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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 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Future trends in image processing software and hardware

JPL image processing applications are examined, considering future trends in fields such as planetary exploration, electronics, astronomy, computers, and Landsat. Attention is given to adaptive search and interrogation of large image data bases, the display of multispectral imagery recorded in many spectral channels, merging data acquired by a variety of sensors, and developing custom large scale integrated chips for high speed intelligent image processing user stations and future pipeline production processors.

Green, W. B.↗
NASA NTRS1980

Metamorphism of the H-group chondrites - Implications from compositional and textural trends in chondrules

The paper discusses element bulk compositions of 373 chondrules from 18 H3 to H6 chondrites determined by broad-beam electron probe analysis. Bulk chondrule FeO and Al2O3 amounts increase and TiO2 and Cr2O3 decrease with increasing petrologic type; normative faylite, albite, and plagioclase amounts increase through the petrologic sequence. Chondrule diameters correlate with phenocryst sizes in porphyritic chondrules of type 3 chondrites, but this correlation is diminished in the higher petrologic types. The compositional trends in chondrules through the petrologic sequence are attributed to diffusion and equilibration among chondrules, and between chondrules and matrix in response to increasing degrees of thermal metamorphism. It is suggested that H-group chondrites are formed by accretion of high-temperature (chondrules) and low-temperature (matrix) materials. Internal reheating of the parent materials to different temperatures caused compositional equilibration, grain coarsening, and reduction of FeO to Fe(0) by carbon.

Lux, G.↗
NASA NTRS1980

JT9D-7A /SP/ jet engine performance deterioration trends

It is noted that increasing fuel costs and the decreasing availability of fuel supplies have lead to an increase in the importance of maintaining good specific fuel consumption over the life cycle of jet engines. Attention is given to an engine diagnostics program sponsored by NASA Lewis Research Center which has the objectives of identifying and quantifying the levels, trends, and causes of engine performance deterioration. It is reported that as part of the program, a series of installed engine calibrations were performed on two new Pan American World Airways 747 SP aircraft. A discussion of this specific test program and the results of the analysis of the data are presented.

Richter, G. P.↗
NASA NTRS1980

The identification of trends in outgassing technology

A large amount of chemical analysis data involving identification of outgassing products from spacecraft, experiment modules, and support equipment accumulated at the Goddard Space Flight Center over the past ten years were reduced to a computer compatible format and subjected to a variety of relevant program operations. From these data a list of the most troublesome outgassing species were compiled and several useful and interesting materials' correlations were developed. The frequency of occurrence totals show that in aerospace program, di(2-ethyl hexyl) phthalate (DEHP) is the most often found individual species in outgassing samples and that esters are the leading generic class of compounds. The effectiveness of this data bank was demonstrated by the good correlations between materials and their outgassing products for solar panel bakeouts and cable bakeouts. However, trends in frequency of occurrence of many compounds were demonstrated where no correlation could be established. In the case of the class of compounds called aliphatic hydrocarbons, it is shown that the number of instances of significant outgassing due to these materials is increasing.

Colony, J. A.↗
NASA NTRS1980

Monitoring and control requirement definition study for Dispersed Storage and Generation (DSG). Volume 3, appendix B: State of the art, trends, and potential growth of selected DSG technologies

Present and future relatively small (30 MW) energy systems, such as solar thermal electric, photovoltaic, wind, fuel cell, storage battery, hydro, and cogeneration can help achieve national energy goals and can be dispersed throughout the distribution portion of an electric utility system. Based on current projections, it appears that dispersed storage and generation (DSG) electrical energy will comprise only a small portion, from 4 to 10 percent, of the national total by the end of this century. In general, the growth potential for DSG seems favorable in the long term because of finite fossil energy resources and increasing fuel prices. Recent trends, especially in the institutional and regulatory fields, favor greater use of the DSGs for the future.

