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A wave-optical model that is coupled to a microscopic gain theory is used to investigate lateral mode behavior in group III nitride quantum well lasers. Beam filamentation due to self-focusing in the gain medium is found to limit fundamental-mode output to narrow stripe lasers or to operation close to lasing threshold. Differences between nitride and conventional near-infrared semiconductor lasers arise because of band structure differences, in particular, the presence of a strong quantum-confined Stark effect in the former. Increasing mirror reflectivities in plane-plane resonators to reduce lasing threshold current tends to exacerbate the filamentation problem. On the other hand, a negative-branch unstable resonator is found to mitigate filament effects, enabling fundamental-mode operation far above threshold in broad-area lasers.

A Pollution Prevention project at Dow Chemical's Midland, MI site demonstrates that many opportunities exist for pollution prevention at other large facilities.

On July 28, 1998 a devastating accident occurred at the Test Reactor Area of the Idaho National Engineering and Environmental Laboratory (INEEL). The accident cost a man his life and caused injury to others. In addition to the significant human loss, Lockheed Martin (LMITCO) experienced economic losses that reached millions of dollars. LMITCO eventually lost the managing and operating contract of a premier Department of Energy Laboratory. Just as with the INEEL, companies throughout industry today must face an ever increasingly complex world of government alphabet soup of regulations—OSHA, CAA, TSCA, FIFRA, ADA, and more. For businesses, non-compliance can quickly evaporate profits. For humans, mistakes can seriously affect health, and some work areas are so complicated that a single event could cost human life. Finally, adherence to the regulations can protect the community and the environment. Compliance with regulations is essential and multifaceted. Regulations require interpretation into company policy. Policies must be implemented as standard work practices. The workforce must be trained to follow the procedures. Management must coordinate flow down of requirements and policy for standardized work planning processes and consistent compliance with regulations. Implementing controls to ensure absolute compliance can be a very costly and cumbersome effort, thus, …

Asymmetries in the quark momentum distributions in the proton reveal fundamental aspects of strong interaction physics. Differences between {anti u} and {anti d} quarks in the proton sea provide insight into the dynamics of the pion cloud around the nucleon and the nature of chiral symmetry breaking. Polarized flavor asymmetries allow the effects of pion clouds to be disentangled from those of antisymmetrization. Asymmetries between s and {anti s} quark distributions in the nucleon are also predicted from the chiral properties of QCD.

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Spontaneous radiation emitted from an electron undergoing betatron motion is a plasma focusing channel is analyzed and applications to plasma wakefield accelerator experiments and to the ion channel laser (ICL) are discussed. Important similarities and differences between a free electron laser (FEL) and in an ICL are delineated. It is shown that the frequency of spontaneous radiation is a strong function of the betatron strength parameter a{sub {beta}}, which plays a similar role to that of the wiggler strength parameter in a conventional FEL. For a{sub {beta}} {approx_gt} 1, radiation is emitted in numerous harmonics. Furthermore, a{sub {beta}} is proportional to the amplitude of the betatron orbit, which varies for every electron in the beam. This places serious limits on the possibility of realizing an ICL.

There is currently no effective combination of interoperable design tools to cover all critical aspects of the HVAC design process. Existing design tools are separately available, but require expertise and operating time that is beyond the scope of a normal design project. For example, energy analysis and computational fluid dynamics (CFD) tools are not used in practical design, leading to poor indoor air quality and/or unnecessary energy consumption in buildings. A prototype integrated software tool for demonstration, process mapping and proof-of-concept purposes was developed under a new international, Finland/USA jointly funded development project BildIT. Individual design tools were simplified and adapted to specific applications and also integrated so that they can be used in a timely and effective manner by the designer. The core of the prototype linked together an architectural CAD system, a 3D space model, a CFD program and a building energy simulation program and it utilizes real product data from manufacturer's software. Also the complex building design, construction, maintenance and retrofit processes were mapped to get a template for the structure of the integrated design tool.

Beam position monitor (BPM) signal-processing electronics utilizing the Analog Devices AD8307 logarithmic amplifier has been developed for the Low Energy Demonstration Accelerator (LEDA), part of the Accelerator Production of Tritium (APT) project at Los Alamos. The low-pass filtered 350 MHz fundamental signal from each of the four microstrip electrodes in a BPM is ''detected'' by an AD8307 log amp, amplified and scaled to accommodate the 0 to +5V input of an analog-to-digital (A/D) converter. The resultant four digitized signals represent a linear power relationship to the electrode signals, which are in turn related to beam current and position. As the AD8307 has a potential dynamic range of approximately 92 dB, much attention must be given to noise reduction, sources of which can be digital signals on the same board, power supplies, inter-channel coupling, stray RF and others. This paper will describe the operational experience of this particular analog front-end electronic circuit design.

