CERN Document Server

We examine the observable properties of simulated barred galaxies including radial mass profiles, edge-on structure and kinematics, bar lengths and pattern speed evolution for detailed comparison to real systems. We have run several simulations in which bars are created through inherent instabilities in self-consistent simulations of a realistic disc+halo galaxy model with a disc-dominated, flat rotation curve. These simulations were run at high (N=20M particles) and low (N=500K) resolution to test numerical convergence. We determine the pattern speeds in simulations directly from the phase angle of the bar versus time and the Tremaine-Weinberg method. Fundamental dynamics do not change between the high and low resolution, suggesting that convergence has been reached in this case. We find the higher resolution is needed to simulate structural and kinematic properties accurately. The edge-on view of the ...

Energy Technology Data Exchange (ETDEWEB)

A radial-flow type internally oil-cooled oil-filled cable has been developed. This system is characterized in that the oil flows radially through the paper insulation. The thermal resistance of the insulation is equivalently decreased by the radial-flow. The decreased thermal resistance as well as the cooling effect of the oil flow in the central oil duct and the outer oil duct under an aluminum sheath increase the current capacity. A calculation method of cooling characteristics is introduced. The stability of the cable and accessories was confirmed through initial electrical tests and a long-term field test.

Energy Technology Data Exchange (ETDEWEB)

In this paper, a new design methodology for determining the size, location, type and number of capacitors to be placed on a radial distribution system is presented. The objective is to minimize the peak power losses and the energy losses in the distribution system considering the capacitor cost. A sensitivity analysis based method is used to select the candidate locations for the capacitors. A new optimization method using a Genetic Algorithm is proposed to determine the optimal selection of capacitors. Test results have been presented along with the discussion of the algorithm.

International Nuclear Information System (INIS)

The energy deposited by the passage of a single, energetic, heavy-ion through a semiconductor produces dense electron-hole (eh) pair concentrations near the ion trajectory. The size, shape, and charge density of an ion track represent critical parameters for many models of single event phenomena. The authors describe the design and uses of possible semiconductor test structures for measuring the initial radial distribution of charge and subsequent charge transport in a high energy, heavy-ion track. Numerical simulations show how the test structure can resolve different radial distributions of charge within an ion track. The test structure simulations also show the importance of accurately representing ion track structure in single event effects simulations.

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

The present paper describes the application of the commercial CFD-code FLUENT 6.1 to the numerical simulation of the flow field in a high specific speed radial fan. Two-dimensional as well as three-dimensional computations are performed using the steady 'Frozen-Rotor method' as well as the unsteady 'Sliding-Mesh method'. The predicted performance curves of the radial fan are compared with the results obtained from measurements on a test stand. Due to the relatively low computation times, the 'Frozen-Rotor method' can be used routinely for design purposes. The results of this approach can be improved if the leakage flow through the gap between the inlet nozzle and the impeller is taken into account. (orig.)

International Nuclear Information System (INIS)

A sample of 41 radio-galaxies with 13.0<=msub(corr)<=15.5 has been analyzed to test the angular redshift anisotropy discovered on Sc I galaxies by Rubin, Rubin and Ford (1973). The sample does not present their anisotropy but contains an even more curious distribution of radial velocities which suggests that the Rubin-Ford effect results from an anomalous redshift of light when it travels through clusters of galaxies. (Auth.).

Science.gov (United States)

Radial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly

International Nuclear Information System (INIS)

In the frame of the European Technology R and D programme for International thermonuclear experimental reactor (ITER) and in the area of high heat flux plasma facing components (HHFC), representative small-scale mock-ups were manufactured and tested to compare different concepts and joining technologies (i.e. active brazing, hot isostatic pressing (HIPping), diffusion bonding, etc.). On the basis of the results obtained by thermal fatigue tests, the monoblock concept resulted to be the most robust one, particularly when the HIPping manufacturing technology is used. Within this programme, ENEA developed an alternative technique for manufacturing plasma-facing components with a monoblock geometry of the ITER machine. The basic idea of this technique, named hot radial pressing (HRP), is to perform a radial diffusion bonding between the cooling tube and the armour tile by pressurising the internal tube only ...

Energy Technology Data Exchange (ETDEWEB)

The general relativistic version is developed for Robertson's discussion of the Poynting-Robertson effect that he based on special relativity and Newtonian gravity for point radiation sources like stars. The general relativistic model uses a test radiation field of photons in outward radial motion with zero angular momentum in the equatorial plane of the exterior Schwarzschild or Kerr spacetime.

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

This report covers application of Argonne National Laboratory`s (ANL`s) computer codes to simulation and analysis of components of the magnetohydrodynamic (MHD) power train system at the Component Development and Integration Facility (CDIF). Major components of the system include a 50-MWt coal-fired, two-stage combustor and an MHD channel. The combustor, designed and built by TRW, includes a deswirl section between the first and the second-stage combustor and a converging nozzle following the second-stage combustor, which connects to the MHD channel. ANL used computer codes to simulate and analyze flow characteristics in various components of the MHD system. The first-stage swirl combustor was deemed a mature technology and, therefore, was not included in the computer simulation. Several versions of the ICOMFLO computer code were used for the deswirl section and second-stage combustor. The MGMHD code, upgraded with a slag current leakage submodel, was used for the ...

Energy Technology Data Exchange (ETDEWEB)

A study on development of magnetic drive packless valves for commercial purpose showed the results as follows; 1. Study on the radial rays effecting to the permanent magnets -Measurement of the strength of Nd-magnets according to irradiation of radial rays. 2. Effects of temperature on the magnetic driving device -Temperature dependency of the Nd-casting magnets. -Effects of temperature on the heat releasing fins of high-temperature valve. 3. Optimization of torque -Arranging method of permanent magnets -Measuring method and results of torque. 4. Design, manufacture and test for the pressure-resisting structure of magnetic power transmitting device -Calculation and design for the flat circular plates under pressure of the magnetic power transmitting device -Design, manufacture and test for the pressure-resisting structure of magnetic power transmitting device -Comparison of the characteristics between ...

British Library Electronic Table of Contents (United Kingdom)

Abstract We suggest a simple scheme for automatically determining the width parameter of smearing methods of the Brillouin zone integration in electronic structure calculation. The scheme retains one free parameter that at any time can be eliminated by choosing a denser k-space mesh until the desired accuracy is obtained. The tests are carried out in the context of Methfessel-Paxton smearing. This adaptive Gaussian smearing (AGS) is easily implemented, variational with respect to partial occupancies and free from spurious occupancies that are negative or larger than one. Its convergence properties are similar to those obtained with the modified tetrahedron method for energy resolution of -0.1 meV. 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011

International Nuclear Information System (INIS)

A method of using gamma radiation to determine the density and phase distribution in two-phase flows in pipes is described. Three collimated beams of radiation that pass through a pipe cross-section at different radial positions are used. A theory and computer program used to relate the measured attenuation of these beams to a three-parameter model of the phase distribution and to the average density and void fraction are discussed. Data obtained during both static and dynamic verification experiments using Lucite inserts are presented, as well as the results of several tests done in high pressure, steam-water flows.

Science.gov (United States)

Using an expanded nuclear data base, the transmutation of PCA, AMCR33 (a reduced activation austenitic steel), HT-9, Rafer2 (a reduced activation ferritic steel), V-15%Cr-5%Ti alloy, and SiAlON (a ceramic) were calculated for two positions in the Fast Flux Test Facility (FFTF), three positions in the High Flux Isotope Reactor (HFIR), and the first wall position of both the STARFIRE and MARS conceptual fusion reactors. The peripheral test (PTP) position, and to a lesser extent the radial beryllium (RB) position, of HFIR show significant transmutations which are often in the opposite direction to the transmutations in the fusion conceptual designs. The positions in FFTF, as well as the hafnium covered location in the HFIR RB position show relative minor transmutations.

International Nuclear Information System (INIS)

The Cycle 8A static tests conducted in the Fast Flux Test Facility (FFTF) during 1986 have resulted in the separation of various feedback reactivity components. These feedback components, described by closed-form equations depending only on the reactor temperature field, can be regarded as database for the validation and/or calibration of feedback mechanistic models. The SASSYS safety analysis code contains the most developed feedback reactivity models and was selected for the comparison study between database and mechanistic calculations for the FFTF. Although detailed feedback models for control rod repositioning and core radial expansion/bowing exist, only the simple models were available in SASSYS at the time of this study. The results are described in this paper.

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

International Nuclear Information System (INIS)

The applicability of Broyden's second method for accelerating the convergence of self-consistent electronic-structure calculations based on the linearized augmented-plane-wave method is discussed in terms of a W(001) surface calculation. It is found that its use results in a significant improvement in the convergence of the calculation, and based on this it is concluded that its use should increase the size of the systems for which such calculations are feasible.

Energy Technology Data Exchange (ETDEWEB)

Optimal capacitor placement determines the size, type, and location of capacitors to be installed on a radial distribution feeder that will reduce peak power and energy losses while minimizing the costs of investment and installation of the capacitor banks. This paper describes a sensitivity-based optimal placement of capacitors that employs a new load characterization scheme using a voltage-current-angle-logger. The proposed method allows modeling of loads of different power factors for different portions of the distribution feeder. The optimal solution is obtained by testing various combinations of capacitor banks (based on the smallest bank size specified by the user) and candidate nodes along the distribution feeder, and calculating the resultant savings. In order to reduce solution time, the candidate nodes are ranked according to their sensitivity factors. The highest ranking nodes are considered first in the optimization process. At a ...

Scientific Electronic Library Online (English)

Abstract in english In this work the air flow in a furnace was computationally investigated. The furnace, for which experimental test data are available, is composed of a movable block burner connected to a cylindrical combustion chamber by a conical quarl. The apertures between the movable and the fixed blocks of the burner determine the ratio of the tangential to the radial air streams supplied to the furnace. Three different positions of the movable blocks were studied at this time. A thr (more) ee-dimensional investigation was performed by means of the finite volume method. The numerical grid was developed by the multiblock technique. The turbulence phenomenon was addressed by the RNG k-epsilon model. Profiles of the axial, tangential and radial velocities in the combustion chamber were outlined. The map of the predicted axial velocity in the combustion chamber was compared with a map of the experimental axial velocity. ...

International Nuclear Information System (INIS)

The facilities in the Institute for Nuclear Research at Pitesti allow the testing, handling and examination of nuclear fuel and irradiated materials. The most important facilities are the TRIGA Steady State Research and Material Test Reactor and the Post-Irradiation Examination Laboratory (PIEL). The purpose of this work is to determine by post-irradiation examination, the behavior of CANDU fuel, irradiated in 14 MW TRIGA reactor. The fuel was irradiated in power ramp conditions. The results of post-irradiation examination are: - Visual inspection and photography of the outer appearance of sheath; - Profilometry (diameter, bending, ovality) and length measuring; - Determination of axial and radial distribution of the fusion products activity by gamma scanning and tomography; - Microstructural characterization by metallographic and ceramographic analyzes; - Mechanical properties determination. The data obtained from the ...

CERN Document Server

We investigate weak lensing by large-scale structure using ray tracing through N-body simulations. Photon trajectories are followed through high resolution simulations of structure formation to make simulated maps of shear and convergence on the sky. Tests with varying numerical parameters are used to calibrate the accuracy of computed lensing statistics on angular scales from about 1 arcminute to a few degrees. Various aspects of the weak lensing approximation are also tested. For fields a few degrees on a side the shear power spectrum is almost entirely in the nonlinear regime and agrees well with nonlinear analytical predictions. Sampling fluctuations in power spectrum estimates are investigated by comparing several ray tracing realizations of a given model. For survey areas smaller than a degree on a side the main source of scatter is nonlinear coupling to modes larger than the survey. We develop a method which uses ...

Science.gov (United States)

Examination of measurement invariance provides a powerful method to evaluate the hypothesis that the same set of psychological constructs underlies a set of test scores in different populations. If measurement invariance is observed, then the same psychological meaning can be ascribed to scores in both populations. In this study, the measurement model including core and supplementary subtests of the Wechsler Adult Intelligence Scale-Fourth edition (WAIS-IV) were compared across the U.S. and Canadian standardization samples. Populations were compared on the 15 subtest version of the test in people aged 70 and younger and on the 12 subtest version in people aged 70 or older. Results indicated that a slightly modified version of the four-factor model reported in the WAIS-IV technical manual provided the best fit in both populations and in both age groups. The null hypothesis of measurement invariance across populations was not rejected, and the ...

Energy Technology Data Exchange (ETDEWEB)

The durability of ball bearings, 32-mm- and 45-mm-bore, with a retainer or glass cloth-polytetrafluoroethylene (PTFE) laminate was tested under a high radial load at a speed of 20,000 rpm in LOX or LN2. The retainers were characterized as good self-lubricators because the abrasive glass-cloth fiber tips exposed on the retainer were chemicaly etched away with hydrofluoric acid (HF). During testing, the bearing-cartridge-acceleration was monitored to detect bearing damage. Testing in LOX for about 2.2 hr showed that excellent lubricating conditions were obtained for all bearings. Testing in LN2 for about 5.1 hr detected that the fatigue life of the bearing was about the same as the calculated B10 fatigue life. The HF chemical treatment resulted in a reacted fluoride-oxide material which remained in the etched part of the glass fiber. Several chemical products, particularly MgO, CaO, ...

British Library Electronic Table of Contents (United Kingdom)

The objective of this study is to develop an artificial neural network (ANN) model to predict the thermal conductivity of ethylene glycol-water solutions based on experimentally measured variables. The thermal conductivity of solutions at different concentrations and various temperatures was measured using the cylindrical cell method that physical properties of the solution are being determined fills the annular space between two concentric cylinders. During the experiment, heat flows in the radial direction outwards through the test liquid filled in the annual gap to cooling water. In the steady state, conduction inside the cell was described by the Fourier equation in cylindrical coordinates, with boundary conditions corresponding to heat transfer between the solution and cooling water. ...

Energy Technology Data Exchange (ETDEWEB)

A new test methodology is described which allows access to loading rates that lie between split Hopkinson bar and shock-loading techniques. Gas gun experiments combined with velocity interferometry techniques have been used to experimentally determine the intermediate strain-rate loading behavior of Coors AD995 alumina and Cercom silicon-carbide rods. Graded-density materials have been used as impactors; thereby eliminating the tension states generated by the radial stress components during the loading phase. Results of these experiments demonstrate that the time-dependent stress pulse generated during impact allows an efficient transition from the initial uniaxial strain loading to a uniaxial stress state as the stress pulse propagates through the rod. This allows access to intermediate loading rates over 5 x 10{sup 3}/s to a few times 10{sup 4}/s.

