The condition for extracting a maximum negative ion current density is found when the product of the radius of the negative ion conversion electrode, the cross-section for negative and positive ion recombination, and the density of positive ions in the ion source equals one. The optimum output is obtained at the highest positive ion density and the smallest electrode radius.

Discussion is given on the welding fabrication of tungsten, molybdenum, niobium, and tantalum. Properties which make the four refractory metals important are tabulatcd along with titanium which is given for comparison. Extensive evaluation was conducted using the gas, tungsten arc welding process employing both manual and machine welding. Design data were obtained exclusively from machine welded sheet materials. Flash welding, resistance spot welding and brazing, electron beam welding, and high frequency resistance welding processes were also applied to molybdenum alloys. The oxidation of molybdenum, tantalum, and niobium in flowing air at 2000 deg F is also given. (P.C.H.)

Highlights of technical progress during January 1978 are presented for sixteen separate program activities which comprise the ORNL research program for the Office of Nuclear Regulatory Research's Division of Reactor Safety Research.

The macropore structure of chars is a major factor in determining their reactivity during the gasification stage. The major objectives of this contract were to (a) quantify by direct measurements the effect of pyrolysis conditions of the macropore structure, and (b) establish how the macropores affected the reactivity pattern, the ignition behavior and the fragmentation of the char particles during gasification in the regime of strong diffusional limitations. Results from this project provide much needed information on the factors that affect the quality of the solid products (chars) of coal utilization processes (for example, mild gasification processes). The reactivity data will also provide essential parameters for the optimal design of coal gasification processes. (VC)

The use of magnetic switches to generate high power pulses has opened up a whole new spectrum of possibilities. Here we describe an investigation into the maximum repetition rates possible with these devices.

The Theoretical EOS Group develops theoretical techniques for describing material properties under extreme conditions and constructs equation-of-state (EOS) tables for specific applications. Work this quarter concentrated on a Li equation of state, equation of state for equilibrium plasma, improved ion corrections to the Thomas--Fermi--Kirzhnitz theory, and theoretical estimates of high-pressure melting in metals. The Experimental Physics Group investigates properties of materials at extreme conditions of pressure and temperature, and develops new experimental techniques. Effort this quarter concerned the following: parabolic projectile distortion in the two-state light-gas gun, construction of a ballistic range for long-rod penetrators, thermodynamics and sound velocities in liquid metals, isobaric expansion measurements in Pt, and calculation of the velocity--mass profile of a jet produced by a shaped charge. Code development was concentrated on the PELE code, a multimaterial, multiphase, explicit finite-difference Eulerian code for pool suppression dynamics of a hypothetical loss-of-coolant accident in a nuclear reactor. Activities of the Fluid Dynamics Group were directed toward development of a code to compute the equations of state and transport properties of liquid metals (e.g. Li) and partially ionized dense plasmas, jet stability in the Li reactor system, and the study and problem application of fluid dynamic turbulence theory. 19 …

Literature on ways for saving energy by retrofitting single family homes was surveyed, and each energy conservation option is evaluated for economic desirability. The options considered include the prevention of heat losses by reducing air infiltration and by increasing thermal insulation, optimizing furnace operation, lowering space and water heater temperatures, flue gas heat recovery, and controlling hot water flow. The cost and payback period is given for each option. (LCL)

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This paper extends previous results on nonlinear Schwarz preconditioning ([4]) to unstructured finite element elliptic problems exploiting now nonlocal (but small) subspaces. The non-local finite element subspaces are associated with subdomains obtained from a non-overlapping element partitioning of the original set of elements and are coarse outside the prescribed element subdomain. The coarsening is based on a modification of the agglomeration based AMGe method proposed in [8]. Then, the algebraic construction from [9] of the corresponding non-linear finite element subproblems is applied to generate the subspace based nonlinear preconditioner. The overall nonlinearly preconditioned problem is solved by an inexact Newton method. Numerical illustration is also provided.

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Saline aquifers of high permeability bounded by overlying/underlying seals may be surrounded laterally by low-permeability zones, possibly caused by natural heterogeneity and/or faulting. Carbon dioxide (CO{sub 2}) injection into and storage in such 'closed' systems with impervious seals, or 'semi-closed' systems with nonideal (low-permeability) seals, is different from that in 'open' systems, from which the displaced brine can easily escape laterally. In closed or semi-closed systems, the pressure buildup caused by continuous industrial-scale CO{sub 2} injection may have a limiting effect on CO{sub 2} storage capacity, because geomechanical damage caused by overpressure needs to be avoided. In this research, a simple analytical method was developed for the quick assessment of the CO{sub 2} storage capacity in such closed and semi-closed systems. This quick-assessment method is based on the fact that native brine (of an equivalent volume) displaced by the cumulative injected CO{sub 2} occupies additional pore volume within the storage formation and the seals, provided by pore and brine compressibility in response to pressure buildup. With nonideal seals, brine may also leak through the seals into overlying/underlying formations. The quick-assessment method calculates these brine displacement contributions in response to an estimated average pressure buildup in the storage reservoir. The CO{sub …

