
[Methods in health services research. The example of the evaluation of the German disease management programmes].
Science.gov (United States)
Morfeld, M; Wirtz, M
20060201
According to the established definition of Pfaff, health services research analyses patients' path through the institutions of the health care system. The focus is on development, evaluation and implementation of innovative measures of health care. By increasing its quality health services research strives for an improvement of efficacy and efficiency of the health care system. In order to allow for an appropriate evaluation it is essential to differentiate between structure, process and outcome quality referring to (1) the health care system in its entirety, (2) specific health care units as well as (3) processes of communication in different settings. Health services research comprises a large array of scientific disciplines like public health, medicine, social sciences and social care. For the purpose of managing its tasks adequately a special combination of instruments and methodological procedures is needed. Thus, diverse techniques of evaluation research as well as special requirements for study designs and assessment procedures are of vital importance. The example of the German disease management programmes illustrates the methodical requirements for a scientific evaluation.

Vectorization on the star computer of several numerical methods for a fluid flow problem
Science.gov (United States)
Lambiotte, J. J., Jr.; Howser, L. M.
19740101
A reexamination of some numerical methods is considered in light of the new class of computers which use vector streaming to achieve high computation rates. A study has been made of the effect on the relative efficiency of several numerical methods applied to a particular fluid flow problem when they are implemented on a vector computer. The method of Brailovskaya, the alternating direction implicit method, a fully implicit method, and a new method called partial implicitization have been applied to the problem of determining the steady state solution of the twodimensional flow of a viscous imcompressible fluid in a square cavity driven by a sliding wall. Results are obtained for three mesh sizes and a comparison is made of the methods for serial computation.

Numerical analysis for multigroup neutrondiffusion equation using Radial Point Interpolation Method (RPIM)
International Nuclear Information System (INIS)
Kim, KyungO; Jeong, Hae Sun; Jo, Daeseong
20170101
Highlights: • Employing the Radial Point Interpolation Method (RPIM) in numerical analysis of multigroup neutrondiffusion equation. • Establishing mathematical formation of modified multigroup neutrondiffusion equation by RPIM. • Performing the numerical analysis for 2D critical problem.  Abstract: A meshfree method is introduced to overcome the drawbacks (e.g., mesh generation and connectivity definition between the meshes) of meshbased (nodal) methods such as the finiteelement method and finitedifference method. In particular, the Point Interpolation Method (PIM) using a radial basis function is employed in the numerical analysis for the multigroup neutrondiffusion equation. The benchmark calculations are performed for the 2D homogeneous and heterogeneous problems, and the Multiquadrics (MQ) and Gaussian (EXP) functions are employed to analyze the effect of the radial basis function on the numerical solution. Additionally, the effect of the dimensionless shape parameter in those functions on the calculation accuracy is evaluated. According to the results, the radial PIM (RPIM) can provide a highly accurate solution for the multiplication eigenvalue and the neutron flux distribution, and the numerical solution with the MQ radial basis function exhibits the stable accuracy with respect to the reference solutions compared with the other solution. The dimensionless shape parameter directly affects the calculation accuracy and computing time. Values between 1.87 and 3.0 for the benchmark problems considered in this study lead to the most accurate solution. The difference between the analytical and numerical results for the neutron flux is significantly increased in the edge of the problem geometry, even though the maximum difference is lower than 4%. This phenomenon seems to arise from the derivative boundary condition at (x,0) and (0,y) positions, and it may be necessary to introduce additional strategy (e.g., the method using fictitious points and

