The shock tube technique with H- and D-atom atomic resonance absorption spectrometry (ARAS) detection has been used to study the thermal decomposition of C{sub 2}D{sub 5}I and the reaction, CH{sub 3} + D'' CH{sub 2}D + H, (1) over the temperature ranges, 924-1370 K and 1294-1753 K, respectively. First-order rate constants for the thermal decomposition of C{sub 2}D{sub 5}I can be expressed by the Arrhenius equation, logk{sub C2D5I} = (10.397 {+-} 0.297) - (7700 {+-} 334 K)/T, giving k{sub C2D5I} = 2.49 x 10{sup 10} exp(-17729 K/T) s{sup -1}. The branching ratio between product channels, C{sub 2}D{sub 5} + I and C{sub 2}D{sub 4} + DI, was also determined. These results coupled with the fast decomposition of C{sub 2}D{sub 5} radicals were then used to specify [D]{sub t} in subsequent kinetics experiments with CH{sub 3} where [CH{sub 3}]{sub 0} was prepared from the concurrent thermal decomposition of CH{sub 3}I. Within experimental error, the rate constants for reaction (1) were found to be temperature independent with k{sub 1} = (2.20 {+-} 0.22) x 10{sup -10} cm{sup 3} molecule{sup -1} s{sup -1}. The present data have been combined with earlier lower temperature determinations and the joint database has been examined with unimolecular …

None

Limit load solutions obtained by elastic-perfectly plastic finite element analysis (EPP-FEA) are compared to results of tests of low-alloy steel perforated plate geometries loaded to full plastic collapse. Results are given for two plastic-collapse tests of flat circular disks with circular penetrations arranged in a triangular pattern and drilled normal to the surface of the plate. The ligament efficiency (minimum distance between holes divided by the distance between the centers of the holes) of the pattern is 0.32 and the plate thickness is 2.39 inches (60.7 mm). The tests were designed so that a transverse load generated plastic collapse in the outer row of penetrations due to a combination of transverse shear and in-plane bending. Limit-load solutions were obtained using EPP-FEA with small-strain, small-defection linear geometry assumptions. Two FEA models are used: one where the perforated region is modeled using an equivent solid plate (EQS) representation and another where each hole is explicitly modeled by FEA. The results presented in this paper demonstrate that the deformation patterns produced by the EPP-FEA solutions match exactly with the deformation patterns produced by the test. The EQS-EPP FEA solution is about 15% lower than the explicit-hole EPP-FEA solution. Using one-third the actual ultimate …

A detailed chemical kinetic reaction mechanism is developed to describe incineration of the chemical warfare nerve agent sarin (GB), based on commonly used principles of bond additivity and hierarchical reaction mechanisms. The mechanism is based on previous kinetic models of organophosphorus compounds such as TMP, DMMP and DIMP that are often used as surrogates to predict incineration of GB. Kinetic models of the three surrogates and GB are then used to predict their consumption in a perfectly stirred reactor fueled by natural gas to simulate incineration of these chemicals. Computed results indicate that DIMP is the only one of these surrogates that adequately describes combustion of GB under comparable conditions. The kinetic pathways responsible for these differences in reactivity are identified and discussed. The most important reaction in GB and DIMP that makes them more reactive than TMP or DMMP is found to be a six-center molecular elimination reaction producing propene.

Understanding the role of grain boundaries in controlling heat flow is critical to the success of many envisioned applications of nanocrystalline materials. This study focuses on the effect of grain boundaries on thermal transport behavior in nanocrystalline yttria-stabilized zirconia (YSZ) coatings prepared by metal-organic chemical vapor deposition. A strong grain-size-dependent reduction in thermal conductivity is observed at all temperatures from 6-480 K. The behavior is due primarily to the effect of interfacial (Kapitza) resistance on thermal transport. In response to the application of heat to a material, interfacial resistance results in a small temperature discontinuity at every grain boundary, an effective that is magnified in nanocrystalline materials because of the large number of grain boundaries. The observed behavior in YSZ is compared with predictions derived from a diffuse-mismatch model. Implications for the possible development of improved thermal barriers based on nano-layered structures with large interfacial thermal resistance are discussed.

