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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 235 records · Page 13

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NASA NTRS1977

Development of a drift-correction procedure for a direct-reading spectrometer

A procedure which provides automatic correction for drifts in the radiometric sensitivity of each detector channel in a direct-reading emission spectrometer is described. Such drifts are customarily controlled by the regular analyses of standards, which provide corrections for changes in the excitational, optical, and electronic components of the instrument. This standardization procedure, however, corrects for the optical and electronic drifts. It is a step that must be taken if the time, effort, and cost of processing standards is to be minimized. This method of radiometric drift correction uses a 1,000-W tungsten-halogen reference lamp to illuminate each detector through the same optical path as that traversed during sample analysis. The responses of the detector channels to this reference light are regularly compared with channel response to the same light intensity at the time of analytical calibration in order to determine and correct for drift. Except for placing the lamp in position, the procedure is fully automated and compensates for changes in spectral intensity due to variations in lamp current. A discussion of the implementation of this drift-correction system is included.

Chapman, G. B., II↗

NASA NTRS1977

Recommended procedures for measuring aircraft noise and associated parameters

Procedures are recommended for obtaining experimental values of aircraft flyover noise levels (and associated parameters). Specific recommendations are made for test criteria, instrumentation performance requirements, data-acquisition procedures, and test operations. The recommendations are based on state-of-the-art measurement capabilities available in 1976 and are consistent with the measurement objectives of the NASA Aircraft Noise Prediction Program. The recommendations are applicable to measurements of the noise produced by an airplane flying subsonically over (or past) microphones located near the surface of the ground. Aircraft types covered by the recommendations are fixed-wing airplanes powered by turbojet or turbofan engines and using conventional aerodynamic means for takeoff and landing. Various assumptions with respect to subsequent data processing and analysis were made (and are described) and the recommended measurement procedures are compatible with the assumptions. Some areas where additional research is needed relative to aircraft flyover noise measurement techniques are also discussed.

Marsh, A. H.↗

NASA NTRS1976

An automated procedure for preliminary design of primary structure for transport Aircraft

A multistation structural synthesis procedure, designed to perform structural sizing and detail design of boxbeam structure, is presented. The design procedure combines the use of an iterative sizing technique for distributing material to structural elements with a nonlinear programming technique to finding efficient structural element designs of a given weight. Constraints based on fatigue and fracture criteria and static strength criteria under multiple loading conditions are considered, as well as constraints on the upper and lower bounds of the actual design variables. Emphasis is placed on the overall design procedure and the technique used to include the fatigue and fracture criteria.

Kruse, G. S.↗

NASA NTRS1976

Procedures used in flight tests of an integrated propulsion control system on an F-111E airplane

A digital integrated propulsion control system (IPCS) was tested on an F-111E airplane. The IPCS provided full authority control of the left inlet and the TF30 afterburning engine. Supersonic test conditions were of primary interest. The operational procedures and maneuvers developed for IPCS evaluation, displays for test monitoring and data acquisition, flight safety, and problems encountered are discussed. The software refinements that made modifications to standard flight test procedures necessary are described. The flexibility of digital control and the ways software was used to overcome hardware deficiencies are discussed. Application of these procedures to a typical IPCS flight is described.

Baer, J. L.↗

NASA NTRS1977

A procedure for accurate calibration of the orientation of the three sensors in a vector magnetometer

Procedures are described for the calibration of a vector magnetometer of high absolute accuracy. It is assumed that the calibration will be performed in the magnetic test facility of Goddard Space Flight Center (GSFC). The first main section of the report describes the test equipment and facility calibrations required. The second presents procedures for calibrating individual sensors. The third discusses the calibration of the sensor assembly. In a final section recommendations are made to GSFC for modification of the test facility required to carry out the calibration procedures.

