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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 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
NASA NTRS1944

Compressibility Effects on Heat Transfer and Pressure Drop in Smooth Cylindrical Tubes

An analysis is made to simplify pressure-drop calculations for nonadiabatic and adiabatic friction flow of air in smooth cylindrical tubes when the density changes due to heat transfer and pressure drop are appreciable. Solutions of the equation of motion are obtained by the use of Reynolds' analogy between heat transfer and skin friction. Charts of the solutions are presented for making pressure-drop calculations. A technique of using the charts to determine the position of a normal shock in a tube is described.

AIR FLOW - TUBES, CYLINDRICAL↗
NASA NTRS1993

Effects of turbulence on the geodynamic laser ranging system

The Geodynamic Laser Ranging System (GLRS) is one of several instruments being developed by the National Aeronautics and Space Administration (NASA) for implementation as part of the Earth Observing System in the mid-1990s (Cohen et al., 1987; Bruno et al., 1988). It consists of a laser transmitter and receiver in space and an array of retroreflectors on the ground. The transmitter produces short (100 ps) pulses of light at two harmonics (0.532 and 0.355 microns) of the Nd:YAG laser. These propagate to a retroreflector on the ground and return. The receiver collects the reflected light and measures the round-trip transit time. Ranging from several angles accurately determines the position of the retroreflector, and changes in position caused by geophysical processes can be monitored.

Churnside, James H.↗
NASA NTRS1993

Internetworking satellite and local exchange networks for personal communications applications

The demand for personal communications services has shown unprecedented growth, and the next decade and beyond promise an era in which the needs for ubiquitous, transparent and personalized access to information will continue to expand in both scale and scope. The exchange of personalized information is growing from two-way voice to include data communications, electronic messaging and information services, image transfer, video, and interactive multimedia. The emergence of new land-based and satellite-based wireless networks illustrates the expanding scale and trend toward globalization and the need to establish new local exchange and exchange access services to meet the communications needs of people on the move. An important issue is to identify the roles that satellite networking can play in meeting these new communications needs. The unique capabilities of satellites, in providing coverage to large geographic areas, reaching widely dispersed users, for position location determination, and in offering broadcast and multicast services, can complement and extend the capabilities of terrestrial networks. As an initial step in exploring the opportunities afforded by the merger of satellite-based and land-based networks, several experiments utilizing the NASA ACTS satellite and the public switched local exchange network were undertaken to demonstrate the use of satellites in the delivery of personal communications services.

Wolff, Richard S.↗
NASA NTRS1993

Rack Insertion End Effector (RIEE) automation

NASA is developing a mechanism to manipulate and insert Racks into the Space Station Logistic modules. The mechanism consists of the following: a base with three motorized degrees of freedom, a 3 section motorized boom that goes from 15 to 44 feet in length, and a Rack Insertion End Effector (RIEE) with 5 hand wheels for precise alignment. The robotics section was tasked with the automation of the RIEE unit. In this report, for the automation of the RIEE unit, application of the Perceptics Vision System was conceptually developed to determine the position and orientation of the RIEE relative to the logistic module, and a MathCad program is written to display the needed displacements for precise alignment and final insertion of the Rack. The uniqueness of this report is that the whole report is in fact a MathCad program including text, derivations, and executable equations with example inputs and outputs.

Malladi, Narasimha↗
NASA NTRS1992

Telerobotic rendezvous and docking vision system architecture

This research program has successfully demonstrated a new target label architecture that allows a microcomputer to determine the position, orientation, and identity of an object. It contains a CAD-like database with specific geometric information about the object for approach, grasping, and docking maneuvers. Successful demonstrations were performed selecting and docking an ORU box with either of two ORU receptacles. Small, but significant differences were seen in the two camera types used in the program, and camera sensitive program elements have been identified. The software has been formatted into a new co-autonomy system which provides various levels of operator interaction and promises to allow effective application of telerobotic systems while code improvements are continuing.

