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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 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

A comprehensive comparison between satellite-measured skin and multichannel sea surface temperature

Three algorithms for computing sea-surface temperature (SST) from AVHRR channel-4 and -5 brightness temperatures were compared using 1-week blocks of global-area-coverage (GAC) data archived at NCAR. These are the multichannel SST (MCSST), the cross-product SST (CPSST), and the AVHRR-only satellite-measured ocean-surface skin temperature (SMSST). Maps of each SST product were produced and were compared for various time periods. The difference between the algorithms range from +1.6 to -1.2 K, resulting from the different forms of both the algorithms and the ground truth from which the algorithms were derived. It is concluded that, for the study of relative SST patterns, any of the algorithms can be used. However, for applications requiring accurate absolute temperature measurements, the differences are significant and the derivation of the algorithm must be considered when an algorithm is selected.

Wick, Gary A.↗
NASA NTRS1991

A comprehensive mission to planet Earth: Woods Hole Space Science and Applications Advisory Committee Planning Workshop

The NASA program Mission to Planet Earth (MTPE) is described in this set of visuals presented in Massachusetts on July 29, 1991. The problem presented in this document is that the earth system is changing and that human activity accelerates the rate of change resulting in increased greenhouse gases, decreasing levels of stratospheric ozone, acid rain, deforestation, decreasing biodiversity, and overpopulation. Various national and international organizations are coordinating global change research. The complementary space observations for this activity are sun-synchronous polar orbits, low-inclination, low altitude orbits, geostationary orbits, and ground measurements. The Geostationary Earth Observatory is the major proposed mission of MTPE. Other proposed missions are EOS Synthetic Aperture Radar, ARISTOTELES Magnetic Field Experiment, and the Global Topography Mission. Use of the NASA DC-8 aircraft is outlined as carrying out the Airborne Science and Applications Program. Approved Earth Probes Program include the Total Ozone Mapping Spectrometer (TOMS). Other packages for earth observation are described.

Source record↗
NASA NTRS1992

A comprehensive comparison between skin and multi-channel sea surface temperatures as derived from AVHRR

Global maps of Satellite Measured Surface Skin Temperature (SMSST), MultiChannel Sea Surface Temperature (MCSST) and Cross Product Sea Surface Temperature (CPSSR) are computed from imagery of the Advanced Very High Resolution Radiometer (AVHRR) for five fortnights in 1984/85. They demonstrate systematic latitudinal variations and regional extremes of the differences with greatest root mean square values of 0.7K between MCSST and SMSST found at low latitudes. Mean differences range from 0.1K between CPSST and SMSST to 0.45K between MCSST and SMSST. A part of the differences might be attributed to the skin cooling at the sea surface. A parameterization of the bulk skin temperature difference is derived from in situ field measurements. This can be used to find a relation between satellite measured bulk and skin temperatures.

Schluessel, Peter↗
NASA NTRS1993

A comprehensive comparison of turbulence models in the far wake

In the present study, the far wake was examined numerically using an implicit, upwind, finite-volume, compressible Navier-Stokes code. The numerical grid started at 500 equivalent circular cylinder diameters in the wave, and extended to 4000 equivalent diameters. By concentrating only on the far wake, the numerical difficulties and fine mesh requirements near the wake-generating body were eliminated. At the time of this writing, results for the K-epsilon and K-omega turbulence models at low Mach number have been completed and show excellent agreement with previous incompressible results and far-wake similarity solutions. The code is presently being used to compare the performance of various other turbulence models, including Reynolds stress models and the new anisotropic two-equation turbulence models being developed at NASA Langley. By increasing our physical understanding of the deficiencies and limits of these models, it is hoped that improvements to the universality of the models can be made. Future plans include examination of two-dimensional momentumless wakes as well.

