WorldWideScience
 
 
1

Testing validity of the Tafel extrapolation method for monitoring corrosion of cold rolled steel in HCl solutions - Experimental and theoretical studies  

Energy Technology Data Exchange (ETDEWEB)

The protection influence of glycine (Gly) and a one of its derivatives, namely 2-(bis(2-aminoethyl)amino) acetic acid, designated here as GlyD; where GlyD stands for 'glycine derivative', against cold rolled steel (CRS) corrosion was studied in aerated stagnant 1.0 M HCl solutions at 25 deg. C. Measurements were conducted under various experimental conditions using Tafel polarization, linear polarization and impedance techniques. These studies have shown that Gly and GlyD are very good 'green', mixed-type inhibitors. GlyD is more effective than Gly itself in inhibiting the acid corrosion of CRS. Electrochemical frequency modulation (EFM) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) method of analysis are also presented here for monitoring corrosion. Corrosion rates obtained from both EFM and ICP-AES methods are comparable with those recorded using Tafel extrapolation method, confirming validation of corrosion rates measured by the latter. Adsorption via H-bond is discussed here, based on the presence of oxide film on the electrode surface as well as the number of NH linkages in the inhibitor molecule. Quantum chemical method was also employed to explore the relationship between the inhibitor molecular properties and its protection efficiency. The density function theory (DFT) is used to study the structural properties of Gly and GlyD in aqueous phase in an attempt to understand their inhibition mechanism. The protection efficiencies of these compounds showed a certain relationship to highest occupied molecular orbital (HOMO) energy, Mulliken atomic charges and Fukui indices.

Amin, Mohammed A. [Chemistry Department, Faculty of Science, Ain Shams University, Abbassia, Cairo (Egypt)], E-mail: maaismail@yahoo.com; Khaled, K.F. [Chemistry Department, Faculty of Education, Ain Shams University, Roxi, Cairo (Egypt); Fadl-Allah, Sahar A. [Chemistry Department, Faculty of Science, Cairo University, Giza (Egypt)

2010-01-15

2

Testing validity of the Tafel extrapolation method for monitoring corrosion of cold rolled steel in HCl solutions - Experimental and theoretical studies  

International Nuclear Information System (INIS)

The protection influence of glycine (Gly) and a one of its derivatives, namely 2-(bis(2-aminoethyl)amino) acetic acid, designated here as GlyD; where GlyD stands for 'glycine derivative', against cold rolled steel (CRS) corrosion was studied in aerated stagnant 1.0 M HCl solutions at 25 deg. C. Measurements were conducted under various experimental conditions using Tafel polarization, linear polarization and impedance techniques. These studies have shown that Gly and GlyD are very good 'green', mixed-type inhibitors. GlyD is more effective than Gly itself in inhibiting the acid corrosion of CRS. Electrochemical frequency modulation (EFM) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) method of analysis are also presented here for monitoring corrosion. Corrosion rates obtained from both EFM and ICP-AES methods are comparable with those recorded using Tafel extrapolation method, confirming validation of corrosion rates measured by the latter. Adsorption via H-bond is discussed here, based on the presence of oxide film on the electrode surface as well as the number of NH linkages in the inhibitor molecule. Quantum chemical method was also employed to explore the relationship between the inhibitor molecular properties and its protection efficiency. The density function theory (DFT) is used to study the structural properties of Gly and GlyD in aqueous phase in an attempt to understand their inhibition mechanism. The protection efficiencies of these compounds showed a certain relationship to highest occupied molecular orbital (HOMO) energy, Mulliken atomic charges and Fukui indices.

2010-01-01

3

Electrochemical frequency modulation and inductively coupled plasma atomic emission spectroscopy methods for monitoring corrosion rates and inhibition of low alloy steel corrosion in HCl solutions and a test for validity of the Tafel extrapolation method  

International Nuclear Information System (INIS)

The inhibition effect of glycine (Gly) towards the corrosion of low alloy steel ASTM A213 grade T22 boiler steel was studied in aerated stagnant 0.50 M HCl solutions in the temperature range 20-60 deg. C using potentiodynamic polarization (Tafel polarization and linear polarization) and impedance techniques, complemented with scanning electron microscope (SEM) and energy dispersive X-ray (EDX). Electrochemical frequency modulation (EFM), a non-destructive corrosion measurement technique that can directly give values of corrosion current without prior knowledge of Tafel constants, is also presented here. Experimental corrosion rates determined by the Tafel extrapolation method are compared with corrosion rates obtained by electrochemical, namely EFM technique, and chemical (i.e., non-electrochemical) method for steel in HCl. The chemical method of confirmation of the corrosion rates involved determination of the dissolved cation, using ICP-AES (inductively coupled plasma atomic emission spectrometry) method of analysis. Corrosion rates (in mm y-1) obtained from the electrochemical (Tafel extrapolation and EFM) and the chemical method, ICP, are in a good agreement. Polarization studies have shown that Gly is a good 'green', mixed-type inhibitor with cathodic predominance. The inhibition process was attributed to the formation of an adsorbed film on the metal surface that protects the metal against corrosive agents. Scanning electron microscopy (SEM) and energy dispersion X-ray (EDX) examinations of the electrode surface confirmed the existence of such an adsorbed film. The inhibition efficiency increases with increase in Gly concentration, while it decreases with solution temperature. Temkin isotherm is successfully applied to describe the adsorption process. Thermodynamic functions for the adsorption process were determined.

2009-04-01

4

Electrochemical frequency modulation and inductively coupled plasma atomic emission spectroscopy methods for monitoring corrosion rates and inhibition of low alloy steel corrosion in HCl solutions and a test for validity of the Tafel extrapolation method  

Energy Technology Data Exchange (ETDEWEB)

The inhibition effect of glycine (Gly) towards the corrosion of low alloy steel ASTM A213 grade T22 boiler steel was studied in aerated stagnant 0.50 M HCl solutions in the temperature range 20-60 deg. C using potentiodynamic polarization (Tafel polarization and linear polarization) and impedance techniques, complemented with scanning electron microscope (SEM) and energy dispersive X-ray (EDX). Electrochemical frequency modulation (EFM), a non-destructive corrosion measurement technique that can directly give values of corrosion current without prior knowledge of Tafel constants, is also presented here. Experimental corrosion rates determined by the Tafel extrapolation method are compared with corrosion rates obtained by electrochemical, namely EFM technique, and chemical (i.e., non-electrochemical) method for steel in HCl. The chemical method of confirmation of the corrosion rates involved determination of the dissolved cation, using ICP-AES (inductively coupled plasma atomic emission spectrometry) method of analysis. Corrosion rates (in mm y{sup -1}) obtained from the electrochemical (Tafel extrapolation and EFM) and the chemical method, ICP, are in a good agreement. Polarization studies have shown that Gly is a good 'green', mixed-type inhibitor with cathodic predominance. The inhibition process was attributed to the formation of an adsorbed film on the metal surface that protects the metal against corrosive agents. Scanning electron microscopy (SEM) and energy dispersion X-ray (EDX) examinations of the electrode surface confirmed the existence of such an adsorbed film. The inhibition efficiency increases with increase in Gly concentration, while it decreases with solution temperature. Temkin isotherm is successfully applied to describe the adsorption process. Thermodynamic functions for the adsorption process were determined.

Amin, Mohammed A. [Chemistry Department, Faculty of Science, Ain Shams University, Al-Khalefah Al-Maamoon St., Abbassia, Cairo 11566 (Egypt)], E-mail: maaismail@yahoo.com; Abd El Rehim, Sayed S. [Chemistry Department, Faculty of Science, Ain Shams University, Al-Khalefah Al-Maamoon St., Abbassia, Cairo 11566 (Egypt); Abdel-Fatah, Hesham T.M. [Central Chemical Laboratories, Egyptian Electricity Holding Company, Sabtia, Cairo (Egypt)

2009-04-15

5

The use of Tafel back extrapolation to clarify the influence of ruthenium and palladium alloying on the corrosion behaviour of titanium in concentrated hydrochloric acid  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Tafel back extrapolation of the cathodic reaction was used to interpret polarization data obtained for titanium alloyed with small amounts of ruthenium and palladium in concentrated hydrochloric acid. It was found that the ruthenium and palladium stimulated the cathodic reaction, but that the anodic behaviour of the titanium was unchanged. The results indicate that the corrosion of the titanium is increased by the small amount of alloying as the catalysis of the hydrogen reduction reaction wa...

2005-01-01

6

Evaluation of corrosion rate from polarisation curves not exhibiting a Tafel region  

International Nuclear Information System (INIS)

Evaluation of corrosion rate by Tafel extrapolation is often impossible, simply because an experimental polarisation curve does not exhibit linear Tafel regions. This paper shows how such curves for the Fe/H2O/H+/O2 corrosion system can be accurately deconstructed to furnish both kinetic and thermodynamic parameters for the anodic and cathodic reactions. The curved anodic branch (due to film formation) is then amenable to correction for IR voltage drop and the resulting Tafel slope and other parameters are then substituted in the Tafel equation to accurately determine i corr. An alternative method to obtain the anodic Tafel slope has been used to validate the above approach. Polarisation curves describing the inhibition of mild steel in industrial cooling water were scanned/digitised from the literature

2005-12-01

7

Evaluation of corrosion rate from polarisation curves not exhibiting a Tafel region  

Energy Technology Data Exchange (ETDEWEB)

Evaluation of corrosion rate by Tafel extrapolation is often impossible, simply because an experimental polarisation curve does not exhibit linear Tafel regions. This paper shows how such curves for the Fe/H{sub 2}O/H{sup +}/O{sub 2} corrosion system can be accurately deconstructed to furnish both kinetic and thermodynamic parameters for the anodic and cathodic reactions. The curved anodic branch (due to film formation) is then amenable to correction for IR voltage drop and the resulting Tafel slope and other parameters are then substituted in the Tafel equation to accurately determine i {sub corr}. An alternative method to obtain the anodic Tafel slope has been used to validate the above approach. Polarisation curves describing the inhibition of mild steel in industrial cooling water were scanned/digitised from the literature.

Flitt, Harvey J. [School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001 (Australia); Schweinsberg, D. Paul [School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001 (Australia)]. E-mail: p.schweinsberg@qut.edu.au

2005-12-15

8

Extrapolation methods for dynamic partial differential equations  

Science.gov (United States)

Several extrapolation procedures are presented for increasing the order of accuracy in time for evolutionary partial differential equations. These formulas are based on finite difference schemes in both the spatial and temporal directions. On practical grounds the methods are restricted to schemes that are fourth order in time and either second, fourth or sixth order in space. For hyperbolic problems the second order in space methods are not useful while the fourth order methods offer no advantage over the Kreiss-Oliger method unless very fine meshes are used. Advantages are first achieved using sixth order methods in space coupled with fourth order accuracy in time. Computational results are presented confirming the analytic discussions.

Turkel, E.

1978-01-01

9

Extrapolation Method for Shell Model Calculations with Projected Deformed Basis  

International Nuclear Information System (INIS)

Exact solution of large-scale shell model calculations can be obtained, in a well-controlled manner, by energy variance extrapolation method with spherical and deformed bases. The extrapolation formula including H3 matrix element is presented in shell model calculation. It is also shown that energy variance extrapolation with deformed basis is quite promising for huge shell model calculations, and its feasibility is shown in f p shell calculation

2006-04-26

10

Multiparameter extrapolation and deflation methods for solving equation systems  

Directory of Open Access Journals (Sweden)

Full Text Available Most models in economics and the applied sciences are solved by first order iterative techniques, usually those based on the Gauss-Seidel algorithm. This paper examines the convergence of multiparameter extrapolations (accelerations of first order iterations, as an improved approximation to the Newton method for solving arbitrary nonlinear equation systems. It generalises my earlier results on single parameter extrapolations. Richardson's generalised method and the deflation method for detecting successive solutions in nonlinear equation systems are also presented as multiparameter extrapolations of first order iterations. New convergence results are obtained for those methods.

A. J. Hughes Hallett

1984-12-01

11

Implicit extrapolation methods for multilevel finite element computations  

Energy Technology Data Exchange (ETDEWEB)

The finite element package FEMGP has been developed to solve elliptic and parabolic problems arising in the computation of magnetic and thermomechanical fields. FEMGP implements various methods for the construction of hierarchical finite element meshes, a variety of efficient multilevel solvers, including multigrid and preconditioned conjugate gradient iterations, as well as pre- and post-processing software. Within FEMGP, multigrid {tau}-extrapolation can be employed to improve the finite element solution iteratively to higher order. This algorithm is based on an implicit extrapolation, so that the algorithm differs from a regular multigrid algorithm only by a slightly modified computation of the residuals on the finest mesh. Another advantage of this technique is, that in contrast to explicit extrapolation methods, it does not rely on the existence of global error expansions, and therefore neither requires uniform meshes nor global regularity assumptions. In the paper the authors will analyse the {tau}-extrapolation algorithm and present experimental results in the context of the FEMGP package. Furthermore, the {tau}-extrapolation results will be compared to higher order finite element solutions.

Jung, M.; Ruede, U. [Technische Universitaet Chemnitz-Zwickau (Germany)

1994-12-31

12

Assessment of Load Extrapolation Methods for Wind Turbines  

DEFF Research Database (Denmark)

In the present paper, methods for statistical load extrapolation of wind-turbine response are studied using a stationary Gaussian process model, which has approximately the same spectral properties as the response for the out-of-plane bending moment of a windturbine blade. For a Gaussian process, an approximate analytical solution for the distribution of the peaks is given by Rice. In the present paper, three different methods for statistical load extrapolation are compared with the analytical solution for one mean wind speed. The methods considered are global maxima, block maxima, and the peak over threshold method with two different threshold values. The comparisons show that the goodness of fit for the local distribution has a significant influence on the results, but the peak over threshold method with a threshold value on the mean plus 1.4 standard deviations generally gives the best results. By considering Gaussian processes for 12 mean wind speeds, the â??fitting before aggregationâ? and â??aggregation before fittingâ? approaches are studied. The results show that the fitting before aggregation approach gives the best results.

Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

2011-01-01

13

The extrapolated successive overrelaxation (ESOR method for consistently ordered matrices  

Directory of Open Access Journals (Sweden)

Full Text Available This paper develops the theory of the Extrapolated Successive Overrelaxation (ESOR method as introduced by Sisler in [1], [2], [3] for the numerical solution of large sparse linear systems of the form Au=b, when A is a consistently ordered 2-cyclic matrix with non-vanishing diagonal elements and the Jacobi iteration matrix B possesses only real eigenvalues. The region of convergence for the ESOR method is described and the optimum values of the involved parameters are also determined. It is shown that if the minimum of the moduli of the eigenvalues of B, μ¯ does not vanish, then ESOR attains faster rate of convergence than SOR when 1−μ¯2<(1−μ¯212, where μ¯ denotes the spectral radius of B.

D. J. Evans

1984-06-01

14

The splitting extrapolation method a new technique in numerical solution of multidimensional problems  

CERN Document Server

The splitting extrapolation method is a newly developed technique for solving multidimensional mathematical problems. It overcomes the difficulties arising from Richardson's extrapolation when applied to these problems and obtains higher accuracy solutions with lower cost and a high degree of parallelism. The method is particularly suitable for solving large scale scientific and engineering problems.This book presents applications of the method to multidimensional integration, integral equations and partial differential equations. It also gives an introduction to combination methods which are

Tao, Lu

1995-01-01

15

Nonlinear Force-Free Extrapolation of the Coronal Magnetic Field Based on the MHD Relaxation Method  

CERN Document Server

We develop a nonlinear force-free field (NLFFF) extrapolation code based on the magnetohydrodynamic (MHD) relaxation method. We extend the classical MHD relaxation method in two important ways. First, we introduce an algorithm initially proposed by cite{2002JCoPh.175..645D} to effectively clean the numerical errors associated with $nabla cdot vec{B}$. Second, the multi-grid type method is implemented in our NLFFF to perform direct analysis of the high-resolution magnetogram data. As a result of these two implementations, we successfully extrapolated the high resolution force-free field introduced by cite{1990ApJ...352..343L} with better accuracy in a drastically shorter time. We also applied our extrapolation method to the MHD solution obtained from the flux-emergence simulation by cite{2012ApJ...748...53M}. We found that NLFFF extrapolation may be less effective for reproducing areas higher than a half-domain, where some magnetic loops are found in a state of continuous upward expansion. However, an inverse ...

Inoue, S; Pandey, V S; Shiota., D; Kusano, K; Choe, G S; Kim, K S

2013-01-01

16

A method for the extrapolation of calibration data of PTC 6 throat tap nozzles  

Energy Technology Data Exchange (ETDEWEB)

This paper describes a precise method for extrapolating the coefficient of discharge of PTC 6 throat tap nozzles using all or most of the calibration data. Numerical examples are given using actual calibration data to describe this method. Because this method permits the use of all calibration data at or above Reynolds numbers of 1,000,000 it is a clear improvement over the PTC 6 -1976 method which permits only the highest single point.

Murdock, J.W. (Drexel Univ., Philadelphia, PA (USA)); Keyser, D.R. (Naval Air Development Center, Warminster, PA (USA))

1990-01-01

17

Study on two Methods for Nonlinear Force-free Extrapolation Based on Semi-Analytical Field  

CERN Multimedia

In this paper, two semi-analytical solutions of force free fields (\\citeauthor{low90}, \\citeyear{low90}) have been used to test two nonlinear force-free extrapolation methods. One is the boundary integral equation (BIE) method developed by \\citeauthor{yan00} (\\citeyear{yan00}), and another is the approximate vertical integration (AVI) method developed by \\citeauthor{son06} (\\citeyear{son06}). Some improvements for the AVI method have been taken to avoid the singular points in the process of calculation. It is found that the correlation coefficients between the first semi-analytical field and extrapolated field by BIE, and also that by improved AVI, are greater than $90\\%$ below a height 10 of the $64 \\times 64$ lower boundary. While for the second semi-analytical field, these correlation coefficients are greater than $80\\%$ below the same relative height. Although the differences between the semi-analytical solutions and the extrapolated fields exist for both BIE and AVI methods, these two methods can give re...

S., Liu; T, Su J T Song M

2014-01-01

18

New method of extrapolation of the resistance of a model planing boat to full size  

Science.gov (United States)

The previously employed method of extrapolating the total resistance to full size with lambda(exp 3) (model scale) and thereby foregoing a separate appraisal of the frictional resistance, was permissible for large models and floats of normal size. But faced with the ever increasing size of aircraft a reexamination of the problem of extrapolation to full size is called for. A method is described by means of which, on the basis of an analysis of tests on planing surfaces, the variation of the wetted surface over the take-off range is analytically obtained. The friction coefficients are read from Prandtl's curve for turbulent boundary layer with laminar approach. With these two values a correction for friction is obtainable.

Sottorf, W

1942-01-01

19

Accurate ab initio-based molecular potentials: from extrapolation methods to global modelling  

International Nuclear Information System (INIS)

Accurate molecular potentials are key in theoretical chemical physics and therefore demands for suitable modelling strategies remain pressing. In this combination of a review and new results, we shall address methods to: (i) extrapolate to the one-electron basis set limit, (ii) predict a higher-quality ab initio potential by electron correlation scaling and (iii) refine iteratively an ab initio-based potential through variational calculations to reach near spectroscopic accuracy

2007-09-01

20

Precise Numerical Results of IR-vertex and box integration with Extrapolation Method  

CERN Document Server

We present a new approach for obtaining very precise integration results for infrared vertex and box diagrams, where the integration is carried out directly without performing any analytic integration of Feynman parameters. Using an appropriate numerical integration routine with an extrapolation method, together with a multi-precision library, we have obtained integration results which agree with the analytic results to 10 digits even for such a very small photon mass as $10^{-150}$ GeV in the infrared vertex diagram.

Yuasa, F; Fujimoro, J; Hamaguchi, N; Ishikawa, T; Shimizu, Y

2007-01-01

 
 
 
 
21

Dynamics of Variable Valve Trains and Extrapolation Methods for Time-Stepping Schemes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Set-valued force laws and time-stepping integration schemes are used in the context of multi-body simulation for efficient and physically based modelling of technical systems with friction and impacts saving computational time. In the first part of this thesis, step size adjustment and extrapolation methods are used to improve time-stepping schemes with regard to integration order and time discretisation. Furthermore, parallel computing techniques are used within this approach to reduce compu...

Huber, Robert

2013-01-01

22

Two-dimensional extrapolation methods for texture analysis on CT scans  

International Nuclear Information System (INIS)

The application of texture analysis to medical images may require the calculation of texture descriptors on regions of interest (ROIs) that are not completely filled by the tissue under analysis. If a texture descriptor is calculated using such 'deficient' ROIs, the accuracy and computational speed may be adversely affected. This study applied 198 texture descriptors from five texture classes (first-order statistical, second-order statistical, Fourier, fractal, and Laws' filtered) to lung parenchyma ROIs automatically extracted from the thoracic CT scans of ten patients. Statistically significant differences in the values of 138 of these texture descriptors were demonstrated when calculated on deficient ROIs. Three extrapolation methods (mean fill, tiled fill, and CLEAN deconvolution) then were applied to correct the deficient ROIs. Texture descriptor values were calculated and compared for the original, deficient, and corrected ROIs (based on the three extrapolation methods). Each extrapolation method induced statistically significant improvements in texture descriptor accuracy for some subset of texture descriptors. CLEAN deconvolution improved the greatest number of descriptors, demonstrated the best overall accuracy, and created ROIs that were visually most similar to the original ROIs

2007-09-01

23

Investigation of applicability of extrapolation method for sample field determination in single-yoke measuring setup  

International Nuclear Information System (INIS)

In this work the single-yoke measuring technique is proposed to be optimized by extrapolation of a magnetic field profile to the sample surface for determination of the 'real' field inside the sample. It has been shown that this approach gives reasonable values of magnetic parameters and allows to solve the well-known problem of considerable fluctuations of the measurement results due to imperfections of the yoke-sample contact. The magnetization process with the single-yoke setup is considered on basis of the surface field measurements around the sample and their extrapolation to the sample surfaces. Advantages as well as drawbacks of the measuring procedure and of the suggested optimization method are discussed

2006-12-01

24

Temperature-extrapolation method for Implicit Monte Carlo - Radiation hydrodynamics calculations  

International Nuclear Information System (INIS)

We present a method for implementing temperature extrapolation in Implicit Monte Carlo solutions to radiation hydrodynamics problems. The method is based on a BDF-2 type integration to estimate a change in material temperature over a time step. We present results for radiation only problems in an infinite medium and for a 2-D Cartesian hohlraum problem. Additionally, radiation hydrodynamics simulations are presented for an RZ hohlraum problem and a related 3D problem. Our results indicate that improvements in noise and general behavior are possible. We present considerations for future investigations and implementations. (authors)

2013-05-05

25

Temperature-extrapolation method for Implicit Monte Carlo - Radiation hydrodynamics calculations  

Energy Technology Data Exchange (ETDEWEB)

We present a method for implementing temperature extrapolation in Implicit Monte Carlo solutions to radiation hydrodynamics problems. The method is based on a BDF-2 type integration to estimate a change in material temperature over a time step. We present results for radiation only problems in an infinite medium and for a 2-D Cartesian hohlraum problem. Additionally, radiation hydrodynamics simulations are presented for an RZ hohlraum problem and a related 3D problem. Our results indicate that improvements in noise and general behavior are possible. We present considerations for future investigations and implementations. (authors)

McClarren, R. G. [Department of Nuclear Engineering, Texas A and M University, 3133 TAMU, College Station, TX 77802 (United States); Urbatsch, T. J. [XTD-5: Air Force Systems, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 77845 (United States)

2013-07-01

26

Parametric method for estimation of dose-modifying factors: low-dose extrapolation limit  

International Nuclear Information System (INIS)

A parametric method for the estimation of dose-modifying factors (DMF) is developed, using the linear-quadratic model of radiation effect. The method presented generalizes DMFs to include ratios, such as relative biological effectiveness (RBE), which may vary with dose. A statistical test for constant DMF is derived and a limit to reliable low-dose extrapolation of estimates of the DMF is presented. The relationship of the method presented here to the usual ''straight-line'' method, and a recently developed nonparametric method is discussed. Using cell survival data for 16-MeV neutrons and 60Co, the RBE of 16-MeV neutrons is computed by all three methods for comparison

1977-01-01

27

Low-cost extrapolation method for maximal LTE radio base station exposure estimation: test and validation.  

Science.gov (United States)

An experimental validation of a low-cost method for extrapolation and estimation of the maximal electromagnetic-field exposure from long-term evolution (LTE) radio base station installations are presented. No knowledge on downlink band occupation or service characteristics is required for the low-cost method. The method is applicable in situ. It only requires a basic spectrum analyser with appropriate field probes without the need of expensive dedicated LTE decoders. The method is validated both in laboratory and in situ, for a single-input single-output antenna LTE system and a 2×2 multiple-input multiple-output system, with low deviations in comparison with signals measured using dedicated LTE decoders. PMID:23179190

Verloock, Leen; Joseph, Wout; Gati, Azeddine; Varsier, Nadège; Flach, Björn; Wiart, Joe; Martens, Luc

2013-06-01

28

2.5-D and 3-D DC resistivity modelling using an extrapolation cascadic multigrid method  

Science.gov (United States)

Multigrid methods are well known for their high efficiency in solving elliptic boundary value problems. In this study, an improved extrapolation cascadic multigrid (EXCMG) method is presented to solve large sparse systems of linear equations, which are discretized from both 2.5-D and 3-D DC resistivity modelling using the finite element methods. To increase the accuracy, the singularity generated by the source term is removed by reformulating the solution with the secondary potential. In addition, a set of new and efficient Fourier coefficient is presented to transform the solutions in the 2.5-D Fourier domain to the 3-D Cartesian domain. To show the efficiency and the ease-to-implement of EXCMG, we first implement the EXCMG methods to a two-layered model of both 2-D and 3-D and compare the results with the analytical solutions. It has been shown that the maximum relative error in apparent resistivity is no more than 0.4 per cent provided an appropriate grid size is chosen. Then the comparisons of EXCMG with two other iterative solvers [symmetric successive over-relaxation conjugate gradient (SSORCG) and incomplete Cholesky conjugate gradient (ICCG)] show that converging at a rate independent of the grid size, the EXCMG method is much more efficient than SSORCG and ICCG solvers. Moreover, the EXCMG method has been shown its potential for being generalized to large-scale 3-D problems, due to the fact that it becomes more efficient as the size of the problem increases.

Pan, Kejia; Tang, Jingtian

2014-06-01

29

Statistical Romberg extrapolation: A new variance reduction method and applications to option pricing  

CERN Multimedia

We study the approximation of $\\mathbb{E}f(X_T)$ by a Monte Carlo algorithm, where $X$ is the solution of a stochastic differential equation and $f$ is a given function. We introduce a new variance reduction method, which can be viewed as a statistical analogue of Romberg extrapolation method. Namely, we use two Euler schemes with steps $\\delta$ and $\\delta^{\\beta},0<\\beta<1$. This leads to an algorithm which, for a given level of the statistical error, has a complexity significantly lower than the complexity of the standard Monte Carlo method. We analyze the asymptotic error of this algorithm in the context of general (possibly degenerate) diffusions. In order to find the optimal $\\beta$ (which turns out to be $\\beta=1/2$), we establish a central limit type theorem, based on a result of Jacod and Protter for the asymptotic distribution of the error in the Euler scheme. We test our method on various examples. In particular, we adapt it to Asian options. In this setting, we have a CLT and, as a by-produc...

Kebaier, A

2005-01-01

30

New variational Monte Carlo method with an energy variance extrapolation for large-scale shell-model calculations  

CERN Document Server

We propose a new variational Monte Carlo (VMC) method with an energy variance extrapolation for large-scale shell-model calculations. This variational Monte Carlo is a stochastic optimization method with a projected correlated condensed pair state as a trial wave function, and is formulated with the M-scheme representation of projection operators, the Pfaffian and the Markov-chain Monte Carlo (MCMC). Using this method, we can stochastically calculate approximated yrast energies and electro-magnetic transition strengths. Furthermore, by combining this VMC method with energy variance extrapolation, we can estimate exact shell-model energies.

Mizusaki, Takahiro

2012-01-01

31

Linear extrapolation distance for a black cylindrical control rod with the pulsed neutron method  

International Nuclear Information System (INIS)

The objective of this experiment was to measure the linear extrapolation distance for a central black cylindrical control rod in a cylindrical water moderator. The radius for both the control rod and the moderator was varied. The pulsed neutron technique was used and the decay constant was measured for both a homogeneous and a heterogeneous system. From the difference in the decay constants the extrapolation distance could be calculated. The conclusion is that within experimental error it is safe to use the approximate formula given by Pellaud or the more exact one given by Kavenoky. We can also conclude that linear anisotropic scattering is accounted for in a correct way in the approximate formula given by Pellaud and Prinja and Williams

1978-01-01

32

An investigation of the relationship between extrapolation parameters and approximate solutions in solving fuzzy linear systems using refinement of jacobi over relaxation method  

International Nuclear Information System (INIS)

Extrapolation parameters in Refinement of Jacobi over Relation method in solving fuzzy linear systems were hypothesized to influence the rate of convergence. This paper aims to investigate the relationship between extrapolation parameters and approximate solutions of fuzzy linear systems when solved using Refinement of Jacobi over Relaxation method. The Algorithms of Refinement of Jacobi over Relaxation method are proposed based on the Jacobi method that specifically used in solving the system. A five by five fuzzy linear system is given to investigate the convergence to exact solution with three different values of extrapolation parameters. The numerical results show that there is a positive correlation between extrapolation parameter and convergence to exact solution. The three extrapolation parameters suggest that convergence to exact solution can be increased in line with the increase in the values of extrapolation parameters.

2013-04-26

33

Principal components analysis and polynomials as methods for the track extrapolation/interpolation for SAPHIR  

International Nuclear Information System (INIS)

A program to investigate the possibility of track extrapolation and interpolation for drift chambers with the Principal Components Analysis and polynoms was written for SAPHIR. The results for the most significant configurations at SAPHIR were pointed out. It was shown that the Principal Components Analysis is a good basis to write a fast track reconstruction program for a drift chamber using a global track model in an inhomogeneous magnetic field. A data input/output package was written, too. (orig.)

1991-01-01

34

Correction method for critical extrapolation of control-rods-rising during physical start-up of reactor with spatial effect  

International Nuclear Information System (INIS)

Reasons why the extrapolated critical curve obtained by lifting control rods is cambered during the physical start-up of a reactor are analyzed. Spatial flux deformation factor is introduced, and a new method, by which influences of spatial effect in the reactor are avoided additionally, is proposed based on what is achieved by removing source neutrons. The new method is employed to a real example. Comparing the new results with those of real physical start-up and achieved only by removing source neutrons, it is shown that the new method avoids cambering phenomenon of the extrapolated curve much better, and obtains more precise critical position of control rods, so the reactor will reach the criticality more safely. (authors)

2009-10-01

35

Preprocess the Photospheric Vector Magnetograms for NLFFF Extrapolation using a Potential Field Model and an Optimization Method  

CERN Multimedia

Numerical reconstruction/extrapolation of coronal nonlinear force-free magnetic field (NLFFF) usually takes the photospheric vector magnetogram as input at the bottom boundary. Magnetic field observed at the photosphere, however, contains force which is in conflict with the fundamental assumption of the force-free model and measurement noise which is unfavorable for practical computation. Preprocessing of the raw magnetogram has been proposed by Wiegelmann, Inhester, and Sakurai (2006) to remove the force and noise for providing better input for NLFFF modeling. In this paper we develop a new code of magnetogram preprocessing which is consistent with our extrapolation method CESE-MHD-NLFFF (Jiang, Feng, and Xiang, 2012; Jiang and Feng, 2012). Basing on a magnetic-splitting rule that a magnetic field can be split into a potential field part and a non-potential part, we split the magnetogram and deal with the two parts separately. Preprocessing of the magnetogram's potential part is based on a numerical potentia...

Jiang, Chaowei

2013-01-01

36

Comparison among creep rupture strength extrapolation methods with application to data for AISI 316 SS from Italy, France, U.K. and F.R.G  

International Nuclear Information System (INIS)

Inside Activity 3 ''Materials'' of WGCS, the member states UK and FRG have developed a work regarding extrapolation methods for creep data. This work has been done by comparising extrapolation methods in use in their countries by applying them to creep rupture strength data on AISI 316 SS obtained in UK and FRG. This work has been issued on April 1978 and the Community has dealed it to all Activity 3 Members. Italy, in the figure of NIRA S.p.A., has received, from the European Community a contract to extend the work to Italian and French data, using extrapolation methods currently in use in Italy. The work should deal with the following points: - Collect of Italian experimental data; - Chemical analysis on Italian Specimen; - Comparison among Italian experimental data with French, FRG and UK data; - Description of extrapolation methods in use in Italy; - Application of these extrapolation methods to Italian, French, British and Germany data; - Extensions of a Final Report

1982-01-01

37

Improvement of flux distribution calculation using the extrapolation method of Richardson  

International Nuclear Information System (INIS)

Richardson have advanced a method for increasing the accuracy in numerical solving of linear differential equations. So, he proposed several schemes for performing algorythms, in which various approximtion parameters are used. It has been proved that a linear combination of this solution under certain circumstances gives a higher accuracy. Starting from these facts the present paper descpibes the application of the Richardson's method in improving the neutron flux calculation by using the EXTERMINATOR-2-INPR code. The considered benchmark problem has been conceived by D.R.Vondy from ORNL-USA. It consists of solving the multigroup diffusion equations for homogeneous two-dimensional slab. The results obtained show the efficiency of the Richardson method in improving the neutron flux calculation and constitutes a basis for achieving algorythms for other categories of problems. (authors)

1982-01-01

38

Dilution-Extrapolation Hydrometer Method for Easy Determination of API Gravity of Heavily Weathered Hydrocarbons in Petroleum Contaminated Soil  

Directory of Open Access Journals (Sweden)

Full Text Available When crude petroleum is spilled onto soil, the oil’s properties have a large influence on the toxicity to soil organisms, the biodegradability of the oil, and potential for long term fertility problems in the soil. Furthermore, these properties of environmental concern are related to the crude’s density, commonly measured as API gravity. Currently, methods do not exist to determine the ºAPI of crude oil in contaminated soil. In this study a novel method is presented for the determination of API gravity in small volumes (< 10 ml of heavy and extra-heavy petroleum from contaminated soil. Is uses an economical and readily available solvent (diesel + automotive lubricating oil in a procedure based on the conventional hydrometer method, plus dilution-extrapolation techniques. It was validated with crude petroleum in the 27.1-15.0 ºAPI range, obtaining an excellent correlation with the conventional method (R = 0.996 and an error of less than 0.4% based on specific gravity. Potential applications of this method are discussed for petroleum contaminated soil.

Carlos M. Morales-Bautista

2012-12-01

39

Systematic Errors and Graphical Extrapolation.  

Science.gov (United States)

Presents a laboratory exercise designed to introduce graphical extrapolation. Major advantages of the method are in its simplicity and speed. The only measuring devices are a centimeter ruler and a micrometer caliper to check wall thickness. (JN)

Blickensderfer, Roger

1985-01-01

40

Mass transport corrected Tafel analysis of voltammetric waves: When can it be applied?  

International Nuclear Information System (INIS)

The derivations of mass transport corrected Tafel equations are presented for a heterogeneous electron transfer. It is shown that the equations are valid for an electrode which is uniformly accessible to the electroactive species in solution. It is also shown that the equations are valid for any electrode geometry when the electron transfer is fast and reversible and the chemical species involved have equal diffusion coefficients. The microdisc and tubular flow electrodes are used as examples of non-uniformly accessible electrodes. The case is considered when the electron transfer is fast and reversible, the electrode is non-uniformly accessible and the species involved have unequal diffusion coefficients. Under these conditions it is shown by analytical solution that the Tafel equation is valid at the tubular flow electrode when axial and radial diffusion are insignificant. It is shown by numerical solution that at the same electrode the Tafel equation is not valid when axial and radial diffusion are significant

2007-03-20

 
 
 
 
41

Life of the Tafel equation: Current understanding and prospects for the second century  

International Nuclear Information System (INIS)

The life of Tafel equation is considered briefly as evolution in the understanding of Tafel's empiric parameters in the framework of various phenomenological and theoretical approaches. Modern theories of the interfacial charge transfer reactions are employed to explain the behavior of transfer coefficient versus electrode overvoltage and deviations of this quantity from 0.5 at low overvoltage. The effects of intramolecular reorganization, orbital overlap, reactant quantum modes and solvent dynamics are addressed and illustrated by model calculations. An attempt is made to propose new explanations of some data reported in the literature

2007-03-01

42

Extraordinarily small Tafel slope for oxide formation reaction on Pt (1 1 1) surface  

International Nuclear Information System (INIS)

Oxide formation reaction current density on Pt (1 1 1) was estimated by time-differentiating oxide growth curves during a potential hold as a function of the potential and the coverage with the oxide below 0.35 ML (monolayer). The Tafel slope was 18–24 mV decade?1 in the condition where the Tafel plot is on a straight line. The reaction mechanism accounting for this small slope was proposed, in which the oxide formation process is assumed as a combination of a fast electron transfer step and a following slow step.

2012-09-01

43

On an accelerated procedure of extrapolation  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents some theoretical results concerning an extrapolation method, based on a completely consistent linear stationary iterative method of first degree, for the numerical solution of the linear system Au=b.The main purpose of the paper is to find ranges for the extrapolation parameter, such that the extrapolation method converges independently of whether the original iterative method is convergent or not.

A. Yeyios

1981-12-01

44

Stable explicit depth extrapolation of seismic wavefields  

Energy Technology Data Exchange (ETDEWEB)

Stable explicit filters for depth extrapolation of seismic wavefields may be derived through a modification of the conventional Taylor series method. The modified Taylor series method described here yields extrapolators with maximally-flat amplitude spectra in their passband, while ensuring that no spectral components in the wavefield are amplified by any factor greater than one. The price for stability is increased phase error. For low normalized frequencies, implicit extrapolators are more accurate than the 39-coefficient stable explicit extrapolator described here. However, the small spatial sampling intervals required to obtain high phase accuracy in implicit extrapolation imply that this accuracy is rarely achieved in practice. Over the wide range of normalized frequencies likely to be encountered in practice, stable explicit extrapolators outperform implicit ones. The method presented here for deriving stable explicit extrapolators is in no formal sense optimal. It is only guaranteed to yield stable extrapolators. In my limited experience with alternative methods for designing stable extrapolators, the method presented here produced the least phase error while ensuring stability. Nevertheless, a simple method for designing optimal (in some sense) stable explicit extrapolators would be preferred over the method presented here. 7 refs., 15 figs.

Hale, D.

1990-01-01

45

Extrapolated maximal oxygen consumption: a new method for the objective analysis of respiratory gas exchange during exercise.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Respiratory gas exchange was measured during maximal treadmill exercise testing in six healthy volunteers and 20 patients with chronic heart failure. A curve of equation y = ax-bx2 was used to model the relation between the rate of oxygen consumption (y axis) and the rate of carbon dioxide production (x axis). The constants "a" and "b" were used to calculate the maximal value of the expression ax-bx2. This value was termed the "extrapolated maximal oxygen consumption". For all subjects a clos...

Buller, N. P.; Poole-wilson, P. A.

1988-01-01

46

Impedance and Tafel-plot techniques of indium in acidic media  

International Nuclear Information System (INIS)

The corrosion and electrochemical behaviour of indium in various concentrations of hydrochloric and sulphuric acids have been studied using impedance and Tafel-plot measurements over cathodic and anodic regions. Numerical values of polarisation resistances, double layer capacitances, corrosion potentials and corrosion currents are calculated, compared and discussed. (author). 15 refs., 6 figs., 2 tabs

1993-01-01

47

Chiral extrapolation of lattice data  

CERN Multimedia

We propose analytic approximations of chiral SU(3) amplitudes for the extrapolation of lattice data to the physical meson masses. The method allows the determination of NNLO low-energy constants in a controllable fashion. We test the approach with recent lattice data for the ratio F_K/F_pi of meson decay constants.

Ecker, Gerhard; Neufeld, Helmut

2010-01-01

48

Finite lattice extrapolation algorithms  

International Nuclear Information System (INIS)

Two algorithms for sequence extrapolation, due to von den Broeck and Schwartz and Bulirsch and Stoer are reviewed and critically compared. Applications to three states and six states quantum chains and to the (2+1)D Ising model show that the algorithm of Bulirsch and Stoer is superior, in particular if only very few finite lattice data are available. (orig.)

1987-01-01

49

Optimal analytical extrapolations revisite  

International Nuclear Information System (INIS)

The problem of optimal analytic extrapolation of holomorphic functions from a finite set of interior data points to an other interior point is completely solved in the general case of data known with unequal errors. Simple and easily to handle algorithms are obtained. (author)

1982-01-01

50

Builtin vs. auxiliary detection of extrapolation risk.  

Energy Technology Data Exchange (ETDEWEB)

A key assumption in supervised machine learning is that future data will be similar to historical data. This assumption is often false in real world applications, and as a result, prediction models often return predictions that are extrapolations. We compare four approaches to estimating extrapolation risk for machine learning predictions. Two builtin methods use information available from the classification model to decide if the model would be extrapolating for an input data point. The other two build auxiliary models to supplement the classification model and explicitly model extrapolation risk. Experiments with synthetic and real data sets show that the auxiliary models are more reliable risk detectors. To best safeguard against extrapolating predictions, however, we recommend combining builtin and auxiliary diagnostics.

Munson, Miles Arthur; Kegelmeyer, W. Philip,

2013-02-01

51

Coherence extrapolation for underwater ambient noise.  

Science.gov (United States)

This paper considers extrapolation of the vertical coherence of surface-generated oceanic ambient noise to simulate measurements made on a longer sensor array. The extrapolation method consists of projecting the noise coherence measured with a limited aperture array into the domain spanned by prolate spheroidal wave functions, which are an orthogonal basis defined by array parameters and the noise frequency. Using simulated data corresponding to selected multi-layered seabeds as ground truth, the performance of the extrapolation method is explored. Application of the technique is also demonstrated on experimental data. PMID:24907840

Quijano, Jorge E; Dosso, Stan E; Siderius, Martin; Muzi, Lanfranco

2014-06-01

52

Far Field Extrapolation from Near Field Interactions and Shielding Influence Investigations Based on a FE-PEEC Coupling Method  

Directory of Open Access Journals (Sweden)

Full Text Available Regarding standards, it is well established that common mode currents are the main source of far field emitted by variable frequency drive (VFD-cable-motor associations. These currents are generated by the combination of floating potentials with stray capacitances between these floating potential tracks and the mechanical parts connected to the earth (the heatsink or cables are usual examples. Nowadays, due to frequency and power increases, the systematic compliance to EMC (ElectroMagnetic Compatibility becomes increasingly difficult and costly for industrials. As a consequence, there is a well-identified need to investigate practical and low cost solutions to reduce the radiated fields of VFD-cable-motor associations. A well-adapted solution is the shielding of wound components well known as the major source of near magnetic field. However, this solution is not convenient, it is expensive and may not be efficient regarding far field reduction. Optimizing the components placement could be a better and cheaper solution. As a consequence, dedicated tools have to be developed to efficiently investigate not easy comprehendible phenomena and finally to control EMC disturbances using component placement, layout geometry, shielding design if needed. However, none of the modeling methods usually used in industry complies with large frequency range and far field models including magnetic materials, multilayer PCBs, and shielding. The contribution of this paper is to show that alternatives regarding modeling solutions exist and can be used to get in-deep analysis of such complex structures. It is shown in this paper that near field investigations can give information on far field behavior. It is illustrated by an investigation of near field interactions and shielding influence using a FE-PEEC hybrid method. The test case combining a common mode filter with the floating potentials tracks of an inverter is based on an industrial and commercialized VFD. The near field interactions between the common mode inductance and the tracks with floating potentials are revealed. Then, the influence of the common mode inductance shielding is analyzed.

