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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 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Technology for Safer Skies

The Bendix RDR-4B airborne weather radar, developed by Allied Signal Commercial Avionic Systems, is the product of a decade-long Federal Aviation Administration (FAA)/NASA/industry/academia research program. Numerous aircraft accidents had occurred because of windshear, a sudden shift in wind direction and velocity. A characteristic of windshear is the microburst, a column of air which cools rapidly in a thunderstorm and generates intense downdrafts. Microbursts can cause an airplane to lose lift and speed and then crash. A Congressional Mandate to the FAA launched the program with NASA to develop the essential technology for detecting and avoiding microbursts. Langley Research Center developed microburst sensors, including Doppler microwave radar, which sends a radio wave ahead of the aircraft to measure windshear velocity. These predictions give pilots time to prepare for the microbursts. After flight tests and the design of certification standards, the FAA required all commercial aircraft to install some type of windshear detector or predictor.

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NASA NTRS1987

Ranger's Legacy

With its Landsat satellites, development of sensors, and advancement of processing techniques, NASA provided the initial technology base for another Earth-benefit application of image processing, Earth resources survey by means of remote sensing. Since each object has its own unique "signature," it is possible to distinguish among surface features and to generate computer-processed imagery identifying specific features of importance to resource managers. This capability, commercialized by Perceptive Scientific Instruments, Inc., offers practical application in such areas as agricultural crop forecasting, rangeland and forest management, land use planning, mineral and petroleum exploration, map making, water quality evaluation and disaster assessment. Major users of the technology have been federal, state, and local governments, but it is making its way into commercial operations, for example, resource exploration companies looking for oil, gas and mineral sources, and timber production firms seeking more efficient treeland management. Supporting both government and private users is a small industry composed of companies producing the processing hardware software. As is the case in the medical application, many of these companies are direct offspring of NASA's work.

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NASA NTRS2003

Team Oriented Robotic Exploration Task on Scorpion and K9 Platforms

This final report describes the achievements that have been made in the project over the complete period of performance. The technical progress highlights the different areas of work in terms of Progress in Mechatronics, Sensor integration, Software Development. User Interfaces, Behavior Development and Experimental Results and System Testing. The different areas are: Mechatronics, Sensor integration, Software development, Experimental results and Basic System Testing, Behaviors Development and Advanced System Testing, User Interface and Wireless Communication.

Kirchner, Frank↗
NASA NTRS2004

Passive Measurement of CO2 Column from an Airborne Platform

We are in the third and final year of our IIP funding to develop a sensor for very precise determination of the CO2 Column. Global measurements of this sort from a satellite platform are needed to improve our understanding of the global carbon budget. In previous reports to this meeting we have described the method by which this system operates and presented data taken during ground based tests of the instrument. Work in the final year has concentrated on building the flight hardened version of the instrument that will be used in our field trials on the Dryden DC-8. The flight unit represents an integration of three channels into a single instrument. These three channels are the CO2 channel, the oxygen pressure sensing channel, and the oxygen temperature sensing channel. Integration of the three channels into a single unit significantly decreases the size of the instrument. The flight unit also employs more rugged optical mounts and integrated optical shielding. Light enters the instrument from below first striking the right angled mirror shown extending over the edge of the platform. The light is then focused through a pinhole to define the instrument field of view, chopped and recollimated. Dichroic mirrors are used to separate the CO2 wavelength from the O2 wavelength and that light is further divided by a 50-50 beamsplitter between the 2 oxygen channels - the pressure channel and the temperature channel. The six white boxes contain the detectors for each of the three channels. The detectors on the left in the photo serve the reference channels and the detectors on the right are for the Fabry-Perots. CO2 is measured by the pair of detectors farthest from the viewer. Pressure via O2 is detected by the central pair of detectors. The closest pair is used to determine temperature via O2.