Cimbala, John M.↗
NASA NTRS1993

A comprehensive analysis of electron conical distributions from multi-satellite databases

This report consists of a copy of a paper that has been submitted to the 'Journal of Geophysical Research', entitled 'DE 1 and Viking Observations Associated With Electron Conical Distributions,' and an abstract of another paper (included as an appendix to the report) that is about to be submitted to the same journal entitled 'Perpendicular Electron Heating by Absorption of Auroral Kilometric Radiation.' A bibliography of other papers that have been published as a result of this project follows. The purpose of this project was to use the DE 1 and Viking particle and wave data to better understand the source mechanism of electron conical distributions. We have shown that electron conics are often associated with upper hybrid waves in the nightside auroral region. We have also shown that electron conics are observed near auroral kilometric radiation (AKR) source regions and may be the result of perpendicular heating due to waves. We have completed a statistical study of electron conics observed by DE-l and Viking. The study shows the occurrence frequency and location of electron conical distributions; there are some differences between the results of DE and Viking perhaps due to different regions sampled.

Menietti, J. Douglas↗
NASA NTRS1993

Comprehensive investigation of HgCdTe metalorganic chemical vapor deposition

The principal objective of this experimental and theoretical research program was to explore the possibility of depositing high quality epitaxial CdTe and HgCdTe at very low pressures through metalorganic chemical vapor deposition (MOCVD). We explored two important aspects of this potential process: (1) the interaction of molecular flow transport and deposition in an MOCVD reactor with a commercial configuration, and (2) the kinetics of metal alkyl source gas adsorption, decomposition and desorption from the growing film surface using ultra high vacuum surface science reaction techniques. To explore the transport-reaction issue, we have developed a reaction engineering analysis of a multiple wafer-in-tube ultrahigh vacuum chemical vapor deposition (UHV/CVD) reactor which allows an estimate of wafer or substrate throughput for a reactor of fixed geometry and a given deposition chemistry with specified film thickness uniformity constraints. The model employs a description of ballistic transport and reaction based on the pseudo-steady approximation to the Boltzmann equation in the limit of pure molecular flow. The model representation takes the form of an integral equation for the flux of each reactant or intermediate species to the wafer surfaces. Expressions for the reactive sticking coefficients (RSC) for each species must be incorporated in the term which represents reemission from a wafer surface. The interactions of MOCVD precursors with Si and CdTe were investigated using temperature programmed desorption (TPD) in ultra high vacuum combined with Auger electron spectroscopy (AES). These studies revealed that diethyltellurium (DETe) and dimethylcadmium (DMCd) adsorb weakly on clean Si(100) and desorb upon heating without decomposing. These precursors adsorb both weakly and strongly on CdTe(111)A, with DMCd exhibiting the stronger interaction with the surface than DETe.

Raupp, Gregory B.↗
NASA NTRS1994

Tropospheric ozone in the western Pacific Rim: Analysis of satellite and surface-based observations along with comprehensive 3-D model simulations

Tropospheric ozone production and transport in mid-latitude eastern Asia is studied. Data analysis of surface-based ozone measurements in Japan and satellite-based tropospheric column measurements of the entire western Pacific Rim are combined with results from three-dimensional model simulations to investigate the diurnal, seasonal and long-term variations of ozone in this region. Surface ozone measurements from Japan show distinct seasonal variation with a spring peak and summer minimum. Satellite studies of the entire tropospheric column of ozone show high concentrations in both the spring and summer seasons. Finally, preliminary model simulation studies show good agreement with observed values.

