Computation of self-consistent 2-D MHD with neutral-beam and bootstrap currents in elongated plasmas (open access)

Computation of self-consistent 2-D MHD with neutral-beam and bootstrap currents in elongated plasmas

The observation of substantial current drive from neutral beam injection (NBI) in TFTR, JET and DIII-D has led to renewed interest in a steady state, non-inductively driven tokamak. The discovery of apparently considerable neoclassical (bootstrap) current in TFTR, makes a steady state device even more attractive since the bootstrap portion of the current could be obtained without additional power input. Motivated by these results, we have developed a code, ACCOME, which self-consistently computes the 2-D MHD equilibrium with the current driven by neutral beams, bootstrap and the electric field. In this paper we first describe some details of the code in the next section and in the subsequent section show some applications to DIII-D and to a possible ITER design.
Date: April 5, 1983
Creator: Devoto, R. S.; Tani, K. & Azumi, M.
Object Type: Article
System: The UNT Digital Library
Literature review of the saturation state of seawater with respect to calcium carbonate and its possible significance for scale formation on OTEC heat exchangers (open access)

Literature review of the saturation state of seawater with respect to calcium carbonate and its possible significance for scale formation on OTEC heat exchangers

An investigation of available data on the saturation state of seawater with respect to calcium carbonate and its possible significance for scale formation on Ocean Thermal Energy Conversion (OTEC) heat exchangers has been carried out. Pertinent oceanographic data is lacking at or near potential OTEC sites for the calculation of the degree of saturation of seawater with respect to calcium carbonate. Consequently, only ''extrapolated'' saturation values can be used. These indicate that near surface seawater is probably supersaturated, with respect to the calcium carbonate phases calcite and aragonite, at all potential OTEC sites. The deep seawater that would be brought to the surface at the potential Atlantic Ocean sites is also likely to be supersaturated with respect to calcium carbonate. The deep seawater at the potential Pacific Ocean sites may be slightly undersaturated. The fact that OTEC heat exchangers will be operating in seawater, which is supersaturated with respect to calcium carbonate, means that if nucleation of calcite or aragonite occurs on the heat exchanger surfaces, significant growth rates of calcium carbonate scale may be expected. The potential for calcium carbonate nucleation is highest at cathodic metal surface locations, which are produced as the result of aluminum corrosion in seawater. …
Date: April 5, 1978
Creator: Morse, J. W.; de Kanel, J. & Craig, Jr., H. L.
Object Type: Report
System: The UNT Digital Library
Powerplant Productivity. Improvement Study: current practices in Illinois utilities towards powerplant productivity. Final report, Project 1, Task 1 (open access)

Powerplant Productivity. Improvement Study: current practices in Illinois utilities towards powerplant productivity. Final report, Project 1, Task 1

Efforts of this task indicate that powerplant productivity is a complex issue that has to take into account economic factors, equipment limitations, and system-loading characteristics as well as external constraints such as regulatory requirements. Among the specific findings are: (1) utilities in Illinois use the industry-wide measures of performance such as capacity factor, availability factor, forced outage rates etc.; equivalent availability as a measure is not in common practice; (2) several unit performance statistics are collected on a routine basis such as the daily unit status, component outage data, monthly production figures etc.; (3) identifying major causes of lost productivity appears to be a relatively simple task, but finding economically and technically acceptable corrective actions are generally more difficult; (4) selection of improvement projects, as well as evaluating their future impacts, is mostly based on operating experience and engineering judgement, with no use of formal analytical/statistical models; (5) there generally is a group in every utility - typically called the power production department - with routine responsibilities for upkeep of unit productivity; and (6) recently the Commonwealth Edison Co. has developed a procedure for utilizing the Edison Electric Institute outage data base for analyzing productivity-related questions at nuclear plants; this …
Date: April 5, 1979
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Solar central receiver prototype heliostat. Interim technical progress report (open access)