A relaxationprojection method for compressible flows. Part I: The numerical equation of state for the Euler equations
International Nuclear Information System (INIS)
Saurel, Richard; Franquet, Erwin; Daniel, Eric; Le Metayer, Olivier
20070101
A new projection method is developed for the Euler equations to determine the thermodynamic state in computational cells. It consists in the resolution of a mechanical relaxation problem between the various subvolumes present in a computational cell. These subvolumes correspond to the ones traveled by the various waves that produce states with different pressures, velocities, densities and temperatures. Contrarily to Godunov type schemes the relaxed state corresponds to mechanical equilibrium only and remains out of thermal equilibrium. The pressure computation with this relaxation process replaces the use of the conventional equation of state (EOS). A simplified relaxation method is also derived and provides a specific EOS (named the Numerical EOS). The use of the Numerical EOS gives a cure to spurious pressure oscillations that appear at contact discontinuities for fluids governed by real gas EOS. It is then extended to the computation of interface problems separating fluids with different EOS (liquidgas interface for example) with the Euler equations. The resulting method is very robust, accurate, oscillation free and conservative. For the sake of simplicity and efficiency the method is developed in a Lagrangeprojection context and is validated over exact solutions. In a companion paper [F. Petitpas, E. Franquet, R. Saurel, A relaxationprojection method for compressible flows. Part II: computation of interfaces and multiphase mixtures with stiff mechanical relaxation. J. Comput. Phys. (submitted for publication)], the method is extended to the numerical approximation of a nonconservative hyperbolic multiphase flow model for interface computation and shock propagation into mixtures

Solar cells elaborated by chemical methods: examples of research and development at CIEUNAM
International Nuclear Information System (INIS)
Rincon, Marina E.
20080101
Full text: At the Energy Research Center (CIEUNAMMexico), the major areas of renewable energy research are solar thermal energy, photovoltaic energy, geothermal energy, hydrogen energy, materials for renewable energy, and energy planning. Among the efforts to developed solar cells, both physical and chemical methods are in progress at CIEUNAM. In this contribution we focus on the advancement in efficiency, stability, and cost, of photovoltaic junctions based on chemically deposited films. Examples of early research are a composite thin film electrode comprised of SnO2/Bi2S3 nanocrystallites (5 nm) prepared by sequential deposition of SnO2 and Bi2S3 films onto an optically transparent electrode; the codeposition of pyrrole and Bi2S3 nanoparticles on chemically deposited bismuth sulfide substrates to explore new approaches to improve lightcollection efficiency in polymer photovoltaics; the sensitization of titanium dioxide coatings by chemically deposited cadmium selenide and bismuthe sulfide thin films. Here the good photostability of the coatings was promising for the use of the sensitized films in photocatalytic as well as photovoltaic applications. More recently, chemically deposited cadmium sulfide thin films have been explored in planar hybrid heterojunctions with chemically synthesized poly 3octylthiophene, as well as allchemically deposited photovoltaic structures. Examples of the last are: chemically deposited thin films of CdS (80 nm), Sb2S3 (450 nm), and Ag2Se (150 nm) annealed at 300 C and integrated into a pin structure glass/SnO2:F/nCdS/Sb2S3/pAgSbSe2/Ag, showing Voc ∼ 550 mV and Jsc ∼ 2.3 mA/cm2 at 1 kW/m2 (tungsten halogen) intensity. Similarly, chemically deposited SnS (450nm) and CuS (80nm) thin films integrated in a photovoltaic structure SnO2:F/CdS/SnS/CuS/Ag, showing Voc>300 mV and Jsc up to 5 mA/cm2 under 850 W/m2 tungsten halogen illumination. These photovoltaic structures have been found to be stable over a period extending over

How far away is far enough for extracting numerical waveforms, and how much do they depend on the extraction method?
Energy Technology Data Exchange (ETDEWEB)
Pazos, Enrique [Department of Physics and Astronomy, 202 Nicholson Hall, Louisiana State University, Baton Rouge, LA 70803 (United States); Dorband, Ernst Nils [Department of Physics and Astronomy, 202 Nicholson Hall, Louisiana State University, Baton Rouge, LA 70803 (United States); Nagar, Alessandro [Dipartimento di Fisica, Politecnico di Torino, Corso Duca Degli Abruzzi 24, 10129 Torino (Italy); Palenzuela, Carlos [Department of Physics and Astronomy, 202 Nicholson Hall, Louisiana State University, Baton Rouge, LA 70803 (United States); Schnetter, Erik [Center for Computation and Technology, 216 Johnston Hall, Louisiana State University, Baton Rouge, LA 70803 (United States); Tiglio, Manuel [Department of Physics and Astronomy, 202 Nicholson Hall, Louisiana State University, Baton Rouge, LA 70803 (United States)
20070621
in the extracted waves, compared to the standard method, by between one and three orders of magnitude. In a general scenario, for example a collision of compact objects, there is no precise definition of gravitational radiation at a finite distance, and gravitational wave extraction methods at such distances are thus inherently approximate. The results of this paper bring up the possibility that different choices in the wave extraction procedure at a fixed and finite distance may result in relative differences in the waveforms which are actually larger than the numerical errors in the solution.