Young, Sun-Woo↗
NASA NTRS1994

SEQ-GEN: A comprehensive multimission sequencing system

SEQ-GEN is a user-interactive computer program used to plan and generate a sequence of commands for spacecraft. Desired activities are specified by the user of SEQ-GEN; SEQ-GEN in turn expands these activities, deriving the spacecraft commands necessary to accomplish the desired activities. SEQ-GEN models the effects on the spacecraft of the commands, predicting the state as a function of time, flagging any conflicts and rule violations. These states, conflicts, and violations are viewable both graphically and textually at the user's request. SEQ-GEN also displays the entire sequence graphically, showing each requested activity as a bar on its graphical timeline. SEQ-GEN immediately revalidates the sequence, updating its models and calculations along with its displays based on these changes. Because it has the ability to recalculate spacecraft states immediately, the user is able to perform 'what-if' sessions easily. SEQ-GEN, a multimission tool, is adaptable to any flight project. A flight project writes its adaptation files containing project unique information including in its simplest form, only spacecraft commands. For more involved projects the adaptation files may also contain flight and mission rules, description of the spacecraft and ground models, and the definition of activities. SEQ-GEN operates at whatever level of detail the adaptation files imply. Simple adaptations are straight forward to do. There is, however, no limit to the complexity of activity definitions or of spacecraft models: both may involve unlimited logical decision points. Commands and activities may involve any number of parameters of a wide variety of data types, including integer, float, time, boolean, and character strings. SEQ-GEN will be used by the Mars Pathfinder, Cassini, and VIM (Voyager Interstellar Mission) project in an effort to speed up adaptation time and to keep sequence generation costs down. SEQ-GEN is hosted on UNIX workstations. It uses MOTIF and X for windowing, and was designed and coded in an object-oriented style in the language C++.

Salcedo, Jose↗
NASA NTRS1994

Neural network application to comprehensive engine diagnostics

We have previously reported on the use of neural networks for detection and identification of faults in complex microprocessor controlled powertrain systems. The data analyzed in those studies consisted of the full spectrum of signals passing between the engine and the real-time microprocessor controller. The specific task of the classification system was to classify system operation as nominal or abnormal and to identify the fault present. The primary concern in earlier work was the identification of faults, in sensors or actuators in the powertrain system as it was exercised over its full operating range. The use of data from a variety of sources, each contributing some potentially useful information to the classification task, is commonly referred to as sensor fusion and typifies the type of problems successfully addressed using neural networks. In this work we explore the application of neural networks to a different diagnostic problem, the diagnosis of faults in newly manufactured engines and the utility of neural networks for process control.

Marko, Kenneth A.↗
NASA NTRS1995

The spacelab scientific missions: A comprehensive bibliography of scientific publications

November 1993 represented the 10-year anniversary of the flight of Spacelab 1 mission, with the first precursor mission (OSTA-1) being launched 2 years earlier. Since that time, a total of 27 Shuttle missions has been flown, using the Spacelab system as a facility for conducting scientific research in space. The missions flown to date have allowed a total of approximately 500 Principle Investigator class investigations to be conducted in orbit. These investigations have constituted major scientific efforts in astronomy/astrophysics, atmospheric science, Earth observation, life sciences, microgravity science, and space plasma physics. An initial survey of the scientific products gleaned from Spacelab missions already flown was sent to the Principle Investigators. In that survey, information was gathered from the investigators on the scientific highlights of their investigations and statistical measurements of overall success -- such as papers published. This document is a compilation of the papers that have been published to date in referred literature.

Torr, Marsha↗
NASA NTRS1994

Comprehensive stellar population models and the disentanglement of age and metallicity effects

The construction of detailed models for intermediate and old stellar populations is described. Input parameters include metallicity (-2 less than (Fe/H) less than 0.5), single-burst age (between 1.5 and 17 Gyr), and initial mass function (IMF) exponent. Quantities output include broadband magnitudes, spectral energy distributions, surface brightness fluctuation magnitudes, and a suite of 21 absorption feature indices. The models are checked against a wide variety of available observations. Examinations of model output yield the following conclusions. (1) If the percentage change delta age/delta Z approximately equals 3/2 for two populations, they will appear almost identical in most indices. A few indices break this degeneracy by being either more abundance sensitive (Fe4668, Fe5015, Fe5709, and Fe5782) or more age sensitive (G4300, H beta, and presumably higher order Balmer lines) than usual. (2) Present uncertainties in stellar evolution are of the same magnitude as the effects of IMF and Y in the indices studied. (3) Changes in abundance ratios (like (Mg/Fe)) are predicted to be readily apparent in the spectra of old stellar populations. (4) The I-band flux of a stellar population is predicted to be nearly independent of metallicity and only modestly sensitive to age. The I band is therefore recommended for standard candle work or studies of M/L in galaxies. Other conclusions stem from this work. (1) Intercomparison of models and observations of two TiO indices seem to indicate variation of the (V/Ti) ratio among galaxies, but it is not clear how this observation ties into the standard picture of chemical enrichment. (2) Current estimates of (Fe/H) for the most metal-rich globulars that are based on integrated indices are probably slightly too high. (3) Colors of population models from different authors exhibit a substantial range. At solar metallicity and 13 Gyr, this range corresponds to an age error of roughly +/- 7 Gyr. Model colors from different authors applied in a differential sense have smaller uncertainties. (4) In the present models the dominant error for colors is probably the transformation from stellar atmospheric parameters to stellar colors. (5) Stellar B - V is difficult to model, and current spreads among different authors can reach 0.2 mag. (6) If known defects in the stellar flux library are corrected, the population model colors of this work in passbands redder than U would be accurate to roughly 0.03 mag in an absolute sense. These corrections are not made in the tables of model output.