Gérard Meunier

2013-03-01

53

Determination of SIF for a Crack Emanating From a Rivet Hole in a Plate using Displacement Extrapolation Method  

Directory of Open Access Journals (Sweden)

Full Text Available Modern aircraft structures are designed using a damage tolerance philosophy. This design philosophy envisions sufficient strength and structural integrity to sustain major damage and to avoid catastrophic failure. The most likely places for crack initiating and development are the rivet holes, due to high stress concentration in this area. Such cracks may grow in time and reduces the lifetime of the sheet. The Stress Intensity Factor (SIF is one the most important parameters in fracture mechanics analysis. The objective of this work is to determine SIF (plane stress for a crack emanating from a rivet hole in a plate Finite Element Method (FEM. From this study it was observed that the value of SIF rises suddenly when the crack tip is near to the hole and drops down as the crack tip move far from the hole. The SIF values evaluated for different crack length is compared with the analytical values obtained from Bowie’s equation. This provides important information for subsequent studies such as the crack growth rate determination and prediction of residual strength.

H.V. Lakshminarayana

2012-01-01

54

SPATIAL EXTRAPOLATION OF ANISOTROPIC ROAD TRAFFIC DATA  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A method of spatial extrapolation of traffic data is proposed. The traffic data is given by GPS signals over downtown Berlin sent by approximately 300 taxis. To reconstruct the traffic situation at a given time spatially, i.e., in the form of traffic maps, kriging with moving neighborhood based on residuals is used. Due to significant anisotropy in directed traffic data, the classical kriging has to be modified in order to include additional information. To verify the extrapolation results, t...

2004-01-01

55

Gauging station rating curve extrapolation using HEC-RAS  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Rating curve represents stage-discharge relationship and is used to transform observed water level into discharge. At high water levels, the stage-discharge relationship often has to be extrapolated due to lack of measured data. The graduation thesis analyses rating curve extrapolation for gauging station Litija on river Sava. The intent of thesis is to narrow the expansion area of extrapolation. There are different methods for extrapolating stage-discharge relationships and most advanced of ...

S?upek, Miha

2008-01-01

56

Experimental check of the use of unconventional reference materials for EDS analysis in a TEM by extrapolation method based on pure elements  

Science.gov (United States)

In this work, the use of unconventional reference materials to determine experimentally the Cliff-Lorimer factor for EDS quantitative analysis with a TEM is checked by means of an alternative experimental procedure. The k-factor is determined by the extrapolation method based on pure elements, by measuring the normalized X-ray intensities emitted by thin films of pure gold and pure silver of different thickness, accurately measured by X-ray reflectivity. The goal of this work is to confirm the value of the k-factor previously obtained by the use of unconventional reference materials consisting of a bi-layer of pure gold on pure silver. The current result is in accordance with the previous one when considering their error bars, however, their relative difference is about 13 %, probably due to some uncertainties in mass thickness measurements. The mass thickness measurement of the layers of pure elements needs to be performed by different methods in order to reduce its uncertainty.

Nacucchi, M.; Alvisi, M.; Altamura, D.; Pfister, V.; Valerini, D.; Mello, D.; Giannini, C.

2012-03-01

57

Experimental check of the use of unconventional reference materials for EDS analysis in a TEM by extrapolation method based on pure elements  

International Nuclear Information System (INIS)

In this work, the use of unconventional reference materials to determine experimentally the Cliff-Lorimer factor for EDS quantitative analysis with a TEM is checked by means of an alternative experimental procedure. The k-factor is determined by the extrapolation method based on pure elements, by measuring the normalized X-ray intensities emitted by thin films of pure gold and pure silver of different thickness, accurately measured by X-ray reflectivity. The goal of this work is to confirm the value of the k-factor previously obtained by the use of unconventional reference materials consisting of a bi-layer of pure gold on pure silver. The current result is in accordance with the previous one when considering their error bars, however, their relative difference is about 13 %, probably due to some uncertainties in mass thickness measurements. The mass thickness measurement of the layers of pure elements needs to be performed by different methods in order to reduce its uncertainty.

2012-03-07

58

Species extrapolation for the 21st century.  

Science.gov (United States)

Safety factors are used in ecological risk assessments to extrapolate from the toxic responses of laboratory test species to all species representing that group in the environment. More accurate extrapolation of species responses is important. Advances in understanding the mechanistic basis for toxicological responses and identifying molecular response pathways can provide a basis for extrapolation across species and, in part, an explanation for the variability in whole organism responses to toxicants. We highlight potential short- and medium-term development goals to meet our long-term aspiration of truly predictive in silico extrapolation across wildlife species' response to toxicants. A conceptual approach for considering cross-species extrapolation is presented. Critical information is required to establish evidence-based species extrapolation, including identification of critical molecular pathways and regulatory networks that are linked to the biological mode of action and species' homologies. A case study is presented that examines steroidogenesis inhibition in fish after exposure to fadrozole or prochloraz. Similar effects for each compound among fathead minnow, medaka, and zebrafish were attributed to similar inhibitor pharmacokinetic/pharmacodynamic distributions and sequences of cytochrome P45019A1/2 (CYP19A1/2). Rapid advances in homology modeling allow the prediction of interactions of chemicals with enzymes, for example, CYP19 aromatase, which would eventually allow a prediction of potential aromatase toxicity of new compounds across a range of species. Eventually, predictive models will be developed to extrapolate across species, although substantial research is still required. Knowledge gaps requiring research include defining differences in life histories (e.g., reproductive strategies), understanding tissue-specific gene expression, and defining the role of metabolism on toxic responses and how these collectively affect the power of interspecies extrapolation methods. PMID:20963850

Celander, Malin C; Goldstone, Jared V; Denslow, Nancy D; Iguchi, Taisen; Kille, Peter; Meyerhoff, Roger D; Smith, Ben A; Hutchinson, Thomas H; Wheeler, James R

2011-01-01

59

Comparison of one-particle basis set extrapolation to explicitly correlated methods for the calculation of accurate quartic force fields, vibrational frequencies, and spectroscopic constants: application to H2O, N2H+, NO2+, and C2H2.  

Science.gov (United States)

One-particle basis set extrapolation is compared with one of the new R12 methods for computing highly accurate quartic force fields (QFFs) and spectroscopic data, including molecular structures, rotational constants, and vibrational frequencies for the H(2)O, N(2)H(+), NO(2)(+), and C(2)H(2) molecules. In general, agreement between the spectroscopic data computed from the best R12 and basis set extrapolation methods is very good with the exception of a few parameters for N(2)H(+) where it is concluded that basis set extrapolation is still preferred. The differences for H(2)O and NO(2)(+) are small and it is concluded that the QFFs from both approaches are more or less equivalent in accuracy. For C(2)H(2), however, a known one-particle basis set deficiency for C-C multiple bonds significantly degrades the quality of results obtained from basis set extrapolation and in this case the R12 approach is clearly preferred over one-particle basis set extrapolation. The R12 approach used in the present study was modified in order to obtain high precision electronic energies, which are needed when computing a QFF. We also investigated including core-correlation explicitly in the R12 calculations, but conclude that current approaches are lacking. Hence core-correlation is computed as a correction using conventional methods. Considering the results for all four molecules, it is concluded that R12 methods will soon replace basis set extrapolation approaches for high accuracy electronic structure applications such as computing QFFs and spectroscopic data for comparison to high-resolution laboratory or astronomical observations, provided one uses a robust R12 method as we have done here. The specific R12 method used in the present study, CCSD(T)(R12), incorporated a reformulation of one intermediate matrix in order to attain machine precision in the electronic energies. Final QFFs for N(2)H(+) and NO(2)(+) were computed, including basis set extrapolation, core-correlation, scalar relativity, and higher-order correlation and then used to compute highly accurate spectroscopic data for all isotopologues. Agreement with high-resolution experiment for (14)N(2)H(+) and (14)N(2)D(+) was excellent, but for (14)N(16)O(2)(+) agreement for the two stretching fundamentals is outside the expected residual uncertainty in the theoretical values, and it is concluded that there is an error in the experimental quantities. It is hoped that the highly accurate spectroscopic data presented for the minor isotopologues of N(2)H(+) and NO(2)(+) will be useful in the interpretation of future laboratory or astronomical observations. PMID:21197977

Huang, Xinchuan; Valeev, Edward F; Lee, Timothy J

2010-12-28

60

SPATIAL EXTRAPOLATION OF ANISOTROPIC ROAD TRAFFIC DATA  

Directory of Open Access Journals (Sweden)

Full Text Available A method of spatial extrapolation of traffic data is proposed. The traffic data is given by GPS signals over downtown Berlin sent by approximately 300 taxis. To reconstruct the traffic situation at a given time spatially, i.e., in the form of traffic maps, kriging with moving neighborhood based on residuals is used. Due to significant anisotropy in directed traffic data, the classical kriging has to be modified in order to include additional information. To verify the extrapolation results, test examples on the basis of a well-known model of stochastic geometry, the Boolean random function are considered.

Hans Braxmeier

2011-05-01

 
 
 
 
61

The extrapolated-efficiency method, a new technique to determine the ?-cascade detection efficiency in experiments based on the surrogate-reaction method  

International Nuclear Information System (INIS)

The surrogate-reaction method is an indirect technique to extract neutron-induced cross-sections of short-lived nuclei. In the last years several experiments have been performed to investigate whether this technique can be applied to infer radiative-capture cross-sections. A major difficulty in this type of measurements is the determination of the gamma-cascade detection efficiency. The pulse-height weighting technique (PHWT) has been previously used to determine this quantity in surrogate experiments. In this work, we present a new method to determine the gamma-cascade detection efficiency in the vicinity of the neutron-separation energy that is much simpler than the PHWT. We also investigate the possibility to apply this new technique in standard experiments using neutron beams.

2013-02-01

62

Statistical Extreme Load Extrapolation With Quadratic Distortions for Wind Turbines  

DEFF Research Database (Denmark)

Extrapolation of extreme loads using turbulent wind samples of various mean speeds and random starting points is addressed using probability distribution functions that are suitably distorted to fit the peak extremes. The tail of the extreme value distribution of the simulated loads is required to fit accurately and this tail is extrapolated to a 50-year exceedance probability to determine the characteristic load. The Gumbel distribution with a quadratic distortion is especially addressed due to its asymptotic theoretical validity for Gaussian loads. The blade root moments and the hub moments are studied here with respect to their behavior under extrapolation using a quadratic Gumbel distribution. Verification with a large number of random seeds at various mean wind speeds is done, so as to assess the accuracy of the extrapolation and the convergence of the extrapolated load. Methods of accounting for the variance in the extrapolated load with changes in the random wind seeds are proposed.

Natarajan, Anand; Holley, William E.

2008-01-01

63

Load Extrapolation During Operation for Wind Turbines  

DEFF Research Database (Denmark)

In the recent years load extrapolation for wind turbines has been widely considered in the wind turbine industry. Loads on wind turbines during operations are normally dependent on the mean wind speed, the turbulence intensity and the type and settings of the control system. All these parameters must be taken into account when characteristic load effects during operation are determined. In the wind turbine standard IEC 61400-1 a method for load extrapolation using the peak over threshold method is recommended. In this paper this method is considered and some of the assumptions are examined. The statistical uncertainty related to the limited number of simulations of the response during operation is explored together with the influence of the threshold value.

Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

2008-01-01

64

Wildlife toxicity extrapolations: Dose metric  

Energy Technology Data Exchange (ETDEWEB)

Ecotoxicological assessments must rely on the extrapolation of toxicity data from a few indicator species to many species of concern. Data are available from laboratory studies (e.g., quail, mallards, rainbow trout, fathead minnow) and some planned or serendipitous field studies of a broader, but by no means comprehensive, suite of species. Yet all ecological risk assessments begin with an estimate of risk based on information gleaned from the literature. One is then confronted with the necessity of extrapolating toxicity information from a limited number of indicator species to all organisms of interest. This is a particularly acute problem when trying to estimate hazards to wildlife in terrestrial systems as there is an extreme paucity of data for most chemicals in all but a handful of species. This section continues the debate by six panelists of the ``correct`` approach for determining wildlife toxicity thresholds by examining which dose metric to use for threshold determination and interspecific extrapolation, Since wild animals are exposed to environmental contaminants primarily through ingestion, should threshold values be expressed as amount of chemical in the diet (e.g., ppm) or as a body weight-adjusted dose (mg/kg/day)? Which of these two approaches is most relevant for ecological risk assessment decision making? Which is best for interspecific extrapolations? Converting from one metric to the other can compound uncertainty if the actual consumption rates of a species is unknown. How should this be dealt with? Is it of sufficient magnitude to be of concern?

Fairbrother, A. [Ecological Planning and Toxicology, Inc., Corvallis, OR (United States); Berg, M. van den [Univ. of Utrecht (Netherlands). Research Inst. of Toxicology

1995-12-31

65

Fuzzy Model Comparison to Extrapolate Rainfall Data  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This research presents two fuzzy rule-based models for extrapolating the missing rainfall data records of a station, utilizing as a reference the values from another meteorological station located in an adjacent area. The first one is constructed based on the least squares algorithm and the second one using ANFIS method. Three stations were used in this research, all located in Northern Greece. The values of Thessaloniki station were used as fuzzy premises and the values of Sindos and K...

Tzimopoulos, C.; Mpallas, L.; Evangelides, C.

2008-01-01

66

Modified Extrapolation Length Renormalization Group Equation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A modified renormalization group equation for the inverse extrapolation length $c$ is derived by considering the phase shifts of order parameter fluctuations. The resulting non-linear equation is also derived using standard methods and some additional assumptions. The associated renormalized flow $c(l)$ exhibits the correct behavior near both the special and ordinary fixed points and in particular yields a canonical scaling of $c$ with cross-over exponent $\\phi_{\\rm ord} = -...

Morris, Jacob; Rudnick, Joseph

1999-01-01

67

Chiral extrapolations for nucleon magnetic moments  

CERN Document Server

Lattice quantum chromodynamics (QCD) simulations have made significant progress in the calculation of nucleon electromagnetic form factors in the chiral regime in recent years. With simulation results achieving pion masses of order ~180 MeV, there is an apparent challenge as to how the physical regime is approached. By using contemporary methods in chiral effective field theory, both the quark-mass and finite-volume dependence of the isovector nucleon magnetic moment are carefully examined. The extrapolation to the physical point yields a result that is compatible with experiment, albeit with a combined statistical and systematic uncertainty of 10%. The extrapolation shows a strong finite-volume dependence; lattice sizes of L > 5 fm must be used to simulate results within 2% of the infinite-volume result for the magnetic moment at the physical pion mass.

Hall, J M M; Young, R D

2012-01-01

68

Extrapolating future Arctic ozone losses  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Future increases in the concentration of greenhouse gases and water vapour may cool the stratosphere further and increase the amount of polar stratospheric clouds (PSCs). Future Arctic PSC areas have been extrapolated from the highly significant trends 1958-2001. Using a tight correlation between PSC area and the total vortex ozone depletion and taking the decreasing amounts of ozone depleting substances into account we make empirical estimates of future ozone. The result is that Arctic ozone...

Knudsen, B. M.; Harris, N. R. P.; Andersen, S. B.; Christiansen, B.; Larsen, N.; Rex, M.; Naujokat, B.

2004-01-01

69

A brief survey of extrapolation quadrature.  

Energy Technology Data Exchange (ETDEWEB)

This is a short precis of a presentation on some of the recent advances in the area of extrapolation quadrature given at David Elliott's 65th birthday conference in Hobart in February 1997. Since the dawn of mathematics, historians and others have found many isolated instances of extrapolation being used in numerical calculation. However, the first serious proponent seems to have been Richardson (1923). His technique, also known as the 'deferred approach to the limit,' can be applied to the numerical evaluation of any quantity L, which can be defined as a limit as h approaches zero of an approximation L(h) when this L(h) has an expansion of the form L(h) = L + a{sub 1}h + a{sub 2}h{sup 2} + {hor_ellipsis} + a{sub r}h{sup r} + O(h{sup r+1}). In other words, the discretization error L(h) - L has a power series expansion in the parameter (usually a step length) h. Richardson suggested his technique particularly for large calculations. Richardson's technique comprised evaluating several relatively poor approximations based on different moderate values of h, and then extrapolating these values to obtain an approximately for L(0). This was proposed as an alternative to using a single, much smaller, value of h. During the subsequent 25 years, Richardson's approach was consistently ignored or misunderstood in environments where the analysis was available and, where in retrospect, the method would have been powerful, But, in the second half of the twentieth century, Richardson's idea has been widely exploited in several numerical areas. Many expansions that can be used for extrapolation have been discovered, some of which are displayed here. In the discipline of numerical quadrature, this body of theory is sometimes referred to as extrapolation quadrature. This theory has several aspects. The first, dealt with in this talk, is the establishment of the expansion. But also of significant importance are equations relating to is use: in particular, selecting which values of h to use, organizing such a calculation, avoiding amplification of roundoff and other calculational error, and comparing other methods for handling the same problem. This talk was devoted exclusively to the first problem, the discovery of suitable asymptotic expansions, and was restricted to numerical quadrature.

Lyness, J. N.; Mathematics and Computer Science

2000-07-01

70

Wildlife toxicity extrapolations: Measurement endpoints  

Energy Technology Data Exchange (ETDEWEB)

Ecotoxicological assessments must rely on the extrapolation of toxicity data from a few indicator species to many species of concern. Data are available from laboratory studies (e.g., quail, mallards, rainbow trout, fathead minnow) and some planned or serendipitous field studies of a broader, but by no means comprehensive, suite of species. Yet all ecological risk assessments begin with an estimate of risk based on information gleaned from the literature. One is then confronted with the necessity of extrapolating toxicity information from a limited number of indicator species to ail organisms of interest. This is a particularly acute problem when trying to estimate hazard to wildlife in terrestrial systems as there is an extreme paucity of data for most chemicals in all but a handful of species. This section continues the debate by six panelists of the ``correct`` approach for determining wildlife toxicity thresholds by examining which are the appropriate measurement endpoints. Should only mortality, growth, or reproductive endpoints be used? Since toxicity threshold values may be used to make management decisions, should values related to each measurement endpoint be presented to allow the risk assessor to choose the measurement endpoint most relevant to the assessment questions being asked, or is a standard approach that uses the lowest value that causes a toxicologic response in any system of the animal a more appropriate, conservative estimate?

Fairbrother, A. [Ecological Planning and Toxicology, Inc., Corvallis, OR (United States); Berg, M. van den [Univ. of Utrecht (Netherlands). Research Inst. of Toxicology

1995-12-31

71

Optimal techniques for the extrapolation of SU2 violating ?nucleon amplitudes  

International Nuclear Information System (INIS)

The letter presents some results obtained applying optimal techniques for analytic extrapolation to the latest phase-shift analysis. The followed method gives absolute upper bounds on the extrapolation errors and it does not require any strong smoothness assumption in the energy variable. The approach follows closely the method first outlined by Ciulli and Fischer which use ''truncated Carleman'' functions to weight the functions to be extrapolated to points internal to their holomorphy domain

1976-03-20

72

Fuzzy Model Comparison to Extrapolate Rainfall Data  

Directory of Open Access Journals (Sweden)

Full Text Available This research presents two fuzzy rule-based models for extrapolating the missing rainfall data records of a station, utilizing as a reference the values from another meteorological station located in an adjacent area. The first one is constructed based on the least squares algorithm and the second one using ANFIS method. Three stations were used in this research, all located in Northern Greece. The values of Thessaloniki station were used as fuzzy premises and the values of Sindos and Kria Vrisi were used as fuzzy responses. The model performance was measured by testing several types and numbers of membership functions. Both models are compared with the classical method of linear regression. The comparison between the classical and fuzzy logic method, shows that the second one performs better in recovering the missing rainfall values. It was also found that a fuzzy rule based system, trained with the least squares algorithm, with two fully overlapping fuzzy numbers, is identical to the linear regression method.

C. Tzimopoulos

2008-01-01

73

Extrapolations of nuclear binding energies from new linear mass relations  

DEFF Research Database (Denmark)

We present a method to extrapolate nuclear binding energies from known values for neighboring nuclei. We select four specific mass relations constructed to eliminate smooth variation of the binding energy as function nucleon numbers. The fast odd-even variations are avoided by comparing nuclei with same parity. The mass relations are first tested and shown to either be rather accurately obeyed or revealing signatures of quickly varying structures. Extrapolations are initially made for a nucleus by applying each of these relations. Very reliable estimates are then produced either by an average or by choosing the extrapolation where the smoothest structures enter. Corresponding mass relations for Qα values are used to study the general structure of superheavy elements. A minor neutron shell at N=152 is seen, but no sign of other shell structures are apparent in the superheavy region. Accuracies are typically substantially better than 0.5 MeV.

Hove, D.; Jensen, A. S.

2013-01-01

74

Design and building of an extrapolation ionization chamber for beta dosimetry  

International Nuclear Information System (INIS)

An extrapolation chamber was designed and built to be used in beta dosimetry. The basic characteristics of an extrapolation chamber are discussed, together with fundamental principle of the dosimetric method used. Details of the chamber's design and properties of materials employed are presented. A full evaluation of extrapolation chamber under irradiation from two 90Sr + 90Y beta sources is done. The geometric parameters of the chamber, leakage current and ion collection efficiency are determined. (Author)

1985-01-01

75

Extrapolation Algorithms for Infrared Divergent Integrals  

CERN Document Server

This paper describes applications of extrapolation for the computation of coefficients in an expansion of infrared divergent integrals. An extrapolation procedure is performed with respect to a parameter introduced by dimensional regularization. While this treats typical IR singularities at the boundaries of the integration domain, special care needs to be taken in cases where the integrand is singular in the interior of the domain as well as on the boundaries. A double extrapolation is devised for a class of massless vertex integrals. Quadruple precision results are presented, demonstrating high accuracy. The computations are supported by the use of general adaptive integration programs from the QUADPACK package, in iterated integrations with highly singular integrand functions.

de Doncker, Elise; Hamaguchi, Nobuyuki; Ishikawa, Tadashi; Kurihara, Yoshimasa; Ljucovic, Marko; Shimizu, Yoshimitsu; Yuasa, Fukuko

2011-01-01

76

Methodology for extrapolation of rock mass deformability parameters in tunneling  

Directory of Open Access Journals (Sweden)

Full Text Available This article proposes one approach for extrapolation of necessary parameters for numerical analyses in tunnelling. The approach is named as an empirical - statical - dynamical method for extrapolation. The proposed methodology is based on combination of empirical classification rock mass methods, geophysical measurements and direct dilatometer deformability testing on a field. The analyses are prepared for purposes of investigation and design for several tunnels in Republic of Macedonia. One example for dividing of tunnel length in quasi-homogenous zones, as a basis for forming of geotechnical and numerical model that can be a basis for interaction analyses of rock - structures system and stress-strain behaviour of rock massif, is also given. The several original regressive models between rock mass quality, deformability and velocity of longitudinal seismic waves are shown.

Zafirovski Zlatko

2012-01-01

77

Cosmogony as an extrapolation of magnetospheric research  

International Nuclear Information System (INIS)

A theory of the origin and evolution of the Solar System (Alfven and Arrhenius, 1975: 1976) which considered electromagnetic forces and plasma effects is revised in the light of new information supplied by space research. In situ measurements in the magnetospheres and solar wind have changed our views of basic properties of cosmic plasmas. These results can be extrapolated both outwards in space, to interstellar clouds, backwards in time, to the formation of the solar system. The first extrapolation leads to a revision of some cloud properties which are essential for the early phases in the formation of stars and solar nebule. The latter extrapolation makes possible to approach the cosmogonic processes by extrapolation of (rather) well-known magnetospheric phenomena. Pioneer-Voyager observations of the Saturnian rings indicate that essential parts of their structure are fossils from cosmogonic times. By using detailed information from these space missions, it seems possible to reconstruct certain events 4-5 billion years ago with an accuracy of a few percent. This will cause a change in our views of the evolution of the solar system.(author)

1984-01-01

78

COMPUTERIZED EXTRAPOLATION OF HYDROLYSIS RATE DATA  

Science.gov (United States)

The program RATE was developed to aid in the extrapolation and interpretation of hydrolysis rate data to a format that is useful for environmental risk assessment. ydrolysis data typically are reported in the literature as pseudo-first-order rate constants at the temperature and ...

79

EXTRAPOLATING BRAIN DEVELOPMENT FROM EXPERIMENTAL SPECIES TO HUMANS  

Digital Repository Infrastructure Vision for European Research (DRIVER)

To better understand the neurotoxic effects of diverse hazards on the developing human nervous system, researchers and clinicians rely on data collected from a number of model species that develop and mature at varying rates. We review the methods commonly used to extrapolate the timing of brain development from experimental mammalian species to humans, including morphological comparisons, “rules of thumb” and “event-based” analyses. Most are unavoidably limited in range or detail, ma...

Clancy, Barbara; Finlay, Barbara L.; Darlington, Richard B.; Anand, Kjs

2007-01-01

80

APPLICATION OF SECOND KIND MODEL OF AUTOREGRESSION FOR EXTRAPOLATION ECONOMIC TIME SEQUENCE  

Digital Repository Infrastructure Vision for European Research (DRIVER)

 For extrapolation of economic time sequence we can use the method of autoregression. Originally given method of autoregression is used for prediction of the time series values. We must know: the first few points of sequence and time interval.

2012-01-01

 
 
 
 
81

Evaluation of uncertainty in vertical extrapolation of wind speeds and its implications  

Energy Technology Data Exchange (ETDEWEB)

This paper reported on a study that investigated the influence that topography, surface roughness and atmospheric stability have on wind speed vertical extrapolation and the financial impact throughout the service life of a wind power project. The wind resource should be assessed at hub height in order to calculate the energy yield of a wind turbine and the noise propagation or to determine the structural integrity of a wind tower. The accuracy of the hub height wind speed estimate depends on how well the vertical extrapolation has been done. In this study, directionally, monthly and hourly computed wind shear coefficients were used to extrapolate the measured wind speeds to hub height in order to compare extrapolated and measured wind speed values under different conditions. Boundary layer equations were used to evaluate the atmospheric stability. Wind speeds were extrapolated using the appropriate stability correction function and were verified against measured wind speeds. Different methods to define the stability classes were compared with the measured data. Several WAsP simulations were run with measured and extrapolated wind series in order to evaluate the influence of vertical extrapolation on the horizontal distribution of the wind resource. All evaluated extrapolation methods performed well, with uncertainty of up to 3 per cent for studied cases. The uncertainty was lower in less complex conditions and when more measured data was available. Future work will focus on extending validation of the extrapolation methods using other tall tower data in terrain of varying complexity, as well as further investigating the effects of stability on extrapolation. 8 refs., 2 tabs., 10 figs.

Dimitrijevic, M.; Zaganescu, C.; Dokouzian, S. [Helimax Energy Inc., Montreal, PQ (Canada)

2008-07-01

82

Scintillation Extrapolation Dosimetry of Small Beta-Emitting Sources  

International Nuclear Information System (INIS)

A technique, is described which may be utilized for obtaining values of absorbed dose to tissue-equivalent volumes approaching the volume of individual tissue cells. The method incorporates a series of scintillators (anthracene or Ne-102-A plastic) with dimensions ranging from Il-mm diam. x 0.5 - mm thick to 1- mm diam. x 0.032-mm thick mounted on lucite light pipes. Pulse-height spectra are obtained using each scintillation assembly with absorber thicknesses from zero to several hundred mg cm-2 . These are converted to energy spectra using a computer programme to apply appropriate corrections, and the absorbed dose is calculated. Individual dose measurements are then assembled into extrapolation curves which relate dose to tissue volumes at specified absorber thicknesses. This technique is useful for measurements with sources of activity in the range of 0.05 to 500 ?Ci, which is below the range for which an ionization extrapolation chamber can be used. A comparison is made between the anthracene and plastic scintillation assemblies, and the corrections necessary to convert pulse-height data to absorbed dose are discussed. The advantages and difficulties of this method are evaluated and compared with similar measurements using an air ionization extrapolation chamber of the Loevinger design. (author)

1967-03-01

83

Extrapolating spatial layout in scene representations.  

Science.gov (United States)

Can the visual system extrapolate spatial layout of a scene to new viewpoints after a single view? In the present study, we examined this question by investigating the priming of spatial layout across depth rotations of the same scene (Sanocki & Epstein, 1997). Participants had to indicate which of two dots superimposed on objects in the target scene appeared closer to them in space. There was as much priming from a prime with a viewpoint that was 10° different from the test image as from a prime that was identical to the target; however, there was no reliable priming from larger differences in viewpoint. These results suggest that a scene's spatial layout can be extrapolated, but only to a limited extent. PMID:21156866

Castelhano, Monica S; Pollatsek, Alexander

2010-12-01

84

Chiral extrapolations for nucleon electric charge radii  

CERN Document Server

Lattice simulations for the electromagnetic form factors of the nucleon yield insights into the internal structure of hadrons. The logarithmic divergence of the charge radius in the chiral limit poses an interesting challenge in achieving reliable predictions from finite-volume lattice simulations. Recent results near the physical pion mass are examined in order to confront the issue of how the chiral regime is approached. The electric charge radius of the nucleon presents a forum for achieving consistent finite-volume corrections. Newly-developed techniques within the framework of chiral effective field theory are used to achieve a robust extrapolation of the electric charge radius to the physical pion mass, and to infinite volume. The chiral extrapolations exhibit considerable finite-volume dependence; lattice box sizes of L > 7 fm are required in order to achieve a direct lattice simulation result within 2% of the infinite-volume value at the physical point. Predictions of the volume-dependence are provide...

Hall, J M M; Young, R D

2013-01-01

85

Extrapolation of toxic indices among test objects  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Oligochaeta Tubifex tubifex, fish fathead minnow (Pimephales promelas), hepatocytes isolated from rat liver and ciliated protozoan are absolutely different organisms and yet their acute toxicity indices correlate. Correlation equations for special effects were developed for a large heterogeneous series of compounds (QSAR, quantitative structure-activity relationships). Knowing those correlation equations and their statistic evaluation, one can extrapolate the toxic indices. The reason is that...

Tichy?, Milon?; Rucki, Maria?n; Roth, Zdene?k; Hanzli?kova?, Iveta; Vlkova?, Alena; Tumova?, Jana; Uzlova?, Ru?t

2010-01-01

86

National pattern for the realization of the unit of the dose speed absorbed in air for beta radiation. (Method: Ionometer, cavity of Bragg-Gray implemented in an extrapolation chamber with electrodes of variable separation, exposed to a field of beta radiation of 90Sr/90Y)  

International Nuclear Information System (INIS)

From the year of 1987 the Department of Metrology of the ININ, in their Secondary Laboratory of Calibration Dosimetric, has a patron group of sources of radiation beta and an extrapolation chamber of electrodes of variable separation.Their objective is to carry out of the unit of the dose speed absorbed in air for radiation beta. It uses the ionometric method, cavity Bragg-Gray in the extrapolation chamber with which it counts. The services that offers are: i) it Calibration : Radioactive Fuentes of radiation beta, isotopes: 90Sr/90Y; Ophthalmic applicators 90Sr/90Y; Instruments for detection of beta radiation with to the radiological protection: Ionization chambers, Geiger-Muller, etc.; Personal Dosemeters. ii) Irradiation with beta radiation of materials to the investigation. (Author)

2001-01-01

87

Effective Orthorhombic Anisotropic Models for Wave field Extrapolation  

Wavefield extrapolation in orthorhombic anisotropic media incorporates complicated but realistic models, to reproduce wave propagation phenomena in the Earth\\'s subsurface. Compared with the representations used for simpler symmetries, such as transversely isotropic or isotropic, orthorhombic models require an extended and more elaborated formulation that also involves more expensive computational processes. The acoustic assumption yields more efficient description of the orthorhombic wave equation that also provides a simplified representation for the orthorhombic dispersion relation. However, such representation is hampered by the sixth-order nature of the acoustic wave equation, as it also encompasses the contribution of shear waves. To reduce the computational cost of wavefield extrapolation in such media, I generate effective isotropic inhomogeneous models that are capable of reproducing the first-arrival kinematic aspects of the orthorhombic wavefield. First, in order to compute traveltimes in vertical orthorhombic media, I develop a stable, efficient and accurate algorithm based on the fast marching method. The derived orthorhombic acoustic dispersion relation, unlike the isotropic or transversely isotropic one, is represented by a sixth order polynomial equation that includes the fastest solution corresponding to outgoing P-waves in acoustic media. The effective velocity models are then computed by evaluating the traveltime gradients of the orthorhombic traveltime solution, which is done by explicitly solving the isotropic eikonal equation for the corresponding inhomogeneous isotropic velocity field. The inverted effective velocity fields are source dependent and produce equivalent first-arrival kinematic descriptions of wave propagation in orthorhombic media. I extrapolate wavefields in these isotropic effective velocity models using the more efficient isotropic operator, and the results compare well, especially kinematically, with those obtained from the more expensive anisotropic extrapolator.

Ibanez Jacome, Wilson

2013-05-01

88

Monitoring corrosion and corrosion control of iron in HCl by non-ionic surfactants of the TRITON-X series - Part I. Tafel polarisation, ICP-AES and EFM studies  

Energy Technology Data Exchange (ETDEWEB)

The corrosion inhibition characteristics of non-ionic surfactants of the TRITON-X series, known as TRITON-X-100 (TX-100), TRITON-X-165 (TX-165) and TRITON-X-305 (TX-305), on iron in 1.0 M HCl solution were studied. Measurements were conducted in 1.0 M HCl solutions without and with various concentrations of the three selected surfactants using chemical (ICP-AES method of analysis of dissolved cations) and electrochemical (Tafel polarisation and EFM) techniques at 25 deg. C. These measurements were complemented with SEM and EDX examinations of the electrode surface. Polarisation data showed that the non-ionic surfactants used in this study acted as mixed-type inhibitors with cathodic predominance. The protection efficiency increased with increase in surfactant concentration. Maximum protection efficiency of the surfactant was observed at concentrations around its CMC. From their molecular structure, these surfactants may adsorb on the metal surface through two lone pairs of electrons on the oxygen atoms of the hydrophilic head group.

Amin, Mohammed A. [Materials and Corrosion Lab (MCL), Department of Chemistry, Faculty of Science, Taif University, 888 Haweiah, Taif, KSA (Egypt); Chemistry Department, Faculty of Science, Ain Shams University, Abbassia, Cairo (Egypt)], E-mail: maaismail@yahoo.com; Khaled, K.F. [Materials and Corrosion Lab (MCL), Department of Chemistry, Faculty of Science, Taif University, 888 Haweiah, Taif, KSA (Egypt); Electrochemistry Research Laboratory, Chemistry Department, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt)

2010-05-15

89

Monitoring corrosion and corrosion control of iron in HCl by non-ionic surfactants of the TRITON-X series - Part I. Tafel polarisation, ICP-AES and EFM studies  

International Nuclear Information System (INIS)

The corrosion inhibition characteristics of non-ionic surfactants of the TRITON-X series, known as TRITON-X-100 (TX-100), TRITON-X-165 (TX-165) and TRITON-X-305 (TX-305), on iron in 1.0 M HCl solution were studied. Measurements were conducted in 1.0 M HCl solutions without and with various concentrations of the three selected surfactants using chemical (ICP-AES method of analysis of dissolved cations) and electrochemical (Tafel polarisation and EFM) techniques at 25 deg. C. These measurements were complemented with SEM and EDX examinations of the electrode surface. Polarisation data showed that the non-ionic surfactants used in this study acted as mixed-type inhibitors with cathodic predominance. The protection efficiency increased with increase in surfactant concentration. Maximum protection efficiency of the surfactant was observed at concentrations around its CMC. From their molecular structure, these surfactants may adsorb on the metal surface through two lone pairs of electrons on the oxygen atoms of the hydrophilic head group.

2010-05-01

90

Some remarks on extrapolation with "flat" weights  

CERN Document Server

We prove an extrapolation result for general operators under some weak assumptions on the boundedness of the operator. In particular, we show that if the operator is weakly bounded on some L^{p_{0}}(w), for all "flat" weights, w in A_{p_{0}}, 1 < p_{0} <\\infty, then for p in some small neighborhood around p_{0}, and all "flat" A_{p} weights, w, the operator is weakly bounded on L^{p}(w), and as a result we get strong type estimates for the operator.

Boros, Nicholas; Volberg, Alexander

2012-01-01

91

Wildlife toxicity extrapolations: NOAEL versus LOAEL  

Energy Technology Data Exchange (ETDEWEB)

Ecotoxicological assessments must rely on the extrapolation of toxicity data from a few indicator species to many species of concern. Data are available from laboratory studies (e.g., quail, mallards, rainbow trout, fathead minnow) and some planned or serendipitous field studies of a broader, but by no means comprehensive, suite of species. Yet all ecological risk assessments begin with an estimate of risk based on information gleaned from the literature. One is then confronted with the necessity of extrapolating toxicity information from a limited number of indicator species to all organisms of interest. This is a particularly acute problem when trying to estimate hazards to wildlife in terrestrial systems as there is an extreme paucity of data for most chemicals in all but a handful of species. This section continues the debate by six panelists of the ``correct`` approach for determining wildlife toxicity thresholds by debating which toxicity value should be used for setting threshold criteria. Should the lowest observable effect level (LOAEL) be used or is it more appropriate to use the no observable effect level (NOAEL)? What are the short-comings of using either of these point estimates? Should a ``benchmark`` approach, similar to that proposed for human health risk assessments, be used instead, where an EC{sub 5} or EC{sub 10} and associated confidence limits are determined and then divided by a safety factor? How should knowledge of the slope of the dose-response curve be incorporated into determination of toxicity threshold values?

Fairbrother, A. [Ecological Planning and Toxicology, Inc., Corvallis, OR (United States); Berg, M. van den [Univ. of Utrecht (Netherlands). Research Inst. of Toxicology

1995-12-31

92

Extrapolation models: Absolute and relative risk  

International Nuclear Information System (INIS)

For lifetime experiences concerning the radiation-induced frequency of cancer, there are only a few data available form any of the larger epidemiological studies. Appropriate models must therefore be developed to extrapolate the limited period of life of those irradiated persons that were examined in these studies. Basically, two models may be differentiated for defining the radiation risk after a certain length of study and for extrapolating the risk for the irradiated persons over the actual length of the study. The absolute risk model is based on the assumption that radiation-induced cancer cases occur on a constant level or reach a maximum after a certain latency period, in addition to the spontaneously occurring cancer cases. For the relative risk model it is assumend that radiation-induced cancer increases proportionally to the spontaneous cases. The doubling dose, i.e. the dose which doubles the spontaneous risk, is a particular form of the relative risk and is used specifically for genetic radiation effect. From recent data is more and more apparent that epidemiological findings are better described by a relative rather than an absolute risk model. In consequence of a relative risk projection, the values for the assessed radiation risk are expected to be higher. (orig.)

1991-11-01

93

Dioxin equivalency: Challenge to dose extrapolation  

Energy Technology Data Exchange (ETDEWEB)

Extensive research has shown that all biological effects of dioxin-like agents are mediated via a single biochemical target, the Ah receptor (AhR), and that the relative biologic potencies of such agents in any given system, coupled with their exposure levels, may be described in terms of toxic equivalents (TEQ). It has also shown that the TEQ sources include not only chlorinated species such as the dioxins (PCDDs), PCDFs, and coplanar PCBs, but also non-chlorinated substances such as the PAHs of wood smoke, the AhR agonists of cooked meat, and the indolocarbazol (ICZ) derived from cruciferous vegetables. Humans have probably had elevated exposures to these non-chlorinated TEQ sources ever since the discoveries of fire, cooking, and the culinary use of Brassica spp. Recent assays of CYP1A2 induction show that these ``natural`` or ``traditional`` AhR agonists are contributing 50--100 times as much to average human TEQ exposures as do the chlorinated xenobiotics. Currently, the safe doses of the xenobiotic TEQ sources are estimated from their NOAELs and large extrapolation factors, derived from arbitrary mathematical models, whereas the NOAELs themselves are regarded as the safe doses for the TEQs of traditional dietary components. Available scientific data can neither support nor refute either approach to assessing the health risk of an individual chemical substance. However, if two substances be toxicologically equivalent, then their TEQ-adjusted health risks must also be equivalent, and the same dose extrapolation procedure should be used for both.

Brown, J.F. Jr.; Silkworth, J.B. [GE Corporate Research and Development, Schenectady, NY (United States)

1995-12-31

94

Chiral and continuum extrapolation of partially-quenched hadron masses  

International Nuclear Information System (INIS)

Using the finite-range regularization (FRR) of chiral effective field theory, the chiral extrapolation formula for the vector meson mass is derived for the case of partially-quenched QCD. We re-analyze the dynamical fermion QCD data for the vector meson mass from the CP-PACS collaboration. A global fit, including finite lattice spacing effects, of all 16 of their ensembles is performed. We study the FRR method together with a naive polynomial approach and find excellent agreement (?1%) with the experimental value of M_? from the former approach. These results are extended to the case of the nucleon mass

2005-07-25

95

In situ LTE exposure of the general public: Characterization and extrapolation.  

Science.gov (United States)

In situ radiofrequency (RF) exposure of the different RF sources is characterized in Reading, United Kingdom, and an extrapolation method to estimate worst-case long-term evolution (LTE) exposure is proposed. All electric field levels satisfy the International Commission on Non-Ionizing Radiation Protection (ICNIRP) reference levels with a maximal total electric field value of 4.5 V/m. The total values are dominated by frequency modulation (FM). Exposure levels for LTE of 0.2 V/m on average and 0.5 V/m maximally are obtained. Contributions of LTE to the total exposure are limited to 0.4% on average. Exposure ratios from 0.8% (LTE) to 12.5% (FM) are obtained. An extrapolation method is proposed and validated to assess the worst-case LTE exposure. For this method, the reference signal (RS) and secondary synchronization signal (S-SYNC) are measured and extrapolated to the worst-case value using an extrapolation factor. The influence of the traffic load and output power of the base station on in situ RS and S-SYNC signals are lower than 1 dB for all power and traffic load settings, showing that these signals can be used for the extrapolation method. The maximal extrapolated field value for LTE exposure equals 1.9 V/m, which is 32 times below the ICNIRP reference levels for electric fields. PMID:22271226

Joseph, Wout; Verloock, Leen; Goeminne, Francis; Vermeeren, Günter; Martens, Luc

2012-09-01

96

Extrapolation of neutron-rich isotope cross-sections from projectile fragmentation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Using the measured fragmentation cross sections produced from the 48Ca and 64Ni beams at 140 MeV per nucleon on 9Be and 181Ta targets, we find that the cross sections of unmeasured neutron rich nuclei can be extrapolated using a systematic trend involving the average binding energy. The extrapolated cross-sections will be very useful in planning experiments with neutron rich isotopes produced from projectile fragmentation. The proposed method is general and could be applied ...

