Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Real Data”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Projection of school district enrollments

The objectives were to provide a better statistical basis for enrollment projections, to attempt to model the school district's enrollment, and to produce a single estimate of enrollment for each grade, grade group, and ethnic group, and for the total by year. Efforts were also made to provide error estimates for the projections, to design a simple, user-oriented computer program for use by school district administrators, and to work with real data from local school districts and aid them in making projections on an experimental basis. The study at Jet Propulsion Laboratory was concerned with projection methodology and production of a generally usable computer program.

Van Dillen, S. L.↗
NASA NTRS1974

A Skylab program for the International Hydrological Decade (IHD)

The author has identified the following significant results. The development of the algorithm (using real data) relating red and IR reflectance to surface soil moisture over regions of variable vegetation cover will enable remote sensing to make direct inputs into determination of this important hydrologic parameter.

Polcyn, F. C.↗
NASA NTRS1976

Atmospheric analysis and prediction model development, volume 1

A set of hemispheric atmospheric analysis and prediction models was designed and tested. All programs were executed on either a 63 x 63 or 187 x 187 polar stereographic grid of the Northern Hemisphere. Parameters for objective analysis included sea surface temperature, sea level pressure, and twelve levels (from 1,000 to 100 millibars) of temperatures, heights, and winds. Stratospheric extensions (up to 10 millibars) were also provided. Four versions of a complex atmospheric prediction model, based on primitive equations, were programmed and tested. These models were executed on either the 63 x 63 or 187 x 187 grid, using either five or ten computational layers. The coarse-mesh (63 x 63) models were tested using real data for the period 21-23 April 1976. The fine-mesh (187 x 187) models were debugged, but insufficient computer resources precluded production tests. Preliminary test results for the 63 x 63 models are provided. Problem areas and proposed solutions are discussed.

Kesel, P. G.↗
NASA NTRS1976

Computer-aided analysis of CCD linear image sensors

Special test equipment and techniques to collect and process image information from charge coupled devices (CCDs) by digital computer were reviewed. The video channel was traced from the CCD to the direct memory access bus of the Interdata Computer. Software was developed to evaluate and characterize a CCD for (1) dark signal versus temperature relationship, (2) calculation of temporal noise magnitude and noise shape for each pixel, (3) spatial noise into the video chain due to dark signal, (4) response versus illumination relationship (gamma), (5) response versus wavelength of illumination (spectral), (6) optimization of forcing functions, and (7) evaluation of an image viewed by a CCD. The basic software differences and specific examples of each program operating on real data are presented.

Prince, S. S.↗
NASA NTRS1976

Reference orbits from range and Doppler observations

The paper is concerned with the height accuracy of reference orbits obtained by a system composed of one laser and three Doppler stations. It is thought that reference orbits obtained by this system could be used for altimeter evaluation, although height errors increased up to 50% over those from the orbits with four lasers. Simulation studies and real data results are analyzed, and the implications for the GEOS-3 project are considered.

Berbert, J.↗
NASA NTRS1979

Sensitivity of Forecast Skill to Different Objective Analysis Schemes

Numerical weather forecasts are characterized by rapidly declining skill in the first 48 to 72 h. Recent estimates of the sources of forecast error indicate that the inaccurate specification of the initial conditions contributes substantially to this error. The sensitivity of the forecast skill to the initial conditions is examined by comparing a set of real-data experiments whose initial data were obtained with two different analysis schemes. Results are presented to emphasize the importance of the objective analysis techniques used in the assimilation of observational data.

Baker, W. E.↗
NASA NTRS1979

Mathematic modeling of the Earth's surface and the process of remote sensing

It is shown that real data from remote sensing of the Earth from outer space are not best suited to the search for optimal procedures with which to process such data. To work out the procedures, it was proposed that data synthesized with the help of mathematical modeling be used. A criterion for simularity to reality was formulated. The basic principles for constructing methods for modeling the data from remote sensing are recommended. A concrete method is formulated for modeling a complete cycle of radiation transformations in remote sensing. A computer program is described which realizes the proposed method. Some results from calculations are presented which show that the method satisfies the requirements imposed on it.

Balter, B. M.↗
NASA NTRS1978

The augmentation algorithm and molecular phylogenetic trees

Moore's (1977) augmentation procedure is discussed, and it is concluded that the procedure is valid for obtaining estimates of the total number of fixed nucleotide substitutions both theoretically and in practice, for both simulated and real data, and in agreement, for experimentally dense data sets, with stochastic estimates of the divergence, provided the restrictions on codon mutability resulting from natural selection are explicitly allowed for. Tateno and Nei's (1978) critique that the augmentation procedure has a systematic bias toward overestimation of the total number of nucleotide replacements is disputed, and a data analysis suggests that ancestral sequences inferred by the method of parsimony contain a large number of incorrectly assigned nucleotides.

Holmquist, R.↗
NASA NTRS1979

On the simulation of the oceanic general circulation

Two global ocean simulations based on the physics of a highly viscous ocean are discussed, one having realistic atmospheric functions for calculating the thermal forcing of the ocean. The velocity field of this model compares reasonably well with the relatively small amount of real data available. Temperature and heat budget components of the model reproduce best the equatorial band of heating. A simulation based upon the physics of a weakly viscous ocean is described, which produces the correct pattern of isotherms. This model has not yet been run to thermal equilibrium. The Gulf Stream and eddies and their influence on the oceanic and atmospheric heat budgets are discussed in the terms of their importance in coupled ocean-atmosphere models.

