644 Matching Results

Search Results

On the Properties of Materials for Designing Filters at Optical Frequencies

Description: Frequency Selective Surfaces/Volumes (FSS/Vs), periodic structures with frequency selective properties, have widely been used for millimeter and microwave applications. Some applications include filters (band pass, band stop), reflectors, radoms etc. FSS/Vs typically consist of a single or multiple material layers. Multiple layers (with each layer having a different frequency selectivity) are used for broadband applications. In recent years there has been an interest in using these structures at optical wavelengths. One of the applications is in thermophotovoltaic filters used to convert thermal energy into electricity. The filter is designed to transmit those wavelengths that can be efficiently converted into electricity, and to reflect other spectra, which leads to energy conservation and an increase in overall system efficiency. These filters can be used in space missions to help decrease energy consumption and reduce spacecraft mass, cost, and fuel loading. Numerical simulations of such filters are very limited in the literature. Existing modeling approaches are based on the assumption of purely metallic (perfectly conducting) structures on substrates. however, in practice, metals have finite conductivity that can lead to power absorption in the metal. At optical frequencies the usual material properties and perfect electric conductor (PEC) assumption is not applicable. Moreover, the conventional methods, such as using resistive sheets or lossy dielectrics to simulate metallic losses, are not accurate. The goal is to provide a new approach for modeling metallic losses more accurately at the optical frequencies.
Date: May 5, 2003
Creator: Topsakal, E. & Volakis, J.L.
Partner: UNT Libraries Government Documents Department

Deployment of a Continuously Operated {mu}ChemLab

Description: A continuously operating prototype chemical weapons sensor system based on the {mu}ChemLab{trademark} technology was installed in the San Francisco International Airport in late June 2002. This prototype was assembled in a National Electric Manufacturers Association (NEMA) enclosure and controlled by a personal computer collocated with it. Data from the prototype was downloaded regularly and periodic calibration tests were performed through modem-operated control. The instrument was installed just downstream of the return air fans in the return air plenum of a high-use area of a boarding area. A CW Sentry, manufactured by Microsensor Systems, was installed alongside the {mu}ChemLab unit and results from its operation are reported elsewhere. Tests began on June 26, 2002 and concluded on October 16, 2002. This report will discuss the performance of the prototype during the continuous testing period. Over 70,000 test cycles were performed during this period. Data from this first field emplacement have indicated several areas where engineering improvements can be made for future field emplacement.
Date: May 1, 2003
Creator: ADKINS, DOUGLAS R.; KOTTENSTETTE, RICHARD; LEWIS, PATRICK R.; DULLECK JR., GEORGE R.; OBORNY, MICHAEL C.; GORDON, SUSANNA P. et al.
Partner: UNT Libraries Government Documents Department

Effect of Dielectric Photoemission on Surface Breakdown: An LDRD Report

Description: The research discussed in this report was conceived during our earlier attempts to simulate breakdown across a dielectric surface using a Monte Carlo approach. While cataloguing the various ways that a dielectric surface could affect the breakdown process, we found that one obvious effect--photoemission from the surface--had been ignored. Initially, we felt that inclusion of this effect could have a major impact on how an ionization front propagates across a surface because of the following argument chain: (1) The photon energy required to release electrons from a surface via photoemission is less than the photon energy required to ionize gas molecules directly. (2) The mean free path of a photon in gas is longer for low-energy photons than for high-energy photons. (3) Photoionization is a major effect in advancing the ionization front for breakdown in gas without a surface, therefore, we know that even high-energy photons can be released from the head of a streamer and propagate some distance through the gas. Our hypothesis, therefore, was that photons with energies near the threshold of photoemission could travel further in front of the streamer before being absorbed than higher-energy photons needed for photoionization, yet the lower-energy photons, with the help of the surface, could still create seed electrons for new avalanches. Thus, the streamer would advance more rapidly next to a surface than in gas alone. Additionally, the photoemission from the surface would add to the electrons in the avalanche and cause the avalanche to grow faster. After some study, however, we are forced to conclude that although photoemission does contribute to avalanche growth at fields near breakdown threshold, secondary electron emission causes electrons to stick to the surface and cancels out the growth due to photoemission. This conclusion assumes a discharge that occurs over a short period of time so ...
Date: May 1, 2003
Creator: JORGENSON, ROY E.; WARNE, LARRY K.; NEUBER, ANDREAS A.; KRILE, JOHN; DICKENS, JAMES & KROMPHOLZ, HERMANN
Partner: UNT Libraries Government Documents Department

