The accuracy of a numerical method for solving the neutron transport equation is limited by the smallest mean free path in the problem. Since problems in the asymptotic diffusive regimes have vanishingly small mean free paths, it seems hopeless, given a limited amount of computer memory, that an accurate solution can be obtained for these problems. However we found that the accuracy of a numerical method improves as the scattering ratio increases with the total cross section and the grid spacing held fixed for problems that are in the asymptotic diffusive regime. This phenomenon is independent of the numerical method and can be explained on physical grounds. The numerical results by the Diamond Difference Method are given to show this phenomenon.

Since the U. S. Department of Energy (DOE) published the DOE Beryllium Rule (10 CFR 850) in 1999, DOE sites have been required to measure beryllium on air filters and wipes for worker protection and for release of materials from beryllium-controlled areas. Measurements in the nanogram range on a filter or wipe are typically required. Industrial hygiene laboratories have applied methods from various analytical compendia, and a number of issues have emerged with sampling and analysis practices. As a result, a committee of analytical chemists, industrial hygienists, and laboratory managers was formed in November 2003 to address the issues. The committee developed a baseline questionnaire and distributed it to DOE sites and other agencies in the U.S. and U.K. The results of the questionnaire are presented in this paper. These results confirmed that a wide variety of practices were in use in the areas of sampling, sample preparation, and analysis. Additionally, although these laboratories are generally accredited by the American Industrial Hygiene Association (AIHA), there are inconsistencies in performance among accredited labs. As a result, there are significant opportunities for development of standard methods that could improve consistency. The current availabilities and needs for standard methods are further discussed in …

We study conditions for the existence of asymptotic observables in cosmology. With the exception of de Sitter space, the thermal properties of accelerating universes permit arbitrarily long observations, and guarantee the production of accessible states of arbitrarily large entropy. This suggests that some asymptotic observables may exist, despite the presence of an event horizon. Comparison with decelerating universes shows surprising similarities: Neither type suffers from the limitations encountered in de Sitter space, such as thermalization and boundedness of entropy. However, we argue that no realistic cosmology permits the global observations associated with an S-matrix.

any single computer program for seismic data analysis will not have all the capabilities needed to study reference events, since hese detailed studies will be highly specialized. It may be necessary to develop and test new algorithms, and then these special ;odes must be integrated with existing software to use their conventional data-processing routines. We have investigated two neans of establishing communications between the legacy and new codes: CORBA and XML/SOAP Web services. We have nvestigated making new Java code communicate with a legacy C-language program, geotool, running under Linux. Both methods vere successful, but both were difficult to implement. C programs on UNIX/Linux are poorly supported for Web services, compared vith the Java and .NET languages and platforms. Easier-to-use middleware will be required for scientists to construct distributed applications as easily as stand-alone ones. Considerable difficulty was encountered in modifying geotool, and this problem shows he need to use component-based user interfaces instead of large C-language codes where changes to one part of the program nay introduce side effects into other parts. We have nevertheless made bug fixes and enhancements to that legacy program, but t remains difficult to expand it through communications with external software.

Fouling problems are perhaps the single most important reason for relatively slow acceptance of ultrafiltration in many areas of chemical and biological processing. To overcome the losses in permeate flux associated with concentration polarization and fouling in cross flow membrane filtration, we investigated the concept of flow reversal as a method to enhance membrane flux in ultrafiltration. Conceptually, flow reversal prevents the formation of stable hydrodynamic and concentration boundary layers at or near the membrane surface. Further more, periodic reversal of the flow direction of the feed stream at the membrane surface results in prevention and mitigation of membrane fouling. Consequently, these advantages are expected to enhance membrane flux significantly. A crossflow membrane filtration unit was designed and built to test the concept of periodic flow reversal for flux enhancement. The essential elements of the system include a crossflow hollow fiber membrane module integrated with a two-way valve to direct the feed flow directions. The two-way valve is controlled by a controller-timer for periodic reversal of flow of feed stream. Another important feature of the system is that with changing feed flow direction, the permeate flow direction is also changed to maintain countercurrent feed and permeate flows for enhanced mass …

Displacement measuring interferometer systems and methods are disclosed. One or more acousto-optic modulators for receiving a laser light beam from a laser light source can be utilized to split the laser light beam into two or more laser light beams, while spatially separating frequencies thereof. One or more reflective mechanisms can be utilized to reflect one or more of the laser light beams back to the acoustooptic modulator. Interference of two or more of the laser light beams generally at the acousto-optic modulator can provide an interfered laser light beam thereof. A detector for receiving the interfered laser light beam can be utilized to provide interferometer measurement data.

