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Rigid muffin-tin approximation for the electron-phonon interaction in transition metals

Description: Progress in calculating the electron-phonon parameters of transition metals has been based on either the rigid muffin-tin approximation (RMTA) or the fitted modified tight-binding approximation (FMTBA). The RMTA has been shown to be remarkably accurate for average electron-phonon properties, but there are indications that RMTA matrix elements may be too small at low momentum transfer. An attempt is made to demonstrate these assertions concerning the accuracy of RMTA and the numerous electron-ph… more
Date: January 1, 1980
Creator: Butler, W. H.
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Partner: UNT Libraries Government Documents Department
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Note on the cryostatic stability of superconducting composites

Description: A careful discussion is given of the ''equal area condition'' developed by Maddock et al. In order to make the essential points as clear as possible, analytical solutions are derived under simplifying assumptions (simple model for heat transfer by nucleate and film boiling liquid helium; constant heat conduction and specific heat) instead of using more realistic but less controllable computer calculations. A quantitative definition of the concept of a long wire is given. Num… more
Date: February 1, 1978
Creator: Gauster, W. F.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Potential for use of high-temperature superconductors in fusion reactors

Description: The present rate of development of high-temperature superconductors (HTSs) is sufficiently rapid that there may be opportunities for their use in contemporary fusion devices such as the International Thermonuclear Experimental Reactor (ITER). The most likely 1application is for delivering power to the superconducting magnets, especially in substituting for the current leads between the temperatures of 4 K and 77K. A second possible application of HTSs is as a liquid-nitrogen-cooled power bus, c… more
Date: January 1, 1991
Creator: Hull, J.R.
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Partner: UNT Libraries Government Documents Department
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Adaptive Mesh Refinement for 1-Dimensional Gas Dynamics

Description: We consider the solution of the one-dimensional equation of gas-dynamics. Accurate numerical solutions are difficult to obtain on a given spatial mesh because of the existence of physical regions where components of the exact solution are either discontinuous or have large gradient changes. Numerical methods treat these phenomena in a variety of ways. In this paper, the method of adaptive mesh refinement is used. A thorough description of this method for general hyperbolic systems is given else… more
Date: 1982-08~
Creator: Hedstrom, Gerald; Rodrigue, Garry; Berger, Marsha & Oliger, Joseph
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Partner: UNT Libraries Government Documents Department
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Analytical model for a vertical buoyant jet

Description: An analytical model for a round and two-dimensional turbulent buoyant jet which is discharged vertically into a stagnant ambient is developed. The buoyant jet is considered to have three separate zone models which are matched to form a complete solution. The velocity field is determined for the entire jet and plume regions by the use of an eddy viscosity which varies along the axis of the jet. The centerline decay of buoyancy is determined throughout and the results are compared to existing num… more
Date: October 1, 1980
Creator: Lee, D. W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Dependence of secondary ion emission from organic material on the energy loss of the impacting heavy ion

Description: Samples of the amino acid valine were irradiated by 2.5 MeV-Ar, 0.8 MeV-Kr and 1.0 MeV Xe beams from the Argonne Dynamitron accelerator in order to study the energy distributions of ejected secondary ions. For Kr and Xe the nuclear stopping power exceeded the electronic stopping power by a factor 2 or 3, respectively, but the functional shape of the energy distributions and the mean ejection energies (0.9--1.4 eV) indicated that the molecular ions (M{plus minus}H){sup {plus minus}} are desorbed… more
Date: January 1, 1991
Creator: Hunt, J.E. (Argonne National Lab., IL (United States)) & Wien, K. (Technische Hochschule Darmstadt (Germany). Inst. fuer Kernphysik)
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Partner: UNT Libraries Government Documents Department
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Sources of polarized ions and atoms

Description: In this presentation we discuss methods of producing large quantities of polarized atoms and ions (Stern-Gerlach separation, optical pumping, and spin-exchange) as well as experimental methods of measuring the degree of polarization of atomic systems. The usefulness of polarized atoms in probing the microscopic magnetic surface properties of materials will also be discussed. 39 refs., 5 figs., 2 tabs.
Date: January 1, 1988
Creator: Cornelius, W.D.
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Partner: UNT Libraries Government Documents Department
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Applications of mesoscopic physics

Description: This report discusses the following topics: Acoustical nondestructive evaluation of heterogeneous materials in the multiple scattering regime. Classical and quantum superdiffusion in a time-dependent random potential. Negative Magnetoresistance in Variable Range Hopping Conduction. Reproducible Conductance Fluctuations in Macroscopic Anderson Insulators. Feasibility of far-infared lasers using multiple semiconductor quantum wells.
Date: January 1, 1992
Creator: Feng, Shechao.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Is the two-term expansion valid for highly anisotropic systems. The Townsend ionization coefficient in strong runaway as a test case

Description: The Townsend ionization coefficient in the strong runaway regime is calculated within the framework of the two-term expansion. Results are compared to the 1-D model. General features of the two models are qualitatively similar, but quantitative differences by factors of approx. 2 are observed.
Date: July 15, 1982
Creator: Yu, S. S. & Melendez, R. E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Complex temporal and spatial patterns in nonequilibrium systems

Description: Dynamical systems methods are being developed and used to characterize the formation and evolution of temporal and spatial patterns in systems maintained far from equilibrium. In particular, experiments and analyses are considering electrodeposition of fractal metallic clusters, pattern formation in reaction-diffusion systems, and the primary instabilities of some fluid flows. Novel reactors have been developed to search for chemical patterns (spatial variations in the chemical composition), an… more
Date: September 1, 1991
Creator: Swinney, H. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Devil's staircase and order without periodicity in classical condensed matter

