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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

CERN Document Server

We present an alternative, Bayesian method for large-scale reconstruction from observed peculiar velocity data. The method stresses a rigorous treatment of the random errors and it allows extrapolation into poorly sampled regions in real space or in k-space. A likelihood analysis is used to determine the fluctuation power spectrum, followed by a Wiener Filter (WF) analysis to obtain the minimum-variance mean fields of velocity and mass density. Constrained Realizations (CR) are then used to sample the statistical scatter about the WF mean field. The WF/CR method is applied as a demonstration to the Mark III data with 1200 km/s, 900 km/s, and 500 km/s resolutions. The main reconstructed structures are consistent with those extracted by the POTENT method. A comparison with the structures in the distribution of IRAS 1.2Jy galaxies yields a general agreement. The reconstructed velocity ...

J-STORE (Japan)

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International Nuclear Information System (INIS)

Published in summary form only.

International Nuclear Information System (INIS)

Environmental computer science is a new partial discipline of applied computer science, which makes use of methods and techniques of information processing in environmental protection. Thanks to the inter-disciplinary nature of environmental problems, computer science acts as a mediator between numerous disciplines and institutions in this sector. The handbook reflects the broad spectrum of state-of-the art environmental computer science. The following important subjects are dealt with: Environmental databases and information systems, environmental monitoring, modelling and simulation, visualization of environmental data and knowledge-based systems in the environmental sector. (orig.).

Science.gov (United States)

Sep 1, 2011 ... 2005. Computer simulation modeling of recreation use: current status, case studies, and future directions. Gen. Tech. Rep. RMRS-GTR-143. ...

Energy Technology Data Exchange (ETDEWEB)

We successfully reproduce one of the French pipe whip experiments with the computer code WIPS. The WIPS results are in excellent agreement with the experimental data and the French computer code TEDEL. This justifies the use of its pipe element in conjunction with its U-bar element in a simplified method of impact analyses.

KoreaScience (Korea)

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... Union (INTAS), Brussels (Belgium) Science and Technology Center in Unkraine,

International Nuclear Information System (INIS)

Published in summary form only.

CERN Document Server

Computing with cells

International Nuclear Information System (INIS)

The results for development of methods and computer programs for integrated optimization of parameters of perspective fast reactors are given. The possibilities of the program for the reactor campaign calculation are analysed. This program is based on utilisation of the Bubnov-Galerkin method and Wigner disturbance theory. The possibility of application of approximation methods for the optimization researches is discussed. The results of development of the programs for complex reactor computations with account of control rods system and change of physical parameters in the reactor campaign are discussed. (author).

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Computer tomography used in the diagnosis of tumours is described in the light of particularly great diagnostic difficulties in children. Computer tomography was applied in 12 cases. A high diagnostic value of this method was demonstrated, which makes possible a more accurate diagnosis of the position of the tumour, its size, and expanding tendency. The possibility of estimating healthy tissues and organs, and those with pathological changes on the basis of differences in their density with a detection threshold at 0.5% density difference facilitates not infrequently preoperative diagnosis raising the value of the method.

International Nuclear Information System (INIS)

The FLAPW (full-potential linearized-augmented plane-wave) method is one of the most accurate first-principles methods for determining electronic and magnetic properties of crystals and surfaces. Until the present work, the FLAPW method has been limited to systems of less than about one hundred atoms due to a lack of an efficient parallel implementation to exploit the power and memory of parallel computers. In this work we present an efficient parallelization of the method by division among the processors of the plane-wave components for each state. The code is also optimized for RISC (reduced instruction set computer) architectures, such as those found on most parallel computers, making full use of BLAS (basic linear algebra subprograms) wherever possible. Scaling results are presented for systems of up to 686 silicon atoms and 343 ...

International Nuclear Information System (INIS)

Several computer assisted processing and display methods are evaluated using a series of 100 normal brain scintigrams, 50 of which have had single 'mathematical tumours' superimposed. Using a standard rating system, or in some cases quantitative estimation, LROC curves are generated for each method and compared. (author).

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A new microdensitometry method for quantitative assessment of bone mineral content using Fuji computed radiography (FCR) was developed and the results were compared with those obtained by the conventional film-screen method. Using both methods, X-ray pictures of the 2nd metacarpal bone were taken with a reference aluminum step wedge in nine normal subjects and nine parameters representing the width and density of bone marrow and cortex were calculated in middle of the bone shaft. Interobserver reproducibility assessed for three parameters was significantly higher in the FCR method than the conventional one. The value of {Sigma}GS computed by the FCR method, that is equivalent to the net bone density of the transverse section of the shaft, showed higher correlation with the one obtained by computed tomography in ...

Science.gov (United States)

Jul 24, 2008... (9) coupled multi-disciplinary methods, (10) computational simulation of low cost component fabrication, (11) thermal electrical equivalence ...

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Various physics applications involve the computation of the standard hypergeometric function {sub 2}F{sub 1} and its derivatives. Because it is not an intrinsic in the common programming languages, automatic differentiation tools will either differentiate through the code that computes {sub 2}F{sub 1} if that code is available or require the user to provide a hand-written derivative code. We present options for the derivative computation in the context of an ionization problem and compare the approach implemented in the Diamant library to standard methods.

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Optimization methods are applied to complex problems power systems, economics, and geodesy. Transformation methods and conjugated gradient methods are used to solve the constrained problems in power systems and economics. Conjugated gradient methods are used to solve the unconstrained geodesy problem. Broad applications of the transformation methods are emphasized. In the geodesy problem, the computational efficiency of the Fletcher-Reeves method for optimization of quadratic functions is emphasized. In this problem special storage schemes were used. The method of solution of the economics problem is compared with Beale's method.

UK PubMed Central (United Kingdom)

This paper proposes a novel method for computing linear basis images from tensor-valued image data. As a generalization of the nonnegative matrix factorization, the proposed method aims to approximate...Full Text Available

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A method is presented to derive the absolute dimensions of early-type detached binaries by combining the observed parameters with results of evolutionary computations. The method is used to obtain the absolute dimensions of nine close binaries. We find that most systems have an initial masss ratio near 1.

International Nuclear Information System (INIS)

Dilatation of the azygos vein is usually due to increased pressure or flow, rarely is it diopathic. Another cause is so-called continuation of the azygos in cases of absence of the hepatic segment of the inferior vena cava. The method of choice for the investigation of azygos dilatation nowadays is computer tomotgraphy. Anomalies of the inferior vena cava can be recognised in this way unequivocally by a non-invasive method. Computer tomography frequently shows important additional abnormalities (e.g. situs inversus, polysplenia), since it demonstrates all organs situated in the plane of section. (orig.).

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X-ray diffraction enhanced imaging (DEI) is one of X-ray phase-contrast imaging methods, which is applied to inspect internal structures of weakly absorbing low-Z samples. The key problem of the DEI is how to extract phase information which is expressed by refraction-angle images from a series of DEI images measured in different positions of the rocking curve of the analyzer. Three effective extraction methods are presented in this paper: the statistical geometric-optics-approximation method, the maximum refraction-angle method and the Gaussian curve fitting method. They are compared with the existing methods, such as the D. Chapman's geometric optics approximation method and the multiple-images statistical method. A 2D computer simulation experiment is performed to draw comparisons of these ...

International Nuclear Information System (INIS)

It is shown that the extended softening in k space of the [111] transverse acoustic phonon in Nb_3Sn seen recently by neutron measurements is in agreement with the predictions of a phenomenological Landau description of the structural phase transition in the A-15 compounds. This indicates the feasibility of a calculation of the partial phonon density of states of modes directly coupled to the order parameter driving the structural transition, as a function of temperature.

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Computer Security and the Web

British Library Electronic Table of Contents (United Kingdom)

In this paper we present a new efficient sixth-order scheme for nonlinear equations. The method is compared to several members of the family of methods developed by Neta (1979) [B. Neta, A sixth-order family of methods for nonlinear equations, Int. J. Comput. Math. 7 (1979) 157-161]. It is shown that the new method is an improvement over this well known scheme.

CERN Document Server

The advent of rapid, reliable and cheap computing power over the last decades has transformed many, if not most, fields of science and engineering. The multidisciplinary field of optimization is no exception. First of all, with fast computers, researchers and engineers can apply classical optimization methods to problems of larger and larger size. In addition, however, researchers have developed a host of new optimization algorithms that operate in a rather different way than the classical ones, and that allow practitioners to attack optimization problems where the classical methods are either

International Nuclear Information System (INIS)

The current trend towards the increased use of risk assessment in the regulation of nuclear power plants will inevitably result in changes in the analysis of fire protection systems and the methods of analysis. Before fire protection can be regulated on a risk basis, a consensus must be reached on a number of issues. One key issue is what types of computational tools will be allowable for analyzing fire events, and what types of scenarios those tools will be approved for use. Reaching this consensus will require an understanding of the types of computational tools available and their inherent advantages and disadvantages. To aid with this understanding, three different methods of fire simulation are applied to an oil pool fire test in the HDR (Heiss Dampf Reaktor) containment test facility. These methods are a hand calculation, the zone model code CFAST (Consolidated Model of Fire ...

International Nuclear Information System (INIS)

A Quantitative Computed Tomography (QCT) method, simplifying the well-known technique proposed by Genant (1982) and applied to a standard third generation whole body CT scanner is described. This technique was applied in the measurement of the trabecular bone which has high sensitivity for metabolic changes. The BMC (Bone Mineral Content) measured in different groups of subjects (healthy postmenopausal patients versus women with postmenopausal osteoporosis) showed a highly significant difference (p<0.001). The precision of repositioning (coefficient of variation 1.8% to 2.3%, obtained in healty male patients) and the good, linear relationship computed from the phantom values, minimize measurement errors. Since this method is quickly applied and involves low-dose radiation-exposure, it could be introduced in the clinical study of metabolic bone diseases.

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Even before Egyptian times, fiber and paper-based methods were used to manage time, tasks, and priorities. Papyrus and paper were effective in their time, but now is the time for the even more effective computer-based methods of time management. This study compares paper and computer methods of the management of time, tasks, and priorities. Discussed are recommended strengths of off-the-shelf software for time management. Integrated software is recommended. A case study of the use of idea processing software to manage publication tasks and priorities is examined. Illustrated--for classroom-style training--are uses of a computer to enhance the quality and increase the efficiency of the coordination of publications from conception and research to printing and issuance. 3 refs., 43 figs.

International Nuclear Information System (INIS)

A method for the determination of stereotaxic coordinates in radiography, e.g. angiography, pneumoencephalography or digital vascular radiography, is described. A special localization frame containing radiopaque structures and scales defines a diagnostic coordinate system. This frame is fixed to the X-ray-table prior to the radiographic procedure and two projections are obtained at arbitrary angles to each other. The focus-film distances do not have to be fixed. The target coordinates are then determined either by a simple graphical procedure or with the use of a digitizing x-y-table, by a computer. With the computer method the films are placed on the digitizing table and the target and a few reference points are marked using a cursor. From the relative positions the computer calculates the coordinates. With the special head fixation system, coordinates of structures visualized in ...

Science.gov (United States)

The ultimate compressive strength of 36 thoracolumbar vertebrae was determined experimentally. In addition, the trabecular bone mineral content was measured by single energy quantitative computed tomography. The areas of fractured endplates were also determined by computed tomography. The results show that a linear relationship exists between the compressive strength and the product of bone density and endplate area. These data allow an in vivo prediction of vertebral body strength using a noninvasive method with a standard error of estimate amounting to less than 0.95 kN. PMID:3212488

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A spectral element method embodying Large Eddy Simulation based on Re- Normalization Group theory for simulating Sub Grid Scale viscosity was chosen for this work. This method is embodied in a computer code called NEKTON. NEKTON solves the unsteady, 2D or 3D,incompressible Navier Stokes equations by a spectral element method. The code was later extended to include the variable density and multiple reactive species effects at low Mach numbers, and to compute transport of large particles governed by inertia. Transport of small particles is computed by treating them as trace species. Code computations were performed for a number of test conditions typical of flow past a deep tube bank in a boiler. Results indicate qualitatively correct behavior. Predictions of deposition rates and deposit shape evolution also show correct qualitative behavior. ...

