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in subjects: "Shear"

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Shear alfven resonances in Tokapole II

It has been suggested that efficient heating can occur by coupling energy through the shear Alfven resonance that is predicted to occur at particular locations within inhomogeneous plasmas. This heating mechanism should be applicable to tokamaks; however, the existence of the resonances in tokamaks has not yet been established experimentally. We present here direct observations of localized enhancement in the driven wave magnetic field which are compatible with theoretical predictions for the s… more

Date: March 1, 1982

Creator: Witherspoon, F.D.; Prager, S.C. & Sprott, J.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Solder fatigue reduction in point focus photovoltaic concentrator modules

Solder fatigue tests have been conducted on point focus photovoltaic concentration cell assemblies to identify a baseline fatigue life and to quantify the fatigue life improvements that result using a copper-molybdenum-copper low-expansion insert between the solar cell and copper heat spreader. Solder microstructural changes and fatigue crack growth were identified using cross sections and ultrasonic scans of the fatigue solder joints. The Coffin-Manson and Total Strain fatigue models for low-c… more

Date: January 1, 1991

Creator: Hund, T. D. & Burchett, S. N.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Vortices associated with toroidal ion temperature gradient driven fluctuations

The three nonlinear hydrodynamic equations for potential, parallel ion velocity and ion pressure used in simulations of the toroidal ion temperature gradient driven fluctuations and transport in a shear magnetic field are analyzed for coherent vortex structures. Two types of vortex structures are found: one type for weak shear that is a generalization of the usual modon vortex construction and the second type of solution for strong magnetic shear where the convective nonlinearity in the paralle… more

Date: May 1, 1992

Creator: Horton, W. (Texas Univ., Austin, TX (United States). Inst. for Fusion Studies); Jovanovic, D. (Belgrade Univ. (Yugoslavia). Inst. za Fiziku) & Rasmussen, J.J. (Association Euratom-Risoe National Lab., Roskilde (Denmark))

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Molten salt freeze seal. Final report

This report documents the results of the testing performed at Sandia National Laboratory, Albuquerque, New Mexico, on the applicability of a sodium freeze seal type valve stem in a molten salt environment. The freeze seal tests consisted of cycling the valve stem at set temperature intervals, checking the temperature distribution for freeze plug location, and verifying the actuator forces. In addition to the test results, this report also documents the engineering analysis and other tasks perfo… more

Date: August 1, 1985

Creator: Corugedo, J.J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Excitation of high-n toroidicity-induced shear Alfven eigenmodes by energetic particles and fusion alpha particles in tokamaks

The stability of high-n toroidicity-induced shear Alfven eigenmodes (TAE) in the presence of fusion alpha particles or energetic ions in tokamaks is investigated. The TAE modes are discrete in nature and thus can easily tap the free energy associated with energetic particle pressure gradient through wave particle resonant interaction. A quadratic form is derived for the high-n TAE modes using gyro-kinetic equation. The kinetic effects of energetic particles are calculated perturbatively using t… more

Date: July 1, 1992

Creator: Fu, G. Y. & Cheng, C. Z.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Gelled polymer systems for permeability modification in petroleum reservoirs

The research program described in this report was conducted to improve the performance and predictability of in situ gelation processes designed to increase volumetric sweep efficiency of fluid displacement processes. A principal objective of this research was to develop procedures for design and evaluation of permeability modification processes. Research was conducted in three broad areas: (1) Physical and Chemical Characterization of Gelling Systems (2) In situ Gelation and (3) Mathematical M… more

Date: September 1, 1991

Creator: Willhite, G.P.; Green, D.W.; Thiele, J.L.; McCool, C.S. & Mertes, K.B.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Flow shear suppression of turbulence using externally driven ion Bernstein and Alfven waves

The utilization of externally-launched radio-frequency waves as a means of active confinement control through the generation of sheared poloidal flows is explored. For low-frequency waves, kinetic Alfven waves are proposed, and are shown to drive sheared E {times} B flows as a result of the radial variation in the electromagnetic Reynolds stress. In the high frequency regime, ion Bernstein waves are considered, and shown to generate sheared poloidal rotation through the ponderomotive force. In … more

Date: January 1, 1991

Creator: Biglari, H.; Ono, M. (Princeton Univ., NJ (United States). Plasma Physics Lab.); Diamond, P.H. (California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics) & Craddock, G.G. (Science Applications International Corp., San Diego, CA (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Development and utilization of new diagnostics for dense-phase pneumatic transport

Dense-phase pneumatic transport is an attractive means of conveying solids. Unfortunately, because of the high solid concentrations, this transport method is a difficult regime in which to carry out detailed measurements. Hence most details of the flow are unknown. In this context, the main objective of this work is to develop probes for local measurements of solid velocity and holdup in dense gas-solid flows. Because we anticipate the recent theories of rapid granular flows will bring insight … more