How far away is far enough for extracting numerical waveforms, and how much do they depend on the extraction method?
International Nuclear Information System (INIS)
Pazos, Enrique; Dorband, Ernst Nils; Nagar, Alessandro; Palenzuela, Carlos; Schnetter, Erik; Tiglio, Manuel
20070101
in the extracted waves, compared to the standard method, by between one and three orders of magnitude. In a general scenario, for example a collision of compact objects, there is no precise definition of gravitational radiation at a finite distance, and gravitational wave extraction methods at such distances are thus inherently approximate. The results of this paper bring up the possibility that different choices in the wave extraction procedure at a fixed and finite distance may result in relative differences in the waveforms which are actually larger than the numerical errors in the solution

Assessment of highresolution methods for numerical simulations of compressible turbulence with shock waves
International Nuclear Information System (INIS)
Johnsen, Eric; Larsson, Johan; Bhagatwala, Ankit V.; Cabot, William H.; Moin, Parviz; Olson, Britton J.; Rawat, Pradeep S.; Shankar, Santhosh K.; Sjoegreen, Bjoern; Yee, H.C.; Zhong Xiaolin; Lele, Sanjiva K.
20100101
Flows in which shock waves and turbulence are present and interact dynamically occur in a wide range of applications, including inertial confinement fusion, supernovae explosion, and scramjet propulsion. Accurate simulations of such problems are challenging because of the contradictory requirements of numerical methods used to simulate turbulence, which must minimize any numerical dissipation that would otherwise overwhelm the small scales, and shockcapturing schemes, which introduce numerical dissipation to stabilize the solution. The objective of the present work is to evaluate the performance of several numerical methods capable of simultaneously handling turbulence and shock waves. A comprehensive range of highresolution methods (WENO, hybrid WENO/central difference, artificial diffusivity, adaptive characteristicbased filter, and shock fitting) and suite of test cases (TaylorGreen vortex, ShuOsher problem, shockvorticity/entropy wave interaction, Noh problem, compressible isotropic turbulence) relevant to problems with shocks and turbulence are considered. The results indicate that the WENO methods provide sharp shock profiles, but overwhelm the physical dissipation. The hybrid method is minimally dissipative and leads to sharp shocks and wellresolved broadband turbulence, but relies on an appropriate shock sensor. Artificial diffusivity methods in which the artificial bulk viscosity is based on the magnitude of the strainrate tensor resolve vortical structures well but damp dilatational modes in compressible turbulence; dilatationbased artificial bulk viscosity methods significantly improve this behavior. For welldefined shocks, the shock fitting approach yields good results.

Development of a set of benchmark problems to verify numerical methods for solving burnup equations
International Nuclear Information System (INIS)
Lago, Daniel; Rahnema, Farzad
20170101
Highlights: • Description transmutation chain benchmark problems. • Problems for validating numerical methods for solving burnup equations. • Analytical solutions for the burnup equations. • Numerical solutions for the burnup equations.  Abstract: A comprehensive set of transmutation chain benchmark problems for numerically validating methods for solving burnup equations was created. These benchmark problems were designed to challenge both traditional and modern numerical methods used to solve the complex set of ordinary differential equations used for tracking the change in nuclide concentrations over time due to nuclear phenomena. Given the development of most burnup solvers is done for the purpose of coupling with an established transport solution method, these problems provide a useful resource in testing and validating the burnup equation solver before coupling for use in a lattice or core depletion code. All the relevant parameters for each benchmark problem are described. Results are also provided in the form of reference solutions generated by the Mathematica tool, as well as additional numerical results from MATLAB.

Development of CAD implementing the algorithm of boundary elements’ numerical analytical method
Directory of Open Access Journals (Sweden)
Yulia V. Korniyenko
20150301
Full Text Available Up to recent days the algorithms for numericalanalytical boundary elements method had been implemented with programs written in MATLAB environment language. Each program had a local character, i.e. used to solve a particular problem: calculation of beam, frame, arch, etc. Constructing matrices in these programs was carried out “manually” therefore being timeconsuming. The research was purposed onto a reasoned choice of programming language for new CAD development, allows to implement algorithm of numerical analytical boundary elements method and to create visualization tools for initial objects and calculation results. Research conducted shows that among wide variety of programming languages the most efficient one for CAD development, employing the numerical analytical boundary elements method algorithm, is the Java language. This language provides tools not only for development of calculating CAD part, but also to build the graphic interface for geometrical models construction and calculated results interpretation.