Autonomic Healing of Epoxy Using Micro-Encapsulated Dicyclopentadiene

Description: The autonomic healing ability of an epoxy adhesive containing micro-encapsulated dicyclopentadiene (DCPD) was evaluated. The epoxy resin used was Epon 828 cured with either Versamid 140 or diethylenetriamine (DETA). Variables included total weight percent of microcapsules (MCs) and catalyst, as well as the catalyst to DCPD ratio. The degree of healing was determined by the fracture toughness before and after ''healing'' using double-cantilever beam analysis. It was found that the degree of self-healing was most directly related to the contact area (i.e. crack width) during healing. Temperature also played a significant role. Observed differences between the results of this study and those in literature are discussed.
Date: May 1, 2003
Creator: THOMA, STEVEN G.; GIUNTA, RACHEL K.; STAVIG, MARK E.; EMERSON, JOHN A. & MORALES, ALFREDO M.
Partner: UNT Libraries Government Documents Department

Creating science-driven computer architecture: A new patch to scientific leadership

Description: We believe that it is critical for the future of high end computing in the United States to bring into existence a new class of computational capability that is optimal for science. In recent years scientific computing has increasingly become dependent on hardware that is designed and optimized for commercial applications. Science in this country has greatly benefited from the improvements in computers that derive from advances in microprocessors following Moore's Law, and a strategy of relying on machines optimized primarily for business applications. However within the last several years, in part because of the challenge presented by the appearance of the Japanese Earth Simulator, the sense has been growing in the scientific community that a new strategy is needed. A more aggressive strategy than reliance only on market forces driven by business applications is necessary in order to achieve a better alignment between the needs of scientific computing and the platforms available. The United States should undertake a program that will result in scientific computing capability that durably returns the advantage to American science, because doing so is crucial to the country's future. Such a strategy must also be sustainable. New classes of computer designs will not only revolutionize the power of supercomputing for science, but will also affect scientific computing at all scales. What is called for is the opening of a new frontier of scientific capability that will ensure that American science is greatly enabled in its pursuit of research in critical areas such as nanoscience, climate prediction, combustion, modeling in the life sciences, and fusion energy, as well as in meeting essential needs for national security. In this white paper we propose a strategy for accomplishing this mission, pursuing different directions of hardware development and deployment, and establishing a highly capable networking and grid infrastructure connecting ...
Date: May 16, 2003
Creator: Simon, Horst D.; McCurdy, C. William; Kramer, T.C.; Stevens, Rick; McCoy,Mike; Seager, Mark et al.
Partner: UNT Libraries Government Documents Department

Sludge Batch 3 Melt Rate Assessment

Description: This report focuses on an assessment of melt rate for various frit/sludge combinations. The results provided should not be used as the sole decision-making tool, but they are an important input into the decision making process with respect to the SB3 frit.
Date: May 5, 2003
Creator: Lorier, T.H.
Partner: UNT Libraries Government Documents Department

Process-Based Quality Tools to Verify Cleaning and Surface Preparation

Description: A test method, the Tensile Brazil Nut Sandwich (TBNS) specimen, was developed to measure mixed-mode interfacial toughness of bonded materials. Interfacial toughness measured by this technique is compared to the interfacial toughness of thin film adhesive coatings using a nanoindentation technique. The interfacial toughness of solvent-cast and melt-spun adhesive thin films is compared and found to be similar. Finally, the Johnson-Kendall-Roberts (JKR) technique is used to evaluate the cleanliness of aluminum substrates.
Date: May 1, 2003
Creator: EMERSON, JOHN A.; GIUNTA, RACHEL K.; REEDY JR., EARL DAVID; ADAMS, DAVID P.; LEMKE, PAUL ALBERT & MOODY, NEVILLE R.
Partner: UNT Libraries Government Documents Department