None

None

The reaction of methyl radicals with hydrogen atoms is studied with a combination of ab initio quantum chemistry, variational transition state theory, and classical trajectory simulations. The interaction between the two radicals, including the umbrella mode of the methyl radical, is examined at the CAS+1+2 level using an augmented correlation consistent polarized valence triple zeta basis set. The implementation of an analytic representation of the ab initio data within variable reaction coordinate transition state theory yields predictions for the zero-pressure limit isotopic exchange rate constants that are about 15% greater than the available experimental data. Trajectory simulations indicate that the transition state recrossing factor for the capture process is 0.90, essentially independent of temperature and isotope. The dynamically corrected theoretical prediction for the CH{sub 3} + H high pressure rate coefficient is well reproduced by the expression 1.32 x 10{sup -10}T{sup 0.153}exp(-15.1/RT) cm{sup 3}molecule{sup -1}s{sup -1}, where R = 1.987 cal mole{sup -1} K{sup -1}, for temperatures between 200 and 2400 K. This prediction is in good agreement with the converted experimental data for all but the one measurement at 200 K. Calculations for the triplet abstraction channel suggest that it is unimportant. Methyl umbrella mode variations have surprisingly little …

Diamondlike carbon (DLC) films have attracted great interest in recent years mainly because of their unusual optical, electrical, mechanical, and tribological properties. Such properties are currently being exploited for a wide range of engineering applications including magnetic hard disks, gears, sliding and roller bearings, scratch resistant glasses, biomedical implants, etc. Systematic studies on carbon-based materials in our laboratory have led to the development of a new class of amorphous DLC films that provide extremely low friction and wear coefficients of 0.001 to 0.005 and 10{sup -11} to 10{sup -10} mm{sup 3} /N.m, respectively, when tested in inert-gas or high-vacuum environments. These films were produced in highly hydrogenated gas discharge plasmas by a plasma enhanced chemical vapor deposition process at room temperature. The carbon source gases used in the deposition of these films included methane, acetylene, and ethylene. Tribological studies in our laboratory have established a very close correlation between the composition of the plasmas and the friction and wear coefficients of the resultant DLC films. Specifically, the friction and wear coefficients of DLC films grown in plasmas with higher hydrogen-to-carbon ratios were much lower than films derived from source gases with lower hydrogen-to-carbon ratios. Fundamental tribological and surface analytical studies …

An important component of EPICS (Experimental Physics and Industrial Control System) is iocCore, which is the core software in the IOC (input/output controller) front-end processors. At ICALEPCS 1999 a paper was presented describing plans to port iocCore to multiple operating systems. At that time iocCore only supported vxWorks, but now it also supports RTEMS, Solaris, Linux, and WinNT. This paper describes some key features of how iocCore supports multiple operating systems.

We continue consideration of ways-and-means for creating, in an evolutionary, ever-more-powerful manner, a continually-updated data-base of salient atmospheric properties sufficient for finite differenced integration-based, high-fidelity weather prediction over intervals of 2-3 weeks, leveraging the 10{sup 14} FLOPS digital computing systems now coming into existence. A constellation comprised of 10{sup 6}-10{sup 9} small atmospheric sampling systems--high-tech superpressure balloons carrying early 21st century semiconductor devices, drifting with the local winds over the meteorological spectrum of pressure-altitudes--that assays all portions of the troposphere and lower stratosphere remains the central feature of the proposed system. We suggest that these devices should be active-signaling, rather than passive-transponding, as we had previously proposed only for the ground- and aquatic-situated sensors of this system. Instead of periodic interrogation of the intra-atmospheric transponder population by a constellation of sophisticated small satellites in low Earth orbit, we now propose to retrieve information from the instrumented balloon constellation by existing satellite telephony systems, acting as cellular tower-nodes in a global cellular telephony system whose ''user-set'' is the atmospheric-sampling and surface-level monitoring constellations. We thereby leverage the huge investment in cellular (satellite) telephony and GPS technologies, with large technical and economic gains. This proposal minimizes sponsor forward commitment along its entire …

None

None

We present a short overview of radio surveys for AGN, including the ''complete'' flux limited surveys and ''filtered'' surveys. We also describe our ultra-steep spectrum search for the highest redshift radio galaxies, and our follow-up VLA and ATCA observations of the most distant (z = 5.19) and the most luminous z < 2 radio galaxy known.

The Static Database Access library was first introduced in EPICS (Experimental Physics and Industrial Control System) Release 3.11 in 1994. It provides an application program interface (API) for database configuration tools written in C to manipulate database record definitions and is used for various tasks within the core EPICS software. This paper describes the structure of a replacement for the original library that adds a native C++ API and will make some future enhancements to EPICS significantly easier to implement.