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It is reported on examination-technical possibilities with craniocerebral Computer Tomography in the peri- and postnatal period. Some typical tomographic images from a 17 1/2 months period in our own patient material of 327 children are demonstrated. The special advantages of this new technical-extensive method are: exact diagnoses, observation possibility of the longitudinal section, and the absolute harmlessness to the child.

CERN Document Server

We consider the numerical discretization of the time-domain Maxwell's equations with an energy-conserving discontinuous Galerkin finite element formulation. This particular formulation allows for higher order approximations of the electric and magnetic field. Special emphasis is placed on an efficient implementation which is achieved by taking advantage of recurrence properties and the tensor-product structure of the chosen shape functions. These recurrences have been derived symbolically with computer algebra methods reminiscent of the holonomic systems approach.

International Nuclear Information System (INIS)

The Feynman-#alpha# method was applied to measurement of reactivity and the ability of this method for a real-time reactivity monitoring system was assessed. In the experiment, all measured data by BF_3 detectors were stored in a multi-channel scaler controlled by a personal computer, and they were analyzed to obtain prompt neutron decay constant (#alpha#) and reactivity with consideration of dead time of detector. It was found that #alpha# could be obtained almost in a real-time even for both positive and negative reactivities by the present experimental technique. (author).

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Fractal dimensions of three different samples of lanthanum ferrite were computed using single adsorption method. The fractal Dubinin-Radushkevitch isotherm was used to fit directly the experimental nitrogen adsorption data. Avnir-Jaroniec method for fractal dimension determination was also used. Low and intermediate fractal dimensions were obtained according to BET specific surface areas.

British Library Electronic Table of Contents (United Kingdom)

We investigate an application of the method of fundamental solutions (MFS) to the one-dimensional inverse Stefan problem for the heat equation by extending the MFS proposed in [5] for the one-dimensional direct Stefan problem. The sources are placed outside the space domain of interest and in the time interval (-T,T). Theoretical properties of the method, as well as numerical investigations, are included, showing that accurate and stable results can be obtained efficiently with small computational cost.

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The stability-enchancing two-step (SETS) method has been used successfully in the Transient Reactor Analysis Code (TRAC) for several years. The method consists of a basic semi-implicit step combined with a stabilizer step that, taken together, eliminate the material Courant stability limit associated with standard semi-implicit numerical methods. This approach toward stability requires significantly fewer computational operations than a fully implicit method, but currently maintains the first-order accuracy in space and time of its semi-implicit predecessors.

UK PubMed Central (United Kingdom)

Computational methods for determining the secondary structure of RNA sequences from given alignments are currently either based on thermodynamic folding, compensatory base pair substitutions or both....Full Text Available

Science.gov (United States)

The continuing rapid increase in available computing power has not reduced the importance of efficient methods of optical system assessment for automatic lens design. On the contrary, the new capabilities simply show that truly automatic optical design wi...

UK PubMed Central (United Kingdom)

By use of a new computer-assisted u.v.-spectrophotometric assay method, the kinetic parameters of the reaction catalysed by Bacillus licheniformis 749/C beta-lactamase were re-examined and the mode...Full Text Available

UK PubMed Central (United Kingdom)

The computational fluid dynamics methods for the limited flow rate and the small dimensions of an intracranial artery stenosis may help demonstrate the stroke mechanism in intracranial atherosclerosis....Full Text Available

Energy Technology Data Exchange (ETDEWEB)

A new method for computing petroleum reserves which takes into account the volumetric elasticity of stratal petroleum and a porous medium of a collector is examined based on the example of developing petroleum beds of Cretaceous horizon of the Groznenskiy region.

Energy Technology Data Exchange (ETDEWEB)

Lining shafts and placing them in a given strata needs extensive computation. Therefore, it is natural that the use of electronic computing and of numerical methods in this mining area started early. For shafts being sunk in non-stable water-bearing strata the deformations and stresses of the freezing wall are analysed. The complex system of an outer lining in the shaft sinking stage is designed with regard to the elastic support of the strata. In cases of strata-embedded systems the tubbing liner can be shaped as the loads require. Here analysis of safety against buckling is very important. If a sliding shaft is built as a composite construction, there are advantages in determining the distribution of the material by numerical methods. The analysis of stability is possible only by numerical methods and could not be solved otherwise. The Finite Element Method ...

UK PubMed Central (United Kingdom)

BackgroundSelf-administered computer-assisted blood donor screening strategies may elicit more accurate responses and improve the screening process.MethodsRandomized...Full Text Available

International Nuclear Information System (INIS)

Two methods for computation of real, virtual and quasistationary energy eigenvalues are considered: summation of divergent perturbation series, solution of integral equations for t matrix on physical and nonphysical sheets of energy. The results of energy computation for s-, p- and d-states in potentials of a screened Coulomb type are presented. It is shown on an example of the Yukawa potential that the energy eigenvalues given by both these methods coincide with high precision. As an illustration the positions of real (deuteron) and virtual (singlet deuteron) poles of the np-scattering amplitude are calculated. For Yukawa type potentials the new theorem of symmetry for bound and virtual levels is discussed.

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In recent years very good experience has been accumulated with self-supporting low-pressure blades. Today blades are constructed up to a length of 1060 mm (50 Hz) or 1360 mm (25 Hz). In this process modern computational methods from aerodynamics and also from mechanics are employed. The further development of computer technology also permits new methods, for example the use of curved fixed blading as well as the optimization of existing designs. (orig.).

International Nuclear Information System (INIS)

The single specimen unloading compliance technique has become the preferred method for evaluating J-integrals. It involves data acquisition and analysis using a computer. This paper describes in detail the development of a simple experimental system and related software that can be used in a laboratory equipped with a microcomputer and with access to a minicomputer. The effects of loading rate, test temperature, specimen geometry and material composition can be readily evaluated using this system. The results on a pressure vessel steel and an #alpha#-#beta# titanium alloy are discussed in Part II. (author).

Science.gov (United States)

The results of a computational scheme of Rose (a method for calculating solutions of parabolic equations with free boundary, Math. Comp., 14: 249-256(1960)) are compared with the known analytic solution of a single-phase Stefan problem with constant boundary temperature. Rose's scheme was implemented in FORTRAN on a DEC PDP-10. Computations were performed for Stefan numbers St = 0.01, 0.1, 1, 10, and 100. Three relative mesh sizes (..gamma.. = DT/(DX)/sup 2/ = 1/2, 1/6, and 1/25) were used. For each St, the relative mesh size had very little effect on accuracy. However, taking ..gamma.. = 1/25 resulted in dramatically increased computing time. The relative errors of temperature were large near the phase change front. 11 figures, 5 tables.

CERN Document Server

Obtaining the set of cosmological parameters consistent with observational data is an important exercise in current cosmological research. It involves finding the global maximum of the likelihood function in the multi-dimensional parameter space. Currently sampling based methods, which are in general stochastic in nature, like Markov-Chain Monte Carlo(MCMC), are being commonly used for parameter estimation. The beauty of stochastic methods is that the computational cost grows, at the most, linearly in place of exponentially (as in grid based approaches) with the dimensionality of the search space. MCMC methods sample the full joint probability distribution (posterior) from which one and two dimensional probability distributions, best fit (average) values of parameters and then error bars can be computed. In the present work we demonstrate the application of another stochastic ...

Science.gov (United States)

We propose a combined migration velocity analysis and imaging method based on Kirchhoff integral migration and reverse time migration, using the residual curvature analysis and layer stripping strategy to build the velocity model. This method improves the image resolution of Kirchhoff integral migration and reduces the computations of the reverse time migration. It combines the advantages of efficiency and accuracy of the two migration methods. Its application in tunnel seismic prediction shows good results. Numerical experiments show that the imaging results of reverse time migration are better than the imaging results of Kirchhoff integral migration in many aspects of tunnel prediction. Field data show that this method has efficient computations and can establish a reasonable velocity model and a high quality imaging section. Combination with geological ...

International Nuclear Information System (INIS)

It is a traditional method to diagnose electron-cyclotron-resonance (ECR) plasma source, using a single probe to measure the current-voltage curve of the plasma, based on which and theoretic formula the plasma density can be computed. The article adopts a Langmuir probe having a role of emission electrons to measure two different current-voltage curves with and without emission. It is ease to get the plasma potential via the inflexion of the two curves and compute directly various physical quantities by the assistant computer, such as electron temperature, electron/ion density, plasma potential etc. The deviation is about percent 1.8 between the measurement results by traditional and the new method, but the latter has higher efficiency. (authors)

British Library Electronic Table of Contents (United Kingdom)

An innovative hybrid powder prepared using computer simulation allowed development of a new foundation having a fine, smooth texture that has never been achieved before. The optical structure/design of the powder was based on the results of measurements and analyses conducted on the optical characteristics of a baby's delicate skin, which is the envy of many women. To obtain the optimal optical characteristics, the finite differential time domain (FDTD) method for solving Maxwell's differential equation by difference and time domain was applied to the computer simulation method. For synthesis of the hybrid powder based on the optical model, a proprietary shape regulation coating technology was used in which flaky substrates were coated with microspherical forms of barium sulfate crystals. ...

International Nuclear Information System (INIS)

Objective: To establish a computer program for rapid calculation of internal committed effective close through inhalation and ingestion pathways under radiological emergency. Methods: Visual Basic 6.0 is used to compile the generic procedures of internal committed effective dose by inhalation and ingestion in IAEA-TECDOC-1162, Generic Procedures for Assessment and Response during a Radiological Emergency. Results: The assessment methodology of internal committed effective dose by inhalation and ingestion under radiological emergency in the report IAEA-TECDOC-1162 can be coded into a computer program. Conclusions: This research provides a rapid method of assessment for internal committed effective dose by inhalation and ingestion under radiological emergency, and it may provide needed dosimetry data for treatment under emergency response. (authors)

Science.gov (United States)

A computational fluid dynamics (CFD) is coupled with a computational structural dynamics (CSD) to simulate the unsteady rotor flow with aeroelasticity effects. An unstructured upwind Navier-Stokes solver was developed for this simulation, with 2nd order time-accurate dual-time stepping method for temporal discretization and low Mach number preconditioning method. For turbulent flows, both the Spalart-Allmaras and Menter's SST model are available. Mesh deformation is achieved through a fast dynamic grid method called Delaunay graph map method for unsteady flow simulation. The rotor blades are modeled as Hodges & Dowell's nonlinear beams coupled flap-lag-torsion. The rotorcraft computational structural dynamics code employs the 15-dof beam finite element formulation for modeling. The structure code was validated by comparing the natural ...

CERN Document Server

This paper proposes the use of particle swarm optimization method (PSO) for finite element (FE) model updating. The PSO method is compared to the existing methods that use simulated annealing (SA) or genetic algorithms (GA) for FE model for model updating. The proposed method is tested on an unsymmetrical H-shaped structure. It is observed that the proposed method gives updated natural frequencies the most accurate and followed by those given by an updated model that was obtained using the GA and a full FE model. It is also observed that the proposed method gives updated mode shapes that are best correlated to the measured ones, followed by those given by an updated model that was obtained using the SA and a full FE model. Furthermore, it is observed that the PSO achieves this accuracy at a computational speed that is faster than that by the ...

Energy Technology Data Exchange (ETDEWEB)

Methods are discussed for optimization of organizational model of longwall mining. Operations at a working face, their duration, number of miners, miner qualifications are analyzed. The so-called method for allocation of heteregeneous resources is used. Using the method optimum organizational models of working faces are constructed. The models consider working conditions, coal output, personnel, miner qualifications, duration of various operations and of idletime, and safety regulations. A computer code developed by the author for optimizing organizational models of longwall mining is described. 9 refs.

Energy Technology Data Exchange (ETDEWEB)

A method and apparatus is provided for detecting explosives by thermal imaging. The explosive material is subjected to a high energy wave which can be either a sound wave or an electromagnetic wave which will initiate a chemical reaction in the explosive material which chemical reaction will produce heat. The heat is then sensed by a thermal imaging device which will provide a signal to a computing device which will alert a user of the apparatus to the possibility of an explosive device being present.

Science.gov (United States)

In this work, energy-based features for gear fault diagnosis and prediction are proposed. The instantaneous energy density is shown to obtain high values when defected teeth are engaged. Three methods are compared in terms of sensitivity, reliability and computation effectiveness. The Wigner Ville distribution is contrasted to the wavelet transform and the newly proposed empirical mode decomposition scheme. It is shown that all three methods are capable of a reliable prediction. An empirical law, which relates the energy content to the crack magnitude is established.

