A 2-inch schedule 40 steel core pipe in an evaporator overheads discharge line broke at several locations downstream from a section of the line where it bridges a road. Fish mouth openings that developed along the pipe seams were initiated at lack of fusion defects in the pipe welds. A vacuum created in the piping upstream of the breaks prevented full drainage of the water upon shut down of the pump. Freezing of water in the pipe (the line was not heat traced) and water hammer effects occurring with pump restart could each contribute to the extensive deformation and tearing observed at the breaks. Both the weld flaws and the over pressure contributed to the outcome. All pipe was replaced and a vacuum break was installed to eliminate the problem.

The gap between peak and delivered performance for scientific applications running on microprocessor-based systems has grown considerably in recent years. The inability to achieve the desired performance even on a single processor is often attributed to an inadequate memory system, but without identification or quantification of a specific bottleneck. In this work, we use an adaptable synthetic benchmark to isolate application characteristics that cause a significant drop in performance, giving application programmers and architects information about possible optimizations. Our adaptable probe, called sqmat, uses only four parameters to capture key characteristics of scientific workloads: working-set size, computational intensity, indirection, and irregularity. This paper describes the implementation of sqmat and uses its tunable parameters to evaluate four leading 64-bit microprocessors that are popular building blocks for current high performance systems: Intel Itanium2, AMD Opteron, IBM Power3, and IBM Power4.

The lateral organization of lipids and membrane-associated proteins in biological membranes is often detected by fluorescence microscopy. Although extremely sensitive, fluorescent labels, particularly those attached to lipid molecules, may alter their physical properties.

The Numerical Electromagnetics Code, NEC as it is commonly known, continues to be one of the more widely used antenna modeling codes in existence. With several versions in use that reflect different levels of capability and availability, there are now 450 copies of NEC4 and 250 copies of NEC3 that have been distributed by Lawrence Livermore National Laboratory to a limited class of qualified recipients, and several hundred copies of NEC2 that had a recorded distribution by LLNL. These numbers do not account for numerous copies (perhaps 1000s) that were acquired through other means capitalizing on the open source code, the absence of distribution controls prior to NEC3 and the availability of versions on the Internet. In this paper we briefly review the history of the code that is concisely displayed in Figure 1. We will show how it capitalized on the research of prominent contributors in the early days of computational electromagnetics, how a combination of events led to the tri-service-supported code development program that ultimately led to NEC and how it evolved to the present day product. The authors apologize that space limitations do not allow us to provide a list of references or to acknowledge the numerous …

With rapid developments in wireless sensor networks, there is a growing need for transceiver position estimation independent of GPS, which may not be available in indoor networks. Our approach is to use range estimates from time-of-flight (TOF) measurements, a technique well suited to large bandwidth physical links, such as in ultra-wideband (UWB) systems. In our UWB systems, pulse duration less than 200 psecs can easily be resolved to less than a foot. Assuming an encoded UWB physical layer, we first test positioning accuracy using simulations. We are interested in sensitivity to range errors and the required number of ranging nodes, and we show that in a high-precision environment, such as UWB, the optimal number of transmitters is four. Four transmitters with {+-}20ft. range error can locate a receiver to within one or two feet. We then implement these algorithms on an 802.11 wireless network and demonstrate the ability to locate a network access point to approximately 20 feet.

A nondimensional model of the multifrequency radiation diffusion equation is derived. A single material, ideal gas, equation of state is assumed. Opacities are proportional to the inverse of the cube of the frequency. Inclusion of stimulated emission implies a Wien spectrum for the radiation source function. It is shown that the solutions are uniformly bounded in time and that stationary solutions are stable. The spatially independent solutions are asymptotically stable, while the spatially dependent solutions of the linearized equations approach zero.

We have synthesized ternary and quaternary diluted II-VI oxides using the combination of O ion implantation and pulsed laser melting. CdO{sub x}Te{sub 1-x} thin films with x up to 0.015, and the energy gap reduced by 150 meV were formed by O{sup +}-implantation in CdTe followed by pulsed laser melting. Quaternary Cd{sub 0.6}Mn{sub 0.4}O{sub x}Te{sub 1-x} and Zn{sub 0.88}Mn{sub 0.12}O{sub x}Te{sub 1-x} with mole fraction of incorporated O as high as 0.03 were also formed. The enhanced O incorporation in Mn-containing alloys is believed to be due to the formation of relatively strong Mn-O bonds. Optical transitions associated with the lower (E{sub -}) and upper (E{sub +}) conduction subbands resulting from the anticrossing interaction between the localized O states and the extended conduction states of the host are clearly observed in these quaternary diluted II-VI oxides. These alloys fulfill the criteria for a multiband semiconductor that has been proposed as a material for making high efficiency, single-junction solar cells.

