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Diffusion welding multifilament superconductive composites (open access)

Diffusion welding multifilament superconductive composites

Diffusion welding is shown to be a feasible method for joining composites of niobium-titanium superconductor alloy filaments in a pure copper matrix. Good results were repeatedly obtained using 15/sup 0/ scarf joints welded with externally heated tooling and simple uniaxial compression loading in a conventional hydraulic press. Weld cycles of less than one hour total elapsed time were readily attainable. Through proper closed-die design, it was possible to increase welding pressure sufficiently to use relatively low temperatures to coincide with the optimum aging heat treatment of the superconductor alloy. This temperature limitation is important to retain optimal superconductor properties. Confirming measurements of critical current density of welded joints at 4.2/sup 0/K are in progress. In the welded joints made under optimum conditions, there is bonding of all constituents, including superconductor filaments. Weld tooling which effectively contains the relatively fluid matrix, and resists deformation during repeated weld cycles, is essential to the successful application of the diffusion welding process to these composites.
Date: February 27, 1978
Creator: Witherell, C.E.
System: The UNT Digital Library
Information systems for engineering sustainable development (open access)

Information systems for engineering sustainable development

The ability of a country to follow sustainable development paths is determined to a large extent by the capacity or capabilities of its people and its institutions. Specifically, capacity-building in the UNCED terminology encompasses the country's human, scientific, technological, organizational, institutional, and resource capabilities. A fundamental goal of capacity-building is to enhance the ability to pose, evaluate and address crucial questions related to policy choices and methods of implementation among development options. As a result the United Nations Conference on Environment and Development (UNCED) Agenda 21 planning process has identified the need for better methods by which information can be transferred between industrialized nations and developing nations. The reasons for better methods of information transfer include facilitating decisions related to sustainable development and building the capacity of developing nations to better plan their future in both an economical and environmentally sound manner. This paper is a discussion on mechanisms for providing information and technologies available for presenting the information to a variety of cultures and levels of technical literacy. Consideration is given to access to information technology as well as to the cost to the user. One concept discussed includes an Engineering Partnership'' which brings together the talents and resources …
Date: February 27, 1992
Creator: Leonard, R.S.
System: The UNT Digital Library
Combined low-temperature scanning tunneling/atomic force microscope for atomic resolution imaging and site-specific force spectroscopy (open access)

Combined low-temperature scanning tunneling/atomic force microscope for atomic resolution imaging and site-specific force spectroscopy

The authors present the design and first results of a low-temperature, ultrahigh vacuum scanning probe microscope enabling atomic resolution imaging in both scanning tunneling microscopy (STM) and noncontact atomic force microscopy (NC-AFM) modes. A tuning-fork-based sensor provides flexibility in selecting probe tip materials, which can be either metallic or nonmetallic. When choosing a conducting tip and sample, simultaneous STM/NC-AFM data acquisition is possible. Noticeable characteristics that distinguish this setup from similar systems providing simultaneous STM/NC-AFM capabilities are its combination of relative compactness (on-top bath cryostat needs no pit), in situ exchange of tip and sample at low temperatures, short turnaround times, modest helium consumption, and unrestricted access from dedicated flanges. The latter permits not only the optical surveillance of the tip during approach but also the direct deposition of molecules or atoms on either tip or sample while they remain cold. Atomic corrugations as low as 1 pm could successfully be resolved. In addition, lateral drifts rates of below 15 pm/h allow long-term data acquisition series and the recording of site-specific spectroscopy maps. Results obtained on Cu(111) and graphite illustrate the microscope's performance.
Date: February 27, 2008
Creator: Schwarz, Udo; Albers, Boris J.; Liebmann, Marcus; Schwendemann, Todd C.; Baykara, Mehmet Z.; Heyde, Markus et al.
System: The UNT Digital Library
Studies of Potential Inhibitors of Sodium Aluminosilicate Scales in High-Level Waste Evaporation (open access)

Studies of Potential Inhibitors of Sodium Aluminosilicate Scales in High-Level Waste Evaporation

