[en] Rapidly rotating neutron stars and the accretion disks around super-massive black holes at the nuclei of active galaxies were studied relativistically. The light curves of radiation from antipodal caps of rapidly rotating neutron stars were calculated with and without gravity. The light curves are found to depend strongly on the rotation speed and on the emission spectrum, and could become quite sharp. Gravity generally flattens the light curves; however, it does so less for rapidly rotating neutrons stars and can never flatten them enough to explain the absence of pulsations from low-mass x ray binary (LMXB's), the putative progenitors of millisecond pulsars. Spectral analysis of radiation from rapidly rotating neutron stars must take rotation effects into account; in LMXB's, pulses are expected to be sharpest for the hardest x rays. Line profiles for a Keplerian disk are calcuated, including relativistic effects. An excellent fit was found between the resulting double-peaked, asymmetric profiles and the observed H alpha line of an active galactic nucleus (AGN), Arp 102B. It was concluded that the line profile of Arp 102B shows the most convincing direct kinematic evidence for rotation in any AGN. A self-consistent model of a line-emitting accretion disk is presented which accounts for the observed properties of a small class of AGN's. The prime objects are Arp 102B and 3C 390.3, broad-line radio galaxies with double-peaked emission lines. The combination of ion torus and thin disk accounts for several additional properties of Arp 102B and 3C 390.3. The far-infrared peaks at 25 microns are in agreement with the predicted synchrotron self-absorption turnover for an ion torus. The outer radius of the hot ion torus, which is identified with the measured inner radius of the line-emitting thin disk, is consistent with the theoretical location of the onset of the Lightman-Eardley instability

[en] A photometrically calibrated 0.4 m normal incidence euv monochromator (wavelength range 300 A to 1700 A) has been utilized to study impurities spectroscopically in the Alcator A Tokamak. Light impurities (O, N, C) and heavy impurities (Mo, Fe, Cr) in Alcator A have been identified by the euv emissions from these ions. Besides temporal profiles of all the impurities, the spatial profiles of O VI, O V and N V have also been obtained by tilting the monochromator to scan the plasma. The effects of wall temperature on light impurity concentrations in the Alcator A Tokamak have been measured spectroscopically. The results show that a temperature reduction decreases the influx of oxygen by a factor of 4 approx. 5 in normal tokamak operation when the wall temperature dropped from 450⁰K to 77⁰K but does not affect the other light impurities

[en] STREAM is an emergency response code that predicts downstream pollutant concentrations for releases from the SRS area to the Savannah River. The STREAM code uses an algebraic equation to approximate the solution of the one dimensional advective transport differential equation. This approach generates spurious oscillations in the concentration profile when modeling long duration releases. To improve the capability of the STREAM code to model long-term releases, its calculation module was replaced by the WASP5 code. WASP5 is a US EPA water quality analysis program that simulates one-dimensional pollutant transport through surface water. Test cases were performed to compare the revised version of STREAM with the existing version. For continuous releases, results predicted by the revised STREAM code agree with physical expectations. The WASP5 code was benchmarked with the US EPA 1990 and 1991 dye tracer studies, in which the transport of the dye was measured from its release at the New Savannah Bluff Lock and Dam downstream to Savannah. The peak concentrations predicted by the WASP5 agreed with the measurements within ±20.0%. The transport times of the dye concentration peak predicted by the WASP5 agreed with the measurements within ±3.6%. These benchmarking results demonstrate that STREAM should be capable of accurately modeling releases from SRS outfalls

No abstract available

[en] A systemic study of the deposition processes and magnetic properties for the Sm-Co film system has been carried out. Films of Sm-Co system with various magnetic anisotropies have been synthesized through sputter deposition in both crystalline and amorphous phases. The origins of various anisotropies have been studied. Thermalized sputter deposition process control was used to synthesize Fe enriched Sm-Co films with rhombohedral Th₂Zn₁₇ type structure. The film exhibited unusually strong textures with the crystallographic c axes of the crystallites aligned in the film plane. A large anisotropy was resulted with easy axis in the film plane. A well defined and large in-the-film-plane anisotropy of exceptionally high value of 3.3 x 10⁶ erg/cm³ has been obtained in the amorphous SmCo films by applying a magnetic field in the film plane during deposition. It was found that the in-the-film-plane anisotropy depended essentially on the applied field and Sm concentration. For films not synthesized through thermallized sputtering, the easy axis of the film could reoriented. A perpendicular anisotropy was also presented in the film synthesized through thermallized sputtering deposition. A large in-plane anisotropy was obtained in films deposited above ambient temperatures. It was concluded that the surface induced short range ordering was the origin of the in-the-film-phase anisotropy observed in amorphous film deposited in the presence of a magnetic field. The formation mechanism was different from that of the short range ordering induced by field annealing. The perpendicular anisotropy was shown to be growth induced. Large in-plane anisotropy in amorphous films was resulted form partial crystallization in the film. Both the formation of growth induced structure and partial crystallization in the film prevented the formation of the pair ordering and decreased in-the-film-plane anisotropy