Mocko, M.; Tsang, M. B.; Sun, Z. Y.; Andronenko, L.; Andronenko, M.; Delaunay, F.; Famiano, M.; Friedman, W. A.; Henzl, V.; Henzlova, D.; Hui, H.; Liu, X. D.; Lukyanov, S.; Lynch, W. G.; Rogers, A. M.

2007-01-01

97

Edge database analysis for extrapolation to ITER  

International Nuclear Information System (INIS)

An edge database has been archived to facilitate cross-machine comparisons of SOL and edge pedestal characteristics, and to enable comparison with theoretical models with an aim to extrapolate to ITER. The SOL decay lengths of power, density and temperature become broader for increasing density and q_9_5. The power decay length is predicted to be 1.4-3.5 cm (L-mode) and 1.4-2.7 cm (H-mode) at the midplane in ITER. Analysis of Type I ELMs suggests that each giant ELM on ITER would exceed the ablation threshold of the divertor plates. Theoretical models are proposed for the H-mode transition, for Type I and Type III ELMs and are compared with the edge pedestal database. (author)

2001-05-01

98

Extrapolation of toxic indices among test objects.  

Science.gov (United States)

Oligochaeta Tubifex tubifex, fish fathead minnow (Pimephales promelas), hepatocytes isolated from rat liver and ciliated protozoan are absolutely different organisms and yet their acute toxicity indices correlate. Correlation equations for special effects were developed for a large heterogeneous series of compounds (QSAR, quantitative structure-activity relationships). Knowing those correlation equations and their statistic evaluation, one can extrapolate the toxic indices. The reason is that a common physicochemical property governs the biological effect, namely the partition coefficient between two unmissible phases, simulated generally by n-octanol and water. This may mean that the transport of chemicals towards a target is responsible for the magnitude of the effect, rather than reactivity, as one would assume suppose. PMID:21331180

Tichý, Milo?; Rucki, Marián; Roth, Zden?k; Hanzlíková, Iveta; Vlková, Alena; Tumová, Jana; Uzlová, Rút

2010-12-01

99

Computerized extrapolation of hydrolysis rate data  

Energy Technology Data Exchange (ETDEWEB)

The program RATE was developed to aid in the extrapolation and interpretation of hydrolysis rate data to a format that is useful for environmental risk assessment. Hydrolysis data typically are reported in the literature as pseudo-first-order rate constants at the temperature and pH of the reaction medium used to obtain the kinetics information. The utility of RATE lies in its ability to estimate first-order rate constants at other values of temperature and pH and to convert pseudo-first-order rate constants to second-order rate constants. RATE also will calculate the half-life for the overall reaction, including neutral-, base-, and acid-mediated hydrolysis, at any selected temperature and pH. RATE, programmed in FORTRAN, is used to systematically analyze data for entry in FATE, a comprehensive environmental fate constants information system database.

Hamrick, K.J.; Kollig, H.P.; Bartell, B.A.

1992-01-01

100

Edge database analysis for extrapolation to ITER  

International Nuclear Information System (INIS)

An edge database has been archived to facilitate cross-machine comparisons of SOL and edge pedestal characteristics, and to enable comparison with theoretical models with an aim to extrapolate to ITER. The SOL decay lengths of power, density and temperature become broader for increasing density and q_9_5 . The power decay length is predicted to be 1.4-3.5 cm (L-mode) and 1.4-2.7 cm (H-mode) at the midplane in ITER. Analysis of Type I ELMs suggests that each giant ELM on ITER would exceed the ablation threshold of the divertor plates. Theoretical models are proposed for the H-mode transition, for Type I and Type III ELMs and are compared with the edge pedestal database. (author)

1999-12-01

 
 
 
 
101

The extrapolation of creep rupture data by PD6605 - An independent case study  

Energy Technology Data Exchange (ETDEWEB)

The worked example presented in BSI document PD6605-1:1998, to illustrate the selection, validation and extrapolation of a creep rupture model using statistical analysis, was independently examined. Alternative rupture models were formulated and analysed by the same statistical methods, and were shown to represent the test data more accurately than the original model. Median rupture lives extrapolated from the original and alternative models were found to diverge widely under some conditions of practical interest. The tests prescribed in PD6605 and employed to validate the original model were applied to the better of the alternative models. But the tests were unable to discriminate between the two, demonstrating that these tests fail to ensure reliability in extrapolation. The difficulties of determining when a model is sufficiently reliable for use in extrapolation are discussed and some proposals are made.

Bolton, J., E-mail: john.bolton@uwclub.net [65 Fisher Avenue, Rugby, Warks CV22 5HW (United Kingdom)

2011-04-15

102

Extrapolation from experimental systems to man. A review of the problems and the possibilities  

International Nuclear Information System (INIS)

Various species of experimental animals, but in particular the mouse, have proved to be good model systems for predicting qualitatively the human response to irradiation. While extrapolations of genetic risks from mice to humans have a long history and a record of considerable success, there have been few attempts to extrapolate quantitatively the findings for somatic effects. An ability to extrapolate risks from exposures to various carcinogenic agents from experimental animal systems and from in vitro systems is an urgent need, and radiation studies provide the model for the development of suitable methods of extrapolation. Accurate measurement of dose, a remarkable store of knowledge about radiobiological responses at the molecular, cellular, and whole-organism level, and the body of data on radiation effects in both man and experimental animals make radiation studies the sensible choice of a model for the development of methods of extrapolation. The principles derived from such studies will make the much more difficult task of extrapolating risks from exposures to chemical carcinogens an easier one

1980-03-01

103

Bayesian contour extrapolation: geometric determinants of good continuation.  

Science.gov (United States)

We investigated whether observers use rate of change of curvature in visually extrapolating contour shape. Arcs of Euler spirals with positive or negative rate of change of curvature gamma (hence linearly increasing or decreasing curvature) disappeared behind the straight-edge of a half-disk occluder. Observers adjusted the position and the orientation of a line probe around the curved portion of the occluder to optimize the percept of extrapolation. These paired measurements were obtained at multiple distances from the point of occlusion in order to map out the extended shape of visually extrapolated contours. An Euler-spiral model was fit to the extrapolation data corresponding to each inducing contour. Maximum-likelihood estimates of extrapolation rate of change of curvature gamma/\\ were consistently found to be negative, indicating that visually extrapolated contours are characterized by decaying curvature, irrespective of whether inducer curvature is increasing or decreasing as it approaches the occluder. Moreover, extrapolation gamma/\\ was found to exhibit no systematic dependence on inducer gamma. The results indicate that the visual system does not extrapolate rate of change of contour curvature. They support a Bayesian model of contour extrapolation, in which the decay in extrapolation curvature derives from an interaction between a likelihood bias to continue estimated contour curvature, and a prior bias to minimize contour curvature. Rate of change of curvature does not play a role. PMID:17292938

Singh, Manish; Fulvio, Jacqueline M

2007-03-01

104

Magnetic Field Extrapolations into the Corona: Success and Future Improvements  

Science.gov (United States)

The solar atmosphere being magnetic in nature, the understanding of the structure and evolution of the magnetic field in different regions of the solar atmosphere has been an important task over the past decades. This task has been made complicated by the difficulties to measure the magnetic field in the corona, while it is currently known with a good accuracy in the photosphere and/or chromosphere. Thus, to determine the coronal magnetic field, a mathematical method has been developed based on the observed magnetic field. This is the so-called magnetic field extrapolation technique. This technique relies on two crucial points: i) the physical assumption leading to the system of differential equations to be solved, ii) the choice and quality of the associated boundary conditions. In this review, I summarise the physical assumptions currently in use and the findings at different scales in the solar atmosphere. I concentrate the discussion on the extrapolation techniques applied to solar magnetic data and the comparison with observations in a broad range of wavelengths (from hard X-rays to radio emission).

Régnier, S.

2013-12-01

105

Identification of Contemporaneous Loading for Primary Extrapolated Extreme Loads in Wind Turbines  

DEFF Research Database (Denmark)

This paper describes the statistical identification of component loading occurring at the same instant as an extrapolated primary 50 year extreme load. As it is not feasible to simulate a full lifetime of fluctuating wind turbine loads to determine the largest extreme value, extrapolation to a 50 year or other desired long-term return period is performed based on limited simulation data. For specific wind turbine component design, it is required to identify other simultaneously applied loading corresponding to this long-term extrapolated load level. This identification is performed using statistical methods, since an appropriate loads simulation time series directly giving loads at the extrapolated load level is unavailable. The statistical behavior of each contemporaneous load in the simulation time series that was used to determine the extrapolated load is illustrated by the histogram. Since this histogram is in general skewed, the mean value of the corresponding data may not be an appropriate value for such contemporaneous loads. Instead, in this paper, a value corresponding to the mode of the estimated probability distribution function of the contemporaneous load is used. The robustness of ascertaining this most probable contemporaneous load is also investigated. The application of this process of identification of contemporaneous extreme loads is also applied to cases wherein the extrapolated load is a resultant load value, for which a suitable vector direction for the extreme resultant load is chosen. Copyright © 2008 John Wiley & Sons, Ltd.

Natarajan, Anand; Holley, William E.

2008-01-01

106

Extrapolation-based boundary element quadrature  

Energy Technology Data Exchange (ETDEWEB)

The classical Euler Maclaurin summation formula expresses the discretization error made by the trapezoidal rule approximation to a finite integral as an asymptotic expansion in the mesh ratio. As such, it plays a significant role in the theory of numerical quadrature. In particular, it forms the basis for Richardson's deferred approach to the limit, also known as Romberg integration and as quadrature by extrapolation. In this review, we draw attention to some more recent theory, based on the Euler Maclaurin summation formula (or expansion). During the past 25 years, this theory has undergone significant development. Briefly, the expansion has been systematized to embrace all quadrature rules. It has been generalized to the N-dimensional cube and to the N-dimensional simplex. Moreover, a significant generalization has been made to cover functions having algebraic and logarithmic singularities at vertices. In this article we discuss some of these developments in the context of their possible use to analyze finite elements. In general, no proofs are provided, but references are given. 33 refs.

Lyness, J.N.

1990-01-01

107

Hard hadronic collisions: extrapolation of standard effects  

International Nuclear Information System (INIS)

We study hard hadronic collisions for the proton-proton (pp) and the proton-antiproton (p anti p) option in the CERN LEP tunnel. Based on our current knowledge of hard collisions at the present CERN p anti p Collider, and with the help of quantum chromodynamics (QCD), we extrapolate to the next generation of hadron colliders with a centre-of-mass energy E/sub cm/ = 10 to 20 TeV. We estimate various signatures, trigger rates, event topologies, and associated distributions for a variety of old and new physical processes, involving prompt photons, leptons, jets, W+- and Z bosons in the final state. We also calculate the maximum fermion and boson masses accessible at the LEP Hadron Collider. The standard QCD and electroweak processes studied here, being the main body of standard hard collisions, quantify the challenge of extracting new physics with hadron colliders. We hope that our estimates will provide a useful profile of the final states, and that our experimental physics colleagues will find this of use in the design of their detectors. 84 references

1984-03-22

108

Proportional extrapolation techniques for determining stress intensity factors  

International Nuclear Information System (INIS)

Proportional extrapolation techniques are proposed to compute simply and accurately the stress intensity factor by use of the boundary element method (BEM). They are based on the procedures that the effects of boundary division near crack tip on stresses and displacements are corrected by comparing with a standard problem and the corrected results are only accurate in the limit as r -> 0 (r = distance from crack tip). Comparisons of a few crack problems are made between results using the proposed techniques and those obtained by previously recommended methods. They are seen to be less sensitive than any other techniques regarding human work and accurate results are obtained even in the case of coarse boundary division. (orig.)

1986-07-01

109

Study of the reaction {pi}{sup -}p {yields} {pi}{sup -}{pi}{sup 0} p at 2.77 GeV/c for low momentum transfer of the proton. Application to the Chew-Low extrapolation method for the {pi}{sup -}{pi}{sup 0} elastic scattering; Etude de la reaction {pi}{sup -}p {yields} {pi}{sup -}{pi}{sup 0} p a 2.77 GeV/c pour de faibles impulsions du proton diffuse. Application de la methode d'extrapolation de Chew et Low a la diffusion elastiques {pi}{sup -}{pi}{sup 0}  

Energy Technology Data Exchange (ETDEWEB)

Study of the reaction {pi}{sup -}p {yields} {pi}{sup -}{pi}{sup 0} p at 2.77 GeV/c carried out in the CERN 2 meter large liquid hydrogen bubble chamber at the proton synchrotron, shows that 70 per cent of this reaction goes through {pi}{sup -}p {yields} {rho}{sup -}p channel. The high statistics allow us to specify the mass and the width of the {rho}{sup -} resonance. In other hand, if the {rho}{sup -} production parameters are independent of the {rho}{sup -} width, it is not the same case for the decay parameters. In the second part, the Chew-Low extrapolation method allows us to determine the {pi}{sup -}{pi}{sup 0} elastic cross section to the pole, and the phase shifts of the P waves in the isospin 1 state and S waves in the isospin 2 state. (author) [French] L'etude de la reaction {pi}{sup -}p {yields} {pi}{sup -}{pi}{sup 0} p a 2.77 GeV/c, effectuee a l'aide de la chambre a bulles a hydrogene liquide de 2 metres du CERN, exposee aupres du synchrotron a protons, montre que 70 pour cent de cette reaction passe par la voie {pi}{sup -}p {yields} {rho}{sup -}p. L'abondance de la statistique a permis de preciser la masse et la largeur de la resonance {rho}{sup -}. D'autre part, si les parametres de la production du {rho}{sup -} sont independants de la largeur de la resonance, il n'en est pas de meme des parametres de la desintegration. Dans la deuxieme partie, la methode d'extrapolation de Chew et Low permet de determiner la section efficace de diffusion elastique {pi}{sup -}{pi}{sup 0} au pole, ainsi que les dephasages des ondes P dans l'etat d'isospin 1 et S dans l'etat d'isospin 2. (auteur)

Baton, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1968-05-01

110

Towards a Thomas-Fermi mass formula for extrapolation to the neutron-drip line  

International Nuclear Information System (INIS)

For an analysis of the r-process of stellar nucleosynthesis, binding energies of the unknown nuclei close to the neutron drip line are required. The way to get these energies is to use the nuclear mass formula to extrapolate from the known nuclei to the unknown nuclei close to the neutron-drip line. It is observed that the mass formulas based on existing forms of the droplet model (DM) extrapolate very badly out to the neutron-drip line, but a mass formula based on the Extended Thomas-Fermi (ETF) method with Skyrme-type force extrapolates out to the neutron-drip line almost as well as the Hartree-Fock (HF) method and is computationally much faster than HF method. (M.G.B.)

1986-01-01

111

Wavefront reconstruction over a circular aperture using gradient data extrapolated via the mirror equations.  

Science.gov (United States)

Methods for extrapolating gradient data outside a circular aperture from measurements obtained within a circular aperture are presented. The proposed methods are required to be computationally efficient and to avoid the excitation of additional waffle modes in Fried alignment. It is shown that, using an octagon as an intermediate step from the circle to the square in the extrapolation process, the computations or residual reconstruction error can be reduced. The resulting computational cost is as low as O(N(1/2)), where N is the number of measurement points. The performances of the extrapolation methods are studied in connection with a recently developed O(N) wavefront reconstruction algorithm based on wavelet filter banks [IEEE J. Sel. Top. Signal Process. 2, 781 (2008)] Experiments indicate that, as expected, there is a significant reconstruction error if no extrapolation is used. Further, the proposed extrapolation techniques lead to a reconstruction with data that are marginally different from a pupil masked reconstruction using data from a square aperture. PMID:19593356

Hampton, Peter J; Agathoklis, Pan; Bradley, Colin

2009-07-10

112

Beyond Statistical Extrapolation: Stochastic Rainfall Generators and Extreme Values (Invited)  

Science.gov (United States)

The rainfall series are unfortunately rather short (rarely exceeding a century) and statistical extrapolation have been extensively used to extrapolate the empirical quantiles to return periods larger than their length. Unfortunately, these extrapolations are based on convenient but simplistic mathematical hypothesis (e.g. the renewable model, the Gumbel law) rather than on the precipitation physics. An attractive alternative that is getting more and more attention is to use very long synthetic series generated by stochastic rainfall generators. We first discuss the most important requirements for these generators: to fit all possible behaviour of the probability tails, the possible clustering of extremes and a large variability over a wide range of space time scales. We compare how these features can be satisfied by two distinct types of generators: - an episodic rainfall model SHYPRE, which is rooted to the occurrence of primary and secondary rainfalls, therefore stochastic simulations are then used to reconstruct the high resolution time series of heavy rainfall episodes; - a continuous scaling model MFM, more precisely a multiftractal model based on the idea that rain cascades from larger to smaller structures, therefore involve an infinite hierarchy of rainfalls, whose extreme behavior can be analytically estimated. For both methods, the model parameters are estimated with the help of a statistical analysis of limited length rainfall time series. The model is then used to infer numerically or analytically the quantiles for return periods ranging from 1 to 1000 years and for durations from 1 hour to 72 hours. Based on these quantile estimates, we performed a detailed comparison of SHYPRE and MFM results for 252 French meteorological stations. A particular attention was given to Pyrenees, Rhone Valley, Cevennes and Alps - the four south France areas with rather similar precipitation regimes. For large return periods the empirical quantiles obtained from long hydro-meteorological records are often much more important than those inferred from Gumbel law. It can be shown theoretically that MFM yields a power-law probability of the extremes, often called a ‘fat tail’. The SHYPRE model generally leads to a hyper-exponential asymptotic behavior. The comparison of the quantile estimates has demonstrated that both models yield rather similar results, in particular for the larger return periods (100-1000 years). It is important to mention that the spatial distribution of the rainfall quantiles corresponding to the 252 French meteorological stations exhibit strong space variability for all durations and return periods. We conclude on the consequences of such variability for the return periods of regional floods, in particular flashfloods in south France areas.

Tchiguirinskaia, I.; Arnaud, P.; Schertzer, D. J.; Lavabre, J.

2009-12-01

113

Dose rates from a C-14 source using extrapolation chamber and MC calculations  

International Nuclear Information System (INIS)

The extrapolation chamber technique and the Monte Carlo (MC) calculation technique based on the EGS4 system have been studied for application for determination of dose rates in a low-energy ? radiation field e.g., that from a 14C source. The extrapolation chamber measurement method is the basic method for determination of dose rates in ? radiation fields. Applying a number of correction factors and the stopping power ratio, tissue to air, the measured dose rate in an air volume surrounded by tissue equivalent material is converted into dose to tissue. Various details of the extrapolation chamber measurement method and evaluation procedure have been studied and further developed, and a complete procedure for the experimental determination of dose rates from a14C source is presented. A number of correction factors and other parameters used in the evaluation procedure for the measured data have been obtained by MC calculations. The whole extrapolation chamber measurement procedure was simulated using the MC method. The measured dose rates showed an increasing deviation from the MC calculated dose rates as the absorber thickness increased. This indicates that the EGS4 code may have some limitations for transport of very low-energy electrons. i.e., electrons with estimated energies less than 10 - 20 keV. MC calculations of dose to tissue were performed using two models: a cylindrical tissue phantom and a computer model of the extrapolation chamber. The dose to tissue in the extrapolation chamber model showed an additional buildup dose compared to the dose in the tissue model. (au) 10 tabs., 11 ills., 18 refs

1996-01-01

114

Slow neutron flux extrapolation distances in R-5 and CIRUS reactors  

International Nuclear Information System (INIS)

In order to calculate the core reactivity, fuel channel power outputs and neutron flux levels in the R-5 reactor at Trombay, axial flux extrapolation distances are required. For this, an analysis is carried out considering the reactor core as a two region neutron multiplying system in axial direction. The slow neutron diffusion equations for both the regions are solved analytically by applying suitable boundary conditions. Application of this method for the estimation of top extrapolation distances in CIRUS, has given results which agree well with accepted values for the reactor. (author)

1976-03-01

115

Chiral extrapolation and determination of low-energy constants from lattice data  

Energy Technology Data Exchange (ETDEWEB)

We propose analytic approximations of chiral SU(3) amplitudes for the extrapolation of lattice data to the physical meson masses. The method allows the determination of NNLO low-energy constants in a controllable fashion. We test the approach with recent lattice data for the ratio F{sub K}/F{sub {pi}}of meson decay constants.

Ecker, G., E-mail: gerhard.ecker@univie.ac.a [Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Wien (Austria); Masjuan, P.; Neufeld, H. [Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Wien (Austria)

2010-08-30

116

Quark Mass Dependence of Nucleon Properties and Extrapolation from Lattice QCD  

CERN Document Server

We summarize developments concerning the quark mass dependence of nucleon magnetic moments and the axial-vector coupling constant g_A. The aim is to explore the feasibility of chiral effective field theory methods for the extrapolation of lattice QCD results, from the relatively large quark masses that can be handled in such computations down to the physically relevant range.

Hemmert, T R; Weise, W; Hemmert, Thomas R.; Procura, Massimiliano; Weise, Wolfram

2003-01-01

117

The role of isoelectronic extrapolation of highly ionized atoms in plasma physics  

International Nuclear Information System (INIS)

It is studied the role of the extrapolation of highly ionized atoms through the isoelectronic sequences and it is applied the method for the configurations 2p43s, 3p and 3d in six times ionized phophorus (P VII) and nine times ionized argon (Ar X). (author)

1987-08-17

118

Volatility smile extrapolation with an artificial neural network  

Digital Repository Infrastructure Vision for European Research (DRIVER)

I use a multi-layer feedforward perceptron, with backpropagation learning implemented via stochastic gradient descent, to extrapolate the volatility smile of Euribor derivatives over low-strikes by training the network on parametric prices.

Richter, Mark Michael

2012-01-01

119

Local Forecasting through Extrapolation of GOES Imagery Patterns.  

Science.gov (United States)

An attractive approach to short-range forecasting is to determine cloud motion from a sequence of satellite images and extrapolate the patterns and associated weather into the future. Objective motion vector techniques are available and the forecast proce...

H. S. Muench

1980-01-01

120

Extrapolated ranges of electrons determined from transmission and projected-range straggling curves  

Energy Technology Data Exchange (ETDEWEB)

Extrapolated ranges of electrons R{sub ex,t} and R{sub ex,p} have been determined from transmission and projected-range straggling curves, respectively. Data on the two kinds of curve have been obtained by Monte Carlo calculations for 0.1-50 MeV electrons incident on elemental absorbers of atomic numbers between 4 and 92. The two sets of extrapolated ranges, as well as another set, R{sub ex,q}, determined from charge-deposition curves (Nucl. Instrum. Methods B 119 (4) (1996) 463), have been found practically the same. Appreciable differences of R{sub ex,t} from R{sub ex,p} and R{sub ex,q} have been observed only for electrons of energies below 2 MeV incident on absorbers of the highest atomic numbers. The cause of these differences has been traced to the backscattering of electrons from the incident surface, phenomenon affecting only R{sub ex,t} among the extrapolated ranges determined by the three methods. The fact that the extrapolated range is in most cases independent of the method of determination establishes the usefulness of this quantity. An analytic expression fitted to the Monte Carlo results of R{sub ex,t} is given.

Tabata, Tatsuo E-mail: tttabata@pearl.ocn.ne.jp; Moskvin, Vadim; Andreo, Pedro; Lazurik, Valentin; Rogov, Yuri

2002-06-01

 
 
 
 
121

Extrapolation-based implicit-explicit general linear methods  

Digital Repository Infrastructure Vision for European Research (DRIVER)

For many systems of differential equations modeling problems in science and engineering, there are natural splittings of the right hand side into two parts, one non-stiff or mildly stiff, and the other one stiff. For such systems implicit-explicit (IMEX) integration combines an explicit scheme for the non-stiff part with an implicit scheme for the stiff part. In a recent series of papers two of the authors (Sandu and Zhang) have developed IMEX GLMs, a family of implicit-ex...

Cardone, Angelamaria; Jackiewicz, Zdzislaw; Zhang, Hong; Sandu, Adrian

2013-01-01

122

Extrapolation of K to \\pi\\pi decay amplitude  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We examine the uncertainties involved in the off-mass-shell extrapolation of the $K\\rightarrow \\pi\\pi$ decay amplitude with emphasis on those aspects that have so far been overlooked or ignored. Among them are initial-state interactions, choice of the extrapolated kaon field, and the relation between the asymptotic behavior and the zeros of the decay amplitude. In the inelastic region the phase of the decay amplitude cannot be determined by strong interaction alone and even ...

Suzuki, Mahiko

2001-01-01

123

X-CAPM: An Extrapolative Capital Asset Pricing Model  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Survey evidence suggests that many investors form beliefs about future stock market returns by extrapolating past returns. Such beliefs are hard to reconcile with existing models of the aggregate stock market. We study a consumption-based asset pricing model in which some investors form beliefs about future price changes in the stock market by extrapolating past price changes, while other investors hold fully rational beliefs. We find that the model captures many features of actual prices and...

Barberis, Nicholas; Greenwood, Robin Marc; Jin, Lawrence; Shleifer, Andrei

2013-01-01

124

Role of animal studies in low-dose extrapolation  

International Nuclear Information System (INIS)

Current data indicate that in the case of low-LET radiation linear, extrapolation from data obtained at high doses appears to overestimate the risk at low doses to a varying degree. In the case of high-LET radiation, extrapolation from data obtained at doses as low as 40 rad (0.4 Gy) is inappropriate and likely to result in an underestimate of the risk

1981-04-29

125

Wildlife toxicity extrapolations: Allometry versus physiologically-based toxicokinetics  

Energy Technology Data Exchange (ETDEWEB)

Ecotoxicological assessments must rely on the extrapolation of toxicity data from a few indicator species to many species of concern. Data are available from laboratory studies (e.g., quail, mallards, rainbow trout, fathead minnow) and some planned or serendipitous field studies of a broader, but by no means comprehensive, suite of species. Yet all ecological risk assessments begin with an estimate of risk based on information gleaned from the literature. The authors are then confronted with the necessity of extrapolating toxicity information from a limited number of indicator species to all organisms of interest. This is a particularly acute problem when trying to estimate hazards to wildlife in terrestrial systems as there is an extreme paucity of data for most chemicals in all but a handful of species. The question arises of how interspecific extrapolations should be made. Should extrapolations be limited to animals within the same class, order, family or genus? Alteratively, should extrapolations be made along trophic levels or physiologic similarities rather than by taxonomic classification? In other words, is an avian carnivore more like a mammalian carnivore or an avian granivore in its response to a toxic substance? Can general rules be set or does the type of extrapolation depend upon the class of chemical and its mode of uptake and toxicologic effect?

Fairbrother, A. [Ecological Planning and Toxicology Inc., Corvallis, OR (United States); Berg, M. van den [Univ. of Utrecht (Netherlands). Research Inst. of Toxicology

1995-12-31

126

Seismic tomography with non-uniform ray coverage and autoregressive extrapolation  

Science.gov (United States)

Seismic tomography as used in the laboratory and in the field is strongly affected by limited and non-uniform ray coverage, and this will generally result in ill-posed inverse problems. In this study several regularization methods to improve inversion for non-uniform ray coverage are described. Inversions based on variable damping are tested and compared with inversions using simple damping. A two-stage autoregressive extrapolation technique is then proposed that can be used to extend the observed data and provide better tomographic images. The algorithm is based on the principle that the extrapolated data adds minimal information to the existing data. The first stage of the extrapolation is to find the optimal prediction-error filter (PE filter). The second stage is to use the PE filter to find the values of the missing data. The missing data are estimated to have the same spectrum as the observed data and this is similar to maximizing an entropy criterion. In order to test the method, synthetic and laboratory tomography experiments for rock samples are used in which full ray coverage can be obtained. Autoregressive methods are then used to extrapolate for partial ray coverage and the tomographic results are compared with the full ray coverage case. These tests show that the autoregressive method can extrapolate known data to find missing data as well as provide improved tomographic images. The autoregressive extrapolation is also tolerant to noise. Autoregressive methods may have important applications to tomography experiments in the field where it is often impossible to set up tomography experiments with perfect ray coverage. A synthetic field example using a cross-borehole geometry is performed and shows that autoregressive extrapolation can be applied to a limited ray coverage field geometry for seismic tomography. We finally applied travel-time tomography techniques to observed datasets recorded in the laboratory for rock samples. The results for these experiments show that for laboratory tomographic experiments, simple as well as complicated internal structures can be reconstructed.

Li, Cuiping

127

-Error Estimates of the Extrapolated Crank-Nicolson Discontinuous Galerkin Approximations for Nonlinear Sobolev Equations  

Directory of Open Access Journals (Sweden)

Full Text Available We analyze discontinuous Galerkin methods with penalty terms, namely, symmetric interior penalty Galerkin methods, to solve nonlinear Sobolev equations. We construct finite element spaces on which we develop fully discrete approximations using extrapolated Crank-Nicolson method. We adopt an appropriate elliptic-type projection, which leads to optimal error estimates of discontinuous Galerkin approximations in both spatial direction and temporal direction.

Lee HyunYoung

2010-01-01

128

Extrapolation of small sample Doppler reactivity measurements  

International Nuclear Information System (INIS)

An application of 238U small sample Doppler measurements to the confirmation of LMFBR design calculations is proposed. The method uses the Doppler measurements in conjunction with 238U(n,#betta#) data to predict the radial behavior of the Doppler reactivity C/E, and includes a description of azimuthal variations by using the measured values to normalize a calculated map. The result is a spatial map which can be used, along with data from the SEFOR experiments, to test design level calculations of Doppler reactivity

1982-08-01

129

Convergence and extrapolation studies with the fit 3D code  

International Nuclear Information System (INIS)

The FIT Code, designed to compute ideal MHD equilibria, was tested on six configurations representative of stellarator research. The code was modified in the following points: 1) The previous iteration mehods were extended by a conjugate gradient method capable of varying all three dependent inverse variables r,z, and ? simultaneously. The non-uniqueness of these variables can be eliminated by appropriate coupling of some of the r- and z-coefficients in the Fourier series. The selected configurations are: 1) an axisymmetric Solov'ev equilibrium, where the energy was computed analytically; 2) an axisymmetric high-beta equilibrium, where, owing to the strong axis shift and the simple circular boundary ?? O is necessary to obtain reasonable numerical solutions at all 3) a low aspect ratio (A ? 4) l = 2 configuration, 4) an ATF model; 5) a W VII-AS; and 6) a Heliac. The results obtained with FIT are presented in detail and compared with those of other codes. The accuracy is checked by two scalars, the energy and the mean axis shift. Because of the radial (s) difference approximations, extrapolation in the mesh-size is necessary

1984-09-24

130

Associação de cetamina S(+) e midazolam pelo método convencional de cálculo e pela extrapolação alométrica em bugios-ruivo (Alouatta guariba clamitans): resposta clínica e cardiorrespiratória / S(+) ketamine and midazolam association by the conventional method of calculation and allometric extrapolation in red howler monkeys (Alouatta guariba clamitans): clinical and cardiopulmonary response  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O objetivo deste estudo foi avaliar o protocolo de contenção química com cetamina S(+) e midazolam em bugios-ruivos, comparando o cálculo de doses pelo método convencional e o método de extrapolação alométrica. Foram utilizados 12 macacos bugios (Alouatta guariba clamitans) hígidos, com peso médio d [...] e 4,84±0,97kg, de ambos os sexos. Após jejum alimentar de 12 horas e hídrico de seis horas, realizou-se contenção física manual e aferiram-se os seguintes parâmetros: frequência cardíaca (FC), frequência respiratória (f), tempo de preenchimento capilar (TPC), temperatura retal (TR), pressão arterial sistólica não invasiva (PANI) e valores de hemogasometria arterial. Posteriormente, os animais foram alocados em dois grupos: GC (Grupo Convencional, n=06), os quais receberam cetamina S(+) (5mg kg-1) e midazolam (0,5mg kg-1), pela via intramuscular, com doses calculadas pelo método convencional; e GA (Grupo Alometria, n=06), os quais receberam o mesmo protocolo, pela mesma via, utilizando-se as doses calculadas pelo método de extrapolação alométrica. Os parâmetros descritos foram mensurados novamente nos seguintes momentos: M5, M10, M20 e M30 (cinco, 10, 20 e 30 minutos após a administração dos fármacos, respectivamente). Também foram avaliados: qualidade de miorrelaxamento, reflexo podal e caudal, pinçamento interdigital, tempo para indução de decúbito, tempo hábil de sedação, qualidade de sedação, e tempo e qualidade de recuperação. O GA apresentou menor tempo para indução ao decúbito, maior grau e tempo de sedação, bem como redução significativa da FC e PANI de M5 até M30, quando comparado ao GC. Conclui-se que o grupo no qual o cálculo de dose foi realizado por meio da alometria (GA) apresentou melhor grau de relaxamento muscular e sedação, sem produzir depressão cardiorrespiratória significativa. Abstract in english The aim of this study was to evaluate a protocol of chemical restraint comparing the conventional method of calculation (weight dose) and allometric extrapolation. Twelve healthy red howler monkeys (Alouatta guariba clamitans), average weight 4.84±0.97kg, male and female, were used for this study. A [...] fter a 12-hour period of food restriction and 6 hours of water restriction, the animals were physically restraint and the following parameters were measured: heart rate (HR), respiratory rate (RR), capillary refill time (CRT), rectal temperature (RT), non invasive systolic arterial pressure (NISAP) and arterial blood gases analysis. The animals were distributed into two groups: CG (Conventional Group, n=6), in which the animals received S(+) ketamine (5mg kg-1) and midazolam (0.5mg kg-1), by intramuscular (IM) injection; and AG (Allometry Group, n=6), in which the animals also received S(+) ketamine and midazolan IM, but the doses were calculated by allometric extrapolation. Parameters were evaluated at the following moments: M5, M10, M20 and M30 (5, 10, 20 and 30 minutes after IM injection, respectively). Muscle relaxation, pedal and caudal reflexes, interdigital pinch, recumbency time, sedation's quality and duration, and recovery time and its quality were also evaluated. The AG had a faster time for recumbency, higher period and quality of sedation, and a significantly reduction on HR and SAP from M5 to M30 when compared to CG. It was concluded that allometric extrapolation presented a better muscle relaxation and sedation without significant cardiorespiratory depression.

Joana Aurora Braun, Chagas; Nilson, Oleskovicz; Aury Nunes de, Moraes; Fabíola Niederauer, Flôres; André Luís, Corrêa; Júlio César, Souza Júnior; André Vasconcelos, Soares; Átila, Costa.

131

Accelerating Monte Carlo Molecular Simulations Using Novel Extrapolation Schemes Combined with Fast Database Generation on Massively Parallel Machines  

We introduce an efficient thermodynamically consistent technique to extrapolate and interpolate normalized Canonical NVT ensemble averages like pressure and energy for Lennard-Jones (L-J) fluids. Preliminary results show promising applicability in oil and gas modeling, where accurate determination of thermodynamic properties in reservoirs is challenging. The thermodynamic interpolation and thermodynamic extrapolation schemes predict ensemble averages at different thermodynamic conditions from expensively simulated data points. The methods reweight and reconstruct previously generated database values of Markov chains at neighboring temperature and density conditions. To investigate the efficiency of these methods, two databases corresponding to different combinations of normalized density and temperature are generated. One contains 175 Markov chains with 10,000,000 MC cycles each and the other contains 3000 Markov chains with 61,000,000 MC cycles each. For such massive database creation, two algorithms to parallelize the computations have been investigated. The accuracy of the thermodynamic extrapolation scheme is investigated with respect to classical interpolation and extrapolation. Finally, thermodynamic interpolation benefiting from four neighboring Markov chains points is implemented and compared with previous schemes. The thermodynamic interpolation scheme using knowledge from the four neighboring points proves to be more accurate than the thermodynamic extrapolation from the closest point only, while both thermodynamic extrapolation and thermodynamic interpolation are more accurate than the classical interpolation and extrapolation. The investigated extrapolation scheme has great potential in oil and gas reservoir modeling.That is, such a scheme has the potential to speed up the MCMC thermodynamic computation to be comparable with conventional Equation of State approaches in efficiency. In particular, this makes it applicable to large-scale optimization of L-J model parameters for hydrocarbons and other important reservoir species. The efficiency of the thermodynamic dependent techniques is expected to make the Markov chains simulation an attractive alternative in compositional multiphase flow simulation.

Amir, Sahar Z.

2013-05-01

132

Why people underestimate y when extrapolating in linear functions.  

Science.gov (United States)

E. L. DeLosh, J. R. Busemeyer, and M. A. McDaniel (1997) found that when learning a positive, linear relationship between a continuous predictor (x) and a continuous criterion (y), trainees tend to underestimate y on items that ask the trainee to extrapolate. In 3 experiments, the authors examined the phenomenon and found that the tendency to underestimate y is reliable only in the so-called lower extrapolation region--that is, new values of x that lie between zero and the edge of the training region. Existing models of function learning, such as the extrapolation-association model (DeLosh et al., 1997) and the population of linear experts model (M. L. Kalish, S. Lewandowsky, & J. Kruschke, 2004), cannot account for these results. The authors show that with minor changes, both models can predict the correct pattern of results. PMID:16938043

Kwantes, Peter J; Neal, Andrew

2006-09-01

133

Weights, Extrapolation and the Theory of Rubio de Francia  

CERN Document Server

This book provides a systematic development of the Rubio de Francia theory of extrapolation, its many generalizations and its applications to one and two-weight norm inequalities. The book is based upon a new and elementary proof of the classical extrapolation theorem that fully develops the power of the Rubio de Francia iteration algorithm. This technique allows us to give a unified presentation of the theory and to give important generalizations to Banach function spaces and to two-weight inequalities. We provide many applications to the classical operators of harmonic analysis to illustrate

Cruz-Uribe, David; Perez, Carlos

2011-01-01

134

Precision state and filter weighting matrix extrapolation, revision 3  

Science.gov (United States)

The matrix extrapolation routine presented is a coded algorithm for the numerical solution of modified forms of the basic differential equations which are satisfied by the geocentric state vector of a spacecraft's center of mass and by the filter-weighting matrix. The equations are described in detail and the various input and output variables designated. The capability is thus established to extrapolate any spacecraft's geocentric state vector, either backwards or forwards in time, through a force field consisting of the earth's primary central-force gravitational attraction, and a superimposed perturbing acceleration.

Robertson, W. M.

1972-01-01

135

Extrapolation of ASDEX Upgrade H-mode discharges to ITER  

International Nuclear Information System (INIS)

In this paper we discuss a procedure to evaluate the fusion performance of ASDEX Upgrade discharges scaled up to ITER. The kinetic profile shape is taken from the measured profiles. Multiplication factors are used to obtain a fixed Greenwald fraction and an ITER normalized thermal pressure as in the corresponding ASDEX Upgrade discharge. The toroidal field and the plasma geometry are taken from the ITER-FEAT design (scenario 2), whereas q95 is taken from the experiment. The confinement time is inferred assuming that the measured H-factor with respect to several existing scaling laws also holds for ITER. While retaining the information contained in the multi-machine databases underlying the different scaling laws, this approach adds profile effects and confinement improvement with respect to the ITER baseline, thus including recent experimental evidence such as the prediction of peaked density profiles in ITER. Under this set of assumptions, of course not unique, we estimate the ITER performance on the basis of a wide database of ASDEX Upgrade H-mode discharges, in terms of fusion power, fusion gain and triple product. According to the three scalings considered, there is a finite probability of reaching ignition, while more than half of the discharges require less auxiliary power than the one foreseen for ITER. For all the scaling laws, high values of the thermal ?N up to 2.4 are accessible. A sensitivity study gives an estimate of the accuracy of the extrapolation. The impact of different levels of tungsten concentration on the fusion performance is also studied in this paper. This scaling method is used to verify some common 0D figures of merit of ITER's fusion performance.

2009-07-01

136

Variational procedure for nuclear shell-model calculations and energy-variance extrapolation  

CERN Document Server

We discuss a variational calculation for nuclear shell-model calculations and propose a new procedure for the energy-variance extrapolation (EVE) method using a sequence of the approximated wave functions obtained by the variational calculation. The wave functions are described as linear combinations of the parity, angular-momentum projected Slater determinants, the energy of which is minimized by the conjugate gradient method obeying the variational principle. The EVE generally works well using the wave functions, but we found some difficult cases where the EVE gives a poor estimation. We discuss the origin of the poor estimation concerning shape coexistence. We found that the appropriate reordering of the Slater determinants allows us to overcome this difficulty and to reduce the uncertainty of the extrapolation.

Shimizu, Noritaka; Mizusaki, Takahiro; Honma, Michio; Tsunoda, Yusuke; Otsuka, Takaharu

2012-01-01

137

Performance characteristics of an extrapolation chamber for beta radiation detection  

International Nuclear Information System (INIS)

The performance of an extrapolation chamber was evaluated in ? radiation fields. The main characteristics such as calibration factors, energy and angular dependence, transmission factors in tissue and source-detector distance dependence have been determined. The influence of the collecting electrode area on the calibration factors was also investigated. (author)

1986-01-01

138

Freeze-out parameters from continuum extrapolated lattice data  

CERN Document Server

We present continuum extrapolated lattice results for the higher order fluctuations of conserved charges in high temperature Quantum Chromodynamics. Through the matching of the grand canonical ensemble on the lattice to the net charge and net baryon distribution realized in heavy ion experiments the temperature and the chemical potential may be estimated at the time of chemical freeze-out

Borsanyi, S; Katz, S D; Krieg, S; Ratti, C; Szabo, K K

2013-01-01

139

Extrapolation of ZPR sodium void measurements to the power reactor  

International Nuclear Information System (INIS)

Sodium-voiding measurements of ZPPR assemblies 2 and 5 are analyzed with ENDF/B Version IV data. Computations include directional diffusion coefficients to account for streaming effects resulting from the plate structure of the critical assembly. Bias factors for extrapolating critical assembly data to the CRBR design are derived from the results of this analysis

1976-10-08

140

Comparing Gravitational Waveform Extrapolation to Cauchy-Characteristic Extraction in Binary Black Hole Simulations  

CERN Multimedia

We extract gravitational waveforms from numerical simulations of black hole binaries computed using the Spectral Einstein Code. We compare two extraction methods: direct construction of the Newman-Penrose (NP) scalar $\\Psi_4$ at a finite distance from the source and Cauchy-characteristic extraction (CCE). The direct NP approach is simpler than CCE, but NP waveforms can be contaminated by near-zone effects---unless the waves are extracted at several distances from the source and extrapolated to infinity. Even then, the resulting waveforms can in principle be contaminated by gauge effects. In contrast, CCE directly provides, by construction, gauge-invariant waveforms at future null infinity. We verify the gauge invariance of CCE by running the same physical simulation using two different gauge conditions. We find that these two gauge conditions produce the same CCE waveforms but show differences in extrapolated-$\\Psi_4$ waveforms. We examine data from several different binary configurations and measure the domi...

Taylor, Nicholas W; Reisswig, Christian; Scheel, Mark A; Chu, Tony; Kidder, Lawrence E; Szilagyi, Bela

2013-01-01

 
 
 
 
141

A physiologically based pharmacokinetics model for florfenicol in crucian carp and oral-to-intramuscular extrapolation.  