Solar central receiver prototype heliostat. Interim technical progress report

The objective of Phase I of this project is to support the Solar Central Receiver Power Plant research, development and demonstration effort by: (1) Establishment of a heliostat design, with associated manufacturing, assembly, installation and maintenance approaches, that, in quantity production will yield significant reductions in capital and operating costs over an assumed 30 year plant lifetime as compared with existing designs. (2) Identification of needs for near term and further research and development in heliostat concept, materials, manufacture, installation, maintenance, and other areas, where successful accomplishment and application would offer significant payoffs in the further reduction of the cost of electrical energy from Solar Central Receiver Power Plants. The Phase I study will define a low-cost heliostat preliminary design and the conceptual design of a heliostat manufacturing/installation plan which will result in low life cycle cost when produced and installed at high rate and large quantities for commercial Solar Central Receiver Power Plants. The study will develop the annualized life cycle cost and the performance of heliostats for a 30 year plant life, for each of three rates of continuous production and installation. The three specified rates are 25,000, 250,000, and 1,000,000 heliostats per year. The analysis of these …
Date: April 5, 1978
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Study of mechanisms of hydrogen diffusion in separation devices. Third annual report, 1979-1980 (open access)

Study of mechanisms of hydrogen diffusion in separation devices. Third annual report, 1979-1980

The main results are in the following three areas: (1) examination of a diffusion model for PdH system, (2) connection between the diffusion model and other physical models, (3) related problems. Advances made during the third year of this project, particularly in understanding the physical model for hydrogen diffusion, make it possible to begin to meet some of the long-range objectives described in the initial proposals of 1977-1978.
Date: April 5, 1980
Creator: Lee, M.H.
Object Type: Report
System: The UNT Digital Library
Power Systems Development Facility Gasification Test Run TC07 (open access)

Power Systems Development Facility Gasification Test Run TC07

This report discusses Test Campaign TC07 of the Kellogg Brown & Root, Inc. (KBR) Transport Reactor train with a Siemens Westinghouse Power Corporation (Siemens Westinghouse) particle filter system at the Power Systems Development Facility (PSDF) located in Wilsonville, Alabama. The Transport Reactor is an advanced circulating fluidized-bed reactor designed to operate as either a combustor or a gasifier using a particulate control device (PCD). The Transport Reactor was operated as a pressurized gasifier during TC07. Prior to TC07, the Transport Reactor was modified to allow operations as an oxygen-blown gasifier. Test Run TC07 was started on December 11, 2001, and the sand circulation tests (TC07A) were completed on December 14, 2001. The coal-feed tests (TC07B-D) were started on January 17, 2002 and completed on April 5, 2002. Due to operational difficulties with the reactor, the unit was taken offline several times. The reactor temperature was varied between 1,700 and 1,780 F at pressures from 200 to 240 psig. In TC07, 679 hours of solid circulation and 442 hours of coal feed, 398 hours with PRB coal and 44 hours with coal from the Calumet mine, and 33 hours of coke breeze feed were attained. Reactor operations were problematic due to …
Date: April 5, 2002
Creator: Southern Company Services
Object Type: Report
System: The UNT Digital Library
Biosynthesis of a Fully Functional Cyclotide inside Living Bacterial Cells (open access)

Biosynthesis of a Fully Functional Cyclotide inside Living Bacterial Cells

The cyclotide MCoTI-II is a powerful trypsin inhibitor recently isolated from the seeds of Momordica cochinchinensis, a plant member of cucurbitaceae family. We report for the first time the in vivo biosynthesis of natively-folded MCoTI-II inside live E. coli cells. Our biomimetic approach involves the intracellular backbone cyclization of a linear cyclotide-intein fusion precursor mediated by a modified protein splicing domain. The cyclized peptide then spontaneously folds into its native conformation. The use of genetically engineered E. coli cells containing mutations in the glutathione and thioredoxin reductase genes considerably improves the production of folded MCoTI-II in vivo. Biochemical and structural characterization of the recombinant MCoTI-II confirmed its identity. Biosynthetic access to correctly-folded cyclotides allows the possibility of generating cell-based combinatorial libraries that can be screened inside living cells for their ability to modulate or inhibit cellular processes.
Date: April 5, 2007
Creator: Camarero, J A; Kimura, R H; Woo, Y; Cantor, J & Shekhtman, A
Object Type: Article
System: The UNT Digital Library
Protein Microarrays--Without a Trace (open access)

