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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 1,315 records · Page 73
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Accuracy of remotely sensed data: Sampling and analysis procedures

A review and update of the discrete multivariate analysis techniques used for accuracy assessment is given. A listing of the computer program written to implement these techniques is given. New work on evaluating accuracy assessment using Monte Carlo simulation with different sampling schemes is given. The results of matrices from the mapping effort of the San Juan National Forest is given. A method for estimating the sample size requirements for implementing the accuracy assessment procedures is given. A proposed method for determining the reliability of change detection between two maps of the same area produced at different times is given.

Congalton, R. G.↗
NASA NTRS1983

New test techniques and analytical procedures for understanding the behavior of advanced propellers

Analytical procedures and experimental techniques were developed to improve the capability to design advanced high speed propellers. Some results from the propeller lifting line and lifting surface aerodynamic analysis codes are compared with propeller force data, probe data and laser velocimeter data. In general, the code comparisons with data indicate good qualitative agreement. A rotating propeller force balance demonstrated good accuracy and reduced test time by 50 percent. Results from three propeller flow visualization techniques are shown which illustrate some of the physical phenomena occurring on these propellers.

Stefko, G. L.↗
NASA NTRS1982

The Shuttle Environment Workshop, executive summary and workshop procedures

One of the main experimental monitors used to determine the environment in the payload bay was the Induced Environment Contamination Monitor. This package of instruments has made environmental measurements during STS flights with a high degree of success. This has shown that the shuttle environment is relatively free of contaminants, except for special instances of increased abundance of methane, water vapor and particulates. Results of these measurements are rapidly becoming more available. In establishing the Shuttle Environment Workshop, the findings were shared with scientific experimenters, users and other individuals who need to know what the Shuttle is like and what experimenters may expect in the payload bay. The Workshop was centered around results obtained from the environmental measurements made on the Shuttle. The program agenda for the workshop is given. The procedures and flow of communications for the workshop are indicated.

Lehmann, J.↗
NASA NTRS1983

Development of an analytic procedure to calculate damage accumulation in composites during low velocity impact

A computerized procedure was developed to model the response of a laminated composite plate subjected to low velocity impact. The methodology incorporated transient dynamics finite element analysis coupled with composite layer and interlaminar stress predictions. Damage was predicted using a stress based failure criteria and incorporated into the solution as stiffness modifications. The force-displacement relation between the impactor and plate was modelled with a nonlinear contact spring similar to Hertzian contact. Analyses performed predicted ply damage early in the impact event when the displacement fields were characteristic of high frequency flexurable response.

Humphreys, E. A.↗
NASA NTRS1983

VAS operational procedures and results at the Kansas City Satellite Field Services Station

An operational assessment of VAS data by using a Man-computer Interactive Data Access System (McIDAS) terminal linked by a 9600 band telephone line is discussed. Seven hours of VAS data were processed and edited daily. Data was scheduled 16 hours a day, 7 days a week; however, during this time period there were very few days with 16 hours of data to evalute. The McIDAS terminal, which has 10 display frames and 5 graphics, provide access to the sounding data processed. These data are processed using two procedures. The dwell sounding data are generated by using all 12 spectral channels with a spin budget of 39. To provide coverage for most of the United States, soundings are made starting at 18 minutes after the hour from approximately 49 deg N to 36 deg N and at 48 minutes after the hour from 36 deg N to 26 deg N. The dwell imaging mode uses 11 channels but the spin budge is 17. With the reduced spin budget, retrievals can be made at 18 or 48 minutes after the hour for approximately 44 deg N to 27 deg N. With these constraints a schedule, of data sets was proposed to use the schedule and how the data set could be used are shown.

Heckman, B.↗
NASA NTRS1983

Design procedures for fiber composite structural components: Rods, columns and beam columns

Step by step procedures are described which are used to design structural components (rods, columns, and beam columns) subjected to steady state mechanical loads and hydrothermal environments. Illustrative examples are presented for structural components designed for static tensile and compressive loads, and fatigue as well as for moisture and temperature effects. Each example is set up as a sample design illustrating the detailed steps that are used to design similar components.

Chamis, C. C.↗
NASA NTRS1983

Constrained Self-adaptive Solutions Procedures for Structure Subject to High Temperature Elastic-plastic Creep Effects

This paper will develop a new solution strategy which can handle elastic-plastic-creep problems in an inherently stable manner. This is achieved by introducing a new constrained time stepping algorithm which will enable the solution of creep initiated pre/postbuckling behavior where indefinite tangent stiffnesses are encountered. Due to the generality of the scheme, both monotone and cyclic loading histories can be handled. The presentation will give a thorough overview of current solution schemes and their short comings, the development of constrained time stepping algorithms as well as illustrate the results of several numerical experiments which benchmark the new procedure.

Padovan, J.↗
NASA NTRS1983

A root locus based flutter synthesis procedure

An efficient generalized constraint is proposed in the context of a nonlinear mathematical programming approach for the minimum weight design of wing structures for flutter considerations. The approach is based on a root locus analysis procedure that is better suited for flutter redesign than the conventionally used V-g method. The proposed flutter constraint does not require an actual computation of the flutter speed, allows prescription of meaningful margins of safety in the optimized design and lends itself to elegant computation of sensitivity information. The approach is implemented and results presented for representative structural models.

