62,028 research outputs found
Is There a Role for Producer and Consumer Subsidy Equivalents in Trade Negotiations
International Relations/Trade,
Statutory Strict Liability for an Insurer’s Failure to Settle: A Balanced Plan for an Unresolved Problem
Demonstration of the feasibility of automated silicon solar cell fabrication
A study effort was undertaken to determine the process, steps and design requirements of an automated silicon solar cell production facility. Identification of the key process steps was made and a laboratory model was conceptually designed to demonstrate the feasibility of automating the silicon solar cell fabrication process. A detailed laboratory model was designed to demonstrate those functions most critical to the question of solar cell fabrication process automating feasibility. The study and conceptual design have established the technical feasibility of automating the solar cell manufacturing process to produce low cost solar cells with improved performance. Estimates predict an automated process throughput of 21,973 kilograms of silicon a year on a three shift 49-week basis, producing 4,747,000 hexagonal cells (38mm/side), a total of 3,373 kilowatts at an estimated manufacturing cost of 1.22 per watt
Exobiology and the search for biological signatures on Mars
In preparation for a Mars Rover/Sample return mission, the mission goals and objectives must be identified. One of the most important objectives must address exobiology and the question of the possibility of the origin and evolution of life on Mars. In particular, key signatures or bio-markers of a possible extinct Martian biota must be defined. To that end geographic locations (sites) that are likely to contain traces of past life must also be identified. Sites and experiments are being defined in support of a Mars rover sample return mission. In addition, analyses based on computer models of abiotic processes of CO2 loss from Mars suggest that the CO2 from the atmosphere may have precipitated as carbonates and be buried within the Martian regolith. The carbon cycle of perennially frozen lakes in the dry valley of Antarctica are currently being investigated. These lakes were purported to be a model system for the ancient Martian lakes. By understanding the dynamic balance between the abiotic vs. biotic cycling of carbon within this system, information is gathered which will enable the interpretation of data obtained by a Mars rover with respect to possible carbonate deposits and the processing of carbon by biological systems. These ancient carbonate deposits, and other sedimentary units would contain traces of biological signatures that would hold the key to understanding the origin and evolution of life on Mars, as well as Earth
Mobility and transverse flow visualization using phase variance contrast with spectral domain optical coherence tomography
Phase variance-based motion contrast is demonstrated using two phase analysis methods in a spectral domain optical coherence tomography system. Mobility contrast is demonstrated for an intensity matched Intralipid solution placed without flow within agarose wells. Vasculature oriented transversely to the imaging direction has been imaged for 3-4 dpf in vivo zebrafish using the phase variance contrast methods. 2D phase variance contrast images are demonstrated with imaging times only 25% higher than a Doppler flow image with comparable statistics. En face images created by integrating depth regions of 3D zebrafish intensity and phase variance contrast data demonstrate vasculature consistent with expected images
DRSS communication considerations for manned space flight
A lower and an upper bound or manned space flight requirements for a data relay satellite system (DRSS) in the 1975-1980 time period are described. In all cases, the most stringent requirement is an intersatellite link to provide wideband information transfer from an overseas DRS to the Continental United States. A parametric communication analysis is made as a function of varying frequency and antenna aperture. The desirability of using a VHF frequency band for low data rates and voice relay and the requirement for frequencies of 8 and 16 GHz for video and wideband digital data relay are shown
Overview: Exobiology in solar system exploration
In Aug. 1988, the NASA Ames Research Center held a three-day symposium in Sunnyvale, California, to discuss the subject of exobiology in the context of exploration of the solar system. Leading authorities in exobiology presented invited papers and assisted in setting future goals. The goals they set were as follows: (1) review relevant knowledge learned from planetary exploration programs; (2) detail some of the information that is yet to be obtained; (3) describe future missions and how exobiologists, as well as other scientists, can participate; and (4) recommend specific ways exobiology questions can be addressed on future exploration missions. These goals are in agreement with those of the Solar System Exploration Committee (SSEC) of the NASA Advisory Council. Formed in 1980 to respond to the planetary exploration strategies set forth by the Space Science Board of the National Academy of Sciences' Committee on Planetary and Lunar Exploration (COMPLEX), the SSEC's main function is to review the entire planetary program. The committee formulated a long-term plan (within a constrained budget) that would ensure a vital, exciting, and scientifically valuable effort through the turn of the century. The SSEC's goals include the following: determining the origin, evolution, and present state of the solar system; understanding Earth through comparative planetology studies; and revealing the relationship between the chemical and physical evolution of the solar system and the appearance of life. The SSEC's goals are consistent with the over-arching goal of NASA's Exobiology Program, which provides the critical framework and support for basic research. The research is divided into the following four elements: (1) cosmic evolution of the biogenic compounds; (2) prebiotic evolution; (3) origin and early evolution of life; and (4) evolution of advanced life
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