Science.gov (United States)

In this study, an oral physiologically based pharmacokinetics (PBPK) model was developed for florfenicol in crucian carp (Carassius auratus). Subsequently, oral-to-intramuscular extrapolation was performed and the two models were used to predict florfenicol concentrations in the edible tissues of crucian carp. The oral model gave good predictions in most tissues, except for kidney and liver in which the florfenicol concentrations were underestimated at the later time points. In contrast, using the intramuscular model, the concentrations in the kidney were overestimated at the later time points. Both models had the best predictive ability in the main edible tissue, the muscle. The oral model also accurately predicted the florfenicol concentrations in the muscle after multiple doses. The present study demonstrated the feasibility of predicting florfenicol concentrations in the edible tissues of crucian carp using a route-to-route extrapolation method. PMID:22712485

Yang, F; Sun, N; Sun, Y X; Shan, Q; Zhao, H Y; Zeng, D P; Zeng, Z L

2013-04-01

142

Extrapolation and Local Acceleration of an Iterative Process for Common Fixed Point Problems  

CERN Document Server

We consider sequential iterative processes for the common fixed point problem of families of cutter operators on a Hilbert space. These are operators that have the property that, for any point x\\inH, the hyperplane through Tx whose normal is x-Tx always "cuts" the space into two half-spaces one of which contains the point x while the other contains the (assumed nonempty) fixed point set of T. We define and study generalized relaxations and extrapolation of cutter operators and construct extrapolated cyclic cutter operators. In this framework we investigate the Dos Santos local acceleration method in a unified manner and adopt it to a composition of cutters. For these we conduct convergence analysis of successive iteration algorithms.

Cegielski, Andrzej

2012-01-01

143

Improving the reliability of the background extrapolation in transmission electron microscopy elemental maps by using three pre-edge windows  

International Nuclear Information System (INIS)

Over the last decades, elemental maps have become a powerful tool for the analysis of the spatial distribution of the elements within specimen. In energy-filtered transmission electron microscopy (EFTEM) one commonly uses two pre-edge and one post-edge image for the calculation of elemental maps. However, this so called three-window method can introduce serious errors into the extrapolated background for the post-edge window. Since this method uses only two pre-edge windows as data points to calculate a background model that depends on two fit parameters, the quality of the extrapolation can be estimated only statistically assuming that the background model is correct. In this paper, we will discuss a possibility to improve the accuracy and reliability of the background extrapolation by using a third pre-edge window. Since with three data points the extrapolation becomes over-determined, this change permits us to estimate not only the statistical uncertainly of the fit, but also the systematic error by using the experimental data. Furthermore we will discuss in this paper the acquisition parameters that should be used for the energy windows to reach an optimal signal-to-noise ratio (SNR) in the elemental maps. -- Highlights: ? Comparison of three pre-edge windows to the regular two pre-edge windows. ? Investigation of the optimal positioning of the third pre-edge window. ? Description of the ?2 test for extrapolation quality check.

2012-07-01

144

TLD extrapolation for skin dose determination in vivo  

International Nuclear Information System (INIS)

Prediction of skin reactions requires knowledge of the dose at various depths in the human skin. Using thermoluminescence dosimeters of three different thicknesses, the dose can be extrapolated to the surface and interpolated between the different depths. A TLD holder was designed for these TLD extrapolation measurements on patients during treatment which allowed measurements of entrance and exit skin dose with a day to day variability of ±7% (S.D. of mean reading). In a pilot study on 18 patients undergoing breast irradiation, it was found that the angle of incidence of the radiation beam is the most significant factor influencing skin entrance dose. In most of these measurements the beam exit dose contributed 50% more to the surface dose than the entrance dose

1996-11-01

145

Extrapolated gradientlike algorithms for molecular dynamics and celestial mechanics simulations.  

Science.gov (United States)

A class of symplectic algorithms is introduced to integrate the equations of motion in many-body systems. The algorithms are derived on the basis of an advanced gradientlike decomposition approach. Its main advantage over the standard gradient scheme is the avoidance of time-consuming evaluations of force gradients by force extrapolation without any loss of precision. As a result, the efficiency of the integration improves significantly. The algorithms obtained are analyzed and optimized using an error-function theory. The best among them are tested in actual molecular dynamics and celestial mechanics simulations for comparison with well-known nongradient and gradient algorithms such as the Störmer-Verlet, Runge-Kutta, Cowell-Numerov, Forest-Ruth, Suzuki-Chin, and others. It is demonstrated that for moderate and high accuracy, the extrapolated algorithms should be considered as the most efficient for the integration of motion in molecular dynamics simulations. PMID:17025782

Omelyan, I P

2006-09-01

146

Extrapolation and optimal decompositions with applications to analysis  

CERN Document Server

This book develops a theory of extrapolation spaces with applications to classical and modern analysis. Extrapolation theory aims to provide a general framework to study limiting estimates in analysis. The book also considers the role that optimal decompositions play in limiting inequalities incl. commutator estimates. Most of the results presented are new or have not appeared in book form before. A special feature of the book are the applications to other areas of analysis. Among them Sobolev imbedding theorems in different contexts including logarithmic Sobolev inequalities are obtained, commutator estimates are connected to the theory of comp. compactness, a connection with maximal regularity for abstract parabolic equations is shown, sharp estimates for maximal operators in classical Fourier analysis are derived.

Milman, Mario

1994-01-01

147

Application of the Weibull extrapolation to 137Cs geochronology in Tokyo Bay and Ise Bay, Japan  

International Nuclear Information System (INIS)

Considerable doubt surrounds the nature of processes by which 137Cs is deposited in marine sediments, leading to a situation where 137Cs geochronology cannot be always applied suitably. Based on extrapolation with Weibull distribution, the maximum concentration of 137Cs derived from asymptotic values for cumulative specific inventory was used to re-establish 137Cs geochronology, instead of original 137Cs profiles. Corresponding dating results for cores in Tokyo Bay and Ise Bay, Japan, by means of this new method, are in much closer agreement with those calculated from 210Pb method than the previous method

2004-01-01

148

An efficient extrapolation to the (T)/CBS limit  

Science.gov (United States)

We extrapolate to the perturbative triples (T)/complete basis set (CBS) limit using double ? basis sets without polarization functions (Wesleyan-1-Triples-2? or "Wes1T-2Z") and triple ? basis sets with a single level of polarization functions (Wesleyan-1-Triples-3? or "Wes1T-3Z"). These basis sets were optimized for 102 species representing the first two rows of the Periodic Table. The species include the entire set of neutral atoms, positive and negative atomic ions, as well as several homonuclear diatomic molecules, hydrides, rare gas dimers, polar molecules, such as oxides and fluorides, and a few transition states. The extrapolated Wes1T-(2,3)Z triples energies agree with (T)/CBS benchmarks to within ±0.65 mEh, while the rms deviations of comparable model chemistries W1, CBS-APNO, and CBS-QB3 for the same test set are ±0.23 mEh, ±2.37 mEh, and ±5.80 mEh, respectively. The Wes1T-(2,3)Z triples calculation time for the largest hydrocarbon in the G2/97 test set, C6H5Me+, is reduced by a factor of 25 when compared to W1. The cost-effectiveness of the Wes1T-(2,3)Z extrapolation validates the usefulness of the Wes1T-2Z and Wes1T-3Z basis sets which are now available for a more efficient extrapolation of the (T) component of any composite model chemistry.

Ranasinghe, Duminda S.; Barnes, Ericka C.

2014-05-01

149

Revisiting Chiral Extrapolation by Studying a Lattice Quark Propagator  

International Nuclear Information System (INIS)

The quark propagator in the Landau gauge is studied on the lattice, including the quenched and the unquenched results. No obvious unquenched effects are found by comparing the quenched quark propagator with the dynamical one. For the quenched and unquenched configurations, the results with different quark masses have been computed. For the quark mass function, a nonlinear chiral extrapolating behavior is found in the infrared region for both the quenched and dynamical results. (the physics of elementary particles and fields)

2009-08-01

150

Extrapolation in games of coordination and dominance solvable games  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study extrapolation between games in a laboratory experiment. Participants in our experiment first play either the dominance solvable guessing game or a Coordination version of the guessing game for five rounds. Afterwards they play a 3x3 normal form game for ten rounds with random matching which is either a game solvable through iterated elimination of dominated strategies (IEDS), a pure Coordination game or a Coordination game with pareto ranked equilibria. We find strong evidence that p...

2010-01-01

151

Continuum extrapolation of $B_K$ with staggered fermions  

CERN Document Server

We report on recent progress in the calculation of $B_K$ using HYP-smeared staggered fermions on the MILC asqtad lattices. Our main focus is on the continuum extrapolation, which is done using (up to) four different lattice spacings---$a\\approx$ 0.12, 0.09, 0.06 and 0.045 fm. Since Lattice 2010, we have reduced the statistical errors on the $a\\approx 0.09\\;$fm lattices by a factor of $\\sim 3$, and roughly doubled the size of the $a\\approx0.045\\;$fm ensemble. We find that these improvements have a very significant impact on the continuum extrapolation, with the $a\\approx 0.12\\;$fm data lying outside the range of applicability of simple functional forms. Hence we use only the three smallest lattice spacings to perform the extrapolation, finding $\\hat{B}_K = B_K(\\text{RGI}) = 0.725 \\pm 0.004(\\text{stat}) \\pm 0.038(\\text{sys}) $. This value is consistent with our published value from 2010 (based the three coarsest lattice spacings), but has smaller errors.

Lee, Weonjong; Kim, Hyung-Jin; Kim, Jangho; Kim, Kwangwoo; Yoon, Boram; Bae, Taegil; Jung, Chulwoo; Kim, Jongjeong; Sharpe, Stephen R

2011-01-01

152

Three dimensional image guided extrapolation for cone-beam CT image reconstruction  

Science.gov (United States)

In cone-beam CT the range of projection views measured for each given image voxel is spatially variant. In the corners of the image volume there is less projection data available to be used by the image reconstruction algorithm, due to data truncation in the z direction (i.e. along the scanner axis). Given the desire to increase the fraction of the voxels which may be reconstructed from a given scan there is a desire to incorporate some extrapolated data into the image reconstruction procedure. In this work one approach is described which consists of a two-pass procedure where the first pass image reconstruction is performed over a larger extent in the z direction, a non-linear transform is applied to the initial reconstruction and a forward projection is applied in order to estimate the extrapolated image data. Initial results are presented which compare the method to zeroth order extrapolation and demonstrate that improvement in the reconstruction of the corner regions with a simple numerical phantom and with anatomical phantom data from a prototype wide coverage CT system.

Nett, Brian

2014-03-01

153

A technique to improve the accuracy of Earth orientation prediction algorithms based on least squares extrapolation  

Science.gov (United States)

We present a technique to improve the least squares (LS) extrapolation of Earth orientation parameters (EOPs), consisting of fixing the last observed data point on the LS extrapolation curve, which customarily includes a polynomial and a few sinusoids. For the polar motion (PM), a more sophisticated two steps approach has been developed, which consists of estimating the amplitude of the more stable one of the annual (AW) and Chandler (CW) wobbles using data of longer time span, and then estimating the other parameters using a shorter time span. The technique is studied using hindcast experiments, and justified using year-by-year statistics of 8 years. In order to compare with the official predictions of the International Earth Rotation and Reference Systems Service (IERS) performed at the U.S. Navy Observatory (USNO), we have enforced short-term predictions by applying the ARIMA method to the residuals computed by subtracting the LS extrapolation curve from the observation data. The same as at USNO, we have also used atmospheric excitation function (AEF) to further improve predictions of UT1-UTC. As results, our short-term predictions are comparable to the USNO predictions, and our long-term predictions are marginally better, although not for every year. In addition, we have tested the use of AEF and oceanic excitation function (OEF) in PM prediction. We find that use of forecasts of AEF alone does not lead to any apparent improvement or worsening, while use of forecasts of AEF + OEF does lead to apparent improvement.

Guo, J. Y.; Li, Y. B.; Dai, C. L.; Shum, C. K.

2013-10-01

154

Optimisation of efficiency extrapolation functions in radioactivity standardisation  

International Nuclear Information System (INIS)

When radioactivity is measured by 4??-? efficiency extrapolation the data is commonly fitted to a linear function, but also to a polynomial function of second or third order if this proves necessary. In order to justify the empirical fitting procedure, we compared the experimental results with some functions which could be expected on theoretical grounds. The most suitable function was a linear function at high 4? counting efficiencies joined on to a second-order function at low 4? counting efficiencies, while a third-order polynomial function without second-order term produced accurate results regardless of the fitting region. (author)

1986-01-01

155

Assessing ecological effects of radionuclides: data gaps and extrapolation issues  

International Nuclear Information System (INIS)

By inspection of the FASSET database on radiation effects on non-human biota, one of the major difficulties in the implementation of ecological risk assessments for radioactive pollutants is found to be the lack of data for chronic low-level exposure. A critical review is provided of a number of extrapolation issues that arise in undertaking an ecological risk assessment: acute versus chronic exposure regime; radiation quality including relative biological effectiveness and radiation weighting factors; biological effects from an individual to a population level, including radiosensitivity and lifestyle variations throughout the life cycle; single radionuclide versus multi-contaminants. The specificities of the environmental situations of interest (mainly chronic low-level exposure regimes) emphasise the importance of reproductive parameters governing the demography of the population within a given ecosystem and, as a consequence, the structure and functioning of that ecosystem. As an operational conclusion to keep in mind for any site-specific risk assessment, the present state-of-the-art on extrapolation issues allows us to grade the magnitude of the uncertainties as follows: one species to another > acute to chronic = external to internal = mixture of stressors> individual to population> ecosystem structure to function

2004-12-01

156

Longitudinal static optical properties of hydrogen chains: finite field extrapolations of matrix product state calculations  

CERN Document Server

We have implemented the sweep algorithm for the variational optimization of SU(2) x U(1) (spin and particle number) invariant matrix product states (MPS) for general spin and particle number invariant fermionic Hamiltonians. This class includes non-relativistic quantum chemical systems within the Born-Oppenheimer approximation. High-accuracy ab-initio finite field results of the longitudinal static polarizabilities and second hyperpolarizabilities of one-dimensional hydrogen chains are presented. This allows to assess the performance of other quantum chemical methods. For small basis sets, MPS calculations in the saturation regime of the optical response properties can be performed. These results are extrapolated to the thermodynamic limit.

Wouters, Sebastian; Van Neck, Dimitri; Ayers, Paul W

2012-01-01

157

The evaluation of preliminary extrapolation experimental results of the chinese ADS subcritical experimental assembly venus-1  

International Nuclear Information System (INIS)

The design objectives and structure of' the Chinese accelerator-driven subcritical system (ADS) subcritical assembly VENUS-1 are presented. The experiment of source multiplication method is used to determine the final loading of the Chinese ADS VENUS-i subcritical assembly. The Keff of the assembly with the same loading as extrapolation experiment have been calculated. The results of calculation and experiment are evaluated. The final loading of the Chinese ADS VENUS-1 subcritical assembly has been determined by preliminary experiments on VENUS-1. (authors)

2008-01-01

158

Beamforming regularization matrix and inverse problems applied to sound field measurement and extrapolation using microphone array  

Science.gov (United States)

For sound field reproduction using multichannel spatial sound systems such as Wave Field Synthesis and Ambisonics, sound field extrapolation is a useful tool for the measurement, description and characterization of a sound environment to be reproduced in a listening area. In this paper, the inverse problem theory is adapted to sound field extrapolation around a microphone array for further spatial sound and sound environment reproduction. A general review of inverse problem theory and analysis tools is given and used for the comparative evaluation of various microphone array configurations. Classical direct regularization methods such as truncated singular value decomposition and Tikhonov regularization are recalled. On the basis of the reviewed background, a new regularization method adapted to the problem at hand is introduced. This method involves the use of an a priori beamforming measurement to define a data-dependent discrete smoothing norm for the regularization of the inverse problem. This method which represents the main contribution of this paper shows promising results and opens new research avenues.

Gauthier, P.-A.; Camier, C.; Pasco, Y.; Berry, A.; Chambatte, E.; Lapointe, R.; Delalay, M.-A.

2011-11-01

159

L2-Error Estimates of the Extrapolated Crank-Nicolson Discontinuous Galerkin Approximations for Nonlinear Sobolev Equations  

Directory of Open Access Journals (Sweden)

Full Text Available We analyze discontinuous Galerkin methods with penalty terms, namely, symmetric interior penalty Galerkin methods, to solve nonlinear Sobolev equations. We construct finite element spaces on which we develop fully discrete approximations using extrapolated Crank-Nicolson method. We adopt an appropriate elliptic-type projection, which leads to optimal ??(L2 error estimates of discontinuous Galerkin approximations in both spatial direction and temporal direction.

Hyun Young Lee

2010-01-01

160

True amplitude migration using common-shot one-way wavefield extrapolation  

Energy Technology Data Exchange (ETDEWEB)

Kirchhoff migration has been commonly applied to most 3-D prestack migrations because of its versatility, but the need for increased imaging fidelity has led to the development of methods that allow for an unlimited number of arrivals. This paper presented a fluid flow imaging method that can deal with more than a single arrival and describes a one-way wavefield extrapolation with particular reference to its amplitude and phase behaviour. This new method offers greater structural imaging quality. The amplitudes produced by shot-record migration using one-way wavefield extrapolation in a medium with velocity v(z) was analyzed. The amplitudes were then compared with those produced by true-amplitude Kirchhoff migration to determine amplitude and phase errors. The standard formulation of finite-difference migration consists of a downward continuation of the wavefields from the source and receiver locations using a split wave equation. It also includes an imaging condition which divides the downward receiver wavefield by the downward source wavefield at each image point. However, the wave equations in the downward continuation are not equivalent to the acoustic wave equation, resulting in a migrated wavefield and incorrect amplitude and phase behaviour. The equation was corrected by comparing the imaged wavefield with the reflection coefficient produced by true amplitude Kirchhoff migration. 7 refs., 5 figs.

Zhang, Y.; Sun, J. [Veritas DGC Inc., Houston, TX (United States); Notfors, C. [Veritas DGC Inc., Singapore (Singapore); Gray, S.H. [Veritas DGC Inc., Calgary, AB (Canada); Bleistein, N. [Colorado School of Mines, Golden, CO (United States); Zhang, G. [Chinese Academy of Sciences (China)

2003-07-01

 
 
 
 
161

Application of extrapolation chambers in low-energy X-rays as reference systems.  

Science.gov (United States)

Extrapolation chambers are instruments designed to measure doses of low-energy radiations, mainly beta radiation. In this work, a commercial extrapolation chamber and a homemade extrapolation chamber were applied in measurements using standard radiotherapy X-ray beams. Saturation curves and polarity effect as well as short- and medium-term stabilities were obtained, and these results are within the recommendations of the International Electrotechnical Commission (IEC). The response linearity and the extrapolation curves were also obtained, and they presented good behavior. The results show the usefulness of these extrapolation chambers in low-energy X-ray beams. PMID:22520689

da Silva, Eric A B; Caldas, Linda V E

2012-07-01

162

3D Drop Size Distribution Extrapolation Algorithm Using a Single Disdrometer  

Science.gov (United States)

Determining the Z-R relationship (where Z is the radar reflectivity factor and R is rainfall rate) from disdrometer data has been and is a common goal of cloud physicists and radar meteorology researchers. The usefulness of this quantity has traditionally been limited since radar represents a volume measurement, while a disdrometer corresponds to a point measurement. To solve that problem, a 3D-DSD (drop-size distribution) method of determining an equivalent 3D Z-R was developed at the University of Central Florida and tested at the Kennedy Space Center, FL. Unfortunately, that method required a minimum of three disdrometers clustered together within a microscale network (.1-km separation). Since most commercial disdrometers used by the radar meteorology/cloud physics community are high-cost instruments, three disdrometers located within a microscale area is generally not a practical strategy due to the limitations of these kinds of research budgets. A relatively simple modification to the 3D-DSD algorithm provides an estimate of the 3D-DSD and therefore, a 3D Z-R measurement using a single disdrometer. The basis of the horizontal extrapolation is mass conservation of a drop size increment, employing the mass conservation equation. For vertical extrapolation, convolution of a drop size increment using raindrop terminal velocity is used. Together, these two independent extrapolation techniques provide a complete 3DDSD estimate in a volume around and above a single disdrometer. The estimation error is lowest along a vertical plane intersecting the disdrometer position in the direction of wind advection. This work demonstrates that multiple sensors are not required for successful implementation of the 3D interpolation/extrapolation algorithm. This is a great benefit since it is seldom that multiple sensors in the required spatial arrangement are available for this type of analysis. The original software (developed at the University of Central Florida, 1998.- 2000) has also been modified to read standardized disdrometer data format (Joss-Waldvogel format). Other modifications to the software involve accounting for vertical ambient wind motion, as well as evaporation of the raindrop during its flight time.

Lane, John

2012-01-01

163

On the extrapolation to ITER of discharges in present tokamaks  

CERN Document Server

An expression for the extrapolated fusion gain G = Pfusion /5 Pheat (Pfusion being the total fusion power and Pheat the total heating power) of ITER in terms of the confinement improvement factor (H) and the normalised beta (betaN) is derived in this paper. It is shown that an increase in normalised beta can be expected to have a negative or neutral influence on G depending on the chosen confinement scaling law. Figures of merit like H betaN / q95^2 should be used with care, since large values of this quantity do not guarantee high values of G, and might not be attainable with the heating power installed on ITER.

Peeters, A G; Sips, A C C

2007-01-01

164

National pattern for the realization of the unit of the dose speed absorbed in air for beta radiation. (Method: Ionometer, cavity of Bragg-Gray implemented in an extrapolation chamber with electrodes of variable separation, exposed to a field of beta radiation of {sup 90}Sr/{sup 90}Y); Patron Nacional para la realizacion de la unidad de la rapidez de dosis absorbida en aire para radiacion beta. (Metodo: Ionometrico, cavidad de Bragg-Gray implementada en una camara de extrapolacion con electrodos de separacion variable, expuesta a un campo de radiacion beta de {sup 90}Sr/{sup 90}Y)  

Energy Technology Data Exchange (ETDEWEB)

From the year of 1987 the Department of Metrology of the ININ, in their Secondary Laboratory of Calibration Dosimetric, has a patron group of sources of radiation beta and an extrapolation chamber of electrodes of variable separation.Their objective is to carry out of the unit of the dose speed absorbed in air for radiation beta. It uses the ionometric method, cavity Bragg-Gray in the extrapolation chamber with which it counts. The services that offers are: i) it Calibration : Radioactive Fuentes of radiation beta, isotopes: {sup 90}Sr/{sup 90}Y; Ophthalmic applicators {sup 9}0{sup S}r/{sup 90}Y; Instruments for detection of beta radiation with to the radiological protection: Ionization chambers, Geiger-Muller, etc.; Personal Dosemeters. ii) Irradiation with beta radiation of materials to the investigation. (Author)

Alvarez R, M. T.; Morales P, J. R. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

2001-01-15

165

Determination of dose rates in beta radiation fields using extrapolation chamber and GM counter  

DEFF Research Database (Denmark)

The extrapolation chamber measurement method is the basic method for the determination of dose rates in beta radiation fields and the method has been used for the establishment of beta calibration fields. The paper describes important details of the method and presents results from the measurement of depth-dose profiles from different beta radiation fields with E(max) values down to 156 keV. Results are also presented from studies of GM counters for use as survey instruments for monitoring beta dose rates at the workplace. Advantages of GM counters are a simple measurement technique and high sensitivity. GM responses were measured from exposures in different beta radiation fields using different filters in front of the GM detector and the paper discusses the possibility of using the results from GM measurements with two different filters in an unknown beta radiation field to obtain a value of the dose rate.

Borg, J.; Christensen, P.

1995-01-01

166

Extrapolation from animals to the human for the retention of radiothallium in the blood  

International Nuclear Information System (INIS)

The extrapolation of tissue distribution data from animal to human has implications in the clinical application of new radiopharmaceuticals, in studies of biodistribution and biokinetics, and in estimation of radiation absorbed dose. The extrapolative method described in this study is based on the assumption that the mechanism of tissue distribution of a radionuclide in different mammalian species is similar. This assumption implies that the fractional distribution function, ?/sub h/(t), of a radionuclide in a specific tissue of one species is related to the corresponding fractional distribution function in any other species by linear transformations in the activity and time variables. Hence, the successful application of the extrapolative technique requires determining a reference ?/sub h/(t) based on a conveniently studied species and finding the relationships between the factors of the transformations and one or more measurable species-dependent parameters. To test this approach, data for retention of T1-201 in the blood of several species were used. Detailed biokinetic data in mice, collected in our laboratory, were used to determine the reference ?/sub h/(t) mouse. Data for other species were extracted from the literature and compared with ?/sub h/(t) mouse to determine the transformation factors, using the least squares fitting technique. These factors appear, on the basis of the data available, to be power functions of body weight. Retention of activity in blood was chosen as a test of the theory because data have been published for several nonhuman species as well as verifying values for the human

1981-06-01

167

Extrapolation from animals to the human for the retention of radiothallium in the blood  

Energy Technology Data Exchange (ETDEWEB)

The extrapolation of tissue distribution data from animal to human has implications in the clinical application of new radiopharmaceuticals, in studies of biodistribution and biokinetics, and in estimation of radiation absorbed dose. The extrapolative method described in this study is based on the assumption that the mechanism of tissue distribution of a radionuclide in different mammalian species is similar. This assumption implies that the fractional distribution function, ..cap alpha../sub h/(t), of a radionuclide in a specific tissue of one species is related to the corresponding fractional distribution function in any other species by linear transformations in the activity and time variables. Hence, the successful application of the extrapolative technique requires determining a reference ..cap alpha../sub h/(t) based on a conveniently studied species and finding the relationships between the factors of the transformations and one or more measurable species-dependent parameters. To test this approach, data for retention of T1-201 in the blood of several species were used. Detailed biokinetic data in mice, collected in our laboratory, were used to determine the reference ..cap alpha../sub h/(t) mouse. Data for other species were extracted from the literature and compared with ..cap alpha../sub h/(t) mouse to determine the transformation factors, using the least squares fitting technique. These factors appear, on the basis of the data available, to be power functions of body weight. Retention of activity in blood was chosen as a test of the theory because data have been published for several nonhuman species as well as verifying values for the human.

Tsui, B.M.W.; Lathrop, K.A.; Harper, P.V.

1981-06-01

168

Improving the reliability of the background extrapolation in transmission electron microscopy elemental maps by using three pre-edge windows  

Energy Technology Data Exchange (ETDEWEB)

Over the last decades, elemental maps have become a powerful tool for the analysis of the spatial distribution of the elements within specimen. In energy-filtered transmission electron microscopy (EFTEM) one commonly uses two pre-edge and one post-edge image for the calculation of elemental maps. However, this so called three-window method can introduce serious errors into the extrapolated background for the post-edge window. Since this method uses only two pre-edge windows as data points to calculate a background model that depends on two fit parameters, the quality of the extrapolation can be estimated only statistically assuming that the background model is correct. In this paper, we will discuss a possibility to improve the accuracy and reliability of the background extrapolation by using a third pre-edge window. Since with three data points the extrapolation becomes over-determined, this change permits us to estimate not only the statistical uncertainly of the fit, but also the systematic error by using the experimental data. Furthermore we will discuss in this paper the acquisition parameters that should be used for the energy windows to reach an optimal signal-to-noise ratio (SNR) in the elemental maps. -- Highlights: Black-Right-Pointing-Pointer Comparison of three pre-edge windows to the regular two pre-edge windows. Black-Right-Pointing-Pointer Investigation of the optimal positioning of the third pre-edge window. Black-Right-Pointing-Pointer Description of the {chi}{sup 2} test for extrapolation quality check.

Heil, Tobias, E-mail: tobiasheil@uni-muenster.de [Physikalisches Institut and Interdisziplinaeres Centrum fuer Elektronenmikroskopie und Mikroanalyse (ICEM), Universitaet Muenster, Wilhelm-Klemm-Str. 10, 48149 Muenster (Germany); Gralla, Benedikt, E-mail: lexx.matrix@uni-muenster.de [Physikalisches Institut and Interdisziplinaeres Centrum fuer Elektronenmikroskopie und Mikroanalyse (ICEM), Universitaet Muenster, Wilhelm-Klemm-Str. 10, 48149 Muenster (Germany); Epping, Michael, E-mail: michael.epping@uni-muenster.de [Physikalisches Institut and Interdisziplinaeres Centrum fuer Elektronenmikroskopie und Mikroanalyse (ICEM), Universitaet Muenster, Wilhelm-Klemm-Str. 10, 48149 Muenster (Germany); Kohl, Helmut, E-mail: kohl@uni-muenster.de [Physikalisches Institut and Interdisziplinaeres Centrum fuer Elektronenmikroskopie und Mikroanalyse (ICEM), Universitaet Muenster, Wilhelm-Klemm-Str. 10, 48149 Muenster (Germany)

2012-07-15

169

Determination of the bulk melting temperature of nickel using Monte Carlo simulations: Inaccuracy of extrapolation from cluster melting temperatures  

Science.gov (United States)

We have determined the bulk melting temperature Tm of nickel according to a recent interatomic interaction model via Monte Carlo simulation by two methods: extrapolation from cluster melting temperatures based on the Pavlov model (a variant of the Gibbs-Thompson model) and by calculation of the liquid and solid Gibbs free energies via thermodynamic integration. The result of the latter, which is the most reliable method, gives Tm=2010±35K , to be compared to the experimental value of 1726 K. The cluster extrapolation method, however, gives a 325° higher value of Tm=2335K . This remarkable result is shown to be due to a barrier for melting, which is associated with a nonwetting behavior.

Los, J. H.; Pellenq, R. J. M.

2010-02-01

170

Extrapolation from animals to the human for the retention of radiothallium in the blood  

International Nuclear Information System (INIS)

The extrapolation of tissue distribution data from animal to human has implications in the clinical application of new radiopharmaceuticals, in studies of biodistribution and biokinetics, and in estimation of radiation absorbed dose. The extrapolative method described in this study is based on the assumption that the mechanism of tissue distribution of a radionuclide in different mammalian species is similar. This assumption implies that the fractional distribution function, ?/sub h/(t), of a radionuclide in a specific tissue of one species is related to the corresponding fractional distribution function in any other species by linear transformations in the activity and time variables. To test this approach, data for retention of T1-201 in the blood of several species were used. Detailed biokinetic data in mice, collected in our laboratory, were used to determine the reference ?/sub h/(t)/sub mouse/. Data for other species were extracted from the literature and compared with ?/sub h/(t)/sub mouse/ to determine the transformation factors, using the least squares fitting technique. These factors appear, on the basis of the data available, to be power functions of body weight. Retention of activity in blood was chosen as a test of the theory because data have been published for several nonhuman species as well as verifying values for the human

1981-06-01

171

THREE-DIMENSIONAL STRUCTURE OF MICROWAVE SOURCES FROM SOLAR ROTATION STEREOSCOPY VERSUS MAGNETIC EXTRAPOLATIONS  

International Nuclear Information System (INIS)

We use rotation stereoscopy to estimate the height of a steady-state solar feature relative to the photosphere, based on its apparent motion in the image plane recorded over several days of observation. The stereoscopy algorithm is adapted to work with either one- or two-dimensional data (i.e., from images or from observations that record the projected position of the source along an arbitrary axis). The accuracy of the algorithm is tested on simulated data, and then the algorithm is used to estimate the coronal radio source heights associated with the active region NOAA 10956, based on multifrequency imaging data over seven days from the Siberian Solar Radio Telescope near 5.7 GHz, the Nobeyama Radio Heliograph at 17 GHz, as well as one-dimensional scans at multiple frequencies spanning the 5.98-15.95 GHz frequency range from the RATAN-600 instrument. The gyroresonance emission mechanism, which is sensitive to the coronal magnetic field strength, is applied to convert the estimated radio source heights at various frequencies, h(f), to information about magnetic field versus height B(h), and the results are compared to a magnetic field extrapolation derived from photospheric magnetic field observations obtained by Hinode and Michelson Doppler Imager. We found that the gyroresonant emission comes from heights exceeding the location of the third gyrolayer irrespective of the magnetic extrapolation method; implications of this finding for coronal magnetography and coronal plasma physics are discussed.

2011-08-20

172

Extrapolation procedures for calculating high-temperature Gibbs free energies of aqueous electrolytes  

International Nuclear Information System (INIS)

Methods for calculating high-temperature Gibbs free energies of mononuclear cations and anions from room-temperature data are reviewed. Emphasis is given to species required for oxide solubility calculations relevant to mass transport situations in the nuclear industry. Free energies predicted by each method are compared with selected values calculated from recently reported solubility studies and other literature data. Values for monatomic ions estimated using the assumption anti Csub(p)0(T)=anti Csub(p)0(298) agree best with experiment to 423 K. From 423 to 523 K, free energies from an electrostatic model for ion hydration are more accurate. Extrapolations for hydrolysed species are limited by a lack of room-temperature entropy data and expressions for estimating these entropies are discussed. (author)

1979-02-02

173

Precise estimates by finite-size extrapolations of the S=1 Haldane-gapped system  

International Nuclear Information System (INIS)

We carry out finite-size extrapolations of numerical-diagonalization data of the S=1 Heisenberg chain having a nonzero energy gap between the unique singlet ground state and the first excited state, namely the Haldane gap. Very precise estimates of the ground-state energy per site Eg/N -1.4014840447(39) and the staggered component of the magnetic structure factor S? = 3.864356(31) at T=0 are successfully obtained from the finite-size data of system sizes up to N = 24 under the twisted boundary condition by the sequence interval squeeze method, which was applied to a precise estimation of the Haldane gap by Nakano and Terai [J. Phys. Soc. Jpn. 78 (2009) 014003]. The present estimates are compared with other estimates in previous studies from various methods including the quantum Monte Carlo simulation and the density matrix renormalization group calculation.

2010-01-01

174

Applications of extrapolation techniques to multidimensional quadrature of some integrand functions with a singularity  

International Nuclear Information System (INIS)

Many large-scale calculations require the numerical integration of functions that are products of simple functions of a radius with a function readily expressed in cartesian coordinates. The analytic singularity at the origin can cause a relatively expensive calculation when standard methods are employed. The application of known asymptotic expansions to this sort of problem can result in a considerable reduction in expense or increase in accuracy. A set of useful expansions is stated. An approach based on extrapolation is described that leads to a method not unlike the Romberg integration. The emphasis here is on applications. For example, the rearrangement of the theory to provide a technique for grid-oriented calculations is discussed; and a full description of the possible effect of numerical instability, how to recognize it and how to alleviate it, is included. 3 tables

1976-01-01

175

Extrapolative Analysis of Fast-Switching Free Energy Estimates in a Molecular System  

CERN Document Server

We perform an extrapolative analysis of "fast-growth" free-energy-difference (DF) estimates of a computer-modeled, fully-solvated ethanemethanol transformation. The results suggest that extrapolation can greatly reduce the systematic error in DF estimated from a small number of very fast switches. Our extrapolation procedure uses block-averages of finite-data estimates, and appears to be particularly useful for broad, non-Gaussian distributions of data which produce substantial systematic errors with insufficient data. In every tested case, the extrapolative results were better than direct estimates.

Zuckerman, D M; Zuckerman, Daniel M.; Woolf, Thomas B.

2001-01-01

176

Generalized multi-hit dose response model for low-dose extrapolation  

International Nuclear Information System (INIS)

Man is exposed to a variety of natural and synthetic substances that are known to be harmful to experimental animals at high dose levels and consequently are under suspicion of being harmful to humans. The large number of animals required to obtain any positive response at low-dose levels makes it prohibitive to directly estimate the risk at the required dose levels. Thus, the most common method for establishing safe dose levels is to estimate a dose-response curve based on laboratory tests on a limited number of animals at exposure levels well beyond the human usage levels. Then, using such a dose-response curve, one attempts to establish a safe dose based on a statistical low-dose extrapolation procedure. This thesis introduces a generalized multi-hit dose-response model. A biological interpretation of the model in terms of the occurrence of k hits to cause the toxic response, and a statistical interpretation in terms of a gamma tolerance distribution are given. Other dose-response models in the literature are reviewed, with the one-hit or linear model being seen as a special case of the proposed model. The method of maximum likelihood for estimating the parameters of the model, their large sample properties, and their use in risk assessment through extrapolation to low-doses is presented. A method of point estimation of the virtual safe dose, along with its lower 100(1 - ?)% confidence limit is treated. The resulting procedures are then applied to twelve sets of toxic response data from the literature. Based on these applications, it is seen that the peformance of the model for risk assessment is similar to that of the one-hit model under evidence of near linearity of the dose-response curve in the low-dose range. However, under evidence of concavity (convexity) in the low-dose range, the model is more (less) stringent in its risk assessment

1978-01-01

177

Multi-threaded adaptive extrapolation procedure for Feynman loop integrals in the physical region  

International Nuclear Information System (INIS)

Feynman loop integrals appear in higher order corrections of interaction cross section calculations in perturbative quantum field theory. The integrals are computationally intensive especially in view of singularities which may occur within the integration domain. For the treatment of threshold and infrared singularities we developed techniques using iterated (repeated) adaptive integration and extrapolation. In this paper we describe a shared memory parallelization and its application to one- and two-loop problems, by multi-threading in the outer integrations of the iterated integral. The implementation is layered over OpenMP and retains the adaptive procedure of the sequential method exactly. We give performance results for loop integrals associated with various types of diagrams including one-loop box, pentagon, two-loop self-energy and two-loop vertex diagrams

2013-08-12

178

Characterization of a extrapolation chamber in standard X-ray beam, radiodiagnosis level  

International Nuclear Information System (INIS)

The extrapolation chamber is a ionization chamber used for detection low energy radiation and can be used as an standard instrument for beta radiation beams. This type of ionization chamber have as main characteristic the variation of sensible volume. This paper performs a study of characterization of a PTW commercial extrapolation chamber, in the energy interval of the qualities of conventional radiodiagnostic

2010-05-28

179

A new mini-extrapolation chamber for beta source uniformity measurements  

International Nuclear Information System (INIS)

According to recent international recommendations, beta particle sources should be specified in terms of absorbed dose rates to water at the reference point. However, because of the clinical use of these sources, additional information should be supplied in the calibration reports. This additional information include the source uniformity. A new small volume extrapolation chamber was designed and constructed at the Calibration Laboratory at Instituto de Pesquisas Energeticas e Nucleares, IPEN, Brazil, for the calibration of 90Sr+90Y ophthalmic plaques. This chamber can be used as a primary standard for the calibration of this type of source. Recent additional studies showed the feasibility of the utilization of this chamber to perform source uniformity measurements. Because of the small effective electrode area, it is possible to perform independent measurements by varying the chamber position by small steps. The aim of the present work was to study the uniformity of a 90Sr+90Y plane ophthalmic plaque utilizing the mini extrapolation chamber developed at IPEN. The uniformity measurements were performed by varying the chamber position by steps of 2 mm in the source central axis (x-and y-directions) and by varying the chamber position off-axis by 3 mm steps. The results obtained showed that this small volume chamber can be used for this purpose with a great advantage: it is a direct method, being unnecessary a previously calibration of the measurement device in relation to a reference instrument, and it provides real -time results, reducing the time necessary for the study and the determination of the uncertainties related to the measurements. (authors)

2006-05-15

180

Determination of the bulk melting temperature of nickel using Monte Carlo simulations: Inaccuracy of extrapolation from cluster melting temperatures  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have determined the bulk melting temperature T[subscript m] of nickel according to a recent interatomic interaction model via Monte Carlo simulation by two methods: extrapolation from cluster melting temperatures based on the Pavlov model (a variant of the Gibbs-Thompson model) and by calculation of the liquid and solid Gibbs free energies via thermodynamic integration. The result of the latter, which is the most reliable method, gives T[subscript m]=2010±35?K, to be compared to the exp...

Pellenq, Roland J. -m; Los, J. H.

2010-01-01

 
 
 
 
181

Design and construction of an interface system for the extrapolation chamber from the beta secondary standard  

International Nuclear Information System (INIS)

The Interface System for the Extrapolation Chamber (SICE) contains several devices handled by a personal computer (PC), it is able to get the required data to calculate the absorbed dose due to Beta radiation. The main functions of the system are: a) Measures the ionization current or charge stored in the extrapolation chamber. b) Adjusts the distance between the plates of the extrapolation chamber automatically. c) Adjust the bias voltage of the extrapolation chamber automatically. d) Acquires the data of the temperature, atmospheric pressure, relative humidity of the environment and the voltage applied between the plates of the extrapolation chamber. e) Calculates the effective area of the plates of the extrapolation chamber and the real distance between them. f) Stores all the obtained information in hard disk or diskette. A comparison between the desired distance and the distance in the dial of the extrapolation chamber, show us that the resolution of the system is of 20 ?m. The voltage can be changed between -399.9 V and +399.9 V with an error of less the 3 % with a resolution of 0.1 V. These uncertainties are between the accepted limits to be used in the determination of the absolute absorbed dose due to beta radiation. (Author)

1995-01-01

182

Nonparametric reconstruction of the cosmic expansion with local regression smoothing and simulation extrapolation  

CERN Document Server

In this work we present a nonparametric approach, which works on minimal assumptions, to reconstruct the cosmic expansion of the Universe. We propose to combine a locally weighted scatterplot smoothing method and a simulation-extrapolation method. The first one (Loess) is a nonparametric approach that allows to obtain smoothed curves with no prior knowledge of the functional relationship between variables nor of the cosmological quantities. The second one (Simex) takes into account the effect of measurement errors on a variable via a simulation process. For the reconstructions we use as raw data the Union2.1 Type Ia Supernovae compilation, as well as recent Hubble parameter measurements. This work aims to illustrate the approach, which turns out to be a self-sufficient technique in the sense we do not have to choose anything by hand. We examine the details of the method, among them the amount of observational data needed to perform the locally weighted fit which will define the robustness of our reconstructio...

Montiel, Ariadna; Sendra, Irene; Escamilla-Rivera, Celia; Salzano, Vincenzo

2014-01-01

183

Energy confinement scaling and the extrapolation to ITER  

International Nuclear Information System (INIS)

The fusion performance of ITER is predicted using three different techniques; statistical analysis of the global energy confinement data, a dimensionless physics parameter similarity method and the full 1-D modeling of the plasma profiles. Although the three methods give overlapping predictions for the performance of ITER, the confidence interval of all of the techniques is still quite wide

1997-06-09

184

Melting of "non-magic" argon clusters and extrapolation to the bulk limit  

Science.gov (United States)

The melting of argon clusters ArN is investigated by applying a parallel-tempering Monte Carlo algorithm for all cluster sizes in the range from 55 to 309 atoms. Extrapolation to the bulk gives a melting temperature of 85.9 K in good agreement with the previous value of 88.9 K using only Mackay icosahedral clusters for the extrapolation [E. Pahl, F. Calvo, L. Ko?i, and P. Schwerdtfeger, "Accurate melting temperatures for neon and argon from ab initio Monte Carlo simulations," Angew. Chem., Int. Ed. 47, 8207 (2008)]. Our results for argon demonstrate that for the extrapolation to the bulk one does not have to restrict to magic number cluster sizes in order to obtain good estimates for the bulk melting temperature. However, the extrapolation to the bulk remains a problem, especially for the systematic selection of suitable cluster sizes.