Description: The existence of incommensurate structures proves that crystal ordering is not always the most stable one for nonquantum matter. Some properties of structures which are obtained by minimizing a free energy are investigated in the Frenkel Kontorova and related models. It is shown that an incommensurate structure can be either quasi-sinusoidal with a phason mode or built out of a sequence of equidistant defects (discommensurations) which are locked to the lattice by the Peierls force. In that sit… more
Date: January 1, 1982
Creator: Aubry, S.
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Partner: UNT Libraries Government Documents Department
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Neutron diffraction study of magnetic order in the ternary superconductor ErMo/sub 6/Se/sub 8/

Description: Synthesis of new classes of ternary superconducting materials has led to compounds which also show a strong tendency toward magnetic order when one of the constituent elements is a rare earth. Powder neutron diffraction data on superconducting (T/sub s/ approximately 6 K) samples of ErMo/sub 6/Se/sub 8/ taken in the temperature range 0.05 to 2.0 K show that magnetic Bragg peaks develop at T/sub M/ = 1.1 K, in agreement with specific heat studies. However, it is not possible to index these new r… more
Date: 1977~
Creator: Lynn, J. W.; Moncton, D. E.; Shirane, G.; Thomlinson, W.; Eckert, J. & Shelton, R. N.
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Partner: UNT Libraries Government Documents Department
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Equation of state of solid neon from x-ray diffraction measurements to 110 GPa

Description: This paper briefly discusses the pressure-volume properties of condensed neon. X-ray diffraction techniques are used to determine solid neon equation of state and crystal structure. 16 refs., 2 figs. (LSP)
Date: January 1, 1987
Creator: Hemley, R. J.; Jephcoat, A. P.; Zha, C. S.; Mao, H. K.; Finger, L. W. & Cox, D. E.
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Partner: UNT Libraries Government Documents Department
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NQR-NMR studies of higher alcohol synthesis Cu-Co catalysts

Description: The primary objective of the project is to examine the relations between the catalytic and magnetic properties of the copper-cobalt higher alcohol synthesis catalysts. We have undertaken to investigate the magnetic character by studying the Nuclear Quadrupole resonance of copper and (Zerofield) Nuclear Magnetic Resonance of cobalt in copper cobalt catalysts.
Date: December 17, 1991
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Study of roughness-induced diffuse and specular reflectance at silver-air and silver-liquid interfaces. Final report, July 1, 1979-August 31, 1980

Description: Results of an extended investigation of surface plasma-wave absorption and roughness-induced optical scattering from an interface of silver and air are described. In particular, the position of the surface plasma resonance minimum in reflectivity for a stochastically roughened metal silver surface has been studied as a function of a number of distinct roughness perturbations. In the case of a transparent liquid-silver boundary the frequency red shift of the resonance minimum has been determined… more
Date: July 1, 1980
Creator: Sari, S.O.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Performance of trim coils made by a novel method

Description: A precision, automated method of manufacturing trim coils based on printed circuit technology has been developed. Excellent quench performance and increased radiation resistance have been achieved in recently-tested models of sextupole trim coils developed for operation inside 40 mm-aperture SSC Main Collider dipoles. 6 refs., 2 figs.
Date: January 1, 1991
Creator: Wanderer, P.; Anerella, M.; Cottingham, J.; Ganetis, G.; Garber, M.; Ghosh, A. et al.
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Partner: UNT Libraries Government Documents Department
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Progress in collisions of multiply charged ions

Description: The increasing power and availability of supercomputers during the last decade led to significant progress in the theory of multicharged ion interactions. However, important tests of many theoretical predictions were lacking, and have become possible only quite recently as new capabilities have been realized in the laboratory. This paper broadly surveys some of these experimental developments, and their impact on our understanding of collisional interactions of multicharged ions. The scope is l… more
Date: January 1, 1991
Creator: Phaneuf, R.A.
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Partner: UNT Libraries Government Documents Department
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Superconductivity: Past, present, and future

Description: This paper provides an overview of superconductor research and development activities, with emphasis on the potential of high-{Tc} materials for future applications. Superconductor applications are grouped under the following categories: electronics/instrumentation, bulk material/castings, research devices, industrial/commercial, electric power, and transportation/propulsion. Near-term applications are typically based on thin film and cast forms of high-{Tc} materials, while large-scale applica… more
Date: January 1, 1992
Creator: Uherka, K.L.
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Partner: UNT Libraries Government Documents Department
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Microscopic theory of charges density wave instability in NbSe/sub 2/

Description: The microscopic theory of Sinha and Harmon for electronically driven lattice instabilities is used to explain the ''Kohn-like'' anomalies in the ..sigma../sub 1/ phonon branch and the observed incommensurate superlattice Bragg peak in 2H-NbSe/sub 2/, characteristic of the charge density wave at low temperatures in the neutron scattering experiments of Moncton et al. In accordance with the APW and LCAO band-structure calculations of Mattheiss of 2H-NbSe/sub 2/, the presence o… more
Date: January 1, 1977
Creator: Das, S G; Sinha, S K & Wakabayashi, N
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Partner: UNT Libraries Government Documents Department
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Elastic constants and the structural phase transition in La sub 2-x Sr sub x CuO sub 4

Description: Resonant ultrasound spectroscopy is used to measure the temperature dependence of all six elastic moduli of La{sub 2-x}Sr{sub x}CuO{sub 4}. A giant softening (> 50% reduction) in the in-plane shear modulus, c{sub 66}, is observed and is attributed to the tetragonal-orthorhombic structural phase transition in this material. This phase transition and the corresponding softening is examined with a simple anharmonic mechanical model and a macroscopic Ginsburg-Landau formalism exploiting the full sy… more
Date: January 1, 1991
Creator: Sarrao, J.L.; Lei, Ming; Stekel, A.; Bell, T.M.; Leisure, R. G.; Sham, L.J. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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