Hajela, P.↗
NASA NTRS1982

Numerical boundary condition procedures and multigrid methods; Proceedings of the Symposium, NASA Ames Research Center, Moffett Field, CA, October 19-22, 1981

Papers presented in this volume provide an overview of recent work on numerical boundary condition procedures and multigrid methods. The topics discussed include implicit boundary conditions for the solution of the parabolized Navier-Stokes equations for supersonic flows; far field boundary conditions for compressible flows; and influence of boundary approximations and conditions on finite-difference solutions. Papers are also presented on fully implicit shock tracking and on the stability of two-dimensional hyperbolic initial boundary value problems for explicit and implicit schemes.

Source record↗
NASA NTRS1982

Top-off procedure for space-bound superfluid helium cryostats

Tests have been carried out on the transfer of pressurized liquid helium, slightly above the lambda temperature, in order to determine the optimum transfer parameters for a ground-based top-off just prior to launch. It is shown that the maximum mass fill of a spaceborne cryostat can be accomplished with the low-pressure top-off after initial fill with normal helium. The realistic maximum fill at temperatures below the lambda temperature can be expected to be at least 90 percent, which results in about 40 to 50 percent more mass at launch than without the top-off. In each case, specific ground support equipment is required to satisfy the individual cryostat requirements and extreme care is necessary during the transfer procedure.

Petrac, D.↗
NASA NTRS1983

Development of a systems theoretical procedure for evaluation of the work organization of the cockpit crew of a civil transport airplane

To achieve optimum design for the man machine interface with aircraft, a description of the interaction and work organization of the cockpit crew is needed. The development of system procedure to evaluate the work organization of pilots while structuring the work process is examined. Statistical data are needed to simulate sequences of pilot actions on the computer. Investigations of computer simulation and applicability for evaluation of crew concepts are discussed.

Fricke, M.↗
NASA NTRS1984

An analytical design procedure for the determination of effective leading edge extensions on thick delta wings

An analytical design procedure for leading edge extensions (LEE) was developed for thick delta wings. This LEE device is designed to be mounted to a wing along the pseudo-stagnation stream surface associated with the attached flow design lift coefficient of greater than zero. The intended purpose of this device is to improve the aerodynamic performance of high subsonic and low supersonic aircraft at incidences above that of attached flow design lift coefficient, by using a vortex system emanating along the leading edges of the device. The low pressure associated with these vortices would act on the LEE upper surface and the forward facing area at the wing leading edges, providing an additional lift and effective leading edge thrust recovery. The first application of this technique was to a thick, round edged, twisted and cambered wing of approximately triangular planform having a sweep of 58 deg and aspect ratio of 2.30. The panel aerodynamics and vortex lattice method with suction analogy computer codes were employed to determine the pseudo-stagnation stream surface and an optimized LEE planform shape.

Farhad Ghaffari↗
NASA NTRS1984

Development of a simplified procedure for cyclic structural analysis

Development was extended of a simplified inelastic analysis computer program (ANSYMP) for predicting the stress-strain history at the critical location of a thermomechanically cycled structure from an elastic solution. The program uses an iterative and incremental procedure to estimate the plastic strains from the material stress-strain properties and a plasticity hardening model. Creep effects can be calculated on the basis of stress relaxation at constant strain, creep at constant stress, or a combination of stress relaxation and creep accumulation. The simplified method was exercised on a number of problems involving uniaxial and multiaxial loading, isothermal and nonisothermal conditions, dwell times at various points in the cycles, different materials, and kinematic hardening. Good agreement was found between these analytical results and nonlinear finite-element solutions for these problems. The simplified analysis program used less than 1 percent of the CPU time required for a nonlinear finite-element analysis.

Kaufman, A.↗
NASA NTRS1984

Element-by-element Solution Procedures for Nonlinear Structural Analysis

Element-by-element approximate factorization procedures are proposed for solving the large finite element equation systems which arise in nonlinear structural mechanics. Architectural and data base advantages of the present algorithms over traditional direct elimination schemes are noted. Results of calculations suggest considerable potential for the methods described.

Hughes, T. J. R.↗
NASA NTRS1984

Guidelines for testing and release procedures

Guidelines and procedures are recommended for the testing and release of the types of computer software efforts commonly performed at NASA/Ames Research Center. All recommendations are based on the premise that testing and release activities must be specifically selected for the environment, size, and purpose of each individual software project. Guidelines are presented for building a Test Plan and using formal Test Plan and Test Care Inspections on it. Frequent references are made to NASA/Ames Guidelines for Software Inspections. Guidelines are presented for selecting an Overall Test Approach and for each of the four main phases of testing: (1) Unit Testing of Components, (2) Integration Testing of Components, (3) System Integration Testing, and (4) Acceptance Testing. Tools used for testing are listed, including those available from operating systems used at Ames, specialized tools which can be developed, unit test drivers, stub module generators, and the use of format test reporting schemes.

Molari, R.↗
NASA NTRS1984

Rocket injector anomalies study. Volume 1: Description of the mathematical model and solution procedure

The capability of simulating three dimensional two phase reactive flows with combustion in the liquid fuelled rocket engines is demonstrated. This was accomplished by modifying an existing three dimensional computer program (REFLAN3D) with Eulerian Lagrangian approach to simulate two phase spray flow, evaporation and combustion. The modified code is referred as REFLAN3D-SPRAY. The mathematical formulation of the fluid flow, heat transfer, combustion and two phase flow interaction of the numerical solution procedure, boundary conditions and their treatment are described.

Przekwas, A. J.↗