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. Adjusted data analyzed involve a total of 19,828 events, 7,401 ''adverse'' events (each causing {ge}1 victim), and 86,568 ''casualties'' (injuries) of which 25,408 were fatal. Most terror-related adverse events, casualties and deaths involved bombs and guns. Weapon-specific patterns and terror-related risk levels in Israel (IS) have differed markedly from those of all other regions combined (OR). IS had a fatal fraction of casualties about half that of OR, 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 OR that 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 2.5% (or 10%) of harm-ranked events in OR (or IS). Extreme values of victim/event rates were approximated fairly well by generalized Pareto models (typically used to fit to data on forest …

The objective of this paper is to set down the rationale for a separate Science & Technology (S&T) Program within every national deep-geological-isolation program. The fundamental rationale for such a Program is to provide a dedicated focus for longer-term science and technology activities that ultimately will benefit the whole repository mission. Such a Program, separately funded and with a dedicated staff (separate from the ''mainline'' activities to develop the repository, the surface facilities, and the transportation system), can devote itself exclusively to the development and management of a long-term science and technology program. Broad experience in governments worldwide has demonstrated that line offices are unlikely to be able to develop and sustain both the appropriate longer-term philosophy and the specialized skills associated with managing longer-term science and technology projects. Accomplishing both of these requires a separate dedicated program office with its own staff.

Yucca Flat is a topographic and structural basin in the northeastern part of the Nevada Test Site (NTS) in Nye County, Nevada. Between the years 1951 and 1992, 659 underground nuclear tests took place in Yucca Flat; most were conducted in large, vertical excavations that penetrated alluvium and the underlying Cenozoic volcanic rocks. Radioactive and other potential chemical contaminants at the NTS are the subject of a long-term program of investigation and remediation by the U.S. Department of Energy (DOE), National Nuclear Security Administration, Nevada Site Office, under its Environmental Restoration Program. As part of the program, the DOE seeks to assess the extent of contamination and to evaluate the potential risks to humans and the environment from byproducts of weapons testing. To accomplish this objective, the DOE Environmental Restoration Program is constructing and calibrating a ground-water flow model to predict hydrologic flow in Yucca Flat as part of an effort to quantify the subsurface hydrology of the Nevada Test Site. A necessary part of calibrating and evaluating a model of the flow system is an understanding of the location and characteristics of faults that may influence ground-water flow. In addition, knowledge of fault-zone architecture and physical properties is a …

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In order to shed light on the intriguing, and not yet fully understood fcc-isostructural {gamma} {yields} {alpha} transition in cerium, we have begun an experimental program aimed at the determination of the pressure evolution of the transverse acoustic (TA) and longitudinal acoustic (LA) phonon dispersions up to and above the transition. {gamma}-Ce Crystals of 60-80 mm diameter and 20 mm thickness were prepared from a large ingot, obtained from Ames Lab, using laser cutting, micro-mechanical and chemical polishing techniques. Three samples with a surface normal approximately oriented along the [110] direction were loaded into diamond anvil cells (DAC), using neon as a pressure transmitting medium. The crystalline quality was checked by rocking curve scans and typical values obtained ranged between one and two degrees. Only a slight degradation in the sample quality was observed when the pressure was increased to reach the {alpha}-phase, and data could be therefore recorded in this phase as well. The spectrometer was operated at 17794 eV in Kirkpatrick-Baez focusing geometry, providing an energy resolution of 3 meV and a focal spot size at the sample position of 30 x 60 mm{sup 2} (horizontal x vertical, FWHM). Eight to ten IXS spectra were typically recorded per …

Weak scale supersymmetry is often said to be fine-tuned, especially if the matter content is minimal. This is not true if there is a large A term for the top squarks. We present a systematic study on fine-tuning in minimal supersymmetric theories and identify low energy spectra that do not lead to severe fine-tuning. Characteristic features of these spectra are: a large A term for the top squarks, small top squark masses, moderately large tan {beta}, and a small {mu} parameter. There are classes of theories leading to these features, which are discussed. In one class, which allows a complete elimination of fine-tuning, the Higgsinos are the lightest among all the superpartners of the standard model particles, leading to three nearly degenerate neutralino/chargino states. This gives interesting signals at the LHC--the dilepton invariant mass distribution has a very small endpoint and shows a particular shape determined by the Higgsino nature of the two lightest neutralinos. We demonstrate that these signals are indeed useful in realistic analyses by performing Monte Carlo simulations, including detector simulations and background estimations. We also present a method that allows the determination of all the relevant superparticle masses without using input from particular models, despite the …

