222 Matching Results

Search Results

Advanced search parameters have been applied.

Final Report DE-FG02-00ER54583: "Physics of Atmospheric Pressure Glow Discharges" and "Nanoparticle Nucleation and Dynamics in Low-Pressure Plasmas"

Description: This project was funded over two periods of three years each, with an additional year of no-cost extension. Research in the first funding period focused on the physics of uniform atmospheric pressure glow discharges, the second funding period was devoted to the study of the dynamics of nanometer-sized particles in plasmas.
Date: June 1, 2009
Creator: Kortshagen, Uwe; Heberlein, Joachim & Girshick, Steven L.
Partner: UNT Libraries Government Documents Department

Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

Description: The objective of this work is to demonstrate a practical, atmospheric pressure plasma tool for the surface decontamination of heavy metal waste. Decontamination of radioactive materials that have accumulated on the surfaces of equipment and structures is a challenging and costly undertaking for the US Department of Energy. Our technology shows great promise for mitigating the cost of this clean up effort.
Date: June 1, 2002
Creator: Hicks, Robert F. & Herrmann, Hans W.
Partner: UNT Libraries Government Documents Department

Boiling Visualization and Critical Heat Flux Phenomena In Narrow Rectangular Gap

Description: An experimental study was performed to investifate the pool boling critical hear flux (CHF) on one-dimensional inclined rectangular channels with narrow gaps by changing the orientation of a copper test heater assembly. In a pool of saturated water at atmospheric pressure, the test parameters include the gap sizes of 1,2,5, and 10 mm, andthe surface orientation angles from the downward facing position (180 degrees) to the vertical position (90 degress) respectively.
Date: December 1, 2004
Creator: Kim, J. J.; Kim, Y. H.; Kim, S. J.; Noh, S. W.; Suh, K. Y.; Rempe, J. et al.
Partner: UNT Libraries Government Documents Department

Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

Description: Project was to develop a low-cost, environmentally benign technology for the decontamination and decommissioning of transuranic waste. With the invention of the atmospheric-pressure plasma jet the goal was achieved. This device selectively etches heavy metals from surfaces, rendering objects radiation free and suitable for decommissioning. The volatile reaction products are captured on filters, which yields a tremendous reduction in the volume of the waste. Studies on tantalum, a surrogate material for plutonium, have shown that etch rate of 6.0 microns per minute can be achieved under mild conditions. Over the past three years, we have made numerous improvements in the design of the plasma jet. It may now be operated for hundreds of hours and not undergo any degradation in performance. Furthermore, small compact units have been developed, which are easily deployed in the field.
Date: January 9, 2001
Creator: Hicks, Robert F. & Selwyn, Gary S.
Partner: UNT Libraries Government Documents Department

Vacuum Technology

Description: The environmental condition called vacuum is created any time the pressure of a gas is reduced compared to atmospheric pressure. On earth we typically create a vacuum by connecting a pump capable of moving gas to a relatively leak free vessel. Through operation of the gas pump the number of gas molecules per unit volume is decreased within the vessel. As soon as one creates a vacuum natural forces (in this case entropy) work to restore equilibrium pressure; the practical effect of this is that gas molecules attempt to enter the evacuated space by any means possible. It is useful to think of vacuum in terms of a gas at a pressure below atmospheric pressure. In even the best vacuum vessels ever created there are approximately 3,500,000 molecules of gas per cubic meter of volume remaining inside the vessel. The lowest pressure environment known is in interstellar space where there are approximately four molecules of gas per cubic meter. Researchers are currently developing vacuum technology components (pumps, gauges, valves, etc.) using micro electro mechanical systems (MEMS) technology. Miniature vacuum components and systems will open the possibility for significant savings in energy cost and will open the doors to advances in electronics, manufacturing and semiconductor fabrication. In conclusion, an understanding of the basic principles of vacuum technology as presented in this summary is essential for the successful execution of all projects that involve vacuum technology. Using the principles described above, a practitioner of vacuum technology can design a vacuum system that will achieve the project requirements.
Date: October 15, 2004
Creator: Biltoft, P. J.
Partner: UNT Libraries Government Documents Department