Gravely, Ben↗
NASA NTRS1995

The Global Positioning System (GPS) and attitude determination: Applications and activities in the Flight Dynamics Division

The application of GPS to spacecraft attitude determination is a new and growing field. Although the theoretical literature is extensive, space flight testing is currently sparse and inadequate. As an operations organization, the Flight Dynamics Division (FDD) has the responsibility to investigate this new technology, and determine how best to implement the innovation to provide adequate support for future missions. This paper presents some of the current efforts within FDD with regard to GPS attitude determination. This effort specifically addresses institutional capabilities to accommodate a new type of sensor, critically evaluating the literature for recent advancements, and in examining some available -albeit crude- flight data.

Ketchum, Eleanor↗
NASA NTRS1994

Lunar crescent visibility

We report the results of five Moonwatches, in which more than 2000 observers throughout North America attempted to sight the thin lunar crescent. For each Moonwatch we were able to determine the position of the Lunar Date Line (LDL), the line along which a normal observer has a 50% probability of spotting the Moon. The observational LDLs were then compared with predicted LDLs derived from crescent visibility prediction algorithms. We find that ancient and medieval rules are higly unreliable. More recent empirical criteria, based on the relative altitude and azimuth of the Moon at the time of sunset, have a reasonable accuracy, with the best specific formulation being due to Yallop. The modern theoretical model by Schaefer (based on the physiology of the human eye and the local observing conditions) is found to have the least systematic error, the least average error, and the least maximum error of all models tested. Analysis of the observations also provided information about atmospheric, optical and human factors that affect the observations. We show that observational lunar calendars have a natural bias to begin early.

Doggett, Leroy E.↗
NASA NTRS1994

Extreme ultraviolet spectrum of a solar active region from SERTS

We present wavelengths and absolute intensities for 243 emission lines from a single active region observed by the Solar Extreme Ultraviolet (EUV) Rocket Telescope and Spectrograph (SERTS) on 1989 May 5. For this catalog, the imaged spectra have been spatially averaged over a field of view 7 sec x 276 sec cutting through the center of AR5464 at S18 W45. Wavelength coverage is 170-450 A with a spectral resolution approaching 10,000. Most of the line positions are determined to 5 mA or better, representing the highest accuracy yet obtained for solar wavelengths throughout this spectral interval. The relative photometric calibration of the instrument is good to +/- 20% over its first-order range, and has been placed onto an absolute scale that should be correct to within a factor less than 2. Where known, identifications, atomic transitions and formation temperatures are also given. The identified lines arise from temperatures that cover the range log T greater than or equal to 4.7 and less than or equal to 6.8, providing information about the Sun's corona and upper transition region. Upper limits to the intensity of any emission line not included here can be estimated from the measured instrumental sensitivity. This averaged EUV spectrum should prove useful as a source of accurate wavelengths and intensities for emission characteristic of the high-temperature plasma associated with a solar active region and small subflare.

Thomas, Roger J.↗
NASA NTRS1994

The dynamic cusp at low altitudes: A case study utilizing Viking, DMSP-F7 and Sondrestrom incoherent scatter radar observations

Coincident multi-instrument magnetospheric and ionospheric observations have made it possible to determine the position of the ionospheric footprint of the magnetospheric cusp and to monitor its evolution over time. The data used include charged particle and magnetic field measurements from the Earth-orbiting Viking and DMSP-F7 satellites, electric field measurements from Viking, interplanetary magnetic field and plasma data from IMP-8, and Sondrestrom incoherent scatter radar observations of the ionospheric plasma density, temperature, and convection. Viking detected cusp precipitation poleward of 75.5 deg invariant latitude. The ionospheric response to the observed electron precipitation was simulated using an auroral model. It predicts enhanced plasma density and elevated electron temperature in the upper E- and F- regions. Sondrestrom radar observations are in agreement with the predictions. The radar detected a cusp signature on each of five consecutive antenna elevation scans covering 1.2h local time. The cusp appeared to be about 2 deg invariant latitude wide, and its ionospheric footprint shifted equatorward by nearly 2 deg during this time, possibly influenced by an overall decrease in the interplanetary magnetic field (IMF) B(sub z) component. The radar plasma drift data and the Viking magnetic and electric field data suggest that the cusp was associated with a continuous, rather than a patchy, merging between the IMF and the geomagnetic field.