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By combining newly developed technologies to engineer composite laser components with state of the art diode laser pump delivery technologies, we are in a position to demonstrate high beam quality, continuous wave, laser radiation at scaleable high average powers. The crucial issues of our composite thin disk laser technology were demonstrated during a successful first light effort. The high continuous wave power levels that are now within reach make this system of high interest to future DoD initiatives in solid-state laser technology for the laser weapon arena.

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The Accelerated Strategic Computing Initiative (ASCI) computational grid is being constructed to interconnect the high performance computing resources of the nuclear weapons complex. The grid will simplify access to the diverse computing, storage, network, and visualization resources, and will enable the coordinated use of shared resources regardless of location. To match existing hardware platforms, required security services, and current simulation practices, the Globus MetaComputing Toolkit was selected to provide core grid services. The ASCI grid extends Globus functionality by operating as an independent grid, incorporating Kerberos-based security, interfacing to Sandia's Cplant{trademark},and extending job monitoring services. To fully meet ASCI's needs, the architecture layers distributed work management and criteria-driven resource selection services on top of Globus. These services simplify the grid interface by allowing users to simply request ''run code X anywhere''. This paper describes the initial design and prototype of the ASCI grid.

We present an entirely new method for measuring residual stress that is extremely simple to apply yet more powerful than existing techniques. In this method, a part is carefully cut in two. The contour of the resulting new surface is measured to determine the displacements normal to the surface caused by the release of the residual stresses. Analytically, the opposite of these measured displacements are applied as boundary conditions to the surface in a finite element model. By Bueckner's superposition principle, this gives the original residual stresses normal to the plane of the cut. Unlike other relaxation methods for measuring residual stress, the measured data can be used to solve directly for the stresses without a tedious inversion technique. At the same time, an arbitrary two-dimensional variation in stresses can be determined. We demonstrate the method on a steel specimen with a known residual stress profile.

City streets are usually paved with asphalt concrete because this material gives good service and is relatively inexpensive to construct and maintain. We show that making asphalt pavements cooler, by increasing their reflection of sunlight, may lead to longer lifetime of the pavement, lower initial costs of the asphalt binder, and savings on street lighting and signs. Excessive glare due to the whiter surface is not likely to be a problem.

Habitat corridors have been proposed to reduce patch isolation and increase population persistence in fragmented landscapes. This study tested whether patch colonization was increased by the presence and various length corridors. The specific butterfly species tested has been shown to use corridors, however, the results indicate that neither the distance between patches or the presence of a corridor influenced colonization.

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This paper reports on the design, simulation, and preliminary testing of a three phase variable reluctance stepping motor. This motor is pancake-shaped with an overall outside diameter of 8 mm and a height of 3 mm. The outside diameter of the rotor is 4.7 mm. The rotor and stators occupy 2 mm of the height with the remaining 1 mm reserved for a 6:1 planetary gear reductor. The rotor and stators were constructed of Hyperco 50 using conventional miniature machining. The reductor was assembled using copper and PMMA (polymethylmethacrylate) components that were constructed using the LIGA (Lithographic Galvanoformung Abformung) microfabrication process. The maximum measured stall torque of the motor without the reductor is 0.47mNm at 4W and the maximum speed is 2,400 rpm.

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The astrophysical S factor for the {sup 7}Be(p, {gamma}){sup 8}B reaction at threshold is investigated using simple models to determine the model dependence in the extrapolation of the laboratory data to the region of astrophysical interest near 20 keV. We find that the energy dependence below 400 keV is largely well understood in terms of the Coulomb interaction and constrained by the data for the elastic scattering of low-energy neutrons from {sup 7}Li.

The status of ''ab initio'' microscopic calculations of the {sup 2}H(p,{gamma}){sup 3}He and {sup 3}He(p,e{sup +}{nu}{sub e}){sup 4}He reactions is reviewed. The methods used to generate accurate nuclear ground- and scattering-state wave functions, and to construct realistic electro-weak transition operators are described. The uncertainties in the theoretical predictions, particularly those relevant to the p-{sup 3}He weak capture, are discussed. For the dp radiative capture, the theoretical results are compared with the TUNL data in the energy range 0--100 keV.