Preface of "The Second Symposium on Border Zones Between Experimental and Numerical Application Including Solution Approaches By Extensions of Standard Numerical Methods"
Science.gov (United States)
Ortleb, Sigrun; Seidel, Christian
20170701
In this second symposium at the limits of experimental and numerical methods, recent research is presented on practically relevant problems. Presentations discuss experimental investigation as well as numerical methods with a strong focus on application. In addition, problems are identified which require a hybrid experimentalnumerical approach. Topics include fast explicit diffusion applied to a geothermal energy storage tank, noise in experimental measurements of electrical quantities, thermal fluid structure interaction, tensegrity structures, experimental and numerical methods for Chladni figures, optimized construction of hydroelectric power stations, experimental and numerical limits in the investigation of rainwind induced vibrations as well as the application of exponential integrators in a domainbased IMEX setting.

A numerical simulation method and analysis of a complete thermoacousticStirling engine.
Science.gov (United States)
Ling, Hong; Luo, Ercang; Dai, Wei
20061222
Thermoacoustic prime movers can generate pressure oscillation without any moving parts on selfexcited thermoacoustic effect. The details of the numerical simulation methodology for thermoacoustic engines are presented in the paper. First, a fourport network method is used to build the transcendental equation of complex frequency as a criterion to judge if temperature distribution of the whole thermoacoustic system is correct for the case with given heating power. Then, the numerical simulation of a thermoacousticStirling heat engine is carried out. It is proved that the numerical simulation code can run robustly and output what one is interested in. Finally, the calculated results are compared with the experiments of the thermoacousticStirling heat engine (TASHE). It shows that the numerical simulation can agrees with the experimental results with acceptable accuracy.

An analytically based numerical method for computing view factors in real urban environments
Science.gov (United States)
Lee, DooIl; Woo, JuWan; Lee, SangHyun
20180101
A view factor is an important morphological parameter used in parameterizing incanyon radiative energy exchange process as well as in characterizing local climate over urban environments. For realistic representation of the incanyon radiative processes, a complete set of view factors at the horizontal and vertical surfaces of urban facets is required. Various analytical and numerical methods have been suggested to determine the view factors for urban environments, but most of the methods provide only skyview factor at the ground level of a specific location or assume simplified morphology of complex urban environments. In this study, a numerical method that can determine the skyview factors ( ψ ga and ψ wa ) and wallview factors ( ψ gw and ψ ww ) at the horizontal and vertical surfaces is presented for application to real urban morphology, which are derived from an analytical formulation of the view factor between two blackbody surfaces of arbitrary geometry. The established numerical method is validated against the analytical skyview factor estimation for ideal street canyon geometries, showing a consolidate confidence in accuracy with errors of less than 0.2 %. Using a threedimensional building database, the numerical method is also demonstrated to be applicable in determining the skyview factors at the horizontal (roofs and roads) and vertical (walls) surfaces in real urban environments. The results suggest that the analytically based numerical method can be used for the radiative process parameterization of urban numerical models as well as for the characterization of local urban climate.

An analyticalnumerical comprehensive method for optimizing the fringing magnetic field
International Nuclear Information System (INIS)
Xiao Meiqin; Mao Naifeng
19910101
The criterion of optimizing the fringing magnetic field is discussed, and an analyticalnumerical comprehensive method for realizing the optimization is introduced. The method mentioned above consists of two parts, the analytical part calculates the field of the shims, which corrects the fringing magnetic field by using uniform magnetizing method; the numerical part fulfils the whole calculation of the field distribution by solving the equation of magnetic vector potential A within the region covered by arbitrary triangular meshes with the aid of finite difference method and successive over relaxation method. On the basis of the method, the optimization of the fringing magnetic field for a largescale electromagnetic isotope separator is finished

