Transmission electron microscopy (TEM) has been applied to the microstructural investigation of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) thick films deposited on polycrystalline Ni-based metal substrates by pulsed laser deposition. The films were found to be strongly textured with c-axis oriented grains aligned perpendicular to the substrates. Despite the large average in-plane misorientation, as was estimated from selected area electron diffraction and x-ray diffraction, TEM inspection reveals colonies of submicron-sized grains with low angle tilt grain boundaries. The linkage of the colony structures may provide a continuous percolation pathway for the supercurrent transport in YBCO, which may provide the mechanism for the higher than expected critical current density J{sub c}. Periodic arrays of grain boundary dislocations were observed, which may serve as effective flux pinners.

With the implementation of a transmission-type curved crystal spectrometer at the Livermore high-energy electron beam ion trap (SuperEBIT) the window on sub-eV level measurements of the ground-state quantum electrodynamics and the two-electron quantum electrodynamics of high-Z ions has been opened. High-resolution spectroscopic measurements of the K{alpha} spectra of hydrogenlike Xe{sup 53+} and heliumlike Xe{sup 52+} are presented. The electron-impact excitation cross sections have been determined relative to the radiative recombination cross sections. The electron-impact energy was 112 keV which is about 3.7 times the excitation threshold for the n = 2 {yields} 1 transitions. Although the relative uncertainties of the measured electron-impact excitation cross sections range from about 20% to 50%, significant disagreement between the measured and calculated cross section values has been found for one of the heliumlike xenon lines. Overall, the comparison between experiment and theory shows that already for xenon (Z=54) the Breit interaction plays a significant part in the collisional excitation process. The measured cross sections for the hydrogenlike transitions are in good agreement with theoretical predictions. Additionally, the Xe{sup 53+} Ly-{alpha}{sub 1} transition energy has been measured utilizing the K{alpha} emission of neutral cesium and barium for calibration. Surprisingly, the experimental result, (31279.2 {+-} 1.5) …

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A superconducting imaging-surface system was constructed using 12 coplanar thin-film SQUID magnetometers located parallel to and spaced 2 cm from a 25 cm diameter lead imaging-plane. Some measurements included two additional sensors on the ''back'' side of the superconducting imaging-plane to study the field symmetry for our system. Performance was measured in a shielded can and in the open laboratory environment. Data from this system has been used to: (a) understand the noise characteristics of the dewar-SQUID imaging plate arrangement, (b) to verify the imaging principle, (c) measure the background rejection factor of the imaging plane, and (d) compare superconducting materials for the imaging plane. A phantom source field was measured at the sensors as a function of phantom distance from the sensor array to verify the imaging theory. Both the shape and absolute value of the measured and predicted curves agree very well indicating the system is behaving as a gradiometer in accordance with theory. The output from SQUIDs located behind the imaging surface that sense background fields can be used for software or analog background cancellation. Fields arising from sources close to the imaging plane were shielded form the background sensors by more than a factor of 1000. …

One meter long tapes based on 50-100 {micro}m thick by 1 cm wide nickel alloy substrates have been coated in a continuous process with a textured yttria-stabilized zirconia layer by ion beam-assisted deposition, followed by a 1-2 {micro}m thick layer of YBCO by pulsed laser deposition. The best result to date is a tape with a critical current (I{sub c}) at 75 K of 96 A over an 87 cm measurement length. The overall critical current density and engineering current density are 1 MA/cm{sup 2} and 10 kA/cm{sup 2}, respectively. Using a special probe, individual I-V curves were generated for each centimeter of tape length in order to investigate longitudinal uniformity of the transport properties: the highest and lowest I{sub c} values fall within a range of {+-}25%.

In 1997, the authors initiated a development program in Los Alamos for high-current superconducting proton-linac technology to build prototypes components of this linac to demonstrate the feasibility. The authors are building 700-MHz niobium cavities with elliptical shapes, as well as power couplers to transfer high RF power to these cavities. The cavities and power couplers will be integrated in cryostats as linac cryomodules. In this paper, they describe the linac design and the status of the development program.

We demonstrate that the insertion of low-temperature (LT) AlGaN interlayers is effective in reducing mismatch-induced tensile stress and suppressing the formation of cracks during growth of AlGaN directly upon GaN epilayers., Stress evolution and relaxation is monitored using an in-situ optical stress sensor. The combination of in-situ and ex-situ. characterization techniques enables us to determine the degree of pseudomorphism in the interlayers. It is observed that the elastic tensile mismatch between AlGaN and GaN is mediated by the relaxation of interlayers; the use of interlayers offers tunability in the in-plane lattice parameters.

