Slicing tests of silicon to show the dependence of cutting rate on operating conditions are complete. Cutting rate is linear with cutting force per blade and bladehead speed, and inversely proportional to kerf width (loss) and kerf length. The dimensionless parameter of cutting efficiency is a good measure of the performance of a multiblade slicing system. Low contact pressure between the blades and the silicon workpiece result in increased wafer accuracy and cutting efficiency. Blade wear seems to be stable for all slicing tests, and is slightly lower with low cutting pressure. (WDM)

Electron microscope images obtained at about 3A resolution for Pr/sub 7/O/sub 12/ (and isomorphous Zr/sub 3/Sc/sub 4/O/sub 12/) are in excellent agreement with calculated images based upon the structure determined separately by total profile neutron powder diffraction analysis. The image calculation programs establish the efficacy of lattice image interpretation in structural terms for these types of related phases whose structures are as yet beyond conventional means to determine. Such images for several other intermediate phases are interpreted and structures proposed. Finally, images of crystals which can be made to undergo reaction within the microscope are interpreted according to the structures involved. These studies reveal the role of intergrowth and topotaxy in these systems. (auth)

This research program began January 6, 1976. Its objective is to demonstrate the feasibility of the floating substrate sheet growth process for the growth of silicon sheet. This process is an approach to the formation of single-crystal silicon by direct epitaxial conversion from a gaseous silane. Incoming feedstock gas impinges upon a silicon substrate which is floating upon a thin pool of liquid tin. Single-crystal silicon grows to the desired thickness by means of vapor phase epitaxy. Nucleation of fresh substrate silicon takes place by rapid growth from the edge of the growing sheet into a region at the surface of the liquid tin which is supersaturated in the silicon. The process lends itself to continuous operation with the growing sheet being continuously withdrawn from the growth zone. (WDM)

The principles of mirror machine confinement are reviewed with emphasis on the physical process of neutral beam injection and plasma end leakage. The characteristics of efficient neutral beam injectors and direct energy convertors for the plasma and leakage are described.

A review is made of the current status of /sup 235/U fission cross section data from thermal to 20 MeV neutron energies. The accuracy achieved is compared with the 1 percent accuracy required of a reaction-cross-section standard throughout this range. The energy ranges from thermal to 10 keV, 10 keV to 0.8 MeV and 0.8 to 20 MeV are considered separately because of the different experimental techniques required in each. The goal of normalizing all fission cross sections to the thermal value and the current degree of success is discussed.

From data generated in the laboratory and pilot plant studies a quality rerefined oil can be produced via BERC/ERDA solvent extraction and clay treatment. Some of the important processing variables that determine the quality of the finished product are temperature of solvent extraction, type of clay used, temperature and time of clay treatment, and the atmosphere under which the oil is treated with clay. Yields of 75 percent based on water-distillate-free oil can be expected at the conditions used in pilot plant operations. The oils obtained could be compounded to produce a large number of high quality lubricating products. Unlike an acid-clay process where the acid sludges pose an environmental problem, the BERC/ERDA system produces a marketable sludge.

CH2MHill Hanford Group, Inc. (CHG) is designing and assessing the performance of an Integrated Disposal Facility (IDF) to receive immobilized low-activity waste (ILAW), Low-Level and Mixed Low-Level Wastes (LLW/MLLW), and the Waste Treatment Plant (WTP) melters used to vitrify the ILAW. The IDF Performance Assessment (PA) assesses the performance of the disposal facility to provide a reasonable expectation that the disposal of the waste is protective of the general public, groundwater resources, air resources, surface water resources, and inadvertent intruders. The PA requires prediction of contaminant migration from the facilities, which is expected to occur primarily via the movement of water through the facilities and the consequent transport of dissolved contaminants in the pore water of the vadose zone. Pacific Northwest National Laboratory (PNNL) assists CHG in its performance assessment activities. One of PNNL’s tasks is to provide estimates of the physical, hydraulic, and transport properties of the materials comprising the disposal facilities and the disturbed region around them. These materials are referred to as the near-field materials. Their properties are expressed as parameters of constitutive models used in simulations of subsurface flow and transport. In addition to the best-estimate parameter values, information on uncertainty in the parameter values and …

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We have developed and characterized a mixer to study the reaction kinetics of protein folding on a microsecond timescale. The mixer uses hydrodynamic focusing of pressure-driven flow in a microfluidic channel to reduce diffusion times as first demonstrated by Knight et al.[1]. Features of the mixer include 1 {micro}s mixing times, sample consumptions of order 1 nl/s, loading sample volumes on the order of microliters, and the ability to manufacture in fused silica for compatibility with most spectroscopic methods.