Senn, Florian; Wiebke, Jonas; Schumann, Ole; Gohr, Sebastian; Schwerdtfeger, Peter; Pahl, Elke

2014-01-01

185

Design for low dose extrapolation of carcinogenicity data. Technical report No. 24  

Energy Technology Data Exchange (ETDEWEB)

Parameters for modelling dose-response relationships in carcinogenesis models were found to be very complicated, especially for distinguishing low dose effects. The author concluded that extrapolation always bears the danger of providing misleading information. (PCS)

Wong, S C

1979-06-01

186

Loop integration results using numerical extrapolation for a non-scalar integral  

International Nuclear Information System (INIS)

Loop integration results have been obtained using numerical integration and extrapolation. An extrapolation to the limit is performed with respect to a parameter in the integrand which tends to zero. Results are given for a non-scalar four-point diagram. Extensions to accommodate loop integration by existing integration packages are also discussed. These include: using previously generated partitions of the domain and roundoff error guards

2004-11-21

187

Loop integration results using numerical extrapolation for a non-scalar integral  

CERN Document Server

Loop integration results have been obtained using numerical integration and extrapolation. An extrapolation to the limit is performed with respect to a parameter in the integrand which tends to zero. Results are given for a non-scalar four-point diagram. Extensions to accommodate loop integration by existing integration packages are also discussed. These include: using previously generated partitions of the domain and roundoff error guards.

Doncker, E; Fujimoto, J; Yuasa, F; Kaugars, K; Cucos, L; Van Voorst, J

2004-01-01

188

EXTRAPOLATING PHOTOLYSIS RATES FROM THE LABORATORY TO THE ENVIRONMENT  

Science.gov (United States)

The importance of environmental photolysis of pesticides and other xenobiotics has been realized in the last decade and methods for assessing these processes are continually being improved. The general goal has been to develop quantitative laboratory procedures that can be used t...

189

Extrapolated ranges and stopping cross-sections for alpha particles  

Energy Technology Data Exchange (ETDEWEB)

The stopping power and ranges of alpha particles (2.0 to 4.75 MeV) in liquid n-pentane, n-hexane and benzene have been measured by the indirect method to a precision of better than 2.5% for ranges and 4% for stopping powers. Comparison of the results with the stopping powers of these materials in gaseous phase shows that liquids have lower stopping powers than their vapours.

Rezvani, M.; Watt, D.E.

1984-07-01

190

Extrapolated ranges and stopping cross-sections for alpha particles  

International Nuclear Information System (INIS)

The stopping power and ranges of alpha particles (2.0 to 4.75 MeV) in liquid n-pentane, n-hexane and benzene have been measured by the indirect method to a precision of better than 2.5% for ranges and 4% for stopping powers. Comparison of the results with the stopping powers of these materials in gaseous phase shows that liquids have lower stopping powers than their vapours. (author)

1984-01-01

191

Costs of multiple sclerosis - extrapolation of Czech data to Polish patients.  

Science.gov (United States)

Aims: To estimate the direct and indirect costs associated with disability due to multiple sclerosis (MS) in Poland. Methods: Recently a cost-of-illness study was conducted in the Czech Republic, involving 909 patients with different levels of disability (the COMS study). Data on resource use from this trial was extrapolated to Polish patients and combined with Polish unit costs in 2012. The mean annual costs from societal and payers perspective were calculated for patients according to EDSS. Results: The estimated mean annual cost per patient with MS from a societal perspective ranges from 6970 EUR to 26,791 EUR. Indirect costs (production loss due to early retirement, sick-leave and informal care) cover up to 70% of total costs. Conclusions: With an estimated 40-60,000 patients with MS in Poland, the disease poses a high economic burden. Indirect costs have a substantial share in these costs. A high-quality prospective study on costs is needed. PMID:24702130

Szmur?o, Daria; Fundament, Tomasz; Ziobro, Maciej; Kruntorádová, Klára; Doležal, Tomáš; G?ogowski, Cezary

2014-06-01

192

Skeletal 212Pb retention following 224Ra injection: extrapolation of animal data to adult humans  

International Nuclear Information System (INIS)

Two methods of interspecies extrapolation, one based on a correlation of skeletal 212Pb/224Ra with body weight, the other based on the mechanistic relationship between skeletal 212Pb/224Ra and reciprocal bone surface-to-volume ratio, lead to the conclusion that the retention of 212Pb in the adult human skeleton is approximately complete a few days after injection. The correlation-based method gives most probable values for 212Pb/224Ra of 1.0 and 1.1 at 2 d and 7 d after injection, compared with values of 1.05 and 1.27 expected at these same times if the retention of 212Pb were complete from the time of injection and if no 212Pb were in the injection solution. The range of values corresponding to one geometric standard error on either side of the most probable value is 0.87 to 1.21 at 2 d post-injection. With the method based on the reciprocal bone surface-to-volume ratio, the best estimate of 212Pb/224Ra at 2 d after injection is 0.88, equal to the value observed in young adult beagles. An alternative interpretation of the results of this latter method leads to the conclusion that retention is complete, with 212Pb/224Ra equal to 1.0 for a 212Pb-free injection solution and 1.1 for a solution containing 212Pb in secular equilibrium with 224Ra. This work, which uses 224Ra daughter product retention data from mice, rats and dogs following 224Ra injection, provides a scientific foundation for retention assumptions made in the calculation of mean skeletal dose for adult humans. There now appear to be few uncertainties in these latter dose values, stemming from inaccurate retention assumptions; but substantial uncertainties remain in the mean skeletal dose values for juveniles and in the endosteal tissue doses regardless of age

1988-01-01

193

Rapid screening of hazard (RASH) based on maximum use of biological data and minimum use of extrapolation models  

Energy Technology Data Exchange (ETDEWEB)

Traditional methods for evaluation of human health effects are based on identification of the toxic agent, selection of a toxicological study judged to be a suitable analogue for man, analysis of the experimental dose response, incorporation of safety factors, and scaling of the dose and response values to be predictive for humans exposed to untested pollutants or under untested conditions. This method of absolute decision making derives from expert committees and regulatory standards for protection of human health. This work will describe how new relative methods can be used to supplement absolute methods used by the Environmental Protection Agency (EPA) to set regulatory standards and performance guidelines. Relative decision making uses many potency comparisons between various biological tests and minimizes the use of mathematical models commonly used to extrapolate dose and response metrics from past experience to future concerns. 10 refs., 2 figs., 5 tabs.

Jones, T.D.; Glass, L.R.; Easterly, C.E.; Owen, B.A.

1987-01-01

194

Data-driven scale extrapolation: estimating yearly discharge for a large region by small sub-basins  

Science.gov (United States)

Large-scale hydrological models and land surface models are so far the only tools for assessing current and future water resources. Those models estimate discharge with large uncertainties, due to the complex interaction between climate and hydrology, the limited availability and quality of data, as well as model uncertainties. A new purely data-driven scale-extrapolation method to estimate discharge for a large region solely from selected small sub-basins, which are typically 1-2 orders of magnitude smaller than the large region, is proposed. Those small sub-basins contain sufficient information, not only on climate and land surface, but also on hydrological characteristics for the large basin. In the Baltic Sea drainage basin, best discharge estimation for the gauged area was achieved with sub-basins that cover 5% of the gauged area. There exist multiple sets of sub-basins whose climate and hydrology resemble those of the gauged area equally well. Those multiple sets estimate annual discharge for the gauged area consistently well with 6 % average error. The scale-extrapolation method is completely data-driven; therefore it does not force any modelling error into the prediction. The multiple predictions are expected to bracket the inherent variations and uncertainties of the climate and hydrology of the basin.

Gong, L.

2014-01-01

195

Application of the largest Lyapunov exponent and non-linear fractal extrapolation algorithm to short-term load forecasting  

International Nuclear Information System (INIS)

Highlights: ? The maximal predictive step size is determined by the largest Lyapunov exponent. ? A proper forecasting step size is applied to load demand forecasting. ? The improved approach is validated by the actual load demand data. ? Non-linear fractal extrapolation method is compared with three forecasting models. ? Performance of the models is evaluated by three different error measures. - Abstract: Precise short-term load forecasting (STLF) plays a key role in unit commitment, maintenance and economic dispatch problems. Employing a subjective and arbitrary predictive step size is one of the most important factors causing the low forecasting accuracy. To solve this problem, the largest Lyapunov exponent is adopted to estimate the maximal predictive step size so that the step size in the forecasting is no more than this maximal one. In addition, in this paper a seldom used forecasting model, which is based on the non-linear fractal extrapolation (NLFE) algorithm, is considered to develop the accuracy of predictions. The suitability and superiority of the two solutions are illustrated through an application to real load forecasting using New South Wales electricity load data from the Australian National Electricity Market. Meanwhile, three forecasting models: the gray model, the seasonal autoregressive integrated moving average approach and the support vector machine method, which received high approval in STLF, are selected to compare with the NLFE algorithm. Comparison results also show that the NLFE model is outstanding, effective, practical and feasible.

2012-01-01

196

Generalized empirical equation for the extrapolated range of electrons in elemental and compound materials  

International Nuclear Information System (INIS)

The extrapolated range Rex of electrons is useful for various purposes in research and in the application of electrons, for example, in polymer modification, electron energy determination and estimation of effects associated with deep penetration of electrons. A number of works have used empirical equations to express the extrapolated range for some elements. In this work a generalized empirical equation, very simple and accurate, in the energy region 0.3 keV - 50 MeV is proposed. The extrapolated range for elements, in organic or inorganic molecules and compound materials, can be well expressed as a function of the atomic number Z or two empirical parameters Zm for molecules and Zc for compound materials instead of Z. (author)

1999-03-01

197

Windtunnel Rebuilding and Extrapolation to Flight at Transsonic Speed for ExoMars  

Science.gov (United States)

The static as well as the dynamic behaviour of the EXOMARS vehicle in the transonic velocity regime has been investigated experimentally by the Supersonic and Hypersonic Technology Department of DLR in order to investigate the behaviour prior to parachute opening. Since the experimental work was performed in air, a numerical extrapolation to flight by means of CFD is necessary. At low supersonic speed this extrapolation to flight was performed by the Spacecraft Department of the Institute of Flow Technology of DLR employing the CFD code TAU. Numerical as well as experimental results for the wind tunnel test at Mach 1.2 will be compared and discussed for three different angles of attack.

Fertig, M.; Neeb, D.; Gülhan, A.

2011-08-01

198

Evaluation of time extrapolation factors based on the database RepDose  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In chemical risk assessment for many substances only short-term animal studies are available for the evaluation of long-term human exposure. Therefore usually extrapolation factors (EF) are used to extrapolate NOAELs from existing short-term studies to NOAELs for long term exposure. In this report time EFs are derived, based on NOEL/C or LOEL/C ratios (short term N(L)OEL/long term N(L)OEL) from the large datasets of the database RepDose (www.fraunhofer-repdose.de) on repeated dose toxicity fo...

2011-01-01

199

Primary standardisation of Sm-153 by a 4??-? coincidence counting efficiency extrapolation technique  

International Nuclear Information System (INIS)

Sm-153 is the basis of the Quadramet radiopharmaceutical used for the relief of pain due to osteoblastic skeletal metastases (or tumour deposits in the bone). To provide confidence in its use, there is a requirement for primary standardisation of the Sm-153 activity. Primary standardisation of a radionuclide refers to the establishment of a standard measurement procedure for determining the absolute activity of a sample of the radionuclide. Results from the new procedure are usually compared internationally to verify accuracy. In this way the primary standard gains international acceptance and can then be quoted as a legal national standard. There is no single set of apparatus or procedure which can determine the activity of all radioactive species. Rather, the method developed will depend on the unique decay scheme of the selected isotope. In the case of Sm-153, radioactive decay is via beta emission to Eu-153 which is stable. The half-life is 46.3 hrs. The decay scheme is complex with 16 known branches. Most of the beta decays (> 99 %), are via high energy branches which have end point energies within the range 635 to 809 keV. Following beta emission, relaxation to the Eu-153 ground state occurs via gamma ray emission. The most probabilistic emission is a 103.12 keV photon (28.5 %). The almost coincident emission of the beta particle and 103.12 keV photon form the basis of the primary measurement procedure used to standardise this radionuclide. The procedure is known as 4??-? Coincidence Counting Efficiency Extrapolation Technique. Details of the methodology used along with results obtained will be presented. In addition to primary standardisation, a High Purity germanium gamma ray spectrometer was used to measure the Sm-153 gamma-ray emission probabilities

2003-08-17

200

Slow Neutron Flux Extrapolation Distances in R-5 and Cirus Reactors.  

Science.gov (United States)

In order to calculate the core reactivity, fuel channel power outputs and neutron flux levels in the R-5 reactor at Trombay, axial flux extrapolation distances are required. For this, an analysis is carried out considering the reactor core as a two region...

Kanchi S S. Sankaranarayanan N. Veeraraghavan

1976-01-01

 
 
 
 
201

DEMO ampersand commercial fusion reactors extrapolated from the ITER and advanced physics ampersand materials data bases  

International Nuclear Information System (INIS)

The characteristics of demonstration (DEMO) reactors that could be conservatively extrapolated from the data base that will be provided by ITER and its supporting R ampersand D and from a data base supplemented by advanced physics and advanced materials R ampersand D programs are identified

1994-11-01

202

Scaling and chiral extrapolation of pion mass and decay constant with maximally twisted mass QCD  

International Nuclear Information System (INIS)

We present an update of the results for pion mass and pion decay constant as obtained by the ETM collaboration in large scale simulations with maximally twisted mass fermions and two mass degenerate flavours of light quarks. We discuss the continuum, chiral and infinite volume extrapolation of these quantities as well as the extraction of low energy constants, and investigate possible systematic uncertainties. (orig.)

2008-07-14

203

Potential Hydraulic Modelling Errors Associated with Rheological Data Extrapolation in Laminar Flow  

Energy Technology Data Exchange (ETDEWEB)

The potential errors associated with the modelling of flows of non-Newtonian slurries through pipes, due to inadequate rheological models and extrapolation outside of the ranges of data bases, are demonstrated. The behaviors of both dilatant and pseudoplastic fluids with yield stresses, and the errors associated with treating them as Bingham plastics, are investigated.

Shadday, Martin A., Jr.

1997-03-20

204

Infinite Volume Extrapolations of Finite Cluster Calculations, ---How Correct are These?  

CERN Document Server

Extrapolations of numerical data obtained from finite cluster calculations to the infinite volume limit can often give incorrect results. We discuss four separate cases: (a) the intensity of the lowest two-photon absorption in the infinite polyene, (b) bond alternation in the infinite polyene, (c) Cooper type pairing in the simple Hubbard model, and (d) pairing within the extended Hubbard model.

Mazumdar, S; Guo, D; Ung, K C; Gammel, J T

1993-01-01

205

Extrapolating toxic effects on individuals to the population level: the role of dynamic energy budgets.  

Science.gov (United States)

The interest of environmental management is in the long-term health of populations and ecosystems. However, toxicity is usually assessed in short-term experiments with individuals. Modelling based on dynamic energy budget (DEB) theory aids the extraction of mechanistic information from the data, which in turn supports educated extrapolation to the population level. To illustrate the use of DEB models in this extrapolation, we analyse a dataset for life cycle toxicity of copper in the earthworm Dendrobaena octaedra. We compare four approaches for the analysis of the toxicity data: no model, a simple DEB model without reserves and maturation (the Kooijman-Metz formulation), a more complex one with static reserves and simplified maturation (as used in the DEBtox software) and a full-scale DEB model (DEB3) with explicit calculation of reserves and maturation. For the population prediction, we compare two simple demographic approaches (discrete time matrix model and continuous time Euler-Lotka equation). In our case, the difference between DEB approaches and population models turned out to be small. However, differences between DEB models increased when extrapolating to more field-relevant conditions. The DEB3 model allows for a completely consistent assessment of toxic effects and therefore greater confidence in extrapolating, but poses greater demands on the available data. PMID:20921051

Jager, Tjalling; Klok, Chris

2010-11-12

206

Short-Range Forecasting through Extrapolation of Satellite Imagery Patterns. Part II. Testing Motion Vector Techniques.  

Science.gov (United States)

An effort is underway at Air Force Geophysics Laboratory to develop automated procedures to make short-range (0-6 hr) terminal weather forecasts using GOES imagery data. A simple approach is to extrapolate the cloud patterns using motion vectors derived f...

H. S. Muench

1979-01-01

207

Photon neutrino-production in a chiral EFT for nuclei and extrapolation to $E_{\  

CERN Document Server

We carry out a series of studies on pion and photon productions in neutrino/electron/photon--nucleus scatterings. The low energy region is investigated by using a chiral effective field theory for nuclei. The results for the neutral current induced photon production ($\\gamma$-NCP) are then extrapolated to neutrino energy $E_{\

Zhang, Xilin

2013-01-01

208

Kinetic energy of solid neon by Monte Carlo with improved Trotter- and finite-size extrapolation  

CERN Document Server

The kinetic energy of solid neon is calculated by a path-integral Monte Carlo approach with a refined Trotter- and finite-size extrapolation. These accurate data present significant quantum effects up to temperature T=20 K. They confirm previous simulations and are consistent with recent experiments.

Cuccoli, A; Macchi, A; Tognetti, V; Vaia, R; Cuccoli, Alessandro; Pedrolli, Gaia; Macchi, Alessandro; Tognetti, Valerio; Vaia, Ruggero

1997-01-01

209

Benchmarks of improved complete basis set extrapolation schemes designed for standard CCSD(T) atomization energies  

Science.gov (United States)

Simple modifications of complete basis set extrapolation formulas chosen from the literature are examined with respect to their abilities to reproduce a diverse set of 183 reference atomization energies derived primarily from very large basis set standard, frozen core coupled-cluster singles, doubles plus perturbative triples (CCSD(T)) with the aug-cc-pVnZ basis sets. This reference set was augmented with a few larger chemical systems treated with explicitly correlated CCSD(T)-F12b using a quadruple zeta quality basis set followed by extrapolation to complete basis set limit. Tuning the extrapolation formula parameters for the present reference set resulted in substantial reductions in the error metrics. In the case of the best performing approach, the aVnZ extrapolated results are equivalent to or better than results obtained from raw aV(n + 3)Z basis set calculations. To the extent this behavior holds for molecules outside the reference set, it represents an improvement of at least one basis set level over the original formulations and a further significant reduction in the amount of computer time needed to accurately approximate the basis set limit.

Feller, David

2013-02-01

210

Benchmarks of improved complete basis set extrapolation schemes designed for standard CCSD(T) atomization energies.  

Science.gov (United States)

Simple modifications of complete basis set extrapolation formulas chosen from the literature are examined with respect to their abilities to reproduce a diverse set of 183 reference atomization energies derived primarily from very large basis set standard, frozen core coupled-cluster singles, doubles plus perturbative triples (CCSD(T)) with the aug-cc-pVnZ basis sets. This reference set was augmented with a few larger chemical systems treated with explicitly correlated CCSD(T)-F12b using a quadruple zeta quality basis set followed by extrapolation to complete basis set limit. Tuning the extrapolation formula parameters for the present reference set resulted in substantial reductions in the error metrics. In the case of the best performing approach, the aVnZ extrapolated results are equivalent to or better than results obtained from raw aV(n + 3)Z basis set calculations. To the extent this behavior holds for molecules outside the reference set, it represents an improvement of at least one basis set level over the original formulations and a further significant reduction in the amount of computer time needed to accurately approximate the basis set limit. PMID:23444993

Feller, David

2013-02-21

211

Establishing macroecological trait datasets: digitalization, extrapolation, and validation of diet preferences in terrestrial mammals worldwide  

DEFF Research Database (Denmark)

Ecological trait data are essential for understanding the broad-scale distribution of biodiversity and its response to global change. For animals, diet represents a fundamental aspect of speciesâ?? evolutionary adaptations, ecological and functional roles, and trophic interactions. However, the importance of diet for macroevolutionary and macroecological dynamics remains little explored, partly because of the lack of comprehensive trait datasets. We compiled and evaluated a comprehensive global dataset of diet preferences of mammals (â??MammalDIETâ?). Diet information was digitized from two global and cladewide data sources and errors of data entry by multiple data recorders were assessed. We then developed a hierarchical extrapolation procedure to fill-in diet information for species with missing information. Missing data were extrapolated with information from other taxonomic levels (genus, other species within the same genus, or family) and this extrapolation was subsequently validated both internally (with a jack-knife approach applied to the compiled species-level diet data) and externally (using independent species-level diet information from a comprehensive continentwide data source). Finally, we grouped mammal species into trophic levels and dietary guilds, and their species richness as well as their proportion of total richness were mapped at a global scale for those diet categories with good validation results. The success rate of correctly digitizing data was 94%, indicating that the consistency in data entry among multiple recorders was high. Data sources provided species-level diet information for a total of 2033 species (38% of all 5364 terrestrial mammal species, based on the IUCN taxonomy). For the remaining 3331 species, diet information was mostly extrapolated from genus-level diet information (48% of all terrestrial mammal species), and only rarely from other species within the same genus (6%) or from family level (8%). Internal and external validation showed that: (1) extrapolations were most reliable for primary food items; (2) several diet categories (â??Animalâ?, â??Mammalâ?, â??Invertebrateâ?, â??Plantâ?, â??Seedâ?, â??Fruitâ?, and â??Leafâ?) had high proportions of correctly predicted diet ranks; and (3) the potential of correctly extrapolating specific diet categories varied both within and among clades. Global maps of species richness and proportion showed congruence among trophic levels, but also substantial discrepancies between dietary guilds. MammalDIET provides a comprehensive, unique and freely available dataset on diet preferences for all terrestrial mammals worldwide. It enables broad-scale analyses for specific trophic levels and dietary guilds, and a first assessment of trait conservatism in mammalian diet preferences at a global scale. The digitalization, extrapolation and validation procedures could be transferable to other trait data and taxa.

Kissling, W. Daniel; Dalby, Lars

2014-01-01

212

Data-based discharge extrapolation: estimating annual discharge for a partially gauged large river basin from its small sub-basins  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Large-scale hydrological models and land surface models are by far the only tools for accessing future water resources in climate change impact studies. Those models estimate discharge with large uncertainties, due to the complex interaction between climate and hydrology, the limited quality and availability of data, as well as model uncertainties. A new purely data-based scale-extrapolation method is proposed, to estimate water resources for a large basin solely from selected small su...

2012-01-01

213

Terahertz in-line digital holography of dragonfly hindwing: amplitude and phase reconstruction at enhanced resolution by extrapolation  

CERN Document Server

We report here on terahertz (THz) digital holography on a biological specimen. A continuous-wave (CW) THz in-line holographic setup was built based on a 2.52 THz CO2 pumped THz laser and a pyroelectric array detector. We introduced novel statistical method of obtaining true intensity values for the pyroelectric array detector's pixels. Absorption and phase-shifting images of a dragonfly's hind wing were reconstructed simultaneously from single in-line hologram. Furthermore, we applied phase retrieval routines to eliminate twin image and enhanced the resolution of the reconstructions by hologram extrapolation beyond the detector area. The finest observed features are 35 {\\mu}m width cross veins.

Rong, Lu; Wang, Dayong; Zhou, Xun; Huang, Haochong; Li, Zeyu; Wang, Yunxin

2014-01-01

214

Determination of the activity concentration of a 125I solution by X-(X,?) coincidence counting and an efficiency extrapolation curve  

Science.gov (United States)

The activity concentration of a 125I solution has been measured by a X-(X, ?) coincidence counting method and an extrapolation of a linear function of the associated efficiency curve. Two thin NaI(Tl) scintillation detectors were mounted on a horizontal rail, and the efficiency curve was obtained by systematically changing the distance between the source and movable detectors. All sum-coincidence events were recorded with a counting window set between 10 and 100 keV. The disintegration rate was measured and the data expressed in terms of a linear function so that the activity concentration of 125I could be determined by extrapolation. A high-purity germanium detector (Ortec Gamma-X) was also used to determine an emission probability of 0.0668 ± 0.0013 (1 ?) for the 35.5 keV gamma ray of 125I.

Iwahara, A.; Marechal, M. H. H.; Da Silva, C. J.; Poledna, R.

1990-01-01

215

A cluster based V. A. I. method for distribution load forecasting  

Energy Technology Data Exchange (ETDEWEB)

A new method of extrapolating load growth for distribution planning is described. The method combines two previously used methods of extrapolation in a manner in which each reinforces the other. Tests reveal the new method to be more accurate and dependable than other extrapolation procedures. The technique is described, including a flowchart for computer implementation.

Willis, H.L.; Tram, H.

1983-08-01

216

EVALUATION OF THE ADEQUACY OF THE WIND SPEED EXTRAPOLATION LAWS FOR TWO DIFFERENT ROUGHNESS METEOROLOGICAL SITES  

Directory of Open Access Journals (Sweden)

Full Text Available Increasing knowledge on wind shear models to strengthen their reliability appears as a crucial issue, markedly for energy investors to accurately predict the average wind speed at different turbine hub heights and thus the expected wind energy output. This is particularly helpful during the feasibility study to abate the costs of a wind power project. The extrapolation laws were found to provide the finest representation of the wind speed according to heights, thus avoiding installation of tall towers, or even more expensive devices such as LIDAR or SODAR. The proposed models are based on theories that determine the vertical wind profile from implicit relationships. However, these empirical extrapolation formulas have been developed for specific meteorological conditions and appropriate sites for wind turbines; reason that several studies have been made by various authors to determine the best suited formula to their own conditions. This study is aimed at proceeding the research issue addressed within a previous study, where some extrapolation models were tested and compared by extrapolating the energy resources at different heights. However, comparable results are returned by the power law and the log law which indeed proved to be preferable. In this context, this study deals the assessment of several wind speed extrapolation laws (six laws, by comparing the analytical results obtained with real data for two different meteorological Sites, different roughness, different altitudes and different measurement periods. The first site studied is an extremely rough site with daily measurements of March 2007, wind speed measurements are available at four different heights of Gantour/Gao site, obtained by the water, energy and environment company Senegal. The second site studied is a feeble rough site with monthly measurements for 2005, wind speed measurements are available at three different heights of Kuujjuarapik Site obtained by Hydro-Quebec Energy Helimax Canada. The study aims to determine the effectiveness and concordance between the extrapolation laws and the real measured data. The results show that the adjusted law is efficiently adequate for an extremely rough site and the modified laws with two other laws are efficiently adequate for a feeble rough site. The experimental results and numerical calculations exploited for the evaluation of the Weibull parameters fall the shape factors k greater than 9. The increase in altitude often causes an increase in the Weibull parameters values, however, our results show that the shape factor k can take lower values to those established in the reference altitude.

Dalila Khalfa

2014-01-01

217

Response characteristics of an extrapolation chamber made at IPEN to X radiation  

International Nuclear Information System (INIS)

Measurements of absorbed dose rates produced by beta or low energy X radiation are often difficult to obtain with accuracy. The recommended instruments for these measurements are extrapolation chambers. A plane parallel ionization chamber of variable air volume of this type was designed and constructed; its performance was tested in the radiation standard beams of the Calibration Laboratory of Sao Paulo. The performance of the chamber was studied in relation to its response linearity and energy dependence. Extrapolation curves were initially obtained for X-rays (25 and 50kV), varying the interelectrode distance between 0.2 and 1.0 mm and keeping the electric field constant at 10 V/mm. The calibration factors were obtained. The obtained results are comparable to those of commercial plane parallel chambers

1994-10-01

218

Use of Si semiconductor detectors as an extrapolation chamber for measurement of absorbed beta-radiation  

International Nuclear Information System (INIS)

Investigated is the possibility of using silicon semiconductor detectors as a solid-state extrapolation ionizing chamber with plane electrodes for measuring the absorbed dose produced by 90Sr + 90Y and 204Te beta sources. Measured are the losses of energy of the beta radiation depending on the depth of the sensitive layer for 18 and 10 mm distances between the source and detector. Assessment of contribution of gamma radiation of the beta sources has revealed that it amounts to 0.145 keV/c for the 1 MeV gamma quanta energy. The advantages of the beta dosimeters are: the extrapolation principle of operation, wide range of absorbed doses, low sensitivity to the gamma background and magnetic fields, fast response (about 10-9 s), and possibility of use under field conditions. These advantages determine the promises in their use in dosimetry of electron and beta radiations

1977-01-01

219

Electric form factors of the octet baryons from lattice QCD and chiral extrapolation  

International Nuclear Information System (INIS)

We apply a formalism inspired by heavy baryon chiral perturbation theory with finite-range regularization to dynamical 2+1-flavor CSSM/QCDSF/UKQCD Collaboration lattice QCD simulation results for the electric form factors of the octet baryons. The electric form factor of each octet baryon is extrapolated to the physical pseudoscalar masses, after finite-volume corrections have been applied, at six fixed values of Q2 in the range 0.2-1.3 GeV2. The extrapolated lattice results accurately reproduce the experimental form factors of the nucleon at the physical point, indicating that omitted disconnected quark loop contributions are small. Furthermore, using the results of a recent lattice study of the magnetic form factors, we determine the ratio ?pGEp/GMp. This quantity decreases with Q2 in a way qualitatively consistent with recent experimental results.

2014-01-01

220

Electric form factors of the octet baryons from lattice QCD and chiral extrapolation  

Energy Technology Data Exchange (ETDEWEB)

We apply a formalism inspired by heavy baryon chiral perturbation theory with finite-range regularization to dynamical 2+1-flavor CSSM/QCDSF/UKQCD Collaboration lattice QCD simulation results for the electric form factors of the octet baryons. The electric form factor of each octet baryon is extrapolated to the physical pseudoscalar masses, after finite-volume corrections have been applied, at six fixed values of Q{sup 2} in the range 0.2-1.3 GeV{sup 2}. The extrapolated lattice results accurately reproduce the experimental form factors of the nucleon at the physical point, indicating that omitted disconnected quark loop contributions are small. Furthermore, using the results of a recent lattice study of the magnetic form factors, we determine the ratio ?{sub p}G{sub E}{sup p}/G{sub M}{sup p}. This quantity decreases with Q{sup 2} in a way qualitatively consistent with recent experimental results.

Shanahan, P.E.; Thomas, A.W.; Young, R.D.; Zanotti, J.M. [Adelaide Univ., SA (Australia). ARC Centre of Excellence in Particle Physics at the Terascale and CSSM; Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Nakamura, Y. [RIKEN Advanced Institute for Computational Science, Kobe, Hyogo (Japan); Pleiter, D. [Forschungszentrum Juelich (Germany). JSC; Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Div.; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Stueben, H. [Hamburg Univ. (Germany). Regionales Rechenzentrum; Collaboration: CSSM and QCDSF/UKQCD Collaborations

2014-03-15

 
 
 
 
221

Minimization of edge effects in images using an extrapolated discrete wavelet transform  

Science.gov (United States)

The discrete wavelet transform(DWT) is a tool extensively used in image processing algorithms. It can be used to decorrelate information from the original image, which can thus help in compressing the data for storage, transmission or other post-processing purposes. However, the finite nature of such images gives rise to edge artifacts in the reconstructed data. A commonly used technique to overcome this problem is a symmetric extension of the image, which can preserve zeroth order continuity in the data. This still produces undesirable edge artifacts in derivatives and subsampled versions of the image. In this paper we present an extension to Williams and Amaratunga's work of extrapolating the image data using a polynomial extrapolation technique before performing the forward or inverse DWT for biorthogonal wavelets. Comaparitive results of reconstructed data, with individual subband reconstruction as well as using the embedded zerotree coding (EZC) scheme, are also presented for both the aforementioned techniques.

Nath, Sumit K.; Dubois, Eric

2001-11-01

222

Electric form factors of the octet baryons from lattice QCD and chiral extrapolation  

CERN Document Server

We apply a formalism inspired by heavy baryon chiral perturbation theory with finite-range regularization to dynamical $2+1-$flavor CSSM/QCDSF/UKQCD Collaboration lattice QCD simulation results for the electric form factors of the octet baryons. The electric form factor of each octet baryon is extrapolated to the physical pseudoscalar masses, after finite-volume corrections have been applied, at six fixed values of $Q^2$ in the range 0.2-1.3 GeV$^2$. The extrapolated lattice results accurately reproduce the experimental form factors of the nucleon at the physical point, indicating that omitted disconnected quark loop contributions are small. Furthermore, using the results of a recent lattice study of the magnetic form factors, we determine the ratio $\\mu_p G^p_E/G^p_M$. This quantity decreases with $Q^2$ in a way qualitatively consistent with recent experimental results.

Shanahan, P E; Young, R D; Zanotti, J M; Horsley, R; Nakamura, Y; Pleiter, D; Rakow, P E L; Schierholz, G; Stüben, H

2014-01-01

223

Iterative Solution of the Ornstein-Zernike Equation with Various Closures Using Vector Extrapolation  

CERN Document Server

The solution of the Ornstein-Zernike equation with various closure approximations is studied. This problem is rewritten as an integral equation that can be solved iteratively on a grid. The convergence of the fixed point iterations is relatively slow. We consider transformations of the sequence of solution vectors using non-linear sequence transformations, so-called vector extrapolation processes. An example is the vector J transformation. The transformed vector sequences turn out to converge considerably faster than the original sequences.

Homeier, H H H; Krienke, H; Homeier, Herbert H. H.; Rast, Sebastian; Krienke, Hartmut

1995-01-01

224

Self-Similar Extrapolation for the Law of Acoustic Emission Before Failure of Heterogeneous Materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Acoustic emission before the failure of heterogeneous materials is studied as a function of applied hydrostatic pressure. A formula for the energy release is suggested, which is valid in the whole diapason of pressures, from zero to the critical pressure of rupture. This formula is obtained by employing the extrapolation technique of the self-similar approximation theory. The result is fitted to experiment in order to demonstrate the correct general behaviour of the obtained...

Moura, A.; Yukalov, V. I.

2003-01-01

225

Coherent microscopy at resolution beyond diffraction limit using post-experimental data extrapolation  

International Nuclear Information System (INIS)

Conventional microscopic records represent intensity distributions whereby local sample information is mapped onto local information at the detector. In coherent microscopy, the superposition principle of waves holds; field amplitudes are added, not intensities. This non-local representation is spread out in space and interference information combined with wave continuity allows extrapolation beyond the actual detected data. Established resolution criteria are thus circumvented and hidden object details can retrospectively be recovered from just a fraction of an interference pattern

2013-11-11

226

A surge and choke capable compressor flow model : Validation and extrapolation capability  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Increasingly stringent emissions legislation combined with consumer performance demand, have created the need for complex automotive engines. The control of these complex system rely heavily on control oriented models. Models capable of describing all operating modes of the systems are beneficial, and the models should be easily parametrized and enable extrapolation. A large database of automotive compressor maps is characterized, and used to develop, validate and automatically parametrize a ...

Leufve?n, Oskar; Eriksson, Lars

2013-01-01

227

Charge symmetry breaking from a chiral extrapolation of moments of quark distribution functions  

CERN Document Server

We present a determination, from lattice QCD, of charge symmetry violation in the spin- independent and spin-dependent parton distribution functions of the nucleon. This is done by chirally extrapolating recent QCDSF/UKQCD Collaboration lattice simulations of the first several Mellin moments of the parton distribution functions of octet baryons to the physical point. We find small chiral corrections for the polarized moments, while the corrections are quantitatively significant in the unpolarized case.

Shanahan, P E; Young, R D

2013-01-01

228

Is extrapolation of the safety and efficacy data in one indication to another appropriate for biosimilars?  

Science.gov (United States)

CT-P13, the world's first biosimilar monoclonal antibody to infliximab, was approved for marketing in South Korea for all the six indications of infliximab, which Europe may follow, although the product was tested only in rheumatoid arthritis (RA) with a limited pharmacokinetic comparison in ankylosing spondylitis. However, the extrapolation of the efficacy and safety findings of CT-P13 in RA to the other indications appears scientifically challenging when assessed by the current regulatory requirements. RA is not a sensitive clinical model to detect potential differences between CT-P13 and infliximab, and other mechanisms of action than antagonizing tumor necrosis factor ? appear to be also important, which could be different by the approved indications. Furthermore, the immunogenicity and safety profiles of CT-P13 were not sufficiently characterized in that immunogenicity potential was lowest in RA, which was even further suppressed by the concomitant use of methotrexate. Extrapolation of the safety and efficacy data in one indication to another may be inappropriate for biosimilars unless backed up by strong scientific justification, which may include the mechanistic exposure-relationship approach. Therefore, regulatory agencies need to exercise caution before granting extrapolated indications to biosimilars. PMID:24114449

Lee, Howard

2014-01-01

229

Motion-based prediction explains the role of tracking in motion extrapolation.  

Science.gov (United States)

During normal viewing, the continuous stream of visual input is regularly interrupted, for instance by blinks of the eye. Despite these frequents blanks (that is the transient absence of a raw sensory source), the visual system is most often able to maintain a continuous representation of motion. For instance, it maintains the movement of the eye such as to stabilize the image of an object. This ability suggests the existence of a generic neural mechanism of motion extrapolation to deal with fragmented inputs. In this paper, we have modeled how the visual system may extrapolate the trajectory of an object during a blank using motion-based prediction. This implies that using a prior on the coherency of motion, the system may integrate previous motion information even in the absence of a stimulus. In order to compare with experimental results, we simulated tracking velocity responses. We found that the response of the motion integration process to a blanked trajectory pauses at the onset of the blank, but that it quickly recovers the information on the trajectory after reappearance. This is compatible with behavioral and neural observations on motion extrapolation. To understand these mechanisms, we have recorded the response of the model to a noisy stimulus. Crucially, we found that motion-based prediction acted at the global level as a gain control mechanism and that we could switch from a smooth regime to a binary tracking behavior where the dot is tracked or lost. Our results imply that a local prior implementing motion-based prediction is sufficient to explain a large range of neural and behavioral results at a more global level. We show that the tracking behavior deteriorates for sensory noise levels higher than a certain value, where motion coherency and predictability fail to hold longer. In particular, we found that motion-based prediction leads to the emergence of a tracking behavior only when enough information from the trajectory has been accumulated. Then, during tracking, trajectory estimation is robust to blanks even in the presence of relatively high levels of noise. Moreover, we found that tracking is necessary for motion extrapolation, this calls for further experimental work exploring the role of noise in motion extrapolation. PMID:24036184

Khoei, Mina A; Masson, Guillaume S; Perrinet, Laurent U

2013-11-01

230

J-85 jet engine noise measured in the ONERA S1 wind tunnel and extrapolated to far field  

Science.gov (United States)

Noise from a J-85 turbojet with a conical, convergent nozzle was measured in simulated flight in the ONERA S1 Wind Tunnel. Data are presented for several flight speeds up to 130 m/sec and for radiation angles of 40 to 160 degrees relative to the upstream direction. The jet was operated with subsonic and sonic exhaust speeds. A moving microphone on a 2 m sideline was used to survey the radiated sound field in the acoustically treated, closed test section. The data were extrapolated to a 122 m sideline by means of a multiple-sideline source-location method, which was used to identify the acoustic source regions, directivity patterns, and near field effects. The source-location method is described along with its advantages and disadvantages. Results indicate that the effects of simulated flight on J-85 noise are significant. At the maximum forward speed of 130 m/sec, the peak overall sound levels in the aft quadrant were attentuated approximately 10 dB relative to sound levels of the engine operated statically. As expected, the simulated flight and static data tended to merge in the forward quadrant as the radiation angle approached 40 degrees. There is evidence that internal engine or shock noise was important in the forward quadrant. The data are compared with published predictions for flight effects on pure jet noise and internal engine noise. A new empirical prediction is presented that relates the variation of internally generated engine noise or broadband shock noise to forward speed. Measured near field noise extrapolated to far field agrees reasonably well with data from similar engines tested statically outdoors, in flyover, in a wind tunnel, and on the Bertin Aerotrain. Anomalies in the results for the forward quadrant and for angles above 140 degrees are discussed. The multiple-sideline method proved to be cumbersome in this application, and it did not resolve all of the uncertainties associated with measurements of jet noise close to the jet. The simulation was complicated by wind-tunnel background noise and the propagation of low frequency sound around the circuit.

Soderman, Paul T.; Julienne, Alain; Atencio, Adolph, Jr.

1991-01-01

231

Model of a realistic InP surface quantum dot extrapolated from atomic force microscopy results  

Science.gov (United States)

We report on numerical simulations of a zincblende InP surface quantum dot (QD) on \\text{I}{{\\text{n}}_{0.48}}\\text{G}{{\\text{a}}_{0.52}}\\text{P} buffer. Our model is strictly based on experimental structures, since we extrapolated a three-dimensional dot directly by atomic force microscopy results. Continuum electromechanical, \\vec{k}\\;\\cdot \\;\\vec{p} bandstructure and optical calculations are presented for this realistic structure, together with benchmark calculations for a lens-shape QD with the same radius and height of the extrapolated dot. Interesting similarities and differences are shown by comparing the results obtained with the two different structures, leading to the conclusion that the use of a more realistic structure can provide significant improvements in the modeling of QDs fact, the remarkable splitting for the electron p-like levels of the extrapolated dot seems to prove that a realistic experimental structure can reproduce the right symmetry and a correct splitting usually given by atomistic calculations even within the multiband \\vec{k}\\;\\cdot \\;\\vec{p} approach. Moreover, the energy levels and the symmetry of the holes are strongly dependent on the shape of the dot. In particular, as far as we know, their wave function symmetries do not seem to resemble to any results previously obtained with simulations of zincblende ideal structures, such as lenses or truncated pyramids. The magnitude of the oscillator strengths is also strongly dependent on the shape of the dot, showing a lower intensity for the extrapolated dot, especially for the transition between the electrons and holes ground state, as a result of a relevant reduction of the wave functions overlap. We also compare an experimental photoluminescence spectrum measured on an homogeneous sample containing about 60 dots with a numerical ensemble average derived from single dot calculations. The broader energy range of the numerical spectrum motivated us to perform further verifications, which have clarified some aspects of the experimental results and helped us to develop a suitable model for the spectrum, by assuming a not equiprobable weight from each dot, a model which is extremely consistent with the experimental data.

Barettin, Daniele; De Angelis, Roberta; Prosposito, Paolo; Auf der Maur, Matthias; Casalboni, Mauro; Pecchia, Alessandro

2014-05-01

232

Chiral extrapolations with small sea quark mass data in two-flavor lattice QCD  

CERN Document Server

We present results on the light hadron spectrum and quark mass in two-flavor QCD calculated with small sea quark masses down to $m_{PS}/m_{V}=0.35$. The configurations are generated using the RG improved gauge and tadpole-improved clover quark action at $\\beta=1.8$, where $a^{-1} \\simeq 1$ GeV. Chiral extrapolations are made using not only polynomials and ChPT in the continuum but also formulae of Wilson chiral perturbation theory (WChPT) including $O(a^2)$ chiral breaking terms. We examine the viability of WChPT and its influence on quark masses.

