100,834 research outputs found
Synthesis of atactic and stereoregular vinylaromatic polymers and a study of their reactions with alkali metals Final report
Synthesis and characteristics of atactic and stereoregular vinylaromatic polymers and their reactions with alkali metal
Silicon halide-alkali metal flames as a source of solar grade silicon
The feasibility of using alkali metal-silicon halide diffusion flames to produce solar-grade silicon in large quantities and at low cost is demonstrated. Prior work shows that these flames are stable and that relatively high purity silicon can be produced using Na + SiCl4 flames. Silicon of similar purity is obtained from Na + SiF4 flames although yields are lower and product separation and collection are less thermochemically favored. Continuous separation of silicon from the byproduct alkali salt was demonstrated in a heated graphite reactor. The process was scaled up to reduce heat losses and to produce larger samples of silicon. Reagent delivery systems, scaled by a factor of 25, were built and operated at a production rate of 0.5 kg Si/h. Very rapid reactor heating rates are observed with wall temperatures reaching greater than 2000 K. Heat release parameters were measured using a cooled stainless steel reactor tube. A new reactor was designed
Determining masses of supersymmetric particles
If supersymmetric particles are produced at the Large Hadron Collider it
becomes very important not only to identify them, but also to determine their
masses with the highest possible precision, since this may lead to an
understanding of the SUSY-breaking mechanism and the physics at some higher
scale. We here report on studies of how such mass measurements are obtained,
and how the precision can be optimized.Comment: 11 pages, contribution to the proceedings "II. Southeastern European
Workshop Challenges Beyond The Standard Model", 19-23 May 2005, Vrnjacka
Banja, Serbi
Resolving ambiguities in mass determinations at future colliders
The measurements of kinematical endpoints, in cascade decays of
supersymmetric particles, in principle allow for a determination of the masses
of the unstable particles. However, in this procedure ambiguities often arise.
We here illustrate how such ambiguities arise. They can be resolved by a
precise determination of the LSP mass, provided by the Linear Collider.Comment: 6 pages, 6 figures, to appear in the proceedings of the 2005
International Linear Collider Workshop, Stanford, U.S.
A Production System Model of Capturing Reactive Moving Targets
Subjects manipulated a control stick to position a cursor over a moving target that reacted with a computer-generated escape strategy. The cursor movements were described at two levels of abstraction. At the upper level, a production system described transitions among four modes of activity; rapid acquisition, close following, a predictive mode, and herding. Within each mode, differential equations described trajectory-generating mechanisms. A simulation of this two-level model captures the targets in a manner resembling the episodic time histories of human subjects
Status of advanced turboprop technology
Research is reviewed in the following areas: turboprop powered transport aircraft; wind tunnel aerodynamic and acoustics tests of model propellers; turboprop maintenance; and wind tunnel tests on airframe-turboprop interactions. Continued development of the technology for advanced turboprop transport was emphasized
Lunar Surface Rovers
Many questions of lunar science remain unanswered because of a lack of specific data. With the potential for returning humans to the Moon and establishing a long-term presence there, a new realm of exploration is possible. Numerous plans have been outlined for orbital and surface missions. The capabilities and objectives of a small class of rovers to be deployed on the lunar surface are described. The objective of these small rovers is to collect detailed in situ information about the composition and distribution of materials on the lunar surface. Those data, in turn, would be applied to a variety of lunar geoscience questions and form a basis for planning human activities on the lunar surface
Mass ambiguities in cascade decays
We review the use of invariant mass distributions in cascade decays to
measure the masses of New Physics (NP) particles in scenarios where the final
NP cascade particle is invisible. We extend earlier work by exploring further
the problem of multiple solutions for the masses.Comment: 4 pages, 4 figures, to appear in the proceedings of the XXXIII
International Conference on High Energy Physics (ICHEP'06), July 26 - August
2 2006, Mosco
Mass Determination in Cascade Decays Using Shape Formulas
In SUSY scenarios with invisible LSP, sparticle masses can be determined from
fits to the endpoints of invariant mass distributions. Here we discuss possible
improvements by using the shapes of the distributions. Positive results are
found for multiple-minima situations and for mass regions where the endpoints
do not contain sufficient information to obtain the masses.Comment: to appear in Proceedings of SUSY06, the 14th International Conference
on Supersymmetry and the Unification of Fundamental Interactions, UC Irvine,
California, 12-17 June 200
Study of physiological tolerance to centrifugation Final report
Physiological effects and acceleration tolerances after weightlessness based on space environment simulation with human centrifuges and bed res
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