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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 271 records · Page 15

Capacity of PPM on Gaussian and Webb Channels

This paper computes and compares the capacities of M-ary PPM on various idealized channels that approximate the optical communication channel: (1) the standard additive white Gaussian noise (AWGN) channel;(2) a more general AWGN channel (AWGN2) allowing different variances in signal and noise slots;(3) a Webb-distributed channel (Webb2);(4) a Webb+Gaussian channel, modeling Gaussian thermal noise added to Webb-distributed channel outputs.

Capacity PPM Webb Optical↗

Capacity of the generalized PPM channel

We show the capacity of a generalized pulse-position-modulation (PPM) channel, where the input vectors may be any set that allows a transitive group of coordinate permutations, is achieved by a uniform input distribution.

modulation↗

Calibration of High Temperature Thermal Conductivity System: New Algorithm to Measure Heat Capacity Using Flash Thermal Diffusivity in Thermoelectric Materials

A viewgraph presentation describing thermoelectric materials, an algorithm for heat capacity measurements and the process of flash thermal diffusivity. The contents include: 1) What are Thermoelectrics?; 2) Thermoelectric Applications; 3) Improving Thermoelectrics; 4) Research Goal; 5) Flash Thermal Diffusivity; 6) Background Effects; 7) Stainless Steel Comparison; 8) Pulse Max Integral; and 9) Graphite Comparison Algorithm.

heat capacity↗

Space Exploration Applications for Development of High Capacity Cryocoolers

Long term storage of cryogens is necessary to enable NASAs long duration crewed missions to both the lunar and Martian surfaces. Such missions require in-space transport systems such as Nuclear Thermal Propulsion (NTP), and descent/ascent vehicles for transportation to and from the lunar and Martian surfaces. NTP systems and Lunar/Martian landers utilize cryogenic fluids to minimize architectural volume and mass. To further enhance the capability of these cryogenic systems, the Agency is putting emphasis on reusability, which requires the NTP and ascent/descent elements be replenished on-orbit via tankers or propellant depots, or on the lunar or Martian surface using liquefied in-situ produced propellants. NTP is one of the leading propulsion option for human Mars missions and requires liquid hydrogen to be stored on-orbit for over four years. For such a long duration mission, near “Zero Boil-Off” (ZBO) must be achieved which requires an optimized suite of passive Cryogenic Fluid Management technologies and active cooling (cryocoolers). Tens of Watts of 20K cooling is required to achieve ZBO conditions for NTP, however two-stage cooling using both 20K and 90K systems can lead to a significant reduction in both active cooling mass and power. The use of in-situ resources for lunar and Martian missions will require 150 Watts of 90K cooling for oxygen liquefaction and 300 Watts of 20K cooling for hydrogen liquefaction (lunar only). Descent/Ascent vehicles, propellant depots, and tankers will also require the use of cryocoolers to achieve ZBO conditions. To support these programs, NASA is developing high capacity 20K and 90K reverse turbo-Brayton cycle cryocoolers which offer a scalable, high efficiency, low vibration solution.

cryocooler↗

Building Capacity to Use Earth Observations for Disaster Risk Reduction and Resilience Applications: A Summary of NASA’s DEVELOP Program and Projects in Central and South America

NASA’s DEVELOP program engages individuals and organizations in 10-week feasibility studies to apply NASA Earth observations (EO) to decision makers’ needs. Since 2018, DEVELOP conducted 21 projects in Central and South America, eight of those in collaboration with Sistema de la Integración Centroamericana (SICA) and its member state partner agencies. These projects addressed a diverse set of community needs across multiple themes, including two focused on disaster risk reduction and resilience using EO for mapping landslide susceptibility in the Dominican Republic and riparian flooding in Guatemala and El Salvador. This poster introduces DEVELOP, its approach to capacity building, key partnerships, and project results highlighting the capabilities of EO for enhanced decision making in the area of reduction of disaster risk and support disaster resilience.

Capacity Building↗

Building Capacity to Use Earth Observations for Ecosystem Services & Biodiversity Applications: A Summary of NASA’s DEVELOP Program and Projects in Central and South America

NASA’s DEVELOP program engages individuals and organizations in 10-week feasibility studies to apply NASA Earth observations (EO) to decision makers’ needs. Since 2018, DEVELOP conducted 21 projects in Central and South America, eight of those in collaboration with Sistema de la Integración Centroamericana (SICA) and its member state partner agencies. These projects addressed a diverse set of community needs across multiple themes, including 11 addressing issues related to biodiversity and ecosystem services that utilized a suite of EO to measure and monitor deforestation, habitat suitability, and land change impacts on watershed health in Peru, Costa Rica, Panama, Honduras, and Colombia. This poster introduces DEVELOP, its approach to capacity building, key partnerships, and project results highlighting the capabilities of EO for enhanced decision making in the area of ecosystem services and biodiversity.

