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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Simmer-enhanced flashlamp-pumped dye laser

It has been demonstrated experimentally that by enhancing the simmer current in the flash lamps before the energy discharge, the lamp inductance is reduced and the dye laser efficiency is thus remarkably improved. This technique has advantages over the prepulsing technique for conditioning flash lamps; the electronic circuit for the simmer enhancement is simple, inexpensive and reliable, and accurate timing is not required. Furthermore, the simmer enhancement consumes much less power, thus minimizing the attendant thermal effects and improving overall laser efficiency.

Yee, T. K.↗
NASA NTRS1981

Real-time digital image enhancement

A programmable system for enhancing monocular and stereographic images at video rates is presented. The system provides both automatic and interactive enhancement modes based on histogram modification and intensity mapping techniques. Experimental results which illustrate enhancement capabilities under a variety of scene types and conditions are described.

Woods, R. E.↗
NASA NTRS1981

Enhancement of Far Field Sound Levels by Refractive Focusing

The enhancement of sound pressure levels resulting from refractive focusing was calculated for meteorological conditions representative of those observed at the MOD-1 site near Boone, N.C. The results show that 10 to 20dB enhancements can occur over ranges of several hundred meters. Localized enhancements in excess of 20dB can occur but will probably be of limited duration as a consequence of normal temporally varying meteorological conditions.

Thomson, D. W.↗
NASA NTRS1980

Applications of the TIROS-N sounding and cloud motion wind enhancement for the FGGE 'special effort'

In January of 1978, a panel of experts recommended that a 'special effort' be made to enhance and edit satellite soundings and cloud tracked winds in data sparse regions. It was felt that these activities would be necessary to obtain maximum benefits from an evaluation of satellite data during the Global Weather Experiment (FGGE). The 'special effort' is being conducted for the two special observing periods of FGGE. More than sixty cases have been selected for enhancement on the basis of meteorological interest. These cases include situations of blocking, cutoff low development, cyclogenesis, and tropical circulations. The sounding data enhancement process consists of supplementing the operational satellite sounding data set with higher resolution soundings in meteorologically active regions, and with new soundings where data voids or soundings of questionable quality exist.

Atlas, R.↗
NASA NTRS1982

Evaluation of photographic enhancements of Landsat imagery

The photographic processing of color Landsat imagery was evaluated to determine the optimal enhancement techniques. Twenty-six images were examined to explore the effects of gamma values upon image interpretation in a subarctic environment. Gamma values were varied on the images of bands 4 through 7 prior to the creation of the color composites. This yielded color-composited images with various color balances. These images were evaluated in terms of visible geological features (drainage, lineaments, landforms, etc.) and landcover features (exposed rock and ground, coniferous forest, etc.). The results indicate that the most informative images are created by using gamma values of 2.0 for band 4, 1.0 for band 5, and 2.0 for band 6 or 7. Other photographic enhancements tend to enhance some features at the expense of others.

Dean, K. G.↗
NASA NTRS1983

Androgens enhance in vivo 2-deoxyglucose uptake by rat striated muscle

It is shown that testosterone propionate (TP) causes a striking increase in the in vivo uptake of 2-deoxyglucose (2-DG) by the levator ani muscle of immature male rats, which was found to be uniformly distributed over the entire muscle. After a single subcutaneous injection of TP, no enhancement of 2-DG was observed before 3.5 hr, at which time uptake was increased 2-fold; maximum enhancement (4-fold) was attained at 12 hr. At 72 hr, 2-DG uptake remained elevated at twice the control value. It was determined that the effect of TP probably is mediated by specific androgen receptors. In addition, it was found that the effect of TP was blocked by the simultaneous administration of an androgen antagonist, cyproterone acetate. TP also was found to enhance the uptake of 2-DG in the bulbocavernosus (253 percent over control) and extensor digitorum longus muscles (150 percent over control), but not in the biceps brachii or soleus. It is suggested that the increased uptake of glucose may be an important early step in the anabolic response of muscle to androgens.

Max, S. R.↗
NASA NTRS1982

Enhanced diffusion of phosphorus at grain boundaries

Enhanced diffusion of phosphorus at grain boundaries in cast polycrystalline photovoltaic materials (Wacker, HEM, and Semix) was studied. It was found that the enhancements for the three materials were the same, indicating that the properties of boundaries are similar, even though they were grown by different techniques. In addition, it was observed that grain boundaries capable of enhancing the diffusion always have strong recombination activities. Both phenomena could be related to dangling bonds existing at the boundaries. The present study gives the first evidence that incoherent second order twins of 111/115-plane type are diffusion-active.