Namekawa, Y; Fukugita, M; Ishikawa, K I; Ishizuka, N; Iwasaki, Y; Kanaya, K; Kaneko, T; Kuramashi, Y; Lesk, V I; Okawa, M; Ukawa, A; Umeda, T; Yoshié, T

2005-01-01

233

QSAR analysis and data extrapolation among mammals in a series of aliphatic alcohols.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Concepts of QSAR analysis and biological similarity models are combined for use in extrapolation of LD50 values after IP application of a series of aliphatic alcohols (C1-C5) to mouse, hamster, rat, and guinea pig and rabbit. It has been found that although close correlation exists between LD50 values after IP and IV applications for mouse and rat, the QSARs obtained with LD50 after IV application are not suitable for a prediction of LD50 values after IP application for rabbit. Different tran...

Tichy?, M.; Trcka, V.; Roth, Z.; Krivucova?, M.

1985-01-01

234

Standardization of beta dose rate using an extrapolation chamber for skin dose measurements  

International Nuclear Information System (INIS)

The calibration of a beta skin dose monitor developed by Electronics Division, BARC was done as a first step to verify its conformity with the international standard ISO 6980-1. An extrapolation chamber was used to standardize the dose rate of a 90Sr- 90Y beta source. Standardization of the beta source was done in terms of dose to skin for calibration of field instruments. Effective area of the source was determined by determining the 50% isodose contours of the GAFCHROMIC films exposed. Field was standardized for various source to surface distances. The paper gives the details of measurement technique, analysis of data and the results. (author)

2010-02-01

235

Characteristics of an extrapolation chamber FWT type EIC.1 in beta radiation fields  

International Nuclear Information System (INIS)

The characteristics of an extrapolation chamber FWT type EIC.1 have been determined to aid its utilisation as a transfer instrument for the characterisation of beta radiation field in terms of absorbed dose in tissue. This detector, made of A-150 tissue-equivalent material, is fitted with a window 7 mg.cm"-"2 thick. It can be used either with ambient air or with a tissue-equivalent gas flow. Some changes have been made to the commercial model (alteration of the variable spacing of the thickness of the cavity, and of the circuit of gas flow) so that it could be used correctly for low energy radiation. (author)

1985-10-07

236

Impact of new collider data on fits and extrapolations of cross sections and slopes  

International Nuclear Information System (INIS)

The latest Collider data are compared with our earlier extrapolations. Fits that include the new data are made. Those for which sigma/sub tot/ grows as log"2(s/s/sub o/) indefinitely give a significantly poorer chi"2 than those for which sigma/sub tot/ eventually levels out. For the proposed SSC energy for the former fits predict sigma/sub tot/(?s = 40 TeV) approx. =200 mb while the latter give sigma/sub tot/(?s = 40 TeV) approx. = 100 mb. 6 refs

1985-06-03

237

Energy extrapolation schemes for adaptive multi-scale molecular dynamics simulations  

Science.gov (United States)

This paper evaluates simple schemes to extrapolate potential energy values using the set of energies and forces extracted from a molecular dynamics trajectory. In general, such a scheme affords the maximum amount of information about a molecular system at minimal computational cost. More specifically, schemes like this are very important in the field of adaptive multi-scale molecular dynamics simulations. In this field, often the computation of potential energy values at certain trajectory points is not required for the simulation itself, but solely for the a posteriori analysis of the simulation data. Extrapolating the values at these points from the available data can save considerable computational time. A set of extrapolation schemes are employed based on Taylor series and central finite difference approximations. The schemes are first tested on the trajectories of molecular systems of varying sizes, obtained at MM and QM level using velocity-Verlet integration with standard simulation time steps. Remarkably good accuracy was obtained with some of the approximations, while the failure of others can be explained in terms of the distinct features of a molecular dynamics trajectory. We have found that, for a Taylor expansion of the potential energy, both a first and a second order truncation exhibit errors that grow with system size. In contrast, the second order central finite difference approximation displays an accuracy that is independent of the size of the system, while giving a very good estimate of the energy, and costing as little as a first order truncation of the Taylor series. A fourth order central finite difference approximation requires more input data, which is not always available in adaptive multi-scale simulations. Furthermore, this approximation gives errors of similar magnitude or larger than its second order counterpart, at standard simulation time steps. This leads to the conclusion that a second order central finite difference approximation is the optimal choice for energy extrapolation from molecular dynamics trajectories. This finding is confirmed in a final application to the analysis of an adaptive multi-scale simulation.

Fleurat-Lessard, Paul; Michel, Carine; Bulo, Rosa E.

2012-08-01

238

CUORE crystal validation runs: results on radioactive contamination and extrapolation to CUORE background  

CERN Document Server

The CUORE Crystal Validation Runs (CCVRs) have been carried out since the end of 2008 at the Gran Sasso National Laboratories, in order to test the performances and the radiopurity of the TeO$_2$ crystals produced at SICCAS (Shanghai Institute of Ceramics, Chinese Academy of Sciences) for the CUORE experiment. In this work the results of the first 5 validation runs are presented. Results have been obtained for bulk contaminations and surface contaminations from several nuclides. An extrapolation to the CUORE background has been performed.

Alessandria, F; Ardito, R; Arnaboldi, C; Avignone, F T; Balata, M; Bandac, I; Banks, T I; Bari, G; Beeman, J W; Bellini, F; Bersani, A; Biassoni, M; Bloxham, T; Brofferio, C; Bryant, A; Bucci, C; Cai, X Z; Canonica, L; Capelli, S; Carbone, L; Cardani, L; Carrettoni, M; Chott, N; Clemenza, M; Cosmelli, C; Cremonesi, O; Creswick, R J; Dafinei, I; Dally, A; De Biasi, A; Decowski, M P; Deninno, M M; de Waard, A; Di Domizio, S; Ejzak, L; Faccini, R; Fang, D Q; Farach, H; Ferri, E; Ferroni, F; Fiorini, E; Foggetta, L; Freedman, S; Frossati, G; Giachero, A; Gironi, L; Giuliani, A; Gorla, P; Gotti, C; Guardincerri, E; Gutierrez, T D; Haller, E E; Han, K; Heeger, K M; Huang, H Z; Ichimura, K; Kadel, R; Kazkaz, K; Keppel, G; Kogler, L; Kolomensky, Y G; Kraft, S; Lenz, D; Li, Y L; Liu, X; Longo, E; Ma, Y G; Maiano, C; Maier, G; Martinez, C; Martinez, M; Maruyama, R H; Moggi, N; Morganti, S; Newman, S; Nisi, S; Nones, C; Norman, E B; Nucciotti, A; Orio, F; Orlandi, D; Ouellet, J; Pallavicini, M; Palmieri, V; Pattavina, L; Pavan, M; Pedretti, M; Pessina, G; Pirro, S; Previtali, E; Rampazzo, V; Rimondi, F; Rosenfeld, C; Rusconi, C; Salvioni, C; Sangiorgio, S; Schaeffer, D; Scielzo, N D; Sisti, M; Smith, A R; Stivanello, F; Taffarello, L; Terenziani, G; Tian, W D; Tomei, C; Trentalange, S; Ventura, G; Vignati, M; Wang, B; Wang, H W; Whitten, C A; Wise, T; Woodcraft, A; Xu, N; Zanotti, L; Zarra, C; Zhu, B X; Zucchelli, S

2011-01-01

239

Magnetic form factors of the octet baryons from lattice QCD and chiral extrapolation  

Energy Technology Data Exchange (ETDEWEB)

We present a 2+1-flavor lattice QCD calculation of the electromagnetic Dirac and Pauli form factors of the octet baryons. The magnetic Sachs form factor is extrapolated at six fixed values of Q{sup 2} to physical pseudoscalar masses and infinite volume using a formulation based on heavy baryon chiral perturbation theory with finite-range regularization. We properly account for omitted disconnected quark contractions using a partially-quenched effective field theory formalism. The results compare well with the experimental form factors of the nucleon and the magnetic moments of the octet baryons.

Shanahan, P.E.; Thomas, A.W.; Young, R.D.; Zanotti, J.M. [Adelaide Univ. (Australia). School of Chemistry and Physics; Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Nakamura, Y. [RIKEN Advanced Institute for Computational Science, Kobe, Hyogo (Japan); Pleiter, D. [Forschungszentrum Juelich GmbH (Germany). Juelich Supercomputing Centre (JSC); Regensburg Univ. (Germany). Institut fuer Theoretische Physik; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Division; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Stueben, H. [Hamburg Univ. (Germany). Regionales Rechenzentrum; Collaboration: CSSM and QCDSF/UKQCD Collaborations

2014-01-15

240

Magnetic form factors of the octet baryons from lattice QCD and chiral extrapolation  

International Nuclear Information System (INIS)

We present a 2+1-flavor lattice QCD calculation of the electromagnetic Dirac and Pauli form factors of the octet baryons. The magnetic Sachs form factor is extrapolated at six fixed values of Q2 to physical pseudoscalar masses and infinite volume using a formulation based on heavy baryon chiral perturbation theory with finite-range regularization. We properly account for omitted disconnected quark contractions using a partially-quenched effective field theory formalism. The results compare well with the experimental form factors of the nucleon and the magnetic moments of the octet baryons.

2014-01-01

 
 
 
 
241

Parameter extrapolation to ungauged basins with a hydrological distributed model in a regional framework  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A Regional Water Resources study was performed at basins within and draining to the Basque Country Region (N of Spain), with a total area of approximately 8500 km2. The objective was to obtain daily and monthly long-term discharges in 567 points, most of them ungauged, with basin areas ranging from 0.25 to 1850 km2. In order to extrapolate the calibrations at gauged points to the ungauged ones, a distributed and conceptually based model called TET...

Ve?lez, J. J.; Puricelli, M.; Lo?pez Unzu, F.; France?s, F.

2009-01-01

242

Parameter extrapolation to ungauged basins with a hydrological distributed model in a regional framework  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A Regional Water Resources study was performed at basins within and draining to the Basque Country Region (N of Spain), with a total area of approximately 8500 km2. The objective was to obtain daily and monthly long-term discharges in 567 points, most of them ungauged, with basin areas ranging from 0.25 to 1850 km2. In order to extrapolate the calibrations at gauged points to the ungauged ones, a distributed and conceptually based model called TET...

Ve?lez, J. J.; Lo?pez Unzu, F.; Puricelli, M.; France?s, F.

2007-01-01

243

Theoretical basis for extrapolation of calibration data of PTC 6 throat tap nozzles  

Energy Technology Data Exchange (ETDEWEB)

Equations for the extrapolation of calibration data for ASME/PTC 6 throat tap nozzles are derived from boundary layer theory. Results match published coefficients with a maximum difference of +0.03 per cent. It is also shown that the effects of transition in the boundary layer extend to throat Reynolds numbers in excess of 10,000,000, far beyond the capacity of any known calibration laboratory. The present PTC 6 requirement that calibration data must be in the fully-turbulent range cannot be met with current facilities.

Keyser, D.R. (Naval Air Development Center, Warminster, PA (USA)); Murdock, J.W. (Drexel Univ., Philadelphia, PA (USA))

1990-01-01

244

Magnetic form factors of the octet baryons from lattice QCD and chiral extrapolation  

CERN Document Server

We present a 2+1--flavor lattice QCD calculation of the electromagnetic Dirac and Pauli form factors of the octet baryons. The magnetic Sachs form factor is extrapolated at six fixed values of $Q^2$ to physical pseudoscalar masses and infinite volume using a formulation based on heavy baryon chiral perturbation theory with finite-range regularization. We properly account for omitted disconnected quark contractions using a partially-quenched effective field theory formalism. The results compare well with the experimental form factors of the nucleon and the magnetic moments of the octet baryons.

Shanahan, P E; Young, R D; Zanotti, J M; Horsley, R; Nakamura, Y; Pleiter, D; Rakow, P E L; Schierholz, G; Stüben, H

2014-01-01

245

Demonstration of ELM pacing by Pellet Injection on DIII-D and Extrapolation to ITER  

Energy Technology Data Exchange (ETDEWEB)

Demonstration of ELM pacing by pellet injection on DIII-D and extrapolation to ITER<#_ftn1>* L.R. Baylor1, N. Commaux1, T.C. Jernigan1, P.B. Parks2, T.E. Evans2, T.H. Osborne2, E.J. Strait2, M.E. Fenstermacher3, C.J. Lasnier3, R.A. Moyer4, J.H. Yu4 1Oak Ridge National Laboratory, Oak Ridge, TN, USA 2General Atomics, San Diego, CA, USA 3 Lawrence Livermore National Laboratory, Livermore, CA, USA 4University of California San Diego, La Jolla, CA, USA Deuterium pellet injection has been used in experiments on the DIII-D tokamak to investigate the possibility of triggering small rapid edge localized modes (ELMs) in reactor relevant plasma regimes. ELMs have been observed to be triggered from small 1.8 mm pellets injected from all available locations and under all H-mode operating scenarios in DIII-D. Experimental details have shown that the ELMs are triggered before the pellets reach the top of the H-mode pedestal, implying that very small shallow penetrating pellets are sufficient to trigger ELMs. Fast camera images of the pellet entering the plasma from the low field side show a single plasma filament becoming visible near the pellet cloud and striking the outer vessel wall within 200 ms. Additional ejected filaments are then observed to subsequently reach the wall. The plasma stored energy loss from the pellet triggered ELMs is a function of the elapsed time after a previous ELM. Pellet ELM pacing has been proposed as a method to prevent large ELMs that can damage the ITER plasma facing components [1]. A demonstration of pacing of ELMs on DIII-D was made by injecting slow 14 Hz pellets on the low field side in an ITER shape plasma with low natural ELM frequency and a normalized b of 1.8. The non-pellet discharge natural ELM frequency was ~5 Hz with ELM energy losses up to 85 kJ (>10% of total stored energy) while the case with pellets was able to demonstrate >20 Hz ELMs with an average ELM energy loss less than 22 kJ (<3% of the total). The resulting ELM frequency was larger than the pellet frequency indicating both a direct ELM trigger by each pellet and an indirect effect on the overall pedestal stability to ELMs from the multiple pellets. No increase in density or significant decrease in energy confinement with the pellets was observed. The implications of these results for possible pellet ELM pacing on ITER will be discussed. [1] P.T. Lang et al., Nucl. Fusion 44 (2004) 665.

Baylor, Larry R [ORNL; Commaux, Nicolas JC [ORNL; Jernigan, Thomas C [ORNL; Parks, P. B. [General Atomics; Evans, T.E. [General Atomics, San Diego; Osborne, T. H. [General Atomics; Strait, E. J. [General Atomics; Fenstermacher, M. E. [Lawrence Livermore National Laboratory (LLNL); Lasnier, C. J. [Lawrence Livermore National Laboratory (LLNL); Moyer, R.A. [University of California, San Diego; Yu, J.H. [University of California, San Diego

2010-01-01

246

Extrapolation chamber mounted on perspex for calibration of high energy photon and electron beams from a clinical linear accelerator  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The objective of the present study is to establish radiation standards for absorbed doses, for clinical high energy linear accelerator beams. In the nonavailability of a cobalt-60 beam for arriving at Nd, water values for thimble chambers, we investigated the efficacy of perspex mounted extrapolation chamber (EC) used earlier for low energy x-rays and beta dosimetry. Extrapolation chamber with facility for achieving variable electrode separations 10.5mm to 0.5mm using micrometer screw was use...

2009-01-01

247

Is the Climate Right for Pleistocene Rewilding? Using Species Distribution Models to Extrapolate Climatic Suitability for Mammals across Continents  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Species distribution models (SDMs) are increasingly used for extrapolation, or predicting suitable regions for species under new geographic or temporal scenarios. However, SDM predictions may be prone to errors if species are not at equilibrium with climatic conditions in the current range and if training samples are not representative. Here the controversial “Pleistocene rewilding” proposal was used as a novel example to address some of the challenges of extrapolating modeled species-cli...

Richmond, Orien M. W.; Mcentee, Jay P.; Hijmans, Robert J.; Brashares, Justin S.

2010-01-01

248

Understanding receptor-mediated effects in rainbow trout: in vitro-in vivo extrapolation using physiologically based toxicokinetic models.  

Science.gov (United States)

The European REACH regulation requires the use of animal experimentation to assess the risk of industrial chemicals. However, the 3R principle (reduction, replacement, refinement) demands the use of suitable alternative test methods. Many dossiers submitted for the authorization of chemicals have attempted to provide the required data without performing new experiments, relying heavily on in silico methods; in vitro assays were scarcely used. We propose a methodology that uses physiologically based toxicokinetic (PBTK) models to extrapolate in vitro data to the in vivo level. We collected experimental results for in vitro and in vivo ethoxyresorufin-O-deethylase and vitellogenin induction following chemical exposure and compared those results with model predictions. We found that the predictive power of aqueous chemical concentrations was limited; median effect concentrations (EC50s) based on internal concentrations in fish correlated better with in vitro EC50s. Our data show that in vitro assays could offer a substitute for fish studies when combined with PBTK models. PMID:24548176

Brinkmann, Markus; Eichbaum, Kathrin; Buchinger, Sebastian; Reifferscheid, Georg; Bui, Thuy; Schäffer, Andreas; Hollert, Henner; Preuss, Thomas G

2014-03-18

249

Extrapolation models: Absolute and relative risk. Extrapolationsmodelle - absolutes und relatives Risiko  

Energy Technology Data Exchange (ETDEWEB)

For lifetime experiences concerning the radiation-induced frequency of cancer, there are only a few data available form any of the larger epidemiological studies. Appropriate models must therefore be developed to extrapolate the limited period of life of those irradiated persons that were examined in these studies. Basically, two models may be differentiated for defining the radiation risk after a certain length of study and for extrapolating the risk for the irradiated persons over the actual length of the study. The absolute risk model is based on the assumption that radiation-induced cancer cases occur on a constant level or reach a maximum after a certain latency period, in addition to the spontaneously occurring cancer cases. For the relative risk model it is assumend that radiation-induced cancer increases proportionally to the spontaneous cases. The doubling dose, i.e. the dose which doubles the spontaneous risk, is a particular form of the relative risk and is used specifically for genetic radiation effect. From recent data is more and more apparent that epidemiological findings are better described by a relative rather than an absolute risk model. In consequence of a relative risk projection, the values for the assessed radiation risk are expected to be higher. (orig.).

Martignoni, K. (Bundesamt fuer Strahlenschutz, Neuherberg (Germany). Inst. fuer Strahlenhygiene)

1991-11-01

250

Evaluation of two-parameter extrapolation efficiency for one class of spectral problems with integral operator on a half-axis  

International Nuclear Information System (INIS)

The computational experiments on the evoluation of two-parameter extrapolation efficiency at numerical solving of one class of spectral problems for integral operator on the half-axis are carried out. The computational scheme to realize this extrapolation is proposed. The motion along h- and R-levels is combined optimally in this type of extrapolation. Due to the application of extrapolation procedure the eigenvalue precision could be improved twice on the average and algorithm complexity decreased by 1-2 orders

1985-01-01

251

Data-based discharge extrapolation: estimating annual discharge for a partially gauged large river basin from its small sub-basins  

Science.gov (United States)

Large-scale hydrological models and land surface models are by far the only tools for accessing future water resources in climate change impact studies. Those models estimate discharge with large uncertainties, due to the complex interaction between climate and hydrology, the limited quality and availability of data, as well as model uncertainties. A new purely data-based scale-extrapolation method is proposed, to estimate water resources for a large basin solely from selected small sub-basins, which are typically two-orders-of-magnitude smaller than the large basin. Those small sub-basins contain sufficient information, not only on climate and land surface, but also on hydrological characteristics for the large basin In the Baltic Sea drainage basin, best discharge estimation for the gauged area was achieved with sub-basins that cover 2-4% of the gauged area. There exist multiple sets of sub-basins that resemble the climate and hydrology of the basin equally well. Those multiple sets estimate annual discharge for gauged area consistently well with 5% average error. The scale-extrapolation method is completely data-based; therefore it does not force any modelling error into the prediction. The multiple predictions are expected to bracket the inherent variations and uncertainties of the climate and hydrology of the basin. The method can be applied in both un-gauged basins and un-gauged periods with uncertainty estimation.

Gong, L.

2013-12-01

252

Data-based discharge extrapolation: estimating annual discharge for a partially gauged large river basin from its small sub-basins  

Directory of Open Access Journals (Sweden)

Full Text Available Large-scale hydrological models and land surface models are by far the only tools for accessing future water resources in climate change impact studies. Those models estimate discharge with large uncertainties, due to the complex interaction between climate and hydrology, the limited quality and availability of data, as well as model uncertainties. A new purely data-based scale-extrapolation method is proposed, to estimate water resources for a large basin solely from selected small sub-basins, which are typically two-orders-of-magnitude smaller than the large basin. Those small sub-basins contain sufficient information, not only on climate and land surface, but also on hydrological characteristics for the large basin In the Baltic Sea drainage basin, best discharge estimation for the gauged area was achieved with sub-basins that cover 2–4% of the gauged area. There exist multiple sets of sub-basins that resemble the climate and hydrology of the basin equally well. Those multiple sets estimate annual discharge for gauged area consistently well with 5% average error. The scale-extrapolation method is completely data-based; therefore it does not force any modelling error into the prediction. The multiple predictions are expected to bracket the inherent variations and uncertainties of the climate and hydrology of the basin. The method can be applied in both un-gauged basins and un-gauged periods with uncertainty estimation.

L. Gong

2012-06-01

253

Improved spatial resolution in time-resolved transillumination imaging using temporal extrapolation with the cumulant expansion solution to the transport equation  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English Abstract in spanish Este artículo presenta resultados de un método para la formación de imágenes resueltas temporalmente mediante la transmisión de luz usando una extrapolación temporal. La extrapolación temporal se realiza mediante la solución a la ecuación de transporte mediante la expansión en cumulantes. Los result [...] ados obtenidos se comparan con los resultados del mismo método pero usando la solución mediante la aproximación de difusión. Se encuentra que los resultados son consistentes pero la el método usando la expansión en cumulantes da mejor resolución, en un factor de aproximadamente 3, para el proceso de formación de imágenes, esto debido a que da una mejor estimación de la contribución de los fotones con tiempos de integración menores. Abstract in english This paper presents results of a time-resolved transillumination imaging method using temporal extrapolation. The temporal extrapolation is performed with the cumulant expansion solution to the transport equation. The results obtained are compared to results of the same method but using the diffusio [...] n approximation solution. It is found that the results are consistent but that the cumulant expansion method gives better resolution, by a factor of approximately 3, for the imaging process, because it gives a better estimation of the photon contribution for shorter integration times.

Ortiz-Rascón, E.; Bruce, N. C.; Rodríguez-Rosales, A. A.; Garduño-Mejía, J.; Ortega-Martínez, R..

254

Corrosion and corrosion control of mild steel in concentrated H2SO4 solutions by a newly synthesized glycine derivative  

International Nuclear Information System (INIS)

Graphical abstract: Display Omitted Research highlights: ? GlyD1 exhibits inhibiting properties more than GlyD2 and Gly. ? Inhibition efficiency increases with inhibitor concentration. ? Inhibition efficiency decreases with temperature, suggesting physical adsorption. ? Validation of corrosion rates measured by Tafel extrapolation method is confirmed. - Abstract: A newly synthesized glycine derivative (GlyD1), 2-(4-(dimethylamino)benzylamino)acetic acid hydrochloride, was used to control mild steel corrosion in 4.0 M H2SO4 solutions at different temperatures (278-338 K). Tafel extrapolation, linear polarization resistance (LPR) and impedance methods were used to test corrosion inhibitor efficiency. An independent method of chemical analysis, namely ICP-AES (inductively coupled plasma atomic emission spectrometry) was also used to test validity of corrosion rate measured by Tafel extrapolation method. Results obtained were compared with an available glycine derivative (GlyD2) and glycine (Gly). Tafel polarization measurements revealed that the three tested inhibitors function as mixed-type compounds. The inhibition efficiency increased with increase in inhibitor concentration and decreased with temperature, suggesting the occurrence of physical adsorption. The adsorptive behaviour of the three inhibitors followed Temkin-type isotherm and the standard free energy changes of adsorption (?Gadso) were evaluated for the three tested inhibitors as a function of temperature. The inhibition performance of GlyD1 was much better than those of GlyD2 and Gly itself. Results obtained from the different corrosion evaluation techniques were in good agreement.

2011-03-01

255

Monitoring corrosion and corrosion control of iron in HCl by non-ionic surfactants of the TRITON-X series - Part II. Temperature effect, activation energies and thermodynamics of adsorption  

Energy Technology Data Exchange (ETDEWEB)

Research highlights: TX-305 exhibits inhibiting properties for iron corrosion more than TX-165 and TX 100. Inhibition efficiency increases with temperature, suggesting chemical adsorption. The three tested surfactants act as mixed-type inhibitors with cathodic predominance. Validation of corrosion rates measured by Tafel extrapolation method is confirmed. - Abstract: The inhibition characteristics of non-ionic surfactants of the TRITON-X series, namely TRITON-X-100 (TX-100), TRITON-X-165 (TX-165) and TRITON-X-305 (TX-305), on the corrosion of iron was studied in 1.0 M HCl solutions as a function of inhibitor concentration (0.005-0.075 g L{sup -1}) and solution temperature (278-338 K). Measurements were conducted based on Tafel extrapolation method. Electrochemical frequency modulation (EFM), a non-destructive corrosion measurement technique that can directly give values of corrosion current without prior knowledge of Tafel constants, is also presented. Experimental corrosion rates determined by the Tafel extrapolation method were compared with corrosion rates obtained by the EFM technique and an independent method of chemical analysis. The chemical method of confirmation of the corrosion rates involved determination of the dissolved cation, using ICP-AES (inductively coupled plasma atomic emission spectrometry). The aim was to confirm validation of corrosion rates measured by the Tafel extrapolation method. Results obtained showed that, in all cases, the inhibition efficiency increased with increase in temperature, suggesting that chemical adsorption occurs. The adsorptive behaviour of the three surfactants followed Temkin-type isotherm. The standard free energies of adsorption decreased with temperature, reflecting better inhibition performance. These findings confirm chemisorption of the tested inhibitors. Thermodynamic activation functions of the dissolution process were also calculated as a function of each inhibitor concentration. All the results obtained from the methods employed are in reasonable agreement.

Amin, Mohammed A., E-mail: maaismail@yahoo.co [Materials and Corrosion Lab (MCL), Department of Chemistry, Faculty of Science, Taif University, 888 Hawiya (Saudi Arabia); Department of Chemistry, Faculty of Science, Ain shams University, 11566 Abbassia, Cairo (Egypt); Ahmed, M.A. [Physics Department, Faculty of Science, Taif University, 888 Hawiya (Saudi Arabia); Arida, H.A. [Materials and Corrosion Lab (MCL), Department of Chemistry, Faculty of Science, Taif University, 888 Hawiya (Saudi Arabia); Arslan, Taner [Department of Chemistry, Eskisehir Osmangazi University, 26480 Eskisehir (Turkey); Saracoglu, Murat [Faculty of Education, Erciyes University, 38039 Kayseri (Turkey); Kandemirli, Fatma [Department of Chemistry, Nigde University, 41000 Nigde (Turkey)

2011-02-15

256

Monitoring corrosion and corrosion control of iron in HCl by non-ionic surfactants of the TRITON-X series - Part II. Temperature effect, activation energies and thermodynamics of adsorption  

International Nuclear Information System (INIS)

Research highlights: ? TX-305 exhibits inhibiting properties for iron corrosion more than TX-165 and TX 100. ? Inhibition efficiency increases with temperature, suggesting chemical adsorption. ? The three tested surfactants act as mixed-type inhibitors with cathodic predominance. ? Validation of corrosion rates measured by Tafel extrapolation method is confirmed. - Abstract: The inhibition characteristics of non-ionic surfactants of the TRITON-X series, namely TRITON-X-100 (TX-100), TRITON-X-165 (TX-165) and TRITON-X-305 (TX-305), on the corrosion of iron was studied in 1.0 M HCl solutions as a function of inhibitor concentration (0.005-0.075 g L-1) and solution temperature (278-338 K). Measurements were conducted based on Tafel extrapolation method. Electrochemical frequency modulation (EFM), a non-destructive corrosion measurement technique that can directly give values of corrosion current without prior knowledge of Tafel constants, is also presented. Experimental corrosion rates determined by the Tafel extrapolation method were compared with corrosion rates obtained by the EFM technique and an independent method of chemical analysis. The chemical method of confirmation of the corrosion rates involved determination of the dissolved cation, using ICP-AES (inductively coupled plasma atomic emission spectrometry). The aim was to confirm validation of corrosion rates measured by the Tafel extrapolation method. Results obtained showed that, in all cases, the inhibition efficiency increased with increase in temperature, suggesting that chemical adsorption occurs. The adsorptive behaviour of the three surfactants followed Temkin-type isotherm. The standard free energies of adsorption decreased with temperature, reflecting better inhibition performance. These findings confirm chemisorption of the tested inhibitors. Thermodynamic activation functions of the dissolution process were also calculated as a function of each inhibitor concentration. All the results obtained from the methods employed are in reasonable agreement.

2011-02-01

257

Hematological responses after inhaling 238PuO2: An extrapolation from beagle dogs to humans  

International Nuclear Information System (INIS)

The alpha emitter plutonium-238 (238Pu), which is produced in uranium-fueled, light-water reactors, is used as a thermoelectric power source for space applications. Inhalation of a mixed oxide form of Pu is the most likely mode of exposure of workers and the general public. Occupational exposures to 238PuO2 have occurred in association with the fabrication of radioisotope thermoelectric generators. Organs and tissue at risk for deterministic and stochastic effects of 238Pu-alpha irradiation include the lung, liver, skeleton, and lymphatic tissue. Little has been reported about the effects of inhaled 238PuO2 on peripheral blood cell counts in humans. The purpose of this study was to investigate hematological responses after a single inhalation exposure of Beagle dogs to alpha-emitting 238PuO2 particles and to extrapolate results to humans

1994-11-01

258

Continuum extrapolation of finite temperature meson correlation functions in quenched lattice QCD  

CERN Document Server

We explore the continuum limit $a\\rightarrow 0$ of meson correlation functions at finite temperature. In detail we analyze finite volume and lattice cut-off effects in view of possible consequences for continuum physics. We perform calculations on quenched gauge configurations using the clover improved Wilson fermion action. We present and discuss simulations on isotropic $N_\\sigma^3\\times 16$ lattices with $N_\\sigma=32,48,64,128$ and $128^3 \\times N_\\tau$ lattices with $N_\\tau=16,24,32,48$ corresponding to lattice spacings in the range of $0.01 fm \\lsim a \\lsim\\ 0.031 fm$ at $T\\simeq1.45T_c$. Continuum limit extrapolations of vector meson and pseudo scalar correlators are performed and their large distance expansion in terms of thermal moments is introduced. We discuss consequences of this analysis for the calculation of the electrical conductivity of the QGP at this temperature.

Francis, Anthony

2010-01-01

259

Méthodologie de l'extrapolation des réacteurs chimiques Methodology for Scaling Up Chemical Reactors  

Directory of Open Access Journals (Sweden)

Full Text Available Après un exposé général relatif à la méthodologie du développement des procédés, applicable à l'extrapolation des réacteurs, est présenté un rapide examen critique des deux principales techniques mises en oeuvre, à savoir : - la théorie de la similitude ; - l'élaboration de modèles mathématiques. Deux exemples pratiques, relatifs aux réacteurs homogènes et aux réacteurs catalytiques à lit fixe et deux phases fluides, sont ensuite examinés à la lumière des considérations générales précédentes. After giving a general description of process-development methodology applicable to scaling up reactors, this article makes a quick critical examination of the two main techniques involved, i. e. : (a the theory of similarity, and (b the compiling of mathematical models. Two practical examples relating to homogeneous reactors and trickle-bed catalytic reactors are then examined in the light of the preceding general considerations.

Trambouze P.

2006-11-01

260

Linear Extrapolation of Ultrarelativistic Nucleon-Nucleon Scattering to Nucleus-Nucleus Collisions  

CERN Document Server

We use a Glauber-like approach to describe very energetic nucleus-nucleus collisions as a sequence of binary nucleon-nucleon collisions. No free parameters are needed: all the information comes from simple parametrizations of nucleon-nucleon collision data. Produced mesons are assumed not to interact with each other or with the original baryons. Comparisons are made to published experimental measurements of baryon rapidity and transverse momentum distributions, negative hadron rapidity and transverse momentum distributions, average multiplicities of pions, kaons, hyperons, and antihyperons, and zero degree energy distributions for sulfur-sulfur collisions at 200 GeV/c per nucleon and for lead-lead collisions at 158 GeV/c per nucleon. Good agreement is found except that the number of strange particles produced, especially antihyperons, is too small compared with experiment. We call this model LEXUS: it is a baseline linear extrapolation of ultrarelativistic nucleon-nucleon scattering to heavy ion collisions.

Jeon, S; Jeon, Sangyong; Kapusta, Joseph

1997-01-01

 
 
 
 
261

Linear extrapolation of ultrarelativistic nucleon-nucleon scattering to nucleus-nucleus collisions  

Science.gov (United States)

We use a Glauber-like approach to describe very energetic nucleus-nucleus collisions as a sequence of binary nucleon-nucleon collisions. No free parameters are needed: All the information comes from simple parametrizations of nucleon-nucleon collision data. Produced mesons are assumed not to interact with each other or with the original baryons. Comparisons are made to published experimental measurements of baryon rapidity and transverse momentum distributions, negative hadron rapidity and transverse momentum distributions, average multiplicities of pions, kaons, hyperons, and antihyperons, and zero degree energy distributions for sulfur-sulfur collisions at 200 GeV/c per nucleon and for lead-lead collisions at 158 GeV/c per nucleon. Good agreement is found except that the number of strange particles produced, especially antihyperons, is too small compared with experiment. We call this model LEXUS: It is a base-line linear extrapolation of ultrarelativistic nucleon-nucleon scattering to heavy ion collisions.

Jeon, Sangyong; Kapusta, Joseph

1997-07-01

262

Determination of the electronic structure of thiophene oligomers and extrapolation to polythiophene  

Energy Technology Data Exchange (ETDEWEB)

Ionization energies, attachment energies, and electrochemical reduction potentials of thiophene oligomers (n {le} 5) have been determined experimentally (ultraviolet photoelectron and electron transmission spectroscopies and cyclic voltammetry) and theoretically (ionization and attachment energies by MINDO/3). The geometrical parameters of the most stable conformation of 2,2{prime}-bithienyl have been computed at the ab initio STO-3G level with complete relaxation. A short extrapolation of the energy data to the polymer provided accurate and reliable values for important properties of (gas phase) polythiophene, namely, ionization energy (6.9 eV), valence bandwidth (3.2 eV), electron affinity (0.9-1.1 eV), HOMO-LUMO energy gap (5.9 eV), and {lambda}{sub max} (2.7 eV).

Jones, D.; Guerra, M.; Favaretto, L. (ICoCEA, Bologna (Italy)); Modelli, A. (Universita di Bologna (Italy)); Fabrizio, M. (IPELP, Padova (Italy)); Distefano, G. (Universita di Ferrara (Italy))

1990-07-26

263

Feasibility of interspecies extrapolation in determining the bioequivalence of animal products intended for intramuscular administration.  

Science.gov (United States)

To examine the validity of extrapolating parenteral product bioequivalence determinations across target animal species, the relative bioavailability of two injectable formulations of ampicillin trihydrate (PolyflexR, a water-based suspension, and Ampi-kel 10R, an oil-based suspension) was examined in calves, sheep and swine. Employing products recognized to be bioinequivalent provided an opportunity to explore potential species-by-formulation interactions. As compared with PolyflexR, Ampi-kel 10R exhibited lower area under the curve (AUC) estimates but higher peak concentrations in all target animal species. Nevertheless, marked interspecies differences were noted in the width and bounds of the confidence intervals about the differences in treatment means. Potential physiological and physico-chemical reasons for these findings are discussed. PMID:11442787

Martinez, M N; Pedersoli, W M; Ravis, W R; Jackson, J D; Cullison, R

2001-04-01

264

Extrapolated neutron activation cross sections for dosimetry to 44 MeV  

International Nuclear Information System (INIS)

Thirty-one neutron activation cross sections have been extrapolated to 44 MeV for dosimetry applications at high-energy, accelerator-based neutron sources. All cross sections have undergone integral testing in Be(d,n) fields at E/sub d/ = 14, 16, and 40 MeV. The integral activities for most of the reactions agree within 10% with calculations based on time-of-flight measurements of the flux spectra. Tests show that at least 25 of the cross sections can be used with the SAND II code to unfold neutron spectra with differential errors of 10 to 30% in the neutron energy range from 2 to 30 MeV

1978-01-01

265

Modeling the systemic retention of beryllium in rat. Extrapolation to human  

International Nuclear Information System (INIS)

In this work, we analyzed different approaches, assayed in order to numerically describe the systemic behaviour of Beryllium. The experimental results used in this work, were previously obtained by Furchner et al. (1973), using Sprague-Dawley rats, and others animal species. Furchner's work includes the obtained model for whole body retention in rats, but not for each target organ. In this work we present the results obtained by modeling the kinetic behaviour of Beryllium in several target organs. The results of this kind of models were used in order to establish correlations among the estimated kinetic constants. The parameters of the model were extrapolated to humans and, finally, compared with others previously published. (Author) 12 refs

1994-01-01

266

Integrated scenario with type-III ELMy H-mode edge: extrapolation to ITER  

International Nuclear Information System (INIS)

One of the most severe problems for fusion reactors is the power load on the plasma facing components. The challenge is to develop operation scenarios, which combine sufficient energy confinement with benign heat loads to the plasma facing components. The radiative type-III ELMy H-mode seems a possible solution for such an integrated ITER scenario. Nitrogen seeded type-III ELMy H-modes for the standard inductive scenario and the high beta stationary hybrid scenario are investigated with respect to their transient and steady-state power fluxes to the divertor, confinement properties, edge operational space, core operational space, plasma purity and MHD behaviour. A large database of highly radiative type-III ELMy H-modes on JET is used for extrapolations to ITER. On this basis the transient heat load should be acceptable for ITER. It was found that the scaling of the confinement time with respect to the ion gyroradius is close to the gyro-Bohm scaling. Scalings with respect to the plasma collisionality suggest that the confinement will be good enough for an ITER scenario at 17 MA with a power amplification factor (Q) of 10 and might be marginally good enough for a Q = 10 scenario at 15 MA. Those extrapolations are supported by simulations with an integrated core/edge model COREDIV. In addition the hybrid scenario with type-III edge localized modes has been proven to have improved edge conditions without any modification of the central plasma current profile, indicating it is compatible with a high beta operation for a steady-state ITER Q = 5 scenario.

2009-09-01

267

Extrapolating glacier mass balance to the mountain range scale: the European Alps 1900–2100  

Directory of Open Access Journals (Sweden)

Full Text Available This study addresses the extrapolation of single glacier mass balance measurements to the mountain range scale and aims at deriving time series of area-averaged mass balance and ice volume change for all glaciers in the European Alps for the period 1900–2100. Long-term mass balance series for 50 Swiss glaciers based on a combination of field data and modelling, and WGMS data for glaciers in Austria, France and Italy are used. A complete glacier inventory is available for the year 2003. Mass balance extrapolation is performed based on (1 arithmetic averaging, (2 glacier hypsometry, and (3 multiple regression. Given a sufficient number of data series, multiple regression with variables describing glacier geometry performs best in reproducing observed spatial mass balance variability. Future mass changes are calculated by driving a combined model for mass balance and glacier geometry with GCM ensembles based on four emission scenarios. Mean glacier mass balance in the European Alps is ?0.32 ± 0.04 m w.e. a?1 in 1900–2011, and ?1 m w.e. a?1 over the last decade. Total ice volume change since 1900 is ?100 ± 13 km3; annual values vary between ?5.9 km3 (1947 and +3.9 km3 (1977. Mean mass balances are expected to be around ?1.3 m w.e. a?1 by 2050. Model results indicate a glacier area reduction to 4–18% relative to 2003 for the end of the 21st century.

M. Huss

2012-03-01

268

Extrapolating glacier mass balance to the mountain-range scale: the European Alps 1900–2100  

Directory of Open Access Journals (Sweden)

Full Text Available This study addresses the extrapolation of in-situ glacier mass balance measurements to the mountain-range scale and aims at deriving time series of area-averaged mass balance and ice volume change for all glaciers in the European Alps for the period 1900–2100. Long-term mass balance series for 50 Swiss glaciers based on a combination of field data and modelling, and WGMS data for glaciers in Austria, France and Italy are used. A complete glacier inventory is available for the year 2003. Mass balance extrapolation is performed based on (1 arithmetic averaging, (2 glacier hypsometry, and (3 multiple regression. Given a sufficient number of data series, multiple regression with variables describing glacier geometry performs best in reproducing observed spatial mass balance variability. Future mass changes are calculated by driving a combined model for mass balance and glacier geometry with GCM ensembles based on four emission scenarios. Mean glacier mass balance in the European Alps is ?0.31 ± 0.04 m w.e. a?1 in 1900–2011, and ?1 m w.e. a?1 over the last decade. Total ice volume change since 1900 is ?96 ± 13 km3; annual values vary between ?5.9 km3 (1947 and +3.9 km3 (1977. Mean mass balances are expected to be around ?1.3 m w.e. a?1 by 2050. Model results indicate a glacier area reduction of 4–18% relative to 2003 for the end of the 21st century.

M. Huss

2012-07-01

269

On the effectiveness of CCSD(T) complete basis set extrapolations for atomization energies.  

Science.gov (United States)

The leading cause of error in standard coupled cluster theory calculations of thermodynamic properties such as atomization energies and heats of formation originates with the truncation of the one-particle basis set expansion. Unfortunately, the use of finite basis sets is currently a computational necessity. Even with basis sets of quadruple zeta quality, errors can easily exceed 8 kcal/mol in small molecules, rendering the results of little practical use. Attempts to address this serious problem have led to a wide variety of proposals for simple complete basis set extrapolation formulas that exploit the regularity in the correlation consistent sequence of basis sets. This study explores the effectiveness of six formulas for reproducing the complete basis set limit. The W4 approach was also examined, although in lesser detail. Reference atomization energies were obtained from standard coupled-cluster singles, doubles, and perturbative triples (CCSD(T)) calculations involving basis sets of 6? or better quality for a collection of 141 molecules. In addition, a subset of 51 atomization energies was treated with explicitly correlated CCSD(T)-F12b calculations and very large basis sets. Of the formulas considered, all proved reliable at reducing the one-particle expansion error. Even the least effective formulas cut the error in the raw values by more than half, a feat requiring a much larger basis set without the aid of extrapolation. The most effective formulas cut the mean absolute deviation by a further factor of two. Careful examination of the complete body of statistics failed to reveal a single choice that out performed the others for all basis set combinations and all classes of molecules. PMID:21806085

Feller, David; Peterson, Kirk A; Hill, J Grant

2011-07-28

270

Properties of high-T/sub c/, A-15 Nb3Si: An extrapolation  

International Nuclear Information System (INIS)

We have measured the low-temperature specific heats of two samples of A-15 Nb-Si prepared by chemical vapor deposition. From the specific-heat data, low-T/sub c/, A-15 Nb-Si is found to have a ? of 15.2 +- 1.5 mJ/mole K2 and a Debye temperature, THETA/sub D/, of 319 +- 10 K, for a mole containing four atoms. In addition, the low-temperature specific heat of arc melted Nb/sub 0.82/Ge/sub 0.18/(A-15 structure) has been measured. The ? was found to be 15.2 +- 1.0 mJ/mole K2 and THETA/sub D/ was 345 +- 10 K. Using these data, the properties of stoichiometric (high-T/sub c/) Nb3Si are extrapolated from the substoichiometric Nb-Si samples measured, by analogy to the Nb-Ge system. Stoichiometric, single-phase A-15 Nb3Si, if preparable, should have a ? of 30 mJ/mole K2 and a THETA/sub D/ of 275 K. By calculating lambda, the electron-phonon coupling constant, and treating T/sub c/ as a variable (15--30 K), the electronic density of states, N (0), is extracted from this extrapolated ? and is found to be low, varying from 1.38 states /(eV atom) at T/sub c/=15 K to 0.91 states /(eV atom) at T/sub c/=30 K. The N (0) calculated for the low-T/sub c/ Nb/sub 0.82/Ge/sub 0.18/ is 1.01 states/(eV atom) and is remarkably close to the 1.08 states/(eV atom) calculated for the high-T/sub c/ Nb3Ge

1979-11-01

271

Space shuttle guidance, navigation and control equation document no. 4: Precision state and filter weighting matrix extrapolation  

Science.gov (United States)

The Precision State and Filter Weighting Matrix Extrapolation Routine is described which provides the capability to extrapolate any spacecraft geocentric state vector either backwards or forwards in time through a force field consisting of the earth's primary central-force gravitational attraction and a superimposed perturbing acceleration. The routine also provides the capability of extrapolating the filter-weighting matrix along the precision trajectory. This matrix is a square root form of the error covariance matrix and contains statistical information relative to the accuracies of the state vectors and certain other optionally estimated quantities. The routine is a cooled algorithm for the numerical solution of modified forms of the basic differential equations which are satisfied by the geocentric state vector of the spacecraft's center of mass and by the filter-weighting matrix.

