This paper discusses the features of an annotation language that we believe to be essential for optimizing user-defined abstractions. These features should capture semantics of function, data, and object-oriented abstractions, express abstraction equivalence (e.g., a class represents an array abstraction), and permit extension of traditional compiler optimizations to user-defined abstractions. Our future work will include developing a comprehensive annotation language for describing the semantics of general object-oriented abstractions, as well as automatically verifying and inferring the annotated semantics.

A tool holder was designed to facilitate the machining of precision meso-scale components with complex three-dimensional shapes with sub-{micro}m accuracy on a four-axis lathe. A four-axis lathe incorporates a rotary table that allows the cutting tool to swivel with respect to the workpiece to enable the machining of complex workpiece forms, and accurately machining complex meso-scale parts often requires that the cutting tool be aligned precisely along the axis of rotation of the rotary table. The tool holder designed in this study has greatly simplified the process of setting the tool in the correct location with sub-{micro}m precision. The tool holder adjusts the tool position using flexures that were designed using finite element analyses. Two flexures adjust the lateral position of the tool to align the center of the nose of the tool with the axis of rotation of the B-axis, and another flexure adjusts the height of the tool. The flexures are driven by manual micrometer adjusters, each of which provides a minimum increment of motion of 20 nm. This tool holder has simplified the process of setting a tool with sub-{micro}m accuracy, and it has significantly reduced the time required to set a tool.

Wide-band reflectrometry and ellipsometry have been used to determine the optical properties n and k of freshly polished uranium and of the epitaxial oxide layer, and also the rate of oxide growth in air. Results for uranium metal as well as for epitaxial oxide are compared with single wavelength ellipsometry literature values.

The nuclear waste package design for Yucca Mountain (Nevada, USA), in its current configuration, consists of a double wall cylindrical container fabricated using a highly corrosion resistant Ni-based Alloy 22 for the outer barrier and type 316 stainless steel for the inner structural vessel. A mailbox-shaped drip shield fabricated primarily using Ti Grade 7 will cover the waste packages. The environmental degradation of the relevant materials have been extensively studied and modeled for over ten years. This paper reviews the state-of-the-art understanding of the degradation modes of Alloy 22 (N06022) due to its interaction with the predicted in-drift mountain conditions including temperature and types of electrolytes. Subjects discussed include thermal aging and phase stability, dry oxidation, general and localized corrosion, stress corrosion cracking and hydrogen induced cracking.

Alloy 22 is a nickel base alloy highly resistant to all forms of corrosion. In conditions where tight crevices exist in hot chloride containing solutions and at anodic potentials, Alloy 22 may suffer crevice corrosion, a form of localized attack. The occurrence (or not) of crevice corrosion in a given environment (e.g. salt concentration and temperature), is governed by the values of the critical potential (E{sub crit}) for crevice corrosion and the corrosion potential (E{sub corr}) that the alloy may establish in the studied environment. If E{sub corr} is equal or higher than E{sub crit}, crevice corrosion may be expected. In addition, it is generally accepted that as Alloy 22 becomes passive in a certain environment, its E{sub corr} increases and its corrosion rate (CR) decreases. This paper discusses the evolution of E{sub corr} and corrosion rate (CR) of creviced Alloy 22 specimens in six different mixtures of sodium chloride (NaCl) and potassium nitrate (KNO{sub 3}) at 100 C. The effect of immersion time on the value of E{sub crit} was also determined. Two types of specimens were used, polished as-welded (ASW) and as-welded plus solution heat-treated (ASW+SHT). The latter contained the black annealing oxide film on the surface. Results …

The stability and NO{sub x} sensing performance of electrochemical cells of the structure Sr-doped LaCrO{sub 3-{delta}} (LSC)/yttria-stabilized zirconia (YSZ)/Pt are being investigated for use in NO{sub x} aftertreatment systems in diesel vehicles. Among the requirements for NO{sub x} sensor materials in these systems are stability and long lifetime (up to ten years) in the exhaust environment. In this study, cell aging effects were explored following extended exposure to a test environment of 10% O{sub 2} at operating temperatures of 600-700 C. The data show that aging results in changes in particle morphology, chemical composition and interfacial structure, Impedance spectroscopy indicated an initial increase in the cell resistance during the early stages of aging, which is correlated to densification of the Pt electrode. Also, x-ray photoelectron spectroscopy indicated formation of SrZrO{sub 2} solid state reaction product in the LSC, a process which is of finite duration. Subsequently, the overall cell resistance decreases with aging time due, in part, to roughening of YSZ-LSC interface, which improves interface adherence and enhances charge transfer kinetics at the O{sub 2}/YSZ/LSC triple phase boundary. This study constitutes a first step in the development of a basic understanding of aging phenomena in solid state electrochemical systems with …