Mcpherron, R. L.↗

NASA NTRS1977

US terrestrial solar cell calibration and measurement procedures

A workshop was held in the fall of 1976, to evaluate and revise interim terrestrial solar cell calibration and measurement procedures. The revisions made to the interim testing procedures are described. The calibration of reference cells and the design of their holders are covered. Considerations include view angle and optical and thermal matching. Atmospheric factors which affect the calibration and performance of solar cells are discussed. The most critical atmospheric parameter appears to be water vapor. Techniques for matching reference cells to cells or arrays under test are described. Data showing errors in performance under artificial sunlight simulators due to mismatch of reference and test cells are presented. Finally, measurement procedures and data transformations needed to obtain the performance of solar cells and arrays in outdoor natural sunlight are described.

Brandhorst, H. W., Jr.↗

NASA NTRS1978

Numerical procedure to determine geometric view factors for surfaces occluded by cylinders

A numerical procedure was developed to determine geometric view factors between connected infinite strips occluded by any number of infinite circular cylinders. The procedure requires a two-dimensional cross-sectional model of the configuration of interest. The two-dimensional model consists of a convex polygon enclosing any number of circles. Each side of the polygon represents one strip, and each circle represents a circular cylinder. A description and listing of a computer program based on this procedure are included in this report. The program calculates geometric view factors between individual strips and between individual strips and the collection of occluding cylinders.

Sawyer, P. L.↗

NASA NTRS1978

A finite element thermal analysis procedure for several temperature-dependent parameters

A finite-element thermal analysis procedure for elements with several temperature-dependent thermal parameters is presented. The procedure, based on an application of the Newton-Raphson iteration technique, is formulated by resolving element matrices into component matrices, one component for each thermal parameter. Component conductance matrices are evaluated by assuming constant thermal parameters within an element and are computed once per unit thermal parameter. Significant savings in computer time result from the unit thermal parameter concept. The solution procedure applied to a convectively cooled structure with significantly varying thermal parameters converged in four iterations.

Thornton, E. A.↗

NASA NTRS1978

Performance of ground attitude determination procedures for HEAO-1

Ground attitude support for HEAO 1 provided at GSFC by the HEAO 1 Attitude Ground Support System (AGSS) is described. Information telemetered from Sun sensors, gyroscopes, star trackers, and an onboard computer are used by the AGSS to compute updates to the onboard attitude reference and gyro calibration parameters. The onboard computer utilizes these updates in providing continuous attitudes (accurate to 0.25degree) for use in the observatory's attitude control procedures. The relationship between HEAO 1 onboard and ground processing, the procedures used by the AGSS in computing attitude and gyro calibration updates, and the performance of these procedures in the HEAO 1 postlaunch environment is discussed.

Fallon, L., III↗

NASA NTRS1979

A consistent design procedure for supercritical airfoils in free air and a wind tunnel

A computational inverse procedure for transonic airfoils in which shapes are determined supporting prescribed pressure distributions is presented. The method uses the small disturbance equation and a consistent analysis-design differencing procedure at the airfoil surface. This avoids the intermediate analysis-design-analysis iterations. The effect of any openness at the trailing edge is taken onto account by adding an effective source term in the far field. The final results from a systematic expansion procedure which models the far field for solid, ideal slotted, and free jet tunnel walls are presented along with some design results for the associated boundary conditions and those for a free flight.

Shankar, V.↗

NASA NTRS1979

Large Area Crop Inventory Experiment (LACIE). Development of procedure M for multicrop inventory, with tests of a spring-wheat configuration

The author has identified the following significant results. An outgrowth of research and development activities in support of LACIE was a multicrop area estimation procedure, Procedure M. This procedure was a flexible, modular system that could be operated within the LACIE framework. Its distinctive features were refined preprocessing (including spatially varying correction for atmospheric haze), definition of field like spatial features for labeling, spectral stratification, and unbiased selection of samples to label and crop area estimation without conventional maximum likelihood classification.

Horvath, R.↗

NASA NTRS1979

Standard operating procedures, water immersion facility, revision B

General guideline procedures to identify those factors that are common to all spacecraft design laboratory support group emergency procedures and to establish the basic rescue plan are presented. This eliminates needless repetition of the fundamentals from the other, more specific procedures.