Protein Microarrays--Without a Trace

Many experimental approaches in biology and biophysics, as well as applications in diagnosis and drug discovery, require proteins to be immobilized on solid supports. Protein microarrays, for example, provide a high-throughput format to study biomolecular interactions. The technique employed for protein immobilization is a key to the success of these applications. Recent biochemical developments are allowing, for the first time, the selective and traceless immobilization of proteins generated by cell-free systems without the need for purification and/or reconcentration prior to the immobilization step.
Date: April 5, 2007
Creator: Camarero, J A
Object Type: Article
System: The UNT Digital Library
Who Owns Renewable Energy Certificates? An Exploration of PolicyOptions and Practice (open access)

Who Owns Renewable Energy Certificates? An Exploration of PolicyOptions and Practice

Renewable energy certificates (RECs) represent the bundle of information that describes the characteristics of renewable electricity generation, and may be (and increasingly are) sold separately from the underlying electricity itself. RECs are a relatively new phenomenon, emerging as a tradable commodity in voluntary markets in the late 1990s, and gaining strength as a means of compliance with various state policy requirements affecting renewable generation in the early 2000s (Holt and Bird 2005). Twenty states and Washington, D.C. now have mandatory renewables portfolio standard (RPS) obligations, and most of these may be satisfied by owning and retiring RECs. Many states also have fuel source and emissions disclosure requirements, for which RECs are useful. Even where state policy does not allow unbundled and fully tradable RECs to meet these requirements, RECs may still be used as an accounting and verification tool (REC tracking systems are in place or under development in many regions of the U.S.). These applications, plus REC trading activity in support of voluntary green claims, give rise to potential ''double counting'' to the extent that the purchaser of the RECs and the purchaser of the underlying electricity both make claims to the renewable energy attributes of the facility in …
Date: April 5, 2006
Creator: Holt, Edward A.; Wiser, Ryan & Bolinger, Mark
Object Type: Report
System: The UNT Digital Library
Quadratic function approaching method for magnetotelluric soundingdata inversion (open access)

Quadratic function approaching method for magnetotelluric soundingdata inversion

The quadratic function approaching method (QFAM) is introduced for magnetotelluric sounding (MT) data inversion. The method takes the advantage of that quadratic function has single extreme value, which avoids leading to an inversion solution for local minimum and ensures the solution for global minimization of an objective function. The method does not need calculation of sensitivity matrix and not require a strict initial earth model. Examples for synthetic data and field measurement data indicate that the proposed inversion method is effective.
Date: April 5, 2004
Creator: Liangjun, Yan; Wenbao, Hu & Zhang, Keni
Object Type: Article
System: The UNT Digital Library
Melting Sequence of Quarkonia (open access)

Melting Sequence of Quarkonia

In this talk I discuss what we can learn about quarkonium dissociation from lattice-potential based models, and summarize the current understanding of lattice data on quarkonium.
Date: April 5, 2008
Creator: Mocsy,A.
Object Type: Article
System: The UNT Digital Library
Simulations of Fracture and Fragmentation of Geologic Materials using Combined FEM/DEM/SPH Analysis (open access)

Simulations of Fracture and Fragmentation of Geologic Materials using Combined FEM/DEM/SPH Analysis

An overview of the Lawrence Discrete Element Code (LDEC) is presented, and results from a study investigating the effect of explosive and impact loading on geologic materials using the Livermore Distinct Element Code (LDEC) are detailed. LDEC was initially developed to simulate tunnels and other structures in jointed rock masses using large numbers of polyhedral blocks. Many geophysical applications, such as projectile penetration into rock, concrete targets, and boulder fields, require a combination of continuum and discrete methods in order to predict the formation and interaction of the fragments produced. In an effort to model this class of problems, LDEC now includes implementations of Cosserat point theory and cohesive elements. This approach directly simulates the transition from continuum to discontinuum behavior, thereby allowing for dynamic fracture within a combined finite element/discrete element framework. In addition, a Smooth Particle Hydrodynamics (SPH) capability has been incorporated into LDEC, permitting the simulation of fluid-structure interaction. We will present results from a study of detonation-induced fracture and fragmentation of geologic media surrounding a tunnel using LDEC.
Date: April 5, 2007
Creator: Morris, J. P. & Johnson, S. M.
Object Type: Article
System: The UNT Digital Library
Imaging at high spatial resolution: Soft x-ray microscopy to 15nm (open access)