Solid oxide fuel cell interconnect materials must meet stringent requirements. Such interconnects must operate at temperatures approaching 800 C while resisting oxidation and reduction, which can occur from the anode and cathode materials and the operating environment. They also must retain their electrical conductivity under these conditions and possess compatible coefficients of thermal expansion as the anode and cathode. Results are presented in this report for fuel cell interconnect candidate materials currently under investigation based upon nano-size titanium carbide (TiC) powders. The TiC is liquid phase sintered with either nickel (Ni) or nickel-aluminide (Ni{sub 3}Al) in varying concentrations. The oxidation resistance of the submicron grain TiC-metal materials is presented as a function weight change versus time at 700 C and 800 C for varying content of metal/intermetallic in the system. Electrical conductivity at 800 C as a function of time is also presented for TiC-Ni to demonstrate the vitality of these materials for interconnect applications. TGA studies showed that the weight gain was 0.8 mg/cm{sup 2} for TiC(30)-Ni(30wt.%) after 100 hours in wet air at 800 C and the weight gain was calculated to be 0.5205 mg/cm{sup 2} for TiC(30)- Ni(10 wt.%) after 100 hours at 700 C and 100 …

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Ion current extracted from an ion source (ion thruster) can be increased above the Child-Langmuir limit if the ion space charge is neutralized. Similarly, the limiting kinetic energy density of the plasma flow in a Hall thruster might be exceeded if additional mechanisms of space charge neutralization are introduced. Space charge neutralization with high-mass negative ions or negatively charged dust particles seems, in principle, promising for the development of a high current or high energy density source of positive light ions. Several space charge neutralization schemes that employ heavy negatively charged particles are considered. It is shown that the proposed neutralization schemes can lead, at best, only to a moderate but nonetheless possibly important increase of the ion current in the ion thruster and the thrust density in the Hall thruster.

A new method for the solution of nonlinear dispersive partial differential equations is described. The marker method relies on the definition of a convective field associated with the underlying partial differential equation; the information about the approximate solution is associated with the response of an ensemble of markers to this convective field. Some key aspects of the method, such as the selection of the shape function and the initial loading, are discussed in some details.

The signal in an NMR experiment is highly sensitive to fluctuations of the environment of the sample. If, for example, the static magnetic field B{sub 0}, the amplitude and phase of radio frequency (rf) pulses, or the resonant frequency of the detection circuit are not perfectly stable and reproducible, the magnetic moment of the spins is altered and becomes a noisy quantity itself. This kind of noise not only depends on the presence of a signal, it is in fact proportional to it. Since all the spins at a particular location in a sample experience the same environment at any given time, this noise primarily affects the reproducibility of an experiment, which is mainly of importance in the indirect dimensions of a multidimensional experiment, when intense lines are suppressed with a phase cycle, or for difference spectroscopy techniques. Equivalently, experiments which are known to be problematic with regard to their reproducibility, like flow experiments or experiments with a mobile target, tend to be affected stronger by multiplicative noise. In this article it is demonstrated how multiplicative noise can be identified and characterized using very simple, repetitive experiments. An error estimation approach is developed to give an intuitive, yet quantitative understanding …

View-factor simulations are presented of the spatially varying radiation conditions inside double-ended gold hohlraums and single-ended gold hohlraums (''halfraums'') used in inertial confinement fusion (ICF) and high energy density (HED) physics experiments [J. Lindl, Phys. Plasmas 11, 339 (2004); M. D. Rosen, Phys. Plasmas 3, 1803 (1996)]. It is shown that in many circumstances, the common assumption that the hohlraum ''drive'' can be characterized by a single temperature is too simplistic. Specifically, the radiation conditions seen by an experimental package can differ significantly from the wall reemission measured through diagnostic holes or laser entrance holes (LEHs) by absolutely calibrated detectors. Furthermore, even in situations where the radiation temperature is roughly the same for diagnostics and experimental packages, or for packages at different locations, the spectral energy distributions can vary significantly, due to the differing fractions of reemitting wall, laser hot spots, and LEHs seen from different locations. We find that the spatial variation of temperature, and especially the differences between what diagnostics looking in the LEH measure vs. the radiation temperature on wall-mounted experimental packages, is generally greater for double-ended hohlraums than it is for halfraums. View-factor simulations can also be used to explore experimental variables (halfraum length and geometry, …