Planned Disposition of Material in the Savannah River Site High Level Waste System

Description: Since the early 1950's Savannah River Site (SRS) has received over 100 million gallons of waste into the F and H Tank Farms, commonly known as the High Level Waste System (HLW) system. This waste was neutralized, insoluble sludge settled, and supernate was evaporated to form saltcake such that as of January 2003 only 37 million gallons of waste is stored in F and H tank farm. This waste contains approximately 417 million curies of radioactivity and includes approximately 3 million gallons of sludge and 34 million gallons of salt waste. Additionally, 5 million curies have already been dispositioned by the Defense Waste Processing Facility (DWPF) into glass canisters. The Accelerated Clean-up Plan (ACP)1 will result in the acceleration of risk reduction by emptying HLW tanks sooner, shipping HLW glass canisters and Transuranic Waste (TRU) to their geologic repositories sooner and decommissioning the F Canyon facilities and other excess facilities sooner. This document discusses the planned disposition of the material currently stored in the HLW System.
Date: May 5, 2003
Creator: Carter, J.
Partner: UNT Libraries Government Documents Department

DIE Deflection Modeling: Empirical Validation and Tech Transfer

Description: This report summarizes computer modeling work that was designed to help understand how the die casting die and machine contribute to parting plane separation during operation. Techniques developed in earlier research (8) were applied to complete a large computational experiment that systematically explored the relationship between the stiffness of the machine platens and key dimensional and structural variables (platen area covered, die thickness, platen thickness, thickness of insert and the location of the die with respect to the platen) describing the die/machine system. The results consistently show that there are many significant interactions among the variables and it is the interactions, more than the individual variables themselves, which determine the performance of the machine/die system. That said, the results consistently show that it is the stiffness of the machine platens that has the largest single impact on die separation.
Date: May 28, 2003
Creator: Miller, R. Allen
Partner: UNT Libraries Government Documents Department

TWR Bench-Scale Steam Reforming Demonstration

Description: The Idaho Nuclear Technology and Engineering Center (INTEC) was home to nuclear fuel reprocessing activities for decades at the Idaho National Engineering and Environmental Laboratory. As a result of the reprocessing activities, INTEC has accumulated approximately one million gallons of acidic, radioactive, sodium-bearing waste (SBW). The purpose of this demonstration was to investigate a reforming technology, offered by ThermoChem Waste Remediation, LLC, (TWR) for treatment of SBW into a ''road ready'' waste form that would meet the waste acceptance criteria for the Waste Isolation Pilot Plant (WIPP). TWR is the licensee of Manufacturing Technology Conservation International (MTCI) steam-reforming technology in the field of radioactive waste treatment. A non-radioactive simulated SBW was used based on the known composition of waste tank WM-180 at INTEC. Rhenium was included as a non-radioactive surrogate for technetium. Data was collected to determine the nature and characteristics of the product, the operability of the technology, the composition of the off-gases, and the fate of key radionuclides (cesium and technetium) and volatile mercury compounds. The product contained a low fraction of elemental carbon residues in the cyclone and filter vessel catches. Mercury was quantitatively stripped from the product but cesium, rhenium (Tc surrogate), and the heavy metals were retained. Nitrate residues were about 400 ppm in the product and NOx destruction exceeded 86%. The demonstration was successful.
Date: May 21, 2003
Creator: Marshall, D.W. & Soelberg, N.R.
Partner: UNT Libraries Government Documents Department

