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Transient elastodynamic response of a circular crack in a thick plate under torsion

Description: The elastodynamic response of a thick plate under torsion is considered. A penny-shaped crack is assumed to exist in the center of the plate such that the problem is axisymmetric in nature. The crack is pressurized suddenly along its surfaces resulting in transient conditions. This problem is also equivalent to that of sudden appearance of a crack in the loaded plate. Hankel and Laplace transforms are used to reduce the problem to the solution of a pair of dual integral equations. A numerical Laplace inversion routine is used to recover the time-dependence of the solution. The dynamic stress intensity factor is determined and its dependence on time and geometry is discussed.
Date: January 1, 1979
Creator: Chen, E.P.
Partner: UNT Libraries Government Documents Department

Transient thermal stress analysis of a proposed pion production target

Description: The results of a transient temperature and stress analysis of a proposed LAMPF proton target are presented. The target configuration, suitable for the LAMPF A-1, A-2, or A-5 pion production sites (800-MeV protons, 1-mA average current), is composed of pyrolytic graphite and is cooled by flowing water. Special attention is paid to the pulsed nature of the proton beam (6% duty). The computer code TSAAS is used to develop a temperature and stress history of the target during the first five beam pulses and the final, steady-state temperature distribution. The results of this analysis indicate that a conduction-cooled pyrolytic graphite target of the type shown in this report wil be suitable as a LAMPF pion production target at a beam current of 1 mA.
Date: May 1, 1978
Creator: Lindquist, L.O. & Scarbrough, E.C.
Partner: UNT Libraries Government Documents Department

Thermal properties. Period covered: October--December 1975

Description: The thermal decomposition investigation of PETN using an LX-13 type PETN was begun this quarter. Samples are being conditioned at 373, 353 and 333/sup 0/K and others will be conditioned at 393 and 383/sup 0/K. Data from five samples are reported. A series of chemical reactivity tests was made using PETN to determine if decomposition rates could be calculated from the results. The data fit a semilogarithmic plot of the gas evolved as a function of time reasonably well. The last of a series of HNAB and PETN samples was evaluated to determine if the two are compatible. These samples were conditioned at 80/sup 0/C for 26 and 25 months and showed no indication of reactivity. The investigation into methods of improving the chemical reactivity test data has continued and a source of a small variation in the instrument sensitivity was determined.
Date: January 1, 1975
Creator: Myers, L.C.
Partner: UNT Libraries Government Documents Department

Thin epitaxial silicon for dE/dx detectors

Description: The techniques for fabricating thin self-supporting epitaxial films for dE/dx detectors have been studied. Detectors having thicknesses between 1 and 4 ..mu..m with areas of 12.5 mm/sup 2/ have been fabricated and tested. The response of the detectors has been studied with alpha particles, oxygen ions, and fission framents.
Date: January 1, 1976
Creator: Maggiore, C. J.; Goldstone, P. D.; Gruhn, C. R.; Jarmie, N.; Stotlar, S. C. & DeHaven, H. V.
Partner: UNT Libraries Government Documents Department

Three-dimensional finite element formulation for fluid-structure interaction

Description: The safety evaluation of fast reactors often involves the modeling of various types of structural components which interact with surrounding fluid in three-dimensional space. In this paper, several key areas for performing three-dimensional fluid-structure interaction calculations are discussed. A new development is presented for a three-dimensional hexahedral hydrodynamic finite-element based upon a Quasi-Eulerian approach. By using trilinear shape functions and assuming a constant pressure field within the element, simple relations are obtained for internal nodal forces. The forms developed are easily coded and computationally efficient. Because the formulation is based upon a rate approach it is applicable to problems involving large displacements. Only adiabatic processes are considered. The difficult tasks (1) of input data preparation and checking and (2) the displaying of computed results are discussed. The use of automatic mesh generators, input data error analysis, and graphical display of the finite element meshes used to model reactor components are shown to ease the input task. In the final section, the formulation is applied to the three-dimensional fluid-structure interactions involved in a current reactor safety problem.
Date: January 1, 1979
Creator: Kulak, R.F.
Partner: UNT Libraries Government Documents Department

Bovine lymphocytic leukemia: studies of etiology, pathogenesis and mode of transmission. Progress report No. 17, July 1976--October 1977