Numerical simulation for fractional order stationary neutron transport equation using Haar wavelet collocation method
Energy Technology Data Exchange (ETDEWEB)
Saha Ray, S., Email: santanusaharay@yahoo.com; Patra, A.
20141015
Highlights: • A stationary transport equation has been solved using the technique of Haar wavelet collocation method. • This paper intends to provide the great utility of Haar wavelets to nuclear science problem. • In the present paper, twodimensional Haar wavelets are applied. • The proposed method is mathematically very simple, easy and fast.  Abstract: In this paper the numerical solution for the fractional order stationary neutron transport equation is presented using Haar wavelet Collocation Method (HWCM). Haar wavelet collocation method is efficient and powerful in solving wide class of linear and nonlinear differential equations. This paper intends to provide an application of Haar wavelets to nuclear science problems. This paper describes the application of Haar wavelets for the numerical solution of fractional order stationary neutron transport equation in homogeneous medium with isotropic scattering. The proposed method is mathematically very simple, easy and fast. To demonstrate about the efficiency and applicability of the method, two test problems are discussed.

Numerical methods for the simulation of particle generated electromagnetic fields in acclerator physics
International Nuclear Information System (INIS)
Lau, T.
20060101
In this work modifications of the classical ParticleInCell method for the solution of the MaxwellVlasov equations are investigated with respect to their application in particle accelerator physics. The aim of the work is to find modifications of the method which minimize and under certain conditions even eliminate the numerical dispersion effect along the beam axis in the numerical solution of Maxwell's equations. This is achieved by the development of dedicated timeintegration methods for the Finite Integration Technique and two Finite Volume Methods. The methods are theoretically investigated regarding the conservation of a discrete energy and the existence of a discrete continuity equation. Finally, some of the methods are applied to the simulation of a high frequency rfgun. (orig.)

Monotone numerical methods for finitestate meanfield games
KAUST Repository
Gomes, Diogo A.; Saude, Joao
20170101
Here, we develop numerical methods for finitestate meanfield games (MFGs) that satisfy a monotonicity condition. MFGs are determined by a system of differential equations with initial and terminal boundary conditions. These nonstandard conditions are the main difficulty in the numerical approximation of solutions. Using the monotonicity condition, we build a flow that is a contraction and whose fixed points solve the MFG, both for stationary and timedependent problems. We illustrate our methods in a MFG modeling the paradigmshift problem.

Numerical method for solving the threedimensional timedependent neutron diffusion equation
International Nuclear Information System (INIS)
Khaled, S.M.; Szatmary, Z.
20050101
A numerical timeimplicit method has been developed for solving the coupled threedimensional timedependent multigroup neutron diffusion and delayed neutron precursor equations. The numerical stability of the implicit computation scheme and the convergence of the iterative associated processes have been evaluated. The computational scheme requires the solution of large linear systems at each time step. For this purpose, the point overrelaxation GaussSeidel method was chosen. A new scheme was introduced instead of the usual source iteration scheme. (author)

Solution methods for compartment models of transport through the environment using numerical inversion of Laplace transforms
International Nuclear Information System (INIS)
Garratt, T.J.
19890501
Compartment models for the transport of radionuclides in the biosphere are conventionally solved using a numerical timestepping procedure. This report examines an alternative method based on the numerical inversion of Laplace transforms, which is potentially more efficient and accurate for some classes of problem. The central problem considered is the most efficient and robust technique for solving the Laplacetransformed rate equations. The conclusion is that Gaussian elimination is the most efficient and robust solution method. A general compartment model has been implemented on a personal computer and used to solve a realistic case including radionuclide decay chains. (author)

NUMERICAL METHODS FOR SOLVING THE MULTITERM TIMEFRACTIONAL WAVEDIFFUSION EQUATION.
Science.gov (United States)
Liu, F; Meerschaert, M M; McGough, R J; Zhuang, P; Liu, Q
20130301
In this paper, the multiterm timefractional wavediffusion equations are considered. The multiterm time fractional derivatives are defined in the Caputo sense, whose orders belong to the intervals [0,1], [1,2), [0,2), [0,3), [2,3) and [2,4), respectively. Some computationally effective numerical methods are proposed for simulating the multiterm timefractional wavediffusion equations. The numerical results demonstrate the effectiveness of theoretical analysis. These methods and techniques can also be extended to other kinds of the multiterm fractional timespace models with fractional Laplacian.