The Direct Pouring of Liquid Metal from the Reduction Bomb

Description: By the time regular crude biscuit production was interrupted at Ames on November 9, 1944, we had made well over 100 special experimental castings by pouring the liquid metal directly from the bomb. The workmen on the regular crude production line were alternating these special castings with the regular runs without the assistance of the research group. The process had reached a state of development 'wherein the castings were made by pouring batches of about 135 pounds of liquid metal directly from the bomb into a water-cooled steel mold in the presence of air at atmospheric pressure. The pouring operation was effected through a mechanically operated valve in the bottom of the bomb. The workability of such a process has been well established, and the quality of the metal has been proved through candling and chemical tests. The first sixty billets produced by this method have been extruded successfully. A number of changes, designed to improve the quality and yield of the product and to simplify the process, have been made since producing the metal for these tests. The first set-up to test the possibility of pouring the metal directly from the bomb was made on a small scale here last spring. The fortunate success of that first trial, although made with a valve mechanism that failed repeatedly to pour in the next few runs, pointed definitely to the feasibility of such a process. The development of a practicable set-up and procedure was then undertaken, and the plan of experimentation was to make a run, closely observe the operation, and inspect the complete set-up afterwards. Observations in each case led to changes that were made for the following trials. This method of development was slow at first, but, after an acquantance was gained with the main factors involved, the developments ...
Date: March 9, 1945
Creator: Wilhelm, H. A.
Partner: UNT Libraries Government Documents Department

Expansion analyses of strategic petroleum reserve in Bayou Choctaw : revised locations.

Description: This report summarizes a series of three-dimensional simulations for the Bayou Choctaw Strategic Petroleum Reserve. The U.S. Department of Energy plans to leach two new caverns and convert one of the existing caverns within the Bayou Choctaw salt dome to expand its petroleum reserve storage capacity. An existing finite element mesh from previous analyses is modified by changing the locations of two caverns. The structural integrity of the three expansion caverns and the interaction between all the caverns in the dome are investigated. The impacts of the expansion on underground creep closure, surface subsidence, infrastructure, and well integrity are quantified. Two scenarios were used for the duration and timing of workover conditions where wellhead pressures are temporarily reduced to atmospheric pressure. The three expansion caverns are predicted to be structurally stable against tensile failure for both scenarios. Dilatant failure is not expected within the vicinity of the expansion caverns. Damage to surface structures is not predicted and there is not a marked increase in surface strains due to the presence of the three expansion caverns. The wells into the caverns should not undergo yield. The results show that from a structural viewpoint, the locations of the two newly proposed expansion caverns are acceptable, and all three expansion caverns can be safely constructed and operated.
Date: November 1, 2010
Creator: Ehgartner, Brian L. & Park, Byoung Yoon
Partner: UNT Libraries Government Documents Department

Apparatus and Method for Increasing the Diameter of Metal Alloy Wires Within a Molten Metal Pool

Description: In a dip forming process the core material to be coated is introduced directly into a source block of coating material eliminating the need for a bushing entrance component. The process containment vessel or crucible is heated so that only a portion of the coating material becomes molten, leaving a solid portion of material as the entrance port of, and seal around, the core material. The crucible can contain molten and solid metals and is especially useful when coating core material with reactive metals. The source block of coating material has been machined to include a close tolerance hole of a size and shape to closely fit the core material. The core material moves first through the solid portion of the source block of coating material where the close tolerance hole has been machined, then through a solid/molten interface, and finally through the molten phase where the diameter of the core material is increased. The crucible may or may not require water-cooling depending upon the type of material used in crucible construction. The system may operate under vacuum, partial vacuum, atmospheric pressure, or positive pressure depending upon the type of source material being used.
Date: January 29, 2002
Creator: Hartman, Alan D.; Argetsinger, Edward R.; Hansen, Jeffrey S.; Paige, Jack I.; King, Paul E. & Turner, Paul C.
Partner: UNT Libraries Government Documents Department

Achieve Continuous Injection of Solid Fuels into Advanced Combustion System Pressures