During 1998 and 1999, the National Wind Coordinating Committee (NWCC) conducted an assessment of distributed wind power. The project team was led by Princeton Economic Research, Inc., now known as Princeton Energy Resources International (PERI). Financial support was provided by the US Department of Energy (DOE) through the wind energy program at the National Renewable Energy Laboratory (NREL) and the Electric Power Research Institute (EPRI). Project oversight and review were provided by NWCC's Distributed Working Group. The overall objective for the NWCC assessment was to enhance understanding of business, policy, and technical issues associated with the deployment of wind-electric generating systems in the distributed-generation mode. In general, that mode is defined by placement of the generation close to customers-in contrast to large, distant central stations-and by electrical interconnection to the local distribution system-in contrast to higher voltage electrical transmission systems. As a follow-up to the assessment, NWCC intends to prepare a consensus-based issue brief that summarizes its findings and highlights the major results and conclusions for each stakeholder sector. This brief will also identify key action steps that could be undertaken by each stakeholder sector to facilitate the growth of distributed wind. The aim of this paper is to provide …

Starting from the microscopic light-matter interaction in form of the minimal coupling Hamiltonian, the multipole approximation for the optical response of localized electrons in atomic systems is extended to delocalized electrons in solids. A spatial averaging procedure is used to derive the electromagnetic sources for macroscopic Maxwell's equations as well as the corresponding many particle Hamiltonian on a coarse grained length scale. The results are illustrated for semiconductor bulk material up to quadruple moments for the interband transitions, where gauge invariant equations of motion for the optical response are obtained.

Electrical grounding is probably the most over-looke~ ignored, and misunderstood part of electrical energy source circuits. A faulty ground circuit am have lethal potential to the worker, can damage electrical equipment" or components, and can lead to higher consequences. For example, if the green-wire ground return circuit (in a three-wire power circuit) is fhulty or is open (someone cut the prong, etc.) a person can receive an electrical shock by touching the conductive enclosure, and the result can be lethal. If high explosives are involved m the process, sneak electrical energy paths may cause electrical threats that lead to ignition, which results to higher damage consequences. Proper electrical grounding is essential to mitigate the electrical hazard and improve work place safety. A designer must ask the question, "What grounding is proper?" continuously through a process design and in its application. This question must be readdressed with any process change, including tiom layout, equipment, or procedure changes. Electrical grounding varies ilom local work area grounding to the multi-point grounding found in large industrial areas. These grounding methods become more complex when the designer adds bonding to the grounding schemes to mitigate electrostatic discharge (ESD) and surfkce potentials resulting from lightning currents …

The U. S. Department of Energy (DOE) has recognized that safety assurance requires a balance of institutional and engineering approaches as part of an ongoing safety process. This recognition formed the basis for a new approach to nuclear explosive safety with a focus on the inherent value of the examination process, as opposed to an absolute justification of the nuclear explosive operation against some preddined acceptance criteria. This new approach to safety is reflected in recent DOE Orders and Standards in that there is no requirement that quantitative risk assessment or risk quantification be used in meeting requirements. Furthermore, there is no requirement to compare hazard and accident analysis results against numerical acceptance criteria. This paper discusses the evolution of the DOE nuclear explosive safety orders and compares those with facility safety requirements. The DOE nuclear explosive safety process is examined, and an example application is discussed with emphasis on identification of safety measures and controls.

This paper reports on the feasibility of using Acoustic Emission (AE) for sensing the proximity of a grinding wheel to a glass workpiece, both prior to contact and in the early stages of contact. Our measured AE signals indicate that we can track the position of the grinding wheel as it approaches the workpiece through the turbulent coolant layer and than as contact initiates with a workpiece during spherical generation. Our data for the initial contact region is dominated by cyclical bursts of AE that appear to correspond to tool spindle motion errors. Our principal goal is to minimize the time required to {open_quote}find the part{close_quote} without damaging the surface of a brittle workmaterial, i.e. during the transition from a fast approach to the much slower final in-feed required for the grinding operation. Our results also suggest that AE is useful as a gauging signal in determining the position of the grinding wheel with respect to the machine tool.

Microscopic time reversibility and macroscopic irreversibility are a paradoxical combination. This was first observed by J. Loschmidt in 1876 and was explained, for conservative systems, by L. Boltzmann the following year. Both these features are also present in modern simulations of classic many-body systems in steady nonequilibrium states. We illustrate them here for the simplest possible models, a continuous one-dimensional model of field-driven diffusion, the so-called driven Lorentz gas or Galton Board, and an ergodic time reversible dissipative map.

This paper describes a relatively inexpensive, fast, and easy to execute approach to mapping the volumetric errors of a machine tool, coordinate measuring machine, or robot. An error map is used to characterize a machine or to improve its accuracy by compensating for the systematic errors. The method consists of three steps: (1) modeling the relationship between the volumetric error and the current state of the machine; (2) acquiring error data based on length measurements throughout the work volume; and (3) optimizing the model to the particular machine.

