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Low Noise Millimeter Wave LNA Project
nasa-test-0.demo.socrata.com | Last Updated 2015-07-20T05:24:11.000ZThe Phase I effort will result in a low noise MMIC G-Band amplifier the covers the entire 165 to 193GHz frequency range. The amplifier will be designed using a 50nm MHEMT that has already been developed by BAE Systems that enables the state-of-the-art performance to be achieved. The innovative amplifier design will have a gain of 20dB, a noise figure of less than 6dB(~4dB, an input output VSWR of less than 2:1. In addition, the MHEMT has the added advantage of having lower noise power stability and 1/f noise than InP devices. A balanced amplifier is the primary approach while a single ended unit will be investigated for missions that require reduced bandwidths. The MMIC amplifier will be designed to be inserted into a waveguide housing for additional and environmental testing in a Phase II program. At completion of the Phase II program, the amplifier will be capable of being space qualified for NASA missions.
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Agency for Toxic Substances and Disease Registry (ATSDR) Hazardous Waste Site Polygon Data, 1996
nasa-test-0.demo.socrata.com | Last Updated 2015-07-19T07:26:48.000ZThe Agency for Toxic Substances and Disease Registry (ATSDR) Hazardous Waste Site Polygon Data, 1996 consists of 2042 polygons for selected hazardous waste sites that were compiled in January 1996. The Hazardous Waste Site ATSDR layer was created by linking HAZ_SITES_ATSDR_BASE with additional data. Most polygons represent sites considered for cleanup under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA or Superfund). Typical sites are either on the EPA National Priorities List (NPL) or are being considered for inclusion on the NPL. This dataset is distributed by the Columbia University Center for International Earth Science Information Network (CIESIN). (Suggested Usage: To provide a polygon dataset of hazardous waste sites in the United States, which can be used to identify nearby populations and assess their potential risk)
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Photonic antenna enhanced middle wave and longwave infrared focal plane array with low noise and high operating temperature Project
nasa-test-0.demo.socrata.com | Last Updated 2015-07-20T05:33:59.000ZPhotodetectors and focal plane arrays (FPAs) covering the middle-wave and longwave infrared (MWIR/LWIR) are of great importance in numerous NASA applications, including earth remote sensing for carbon-based trace gases, Lidar mapping for earth resource locating, and environment and atmosphere monitoring. Existing MWIR/LWIR photodetectors have a low operating temperature of below 77K. The requirement for cryogenic cooling systems adds cost, weight and reliability issues, making it unsuitable for satellite remote sensing applications. This STTR project aims to develop a new plasmonic photonic antenna coupled MWIR/LWIR photodetector and FPA with significantly enhanced performance and a high operating temperature. In Phase I, we developed a preliminary plasmonic photonic antenna enhanced MWIR/LWIR photodetector and demonstrated significant enhancement in photodetectivity and operating temperature. Antenna directivity is also tested and agrees with the simulation. The phase I results not only demonstrated the feasibility of achieving high performance MWIR/LWIR photodetector using the proposed innovation, but also show its promising potentials for high operating temperature FPA development. Motivated by the successful feasibility demonstration and the promising potentials, in this STTR Phase II project, we will develop a prototype of the plasmonic photonic antenna enhanced MWIR/LWIR FPA with a high operating temperature and demonstrate its earth remote sensing capability.