British Library Electronic Table of Contents (United Kingdom)

Sulfur pollution can lead to serious problems in freshwater wetlands, including phosphorus eutrophication and sulfide toxicity. We tested the effects of anaerobic iron-rich groundwater discharge in fens, simulated by iron injection, on two characteristic species (Juncus effusus and Caltha palustris) in a sulfidic environment. Biomass production of C. palustris roots showed an optimum response to the combined addition of iron and sulfide, with highest values at intermediate concentrations of both substances. Iron deficiency apparently occurred at low iron concentrations, while at high iron concentrations, growth was decreased. For J. effusus, in contrast, no toxic effects were found of both iron and sulfide. This could be explained by larger radial oxygen loss (ROL) of J. effusus and could ...

Energy Technology Data Exchange (ETDEWEB)

An IEC-TDG waveform analysis program that can accurately calculate the waveform parameters in waveforms containing much noise as well as waveforms based on the IEC 1083-2 standard was developed in the impulse voltage and current test field. In the conventional curve fitting method, it is difficult to solve the non-linear equation directly when obtaining waveform parameters from the assigned discrete data. An approximate solution method is low in precision. Therefore, the residual between the standardized data and approximate function was calculated for high-speed Fourier transformation. Unrelated components were eliminated from the calculated frequency spectrum to synthesize waveforms. An L-M method is used for analysis. The solution is first tracked by a maximum diving method. If the convergence is judged to have been largely promoted, the method is switched into a Newton method to continue the calculation. The non-linear equation in a curve ...

Science.gov (United States)

High precision, fast computation speed, as well as a good capability of fault tolerant and reconstruction are required more and more for spacecraft attitude determination system. To realize the above requirement, an approach was presented to the synthesis of federated filters using sigma point technique. In this algorithm, the sigma point technique brought the algorithm a high precision, while the federated structure significantly enhanced the filters' capability of multi-rate information fusion, fault tolerance, and system modularity. Within consideration of computation consumption, a simple information-sharing formulation was derived to adapt to the special property of sigma point distribution, and a dynamical information sharing strategy for multi-rate fusion was developed. A numerical simulation example was employed to give the algorithm a test, where the simulated system contained a suit of gyroscopes; a three-axis magnetometer and a sun sensor each had a ...

British Library Electronic Table of Contents (United Kingdom)

In this article we obtain an alternative formulation of the von Mises type conditions for p-max stable laws in terms of generalized log Pareto distributions (glogPds). Relationship between the rate of convergence of extremes and the remainder terms in the von Mises type conditions is investigated. It is shown that the rate of convergence in the von Mises type conditions for p-max stable laws determines the distance of the underlying distribution function from a glogPd.

Science.gov (United States)

Satellite Observations of the Southeast Pacific Intertropical Convergence Zone During 1993-1998, Halpern, D.; Hung, C.-W., Journal of Geophysical Research ? ...

CERN Document Server

We reconsider stochastic convergence analyses of particle swarm optimisation, and point out that previously obtained parameter conditions are not always sufficient to guarantee mean square convergence to a local optimum. We show that stagnation can in fact occur for non-trivial configurations in non-optimal parts of the search space, even for simple functions like SPHERE. The convergence properties of the basic PSO may in these situations be detrimental to the goal of optimisation, to discover a sufficiently good solution within reasonable time. To characterise optimisation ability of algorithms, we suggest the expected first hitting time (FHT), i.e., the time until a search point in the vicinity of the optimum is visited. It is shown that a basic PSO may have infinite expected FHT, while an algorithm introduced here, the Noisy PSO, has finite expected FHT on some functions.

Energy Technology Data Exchange (ETDEWEB)

Location of transmission line faults are traditionally estimated by measuring the apparent impedance from a line terminal to the fault and converting the reactive component of the impedance to line length. None of the methods proposed to date address adequately the problems of fault location on distribution systems that have single or multiphase laterals and/or tapped loads. The research for this dissertation resulted in the development of a technique that estimates the location of a shunt fault on a radial distribution system that has several single and/or multiphase laterals. The technique takes into account load taps and non-homogeneity of the system, and has been tested for its ability to handle single-phase-to-ground, two-phase-to-ground, phase-to-phase and balanced three-phase faults. Computer simulations indicate that the technique is more accurate than the reactive component method. Results from a prototype of the technique was ...

Science.gov (United States)

OVERFLOW Convergence Rsults: Baldwin-Barth. M = 0.2, Re = 100 Million. B-B Pre Sca Diss. B-B NoPre Sca Diss. B-B Pre Mat Diss. B-B NoPre Mat Diss. B-B Roe.

British Library Electronic Table of Contents (United Kingdom)

The influence of geometry and operating conditions of the centrifugal compressor stage on the radial gas force is determined on the basis of the theoretical method and calculation program using experimental boundary conditions.

Energy Technology Data Exchange (ETDEWEB)

New measuring methods are developed and are tested with the small reactor simulator MIDAS (Mini Dodewaard ASsembly). The purpose of this work is to be able to measure accurately as many different properties of the flow as possible in the coming bigger simulator SIDAS (Simulated Dodewaard ASsembly). In SIDAS the flow around a fuel assembly of the Dutch Dodewaard reactor will be simulated. An extensive evaluation of the gamma detection system showed that the detection system could be simplified strongly. The simplified system is used to measure the radial and axial distribution of the void fraction in the core of MIDAS for three different operating conditions. Two new measuring methods have been developed and tested. A method to estimate the probability density of the void fraction in time. Due to the nonlinear relation between transmission and void fraction the determined average value of the void fraction in general will ...

Energy Technology Data Exchange (ETDEWEB)

This work presents comparative results of a numerical investigation of four possible models for the prediction of thermal performance of fixed bed storage units and their thermal design. These models includes Schumann's model, the radial dispersion model, a model that include both axial heat conduction in the fluid phase and admits thermal gradient in the solids particles and finally a two dimensional single phase model. For each of these models a computer code was written and tested to evaluate the computing time of same data and analyze any other computational problems. The tests of thermal performance included particle size, porosity, particle material, flow rate, inlet temperature and heat losses form tank walls and extremities. Dynamics behaviour of the storage units due to transient variation in either flow rate or inlet temperature was also investigated. The results presented include temperature gradients, ...

Energy Technology Data Exchange (ETDEWEB)

A highly reliable control rod drive mechanism (CRDM) installed inside the reactor vessel has developed for use of an advanced marine reactor. This CRDM contributes to compactness and simplicity of the reactor system, and it can eliminate the possibility of a rod ejection accident. The CRDM works in the high temperature and high pressure water - 310degC and 12 MPa, the same atmosphere as the primary loop. Driving force is produced by a synchronous motor with the rotor of a permanent magnet, which has been developed. An innovative latch mechanism using separable ball nuts can latch driving shaft connecting the control rod and de-latch it for scram. The rod position detector using a magnetostrictive wire type sensor on the principle of Wiedeman effect has been developed, accuracy of which is verified to have a detecting error within 1.2 mm. Ball bearings for thrust and radial supports in rotation have been developed to be capable of working under the high temperature ...

Energy Technology Data Exchange (ETDEWEB)

Feed-forward (FF) artificial neural networks (ANN) and radial basis function (RBF) ANN methods were addressed for evaluating the lightning performance of high voltage transmission lines. Several structures, learning algorithms and transfer functions were tested in order to produce a model with the best generalizing ability. Actual input and output data, collected from operating Hellenic high voltage transmission lines, as well as simulated output data were used in the training, validation and testing process. The aims of the paper are to describe in detail and compare the proposed FF and RBF ANN models, to state their advantages and disadvantages and to present results obtained by their application on operating Hellenic transmission lines of 150kV and 400kV. The ANN results are also compared with results obtained using conventional methods and real records of outage rate showing a quite satisfactory agreement. The proposed ...

International Nuclear Information System (INIS)

The efficient use of the fuel is one of the objectives in the assemblies design of type BWR. The present tendency in the assemblies design of type BWR is through a radial distribution of enrichments. The present work has like object showing the because of this decision, for what a comparison of the neutronic performance of two fuel cells with the same enrichment average but one of them with radial distribution of enrichment and the other with a single enrichment equal to the average. The cells were analyzed with the CASMO-4 code and the obtained results of the behavior of the neutron flow and the power sustain the because of the radial distribution of enrichments. (Author)

Energy Technology Data Exchange (ETDEWEB)

The radial distribution function (RDF) derived from wide angle X-ray diffraction patterns gives additional information about the spatial distribution of atoms. Their radial distances and relative average coordination numbers can be calculated using appropriate mathematical procedures. 7 refs.

International Nuclear Information System (INIS)

The Monte-Carlo method and experimental methods were used to determine the neutron fluxes in the irradiation channels of the Ghana Research Reactor -1. The MCNP5 code was used for this purpose to simulate the radial and axial distribution of the neutron fluxes within all the ten irradiation channels. The results obtained were compared with the experimental results. After the MCNP simulation and experimental procedure, it was observed that axially, the fluxes rise to a peak before falling and then finally leveling out. Axially and radially, it was also observed that the fluxes in the centre of the channels were lower than on the sides. Radially, the fluxes dip in the centre while it increases steadily towards the sides of the channels. The results have shown that there are flux variations within the irradiation channels both axially and radially. (au)

International Nuclear Information System (INIS)

Between December 2001 and May 2004, a ventilation experiment (VE) was performed in the Mont Terri Underground Research Laboratory (URL) and co-financed by the Commission of the European Communities. The objective was to investigate the desaturation of consolidated clay formations in consequence of the ventilation of underground openings of a repository in such a formation. The results of the geoelectric measurements performed in the second phase of the Mont Terri ventilation test can be summarized as follows: Geoelectric tomography has been found suitable for monitoring ventilation-induced saturation changes in the Opalinus clay. During ventilation with dry air a desaturation down to below 50% could be detected in both desaturation cycles. The desaturated zone extends less than 0.5 m into the rock around the microtunnel. During the second resaturation phase, ventilation with humid air led to quick resaturation at the tunnel surface, while resaturation of the rock ...

Energy Technology Data Exchange (ETDEWEB)

The authors are developing MP-TOUGH2 for exploiting massively parallel computers. The goals of this effort are to (1) create a data-parallel subsurface transport code for solving larger problems than currently practical on workstations, (2) write portable code that can take advantage of scalability to run on machines with more processors, and (3) minimize the necessity for additional validation and verification of the resulting code. The initial strategy they have followed is to focus on optimizing the generic and time-consuming task of linear equation solution while leaving the bulk of TOUGH2 unmodified. In so doing, they have implemented a massively parallel direct solver (MPDS) that takes advantage of the banded structure of TOUGH2 Jacobian matrices. The authors have compared timings of the iterative conjugate gradient solvers DSLUBC, DSLUCS, and DSLUGM written in Fortran77 for the front end with the MPDS which uses the data parallel unit. The MPDS shows good performance relative to ...

CERN Document Server

We demonstrate the use of a variational method to determine a quantitative lower bound on the rate of convergence of Markov Chain Monte Carlo (MCMC) algorithms as a function of the target density and proposal density. The bound relies on approximating the second largest eigenvalue in the spectrum of the MCMC operator using a variational principle and the approach is applicable to problems with continuous state spaces. We apply the method to one dimensional examples with Gaussian and quartic target densities, and we contrast the performance of the basic Metropolis-Hastings algorithms with a ``smart'' variant that incorporates gradient information into the trial moves. We find that the variational method agrees quite closely with numerical simulations. We also see that the smart MCMC algorithm often fails to converge geometrically in the tails of the target density except in the simplest case we examine, and even then care must be taken to choose ...

Energy Technology Data Exchange (ETDEWEB)

The thermal performance and phase change stability of stearic acid as a latent heat energy storage material has been studied experimentally. The thermal performance and heat transfer characteristics of the stearic acid were tested and compared with other studies given in the literature. In the present study, parameters such as transition times, temperature range and propagation of the solid-liquid interface as well as the effect of heat flow rate on the phase change stability of stearic acid as a phase change material (PCM) were studied. The experimental results showed that the melting stability of the PCM is better in the radial direction than in the axial direction. The variation in the melting and solidification parameters of the PCM with the change of inlet water temperature is also studied. We observed that while the heat exchanger tube is in the horizontal position, the PCM has more effective and steady phase change characteristics than ...

Energy Technology Data Exchange (ETDEWEB)

The objective of this work is the measurement of two-phase flow parameters to support development of constitutive relationships for the HANARO/MAPLE type finned fuel using Real-Time Neutron Radiography (RTNR). A single element finned Fuel Element Simulator was used with R134a Freon flow. To observe the effect of a spacer device on void distribution, single pin tests were performed with and without a spacer. By analyzing the RTNR images using image processing, the effects of the spacer on the time-averaged and instantaneous void fraction distributions were studied. For the experimental results without a spacer, the time-averaged local void distribution is radially asymmetric and the degree of void fluctuation increases with a decreasing frequency along the heated channel, where the observed asymmetry may be caused by flow induced vibration. For the experimental results with a spacer, the spacer clearly limits any significant vibration and the ...

International Nuclear Information System (INIS)

The measurement of two-phase flow parameters and development of constitutive relationships for the HANARO/MAPLE type finned fuel using Real-Time Neutron Radiography (RTNR) is discussed in this paper. A single element finned Fuel Element Simulator (FES) was used with R134a Freon as the working fluid. To observe the effect of a spacer device on void distribution, single pin tests were performed with and without a spacer. By analyzing the RTNR images using image processing, the effects of the spacer on the time-averaged and instantaneous void fraction distribution were studied. For the experimental results without a spacer, the time-averaged local void distribution is radially asymmetric and the degree of void fluctuation increases with a decreasing frequency along the heated channel, where the observed asymmetry may be caused by flow induced vibration. For the experimental results with a spacer, the spacer clearly limits any significant vibration ...

Energy Technology Data Exchange (ETDEWEB)

Sulfur pollution can lead to serious problems in freshwater wetlands, including phosphorus eutrophication and sulfide toxicity. We tested the effects of anaerobic iron-rich groundwater discharge in fens, simulated by iron injection, on two characteristic species (Juncus effusus and Caltha palustris) in a sulfidic environment. Biomass production of C. palustris roots showed an optimum response to the combined addition of iron and sulfide, with highest values at intermediate concentrations of both substances. Iron deficiency apparently occurred at low iron concentrations, while at high iron concentrations, growth was decreased. For J. effusus, in contrast, no toxic effects were found of both iron and sulfide. This could be explained by larger radial oxygen loss (ROL) of J. effusus and could not be explained by differences in phosphorous concentrations. The results of our experiments confirm that iron-rich groundwater discharge has the potential ...

International Nuclear Information System (INIS)

This study deals with testing the capability of the code PARET to simulate natural convection cooling phenomena under different boundary conditions. In addition to applying and testing some new options related to simulation of the control rod movement and studying the reactivity effect of thermal expansion fuel elements. The experiments of the simple thermal hydraulic loop of Missouri university about natural cooling phenomena in two narrow paralled channels were used to validate the code. The study indicate good results regarding the distribution of coolant flux velocity and clad temperature. In particular the heat transfer coefficient of natural convection has been calculated in good agreement with the experiment. On the other hand, the core of MNSR reactor has been modelled to simulate the reactor dynamic behaviour under natural convection cooling conditions for different initial power level. The observed oscillation during the initial phase ...