Heaps, William S.↗
NASA NTRS2004

The Impact of Current and Future Polar Orbiting Satellite Data on Numerical Weather Prediction at NASA/GSFC

The lack of adequate observational data continues to be recognized as a major factor limiting both atmospheric research and numerical prediction on a variety of temporal and spatial scales. Since the advent of meteorological satellites in the 1960's, a considerable research effort has been directed toward the design of space-borne meteorological sensors, the development of optimal methods for the utilization of these data, (and an assessment of the influence of existing satellite data and the potential influence of future satellite observations on numerical weather prediction. This has included both Observing System Experiments (OSEs) and Observing System Simulation Experiments (OSSEs). OSEs are conducted to evaluate the impact of specific observations or classes of observations on analyses and forecasts. While OSEs are performed with existing data, OSSEs are conducted to evaluate the potential for future observing systems to improve-NWP, as well as to evaluate trade-offs in observing system design, and to develop and test improved methods for data assimilation. At the conference, results from OSEs to evaluate satellite data sets that have recently become available to the global observing system, such as AIRS and Seawinds, and results from OSSEs to determine the potential impact of space-based lidar winds will be presented.

Atlas, Robert↗
NASA NTRS1998

New Research Methods Developed for Studying Diabetic Foot Ulceration

Dr. Brian Davis, one of the Cleveland Clinic Foundation's researchers, has been investigating the risk factors related to diabetic foot ulceration, a problem that accounts for 20 percent of all hospital admissions for diabetic patients. He had developed a sensor pad to measure the friction and pressure forces under a person's foot when walking. As part of NASA Lewis Research Center's Space Act Agreement with the Cleveland Clinic Foundation, Dr. Davis requested Lewis' assistance in visualizing the data from the sensor pad. As a result, Lewis' Interactive Data Display System (IDDS) was installed at the Cleveland Clinic. This computer graphics program is normally used to visualize the flow of air through aircraft turbine engines, producing color two- and three-dimensional images.

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NASA NTRS2004

OBPR Product Lines, Human Research Initiative, and Physics Roadmap for Exploration

The pace of change has increased at NASA. OBPR s focus is now on the Human interface as it relates to the new Exploration vision. The fundamental physics community must demonstrate how we can contribute. Many opportunities exist for physicists to participate in addressing NASA's cross-disciplinary exploration challenges: a) Physicists can contribute to elucidating basic operating principles for complex biological systems; b) Physics technologies can contribute to developing miniature sensors and systems required for manned missions to Mars. NASA Codes other than OBPR may be viable sources of funding for physics research.

Israelsson, Ulf↗
NASA NTRS2006

The Space Technology-7 Disturbance Reduction System Precision Control Flight Validation Experiment Control System Design

As originally proposed, the Space Technology-7 Disturbance Reduction System (DRS) project, managed out of the Jet Propulsion Laboratory, was designed to validate technologies required for future missions such as the Laser Interferometer Space Antenna (LISA). The two technologies to be demonstrated by DRS were Gravitational Reference Sensors (GRSs) and Colloidal MicroNewton Thrusters (CMNTs). Control algorithms being designed by the Dynamic Control System (DCS) team at the Goddard Space Flight Center would control the spacecraft so that it flew about a freely-floating GRS test mass, keeping it centered within its housing. For programmatic reasons, the GRSs were descoped from DRS. The primary goals of the new mission are to validate the performance of the CMNTs and to demonstrate precise spacecraft position control. DRS will fly as a part of the European Space Agency (ESA) LISA Pathfinder (LPF) spacecraft along with a similar ESA experiment, the LISA Technology Package (LTP). With no GRS, the DCS attitude and drag-free control systems make use of the sensor being developed by ESA as a part of the LTP. The control system is designed to maintain the spacecraft s position with respect to the test mass, to within 10 nm/the square root of Hz over the DRS science frequency band of 1 to 30 mHz.