CH Packaging Operations for High Wattage Waste at LANL

Description: This procedure provides instructions for assembling the following contact-handled (CH) packaging payloads: - Drum payload assembly - Standard Waste Box (SWB) assembly - Ten-Drum Overpack (TDOP) In addition, this procedure also provides operating instructions for the TRUPACT-II CH waste packaging. This document also provides instructions for performing ICV and OCV preshipment leakage rate tests on the following packaging seals, using a nondestructive helium (He) leak test: - ICV upper main O-ring seal - ICV outer vent port plug O-ring seal - OCV upper main O-ring seal - OCV vent port plug O-ring seal.
Date: May 6, 2003
Creator: Westinghouse TRU Solutions LLC
Partner: UNT Libraries Government Documents Department

Final Report

Description: OAK B135 The formation of metastable crystalline phases in lithium disilicate glass has been a subject of controversy for decades. Here, one aspect of this problem relating to the stability of these non-equilibrium phases when glasses are heated for extended time periods in the nucleation regime is addressed. The results of a systematic experimental investigation on the persistence of metastable phases and the factors that may influence the appearance of such phases, e.g., water content, impurities, glass composition, and glass preparation procedure are presented. Growth rates of lithium disilicate crystals in lithium disilicate glass are measured as a function water concentration in the glass and of temperature in the deeply undercooled regime. The growth rate data obtained in this work are combined with data reported in the literature and used to assess the applicability of standard models of crystal growth for the description of experimental results over a very broad temperature range. The reduced growth rate versus undercooling graph is found to consist of three regimes. For undercoolings less than 140°C, the reduced growth rate curve is suggestive of either 2-D surface nucleation or screw dislocation growth. For undercoolings greater than 400°C, the reduced growth rate plot suggests the operative crystal growth mechanism is 2-D surface nucleation, but detailed calculations cast doubt upon this conclusion. In the intermediate undercooling range, there appears to be some sort of transitional behavior for which none of the standard models appear to be applicable. Further, it is observed that small differences in the viscosity data employed can produce enormous differences in the predicted growth rates at larger undercoolings. Results of the kinetic analyses conducted herein seem to indicate that the nature of the kinetic rate coefficient used in the standard growth models may be incorrect. Nucleation rates of sodium metasilicate crystals in a sodium ...
Date: May 23, 2003
Creator: Weinberg, Michael C.; Burgner, Lori L. & Simmons, Joseph H.
Partner: UNT Libraries Government Documents Department

A Theory for RF and Microwave Scalar Reflectometers

Description: A careful analysis of rf and microwave scalar reflectometers is conducted to (1) reveal the advantages of 4-port over 3-port reflectometers, (2) show the advantage--and remaining weaknesses--of a reflectometer initialized by the open/short method and (3) present expressions for the worst-case errors in scalar reflectometer measurements.
Date: May 1, 2003
Creator: MOYER, ROBERT D.
Partner: UNT Libraries Government Documents Department

Technical Basis for the Use of Alarming Personal Criticality Detectors to Augment Permanent Nuclear Incident Monitor (NIM) Systems in Areas Not Normally Occupied

Description: The technical basis for the use of alarming personal criticality detectors (APCDs) to augment permanent Nuclear Incident Monitor (NIM) Systems in areas not normally occupied is evaluated. All applicable DOE O 420.1A and ANSI/ANS-8.3-1997 criticality alarm system requirements and recommendations are evaluated for applicability to APCDs. Based on this evaluation, design criteria and administrative requirements are presented for APCDs. Siemens EPD/Mk-2 and EPD-N devices are shown to meet the design criteria. A definition of not normally occupied is also presented.
Date: May 26, 2003
Creator: Yates, K.R.
Partner: UNT Libraries Government Documents Department

Evaluating the Effects of Tri-Butyl Phosphate and Normal Paraffin Hydrocarbon in Simulated Low-Activity Waste Solution on Ion Exchange

Description: Ultrafiltration and ion exchange are among the pretreatment processes selected for the WTP at the Hanford Site. This study is the second part of a two-part study on Evaluating the Effects of Tri-Butyl Phosphate and Normal Paraffin Hydrocarbon in Simulated Low-Activity Waste Solution on Ultrafiltration and Ion Exchange.
Date: May 13, 2003
Creator: Adu-Wusu, K.
Partner: UNT Libraries Government Documents Department