[en] The Savannah River National Laboratory (SRNL) uses the Lagrangian Particle Dispersion Model (LPDM) in conjunction with the Regional Atmospheric Modeling System as an operational tool for emergency response consequence assessments for the Savannah River Site (SRS). The LPDM is an advanced stochastic atmospheric transport model used to transport and disperse passive tracers subject to the meteorological field generated by RAMS from sources of varying number and shape. The Atmospheric Technologies Group (ATG) of the SRNL is undertaking the task of reviewing documentation and code for LPDM Quality Assurance (QA). The LPDM QA task will include a model technical description, computer coding descriptions, model applications, and configuration control. This report provides a comprehensive technical description of the LPDM model

[en] A series of tests injecting air into a tank of stagnant water was conducted in June 1980 utilizing the GE Plenum Mixing Test Facility in San Jose, California. The test was concerned with investigating the behavior of air jets at a submerged orifice in water over a wide range of flow rates. The main objective was to improve the basic understanding of gas-liquid phenomena (e.g., leak dynamics, gas bubble agglomeration, etc.) in a simulated tube bundle through visualization. The experimental results from these air-water tests will be used as a guide to help select the leak size for LLTR Series II Test A-4 because air-water system is a good simulation of water-sodium mixture

No abstract available

[en] With the aid of large-scale computer simulations on state-of-the-art supercomputers, the author has carried out a comprehensive study of first-order phase transitions, both static and dynamic critical behavior, as well as various excitations in different three-dimensional classical Heisenberg magnetic models with periodic boundary conditions and only nearest-neighbor interactions. In the Monte Carlo study of finite-size effects on the first-order phase transition in the simple-cubic classical Heisenberg ferromagnet, the author found that the current Fisher-Privman theory failed at temperatures close to criticality and/or for small systems. Explicit scaling functions were rederived for the longitudinal magnetization and susceptibility under a new phenomenological assumption. The predictions were in excellent agreement with Monte Carlo simulations. Using both recently developed cluster algorithm and histogram methods, a high-resolution Monte Carlo study of static critical properties of the simple-cubic and body-centered-cubic ferromagnets was performed. From finite-size scaling behavior of various thermodynamic quantities, the inverse critical temperatures were estimated to be 0.693035(37) for the simple-cubic system and 0.486798(12) for the body-centered-cubic system. Estimated static critical exponents for both systems agreed with each other within their respective error bars, and the mean estimates ν = 0.7048(30) and γ = 1.3873(85) were also in excellent agreement with field theoretic predictions. Using spin dynamics methods, extensive simulations were carried out of the dynamic critical behavior of the body-centered-cubic ferromagnet. The space-and time-displaced spin-spin correlation functions and their space-time Fourier transforms were calculated to determine neutron- scattering functions

[en] STREAM II-V4 is the aqueous transport module currently used by the Savannah River Site emergency response Weather Information Display (WIND) system. The transport model of the Water Quality Analysis Simulation Program (WASP) was used by STREAM II to perform contaminant transport calculations. WASP5 is a US Environmental Protection Agency (EPA) water quality analysis program that simulates contaminant transport and fate through surface water. STREAM II-V4 predicts peak concentration and peak concentration arrival time at downstream locations for releases from the SRS facilities to the Savannah River. The input flows for STREAM II-V4 are derived from the historical flow records measured by the United States Geological Survey (USGS). The stream flow for STREAM II-V4 is fixed and the flow only varies with the month in which the releases are taking place. Therefore, the effects of flow surge due to a severe storm are not accounted for by STREAM II-V4. STREAM II-V4 has been revised to account for the effects of a storm event. The steps used in this method are: (1) generate rainfall hyetographs as a function of total rainfall in inches (or millimeters) and rainfall duration in hours; (2) generate watershed runoff flow based on the rainfall hyetographs from step 1; (3) calculate the variation of stream segment volume (cross section) as a function of flow from step 2; (4) implement the results from steps 2 and 3 into the STREAM II model. The revised model (STREAM II-V5) will find the proper stream inlet flow based on the total rainfall and rainfall duration as input by the user. STREAM II-V5 adjusts the stream segment volumes (cross sections) based on the stream inlet flow. The rainfall based stream flow and the adjusted stream segment volumes are then used for contaminant transport calculations.