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The Drag of Streamline Wires

Description: "Preliminary results are given of drag tests of streamline wires. Full-size wires were tested over a wide range of speeds in the N.A.C.A. high speed tunnel. The results are thus directly applicable to full-scale problems and include any compressibility effects encountered at the higher speeds. The results show how protuberances may be employed on conventional streamline wires to reduce the drag, and also show how the conventional wires compare with others having sections more like strut or symmetrical airfoil sections" (p. 1).
Date: December 1933
Creator: Jacobs, Eastman N.
Partner: UNT Libraries Government Documents Department

Some Experiences Regarding the Nonlinearity of Hot Wires

Description: "We compare here the results of some experiences with the formulas established in our preceding report 'Nonlinear Theory of a Hot-Wire Anemometer.' We shall show that the nonlinear term plays a role as important as the thermal conduction in the calculation of the thermal inertia of the hot wire" (p. 1).
Date: June 1952
Creator: Betchov, R. & Welling, W.
Partner: UNT Libraries Government Documents Department

Resistance of streamline wires

Description: "This note contains the results of tests to determine the resistance of four sizes of streamline wire. The investigation was conducted in the six-inch wind tunnel of the National Advisory Committee for Aeronautics. The tests were made at various velocities and it was found that the resistance of streamline wires was considerably less than that of round wires of equivalent strength. Scale effect was also found since, with an increase of Reynolds Number, a decrease in the resistance coefficient was obtained" (p. 1).
Date: March 1928
Creator: DeFoe, George L.
Partner: UNT Libraries Government Documents Department

Measurements of the Nonlinear Variation With Temperature of Heat-Transfer Rate From Hot Wires in Transonic and Supersonic Flow

Description: Note presenting equilibrium temperatures and heat-transfer rates for 0.00015- and 0.00030-inch diameter tungsten wires normal to the flow throughout a range of Mach numbers and Reynolds numbers. For the range of variables, equilibrium temperature of the hot wire is characterized by constant recovery factor for subsonic Mach numbers but constant equilibrium to total temperature ratio for supersonic Mach numbers. Results regarding the equilibrium temperature tests and heat-transfer tests are provided.
Date: April 1957
Creator: Winovich, Warren & Stine, Howard A.
Partner: UNT Libraries Government Documents Department

Large Exploding Wires-Correlation to Small Wires and Pause Time Versus Length Dependency

Description: The results of small exploding-wire studies were found to be capable of direct extrapolation to larger wires (an increase in cross-sectional area of 1500 to 1500 from the small wires). Copper wires up to 40 mils in diameter and iron wires to 62 mils in diameter were studied for use as fuses. in lengths up to 18 in. A dependency between pause time (the time between system current cut-off and current restrike) and wire length is described for several sizes of copper wires exploded with 16.5- and 49.5-kilojoule sources. The role of wire confinement is discussed in connection with establishment of the pause. (auth)
Date: May 1, 1959
Creator: Cnare, E. C. & Neilson, F. W.
Partner: UNT Libraries Government Documents Department

Radiative Properties of High Wire Number Tungsten Arrays with Implosion Times up to 250 ns

Description: High wire number, 25-mm diameter tungsten wire arrays have been imploded on the 8-MA Saturn generator, operating in a long-pulse mode. By varying the mass load from 710 to 6140 ps/cm, implosion times of 130 to 250 ns have been obtained with implosion velocities of 50 to 25 cn-dys, respectively. These z-pinch implosions produced plasmas with millimeter diameters that radiated 600 to 800 kJ of x-rays, with powers of 20 to 49 TW; the corresponding pulse widths were 19 to 7.5 ns, with risetimes ranging from 6.5 to 4.0 ns. These powers and pulse widths are similar to those achieved with 50 ns implosion times on Saturn. Two-dimensional, radiation- magnetohydrodynamic calculations indicate that the imploding shells in these long implosion time experiments are comparable in width to those in the short pulse cases. This can only be due to lower initial perturbations. A heuristic wire array model suggests that the reduced perturbations, in the long pulse cases, may be due to the individual wire merger occurring well before the acceleration of the shell. The experiments and modeling suggest that 150 to 200 ns implosion time z-pinches could be employed for high-power, x-ray source applications.
Date: February 2, 1999
Creator: Beg, F.N.; Coverdale, C.A.; Deeney, C.; Douglas, M.R.; Haines, M.G.; Peterson, D.L. et al.
Partner: UNT Libraries Government Documents Department

Linear stability of an accelerated wire array

Description: The linear stability of an array of a large number of thin wires is considered. The wires form a cylindrical surface which is accelerated towards the axis under the action of a current excited in the array by an external source. General equations governing stability of this system are derived and a complete classification of all the modes present in such a system is presented. In agreement with an earlier analysis by Felber and Rostoker, it is shown that there exist two types of modes: medial modes, in which the wires experience deformation in the rz plane, and lateral modes, in which only a purely azimuthal deformation is present. For a given axial wave number k, the maximum growth rate for medial perturbations corresponds to a mode in which all the wires move �in phase� (an analog of an axisymmetric mode for a continuous cylindrical shell), whereas for the lateral perturbations the maximum growth rate corresponds to the opposite displacements of the neighboring wires. Numerical analysis of a dispersion relation for a broad range of modes is presented: Some limiting cases are discussed. In particular, it is shown that a traditional k�� scaling holds until surprisingly high wave numbers, even exceeding the inverse inter- wire distance. In the limit of long-wavelength perturbations, a model of a continuous shell becomes valid; the presence of the wires manifests itself in this model by a strong anisotropy of electrical conductivity, high along the wires and vanishing across the wires. The resulting modes differ considerably from the modes of a thin perfectly conducting shell. In particular, a new mode of �zonal flows� is identified.
Date: October 15, 1998
Creator: Hammer, J H & Ryutov, D D
Partner: UNT Libraries Government Documents Department