The Savannah River Site (SRS) has 49 underground storage tanks used to store High Level Waste (HLW). The tank space in these tanks must be managed to support the continued operation of key facilities. The reduction of the tank volumes in these tanks are accomplished through the use of three atmospheric pressure HLW evaporators. For a decade, evaporation of highly alkaline HLW containing aluminum and silicates has produced sodium aluminosilicate scales causing both operation and criticality hazards in the 2H Evaporator System. Segregation of aluminum-rich wastes from silicate-rich wastes minimizes the amount of scale produced and reduces cleaning expenses, but does not eliminate the scaling nor increases operation flexibility in waste process. Similar issues have affected the aluminum refining industry for many decades. Over the past several years, successful commercial products have been identified to eliminate aluminosilicate fouling in the aluminum industry, but have not been utilized in a nuclear environment. Laboratory quantities of three proprietary aluminosilicate scale inhibitors have been produced and been shown to prevent formation of scales. SRNL has been actively testing these potential inhibitors to examine their radiation stability, radiolytic degradation behaviors, and downstream impacts to determine their viability within the HLW system. One of the …
Date: February 27, 2008
Creator: Wilmarth, W. R.; Oji, L. N.; Fellinger, T. L.; Hobbs, D. T. & Badheka, N. P.
System: The UNT Digital Library
Reversible expansion of gallium-stabilized (delta)-plutonium (open access)

Reversible expansion of gallium-stabilized (delta)-plutonium

It is shown that the transient expansion of plutonium-gallium alloys observed both in the lattice parameter as well as in the dimension of a sample held at ambient temperature can be explained by assuming incipient precipitation of Pu{sub 3}Ga. However, this ordered {zeta}-phase is also subject to radiation-induced disordering. As a result, the gallium-stabilized {delta}-phase, being metastable at ambient temperature, is driven towards thermodynamic equilibrium by radiation-enhanced diffusion of gallium and at the same time reverted back to its metastable state by radiation-induced disordering. A steady state is reached in which only a modest fraction of the gallium present is arranged in ordered {zeta}-phase regions.
Date: February 27, 2006
Creator: Wolfer, W G; Oudot, B & Baclet, N
System: The UNT Digital Library
Technology of the LSST Focal Plane (open access)

Technology of the LSST Focal Plane

None
Date: February 27, 2008
Creator: O'Connor, P.; Radeka, V.; Takacs, P.; Geary, J.; Gilmore, K.; Oliver, J. et al.
System: The UNT Digital Library
Monochromatic electron photoemission from diamondoid monolayers (open access)

Monochromatic electron photoemission from diamondoid monolayers

We found monochromatic electron photoemission from large-area self-assembled monolayers of a functionalized diamondoid, [121]tetramantane-6-thiol. Photoelectron spectra of the diamondoid monolayers exhibited a peak at the low-kinetic energy threshold; up to 68percent of all emitted electrons were emitted within this single energy peak. The intensity of the emission peak is indicative of diamondoids being negative electron affinity materials. With an energy distribution width of less than 0.5 electron volts, this source of monochromatic electrons may find application in technologies such as electron microscopy, electron beam lithography, and field-emission flatpanel displays.
Date: February 27, 2007
Creator: Yang, Wanli; Yang, Wanli L.; Fabbri, J. D.; Willey, T. M.; Lee, J. R. I.; Dahl, J. E. et al.
System: The UNT Digital Library
CANCELLED Microwave Ion Source and Beam Injection for anAccelerator-Driven Neut ron Source (open access)

CANCELLED Microwave Ion Source and Beam Injection for anAccelerator-Driven Neut ron Source