UK PubMed Central (United Kingdom)

Spike-timing-dependent plasticity (STDP), a form of Hebbian plasticity, is inherently stabilizing. Whether and how GABAergic inhibition influences STDP is not well understood. Using a model neuron driven...Full Text Available

UK PubMed Central (United Kingdom)

Ten patients in the age range 2 to 22 years are described who had operations initially for squint in childhood. Nine had had concomitant convergent strabismus and one divergent. All presented again...Full Text Available

UK PubMed Central (United Kingdom)

Healthcare-associated infections (HAIs) take a major human toll on society and reduce public confidence in the healthcare system. The current convergence of scientific, public, and legislative...Full Text Available

Science.gov (United States)

The dynamical factors controlling the mean state and variability of the east Pacific intertropical convergence zone (ITCZ) and the associated cross-equatorial boundary layer flow are investigated using observations from the East Pacific Investigation of Climate (EPIC2001) project. The tropical east Pacific exhibits a southerly boundary layer flow that terminates in the ITCZ. This flow is induced by the strong meridional sea surface temperature (SST) gradient in the region. Away from the equator and from deep convection, it is reasonably well described on a day-to-day basis by an extended Ekman balance model. Variability in the strength and northward extent of this flow is caused by variations in free-tropospheric pressure gradients that either reinforce or oppose the pressure gradient associated with the SST gradient. These free-tropospheric gradients are caused by easterly waves, tropical cyclones, and the Madden Julian oscillation.Convergence ...

Energy Technology Data Exchange (ETDEWEB)

The performance of conjugate gradient schemes for minimizing unconstrained energy functionals in the context of electronic structure calculations is studied. The unconstrained functionals allow a straightforward application of conjugate gradients by removing the explicit orthonormality constraints on the quantum-mechanical wave functions. However, the removal of the constraints can lead to slow convergence, in particular when preconditioning is used. The convergence properties of two previously suggested energy functionals are analyzed, and a new functional is proposed, which unifies some of the advantages of the other functionals. A numerical example confirms the analysis.

International Nuclear Information System (INIS)

Monte Carlo criticality calculations have been performed for over 50 years for reactor physics and criticality safety applications. With today's faster computers, these calculations are being carried out to greater precision (smaller uncertainties) in keff, and detailed distributions of power and reaction rates are being computed routinely. This paper provides a review of the fundamental theory of Monte Carlo criticality calculations, with guidance on practical methods for: (1) assuring convergence of both keff and the source distribution, (2) minimizing the bias in keff and reaction rate distributions, and (3) dealing with the under-prediction bias in uncertainties for keff and reaction rate distributions. (authors)

International Nuclear Information System (INIS)

A phenomenological analysis of lifetimes of bottom and charmed hadrons within the framework of the heavy quark expansion is performed. The baryon matrix element is evaluated using the bag model and the nonrelativistic quark model. We find that bottom-baryon lifetimes follow the pattern #tau#(#OMEGA#_b)#approx =##tau#(#XI#_b"-)>#tau#(#LAMBDA#_b)#approx =##tau#(#XI#_b"0). However, neither the lifetime ratio #tau#(#LAMBDA#_b)/#tau#(B_d) nor the absolute decay rates of the #LAMBDA#_b baryon and B mesons can be explained. One way of solving both difficulties is to allow the presence of linear 1/m_Q corrections by scaling the inclusive nonleptonic width with the fifth power of the hadron mass m_H__Q rather than the heavy quark mass m_Q. The hierarchy of bottom baryon lifetimes is dramatically modified to #tau#(#LAMBDA#_b)>#tau#(#XI#_b"-)>#tau#(#XI#_b"0)>#tau#(#OMEGA#_b): The longest-lived #OMEGA#_b among bottom baryons in the OPE prescription now becomes the shortest lived. The ...

International Nuclear Information System (INIS)

To aid in the study of lower hybrid current drive as a means of current profile control, the radial profile and velocity distribution of the fast current-carrying electrons and their time evolution must be known. As part of the recent effort to understand this fast electron transport, a diagnostic has been installed on PBX-M to measure the electron cyclotron emission from the fast electrons. An oblique horizontal view of upshifted cyclotron emission in the midplane can give radial as well as velocity space information about the fast electrons. Emission in X mode frequencies refracted by the right-hand cutoff is radially localized. The observed emission at a specific frequency comes only from the radial region r_t_u_r_n=#0. Emission measured by this new diagnostic has been found to be radially localized as predicted. It is also expected that localized moments of the distribution ...

International Nuclear Information System (INIS)

This report is devoted to the investigation of the influence of electron collisions and radial non-uniformity of plasma density on phase characteristics, spatial attenuation and wave field structure of slow symmetric electromagnetic waves that propagate along cylindrical waveguide structure. It has been shown that collision rate and radial non-uniformity of plasma density for various parameters of waveguide structure and dielectric affect essentially on the wave characteristics and consequently, on the parameters of gas discharge that is sustained by this wave. The results obtained are of large importance for the construction of the theory of gas discharges that are sustained by the surface electromagnetic waves.

Energy Technology Data Exchange (ETDEWEB)

Role of ballooning effect in toroidal plasmas on the transient transport problems is investigated. Due to the mode localization along the magnetic field line, a meso scale appears in a radial correlation length of fluctuating fields. This scale length introduces the interference of the gradient and flux in different radial locations. For the fluctuation which gives the gyro-Bohm-like diffusion in a stationary state, this long radial correlation of the fluctuating field causes a fast propagation of response against a rapid transient perturbation. Upper bound of transient thermal diffusivity is derived. (author)

Science.gov (United States)

Eckert, B., "Axial Kompressoren und Radial Kompressoren," Springer. Verlag, Berlin, 1953. 3. Lebot, Y., et al., "Theoretical and Experimental Determination ...

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Molecular dynamics simulations have been carried out of the radial distribution function of the hard sphere fluid for a range of densities in the equilibrium fluid and just into the metastable region. The first derivative of the hard-sphere radial distribution function at contact was computed and its density dependence fitted to a simple analytic form. Comparisons were made with semi-empirical formulae from the literature, and of these the formula proposed by Tao et al (1992 Phys. Rev. A 46 8007) was found to be in best agreement with the simulation data, although it slightly underestimates the derivative at the higher packing fractions in excess of about 0.45. Close to contact, within a few per cent of the particle diameter, the radial distribution function can be represented well by a second order polynomial. An exponential function, which has some useful analytic features, can also be applied in this region.

International Nuclear Information System (INIS)

A new semi-empirical algorithm for the radial distribution of dose is compared with available data. The algorithm is used to calculate the inactivation cross section for dry enzymes and viruses using an extended target model of a 1-hit detector. Agreement with data is at about the 15% level, approximating the precision of the data itself. (author).

International Nuclear Information System (INIS)

Radial distribution functions of liquid sodium and caesium at 100"0C have been calculated by the method of molecular dynamics with interionic pair potentials derived from Heine-Abarenkov-Shaw type model potential. The results were found to be in good agreement with recent experimental data. (Auth.).

International Nuclear Information System (INIS)

The radial distribution function and the second virial coefficient of interacting bosons have been studied. The second virial coefficient has been deduced theoretically and is in good agreement with experimental values. The third virial coefficient has been calculated from the experimental values of the pressure. (Auth.).

International Nuclear Information System (INIS)

A formula for calculating the Dirac S-matrix for central Lorentz scalar and vector potentials is derived by use of a new amplitude-phase method. The derivation also makes use of certain invariants of the reduced 2-spinor radial Dirac equations.

International Nuclear Information System (INIS)

An experiment was performed with a mock-up of the core of the Fast Flux Test Facility (FFTF) reactor to evaluate three reactivity measurement methods for application to liquid-metal fast breeder reactors (LMFBR): modified source multiplication measurements with the low-level flux monitor for refueling (35 dollars subcritical) of FFTF, noise analysis to 35 dollars subcritical, and inverse kinetics rod drop to 12 dollars subcritical. To investigate the spatial dependence of these measurement methods and to resolve discrepancies previously reported, detectors were placed in the core, reflector, and radial shield, and experimental data were collected with the reactivity at near delayed criticality to 35 dollars subcritical. Conclusions from this experiment are the following. Low-level flux monitors in the shield of the FFTF will be adequate for reactivity surveillance during refueling, using the modified source multiplication method calibrated near ...

CERN Document Server

We study a stochastic gossip model of continuous opinion dynamics in a society consisting of two types of agents: regular agents, who update their beliefs according to information that they receive from their social neighbors; and stubborn agents, who never update their opinions and might represent leaders, political parties or media sources attempting to influence the beliefs in the rest of the society. When the society contains stubborn agents with different opinions, opinion dynamics never lead to a consensus (among the regular agents). Instead, beliefs in the society almost surely fail to converge, and the belief of each regular agent converges in law to a non-degenerate random variable. The model thus generates long-run disagreement and continuous opinion fluctuations. The structure of the social network and the location of stubborn agents within it shape opinion dynamics. When the society is ``highly fluid'', meaning that the mixing time ...

CERN Document Server

We consider the effect of distributed delays in neural feedback systems. The avian optic tectum is reciprocally connected with the nucleus isthmi. Extracellular stimulation combined with intracellular recordings reveal a range of signal delays from 4 to 9 ms between isthmotectal elements. This observation together with prior mathematical analysis concerning the influence of a delay distribution on system dynamics raises the question whether a broad delay distribution can impact the dynamics of neural feedback loops. For a system of reciprocally connected model neurons, we found that distributed delays enhance system stability in the following sense. With increased distribution of delays, the system converges faster to a fixed point and converges slower toward a limit cycle. Further, the introduction of distributed delays leads to an increased range of the average delay value for which the system's equilibrium point is stable. The enhancement of ...

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Particle simulation studies of collisionless driven reconnection in an open system are presented. Collisionless reconnection evolves in two steps in accordance with the formation of two current layers, i.e., an ion current layer in the early ion phase and an electron current layer in the late electron phase. After the electron current layer is formed inside the ion current layer, the system relaxes gradually to a steady state when convergent plasma flow is driven by an external electric field with a narrow input window. On the other hand, when the convergent plasma flow is driven from the wide input window, magnetic reconnection takes place in an intermittent manner, due to the frequent formation of magnetic islands in the vicinity of neutral sheet. (author)

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The possibility of controlling the radial electric field of toroidal plasmas by injecting high energy electrons along the reversible loss cone orbit of the helical magnetic traps is investigated. It is well known that the radial electric field plays an important role in the confinement improvement scenario especially in the low collisional regime under the physics picture of neoclassical theory. For this purpose, it is made clear that the most suitable particles are transit particles, which show a transition from helically trapped orbits to blocked ones. It is also found that a parallel AC electric field launched from outside assists this transition and makes it possible for particles to penetrate deeply into the plasma. In addition we clarify that the viscosity of the plasma coupled with the helical field configuration provide a bifurcation of plasma states and its stable solution results in confinement improvement. (author)

CERN Document Server

New non-stationary non-contracted form of the erosive radially-slotted discharge as a thin round sheet with the current of the azimuth direction have been discovered, its existence beings stipulated by a radial transport-wave fluxes. Characteristic features of this discharge is self-confinement of the discharge current magnitude, corresponding decrease of the current pulse duration and occurrence of an energy and substance ejection with rather unusual properties. Measurements of kinetics of the discharge current, the plasma radiation intensity and an electrical probe signal, as well as the transmission electron microscope investigations of characteristic aerodisperse aggregates arising the erosive phase, have been carried out. The probe signal duration was about 10 times greater than that of the current; its kinetics was complicated suggesting existence in the slot of two components with fundamentally different properties and states of the ...

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Radial sonic crystals (RSC) are fluidlike structures infinitely periodic along the radial direction that verify the Bloch theorem and are possible only if certain specially designed acoustic metamaterials with mass density anisotropy can be engineered (see Torrent and Sanchez-Dehesa 2009 Phys. Rev. Lett. 103 064301). A comprehensive analysis of two-dimensional (2D) RSC shells is reported here. A given shell is in fact a circular slab with a central cavity. These finite crystal structures contain Fabry-Perot-like resonances and modes strongly localized at the central cavity. Semi-analytical expressions are developed to obtain the quality factors of the different resonances, their symmetry features and their excitation properties. The results reported here are completely general and can be extended to equivalent 3D spherical shells and to their photonic counterparts.

International Nuclear Information System (INIS)

TRIGA-SSR is a steady state research and material test reactor that has been in operation since 1980. The original TRIGA fuel was HEU (highly enriched uranium) with a U"2"3"5 enrichment of 93 per cent. Almost all TRIGA HEU fuel bundles are now burned-up. Part of the spent fuel was loaded and transferred to US, in a Romania - DOE arrangement. The rest of the TRIGA fuel bundles have to be temporarily stored in the TRIGA facility. As the storage conditions had to be established with caution, neutron and thermal hydraulic evaluations of the storage conditions were required. Some criticality evaluations were made based on the SAR (Safety Analysis Report) data. Fuel constant axial temperature approximation effect is usual for criticality computations. TRIGA-SSR fuel bundle geometry and materials model for SCALE5-CSAS module allows the introduction of a fuel temperature dependency for the entire fuel active height, using different materials for each fuel bundle region. ...

International Nuclear Information System (INIS)

To evaluate the usefulness of three-dimensional (3D) rotational angiography, cervical carotid or cerebral angiography was done without catheterizing the branches of the thoracic aorta. A 5-Fr pig-tail type catheter was passed into the ascending aorta via the radial artery or the femoral artery. Optimal carotid angiogram views were obtained using approximately 45 ml of contrast medium at a flow rate of 15 ml/sec. Optimal cerebral angiogram views were obtained using approximately 70 ml of contrast medium at a flow rate of 20 ml/sec. The contrast medium concentration was 300 to 350 mgI/ml. A satisfactory view could be obtained in 5 of 8 (63%) cases on cervical carotid 3D angiography and in 8 of 14 (57%) cases on cerebral 3D angiography. In all cases, no complications were noted. This method offers the advantages of requiring a relatively short procedure time and a decrease in radiation exposure. Further studies are needed to determine the optimal time to start filming ...

Science.gov (United States)

A marine propulsion system is a very complicated system composed of many mechanical components. As a result, the vibration signal of a gearbox in the system is strongly coupled with the vibration signatures of other components including a diesel engine and main shaft. It is therefore imperative to assess the coupling effect on diagnostic reliability in the process of gear fault diagnosis. For this reason, a fault detection and diagnosis method based on bispectrum analysis and artificial neural networks (ANNs) was proposed for the gearbox with consideration given to the impact of the other components in marine propulsion systems. To monitor the gear conditions, the bispectrum analysis was first employed to detect gear faults. The amplitude-frequency plots containing gear characteristic signals were then attained based on the bispectrum technique, which could be regarded as an index actualizing forepart gear faults diagnosis. Both the back propagation neural network (BPNN) and the ...