Watermann, J.↗
NASA NTRS1995

Large-scale structure of the solar corona and inner heliosphere

The large-scale structure of the solar corona influences solar activity particularly coronal mass ejections (CMEs). The helmet streamers that are observed to dominate the structure of the inner corona are formed by the interaction of the solar wind with coronal magnetic fields. We have simulated this interaction in three dimensions using the magnetohydrodynamic (MHD) equations. In order to create a realistic model, we use the magnetic field that is observed at the Sun's surface (deduced from daily Wilcox Solar Observatory magnetograms) as input, in combination with specified density and temperature profiles at the surface. A self-consistent 3D solar-wind solution is developed by integrating the MHD equations in time to steady state. Such solutions can reproduce the observed structures that are seen in coronagraph images and eclipse photographs of the corona. This model allows us to accurately determine the position of the heliospheric current sheet. We will compare the results obtained from our model with Ulysses observations during the period May-June 1993, and with an eclipse photograph of the corona on November 3, 1994.

Mikic, Z.↗
NASA NTRS1997

Flight Demonstration of a Shock Location Sensor Using Constant Voltage Hot-Film Anemometry

Flight tests have demonstrated the effectiveness of an array of hot-film sensors using constant voltage anemometry to determine shock position on a wing or aircraft surface at transonic speeds. Flights were conducted at the NASA Dryden Flight Research Center using the F-15B aircraft and Flight Test Fixture (FTF). A modified NACA 0021 airfoil was attached to the side of the FTF, and its upper surface was instrumented to correlate shock position with pressure and hot-film sensors. In the vicinity of the shock-induced pressure rise, test results consistently showed the presence of a minimum voltage in the hot-film anemometer outputs. Comparing these results with previous investigations indicate that hot-film anemometry can identify the location of the shock-induced boundary layer separation. The flow separation occurred slightly forward of the shock- induced pressure rise for a laminar boundary layer and slightly aft of the start of the pressure rise when the boundary layer was tripped near the airfoil leading edge. Both minimum mean output and phase reversal analyses were used to identify the shock location.

Moes, Timothy R.↗
NASA NTRS1997

The scientific basis for the space interferometry mission

The space interferometry mission (SIM), for launch in 2004, is expected to determine the positions of point sources to a global accuracy of 4 microarcsec, and an accuracy of 1 microarcsec over small angles. The instrument will reach 200 mag in 3 x 10(exp 4) s and has a nominal lifetime of five years. A nulling capability will be provided and synthesis imaging and near-infrared capabilities are being considered. These capabilities will extend those of the Hipparcos mission by almost three orders of magnitude in every sense. The NASA's expectation for the scientific return from the SIM mission is outlined in terms of the areas of stellar physics, galactic structure and extragalactic astrophysics, including the distance scale problem.

Peterson, Deane↗
NASA NTRS1998

Autonomous Mobile Platform for Research in Cooperative Robotics

This paper describes the design and development of a platform for research in cooperative mobile robotics. The structure and mechanics of the vehicles are based on R/C cars. The vehicle is rendered mobile by a DC motor and servo motor. The perception of the robot's environment is achieved using IR sensors and a central vision system. A laptop computer processes images from a CCD camera located above the testing area to determine the position of objects in sight. This information is sent to each robot via RF modem. Each robot is operated by a Motorola 68HC11E micro-controller, and all actions of the robots are realized through the connections of IR sensors, modem, and motors. The intelligent behavior of each robot is based on a hierarchical fuzzy-rule based approach.

Daemi, Ali↗
NASA NTRS1998

Effect of Fresh Poultry Litter and Compost on Soil Physical and Chemical Properties

Application of poultry litter and compost as a substitute for fertilizer not only uses unwanted waste and decreases expenditures for commercial fertilizer, it adds nutrients to soil for plant uptake. The properties of soil affected by poultry litter were analyzed to determine the positive and negative aspects of using this substitute fertilizer. This study focused on changes associated with saturated hydraulic conductivity, bulk density, nitrate concentrations, and pH after application of varying concentrations of poultry litter and compost. Soil samples from Tennessee Valley Substation in Alabama were analyzed in a laboratory at Alabama A&M University. As a result of the application of fresh poultry litter and compost, we found that the saturated hydraulic conductivity increased and the bulk density decreased, while the pH was generally not affected. Using poultry litter and compost as an alternative commercial fertilizers could be adapted by the farming community to protect the sustainability of our environment. Unwanted waste is used productively and soil is enriched for farming.