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Data Grids provide a convenient environment for researchers to manage and access massively distributed bulk data by addressing several system and transfer challenges inherent to these environments. This work addresses issues involved in the efficient selection and access of replicated data in Grid environments in the context of the Globus Toolkit{trademark}, building middleware that (1) selects datasets in highly replicated environments, enabling efficient scheduling of data transfer requests; (2) predicts transfer times of bulk wide-area data transfers using extensive statistical analysis; and (3) co-allocates bulk data transfer requests, enabling parallel downloads from mirrored sites. These efforts have demonstrated a decentralized data scheduling architecture, a set of forecasting tools that predict bandwidth availability within 15% error and co-allocation architecture, and heuristics that expedites data downloads by up to 2 times.

This project was initially targeted to the making of coke for blast furnaces by using proprietary technology of Calderon in a phased approach, and Phase I was successfully completed. The project was then re-directed to the making of iron units. In 2000, U.S. Steel teamed up with Calderon for a joint effort which will last 42 months to produce directly reduced iron with the potential of converting it into molten iron or steel consistent with the Roadmap recommendations of 1998 prepared by the Steel Industry in cooperation with the Department of Energy by using iron ore concentrate and coal as raw materials, both materials being appreciably lower in cost than using iron pellets and coke.

Pulvirenti et al. (2004) recently conducted a laboratory evaporation/condensation experiment on a synthetic solution of primarily calcium chloride. This solution represents one potential type of evaporated pore water at Yucca Mountain, Nevada, a site proposed for geologic storage of high-level nuclear waste. These authors reported that boiling this solution to near dryness (a concentration factor >75,000 relative to actual pore waters) leads to the generation of acid condensate (pH 4.5) presumably due to volatilization of HCl (and minor HF and/or HNO{sub 3}). To investigate the various processes taking place, including boiling, gas transport, and condensation, their experiment was simulated by modifying an existing multicomponent and multiphase reactive transport code (TOUGHREACT). This code was extended with a Pitzer ion-interaction model to deal with high ionic strength. The model of the experiment was set-up to capture the observed increase in boiling temperature (143 C at {approx}1 bar) resulting from high concentrations of dissolved salts (up to 8 m CaCl{sub 2}). The computed HCI fugacity ({approx} 10{sup -4} bars) generated by boiling under these conditions is not sufficient to lower the pH of the condensate (cooled to 80 and 25 C) down to observed values unless the H{sub 2}O mass fraction in gas …

In the January 2002 edition of SIAM News, Nick Trefethen announced the '$100, 100-Digit Challenge'. In this note he presented ten easy-to-state but hard-to-solve problems of numerical analysis, and challenged readers to find each answer to ten-digit accuracy. Trefethen closed with the enticing comment: 'Hint: They're hard! If anyone gets 50 digits in total, I will be impressed.' This challenge obviously struck a chord in hundreds of numerical mathematicians worldwide, as 94 teams from 25 nations later submitted entries. Many of these submissions exceeded the target of 50 correct digits; in fact, 20 teams achieved a perfect score of 100 correct digits. Trefethen had offered $100 for the best submission. Given the overwhelming response, a generous donor (William Browning, founder of Applied Mathematics, Inc.) provided additional funds to provide a $100 award to each of the 20 winning teams. Soon after the results were out, four participants, each from a winning team, got together and agreed to write a book about the problems and their solutions. The team is truly international: Bornemann is from Germany, Laurie is from South Africa, Wagon is from the USA, and Waldvogel is from Switzerland. This book provides some mathematical background for each problem, and …

Worldwide data on terrorist incidents between 1968 and 2004 gathered by the RAND corporation and the Oklahoma City National Memorial Institute for the Prevention of Terrorism (MIPT) were assessed for patterns and trends in morbidity/mortality. The data involve a total of 19,828 events, 7,401 ''adverse'' events (each causing {ge}1 victim), 91,346 cases of casualty (either injury or death) and 25,408 deaths. Analyses revealed a number of interesting patterns and apparently significant trends. Most terror-related adverse events, casualties and deaths involved bombs and guns. Weapon-specific patterns and terror-related risk levels in Israel (ISR) have differed markedly from those of all other regions combined (AOR). ISR had a fatal fraction of casualties about half that of AOR, but has experienced relatively constant lifetime terror-related casualty risks on the order of 0.5%--a level 2 to 3 orders of magnitude more than those experienced in AOR, which have increased {approx}100-fold over the same period. Individual event fatality has increased steadily, the median increasing from 14 to 50%. Lorenz curves obtained indicate substantial dispersion among victim/event rates: about half of all victims were caused by the top 2% (10%) of harm-ranked events in OAR (ISR). Extreme values of victim/event rates were found to be well …