It has recently been reported that several high power, diode-pumped laser systems have been developed based on crystals of Yb:S-FAP [Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F]. The Mercury Laser, at Lawrence Livermore National Laboratory, is the most prominent system using Yb:S-FAP and is currently producing 23J at 5 Hz in a 15 nsec pulse, based on partial activation of the system. In addition, a regenerative amplifier is being developed at Waseda University in Japan and has produced greater than 12 mJ with high beam quality at 50Hz repetition rate. Q-peak has demonstrated 16 mJ of maximum energy/output pulse in a multi-pass, diode side-pumped amplifier and ELSA in France is implementing Yb:S-FAP in a 985 nm pump for an EDFA, producing 250 mW. Growth of high optical quality crystals of Yb:S-FAP is a challenge due to multiple crystalline defects. However, at this time, a growth process has been developed to produce high quality 3.5 cm diameter Yb:S-FAP crystals and a process is under development for producing 6.5 cm diameter crystals.

The BTeV Collaboration is starting to develop its C++ based offline software suite, an integral part of which is a series of tutorials. These tutorials are targeted at a diverse audience, including new graduate students, experienced physicists with little or no C++ experience, those with just enough C++ to be dangerous, and experts who need only an overview of the available tools. The tutorials must both teach C++ in general and the BTeV specific tools in particular. Finally, they must teach physicists how to find and use the detailed documentation. This report will review the status of the BTeV experiment, give an overview of the plans for and the state of the software and will then describe the plans for the tutorial suite.

We have fitted the Chandra Low Energy Transmission Grating spectrum of SS Cygni in outburst with a single temperature blackbody suffering the photoelectric opacity of a neutral column density and the scattering opacity of an outflowing wind. We find that this simple model is capable of reproducing the essential features of the observed spectrum with the blackbody temperature T{sub bl} {approx} 250{+-}50 kK, hydrogen column density N{sub H} {approx} 5.0{sup +2.9}{sub -1.5}x10{sup 19} cm{sup -2}, fractional emitting area f {approx} 5.6{sup +60}{sub -4.5} x10{sup -3}, boundary layer luminosity Lbl {approx} 5{sup +18}{sub -3} x10{sup 33} erg s{sup -1}, wind velocity v {approx} 2500 km s{sup -1}, wind mass-loss rate w {approx} 1.1x10{sup 16} g s{sup -1}, and arbitrary values of the wind ionization fractions of 20 ions of O, Ne,Mg, Si, S, and Fe. Given that in outburst the accretion disk luminosity L{sub disk} {approx}1x10{sup 35} erg s{sup -1}, L{sub bl}/L{sub disk} {approx} 0.05{sup +0.18}{sub -0.03}, which can be explained if the white dwarf (or an equatorial belt thereon) is rotating with an angular velocity {Omega}{sub wd} {approx} 0.7{sup +0.1}{sub -0.2}Hz, hence V{sub rot}sini {approx} 2300 km s{sup -1}.

The Internet and the World Wide Web have enabled a publishing explosion of useful online information, which has produced the unfortunate side effect of information overload: it is increasingly difficult for individuals to keep abreast of fresh information. In this paper we describe an approach for building a system for efficiently monitoring changes to Web documents. This paper has three main contributions. First, we present a coherent framework that captures different characteristics of Web documents. The system uses the Page Digest encoding to provide a comprehensive monitoring system for content, structure, and other interesting properties of Web documents. Second, the Page Digest encoding enables improved performance for individual page monitors through mechanisms such as short-circuit evaluation, linear time algorithms for document and structure similarity, and data size reduction. Finally, we develop a collection of sentinel grouping techniques based on the Page Digest encoding to reduce redundant processing in large-scale monitoring systems by grouping similar monitoring requests together. We examine how effective these techniques are over a wide range of parameters and have seen an order of magnitude speed up over existing Web-based information monitoring systems.