A gap-free, world-wide, ocean-, atmosphere-, and land surface-spanning geophysical data-set of three decades time-duration containing the full set of geophysical parameters characterizing global weather is the scientific perquisite for defining the climate; the generally-accepted definition in the meteorological community is that climate is the 30-year running-average of weather. Until such a tridecadal climate base line exists, climate change discussions inevitably will have a semi-speculative, vs. a purely scientific, character, as the baseline against which changes are referenced will be at least somewhat uncertain. The contemporary technology base provides ways-and-means for commencing the development of such a meteorological measurement-intensive climate baseline, moreover with a program budget far less than the {approx}$2.5 B/year which the US. currently spends on ''global change'' studies. In particular, the recent advent of satellite-based global telephony enables real-time control of, and data-return from, instrument packages of very modest scale, and Silicon Revolution-based sensor, data-processing and -storage advances permit 'intelligent' data-gathering payloads to be created with 10 gram-scale mass budgets. A geophysical measurement system implemented in such modern technology is a populous constellation 03 long-lived, highly-miniaturized robotic weather stations deployed throughout the weather-generating portions of the Earths atmosphere, throughout its oceans and across its land surfaces. Leveraging the …

The Electric Power Research Institute/U.S. Department of Energy (EPRI/DOE) Turbine Verification Program (TVP) includes four distributed wind generation projects connected to utility distribution feeders located in Algona, Iowa; Springview, Nebraska; Glenmore, Wisconsin; and Kotzebue, Alaska. The TVP has undertaken power quality measurements at each project to assess the impact that power quality has on the local utility grids. The measurements and analysis were guided by the draft IEC 61400-21 standard for power quality testing of wind turbines. The power quality characteristics measured include maximum power, distribution feeder voltage regulation, reactive power, and harmonics. This paper describes the approach to the measurements, the unique electrical system features of the four projects, and an assessment of measured power quality relative to limits prescribed by standards. It also gives anecdotal stories from each project regarding the impact of power quality on the respective distribution feeders.

Dose profiles throughout the front-end building and the accelerator tunnel were calculated for the SNS linac system both for normal operation and after shut down of the facility based on normal operations beam losses. The calculated dose levels at an cylindrical envelope with 60 cm radius range from 0.08 to 10 rem/hr for the drift tube linac part, from 50-80 rem/hr for the coupled cavity linac part, from 1 to 20 rem/hr for the superconducting linac part, and from 70-200 rem/hr for the spare section extending after the linac. In the front-end building that houses the first 10 meters of the drift tube linac, dose levels of up to 500 mrem/hr were calculated that need to be reduced by adequate shielding, for example an ordinary concrete shield of up to 120 cm thickness. The shield thickness can be reduced by 25% using borated concrete or a layer of 20 cm borated polyethylene followed by ordinary concrete. The calculated residual dose levels in the accelerator tunnel are a factor of 2000-30 00 lower compared to the operational doses assuming a 30-year operations period and a 1hour decay period.

None

Experimental investigations on the conditions to achieve transient gain in neon-like Ti and nickel-like molybdenum XUV laser pumped by a 10-HZ sub-Joule femtosecond laser are presented. The 4d-4p (J = 0-1) {lambda} = 18.9 nm and 4f-4d (J = 1-11) {lambda} = 22.6 nm lines in Ni-like Mo as well as the 3p-3s (J = 0-1) {lambda} = 32.6 nm line in neon-like titanium have been observed. The Ni-like laser lines show a threshold behavior with respect to the pump irradiance as they appear only above 10{sup 15} W/cm{sup 2}. Simulation for the fs-laser pumped Ni-like Mo XUV laser are also presented.

Article on the partition of solutes from the gas phase and from water to wet and dry di-n-butyl ether and a linear free energy relationship analysis.

This paper focuses on the channeling of energy from electronic to nuclear degrees of freedom in electron-polyatomic molecule collisions. We examine the feasibility of attacking the full scattering problem, both the fixed-nuclei electronic problem and the post-collision nuclear dynamics, entirely from first principles. The electron-CO{sub 2} system is presented as an example. We study resonant vibrational excitation, showing how a6 initio, fixed-nuclei electronic cross sections can provide the necessary input for a multi-dimensional treatment of the nuclear vibrational dynamics.

A novel design for an electron beam focusing column has been developed at LBNL. The design is based on a low-energy spread multicusp plasma source which is used as a cathode for electron beam production. The focusing column is 10 mm in length. The electron beam is focused by means of electrostatic fields. The column is designed for a maximum voltage of 50 kV. Simulations of the electron trajectories have been performed by using the 2-D simulation code IGUN and EGUN. The electron temperature has also been incorporated into the simulations. The electron beam simulations, column design and fabrication will be discussed in this presentation.

X-ray photoemission and x-ray photoabsorption were used to study the composition and the electronic structure of ytterbium doped strontium fluoroapatite (Yb:S-FAP). High resolution photoemission measurements on the valence band electronic structure was used to evaluate the density of occupied states of this fluoroapatite. Element specific density of unoccupied electronic states in Yb:S-FAP were probed by x-ray absorption spectroscopy (XAS) at the Yb 4d (N{sub 4,5}-edge), Sr 3d (M{sub 4,5}-edge), P 2p (L{sub 2,3}-edge), F 1s and O 1s (K-edges) absorption edges. These results provide the first measurements of the electronic structure and surface chemistry of this material.