4,450 research outputs found
Large solar arrays
A spectrophotovoltaic converter, a thermophotovoltaic converter, a cassegrainian concentrator, a large silicon cell blanket, and a high flux approach are among the concepts being investigated as part of the multihundred kW solar array program for reducing the cost of photovoltaic energy in space. These concepts involve a range of technology risks, the highest risk being represented by the thermophotovoltaics and spectrophotovoltaics approaches which involve manipulation to of the incoming spectrum to enhance system efficiency. The planar array (solar blanket) has no technology risk and a moderate payback. The primary characteristics, components, and technology concerns of each of these concepts are summarized. An orbital power platform mission in the late 1980's is being used to allow a coherent technology advancement program in order to achieve a ten year life with maintenance at a capital recurring cost of $30/watt based on 1978 dollars
Solar array systems
The recent past, present state-of-the-art, and future needs in the area of large photovoltaic solar arrays are discussed. In the past most attention was focused upon performance whereas in the future most of the effort should go into cost reduction. Suggestions are made regarding possible approaches to reducing cost such as on-orbit maintenance, extended lifetime, solar concentrators, and high-voltage modular concepts
Toward better minimum tillage for south-coastal sandplain soils
Seventeen farmers compared their conventional cropping practices with some form of minimum tillage cropping. The minimum tilled crops yielded 21 percent less grain than the conventionally sown crops. The reasons for these decreased yields were in most cases related to inexperienced management. The minimum tilled treatments usually had very poor weed kill strategies which often resulted in large weeds at sowing, very cloddy seed-beds, and numerous insects in the young crops
Records for the Utilization of \u3ci\u3ePrunus\u3c/i\u3e as a Larval Foodplant by 71 Species of Lepidoptera in Northeast California
Twenty-six sites in five northeastern California counties (Shasta, Modoc, Plumas, Lassen, Tehama) were surveyed from 1991 to 1999 for the presence of lepidopteran larvae on naturally occurring shrubs of the genus Prunus. To date, a total of seventy-one species of Lepidoptera from seventeen families have been documented to utilize one or more of the area’s three Prunus species (P. emarginata, P. subcordata, and P. virginiana var. demissa)
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