Capacity Building↗

Building Capacity to Use Earth Observations for Agriculture and Food Security Applications: A Summary of NASA’s DEVELOP Program and Projects in Central and South America

NASA’s DEVELOP program engages individuals and organizations in 10-week feasibility studies to apply NASA Earth observations (EO) to decision makers’ needs. Since 2018, DEVELOP conducted 21 projects in Central and South America, eight of those in collaboration with Sistema de la Integración Centroamericana (SICA) and its member state partner agencies. These projects addressed a diverse set of community needs across multiple themes, including two feasibility studies that focused on monitoring drought and precipitation patterns and their impacts on agriculture in Guatemala, Honduras, El Salvador, and Nicaragua using EO from Terra MODIS and GPM. This poster introduces DEVELOP, its approach to capacity building, key partnerships, and project results highlighting the capabilities of EO for enhanced decision making in the area of agriculture and food security.

Capacity Building↗

Building Capacity to Use Earth Observations for Health Applications: A Summary of NASA’s DEVELOP Program and Projects in Central and South America

NASA’s DEVELOP program engages individuals and organizations in 10-week feasibility studies to apply NASA Earth observations (EO) to decision makers’ needs. Since 2018, DEVELOP conducted 21 projects in Central and South America, eight of those in collaboration with Sistema de la Integración Centroamericana (SICA) and its member state partner agencies. These projects addressed a diverse set of community needs across multiple themes, including a project focused on monitoring aerosols using satellite-based measurements from Aqua and Terra MODIS, Suomi NPP VIIRS, and CALIPSO CALIOP and in situ data in El Salvador, Guatemala, and Panama. This poster introduces DEVELOP, its approach to capacity building, key partnerships, and project results highlighting the capabilities of Earth observations for enhanced decision making in the area of health.

Capacity Building↗

Building Capacity to Use Earth Observations for Water Resource Management Applications: A Summary of NASA’s DEVELOP Program and Projects in Central and South America

NASA’s DEVELOP program engages individuals and organizations in 10-week feasibility studies to apply NASA Earth observations (EO) to decision makers’ needs. Since 2018, DEVELOP conducted 21 projects in Central and South America, eight of those in collaboration with Sistema de la Integración Centroamericana (SICA) and its member state partner agencies. These projects addressed a diverse set of community needs across multiple themes, including five that explored the use of both spaceborne and airborne EO to assess coastal water quality related to SDG monitoring of natural resources in Belize and Honduras, evaluating evapotranspiration and water balance in Argentina, and characterizing vegetation water use for informed water management in Panama. This poster introduces DEVELOP, its approach to capacity building, key partnerships, and project results highlighting the capabilities of EO for enhanced decision making in the area of sustainable water management.

Capacity Building↗

NASA DEVELOP’s Approach to Building Individual and Institutional Capacity to Use Earth Observations for Atmospheric Monitoring and Decision Making

NASA DEVELOP, an Applied Sciences’ Capacity Building program, introduces individuals and institutions to the applications of NASA Earth observation data in an effort to help inform decision making. The program employs early career professionals to conduct rapid feasibility studies tailored specific to partner needs. Each year, DEVELOP conducts 50-60 feasibility studies that highlight the capabilities of Earth observations for measuring and monitoring a wide range of environmental phenomena. For this presentation, example projects will be highlighted that focus on monitoring air quality and pollution, wildfire emissions, and greenhouse gasses such as methane. An overview of example projects, the user communities involved, satellite data used, and lessons learned will be shared.

Capacity Building↗

Theoretical and Simulated Capacity of Urban Air Mobility Airspace Characteristics

As interest in urban air mobility grows, as are the optimistic predictions for potentially hundreds of simultaneous operations within a given metropolitan airspace. This high density of traffic poses a challenge for safe, efficient, and timely operations, particularly when realistic airspace restrictions, fleet sizes, and fluctuating demand are considered. Routes for urban air mobility aircraft, similar to automotive roadways more than other types of airways, are one proposed solution for traffic management. This paper identifies several potential components of urban air mobility routes and compares their numerically predicted maximum capacity with what is achieved in a realistic simulation that includes airspace restrictions, parking limitations, fleet sizes, and uneven demand.

Urban Air Mobility↗

Theoretical and Simulated Capacity of Urban Air Mobility Airspace Characteristics

As interest in urban air mobility grows, as are the optimistic predictions for potentially hundreds of simultaneous operations within a given metropolitan airspace. This high density of traffic poses a challenge for safe, efficient, and timely operations, particularly when realistic airspace restrictions, fleet sizes, and fluctuating demand are considered. Routes for urban air mobility aircraft, similar to automotive roadways more than other types of airways, are one proposed solution for traffic management. This paper identifies several potential components of urban air mobility routes and compares their numerically predicted maximum capacity with what is achieved in a realistic simulation that includes airspace restrictions, parking limitations, fleet sizes, and uneven demand.

Urban Air Mobility↗

NASA Engineering and Safety Center Technical Bulletin No. 11-01: Nickel-Hydrogen (NiH 2 ) Common Pressure Vessel (CPV) Cell Capacity Loss and Voltage Collapse

During an investigation of anomalous voltages during a NASA scientific mission, a NASA Engineering and Safety Center (NESC) team discovered that the design of NiH 2 CPV batteries may be susceptible to a unique electrolyte bridging between the two internal cells resulting in undesired ionic current flow. This condition can lead to depletion of the capacity within one of the two cells.

Nickel-Hydrogen↗