Worthey, Guy↗
NASA NTRS1996

A Comprehensive and Cost-Effective Computer Infrastructure for K-12 Schools

Since 1993, NASA Langley Research Center has been developing and implementing a low-cost Internet connection model, including system architecture, training, and support, to provide Internet access for an entire network of computers. This infrastructure allows local area networks which exceed 50 machines per school to independently access the complete functionality of the Internet by connecting to a central site, using state-of-the-art commercial modem technology, through a single standard telephone line. By locating high-cost resources at this central site and sharing these resources and their costs among the school districts throughout a region, a practical, efficient, and affordable infrastructure for providing scale-able Internet connectivity has been developed. As the demand for faster Internet access grows, the model has a simple expansion path that eliminates the need to replace major system components and re-train personnel. Observations of optical Internet usage within an environment, particularly school classrooms, have shown that after an initial period of 'surfing,' the Internet traffic becomes repetitive. By automatically storing requested Internet information on a high-capacity networked disk drive at the local site (network based disk caching), then updating this information only when it changes, well over 80 percent of the Internet traffic that leaves a location can be eliminated by retrieving the information from the local disk cache.

Warren, G. P.↗
NASA NTRS1996

Comprehensive Mathematical Model Of Real Fluids

Mathematical model of thermodynamic properties of water, steam, and liquid and gaseous hydrogen and oxygen developed for use in computational simulations of flows of mass and heat in main engine of space shuttle. Similar models developed for other fluids and applications. Based on HBMS equation of state.

Anderson, Peter G.↗
NASA NTRS1995

A Comprehensive Approach to Management of Workplace and Environmental Noise at NASA Lewis Research Center

NASA Lewis Research Center is home to more than 100 experimental research testing facilities and laboratories, including large wind tunnels and engine test cells, which in combination create a varied and complex noise environment. Much of the equipment was manufactured prior to the enactment of legislation limiting product noise emissions or occupational noise exposure. Routine facility maintenance and associated construction also contributes to a noise exposure management responsibility which is equal in magnitude and scope to that of several small industrial companies. The Noise Program, centrally managed within the Office of Environmental Programs at LRC, maintains overall responsibility for hearing conservation, community noise control, and acoustical and noise control engineering. Centralized management of the LRC Noise Program facilitates the timely development and implementation of engineered noise control solutions for problems identified via either the Hearing Conservation of Community Noise Program. The key element of the Lewis Research Center Noise Program, Acoustical and Noise Control Engineering Services, is focused on developing solutions that permanently reduce employee and community noise exposure and maximize research productivity by reducing or eliminating administrative and operational controls and by improving the safety and comfort of the work environment. The Hearing Conservation Program provides noise exposure assessment, medical monitoring, and training for civil servant and contractor employees. The Community Noise Program aims to maintain the support of LRC's neighboring communities while enabling necessary research operations to accomplish their programmatic goals. Noise control engineering capability resides within the Noise Program. The noise control engineering, based on specific exposure limits, is a fundamental consideration throughout the design phase of new test facilities, labs, and office buildings. In summary, the Noise Program addresses hearing conservation, community noise control, and acoustical and noise control engineering.

