Communications payload concepts for geostationary facilities

Summarized and compared are the major results of two NASA sponsored studies that defined potential communication payload concepts to meet the satellite traffic forecast for the turn of the century for the continental US and Region 2 of the International Telecommunications Union. The studies were performed by the Ford Aerospace and Communications Corporation and RCA Astro-Electronics (now GE-RCA Astro-Space Division). Future scenarios of aggregations of communications services are presented. Payload concepts are developed and defined in detail for nine of the scenarios. Payload costs and critical technologies per payload are also presented. Finally the payload concepts are compared and the findings of the reports are discussed

Thermal and cryogenic design study for space infrared telescope facility (SIRTF)

A study was conducted to determine the ability of an all superfluid helium design to meet the performance requirements of background limited to 200 micrometer, and a two year lifetime for a one meter class free flying infrared observatory. Both a 98 deg and 28.5 deg inclination orbits were examined, and aperture shade designs were developed for both orbits. A unique forebaffle cooling design significantly reduces the sensitivity to aperture heat loads. With certain restrictions on observing modes, the study determined that an all superfluid helium Dewar will meet the temperature and lifetime requirements. A dual cryogen SFHe/SH2 system was also investigated for the 28.5 deg orbit and found to provide a more constant forebaffle temperature but with only a slight improvement in lifetime

Deriving Landscape-Scale Vegetation Cover and Aboveground Biomass in a Semi-Arid Ecosystem Using Imaging Spectroscopy

Environmental disturbances in semi-arid ecosystems have highlighted the need to monitor current and future vegetation conditions across the landscape. Imaging spectroscopy provide the necessary information to derive vegetation characteristics at high-spatial resolutions across large geographic areas. The work of this thesis is divided into two sections focused on using imaging spectroscopy to estimate and classify vegetation cover, and approximate aboveground biomass in a semi-arid ecosystem. The first half of this thesis assesses the ability of imaging spectroscopy to derive vegetation classes and their respective cover across large environmental gradients and ecotones often associated with semi-arid ecosystems. Optimal endmember selection and endmember bundling are coupled with classification and spectral unmixing techniques to derive vegetation species and abundances across Reynolds Creek Experimental Watershed (RCEW) in southwest Idaho at high spatial resolution (1 m). Results validated using field data indicated classification of aspen, Douglas fir, juniper, and riparian classes had an overall accuracy of 57.9% and a kappa coefficient of 0.43. Plant functional type classification, consisting of deciduous and evergreen trees, had an overall accuracy of 84.4% and a kappa coefficient of 0.68. Shrub, grass, and soil cover were predicted with an overall accuracy of 67.4% and kappa coefficient of 0.53. I conclude that imaging spectroscopy can be used to map vegetation communities in semi-arid ecosystems across large environmental gradients at high-spatial resolution and with high accuracy. The second half of this thesis focuses on monitoring the changes of aboveground biomass (AGB) from the 2015 Soda Fire, which burned portions of southwest Idaho and southeastern Oregon. Classifications derived in the first study are used to estimate AGB loss within a portion of RCEW, and these estimates are used to compare to gross estimates made over the full extent of the Soda Fire. I found that there was an AGB loss of 174M kg within RCEW and approximately 1.8B kg lost over the full extent of the Soda Fire. Additionally, a post-fire analysis was performed to provide insight into the amount of AGB that returned to both RCEW and the full extent of the Soda Fire. An estimated 2,100 – 208,000 kg of AGB had returned to the burned portion of RCEW one-year post fire, and approximately 3.2M kg of AGB had returned over the full extent of the Soda Fire. These AGB loss and re-growth estimates can be used by researchers and practitioners to monitor carbon flux across the Soda Fire and as baseline data for wildfires in semi-arid ecosystems

Demand for satellite-provided domestic communications services up to the year 2000

Three fixed service telecommunications demand assessment studies were completed for NASA by The Western Union Telegraph Company and the U.S. Telephone and Telegraph Corporation. They provided forecasts of the total U.S. domestic demand, from 1980 to the year 2000, for voice, data, and video services. That portion that is technically and economically suitable for transmission by satellite systems, both large trunking systems and customer premises services (CPS) systems was also estimated. In order to provide a single set of forecasts a NASA synthesis of the above studies was conducted. The services, associated forecast techniques, and data bases employed by both contractors were examined, those elements of each judged to be the most appropriate were selected, and new forecasts were made. The demand for voice, data, and video services was first forecast in fundamental units of call-seconds, bits/year, and channels, respectively. Transmission technology characteristics and capabilities were then forecast, and the fundamental demand converted to an equivalent transmission capacity. The potential demand for satellite-provided services was found to grow by a factor of 6, from 400 to 2400 equivalent 36 MHz satellite transponders over the 20-year period. About 80 percent of this was found to be more appropriate for trunking systems and 20 percent CPS