An over-dense microwave driven ion source capable of producing deuterium (or hydrogen) beams at 100-200 mA/cm{sup 2} and with atomic fraction > 90% was designed and tested with an electrostatic low energy beam transport section (LEBT). This ion source was incorporated into the design of an Accelerator Driven Neutron Source (ADNS). The other key components in the ADNS include a 6 MeV RFQ accelerator, a beam bending and scanning system, and a deuterium gas target. In this design a 40 mA D{sup +} beam is produced from a 6 mm diameter aperture using a 60 kV extraction voltage. The LEBT section consists of 5 electrodes arranged to form 2 Einzel lenses that focus the beam into the RFQ entrance. To create the ECR condition, 2 induction coils are used to create {approx} 875 Gauss on axis inside the source chamber. To prevent HV breakdown in the LEBT a magnetic field clamp is necessary to minimize the field in this region. Matching of the microwave power from the waveguide to the plasma is done by an autotuner. They observed significant improvement of the beam quality after installing a boron nitride liner inside the ion source. The measured emittance data are compared …
Date: February 27, 2007
Creator: Vainionpaa, J. H.; Gough, R.; Hoff, M.; Kwan, J. W.; Ludewigt, B. A.; Regis, M. J. et al.
System: The UNT Digital Library
Temperature-controlled molecular depolarization gates in nuclear magnetic resonance (open access)

Temperature-controlled molecular depolarization gates in nuclear magnetic resonance

Down the drain: Cryptophane cages in combination with selective radiofrequency spin labeling can be used as molecular 'transpletor' units for transferring depletion of spin polarization from a hyperpolarized 'source' spin ensemble to a 'drain' ensemble. The flow of nuclei through the gate is adjustable by the ambient temperature, thereby enabling controlled consumption of hyperpolarization.
Date: February 27, 2008
Creator: Schroder, Leif; Schroder, Leif; Chavez, Lana; Meldrum, Tyler; Smith, Monica; Lowery, Thomas J. et al.
System: The UNT Digital Library
High Harmonic Generation for N2 and CO2 beyond the Two-point Model (open access)

High Harmonic Generation for N2 and CO2 beyond the Two-point Model

None
Date: February 27, 2008
Creator: Guhr, M.; McFarland, B.K.; Farrell, J.P.; Bucksbaum, P.H. & /SLAC, PULSE /SLAC
System: The UNT Digital Library
Electrokinetic coupling in unsaturated porous media (open access)

Electrokinetic coupling in unsaturated porous media

We consider a charged porous material that is saturated bytwo fluid phases that are immiscible and continuous on the scale of arepresentative elementary volume. The wetting phase for the grains iswater and the nonwetting phase is assumed to be an electricallyinsulating viscous fluid. We use a volume-averaging approach to derivethe linear constitutive equations for the electrical current density aswell as the seepage velocities of the wetting and nonwetting phases onthe scale of a representative elementary volume. These macroscopicconstitutive equations are obtained by volume-averaging Ampere's lawtogether with the Nernst Planck equation and the Stokes equations. Thematerial properties entering the macroscopic constitutive equations areexplicitly described as functions of the saturation of the water phase,the electrical formation factor, and parameters that describe thecapillary pressure function, the relative permeability function, and thevariation of electrical conductivity with saturation. New equations arederived for the streaming potential and electro-osmosis couplingcoefficients. A primary drainage and imbibition experiment is simulatednumerically to demonstrate that the relative streaming potential couplingcoefficient depends not only on the water saturation, but also on thematerial properties of the sample, as well as the saturation history. Wealso compare the predicted streaming potential coupling coefficients withexperimental data from four dolomite core samples. Measurements on thesesamples include electrical …
Date: February 27, 2007
Creator: Revil, A.; Linde, N.; Cerepi, A.; Jougnot, D.; Matthai, S. & Finsterle, S.
System: The UNT Digital Library
Reserve seismic capacity determination of a nuclear power plant braced frame with piping (open access)

Reserve seismic capacity determination of a nuclear power plant braced frame with piping