Energy Technology Data Exchange (ETDEWEB)

A new multigrid algorithm based on the method of self-correction for the solution of elliptic problems is described. The method exploits information contained in the residual to dynamically modify the source term (right-hand side) of the elliptic problem. It is shown that the self-correcting solver is more efficient at damping the short wavelength modes of the algebraic error than its standard equivalent. When used in conjunction with a multigrid method, the resulting solver displays an improved convergence rate with no additional computational work.

CERN Document Server

Ozsvath and Szabo show that there is a spectral sequence whose E^2 term is the reduced Khovanov homology of L, and which converges to the Heegaard Floer homology of the (orientation reversed) branched double cover of S^3 along L. We prove that the E^k term of this spectral sequence is an invariant of the link L when k>2. If L is a transverse link, then we show that Plamenevskaya's transverse invariant gives rise to a transverse invariant of L in each of these higher terms.

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Central limit theorem estimates of anomalous fractal dimensions of self-similar random cascades are studied. It is found that, in general, the normal approximation fails badly. A systematic series of approximations which converges to the exact result (both for the fractal dimensions and for the distribution itself) is derived for the {alpha}-model. Consequences for the 'empty bin effect' are indicated. (orig.).

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In ab initio molecular dynamics, whenever information about the potential energy surface is needed for integrating the equations of motion, it is computed 'on the fly' using electronic structure calculations. For Born-Oppenheimer methods, the electronic structure calculations are converged, whereas in the extended Lagrangian approach the electronic structure is propagated along with the nuclei. Some recent advances for both approaches are discussed.

International Nuclear Information System (INIS)

Extensive investigations and detailed analysis of the failure reason of 9DVN002ZV fan in Daya Bay Nuclear Power Station showed that the fan destroy was caused by the failure of non-drive end bear. The direct cause of this bearing' failure was its improper assembly caused by improper maintenance procedure, and the root cause was too small internal radial clearance after mounting. The factor affecting bearing internal radial clearance, the relationship between clearance and operating life time and fan failure process were discussed. (authors)

International Nuclear Information System (INIS)

A clear and reproducible transition to a regime with an improved particle confinement is routinely observed on the CASTOR tokamak, if the biasing electrode is inserted deep enough into the plasma (r/a?0.5) and biased up to +250 V. The steepening of the radial profiles of the plasma density and potential demonstrate the formation of a transport barrier just inside the last closed flux surface. Fast relaxations of the edge plasma parameters, with a frequency of about 10 kHz, are observed when the average radial electric field within the barrier prevails values of about 20 kV/m. A detailed analysis of the spatial-temporal behaviour of these relaxations is presented.

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Longitudinal space charge (LSC) force can be a main effect driving the microbunching instability in the linac for an x-ray free-electron laser (FEL). In this paper, the LSC-induced beam modulation is studied using an integral equation approach that takes into account the transverse (radial) variation of LSC field for both the coasting beam limit and bunched beam. Changes of beam energy and the transverse beam size can be also incorporated. We discuss the validity of this approach and compare it with other analyses as well as numerical simulations.

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Differential cross sections have been measured for the elastic and inelastic scattering of 104 MeV alpha-particles from /sup 90/,/sup 92/Zr. The experimental data are analyzed in terms of coupled channels on the basis of a flexible anharmonic vibrator model and using different parametrizations of the radial shape of the extended optical potential. The results favour the squared Saxon-Woods type for the real part. Additionally to a radial momentum analysis of the real potentials a semimicroscopic folding model has been invoked for extracting isoscalar quadrupole and hexadecapole transition rates.

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Several components of high-temperature reactor units have roller bearings in order to carry out their motions without much friction. The use of such bearings poses friction and wear problems which cannot be mastered by commercial roller bearing technology. Possible improvements of coating, cage design and bearing materials as well as of their parameters were registered and studied. The service life of dry lubricated bearings was considerably improved. With a radial or axial load on the bearing of {>=} 10% of the static load, {approx_equal} 20x10{sup 6} rolling motions/actuations can be performed. The connections between surface compression and wear were determined, and optimum conditions for the transfer of lubricants from the cage onto the bearing race were worked out. Coating of corrosion-resistant roller bearing steels with the HRB-M{sub 0}S{sub 2} running-in coating could be proved. New cage designs and materials were tested with ...

Energy Technology Data Exchange (ETDEWEB)

In this thesis a study is made of the of voltage characteristics and reactive power control in the transmission network of the Electric Power Systems (EPS) with static compensators of VARs (SCVs). The necessity of voltage and reactive power control and the application of SCVs as a solution means for three representative operation stages of the EPS, considering balanced operation conditions and fundamental frequency is analyzed: Operation in the presence of incremental voltage changes, quasi-stationary operation or steady state and behavior at the occurrence of big disturbances. The application of SCVs to systems of integral transmission is in general a closed loop control system, reason why the analysis of the interaction of the system EPS-SCV is considered as an essential part of the voltage and reactive power control study. Firstly, the response analysis of the control loop is made for incremental voltage changes, representing the power system by means of its equivalent of Thevenin ...

International Nuclear Information System (INIS)

In this paper, molecular quantum computation is numerically studied with the quantum search algorithm (Grover's algorithm) by means of optimal control simulation. Qubits are implemented in the vibronic states of I_2, while gate operations are realized by optimally designed laser pulses. The methodological aspects of the simulation are discussed in detail. We show that the algorithm for solving a gate pulse-design problem has the same mathematical form as a state-to-state control problem in the density matrix formalism, which provides monotonically convergent algorithms as an alternative to the Krotov method. The sequential irradiation of separately designed gate pulses leads to the population distribution predicted by Grover's algorithm. The computational accuracy is reduced by the imperfect quality of the pulse design and by the electronic decoherence processes that are modeled by the non-Markovian master equation. However, as long as we focus on the population ...

Energy Technology Data Exchange (ETDEWEB)

Model-based approaches to pattern recognition and machine vision have been proposed to overcome the exorbitant training requirements of earlier computational paradigms. However, uncertainties in data were found to lead to a combinatorial explosion of the computational complexity. This issue is related here to the roles of a priori knowledge vs. adaptive learning. What is the a-priori knowledge representation that supports learning? I introduce Modeling Field Theory (MFT), a model-based neural network whose adaptive learning is based on a priori models. These models combine deterministic, fuzzy, and statistical aspects to account for a priori knowledge, its fuzzy nature, and data uncertainties. In the process of learning, a priori fuzzy concepts converge to crisp or probabilistic concepts. The MFT is a convergent dynamical system of only linear computational complexity. Fuzzy logic turns out to be essential for reducing the combinatorial ...

Energy Technology Data Exchange (ETDEWEB)

The quality of molecular dynamics (MD) simulations of proteins depends critically on the biomolecular force field that is used. Such force fields are defined by force-field parameter sets, which are generally determined and improved through calibration of properties of small molecules against experimental or theoretical data. By application to large molecules such as proteins, a new force-field parameter set can be validated. We report two 3.5 ns molecular dynamics simulations of hen egg white lysozyme in water applying the widely used GROMOS force-field parameter set 43A1 and a new set 45A3. The two MD ensembles are evaluated against NMR spectroscopic data NOE atom-atom distance bounds, {sup 3}J{sub NH{alpha}} and {sup 3}J{sub {alpha}}{sub {beta}} coupling constants, and {sup 1}5N relaxation data. It is shown that the two sets reproduce structural properties about equally well. The 45A3 ensemble fulfills the atom-atom distance bounds derived from NMR spectroscopy slightly less well ...

British Library Electronic Table of Contents (United Kingdom)

For reliable operation and the optimization of production, industrial fermentation processes require appropriate tools for monitoring the process in real time. This work presents the structure and operation of a soft sensor for the on-line monitoring of biomass and product concentration during salinomycin and bacitracin fermentation in an industrial, 80-m^3 batch reactor; moreover it provides a tool for evaluation of batch production verified in industrial application. The process estimation algorithm consists of decoupled growth and product models, which ensures an unbiased convergence of the estimator and the robustness of the model. The production of secondary metabolites is described with a non-structured model upgraded with a variable forgetting factor that demonstrated a successful e...

CERN Document Server

This paper introduces a new parsimonious structure for mixture of autoregressive models. the weighting coefficients are determined through latent random variables, following a hidden Markov model. We propose a dynamic programming algorithm for the application of forecasting. We also derive the limiting behavior of unconditional first moment of the process and an appropriate upper bound for the limiting value of the variance. This can be considered as long run behavior of the process. Finally we show convergence and stability of the second moment. Further, we illustrate the efficacy of the proposed model by simulation and forecasting.

International Nuclear Information System (INIS)

By the linear augmented plane wave method (APW) the energy zone of silver and technetium structure is calculated. The potential has been determined by means of superposition of atomic charge densities according to slater exchange method. Total and partial state densities have been calculated by the tetrahedron method. The APW-method convergence on the example of silver is studied, the comparison with the calculation results by the APW method and other data is carried out. The APW method high efficiency is pointed out. In dipole approximation the intensity distribution in L"3, M"5 N"3 technetium emission spectra is calculated.

British Library Electronic Table of Contents (United Kingdom)

The algorithmic, or consistent, tangent stiffness was introduced to improve the asymptotic convergence rate of the iterative correction algorithm for the evolutive analysis of elastoplastic structures. The original approach is based on a formulation of the elastoplastic law in terms of a plastic multiplier with an analysis which, in general, requires an operator inversion. A geometric description of the method, based on hypersurface theory, is proposed here to provide a clear picture of the algorithmic properties. An estimate of the tangent stiffness associated with finite step elastoplastic and elastoviscoplastic constitutive models is given. It is based on the properties of the projection operator on the elastic domain and avoids operator inversions retaining the beneficial properties of...

CERN Document Server

We study a percolation process on the planted binary tree, where clusters freeze as soon as they become larger than some fixed parameter N. We show that as N goes to infinity, the process converges in some sense to the frozen percolation process introduced by Aldous. In particular, our results show that the asymptotic behaviour differs substantially from that on the square lattice, on which a similar process has been studied recently by van den Berg, de Lima and Nolin.

International Nuclear Information System (INIS)

We study the spin dependence of accretion onto rotating Kerr black holes using analytic techniques. In its linear regime, angular momentum transport in MHD turbulent accretion flow involves the generation of radial magnetic field connecting plasma in a differentially rotating flow. We take a first principles approach, highlighting the constraint that limits the generation and amplification of radial magnetic fields, stemming from the transfer of energy from mechanical to magnetic form. Because the energy transferred in magnetic form is ultimately constrained by gravitational potential energy or Killing energy, the spin dependence of the latter allows us to derive spin-dependent constraints on the success of the accreting plasma to expel its angular momentum. We find an inverse relationship between this ability and black hole spin. If this radial magnetic field generation forms the basis for angular momentum transfer in ...

Science.gov (United States)

The visual outcomes of Acanthamoeba keratitis, a rare cause of corneal infection, can be devastating. This paper reports two contact lens wearers with severe pain and photophobia who presented to the emergency room. Biomicroscopy revealed radial keratoneuritis in both individuals. Tissue culture on a nonnutrient agar plate with Escherichia coli overlay resulted in a heavy growth of Acanthamoeba. The inpatient treatment included 0.02% polyhexamethylene biguanide, chlorhexidine, neomycin/polymyxin B/bacitracin (Neosporin), and oral fluconazole, which successfully controlled the corneal infection and improvement in the best corrected visual acuity in both patients. Infection did not recur during the 12-month follow-up period. Acanthamoeba keratitis can present as radial keratoneuritis, mimicking other common corneal infections resulting in diagnostic and treatment delays. Early diagnosis and prudent treatment of Acanthamoeba keratitis are the keys ...

Energy Technology Data Exchange (ETDEWEB)

The thermal contact resistance between balls and inner and outer rings of thermally steady space-use deep groove ball bearings was studied experimentally to verify the validity of the previously proposed calculation method for the resistance. The 440C stainless steel single row bearing was used for measuring its steady state temperature distributions in a vacuum environment under axial, radial and combined load conditions. As a result, the experimental results of the resistance well agreed with calculated ones under each load condition resulting in the sufficient validity at nearly the same surface roughness. It was necessary to apply a static equivalent radial load to calculation under the combined load that a contact angle is larger than the angle of resultant force dependent on both load components. In experiments under only radial load, measurement of outer ring temperatures was necessary at some points with no contact ...

International Nuclear Information System (INIS)

In this work, the Calibration-Free approach for Laser-Induced Breakdown Spectroscopy (CF-LIBS) was applied for the first time to radially resolved spectra emitted by a laser-induced plasma. The radial profiles of plasma temperature and electron number density were used to calculate the local relative concentration of the elements of interest. We analyzed a set of profiles of the local spectral emission coefficient obtained previously by means of spatial deconvolution of the spectra from a copper-based alloy (Cu 93, Fe 5, Mn 1, Ni 1 wt.%) laser-induced plasma. A spatially integrated spectrum of the same plasma was also analyzed for comparison purpose. The relative abundance of the minor components Fe, Mn and Ni was calculated. The results obtained from the central region of the plasma were closer to the nominal concentrations than those obtained from the spatially integrated spectrum. However, an increasing deviation was observed towards the ...

British Library Electronic Table of Contents (United Kingdom)

Abstract In this paper, the effect of several turbulence parameters during various flow conditions in Owens Valley, educed from coherent Doppler lidar data have been studied. Radial velocity structure functions are processed to estimate the turbulent kinetic energy (TKE) dissipation rate, integral length scale and velocity variance, assuming a theoretical model for isotropic wind fields. Corrections for turbulence measurements have been considered to address the complications due to inherent volumetric averaging of radial velocity over each range gate, noise of the lidar data, and the assumptions required to estimate effects of smaller scales of motion on turbulence quantities. Using data from the Terrain-induced Rotor Experiment (T-REX) in April-May 2006, vertical profiles of wind and tur...

Energy Technology Data Exchange (ETDEWEB)

A rotary drill bit having a drill bit body and at least one trunnion projecting from the drill bit body and a rotary cutter supported on at least one radial roller bearing on the trunnion. The rolling elements of the bearing are guided on at least one axial end facing the drill bit body in an outer bearing race groove incorporated in the bore of the rotary cutter. The inner bearing race groove is formed on the trunnion for the rolling elements of the radial roller bearing. At least one filling opening is provided which extends through the drill bit body and trunnion and is essentially axially oriented having one terminal end adjacent the inner bearing race groove and at least one filler piece for sealing the opening.