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This book contains nomographs for analysis and design of signalized intersections and thoroughly explains how to use them. The nomographs simplify and reduce the work that otherwise would have to be done by hand. The nomograph method for computing capacity has a significant advantage over computerized methods: it provides insight into the interaction between the various factors in the solution process for design analysis.

Energy Technology Data Exchange (ETDEWEB)

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.

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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.)

Energy Technology Data Exchange (ETDEWEB)

The solution of the governing steady transport equations for momentum, heat and mass transfer in flowing fluids can be very difficult. These difficulties arise from the nonlinear, coupled, nonsymmetric nature of the system of algebraic equations that results from spatial discretization of the PDEs. In this manuscript the authors focus on evaluating a proposed nonlinear solution method based on an inexact Newton method with backtracking. In this context they use a particular spatial discretization based on a pressure stabilized Petrov-Galerkin finite element formulation of the low Mach number Navier-Stokes equations with heat and mass transport. The discussion considers computational efficiency, robustness and some implementation issues related to the proposed nonlinear solution scheme. Computational results are presented for several challenging CFD benchmark problems as well as two large scale 3D flow ...

International Nuclear Information System (INIS)

The results of X-ray and neutron diffraction experiments on molten alkali halides in which some data of our experiments by X-ray diffraction such as those of molten LiCl, NaCl, KCl, LiBr and KBr are included were summarized. The first peak positions in the radial distribution function in molten alkali halides by X-ray or neutron diffraction experiments are always longer than those by computer simulations and the differences of 0.1 -- 0.3 A exceed the experimental error. It seems to be due to the deformation of the electron shell. In the computer simulation, the shell model which has the spherical deformation was expected to have more closer value of the first peak position to the experimental one than the rigid ion model by taking the polarization of ions. However, no change in the first peak position was found. Therefore, the non-spherical deformation of electron shell at the point where ions are in contact with each other has to be taken into ...

International Nuclear Information System (INIS)

In this paper, a time-domain equivalent circuit method is applied to solve dispersion of coupled-cavity travelling-wave tube (CCTWT). First, the time-domain circuit equations of CCTWT coupled-cavity chain are deduced from the equivalent circuit model. Then, the equations are solved numerically by fourth-order Runge-Kutta method and a program CTTDCP is developed using MATLAB. Last, a L-band CCTWT is calculated using CTTDCP and the cavity pass-band of this tube is computed to be 1.08-1.48 GHz, which is consistent with the experimental results and the simulation results of electromagnetic code and demonstrates the validity of the time-domain equivalent circuit method. In addition, a new design method which uses the equivalent circuit method and electromagnetic simulation together to optimize the cold cavity characteristics of CCTWT is proposed. (authors)

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Xeroradiography (XR) was retrospectively compared with a newly developed computed radiography (FCR) for diagnostic availability for breast cancer. FCR provides with the image processed by a computer. Subjects were 65 breast cancer patients for XR and 51 for FCR. Both methods were performed preoperatively. No significant difference was observed in distribution of age between the two groups but the average tumor size in XR group was larger than that in FCR group. Tumor shadow appeared in 44 of 65 xeromammograms (67.7%) and in 34 of 51 computed radiograms (66.7%). Microcalcification was detected in 27 of 65 xeromammograms (41.5%) and in 21 of 51 computed radiograms (41.2%). Consequently, diagnosis of breast cancer could be achieved in 47 of 65 patients (72.3%, established: 39, suspective: 8) through XR and in 41 of 51 (80.4%, established: 33, suspected: 8) through FCR. Thus FCR is ...

International Nuclear Information System (INIS)

The tremendous heat generated in a computer chip or very large scale integrated circuit raises many challenging issues to be solved. Recently, liquid metal with a low melting point was established as the most conductive coolant for efficiently cooling the computer chip. Here, by making full use of the double merits of the liquid metal, i.e. superior heat transfer performance and electromagnetically drivable ability, we demonstrate for the first time the liquid-cooling concept for the thermal management of a computer chip using waste heat to power the thermoelectric generator (TEG) and thus the flow of the liquid metal. Such a device consumes no external net energy, which warrants it a self-supporting and completely silent liquid-cooling module. Experiments on devices driven by one or two stage TEGs indicate that a dramatic temperature drop on the simulating chip has been realized without the aid of any fans. The higher the ...

Energy Technology Data Exchange (ETDEWEB)

As the surroundings of objects of oil exploration grow more complicated, seismic survey methods have turned 3-dimensional and, in this report, several models are examined using the 3-dimensional simulation technology. The result obtained by the conventional wave tracking method is different from actual wavefields, and is unrealistic. The difference method among the fullwave modelling methods demands an exorbitantly long computation time and high cost. A pseudospectral method has been developed which is superior to the difference method, and has been put to practical use thanks to the advent of parallel computers. It is found that a 3-dimensional survey is mandatory in describing faults. After examining the SEG/EAGE Salt model, it is learned that the salt is well-developed and that 3-dimensional depth migration is ...

Energy Technology Data Exchange (ETDEWEB)

In the Wajima lung cancer screening program conducted under the auspices of Kanazawa University Hospital, Fuji Computed Radiography (FCR) was utilized in a new chest radiography trial. The results of the screening program are that the necessity of repeat examinations due to poor image quality are less common and the method enables detection of small pulmonary nodular shadows which are possibly candidates for surgery. Oblique chest X-ray with FCR is remarkably effective for the detection and the identification of small lesions. However, the disadvantage of slow processing and high cost must be fully satisfied if FCR is to become a new imaging modality for mass screening.

International Nuclear Information System (INIS)

In order to stress the role of computed tomography (CT) in the evaluation of benign spinal osteoblastoma, the authors examined by CT 10 patients with surgically and histologically proved osteoblastomas of the spine. Basing on surgical and histopathological findings CT proved to be a very important method for attesting the presence of the tumors (usually showed by radiographic examination), and specially for their staging and follow-up. CT in fact showed the real extent of the tumor into the spinal canal and towards the paraspinal soft tissues, and allowed the aerly detection of post surgical relapses. The authors conclude that CT is a primary diagnostic modality for preoperative planning and follow-up of benign osteoblastoma.

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)

British Library Electronic Table of Contents (United Kingdom)

In this paper, we propose and implement a website of post-processing system for finite element analysis (WebDFEA). Finite element analysis is a computer-aided engineering tool and is popular for static/dynamic structure analysis. It includes three processing systems where post-processing system is to graphically demonstrate the analysis result of a structure model analyzed by finite element method. WebDFEA performs as a website. It is cross-platform because it can auto-detect a client computer platform and auto-download proper OpenGL API for drawing computer graphics. It can draw precise graphics on webpage which can be free controlled by the mouse as a manner in professional software. A database server is involved to store finite element model data and its analysis result. The graphic use...

CERN Document Server

An effective computer program for three dimensional relativistic hydrodynamical model has been developed. It implements a new approach to the early hot phase of relativistic heavy-ion collisions. The computer program simulates time-space evolution of nuclear matter in terms of ideal-fluid dynamics. Equations of motions of hydrodynamics are solved making use of finite difference methods. Commonly-used algorithms of numerical relativistic hydrodynamics RHLLE and MUSTA-FORCE have been applied in simulations. To speed-up calculations, parallel processing has been made available for solving hydrodynamical equations. The test results of simulations for 3D, 2D and Bjorken expansion are reported in this paper. As a next step we plan to implement the hadronization algorithm by implementing the continuous particle emission for freeze-out and comparing it with Cooper-Frye formula.

Science.gov (United States)

We have developed a novel laser ray-tracing method to measure aberrations in optical systems. It consists of delivering narrow laser pencils (by a laser scanner), recording the spots that are formed on the image plane (with a CCD camera), and computing the position of each centroid. This approach could be considered an experimental (approximate) implementation of standard numerical ray tracing. Several tests and experiments, including a direct comparison with a Hartmann-Shack wave-front sensor, provided highly satisfactory results that confirmed the validity of the method and revealed potential advantages. PMID:18073906

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The task of selecting reliable computer programs to simulate the performance of passive solar buildings has been assigned by the CEC to a specialized sub-group, the Modelling Sub-Group. This group has selected a detailed program for large computers, which has been commissioned and run by each participant. It has also given a reference for the analysis of a set of simple models, i.e. for mini/micro computers, pocket calculators and manual methods. These simulation techniques have been analyzed by answering an original questionnaire, making test runs of the models with building and climatic data, and comparing the results obtained with the large program. The best manual method has been included in the Passive Solar Handbook prepared by the Passive Solar Working Group. The MSG has also established a comparative table of all the selected simplified models, in order to make the designer ...

International Nuclear Information System (INIS)

Computed tomography (CT) of the thorax shows early promise of important diagnostic advances. We believe that CT often provides information superior to that provided by standard roentgenographic techniques, is capable of significantly influencing patient management, and in selected instances, offers unique information not available by other methods. Computed tomography permits the imaging of mediastinal structures not possible with conventional roentgenographic methods and can diagnose with certainty benign mediastinal conditions such as pericardial cysts and focal or diffuse accumulations of fat. It is ideal for detecting pleural abnormalities and for displaying underlying parenchymal disease in patients with complex pleuroparenchymal shadows on conventional films. Pulmonary metastases unseen on the plain chest film can be detected with greater sensitivity than by any other method. ...

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This volume covers planning, design, and data analysis. It offers statistical methods for designing environmental sampling and monitoring programs as well as analyzing the resulting data. Statistical sample survey methods to problems of estimating average and total amounts of environmental pollution are presented in detail. The book also provides a broad array of statistical analysis methods for many purposes...numerous examples...three case studies...end-of-chapter questions...computer codes (showing what output looks like along with its interpretation)...a discussion of Kriging methods for estimating pollution concentration contours over space and/or time...nomographs for determining the number of samples required to detect hot spots with specified confidence...and a description and tables for conducting Rosner's test to identify outlaying (usually large) pollution ...

Energy Technology Data Exchange (ETDEWEB)

Much of the current technology on 3D-prestack depth migration is based on the Kirchhoff method and the traveltime information needed for this purpose is obtained by the ray-theory approximation. The main motivation driving these options is to reduce computations but it can also have an adverse effect on the quality of results. Experience with real data indicates that the corresponding poststack data migrated by the reverse-time method often yields superior results. Considerable computational efficiency can be obtained by employing nonuniform coarse grid spacing during the reverse-time migration. We followed this strategy for developing a parallel scheme for doing 3D- prestack depth migration. However, we worked only on a small subset of shot gathers whose determined by the Quasi-Monte Carlo method. The results were indistinguishable from those obtained by using a much larger ...

Energy Technology Data Exchange (ETDEWEB)

Development of a strategy for forecasting river ice breakup and jamming on the Saint John River in New Brunswick was described. Methods used to identify ice jam-prone areas by simple temperature-based methods to fairly complex computer models using site specific data, were summarized. Recent technological advances in developing forecasts, including the NWRI probe for remotely measuring ice jam thickness, the RIVJAM model for determining stages upstream of an ice jam, and computational procedures for estimating the thrust exerted by ice jams against bridges, were also reviewed. Criteria and recommendations for river ice breakup and ice jamming for the Saint John River were provided. (Abstract only).

CERN Document Server

Limiters are nonlinear hybridization techniques that are used to preserve positivity and monotonicity when numerically solving hyperbolic conservation laws. Unfortunately, the original methods suffer from the truncation-error being first-order accurate at all extrema despite the accuracy of the higher-order method. To remedy this problem, higher-order extensions were proposed that relied on elaborate analytic and geometric constructions. Since extremum-preserving limiters are applied only at extrema, additional computational cost is negligible. Therefore, extremum-preserving limiters ensure higher-order spatial accuracy while maintaining simplicity. This report presents higher-order limiting for (i) computing van Leer slopes and (ii) adjusting parabolic profiles. This limiting preserves monotonicity and accuracy at smooth extrema, maintains stability in the presence of discontinuities and under-resolved ...

