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Results for “parameter optimization”

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 451 records · Page 25

All sources NASA NTRS DOE OSTI

NASA NTRS1973

Development of advanced materials composites for use as insulations for LH2 tanks

A study of thread-reinforced polyurethane foam and glass fabric liner, serving as internally bonded insulation for space shuttle LH2 tanks, is reported. Emphasis was placed on an insulation system capable of reentry and multiple reuse in the shuttle environment. The optimized manufacturing parameters associated with each element of the composite are established and the results, showing successful completion of subscale system evaluation tests using the shuttle flight environmental requirements, are given.

Lemons, C. R.↗

NASA NTRS1974

Dynamics computation methodology applied to railcar vibrations

The analytical models discussed present typical examples of analyses performed to optimize vehicle parameters and solve specific engineering problems. Subjects investigated include: (1) car body structural dynamics, (2) vehicle dynamic motions and loads, and (3) truck equalization.

Vlaminck, R. R.↗

NASA NTRS1975

Research in millimeter wave techniques

A model 180-GHz radiometer, employing a Cassegrain feed geometry with a parabolic main reflector and a subreflector fed by a corrugated conical horn, was constructed and tested. An absorber-coated chopper is used to modulate the signal, which is down-converted in a cross-guide harmonic mixer. A 100-GHz source was used to evaluate mixer performance and to optimize system parameters. Preliminary results indicate a noise figure of approximately 20 db is being achieved. Preliminary design studies and on-going research plans are discussed.

Dees, J. W.↗

NASA NTRS1977

Active optics simulation system

Set of three major computer program packages aids design of mirror control system for large telescopes. It can be used to evaluate merit of particular active optics control system (or component subsystem); and once system configuration is chosen, it can be used as design aid to optimize system parameters.

Source record↗

NASA NTRS1976

Space stable thermal control coatings

The MOX method, i.e., the use of zinc and titanium oxalate precursors, has the distinct advantages of simple and rapid processing, and of controlled pigment particle size. The chemical identify of TiOX was determined. The Zn/Ti ratio effect on the reflectance spectra and ultraviolet irradiation stability in vacuum for Zn2TiO4 was examined. Optimized processing parameters are considered for reproducibly obtaining a pigment of the most desirable optical properties and behavior.

Harada, Y.↗

NASA NTRS1977

Concept report: Microprocessor control of electrical power system

An electrical power system which uses a microprocessor for systems control and monitoring is described. The microprocessor controlled system permits real time modification of system parameters for optimizing a system configuration, especially in the event of an anomaly. By reducing the components count, the assembling and testing of the unit is simplified, and reliability is increased. A resuable modular power conversion system capable of satisfying a large percentage of space applications requirements is examined along with the programmable power processor. The PC global controller which handles systems control and external communication is analyzed, and a software description is given. A systems application summary is also included.

Perry, E.↗

NASA NTRS1977

Toward fully automated agricultural inventory from satellites

Conventional approaches to inventories from satellites rely heavily on the judgment of image analysts, who 'train' the computer classification program. The fully automated approach to this problem, described in the present paper, eliminates the need for human judgment in training the computer, by using fully automated techniques for selecting spectral characteristics and classification parameters to optimize agreement with ground truth in specified test areas.

Ungar, S. G.↗

NASA NTRS1978

Helicopter mission optimization study

The feasibility of using low-cost, portable computer technology to help a helicopter pilot optimize flight parameters to minimize fuel consumption and takeoff and landing noise was demonstrated. Eight separate computer programs were developed for use in the helicopter cockpit using a hand-held computer. The programs provide the helicopter pilot with the ability to calculate power required, minimum fuel consumption for both range and endurance, maximum speed and a minimum noise profile for both takeoff and landing. Each program is defined by a maximum of two magnetic cards. The helicopter pilot is required to key in the proper input parameter such as gross weight, outside air temperature or pressure altitude.

Olson, J. R.↗

NASA NTRS1980

A nonreflecting outflow boundary condition for subsonic Navier-Stokes calculations

A nonreflecting boundary condition is presented for the numerical solution of the time-dependent compressible Navier-Stokes equations when these equations are used to obtain a steady state. This boundary condition is shown to be effective in reducing reflections at a subsonic outflow boundary. Numerical calculations using a model problem were made to compare this boundary condition with other outflow boundary conditions. The nonreflecting boundary condition contains a parameter whose optimal value is estimated using the analysis of a simplified set of equations.

Rudy, D. H.↗

NASA NTRS1979

Development of RF sputtered chromium oxide coating for wear application

The radio frequency sputtering technique was used to deposite a hard refractory, chromium oxide coating on an Inconel X-750 foil 0.1 mm thick. Optimized sputtering parameters for a smooth and adherent coating were found to be as follows: target-to-substrate spacing, 41.3 mm; argon pressure, 5-10 mTorr; total power to the sputtering module, 400 W (voltage at the target, 1600 V), and a water-cooled substrate. The coating on the annealed foil was more adherent than that on the heat-treated foil. Substrate biasing during the sputter deposition of Cr2O3 adversely affected adherence by removing naturally occurring interfacial oxide layers. The deposited coatings were amorphous and oxygen deficient. Since amorphous materials are extremely hard, the structure was considered to be desirable.