A vacuum crystal spectrometer with nominal resolving power approaching 1000 is described for measuring emission lines with wavelength in the extreme ultraviolet region up to 60 Angstroms. The instrument utilizes a flat octadecyl hydrogen maleate (OHM) crystal and a thin-window 1-D position-sensitive gas proportional detector. This detector employs a 1 {micro}m-thick 100 x8 mm{sup 2} aluminized polyimide window and operates at one atmosphere pressure. The spectrometer has been implemented on the Livermore electron beam ion traps. The performance of the instrument is illustrated in measurements of the newly discovered magnetic field-sensitive line in Ar{sup 8+}.

The second annual conference on optical engineering at Lawrence Livermore National Laboratory (LLNL) focused entirely on National Ignition Facility (NIF) activities. NIF's 192-beam UV laser system is the world's largest optical and optomechanical system. This past year, a decade-long design, construction, fabrication, and installation effort culminated in the commissioning of the first four laser beams in this 30,000 square meter facility. This flashlamp-pumped Nd:glass laser system is built on a scale unprecedented in laser R&D. Nearly every aspect of the NIF design is unconventional, from the 40 x 40-cm-square size of each beam, to the 40 varieties of telephone-booth-size modular optical assemblies, to the elevated configuration of the 200-m-long, class-100 beamlines that converge on a 10-m-diameter target chamber. A large technical staff and many industrial partners were needed to reach the current state of accomplishment, including development of a number of advanced optical materials and fabrication technologies.

A major research goal of the national spherical torus experiment is establishing long-pulse, high beta, high confinement operation and its physics basis. This research has been enabled by facility capabilities developed during 2001 and 2002, including neutral beam (up to 7MW) and high harmonic fast wave (HHFW) heating (up to 6 MW), toroidal fields up to 6 kG, plasma currents up to 1.5 MA, flexible shape control, and wall preparation techniques. These capabilities have enabled the generation of plasmas with {beta}{sub T} {equivalent_to} {l_angle}p{r_angle}/(B{sup 2}{sub T0}/2{mu}{sub 0}) of up to 35%. Normalized beta values often exceed the no-wall limit, and studies suggest that passive wall mode stabilization enables this for H mode plasmas with broad pressure profiles. The viability of long, high bootstrap current fraction operations has been established for ELMing Hmode plasmas with toroidal beta values in excess of 15% and sustained for several current relaxation times. Improvements in wall conditioning and fuelling are likely contributing to a reduction in Hmode power thresholds. Electron thermal conduction is the dominant thermal loss channel in auxiliary heated plasmas examined thus far. HHFW effectively heats electrons, and its acceleration of fast beam ions has been observed. Evidence for HHFW current drive is …

This research and development project was sponsored by the United States Bureau of Reclamation (USBR), who are best known for the dams, power plants, and canals it constructed in the 17 western states. The mission statement of the USBR's Dam Safety Office, located in Denver, Colorado, is ''to ensure Reclamation dams do not present unacceptable risk to people, property, and the environment.'' The Dam Safety Office does this by quickly identifying the dams which pose an increased threat to the public, and quickly completing the related analyses in order to make decisions that will safeguard the public and associated resources. The research study described in this report constitutes one element of USBR's research and development work to advance their computational and analysis capabilities for studying the response of dams to strong earthquake motions. This project focused on the seismic response of Morrow Point Dam, which is located 263 km southwest of Denver, Colorado.

A modeling investigation was performed to choose moderator material and size for creating optimal epithermal neutron beams for BNCT based on a proton accelerator and the 7Li(p,n)7Be reaction as a neutrons source. An optimal configuration is suggested for the beam shaping assembly made from polytetrafluoroethylene and magnesium fluorine. Results of calculation were experimentally tested and are in good agreement with measurements.

Sea hare species within the Aplysia clade are distributed worldwide. Their phylogenetic and biogeographic relationships are, however, still poorly known. New molecular evidence is presented from a portion of the mitochondrial cytochrome oxidase c subunit 1 gene (cox1) that improves our understanding of the phylogeny of the group. Based on these data a preliminary discussion of the present distribution of sea hares in a biogeographic context is put forward. Our findings are consistent with only some aspects of the current taxonomy and nomenclatural changes are proposed. The first, is the use of a rank free classification for the different Aplysia clades and subclades as opposed to previously used genus and subgenus affiliations. The second, is the suggestion that Aplysia brasiliana (Rang, 1828) is a junior synonym of Aplysia fasciata (Poiret, 1789). The third, is the elimination of Neaplysia since its only member is confirmed to be part of the large Varria clade.