To provide a compact high-brightness heavy-ion beam source for Heavy Ion Fusion (HIF), we have been experimenting with merging multi-beamlets in an injector which uses an RF plasma source. An array of converging beamlets was used to produce a beam with the envelope radius, convergence, and ellipticity matched to an electrostatic quadrupole (ESQ) channel. Experimental results were in good quantitative agreement with simulation and have demonstrated the feasibility of this concept. The size of a driver-scale injector system using this approach will be several times smaller than one designed using traditional single large-aperture beams. The success of this experiment has possible significant economical and technical impacts on the architecture of HIF drivers.

A major concern in the design of thick-liquid protected inertial fusion reactors of all types is the dynamic response of the shielding liquid to the pulsed explosions. Induced liquid motion can stress and damage solid chamber structures such as the firstwall. In a z-pinch based inertial fusion (Z-IFE) reactor this issue becomes particularly critical due to the relatively large proposed target yields of several GJ. In this paper we summarize an analysis of the liquid response taking into account ablation of target facing surfaces, pocket venting, and neutron isochoric heating. The impact of varying several reactor parameters is also discussed.

Metal ions are essential for the folding of RNA into stable tertiary structures and for the catalytic activity of some RNA enzymes. To aid in the study of the roles of metal ions in RNA structural biology, we have created MeRNA (Metals in RNA), a comprehensive compilation of all metal binding sites identified in RNA three-dimensional structures available from the Protein Data Bank (PDB) and Nucleic Acid Database (NDB). Currently, our database contains information relating to binding of 9764 metal ions corresponding to 23 distinct elements; in 256 RNA structures. The metal ion locations were confirmed and ligands characterized using original literature references. MeRNA includes eight manually identified metal-ion binding motifs, which are described in the literature. MeRNA is searchable by PDB identifier, metal ion, method of structure determination, resolution and R-values for X-ray structure, and distance from metal to any RNA atom or to water. New structures with their respective binding motifs will be added to the database as they become available. The MeRNA database will further our understanding of the roles of metal ions in RNA folding and catalysis and have applications in structural and functional analysis, RNA design and engineering.

An electronic transition of iron in magnesiowuestite has been studied with synchrotron Moessbauer and X-ray emission spectroscopies under high pressures. Synchrotron Moessbauer studies show that the quadrupole splitting disappears and the isomer shift drops significantly across the spin-paring transition of iron in (Mg{sub 0.75},Fe{sub 0.25})O between 62 and 70 GPa, whereas X-ray emission spectroscopy of the Fe-K{sub {beta}} fluorescence lines in dilute (Mg{sub 0.95},Fe{sub 0.05})O also confirms that a high-spin to low-spin transition occurs between 46 GPa and 55 GPa. Based upon current results and percolation theory, we reexamine the high-pressure phase diagram of (Mg,Fe)O and find that iron-iron exchange interaction plays an important role in stabilizing the high-spin state of iron in FeO-rich (Mg,Fe)O.

The RadPoleCam was developed to provide Department Of Energy (DOE) first responders the capability to assess the radiological and visual condition of remote or inaccessible locations. Real time gamma isotopic identification is provided to the first responder in the form of audio feedback (i.e. spoken through head phones) from a gamma detector mounted on a collapsible pole that can extend from 1 to 9 meters (6 to 29 feet). Simultaneously, selectable direct and side looking visual images are provided from the 5cm (2in) diameter, waterproof probe tip. The lightweight, self contained, ruggedized, system will provide a rapidly deployable field system for visual and radiological search and assessment of confined spaces and extended reach locations.

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This article discusses a T-shaped three-coordinate nickel(l) carbonyl complex and the geometric preferences of three-coordinate d9 complexes.