Carr, Stacy↗
NASA NTRS2000

Marine Magnetic Anomalies and the Reconstruction of the World

Until the middle of the 20th century little was known about magnetic anomalies in the oceans. Then it was discovered that there are relatively large anomalies in most of the oceans and they were unrelated to any geological structure known at that time. In the early 1950's large anomalies had been found over the Mid-Atlantic Ridge, and linear anomalies over the eastern continental shelf of North America and, shortly after that, off the west coast. A survey of the ridge south of Iceland showed that the anomalies were linear, parallel to the ridge axis, and symmetrical about the axis. Using the theory that the anomalies were caused by geomagnetic field reversals and seafloor spreading it was possible to greatly extend the time scale of geomagnetic reversals, to determine the velocity of seafloor spreading and estimate the time of opening of the North Atlantic. Lamont had a world-wide collection of marine magnetic profiles. These were used, systematically, to determine the positions of most of the land masses of the world since the beginnings of the world's present oceans.

Heirtzler, James R.↗
NASA NTRS2003

Modeling of Depth Cue Integration in Manual Control Tasks

Psychophysical research has demonstrated that human observers utilize a variety of visual cues to form a perception of three-dimensional depth. However, most of these studies have utilized a passive judgement paradigm, and failed to consider depth-cue integration as a dynamic and task-specific process. In the current study, we developed and experimentally validated a model of manual control of depth that examines how two potential cues (stereo disparity and relative size) are utilized in both first- and second-order active depth control tasks. We found that stereo disparity plays the dominate role for determining depth position, while relative size dominates perception of depth velocity. Stereo disparity also plays a reduced role when made less salient (i.e., when viewing distance is increased). Manual control models predict that position information is sufficient for first-order control tasks, while velocity information is required to perform a second-order control task. Thus, the rules for depth-cue integration in active control tasks are dependent on both task demands and cue quality.

Sweet, Barbara T.↗
NASA NTRS1984

Determination of the gram-positive bacterial content of soils and sediments by analysis of teichoic acid components

Many gram-positive bacteria form substituted polymers of glycerol and ribitol phosphate esters known as teichoic acids. Utilizing the relative specificity of cold concentrated hydrofluoric acid in the hydrolysis of polyphosphate esters it proved possible to quantitatively assay the teichoic acid-derived glycerol and ribitol from gram-positive bacteria added to various soils and sediments. The lipids are first removed from the soils or sediments with a one phase chloroform-methanol extraction and the lipid extracted residue is hydrolyzed with cold concentrated hydrofluoric acid. To achieve maximum recovery of the teichoic acid ribitol, a second acid hydrolysis of the aqueous extract is required. The glycerol and ribitol are then acetylated after neutralization and analyzed by capillary gas-liquid chromatography. This technique together with measures of the total phospholipid, the phospholipid fatty acid, the muramic acid and the hydroxy fatty acids of the lipopolysaccharide lipid A of the gram-negative bacteria makes it possible to describe the community structure environmental samples. The proportion of gram-positive bacteria measured as the teichoic acid glycerol and ribitol is higher in soils than in sediments and increases with depth in both.

Ribitol/analogs & derivatives↗
NASA NTRS2005

Constraints of Melting, Sea-Level and the Paleoclimate from GRACE

To gauge the accuracy of the GRACE data, we have undertaken a study to compare deformations predicted by GRACE inferences of seasonal water loading to crustal position variations determined from GRACE data. Two manuscripts that resulted from this study are attached. We found a very high correlation between the GRACE and GPS determinations for South America [Duvis et al., 2004]. We also developed a statistical approach for choosing which Stokes coefficients to include. This approach proves to be somewhat more accurate than the traditional Gaussian filter [Duvis et al., 2005].

Davis, James L.↗