O'Donnell, James R.↗
NASA NTRS1993

Imaging Radar Polarimetry

In this paper, we review the state of the art in imaging radar polarimetry, examine current developments in sensor technology and implementation for recording polarimetric measurements, and describe techniques and areas of application for the new remote sensing data.

radars fixed-polarization antenna digital data rec↗
NASA NTRS2006

InGaAsSb/AlGaAsSb Heterojunction Phototransistors for Infrared Applications

High quality infrared (IR) quantum detectors are important for several applications, such as atmospheric remote sensing, chemical detection and absorption spectroscopy. Although several IR detectors are commercially available, with different materials and structures, they provide limited performance regarding the signal-to-noise ratio and the corresponding minimum detectable signal. InGaAsSb/AlGaAsSb heterojunction based phototransistors show strong potential for developing IR sensors with improved performance. In this paper, the performance of a novel npn InGaAsSb/AlGaAsSb heterojunction phototransistor is presented. This performance study is based on experimental characterization of the device dark current, noise and spectral response. Detectivity of 1.7x10(exp 9) cmHz(exp 1/2)/W at 2 microns was obtained at 100 C temperature and 2 V bias voltage. This corresponds to a responsivity of 94.7 A/W and an internal gain of 156 with about 37.7% quantum efficiency. Reducing the temperature to -30 C allows to increase the bias to 3V and enhance the detectivity to 8.7x10(exp 10) cmHz(exp 1/2)/W at the same wavelength, which corresponds to a responsivity of 386.5 A/W and an internal gain of 288.2 with about 83.3% quantum efficiency. The device impulse response and linearity, including the corresponding dynamic range, also are presented. Impulse response analysis indicated a settling time of about 1.1 s at 2V and 100 C, while linearity measurements indicated a constant responsivity in the radiation intensity range of 1.6x10(exp -7) W/sq cm and 31.6 mW/sq cm.

Refaat, Tamer F.↗
NASA NTRS2007

High-Temperature Characterization of Alumina Substrates and Folded Slot Antenna

The characterization of 99.6% polycrystalline alumina substrates and folded slot antennas is presented in this paper. Coplanar Waveguide (CPW) calibration standards where fabricated on 99.6% polycrystalline alumina substrates. Thru-Reflect-Line (TRL) calibrations were performed at temperatures of 25 to 400 C over a frequency range from 0.5 to 50 GHz. The effective dielectric constant of the alumina substrates was determined to be relatively constant at 5.4 from 25 to 200 C and then increased steadily to approximately 6 at 400 C. The loss of the CPW lines increased as temperature and frequency increased as well noting that the increase in loss is even more profound as both the temperature and frequency increased simultaneously. A CPW fed folded slot antenna fabricated on the alumina substrates is also presented. The Return Loss (RL) of a CPW fed folded slot antenna exhibits a self impedance matching technique. The RL of the folded slot antenna at 25 C displays a resonance at 3.5 GHz and is approximately 16 dB in magnitude. At 300 C the resonance shifts down in frequency to approximately 3.3 dB and has roughly the same magnitude. However the loss of the antenna response also increases at this elevated temperature. This work is part of the initial stages of an effort at NASA Glenn research Center to develop wireless sensors for harsh environments. This work can reduce cost, space to house all the hard wired connections, and reduce the weight of the overall units such as aerospace engines and allow for the placement of the wireless sensors in the engine which are not possible with hard wired sensors.

Scardelletti, Maximilian C.↗
NASA NTRS2006

The Critical Need for Continued Data Collection and Development of Future Thermal Satellite Sensors

There is a rich and long history of thermal infrared (TIR) remote sensing data for multidisciplinary Earth science research. The continuity of TIR data collection, however, is now in jeopardy given there are no planned future Earth observing TIR remote sensing satellite systems with moderately high spatial resolutions to replace those currently in orbit on NASA's Terra suite of sensors. This session will convene researchers who have actively worked in the field of TIR remote sensing to present results that elucidate the importance of thermal remote sensing to the wider Earth science research community. Additionally, this session will also exist as a forum for presenting concepts and ideas for new thermal sensing systems with high spatial resolutions for future Earth science satellite missions, as opposed to planned systems such as the Visible/Infrared Imager/Radiometer (VIIRS) suite of sensors on the National Polar-orbiting Operational Environmental Satellite System (NPOESS) that will collect TIR data at very coarse spatial resolutions.