Cheng, L. J.↗
NASA NTRS1984

Substrate orientation dependence of enhanced epitaxial regrowth of silicon

This work extends the study of dopant-enhanced epitaxial regrowth rate of amorphized Si from the 100 to the 110 and 111 line orientations of Si. Boron and phosphorus dopants are considered. The annealing temperatures are 500 and 550 C. Phosphorus enhances the growth rates in all three orientations by a constant factor of 8.1 + or - 0.9. Boron produces a higher enhancement factor of 12.2 + or - 1.2, except in the case of 100. Implications of the results on various growth models are considered. The crystalline quality of regrown 111 layers is improved in the doped samples.

Ho, K. T.↗
NASA NTRS1985

New Enhancements in April 85 NASTRAN Release

Several features were added to COSMIC NASTRAN, along with some enhancements to improve or update existing capabilities. Most of these additions and enhancements were provided by industry users to be incorporated into NASTRAN for wider use. DIAG 48 provides a synopsis of significant developments in past NASTRAN releases (1983-1985) and indexes all diagnostic output messages and operation requests (DOMOR). Other features include: volume and surface computation of the 2-D and 3-D elements, NOLIN5 input and; NASTRAN PLOTOPT-N (where N = 2, 3, 4, or 5); shrink element plots; and output scan. A nonprint option on stress and force output request cards was added. Automated find and nofind options on the plot card, fully stressed design, high level plate elements, eigenvalue messages, and upgrading of all FORTRAN source code to the ANSI standard are enhancements made.

Chan, G. C.↗
NASA NTRS1986

Evaluation of the usefulness of various simulation technology options for TERPS enhancement

Current approved terminal instrument procedures (TERPS) do not permit the full exploitation of the helicopter's unique flying characteristics. Enhanced TERPS need to be developed for a host of non-standard landing sites and navigation aids. Precision navigation systems such as microwave landing systems (MLS) and the Global Positioning System (GPS) open the possibility of curved paths, steep glide slopes, and decelerating helicopter approaches. This study evaluated the feasibility, benefits, and liabilities of using helicopter cockpit simulators in place of flight testing to develop enhanced TERPS criteria for non-standard flight profiles and navigation equipment. Near-term (2 to 5 year) requirements for conducting simulator studies to verify that they produce suitable data comparable to that obtained from previous flight tests are discussed. The long-term (5 to 10 year) research and development requirements to provide necessary modeling for continued simulator-based testing to develop enhanced TERPS criteria are also outlined.

Phatak, A. V.↗
NASA NTRS1987

Color enhancement of highly correlated images. II - Channel ratio and 'chromaticity' transformation techniques

Two techniques for enhancing the color of multispectral images are described; both involve ratioing of data from different image channels. In the first technique, the ratioed data are assigned the primary color for display as color ratio pictures, and in the second method, image data are transformed to RGB chromaticity coordinates by ratioing the data acquired in three channels to the sum of their intensities. The two techniques are applied to a NASA Thermal-IR Multispectral Scanner (TIMS) image of Death Valley and to a Landsat MSS image of the Mojave Desert. The basic principles of ratioing are discussed, and the effects of atmospheric path radiances on the interpretation of ratioed images are investigated. It is observed that the color pictures produced using these two enhancement techniques are similar to the pictures enhanced by decorrelation and hue-saturation-intensity methods.

Gillespie, Alan R.↗
NASA NTRS1987

Visual enhancements in pick-and-place tasks - Human operators controlling a simulated cylindrical manipulator

A teleoperation simulator has been constructed with vector display system, joysticks, and a simulated cylindrical manipulator, in order to quantitatively evaluate various display conditions. The first of two experiments thus conducted investigated the effects of perspective parameter variations on human operators' pick-and-place performance, using a monoscopic perspective display. The second experiment involved visual enhancements of the monoscopic perspective display, by adding a grid and reference lines, by comparison with visual enhancements of a stereoscopic display; results indicate that stereoscopy generally permits superior pick-and-place performance, but that monoscopy nevertheless allows equivalent performance when defined with appropriate perspective parameter values and adequate visual enhancements.

Kim, Won S.↗
NASA NTRS1988

Digital processing of orbital radar data to enhance geologic structure - Examples from the Canadian Shield

Various digital enhancement techniques for SAR are compared using SIR-B and Seasat images of the Canadian Shield. The three best methods for enhancing geological structure were found to be: (1) a simple linear contrast stretch; (2) a mean or median low-pass filter to reduce speckle prior to edge enhancement or a K nearest-neighbor average to cosmetically reduce speckle; and (3) a modification of the Moore-Waltz (1983) technique. Three look directions were coregistered and several means of data display were investigated as means of compensating for radar azimuth biasing.