Qualitative Reasoning for Additional Die Casting Applications

Description: If manufacturing incompatibility of a product can be evaluated at the early product design stage, the designers can modify their design to reduce the effect of potential manufacturing problems. This will result in fewer manufacturing problems, less redsign, less expensive tooling, lower cost, better quality, and shorter development time. For a given design, geometric reasoning can predict qualitatively the behaviors of a physical manufacturing process by representing and reasoning with incomplete knowledge of the physical phenomena. It integrates a design with manufacturing processes to help designers simultaneously consider design goals and manufacturing constraints during the early design stage. The geometric reasoning approach can encourage design engineers to qualitatively evaluate the compatibility of their design with manufacturing limitations and requirements.
Date: May 28, 2003
Creator: Miller, R. Allen; Cui, Dehua & Ma, Yuming
Partner: UNT Libraries Government Documents Department

WELDON SPRING SITE ENVIRONMENTAL REPORT FOR CALENDAR YEAR 2002

Description: This annual report presents a summary of data from the environmental monitoring program, to characterize trends and environmental conditions at the site, and to confirm compliance with environmental and health protection standards and requirements. This report also presents the status of remedial activities and the results of monitoring activities to assess their impacts on the public and environment.
Date: May 1, 2003
Creator: GROUP, WASHINGTON GROUP INTERNATIONAL AND JACOBS ENGINEERING
Partner: UNT Libraries Government Documents Department

Review of arsenic removal technologies for contaminated groundwaters.

Description: This review was compiled to summarize the technologies currently being investigated to remove arsenic from drinking waters, with a special focus on developing and third-world countries where the problem is exacerbated by flooding and depressed economic conditions. The reason for compiling this report is to provide background material and a description of competing technologies currently described in the literature for arsenic removal. Based on the sophistication and applicability of current technologies, Argonne National Laboratory may develop an improved method based on magnetic particle technology. Magnetic particle sorbents may afford improved reaction rates, facilitate particle-water separation, and offer reusability. Developing countries like Vietnam and Bangladesh cannot afford expensive, large-scale treatments to remove arsenic from drinking waters to acceptable limits (from 50 ppb to 10 ppb, depending on the country). Low-cost, effective technologies that can be readily available at the household or community level are needed to solve the present crisis. Appropriate technologies should meet certain criteria, including the following: The treatment must be applicable over a wide range of arsenic concentrations; It should be easy to use without running water or electricity; and The materials for the treatment should be cheap and readily available, and/or suitable for reuse. Our review of arsenic removal technologies and procedures indicates that iron filings, ferric salts, granular ferric hydroxide, alumina manganese oxide, Aqua-bind., and Kimberlite tailings are potentially low-cost sorbents that can remove arsenic after simple mixing in a relatively short time. However, all these technologies suffer from significant shortcomings. Ferric salts are cheap and very effective at removing arsenic but the reaction rates are slow. Fixed-bed columns make use of activated alumina and iron-coated sands but do not work well with groundwater having high concentrations of iron because iron precipitates in the presence of air, which could clog and foul the column. Synthetic sorbents ...
Date: May 2, 2003
Creator: Vu, K. B.; Kaminski, M. D. & Nunez, L.
Partner: UNT Libraries Government Documents Department

Dispersion and orbit distortions in the Tevatron: A comparison of measurements with a computer model

Description: In order to improve the Tevatron's performance an accurate model would be of great value. To create a realistic model of the current accelerator requires that we be able to integrate information from measurements made on the Tevatron into the computer model. The data, obtained from experiments on the Tevatron, can constrain the model and also constitute a test of the model. This note will describe comparisons of a computer model of the Tevatron with measurements. All the comparisons are for the injection lattice at 150 GeV.
Date: May 20, 2003
Creator: Gelfand, Norman M
Partner: UNT Libraries Government Documents Department