The efficient representation of volumetric meshes is a central problem in scientific visualization. The difference in performance between most visualization algorithm for rectilinear grids and for unstructured mesh is mostly due to fundamental difference in efficiency of their representations. In Computer Graphics the gap in performance between 2D rectilinear grids and unstructured mesh has been overcome with the development of representation schemes based on the concept of subdivision surfaces. This gap has not been bridged in the volumetric cases which is fundamental interest for Scientific Visualization. In this paper we introduce a slow-growing volumetric subdivision scheme for meshes of any topology, any intrinsic dimension d and composed of a general type of polyhedral cells (topological balls). The main feature of this approach is the ability to split in different stages cells of different dimensions. This allows to increase the resolution of the mesh slowly using small stencils for the smoothing rules. ''Sharp features'' of dimension lower than d are embedded naturally in the subdivision procedure. Automatic adaptation is provided for variable resolution. In the uniform case the slow subdivision doubles the number of vertices in the mesh at each refinement independent of its dimension d. The bisection of all the …

In a new mode of measurement, the amplitude of a tearing mode rotating at frequencies of up to tens of KHz has been obtained using the spectral features of high frequency MSE data. A formulation has been developed to calculate the pitch angle oscillations associated with these instabilities, from the MSE spectrum. Density fluctuations can be simultaneously obtained from MSE measurements if the intensity response to density variation can be calibrated. Examples of observations are given and detection limits are explored.

This paper briefly reviews activities and research related to children and educational environments. The increasing prevalence and role of information and communications technology in the lives of children as well as the incidence of back pain and heavy loads children carry in back packs are raising concerns around the world. Out of this concern an International Ergonomics Association Technical Committee has been formed. A survey was sent to Ergonomics for Children and Educational Environments membership and those who have communicated through the committee. The results are compiled to describe a cross-section of international efforts to address the health and the future of children.

This report describes a signal processing algorithm and MATLAB software for improving spatial resolution in ultrasonic nondestructive evaluation (NDE) imaging of materials. Given a measured reflection signal and an associated reference signal, the algorithm produces an optimal least-squares estimate of the impulse response of the material under test. This estimated impulse response, when used in place of the raw reflection signal, enhances the spatial resolution of the ultrasonic measurements by removing distortion caused by the limited-bandwidth transducers and the materials under test. The theory behind the processing algorithms is briefly presented, while the reader is referred to the bibliography for details. The main focus of the report is to describe how to use the MATLAB software. Two processing examples using actual ultrasonic measurements are provided for tutorial purposes.

A distributed memory message-passing parallel implementation of a finite-volume discretization of the primitive equations in the Community Atmosphere Model is presented. Due to the data dependencies resulting from the polar singularity of the latitude-longitude coordinate system, it is necessary to employ two separate domain decompositions within the dynamical core. Data must be periodically redistributed between these two decompositions. In addition, the domains contain halo regions that cover the nearest neighbor data dependencies. A combination of several techniques, such as one-sided communication and multithreading, are presented to optimize data movements. The resulting algorithm is shown to scale to very large machine configurations, even for relatively coarse resolutions.

Under anaerobic conditions and at circumneutral pH, cells of the widely-distributed, obligate chemolithoautotrophic bacterium Thiobacillus denitrificans oxidatively dissolved synthetic and biogenic U(IV) oxides (uraninite) in nitrate-dependent fashion: U(IV) oxidation required the presence of nitrate and was strongly correlated to nitrate consumption. This is the first report of anaerobic U(IV) oxidation by an autotrophic bacterium.

