Performance of ceramic superconductors in magnetic bearings

Magnetic bearings are large-scale applications of magnet technology, quite similar in certain ways to synchronous machinery. They require substantial flux density over relatively large volumes of space. Large flux density is required to have satisfactory force density. Satisfactory dynamic response requires that magnetic circuit permeances not be too large, implying large air gaps. Superconductors, which offer large magnetomotive forces and high flux density in low permeance circuits, appear to be desirable in these situations. Flux densities substantially in excess of those possible with iron can be produced, and no ferromagnetic material is required. Thus the inductance of active coils can be made low, indicating good dynamic response of the bearing system. The principal difficulty in using superconductors is, of course, the deep cryogenic temperatures at which they must operate. Because of the difficulties in working with liquid helium, the possibility of superconductors which can be operated in liquid nitrogen is thought to extend the number and range of applications of superconductivity. Critical temperatures of about 98 degrees Kelvin were demonstrated in a class of materials which are, in fact, ceramics. Quite a bit of public attention was attracted to these new materials. There is a difficulty with the ceramic superconducting materials which were developed to date. Current densities sufficient for use in large-scale applications have not been demonstrated. In order to be useful, superconductors must be capable of carrying substantial currents in the presence of large magnetic fields. The possible use of ceramic superconductors in magnetic bearings is investigated and discussed and requirements that must be achieved by superconductors operating at liquid nitrogen temperatures to make their use comparable with niobium-titanium superconductors operating at liquid helium temperatures are identified

Effects of squash leaf trichome exudates and honey on adult feeding, survival, and fecundity of the squash bug (Heteroptera: Coreidae) egg parasitoid Gryon pennsylvanicum (Hymenoptera: Scelionidae)

Citation: Olson, D., & Nechols, J. Effects of Squash Leaf Trichome Exudates and Honey on Adult Feeding, Survival, and Fecundity of the Squash Bug (Heteroptera: Coreidae) Egg Parasitoid Gryon pennsylvanicum (Hymenoptera: Scelionidae). Environmental Entomology, 24(2), 454-458. https://doi.org/10.1093/ee/24.2.454A laboratory experiment was conducted to determine whether leaf exudates could be used as a source of adult nutrition for the squash bug, Auasa tristis (De Geer), egg parasitoid, Gryon pennsylvanicum (Ashmead), and to compare adult and progeny fitness traits when female Wasps were provided with squash leaves, a standard honey diet, a combination of leaves and honey, or water only Results showed that fecundity, progeny developmental rates, and progeny survival did not differ significantly when females were exposed to different dietary sources. Adult longevity was shorter on squash leaves without honey than on leaves with honey or the honey-only diet. However, reproductive fitness was not reduced because oviposition had been completed before death of the adult females. When only water was provided, parasitoid females lived only a few days. Observations showed that squash leaves have two kinds of trichomes (hair-like and peg-like), both of which produce droplets that are fed on by both sexes of G. pennsylvanicum. Nutrient analyses revealed that exudates from the hair-like trichomes are composed predominantly of monosaccharides (mainly glucose and galactose), and that the peg-like trichomes produce glucose and some protein. Thus, these trichomes appear to serve as extrafloral nectaries and may provide an important energy source for augmentatively released G. pennsylvanicum

Large space systems technology program

Technical challenges of shuttle-era large space systems include the development of space-configured spacecraft concepts, compatibility with the space transportation system, and cost effectiveness. The objectives and organization of NASA's large space structures program are outlined and program elements are discussed. The technology for the offset wrap-rip and the maypole (hoop/column) antenna concepts are discussed as well as analysis techniques for predicting the electromagnetic performance of a broad class of large reflectors. Deployable systems, assembly methods, and modular control systems for space platforms are described. Assembly equipment and devices, surface sensors and shape control, control and stabilization, and integrated analysis and design are also considered

Recent Changes in State and Local Funding for Education in Georgia

This report examines how the 2001 recession affected K-12 education spending in Georgia school systems. FRC Report 20

Liophis ceii

Number of Pages: 2Integrative BiologyGeological Science

Comparisons between the squash bug egg parasitoids Ooencyrtus anasae and O. sp. (Hymenoptera: Encyrtidae): development, survival,and sex ratio in relation to temperature

Citation: Tracy, J. L., and J. R. Nechols. 1987. “Comparisons Between the Squash Bug Egg Parasitoids Ooencyrtus Anasae and O. Sp. (Hymenoptera: Encyrtidae): Development, Survival, and Sex Ratio in Relation to Temperature.” Environmental Entomology 16 (6): 1324–29. https://doi.org/10.1093/ee/16.6.1324.Laboratory investigations of the gregarious squash bug egg parasitoids Ooencyrtus anasae and O. n. sp. near anasae (O. sp.) were conducted at 20.8, 23.0, and 26.6°C. In both species, total developmental periods (egg to eclosed adult) were inversely related to temperature. Temperature had no significant influence on survivorship, progeny production, or sex ratio. At each temperature, O. anasae developed and emerged about a day earlier and produced a significantly higher percentage of female progeny (77%) than did O. sp. (60%). Both parasitoids deposited an average of three (2-7) progeny per host. However, O. anasae consistently deposited more female eggs per host than did O. sp. Proportion of females produced per host by O. anasae tended to increase directly with number of hosts parasitized, but no such relationship was observed in O. sp. Total preimaginal survivorship in both parasitoids was about 89%. In O. sp., male progeny that developed without females emerged about a day later at all temperatures and had a lower pharate adult survivorship than did males that developed in hosts with female siblings

The Price Effect of Georgia's Temporary Suspension of State Fuel Taxes

This report explores the effect of the fuel tax suspension on the price of gasoline in Georgia. FRC Report 14

Citizen Soldiers: The North Carolina Volunteers and the War on Poverty

During the summers of 1964 and 1965, more than 300 college students fanned out across the state of North Carolina in a bold campaign to defeat poverty and, as they saw it, to uplift the poor. Korstad and Leloudis trace the history of the North Carolina Fund\u27s Volunteers program, provide an analysis of the contribution that those students made to fighting poverty in the state, and evaluate the impact of that experience on the lives of the Volunteers themselves

The Price Effect of Georgia's Temporary Suspension of State Fuel Taxes - Brief

This report explores the effect of the fuel tax suspension on the price of gasoline in Georgia. FRC Brief 14

Liophis jaegeri

Number of Pages: 4Integrative BiologyGeological Science