Description: Second generation (2G) technologies to fabricate high-performance superconducting wires developed at the Oak Ridge National Laboratory (ORNL) were transferred to American Superconductor via this CRADA. In addition, co-development of technologies for over a decade was done to enable fabrication of commercial high-temperature superconducting (HTS) wires with high performance. The massive success of this CRADA has allowed American Superconductor Corporation (AMSC) to become a global leader in the fabrication of HTS wire and the technology is fully based on the Rolling Assisted Biaxially Textured Substrates (RABiTS) technology invented and developed at ORNL.
Date: October 23, 2012
Creator: Goyal, A. & Rupich, M. (American Superconductor Corp.)
Partner: UNT Libraries Government Documents Department

Magnetoconductance of Independently Tunable Tunnel-Coupled Double Quantum Wires

Description: The authors report on their recent experimental studies of vertically-coupled quantum point contacts subject to in-plane magnetic fields. Using a novel flip-chip technique, mutually aligned split gates on both sides of a sub micron thick double quantum well heterostructure define a closely-coupled pair of ballistic one-dimensional (1D) constrictions. They observe quantized conductance steps due to each quantum well and demonstrate independent control of each ID constriction width. In addition, a novel magnetoconductance feature at {approximately}6 T is observed when a magnetic field is applied perpendicular to both the current and growth directions. This conductance dip is observed only when 1D subbands are populated in both the top and bottom constrictions. This data is consistent with a counting model whereby the number of subbands crossing the Fermi level changes with field due to the formation of an anticrossing in each pair of 1D subbands.
Date: July 13, 2000
Partner: UNT Libraries Government Documents Department

A New Form of Standard Resistance

Description: Report issued by the Bureau of Standards over new developments of electrical resistivity in manganin wire coils. The results of the developments are discussed. This report includes tables, illustrations, and photographs.
Date: October 1, 1908
Creator: Rosa, Edward B.
Partner: UNT Libraries Government Documents Department

Numerical simulation of fiber and wire array Z-pinches with Trac-II

Description: Trac-II is a two dimensional axisymmetric resistive MHD code. It simulates all three spatial components (r, z, &phi;) of the magnetic field and fluid velocity vectors, and the plasma is treated as a single fluid with two temperatures (T<sub>e</sub>,T<sub>i</sub>). In addition, it can optionally include a self-consistent external circuit. Recent modifications to the code include the addition of the 3-T radiation model, a 4-phase (solid-liquid-vapor-plasma) equation of state model (QEOS), a 4-phase electrical/thermal conductivity model, and an implicit solution of poloidal B<sub>z</sub>,B<sub>r</sub>) magnetic field diffusion. These changes permit a detailed study of fiber and wire array Z-pinches. Specifically, Trac-II is used to study the wire array Z-pinch at the PBFA-Z pulse power generator at Sandia National Laboratory. First, in 1-D we examine the behavior of a single wire in the Z-pinch. Then, using these results as initial radial conditions in 2-D, we investigate the dynamics of wire array configurations in the r-z and r-&theta; plane. In the r-z plane we examine the growth of the m=0 or ��sausage�� instability in single wires within the array. In the r-&theta; plane we examine the merging behavior between neighboring wires. Special emphasis is placed on trying to explain how instability growth affects the performance of the Z-pinch. Lastly, we introduce Trac-III, a 3-D MHD code, and illustrate the m=1 or �"kink" instability. We also discuss how Trac-III can be modified to simulate the wire array Z-pinch.
Date: September 1, 1998
Creator: Reisman, D
Partner: UNT Libraries Government Documents Department

Some comments on manganin wire pressure gauges

Description: A standard manganin wire pressure gage was examined by comparing it with a recently developed 0.01% CaF/sub 2/ capacitive pressure gage. The effects of the Bridgman water kick'' and intrinsic time constant are clearly shown, and the results punctuate the usual assertion that manganin wire gages are extremely difficult to use approaching the 0.1% level. (auth)
Date: January 1, 1973
Creator: Andeen, C.; Schuele, D. & Fontanella, J.
Partner: UNT Libraries Government Documents Department

Manipulator Cable With Constant Stress

Description: A manipulator or mechanical arm involves an upper and a lower arm, with a variable angle between them. Cables used to transmit motion and force from the upper to the lower arms pass over a pulley at the joint or elbow. A pulley, axiaily fixed with respect to the joint, imposes a change in length of the cable as the angle between the arms varies. Manipulation design requires a cable of constant length during this variation; this constant length may be achieved by guiding the center of the pulley along the proper path. Acceptable solutions were obtained in terms of variables such as the lengths of each arm, the radius of the pulley, and the angle between the arms. In one design the pulley center is moved along a straight line with respect to the lower arm, while in the other solution the pulley center is moved along a circular arc with respect to the upper amn. Practical and economical mechanisms based on these solutions were investigated for use in manipulator design. (auth)
Date: November 1, 1959
Creator: Grimson, J. H.
Partner: UNT Libraries Government Documents Department