Source record↗
NASA NTRS1981

Comparisons of global ozone trends inferred from the BUV experiment on Nimbus 4 and the ground-based network

Preliminary comparisons between global ozone burdens derived from the backscattered ultraviolet (BUV) experiment on Nimbus 4 and those inferred from an analysis of ground-based network data seem to indicate significant differences in the inter-annual variability of ozone. Some of the observed differences may be due to improper weighting of the ground-based network data, slowly changing planetary wave structure over the fixed station, of small inter-annual changes in meridional transport parameters. There is also some evidence which indicates that the polar stratosphere at high latitudes may represent an important ozone storage resevoir which tends to compensate for large scale changes observed in the regions outside of the polar stratosphere. Possible consequences of this are that the global trends derived from ground based ozone measurements may not be valid and furthermore that the current satellite techniques by themselves may be sufficient. An ozone monitoring system which includes observations from satellites, ground-based stations, balloons and rockets may be necessary.

Heath, D. F.↗
NASA NTRS1981

Aviation turbine fuel properties and their trends

Fuel property values and their trends were studied through a review of a recognized, wide ranging sample population from actual fuel inspection data. A total of 676 fuel samples of Jet A aviation turbine fuel were compiled over an eleven year period. Results indicate that most fuel samples have one to three near-specification properties, the most common being aromatics, smoke point, and freezing point.

Friedman, R.↗
NASA NTRS1980

A comparison of fractionation trends in the lunar crust and the Stillwater complex

Trends analogous to those of lunar highland samples are found in a plot of Mg/(Mg+Fe) in mafic minerals against the anorthosite content of coexisting plagioclase for the Stillwater complex. By applying the model derived from such data to lunar highland rocks, major element variations in the 'ferroan anorthosite' suite can be explained. It is concluded that the anorthositic suite may represent the original lunar crust, whereas the Mg-rich suite may have been derived from later high level intrusions.

Raedeke, L. D.↗
NASA NTRS1981

Estimation of trends

The application of statistical methods to recorded ozone measurements. The effects of a long term depletion of ozone at magnitudes predicted by the NAS is harmful to most forms of life. Empirical prewhitening filters the derivation of which is independent of the underlying physical mechanisms were analyzed. Statistical analysis performs a checks and balances effort. Time series filters variations into systematic and random parts, errors are uncorrelated, and significant phase lag dependencies are identified. The use of time series modeling to enhance the capability of detecting trends is discussed.

Source record↗
NASA NTRS1982

Advances and trends in plate buckling research

Advances and current trends in plate bucklin research are summarized. The field is divided into three parts: (1) classical buckling studies, including plates of rectangular, circular and other shapes; (2) classical complicating effects, including elastic foundation, anisotropic material, variable thickness, shear deformation and nonhomogeneous material; and (3) nonclassical considerations, including postbuckling, imperfections, parametric excitation, follower forces, magnetoelastic buckling and inelastic buckling.

Leissa, A.↗
NASA NTRS1981

Atmospheric methane /CH4/ - Trends and seasonal cycles

On the basis of 22 months of almost continuous automated, GC/FID measurements of atmospheric CH4 and Cape Meares (45 deg N), it is shown that the concentration of CH4 is increasing at about 2% per yr (+ or - 0.5%/yr). The data also revealed stable seasonal cycles with peak concentrations in October and minimum concentrations in July. The magnitude of the seasonal variations during these months is about + or - 20 ppby from the average (+ or - 1.2%). If the current trend continues, the increased CH4 concentration may result in a 0.2 K to 0.4 K average increase in earth's surface temperature over the next 40 years or so (based on calculations of Wang et al. (1976)). The coupling of CH4 to tropospheric and stratospheric chemical processes is discussed.

Rasmussen, R. A.↗
NASA NTRS1981

Aviation turbine fuel properties and their trends

This paper is an examination of published Jet A inspection data covering selected property distributions, averages, and trends for the period from 1969 to 1979. Yearly median values of aromatics, mercaptan sulfur content, 10-percent distillation temperature, smoke point, and freezing point are changing with time, approaching their specification limit values, particularly in the last three years. A near-specification property is defined as one within a stated tolerance band around the specification limit. On this basis, most fuel samples have one to three near-specification properties, the most common being aromatics, smoke point, and freezing point.

