Photovoltaic power system tests on an 8-kilowatt single-phase line-commutated inverter

Efficiency and power factor were measured as functions of solar array voltage and current. The effects of input shunt capacitance and series inductance were determined. Tests were conducted from 15 to 75 percent of the 8 kW rated inverter input power. Measured efficiencies ranged from 76 percent to 88 percent at about 50 percent of rated inverter input power. Power factor ranged from 36 percent to 72 percent

System tests with electric thruster beam and accelerator directly powered from laboratory solar arrays

Laboratory high voltage solar arrays were operated directly connected to power the beam and accelerator loads of an 8-centimeter ion thruster. The beam array comprised conventional 2 by 2 centimeter solar cells; the accelerator array comprised multiple junction edge-illuminated solar cells. Conventional laboratory power supplies powered the thruster's other loads. Tests were made to evaluate thruster performance and to investigate possible electrical interactions between the solar arrays and the thruster. Thruster performance was the same as with conventional laboratory beam and accelerator power supplies. Most of the thruster beam short circuits that occurred during solar array operation were cleared spontaneously without automatic or manual intervention. No spontaneous clearing occurred during conventional power supply operation

Bit error rate testing of a proof-of-concept model baseband processor

Bit-error-rate tests were performed on a proof-of-concept baseband processor. The BBP, which operates at an intermediate frequency in the C-Band, demodulates, demultiplexes, routes, remultiplexes, and remodulates digital message segments received from one ground station for retransmission to another. Test methods are discussed and test results are compared with the Contractor's test results

Time Resolved Spectroscopy Of Cataclysmic Variables - SS Cygni

NSF AST76-23882, AST 79-06340McDonald Observator

Youth Sport Concussion Management

As knowledge about concussions increases and more is being discovered regarding the lasting effects of concussions, youth sport coaches need to be better informed and educated on the signs and symptoms, the management of concussions, and return-to-play procedures. This research examines what coaches of youth athletes (5-14 years of age) know about concussions and concussion management. Semi-structured interviews with coaches were conducted and analyzed in order to develop recommendations for effective training tools to help coaches identify and properly manage youth sport concussions. Results from the interviews found that coaches need more training on the long-term symptoms of concussions. The training should also include proper concussion management steps to take because coaches seemed to miss a few key steps in the management process. The results also indicated that a training should be required for parents and players

Soil Homogenization: Plant Species Diversity, Ecosystem Properties and Soil Freezing Effects During Tallgrass Prairie Restoration

Tillage can increase soil uniformity in former agricultural sites. Within plant communities, niche-based species sorting may occur among distinct soil patches (microsites), increasing diversity, and the interfaces between microsites (microedges) also may provide unique microsites. However, the influence of soil homogenization and microedges on ecosystem processes and plant responses to stress have not been examined. My thesis assessed if adding microsites containing sand, woodchips, pits or mounds increased plant species diversity, productivity, decomposition and nitrogen retention (15N tracer) and buffered plant responses to soil freezing in a tallgrass prairie restoration on former cropland. Homogenization decreased diversity in flat topsoil plots relative to topographically heterogeneous plots with pits and in the sand treatment, but increased diversity in the woodchip treatment. Homogenization reduced aboveground productivity and plant 15N retention for the woodchip treatment and increased the rate of litter decomposition. Variation in diversity and ecosystem responses were associated with effects on plant production, suggesting that the influence of soil homogenization may occur indirectly via effects on productivity. Elevated levels of plant cover and 15N retention along microedges occurred, indicating microedges may act as unique microsites and small scale ecological transition zones. Soil homogenization increased the sensitivity of total plant cover to frost stress in the sand treatment and this effect appeared to be driven by greater severity of frost stress in sand versus topsoil microsites in the heterogeneous treatment. My results indicate addition of microsites could be used to benefit plant community stability and diversity during ecological restoration

AN ADDITIONAL RECORD OF THE ORNATE BOX TURTLE FROM WESTERN SOUTH DAKOTA

On 11 June 2003, one of us (EJS) found an ornate box turtle crossing BIA Highway 2, approximately 7.2 km north of Sharps Comer on the Pine Ridge Indian Reservation in Shannon County, South Dakota. The air temperature at the time of collection was approximately 30°C, and the substrate was moist from light rain the previous day. The turtle was an adult female with a straight-line carapace length of 118 mm. Other straight-line measurements were: maximum carapace width = 100 mm; plastron length = 122 mm; maximum plastron width = 82 mm; and maximum shell depth = 64 mm. We deposited voucher photographs (CUSC 2166) of the turtle in the Campbell Museum, Clemson University, Clemson, South Carolina. Our specimen constitutes the first record of the ornate box turtle from Shannon County, and represents the westernmost occurrence of this species yet documented in South Dakota (Ballinger et al. 2000)

Letters between Arthur Stover and W. J. Kerr

Letters concerning a position in the engineering department at Utah Agricultural College

Designing Dental Student Portfolios to Assess Performance

The purpose of this poster is to share a project developed by Marquette University’s liaisons to the American Dental Education Association’s Commission on Change and Innovation in Dental Education with others interested in learning about the use of portfolios to assess the quality of student performance in dental school. Sample components from the pilot portfolios will be integrated into the poster to provide participants with a view from portfolio design to completion. Portfolios are becoming a more common method of assessing the quality of student performance in health professions education. Portfolios can assist in documenting evidence of specific competencies at the student level and also serve as a longitudinal measure of a student’s development

Best combiners during 40 years of breeding Vitis cuitivars resistant to Pierce's disease

By breeding for resistance to Pierce's disease in Vitis we have obtained useful cultivars that can be grown productively in areas formerly considered unsuitable for grape production. Reviewing the most successful recombinants from crosses made between 1945 and 1984, 6 Vitis clones were prominent foundation parents among those tested as primitive resistant germplasm: V. aestivalis, ssp. smalliana cvs Fla. 43-47 and Fla. 449, V. aestivalis ssp. simpsoni cvs Pixiola and Fla. 451, and V. shuttleworthii cvs Haines City and Kissimmee. The best combiners for productivity, fruit size, and high quality were PD susceptible cultivars Aurelia, Carolina Blackrose, Cardinal, Exotic, Golden Muscat, and Villard blanc. The best combiners for seedlessness and early ripening were susceptible cultivars Lakemont and Perlette. Selection for resistance to PD required 7 or more years each generation for exposure of seedlings to PD-carrying vectors. Inbreeding was detrimental to vine vigor but good combiners were selected among inbred progeny which were more homozygous for disease resistance. Subsequent crosses of these inbreds to large-fruited, high-quality cultivars resulted in some recombinants with restored vigor and superior traits such as Blanc Du Bois