Imaging at high spatial resolution: Soft x-ray microscopy to 15nm

Soft x-ray microscopy has now achieved 15 nm spatial resolution with new zone plates and bending magnet radiation. Combined with elemental sensitivity and flexible sample environment (applied magnetic or electric fields, wet samples, windows, overcoatings) this emerges as a valuable tool for nanoscience and nanotechnology, complimenting common electron and scanning tip microscopies. In this presentation we describe recent advances in spatial resolution, expectations for the near future, and applications to magnetic materials, bio-tomography, etc.
Date: April 5, 2006
Creator: Attwood, D.; Chao, W.; Anderson, E.; Liddle, J. A.; Harteneck, B.; Fischer, P. et al.
Object Type: Article
System: The UNT Digital Library
The age of the martian meteorite Northwest Africa 1195 and the differentiation history of the shergottites (open access)

The age of the martian meteorite Northwest Africa 1195 and the differentiation history of the shergottites

Samarium-neodymium isotopic analyses of unleached and acid-leached mineral fractions from the recently identified olivine-bearing shergottite Northwest Africa 1195 yield a crystallization age of 348 {+-} 19 Ma and an {var_epsilon}{sub Nd}{sup 143} value of +40.1 {+-} 1.3. Maskelynite fractions do not lie on the Sm-Nd isochron and appear to contain a martian surface component with low {sup 147}Sm/{sup 144}Nd and {sup 143}Nd/{sup 144}Nd ratios that was added during shock. The Rb-Sr system is disturbed and does not yield an isochron. Terrestrial Sr appears to have affected all of the mineral fractions, although a maximum initial {sup 87}Sr/{sup 86}Sr ratio of 0.701614 {+-} 16 is estimated by passing a 348 Ma reference isochron through the maskelynite fraction that is least affected by contamination. The high initial {var_epsilon}{sub Nd}{sup 143} value and the low initial {sup 87}Sr/{sup 86}Sr ratio, combined with the geologically young crystallization age, indicate that Northwest Africa 1195 is derived from a source region characterized by a long-term incompatible element depletion. The age and initial Sr and Nd isotopic compositions of Northwest Africa 1195 are very similar to those of Queen Alexandra Range 94201, indicating these samples were derived from source regions with nearly identical Sr-Nd isotopic systematics. These …
Date: April 5, 2007
Creator: Symes, S; Borg, L; Shearer, C & Irving, A
Object Type: Article
System: The UNT Digital Library
Simulation of Flow and Transport at the Micro (Pore) Scale (open access)

Simulation of Flow and Transport at the Micro (Pore) Scale

An important problem in porous media involves the ability of micron and submicron-sized biological particles such as viruses or bacteria to move in groundwater systems through geologic media characterized by rock or mixed gravel, clay and sand materials. Current simulation capabilities require properly upscaled (continuum) models of colloidal filtration and adsorption to augment existing theories of fluid flow and chemical transport. Practical models typically address flow and transport behavior in aquifers over distances of 1 to 10 km where, for example, fluid momentum balance is governed by the simple Darcy's Law as a function of a pressure gradient, elevation gradient and a medium-dependent permeability parameter. In addition to fluid advection, there are multiple transport processes occurring in these systems including diffusion, dispersion and chemical interactions with solids or other aqueous chemical species. Particle transport is typically modeled in the same way as dissolved species, except that additional loss terms are incorporated to model particle filtration (physical interception), adsorption (chemical interception) and inactivation. Proper resolution of these processes at the porous medium continuum scale constitutes an important closure problem in subsurface science. We present a new simulation capability based on enabling technologies developed for microfluidics applications to model transport of colloidal-sized …
Date: April 5, 2007
Creator: Trebotich, D & Miller, G H
Object Type: Article
System: The UNT Digital Library
A systematic study of J/psi suppression in cold nuclear matter (open access)