A typical diagonal braced steel frame was developed to determine the amount of reserve capacity that is available beyond elastic design levels. The frame was analyzed first using elastic static and dynamic analyses. The loadings included dead and live load, an equivalent static lateral earthquake load, two response spectra and a suite of eight earthquake time history records. The response spectra used were the Housner and Regulatory Guide 1.60. The time histories represented different site conditions, distances to causative faults and magnitudes. The lateral static load and Housner spectrum represent vintage design criteria, while the R.G. 1.60 and time history analyses reflect current methodology. The elastic limit responses of the structure were determined along with the accompanying threshold peak ground accelerations (threshold g values). The frame was then analyzed using the program DRAIN-2D to perform two-dimensional elastic--plastic analyses for the eight time histories.
Date: February 27, 1979
Creator: Nelson, T.A.
System: The UNT Digital Library
Proposal for a new tomographic device providing information on the chemical properties of a body section (open access)

Proposal for a new tomographic device providing information on the chemical properties of a body section

A system to analyze the chemical properties of a region of tissue located deep inside the human body without having to access it is proposed. The method is based on a high precision detection of x-rays or ..gamma..-rays (photons) from an external source Compton scattered from the tissue under inspection. The method provides chemical information of plane regions lying not too deep inside the body (<6 cm). The amount of radiation absorbed by the body is about the same as needed for a standard x-ray tomography. The exposure time is estimated to be shorter than 10 minutes. 37 refs., 13 figs.
Date: February 27, 1986
Creator: Gatti, E.; Rehak, P. & Kemmer, J.
System: The UNT Digital Library
Sodium technology activities at HEDL in support of fast reactor development and the FFTF (open access)

Sodium technology activities at HEDL in support of fast reactor development and the FFTF

Activities of the Hanford Engineering Development Laboratory are presented. A brief description of FFTF and some highlights of reactor operations are reviewed. The sodium technology work at HEDL is summarized by discussing several facets of the program and their tie-ins to breeder reactor development.
Date: February 27, 1984
Creator: Atwood, J.M.
System: The UNT Digital Library
The design of the AIE: An object-oriented application development system (open access)

The design of the AIE: An object-oriented application development system

Three years ago, in response to our challenging development context, the Advanced Modeling and Analysis Section designed and implemented an object-oriented environment -- the Application Interface Engine (AIE). Our prototyping requirements forced existing application development systems beyond their capabilities. Programmers at AMAS and its contractors have developed over twenty applications using AIE. Our initial experience has been very positive. AIE extends an object-oriented programming language with syntax and classes to support applications specification. This extended system improves all stages of the application engineering life cycle, from rapid prototyping to long term maintenance.
Date: February 27, 1992
Creator: Fuja, R.S. & Widing, M.A.
System: The UNT Digital Library
Technical options for the future of West Valley (open access)

Technical options for the future of West Valley

The West Valley Processing Plant reprocessed spent fuel from 1966 to 1972. It was shut down in 1972 for modifications, and in 1976 NFS decided not to renew the lease. This paper discusses the technical options for dealing with the financial responsibilities. The study shows that there is a range of options for both decommissioning and continued use of the plant with decommissioning involving either the immobilization or the off-site disposal of the wastes. (DLC)
Date: February 27, 1979
Creator: Luner, C. & Lazur, E.G.
System: The UNT Digital Library
Application of Soil Venting at a Large Scale: A Data and Modeling Analysis (open access)

Application of Soil Venting at a Large Scale: A Data and Modeling Analysis

Soil venting will be applied at a demonstration scale to a site at the Idaho National Engineering Laboratory which is contaminated with carbon tetrachloride and other organic vapors. The application of soil venting at the site is unique in several aspects including scale, geology, and data collection. The containmented portion of the site has a surface area of over 47,000 square meters (12 acres) and the depth to the water table is approximately 180 meters. Migration of contaminants through the entire depth of the vadose zone is evidenced by measured levels of chlorinated solvents in the underlying aquifer. The geology of the site consists of a series of layered basalt flows interspersed with sedimentary interbeds. The depth of the vadose zone, the nature of fractured basalt flows, and the degree of contamination all tend to make drilling difficult and expensive. Because of the scale of the site, extent of contamination, and expense of drilling, a computer model has been developed to simulate the migration of the chlorinated solvents during plume growth and cleanup. The demonstration soil venting operation has been designed to collect pressure drop and plume migration data to assist with calibration of the transport model. The model will …
Date: February 27, 1990
Creator: Walton, J. C.; Baca, R. G.; Sisson, J. B. & Wood, T. R.
System: The UNT Digital Library
Collider physics for the late 1980's (open access)