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Storage of greenhouse gases, primarily CO2, in geologic formations has been proposed as a means by which atmospheric emissions of such gases may be reduced (Bachu et al., 1994; Orr, 2004). Possible storage reservoirs currently under consideration include saline aquifers, depleted or depleting oil and gas fields, and unmineable coal seams (Baines and Worden, 2004). The amount of CO2 emitted from fossil-fueled power plants is very large, of the order of 30,000 tons per day (10 million tons per year) for a large 1,000 MW coal-fired plant (Hitchon,1996). In order to make a significant impact on reducing emissions, very large amounts of CO2 would have to be injected into subsurface formations, resulting in CO2 disposal plumes with an areal extent of order 100 km2 or more (Pruess et al., 2003). It appears inevitable, then, that such plumes will encounter imperfections in caprocks, such as fracture zones or faults, that would allow CO2 to leak from the primary storage reservoir. At typical subsurface conditions of temperature and pressure, CO2 is always less dense than aqueous fluids; thus buoyancy forces will tend to drive CO2 upward, towards the land surface, whenever adequate (sub-)vertical permeability is available. Upward migration of CO2 could also …

We introduce a low Mach number equation set for the large-scale numerical simulation of carbon-oxygen white dwarfs experiencing a thermonuclear deflagration. Since most of the interesting physics in a Type Ia supernova transpires at Mach numbers from 0.01 to 0.1, such an approach enables both a considerable increase in accuracy and savings in computer time compared with frequently used compressible codes. Our equation set is derived from the fully compressible equations using low Mach number asymptotics, but without any restriction on the size of perturbations in density or temperature. Comparisons with simulations that use the fully compressible equations validate the low Mach number model in regimes where both are applicable. Comparisons to simulations based on the more traditional an elastic approximation also demonstrate the agreement of these models in the regime for which the anelastic approximation is valid. For low Mach number flows with potentially finite amplitude variations in density and temperature, the low Mach number model overcomes the limitations of each of the more traditional models and can serve as the basis for an accurate and efficient simulation tool.

Significant effort is currently being devoted to the development of noninvasive imaging systems that allow in vivo assessment of biological and biomolecular interactions in mice and other small animals. Ideally, one would like to discern these functional and metabolic relationships with in vivo radionuclide imaging at spatial resolutions approaching those that can be obtained using the anatomical imaging techniques (i.e., <100 {micro}m), which would help to answer outstanding questions in many areas of biomedicine. In this paper, we report progress on our effort to develop high-resolution focusing X-ray and gamma-ray optics for small-animal radionuclide imaging. The use of reflective optics, in contrast to methods that rely on absorptive collimation like single- or multiple-pinhole cameras, decouples spatial resolution from sensitivity (efficiency). Our feasibility studies have refined and applied ray-tracing routines to design focusing optics for small animal studies. We also have adopted a replication technique to manufacture the X-ray mirrors, and which in experimental studies have demonstrated a spatial resolution of {approx}190 {micro}m. We conclude that focusing optics can be designed and fabricated for gamma-ray energies, and with spatial resolutions, and field of view suitable for in vivo biological studies. While the efficiency of a single optic is limited, fabrication methods …

SPARX is an evolutionary project proposed by a collaboration among ENEA-INFN-CNR-Universita di Roma Tor Vergata aiming at the construction of a FELSASE X-ray source in the Tor Vergata Campus. The first phase of the SPARX project, funded by Government Agencies, will be focused on R&D activity on critical components and techniques for future X-ray facilities as described in this paper.

This paper explores some of the system dynamics and control issues for a short-stroke rotary actuator that we designed and tested for a new fast tool servo referred to as the 10 kHz rotary fast tool servo. The use of a fast tool servo (FTS) with a diamond turning machine for producing non-axisymmetric or textured surfaces on a workpiece is well known. In a previous paper [1] the authors provide details on the mechanical design and trade-off issues that were considered during the design phase for the fast tool servo. At the heart of that machine is the normal-stress variable reluctance rotary actuator described in more detail in this paper. In addition to producing the torque that is needed for the 10 kHz rotary fast tool servo, the actuator produces a force and is therefore referred to as a hybrid rotary/linear actuator. The actuator uses bias and steering magnetic fluxes for linearizing the torque versus current relationship. Certain types of electric engraving heads use an actuator similar in principle to our hybrid actuator. In the case of the engraving heads, the actuator is used to produce and sustain a resonating mechanical oscillator. This is in sharp contrast to the arbitrary …