Date: January 1, 1991

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Nonlinear evolution of resistive tearing mode instability with shear flow and viscosity

The nonlinear evolution of the tearing mode instability with equilibrium shear flow is investigated via numerical solutions of the resistive magnetohydrodynamic equations. The two-dimensional simulations are in slab geometry, are periodic in the x-direction, and are initiated with solutions of the linearized MHD equations. The magnetic Reynolds number S was varied from 10{sup 2} to 10{sup 5}, a parameter V that measures the strength of the flow in units of the average Alfven speed was varied, a… more

Date: December 1, 1991

Creator: Ofman, L.; Morrison, P.J. (Texas Univ., Austin, TX (United States). Inst. for Fusion Studies) & Steinolfson, R.S. (Southwest Research Inst., San Antonio, TX (United States). Dept. of Space Sciences)

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Thinning and rupture of a thin liquid film on a heated surface

The objective of this work continues to be the study of dynamics, stability, and rupture (including contact line motions) of thin liquid films, especially with heat and/or mass transfer. Following the publication of a comprehensive paper on thin-film stability and rupture, taking into account evaporation (condensation), thermocapillarity, surface tension, vapor recoil, van der Waals forces, and mass loss (gain), two follow-up papers have appeared. The first examines the conditions for a non-uni… more

Date: May 1, 1992

Creator: Bankoff, S.G. & Davis, S.H.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Effects of shear on vortex shedding patterns in high Reynolds number flow: an experimental study

Vortex shedding has been identified as a potential major source of loading on the Ocean Thermal Energy Conversion (OTEC) Plant Cold Water Pipe (CWP). To gain a better understanding of the vortex shedding phenomena, a series of model tests has been conducted. The results of this investigation are presented. The effects of current shear on vortex shedding patterns in high Reynolds number (R/sub e/) flow around a circular cylinder used to model the OTEC CWP are addressed. Tests were conducted in a… more

Date: unknown

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Hydrodynamic design loads for the OTEC cold water pipe

Ocean current and/or plant motion crossflows induce time dependent hydrodynamic loads on the OTEC cold water pipe due to vortex shedding. Design criteria were established for mean and fluctuating loads based on a review of the literature, analysis of test data acquired by SAI under a previous experimental program and an analytical extension of test results to higher Reynolds number. Baseline loads were specified for rigid cylinders in uniform flows. Modifications to the loads by current shear, … more

Date: September 1, 1978

Creator: Hove, D.; Shih, W. & Albano, E.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Finite element analysis for the initiation of lamellar tearing in welded joints

A numerical procedure using the finite element method is presented for predicting the initiation of lamellar tearing in fillet welded T-joints commonly employed in large structures. Starting with a prescribed geometry, the welding process is approximated by a known time-dependent volumetric heat source which simulates the arc heating and deposition of liquid metal. The transient nonlinear thermal and stress problems are then solved using finite element computer codes. Results of the elastic-pla… more

Date: January 1, 1980

Creator: Krieg, R. D. & Thomas, R. K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Pretreatment of Kapton-coated cable for epoxy adhesion

Preliminary testing of a new system for protecting bonded strain gages that will be attached to the MFTF magnets indicated falling electrical resistance to ground, attributed to the infiltration of moisture. The most likely infiltration route seemed to be along the Kapton lead cable, which has an outer surface of FEP fluorocarbon resin. Samples of the cable were pretreated with a fluorocarbon etchant, Tetra-Etch, for periods of 10, 25, and 40 s at room temperature, followed by rinsing with demi… more

Date: January 9, 1984

Creator: Carley, J. F.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Relationship between swelling and the shear modulus of irradiated metal

In three alloy systems, AISI 316, the Ni-Al binary system, and the Fe-Cr-Ni ternary system, a relationship exists between the shear modulus of the unirradiated alloys and the resultant swelling observed. An alloying addition which reduces the shear modulus will subsequently reduce the irradiation-induced swelling in a solid solution hardened alloy system. The reduction in swelling is thought to be associated with the void nucleation phase of the swelling phenomenon. Thus, relative high temperat… more

Date: February 1, 1979

Creator: Bates, J. F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Mechanical tests for validation of seismic isolation elastomer constitutive models

High damping laminated elastomeric bearings are becoming the preferred device for seismic isolation of large buildings and structures, such as nuclear power plants. The key component of these bearings is a filled natural rubber elastomer. This material exhibits nonlinear behavior within the normal design range. The material damping cannot be classified as either viscous or hysteritic, but it seems to fall somewhere in between. This paper describes a series of tests that can be used to character… more

Date: January 1, 1992

Creator: Kulak, R.F. & Hughes, T.H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Numerical simulations of collisionless drift instabilities for low-density plasmas