Collider physics for the late 1980's

Topics in the Standard Model of strong and electroweak interactions and how these topics are relevant for the high energy colliders are discussed. Radiative corrections in the Glashow-Weinberg-Salam model are discussed, stressing how these corrections may be measured at LEP and the SLC. CP violation is discussed, followed by a discussion of the Higgs boson and the searches which can be carried out for it. Some features of quantum chromodynamics are discussed which are relevant to hadron colliders. Some of the problems which the Standard Model does not solve are discussed. 115 refs., 53 figs. (LEW)
Date: February 27, 1987
Creator: Hinchliffe, I.
System: The UNT Digital Library
Pressure measurements of nonplanar stress waves (open access)

Pressure measurements of nonplanar stress waves

A useful gage has been developed for measuring pressure of nonplanar or obliquely incident stress waves. The measurements made with these gages are not as precise as direct strain gage measurements, but are very good considering the conditions under which these gages are used. We feel a need to further develop our ability to measure nonplanar stress waves in the 0 to 10 kbar range. Carbon or ytterbium will probably be chosen for the sensing element.
Date: February 27, 1981
Creator: Carlson, G.H. & Charest, J.A.
System: The UNT Digital Library
Information systems for engineering sustainable development (open access)

Information systems for engineering sustainable development

The ability of a country to follow sustainable development paths is determined to a large extent by the capacity or capabilities of its people and its institutions. Specifically, capacity-building in the UNCED terminology encompasses the country`s human, scientific, technological, organizational, institutional, and resource capabilities. A fundamental goal of capacity-building is to enhance the ability to pose, evaluate and address crucial questions related to policy choices and methods of implementation among development options. As a result the United Nations Conference on Environment and Development (UNCED) Agenda 21 planning process has identified the need for better methods by which information can be transferred between industrialized nations and developing nations. The reasons for better methods of information transfer include facilitating decisions related to sustainable development and building the capacity of developing nations to better plan their future in both an economical and environmentally sound manner. This paper is a discussion on mechanisms for providing information and technologies available for presenting the information to a variety of cultures and levels of technical literacy. Consideration is given to access to information technology as well as to the cost to the user. One concept discussed includes an ``Engineering Partnership`` which brings together the talents and resources …
Date: February 27, 1992
Creator: Leonard, R. S.
System: The UNT Digital Library
Slow Nonradiative Decay for Rare Earths in KPb2Br5 and RbPb2Br5 (open access)

Slow Nonradiative Decay for Rare Earths in KPb2Br5 and RbPb2Br5

We report on spectroscopic investigations of Nd{sup 3+}- and Tb{sup 3+}- doped low phonon energy, moisture-resistant host crystals, KPb{sub 2}Br{sub 5} and RbPb{sub 2}Br{sub 5}, and their potential to serve as new solid state laser materials at new wavelengths, especially in the long wavelength infrared region. This includes emission spectra, emission lifetime measurements, Raman scattering spectra as well as calculations of the multiphonon decay rate, radiative lifetimes and quantum efficiencies for relevant (laser) transitions in these crystals.
Date: February 27, 2004
Creator: Rademaker, K.; Petermann, K.; Huber, G.; Krupke, W.; Page, R.; Payne, S. et al.
System: The UNT Digital Library
EFFECTIVE POROSITY IMPLIES EFFECTIVE BULK DENSITY IN SORBING SOLUTE TRANSPORT (open access)