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.

Due to the higher currents (and therefore higher losses) compared to individual wires and tapes, the ac loss characterization of HTS cable conductors carrying transport current can be performed using calorimetric as well as electrical methods. We discuss the main features of two calorimetric methods, one based on temperature profile determination, and one, more recently developed, based on nitrogen boil-off rate, and of the electrical method, substantially derived from that already established for tapes, based on voltage measurement by a Lock-In amplifier. Advantages and limits of each approach are analyzed and compared. Tests have been carried out with the three methods on samples 1 to 1.5 m long cut from a Bi-2223 cable conductor prototype fabricated by Pirelli in a longer length. Results obtained from measurements covering a wide range of currents are compared and thoroughly discussed.

We discuss the electromagnetic form factors, axial form factors, and structure functions of a nucleon bound in the quark-meson coupling (QMC) model. Free space nucleon form factors are calculated using the improved cloudy bag model (ICBM). After describing finite nuclei and nuclear matter in the quark-based (EMC) model, the in-medium modification of the bound nucleon form factors is calculated in the same model. Finally, the bound nucleon structure function, F2, is extracted using the calculated in-medium electromagnetic form factors and Bloom-Gilman (quark-hadron) duality.

Recent developments in solid-state radio frequency (RF) power technologies allow for the practical consideration of RF heated plasmas for space propulsion. These technologies permit the use of any electrical power source, de-couple the power and propellant sources, and allow for the effcient use of both the propellant mass and power. Effcient use of the propellant is obtained by expelling the rocket exhaust at the highest possible velocity, which can be orders of magnitude higher than those achieved in chemical rockets. Handling the hot plasma exhaust requires the use of magnetic nozzles, and the basic physics of ion detachment from the magnetic #12;eld is discussed. The plasma can be generated by RF using helicon waves to heat electrons. Further direct heating of the ions helps to reduce the line radiation losses, and the magnetic geometry is tailored to allow ion cyclotron resonance heating. RF #12;eld and ion trajectory calculations are presented to give a reasonably self-consistent picture of the ion acceleration process.

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Study assesses food choice priorities (FCP) and associations with consumption of fruits and vegetables (FV), fiber, added sugars from non-beverage sources, and sugar-sweetened beverages (SSB) among college students, and how those choices evolve over their first year of college.

An online article that is an overview of the instructional unit guidelines for the National Arts Education Consortium.

This article investigates how the structural mix of USA regional economies affects their volatility of economic growth using four exogenous sectors: Federal Government, construction, manufacturing, and tourism. Results suggest that a larger share of Federal Government employment in an economy reduces the variability of overall employment growth, while a larger share of construction activity elevates it. Results also show that recently manufacturing has not contributed as much to such variability, and that a larger tourism presence increases it. The increasing integration of technology in tourism offers significant opportunities for a network approach and innovation in regional development.

A new experiment has been proposed at Los Alamos National Laboratory to measure the neutron electric dipole moment (EDM) to 4x10{sup {minus}28} ecm, a factor of 250 times better than the current experimental limit. Such a measure of the neutron EDM would challenge the theories of supersymmetry and time reversal violation as the origin of the observed cosmological asymmetry in the ratio of baryons to antibaryons. One possible design for this new experiment includes the use of LTC SQUIDs coupled to large ({approximately}100 cm{sup 2}) pick-up coils to measure the precession frequency of the spin-polarized {sup 3}He atoms that act as polarizer, spin analyzer, detector, and magnetometer for the ultra-cold neutrons used in the experiment. The method of directly measuring the {sup 3}He precession signal eliminates the need for very uniform magnetic fields (a major source of systematic error in these types of experiments). It is estimated that a flux of {approximately}2x10{sup {minus}16} Tm{sup 2} (0.1 F{sub 0}) will be coupled into the pick-up coils. To achieve the required signal-to-noise ratio one must have a flux resolution of d F{sub SQ}=2x10{sup {minus}6} F{sub 0}/{radical}Hz at 10 Hz. While this is close to the sensitivity available in commercial devices, the effects …

The pressure dependence of the photoluminescence (PL) transition associated with the fundamental band gap of ZnO nanowires has been studied at pressures up to 15 GPa. ZnO nanowires are found to have a higher structural phase transition pressure around 12 GPa as compared to 9.0 GPa for bulk ZnO. The pressure-induced energy shift of the near band-edge luminescence emission yields a linear pressure coefficient of 29.6 meV/GPa with a small sublinear term of -0.43 meV/GPa{sup 2}. An effective hydrostatic deformation potential -3.97 eV for the direct band gap of the ZnO nanowires is derived from the result.