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At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

WIRE-21 Experiment Irradiation Conditions and In-Situ Data Collection

This report summarizes the in situ data collected during three cycles of irradiation (~75 days) of the Wireless Instrumented Removable Beryllium Experiment 2021 (WIRE-21) in the removable beryllium (RB) positions of the High Flux Isotope Reactor (HFIR). The experiment was designed primarily to evaluate the effects of high neutron flux and fluence on the performance of wireless temperature and pressure sensors being developed by Westinghouse Electric Company (WEC). WEC’s sensors could provide critical data regarding the evolution of centerline temperatures and pressurization due to fission gas release during fuel operation in light-water reactors (LWRs) or various advanced reactor applications. In addition to WEC’s wireless sensors, many other sensors were interrogated, including thermocouples, self-powered neutron detectors (SPNDs), distributed fiber optic temperature sensors, and passive neutron flux wires and silicon carbide thermometry.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1973

An airborne laser fluorosensor for the detection of oil on water

The successful operation of an airborne laser fluorosensor system is reported that makes it possible to detect and map surface oil, either of natural-seepage or spill origin, on large bodies of water. Preliminary results indicate that the sensitivity of the instrument exceeds that of conventional passive remote sensors currently available for oil spill detection.

Kim, H. H.↗
NASA NTRS1975

Passive microwave sensing of the earth

The natural thermal radio radiation emitted by the terrestrial atmosphere and surface can be measured by passive microwave sensors. The receivers and antennas for the required sensing systems are briefly considered along with questions regarding the geophysical information obtainable. Satellite, aircraft, and ground-based observations are discussed. Attention is given to the possibility to monitor continually the evolution of the ice caps in polar regions.

Staelin, D. H.↗
NASA NTRS1975

Microwave remote sensing of soil moisture

The potential application of microwave remote sensing devices in estimating soil moisture content over extended areas was examined. Experimental measurements involving both active and passive microwave sensors acquired from a variety of platforms are presented.

Ulaby, F. T.↗
NASA NTRS1977

Microwave remote sensing and its application to soil moisture detection

The author has identified the following significant results. Experimental measurements were utilized to demonstrate a procedure for estimating soil moisture, using a passive microwave sensor. The investigation showed that 1.4 GHz and 10.6 GHz can be used to estimate the average soil moisture within two depths; however, it appeared that a frequency less than 10.6 GHz would be preferable for the surface measurement. Average soil moisture within two depths would provide information on the slope of the soil moisture gradient near the surface. Measurements showed that a uniform surface roughness similar to flat tilled fields reduced the sensitivity of the microwave emission to soil moisture changes. Assuming that the surface roughness was known, the approximate soil moisture estimation accuracy at 1.4 GHz calculated for a 25% average soil moisture and an 80% degree of confidence, was +3% and -6% for a smooth bare surface, +4% and -5% for a medium rough surface, and +5.5% and -6% for a rough surface.

Newton, R. W.↗
NASA NTRS1979

Active/passive scanning

The paper deals with the design, construction, and applications of an active/passive multispectral scanner combining lasers with conventional passive remote sensors. An application investigation was first undertaken to identify remote sensing applications where active/passive scanners (APS) would provide improvement over current means. Calibration techniques and instrument sensitivity are evaluated to provide predictions of the APS's capability to meet user needs. A preliminary instrument design was developed from the initial conceptual scheme. A design review settled the issues of worthwhile applications, calibration approach, hardware design, and laser complement. Next, a detailed mechanical design was drafted and construction of the APS commenced. The completed APS was tested and calibrated in the laboratory, then installed in a C-47 aircraft and ground tested. Several flight tests completed the test program.

Woodfill, J. R.↗
NASA NTRS1979

Relation between West Coastal rainfall and Nimbus 6 SCAMS liquid water data over the northeastern Pacific Ocean

A research study is described in which the application to rainfall prediction of cloud liquid water data obtained from the SCAMS experiment of Nimbus 6 is explored. The study area is the Pacific Northwest coast of the United States, where rainfall is produced by extratropical storms that approach from across the Pacific Ocean. SCAMS data related to cloud liquid water over the ocean, and coastal rainfall data, are analyzed for 20 different storm systems in the northeastern Pacific Ocean; these produced significant rainfall from Washington to central California during the period October 1975-March 1976. Results show that the distribution of storm-cloud water analyzed from the SCAMS data over the ocean foreshadows the distribution of coastal rainfall accumulated from the storm at a later time. It is concluded that passive microwave sensor measurements of cloud water over the ocean, when used in conjunction with numerical and other objective guidance, can be used to enhance the accuracy of predictions of coastal rainfall distribution. Limitations in the SCAMS measurements and in the data analysis and interpretation are noted.

Viezee, W.↗
NASA NTRS1979

Relation between west coastal rainfall and Nimbus-6 SCAMS liquid water data over the northeastern Pacific Ocean

The application to rainfall prediction of cloud liquid water data obtained from the SCAMS experiment of Nimbus-6 is explored. The study area is the Pacific Northwest coast of the United States, where rainfall is produced by extratropical storms that approach from across the Pacific Ocean. The SCAMS data related to cloud liquid water over the ocean, and coastal rainfall data, are analyzed for 20 different storm systems in the northeastern Pacific Ocean; these produced significant rainfall from Washington to central California during the period October 1975 through March 1976. Results show that the distribution of storm cloud water analyzed from the SCAMS data over the ocean foreshadows the distribution of coastal rainfall accumulated from the storm at a later time. It is concluded that passive microwave sensor measurements of cloud water over the ocean, when used in conjunction with numerical and other objective guidance, can be used to enhance the accuracy of predictions of coastal rainfall distribution. Limitations in the SCAMS measurements and in the data analysis and interpretation are noted.