Quattrochi, Dale A.↗
NASA NTRS2006

Introduction to the Special Session on Thermal Remote Sensing Data for Earth Science Research: The Critical Need for Continued Data Collection and Development of Future Thermal Satellite Sensors

There is a rich and long history of thermal infrared (TIR) remote sensing data for multidisciplinary Earth science research. The continuity of TIR data collection, however, is now in jeopardy given there are no planned future Earth observing TIR remote sensing satellite systems with moderately high spatial resolutions to replace those currently in orbit on NASA's Terra suite of sensors. This session will convene researchers who have actively worked in the field of TIR remote sensing to present results that elucidate the importance of thermal remote sensing to the wider Earth science research community. Additionally, this session will also exist as a forum for presenting concepts and ideas for new thermal sensing systems with high spatial resolutions for future Earth science satellite missions, as opposed to planned systems such as the Visible/Infrared Imager/Radiometer (VIIRS) suite of sensors on the National Polar-orbiting Operational Environmental Satellite System (NPOESS) that will collect TIR data at very coarse ~~~iairesolutions.

Quattrochi, Dale a.↗
NASA NTRS2008

Intelligent Engine Systems: Thermal Management and Advanced Cooling

The objective of the Advanced Turbine Cooling and Thermal Management program is to develop intelligent control and distribution methods for turbine cooling, while achieving a reduction in total cooling flow and assuring acceptable turbine component safety and reliability. The program also will develop embedded sensor technologies and cooling system models for real-time engine diagnostics and health management. Both active and passive control strategies will be investigated that include the capability of intelligent modulation of flow quantities, pressures, and temperatures both within the supply system and at the turbine component level. Thermal management system concepts were studied, with a goal of reducing HPT blade cooling air supply temperature. An assessment will be made of the use of this air by the active clearance control system as well. Turbine component cooling designs incorporating advanced, high-effectiveness cooling features, will be evaluated. Turbine cooling flow control concepts will be studied at the cooling system level and the component level. Specific cooling features or sub-elements of an advanced HPT blade cooling design will be downselected for core fabrication and casting demonstrations.

Bergholz, Robert↗
NASA NTRS2009

Measurement of the Dielectric Constant of Seawater at L-Band: Techniques and Measurements

Satellite instruments, that will monitor salinity from space in the near future, require an accurate relationship between salinity/temperature and seawater dielectric constant. This paper will review measurements that were made of the dielectric constant of seawater during the past several years. The objective of the measurements is to determine the dependence of the dielectric constant of seawater on salinity and on temperature, more accurately than in the past. by taking advantage of modem instrumentation. The measurements of seawater permittivity have been performed as a function of salinity and temperature using a transmission resonant cavity technique. The measurements have been made in the salinity range of 10 to 38 psu and in the temperature range of IOU C to 35 C. These results will be useful in algorithm development for sensor systems such as SMOS and Aquarius. The measurement system consists of a brass microwave cavity that is resonant at 1.413 GHz. The seawater is introduced into the cavity through a capillary glass tube having an inner diameter of 0.1 mm. The diameter of the tube has been made very small so that the amount of seawater introduced in the cavity is small - thus maintaining the sensitivity of the measurements and allowing the use of perturbation theory predicting the seawater permittivity. The change in resonant frequency and the change in cavity Q can be used to determine the real and imaginary pare of the dielectric constant of seawater introduced into the slender tube. The microwave measurements are made by an HPS722D network analyzer. The cavity has been immersed in a u~ateriethylene-glycol bath which is connected to a Lauda circulator. The circulator keeps the brass cavity at a temperature constant to within 0.01 degrees. The system is automated using a Visual Basic program to control the analyzer and to collect the data. The results of the dielectric constant measurements of seawater will be presented. The measurement results will be compared with permittivity values generated from the Kline and Swift relationship. Two methods of calibration will be discussed, The errors that each technique introduces into the measurement resulls will be reviewed. Temperature stability, frequency drift and the effect of increasing cavity transmission loss on the unloaded cavity Q will also be discussed.

Lang, R.↗