CERN Document Server

A generalized relativistic harmonic oscillator for spin 1/2 particles is studied. The Dirac Hamiltonian contains a scalar, $S$, and a vector, $V$, quadratic potentials in the radial coordinate, as well as a tensor potential, $U$, linear in $r$. Setting either or both combinations $\\Sigma=S+V$ and $% \\Delta=V-S$ to zero, analytical solutions for bound states of the corresponding Dirac equations are found. The eigenenergies and wave functions are presented and particular cases are discussed, devoting a special attention to the non-relativistic limit and the case $\\Sigma=0$, for which pseudospin symmetry is exact. We also show that the case $U=\\Delta=0$ is the most natural generalization of the non-relativistic harmonic oscillator. The radial node structure of the Dirac spinor is studied for several combinations of harmonic oscillator potentials, and that study allows us to explain why nuclear intruder levels cannot be described in the ...

CERN Document Server

The confining effect of a spherical substrate inducing anchoring (normal to the surface) of rod-like liquid crystal molecules contained in a thin film spread over it has been investigated with regard to possible changes in the nature of the isotropic-to-nematic phase transition as the sample is cooled. The focus of these Monte Carlo simulations is to study the competing effects of the homeotropic anchoring due to the surface inducing orientational ordering in the radial direction and the inherent uniaxial order promoted by the intermolecular interactions. By adopting entropic sampling procedure, we could investigate this transition with a high temperature precision, and we studied the effect of the surface anchoring strength on the phase diagram for a specifically chosen geometry. We find that there is a threshold anchoring strength of the surface below which uniaxial nematic phase results, and above which the isotropic fluid cools to a ...

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Test de levage module QRL

International Nuclear Information System (INIS)

Short communication.

CERN Document Server

Metals and alloys : atmospheric corrosion testing : General requirements for field tests

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The wind unit working wheel has 4 radial rectangular frames arranged in two vertical planes which are perpendicular to each other. In the planes limited by the frames, on loop hinges with limiting supports, there are flat blades. When the working wheel rotates under the influence of wind pressure, the blades automatically occupy a vertical or horizontal (wind vane) position depending on the direction of blade motion and the direction of wind velocity.

Energy Technology Data Exchange (ETDEWEB)

The completed ribbon-winding theory, including temperature loading of the high-pressure compound vessel, was proposed. The influence of the bending stress in the wound ribbon is taken into account. Internal core of the compound vessel consists of matrix and ring, made of different materials. The relations were derived in analytical form, describing the radial distribution of necessary tangential prestressing.

Energy Technology Data Exchange (ETDEWEB)

The Klein-Gordan equation in the background of the Schwarzschild curved space-time is considered and the scattering of radial tardyons and tachyons from a black hole is studied. It is shown that black holes of mass below 7x10/sup 14/g may contain bound states of tardyons of pion mass which will be unstable on account of the presence of an attractive r/sup -4/ term.

International Nuclear Information System (INIS)

''Magnetic braking'' of the plasma toroidal rotation in the high confinement H mode by applied resonant, low m,n=1 static error fields is used in DIII-D [Nucl. Fusion 31, 875 (1991)] as an independent control to evaluate the E_rxB stabilization of microturbulence in the plasma core. In the core (#rho# approx-lt 0.9) of a tokamak, the radial electric field and its shear are dominated by toroidal rotation. The fundamental quantity for shear stabilization of microturbulence is shear in the velocity of the fluctuations v_p_e_r_p_e_n_d_i_c_u_l_a_r#approx#E_rxB/B#centre dot#B which in the core is v_p_e_r_p_e_n_d_i_c_u_l_a_r#approx#v_#phi#B_#theta#/ B_#phi#. With magnetic braking greatly decreasing the toroidal rotation and thus reducing the core radial electric field and shear, far infrared (FIR) measurements of density microturbulence show downshifting in frequency near #rho##approx#0.8 as a result of the reduced Doppler shift ...

CERN Document Server

A general theorem on the GBDT version of the B\\"acklund-Darboux transformation for systems rationally depending on the spectral parameter is treated and its applications to nonlinear equations are given. Explicit solutions of direct and inverse problems for Dirac-type systems, including systems with singularities, and for the system auxiliary to the $N$-wave equation are reviewed. New results on explicit construction of the wave functions for radial Dirac equation are obtained.

International Nuclear Information System (INIS)

The influence of RTA (Rapid Thermal Anneal) treatment on MOS radiation hardness is demonstrated and compared with classical furnace treatment. In the case of the RTA, the oxide trapped charge is found to depend on: (i) the anneal temperature as expected, data are in good agreement with a recently developed model of oxygen out-diffusion; (ii) the location across the wafer with a radial dependence, results could be related to stress induced by thermal gradient.

International Nuclear Information System (INIS)

A unified calculation of neutron-rich isotopes in lithium is performed using the hyperspherical basis in which the underlying symmetry of each isotope exhibits a simple structure. The variation of the binding energy as a function of mass number is qualitatively reproduced, and the asymptotic of radial distribution of each isotope decreases exponentially. The form factors of the lithium isotopes are calculated and display diffraction minima. 27 refs., 3 figs., 3 tabs.

CERN Document Server

The network utility maximization (NUM) problem for multi-path is a problem which is non-strictly convex and non-separable. Using Jensen's inequality, we approximate the NUM to a strictly convex and separable problem which can be solved efficiently by the dual decomposition method. After a series of approximations, the result of the approximation problem converges to the globally optimal solution of the original NUM. Moreover, because of the separable and dual-based natures of the proposed algorithm, we utilize the reverse engineering frameworks of the current TCPs to develop a series of multi-path TCPs which are totally compatible with current TCPs. The multi-path users using our protocols can run simultaneously with the single-path users using the current TCPs. The simulations of our Multi-path Reno on ns-2 show the compatibility and the fairness among multi-path and single-path users.

CERN Document Server

Hidden Markov models (HMMs) are probabilistic functions of finite Markov chains, or, put in other words, state space models with finite state space. In this paper we examine subspace estimation methods for HMMs whose output lies a finite set as well. In particular we study the geometric structure arising from the non-minimality of the linear state space representation of HMMs, and consistency of a subspace algorithm arising from a certain factorisation of the singular value decomposition of the estimated linear prediction matrix. For this algorithm we show that the estimates of the transition and emission probability matrices are consistent up to a similarity transformation, and that the m-step linear predictor computed from the estimated system matrices is consistent, i.e. converges to the true optimal linear m-step predictor.

CERN Document Server

We assess the accuracy and relevance of the numerical algorithms based on the principles of Geometrical Optics (GO) and Physical Optics (PO) in the analysis of reduced-size homogeneous dielectric lenses prone to behave as open resonators. As a benchmark solution, we use the Muller boundary integral equations discretized with trigonometric Galerkin scheme that has guaranteed and fast convergence as well as controllable accuracy. The lens cross-section is chosen typical for practical applications, namely an extended hemiellipse whose eccentricity satisfies the GO focusing condition. The analysis concerns homogeneous lenses made of rexolite, fused quartz, and silicon with the size varying between 3 and 20 wavelengths in free space. We consider the 2-D case with both E- and H-polarized plane waves under normal and oblique incidence, and compare characteristics of the near fields.

International Nuclear Information System (INIS)

The difficulty and unstability of the parameter estimation of mass action model for radioimmunoassay are the major obstacles to its application in routine work. A unique robust curve fitting method for the mass action model was introduced. large numbers of simulated data were generated with Monte Carlo method to compare the accuracy and robustness of the robust fitting and the least squre fitting (Marquardt method) of the mass action model. The results demonstrated that the new robusst method significantly increased the accuracy and reliability of data processing with the mass action model. It also markedly reduced the influence of outliers in the fitting of RIA data, and it was always 'convergent'. This robust method could also be applied to other mathematical models which can be transformed into high degree equations and no initial estimates are needed for curve fitting.

International Nuclear Information System (INIS)

In this paper, research on pass schedule of tandem cold mill (TCM) is carried out. According to load (reduction, rolling force, motor power) balance, non-linear equations set with variables of inter-stand thickness is constructed. The pass schedule optimization is carried out by solving the non-linear equations set. As the traditional method, the Newton-Raphson method is used for solving the non-linear equations set. In this paper a new simple method is brought up. On basis of the monotone relations between thickness and load, the inter-stands thickness is adjusted dynamically. The solution of non-linear equations set can be converged by iterative calculation. This method can avoid the derivative calculation used by traditional method. So, this method is simple and calculation speed is high. It is suitable for on-line control. (author)

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Even though the currently intensive research efforts on high- temperature superconducting materials have not yet converged on a well specified practical material, the indications are that such a material may be quite brittle, anisotropic, and may contain many flaws such as microcracks and voids at grain boundaries. Consequently, practical applications of high temperature superconducting materials will require a very careful strength analysis based on fracture mechanics considerations. Because of the high sensitivity of the strength of such materials to the presence of defects, methods of quantitative non-destructive evaluation may be expected to play an important role in strength determinations. This proposal is concerned with the use of ultrasonic methods to detect and characterize isolated cracks, clusters of microcracks and microcracks distributed throughout the material. Particular attention has been, and will continue to be devoted to relating ultrasonic ...

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Recently, we showed (Yu, Phys. Rev. E 58 (1998) 4991) that the widely used simulation code TDA3D, even though a single-frequency code, can be used to determine the power spectrum in the SASE process with excellent approximation in the exponential growth regime. In this paper, we apply this method to the BNL Cornell Wiggler A SASE experiment as an example. When the gain is not very high, there are many modes in the radiation, which seems to make the analytical calculation very difficult. However, we show that the increment of the radiation due to SASE over the spontaneous radiation can be expanded in terms of guided modes with rapid convergence. Thus when the spontaneous radiation is subtracted from the SASE power during the calculation, there is a good agreement between the analytical theory and the numerical simulation.

British Library Electronic Table of Contents (United Kingdom)

ResumeLa convergence des solutions faibles du systeme de Navier-Stokes-Fourier-Poisson compressible avec un terme de frottement est etudiee dans la limite dun frottement infini, la loi de pression incluant, comme cas particulier, celle correspondant aux particules de Fermi-Dirac. La limite se trouve etre une solution faible dun systeme de Smoluchowski-Poisson non isotherme, la temperature ne dependant que de la variable temporelle et etant determinee par la conservation de lenergie totale.

CERN Document Server

This paper presents three non-linear asymptotic observers corresponding to three examples of engineering interest: a chemical reactor, a non-holonomic car, and an inertial navigation system. For each example, the design is based on physical symmetries. This motivates the theoretical development of invariant observers, i.e, symmetry-preserving observers. We consider an observer to consist in a copy of the system equation and a correction term, and we give a constructive method (based on the Cartan moving-frame method) to find all the symmetry-preserving correction terms. They rely on an invariant frame (a classical notion) and on an invariant output-error, a less standard notion precisely defined here. For each example, the convergence analysis relies also on symmetries consideration with a key use of invariant state-errors. For the non-holonomic car and the inertial navigation system, the invariant state-errors is shown to obey an autonomous differential equation ...

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An array of sonic transducers, useful for medical ultrasonic imaging, has individual sections thereof separately coupled for forming separate beams of sonic energy which converge, respectively, to separate foci along a common axis of the beams. The ratio of the diameter of the radiating aperture of the array relative to a wavelength of the sonic energy is chosen to provide a moderate degree of focusing so that the depth of field at one focus blends with the depth of field of the next focus. Thereby, there is formed a continuous region of substantially uniform intensity of sonic radiation along the common beam axis. Circuitry is provided for selecting one or more specific foci dependent on the bounds of a selected region to be insonified. Upon reception of sonic energy, circuitry is provided for selecting one or more specific foci as a function of the time of travel of an echo from a subject being observed to approximate a continuously varying focus in accordance ...

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Code coupling activities have so far focused on coupling the neutronics modules with the CFD module. An interface module for the CFD-ACE/DeCART coupling was established as an alternative to the original STAR-CD/DeCART interface. The interface module for DeCART/CFD-ACE was validated by single-pin model. The optimized CFD mesh was decided through the calculation of multi-pin model. It was important to consider turbulent mixing of subchannels for calculation of fuel temperature. For the parallel calculation, the optimized decompose process was necessary to reduce the calculation costs and setting of the iteration and convergence criterion for each code was important, too.

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A fast multipole transformation is adapted to the evaluation of summations that occur in global climate calculations when transforming between spatial and spherical harmonic representations. For each summation, the timing of the fast multipole transformation scales linearly with the number of latitude gridpoints, but the timing for direct evaluations scales quadratically. In spite of a larger computational overhead, this scaling advantage renders the fast multipole method faster than direct evaluation for transformations involving greater than approximately 300 to 500 gridpoints. Convergence of the fast multipole transformation is accurate to machine precision. As the resolution in global climate calculations continues to increase, an increasingly large fraction of the computational work involves the transformation between spatial and spherical harmonic representations. The fast multipole transformation offers a significant reduction in computational time for these ...

Science.gov (United States)

The procedure describes the procedures to be used in evaluating consumable and combustible cartridge cases. Included are ballistic tests, environmental tests, adverse condition tests, fungus resistance tests, drop tests and safety tests. (Author)

Science.gov (United States)

Spike-timing-dependent plasticity (STDP), a form of Hebbian plasticity, is inherently stabilizing. Whether and how GABAergic inhibition influences STDP is not well understood. Using a model neuron driven by converging inputs modifiable by STDP, we determined that a sufficient level of inhibition was critical to ensure that temporal coherence (correlation among presynaptic spike times) of synaptic inputs, rather than initial strength or number of inputs within a pathway, controlled postsynaptic spike timing. Inhibition exerted this effect by preferentially reducing synaptic efficacy, the ability of inputs to evoke postsynaptic action potentials, of the less coherent inputs. In visual cortical slices, inhibition potently reduced synaptic efficacy at ages during but not before the critical period of ocular dominance (OD) plasticity. Whole-cell recordings revealed that the amplitude of unitary IPSCs from parvalbumin positive (Pv+) interneurons to pyramidal neurons ...

Science.gov (United States)

Observations are presented that link extratropical Rossby wave disturbances excited in the Southern Hemisphere subtropical jet to the initiation of convectively coupled Kelvin waves in the Pacific intertropical convergence zone (ITCZ) during austral winter. A baroclinic, zonal wavenumber 6, eastward-propagating Rossby wave train in the subtropical jet turns northeastward in the vicinity of Australia, inducing upper tropospheric divergence and vertical motion fields that spread equatorward and induce cloudiness anomalies in the Tropics. Lower tropospheric pressure surges excited from the extratropics also induce Kelvin wave-like geopotential height and temperature anomalies at the surface, providing additional lower tropospheric convergence and vertical motion forcing. The tropical outgoing longwave radiation (OLR) and circulation fields propagate eastward in tandem with the extratropical Rossby wave train at approximately 17 m s-1. Kelvin wave ...