Description: The overall objective of this project is the development of a mechanical rotary-disk feeder, known as the Stamet Posimetric High Pressure Solids Feeder System, to demonstrate feeding of dry granular coal continuously and controllably into pressurized environments of up to 70 kg/cm2 (1,000 psi). This is the Phase III of the ongoing program. Earlier Phases 1 and II successfully demonstrated feeding into pressures up to 35 kg/cm{sup 2} (500 psi). The final report for those phases was submitted in April 2005. Based on the previous work done in Phases I & II using Powder River Basin coal provided by the PSDF facility in Wilsonville, AL, a Phase III feeder system was designed and built to accomplish the target of feeding the coal into a pressure of 70 kg/cm2 (1,000 psi) and to be capable of feed rates of up to 550 kilograms (1,200lbs) per hour. The drive motor system from Phase II was retained for use on Phase III since projected performance calculations indicated it should be capable of driving the Phase III pump to the target levels. The pump & motor system was installed in a custom built test rig comprising an inlet vessel containing an active live-wall hopper mounted on weigh cells in a support frame, transition into the pump inlet, transition from pump outlet and a receiver vessel containing a receiver drum supported on weigh cells. All pressure containment on the rig was rated to105 kg/cm{sup 2} (1,500psi) to accommodate the final pressure requirement of a proposed Phase IV of the program. A screw conveyor and batch hopper were added to transfer coal at atmospheric pressure from the shop floor up into the test rig to enable continuous feeding up to the capacity of the receiving vessel. Control & monitoring systems were up-rated from the Phase II ...
Date: March 31, 2007
Creator: Aldred, Derek L. & Saunders, Timothy
Partner: UNT Libraries Government Documents Department

Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

Description: The purpose of this project is to develop a low-cost, environmentally benign technology for the decontamination and decommissioning of transuranic waste. In order to accomplish this goal, an understanding of the scientific principles of operating the atmospheric-pressure plasma jet must be achieved. This knowledge can then be applied to the design of a working tool for D & D applications within DOE.
Date: June 1, 2000
Creator: Hicks, Robert F. & Selwyn, Gary S.
Partner: UNT Libraries Government Documents Department

Experience with atmospheric fluidized bed gasification of switchgrass

Description: Switchgrass was gasified in a bubbling fluidized bed reactor rated at 800 kW (2.75 MMBtu/hr) thermal input and operating at atmospheric pressure. A combustible gas with higher heating value varying between 4.2--5.9 MJ/Nm{sup 3} (114--160 Btu/scf) was produced. Carbon conversion was approximately 85%. Difficulties in feeding high moisture switchgrass inhibited smooth reactor operation. Several feed systems for switchgrass were tried with varying degrees of success. The results of gasification trials using switchgrass as fuel are described.
Date: December 31, 1998
Creator: Smeenk, J. & Brown, R.C.
Partner: UNT Libraries Government Documents Department

Six- and three-hourly meteorological observations from 223 USSR stations

Description: This document describes a database containing 6- and 3-hourly meteorological observations from a 223-station network of the former Soviet Union. These data have been made available through cooperation between the two principal climate data centers of the United States and Russia: the National Climatic Data Center (NCDC), in Asheville, North Carolina, and the All-Russian Research Institute of Hydrometeorological Information -- World Data Centre (RIHMI-WDC) in Obninsk. Station records consist of 6- and 3-hourly observations of some 24 meteorological variables including temperature, weather type, precipitation amount, cloud amount and type, sea level pressure, relative humidity, and wind direction and speed. The 6-hourly observations extend from 1936 to 1965; the 3-hourly observations extend from 1966 through the mid-1980s (1983, 1984, 1985, or 1986; depending on the station). These data have undergone extensive quality assurance checks by RIHMI-WDC, NCDC, and the Carbon Dioxide Information Analysis Center (CDIAC). The database represents a wealth of meteorological information for a large and climatologically important portion of the earth`s land area, and should prove extremely useful for a wide variety of regional climate change studies. These data are available free of charge as a numeric data package (NDP) from CDIAC. The NDP consists of this document and 40 data files that are available via the Internet or on 8mm tape. The total size of the database is {approximately}2.6 gigabytes.
Date: April 1, 1995
Creator: Razuvaev, V.N.; Apasova, E.B.; Martuganov, R.A. & Kaiser, D.P.
Partner: UNT Libraries Government Documents Department

