-Tradeoff Model For Space Station

System Design Tradeoff Model (SDTM) computer program produces information which helps to enforce consistency of design objectives throughout system. Mathematical model of set of possible designs for Space Station Freedom. Program finds particular design enabling station to provide specified amounts of resources to users at lowest total (or life-cycle) cost. Compares alternative design concepts by changing set of possible designs, while holding specified services to users constant, and then comparing costs. Finally, both costs and services varied simultaneously when comparing different designs. Written in Turbo C 2.0.

Chamberlain, Robert G.↗
NASA NTRS1967

Adaptive age replacement.

Loss structure models concerning age replacement policies, discussing mathematical aspects of maintenance with dynamic programming formulation

COST ESTIMATE↗
NASA NTRS1967

State-of-the-art oriented review of CIRCUS

Mathematical procedures for CIRCUS, digital computer program which is based on built-in model library and is capable of time domain analysis of certain circuits

Eskin, H. D.↗
NASA NTRS1973

Formulation of image quality prediction criteria for the Viking lander camera

Image quality criteria are defined and mathematically formulated for the prediction computer program which is to be developed for the Viking lander imaging experiment. The general objective of broad-band (black and white) imagery to resolve small spatial details and slopes is formulated as the detectability of a right-circular cone with surface properties of the surrounding terrain. The general objective of narrow-band (color and near-infrared) imagery to observe spectral characteristics if formulated as the minimum detectable albedo variation. The general goal to encompass, but not exceed, the range of the scene radiance distribution within single, commandable, camera dynamic range setting is also considered.

Huck, F. O.↗
NASA NTRS1975

Algorithms

The implementation of the algorithms used in the flight program to approximate elementary functions and mathematical procedures was checked. This was done by verifying that at least one, and in most cases, more than one function computed through the use of the algorithms was calculated properly. The following algorithms were checked: sine-cosine, arctangent, natural logarithm, square root, inverse square root, as well as the vector dot and cross products.

Source record↗
NASA NTRS1979

A method for the processing and analysis of digital terrain elevation data

A method is presented for the processing and analysis of digital topography data that can subsequently be entered in an interactive data base in the form of slope, slope length, elevation, and aspect angle. A discussion of the data source and specific descriptions of the data processing software programs are included. In addition, the mathematical considerations involved in the registration of raw digitized coordinate points to the UTM coordinate system are presented. Scale factor considerations are also included. Results of the processing and analysis are illustrated using the Shiprock and Gallup Quadrangle test data.

Junkin, B. G.↗
NASA NTRS1987

Calculating Wave Drag on an Aircraft

Improved program based on more-accurate mathematical mode. WDAG2 calculates supersonic zero-lift wave drag of complex aircraft configurations. Incorporates extended capabilities for geometric input to enable use of more-accurate mathematical model. Engineer defines aircraft components as fusiform or non-fusiform by use of traditional parallel contours. Written in FORTRAN IV.

Dollyhigh, Samuel M.↗
NASA NTRS1989

Modeling of transient heat pipe operation

Mathematical models and an associated computer program for heat pipe startup from the frozen state have been developed. Finite element formulations of the governing equations are written for each heat pipe region for each operating condition during startup from the frozen state. The various models were checked against analytical and experimental data available in the literature for three specific types of operation. Computations using the methods developed were made for a space shuttle reentry mission where a heat pipe cooled leading edge was used on the wing.

Colwell, Gene T.↗
NASA NTRS1990

Capillary Pumped Loop Modeler

Capillary Pumped Loop (CPL) Modeler computer program is amalgamation of software that mathematically models performance of CPL system and its environment. Two-phase heat-transport device capable of transferring heat loads efficiently over large distance with little temperature differential. Utilizes surface-tension forces established in fine-pore capillary wick to circulate working fluid, requiring no external pumpling power. Predicts steady-state or quasi-steady behavior of CPL embedded in spacecraft or other thermal environment. Also predicts location of liquid/vapor interface in each condenser. Written in VAX/VMS FORTAN 77.

Ku, Jentung↗
NASA NTRS1993

Displaying Data From Duct/Fluid Calculations

DUCT6D is FORTRAN program for enhancing postprocessing of data computed by programs based on line-element mathematical models, especially dynamical models of ducts and fluids contained in them. Based partly on assumption that coupled duct/fluid-dynamic system analyzed by use of line elements representing beam properties of duct and one-dimensional acoustical properties of fluid. Inputs include geometric data from model and static, modal, or transient-displacement data from solution. Output represents geometry of coupled duct/fluid system and results of analysis by use of three-dimensional shell elements. Written in FORTRAN.

Saxon, Joe B.↗
NASA NTRS1988

Evaluation of structural integrity using integrated testing and analysis

An integrated approach to dynamic testing and mathematical model analysis is described. The overall approach addresses four key tasks, namely, pretest planning and analysis, test data acquisition, data reduction and analysis, and test/analysis correlation and mathematical model updates. Several key software programs are employed to accomplish this task. They are a leading finite element code, a sophisticated data analysis processor and a graphical pre- and post-processor along with an advanced interface utility. Several practical structures are used to illustrate tools and concepts employed in the integrated test analysis process.

Coppolino, Robert N.↗
NASA NTRS1991

Automatic Abstraction in Planning

Traditionally, abstraction in planning has been accomplished by either state abstraction or operator abstraction, neither of which has been fully automatic. We present a new method, predicate relaxation, for automatically performing state abstraction. PABLO, a nonlinear hierarchical planner, implements predicate relaxation. Theoretical, as well as empirical results are presented which demonstrate the potential advantages of using predicate relaxation in planning. We also present a new definition of hierarchical operators that allows us to guarantee a limited form of completeness. This new definition is shown to be, in some ways, more flexible than previous definitions of hierarchical operators. Finally, a Classical Truth Criterion is presented that is proven to be sound and complete for a planning formalism that is general enough to include most classical planning formalisms that are based on the STRIPS assumption.

LOGIC PROGRAMMING↗