International Nuclear Information System (INIS)

Fuji Computed Radiography (FCR) was evaluated for detection of intracardiac calcification as compared with conventional radiography in 77 patients. Intracardiac calcification was found in 37 patients (left coronary artery: 31, right coronary artery: 11, valve: 9) on cine-fluorography. The sensitivity for detecting these calcified foci with FCR was higher than conventional screen-film method. Especially, sensitivity for detecting left coronary artery calcification with FCR was significantly higher than conventional method (71 %, 32 %) (p < 0.01), Fine anatomical details of calcification were well shown on FCR. Chest radiography using FCR is of great use for detection of intracardiac calcification. (author).

Energy Technology Data Exchange (ETDEWEB)

An approximate solution was proposed in which a sensitivity analysis by the storage and release of heat was performed for the subject issues and in which an operating method was thereby determined for the equipment constituting the system by means of a linear programming. Accordingly, a heat storage type energy supply system for a district cooling and heating was taken up as a concrete object to be examined. This system consisted of a gas turbine generator, initial power receiving equipment, gas boiler, electric heat pump for ice heat storage, cooling tower, heat exchanger, steam absorbing refrigerating machine, ice heat storage tank, cold and warm water heat storage tank, etc. As a result of comparison between the proposed method and the resolving method, the former showed -0.92 to 2.58% in the increase in the operating cost compared with the latter. A case where the operating cost of the resolving ...

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This paper describes the method to estimate the true formation temperature using temperature recovery logging data after the well reach to total depth (T.D.). The method designated as ''Curve-fitting method (CFM)'' is based on mathematical model proposed by Middleton (1979, 1982). The accuracy and applicability of this method are evaluated with several field data and compared advantageously with the Horner-plot method. Then, real-time data acquisition system including interpretation software has also been successfully developed. As a conclusion, the followings are confirmed: (1) The developed CFM can be applicable to the estimation of the true formation temperature even using 24 hours temperature recovery data, although the Horner-plot method might need up to 120 hours recovery data, usually. (2) Though depending upon the ...

Energy Technology Data Exchange (ETDEWEB)

Finite element method is one of the bases for numerical solutions to engineering problems. Complex engineering problems using finite element analysis typically imply excessively large computational time. Parallel supercomputers have the potential for significantly increasing calculation speeds in order to meet these computational requirements. This paper predicts parallel NIKE3D performance on the Kendall Square Research (KSR1) system. The first part of the prediction is based on the implementation of parallel Cholesky (U{sup T}DU) matrix decomposition algorithm through actual computations on the KSRI multiprocessor system, with 64 processors, at Oak Ridge National Laboratory. The other predictions are based on actual computations for parallel element matrix generation, parallel global stiffness matrix assembly, and parallel forward/backward substitution on the BBN TC2000 ...

Energy Technology Data Exchange (ETDEWEB)

Eddy current inspection methods are widely used for the nondestructive evaluation (NDE) of tubular products. Specifically, the sensors and instrumentation are designed to detect and characterize changes in a material's electrical and magnetic properties produced by the presence of discontinuities. A recent major enhancement in eddy current inspection technology has been the development of computer interfacing for data collection, analysis, and display. This breakthrough has led to multiple-frequency testing, eddy current imaging, and automated data interpretation systems that significantly enhance both capabilities and reliability of the eddy current inspection. In addition to the clear advantages in data processing, computer interfacing also permits the design and creation of unique sensors that further enhance eddy current inspection capabilities. Perhaps the most promising area of computer ...

Energy Technology Data Exchange (ETDEWEB)

To determine the diagnostic accuracy of iofetamine hydrochloride I 123 (IMP) with single photon emission computed tomography in Alzheimer's disease, we studied 58 patients with AD and 15 age-matched healthy control subjects. We used a qualitative method to assess regional IMP uptake in the entire brain and to rate image data sets as normal or abnormal without knowledge of subjects'clinical classification. The sensitivity and specificity of IMP with single photon emission computed tomography in AD were 88% and 87%, respectively. In 15 patients with mild cognitive deficits (Blessed Dementia Scale score, less than or equal to 10), sensitivity was 80%. With the use of a semiquantitative measure of regional cortical IMP uptake, the parietal lobes were the most functionally impaired in AD and the most strongly associated with the patients' Blessed Dementia Scale scores. These results indicated that IMP ...

International Nuclear Information System (INIS)

The use of computer codes based on Monte Carlo methods to perform criticality calculations has become common-place. Although results frequently published in the literature report calculated k_e_f_f values to four decimal places, people who use the codes in their everyday work say that they only believe the first two decimal places of any result. The lack of confidence in the computed k_e_f_f values may be due to the tendency of the reported standard deviation to underestimate errors associated with the Monte Carlo process. The standard deviation as reported by the codes is the standard deviation of the mean of the k_e_f_f values for individual generations in the computer simulation, not the standard deviation of the computed k_e_f_f value compared with the physical system. A more subtle problem with the standard deviation of the mean as reported by the codes is that all the k_e_f_f ...

Energy Technology Data Exchange (ETDEWEB)

The use of nondestructive evaluation (NDE) methods is proposed for characterization of transuranic (TRU) waste stored at the Radioactive Waste Management Complex. These NDE methods include real-time x-ray radiography, real-time neutron radiography, x-ray and neutron computed tomography, thermal imaging, container weighing, visual examination, and acoustic measurements. An integrated NDE system is proposed for characterization and certification of TRU waste destined for eventual shipment to the Waste Isolation Pilot Plant in New Mexico. Methods for automating both the classification waste and control of a complete nondestructive evaluation/nondestructive assay system are presented. Feasibility testing of the different NDE methods, including real-time x-ray radiography, and development of automated waste classification techniques are covered as part of a five year effort designed to ...

Energy Technology Data Exchange (ETDEWEB)

A procedure for code Verification by the Method of Manufactured Solutions (MMS) is presented. Although the procedure requires a certain amount of creativity and skill, we show that MMS can be applied to a variety of engineering codes which numerically solve partial differential equations. This is illustrated by detailed examples from computational fluid dynamics. The strength of the MMS procedure is that it can identify any coding mistake that affects the order-of-accuracy of the numerical method. A set of examples which use a blind-test protocol demonstrates the kinds of coding mistakes that can (and cannot) be exposed via the MMS code Verification procedure. The principle advantage of the MMS procedure over traditional methods of code Verification is that code capabilities are tested in full generality. The procedure thus results in a high degree of confidence that all coding mistakes which prevent ...

Energy Technology Data Exchange (ETDEWEB)

In this paper the newly developed discrete-time adaptive sliding mode control method is proposed and applied to the power system stabilization problem. In contrast to the conventional continuous-time sliding mode controller, the proposed method is developed in the discrete-time domain and based on the input/output measurements instead of the continuous-time and the full-states feedback, respectively. Because the proposed control method has the adaptivity property in addition to the natural robustness property of the sliding mode control, it is possible to design the power system stabilizer which can overcome both the minor variations of the parameters of the power system and the diverse operating conditions and faults of the power system. Mathematical proof and the various computer simulations are done to verify the performance and stability of the proposed method. (author). 14 ...

Science.gov (United States)

This dissertation reports on the application of numerical optimization techniques as applied to fuel cell simulation and design. Due to the "multi-physics" inherent in a fuel cell, which results in a highly coupled and non-linear behavior, an experimental program to analyze and improve the performance of fuel cells is extremely difficult. This program applies new optimization techniques with computational methods from the field of aerospace engineering to the fuel cell design problem. After an overview of fuel cell history, importance, and classification, a mathematical model of solid oxide fuel cells (SOFC) is presented. The governing equations are discretized and solved with computational fluid dynamics (CFD) techniques including unstructured meshes, non-linear solution methods, numerical derivatives with complex variables, and sensitivity analysis with adjoint methods. Following ...

Energy Technology Data Exchange (ETDEWEB)

A generalized approach to the analysis of the effects of transmission line faults on natural gas transmission pipelines has been developed and is presented in this report. A state of the art user-friendly computational tool has been developed and verified for the analysis of interference between electrical power lines and nearby buried or above-ground pipelines. This computer program, ECCAPP, is distinguished by its ability to model and analyze accurately complex, realistic interactions between pipelines and power lines, using easily obtained input data. The final report consists of three volumes. An independent fourth volume was also developed to simplify the installation of the ECCAPP software. This report, volume 1, contains the theory upon which the ECCAPP computer program is based. A parametric analysis and graphical charts have been formulated using ECCAPP to permit estimates to be made in the field or during ...

Energy Technology Data Exchange (ETDEWEB)

Production decline-curve analysis is accepted for prediction of future performance of oil and gas wells and fields. One type of decline-curve analysis involves the hyperbolic-decline-curve equation. The challenge with this equation is to determine simultaneously three parameters. The new method creates a computer spreadsheet containing a set of production data. Then, the specific arrangement of cells and columns containing data and/or formulas allows for statistical fits of the data. Finally, setting-up the nonlinear solver allows for optimization of the three parameters by maximization of the square of the regression coefficient. Eight field cases demonstrated the repeatable and rapid curve-fitting of the method.

Energy Technology Data Exchange (ETDEWEB)

The automatic interpretation of apparent resistivity curves from horizontally layered earth models is carried out by the curve-fitting method in three steps: (1) the observed VES data are interpolated at equidistant points of electrode separations on the logarithmic scale by using the cubic spline function, (2) the layer parameters which are resistivities and depths are predicted from the sampled apparent resistivity values by SALS system program and (3) the theoretical VES curves from the models are calculated by Ghosh's linear filter method using the Zhody's computer program. Two soundings taken over Takenoyu geothermal area were chosen to test the procedures of the automatic interpretation.

Energy Technology Data Exchange (ETDEWEB)

Diffusion of radon in a bed of activated charcoal is described by diffusion equations. An analytical solution of these equations is presented for the case of constant radon concentration in the atmosphere. The solutions are given separately for short term and long term exposure. An analytical form of the calibration constant f for long term exposure and constant radon concentration in air, was found. A numerical method and computer code based on the method of finite elements is developed for the case of variable radon concentration in air. This program simulates radon adsorption by the activated charcoal bed, enabling determination of sensitivity. The dependence of sensitivity on different parameters, such as temperature, thickness of the charcoal, etc. was studied using this program. (orig.) 10 refs.

International Nuclear Information System (INIS)

A computer code based on Nodal expansion method has been developed for solving two groups three dimensional diffusion equation. This code can be used for fuel management and time average core calculation. Explicit Xenon and fuel temperature estimation are also incorporated in this code. TAPP-4 phase-B physics experimental results were analyzed using this code and a code based on FD method. This paper gives the comparison of the observed data and the results obtained with this code and FD code. (author)

International Nuclear Information System (INIS)

27 cases including 7 outpatients, underwent intraarterial DSA using 4-F nylon catheter, by transbrachial arterial approach. Much of DSAs were performed in Fuji Computed Radiography (FCR), which has high spatial resolution. In all cases, image quality satisfied clinical demands. No major complication occured in this series. Transbrachial arterial digital subtraction angiography is excellent and safe method for screening of vascular disease. (author).

Energy Technology Data Exchange (ETDEWEB)

Information is presented concerning new trends in licensing; seismic considerations and system structural behavior; TMI-2 risk assessment and thermal hydraulics; statistical assessment of potential accidents and verification of computational methods; issues with respect to improved safety; human factors in nuclear power plant operation; diagnostics and activities in support of recovery; LOCA transient analysis; unresolved safety issues and other safety considerations; and fission product transport.

Energy Technology Data Exchange (ETDEWEB)

Classical molecular dynamics simulations are carried out to investigate the salvation shell exchange kinetics of potassium ion in bulk water, chloroform, and carbon tetrachloride. The reactive flux method is used to compute the dissociation rates. The influence of the solvent on the reaction rates and kinetic properties of this exchange process will be discussed. Comparison will be also be made to the prediction of the Grote-Hynes theory.

International Nuclear Information System (INIS)

In developing new receptor-site specific brain imaging agents labeled with I-123 for single photon emission computed tomography (SPECT), an analog of raclopride, 3-["1"2"5I]-iodo-N-[(1-ethyl-2-pyrrolidinyl)-methyl]-2-hydroxy-6-me-thoxy benzamide (IBZM), was prepared using a method similar to that reported for raclopride and its derivatives. (author).