Nonlinear behavior of the collisionless drift instabilities are studied for the universal and current driven modes by means of electrostatic particle simulations in two-and-a-half dimensions. Realistic mass ratios of the electrons to the ions are used in the simulations, where the guiding-center approximation for the electrons and the exact dynamics for the ions are employed. Several nonlinear effects including the quasilinear diffusion of the particle density, the frequency shift due to the am… more

Date: October 1, 1977

Creator: Lee, W. W.; Yau, Y. Y. K. & Okuda, H.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Structural analysis of TFTR toroidal field coil conceptual design

The conceptual design evaluation of the V-shaped toroidal field coils on the Tokamak Fusion Test Reactor has been performed by detailed structural analysis with the finite element method. The innovation provided by this design and verified in this work is the capability to support toroidal field loads while simultaneously performing the function of twist restraint against the device axial torques resulting from the vertical field loads. The evaluations made for the conceptual design provide pre… more

Date: October 1, 1975

Creator: Smith, R. A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Resistive G-modes and ballooning

A unified theory of the linear stability of the Roberts and Taylor type of resistive interchange and ballooning is presented. The effects of both parallel and perpendicular viscosity as well as of finite shear and finite ..beta.. are included in a MHD treatment of the problem. Kinetic effects are also studied. The hybrid kinetic model with Vlasov ions and guiding center electrons has been appropriately generalized to allow for electron-ion collisions. The geometry is that of a plane slab with m… more

Date: January 1, 1980

Creator: Dagazian, R.Y.; Mondt, J.P. & Paris, R.B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Mechanical characterization of selected adhesives and bulk materials at liquid nitrogen and room temperatures

This paper presents the results of a series of mechanical tests on selected adhesives and bulk materials. The materials tested are of general interest to designers of magnets for cryogenic service and include several epoxies, a varnish, a B-stage glass cloth, insulation papers, and commercially available fiber-reinforced composites. These tests were performed at room temperature (293 K) and at liquid nitrogen temperature (77 K). The tests include both simple tension tests and lap shear tests wi… more

Date: January 1, 1977

Creator: Fitzpatrick, C.M. & Stoddart, W.C.T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Mechanical design and finite element analysis of the SDC central calorimeter

When designing scintillating calorimeters for the study of particle interactions resulting from colliding beams, a primary goal is to instrument 100% of the available solid angle. In pursuit of this goal the challenge for mechanical designers is to minimize the amount of structural mass and still maintain acceptable engineering standards in the design. Argonne National Laboratory, High Energy Physics involvement in the design of a central calorimeter for the SSC started in 1989. Our first propo… more

Date: January 1, 1992

Creator: Guarino, V.; Hill, N. F.; Nasiatka, J.; Hoecker, D. A.; Hordubay, T. D. & Swensrud, R. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The relaxation of the second moments in rapid shear flows of smooth disks

This paper compares the results of numerical simulations for two- dimensional, rapid, homogeneous shear flows of identical, smooth, inelastic disks with the predictions of Jenkins and Richman (JFM 192, 313-328 (1988)) for the relaxation of the second moments of the velocity distribution function following a homogeneous, but anisotropic disturbance of their steady values. For nearly elastic disks, the time-history of the relaxation is in excellent agreement with the theory in both its dense and … more

Date: 1991

Creator: Louge, M. Y.; Jenkins, J. T. & Hopkins, M. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Static and simulated seismic testing of the TRG-7 through -16 shear wall structures

Results from the static, simulated seismic base excitation, and experimental modal analysis tests performed on the TRG-7 through -16 structures are reported. These results were used to establish the scalability of static and dynamic response measured on small structural models to the dynamic response of conventional concrete structures. In addition, these tests provided information concerning cumulative damage effects that occur in concrete structures when they are subjected to different dynami… more

Date: September 1, 1991

Creator: Farrar, C.R. (Los Alamos National Lab., NM (United States)); Baker, W.E. (New Mexico Univ., Albuquerque, NM (United States)) & Dove, R.C. (Dove (R.C.), Del Norte, CO (United States))

Item Type: Report

Partner: UNT Libraries Government Documents Department

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BPX insulation irradiation program test results

The toroidal field coil insulation for the Burning Plasma Experiment (BPX) is expected to receive a radiation dose of nearly 10{sup 10} rad and to withstand significant mechanical stresses. An irradiation test program was performed at the Idaho National Engineering Laboratory (INEL) using the Advanced Technology Reactor (ATR) for irradiations to doses on the order of 3 {times} 10{sup 10} rad. The flexure and shear strength with compression of commercially procured sheet material were reported e… more

Date: January 1, 1991

Creator: McManamy, T.J. (Oak Ridge National Lab., TN (United States)); Kanemoto, G. (EG and G Idaho, Inc., Idaho Falls, ID (United States)) & Snook, P.G. (Princeton Univ., NJ (United States). Plasma Physics Lab.)

Item Type: Article

Partner: UNT Libraries Government Documents Department