Masuoka, Penny M.↗
NASA NTRS1987

Investigation of the enhanced spatial density of submicron lunar ejecta between L values 1.2 and 3.0 in the earth's magnetosphere: Theory

Initial results from the measurement conducted by the dust particle experiment on the lunar orbiting satellite Lunar Explorer 35 (LE 35) were reported with the data interpreted as indicating that the moon is a significant source of micrometeroids. Primary sporadic and stream meteoroids impacting the surface of the moon at hypervelocity was proposed as the source of micron and submicron particles that leave the lunar craters with velocities sufficient to escape the moon's gravitational sphere of influence. No enhanced flux of lunar ejecta with masses greater than a nanogram was detected by LE 35 or the Lunar Orbiters. Hypervelocity meteoroid simulation experiments concentrating on ejecta production combined with extensive analyses of the orbital dynamics of micron and submicron lunar ejecta in selenocentric, cislunar, and geocentric space have shown that a pulse of these lunar ejecta, with a time correlation relative to the position of the moon relative to the earth, intercepts the earth's magnetopause surface (EMPs). As shown, a strong reason exists for expecting a significant enhancement of submicron dust particles in the region of the magnetosphere between L values of 1.2 and 3.0. This is the basis for the proposal of a series of experiments to investigate the enhancement or even trapping of submicron lunar ejecta in this region. The subsequent interaction of this mass with the upper-lower atmosphere of the earth and possible geophysical effects can then be studied.

Alexander, W. M.↗
NASA NTRS1989

Visual enhancements in pick-and-place tasks: Human operators controlling a simulated cylindrical manipulator

A teleoperation simulator was constructed with vector display system, joysticks, and a simulated cylindrical manipulator, in order to quantitatively evaluate various display conditions. The first of two experiments conducted investigated the effects of perspective parameter variations on human operators' pick-and-place performance, using a monoscopic perspective display. The second experiment involved visual enhancements of the monoscopic perspective display, by adding a grid and reference lines, by comparison with visual enhancements of a stereoscopic display; results indicate that stereoscopy generally permits superior pick-and-place performance, but that monoscopy nevertheless allows equivalent performance when defined with appropriate perspective parameter values and adequate visual enhancements.

Kim, Won S.↗
NASA NTRS1990

Electron collection enhancement arising from neutral gas jets on a charged vehicle in the ionosphere

Observations of current collection enhancements due to cold nitrogen gas control jet emissions from a highly charged, isolated rocket payload in the ionosphere have been made during the cooperative high altitude rocket gun experiment (CHARGE) 2 using an electrically tethered mother/daughter payload system. The current collection enhancement was observed on a platform (daughter payload) located 100 to 400 m away from the main payload firing an energetic electron beam (mother payload). These results are interpreted in terms of an electrical discharge forming in close proximity to the daughter vehicle during the short periods of gas emission. The results indicate that it is possible to enhance the electron current collection capability of positively charged vehicles by means of deliberate neutral gas releases into an otherwise undisturbed space plasma. The results are also compared with recent laboratory observations of hollow cathode plasma contactors operating in the 'ignited' mode.

Gilchrist, Brian E.↗
NASA NTRS1989

Large-scale transport of a CO-enhanced air mass from Europe to the Middle East

On November 14, 1981, the shuttle-borne Measurement of Air Pollution from Satellites (MAPS) experiment observed a carbon monoxide (CO) enhanced air mass in the middle troposphere over the Middle East. The primary source of this polluted air was estimated by constructing adiabatic isentropic trajectories backwards from the MAPS measurement location over a 36 h period. The isentropic diagnostics indicate that CO-enhanced air was transported southeastward over the Mediterranean from an organized synoptic-scale weather regime, albeit of moderate intensity, influencing central Europe on November 12. Examination of the evolving synoptic scale vertical velocity and precipitation patterns during this period, in conjuction with Meteosat visible, infrared, and water vapor imagery, suggests that the presence of this disturbed weather system over Europe may have created upward transport of CO-enhanced air between the boundary-layer and midtropospheric levels, and subsequent entrainment in the large-scale northwesterly jet stream flow over Europe and the Mediterranean.

Connors, V. S.↗
NASA NTRS1990

National plan to enhance aviation safety through human factors improvements

The purpose of this section of the plan is to establish a development and implementation strategy plan for improving safety and efficiency in the Air Traffic Control (ATC) system. These improvements will be achieved through the proper applications of human factors considerations to the present and future systems. The program will have four basic goals: (1) prepare for the future system through proper hiring and training; (2) develop a controller work station team concept (managing human errors); (3) understand and address the human factors implications of negative system results; and (4) define the proper division of responsibilities and interactions between the human and the machine in ATC systems. This plan addresses six program elements which together address the overall purpose. The six program elements are: (1) determine principles of human-centered automation that will enhance aviation safety and the efficiency of the air traffic controller; (2) provide new and/or enhanced methods and techniques to measure, assess, and improve human performance in the ATC environment; (3) determine system needs and methods for information transfer between and within controller teams and between controller teams and the cockpit; (4) determine how new controller work station technology can optimally be applied and integrated to enhance safety and efficiency; (5) assess training needs and develop improved techniques and strategies for selection, training, and evaluation of controllers; and (6) develop standards, methods, and procedures for the certification and validation of human engineering in the design, testing, and implementation of any hardware or software system element which affects information flow to or from the human.

Foushee, Clay↗