Energy Technology Data Exchange (ETDEWEB)

The aim of this study concerns the use of numerical methods for the resolution of the Reynolds Averaged Navier Stokes equations adapted to the simulation of the cooling of the trailing edge of a stator in a high pressure turbine. These methods, based on the elsA solver developed at ONERA, use a four steps Runge Kutta time discretization scheme and a Jameson centered space discretization scheme. The scheme is applied through a finite volume approach on control volume centered on the cells of a multi-block structured mesh. Turbulence is simulated either through the algebraic Michel model, or through the one-transport-equation Spalart-Allmaras model, or through the two-transport-equations k 1, k {omega} and k {epsilon} models, and through ASM model. A simulation of the flow in a bidimensional stator, without cooling, is carried out. The cooling, which is realized with trailing edge slots, is then simulated on a bidimensional stator. Because the ...

Energy Technology Data Exchange (ETDEWEB)

The macroscopic behavior of magnetostrictive materials results from domain evolutions occurring at a microscopic scale. The author shows how to compute magnetization and magnetostriction curves by appraising the behavior of the underlying microstructures. The method hinges on an averaging device (Young measures), which allows one to pass from the microscopic to the macroscopic scale. He takes into account the kinematical constraints on the accommodation of elastic effects, and he highlights the role of material symmetry in the selection of energetically optimal microstructures.

International Nuclear Information System (INIS)

Both the accuracy and real-time are quite strictly required for the RCS thermal-hydraulic model of the simulation of nuclear power station. So, a large amount of reasonable simplifications should be carried on. The author introduces the RCS thermal-hydraulic model of the full scope simulator of Daya Bay Nuclear Power Station, and emphasizes on the fundamental hypotheses and computation method of its kernel part--DEFI programme.

Energy Technology Data Exchange (ETDEWEB)

The workshop focused on strategies for promoting and developing engineering level transonic flutter prediction techniques. The technology of transonic aerodynamics is currently undergoing rapid development. Significant progress is being made to solve the inherently nonlinear equations describing unsteady motions of wings in transonic flow, while the availability of reliable and efficient computational methods will greatly enhance the ability to predict the aeroelastic behavior of modern aircraft operating under transonic flow conditions.

Science.gov (United States)

The jet in cross flow (JICF) is a basic flowfield which is relevant to a wide variety of applications which are described to provide context for JICF investigations. Material consistent with the scope of topics presented at the 72nd AGARD Fluid Dynamics Panel Meeting and Symposium on Computational and Experimental Assessment of Jets in Cross Flow on 19-22 April 1993 in Winchester, U.K. is summarized. The JICF research was divided into three time periods: (1) early research - up to 1970, (2) research during the 1970's, and (3) research since 1980. The following areas of experimental activity are discussed; the definition of an effective correlation parameter; the jet flowfield including the jet trajectories, cross-section shape, and jet induced pressures; the effects of jet deflection angle, nozzle shape, pressure ratio, velocity decay, and temperature; and the effect of confined flowfield, ground effects, multiple jets, and adjacent surface geometry. In addition, ...

Energy Technology Data Exchange (ETDEWEB)

Conventional methods for calculating electricity losses in pipe-type cable systems rely heavily on data measured in lower-voltage systems in the 1950s. With the new technique developed in this study, engineers can compute power losses more precisely for cables of various configurations and voltage ratings.

Wastenet

... 1 (2008) Algorithms - Open Access Journal Algorithms (ISSN 1999-4893; CODEN: ALGOCH), an open access journal of computer science, theory, methods and interdisciplinary applications, data and information systems, software engineering, artificial intelligence, automation and control systems, is published online quarterly by MDPI. - free for readers, with low publishing fees paid by authors or their institutions High visibility: indexed in leading indexing and abstracting databases....

Energy Technology Data Exchange (ETDEWEB)

Development of a number of original 3-D migration methods and algorithms is described. The computational efficiency of these algorithms is demonstrated by implementing them on vector and parallel supercomputers. Two-dimensional post-stack and pre-stack depth migration algorithms in the frequency - space domain using implicit finite difference method were also developed and implemented on a parallel computer, and adapted for applications that range from deep crustal imaging of seismic wavefields that involve wide ranging travel times and frequencies. All implicit finite difference migration algorithms were highly prallelized . The one pass 3-D post-stack depth migration algorithm was extensively used for imaging of seismic monitoring data from Cold Lake, Alberta. Experience shows that it provides the right trade-off between accuracy and computational efficiency. A new formulation of ...

International Nuclear Information System (INIS)

Pipe whip restraints are used in nuclear power plants in order to limit the consequences of ruptured pipe whip effects and are thus an important part of the plant safety concept. The design of these devices is based on the choice of adequate construction and computational analysis supported by experimental investigation. Pipe whip restraints should, by means of deforming components, be able to absorb the energy of a ruptured pipe accelerated by the fluid reaction force. Since the elastic deformation of the restraint material is not sufficient for this purpose, or would result in excessive anchor loads, pipe whip restraints must generally be designed to work in the plastic range. Two types of restraints are presented in this paper, including the description of their mode of operation, design and computation. A comparison and critical evaluation of the calculation methods presently available are also given. The range of ...

Science.gov (United States)

Jun 16, 2011 ... The research is part of a team effort to help the hardwood sawmill industry automate with computer vision systems, and computer-aided or ...

International Nuclear Information System (INIS)

Combining the approaches given by Baldwin [Baldwin D et al. Symbolic computation of exact solutions expressible in hyperbolic and elliptic functions for nonlinear PDEs. J Symbol Comput 2004;37:669-705], Peng [Peng YZ. A polynomial expansion method and new general solitary wave solutions to KS equation. Comm Theor Phys 2003;39:641-2] and by Schuermann [Schuermann HW, Serov VS. Weierstrass' solutions to certain nonlinear wave and evolution equations. Proc progress electromagnetics research symposium, 28-31 March 2004, Pisa. p. 651-4; Schuermann HW. Traveling-wave solutions to the cubic-quintic nonlinear Schroedinger equation. Phys Rev E 1996;54:4312-20] leads to a method for finding exact travelling wave solutions of nonlinear wave and evolution equations (NLWEE). The first idea is to generalize ansaetze given by Baldwin and Peng to find elliptic solutions of NLWEEs. Secondly, conditions used by ...

International Nuclear Information System (INIS)

An outline is given of time-dependent wavepacket methods as applied to calculations of molecular collisions with solid surfaces. The methods reviewed include numerical integration algorithms for the time-dependent Schroedinger equation, semiclassical wavepacket treatments, and approximations that treat some of the degrees-of-freedom quantum-mechanically and others classically. The computational and numerical characteristics of these methods are discussed, with emphasis on their particular advantages and relevance in the context of certain molecule/surface scattering problems. For the semiclassical and mixed quantal-classical treatments, the approximation errors and their physical origins are discussed. For the quantum wavepacket techniques a numerical error analysis is presented. The computational efficiency of the various algorithms is considered and examined in the context of ...

Energy Technology Data Exchange (ETDEWEB)

The computer programme COMMIX-2 describes steady state and transient multidimensional single- and two-phase fluid flows with heat transfer in nuclear reactor components and multicomponent systems. Originally from the Argonne National Laboratory, the code has been further developed at the Kernforschungszentrum Karlsruhe. The original Point-SOR iterative method for the solution of a Poisson-like equation describing the pressure distribution in the fluid as well as the transport of enthalpy and turbulent quantities has been complemented with iterative and direct line- and block-methods. None of the newly implemented methods is original in itself but their implementation into the computer code, which can describe the most general shapes of definition domains, gave a code speed-up by a factor of 2-5, depending on the problem treated. The code capabilities are assessd by the calculation ...

Energy Technology Data Exchange (ETDEWEB)

We consider the supercooled Stefan problem with a general anisotropic curvature- and velocity-dependent boundary condition on the moving interface. We present numerical methods, based on an integral equation formulation and including a new algorithm for moving curves with curvature-dependent velocity. These methods compute a periodic interface with {ital O}({Delta}{ital t}) accuracy, where {Delta}{ital t} is the time step. Previous work has been limited to short time spans and achieved slightly less than {ital O}({Delta}{ital t}{sup 1/2}) accuracy. Accurate numerical results are seen to agree with the predictions of linear stability theory. This agreement has eluded previous authors, because their numerical methods suffered from grid effects and their linear stability theory was incorrect. We study the long-time evolution of an unstable interface. Our computations exhibit the ...

Energy Technology Data Exchange (ETDEWEB)

Chest computed tomography (CT) was valuable in detecting extrinsic tracheal compression by mediastinal masses in two pediatric patients. This prompted an independent evaluation by CT of 14 children with masses involving the middle mediastinum and possible intrathoracic tracheal narrowing. Computer programs permit precise calculation of tracheal cross-sectional areas. Any apparent decrease in tracheal area may be compared with CT-derived data in normal children. Chest CT not only demonstrates the presence of extrinsic airway compression in pediatric patients with mediastinal masses, but also is capable of precisely measuring the extent of this narrowing. This method identifies children at potential risk for respiratory compromise and may aid in subsequent therapy.

International Nuclear Information System (INIS)

Atomic ensembles, comprising clouds of atoms addressed by laser fields, provide an attractive system for both the storage of quantum information and the coherent conversion of quantum information between atomic and optical degrees of freedom. We describe a scheme for full-scale quantum computing with atomic ensembles, in which qubits are encoded in symmetric collective excitations of many atoms. We consider the most important sources of error-imperfect exciton-photon coupling and photon losses-and demonstrate that the scheme is extremely robust against these processes: the required photon emission and collection efficiency threshold is #approx#>86%. Our scheme uses similar methods to those already demonstrated experimentally in the context of quantum repeater schemes and yet has information processing capabilities far beyond those proposals.

British Library Electronic Table of Contents (United Kingdom)

Multiple receivers can be utilized to enhance the spatiotemporal resolution of MRI by employing the parallel imaging technique. Previously, we have reported the L-curve Tikhonov regularization technique to mitigate noise amplification resulting from the geometrical correlations between channels in a coil array. Nevertheless, one major disadvantage of regularized image reconstruction is lengthy computational time in regularization parameter estimation. At a fixed noise level, L-curve regularization parameter estimation was also found not to be robust across repetitive measurements, particularly for low signal-to-noise ratio (SNR) acquisitions. Here we report a computationally efficient and robust method to estimate the regularization parameter by partitioning the variance of the noise-white...

British Library Electronic Table of Contents (United Kingdom)

Purpose We evaluated low-contrast injection protocols for coronary computed tomography angiography (CTA) using a 64-detector scanner and the test bolus technique. Materials and methods We randomly assigned 60 patients undergoing coronary CTA to one of two contrast material (CM) injection protocols. For the lowcontrast dose protocol (Plow), the patients received injections of iohexol-350 [0.7 ml/kg body weight (BW)] during 9 s, and the test-bolus technique was used. Under the conventional protocol (Pconv), they received iohexol-350 (1.0 ml/kg BW) during 15 s, and bolus tracking was used. We compared the protocols for attenuation values in the ascending aorta and coronary arteries and for the amount of CM required. Results There was no significant difference in the mean CT attenuation of the...

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Twenty-two out of 31 patients with chronic renal failure and secondary hyperparathyroidism who underwent parathyroidectomy before operation underwent non-invasive image diagnosis of parathyroid glands by computed tomography (CT), scintigraphy with /sup 201/TlCl and /sup 99m/TcO/sup 4 +/, and/or ultrasonography. CT visualized 39 of 45 parathyroid glands (86.7%), weighing more than 500 mg. Scintigraphy with a subtraction method using a computer performed the diagnosis in 19 of 27 glands (70.4%). Ultrasonography detected 21 of 27 glands (77.8%). Image diagnosis was also useful in the postoperative follow-up study. The non-invasive image diagnosis of parathyroid glands in patients with chronic renal failure is thus valuable for 1) definite diagnosis of secondary hyperparathyroidism, 2) localization, and 3) diagnosis for effectiveness of conservative treatment.

Energy Technology Data Exchange (ETDEWEB)

Fuji computed radiography (FCR) utilizing imaging plates stimulated by a scanning lazer has been developed in Japan and come to be widely available in diagnostic radiology. This system is advantageous because many processed images can be obtained with a single exposure. However, no reports have been published on the exact conditions necessary under which the FCR image processing method will produce improved visibility of pulmonary abnormal shadows on chest radiographs. In this report, chest FCR images obtained from 50 patients were analyzed, and the best practical image processing conditions were determined for each pathological state. Fundamental analysis was also performed for spatial and contrast resolution with FUNK chart and Burger's phantom using various thickness of acryl plate. Ninety processing images per exposure were analyzed, and the best practical conditions were determined. (author).