We present XMM-Newton observations of the radio pulsar PSR J1119-6127, which has an inferred age of 1,700 yr and surface dipole magnetic field strength of 4.1 x 10{sup 13} G. We report the first detection of pulsed X-ray emission from PSR J1119-6127. In the 0.5-2.0 keV range, the pulse profile shows a narrow peak with a very high pulsed fraction of (74 {+-} 14)%. In the 2.0-10.0 keV range, the upper limit for the pulsed fraction is 28% (99% confidence). The pulsed emission is well described by a thermal blackbody model with a temperature of T{infinity} = 2.4{sub -0.2}{sup +0.3} x 10{sup 6} K and emitting radius of 3.4{sub -0.3}{sup +1.8} km (at a distance of 8.4 kpc). Atmospheric models result in problematic estimates for the distance/emitting area. PSR J1119-6127 is now the radio pulsar with smallest characteristic age from which thermal X-ray emission has been detected. The combined temporal and spectral characteristics of this emission are unlike those of other radio pulsars detected at X-ray energies and challenge current models of thermal emission from neutron stars.

We present non-equilibrium molecular dynamics (MD) simulations of wave propagation in nanocrystals. We find that the width of the traveling wave front increases with grain size, d, as d{sup 1/2}. This width also decreases with the pressure behind the front. We extrapolate our results to micro-crystals and obtain reasonable agreement with experimental data. In addition, our extrapolation agrees with models that only take into account the various velocities of propagation along different crystalline orientations, without including grain boundary effects. Our results indicate that, even at the nanoscale, the role of grain boundaries as scattering centers or as sources of plasticity does not increase significantly the width of the traveling wave.

A design for a high gradient, low inductance pulsed quadrupole magnet is presented. The magnet is a circular current dominated design with a circular iron return yoke. Conductor angles are determined by a method of direct multipole elimination which theoretically eliminates the first four higher order multipole field components. Coils are fabricated from solid round film-insulated conductor, wound as a single layer ''non-spiral bedstead'' coil having a diagonal leadout entirely within one upturned end. The coils are wound and stretched straight in a special winder, then bent in simple fixtures to form the upturned ends.

This paper will discuss the Safeguards & Security (S&S) activities that resulted in the downgrade of the Savannah River Site's FB-Line (FBL) from a Category I Material Balance Area (MBA) in a Material Access Area (MAA) to a Category IV MBA in a Property Protection Area (PPA). The Safeguards activities included measurement of final product items, transferal of nuclear material to other Savannah River Site (SRS) facilities, discard of excess nuclear material items, and final measurements of holdup material. The Security activities included relocation and destruction of classified documents and repositories, decertification of a classified computer, access control changes, updates to planning documents, deactivation and removal of security systems, Human Reliability Program (HRP) removals, and information security training for personnel that will remain in the FBL PPA.

For many thin-film applications substrate imperfections such as particles, pits, scratches, and general roughness, can nucleate film defects which can severely detract from the coating's performance. Previously we developed a coat-and-etch process, termed the ion beam thin film planarization process, to planarize substrate particles up to {approx} 70 nm in diameter. The process relied on normal incidence etching; however, such a process induces defects nucleated by substrate pits to grow much larger. We have since developed a coat-and-etch process to planarize {approx}70 nm deep by 70 nm wide substrate pits; it relies on etching at an off-normal incidence angle, i.e., an angle of {approx} 70{sup o} from the substrate normal. However, a disadvantage of this pit smoothing process is that it induces defects nucleated by substrate particles to grow larger. Combining elements from both processes we have been able to develop a silicon-based, coat-and-etch process to successfully planarize {approx}70 nm substrate particles and pits simultaneously to at or below 1 nm in height; this value is important for applications such as extreme ultraviolet lithography (EUVL) masks. The coat-and-etch process has an added ability to significantly reduce high-spatial frequency roughness, rendering a nearly perfect substrate surface.