We suggest a new class of high-flux renewable optics, in particular, for the use at the X-ray free electron laser, LCLS, which is under discussion now. The size of optical elements we have in mind is from a fraction of a square centimeter to a few square centimeters. We suggest that working fluid be pressed through a porous substrate (made, e.g., of fused capillaries) to form a film, a few tens to a hundred microns thick. After the passage of an intense laser pulse, the liquid film is sucked back through the substrate by a reversed motion of the piston, and formed anew before the next pulse. The working surface of the film is made flat by capillary forces. We discuss the role of viscous, gravitational, and capillary forces in the dynamics of the film and show that the properly made film can be arbitrarily oriented with respect to the gravitational force. This makes the proposed optics very flexible. We discuss effects of vibrations of the supporting structures on the quality of optical elements. Limitations on the radiation intensity are formulated. We show how the shape of the film surface can be controlled by electrostatic and magnetic forces, allowing one …

Understanding and predicting the behavior of high-Z non-LTE plasmas is important for developing indirect-drive inertial confinement fusion. Extending earlier work from the Nova laser, we present results from experiments using the Omega laser to study the ionization balance of gold as a function of electron and radiation temperature. In these experiments, gold samples embedded in Be disks expand under direct laser heating to n{sub e} {approx} 10{sup 21} cm{sup -3}, with T{sub e} varying from 0.8 to 2.5 keV. An additional finite radiation field with effective temperature T{sub r} up to 150 eV is provided by placing the gold-Be disks inside truncated 1.2 mm diameter tungsten-coated cylindrical hohlraums with full laser entrance holes. Densities are measured by imaging of plasma expansion. Electron temperatures are diagnosed with either 2 {omega} or 4 {omega} Thomson scattering, and also K-shell spectroscopy of KCl tracers co-mixed with the gold. Hohlraum flux and effective radiation temperature are measured using an absolutely-calibrated multichannel filtered diode array. Spectroscopic measurements of the M-shell gold emission in the 2.9-4 keV spectral range provide ionization balance and charge state distribution information. The spectra show strong variation with T{sub e}, strong variation with the applied T{sub r} at T{sub e} below …

The increasing presence of computers and other forms of information and communications technology (ICT) in schools has raised concerns in the United States (US) and elsewhere. Children are using computers more than any other age group in the US. It is not known whether early intensive use of ICT predisposes children to future injury. Ergonomics is not included in state curriculum standards or requirements but can be supported by some of the existing standards. Some who believe that children are better off being educated early about ergonomics are taking action to bring ergonomics into elementary and secondary schools. This paper describes the process used to introduce ergonomics into two elementary schools in two different states by initiators with two different roles.

Alumina aerogels were prepared through the addition of propylene oxide to aqueous or ethanolic solutions of hydrated aluminum salts, AlCl{sub 3} {center_dot} 6H{sub 2}O or Al(NO{sub 3}){sub 3} {center_dot} 9H{sub 2}O, followed by drying with supercritical CO{sub 2}. This technique affords low-density (60-130 kg/m{sup 3}), high surface area (600-700 m{sup 2}/g) alumina aerogel monoliths without the use of alkoxide precursors. The dried alumina aerogels were characterized using elemental analysis, high-resolution transmission electron microscopy, powder X-ray diffraction, solid state NMR, acoustic measurements and nitrogen adsorption/desorption analysis. Powder X-ray diffraction and TEM analysis indicated that the aerogel prepared from hydrated AlCl{sub 3} in water or ethanol possessed microstructures containing highly reticulated networks of pseudoboehmite fibers, 2-5 nm in diameter and of varying lengths, while the aerogels prepared from hydrated Al(NO{sub 3}){sub 3} in ethanol were amorphous with microstructures comprised of interconnected spherical particles with diameters in the 5-15 nm range. The difference in microstructure resulted in each type of aerogel displaying distinct physical and mechanical properties. In particular, the alumina aerogels with the weblike microstructure were far more mechanically robust than those with the colloidal network, based on acoustic measurements. Both types of alumina aerogels can be transformed to {gamma}-Al{sub 2}O{sub 3} …

An intermediate regime for tokamak operation has been obtained in DIII-D and in other tokamaks in which the inductive flux consumption is reduced and a broad current profile with the safety factor just above or near the sawtoothing limit is obtained and maintained. The DIII-D tokamak was operated in this regime near the no-wall b limit. High stability and good confinement was achieved at a desired level of q{sub 95} {approx} 3 to 4 for durations as long as 35{tau}{sub E}, three times the current-diffusion time. This regime offers the promise of achieving higher fusion gain and yield and/or longer burn duration for ITER.

