Controlled incorporation of mid-to-high Z transition metals in CVD diamond (open access)

Controlled incorporation of mid-to-high Z transition metals in CVD diamond

We report on a general method to fabricate transition metal related defects in diamond. Controlled incorporation of Mo and W in synthetic CVD diamond was achieved by adding volatile metal precursors to the diamond chemical vapor deposition (CVD) growth process. Effects of deposition temperature, grain structure and precursor exposure on the doping level were systematically studied, and doping levels of up to 0.25 at.% have been achieved. The metal atoms are uniformly distributed throughout the diamond grains without any indication of inclusion formation. These results are discussed in context of the kinetically controlled growth process of CVD diamond.
Date: January 8, 2010
Creator: Biener, M M; Biener, J; Kucheyev, S O; Wang, Y M; El-Dasher, B; Teslich, N E et al.
Object Type: Article
System: The UNT Digital Library
FIRST STATUS REPORT: TESTING OF AGED SOFTWOOD FIBERBOARD MATERIAL FOR THE 9975 SHIPPING PACKAGE (open access)

FIRST STATUS REPORT: TESTING OF AGED SOFTWOOD FIBERBOARD MATERIAL FOR THE 9975 SHIPPING PACKAGE

Samples have been prepared from a softwood fiberboard lower subassembly. Physical, mechanical and thermal properties have been measured following varying periods of conditioning in each of several environments. These tests have been conducted in the same manner as previous testing on cane fiberboard samples. Overall, similar aging trends are observed for softwood and cane fiberboard samples. Some of the observed differences result from the limited exposure periods of the softwood fiberboard samples, and the impact of seasonal humidity levels. Testing following additional conditioning will continue and should eliminate this bias. Post-conditioning data have been measured on a single softwood fiberboard assembly, and baseline data are also available from a limited number of vendor-provided samples. This provides minimal information on the possible sample-to-sample variation exhibited by softwood fiberboard. Data to date are generally consistent with the range seen in cane fiberboard, but much of the compression strength data tends toward the lower end of that range. Further understanding of the variability of softwood fiberboard properties will require testing of additional material. Cane fiberboard wall sheathing is specified for thermal insulation and impact resistance in 9975 shipping packages. Softwood fiberboard manufactured by Knight-Celotex was approved as an acceptable substitute for transportation in …
Date: January 8, 2010
Creator: Daugherty, W.
Object Type: Report
System: The UNT Digital Library
ELIST 8.7 Transportation Model (open access)

ELIST 8.7 Transportation Model

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Date: January 8, 2010
Creator: Braun, M. D.; Craig, B. A.; Van Groningen, C. N. & Sciences, Decision and Information
Object Type: Report
System: The UNT Digital Library
Using wesBench to Study the Rendering Performance of Graphics Processing Units (open access)

Using wesBench to Study the Rendering Performance of Graphics Processing Units

Graphics operations consist of two broad operations. The first, which we refer to here as vertex operations, consists of transformation, lighting, primitive assembly, and so forth. The second, which we refer to as pixel or fragment operations, consist of rasterization, texturing, scissoring, blending, and fill. Overall GPU rendering performance is a function of throughput of both these interdependent stages: if one stage is slower than the other, the faster stage will be forced to run more slowly and overall rendering performance will be adversely affected. This relationship is commutative: if the later stage has a greater workload than the earlier stage, the earlier stage will be forced to 'slow down.' For example, a large triangle that covers many screen pixels will incur a very small amount of work in the vertex stage while at the same time incurring a relatively large amount of work in the fragment stage. Rendering performance of a scene consisting of many large-area triangles will be limited by throughput of the fragment stage, which will have relatively more work than the vertex stage. There are two main objectives for this document. First, we introduce a new graphics benchmark, wesBench, which is useful for measuring performance of …
Date: January 8, 2010
Creator: Bethel, Edward W
Object Type: Report
System: The UNT Digital Library
MCNPX Simulation Study of STRAW Neutron Detectors (open access)