The acceleration of the expansion of the universe arises from unknown physical processes involving either new fields in high energy physics or modifications of gravitation theory. It is crucial for our understanding to characterize the properties of the dark energy or gravity through cosmological observations and compare and distinguish between them. In fact, close consistencies exist between a dark energy equation of state function w(z) and changes to the framework of the Friedmann cosmological equations as well as direct spacetime geometry quantities involving the acceleration, such as ''geometric dark energy'' from the Ricci scalar. We investigate these interrelationships, including for the case of super acceleration or phantom energy where the fate of the universe may be more gentle than the Big Rip.

We have conducted a detailed numerical analysis of HCCI engine operation at low loads to investigate the sources of HC and CO emissions and the associated combustion inefficiencies. Engine performance and emissions are evaluated as fueling is reduced from typical HCCI conditions, with an equivalence ratio f = 0.26 to very low loads (f = 0.04). Calculations are conducted using a segregated multi-zone methodology and a detailed chemical kinetic mechanism for iso-octane with 859 chemical species. The computational results agree very well with recent experimental results. Pressure traces, heat release rates, burn duration, combustion efficiency and emissions of hydrocarbon, oxygenated hydrocarbon, and carbon monoxide are generally well predicted for the whole range of equivalence ratios. The computational model also shows where the pollutants originate within the combustion chamber, thereby explaining the changes in the HC and CO emissions as a function of equivalence ratio. The results of this paper contribute to the understanding of the high emission behavior of HCCI engines at low equivalence ratios and are important for characterizing this previously little explored, yet important range of operation.

An effort has been started to measure the short pulse laser absorption and energy partition at relativistic laser intensities up to 10{sup 21} W/cm{sup 2}. Plasma polarization spectroscopy is expected to play an important role in determining fast electron generation and measuring the electron distribution function.

In a recent paper it has been shown that the nuclear Ramsauer model does not do well in representing details of the angular distribution of neutron elastic scattering for incident energies of less than 60 MeV for {sup 208}Pb. We show that the default angular bin dispersion most widely used in Monte Carlo transport codes is such that the observed differences in angular shapes are on too fine a scale to affect transport calculations. The effect of increasing the number of Monte Carlo angle bins is studied to determine the dispersion necessary for calculations to be sensitive to the observed discrepancies in angular distributions. We also show that transport calculations are sensitive to differences in the elastic scattering cross section given by recent fits of {sup 208}Pb data compared with older fits.

We have successfully developed a practical approach to predicting the location of skin surface dose at potential biopsy sites that receive 1 cGy and 10 cGy, respectively, in support of in vivo biologic dosimetry in humans. This represents a significant technical challenge as the sites lie on the patient surface out side the radiation fields. The PEREGRINE Monte Carlo simulation system was used to model radiation dose delivery and TLDs were used for validation on a phantom and confirmation during patient treatment. In the developmental studies the Monte Carlo simulations consistently underestimated the dose at the biopsy site by approximately 15% for a realistic treatment configuration, most likely due to lack of detail in the simulation of the linear accelerator outside the main beam line. Using a single, thickness-independent correction factor for the clinical calculations, the average of 36 measurements for the predicted 1 cGy point was 0.985 cGy (standard deviation: 0.110 cGy) despite patient breathing motion and other real world challenges. Since the 10 cGy point is situated in the region of high dose gradient at the edge of the field, patient motion had a greater effect and the six measured points averaged 5.90 cGy (standard deviation: 1.01 cGy), …

This research was conducted to investigate the feasibility of applying microbial biodegradation as a treatment technology for wastes containing radioactive elements and organic solvents (mixed wastes). In this study, we focused our efforts on the treatment of wastes generated by biomedical research as the result of purifying tritium labeled compounds by high-performance liquid chromatography (HPLC). These wastes are typically 80 percent water with 20 percent acetonitrile or methanol or a mixture of both. The objective was to determine the potential of using biodegradation to treat the solvent component of tritiated mixed waste to a concentration below the land disposal restriction standard (1mg/L for acetonitrile). Once the standard is reached, the remaining radioactive waste is no longer classified as a mixed waste and it can then be solidified and placed in a secure landfill. This investigation focused on treating a 10 percent acetonitrile solution, which was used as a non-radioactive surrogate for HPLC waste, in a bioreactor. The results indicated that the biodegradation process could treat this solution down to less than 1 mg/L to meet the land disposal restriction standard.

A novel, but general, arrangement of parallel sets of gratings is presented that can effectively increase the dispersion of pulse compressors and expanders by over an order of magnitude. These arrangements will dramatically reduce the footprint of the pulse compressors and expanders used in CPA.