British Library Electronic Table of Contents (United Kingdom)

Purpose. The paper introduces a novel design of air-core inductive sensors in printed circuit board (PCB) technology for a tongue control system. The tongue control system provides a quadriplegic person with a keyboard and a joystick type of mouse for interaction with a computer or for control of an assistive device. Method. Activation of inductive sensors was performed with a cylindrical, soft ferromagnetic material (activation unit). Comparative analysis of inductive sensors in PCB technology with existing hand-made inductive sensors was performed with respect to inductance, resistance, and sensitivity to activation when the activation unit was placed in the center of the sensor. Optimisation of the activation unit was performed in a finite element model. Results. PCBs with air-core indu...

International Nuclear Information System (INIS)

Colorectal cancer (CRC) is the most common cause of cancer death among Canadian non-smokers. Each year about 21,500 Canadians are diagnosed with CRC. Ninety percent of cases occur in people aged 50 years or older. An estimated 4,800 Canadian men and 4,100 Canadian women die each year from the disease. About 75% of all new CRC cases arise in people with no known risk factors. Computed tomography colonography (CTC), a cross-sectional imaging examination that permits complete structural examination of the colon, shows promise as a tool for CRC screening. This article reviews the rationale for CRC screening, currently recommended Canadian and American screening guidelines and screening tools, and current evidence supporting CTC as a CRC screening tool and its advantages over conventional screening methods. (author)

CERN Document Server

The pair-specific ground state energy of Newtonian N-body systems grows monotonically in N. This furnishes a whole family of simple new tests for minimality of putative ground state energies obtained through computer experiments. Inspection of several publically available lists of such computer-experimentally obtained putative ground state energies has yielded several dozen instances which failed (at least) one of these tests. Although the correct ground state energy is not revealed by this method, it does yield a better upper bound on it than the experimentally found value whenever the latter fails a monotonicity test. The surveyed N-body systems include in particular N point charges with 2- or 3-dimensional Coulomb pair interactions, placed either on the unit 2-sphere or on a 2-torus (a.k.a. Thomson, Fekete, or Riesz problems).

Energy Technology Data Exchange (ETDEWEB)

This paper proposes a high accuracy numerical method to model oil spill trajectories using a particle-tracking algorithm. The Euler method, used to calculate oil trajectories, can give adequate solutions in most open ocean applications. However, this method may not predict accurate particle trajectories in certain highly non-uniform velocity fields near coastal zones or in river problems. Simple numerical experiments show that the Euler method may also introduce artificial numerical dispersion that could lead to overestimation of spill areas. This article proposes a fourth-order Runge-Kutta method with fourth-order velocity interpolation to calculate oil trajectories that minimise these problems. The algorithm is implemented in the OilTrack model to predict oil trajectories following the 'Nissos Amorgos' oil spill accident that occurred in the Gulf of Venezuela in ...

Energy Technology Data Exchange (ETDEWEB)

A noninvasive method is described for estimating local cerebral blood flow (LCBF) and local partition coefficients by means of computed tomographic scanning during inhalation of 30% stable xenon gas in oxygen. Time-dependent xenon concentrations in arterial blood and brain tissue during the wash-in and washout phases are used to calculate partition coefficients and LCBF values by means of a least-squares curve-fitting analysis. Control values for partition coefficient and LCBF obtained from control subjects with minor head trauma in the chronic stage were compatible with those in several past reports, and reproducibility was satisfactory. The theoretic grounds underlying this new method of curve-fitting analysis are discussed.

Energy Technology Data Exchange (ETDEWEB)

The application of a method for determining the temperature of an oxygen-replenished air stream heated to 2600 K by a hydrogen burner is reviewed and discussed. The purpose of the measurements is to determine the spatial uniformity of the temperature in the core flow of a ramjet test facility. The technique involves sampling the product gases at the exit of the test section nozzle to infer the makeup of the reactant gases entering the burner. Knowing also the temperature of the inlet gases and assuming the flow is at chemical equilibrium, the adiabatic flame temperature is determined using an industry accepted chemical equilibrium computer code. Local temperature depressions are estimated from heat loss calculations. A description of the method, hardware and procedures is presented, along with local heat loss estimates and uncertainty assessments. The uncertainty of the method is estimated at {+-}31 K, ...

Science.gov (United States)

An improved method of generating angle-domain common-image gathers (ADCIGs) by VSP reverse time migration (RTM) is introduced in this paper. The formula which is used to compute the receiver wavefield for VSP RTM is modified by adding an amplitude correction term in order to conveniently output amplitude-preserved ADCIGs. Compared with the surface seismic data, VSP data contains much richer wavefields. However, the direct and downgoing waves can bring about serious imaging artifacts in ADCIGs, especially the direct wave. The feasibility and validity of this method is demonstrated by both numerical and real VSP data from western China. Thus, the ADCIGs from this method can provide reliable basic data for VSP migration velocity analysis, VSP AVO/AVA analysis, and inversion.

Energy Technology Data Exchange (ETDEWEB)

Our work has focused on the development and analysis of domain decomposition algorithms for a variety of problems arising in continuum mechanics modeling. In particular, we have extended and analyzed FETI-DP and BDDC algorithms; these iterative solvers were first introduced and studied by Charbel Farhat and his collaborators, see [11, 45, 12], and by Clark Dohrmann of SANDIA, Albuquerque, see [43, 2, 1], respectively. These two closely related families of methods are of particular interest since they are used more extensively than other iterative substructuring methods to solve very large and difficult problems. Thus, the FETI algorithms are part of the SALINAS system developed by the SANDIA National Laboratories for very large scale computations, and as already noted, BDDC was first developed by a SANDIA scientist, Dr. Clark Dohrmann. The FETI algorithms are also making inroads in commercial engineering software systems. ...

International Nuclear Information System (INIS)

A computer controlled digital system, Fuji Computed Radiography (FCR) is capable of providing more stable output image than conventional screen/film system. So FCR would be an ideal system for the detection of pneumoconiosis due to the constant high quality of the output films. We tried to find the optimum image processing to compensate the small size (1/2 in length of a full-size radiograph) of the output image of digital radiography. The best result for FCR was given with gamma 0.85 and 0.30 enhancement of response at spatial frequency of 0.085 cycle/mm. On the other hand, the digitally processed FCR size ILO standard films, the characteristics of which is different from FCR output films, proved to be most preferable when the image processing is made with gamma 0.85 and 0.25 enhancement at spacial frequency of 0.17 cycle/mm. If the above mentioned image processings are adopted, FCR can be used for the diagnosis of pneumoconiosis with the same ...

Energy Technology Data Exchange (ETDEWEB)

Activities are reported by the Reactor Systems Section, Research Instrument Section, and the Measurement and Controls Engineering Section. Reactor system activities include dynamic analysis, survillanc and diagnostic methods, design and evaluation, detectors, facilities support, process instrumentation development, and special assignments. Activities in the Research Instrument Section include the Navy-ORNL RADIAC development program, advanced ..gamma.. and x ray detector systems, neutron detection and subcriticality measurements, circuit development, position-sensitive detectors, stand-alone computers, environmental monitoring-detectors and systems, plant security, engineering support for fusion energy division, engineering support for accelerator physics, and communications: radio, closed-circuit tv, and computer. Activities in the Measurement and Controls Engineering Section include the AVLIS program; gas centrifuge ...

Energy Technology Data Exchange (ETDEWEB)

A system and method for generating global asynchronous signals in a computing structure. Particularly, a global interrupt and barrier network is implemented that implements logic for generating global interrupt and barrier signals for controlling global asynchronous operations performed by processing elements at selected processing nodes of a computing structure in accordance with a processing algorithm; and includes the physical interconnecting of the processing nodes for communicating the global interrupt and barrier signals to the elements via low-latency paths. The global asynchronous signals respectively initiate interrupt and barrier operations at the processing nodes at times selected for optimizing performance of the processing algorithms. In one embodiment, the global interrupt and barrier network is implemented in a scalable, massively parallel supercomputing device structure comprising a plurality of processing ...

Energy Technology Data Exchange (ETDEWEB)

Accurate and rapid evaluation of radar signature for alternative aircraft/store configurations would be of substantial benefit in the evolution of integrated designs that meet RCS requirements across the threat spectrum. Finite-volume time domain methods offer the possibility of modeling the whole aircraft, including penetrable regions and stores, at longer wavelengths on today's supercomputers and at typical airborne radar wavelengths on the teraflop computers of tomorrow. A structure-grid finite-volume time domain CFD based RCS code has already been developed at the Rockwell Science Center, and this code incorporates modeling techniques for general radar absorbing materials and structures. Using this work as a base, the goal of the CFD based CEM effort is to define, implement, and evaluate various code development issues suitable for rapid prototype signature prediction addressing many issues related to physics of electromagnetics, ...

Energy Technology Data Exchange (ETDEWEB)

The costs of establishing a computer-based training program for FFTF reactor operators are analyzed.

International Nuclear Information System (INIS)

First structural wall material (FSW) materials in inertial fusion energy (IFE) power reactors will be irradiated under typical repetition rates of 1-10 Hz, for an operation time as long as the total reactor lifetime. The main objective of the present work is to determine whether a continuous-pulsed (CP) approach can be an efficient method in modeling the pulsed activation process for operating conditions of FSW materials. The accuracy and practicability of this method was investigated both analytically and (for reaction/decay chains of two and three nuclides) by computational simulation. It was found that CP modeling is an accurate and practical method for calculating the neutron-activation of FSW materials. Its use is recommended instead of the equivalent steady-state method or the exact pulsed modeling. Moreover, the applicability of this method to components ...

Energy Technology Data Exchange (ETDEWEB)

A generalized approach to the analysis of the effects of transmission line faults on natural gas transmission pipelines has been developed and is presented in this report. A state of the art user-friendly computational tool has been developed and verified for the analysis of interference between electrical power lines and nearby buried or above-ground pipelines. This computer program, ECCAPP, is distinguished by its ability to model and analyze accurately complex, realistic interactions between pipelines and power lines, using easily obtained input data. The final report consists of three volumes. An independent fourth volume was also developed to simplify the installation of the ECCAPP software. Volume 1 contains the theory upon which the ECCAPP computer program is based. A parametric analysis and graphical charts have been formulated using ECCAPP to permit estimates to be made in the field or during preliminary analyses ...

Energy Technology Data Exchange (ETDEWEB)

An essential part of fire risk assessment is the analysis of fire hazards and fire propagation. In this work, models and tools for two different aspects of numerical fire simulation have been developed. The primary objectives have been firstly to investigate the possibility of exploiting state-of-the-art fire models within probabilistic fire risk assessments and secondly to develop a computationally efficient solver of thermal radiation for the Fire Dynamics Simulator (FDS) code. In the first part of the work, an engineering tool for probabilistic fire risk assessment has been developed. The tool can be used to perform Monte Carlo simulations of fires and is called the Probabilistic Fire Simulator (PFS). In Monte Carlo simulation, the simulations are repeated multiple times, covering the whole range of variability of the input parameters and thus resulting in a distribution of results covering what can be expected in reality. In practical applications, advanced ...

International Nuclear Information System (INIS)

Dose calculations for radiation arc therapy are traditionally performed by approximating continuous delivery arcs with multiple static beams. For 3D conformal arc treatments, the shape and weight variation per degree is usually small enough to allow arcs to be approximated by static beams separated by 5"0-10"0. But with intensity-modulated arc therapy (IMAT), the variation in shape and dose per degree can be large enough to require a finer angular spacing. With the increase in the number of beams, a deterministic dose calculation method, such as collapsed-cone convolution/superposition, will require proportionally longer computational times, which may not be practical clinically. We propose to use a homegrown Monte Carlo kernel-superposition technique (MCKS) to compute doses for rotational delivery. The IMAT plans were generated with 36 static beams, which were subsequently interpolated into finer angular intervals for dose ...