Source record↗

NASA NTRS1979

An evaluation of procedure 1

LACIE Procedure 1 has undergone continuous testing and evaluation, starting with analytical and experimental studies even before it was implemented in ERIPS software and continuing to the present with performance evaluations using blind-site data. The strengths and weaknesses of the procedure are indicated and some areas for possible improvement are identified. Results from three of the experiments performed and an evaluation of LACIE Procedure 1 proportion estimates for some blind-site segments are discussed.

Wheeler, S. G.↗

NASA NTRS1980

Application of advanced computational procedures for modeling solar-wind interactions with Venus: Theory and computer code

Computational procedures are developed and applied to the prediction of solar wind interaction with nonmagnetic terrestrial planet atmospheres, with particular emphasis to Venus. The theoretical method is based on a single fluid, steady, dissipationless, magnetohydrodynamic continuum model, and is appropriate for the calculation of axisymmetric, supersonic, super-Alfvenic solar wind flow past terrestrial planets. The procedures, which consist of finite difference codes to determine the gasdynamic properties and a variety of special purpose codes to determine the frozen magnetic field, streamlines, contours, plots, etc. of the flow, are organized into one computational program. Theoretical results based upon these procedures are reported for a wide variety of solar wind conditions and ionopause obstacle shapes. Plasma and magnetic field comparisons in the ionosheath are also provided with actual spacecraft data obtained by the Pioneer Venus Orbiter.

Stahara, S. S.↗

NASA NTRS1980

Effectiveness of advanced fuel-conservative procedures in the transitional ATC environment

The real time simulation (involving both the pilot and the air traffic controller) of fuel conservative approaches, profile descents, and four dimensional area navigation to assess the effectiveness of the procedures is discussed. Generally, results indicate some difficulties with the procedures tested in a mixed traffic environment and point to the need for computer assistance for effective implementation of candidate procedures.

Tobias, L.↗

NASA NTRS1980

Substructure procedure for including tile flexibility in stress analysis of shuttle thermal protection system

A substructure procedure to include the flexibility of the tile in the stress analysis of the shuttle thermal protection system (TPS) is described. In this procedure, the TPS is divided into substructures of (1) the tile which is modeled by linear finite elements and (2) the SIP which is modeled as a nonlinear continuum. This procedure was applied for loading cases of uniform pressure, uniform moment, and an aerodynamic shock on various tile thicknesses. The ratios of through-the-thickness stresses in the SIP which were calculated using a flexible tile compared to using a rigid tile were found to be less than 1.05 for the cases considered.

Giles, G. L.↗

NASA NTRS1980

Evaluation of results of US corn and soybeans exploratory experiment: Classification procedures verification test

The classification procedure utilized in making crop proportion estimates for corn and soybeans using remotely sensed data was evaluated. The procedure was derived during the transition year of the Large Area Crop Inventory Experiment. Analysis of variance techniques were applied to classifications performed by 3 groups of analysts who processed 25 segments selected from 4 agrophysical units (APU's). Group and APU effects were assessed to determine factors which affected the quality of the classifications. The classification results were studied to determine the effectiveness of the procedure in producing corn and soybeans proportion estimates.

Carnes, J. G.↗

NASA NTRS1981

A rapid perturbation procedure for determining nonlinear flow solutions: Application to transonic turbomachinery flows

Perturbation procedures and associated computational codes for determining nonlinear flow solutions were developed to establish a method for minimizing computational requirements associated with parametric studies of transonic flows in turbomachines. The procedure that was developed and evaluated was found to be capable of determining highly accurate approximations to families of strongly nonlinear solutions which are either continuous or discontinuous, and which represent variations in some arbitrary parameter. Coordinate straining is employed to account for the movement of discontinuities and maxima of high gradient regions due to the perturbation. The development and results reported are for the single parameter perturbation problem. Flows past both isolated airfoils and compressor cascades involving a wide variety of flow and geometry parameter changes are reported. Attention is focused in particular on transonic flows which are strongly supercritical and exhibit large surface shock movement over the parametric range studied; and on subsonic flows which display large pressure variations in the stagnation and peak suction pressure regions. Comparisons with the corresponding 'exact' nonlinear solutions indicate a remarkable accuracy and range of validity of such a procedure.

Stahara, S. S.↗