Cooper, Beth A.↗
NASA NTRS1997

Comprehensive Analyses of Data Collected from TEREK (Solar EUV Telescope) RES-C (Solar X-Ray Spectrometer) and SORS (Solar Radio Spectrometer) on board CORONAS-1 Using Magnetohydrodynamic Models

By using the observed magnetic field data obtained from the Wilcox Solar Observatory at Stanford University as the inputs to a two-dimensional plane-of-sky magnetohydrodynamic model, via numerical relaxation method, we have deduced the plasma and magnetic field parameters for the observed coronal hole by CORONAS-1. The method for this self-consistent MHD analysis will be discussed in detail. Numerical results for the magnetic field configuration, velocity distribution, density and temperature distributions will be presented. We have converted the computed density to polarization brightness in order to directly compare the MHD outputs with observations. Also included is a summary of achievements made during the grant period. This section is summarized into three categories: 1) Visit of Co-Investigators; 2) Presentations; and 3) Papers published, accepted and submitted for publication in journals.

Wu, S. T.↗
NASA NTRS1997

Enhanced Multiobjective Optimization Technique for Comprehensive Aerospace Design

A multidisciplinary design optimization procedure which couples formal multiobjectives based techniques and complex analysis procedures (such as computational fluid dynamics (CFD) codes) developed. The procedure has been demonstrated on a specific high speed flow application involving aerodynamics and acoustics (sonic boom minimization). In order to account for multiple design objectives arising from complex performance requirements, multiobjective formulation techniques are used to formulate the optimization problem. Techniques to enhance the existing Kreisselmeier-Steinhauser (K-S) function multiobjective formulation approach have been developed. The K-S function procedure used in the proposed work transforms a constrained multiple objective functions problem into an unconstrained problem which then is solved using the Broyden-Fletcher-Goldfarb-Shanno (BFGS) algorithm. Weight factors are introduced during the transformation process to each objective function. This enhanced procedure will provide the designer the capability to emphasize specific design objectives during the optimization process. The demonstration of the procedure utilizes a computational Fluid dynamics (CFD) code which solves the three-dimensional parabolized Navier-Stokes (PNS) equations for the flow field along with an appropriate sonic boom evaluation procedure thus introducing both aerodynamic performance as well as sonic boom as the design objectives to be optimized simultaneously. Sensitivity analysis is performed using a discrete differentiation approach. An approximation technique has been used within the optimizer to improve the overall computational efficiency of the procedure in order to make it suitable for design applications in an industrial setting.

Chattopadhyay, Aditi↗
NASA NTRS1997

Comprehensive evaluation of attitude and orbit estimation using real earth magnetic field data

A single, augmented extended Kalman filter (EKF) which simultaneously and autonomously estimates spacecraft attitude and orbit was developed and tested with simulated and real magnetometer and rate data. Since the earth's magnetic field is a function of time and position, and since time is accurately known, the differences between the computed and measured magnetic field components, as measured by the magnetometers throughout the entire spacecraft's orbit, are a function of orbit and attitude errors. These differences can be used to estimate the orbit and attitude. The test results of the EKF with magnetometer and gyro data from three NASA satellites are presented and evaluated.

Deutschmann, Julie↗
NASA NTRS1997

A Comprehensive Opacities/Atomic Database for the Analysis of Astrophysical Spectra and Modeling

The main goals of this ADP award have been accomplished. The electronic database TOPBASE, consisting of the large volume of atomic data from the Opacity Project, has been installed and is operative at a NASA site at the Laboratory for High Energy Astrophysics Science Research Center (HEASRC) at the Goddard Space Flight Center. The database will be continually maintained and updated by the PI and collaborators. TOPBASE is publicly accessible from IP: topbase.gsfc.nasa.gov. During the last six months (since the previous progress report), considerable work has been carried out to: (1) put in the new data for low ionization stages of iron: Fe I - V, beginning with Fe II, (2) high-energy photoionization cross sections computed by Dr. Hong Lin Zhang (consultant on the Project) were 'merged' with the current Opacity Project data and input into TOPbase; (3) plans laid out for a further extension of TOPbase to include TIPbase, the database for collisional data to complement the radiative data in TOPbase.

Pradhan, Anil K.↗