A systematic study of J/psi suppression in cold nuclear matter

Understanding the effects of cold nuclear matter on J/psi production is a key requirement in order to interpret the J/psi suppression reported in heavy-ion collisions. Based on a Glauber model, the J/psi-nucleon inelastic cross section is determined from a statistical analysis of J/psi world data on nuclear targets. The global fit of all data gives sigmaJ/psiN = 3.4 +/- 0.2 mb, significantly smaller than previous estimates, yet the chi2 of the fit is pretty large, chi2/ndf = 1.5. A similar value, sigmaJ/psiN = 3.5 +/- 0.2 +/- 1.7 mb, is obtained when the De Florian-Sassot modifications of the nuclear parton densities are included in the analysis, although we emphasize that the present uncertainties on gluon (anti)shadowing do not allow for a precise determination of sigmaJ/psiN. Finally, the possible energy dependence of the J/psi-nucleon inelastic cross section is investigated within this framework. No significant energy dependence of the J/psi-N interaction is observed.
Date: April 5, 2008
Creator: Arleo, Francois & Tram, Vi-Nham
Object Type: Article
System: The UNT Digital Library
Prototype Performance of Novel Muon Telescope Detector at STAR. (open access)

Prototype Performance of Novel Muon Telescope Detector at STAR.

Research on a large-area, cost-effective Muon Telescope Detector (MTD) has been carried out for RHIC and for next generation detectors at future QCD Lab. We utilize state-of-the-art multi-gap resistive plate chambers with large modules and long readout strips in detector design. The results from cosmic ray and beam test will be presented to address intrinsic timing and spatial resolution for a Long-MRPC. The prototype performance of a novel muon telescope detector at STAR will be reported, including muon identification capability, timing and spatial resolution.
Date: April 5, 2008
Creator: Ruan,L.
Object Type: Article
System: The UNT Digital Library
Electron electric dipole moment experiment using electric-fieldquantized slow cesium atoms (open access)

Electron electric dipole moment experiment using electric-fieldquantized slow cesium atoms

A proof-of-principle electron electric dipole moment (e-EDM)experiment using slow cesium atoms, nulled magnetic fields, and electricfield quantization has been performed. With the ambient magnetic fieldsseen by the atoms reduced to less than 200 pT, an electric field of 6MV/m lifts the degeneracy between states of unequal lbar mF rbar and,along with the low (approximately 3 m/s) velocity, suppresses thesystematic effect from the motional magnetic field. The low velocity andsmall residual magnetic field have made it possible to induce transitionsbetween states and to perform state preparation, analysis, and detectionin regions free of applied static magnetic and electric fields. Thisexperiment demonstrates techniques that may be used to improve the e-EDMlimit by two orders of magnitude, but it is not in itself a sensitivee-EDM search, mostly due to limitations of the laser system.
Date: April 5, 2007
Creator: Amini, Jason M.; Munger Jr., Charles T. & Gould, Harvey.
Object Type: Article
System: The UNT Digital Library
Motif based Hessian matrixfor ab initio geometry optimization ofnanostructures (open access)

Motif based Hessian matrixfor ab initio geometry optimization ofnanostructures

A simple method to estimate the atomic degree Hessian matrixof a nanosystem is presented. The estimated Hessian matrix, based on themotif decomposition of the nanosystem, can be used to accelerate abinitio atomic relaxations with speedups of 2 to 4 depending on the sizeof the system. In addition, the programing implementation for using thismethod in a standard ab initio package is trivial.
Date: April 5, 2006
Creator: Zhao, Zhengji; Wang, Lin-Wang & Meza, Juan
Object Type: Article
System: The UNT Digital Library
Solid Nitrogen at Extreme Conditions of High Pressure and Temperature (open access)

Solid Nitrogen at Extreme Conditions of High Pressure and Temperature

We review the phase diagram of nitrogen in a wide pressure and temperature range. Recent optical and x-ray diffraction studies at pressures up to 300 GPa and temperatures in excess of 1000 K have provided a wealth of information on the transformation of molecular nitrogen to a nonmolecular (polymeric) semiconducting and two new molecular phases. These newly found phases have very large stability (metastability) range. Moreover, two new molecular phases have considerably different orientational order from the previously known phases. In the iota phase (unlike most of other known molecular phases), N{sub 2} molecules are orientationally equivalent. The nitrogen molecules in the theta phase might be associated into larger aggregates, which is in line with theoretical predictions on polyatomic nitrogen.
Date: April 5, 2004
Creator: Goncharov, A. & Gregoryanz, E.
Object Type: Book
System: The UNT Digital Library
Aerial radiometric and magnetic survey: Bozeman National Topographic Map, Montana (open access)