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Low Cost Variable Conductance Heat Pipe for Balloon Payload Project
nasa-test-0.demo.socrata.com | Last Updated 2015-07-20T05:08:14.000ZWhile continuously increasing in complexity, the payloads of terrestrial high altitude balloons need a thermal management system to reject their waste heat and to maintain a stable temperature as the air (sink) temperature swings from as cold as -90<SUP>o</SUP>C to as hot as +40<SUP>o</SUP>C. Currently, constant conductance, copper-methanol heat pipes are utilized on balloon payloads to remove the waste heat. It would be desirable to use a Variable Conductance Heat Pipe (VCHP) instead, to allow the thermal resistance to increase under cold operating or cold survival environment conditions, keeping the instrument section warm. In spacecraft, thermal management is achieved using axially-grooved aluminum-ammonia heat pipes and VCHPs, which are relatively expensive to manufacture and validate. Advanced Cooling Technologies, Inc. (ACT) is proposing a low-cost VCHP based on smooth-bore, thin-wall stainless steel tubing, with either methanol or pentane as working fluids, that is capable of passively maintaining a relatively constant evaporator (payload) temperature while the sink temperature varies between -90<SUP>o</SUP>C and +40<SUP>o</SUP>C. The thin wall will be much lighter and will provide much better temperature control due to its higher thermal resistance, while the combination of working fluid and envelope material result in a heat pipe that is much less expensive to manufacture than standard grooved aluminum heat pipes. Spacecraft VCHPs normally have the gas reservoir at the end of the condenser, and maintain its temperature with electrical heaters. The proposed VCHP moves the reservoir near the evaporator, eliminating the need for electrical power to control the temperature. Preliminary calculations show that either system, methanol based or pentane based, is capable of meeting the thermal performance requirements. For both the pentane and methanol systems, the evaporator (payload) temperature varies less than 6<SUP>o</SUP>C while the heat sink temperature varies from 90<SUP>o</SUP>C to +40<SUP>o</SUP>C.
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Pyramid Comet Sampler Project
nasa-test-0.demo.socrata.com | Last Updated 2015-07-20T05:34:48.000ZBased on the sampling requirements, we propose an Inverted Pyramid sampling system. Each face of the pyramid includes a cutting blade which is independently actuated by redundant pyrotechnic actuators. Such sampler shape has a number of advantages. The pyramidal V shape acts as an arrow piercing into the comet surface at a steep angle. The 4 opposing blades offset tangential forces, meaning that only vertical forces would need to be reacted during impact. These forces could be minimized by making the pyramid height low (and in turn the pyramid would be more flat). In the latest Decadal Survey, the committee recommended selecting a Comet Surface Sample Return mission as one of the five New Frontiers 4 (NF4) missions, solidifying the importance of studying returned physical samples from a comet. Lunar South Pole-Aitken Basin Sample Return could also benefit from the development of this sampling approach.
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ATSDR Hazardous Waste Site Polygon Data with CIESIN Modifications, Version 2
nasa-test-0.demo.socrata.com | Last Updated 2015-07-20T04:34:05.000ZThe Agency for Toxic Substances and Disease Registry (ATSDR) Hazardous Waste Site Polygon Data with CIESIN Modifications, Version 2 is a database providing georeferenced data for 1,572 National Priorities List (NPL) Superfund sites. These were selected from the larger set of the ATSDR Hazardous Waste Site Polygon Data, Version 2 data set with polygons from May 26, 2010. The modified data set contains only sites that have been proposed, currently on, or deleted from the final NPL as of October 25, 2013. Of the 2,080 ATSDR polygons from 2010, 1,575 were NPL sites but three sites were excluded - 2 in the Virgin Islands and 1 in Guam. This data set is modified by the Columbia University Center for International Earth Science Information Network (CIESIN). The modified polygon database includes all the attributes for these NPL sites provided in the ATSDR GRASP Hazardous Waste Site Polygon database and selected attributes from the EPA List 9 Active CERCLIS sites and SCAP 12 NPL sites databases. These polygons represent sites considered for cleanup under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA or Superfund). The Geospatial Research, Analysis, and Services Program (GRASP, Division of Health Studies, Agency for Toxic Substances and Disease Registry, Centers for Disease Control and Prevention) has created site boundary data using the best available information for those sites where health assessments or consultations have been requested.