Friedman, R.↗
NASA NTRS1982

Global sea level trend in the past century

Data derived from tide-gauge stations throughout the world indicate that the mean sea level rose by about 12 centimeters in the past century. The sea level change has a high correlation with the trend of global surface air temperature. A large part of the sea level rise can be accounted for in terms of the thermal expansion of the upper layers of the ocean. The results also represent weak indirect evidence for a net melting of the continental ice sheets.

Gornitz, V.↗
NASA NTRS1982

Evaluation of the CEAS trend and monthly weather data models for soybean yields in Iowa, Illinois, and Indiana

The CEAS models evaluated use historic trend and meteorological and agroclimatic variables to forecast soybean yields in Iowa, Illinois, and Indiana. Indicators of yield reliability and current measures of modeled yield reliability were obtained from bootstrap tests on the end of season models. Indicators of yield reliability show that the state models are consistently better than the crop reporting district (CRD) models. One CRD model is especially poor. At the state level, the bias of each model is less than one half quintal/hectare. The standard deviation is between one and two quintals/hectare. The models are adequate in terms of coverage and are to a certain extent consistent with scientific knowledge. Timely yield estimates can be made during the growing season using truncated models. The models are easy to understand and use and are not costly to operate. Other than the specification of values used to determine evapotranspiration, the models are objective. Because the method of variable selection used in the model development is adequately documented, no evaluation can be made of the objectivity and cost of redevelopment of the model.

French, V.↗
NASA NTRS1982

Evaluation of Thompson-type trend and monthly weather data models for corn yields in Iowa, Illinois, and Indiana

An evaluation was made of Thompson-Type models which use trend terms (as a surrogate for technology), meteorological variables based on monthly average temperature, and total precipitation to forecast and estimate corn yields in Iowa, Illinois, and Indiana. Pooled and unpooled Thompson-type models were compared. Neither was found to be consistently superior to the other. Yield reliability indicators show that the models are of limited use for large area yield estimation. The models are objective and consistent with scientific knowledge. Timely yield forecasts and estimates can be made during the growing season by using normals or long range weather forecasts. The models are not costly to operate and are easy to use and understand. The model standard errors of prediction do not provide a useful current measure of modeled yield reliability.

French, V.↗
NASA NTRS1983

Trends in software reliability for digital flight control

Software error data of major recent Digital Flight Control Systems Development Programs. The report summarizes the data, compare these data with similar data from previous surveys and identifies trends and disciplines to improve software reliability.

Hecht, H.↗
NASA NTRS1983

Trends of Reynolds number effects on two-dimensional airfoil characteristics for helicopter rotor analyses

The primary effects of Reynolds number on two dimensional airfoil characteristics are discussed. Results from an extensive literature search reveal the manner in which the minimum drag and maximum lift are affected by the Reynolds number. C sub d sub min and C sub l sub max are plotted versus Reynolds number for airfoils of various thickness and camber. From the trends observed in the airfoil data, universal scaling laws and easily implemented methods are developed to account for Reynolds number effects in helicopter rotor analyses.

Yamauchi, G. K.↗
NASA NTRS1983

Weight trends for a fully reusable advanced single-stage shuttle

The rate at which subsystem weights grow with vehicle gross weight is assessed and is shown to be critical to the efficiency of large Earth to orbit transports. The overall trend, however, is a reduction in the inerts as a percentage of gross weight as the vehicle size is increased. For this reason, the larger the vehicle, the greater the payload weight delivered per pound of vehicle manufactured. Other critical issues addressed include the effects of wing loading and wing size on wing weight, the effect of entry planform loading on thermal protection system weight, the impact of power demand on cooling system and prime power weight, and tank fineness ratio on insulation weight. The effects of body shape and various internal packaging arrangements on weight and balance are also discussed. The greatest impact on overall vehicle weight is body shape and internal packaging, and could account for weight savings of up to 30 percent in body structure. Other subsystems are important, but the savings are much smaller in relation to overall vehicle weight--individually less than one percent.

Macconochie, I. O.↗