Description: The primary objective of the proposed research will be elucidation of the etiology and pathogenesis of bovine leukemia. We have consistently demonstrated C-type particles in mitogen stimulated lymphocyte cultures from leukemic cows and cows with a persistent lymphocytosis. These particles have been concentrated and partially purified by continuous flow, density gradient, ultracentrifugation. Newborn calves and late stage bovine fetuses have been inoculated with these concentrated cell free preparations. Our current study involves extensive monitoring of these inoculated animals to detect early pre-cancerous changes. The following parameters are being measured: the serological titer against a bovine leukemia associated antigen; the percentage of lymphocytes showing nuclear pockets; the percentage of mitogen stimulated lymphocytes with C-type particles adherent to their surface; the percentage of B-lymphocytes in the peripheral circulation; the complete blood count; and the quantity of bovine leukemia virus (BLV) production as determined by the syncytia induction assay. Additional proposals include: using the monitoring parameters to study animals with the juvenile and thymic forms of leukemia; the examination of adult lymphosarcoma cases to determine which tissues harbor BLV; and lymphocyte subpopulation work to further define which cell types are associated with BLV production and tumor formation.
Date: July 22, 1977
Creator: Sorensen, D. K.
Partner: UNT Libraries Government Documents Department

Brillouin scatter in a hydrodynamic simulation

Description: A numerical method for modeling stimulated Brillouin scatter (SBS) in a hydrodynamic simulation code is discussed. Preliminary results using the model show that scattering is reduced as shorter wavelengths are used and for spherical symmetry that ion heating by SBS is not significant since the ions cool by expansion.
Date: June 8, 1979
Creator: Harte, J.; Estabrook, K. & Bailey, D.
Partner: UNT Libraries Government Documents Department

Bulk shielding facility quarterly report, October, November, and December of 1975

Description: The BSR operated at an average power level of 1,996 kw for 31.93 percent of the time during the report period. Water-quality control in both the reactor primary and secondary cooling systems was satisfactory. An unscheduled shutdown occurred on October 31, 1975, because of water loss from the pool at a rate of 1.6 gpm, apparently due to several small leaks. The reactor fuel was transferred to the OGR Canal Storage and the pool water level lowered to the pool floor. Defective areas in the concrete pool walls and floor are being chipped, grouted and sealed in preparation for applying fiberglass and repainting. Pool repairs accounted for 98 percent of the downtime reported. The PCA was not used during this report period and remains in a secured condition.
Date: May 1, 1976
Creator: Hurt, S. S. III.; Lance, E. D. & Thomas, J. R.
Partner: UNT Libraries Government Documents Department

Calculation of radionuclides in the defense waste processing facility

Description: SHIELD system calculations yield the isotopic inventory, activity, decay heat, and multigroup radiation source spectra for all of the DWPF process streams and for the solidified waste products. One application of these results is the analysis of the radiation emissions of the stored waste. Another application is the analysis of time dependent properties of the solidified waste. Initially, gamma radiation from /sup 137m/Ba decay contributes approximately one-third of the total energy. As the /sup 137/Cs content decreases, the gamma contribution declines. The major producers of beta radiation are the /sup 90/Sr, /sup 137/Cs, and /sup 144/Pr decay chains. As the glass age increases, however, the contribution from the actinides dominates increasingly. The inital activity level in the glass is 2000 curies per gallon. The activity and decay heat decrease by a factor of 2 in about fifteen years, and by a factor of 4 in fifty years. A similar analysis was made for the salt cake. Initially, the salt cake produces 0.01 watts per gallon from 2.4 curies per gallon of activity. In five years, the activity is reduced by a factor of 19, and the decay heat declines by a factor of 24. After ten years, both the activity and decay heat levels are less than 1% of their initial values. 7 figures, 4 tables.
Date: January 1, 1979
Creator: Chandler, J.R.; Finch, D.R. & Becker, G.W. Jr.
Partner: UNT Libraries Government Documents Department

Calculation of the small scale self-focusing ripple gain spectrum for the CYCLOPS laser system: a status report

Description: The FLAC code (Fourier Laser Amplifier Code) was used to simulate the CYCLOPS laser system up to the third B-module and to calculate the maximum ripple gain spectrum. The model of this portion of CYCLOPS consists of 33 segments that correspond to 20 optical elements (simulation of the cell requires 2 segments and 12 external air spaces). (MHR)
Date: October 1, 1976
Creator: Fleck, J. A. Jr.; Morris, J. R. & Thompson, P. F.
Partner: UNT Libraries Government Documents Department