MCNPX Simulation Study of STRAW Neutron Detectors

A novel prototype fission meter is being designed at National Security Technologies, LLC, using a thin uniform coating (only 1 micron thick) of {sup 10}B as a neutron converter inside a large array of thin (4 mm diameter) copper tubes. The copper tubes are only 2 mils thick, and each holds the stretched anode wire under tension and high voltage. The tubes are filled with proportional counter gas (a mixture of 90%/10% of Ar/CO{sub 2}). The tubes operate in proportional counter mode and attract mobile charged particles ({alpha}'s) created in the nuclear interaction {sup 10}B(n, {sup 4}He){sup 7}Li. However, a single tube has about 1/7th the sensitivity of a {sup 3}He tube. Modeling is required to determine if enough such tubes could be placed in a neutron detection assembly of the current size to give comparable sensitivity to {sup 3}He. Detectors lined with {sup 10}B lie between {sup 3}He and {sup 10}BF{sub 3} proportional counters and fission chambers in terms of neutron detection efficiency and gamma ray insensitivity. The mean free path of thermal neutrons in {sup 10}B is about 18 {micro}m. It takes about 60 {micro}m of {sup 10}B layer to completely stop thermal neutrons, but the energetic {alpha}-particles …
Date: January 8, 2010
Creator: Sanjoy Mukhopadhyay, Richard Maurer, Stephen Mitchell
Object Type: Article
System: The UNT Digital Library
Novel Anionic Clay Adsorbents for Boiler-Blow-Down Waters Reclaim and Reuse (open access)

Novel Anionic Clay Adsorbents for Boiler-Blow-Down Waters Reclaim and Reuse

Arsenic (As) and Selenium (Se) are found in water in the form of oxyanions. Relatively high concentrations of As and Se have been reported both in power plant discharges, as well as, in fresh water supplies. The International Agency for Research on Cancer currently classifies As as a group 1 chemical, that is considered to be carcinogenic to humans. In Phase I of this project we studied the adsorption of As and Se by uncalcined and calcined layered double hydroxide (LDH). The focus of the present work is a systematic study of the adsorption of As and Se by conditioned LDH adsorbents. Conditioning the adsorbent significantly reduced the Mg and Al dissolution observed with uncalcined and calcined LDH. The adsorption rates and isotherms have been investigated in batch experiments using particles of four different particle size ranges. As(V) adsorption is shown to follow a Sips-type adsorption isotherm. The As(V) adsorption rate on conditioned LDH increases with decreasing adsorbent particle size; the adsorption capacity, on the other hand, is independent of the particle size. A homogeneous surface diffusion model (HSDM) and a bi-disperse pore model (BPM) - the latter viewing the LDH particles as assemblages of microparticles and taking into account …
Date: January 8, 2010
Creator: Sahimi, Muhammad & Tsotsis, Theodore
Object Type: Report
System: The UNT Digital Library
Gasdynamic Model of Turbulent Combustion in TNT Explosions (open access)

Gasdynamic Model of Turbulent Combustion in TNT Explosions

A model is proposed to simulate turbulent combustion in confined TNT explosions. It is based on: (i) the multi-component gasdynamic conservation laws, (ii) a fast-chemistry model for TNT-air combustion, (iii) a thermodynamic model for frozen reactants and equilibrium products, (iv) a high-order Godunov scheme providing a non-diffusive solution of the governing equations, and (v) an ILES approach whereby adaptive mesh refinement is used to capture the energy bearing scales of the turbulence on the grid. Three-dimensional numerical simulations of explosion fields from 1.5-g PETN/TNT charges were performed. Explosions in six different chambers were studied: three calorimeters (volumes of 6.6-l, 21.2-l and 40.5-l with L/D = 1), and three tunnels (L/D = 3.8, 4.65 and 12.5 with volumes of 6.3-l) - to investigate the influence of chamber volume and geometry on the combustion process. Predicted pressures histories were quite similar to measured pressure histories for all cases studied. Experimentally, mass fraction of products, Y{sub p}{sup exp}, reached a peak value of 88% at an excess air ratio of twice stoichiometric, and then decayed with increasing air dilution; mass fractions Y{sub p}{sup calc} computed from the numerical simulations followed similar trends. Based on this agreement, we conclude that the dominant effect that …
Date: January 8, 2010
Creator: Kuhl, A L; Bell, J B & Beckner, V E
Object Type: Article
System: The UNT Digital Library
Hanford Site Environmental Surveillance Master Sampling Schedule for Calendar Year 2010 (open access)

Hanford Site Environmental Surveillance Master Sampling Schedule for Calendar Year 2010

Environmental surveillance of the Hanford Site and surrounding areas is conducted by Pacific Northwest National Laboratory for the U.S. Department of Energy (DOE). Sampling is conducted to evaluate levels of radioactive and nonradioactive pollutants in the Hanford Site environs per regulatory requirements. This document contains the calendar year 2010 schedule for the routine collection of samples for the Surface Environmental Surveillance Project and the Drinking Water Monitoring Project. Each section includes sampling locations, sampling frequencies, sample types, and analyses to be performed. In some cases, samples are scheduled on a rotating basis. If a sample will not be collected in 2010, the anticipated year for collection is provided. Maps showing approximate sampling locations are included for media scheduled for collection in 2010.
Date: January 8, 2010
Creator: Bisping, Lynn E.
Object Type: Report
System: The UNT Digital Library