Aerial radiometric and magnetic survey: Bozeman National Topographic Map, Montana

The results of analyses of the airborne gamma radiation and total magnetic field survey flown for the region identified as the Bozeman National Topographic Map NL12-8 are presented in Volume I and II of this report. The airborne data gathered are reduced by ground computer facilities to yield profile plots of the basic uranium, thorium, and potassium equivalent gamma radiation intensities, ratios of these intensities, aircraft altitude above the earth's surface, total gamma ray and earth's magnetic field intensity, correlated as a function of geologic units. The distribution of data within each geologic unit, for all surveyed map lines and tie lines, has been calculated and is included. Two sets of profiled data for each line are included with one set displaying the above-cited data. The second set includes only flight line magnetic field, temperature, pressure, altitude data plus magnetic field data as measured at a base station. A general description of the area, including descriptions of the various geologic units and the corresponding airborne data, is included also.
Date: April 5, 1979
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Raising the acceptance of the AP2-line (open access)

Raising the acceptance of the AP2-line

The 120 GeV Main Ring proton beam collides with the target at the end of the AP-1 line and creates antiprotons and other secondary particles. The AP-2 line transfers the negative particles from the target to the Debuncher. To provide a bigger antiproton stack size in the Accumulator, both the Debuncher as well as the AP-2 line acceptance have to be raised. This is a proposal for the improvement of the AP-2 line acceptance. The first part of the memo presents an acceptance examination of the existing AP-2 line by computer simulation, while the second presents a short proposal for aperture corrections. The computer program TURTLE was used to trace antiprotons through the AP-2 line without taking into account other negative charged particles. Betatron functions were obtained from the output of the SYNCH computer program. The SYNCH program was also used to check the dispersion match between the AP-2 line and the Debuncher. 3 refs., 6 figs., 5 tabs.
Date: April 5, 1989
Creator: Trbojevic, D.
Object Type: Report
System: The UNT Digital Library
Nuclear chemistry counting facilities: requirements definition (open access)

Nuclear chemistry counting facilities: requirements definition

In an effort to upgrade outdated instrumentation and to take advantage of current and imminent technologies the Nuclear Chemistry Division at Lawrence Livermore Laboratory is about to undertake a major upgrade of their low level radiation counting and analysis facilities. It is expected that such a project will make a more coordinated data acquisition and data processing system, reduce manual data handling operations and speed up data processing throughput. Before taking on a systems design it is appropriate to establish a definition of the requirements of the facilities. This report examines why such a project is necessary in the context of the current and projected operations, needs, problems, risks and costs. The authors also address a functional specification as a prelude to a system design and the design constraints implicit in the systems implementation. Technical, operational and economic assessments establish necessary boundary conditions for this discussion. This report also establishes the environment in which the requirements definition may be considered valid. The validity of these analyses is contingent on known and projected technical, scientific and political conditions.
Date: April 5, 1979
Creator: O'Brien, D.W. & Baker, J.
Object Type: Report
System: The UNT Digital Library
Fusion-breeder-reactor design studies (open access)

Fusion-breeder-reactor design studies

Studies of the technical and economic feasibility of producing fissile fuel in tandem mirrors and in tokamaks for use in fission reactors are presented. Fission-suppressed fusion breeders promise unusually good safety features and can provide make-up fuel for 11 to 18 LWRs of equal nuclear power depending on the fuel cycle. The increased revenues from sales of both electricity and fissile material might allow the commercial application of fusion technology significantly earlier than would be possible with electricity production from fusion alone. Fast-fission designs might allow a fusion reactor with a smaller fusion power and lower Q value to be economical and thus make this application of fusion even earlier. A demonstration reactor with a fusion power of 400 MW could produce 600 kg of fissile material per year at a capacity factor of 50%. The critical issues, for which small scale experiments are either being carried out or planned, are: (1) material compatibility, (2) beryllium feasibility, (3) MHD effects, and (4) pyrochemical reprocessing.
Date: April 5, 1983
Creator: Moir, R. W.; Lee, J. D. & Coops, M. S.
Object Type: Article
System: The UNT Digital Library