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BUV/Nimbus-04 Ozone (O3) Profile and Total Column Ozone Monthly L3 Global 5.0deg Lat Zones V1
nasa-test-0.demo.socrata.com | Last Updated 2015-07-20T05:06:00.000ZThe Solar Backscattered Ultra Violet (SBUV) from Nimbus-4 Level-3 monthly zonal mean (MZM) product (BUVN04L3zm) is derived from the Level-2 retrieved ozone profiles. Ozone retrievals are generated from the v8.6 SBUV algorithm. A Level-3 MZM file computes zonal means covering 5 degree latitude bands for each calendar month. For this product there are 72 months of data from May 1970 through April 1976. There are a total of 36 latitudinal bands, 18 in each hemisphere. Profile data are provided at 21 layers from 1013.25, 639.318, 403.382,254.517, 160.589, 101.325,63.9317, 40.3382, 25.4517, 16.0589, 10.1325, 6.39317,4.03382, 2.54517, 1.60589, 1.01325,0.639317, 0.403382, 0.254517, 0.160589 and 0.101325 hPa (measured at bottom of layer). NOTE: Some profiles have 20 layers and do not report the top most layer. Mixing ratios are reported at 15 layers from 0.5, 0.7, 1.0, 1.5, 2.0, 3.0, 4.0, 5.0, 7.0, 10.0, 15.0, 20.0, 30.0, 40.0 and 50.0 hPa (measured at middle of layer). The MZM product averages retrievals that meet the criteria for a good retrieval as determined by error flags in the Level 2 data. A good retrieval is defined as satisfying the following conditions: 1) Profile Error Flag = 0 or 1 (0 = good retrieval; 1 = solar zenith angle > 84 deg.) 2) Total Error Flags = 0, 1, 2 or 5 (0 = good retrieval; 1 = not used; 2 = solar zenith angle > 84 deg; large discrepancy between profile total and best total ozone) NOTE - Total error flag = 5 is anomalously applied at high latitudes and high solar zenith angle where B-Pair total ozone estimate is not as reliable as profile under these conditions. This error flag may be removed in future version of algorithm. The zonal means computed for each month are screened according to the following statistical criteria: 1) number of good retrievals for the month greater than or equal to 2/3 of the samples for a nominal month. 2) mean latitude of good retrievals less than or equal to 1 degree from center of latitude band. 3) mean time of good retrievals less than or equal to 4 days from center of month (i.e., day = 15)
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TRMM Precipitation Radar (PR) Level 2 Rainfall Rate and Profile Product (TRMM Product 2A25) V7
nasa-test-0.demo.socrata.com | Last Updated 2015-07-19T08:53:20.000ZThe TRMM Precipitation Radar (PR), the first of its kind in space, is an electronically scanning radar, operating at 13.8 GHz that measures the 3-D rainfall distribution over both land and ocean, and defines the layer depth of the precipitation. The objectives of 2A25 is to correct for the rain attenuation in measured radar reflectivity and to estimate the instantaneous three-dimensional distribution of rain from the TRMM Precipitation Radar (PR) data. The estimates of attenuation-corrected radar reflectivity factor and rainfall rate are given at each resolution cell of the PR. The estimated near-surface rainfall rate and average rainfall rate between the two pre-defined altitudes (2 and 4 km) are also calculated for each beam position. 2A25 basically uses a hybrid of the Hitschfeld-Bordan method and the surface reference method to estimate the vertical true radar reflectivity (Z) profile. (The hybrid method is described in Iguchi and Meneghini (1994)). The vertical rain profile is then calculated from the estimated true Z profile by using an appropriate Z-R relationship. The attenuation correction is, in principle, based on the surface reference method. This method assumes that the decrease in the apparent surface cross section (delta sigma-zero) is caused by the propagation loss in rain. The coefficient a in the k-Z relationship, k=a Z**b, is adjusted in such a way that the path-integrated attenuation (PIA) estimated from the measured Zm-profile will match the delta sigma-zero. The attenuation correction of Z is carried out by the Hitschfeld-Bordan method with the modified a. Since a is adjusted, this type of surface reference method is called the a-adjustment method. The a-adjustment method assumes that the discrepancy between the PIA estimate from delta sigma-zero and that from the measured Zm-profile can be attributed to the inappropriate choice of a values, which may vary depending on the raindrop size distribution and other conditions. It assumes that the radar is properly calibrated and that the measured Zm has no error. In order to avoid inaccuracies in the attenuation correction when rain is weak, a hybrid of the surface reference method and the Hitschfeld-Bordan method is used (Iguchi and Meneghini, 1994). The PIA is first estimated from the precipitation echo alone. The weight given by the hybrid method to the PIA estimate from the surface reference increases as the attenuation estimate increases. When rain is very weak and the attenuation estimate is small, the PIA estimate from the surface reference is effectively neglected. With the introduction of the hybrid method, the divergence associated with the Hitschfeld-Bordan method is also prevented. One major difference from the method described in the above reference is that, in order to deal with the beam-filling problem, a non-uniformity parameter is introduced and is used to correct the bias in the surface reference arising from the horizontal non-uniformity of rain field within the beam. Since radar echoes from near the surface are contaminated by the mainlobe clutter, the rain estimate at the lowest point in the clutter-free region is given as the near-surface rainfall rate for each angle bin. Spatial coverage is between 38 degrees North and 38 degrees South, owing to the 35 degree inclination of the TRMM satellite. This orbit provides extensive coverage in the tropics and allows each location to be covered at a different local time each day, enabling the analysis of the diurnal cycle of precipitation. There are, in general, 9150 scans along the orbit, with each scan consisting of 49 rays. The scan width is about 220 km. The data are stored in the Hierarchical Data Format (HDF), which includes both core and product specific metadata applicable to the PR measurements. A fi...