Bhushan, B.↗

NASA NTRS1980

Structural and compositional characterization of RF sputter-deposited Ni-Cr + Cr2O3 films

An RF-sputtered chrome oxide coating with metallic binders was developed. The chrome oxide coating has high-temperature capabilities and is wear resistant, and has some self-lubricating properties. A nichrome metallic binder was added in the coating to improve its ductility without significant loss in the hardness. The sputtering parameters were optimized to obtain a smooth coating with the maximum adherence. The coatings were applied using bias-sputter and sputter-deposit modes on the heat treated and annealed foil substrates. The coating applied on annealed foils using the sputter-deposit mode was smooth and had the best adherence. Metallurgical examinations showed that the coating was Ni-Cr + Cr2O3. The coating as applied was amorphous and it crystallized during substrate heat treatment.

Bhushan, B.↗

NASA NTRS1980

Context distribution estimation for contextual classification of multispectral image data

A classification algorithm incorporating contextual information in a general, statistical manner is presented. Methods are investigated for obtaining adequate estimates of the context distribution (a statistical characterization of context) upon which the classification algorithm depends. Finally, a method of estimating optimal algorithm parameters prior to performing preliminary classifications is explored.

Tilton, J. C.↗

NASA NTRS1982

Conversion and matched filter approximations for serial minimum-shift keyed modulation

Serial minimum-shift keyed (MSK) modulation, a technique for generating and detecting MSK using series filtering, is ideally suited for high data rate applications provided the required conversion and matched filters can be closely approximated. Low-pass implementations of these filters as parallel inphase- and quadrature-mixer structures are characterized in this paper in terms of signal-to-noise ratio (SNR) degradation from ideal and envelope deviation. Several hardware implementation techniques utilizing microwave devices or lumped elements are presented. Optimization of parameter values results in realizations whose SNR degradation is less than 0.5 dB at error probabilities of .000001.

Ziemer, R. E.↗

NASA NTRS1981

Optimization of radar imaging system parameters for geological analysis

The use of radar image simulation to model terrain variation and determine optimum sensor parameters for geological analysis is described. Optimum incidence angle is determined by the simulation, which evaluates separately the discrimination of surface features possible due to terrain geometry and that due to terrain scattering. Depending on the relative relief, slope, and scattering cross section, optimum incidence angle may vary from 20 to 80 degrees. Large incident angle imagery (more than 60 deg) is best for the widest range of geological applications, but in many cases these large angles cannot be achieved by satellite systems. Low relief regions require low incidence angles (less than 30 deg), so a satellite system serving a broad range of applications should have at least two selectable angles of incidence.

Waite, W. P.↗

NASA NTRS1984

Abrasive tip treatment for use on compressor blades

A co-spray process was used which simultaneously but separately introduces abrasive grits and metal matrix powder into the plasma stream and entraps the abrasive grits within a molten matrix to form an abrasive coating as the matrix material solidifies on test specimen surfaces. Spray trials were conducted to optimize spray parameter settings for the various matrix/grit combinations before actual spraying of the test specimens. Rub, erosion, and bond adhesion tests were conducted on the coated specimens in the as-sprayed condition as well as on coated specimens that were aged for 100 hours at a temperature of 866K (1100 F). Microscopic examinations were performed to determine the coating abrasive-particle content, the size and shape of the adhesive particles in the coating, and the extent of compositional or morphological changes resulting from the aging process. A nickel chromium/aluminum composite with No. 150 size (0.002 to 0.005 inch) silicon carbide grits was selected as the best matrix/abrasive combination of the candidates surveyed for coating compressor blade tips.

Pedersen, H. C.↗

NASA NTRS1984

Carbon-13 and proton nuclear magnetic resonance analysis of shale-derived refinery products and jet fuels and of experimental referee broadened-specification jet fuels

A proton and carbon-13 nuclear magnetic resonance (NMR) study was conducted of Ashland shale oil refinery products, experimental referee broadened-specification jet fuels, and of related isoprenoid model compounds. Supercritical fluid chromatography techniques using carbon dioxide were developed on a preparative scale, so that samples could be quantitatively separated into saturates and aromatic fractions for study by NMR. An optimized average parameter treatment was developed, and the NMR results were analyzed in terms of the resulting average parameters; formulation of model mixtures was demonstrated. Application of novel spectroscopic techniques to fuel samples was investigated.

Dalling, D. K.↗

NASA NTRS1984

Injection molding of silicon carbide capable of being sintered without pressure

The most suitable SiC mass for injection molding of SiC articles (for subsequent pressureless sintering) consisted of beta SiC 84, a wax mixture 8, and polyethylene or polystyrene 8 parts. The most effective method for adding the binders was by dissolving them in a solvent and subsequent evaporation. The sequence of component addition was significant, and all parameters were optimized together rather than individually.

Muller-Zell, A.↗

NASA NTRS1985

Proceedings of the Workshop on Identification and Control of Flexible Space Structures, Volume 3

The results of a workshop on identification and control of flexible space structures are reported. This volume deals mainly with control theory and methodologies as they apply to space stations and large antennas. Integration and dynamics and control experimental findings are reported. Among the areas of control theory discussed were feedback, optimization, and parameter identification.

Rodriguez, G.↗