This issue of Science and Technology Review has the following articles: (1) Enhanced National Security through International Research Collaborations--Commentary by Stephen G. Cochran; (2) Building Networks of Trust through Collaborative Science--Livermore scientists are leading collaborative science and technology projects with colleagues from Central and South Asia and the Middle East; (3) Tracing the Steps in Nuclear Material Trafficking--The Laboratory.s nuclear science expertise is helping to thwart the illicit trafficking of nuclear material; (4) Looking at Earth in Action--Geophysicists at Livermore are using laboratory experiments to examine such issues as how best to store nuclear wastes and how to mitigate the effects of greenhouse gases; and (5) Gamma-Ray Bursts Shower the Universe with Metals--Computer models indicate that gamma-ray bursts from dying stars may be important sources of elements such as iron, zinc, titanium, and copper.

The October-December Quarter was dedicated to analyzing the first two years tree planting activities and evaluation of the results. This included the analyses of the species success at each of the sites and quantifying the data for future year determination of research levels. Additional detailed studies have been planned to further quantify total carbon storage accumulation on the research areas. At least 124 acres of new plantings will be established in 2005 to bring the total to 500 acres or more in the study area across the state of Kentucky. During the first 2 years of activities, 172,000 tree seedlings were planted on 257 acres in eastern Kentucky and 77,520 seedlings were planted on 119 acres in western Kentucky. The quantities of each species was discussed in the first Annual Report. A monitoring program was implemented to measure treatment effects on above and below ground C and nitrogen (N) pools and fluxes. A sampling strategy was devised that will allow for statistical comparisons of the various species within planting conditions and sites. Seedling heights and diameters are measured for initial status and re-measured on an annual basis. Leaves were harvested and leaf area measurements were performed. They were then dried …

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We demonstrate a BER of 10{sup -11} for 16 simultaneous users, using wavelength/time O-CDMA. We show the extent to which severe multi-access interference can be used to mask and/or degrade the signal from an intruder.

The need for better nuclear data has been stressed by various organizations throughout the world, and results of studies have been published which demonstrate that current data are inadequate for designing the projects under consideration [1] [2]. In particular, a Working Party of the OECD has been concerned with identifying these needs [3] and has produced a detailed High Priority Request List for Nuclear Data. The French Atomic Energy Commissariat (CEA) has also recognized the need for better data and launched an ambitious program aimed at measuring the integral absorption rate parameters at the CEA-Cadarache Research Center. A complete analytical program is associated with the experimental program and aims at understanding and resolving potential discrepancies between calculated and measured values. The final objective of the program is to reduce the uncertainties in predictive capabilities to a level acceptable to core designers and government regulators. Argonne National Laboratory has expertise in these areas. In the past, ANL teams have developed very accurate experimental techniques and strongly enhanced the development of several French experimental and analytical programs, and have contributed to the computational tools used at CEA-Cadarache. CEA recognized the expertise that ANL has in these areas and was interested in collaborating …

A research program was carried out at the University of Illinois in which develops a scientific approach to gas-liquid flows that explains their macroscopic behavior in terms of small scale interactions. For simplicity, fully-developed flows in horizontal and near-horizontal pipes. The difficulty in dealing with these flows is that the phases can assume a variety of configurations. The specific goal was to develop a scientific understanding of transitions from one flow regime to another and a quantitative understanding of how the phases distribute for a give regime. These basic understandings are used to predict macroscopic quantities of interest, such as frictional pressure drop, liquid hold-up, entrainment in annular flow and frequency of slugging in slug flows. A number of scientific issues are addressed. Examples are the rate of atomization of a liquid film, the rate of deposition of drops, the behavior of particles in a turbulent field, the generation and growth of interfacial waves. The use of drag-reducing polymers that change macroscopic behavior by changing small scale interactions was explored.