High-Harmonic Fast Wave Driven H-mode Plasmas on NSTX

Description: The launch of High-Harmonic Fast Waves (HHFW) routinely provides auxiliary power to NSTX plasmas, where it is used to heat electrons and pursue drive current. H-mode transitions have been observed in deuterium discharges, where only HHFW and ohmic heating, and no neutral beam injection (NBI), were applied to the plasma. The usual H-mode signatures are observed. A drop of the Da light marks the start of a stored energy increase, which can double the energy content. These H-mode plasmas also have the expected kinetic profile signatures with steep edge density and electron temperature pedestal. Similar to its NBI driven counterpart--also observed on NSTX-- the HHFW H mode have density profiles that features ''ears'' in the peripheral region. These plasmas are likely candidates for long pulse operation because of the combination of bootstrap current, associated with H-mode kinetic profiles, and active current drive, which can be generated with HHFW power.
Date: May 2003
Creator: LeBlanc, B. P.; Bell, R. E.; Bernabei, S. I.; Indireshkumar, K.; Kaye, S. M.; Maingi, R. et al.
Partner: UNT Libraries Government Documents Department

Treatment of Perchlorate-Contaminated Groundwater Using Highly-Selective, Regenerable Anion-Exchange Resins at Edwards Air Force Base

Description: Selective ion exchange is one of the most effective treatment technologies for removing low levels of perchlorate (ClO{sub 4}{sup -}) from contaminated water because of its high efficiency without adverse impacts on the water quality caused by adding or removing any chemicals or nutrients. This report summarizes both the laboratory and a field pilot-scale studies to determine the ability and efficiency of the bifunctional synthetic resins to remove ClO{sub 4}{sup -} from the contaminated groundwater at the Edwards Air Force Base in California. Regeneration of the resins after groundwater treatment was also evaluated using the FeCl{sub 3}-HCl regeneration technique recently developed at Oak Ridge National Laboratory. On the basis of this study, the bifunctional resin, D-3696 was found to be highly selective toward ClO{sub 4}{sup -} and performed much better than one of the best commercial nitrate-selective resins (Purolite A-520E) and more than an order of magnitude better than the Purolite A-500 resin (with a relatively low selectivity). At an influent concentration of {approx} 450 {micro}g/L ClO{sub 4}{sup -} in groundwater, the bifunctional resin bed treated {approx} 40,000 empty bed volumes of groundwater before a significant breakthrough of ClO{sub 4}{sup -} occurred. The presence of relatively high concentrations of chloride and sulfate in site groundwater did not appear to affect the ability of the bifunctional resin to remove ClO{sub 4}{sup -}. However, the presence of high iron or iron oxyhydroxides and/or biomass in groundwater caused a significant fouling of the resin beds and greatly influenced the effectiveness in regenerating the resins sorbed with ClO{sub 4}{sup -}. Under such circumstances, a prefilter ({approx} 0.5-1 {micro}m) was found to be necessary to remove these particulates and to reduce the risk of fouling of the resin beds. Without significant fouling, the resin bed could be effectively regenerated by the FeCl{sub 3} displacement technique. ...
Date: May 30, 2003
Creator: Gu, B.
Partner: UNT Libraries Government Documents Department

ACME: Algorithms for Contact in a Multiphysics Environment API Version 1.3

Description: An effort is underway at Sandia National Laboratories to develop a library of algorithms to search for potential interactions between surfaces represented by analytic and discretized topological entities. This effort is also developing algorithms to determine forces due to these interactions for transient dynamics applications. This document describes the Application Programming Interface (API) for the ACME (Algorithms for Contact in a Multiphysics Environment) library.
Date: May 1, 2003
Creator: BROWN, KEVIN H.; VOTH, THOMAS E.; GLASS, MICHEAL W.; GULLERUD, ARNE S.; HEINSTEIN, MARTIN W. & JONES, REESE E.
Partner: UNT Libraries Government Documents Department