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BUV/Nimbus-04 Ozone (O3) Profile and Total Column Ozone Monthly L3 Global 5.0deg Lat Zones V1
nasa-test-0.demo.socrata.com | Last Updated 2015-07-20T05:06:01.000ZThe Solar Backscattered Ultra Violet (SBUV) from Nimbus-4 Level-3 monthly zonal mean (MZM) product (BUVN04L3zm) is derived from the Level-2 retrieved ozone profiles. Ozone retrievals are generated from the v8.6 SBUV algorithm. A Level-3 MZM file computes zonal means covering 5 degree latitude bands for each calendar month. For this product there are 72 months of data from May 1970 through April 1976. There are a total of 36 latitudinal bands, 18 in each hemisphere. Profile data are provided at 21 layers from 1013.25, 639.318, 403.382,254.517, 160.589, 101.325,63.9317, 40.3382, 25.4517, 16.0589, 10.1325, 6.39317,4.03382, 2.54517, 1.60589, 1.01325,0.639317, 0.403382, 0.254517, 0.160589 and 0.101325 hPa (measured at bottom of layer). NOTE: Some profiles have 20 layers and do not report the top most layer. Mixing ratios are reported at 15 layers from 0.5, 0.7, 1.0, 1.5, 2.0, 3.0, 4.0, 5.0, 7.0, 10.0, 15.0, 20.0, 30.0, 40.0 and 50.0 hPa (measured at middle of layer). The MZM product averages retrievals that meet the criteria for a good retrieval as determined by error flags in the Level 2 data. A good retrieval is defined as satisfying the following conditions: 1) Profile Error Flag = 0 or 1 (0 = good retrieval; 1 = solar zenith angle > 84 deg.) 2) Total Error Flags = 0, 1, 2 or 5 (0 = good retrieval; 1 = not used; 2 = solar zenith angle > 84 deg; large discrepancy between profile total and best total ozone) NOTE - Total error flag = 5 is anomalously applied at high latitudes and high solar zenith angle where B-Pair total ozone estimate is not as reliable as profile under these conditions. This error flag may be removed in future version of algorithm. The zonal means computed for each month are screened according to the following statistical criteria: 1) number of good retrievals for the month greater than or equal to 2/3 of the samples for a nominal month. 2) mean latitude of good retrievals less than or equal to 1 degree from center of latitude band. 3) mean time of good retrievals less than or equal to 4 days from center of month (i.e., day = 15)
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Gridded Population of the World, Version 2 (GPWv2)
nasa-test-0.demo.socrata.com | Last Updated 2015-07-19T08:03:40.000ZGridded Population of the World, Version 2 (GPWv2) consists of estimates of human population for the years 1995 and 1990 by 2.5 arc-minute grid cells. The data products are population counts (raw counts), population densities (per square km), and land area (actual area net of ice and water), all of which are available in two GIS-compatible data formats at the global, continent (Antarctica not included), and country levels. A proportional allocation gridding algorithm, utilizing 127,105 national and sub-national administrative units, is used to assign population values to grid cells. Advantages to GPWv2 include higher quality data from the U.S., Africa, Australia, Canada, Europe, Russia, New Zealand, and India; 8 times the number of administrative units; national population estimates that have been adjusted to match the United Nations national estimated population for each country; a proportional allocation algorithm that reduces error with multiple input polygons; and higher spatial resolution. GPWv2 is produced by the Columbia University Center for International Earth Science Information Network (CIESIN) in collaboration with the International Food Policy Research Institute (IFPRI) and the World Resources Institute (WRI). (Suggested Usage: To serve a wide user community by providing the latest data on human population distribution that can be used in interdisciplinary studies of the environment.)