Impact of Balance Of System (BOS) costs on photovoltaic power systems

The Department of Energy has developed a program to effect a large reduction in the price of photovoltaic modules, with significant progress already achieved toward the 1986 goal of 50 cents/watt (1975 dollars). Remaining elements of a P/V power system (structure, battery storage, regulation, control, and wiring) are also significant cost items. The costs of these remaining elements are commonly referred to as Balance-of-System (BOS) costs. The BOS costs are less well defined and documented than module costs. The Lewis Research Center (LeRC) in 1976/77 and with two village power experiments that will be installed in 1978. The costs were divided into five categories and analyzed. A regression analysis was performed to determine correlations of BOS Costs per peak watt, with power size for these photovoltaic systems. The statistical relationship may be used for flat-plate, DC systems ranging from 100 to 4,000 peak watts. A survey of suppliers was conducted for comparison with the predicted BOS cost relationship

Effects of Energy Supplementation of Corn-oat Rations for Growing-Finishing Swine

According to the South Dakota Crop and Livestock Reporting Service of the United States Department of Agriculture in 1960 South Dakota ranked third in the nation in the production of oats. Twenty-four percent of all grains produced in South Dakota was oats. The efficient utilization of oats is therefore important. One of the limiting factors in the use of oats for growing pigs is their low available energy. Animal fats are relatively high in energy. In recent years animal fats have become a surplus item due to their reduced industrial use. This surplus has resulted in low fat prices in relation to other feed ingredients. Feed manufacturers use fat in considerable amounts to reduce dustiness, increase pellet production, and improve the life of pelleting equipment. Many of the earlier studies with lipids in swine rations were aimed at proving them unnecessary and undesirable. Maynard (1935) stated that there was an absence of any interest in feeding fat to swine, aside from its relation to the soft pork problem, and that the content of this nutrient in rations was determined largely by the demand for fat by manufacturing industries which had established a trend resulting in the removal of fat from feed ingredients. He went on to review numerous studies emphasizing the detrimental effect of fats and fatty constituents as well as the fact that very little was needed in the ration. The purpose of these studies was to determine whether or not increased energy by the use of animal fat additions would improve the feeding value of rations containing a high level of oats, and if adjustments in protein would be beneficial with this increased energy. Rate of gain, feed efficiency, and carcass evaluations were used in determining this feeding value

Optimization of the plasma start-up of the Seville spherical tokamak (SMART)

The SMall Aspect Ratio Tokamak (SMART) is currently being designed by the Plasma Science and Fusion Technology Group (PSFT) of the University of Seville. Therefore, several simulations and calculations regarding the di erent aspects of the reactor are needed. SMART is an experimental fusion reactor based on magnetic con nement, which has an aspect ratio (A) of >1.6, that classi es it as a spherical tokamak. Moreover, it has a central solenoid, which induces the toroidal electric eld to the plasma, two divertor coil sets and two poloidal eld coil sets. During this bachelor thesis simulations of the plasma startup in SMART has been carried out. A study optimizing the current of the solenoid and poloidal eld coils has been performed. Furthermore, an analysis of the suitable wall width for the outer, top and bottom walls studying the main parameters involved in the startup process such as the connection length (L) is conducted. Finally, the necessary electric eld to have a reliable breakdown is studied.El grupo "Plasma Science and Fusion Technology Group" (PSFT) de la Universidad de Sevilla está actualmente diseñando el reactor de fusión "SMall Aspect Ratio Tokamak" (SMART). Por lo tanto, se necesitan gran cantidad de simulaciones y cálculos sobre los diferentes aspectos del reactor. La relación de aspecto (A) en SMART es de >1,6, lo que lo clasifica como un tokamak esférico. Además, tiene un solenoide central, que induce el campo eléctrico toroidal al plasma, dos pares de bobinas divertoras y dos pares de anillos de campo poloidal. A lo largo de este trabajo de fin de grado se llevan a cabo distintas simulaciones del arranque del plasma en SMART. Se hace a su vez un estudio para optimizar la corriente de las bobinas del solenoide y del campo poloidal. Asimismo, se realiza un análisis de sobre cuál es el grosor adecuado para las paredes exteriores, superiores e inferiores, estudiando los principales parámetros que intervienen en el proceso de arranque, como la longitud de la conexión (L). Por último, se estudiará el campo eléctrico necesario para tener un "breakdown" que sea fiable.Universidad de Sevilla. Grado en Físic