Energy Technology Data Exchange (ETDEWEB)

We are developing a laterally variable velocity model of the crust and upper mantle across Eurasia and North Africa to reduce event location error by improving regional travel-time prediction accuracy. The model includes both P and S velocities and we describe methods to compute travel-times for Pn, Sn, Pg, and Lg phases. For crustal phases Pg and Lg we assume that the waves travel laterally at mid-crustal depths, with added ray segments from the event and station to the mid crustal layer. Our work on Pn and Sn travel-times extends the methods described by Zhao and Xie (1993). With consideration for a continent scale model and application to seismic location, we extend the model parameterization of Zhao and Xie (1993) by allowing the upper-mantle velocity gradient to vary laterally. This extension is needed to accommodate the large variation in gradient that is known to exist across Eurasia and North African. Further, we ...

Science.gov (United States)

This Dissertation presents the author's investigation and development of a systematic method for evaluating the aerodynamic performance of Vertical Axis Wind Energy Capture Systems (WECS) apart from their electrical generation capability. The current standard method for specifying a wind energy machine is to discuss its rated power in kilowatts (or megawatts when capacity exceeds 100 kW). While this holistic method is effective for comparing machines it does not reveal the essential characteristics necessary for optimization of individual machine components. The method developed herein separates the performance characteristics of the WECS from the generation characteristics and isolates them for benchmarking and optimization. In order to develop an evaluation criterion, it was essential to evaluate and benchmark the current state of the art for wind energy capture. A thorough history of Vertical Axis ...

International Nuclear Information System (INIS)

In this paper, we calculated the radioactive concentration distribution of radioactive waste water, the temperature distribution of drained cooling water and the effect of implement from the Daya Bay Nuclear Power Plant on nearby waters range, discussed and analysed some problems of computational results and computation with Alternating Direction Implicit Method (ADI). The contents of the article included: the establishment of two-dimension tidal current equation, radioactive waste water pollutant dispersion equation and cooling water heat convection diffusion equation, the numerical difference calculation model of tidal current field, concentration field as well as temperature field, effect impingement with ADI method, numerical calculation results. The result of research showed that: when the Daya Bay Nuclear Power Plant is on normal operation and after the low level radioactive waste water and low ...

Science.gov (United States)

The Predictive Capability Maturity Model (PCMM) is a new model that can be used to assess the level of maturity of computational modeling and simulation (M&S) efforts. The development of the model is based on both the authors experience and their analysis of similar investigations in the past. The perspective taken in this report is one of judging the usefulness of a predictive capability that relies on the numerical solution to partial differential equations to better inform and improve decision making. The review of past investigations, such as the Software Engineering Institute's Capability Maturity Model Integration and the National Aeronautics and Space Administration and Department of Defense Technology Readiness Levels, indicates that a more restricted, more interpretable method is needed to assess the maturity of an M&S effort. The PCMM addresses six contributing elements to M&S: (1) representation and geometric ...

CERN Document Server

In dissipative ordinary differential equation systems different time scales cause anisotropic phase volume contraction along solution trajectories. Model reduction methods exploit this for simplifying chemical kinetics via a time scale separation into fast and slow modes. The aim is to approximate the system dynamics with a dimension-reduced model after eliminating the fast modes by enslaving them to the slow ones via computation of a slow attracting manifold. We present a novel method for computing approximations of such manifolds using trajectory-based optimization. We discuss Riemannian geometry concepts as a basis for suitable optimization criteria characterizing trajectories near slow attracting manifolds and thus provide insight into fundamental geometric properties of multiple time scale chemical kinetics. The optimization criteria correspond to a suitable mathematical formulation of "minimal ...

International Nuclear Information System (INIS)

Many types of pipe whip restraints are installed to protect the structural components from the anticipated pipe whip phenomena of high energy lines in nuclear power plants. It is necessary to investigate these phenomena accurately in order to evaluate the acceptability of the pipe whip restraint design. Various research programs have been conducted in many countries to develop analytical methods and to verify the validity of the methods. In this study, various calculational models in ANSYS code and in ADLPIPE code, the general purpose finite element computer programs, were used to simulate the postulated pipe whips to obtain impact loads and the calculated results were compared with the specific experimental results from the sample pipe whip test for the U-shaped pipe whip restraints. Some calculational models, having the spring element between the pipe whip restraint and the pipe line, give reasonably good transient ...

Energy Technology Data Exchange (ETDEWEB)

In the present dissertation, a hierarchical multiscale approach for modeling FePt nanoparticles by atomistic computer simulations is developed. By describing the interatomic interactions on different levels of sophistication, various time and length scales can be accessed. Methods range from static quantum-mechanic total-energy calculations of small periodic systems to simulations of whole particles over an extended time by using simple lattice Hamiltonians. By employing these methods, the energetic and thermodynamic stability of non-crystalline multiply twinned FePt nanoparticles is investigated. Subsequently, the thermodynamics of the order-disorder transition in FePt nanoparticles is analyzed, including the influence of particle size, composition and modified surface energies by different chemical surroundings. In order to identify processes that reduce or enhance the rate of transformation from the disordered to the ...

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.).

International Nuclear Information System (INIS)

The risk analysis was carried out in consideration of conditions prevailing at the Kalkar site analogous to the investigations in phase A of DRS (German Reactor Study). Earthquake design loads include the probabilities of upper deviations of the site intensities to be expected. The calculations of dynamic loads for select buildings are made using models and computational methods. Component analyses were performed analogous to DRS for the supports of large components, supports of the roof construction of the reactor building taking into account support reserves due to plastic work capacity, wall disks in steam generator buildings and switchboard plant buildings. (DG).

Energy Technology Data Exchange (ETDEWEB)

In recent years, the phase stability of austenitic stainless steels, and its effect on the mechanical properties of stainless steels, have been the subject of much interest. With the availability of new experimental techniques, new theoretical methods, and new computational procedures, significant advances have been made in understanding, and being able to predict, phase stability and mechanical properties of stainless steel welds. This paper reviews some of these developments, with an emphasis on recent work that has been done at Oak Ridge National Laboratory.

International Nuclear Information System (INIS)

The use of workstations, controllers or embedded systems and their applications have become much more relevant than previously. PC-based systems, a cooker programmer, applications of, for example, Prolog machines, Unix and Ada papers, Robotics and Automation are typical examples of this. The three keynote addresses of this symposium have as their subjects the most spectacular microcomputer fields and are presented by leading experts. The papers presented cover most of the traditional interests of Euromicro. Special emphasis is given to contributions on the use of workstations and personal computers, on RISC and GaAs and on transputers.

Energy Technology Data Exchange (ETDEWEB)

Radiological findings of chest and abdominal wall involvement in Hodgkin's disease are reported. This manifestation was diagnosed in one patient in the primary staging and in two patients during the course of the disease. Typical radiological findings are soft tissue masses in the chest and abdominal wall, in two cases with continous tumor growth of enlarged mediastinal lymphnodes into the anterior chest wall. The axial computed tomography is the best method to evaluate the extent of chest and abdominal wall involvement in Hodgkin's disease.

Science.gov (United States)

Information security involves many branches of effort, including information assurance, host level security, physical security, and network security. Computer network security methods and implementations are given a top-down description to permit a medically focused audience to anchor this information to their daily practice. The depth of detail of network functionality and security measures, like that of the study of human anatomy, can be highly involved. Presented at the level of major gross anatomical systems, this paper will focus on network backbone implementation and perimeter defenses, then diagnostic tools, and finally the user practices (the human element). Physical security measures, though significant, have been defined as beyond the scope of this presentation.

British Library Electronic Table of Contents (United Kingdom)

The adsorption and corrosion inhibition behavior of three selected thiosemicarbazone derivatives, namely 3-pyridinecarboxaldehyde thiosemicarbazone (META), isonicotinaldehyde thiosemicarbazone (PARA) and 2-pyridinecarboxaldehyde thiosemicarbazone (ORTHO) at the nickel surface were studied electrochemically by Tafel and impedance methods and computationally by carrying out Monte Carlo searches of configurational space on nickel/thiosemicarbazone derivative system. Electrochemical measurements showed that the inhibition efficiency of these compounds increased with increase in their concentration. The recorded inhibition efficiencies of the three tested thiosemicarbazone increase in the order: META>PARA>ORTHO. Polarization studies showed that these compounds act as mixed-type inhibitors for n...

Energy Technology Data Exchange (ETDEWEB)

This executive summary presents the motivation, structure, objectives, methodologies and results of the first stage of the international DECOVALEX project - DECOVALEX I (1992-1995). The acronym stands for Development of Coupled Models and their Validation against Experiment in Nuclear Waste Isolation, and the project is an international effort to develop mathematical models, numerical methods and computer codes for coupled thermo-hydro-mechanical processes in fractured rocks and buffer materials for geological isolation of spent nuclear fuel and other radioactive wastes, and validate them against laboratory and field experiments. 24 refs.

International Nuclear Information System (INIS)

The intention is to define what is required as evidence of continuous resistance to malfunction to ensure operational safety according to Rule KTA 3706 'Proof of electrical component safety under leakage conditions'. As a supporting part of this task, a recognized scientific and engineering basis on which to define the requirements has to be set up. The report is a compilation of studies and development work which could contribute useful improvements to the assessment methodology applied to thermal aging (Arrhenius model, ndeg-rule, Eyring model, Inverse-power model, according to KTA Rule 3505) of electronic controls or electrical components. (orig./DG).

International Nuclear Information System (INIS)

This handbook breaks down the complex field of nuclear reactor calculations into major steps. Each step presents a detailed analysis of the problems to be solved, the parameters involved, and the elaborate computer programs developed to perform the calculations. This book bridges the gap between nuclear reactor theory and the implementation of that theory, including the problems to be encountered and the level of confidence that should be given to the methods described. Volume II: Monte Carlo Calculations for Nuclear Reactors. In-Core Management of Four Reactor Types. In-Core Management in CANDU-PHW Reactors. Reactor Dynamics. The Theory of Neutron Leakage in Reactor Lattices. Index.

International Nuclear Information System (INIS)

The accident assessment under emergency situation includes the accident status evaluation and its consequence estimation. This paper introduces evaluation methods for accident status and its assistant computer system (SESAME-GNP) utilized during the emergency situation in Guangdong Daya Bay Nuclear Power Station (GNPS) in detail. At the same time, an improved accident consequence estimation system in GNPS (RACAS-GNP) is briefly described. With the improvement of the accident assessment systems, the capability of emergency response in GNPS is strengthened

Energy Technology Data Exchange (ETDEWEB)

Monte Carlo methods have been used to compute k{sub eff} and the fundamental mode eigenfunction of critical systems since the 1950s. While such calculations have become routine using standard codes such as MCNP and SCALE/KENO, there still remain 3 concerns that must be addressed to perform calculations correctly: convergence of k{sub eff} and the fission distribution, bias in k{sub eff} and tally results, and bias in statistics on tally results. This paper provides a review of the fundamental problems inherent in Monte Carlo criticality calculations. To provide guidance to practitioners, suggested best practices for avoiding these problems are discussed and illustrated by examples.

International Nuclear Information System (INIS)

Purpose: An inverse treatment planning algorithm for tomotherapy is described. Methods and Materials: The algorithm iteratively computes a set of nonnegative beam intensity profiles that minimizes the least-squares residual dose defined in the target and selected normal tissue regions of interest. At each iteration the residual dose distribution is transformed into a set of residual beam profiles using an inversion method derived from filtered backprojection image reconstruction theory. These 'residual' profiles are used to correct the current beam profile estimates resulting in new profile estimates. Adaptive filtering is incorporated into the inversion model so that the gross structure of the dose distribution is optimized during initial iterations of the algorithm, and the fine structure corresponding to edges is obtained at later iterations. A three dimensional, kernel based, convolution/superposition dose model is used ...

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.

British Library Electronic Table of Contents (United Kingdom)

Study Type - Therapy (case series)Level of Evidence 4 OBJECTIVE To present our experience of retroperitoneoscopic partial adrenalectomy (RPA) for small adrenal tumours, as with modern imaging methods small adrenal lesions are being diagnosed more commonly, and retroperitoneoscopic adrenal surgery for small adrenal tumours (PATIENTS AND METHODS We retrospectively reviewed the records of 389 consecutive retroperitoneoscopic adrenalectomies from September 2005 to December 2008, 88 of which were small adrenal tumours and treated by RPA. Ultrasonography and computed tomography (CT) were used in all patients before RPA, and magnetic resonance imaging or positron emission tomography/CT in some patients. We used RPA for adrenal tumours and total adrenalectomy for adrenal cancer. During the surgery...