The CO2 Gas Cherenkov Detectors for the Jefferson Lab Hall A Spectrometers

Description: Two threshold gas Cherenkov counters have been constructed for the electron and hadron High Resolution Spectrometers (HRS) of the Jefferson Lab Experimental Hall A. These counters are intended to separate electrons/positrons from other particles up to 4 GeV/c. The counters are operated at atmospheric pressure with CO2. Each counter is equipped with ten mirrors. Lightweight, thin, spherical mirrors (5.5 + 10{sup {minus}3} radiation lengths) have been employed resulting in a total thickness of 1.4 + 10{sup {minus}2} radiation lengths crossed by the particles. A prototype of the counter has been tested at CERN with a mixed beam of positrons, pions, and protons from 1 to 4 GeV/c. Its detection efficiency for positrons and the rejection ratios for pions and protons have been measured as a function of the pulse height response (or equivalently the number of photoelectrons). An improvement of 34% in the number of photoelectrons has been obtained by using a wavelength shifter coated on the photocathode glass window. With such an improvement in 1 m long radiator, an inefficiency for positrons less than 10{sup {minus}3} and rejection ratios pi/e at the level of few 10{sup {minus}3} and p/e smaller than 10{sup {minus}3} have been obtained for pulse heights above 2 photoelectrons. Contaminations of particles below the Cherenkov threshold is fully understood considering delta-rays production.
Date: June 1, 1998
Creator: Iodice, M.; Cisbani, E.; Colilli, S.; Crateri, R.; Frullani, S.; Garibaldi, F. et al.
Partner: UNT Libraries Government Documents Department

Development of an atmospheric model based on a generalized vertical coordinate. Final report, September 12, 1991--August 31, 1997

Description: There are great conceptual advantages in the use of an isentropic vertical coordinate in atmospheric models. Design of such a model, however, requires to overcome computational problems due to intersection of coordinate surfaces with the earth`s surface. Under this project, the authors have completed the development of a model based on a generalized vertical coordinate, {zeta} = F({Theta}, p, p{sub s}), in which an isentropic coordinate can be combined with a terrain-following {sigma}-coordinate a smooth transition between the two. One of the key issues in developing such a model is to satisfy the consistency between the predictions of pressure and potential temperature. In the model, the consistency is satisfied by the use of an equation that determines the vertical mass flux. A procedure to properly choose {zeta} = F({Theta}, p, p{sub s}) is also developed, which guarantees that {zeta} is a monotonic function of height even when unstable stratification occurs. There are two versions of the model constructed in parallel: one is the middle-latitude {beta}-plane version and the other is the global version. Both of these versions include moisture prediction, relaxed large-scale condensation and relaxed moist-convective adjustment schemes. A well-mixed planetary boundary layer (PBL) is also added.
Date: December 31, 1997
Creator: Arakawa, Akio & Konor, C.S.
Partner: UNT Libraries Government Documents Department

Effects of Barometric Fluctuations on Well Water-Level Measurements and Aquifer Test Data

Description: The Pacific Northwest National Laboratory, as part of the Hanford Groundwater Monitoring Project, examines the potential for offsite migration of contamination within underlying aquifer systems. Well water-level elevation measurements from selected wells within these aquifer systems commonly form the basis for delineating groundwater-flow patterns (i.e., flow direction and hydraulic gradient). In addition, the analysis of water-level responses obtained in wells during hydrologic tests provides estimates of hydraulic properties that are important for evaluating groundwater-flow velocity and transport characteristics. Barometric pressure fluctuations, however, can have a discernible impact on well water-level measurements. These barometric effects may lead to erroneous indications of hydraulic head within the aquifer. Total hydraulic head (i.e., sum of the water-table elevation and the atmospheric pressure at the water-table surface) within the aquifer, not well water-level elevation, is the hydrologic parameter for determining groundwater-flow direction and hydraulic gradient conditions. Temporal variations in barometric pressure may also adversely affect well water-level responses obtained during hydrologic tests. If significant, adjustments or removal of these barometric effects from the test-response record may be required for quantitative hydraulic property determination. This report examines the effects of barometric fluctuations on well water-level measurements and evaluates adjustment and removal methods for determining areal aquifer head conditions and aquifer test analysis. Two examples of Hanford Site unconfined aquifer tests are examined that demonstrate barometric response analysis and illustrate the predictive/removal capabilities of various methods for well water-level and aquifer total head values. Good predictive/removal characteristics were demonstrated with best corrective results provided by multiple-regression deconvolution methods.
Date: December 16, 1999
Creator: FA Spane, Jr.
Partner: UNT Libraries Government Documents Department