Method of lines approach to the numerical solution of conservation laws

Description: New explicit finite difference methods are developed for approximating the discontinuous time dependent solutions of nonlinear hyperbolic conservation laws. The analysis is based on the method of lines approach of decoupling the space and time discretizations and analyzing each independently before combining them into a composite method. Particular attention is given analyzing to high order spatial differences, artificial dissipation and the accurate approximation of boundary conditions. Both a third order iterated leap-frog predictor-corrector and a second order iterated Runge--Kutta method are shown to have excellent stability and accuracy properties for the time integration. These methods are A-stable when iterated to convergence and have the special property of allowing for local improvements in the stability and accuracy of the computed solution. The paper is designed to aid a scientist or engineer construct a numerical method specially tailored to a specific problem. The analysis requires an elementary knowledge of the numerical solution of ordinary differential equations, finite difference theory and gas dynamics.
Date: January 1, 1979
Creator: Hyman, J.M.
Partner: UNT Libraries Government Documents Department

MHD stability limits on high-. beta. tokamaks

Description: Limitations on high-..beta.. tokamaks are imposed by a number of ideal and resistive MHD instabilities. The present paper reports results on three such studies: (1) Numerical analysis using the Princeton PEST code on ..beta.. optimization of tokamaks for low toroidal mode numbers n; (2) analytic and numerical results on ideal ballooning modes with high n; and (3) analytic and numerical results on resistive ballooning modes at high n.
Date: August 1, 1978
Creator: Chance, M.S.; Dewar, R.L. & Frieman, E.A.
Partner: UNT Libraries Government Documents Department

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 of three narrow d bands of atomic symmetry xy, x/sup 2/-y/sup 2/ and 3z/sup 2/-r/sup 2/ at the Fermi level is assumed. Thus the conduction-band wave function is represented by a linear combination of tight-binding Gaussian atomic orbitals with neglect of the variation of the radial wave function across the bands. The screened electron-ion interaction and the Coulomb energy of the charge fluctuation on the d shells of Nb atoms is represented by a pseudopotential screened by the Lindhard dielectric function. The phonon eigenvectors needed for estimating the electron-phonon interaction were calculated using a simple force constant model. In agreement with the experimental results, it was found that the phonon frequencies for the ..sigma../sub 1/ and ..sigma../sub 3/ branches are very strongly renormalized as one approaches the zone boundary. By introducing the electronic relaxation effects a central peak appears at the q vector of the instability and the actual phonon renormalization is partially suppressed. This explains the superlattice Bragg peaks observed at low temperatures and ''Kohn-like'' anomalies in the ..sigma../sub 1/ phonon branch of NbSe/sub 2/.
Date: January 1, 1977
Creator: Das, S G; Sinha, S K & Wakabayashi, N
Partner: UNT Libraries Government Documents Department

Measurement of vector meson and direct photon production at large transverse momentum at the CERN ISR. [Cross section]

Description: The production at large transverse momentum of low mass electron pairs was investigated at the CERN Intersecting Storage Rings using lithium/xenon transition radiation detectors and liquid argon calorimeters. Production of the vector mesons rho/sup 0/, ..omega../sup 0/, and phi was observed with cross sections consistent with the assumptions that rho/sup 0/, ..omega../sup 0/, and ..pi../sup 0/ production are nearly equal at large p/sub t/ and that phi production is suppressed by about an order of magnitude relative to rho/sup 0/ and ..omega../sup 0/ production. The observed low mass virtual photon continuum between masses of 200 and 500 MeV was consistent with estimates of Dalitz decays plus predictions of the vector dominance model. The measured cross section for virtual photon production enabled a limit of (0.5 +- 1.0) percent to be placed on the ratio of direct real photon production to ..pi../sup 0/ production.
Date: January 1, 1978
Creator: Cobb, J H; Iwata, S & Palmer, R B
Partner: UNT Libraries Government Documents Department

Measurements of neutron spectra from 35 MeV deuterons on thick lithium for the FMIT facility

Description: The Fusion Materials Irradiation Test (FMIT) Facility is currently being designed by the Hanford Engineering Development Laboratory (HEDL) at Richland, Washington, USA. This facility will make use of the intense source of high energy neutrons produced by 35 MeV deuterons incident upon a thick liquid lithium target in order to study radiation effects in fusion reactor materials. The experimental aspects and results of measurements of neutron yields and spectra from 35 MeV deuterons on a thick lithium target are described. (MOW)
Date: September 1, 1979
Creator: Johnson, D.L. & Mann, F.M.
Partner: UNT Libraries Government Documents Department

Meson radiative decays. [Review, rates]

Description: The status of decays of the kind V ..-->.. P..gamma.. and P ..-->.. V..gamma..viewed with special emphasis on the work done by the authors in this field. The low experimental value of GAMMA(rho ..-->.. ..pi gamma..) remains the outstanding problem. The lastest preliminary numbers from a Fermi Laboratory experiment go in the right direction but not far enough. 15 references.
Date: April 1, 1979
Creator: Edwards, B.J. & Kamal, A.N.
Partner: UNT Libraries Government Documents Department