CERN Document Server

The stellar disc kinematics in a sample of fifteen intermediate- to late-type edge-on spiral galaxies are studied using a dynamical modeling technique. The sample covers a substantial range in maximum rotation velocity and deprojected face-on surface brightness and contains seven spirals with either a boxy- or peanut-shaped bulge. Dynamical models of the stellar discs are constructed using the disc structure from $I$-band surface photometry and rotation curves observed in the gas. The differences in the line-of-sight stellar kinematics between the models and absorption line spectroscopy are minimized using a least-squares approach. The modeling constrains the disc surface density and stellar radial velocity dispersion at a fiducial radius through the free parameter $\\sqrt{M/L}$ $(\\sigma_{\\rm z}/\\sigma_{\\rm R})^{-1}$, where $\\sigma_{\\rm z}/\\sigma_{\\rm R}$ is the ratio of vertical and radial velocity dispersion and $M/L$ the disc ...

International Nuclear Information System (INIS)

The numerical calculation of oscillatory wavefunctions occurring in the theory of electron scattering from positive ions is considered, the aim being to develop methods for evaluating the oscillatory solutions using a logarithmic grid. Thus, the permitted step-size for the solution depends only upon the potential, enabling calculations at different energies to be performed using the same discretisation. Two similar generalisations of the W.K.B. transformation for second order ordinary differential equations are made and applied to the radial Dirac equations. Iterative schemes for the solution of the resulting non-linear amplitude equations are discussed, one for use in the asymptotic region and the other a Newton scheme for continuing the solution closer to the origin. Using these techniques a reliable and efficient program for calculating relativistic scattering phase shifts from ionic potentials has been written. Relativistic Optical Model problems have been ...

Science.gov (United States)

The macroscopic rotation of plasma in a toroidal containment device is an important feature of the equilibrium. Toroidal and poloidal rotation in the high beta tokamak Torus II is measured experimentally by examining the Doppler shift of the 4685.75 A He II line emitted from the plasma. The toroidal flow at an average velocity of 1.6 x 10/sup 6/ cm/sec, a small fraction of the ion thermal speed, moves in the same direction as the toroidal plasma current. The poloidal flow follows the ion diamagnetic current direction, also at an average speed of 1.6 x 10/sup 6/ cm/sec. In view of certain ordering parameters, the toroidal flow is compared with predictions from neoclassical theory in the collosional, Pfirsch-Schluter regime. The poloidal motion, however results from an E x B drift in a positive radial electric field, approaching a stable ambipolar state. This radial electric field is determined from theory by using the measured poloidal velocity. ...

International Nuclear Information System (INIS)

The Moderator Temperature Coefficient of reactivity (MTC) was earlier proven to be properly determined via noise analysis when the neutron noise is measured locally and when the radial average of the moderator temperature noise is used. Nevertheless, measurements revealed that the MTC was correctly estimated on a much narrower frequency band (0.6 - 0.7 Hz) than expected (0.1 - 1.0 Hz). The present paper investigates the effect of the feedback on the MTC determination using this new MTC noise estimator (which could explain the deviation at low frequencies, i.e. between 0.1 - 0.5 Hz) and the effect of the detector time constants (which could explain the deviation at high frequencies, i.e. between 0.7 - 1.0 Hz). For that purpose, a coupled neutronic/thermalhydraulic model of the Ringhals-3 PWR is developed in the frequency-domain, based on a radial 2-dimensional heterogeneous representation of the core. The transfer function of the detectors is ...

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The thermal and heat transfer characteristics of stearic acid during the solidification processes were investigated experimentally in a vertical annulus energy storage system. The temperature distribution and temperature variations with time at different radial positions during the freezing processes were obtained. The thermal characteristics of the stearic acid, including movement of the solid-liquid interface in the radial direction, and the effects of Reynolds number on the heat transfer parameters were studied. The heat flux was estimated by using a simple approximate model. A new copper fin was designed and fixed to the electrical heating rod to enhance the thermal conductivity of the stearic acid. The results show that the new fin can enhance both the conduction and the natural convection heat transfer of the PCM, and the enhancement factor during solidification is estimated to be as high as 250%. The effect of the fin width on the ...

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This paper deals with electron flux densities and electron energy flux densities in positive column discharges. Recent kinetic calculations by Uhrlandt and Winkler have revealed the interesting physical phenomenon of radially inward directed energy flux densities in positive column plasmas. We have used a self-consistent positive column model, based on an accurate and highly detailed Monte Carlo code, to study this effect in more depth. The results of this study show a rather complex physical picture of electron particle and energy flux densities. Electrons with low energies usually exhibit radially outward directed particle and energy flux densities. At energies above the threshold for electronic excitation particle and energy flux densities are usually inward directed. Only close to the wall, at total energies above the wall potential energy, do these flux densities point towards the wall. The thickness of this 'wall loss ...

CERN Document Server

We point out that the moduli sector of the $(2,2)$ string compactification with its nonperturbatively preserved non-compact symmetries is a fertile framework to study global topological defects, thus providing a natural source for the large scale structure formation. Based on the target space modular invariance of the nonperturbative superpotential of the four-dimensional N=1 supersymmetric string vacua, topologically stable stringy domain walls are found. They are supersymmetric solutions, thus saturating the Bogomolnyi bound. It is also shown that there are moduli sectors that allow for the global monopole-type and texture-type configurations whose radial stability is ensured by higher derivative terms.

International Nuclear Information System (INIS)

Muonic-atom energy levels and wave functions are calculated. The results are corrected for nearly all important static effects, including finite nuclear size as produced by a user-specified nuclear charge distribution. Fourth-order Runge-Kutta integration of the radial Dirac equations, with the secant method determining the eigenvalues. Corrections are either included as potentials in the Dirac equations or computed as first-order perturbations. The code assumes spherical symmetry, so that effects of nuclear deformation may be treated only as static first-order perturbations. Dynamic muon-electron and muon-nuclear effects are neglected (the latter are calculated by RURP). (Auth.).

CERN Document Server

We present radial velocity and photometry for four early-type, massive double-lined spectroscopic binaries in the R136 cluster. Three of these systems are eclipsing, allowing orbital inclinations to be determined. One of these systems, R136-38 (O3 V + O6 V), has one of the highest masses ever measured, 57 Mo, for the primary. Comparison of our masses with those derived from standard evolutionary tracks shows excellent agreement. We also identify five other light variables in the R136 cluster which are worthy of follow-up study.

International Nuclear Information System (INIS)

The mass distribution of the Sombrero Galaxy, NGC 4594, is calculated in order to investigate the suspicion that the rotational velocity of the galactic gas does not measure the circular velocity in the galaxy. It is shown that the H II rotation velocities are much less than circular in the central 35 arcsec of the galaxy, and that the suspicion is correct. Thus, the H II rotation velocities cannot be used to measure the mass distribution. The absorption-line rotation curve is used to derive the mass distribution, and it is found that the M/L ratio is nearly constant. It is concluded that the visible matter is self-gravitating at least in the central 180 arcsec. 44 references.

International Nuclear Information System (INIS)

The combined magnetic braking-ambipolar diffusion problem in weakly ionized, rigidly rotating disks is studied. An analytical solution is presented for a disk whose angular velocity and magnetic yield vectors are aligned with the symmetry axis, illustrating the effects of the relative azimuthal drift of neutrals and ions. The effects of radial drift are added, commenting on the ratio of the characteristic ambipolar diffusion and magnetic braking time scales in high-mass and low-mass disks. A numerical calculation is used to show the combined action of these two processes. 31 references.

CERN Document Server

Exact solutions are found for the Chandrasekhar Page angular equation which results when the Dirac equation in a Kerr Newman space time is separated into its radial and angular parts. The solutions turn out to be remarkably simple in form while satisfying the asymptotic conditions deduced earlier. The eigenvalues are found to be the square root of the total angular momentum as first found by Dirac for flat space; supplemented by a term which is the product of the mass of the Dirac particle times the specific angular momentum of the black hole. The additional contribution is what is expected from frame dragging.

International Nuclear Information System (INIS)

A nanoparticle generator based on the principle of electrical discharge (PALAS GFG-1000) was used to produce nanoparticles of different chemical natures. The fractions of electrically neutral particles were then measured by means of a Spectrometre de Mobilite Electrique Circulaire (SMEC, i.e. radial-flow mobility analyzer) for different operating conditions. The experimental results were compared with the theoretical values calculated from the Fuchs extended charge equilibrium model for spherical particles and agglomerates. For the smallest particles (below 20 nm), the deviations observed remain below 10%, and tend towards 20% for larger particles (over 35 nm).

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Toroidal Alfven eigenmodes (TAE) destabilized by the pressure gradient of energetic alpha particles may expel the alpha particles before thermalization. TAE is important for tokamaks, and for helical systems (stellarators) as well. In CHS (compact helical system) TAE localized in the plasma core are destabilized when the plasma current is induced by co-injection of neutral beams. The observed TAE exhibits a ballooning nature. The internal structure of TAE was measured with a soft X-ray detector. The soft X-ray fluctuations level for TAE is too low to obtain the radial profiles of fluctuation intensities. (Tanaka, M.)

International Nuclear Information System (INIS)

The method of augmented plane wave (APW) is used to obtain the band structure of the SmS compound in the semiconductor and metal phases. The noncentral part of the Coulomb electron-electron interaction is taken into account in the first order perturbation theory. In this case the radial part of the wave APW-function is taken as a zero approximation function. A multiplet structure of the excited configuration f"5d, which provides a good description of the X-ray photoelectron spectrum and optical spectrum epsilon_2(#omega#), is obtained. The configuration fd is calculated for the interpretation of the optical absorption spectrum of the samarium monosulfide metal phase. (author).

International Nuclear Information System (INIS)

A large acceptance, high stopping power Bragg curve spectrometer has been developed for use in coincidence experiments with heavy ions. The electron collection fields are radial and position information is obtained from a resistive anode. The detector is 60 cm deep and operates at pressures of up to 2.5 atm of P-10 gas. It is mated to a scattering chamber which allows it to be moved out of plane during coincidence measurements. Factors affecting the performance of the detector are discussed, and results obtained with the detector are presented. (orig.).

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We present high-quality X-ray scattering experiments on pure water taken over a temperature range of 2 to 77 C using a synchrotron beam line at the advanced light source (ALS) at Lawrence Berkeley National Laboratory. The ALS X-ray scattering intensities are qualitatively different in trend of maximum intensity over this temperature range compared to older X-ray experiments. While the common procedure is to report both the intensity curve and radial distribution function(s), the proper extraction of the real-space pair correlation functions from the experimental scattering is very difficult due to uncertainty introduced in the experimental corrections, the proper weighting of OO, OH, and HH contributions, and numerical problems of Fourier transforming truncated data in Q-space. Instead, we consider the direct calculation of X-ray scattering spectra using electron densities derived from density functional theory based on real-space configurations generated with ...

International Nuclear Information System (INIS)

For the study of radiation biology and its application to radiotherapy, the double differential cross section of electron emission from water vapor induced by 6.0 MeV alpha particle beam is measured. The energy spectra of electrons ranging 7- 10000 eV are detected by the electrostatic analyzer and micro channel plate. The measurements are made at angles between 20 and 160 degrees. With use of this data set, the radial dose distribution in water is calculated by using KURBUC code. It is the Monte Carlo type code of the electron transport process, where the track of the electron is simulated through each individual interactions including elastic scattering, ionization cross section and total excitation cross section in case that electrons with certain energy are put in the liquid-density water. In order to understand the effect of radiation when the particle flux is injected in the human body like radiotherapy using accelerator beam, the dose distribution in the ...

International Nuclear Information System (INIS)

A general theoretical approach for the study of the two-dimensional structure of high-n Toroidal Alfven Eigenmodes (TAE) in finite-#beta#, large aspect ratio (R_o/a much-gt 1) tokamak equilibria is presented. Here, n is the toroidal mode number, #beta# = plasma/magnetic pressure, and a(R_o) is the minor (major) radius of the torus. It is shown how the general pseudo-differential boundary value problem for the radial eigenmode structure can be systematically constructed from the local dispersion relation; which is obtained using the ballooning formalism. The TAE modes are characterized by a broad radial envelope, the width of which is independent on the mode number in the general case of monotonic equilibrium profiles. The results on the two-dimensional eigenmode structure are expected to be applicable to drift-type waves. The ballooning transform is generalized here to handle singular eigenfunctions typical of the continuous shear Alfven ...

International Nuclear Information System (INIS)

January, 1992, to October, 1995, sixty-four patients with advanced head and neck cancer underwent head and neck reconstructive surgery using myocutaneous or revascularized flaps; in the same period, all patients were consecutively examined with CT and MRI. Myocutaneous flaps were used in 26 patients: 12 flaps were tubular and 14 linear. Revascularized flaps were used in 38 patients: to repair a large defect in 26 patients (14 latissimus dorsi flaps and 12 temporal muscle flaps) and to repair an oral damage in 12 patients (5 revascularized radial and 7 jejunal flaps). CT and MR images of myocutaneous flaps showed the flaps as fatty areas, repairing large surgical defects, hypodense at CT and hyperintense at MRI, with no post-contrast enhancement. The appearance of revascularized flaps at CT and MRI depends on the characteristics of the structure used to repair the surgical defect: jejunal and radial flaps appeared as mostly fatty thickened ...

Science.gov (United States)

... Accession Number : ADD457408. Title : FIELD CORROSION TESTS FOR COMPARISON OF CORROSIVITY IN JAPAN AND CHINA. ...

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The ab initio pseudopotential method is used to study transient-enhanced-diffusion (TED) related processes. The electronic degrees of freedom are included explicitly, together with the fully self-consistent treatment of the electron charge density. A large supercell and a fine k-point mesh are used to ensure numerical convergence. Such method has been demonstrated to give quantitative description of defect energetic. We will show that boron diffusion is significantly enhanced in the presence of the Si interstitial due to the substantial lowering of the migrational barrier through a kick-out mechanism. The resulting mobile boron can also be trapped by another substitutional boron, forming an immobile and elect rically inactive two-boron pair. Similarly, carbon diffusion is also enhanced significantly due to the pairing with Si interstitial. However, carbon binds to Si interstitial much more strongly than boron does, taking away most Si interstitial from boron at ...

CERN Document Server

We analyse how the structure of the inner curst is influenced by the pairing correlations. The inner-crust matter, formed by nuclear clusters immersed in a superfluid neutron gas and ultra-relativistic electrons, is treated in the Wigner-Seitz approximation. The properties of the Wigner-Seitz cells, i.e., their neutron to proton ratio and their radius at a given baryonic density, are obtained from the energy minimization at beta equilibrium. To obtain the binding energy of baryonic matter we perform Skyrme-HFB calculations with zero-range density-dependent pairing forces of various intensities. We find that the Wigner-Seitz cells have much smaller numbers of protons compared to previous calculations. For the dense cells the binding energy of the configurations with small proton numbers do not converge to a well-defined minimum value which precludes the determination of their structure. We show that for these cells there is a significant underestimation of the ...