Hyperthermal Pulsed-Laser Ablation Beams for Film Deposition and Surface Microstructural Engineering

Description: This paper presents an overview of pulsed-laser ablation for film deposition and surface microstructure formation. By changing the ambient gas pressure from high vacuum to several Torr (several hundred Pa) and by selecting the pulsed-laser wavelength, the kinetic energy of ablated atoms/ions can be varied from several hundred eV down to {approximately}0.1 eV and films ranging from superhard to nanocrystalline may be deposited. Furthermore, cumulative (multi-pulse) irradiation of a semiconductor surface (e.g. silicon) in an oxidizing gas (0{sub 2}, SF{sub 6}) et atmospheric pressure can produce dense, self-organized arrays of high-aspect-ratio microcolumns or microcones. Thus, a wide range of materials synthesis and processing opportunities result from the hyperthermal flux and reactive growth conditions provided by pulsed-laser ablation.
Date: November 8, 1999
Creator: Lowndes, D.H.
Partner: UNT Libraries Government Documents Department

Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

Description: The objective of this project is to identify the key physics and chemistry underlying the use of atmospheric pressure plasmas for etching removal of actinides and actinide surrogates. This includes understanding of basic discharge mechanism at atmospheric pressure, gas and surface phase chemistry, and optimization and scale-up effort of atmospheric pressure plasma jet (APPJ).
Date: June 1, 1999
Creator: Hicks, Robert F. & Selwyn, Gary
Partner: UNT Libraries Government Documents Department

Ferroelectric-to-Relaxor Crossover and Oxygen Vacancy Hopping in Compositionally-Disordered Perovskites - KtA(1-x)Nb(x)O(3):Ca

Description: It is shown that lattice disorder induced by Nb and Ca substitution has a strong influence on the dielectric and relaxational properties of KTaO{sub 3}. Both substituents are believed to occupy off-center positions at the Ta site, and the difference in valence between the Ca{sup 2+} and Ta{sup 5+} ions leads to the formation of oxygen vacancies (V{sub 0}). Specifically, for a KTa{sub 1{minus}x}Nb{sub x}O{sub 3}:Ca crystal with x = 0.023 and with a 0.055 at.% Ca doping they observe: (1) a ferroelectric transition at atmospheric pressure (1 bar); (2) a large enhancement of the transition temperature by Ca doping; (3) a pressure-induced crossover from ferroelectric-to-relaxor behavior; (4) the impending vanishing of the relaxor phase at high pressure; (5) the reorientation of the Ca-oxygen vacancy (Ca:V{sub 0}) pair defect; and (6) the variation of the energetics and dynamics of this reorientation with pressure. Most of these effects are associated with Nb- and Ca-induced dipolar entities and appear to be general features of soft mode ferroelectrics with random-site polar nanodomains. The ferroelectric-to-relaxor crossover can be understood in terms of a large decrease with pressure in the correlation length among polar nanodomains--a unique property of soft ferroelectric mode systems.
Date: July 26, 1999
Creator: Samara, G.A. & Boatner, L.A.
Partner: UNT Libraries Government Documents Department