Robertson, W. M.

1972-01-01

272

Extrapolated experimental critical parameters of unreflected and steel-reflected massive enriched uranium metal spherical and hemispherical assemblies  

Energy Technology Data Exchange (ETDEWEB)

Sixty-nine critical configurations of up to 186 kg of uranium are reported from very early experiments (1960s) performed at the Rocky Flats Critical Mass Laboratory near Denver, Colorado. Enriched (93%) uranium metal spherical and hemispherical configurations were studied. All were thick-walled shells except for two solid hemispheres. Experiments were essentially unreflected; or they included central and/or external regions of mild steel. No liquids were involved. Critical parameters are derived from extrapolations beyond subcritical data. Extrapolations, rather than more precise interpolations between slightly supercritical and slightly subcritical configurations, were necessary because experiments involved manually assembled configurations. Many extrapolations were quite long; but the general lack of curvature in the subcritical region lends credibility to their validity. In addition to delayed critical parameters, a procedure is offered which might permit the determination of prompt critical parameters as well for the same cases. This conjectured procedure is not based on any strong physical arguments.

Rothe, R.E.

1997-12-01

273

Extrapolated experimental critical parameters of unreflected and steel-reflected massive enriched uranium metal spherical and hemispherical assemblies  

International Nuclear Information System (INIS)

Sixty-nine critical configurations of up to 186 kg of uranium are reported from very early experiments (1960s) performed at the Rocky Flats Critical Mass Laboratory near Denver, Colorado. Enriched (93%) uranium metal spherical and hemispherical configurations were studied. All were thick-walled shells except for two solid hemispheres. Experiments were essentially unreflected; or they included central and/or external regions of mild steel. No liquids were involved. Critical parameters are derived from extrapolations beyond subcritical data. Extrapolations, rather than more precise interpolations between slightly supercritical and slightly subcritical configurations, were necessary because experiments involved manually assembled configurations. Many extrapolations were quite long; but the general lack of curvature in the subcritical region lends credibility to their validity. In addition to delayed critical parameters, a procedure is offered which might permit the determination of prompt critical parameters as well for the same cases. This conjectured procedure is not based on any strong physical arguments

1997-01-01

274

Eco-label - simple environmental choice / Andres Viia, Külliki Tafel  

Index Scriptorium Estoniae

Autorid selgitavad ökomärgistuse olemust ja vajalikkust tarbijate teavitamisel vähem keskkonda kahjustavatest toodetest ning teenustest. Lisatud näiteid regionaalsetest ja rahvuslikest ökomärkidest EL-is, tuntumatest ökomärkidest väljaspool Euroopat, hoiatavatest ja informatiivsetest keskkonnamärkidest ning libaökomärkidest. Vt. samas: North-East Estonia - a seat of an environment-friendly batteries' recycling

Viia, Andres

2003-01-01

275

Mediatransformasie dek die tafel vir ’n nuwe joernalistiek  

Directory of Open Access Journals (Sweden)

Full Text Available Media transformation sets the scene for a new journalismSince 1993 the South African media have been going through a period of fundamental transformation. This process has resulted in a phenomenon of black journalists and whites with credentials as anti-apartheid activists, moving into senior editorial positions at the South African Broadcasting Corporation (SABC as well as at newspapers. This article briefly describes the said transformational steps within the framework of existing media models, inter alia the developmental, social-responsibility and democratic-participatory models. Journalism covering the arts, culture and literature is thereby placed within a broader media context. It is concluded that the dominant media model(s will determine the kind of journalism we can expect in future.

J. D. Froneman

1997-05-01

276

The new track extrapolation package of the ATLAS tracking software in a case study of a high precision W mass measurement  

International Nuclear Information System (INIS)

Full text: The desired precision of 25 MeV for the W mass with the ATLAS detector is planed to be achieved by using the leptonic decay channel of the W : W ? l?, where l = e, ? . As the longitudinal momentum of the neutrino can not be measured, the measurement is done using the transverse momentum of lepton and neutrino, which is calculated through a recoil method. Results from CDF and D0 have shown that an unprecise knowledge of the total lepton energy and momentum scale is the dominating source of uncertainty of the W mass measurement. The knowledge of the lepton mass scale requires a deep understanding of the material in the ATLAS Inner Detector with a uncertainty of about 1 % which is of an order of magnitude better than in any comparable high energy physics experiment so far. In addition the magnetic field map has to be known with a precision of 0.1 %. This also requires tracking algorithms to process this detailed input. The methodology on how to achieve such a detailed description and its correct treatment including energy loss and multiple scattering effects during track extrapolation will be presented. In addition, results from the ATLAS Combined Testbeam 2004 using the new extrapolation scheme will be included into the presentation. (author)

2005-09-27

277

Accelerating Monte Carlo molecular simulations by reweighting and reconstructing Markov chains: Extrapolation of canonical ensemble averages and second derivatives to different temperature and density conditions  

Science.gov (United States)

Accurate determination of thermodynamic properties of petroleum reservoir fluids is of great interest to many applications, especially in petroleum engineering and chemical engineering. Molecular simulation has many appealing features, especially its requirement of fewer tuned parameters but yet better predicting capability; however it is well known that molecular simulation is very CPU expensive, as compared to equation of state approaches. We have recently introduced an efficient thermodynamically consistent technique to regenerate rapidly Monte Carlo Markov Chains (MCMCs) at different thermodynamic conditions from the existing data points that have been pre-computed with expensive classical simulation. This technique can speed up the simulation more than a million times, making the regenerated molecular simulation almost as fast as equation of state approaches. In this paper, this technique is first briefly reviewed and then numerically investigated in its capability of predicting ensemble averages of primary quantities at different neighboring thermodynamic conditions to the original simulated MCMCs. Moreover, this extrapolation technique is extended to predict second derivative properties (e.g. heat capacity and fluid compressibility). The method works by reweighting and reconstructing generated MCMCs in canonical ensemble for Lennard-Jones particles. In this paper, system's potential energy, pressure, isochoric heat capacity and isothermal compressibility along isochors, isotherms and paths of changing temperature and density from the original simulated points were extrapolated. Finally, an optimized set of Lennard-Jones parameters (?, ?) for single site models were proposed for methane, nitrogen and carbon monoxide.

Kadoura, Ahmad; Sun, Shuyu; Salama, Amgad

2014-08-01

278

Beagle: an appropriate experimental animal for extrapolating the organ distribution pattern of Th in humans  

International Nuclear Information System (INIS)

The concentrations and the organ distribution patterns of 228Th, 230Th and 232Th in two 9-y-old dogs of our beagle colony were determined. The dogs were exposed only to background environmental levels of Th isotopes through ingestion (food and water) and inhalation as are humans. The organ distribution patterns of the isotopes in the beagles were compared to the organ distribution patterns in humans to determine if it is appropriate to extrapolate the beagle organ burden data to humans. Among soft tissues, only the lungs, lymph nodes, kidney and liver, and skeleton contained measurable amounts of Th isotopes. The organ distribution pattern of Th isotopes in humans and dog are similar, the majority of Th being in the skeleton of both species. The average skeletal concentrations of 228Th in dogs were 30 to 40 times higher than the average skeletal concentrations of the parent 232Th, whereas the concentration of 228Th in human skeleton was only four to five times higher than 232Th. This suggests that dogs have a higher intake of 228Ra through food than humans. There is a similar trend in the accumulations of 232Th, 230Th and 228Th in the lungs of dog and humans. The percentages of 232Th, 230Th and 228Th in human lungs are 26, 9.7 and 4.8, respectively, compared to 4.2, 2.6 and 0.48, respectively, in dog lungs. The larger percentages of Th isotopes in human lungs may be due simply to the longer life span of humans. If the burdens of Th isotopes in human lungs are normalized to an exposure time of 9.2 y (mean age of dogs at the time of sacrifice), the percent burden of 232Th, 230Th and 228Th in human lungs are estimated to be 3.6, 1.3 and 0.66, respectively. These results suggest that the beagle may be an appropriate experimental animal for extrapolating the organ distribution pattern of Th in humans

1988-01-01

279

Linear extrapolation of ultrarelativistic nucleon-nucleon scattering to nucleus-nucleus collisions  

International Nuclear Information System (INIS)

We use a Glauber-like approach to describe very energetic nucleus-nucleus collisions as a sequence of binary nucleon-nucleon collisions. No free parameters are needed: All the information comes from simple parametrizations of nucleon-nucleon collision data. Produced mesons are assumed not to interact with each other or with the original baryons. Comparisons are made to published experimental measurements of baryon rapidity and transverse momentum distributions, negative hadron rapidity and transverse momentum distributions, average multiplicities of pions, kaons, hyperons, and antihyperons, and zero degree energy distributions for sulfur-sulfur collisions at 200 GeV/c per nucleon and for lead-lead collisions at 158 GeV/c per nucleon. Good agreement is found except that the number of strange particles produced, especially antihyperons, is too small compared with experiment. We call this model LEXUS: It is a base-line linear extrapolation of ultrarelativistic nucleon-nucleon scattering to heavy ion collisions. copyright 1997 The American Physical Society

1997-07-01

280

Linear extrapolation of ultrarelativistic nucleon-nucleon scattering to nucleus-nucleus collisions  

Energy Technology Data Exchange (ETDEWEB)

We use a Glauber-like approach to describe very energetic nucleus-nucleus collisions as a sequence of binary nucleon-nucleon collisions. No free parameters are needed: All the information comes from simple parametrizations of nucleon-nucleon collision data. Produced mesons are assumed not to interact with each other or with the original baryons. Comparisons are made to published experimental measurements of baryon rapidity and transverse momentum distributions, negative hadron rapidity and transverse momentum distributions, average multiplicities of pions, kaons, hyperons, and antihyperons, and zero degree energy distributions for sulfur-sulfur collisions at 200 GeV/c per nucleon and for lead-lead collisions at 158 GeV/c per nucleon. Good agreement is found except that the number of strange particles produced, especially antihyperons, is too small compared with experiment. We call this model LEXUS: It is a base-line linear extrapolation of ultrarelativistic nucleon-nucleon scattering to heavy ion collisions. {copyright} {ital 1997} {ital The American Physical Society}

Jeon, S.; Kapusta, J. [School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

1997-07-01

 
 
 
 
281

Evidence for Solar Tether-cutting Magnetic Reconnection from Coronal Field Extrapolations  

CERN Document Server

Magnetic reconnection is one of the primary mechanisms for triggering solar eruptive events, but direct observation of its rapid process has been of challenge. In this Letter we present, using a nonlinear force-free field (NLFFF) extrapolation technique, a visualization of field line connectivity changes resulting from tether-cutting reconnection over about 30 minutes during the 2011 February 13 M6.6 flare in NOAA AR 11158. Evidence for the tether-cutting reconnection was first collected through multiwavelength observations and then by the analysis of the field lines traced from positions of four conspicuous flare 1700 A footpoints observed at the event onset. Right before the flare, the four footpoints are located very close to the regions of local maxima of magnetic twist index. Especially, the field lines from the inner two footpoints form two strongly twisted flux bundles (up to ~1.2 turns), which shear past each other and reach out close to the outer two footpoints, respectively. Immediately after the fl...

Liu, Chang; Lee, Jeongwoo; Wiegelmann, Thomas; Moore, Ronald L; Wang, Haimin

2013-01-01

282

QSAR analysis and data extrapolation among mammals in a series of aliphatic alcohols  

Energy Technology Data Exchange (ETDEWEB)

Concepts of QSAR analysis and biological similarity models are combined for use in extrapolation of LD/sub 50/ values after IP application of a series of aliphatic alcohols (C/sub 1/-C/sub 5/) to mouse, hamster, rat, and guinea pig and rabbit. It has been found that although close correlation exists between LD/sub 50/ values after IP and IV applications for mouse and rat, the QSAR obtained with LD/sub 50/ after IV application are not suitable for a prediction of LD/sub 50/ values after IP application for rabbit. Different transformation or distribution processes in mouse, rat, and rabbit after the two types of applications might be the reason. The LD/sub 50/ values (expressed in mmole/m/sup 2/ of body surface) seem to be independent of mammalian species used (at least within the mouse, rat, hamster, and probably guinea pig series). This fact makes it possible to predict reasonable values of LD/sub 50/ after IP application for rabbit. Expression of toxicity in mmole/m/sup 2/ of body surface may be used in toxicological studies. 24 references, 2 figures, 8 tables.

Tichy, M.; Trcka, V.; Roth, Z.; Krivucova, M.

1985-09-01

283

Spatial extrapolation of light use efficiency model parameters to predict gross primary production  

Directory of Open Access Journals (Sweden)

Full Text Available To capture the spatial and temporal variability of the gross primary production as a key component of the global carbon cycle, the light use efficiency modeling approach in combination with remote sensing data has shown to be well suited. Typically, the model parameters, such as the maximum light use efficiency, are either set to a universal constant or to land class dependent values stored in look-up tables. In this study, we employ the machine learning technique support vector regression to explicitly relate the model parameters of a light use efficiency model calibrated at several FLUXNET sites to site-specific characteristics obtained by meteorological measurements, ecological estimations and remote sensing data. A feature selection algorithm extracts the relevant site characteristics in a cross-validation, and leads to an individual set of characteristic attributes for each parameter. With this set of attributes, the model parameters can be estimated at sites where a parameter calibration is not possible due to the absence of eddy covariance flux measurement data. This will finally allow a spatially continuous model application. The performance of the spatial extrapolation scheme is evaluated with a cross-validation approach, which shows the methodology to be well suited to recapture the variability of gross primary production across the study sites.

Karsten Schulz

2011-12-01

284

Interpolating and Extrapolating Contaminant Concentrations from Monitor Wells to Model Grids for Fate-and-Transport Calculations  

Energy Technology Data Exchange (ETDEWEB)

Geostatistical interpolation of groundwater characterization data to visualize contaminant distributions in three dimensions is often hindered by the sparse distribution of samples relative to the size of the plume and scale of heterogeneities. Typically, placement of expensive monitoring wells is guided by the conceptualized plume rather than geostatistical considerations, focusing on contaminated areas rather than thoroughly gridding the plume boundary. The resulting data sets require careful analysis in order to produce plausible plume shells. A purely geostatistical approach is usually impractical; kriging parameters based on the observed data structure can extrapolate contamination far beyond the demonstrated extent of the plume. When more appropriate kriging parameters are selected, holes often occur in the interpolated distribution because realistic kriging ranges may not bridge large gaps between data points. Such artifacts obscure the probable location of the plume boundary and distort the contaminant distribution, obstructing quantitative modeling of remedial strategies. Two methods of constraining kriging can successfully eliminate these geostatistical artifacts. Laterally, the plume boundary may be controlled using a manually constructed mask that delineates the plan-view extent of the plume. After kriging, the mask is used to set all grid cells outside of the plume to a concentration of zero. Use of non-zero control points is a more refined but laborious approach that also bridges data gaps within the body of a plume and permits use of tighter kriging parameters. These can be obtained by manual linear interpolation between measured samples, or derived from historical data migrated along flow paths while accounting for all attenuative processes. Masking and use of non-zero control points result in a plume shell that reflects the intuition and professional judgment of the hydrologist, and can be interpolated automatically to any desired grid, providing initial conditions for fate-and-transport simulations. Error maps are a valuable aid in assessing data density, identifying areas that require additional sampling, or that must be filled by control points, if additional sampling is impractical.

Ward, D. B.; Clement, P.; Bostick, K.

2002-02-26

285

Extrapolated surface dose measurements using a NdFeB magnetic deflector for 6 MV x-ray beams.  

Science.gov (United States)

Extrapolated surface dose measurements have been performed using radiographic film to measure 2-Dimensional maps of skin and surface dose with and without a magnetic deflector device aimed at reducing surface dose. Experiments are also performed using an Attix parallel plate ionisation chamber for comparison to radiographic film extrapolation surface dose analysis. Extrapolated percentage surface dose assessments from radiographic film at the central axis of a 6 MV x-ray beam with magnetic deflector for field size 10 x 10 cm2, 15 x 15 cm2 and 20 x 20 cm2 are 9 +/- 3%, 13 +/- 3% and 16 +/- 3%, these compared to 14 +/- 3%, 19 +/- 3%, and 27 +/- 3% for open fields, respectively. Results from Attix chamber for the same field size are 12 +/- 1%, 15 +/- 1% and 18 +/- 1%, these compared to 16 +/- 1%, 21 +/- 1% and 27 +/- 1% for open fields, respectively. Results are also shown for profiles measured in-plane and cross-plane to the magnetic deflector and compared to open field data. Results have shown that the surface dose is reduced at all sites within the treatment field with larger reductions seen on one side of the field due to the sweeping nature of the designed magnetic field. Radiographic film extrapolation provides an advanced surface dose assessment and has matched well with Attix chamber results. Film measurement allows for easy 2 dimensional dose assessments. PMID:17508601

Damrongkijudom, N; Butson, M; Rosenfeld, A

2007-03-01

286

Extrapolated surface dose measurements using a NdFeB magnetic deflector for 6MV x-ray beams  

International Nuclear Information System (INIS)

Full text: Extrapolated surface dose measurements have been perfonned using radiographic film to measure 2-Dimensional maps of skin and surface dose with and without a magnetic deflector device aimed at reducing surface dose. Experiments are also performed using an Attix parallel plate ionisation chamber for comparison to radiographic film extrapolation surface dose analysis. Extrapolated percentage surface dose assessments from radiographic film at the central axis of a 6 MV x-ray beam with magnetic deflector for field size 10x10 cm. 15x15 cm2 and 20x20 cm: are 9 ± 3 %, 13 ± 3 % and 16 ± 3 %, these compared to 14 ± 3 %, 19 ± 3 %, and 27 ± 3 % for open fields, respectively. Results from Attix chamber for the same field size are 12 ± 1 %, 15 ± 1 % and 18 ± 1 %, these compared to 16 ± 1 %. 21 ± I % and 27 ± 1 % for open fields, respectively. Results are also shown for profiles measured in-plane and cross-plane to the magnetic deflector and compared to open field data. Results have shown that the surface dose is reduced at all sites within the treatment field with larger reductions seen on one side of the field due to the sweeping nature of the designed magnetic field. Radiographic film extrapolation provides an advanced surface dose assessment and has matched well with Attix chamber results. Film measurement allows for easy 2 dimensional dose assessments.

2007-03-01

287

Depth dose distribution in the water for clinical applicators of 90Sr + 90Y, with a extrapolation mini chamber  

International Nuclear Information System (INIS)

This work determines the depth dose in the water for clinical applicators of 90Sr + 90Y, using a extrapolation mini chamber developed at the IPEN, Sao Paulo, Brazil, and different thickness acrylic plates. The obtained results were compared with the international recommendations and were considered satisfactory

2009-11-09

288

Validity of extrapolated response dose as clinical prognostic indicator for incidence of spinal cord myelitis in altered fractionation  

International Nuclear Information System (INIS)

The aim of this study was to test the validity of extrapolated response dose (ERD) of linear quadratic model for altered fractionation schedules to the spinal cord using compiled clinical literature data and clinically reported data of spinal cord myelitis for altered fractionation

2003-11-07

289

Multiple time step molecular dynamics in the optimized isokinetic ensemble steered with the molecular theory of solvation: Accelerating with advanced extrapolation of effective solvation forces  

International Nuclear Information System (INIS)

We develop efficient handling of solvation forces in the multiscale method of multiple time step molecular dynamics (MTS-MD) of a biomolecule steered by the solvation free energy (effective solvation forces) obtained from the 3D-RISM-KH molecular theory of solvation (three-dimensional reference interaction site model complemented with the Kovalenko-Hirata closure approximation). To reduce the computational expenses, we calculate the effective solvation forces acting on the biomolecule by using advanced solvation force extrapolation (ASFE) at inner time steps while converging the 3D-RISM-KH integral equations only at large outer time steps. The idea of ASFE consists in developing a discrete non-Eckart rotational transformation of atomic coordinates that minimizes the distances between the atomic positions of the biomolecule at different time moments. The effective solvation forces for the biomolecule in a current conformation at an inner time step are then extrapolated in the transformed subspace of those at outer time steps by using a modified least square fit approach applied to a relatively small number of the best force-coordinate pairs. The latter are selected from an extended set collecting the effective solvation forces obtained from 3D-RISM-KH at outer time steps over a broad time interval. The MTS-MD integration with effective solvation forces obtained by converging 3D-RISM-KH at outer time steps and applying ASFE at inner time steps is stabilized by employing the optimized isokinetic Nosé-Hoover chain (OIN) ensemble. Compared to the previous extrapolation schemes used in combination with the Langevin thermostat, the ASFE approach substantially improves the accuracy of evaluation of effective solvation forces and in combination with the OIN thermostat enables a dramatic increase of outer time steps. We demonstrate on a fully flexible model of alanine dipeptide in aqueous solution that the MTS-MD/OIN/ASFE/3D-RISM-KH multiscale method of molecular dynamics steered by effective solvation forces allows huge outer time steps up to tens of picoseconds without affecting the equilibrium and conformational properties, and thus provides a 100- to 500-fold effective speedup in comparison to conventional MD with explicit solvent. With the statistical-mechanical 3D-RISM-KH account for effective solvation forces, the method provides efficient sampling of biomolecular processes with slow and/or rare solvation events such as conformational transitions of hydrated alanine dipeptide with the mean life times ranging from 30 ps up to 10 ns for “flip-flop” conformations, and is particularly beneficial for biomolecular systems with exchange and localization of solvent and ions, ligand binding, and molecular recognition

2013-12-28

290

Extrapolation of the relative risk of radiogenic neoplasms across mouse strains and to man  

Energy Technology Data Exchange (ETDEWEB)

We have examined two interrelated questions: is the susceptibility for radiogenic cancer related to the natural incidence, and are the responses of cancer induction by radiation described better by an absolute or a relative risk model. Also, we have examined whether it is possible to extrapolate relative risk estimates across species, from mice to humans. The answers to these questions were obtained from determinations of risk estimates for nine neoplasms in female and male C3Hf/Bd and C57BL/6 Bd mice and from data obtained from previous experiments with female BALB/c Bd and RFM mice. The mice were exposed to /sup 137/Cs gamma rays at 0.4 Gy/min to doses of 0, 0.5, 1.0, or 2.0 Gy. When tumors that were considered the cause of death were examined, both the control and induced mortality rates for the various tumors varied considerably among sexes and strains. The results suggest that in general susceptibility is determined by the control incidence. The relative risk model was significantly superior in five of the tumor types: lung, breast, liver, ovary, and adrenal. Both models appeared to fit myeloid leukemia and Harderian gland tumors, and neither provided good fits for thymic lymphoma and reticulum cell sarcoma. When risk estimates of radiation-induced tumors in humans and mice were compared, it was found that the relative risk estimates for lung, breast, and leukemia were not significantly different between humans and mice. In the case of liver tumors, mice had a higher risk than humans. These results indicate that the relative risk model is the appropriate approach for risk estimation for a number of tumors. The apparent concordance of relative risk estimates between humans and mice for the small number of cancers examined encourages us to undertake further studies.

Storer, J.B.; Mitchell, T.J.; Fry, R.J.

1988-05-01

291

Evaluating the mutagenic potential of chemicals. The minimal battery and extrapolation problems  

Energy Technology Data Exchange (ETDEWEB)

Adequate regulations to restrict exposure to chemical mutagens require recognition and evaluation of mutagenic activity. For this purpose a qualitative and an extrapolation phase can be distinguished. For the qualitative phase, the minimal battery should consist of at least three tests, that is: tests for gene- or point mutations in bacteria with and without metabolic activation; two tests for point mutations in eukaryotes, or one such test and a test for the detection of chromosome aberrations in mammalian cells in vitro. Depending on experience and facilities, a choice of two can be made out of the following four test systems: Tests for point mutations in mammalian cells in vitro, with and without metabolic activation; the sex-linked recessive lethal test with Drosophila melanogaster; tests with yeast, Saccharomyces cerevisiae, for point mutations, tests for chromosome aberrations in mammalian cells in vitro. Two different metabolic activation systems should be employed. For further selection of more sensitive test systems, studies on comparative mutagenesis are considered important. A mammalian test for chromosome aberrations in vivo is not included in this minimal battery. The finding that the effective concentration for the production of chromosome breakage events differs from that required to induce point mutations will be briefly discussed. When mutagenic compounds are indispensible or, in the case of ubiquitous exposure, a quantification of risks becomes necessary and here one is confronted with many difficulties. Information on damage that is hard to measure directly can be obtained in an indirect way by comparison with end-points that can be determined experimentally, such as alkylation per nucleotide.

Sobels, F.H.

1980-11-01

292

Extrapolation of the relative risk of radiogenic neoplasms across mouse strains and to man  

International Nuclear Information System (INIS)

We have examined two interrelated questions: is the susceptibility for radiogenic cancer related to the natural incidence, and are the responses of cancer induction by radiation described better by an absolute or a relative risk model. Also, we have examined whether it is possible to extrapolate relative risk estimates across species, from mice to humans. The answers to these questions were obtained from determinations of risk estimates for nine neoplasms in female and male C3Hf/Bd and C57BL/6 Bd mice and from data obtained from previous experiments with female BALB/c Bd and RFM mice. The mice were exposed to 137Cs gamma rays at 0.4 Gy/min to doses of 0, 0.5, 1.0, or 2.0 Gy. When tumors that were considered the cause of death were examined, both the control and induced mortality rates for the various tumors varied considerably among sexes and strains. The results suggest that in general susceptibility is determined by the control incidence. The relative risk model was significantly superior in five of the tumor types: lung, breast, liver, ovary, and adrenal. Both models appeared to fit myeloid leukemia and Harderian gland tumors, and neither provided good fits for thymic lymphoma and reticulum cell sarcoma. When risk estimates of radiation-induced tumors in humans and mice were compared, it was found that the relative risk estimates for lung, breast, and leukemia were not significantly different between humans and mice. In the case of liver tumors, mice had a higher risk than humans. These results indicate that the relative risk model is the appropriate approach for risk estimation for a number of tumors. The apparent concordance of relative risk estimates between humans and mice for the small number of cancers examined encourages us to undertake further studies

1988-01-01

293

Extrapolated ranges and stopping cross-sections for alpha particles (0. 4 - 5. 5 MeV) in normal and cyclo-hydrocarbons. 1. Gases and vapours  

Energy Technology Data Exchange (ETDEWEB)

The stopping power and ranges of methane, ethane, ethene, n-propane, cyclopropane, n-butane, n-pentane, cyclopentane, n-hexane and benzene for /sup 241/Am alpha particles have been measured by the indirect method in which the residual energy is measured as a function of thickness of absorber traversed. Analytical expressions to allow numerical calculations of extrapolated ranges and the stopping cross-sections of the materials investigated are presented and the results are compared where possible with other published results. The standard error of presented range values is 1-2% and that of stopping cross-sections is 2-4%. This work supports the application of the Bragg rule for single and double bonded hydrocarbons.

Rezvani, M.; Watt, D.E.

1984-07-01

294

Extrapolation of short term observations to time periods relevant to the isolation of long lived radioactive waste. Results of a co-ordinated research project 1995-2000  

International Nuclear Information System (INIS)

This report addresses safety analysis of the whole repository life-cycle that may require long term performance assessment of its components and evaluation of potential impacts of the facility on the environment. Generic consideration of procedures for the development of predictive tools are completed by detailed characterization of selected principles and methods that were applied and presented within the co-ordinated research project (CRP). The project focused on different approaches to extrapolation, considering radionuclide migration/sorption, physical, geochemical and geotechnical characteristics of engineered barriers, irradiated rock and backfill performance, and on corrosion of metallic and vitreous materials. This document contains a comprehensive discussion of the overall problem and the practical results of the individual projects preformed within the CRP. Each of the papers on the individual projects has been indexed separately

2000-01-01

295

Generation of Co{sub 3}O{sub 4} microparticles by solution combustion method and its Zn-Co{sub 3}O{sub 4} composite thin films for corrosion protection  

Energy Technology Data Exchange (ETDEWEB)

Graphical abstract: The pseudo-cubic cobalt oxide microparticles have been successfully synthesized by a solution combustion method using Co(NO{sub 3}){sub 2}{center_dot}6H{sub 2}O (oxidizer) and dextrose (sugar; fuel). The as-synthesized Co{sub 3}O{sub 4} microparticles are crystalline and Rietveld refinement of calcined samples exhibited cubic structure with space group of Fm3m (No. 227). The generated Co{sub 3}O{sub 4} microparticles were used to fabricate Zn-Co{sub 3}O{sub 4} composite thin films for corrosion protection. Highlights: Black-Right-Pointing-Pointer Synthesis of pseudo-cubic Co{sub 3}O{sub 4} microparticles by solution combustion method. Black-Right-Pointing-Pointer As-prepared Co{sub 3}O{sub 4} compounds are calcined and structurally characterized. Black-Right-Pointing-Pointer Prepared Co{sub 3}O{sub 4} are utilized for the fabrication of Zn-Co{sub 3}O{sub 4} composite thin films. - Abstract: Microcrystalline cobalt oxide (Co{sub 3}O{sub 4}) powder was successfully synthesized by a simple, fast, economical and eco-friendly solution-combustion method. The as-synthesized powder was calcined for an hour at temperatures ranging from 100 to 900 Degree-Sign C. The crystallite size, morphology, and chemical state of synthesized powders were characterized by powder XRD, TG-DTA, XPS, SEM/EDAX, TEM and FT-IR spectral methods. The as-synthesized Co{sub 3}O{sub 4} powder was single-crystalline and Rietveld refinement of calcined samples exhibited cubic structure with space group of Fm3m (No. 227). The effect of calcination temperature on crystallite size and morphology was assessed. Scanning electron micrographs show a uniform, randomly oriented pseudo-cubic particle with porous like morphology and EDAX measurement showed its chemical composition. Thermal behavior of as-synthesized compound was examined. The TEM result revealed that, the particles are pseudo-cubic in nature with diameter of 0.2-0.6 {mu}m and a length of 0.9-1.2 {mu}m. The crystallite size increased with increase of calcination temperature. The synthesized Co{sub 3}O{sub 4} powder was used to fabricate Zn-Co{sub 3}O{sub 4} composite thin films and its corrosion behavior was analyzed by anodic polarization, tafel extrapolation and electrochemical impedance spectroscopy. The results indicate that the Zn-Co{sub 3}O{sub 4} composite thin films have potential applications to corrosion protection.

Chandrappa, K.G. [Department of P.G. Studies and Research in Chemistry, School of Chemical Sciences, Jnana Sahyadri Campus, Kuvempu University, Shankaraghatta 577451, Karnataka (India); Venkatesha, T.V., E-mail: drtvvenkatesha@yahoo.co.uk [Department of P.G. Studies and Research in Chemistry, School of Chemical Sciences, Jnana Sahyadri Campus, Kuvempu University, Shankaraghatta 577451, Karnataka (India)

2012-11-25

296

Characterization of a extrapolation chamber in standard X-ray beam, radiodiagnosis level; Caracterizacao de uma camara de extrapolacao em feixes padroes de raios X, nivel radiodiagnostico  

Energy Technology Data Exchange (ETDEWEB)

The extrapolation chamber is a ionization chamber used for detection low energy radiation and can be used as an standard instrument for beta radiation beams. This type of ionization chamber have as main characteristic the variation of sensible volume. This paper performs a study of characterization of a PTW commercial extrapolation chamber, in the energy interval of the qualities of conventional radiodiagnostic

Silva, Eric A.B. da; Caldas, Linda V.E., E-mail: ebrito@usp.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-10-26

297

Extrapolation of the astrophysical S factor for $^{7}Be(p,\\gamma)^{8}B$ to solar energies  

CERN Document Server

We investigate the energy dependence of the astrophysical $S$ factor for the reaction $^7$Be$(p,\\gamma)^8$B, the primary source of high-energy solar neutrinos in the solar $pp$ chain. Using simple models we explore the model dependence in the extrapolation of the experimental data to the region of astrophysical interest near 20 keV. We find that below approximately 400 keV the energy dependence is very well understood and constrained by the data for the elastic scattering of low energy neutrons from $^7$Li. Above 400 keV nuclear distortion of the wave function of the incident proton introduces a significant model dependence. This is particularly important for the s-wave contribution to the $S$ factor. The extracted value of S(0) is $19.0 \\pm 1.0 of the theoretical error in the extrapolation.

Jennings, B K; Shoppa, T D

1998-01-01

298

Some new aspects of comparison of cell survival-dose curves (statistical analysis and extrapolation number modification factor)  

International Nuclear Information System (INIS)

The formulae are presented permitting to calculate, by the regression analysis, the values of n, D0, Dsub(q1, D37, D50, etc., and D0MF,Dsub(q)MF, D37MF, D50MF, etc., and their errors. The ratios between different doses and DMF were determined. It seemed expedient to use the variance analysis in determining the linearity of exponential parts of the dose-survival curves in the lg S-D coordinates, and the parallelism between them. Eight variants of changes in the main parameters of the dose-survival curves are discussed. New indices are proposed: the extrapolation number modification factor and the extrapolation number logarithm modification factor; the expedience of using thereof is reasoned

1982-01-01

299

Short-Term Forecasting of Urban Storm Water Runoff in Real-Time using Extrapolated Radar Rainfall Data  

DEFF Research Database (Denmark)

Model based short-term forecasting of urban storm water runoff can be applied in realtime control of drainage systems in order to optimize system capacity during rain and minimize combined sewer overflows, improve wastewater treatment or activate alarms if local flooding is impending. A novel online system, which forecasts flows and water levels in real-time with inputs from extrapolated radar rainfall data, has been developed. The fully distributed urban drainage model includes auto-calibration using online in-sewer measurements which is seen to improve forecast skills significantly. The radar rainfall extrapolation (nowcast) limits the lead time of the system to two hours. In this paper, the model set-up is tested on a small urban catchment for a period of 1.5 years. The 50 largest events are presented.

Thorndahl, Søren Liedtke; Rasmussen, Michael R.

2013-01-01

300

Characterization of an extrapolation chamber and radiochromic films for verifying the metrological coherence among beta radiation fields  

International Nuclear Information System (INIS)

The metrological coherence among standard systems is a requirement for assuring the reliability of dosimetric quantities measurements in ionizing radiation field. Scientific and technologic improvements happened in beta radiation metrology with the installment of the new beta secondary standard BSS2 in Brazil and with the adoption of the internationally recommended beta reference radiations. The Dosimeter Calibration Laboratory of the Development Center for Nuclear Technology (LCD/CDTN), in Belo Horizonte, implemented the BSS2 and methodologies are investigated for characterizing the beta radiation fields by determining the field homogeneity, the accuracy and uncertainties in the absorbed dose in air measurements. In this work, a methodology to be used for verifying the metrological coherence among beta radiation fields in standard systems was investigated; an extrapolation chamber and radiochromic films were used and measurements were done in terms of absorbed dose in air. The reliability of both the extrapolation chamber and the radiochromic film was confirmed and their calibrations were done in the LCD/CDTN in 90Sr/90Y, 85Kr and 147Pm beta radiation fields. The angular coefficients of the extrapolation curves were determined with the chamber; the field mapping and homogeneity were obtained from dose profiles and isodose with the radiochromic films. A preliminary comparison between the LCD/CDTN and the Instrument Calibration Laboratory of the Nuclear and Energy Research Institute / Sao Paulo (LCI/IPEN) was carried out. Results with the extrapolation chamber measurements showed in terms of absorbed dose in air rates showed differences between both laboratories up to de -I % e 3%, for 90Sr/90Y, 85Kr and 147Pm beta radiation fields, respectively. Results with the EBT radiochromic films for 0.1, 0.3 and 0.15 Gy absorbed dose in air, for the same beta radiation fields, showed differences up to 3%, -9% and -53%. The beta radiation field mappings with radiochromic films in both BSS2 showed that some of them were not geometrically aligned. (author)

2011-01-01

 
 
 
 
301

Negative dimensional group extrapolation and a new Chiral-Nonchiral duality in N=1 supersymmetric gauge theories  

CERN Document Server

By extrapolating the groups to the negative dimensions in the model found by Pouliot and Strassler we find a new chiral-nonchiral duality. The electric theory is N=1 supersymmetric SU(N+4) gauge theory with N antifundamentals and an antisymmetric tensor and the magnetic theory is N=1 supersymmetric Spin(8) gauge theory with N fundamentals, a spinor and singlets. Operator mapping, anomaly matching and superpotential deformation are disscussed.

Maru, N

1996-01-01

302

Far Field Extrapolation from Near Field Interactions and Shielding Influence Investigations Based on a FE-PEEC Coupling Method  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Regarding standards, it is well established that common mode currents are the main source of far field emitted by variable frequency drive (VFD)-cable-motor associations. These currents are generated by the combination of floating potentials with stray capacitances between these floating potential tracks and the mechanical parts connected to the earth (the heatsink or cables are usual examples). Nowadays, due to frequency and power increases, the systematic compliance to EMC (ElectroMagnetic ...

2013-01-01

303

Characterization of an extrapolation chamber for low-energy X-rays: Experimental and Monte Carlo preliminary results  

Energy Technology Data Exchange (ETDEWEB)

The extrapolation chamber is a parallel-plate ionization chamber that allows variation of its air-cavity volume. In this work, an experimental study and MCNP-4C Monte Carlo code simulations of an ionization chamber designed and constructed at the Calibration Laboratory at IPEN to be used as a secondary dosimetry standard for low-energy X-rays are reported. The results obtained were within the international recommendations, and the simulations showed that the components of the extrapolation chamber may influence its response up to 11.0%. - Highlights: Black-Right-Pointing-Pointer A homemade extrapolation chamber was studied experimentally and with Monte Carlo. Black-Right-Pointing-Pointer It was characterized as a secondary dosimetry standard, for low energy X-rays. Black-Right-Pointing-Pointer Several characterization tests were performed and the results were satisfactory. Black-Right-Pointing-Pointer Simulation showed that its components may influence the response up to 11.0%. Black-Right-Pointing-Pointer This chamber may be used as a secondary standard at our laboratory.

Neves, Lucio P., E-mail: lpneves@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000 Sao Paulo, SP (Brazil); Silva, Eric A.B., E-mail: ebrito@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000 Sao Paulo, SP (Brazil); Perini, Ana P., E-mail: aperini@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000 Sao Paulo, SP (Brazil); Maidana, Nora L., E-mail: nmaidana@if.usp.br [Universidade de Sao Paulo, Instituto de Fisica, Travessa R 187, 05508-900 Sao Paulo, SP (Brazil); Caldas, Linda V.E., E-mail: lcaldas@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000 Sao Paulo, SP (Brazil)

2012-07-15

304

Extrapolation to a demonstration reactor from the ITER and advanced physics and materials data bases. Demo and commercial fusion reactors extrapolated from the ITER and advanced physics and materials data bases. Radioactive waste produced by demo and commercial fusion reactors extrapolated from ITER and advanced data bases  

International Nuclear Information System (INIS)

The report contains 2 papers. In the first paper, the characteristics of demonstration (DEMO) reactors that could be conservatively extrapolated from the data base that will be provided by ITER and its supporting R ampersand D and from a data base supplemented by advanced physics and advanced materials R ampersand D programs are identified. In the second paper, the radioactive wastes that would be produced in demonstration (DEMO) and commercial (CFR) fusion reactors which could be extrapolated from the design data base that will be provided by ITER and its supporting R ampersand D and from a design data base supplemented by advanced physics and advanced materials R ampersand D programs are identified and characterized in terms of a number of possible criteria for near-surface burial. The results indicate that there is a possibility that all fusion wastes could satisfy a 'low level' waste criterion for 'near-surface' burial

1994-01-01

305

Parameter extrapolation to ungauged basins with a hydrological distributed model in a regional framework  

Directory of Open Access Journals (Sweden)

Full Text Available A Regional Water Resources study was performed at basins within and draining to the Basque Country Region (N of Spain, with a total area of approximately 8500 km2. The objective was to obtain daily and monthly long-term discharges in 567 points, most of them ungauged, with basin areas ranging from 0.25 to 1850 km2. In order to extrapolate the calibrations at gauged points to the ungauged ones, a distributed and conceptually based model called TETIS was used. In TETIS the runoff production is modelled using five linked tanks at the each cell with different outflow relationships at each tank, which represents the main hydrological processes as snowmelt, evapotranspiration, overland flow, interflow and base flow. The routing along the channels' network couples its geomorphologic characteristics with the kinematic wave approach. The parameter estimation methodology tries to distinguish between the effective parameter used in the model at the cell scale, and the watershed characteristic estimated from the available information, being the best estimation without losing its physical meaning. The relationship between them can be considered as a correction function or, in its simple form, a correction factor. The correction factor can take into account the model input errors, the temporal and spatial scale effects and the watershed characteristics. Therefore, it is reasonable to assume the correction factor is the same for each parameter to all cells within the watershed. This approach reduces drastically the number of parameter to be calibrated, because only the common correction factors are calibrated instead of parameter maps (number of parameters times the number of cells. In this way, the calibration can be performed using automatic methodologies. In this work, the Shuffled Complex Evolution – University of Arizona, SCE-UA algorithm was used. The available recent year's data was used to calibrate the model in 20 of the most representative flow gauge stations in 18 basins with a Nash-Sutcliffe index higher than 0.6 (10 higher than 0.8. The calibrated correction factors at each basin were similar but not equal. The validation process (in time and space was performed using the remaining data in all flow gauge stations (62, with 42 basins with a Nash-Sutcliffe index higher than 0.5 (25 higher than 0.7. Deficient calibration and validations were always related with flow gauge stations very close to the karstic springs. These results confirmed that it was feasible and efficient to use the SCE-UA algorithm for the automatic calibration of distributed conceptual models and the calibrated model could be used at ungauged basins. Finally, meteorological information from the past 50 years at a daily scale was used to generate a daily discharges series at 567 selected points.