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The running data of the super energy saving car on a course with a little difference within 1m in elevation were reported which was developed to pursue the minimum fuel consumption. The super car was featured by length of 2.72m, vehicle running mass of 38.5kg, engine displacement of 42cc and a rear drive tricycle with 2(F) and 1(R). The super car turned 10 times on a racing circuit of 925m a round at 20km/h or more in average speed, repeating engine-driven running and engine-stopped coasting. As a result, the vehicle velocity distribution was slightly affected by tire revolution, while the accelerating resistance was strongly affected by that. With an increase in tire revolution, the maximum accelerating resistance decreased in driven running and its variation converged rapidly in coasting. A total of distance in driven running was only 8% of the whole running one because of probably skilled driving as well as the vehicle performance. The fuel consumption rate also ...

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A shock wave appears when the release of accumulated energy is instantaneous. For instance, it accompanies gunpowder explosion, electric discharge, laser beam convergence, collision of high-speed objects, release of high-pressure gas, and supersonic flight. The shock wave research center of Institute of Fluid Science, Tohoku University, is engaged in researches to elucidate the basics of various shock wave phenomena and to apply the fruit to engineering, science, and medicine. In this report, some examples of recent application studies at the center are described, and the trend of shock wave researches in the future is introduced. The ultimate state of the stagnation point of a nozzle flow simulating a reentry into the atmosphere is produced by shock wave compression in a free piston shock tube which is a ground-borne experimental apparatus. Los Alamos National Laboratory, U.S., succeeded in generating metallic hydrogen of a crystalline structure by subjecting ...

Energy Technology Data Exchange (ETDEWEB)

In the case where sources and receivers are not distributed on a 2-D plane, seismic tomography inversion was studied. In tomography experiments, the existing wells are generally used. In such case, sources and receivers are frequently not distributed on a 2-D plane. The 2.5-D analysis method including 2-D structure and 3-D ray-tracing was thus developed. This method is featured by less memory necessary for ray-tracing calculation, and the same algorithm for velocity determination as 2-D analysis method. In previous methods, since analysis is generally carried out by projecting sources and receivers on a certain assumed 2-D plane, it can derive correct results in the case of constant velocity and straight ray, however, in the other case, it derives incorrect results. Application of 3-D tomography requires a large amount of memory, and falls into poor convergence because of various parameters. The 2.5-D analysis method can avoid these demerits. This analysis method ...

International Nuclear Information System (INIS)

Studying the structure of nanoparticles as a function of their size requires a correlation between the image and the diffraction pattern of single nanoparticles. Nanobeam diffraction technique is generally used but requires long and tedious TEM investigations, particularly when nanoparticles are randomly oriented on an amorphous substrate. We bring a new development to this structural study by controlling the nanoprobe of the Bright and Dark Field STEM (BF/DF STEM) modes of the TEM. The particularity of our experiment is to make the STEM nanoprobe parallel (probe size 1 nm and convergence angle <1 mrad) using a fine tuning of the focal lengths of the microscope illumination lenses. The accurate control of the beam position offered by this technique allowed us to obtain diffraction patterns of many single nanoparticles selected in the digital STEM image. By means of this technique, we demonstrate size effects on the order-disorder transition temperature in CoPt ...

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We will describe recent improvements to the SPEAR reflectometer at the Manuel Lujan Jr. Neutron Scattering Center at Los Alamos. One of the changes consists of wider convergent, incident-beam, collimation to take advantage of optical imaging for specular scattering. In addition, the instrument now views a partially coupled liquid hydrogen moderator as opposed to the decoupled moderator that was previous in-place. While the wavelength distribution is poorer, it matches the time (wavelength) resolution of the reflectometer more closely with the angular resolution. Since the integrated intensity of the partially coupled moderator is higher than the decoupled moderator, we show a similar gain in incident beam flux on the sample without loss of the ability to separate fringes. The increases in intensity from the moderator gain and the improved collimation combine to allow us to measure reflectivities with good statistics down to 10{sup -4} in a matter of minutes and ...

International Nuclear Information System (INIS)

Nuclear energy provides a third of Europe's electricity with nearly no greenhouse-gas emissions. Sustained efforts are now being conducted to harmonize regulations all over Europe through WENRA and to converge on technical nuclear safety practices within the TSO network ETSON (European Technical Safety Organizations Network). In CANDU type NPP the tritiated water occurs by the neutron bombardment of deuterium. The tritiated water vapors imply health hazard (in the critical organs of the body the water presents a 10 day average biological half-life) and the early detection in nuclear plants of tritium emissions is important because the tritiated water vapors have the same characteristics as of atmospheric water vapors. By detecting tritiated vapors, the monitoring system ensures the following objectives: (a) indicates levels of tritium generally due to heavy water leakage, (b) reduces the possibility of health hazard. In order to attain this goal of safety function, ...

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The authors will be conducting an integrated seismic experiment to image the structure of the crust and upper mantle of northern California immediately before and after passage of the Mendocino Triple Junction. The purpose of this representation is to describe the project to other scientists interested in geological and geophysical processes in this region and to solicit input relevant to detailed siting of the funded seismic profiles. The experiment encompasses two field seasons: onshore seismic refraction/wide angle reflection data acquisition along three long profiles scheduled for late summer, 1993; and MCS deep crustal seismic reflection data acquisition accompanied by simultaneous large aperture recording using both ocean bottom and onshore seismographs, tentatively scheduled for summer, 1994. This study represents a component of a long-term, multi-disciplinary effort on the part of many investigators to exploit this well defined system as an in-situ laboratory to study ...

Energy Technology Data Exchange (ETDEWEB)

Smoothness-constrained least-squares technique with ABIC minimization was applied to the inversion of phase velocity of surface waves during geophysical exploration, to confirm its usefulness. Since this study aimed mainly at the applicability of the technique, Love wave was used which is easier to treat theoretically than Rayleigh wave. Stable successive approximation solutions could be obtained by the repeated improvement of velocity model of S-wave, and an objective model with high reliability could be determined. While, for the inversion with simple minimization of the residuals squares sum, stable solutions could be obtained by the repeated improvement, but the judgment of convergence was very hard due to the smoothness-constraint, which might make the obtained model in a state of over-fitting. In this study, Love wave was used to examine the applicability of the smoothness-constrained least-squares technique with ABIC minimization. Applicability of this to ...

International Nuclear Information System (INIS)

Aiming at the non-stationary characteristics of differential pressure fluctuation signals of gas-liquid two-phase flow, and the slow convergence of learning and liability of dropping into local minima for BP neural networks, flow regime identification method based on Singular Value Decomposition (SVD) and Least Square Support Vector Machine (LS-SVM) is presented. First of all, the Empirical Mode Decomposition (EMD) method is used to decompose the differential pressure fluctuation signals of gas-liquid two-phase flow into a number of stationary Intrinsic Mode Functions (IMFs) components from which the initial feature vector matrix is formed. By applying the singular vale decomposition technique to the initial feature vector matrixes, the singular values are obtained. Finally, the singular values serve as the flow regime characteristic vector to be LS-SVM classifier and flow regimes are identified by the output of the classifier. The identification result of four ...

Energy Technology Data Exchange (ETDEWEB)

This work considers the problem of controlling multiple nonholonomic vehicles so that they converge to a scent source without colliding with each other. Since the control is to be implemented on simple 8-bit microcontrollers, fuzzy control rules are used to simplify a linear quadratic regulator control design. The inputs to the fuzzy controllers for each vehicle are the (noisy) direction to the source, the distance to the closest neighbor vehicle, and the direction to the closest vehicle. These directions are discretized into four values: Forward, Behind, Left, and Right, and the distance into three values: Near, Far, Gone. The values of the control at these discrete values are obtained based on the collision-avoidance repulsive forces and the change of variables that reduces the motion control problem of each nonholonomic vehicle to a nonsingular one with two degrees of freedom, instead of three. A fuzzy inference system is used to obtain control values for inputs ...

CERN Document Server

(Abridged) We use 3D SPH calculations with higher resolution, as well as with more realistic viscosity and sound-speed prescriptions than previous work to examine the eccentric instability which underlies the superhump phenomenon in semi-detached binaries. We illustrate the importance of the two-armed spiral mode in the generation of superhumps. Differential motions in the fluid disc cause converging flows which lead to strong spiral shocks once each superhump cycle. The dissipation associated with these shocks powers the superhump. We compare 2D and 3D results, and conclude that 3D simulations are necessary to faithfully simulate the disc dynamics. We ran our simulations for unprecedented durations, so that an eccentric equilibrium is established except at high mass ratios where the growth rate of the instability is very low. Our improved simulations give a closer match to the observed relationship between superhump period excess and binary mass ratio than ...

Energy Technology Data Exchange (ETDEWEB)

The numerous challenges facing the North American electric utility industry were discussed. In addition to competition, electric utilities are faced with low demand growth, public pressure to avoid adding transmission and distribution capacity, and strict environmental requirements. In view of these developments, large central generation additions that have been industry norm until recently, do not always make economic sense in the current environment. Instead, smaller, distributed additions to generating capacity is becoming the new norm. Small-scale on-site generating capacity has the added advantage of reducing the need for expensive high-voltage transmission lines. The Ballard generation system described here is a modular, efficient fuel cell-based solution to implementing distributed power concepts. The system is natural gas fueled, with low noise, vibration and emissions. Apart from its other advantages, it provides ideal convergence opportunity by using the ...

CERN Document Server

This paper describes a study of comparison of global and one-dimensional local optimization methods to operating system scheduler tuning. The operating system scheduler we use is the Linux 2.6.23 Completely Fair Scheduler (CFS) running in simulator (LinSched). We have ported the Hackbench scheduler benchmark to this simulator and use this as the workload. The global optimization approach we use is Particle Swarm Optimization (PSO). We make use of Response Surface Methodology (RSM) to specify optimal parameters for our PSO implementation. The one-dimensional local optimization approach we use is the Golden Section method. In order to use this approach, we convert the scheduler tuning problem from one involving setting of three parameters to one involving the manipulation of one parameter. Our results show that the global optimization approach yields better response but the one- dimensional optimization approach converges to a solution faster than the global ...

Energy Technology Data Exchange (ETDEWEB)

To propose a new design concept of a nuclear reactor used in the space, research has been conducted on the conceptual design of a new nuclear reactor on the basis of the following three main concepts: (1) Thermionic generation by thermionic fuel elements (TFE), (2) reactivity control by rotary reflector, and (3) reactor cooling by liquid metal. The outcomes of the research are: (1) A calculation algorithm was derived for obtaining convergent conditions by repeating nuclear characteristic calculation and thermal flow characteristic calculation for the space nuclear reactor. (2) Use of this algorithm and the parametric study established that a space nuclear reactor using 97% enriched uranium nitride as the fuel and lithium as the coolant and having a core with a radius of about 25 cm, a height of about 50 cm and a generation efficiency of about 7% can probably be operated continuously for at least more than ten years at 100 kW only by reactivity control by rotary ...

International Nuclear Information System (INIS)

The author describes the results of post-test analyses of PANDA transient (M-series) tests M2 and M3. The purpose of the PANDA post-test analysis activity is to demonstrate that TRACG is applicable for the calculation of long-term SBWR containment response to a LOCA. Comparisons between TRACG predictions and test measurements are presented and discussed in the dual context of what the test results show and the capability of TRACG to predict their key features

Energy Technology Data Exchange (ETDEWEB)

Two accelerated aging test procedures are proposed for use on solid dielectric extruded distribution cables under wet conditions. One test method is a fixed time duration test in which the degree of cable specimen aging is assessed in terms of breakdown tests, while the other test method is a time to breakdown test in which the cable specimens are voltage stressed until failure ensues.

Science.gov (United States)

The GEOFLOW I experiment has been successfully performed on the International Space Sta-tion (ISS) in 2008 in the Columbus module in order to study the stability, pattern formation and transition to turbulence in a viscous incompressible fluid layer enclosed in two concentric co-rotating spheres subject to a radial temperature gradient and a radial volumetric force field. The objective of the study is the experimental investigation of large scale astrophysical and geophysical phenomena in spherical geometry stipulated by rotation, thermal convections and radial gravity fields. These systems include earth outer core or mantle convection, differen-tial rotation effects in the sun, atmosphere of gas planets as well as a variety of engineering applications. The GEOFLOW I experimental instrument consists of an experiment insert for operation in the Fluid Science Laboratory, which is part of the Columbus Module of the ISS. It was ...

Science.gov (United States)

Task, Psychomotor Vigilance Test (PVT) Transition to Operations ... Related Tasks (36). Task, Psychomotor Vigilance Test (PVT) on ISS. Common Item(s) ...

International Nuclear Information System (INIS)

The radio, optical, x-ray and gamma-ray nebulae that surround many pulsars are thought to arise from synchrotron and inverse Compton emission. The energy powering this emission as well as the magnetic fields and relativistic particles are supplied by a 'wind' driven by the central object. The inner parts of the wind can be described using the equations of MHD, but these break down in the outer parts, when the density of charge carriers drops below a critical value. This paper reviews the wave properties of the inner part (striped wind), and uses a relativistic two-fluid model (cold electrons and positrons) to re-examine the nonlinear electromagnetic modes that propagate in the outer parts. It is shown that in a radial wind, two solutions exist for circularly polarized electromagnetic modes. At large distances one of them turns into a freely expanding flow containing a vacuum wave, whereas the other decelerates, corresponding to a confined flow.

Energy Technology Data Exchange (ETDEWEB)

A simple tube-in-tube heat exchanger system for thermal energy storage employing stearic acid as PCM has been investigated. The performance and heat transfer characteristics of such a system were studied. Phase transition temperature range and times were measured and the speed of the phase transition front was computed. The melting front was found to move in the radial direction inward as well as in the axial direction from the top toward the bottom of the phase change material PCM tube. The speed of the melting front is enhanced by a convection heat transfer mechanism in the melted PCM. The heat transfer rate and, consequently, phase transition time can be altered by changing the water inlet temperature to the heat exchanger. In addition, a faster phase transition is realized by placing the heat exchanger in a horizontal position rather than a vertical one. (Author)

British Library Electronic Table of Contents (United Kingdom)

Despite advances in polymer and drug technology, the underlying stent platform remains a key determinant of clinical outcome. A clear understanding of stent design and the differences between various stent platforms are of increasing importance for the interventional cardiologist. Reduction in stent strut thickness has been associated with improved stent deliverability, improved procedural outcome, and lower rates of subsequent restenosis. Newer-generation 316L-SS stent designs have enabled reduced strut thickness while retaining radial strength and minimizing recoil, but with significant loss of radiopacity, leading to reduced visibility. Cobalt chromium alloys have enabled a reduction in stent strut thickness to around 80?90 mm while retaining modest radiopacity, but due to higher elasti...