Correlation effects on stability in Pu metal and its alloys

Description: The existence of six crystallographic allotropes from room temperature up to the solid-liquid transition just above 913 K at atmospheric pressure makes solid Plutonium unique among the elements in the periodic table. Among these phases (labeled {alpha}, {beta}, {gamma}, {delta}{delta}{prime}), and {var_epsilon}, the {delta} phase, stable between 593 K and 736 K, has commanded considerable interest in the metallurgical and solid state communities. In contrast to the low-temperature monoclinic {alpha} phase, which is brittle, the face-centered cubic (fcc) {delta} phase is ductile, a property that makes it convenient for engineering applications. This phase can also be stabilized through alloying with a number of other elements such as Ga, Al, Sc, and Am.
Date: April 1, 1999
Creator: Cooper, B R; Gonis, A; Kiousis, N; Price, D L & Turchi, P E
Partner: UNT Libraries Government Documents Department


Description: Magnetically tuned emission lines from ions and atoms were utilized to determine concentrations of NO gas with high selectivity and high sensitivity. One of the Zeeman components of an emission line was shifted to exactly coincide with a single rotational-vibrational lines of NO, whereas the other component was shifted away from the NO line. The coincident component indicated the extent of NO absorption and the noncoincident component measured the extent of background absorption. By making use of a differential measurement, light scattering and molecular absorption caused by coexisting small particles and gases were cancelled out. Detection limits of NO in N{sub 2} were about 30 ppb and 150 ppb at low pressure and at atmospheric pressure, respectively.
Date: March 1, 1979
Creator: Koizumi, Hideaki; Hadeishi, Tetsuo & McLaughlin, Ralph D.
Partner: UNT Libraries Government Documents Department

The Application of Global Kinetic Models to HMX Beta-Delta Transition and Cookoff Processes

Description: The reduction of the number of reactions in kinetic models for both the HMX beta-delta phase transition and thermal cookoff provides an attractive alternative to traditional multi-stage kinetic models due to reduced calibration effort requirements. In this study, we use the LLNL code ALE3D to provide calibrated kinetic parameters for a two-reaction bidirectional beta-delta HMX phase transition model based on Sandia Instrumented Thermal Ignition (SITI) and Scaled Thermal Explosion (STEX) temperature history curves, and a Prout-Tompkins cookoff model based on One-Dimensional Time to Explosion (ODTX) data. Results show that the two-reaction bidirectional beta-delta transition model presented here agrees as well with STEX and SITI temperature history curves as a reversible four-reaction Arrhenius model, yet requires an order of magnitude less computational effort. In addition, a single-reaction Prout-Tompkins model calibrated to ODTX data provides better agreement with ODTX data than a traditional multi-step Arrhenius model, and can contain up to 90% less chemistry-limited time steps for low-temperature ODTX simulations. Manual calibration methods for the Prout-Tompkins kinetics provide much better agreement with ODTX experimental data than parameters derived from Differential Scanning Calorimetry (DSC) measurements at atmospheric pressure. The predicted surface temperature at explosion for STEX cookoff simulations is a weak function of the cookoff model used, and a reduction of up to 15% of chemistry-limited time steps can be achieved by neglecting the beta-delta transition for this type of simulation. Finally, the inclusion of the beta-delta transition model in the overall kinetics model can affect the predicted time to explosion by 1% for the traditional multi-step Arrhenius approach, while up to 11% using a Prout-Tompkins cookoff model.
Date: December 7, 2006
Creator: Wemhoff, A P; Burnham, A K & Nichols III, A L
Partner: UNT Libraries Government Documents Department


Description: Atmospheric pressure and temperature excursions at constant volume for oxidation of high temperature sodium are investigated analytically. Data under both the adiabatic condition and the time dependent transient heat transfer condition are reported. The analyses represent parametric cases involving variations in containment geometry, variations in sodium conditions, and variations in contained gas conditions including oxygen concentrations of 0 to 21 vol%. The objective is to obtain data for design of containment for the Fast Flux Test Facility. Design of containment requires a knowledge of maximum temperatures and pressures to be expected as a consequence of the unlikely occurrence of a high volume sodium leak. This information is presented in graphical and tabular form.
Date: March 7, 1970
Creator: Shire, PR
Partner: UNT Libraries Government Documents Department