Energy Technology Data Exchange (ETDEWEB)

The Los Alamos Cost Estimating System (QUEST) is being converted to run on IBM personal computers. This very extensive estimating system is capable of supporting cost estimators from many different and varied fields. QUEST does not dictate any fixed method for estimating. QUEST supports many styles and levels of detail estimating. QUEST can be used with or without data bases. This system allows the estimator to provide reports based on levels of detail defined by combining work breakdown structures. QUEST provides a set of tools for doing any type of estimate without forcing the estimator to use any given method. The level of detail in the estimate can be mixed based on the amount of information known about different parts of the project. The system can support many different data bases simultaneously. Estimators can modify any cost in any data base.

International Nuclear Information System (INIS)

A theoretical study of electron and positron band structures of zinc-blende AlN and InN and their alloy Al_0_._5In_0_._5N is presented using the first-principles full-potential linearized augmented plane-wave method. Equilibrium lattices constants are determined from the total-energy minimization method. The results are compared with previous calculations and with experimental measurement. Electron and positron charge densities are computed as function of position in the unit cell. Detailed plots of distributions are along the direction. The ionicity factors are calculated by means of three different approaches. The calculated results of the positron charge density reflect the high insight for the annihilation effect.

Energy Technology Data Exchange (ETDEWEB)

Existing oil reservoirs might be more fully exploited if the properties of the flow of oil and water in porous media were better known. In laboratory experiments it is important to collect as much information as possible to make a descriptive model of the system, including position imaging and chemical binding information. This thesis develops nuclear methods for obtaining position image and chemical binding information from flow experiments of porous media. A combined positron emission tomography and single photon emission computed tomography system to obtain position images, and a time-differential perturbed angular correlation system to obtain chemical binding information, have been built and thoroughly tested. 68 refs., 123 figs., 14 tabs.

CERN Document Server

A prescription is given for computing anomalous dimensions of single trace operators in SYM at strong coupling and large $N$ using a reduced model of matrix quantum mechanics. The method involves treating some parts of the operators as "BPS condensates" which, in certain limit, have a dual description as null geodesics on the $S^5$. In the gauge theory, the condensate is similar to a representative of the chiral ring and it is described by a background of commuting matrices. Excitations around these condensates correspond to excitations around this background and take the form of ``string bits" which are dual to the "giant magnons" of Hofman and Maldacena. In fact, the matrix model approach gives a {\\it quantum} description of these string configurations and explains why the infinite momentum limit suppresses the quantum effects. This method allows, not only to derive part of the classical sigma model Hamiltonian of the ...

Energy Technology Data Exchange (ETDEWEB)

In this study, experiments were performed for pipe whip phenomena simulation. The analytical method was developed by combining several kinds of elements in ABAQUS computer code, standard version 5.2 . The transient analytical and the experimental results of the pipe whip test using 6 inch diameter pipe and U-shaped restraints are presented. It is shown that the adequate clearance decreases the restraint strains. As the overhang length increased, the maximum strain of restraints decreased. When the impact force increased, the maximum restraint strain increased slightly. The analytical models simulate the experimental impact phenomena very precisely, with slight conservatism. It is verified that the analytical method developed is very suitable to pipe whip phenomena analysis in nuclear power plants. 6 refs., 10 figs., 1 tab.

Energy Technology Data Exchange (ETDEWEB)

Environmental exposure measurements are, in general, positive and may be subject to left censoring; i.e,. the measured value is less than a ''detection limit''. In occupational monitoring, strategies for assessing workplace exposures typically focus on the mean exposure level or the probability that any measurement exceeds a limit. Parametric methods used to determine acceptable levels of exposure, are often based on a two parameter lognormal distribution. The mean exposure level, an upper percentile, and the exceedance fraction are used to characterize exposure levels, and confidence limits are used to describe the uncertainty in these estimates. Statistical methods for random samples (without non-detects) from the lognormal distribution are well known for each of these situations. In this report, methods for estimating these quantities based on the maximum likelihood ...

International Nuclear Information System (INIS)

Purpose: To develop an accurate, fast, and robust algorithm for registering portal and computed tomographic (CT) images for radiotherapy using a combination of sparse and dense field data that complement each other. Methods and Materials: Gradient Feature Weighted Minimax (GFW Minimax) method was developed to register multiple portal images to three-dimensional CT images. Its performance was compared with that of three others: Minimax, Mutual Information, and Gilhuijs' method. Phantom and prostate cancer patient images were used. Effects of registration errors on tumor control probability (TCP) and normal tissue complication probability (NTCP) were investigated as a relative measure. Results: Registration of four portals to CTs resulted in 30% lower error when compared with registration with two portals. Computation time increased by nearly 50%. GFW Minimax performed the best, ...

Energy Technology Data Exchange (ETDEWEB)

The seismic reflection exploration technique which is one of the geophysical methods for oil exploration became effectively to image the subsurface structure with rapid development of computer. As a tool to perform seismic inversion, seismic forward modeling program using ray tracing should be developed. In this study, we have developed the algorithm that is to calculate the travel time of the complex geological structure using ray tracing by subdividing the geologic model into triangular element (finite element) having the constant velocity. We can analytically calculate Jacobian with some information by this current ray tracing. With this Jacobian, we will develop new algorithm which is to obtain geological properties and to image the subsurface. Since the FEM (Finite Element Method) ray tracing we have developed goes well the inverse velocities structure, we can apply the inversion problem to complex geological model. ...

International Nuclear Information System (INIS)

Techniques for reducing computation time in 3D photon dose calculations are addressed with specific emphasis given to the convolution/superposition approach. A single polyenergetic superposition model calculating absorbed dose per incident photon fluence (Gy cm"2) was developed in terms of TERMA and a total energy deposition kernel (a total point spread function). A novel approach was devised for reducing calculation time. The method, named the CF method, was based on the use of a conventional, fast model (here a modified power-law method was used) for the generation of 3D dose distributions on a fine dose matrix. Superposition calculations were carried out on a coarse matrix and calculation speed was increased simply by reducing the number of calculations. A set of correction factors was derived on the coarse grid from the ratio of the dose values from superposition to those from the conventional ...

UK PubMed Central (United Kingdom)

We present interactive computer programs for the analysis of nucleic acid sequences. In order to handle these programs, minimum computer experience is sufficient. The nucleotide sequence of the human...Full Text Available

USGS Gallery

USGS geologists Peter Triezenberg and William Danforth sit with WHOI/LDEO Computer Technician Tom Bolmer in the Healy computer lab. This was during a scientific expedition to map the Arctic seafloor....

International Nuclear Information System (INIS)

The principal mathematical tools frequently available for calculations in Nuclear Engineering, including coupled neutron-gamma radiations shielding problems, involve the full Transport Theory or the Monte Carlo techniques. The Multigroup Albedo Method applied to shieldings is characterized by following the radiations through distinct layers of materials, allowing the determination of the neutron and gamma fractions reflected from, transmitted through and absorbed in the irradiated media when a neutronic stream hits the first layer of material, independently of flux calculations. Then, the method is a complementary tool of great didactic value due to its clarity and simplicity in solving neutron and/or gamma shielding problems. The outstanding results achieved in previous works motivated the elaboration and the development of this study that is presented in this dissertation. The radiation balance resulting from the incidence of a neutronic ...

Energy Technology Data Exchange (ETDEWEB)

This manual describes the use of the Xyce Parallel Electronic Simulator. Xyce has been designed as a SPICE-compatible, high-performance analog circuit simulator, and has been written to support the simulation needs of the Sandia National Laboratories electrical designers. This development has focused on improving capability over the current state-of-the-art in the following areas: (1) Capability to solve extremely large circuit problems by supporting large-scale parallel computing platforms (up to thousands of processors). Note that this includes support for most popular parallel and serial computers; (2) Improved performance for all numerical kernels (e.g., time integrator, nonlinear and linear solvers) through state-of-the-art algorithms and novel techniques. (3) Device models which are specifically tailored to meet Sandia's needs, including some radiation-aware devices (for Sandia users only); and (4) Object-oriented code design and ...

International Nuclear Information System (INIS)

In order to predict or to evaluate the structural reliability of a variety of nuclear components under actual changing operating conditions, it is necessary to take the detailed geometrical features of components into consideration on one hand, and thermo-mechanical loading conditions with space and time variations during the lifetime, on the other hand. This consideration leads the authors to develop a super large-scale structural analysis program based on a parallel computational FEM with a variable scale of PC cluster architecture, whose prototype system is presented in a companion paper in this Symposium. Development of the PC cluster technology is one of the most important subjects in large-scale structural simulation, reducing computer costs and thus making simulation more acceptable to the engineering community. This paper presents the developmental status of the parallel FEM solver, demonstrating computational ...

International Nuclear Information System (INIS)

Background and purpose: To compare 6 MV and 18 MV photon intensity modulated radiotherapy (IMRT) for non-small cell lung cancer. Materials and methods: Doses for a cohort of 10 patients, typical for our department, were computed with a commercially available convolution/superposition (CS) algorithm. Final dose computation was also performed with a dedicated IMRT Monte Carlo dose engine (MCDE). Results: CS plans showed higher D _9_5_% (Gy) for the GTV (68.13 vs 67.36, p = 0.004) and CTV (67.23 vs 66.87, p = 0.028) with 18 than with 6 MV photons. MCDE computations demonstrated higher doses with 6 MV than 18 MV in D _9_5_% for the PTV (64.62 vs 63.64, p = 0.009), PTV_o_p_t_i_m (65.48 vs 64.83, p = 0.014) and CTV (66.22 vs 65.64, p = 0.027). Dose inhomogeneity was lower with 18 than with 6 MV photons for GTV (0.08 vs 0.09, p = 0.007) and CTV (0.10 vs 0.11, p = 0.045) in CS but not MCDE plans. 6 MV photons ...

International Nuclear Information System (INIS)

Full text: Radiotherapy treatment planning (RTP) relies heavily on medical imaging. Until recently, the most important planning tool was the treatment simulator. The kilovoltage radiographic capabilities in a treatment simulator enabled the boundaries of treatment fields to be visualized with respect to bony anatomic landmarks. Perhaps the most important advance in treatment planning in recent years is the ability to visualize the passage of the beams with respect to a more accurate geometrical representation of the tumor and other soft tissue structures. This 'virtual simulation' uses a computer-based representation of a patient to determine the extent of the disease and the location of radiation sensitive normal tissue. Computer tomographic (CT) imaging produces a high-resolution three-dimensional representation of anatomy that can be correlated with other image sets such as magnetic resonance images (MRI) of function. Positron emission ...

Energy Technology Data Exchange (ETDEWEB)

A real-time neutron radiography facility was constructed including the capability of neutron tomography. The neutron beam was measured for total neutron flux ((1.0 +/- 0.2) x 10/sup 11/ m/(m/sup 2/-sec)), gold cadmium ratio (52 +/- 3) and effective neutron temperature (83/sup 0/C +/- 8/sup 0/C). The angular divergence or nonparallelism of the neutron beam was measured to be 2.3/sup 0/ +/- 0.1/sup 0/ thereby providing a means of quantifying the collimator effectiveness. The resolution capabilities of both static film and real-time neutron radiographs were quantified using a Fourier transform algorithm to calculate the modulation transfer function of both types of radiographs. The contrast sensitivity of both types of radiographs. The contrast sensitivity of both types of radiographs was measured as 3.1% for film and 4.0% for real-time radiographs. Two tomography algorithms, the simultaneous iterative reconstruction technique (SIRT) and the convolution method, were ...

Energy Technology Data Exchange (ETDEWEB)

The purpose of the workshop was to determine the status of the field, to define instrumental and computational requirements, and to establish minimum specifications required by possible users. The most important message sent by implementers was the remainder that CMT is a tool. It solves a wide spectrum of scientific problems and is complementary to other microscopy techniques, with certain important advantages that the other methods do not have. High-resolution CMT can be used non-invasively and non-destructively to study a variety of hierarchical three-dimensional microstructures, which in turn control body function. X-ray computed microtomography can also be used at the frontiers of physics, in the study of granular systems, for example. With high-resolution CMT, for example, three-dimensional pore geometries and topologies of soils and rocks can be obtained readily and implemented directly in transport models. In turn, ...