Evidence for parallel elongated structures in the mesosphere

The physical cause of partial reflection from the mesosphere is of interest. Data are presented from an image-forming radar at Brighton, Colorado, that suggest that some of the radar scattering is caused by parallel elongated structures lying almost directly overhead. Possible physical sources for such structures include gravity waves and roll vortices

Will It be a Tough Year?

While there may be some glimmers of hope about a turnaround to the U.S. economy, such as decreasing unemployment, Virginia CPAs aren\u27t betting on a huge recovery in the next year. The second annual VSCPA Economic Outlook Survey reveals Virginia CPAs are more pessimistic about the United States and Virginia economies than they were last year, but they are actually more optimistic about Virginia\u27s economy compared to the United States as a whole. Likewise, VSCPA members continue to feel good about the economic outlook in Virginia relative to neighboring states

Influence of Forming Rate on the Microstructure and Properties of Materials Subjected to Electromagnetic Forming

Electromagnetic high speed forming has been known since the 1960's and is successfully used for frictional connexions. In addition to joining, other applications of the process include coining, stamping and cutting. Regarding product quality and manufacturing costs, the process is superior to other methods and yet its utilisation can still be extended. The synopsis of the material's microstructure and properties owing to electromagnetic forming, which is given by this article, clarifies the processes from a materials science point of view. This will not only represent an academic view point but also provide insight into a potential expansion of the process to other areas of application

Effects of Electromagnetic and Hydraulic Forming Processes on the Microstructure of the Material

Over the past few years, various papers have been published in the field of high speed forming processes. The focus was mainly on the technological aspects of metal forming, however. Therefore, the present contribution puts an emphasis on transmission electron microscopy analyses. The present research work describes the effects of the two forming processes upon the aluminum microstructure and their influence on the material properties. The objective is to characterise the micro processes determining the plastic deformation with both forming velocities the electromagnetic high speed forming process with strain rates of 10,000 s^(-1) and the bulge test, having deformation rates of less than 0.1 s^(-1) as a quasistatic process. In this article sheet metals out of technical pure aluminum 99.5% with a thickness of 1 mm were investigated. To this end, sample specimens were taken from manufactured workpieces along the radius at various distances from the center. Because of the similarity of the forming paths, two places on the specimens manufactured at different forming rates were evaluated and compared to each other: immediately next to the blankholder and from the area of maximum strain. Metallographic tests of the structures, the sheet thickness, and the micro hardness distribution of the initial state and the formed sheet metals were executed in advance

Design analysis of levitation facility for space processing applications

Containerless processing facilities for the space laboratory and space shuttle are defined. Materials process examples representative of the most severe requirements for the facility in terms of electrical power, radio frequency equipment, and the use of an auxiliary electron beam heater were used to discuss matters having the greatest effect upon the space shuttle pallet payload interfaces and envelopes. Improved weight, volume, and efficiency estimates for the RF generating equipment were derived. Results are particularly significant because of the reduced requirements for heat rejection from electrical equipment, one of the principal envelope problems for shuttle pallet payloads. It is shown that although experiments on containerless melting of high temperature refractory materials make it desirable to consider the highest peak powers which can be made available on the pallet, total energy requirements are kept relatively low by the very fast processing times typical of containerless experiments and allows consideration of heat rejection capabilities lower than peak power demand if energy storage in system heat capacitances is considered. Batteries are considered to avoid a requirement for fuel cells capable of furnishing this brief peak power demand

1881 Proceedings of the Ecumenical Methodist Conference

https://place.asburyseminary.edu/wmcproceedings/1007/thumbnail.jp

Bistability of Slow and Fast Traveling Waves in Fluid Mixtures

The appearence of a new type of fast nonlinear traveling wave states in binary fluid convection with increasing Soret effect is elucidated and the parameter range of their bistability with the common slower ones is evaluated numerically. The bifurcation behavior and the significantly different spatiotemporal properties of the different wave states - e.g. frequency, flow structure, and concentration distribution - are determined and related to each other and to a convenient measure of their nonlinearity. This allows to derive a limit for the applicability of small amplitude expansions. Additionally an universal scaling behavior of frequencies and mixing properties is found. PACS: 47.20.-k, 47.10.+g, 47.20.KyComment: 4 pages including 5 Postscript figure

Influence of the Soret effect on convection of binary fluids

Convection in horizontal layers of binary fluids heated from below and in particular the influence of the Soret effect on the bifurcation properties of extended stationary and traveling patterns that occur for negative Soret coupling is investigated theoretically. The fixed points corresponding to these two convection structures are determined for realistic boundary conditions with a many mode Galerkin scheme for temperature and concentration and an accurate one mode truncation of the velocity field. This solution procedure yields the stable and unstable solutions for all stationary and traveling patterns so that complete phase diagrams for the different convection types in typical binary liquid mixtures can easily be computed. Also the transition from weakly to strongly nonlinear states can be analyzed in detail. An investigation of the concentration current and of the relevance of its constituents shows the way for a simplification of the mode representation of temperature and concentration field as well as for an analytically manageable few mode description.Comment: 30 pages, 12 figure

Measurement of two-halo neutron transfer reaction p(11^{11}Li,9^{9}Li)t at 3AA MeV

The p(\nuc{11}{Li},\nuc{9}{Li})t reaction has been studied for the first time at an incident energy of 3$A$ MeV delivered by the new ISAC-2 facility at TRIUMF. An active target detector MAYA, build at GANIL, was used for the measurement. The differential cross sectionshave been determined for transitions to the \nuc{9}{Li} ground andthe first excited states in a wide range of scattering angles. Multistep transfer calculations using different \nuc{11}{Li} model wave functions, shows that wave functions with strong correlations between the halo neutrons are the most successful in reproducing the observation.Comment: 6 pages, 3 figures, submitted to Physical Review Letter