EFFECTIVE POROSITY IMPLIES EFFECTIVE BULK DENSITY IN SORBING SOLUTE TRANSPORT

The concept of an effective porosity is widely used in solute transport modeling to account for the presence of a fraction of the medium that effectively does not influence solute migration, apart from taking up space. This non-participating volume or ineffective porosity plays the same role as the gas phase in single-phase liquid unsaturated transport: it increases pore velocity, which is useful towards reproducing observed solute travel times. The prevalent use of the effective porosity concept is reflected by its prominent inclusion in popular texts, e.g., de Marsily (1986), Fetter (1988, 1993) and Zheng and Bennett (2002). The purpose of this commentary is to point out that proper application of the concept for sorbing solutes requires more than simply reducing porosity while leaving other material properties unchanged. More specifically, effective porosity implies the corresponding need for an effective bulk density in a conventional single-porosity model. The reason is that the designated non-participating volume is composed of both solid and fluid phases, both of which must be neglected for consistency. Said another way, if solute does not enter the ineffective porosity then it also cannot contact the adjoining solid. Conceptually neglecting the fluid portion of the non-participating volume leads to a …
Date: February 27, 2012
Creator: Flach, G.
System: The UNT Digital Library
Analysis of the Younger Dryas Impact Layer (open access)

Analysis of the Younger Dryas Impact Layer

We have uncovered a thin layer of magnetic grains and microspherules, carbon spherules, and glass-like carbon at nine sites across North America, a site in Belgium, and throughout the rims of 16 Carolina Bays. It is consistent with the ejecta layer from an impact event and has been dated to 12.9 ka BP coinciding with the onset of Younger Dryas (YD) cooling and widespread megafaunal extinctions in North America. At many locations the impact layer is directly below a black mat marking the sudden disappearance of the megafauna and Clovis people. The distribution pattern of the Younger Dryas boundary (YDB) ejecta layer is consistent with an impact near the Great Lakes that deposited terrestrial-like ejecta near the impact site and unusual, titanium-rich projectile-like ejecta further away. High water content associated with the ejecta, up to 28 at. percent hydrogen (H), suggests the impact occurred over the Laurentide Ice Sheet. YDB microspherules and magnetic grains are highly enriched in TiO{sub 2}. Magnetic grains from several sites are enriched in iridium (Ir), up to 117 ppb. The TiO{sub 2}/FeO, K/Th, TiO{sub 2}/Zr, Al{sub 2}O{sub 3}/FeO+MgO, CaO/Al{sub 2}O{sub 3}, REE/ chondrite, FeO/MnO ratios and SiO{sub 2}, Na{sub 2}O, K{sub 2}O, Cr{sub 2}O{sub 3}, …
Date: February 27, 2010
Creator: Firestone, Richard B.; West, Allen; Revay, Zsolt; Hagstrum, Jonathon T,; Belgya, Thomas; Hee, Shane S. Que et al.
System: The UNT Digital Library
Aza Cope Rearrangement of Propargyl Enammonium Cations Catalyzed By a Self-Assembled `Nanozyme (open access)

Aza Cope Rearrangement of Propargyl Enammonium Cations Catalyzed By a Self-Assembled `Nanozyme

The tetrahedral [Ga{sub 4}L{sub 6}]{sup 12-} assembly (L = N,N-bis(2,3-dihydroxybenzoyl)-1,5-diaminonaphthalene) encapsulates a variety of cations, including propargyl enammonium cations capable of undergoing the aza Cope rearrangement. For propargyl enammonium substrates that are encapsulated in the [Ga{sub 4}L{sub 6}]{sup 12-} assembly, rate accelerations of up to 184 are observed when compared to the background reaction. After rearrangement, the product iminium ion is released into solution and hydrolyzed allowing for catalytic turnover. The activation parameters for the catalyzed and uncatalyzed reaction were determined, revealing that a lowered entropy of activation is responsible for the observed rate enhancements. The catalyzed reaction exhibits saturation kinetics; the rate data obey the Michaelis-Menten model of enzyme kinetics, and competitive inhibition using a non-reactive guest has been demonstrated.
Date: February 27, 2008
Creator: Hastings, Courntey J.; Fiedler, Dorothea; Bergman, Robert G. & Raymond, Kenneth N.
System: The UNT Digital Library