Forensics investigations of bio-crime or bio-terrorism incidents require careful analysis of collected evidentiary material. Although the biological markers in the evidentiary material are important (e.g. genomic signatures, protein markers), the elemental make-up of the organisms themselves and the surrounding non-biological material is extremely useful for attributing a specific process and, perhaps, specific persons to the production of the biological agent. This talk will describe the coordinated use of microanalytical techniques such as SEM-EDX, STEM-EDX, and NanoSIMS for generating compositional signatures for bio-forensics investigations. These analytical techniques span length scales from the 50 {micro}m range to the 5nm range. The range of analytical sensitivities spans from {approx}.5wt% for EDX down to parts per billion for SIMS techniques. In addition, we will discuss the use of spectrum imaging techniques for rapidly extracting the key elemental signatures from large scale data sets. Spectrum imaging techniques combined with multivariate statistical analysis allow for the collection and interrogation or enormous quantities of data without pre-biasing the answer.[1] Spectrum imaging has been used successfully in EDX microanalysis[1] (both in the SEM and TEM) and TOF-SIMS[2]. In this study, a set of test biological agents, ?-irradiated Bacillus thuringiensis (Bt), were examined using the aforementioned microanalytical techniques. The …

The proposed retrofit coil is made of superconducting Cable-in-Conduit Conductor (CICC). The coils are designed to produce a nominal vertical field of 4.5 tesla within the MHD channel based on a nominal current density of 13.05 MA/m{sup 2}. The coils are supported within a case, or so-called constant tension strap. When the magnet is energized, the electromagnetic J {times} B body forces push the winding pack laterally outward and vertically towards the machine's midplane, thus putting the strap in tension. The end turns add axial tension to the conductor (a condition which is not simulated by this 2-D model of the midlength cross section). A sketch of the magnet system and structure is shown in Fig. 1.0-1. The purpose of this report is to describe the progress made in the design and analysis of the DC CICC retrofit magnet, and to outline the proposed next step.

This project seeks to develop a technique, based on coal surface properties, for highly dispersing catalysts in coal for gasification and to investigate the potential of using potassium carbonate and calcium acetate mixtures as catalysts for coal gasification. The lower cost and higher catalytic activity of the latter compound will produce economic benefits by reducing the amount of K{sub 2}CO{sub 3} required for high coal char reactivities. As was shown in previous reports, coal loading with potassium or calcium at different pHs produced CO{sub 2} gasification activities which increased in the order pH 6 > pH 10 {much gt} pH 1. The current report shows that a similar trend was obtained when calcium and potassium were simultaneously loaded and char reaction times were less than about 75 min. Beyond this time, the coal impregnated with catalyst at pH 1 became more reactive, reaching 100% conversion after 1.5h. X-ray diffraction analysis suggest that the catalysts are well dispersed around pH 1 and 6 whereas reduced dispersion as obtained at pH 10. The reactivities are independent of the surface areas of the coals.

Classifier systems are quite complicated, in terms of both their components and behavior. This complexity is understandable given the wide spectrum of activity they are intended to model. Unfortunately, the complexity of these systems also makes it difficult to understand them analytically. Previous analysis has focused on specific components of the classifier system, for example, the genetic algorithm or the bucket brigade. The lack of a unified theory has led users of these systems to rely on ad hoc methods for choosing representations and parameter settings. Recent results (Riolo, 1988) indicate that classifier systems can be very sensitive to particular encodings and parameter choices. In this paper, we propose a methodology for studying the interactions among various components of the classifier system architecture.

Test shells of Inconel 625, Inconel 718, 21-6-9 stainless steel, and Hastelloy, C-276 were plasma and/or chemically cleaned before sealing with a multi-component glass-ceramic-to-metal seal was evaluated using a hydrostatic burst test. The results show that plasma cleaning can be used to increase the hydrostatic burst strength and hermeticity of a glass ceramic-to-metal seal.

This report summarizes efforts made by the Seismological Laboratory toward the detection and delineation of shallow crustal zones in the western Great Basin, and toward the development of methods to accomplish such detection. The work centers around the recently-active volcanic center near Long Valley, California. The work effort is broken down into three tasks: (1) network operations, (2) data analysis and interpretation, and (3) the study of shallow crustal amomalies (magma bodies). Section (1) describes the efforts made to record thousand of earthquakes near the Long Valley caldera, and focusses on the results obtained for the November 1984 round Valley earthquake. Section (2) describes the major effort of this contract, which was to quantify the large volume of seismic data being recorded as it pertains to the goals of this contract. Efforts described herein include (1) analysis of earthquake focal mechanisms, and (2) the classification, categorization, and interpretation of unusual seismic phases in terms of reflections and refractions from shallow-crustal anomalous zones. Section (3) summarizes the status of our research to date on the locations of magma bodies, with particular emphasis on a location corresponding to the map location of the south end of Hilton Creek fault. Five lines of …