Mintz, Y.↗
NASA NTRS1978

Treatment of cloudiness in regional scale - Numerical weather prediction models

A numerical weather prediction model is considered in which cloud water and precipitation are explicitly predicted as functions of three space dimensions and time. Approximations in the thermodynamic and continuity equations are discussed in detail, as well as the cumulus parameterization and the cloud microphysics parameterization. An example of a real-data forecast indicates that very accurate quantitative precipitation and cloud cover forecasts are possible using initial observations from only the relatively sparse rawinsonde network in the U.S.

Kreitzberg, C. W.↗
NASA NTRS1980

Semi-empirical estimates of gravitational wave generation by stellar collapse

The problems of the generation and detection of gravitational waves and the difficulty of detecting the burst of gravitational radiation produced by a stellar collapse in our Galaxy, or in neighbouring clusters of galaxies where such collapses are expected to occur frequently, have been reviewed elsewhere. As stellar collapses, explosions, or supernovae are poorly understood, the values of the strength of these sources depend on uncertain assumptions. However, it is possible to make some independent estimates on semi-empirical grounds, using observed facts concerning the remnants of stellar evolution. These estimates, reported here, have serious weaknesses. They must involve oversimplified models and very crude standard calculations of the collapse and radiation processes. Also, because they are based on observed properties of stellar remnants, they say nothing about collapses which do not produce observable remnants. Although this selection may introduce a strong bias, these estimates deserve consideration because they are tied to real data.

Katz, J. I.↗
NASA NTRS1980

Formulation and implementation of a practical algorithm for parameter estimation with process and measurement noise

A new formulation is proposed for the problem of parameter estimation of dynamic systems with both process and measurement noise. The formulation gives estimates that are maximum likelihood asymptotically in time. The means used to overcome the difficulties encountered by previous formulations are discussed. It is then shown how the proposed formulation can be efficiently implemented in a computer program. A computer program using the proposed formulation is available in a form suitable for routine application. Examples with simulated and real data are given to illustrate that the program works well.

Maine, R. E.↗
NASA NTRS1981

Large area application of a corn hazard model

An application test of the crop calendar portion of a corn (maize) stress indicator model developed by the early warning, crop condition assessment component of AgRISTARS was performed over the corn for grain producing regions of the U.S.S.R. during the 1980 crop year using real data. Performance of the crop calendar submodel was favorable; efficiency gains in meteorological data analysis time were on a magnitude of 85 to 90 percent.

Ashburn, P.↗
NASA NTRS1982

Report of the Subpanel on Error Characterization and Error Budgets

The state of knowledge of both user positioning requirements and error models of current and proposed satellite systems is reviewed. In particular the error analysis models for LANDSAT D are described. Recommendations are given concerning the geometric error model for the thematic mapper; interactive user involvement in system error budgeting and modeling and verification on real data sets; and the identification of a strawman mission for modeling key error sources.

Source record↗
NASA NTRS1981

Software for universal noiseless coding

An overview is provided of the universal noiseless coding algorithms as well as their relationship to the now available FORTRAN implementations. It is suggested that readers considering investigating the utility of these algorithms for actual applications should consult both NASA's Computer Software Management and Information Center (COSMIC) and descriptions of coding techniques provided by Rice (1979). Examples of applying these techniques have also been given by Rice (1975, 1979, 1980). Attention is given to reversible preprocessing, general implementation instructions, naming conventions, and calling arguments. A general applicability of the considered algorithms to solving practical problems is obtained because most real data sources can be simply transformed into the required form by appropriate preprocessing.

Rice, R. F.↗
NASA NTRS1982

Computer program to minimize prediction error in models from experiments with 16 hypercube points and 0 to 6 center points

A previous report described a backward deletion procedure of model selection that was optimized for minimum prediction error and which used a multiparameter combination of the F - distribution and an order statistics distribution of Cochran's. A computer program is described that applies the previously optimized procedure to real data. The use of the program is illustrated by examples.

Holms, A. G.↗
NASA NTRS1983

Simple energy balance model resolving the seasons and the continents - Application to the astronomical theory of the ice ages

An analysis is undertaken of the properties of a one-level seasonal energy balance climate model having explicit, two-dimensional land-sea geography, where land and sea surfaces are strictly distinguished by the local thermal inertia employed and transport is governed by a smooth, latitude-dependent diffusion mechanism. Solutions of the seasonal cycle for the cases of both ice feedback exclusion and inclusion yield good agreements with real data, using minimal turning of the adjustable parameters. Discontinuous icecap growth is noted for both a solar constant that is lower by a few percent and a change of orbital elements to favor cool Northern Hemisphere summers. This discontinuous sensitivity is discussed in the context of the Milankovitch theory of the ice ages, and the associated branch structure is shown to be analogous to the 'small ice cap' instability of simpler models.

North, G. R.↗
NASA NTRS1984

What's so Hot About Formulated Synthetics?

The development of synthetic automotive engine oil is discussed. The history of synthetic lubricants, and of the additives required to compete in a market which developed by and for petroleum oils. Some examples of real data, and enlarged using heat transfer properties obtained by chemical engineering thermodynamic methods are shown. The prospects for future successes and ideas on the additives that would most help to bring them about are also presented.

Beerbower, A.↗