We are developing high-current ion sources for Heavy Ion Fusion applications. Our proposed RF plasma source starts with an array of high current density mini-beamlets (of a few mA each at {approx}100 mA/cm{sup 2}) that are kept separated from each other within a set of acceleration grids. After they have gained sufficient kinetic energy (>1.2 MeV), the mini-beamlets are allowed to merge together to form a high current beam (about 0.5 A) with low emittance. Simulations have been done to maximize the beam brightness within the physical constraints of the source. We have performed a series of experiments on an RF plasma source. A 80-kV 20-{micro}s source has produced up to 5 mA of Ar{sup +} in a single beamlet and we measured the emittance of a beamlet, its energy spread, and the fraction of ions in higher charge states. We have also tested a 50-kV 61-hole multi-beamlet array. Two upcoming experiments are being prepared: the first experiment will test full-gradient extraction and transport of 61 beamlets though the first four electrodes, and the second experiment will converge 119 beamlets into an ESQ channel at one-quarter scaled voltage of a 1.6 MV HIF injector.

Properties of rock materials under quasistatic conditions are well characterized in laboratory experiments. Unfortunately, quasistatic data alone are not sufficient to calibrate models for use to describe inelastic wave propagation associated with conventional and nuclear explosions, or with impact. First, rock properties are size-dependent. properties measured using laboratory samples on the order of a few centimeters in size need to be modified to adequately describe wave propagation in a problem on the order of a few hundred meters in size. Second, there is lack of data about the damage (softening) behavior of rock because most laboratory tests focus on the pre-peak hardening region with very little emphasis on the post-peak softening region. This paper presents a model for granite that accounts for both the hardening and softening of geologic materials, and also provides a simple description of rubblized rock. The model is shown to reproduce results of quasistatic triaxial experiments as well as peak velocity and peak displacement attenuation from a compendium of dynamic wave propagation experiments that includes US and French nuclear tests in granite.

A solid-state laser system, used as a directed energy defensive weapon, possesses many compelling logistical advantages over high-average-power chemical laser systems. As an electrically-powered laser, it uses no chemicals, generates no effluents, and requires no specialized logistics support--the laser is recharged by running the vehicle engine. It provides stealth, having low signature operation without the generation of temperature, smoke, or visible light. It is silent in operation, limited only by the onboard vehicle electrical charging and propulsion system. Using the heat-capacity mode of operation, scaling of average power from a solid-state laser has been demonstrated beyond 10kW and work in progress will result in the demonstration of a 100 kW solid-state heat-capacity laser (SSHCL). The heat-capacity approach provides unprecedented power-to-weight ratios in a compact platform that is readily adapted to mobile operation. A conceptual engineering and packaging study has resulted in a 100kW SSHCL design that we believe can be integrated onto a hybrid-electric HMMWV or onto new vehicle designs emerging from the future combat system (FCS) development. 100 kW has been proposed as a power level that demonstrates a significant scaling beyond what has been demonstrated for a solid-state laser system and which could have a significant lethality against …

Under the Situation and Crisis Center (SCC) management, the Information Analytical Center (IAC) of the Ministry of Atomic Energy (Minatom) of Russia was created to oversee the operation of the Federal Nuclear Material Control and Accounting Information System (FIS). During 2000, the FIS achieved an important milestone in its development: the basic functions of the information system were implemented. This includes placing into operation the collecting and processing of nuclear material control and accounting (MC&A) information from the enterprises reporting to the FIS. The FIS began working with 14 Russian enterprises to develop and implement full-function reporting (i.e., reporting inventory and inventory changes including closeout and reconciliation between the FIS and enterprises). In 2001, the system will expand to include enterprise-level inventory information for all enterprises using nuclear materials in Russia. For this reason, at the end of 2000 through the beginning of 2001, five separate training sessions were held for over 100 enterprise personnel responsible for preparation and transfer of the reports to the FIS. Through the assistance of the Nuclear Material Protection, Control and Accounting (MPC&A) program, information systems for the accounting of nuclear materials are being installed at Russia enterprises. In creating the program for modernization of …