Viezee, W.↗
NASA NTRS1978

Passive microwave studies of frozen lakes

Lakes of various sizes, depths and ice thicknesses in Alaska, Utah and Colorado were overflown with passive microwave sensors providing observations at several wavelengths. A layer model is used to calculate the microwave brightness temperature, T sub B (a function of the emissivity and physical temperatures of the object), of snowcovered ice underlain with water. Calculated T sub B's are comparable to measured T sub B's. At short wavelengths, e.g., 0.8 cm, T sub B data provide information on the near surface properties of ice covered lakes where the long wavelength, 21.0 cm, observations sense the entire thickness of ice including underlying water. Additionally, T sub B is found to increase with ice thickness. 1.55 cm observations on Chandalar Lake in Alaska show a T sub B increase of 38 K with an approximate 124 cm increase in ice thickness.

Hall, D. K.↗
NASA NTRS1980

Advanced techniques for future observations from space

Advanced remote sensing techniques for the study of global meteorology and the chemistry of the atmosphere are considered. Remote sensing from Spacelab/Shuttle and free-flying satellites will provide the platforms for instrumentation based on advanced technology. Several laser systems are being developed for the measurement of tropospheric winds and pressure, and trace species in the troposphere and stratosphere. In addition, a high-resolution passive infrared sensor shows promise for measuring temperature from sea level up through the stratosphere. Advanced optical and microwave instruments are being developed for wind measurements in the stratosphere and mesosphere. Microwave techniques are also useful for the study of meteorological parameters at the air-sea interface.

Hinkley, E. D.↗
NASA NTRS1981

Aircraft active microwave measurements for estimating soil moisture

Both active and passive microwave sensors are sensitive to variations in near-surface soil moisture. The principal advantage of active microwave systems for soil moisture applications is that high spatial resolution can be retained even at satellite attitudes. The considered investigation is concerned with the use of active microwave scatterometers for estimating near-surface soil moisture. Microwave scatterometer data were obtained during a series of three aircraft flights over a group of Oklahoma research watersheds during May 1978. Data were obtained for the C, L, and P bands at angles of incidence between 5 and 50 degrees. The best results were obtained using C band data at incidence angles of 10 and 15 degrees and soil moisture depth of 0 to 15 cm. These results were in excellent agreement with the conclusions of the truck-mounted scatterometer measurement program reported by Ulaby et al. (1978, 1979).

Jackson, T. J.↗
NASA NTRS1981

Active microwave measurements for estimating soil moisture in Oklahoma

Previous research has shown that active and passive microwave sensors can be used to estimate near surface soil moisture. An advantage of the active systems is that they have the capability of high spatial resolution from satellite platforms. Most of the previous research has been conducted on agricultural fields. This study examined the use of active microwave data for estimating the average surface soil moisture for several watersheds located near Chicasha, Oklahoma. Data were collected using P, L, and C band scatterometers, mounted on the National Aeronautics and Space Administration C130B aircraft flying at an altitude of 300 m. Soil moisture data were collected in conjunction with three flights during May 1978. Our results indicated that relationships between the scatterometer data and soil moisture do exist and agree with the results obtained at the University of Kansas.

Jackson, T. J.↗
NASA NTRS1980

Airborne microwave radiometer remote sensing of lake ice

The NASA Langley C-Band Stepped Frequency Microwave Radiometer was used to conduct airborne remote sensing measurements of the Great Lakes ice cover during the winters of 1978 and 1979. In order to evaluate the use of microwave radiometry for remote sensing of fresh water ice, an initial experiment was conducted in February 1978. After the results were analyzed an algorithm was developed, and a more comprehensive mission was completed in March 1979, which related the thermal emission from lake ice to meaningful geophysical quantities. A clear discrimination of pressure ridges and rubble from base ice was observed, and evidence was found which showed gradual changes in the thickness of the base itself. Results indicate that passive microwave sensors can provide a measure of lake ice within uncertainties presented by the attenuation coefficient, and the changes in surface reflectivity imposed by surface roughness.

Swift, C. T.↗
NASA NTRS1983

Searching for Clear-Air Turbulence

System for determining potential location and severity of clear-air turbulence based on passive microwave sensor. Horn antenna for prototype clearair-turbulence warning system rotatable through plus or minus 45 degrees. Permits safer more comfortable flights for commercial airplanes and enables safer inflight refueling for military airplanes.

Gary, B. L.↗
NASA NTRS1983

Fiberoptics technology and its application to propulsion control systems

Electro-optical systems have many advantages over conventional electrical systems. Among these are optics' insensitivity to electro-magnetic interference, good electrical isolation and the ability to make measurements in highly explosive areas without risk. These advantages promise to help improve the reliability of future aircraft engine control systems which will be entirely electronic digital. To improve the reliability of these systems, especially against lightning strikes, passive, optical, sensors and fiberoptic transmission lines are being considered for use in future engine systems. Also under consideration are actuators which receive their command signals over fiber optic cables. This paper reviews concepts used for optical instrumentation and actuation systems and discusses work being done by NASA Lewis Research Center in this area.

Baumbick, R. J.↗
NASA NTRS1981

Detection of rainfall rates utilizing spaceborne microwave radiometers

To demonstrate the success of utilizing passive microwave sensors in monitoring synoptic scale rainfall, two studies are described in which electrically scanning microwave radiometers (ESMR-5 and 6) on board Nimbus 5 and 6 were employed using a Langrangian frame of reference. The first study suggests a method of utilizing ESMR-5 measurements to quantize rainfall over water within tropical and extratropical storms and to use these measurements to monitor and possibly predict storm intensity. The second study suggests a method of monitoring the coverage and movement of synoptic rain over land by employing ESMR-6.

Burke, H. H. K.↗