CERN Document Server

Peculiar velocities induce apparent line of sight displacements of galaxies in redshift space, distorting the pattern of clustering in the radial versus transverse directions. On large scales, the amplitude of the distortion yields a measure of the dimensionless linear growth rate \\ff of fluctuations, which is related to the cosmological density \\Omega and the linear bias factor b in linearly biassed standard cosmology by \\ff \\approx \\Omega^{0.6} /b. To make the maximum statistical use of the data in a wide angle redshift survey, and for the greatest accuracy, the spherical character of the distortion needs to be treated properly, rather than in the simpler plane parallel approximation. In the linear regime, the redshift space correlation function is described by a spherical distortion operator acting on the true correlation function. It is pointed out here that there exists an operator, which is essentially the logarithmic derivative with respect to pair ...

Energy Technology Data Exchange (ETDEWEB)

This paper describes in an apparatus for absorbing a beam of concentrated solar energy and which includes a cavity receiver with an inlet for transmission thereinto of solar radiation, a protective apertured shield means about the inlet. It comprises: rigid support means fixed to the periphery of the inlet and projecting radially inwardly therefrom to define a generally central aperture area through which the solar radiation can pass into the cavity receiver; and non-structural blanket means spread over the rigid support means between the periphery of the inlet and the aperture area, the material having a high temperature capability and providing for infra-red radiation insulation, while remaining relatively cool when subjected to solar radiation.

Energy Technology Data Exchange (ETDEWEB)

In this article, the ability of artificial neural networks in prediction of separation in steady two dimensional boundary layer flows is studied. Data for network training is extracted from numerical solution of an ODE obtained from Von Karman integral equation with approximate one parameter Pohlhousen velocity profile. As an appropriate neural network, a two layer radial basis generalized regression artificial neural network is used. The results shows good agreements between the overall behavior of the flow fields predicted by the artificial neural network and the actual flow fields for some cases. The method easily can be extended to unsteady separation and turbulent as well as compressible boundary layer flows. (author)

International Nuclear Information System (INIS)

A steadily increasing part of comminution is nowadays carried out by tube ball mills. Our investigations are a first step to a possible tuning of material distribution with mechanical stress characteristic of the grinding media charge, that is essential for a high efficiency of grinding. A BOND mill filled with porcelain balls as grinding media and labelled corundum (Au-198) as grinding material was used to measure the distribution of material over the cross-section. The evaluation was made by linear interpolation between all combinations of adjacent measuring points to calculate all coordinates with equal intensity for each selected level of activity. Two plottings showing the dependence of material distribution on the rotating speed are presented. (author).

Energy Technology Data Exchange (ETDEWEB)

The validity is given to the newly proposed two weighting {delta}f scheme (Wang et al., Research Report of National Institute for Fusion Science NIFS-588, 1999) for collisional or neoclassical transport calculations, which can solve the drift kinetic equation taking account of effects of steep plasma gradients, large radial electric field, finite banana width, and the non-standard orbit topology near the axis. The marker density functions in weight equations are successively solved by using the idea of {delta}f method and a hierarchy of equations for weight and marker density functions is obtained. These hierarchy equations are solved by choosing an appropriate source function for each marker density. Thus the validity of the two weighting {delta}f scheme is mathematically proved. (author)

Energy Technology Data Exchange (ETDEWEB)

In a new series of modulated electron cyclotron heating (MECH) on RTP the MECH power was deposited either on-axis or off-axis in plasmas with different values of the plasma current (I{sub p}). Besides confirming all previous MECH results on RTP, the new data can be simulated by assuming a radial profile of the incremental diffusivity ({chi}{sup inc}) that is constant ({chi}{sup inc} < 1 m{sup 2}/s) inside the sawtooth region, makes a sharp step near the inversion radius, and has an offset parabolic profile elsewhere with a value of {chi}{sup inc} {approx} 6 m{sup 2}/s at r/a {approx} 0.6. No significant dependence of {chi}{sup inc} on q{sub a} is observed apart from the position of the transition from low to high {chi}{sup inc}. (author) 5 refs., 4 figs.

Energy Technology Data Exchange (ETDEWEB)

Modern tubular type pumps commonly have lubricated radial bearings which require no compressed water supply and reduce the servicing requirements. Problems that may possibly result from entrained sand in the pumped fluid were solved with the development of ceramic Residur {sup trademark} bearngs in the early eighties. (orig.) [German] In zunehmendem Masse werden Rohrgehaeusepumpen mit foerdermediumgeschmierten Radiallagern ausgestattet, da dies z.B. neben dem Wegfall einer ansonsten notwendigen Druckwasserversorgung auch einen deutlichen reduzierten Wartungsaufwand nach sich zieht. Den Problemen durch eine moegliche Sandbeladung des Foerdermedium wurde bereits durch die Entwicklung der keramischen Residur {sup trademark} -Lager Anfang der 80er Jahre Rechnung getragen. (orig.)

British Library Electronic Table of Contents (United Kingdom)

Because the state of a free-floating space robot model is uncertain and sudden changes in the model parameters might undermine the stability of the system, this paper proposes a control strategy based on a variable structure neural integrated controller. This scheme does not need a precise space robot model, making use of the radial basis function neural network ability approach to learn about an uncertain model. The network weights are adjusted online in real-time. During the early period of the control phase and parameter changes, the variable structure controller compensates for the uncertain model which the neural network could not learn well. It also creates global asymptotic stability for the whole closed-loop system. Simulation results show that the controller can handle bad changea...

British Library Electronic Table of Contents (United Kingdom)

All-atom molecular dynamics simulations were used to study the morphology of polymer/inorganic composite particles prepared by heterocoagulation. The results were also compared to those of our previous study of the preparation of TiO2/poly(acrylic acid-co-methyl methacrylate) and Fe3O4/polystyrene composite particles. In the simulation system, polymer or inorganic particles were simulated by surface-charge-modified C60 or Na atoms. Through a combination of analysis of the radial distribution functions of charged atoms and snapshots of the equilibrated structure, three kinds of particle distributions were observed under different conditions. When the polymer and inorganic particles had opposite surface charges and their sizes were very different, the composite morphology showed a core-shell...

International Nuclear Information System (INIS)

Engineering details of a high voltage driven corona-plasma ozone generator are described. The plasma diode of generator has coaxial cylindrical geometry with cathode located inside anode. Cathode is made of a large number of radial gas nozzles arranged on central tubular mast which admits oxygen gas. The sharp endings of the nozzles along with a set of corona rings create the high electric field at the cathode required for formation of dense corona plume responsible for O_3 evolution. A model of coronal plasma generation and ozone production is presented. The plasma formation is strongly dependent on the electric field and temperature in side diode where a high electron density in a low temperature negative corona is suited for high ozone yields. These are established by suitable regulation of A-K gap, voltage, oxygen pressure, and cathode-nozzle population.

British Library Electronic Table of Contents (United Kingdom)

In the emerging restructured power system, the congestion management (CM) has become extremely important in order to ensure the security and reliability of the system. In addition to this, lack of CM can impose a hindrance in electricity trading. This paper presents a novel, growing radial basis function neural network (GRBFNN)-based approach for CM. For achieving CM, Nodal congestion price (NCP) forecasting is performed in real time competitive power market. NCP forecasting is an effective way of price-based preventive CM as it directly indicates the presence as well as the severity of the congestion in the system. In present paper, GRBFNN has been developed for NCP forecasting dividing the whole power system into various congestion zones. An unsupervised learning vector quantization (VQ)...

CERN Document Server

The controlled growth of nanowires (NWs) with dimensions comparable to the Fermi wavelengths of the charge carriers allows fundamental investigations of quantum confinement phenomena. Here, we present studies of proximity-induced superconductivity in undoped Ge/Si core/shell NW heterostructures contacted by superconducting leads. By using a top gate electrode to modulate the carrier density in the NW, the critical supercurrent can be tuned from zero to greater than 100 nA. Furthermore, discrete sub-bands form in the NW due to confinement in the radial direction, which results in stepwise increases in the critical current as a function of gate voltage. Transport measurements on these superconductor-NW-superconductor devices reveal high-order (n = 25) resonant multiple Andreev reflections, indicating that the NW channel is smooth and the charge transport is highly coherent. The ability to create and control coherent superconducting ordered states in ...

International Nuclear Information System (INIS)

We have calculated the electronic structure of Eu for the bcc, hcp, and fcc crystal structures for volumes near equilibrium up to a calculated 90 GPa pressure using the augmented-plane-wave method in the local-density approximation. The frozen-core approximation was used with a semi-empirical shift of the f-states energies in the radial Schroedinger equation to move the occupied 4f valence states below the #GAMMA#_1 energy and into the core. This shift of the highly localized f-states yields the correct europium phase ordering with lattice parameters and bulk moduli in good agreement with experimental data. The calculated superconductivity properties under pressure for the bcc and hcp structures are also found to agree with and follow a T_c trend similar to recent measurement by Debessai et al.

International Nuclear Information System (INIS)

The effect of Kerr nonlinearity on an Airy beam is investigated by using the nonlinear Schroedinger equation. Based on the moments method, the evolution of the Airy beam width in the rms sense is analytically described. Numerical simulations indicate that the central parts of the major lobe of the Airy beam initially give rise to radial compression during propagation in a focusing medium, even though the rms beam width broadens. The partial collapse of the center parts of the major lobe of the beam appear below the threshold for a global collapse. The evolutions of the field distributions of the Airy beams are different during propagation in different Kerr media while the beams still travel along the parabolic trajectory just as the beam propagates in free space.

Energy Technology Data Exchange (ETDEWEB)

Improved separation of heavier material from a dispersoid of gas and heavier material entrained therein is taught by the method of this invention which advantageously uses apparatus embodied in an inertial separator having rotary partition means comprising wall members dividing a housing into a plurality of axially-extending through passages arranged in parallel. Simultaneously with the helical transit of a moving stream of the dispersoid through the parallel arrangement of axially-extending through passages at a constant angular velocity, the heavier material is driven radially to the collecting surfaces of the rotational wall members where it is collected while the wall members are rotating at the same angular velocity as the moving stream. The plurality of wall members not only provides an increased area of collecting surfaces but the positioning of each of the wall members according to the teaching of this invention also results in a shortened time-of-flight to ...

British Library Electronic Table of Contents (United Kingdom)

The homogeneity of a helium dielectric barrier discharge, working at atmospheric pressure and containing oxygen as contaminant, is assessed by mapping the spatial distribution of oxygen metastable atoms in relation to the uniformity of surface properties. Tunable diode laser absorption spectroscopy is used to monitor the time evolution of the absorption coefficient corresponding to the oxygen metastable atoms on the 35S2 level, as a function of the laser absorbing path, whereas bi-dimensional Abel transform is used to obtain local information on the space distribution of the metastable atoms in the discharge. The radial distribution of the surface properties is investigated using atomic force microscopy, contact angle measurement and X-ray photoelectron spectroscopy. The results show that ...

International Nuclear Information System (INIS)

From self-consistent band structure calculations using the 'augmented plane wave'(APW) method, the density of states can be decomposed into local partial (according to azimuthal quantum number l) components, the l-character densities. Within the APW formalism the intensity of X-ray emission spectra is determined by radial transition probabilities and l-character densities of such valence states, which reside inside the same atomic sphere as the core vacancy and whose quantum number l differs by +-1 from the one corresponding to the core state. By taking into account lifetime broadening of the core and valence states and also the instrumental broadening the computed spectra (non-metal K-, vanadium K- and Lsub(III)-spectra) agree well with experiment. (orig.).

British Library Electronic Table of Contents (United Kingdom)

BackgroundWave reflection during the systole increases left ventricular (LV) pressure, tension-time index (TTI) and myocardial oxygen requirement. The purpose of this study was to extract that component of extra myocardial oxygen requirement that is due to early systolic wave reflection, define it as wasted effort (?Ew), and examine its relationship to LV hypertrophy (LVH).MethodsRadial artery pressure waveforms were recorded using applanation tonometry and central aortic waveforms generated in 98 patients with untreated hypertension. Aortic augmentation index (AIa), wave reflection amplitude (i.e., aortic augmented pressure (AG)) and systolic duration (ED?Tr), ejection duration (ED) and round-trip travel time of the pressure wave (Tr) were calculated from the aortic waveform, a...

Energy Technology Data Exchange (ETDEWEB)

A gas core fission reactor that utilizes americium in place of uranium is examined for potential utilization as a nuclear rocket for space propulsion. The isomer [sup 242m]Am with a half life of 141 years is obtained from an (n, [gamma]) capture reaction with [sup 241]Am, and has the highest known thermal fission cross section. We consider a 7500 MW reactor, whose propulsion characteristics with [sup 235]U have already been established, and re-examine it using americium. We find that the same performance can be achieved at a comparable fuel density, and a radial size reduction (of both core and moderator/reflector) of about 70%.

British Library Electronic Table of Contents (United Kingdom)

In this study, a two-stage support-vector-regression optimization model (TSOM) is developed for the planning of municipal solid waste (MSW) management in the urban districts of Beijing, China. It represents a new effort to enhance the analysis accuracy in optimizing the MSW management system through coupling the support-vector-regression (SVR) model with an interval-parameter mixed integer linear programming (IMILP). The developed TSOM can not only predict the city's future waste generation amount, but also reflect dynamic, interactive, and uncertain characteristics of the MSW management system. Four kernel functions such as linear kernel, polynomial kernel, radial basis function, and multi-layer perception kernel are chosen based on three quantitative simulation performance criteria [i.e....

British Library Electronic Table of Contents (United Kingdom)

This work addresses the problem of estimating the direction-of-arrival (DOA) of two sources using an array of sensors. This problem is mostly useful in radar applications, where we have few targets at each range bin. Super-resolution algorithms, such as maximum likelihood (ML) estimation and multiple signal classification (MUSIC), have been applied to this problem, but the former involves high computation efforts, while the later has poor estimation performance for coherent sources. In this work, we propose a DOA estimation network, named RBF-AML, which combines the approximated ML (AML) estimator and a radial basis function (RBF) neural network (NN). In the proposed RBF-AML network, the entire two dimensional DOA space is divided into multiple sectors covered by RBF experts. The AML funct...

International Nuclear Information System (INIS)

A large acceptance, high stopping power, Bragg curve spectrometer has been developed for use in coincidence experiments with heavy ions. The electron collection fields are radial and position information is obtained from a resistive anode. The detector is 60 cm deep and operates at pressures of up to 2.5 atm of P-10 gas. It is mated to a scattering chamber which allows it to be moved out of plane during coincidence measurements. The detector design was aided by the results of computer simulations of the electron collection process in the detector, and of the signal processing in the electronics. The signals from the Bragg curve spectrometer are recorded in a waveform digitizer and the Bragg peak height, range, position and pileup rejection information are determined from software analysis of the recorded signals. Factors limiting the performance of the detector are discussed, and results obtained with the detector are presented. (orig.).

Science.gov (United States)

PMID:17477142