J. J. Vélez

2009-02-01

306

Parameter extrapolation to ungauged basins with a hydrological distributed model in a regional framework  

Directory of Open Access Journals (Sweden)

Full Text Available A Regional Water Resources study was performed at basins within and draining to the Basque Country Region (N of Spain, with a total area of approximately 8500 km2. The objective was to obtain daily and monthly long-term discharges in 567 points, most of them ungauged, with basin areas ranging from 0.25 to 1850 km2. In order to extrapolate the calibrations at gauged points to the ungauged ones, a distributed and conceptually based model called TETIS was used. In TETIS the runoff production is modelled using five linked tanks at each cell with different outflow relationships at each tank, which represents the main hydrological processes as snowmelt, evapotranspiration, surface runoff, interflow and base flow. The routing along the channels' network couples its geomorphologic characteristics with the kinematic wave approach. The parameter estimation methodology tries to distinguish between the effective parameter used in the model at cell scale, and the watershed characteristic estimated from the available information, being the best estimation without losing its physical meaning. The relationship between them can be considered as a correction function or, in its simple form, a correction factor. The correction factor can take into account the model input errors, the temporal and spatial scale effects and the watershed characteristics. Therefore, it is reasonable to assume the correction factor is the same for each parameter to all cells within the watershed. This approach reduces dramatically the number of parameter to be calibrated, because only the common correction factors are calibrated instead of parameter maps (number of parameters times the number of cells. In this way, the calibration can be performed using automatic methodologies. In this work, the Shuffled Complex Evolution – University of Arizona, SCE-UA algorithm was used. The available recent year's data was used to calibrate the model in 20 of the most representative flow gauge stations in 18 basins with a Nash-Sutcliffe index higher than 0.6 (10 higher than 0.8. The calibrated correction factors at each basin were similar but not equal. The validation process (in time and space was performed using the remaining data in all flow gauge stations (62, with 42 basins with a Nash-Sutcliffe index higher than 0.5 (25 higher than 0.7. Deficient calibration and validations were always related with flow gauge stations very close to the karstic springs. These results confirmed that it was feasible and efficient to use the SCE-UA algorithm for the automatic calibration of distributed conceptual models and the calibrated model could be used at ungauged basins. Finally, meteorological information from the past 50 years at a daily scale was used to generate a daily discharges series at 567 selected points.

J. J. Vélez

2007-04-01

307

Diagnostic, Explanatory, and Detection Models of Munchausen by Proxy: Extrapolations from Malingering and Deception  

Science.gov (United States)

Objective: The overriding objective is a critical examination of Munchausen syndrome by proxy (MSBP) and its closely-related alternative, factitious disorder by proxy (FDBP). Beyond issues of diagnostic validity, assessment methods and potential detection strategies are explored. Methods: A painstaking analysis was conducted of the MSBP and FDBP…

Rogers, Richard

2004-01-01

308

Is the climate right for pleistocene rewilding? Using species distribution models to extrapolate climatic suitability for mammals across continents.  

Science.gov (United States)

Species distribution models (SDMs) are increasingly used for extrapolation, or predicting suitable regions for species under new geographic or temporal scenarios. However, SDM predictions may be prone to errors if species are not at equilibrium with climatic conditions in the current range and if training samples are not representative. Here the controversial "Pleistocene rewilding" proposal was used as a novel example to address some of the challenges of extrapolating modeled species-climate relationships outside of current ranges. Climatic suitability for three proposed proxy species (Asian elephant, African cheetah and African lion) was extrapolated to the American southwest and Great Plains using Maxent, a machine-learning species distribution model. Similar models were fit for Oryx gazella, a species native to Africa that has naturalized in North America, to test model predictions. To overcome biases introduced by contracted modern ranges and limited occurrence data, random pseudo-presence points generated from modern and historical ranges were used for model training. For all species except the oryx, models of climatic suitability fit to training data from historical ranges produced larger areas of predicted suitability in North America than models fit to training data from modern ranges. Four naturalized oryx populations in the American southwest were correctly predicted with a generous model threshold, but none of these locations were predicted with a more stringent threshold. In general, the northern Great Plains had low climatic suitability for all focal species and scenarios considered, while portions of the southern Great Plains and American southwest had low to intermediate suitability for some species in some scenarios. The results suggest that the use of historical, in addition to modern, range information and randomly sampled pseudo-presence points may improve model accuracy. This has implications for modeling range shifts of organisms in response to climate change. PMID:20877563

Richmond, Orien M W; McEntee, Jay P; Hijmans, Robert J; Brashares, Justin S

2010-01-01

309

Extrapolation chamber mounted on perspex for calibration of high energy photon and electron beams from a clinical linear accelerator  

Directory of Open Access Journals (Sweden)

Full Text Available The objective of the present study is to establish radiation standards for absorbed doses, for clinical high energy linear accelerator beams. In the nonavailability of a cobalt-60 beam for arriving at Nd, water values for thimble chambers, we investigated the efficacy of perspex mounted extrapolation chamber (EC used earlier for low energy x-rays and beta dosimetry. Extrapolation chamber with facility for achieving variable electrode separations 10.5mm to 0.5mm using micrometer screw was used for calibrations. Photon beams 6 MV and 15 MV and electron beams 6 MeV and 15 MeV from Varian Clinac linacs were calibrated. Absorbed Dose estimates to Perspex were converted into dose to solid water for comparison with FC 65 ionisation chamber measurements in water. Measurements made during the period December 2006 to June 2008 are considered for evaluation. Uncorrected ionization readings of EC for all the radiation beams over the entire period were within 2% showing the consistency of measurements. Absorbed doses estimated by EC were in good agreement with in-water calibrations within 2% for photons and electron beams. The present results suggest that extrapolation chambers can be considered as an independent measuring system for absorbed dose in addition to Farmer type ion chambers. In the absence of standard beam quality (Co-60 radiations as reference Quality for Nd,water the possibility of keeping EC as Primary Standards for absorbed dose calibrations in high energy radiation beams from linacs should be explored. As there are neither Standard Laboratories nor SSDL available in our country, we look forward to keep EC as Local Standard for hospital chamber calibrations. We are also participating in the IAEA mailed TLD intercomparison programme for quality audit of existing status of radiation dosimetry in high energy linac beams. The performance of EC has to be confirmed with cobalt-60 beams by a separate study, as linacs are susceptible for minor variations in dose output on different days.

Ravichandran R

2009-01-01

310

Application of physiologically-based toxicokinetic modelling in oral-to-dermal extrapolation of threshold doses of cosmetic ingredients.  

Science.gov (United States)

The application of physiologically based toxicokinetic (PBTK) modelling in route-to-route (RtR) extrapolation of three cosmetic ingredients: coumarin, hydroquinone and caffeine is shown in this study. In particular, the oral no-observed-adverse-effect-level (NOAEL) doses of these chemicals are extrapolated to their corresponding dermal values by comparing the internal concentrations resulting from oral and dermal exposure scenarios. The PBTK model structure has been constructed to give a good simulation performance of biochemical processes within the human body. The model parameters are calibrated based on oral and dermal experimental data for the Caucasian population available in the literature. Particular attention is given to modelling the absorption stage (skin and gastrointestinal tract) in the form of several sub-compartments. This gives better model prediction results when compared to those of a PBTK model with a simpler structure of the absorption barrier. In addition, the role of quantitative structure-property relationships (QSPRs) in predicting skin penetration is evaluated for the three substances with a view to incorporating QSPR-predicted penetration parameters in the PBTK model when experimental values are lacking. Finally, PBTK modelling is used, first to extrapolate oral NOAEL doses derived from rat studies to humans, and then to simulate internal systemic/liver concentrations - Area Under Curve (AUC) and peak concentration - resulting from specified dermal and oral exposure conditions. Based on these simulations, AUC-based dermal thresholds for the three case study compounds are derived and compared with the experimentally obtained oral threshold (NOAEL) values. PMID:24731971

Gajewska, M; Worth, A; Urani, C; Briesen, H; Schramm, K-W

2014-06-16

311

Extrapolation of contrail investigations by LIDAR to larger scale measurements. Analysis and calibration of CCD camera and satellite images  

Energy Technology Data Exchange (ETDEWEB)

The CCD image of a persistent contrail and the coincident LIDAR measurement are presented. To extrapolate the LIDAR derived optical thickness to the video field of view an anisotropy correction and calibration has to be performed. Observed bright halo components result from highly regular oriented hexagonal crystals with sizes of 200 {mu}m-2 mm. This explained by measured ambient humidities below the formation threshold of natural cirrus. Optical thickness from LIDAR shows significant discrepancies to the result from coincident NOAA-14 data. Errors result from anisotropy correction and parameterized relations between AVHRR channels and optical properties. (author) 28 refs.

Sussmann, R.; Homburg, F.; Freudenthaler, V.; Jaeger, H. [Frauenhofer Inst. fuer Atmosphaerische Umweltforschung, Garmisch-Partenkirchen (Germany)

1997-12-31

312

Estimated UV clutter levels at 10-100 meter sensor pixel resolution extrapolated from recent Polar Bear measurements  

International Nuclear Information System (INIS)

This paper describes the methodology and the results obtained at 1304 A wavelength from an analysis of the AFGL Polar Bear experiment. The basic measurement equipment provided data of a spatial resolution of 20 km over a large portion of the earth. The instrumentation also provided sampled outputs as the footprint scanned along the measurement track. The combination of the fine scanning and large area coverage provided opportunity for a spatial power spectral analysis that in turn provided a means for extrapolation to finer spatial scale

1989-08-07

313

Method Development to Evaluate the Oxygen Reduction Activity of High-Surface-Area Catalysts for Li-Air Batteries  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study presents a new method to quantitatively determine the electrocatalytic activity of Vulcan carbon and Vulcan-supported Au nanoparticles, dispersed as catalyst thin films on glass carbon, for oxygen reduction in an aprotic electrolyte using rotating disk electrode measurements. The ORR activity of Vulcan carbon can be described by a Tafel slope of 120 mV/dec and Levich-Koutecky analysis of Vulcan carbon suggests that solvated LiO[subscript 2] is the initially formed O[subscript 2] re...

Lu, Yi-chun; Gasteiger, Hubert A.; Shao-horn, Yang

2010-01-01

314

Accurate molecular energies by extrapolation of atomic energies using an analytic quantum mechanical model  

CERN Document Server

Using a new analytic quantum mechanical method based on Slater's Xalpha method, we show that a fairly accurate estimate of the total energy of a molecule can be obtained from the exact energies of its constituent atoms. The mean absolute error in the total energies thus determined for the G2 set of 56 molecules is about 16 kcal/mol, comparable to or better than some popular pure and hybrid density functional models.

Zope, R R; Zope, Rajendra R.; Dunlap, Brett I.

2005-01-01

315

Verification of electricity savings through energy-efficient train management - Measurements made on trains and extrapolations - Annex 3; Verifizierung der Stromeinsparung durch energieeffizientes Zugsmanagement - Anhang 3: Messungen auf Fahrzeugen und Hochrechnungen  

Energy Technology Data Exchange (ETDEWEB)

This appendix to a final report for the Swiss Federal Office of Energy (SFOE) presents the results of measurements made on trains and presents and discusses extrapolations made on the basis of these measurements. The evaluation and selection of the trains on which the measurements were to be made is discussed. Mainly passenger trains were selected as only few goods engines have the necessary equipment and equipping them would be costly. Measurements made on a Re 460 locomotive are presented and discussed. The methods used in the energy analysis are described and the results obtained on several itineraries that include partial single-track working are presented and discussed.

Meyer, M.; Lerjen, M.; Menth, S. [emkamatik GmbH, Wettingen (Switzerland); Luethi, M. [Swiss Federal Insitute of Technology (ETHZ), Institute for Transport Planning and Systems (IVT), Zuerich (Switzerland); Tuchschmid, M. [SBB AG, BahnUmwelt-Center, 3000 Bern (Switzerland)

2009-11-15

316

Rarefaction and Extrapolation with Hill Numbers: A Framework for Sampling and Estimation in Species Diversity Studies  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Quantifying and assessing changes in biological diversity are central aspects of many ecological studies, yet accurate methods of estimating biological diversity from sampling data have been elusive. Hill numbers, or the effective number of species, are increasingly used to characterize the taxonomic, phylogenetic or functional diversity of an assemblage. However, empirical estimates of Hill numbers, including species richness, tend to be an increasing function of sampling effort and thus ten...

2013-01-01

317

Imaging of defects in girth welds using inverse wave field extrapolation of ultrasonic data:  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Ultrasonic non-destructive testing is a renowned method for the inspection of girth welds. However, defect sizing and characterization remains challenging with the current inspection philosophy. In addition, data display and interpretation is not straightforward and requires skill and experience from the inspector. A better and more reliable inspection result would contribute to safer pipeline construction and economic benefits (like low false call rates and the possibility to use smaller wal...

Po?rtzgen, N.

2007-01-01

318

Ecosystem modelling of the cycling of marine dimethylsulfide : a review of current approaches and of the potential for extrapolation to global scales  

Energy Technology Data Exchange (ETDEWEB)

Oceanic and atmospheric scientists are interested in the possible role of dimethyl sulfide (DMS) in regulating global climate. DMS is the most abundant volatile organic sulfur compound produced by the ocean. It is derived from biological activity and is the key source of non-sea-salt sulfate aerosols over the ocean. Ecosystem models of marine sulfur cycling can explain how DMS is regulated and how it might respond to climate change. The models consider both spatial/temporal scales and regional/global simulations driven by ocean general circulation models. This paper reviewed ecosystem modelling of carbon and nitrogen dynamics with particular attention to some of their commonalities. Currently, the empirical approach is widely used to extrapolate DMS cycling and fluxes to the global scale. This paper presented a semiempirical method based on a simple ecosystem model. It can reproduce gross features of the global distribution of DMS on surface waters. It can also provide the basis for future modelling of marine sulfur fluxes to the atmosphere. 44 refs., 3 tabs., 3 figs.

Vezina, A.F. [Department of Fisheries and Oceans, Dartmouth, NS (Canada). Bedford Inst. of Oceanography

2004-05-01

319

Extrapolation of Urn Models via Poissonization: Accurate Measurements of the Microbial Unknown  

CERN Document Server

The availability of high-throughput parallel methods for sequencing microbial communities is increasing our knowledge of the microbial world at an unprecedented rate. Though most attention has focused on determining lower-bounds on the alpha-diversity i.e. the total number of different species present in the environment, tight bounds on this quantity may be highly uncertain because a small fraction of the environment could be composed of a vast number of different species. To better assess what remains unknown, we propose instead to predict the fraction of the environment that belongs to unsampled classes. Modeling samples as draws with replacement of colored balls from an urn with an unknown composition, and under the sole assumption that there are still undiscovered species, we show that conditionally unbiased predictors and exact prediction intervals (of constant length in logarithmic scale) are possible for the fraction of the environment that belongs to unsampled classes. Our predictions are based on a P...

Lladser, Manuel; Reeder, Jens; 10.1371/journal.pone.0021105

2011-01-01

320

Ferromagnetic Potts model in a magnetic field: Finite lattice extrapolation of the (1+1)-dimensional Hamiltonian  

International Nuclear Information System (INIS)

The (1+1)-dimensional Hamiltonian q-state ferromagnetic Potts model in an external magnetic field H is studied using finite lattice extrapolation techniques. The possible phases and their boundaries are determined from the ground state energy and the gap in the excitation energy, for arbitrary values of q and both for positive and negative field. We found that, for H positive, there is a critical value qc, where a first order transition line appears for q>qc, starting at the zero field transition point and terminating at a critical point in (h/?, H/?) plane, which separates the disordered phase and the ordered phase in the direction of H. For h negative a critical transition line separating the disordered phase and the others (q-1) ordered phases becomes first order for q>qc. (author). 12 refs, 2 figs

1994-01-01

 
 
 
 
321

Full-disk nonlinear force-free field extrapolation of SDO/HMI and SOLIS/VSM magnetograms  

CERN Document Server

Extrapolation codes in Cartesian geometry for modelling the magnetic field in the corona do not take the curvature of the Sun's surface into account and can only be applied to relatively small areas, e.g., a single active region. We compare the analysis of the photospheric magnetic field and subsequent force-free modeling based on full-disk vector maps from Helioseismic and Magnetic Imager (HMI) on board solar dynamics observatory (SDO) and Vector Spectromagnetograph (VSM) of the Synoptic Optical Long-term Investigations of the Sun (SOLIS). We use Helioseismic and Magnetic Imager and Vector Spectromagnetograph photospheric magnetic field measurements to model the force-free coronal field above multiple solar active regions, assuming magnetic forces to dominate. We solve the nonlinear force-free field equations by minimizing a functional in spherical coordinates over a full disk excluding the poles. After searching for the optimum modeling parameters for the particular data sets, we compare the resulting nonli...

Tadesse, Tilaye; Inhester, B; MacNeice, P; Pevtsov, A; Sun, X

2012-01-01

322

Hematological responses after inhaling {sup 238}PuO{sub 2}: An extrapolation from beagle dogs to humans  

Energy Technology Data Exchange (ETDEWEB)

The alpha emitter plutonium-238 ({sup 238}Pu), which is produced in uranium-fueled, light-water reactors, is used as a thermoelectric power source for space applications. Inhalation of a mixed oxide form of Pu is the most likely mode of exposure of workers and the general public. Occupational exposures to {sup 238}PuO{sub 2} have occurred in association with the fabrication of radioisotope thermoelectric generators. Organs and tissue at risk for deterministic and stochastic effects of {sup 238}Pu-alpha irradiation include the lung, liver, skeleton, and lymphatic tissue. Little has been reported about the effects of inhaled {sup 238}PuO{sub 2} on peripheral blood cell counts in humans. The purpose of this study was to investigate hematological responses after a single inhalation exposure of Beagle dogs to alpha-emitting {sup 238}PuO{sub 2} particles and to extrapolate results to humans.

Scott, B.R.; Muggenburg, B.A.; Welsh, C.A.; Angerstein, D.A.

1994-11-01

323

Extrapolating population size from the occupancy-abundance relationship and the scaling pattern of occupancy  

DEFF Research Database (Denmark)

The estimation of species abundances at regional scales requires a cost-efficient method that can be applied to existing broadscale data. We compared the performance of eight models for estimating species abundance and community structure from presence-absence maps of the southern African avifauna. Six models were based on the intraspecific occupancy-abundance relationship (OAR); the other two on the scaling pattern of species occupancy (SPO), which quantifies the decline in species range size when measured across progressively finer scales. The performance of these models was examined using five tests: the first three compared the predicted community structure against well-documented macroecological patterns; the final two compared published abundance estimates for rare species and the total regional abundance estimate against predicted abundances. Approximately two billion birds were estimated as occurring in South Africa, Lesotho, and Swaziland. SPO models outperformed the OAR models, due to OAR models assuming environmental homogeneity and yielding scale-dependent estimates. Therefore, OAR models should only be applied across small, homogenous areas. By contrast, SPO models are suitable for data at larger spatial scales because they are based on the scale dependence of species range size and incorporate environmental heterogeneity (assuming fractal habitat structure or performing a Bayesian estimate of occupancy). Therefore, SPO models are recommended for assemblage-scale regional abundance estimation based on spatially explicit presence-absence data.

Hui, Cang; McGeoch, Melodie A.

2009-01-01

324

Phase shift analysis of ?? system at energies between 500 and 1370 MeV with Chew-Low extrapolation results from reactions ?-p?p?-?0 and ?-p?n?+?- at 3.92 GeV/c  

International Nuclear Information System (INIS)

Experimental data (12 evts/?N???N reactions) were derived from the analysis of 450000 pictures obtained with the 2 meter hydrogen bubble chamber at CERN. The Chew-Low extrapolation method was used to obtain total and differential cross-sections of ?+0?-??+0?- reactions. Pseudo-peripherism hypothesis, in agreement with data at energy less 1 GeV, was modified to take into account the non-vanishing reactions amplitude at t=0, observed above 1 GeV. Several phase shift analyses were done, either with energy parametrisation of phase shifts, or at fixed energy. Main results concern the parameters of S* (Jsup(P)=0+) resonance which come out from a meromorphic parametrisation of the S0 wave amplitude in the region of the KantiK channel threshold (987 MeV) and the dynamical wave structures in the f0 (Jsup(P)=2+) resonance region. The agreement observed between these results and those of main previous experiments is a proof of the usefulness of the extrapolation method above 1 GeV

1980-01-01

325

Extrapolation of Normal Tissue Complication Probability for Different Fractionations in Liver Irradiation  

International Nuclear Information System (INIS)

Purpose: The ability to predict normal tissue complication probability (NTCP) is essential for NTCP-based treatment planning. The purpose of this work is to estimate the Lyman NTCP model parameters for liver irradiation from published clinical data of different fractionation regimens. A new expression of normalized total dose (NTD) is proposed to convert NTCP data between different treatment schemes. Method and Materials: The NTCP data of radiation- induced liver disease (RILD) from external beam radiation therapy for primary liver cancer patients were selected for analysis. The data were collected from 4 institutions for tumor sizes in the range of of 8-10 cm. The dose per fraction ranged from 1.5 Gy to 6 Gy. A modified linear-quadratic model with two components corresponding to radiosensitive and radioresistant cells in the normal liver tissue was proposed to understand the new NTD formalism. Results: There are five parameters in the model: TD50, m, n, ?/? and f. With two parameters n and ?/? fixed to be 1.0 and 2.0 Gy, respectively, the extracted parameters from the fitting are TD50(1) = 40.3 ± 8.4Gy, m =0.36 ± 0.09, f = 0.156 ± 0.074 Gy and TD50(1) = 23.9 ± 5.3Gy, m = 0.41 ± 0.15, f = 0.0 ± 0.04 Gy for patients with liver cirrhosis scores of Child-Pugh A and Child-Pugh B, respectively. The fitting results showed that the liver cirrhosis score significantly affects fractional dose dependence of NTD. Conclusion: The Lyman parameters generated presently and the new form of NTD may be used to predict NTCP for treatment planning of innovative liver irradiation with different fractionations, such as hypofractioned stereotactic body radiation therapy.

2009-05-01

326

Corrosion and corrosion control of mild steel in concentrated H{sub 2}SO{sub 4} solutions by a newly synthesized glycine derivative  

Energy Technology Data Exchange (ETDEWEB)

Graphical abstract: Display Omitted Research highlights: GlyD1 exhibits inhibiting properties more than GlyD2 and Gly. Inhibition efficiency increases with inhibitor concentration. Inhibition efficiency decreases with temperature, suggesting physical adsorption. Validation of corrosion rates measured by Tafel extrapolation method is confirmed. - Abstract: A newly synthesized glycine derivative (GlyD1), 2-(4-(dimethylamino)benzylamino)acetic acid hydrochloride, was used to control mild steel corrosion in 4.0 M H{sub 2}SO{sub 4} solutions at different temperatures (278-338 K). Tafel extrapolation, linear polarization resistance (LPR) and impedance methods were used to test corrosion inhibitor efficiency. An independent method of chemical analysis, namely ICP-AES (inductively coupled plasma atomic emission spectrometry) was also used to test validity of corrosion rate measured by Tafel extrapolation method. Results obtained were compared with an available glycine derivative (GlyD2) and glycine (Gly). Tafel polarization measurements revealed that the three tested inhibitors function as mixed-type compounds. The inhibition efficiency increased with increase in inhibitor concentration and decreased with temperature, suggesting the occurrence of physical adsorption. The adsorptive behaviour of the three inhibitors followed Temkin-type isotherm and the standard free energy changes of adsorption ({Delta}G{sub ads}{sup o}) were evaluated for the three tested inhibitors as a function of temperature. The inhibition performance of GlyD1 was much better than those of GlyD2 and Gly itself. Results obtained from the different corrosion evaluation techniques were in good agreement.

Amin, Mohammed A., E-mail: maaismail@yahoo.co [Department of Chemistry, Faculty of Science, Ain Shams University, Abbassia, Cairo 11566 (Egypt); Materials and Corrosion Lab (MCL), Department of Chemistry, Faculty of Science, Taif University, 888 Hawiya (Saudi Arabia); Ibrahim, Mohamed M. [Department of Chemistry, Faculty of Science, Kafr El-Sheikh University, Kafr El-Sheikh 33516 (Egypt); Materials and Corrosion Lab (MCL), Department of Chemistry, Faculty of Science, Taif University, 888 Hawiya (Saudi Arabia)

2011-03-15

327

A preliminary result of calculation of Extrapolated-to-Zero-Mesh-Size Solution (EZMSS) of the Second AER Kinetic benchmark with finite - difference code MAG  

International Nuclear Information System (INIS)

A preliminary result of calculation of Extrapolated-to-Zero-Mesh-Size Solution (EZMSS) for the Second AER Kinetic benchmark is presented. Calculation has been made with the code MAG. The standard MCFD (mesh - center finite difference) approximation in ?-Z geometry has been used for space approximation. The mesh refinement technique with h"2 - extrapolation has been used to calculate EXMSS and to evaluate its accuracy. The preliminary result shows a significant difference with all known to author solutions generated earlier by nodal codes, in particular with DYN3D reference solution. The only exception is BIPR8 solution that seems to be rather close to preliminary estimation of the EZMSS. (Authors)

2000-10-01

328

Time extrapolation aspects in the performance assessment of high and medium level radioactive waste disposal in the Boom Clay at Mol (Belgium)  

International Nuclear Information System (INIS)

SCK-CEN is studying the disposal of high and long-lived medium level waste in the Boom Clay at Mol, Belgium. In the performance assessment for such a repository time extrapolation is an inherent problem due to the extremely long half-life of some important radionuclides. To increase the confidence in these time extrapolations SCK-CEN applies a combination of different experimental and modelling approaches including laboratory and in situ experiments, natural analogue studies, deterministic (or mechanistic) models and stochastical models. An overview is given of these approaches and some examples of applications to the different repository system components are given. (author)

2000-09-01

329

Comparison of tropical and temperate freshwater animal species' acute sensitivities to chemicals: implications for deriving safe extrapolation factors.  

Science.gov (United States)

Toxicity data for tropical species are often lacking for ecological risk assessment. Consequently, tropical and subtropical countries use water quality criteria (WQC) derived from temperate species (e.g., United States, Canada, or Europe) to assess ecological risks in their aquatic systems, leaving an unknown margin of uncertainty. To address this issue, we use species sensitivity distributions of freshwater animal species to determine whether temperate datasets are adequately protective of tropical species assemblages for 18 chemical substances. The results indicate that the relative sensitivities of tropical and temperate species are noticeably different for some of these chemicals. For most metals, temperate species tend to be more sensitive than their tropical counterparts. However, for un-ionized ammonia, phenol, and some pesticides (e.g., chlorpyrifos), tropical species are probably more sensitive. On the basis of the results from objective comparisons of the ratio between temperate and tropical hazardous concentration values for 10% of species, or the 90% protection level, we recommend that an extrapolation factor of 10 should be applied when such surrogate temperate WQCs are used for tropical or subtropical regions and a priori knowledge on the sensitivity of tropical species is very limited or not available. PMID:17283595

Kwok, Kevin W H; Leung, Kenneth M Y; Lui, Gilbert S G; Chu, S Vincent K H; Lam, Paul K S; Morritt, David; Maltby, Lorraine; Brock, Theo C M; Van den Brink, Paul J; Warne, Michael St J; Crane, Mark

2007-01-01

330

Modeling approach to characterize intraocular doripenem pharmacokinetics after intravenous administration to rabbits, with tentative extrapolation to humans.  

Science.gov (United States)

The aim of this study was to determine the penetration of doripenem administered intravenously into the rabbit aqueous and vitreous humors. Nineteen New Zealand White rabbits received a 20-mg dose of doripenem intravenously over 60 min. Specimens of aqueous humor, vitreous humor, and blood were obtained 30 min (n = 5), 1 h (n = 5), 2 h (n = 5), and 3 h (n = 4) after the beginning of the infusion and analyzed by high-performance liquid chromatography (HPLC). A pharmacokinetic (PK) model was developed to fit the experimental data. Doripenem concentrations in aqueous humor were lower than those in plasma ultrafiltrates at all sampling times, with an average aqueous humor-to-plasma ultrafiltrate area under the concentration-time curve ratio estimated as 8.3%. A pharmacokinetic model with peripheral elimination described the data adequately and was tentatively used to predict concentration-versus-time profiles and pharmacokinetic-pharmacodynamic (PK-PD) target attainment in patients under various dosing regimens. In conclusion, systematically administered doripenem does not seem to be a promising approach for the treatment of intraocular infections, especially since it could not be detected in the vitreous humor. However, this study has provided an opportunity to develop a new PK modeling approach to characterize the intraocular distribution of doripenem administered intravenously to rabbits, with tentative extrapolation to humans. PMID:22526310

Semoun, Oudy; Marchand, Sandrine; Grégoire, Nicolas; Lamarche, Isabelle; Adier, Christophe; Laroche, Laurent; Goldschmidt, Pablo; Couet, William

2012-07-01

331

High-Accuracy Extrapolated ab Initio Thermochemistry of the Propargyl Radical and the Singlet C3H2 Carbenes  

Science.gov (United States)

Total atomization energies and enthalpies of formation (0 and 298.15 K) are evaluated using the high-accuracy extrapolated ab initio thermochemistry (HEAT) scheme for the two stable singlet C3H2 carbenes [cyclopropenylidene (c-C3H2) and propadienylidene (vinylidencarbene, l-C3H2)], as well as for the 2-propynyl (propargyl, C3H3) radical. In the case of propargyl, the HEAT protocol predicts an enthalpy of formation of 354.9 ± 1.0 kJ mol-1 for 0 K; corresponding values of 498.1 ± 1.0 and 555.6 ± 1.0 kJ mol-1 are estimated for c-C3H2 and l-C3H2. Additional consideration of temperature corrections leads to estimates of 352.2 ± 1.0, 497.1 ± 1.0, and 556.7 ± 1.0 kJ mol-1 for the heats of formation at 298.15 K of the propargyl radical, c-C3H2, and l-C3H2, respectively. Potential strategies for simplifying the HEAT protocol are also investigated and shown to have negligible impact on accuracy.

Vázquez, Juana; Harding, Michael E.; Gauss, Jürgen; Stanton, John F.

2009-07-01

332

Solar flare distribution relative to the sector boundaries of the interplanetary magnetic field extrapolated to the Sun  

International Nuclear Information System (INIS)

The distributions of approximately 7000 flares of importance >= 1 were plotted relative to the sector-structure boundaries of the interplanetary magnetic field (+-) and (-+) extrapolated to the Sun. The data obtained for the time period July 1955 - December 1961 were used. The distributions obtained were analy ed jointly with the same distributions for 1964-1974. It is shown that stable concentration of the flares is observed only near the boundaries (-+) for both hemispheres of the Sun during the increase of the activity and near the maxima cycles No 19 and 20. There are no difference between ''Hale'' and ''non-Hale'' boundaries for these flares. The decrease of the flares was revealed even near the boundary type (+-). For activity decrease phase, after the Sun's general field polarity inversion the concentration of the flares to the boundaries is absent. The difference between Hale and non-Hale boundaries for flares is revealed only in some increase of the flare concentration near the Hale boundaries. The results obtained are likely to give additional evidence in favour of solar magnetic field and flare activity connection

333

Calibration of {sup 90}Sr+{sup 90}Y chemical applicators using a mini extrapolation chamber as reference system;Calibracao de aplicadores clinicos de {sup 90}Sr+{sup 90}Y utilizando uma mini-camera de extrapolacao como sistema de referencia  

Energy Technology Data Exchange (ETDEWEB)

{sup 90}Sr + {sup 90}Y clinical applicators are beta radiation sources utilized in several radiotherapy Brazilian clinics, although don't be more manufactured. These sources are employed in brachytherapy procedures for the treatment of superficial lesions of skin and eyes. International recommendations and previous works determine that dermatological and ophthalmic applicators shall be calibrated periodically, and one of the methods for their calibration consists of the use of an extrapolation chamber. In this work, a method of calibration of {sup 90}Sr + {sup 90}Y clinical applicators was applied using a mini-extrapolation chamber of plane window, developed at the Calibration Laboratory at IPEN, as a reference system. The results obtained were considered satisfactory, when compared with the results given in the calibration certificates of the sources. (author)

Antonio, Patricia L.; Caldas, Linda V.E. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Oliveira, Mercia L. [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil)

2009-07-01

334

The efficiency variation method for 4??-? coincidence counting by ink-jet printing  

International Nuclear Information System (INIS)

In order to vary the counting efficiencies in the 4??-? coincidence extrapolation technique, a radioactive source was coated directly with varying amounts of an electrical conducting pigment using an ink-jet printer. This method can be used to efficiently prepare the multiple sources needed to generate efficiency extrapolation curves, and was successfully applied to the standardization of a 54Mn source

2007-09-03

335

Implementation of the histogram method for equilibrium statistical models using moments of a distribution  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper shows a simple implementation of the Histogram Method for extrapolations in Monte Carlo simulations, using the moments of the operators that define the energy, instead of their histogram. This implementation is suitable for extrapolation over several operators, a type of calculation that is hindered by computer memory limitations. Examples of this approach are given for the 2-D Ising model.

Perez, Gabriel

2005-01-01

336

Cancer risk estimation from the A-bomb survivors: extrapolation to low doses, use of relative risk models and other uncertainties  

International Nuclear Information System (INIS)

The uncertainties in making generalizations concerning cancer risk estimations (leukemia and other cancers) from forty years of study of A-bomb survivors are discussed, particularly in relation to extrapolation to low doses and prolonged exposures and projections in time and age beyond the current follow-up. (UK)

1989-01-01

337

Hot tensile and creep rupture data extrapolation on 2.25Cr-1Mo steel using the CDM Penny-Kachanov methodology  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Hot tensile and creep data were obtained for 2.25Cr-1Mo steel, ASTM A387 Gr.22CL2, at the temperatures of 500-550-600-650-700 °C. Using the concept of equivalence between hot tensile data and creep data, the results were analyzed according to the methodology based on Kachanov Continuum Damage Mechan [...] ics proposed by Penny, which suggests the possibility of using short time creep data obtained in laboratory for extrapolation to long operating times corresponding to tens of thousands hours. The hot tensile data (converted to creep) define in a better way the region where ?=0 and the creep data define the region where ?=1, according to the methodology. Extrapolation to 10,000 h and 100,000 h is performed and the results compared with results obtained by other extrapolation procedures such as the Larson-Miller and Manson-Haferd methodologies. Extrapolation from ASTM and NIMS Datasheets for 10,000 h and 100,000 h as well as data from other authors on 2.25Cr-1Mo steel are used for assessing the reliability of the results.

Reis Sobrinho, José Francisco dos; Bueno, Levi de Oliveira.

338

A study of the inhibition of iron corrosion in HCl solutions by some amino acids  

International Nuclear Information System (INIS)

The performance of three selected amino acids, namely alanine (Ala), cysteine (Cys) and S-methyl cysteine (S-MCys) as safe corrosion inhibitors for iron in aerated stagnant 1.0 M HCl solutions was evaluated by Tafel polarization and impedance measurements. Results indicate that Ala acts mainly as a cathodic inhibitor, while Cys and S-MCys function as mixed-type inhibitors. Cys, which contains a mercapto group in its molecular structure, was the most effective among the inhibitors tested, while Ala was less effective than S-MCys. The low inhibition efficiency recorded for S-MCys compared with that of Cys was attributed to steric effects caused by the substituent methyl on the mercapto group. Electrochemical frequency modulation (EFM) technique and inductively coupled plasma atomic emission spectrometry (ICP-AES), were also applied to make accurate determination of corrosion rates. Validation of the Tafel extrapolation method for measuring corrosion rates was tested. Rates of corrosion rates (in ?m y-1) obtained from Tafel extrapolation method are in good agreement with those measured using EFM and ICP methods. Some theoretical studies, including molecular dynamics (MD) and density functional theory (DFT), were also employed to establish the correlation between the structure (molecular and electronic) of the three tested inhibitors and the inhibition efficiency. Adsorption via hydrogen bonding was discussed here based on some theoretical studies. Experimental and theoretical results were in good agreement.

2010-05-01

339

A study of the inhibition of iron corrosion in HCl solutions by some amino acids  

Energy Technology Data Exchange (ETDEWEB)

The performance of three selected amino acids, namely alanine (Ala), cysteine (Cys) and S-methyl cysteine (S-MCys) as safe corrosion inhibitors for iron in aerated stagnant 1.0 M HCl solutions was evaluated by Tafel polarization and impedance measurements. Results indicate that Ala acts mainly as a cathodic inhibitor, while Cys and S-MCys function as mixed-type inhibitors. Cys, which contains a mercapto group in its molecular structure, was the most effective among the inhibitors tested, while Ala was less effective than S-MCys. The low inhibition efficiency recorded for S-MCys compared with that of Cys was attributed to steric effects caused by the substituent methyl on the mercapto group. Electrochemical frequency modulation (EFM) technique and inductively coupled plasma atomic emission spectrometry (ICP-AES), were also applied to make accurate determination of corrosion rates. Validation of the Tafel extrapolation method for measuring corrosion rates was tested. Rates of corrosion rates (in {mu}m y{sup -1}) obtained from Tafel extrapolation method are in good agreement with those measured using EFM and ICP methods. Some theoretical studies, including molecular dynamics (MD) and density functional theory (DFT), were also employed to establish the correlation between the structure (molecular and electronic) of the three tested inhibitors and the inhibition efficiency. Adsorption via hydrogen bonding was discussed here based on some theoretical studies. Experimental and theoretical results were in good agreement.

Amin, Mohammed A. [Chemistry Department, Faculty of Science, Ain Shams University, Abbassia, 11566 Cairo (Egypt); Materials and Corrosion Lab (MCL), Chemistry Department, Faculty of Science, Taif University, 888 Hawaiya (Saudi Arabia)], E-mail: maaismail@yahoo.com; Khaled, K.F. [Materials and Corrosion Lab (MCL), Chemistry Department, Faculty of Science, Taif University, 888 Hawaiya (Saudi Arabia); Electrochemistry Research Laboratory, Chemistry Department, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt); Mohsen, Q. [Materials and Corrosion Lab (MCL), Chemistry Department, Faculty of Science, Taif University, 888 Hawaiya (Saudi Arabia); Arida, H.A. [Materials and Corrosion Lab (MCL), Chemistry Department, Faculty of Science, Taif University, 888 Hawaiya (Saudi Arabia); Hot Laboratories Center, Atomic Energy Authority, 13759 Cairo (Egypt)

2010-05-15

340

Extrapolation factors to be used in case of small samples of toxicity data (with a special focus on LD50 values for birds and mammals)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

For the evaluation of the possible environmental hazard/risk for birds and mammals of the use of an agricultural pesticide normally the lowest available LD50 is used. Especially in the case of only one or two LD50s an underestimation of the potential hazard/risk can be a real possibility, because there could be uncertainty that these tested animals represent the most sensitive species. An approach towards extrapolating laboratory toxicity data to acceptable concentrations in...

Luttik R; Aldenberg T

2007-01-01

 
 
 
 
341

Measuring limiting low values of PO3 in the liquid: if the extrapolation number of survival curve of mammal cells is decreasing in case of irradiation in anoxia  

International Nuclear Information System (INIS)

The removal of dissolved gas in the vacuum in combination with the chemical oxygen absorption with sodium hydrosulfate (Na2-S2O4) and/or its radiation absorption permits to remove all traces of hydrogen from cells, if they are cultivated on glass cups. In the case of X-ray irradiation of these cells, the extrapolation number does not depend on whether irradiation is carried out under aerobic or anaerobic conditions, with oxygen effect value being 3.0

1974-09-21

342

Nonlinear Force-Free Field Extrapolation of a Coronal Magnetic Flux Rope Supporting a Large-Scale Filament from Photospheric Vector Magnetogram  

CERN Document Server

Solar filament are commonly thought to be supported in magnetic dips, in particular, of magnetic flux ropes (FRs). In this Letter, from the observed photospheric vector magnetogram, we implement a nonlinear force-free field (NLFFF) extrapolation of a coronal magnetic FR that supports a large-scale intermediate filament between an active region and a weak polarity region. This result is the first in that current NLFFF extrapolations with presence of FRs are limited to relatively small-scale filaments that are close to sunspots and along main polarity inversion line (PIL) with strong transverse field and magnetic shear, and the existence of a FR is usually predictable. In contrast, the present filament lies along the weak-field region (photospheric field strength $\\lesssim 100$ G), where the PIL is very fragmented due to small parasitic polarities on both side of the PIL and the transverse field has a low value of signal-to-noise ratio. Thus it represents a far more difficult challenge to extrapolate a large-sc...

Jiang, Chaowei; Feng, Xueshang; Hu, Qiang

2014-01-01

343

Extrapolating surface structures to depth in transpressional systems: the role of rheology and convergence angle deduced from analogue experiments  

Science.gov (United States)

The internal structure of major strike-slip faults is still poorly understood, particularly how the deep structure could be inferred from its surface expression (Molnar and Dayem, 2011 and references therein). Previous analogue experiments suggest that the convergence angle is the most influential factor (Leever et al., 2011). Further analogue modeling may allow a better understanding how to extrapolate surface structures to the subsurface geometry of strike-slip faults. Various scenarios of analogue experiments were designed to represent strike-slip faults in nature from different geological settings. As such key parameters, which are investigated in this study include: (a) the angle of convergence, (b) the thickness of brittle layer, (c) the influence of a rheological weak layer within the crust, and (d) influence of a thick and rheologically weak layer at the base of the crust. The latter aimed to simulate the effect of a hot metamorphic core complex or an alignment of uprising plutons bordered by a transtensional/transpressional strike-slip fault. The experiments are aimed to explain first order structures along major transcurrent strike-slip faults such as the Altyn, Kunlun, San Andrea and Greendale (Darfield earthquake 2010) faults. The preliminary results show that convergence angle significantly influences the overall geometry of the transpressive system with greater convergence angles resulting in wider fault zones and higher elevation. Different positions, densities and viscosities of weak rheological layers have not only different surface expressions but also affect the fault geometry in the subsurface. For instance, rheological weak material in the bottom layer results in stretching when experiment reaches a certain displacement and a buildup of a less segmented, wide positive flower structure. At the surface, a wide fault valley in the middle of the fault zone is the reflection of stretching along the velocity discontinuity at depth. In models with a thin and rheologically weaker layer in the middle of the brittle layer, deformation is distributed over more faults and the geometry of the fault zone below and above the weak zone shows significant differences, suggesting that the correlation of structures across a weak layer has to be supported by geophysical data, which help constraining the geometry of the deep part. This latter experiment has significantly similar phenomena in reality, such as few pressure ridges along Altyn fault. The experimental results underline the need to understand the role of the convergence angle and the influence of rheology on fault evolution, in order to connect between surface deformation and subsurface geometry. References Leever, K. A., Gabrielsen, R. H., Sokoutis, D., Willingshofer, E., 2011. The effect of convergence angle on the kinematic evolution of strain partitioning in transpressional brittle wedges: Insight from analog modeling and high-resolution digital image analysis. Tectonics, 30(2), TC2013. Molnar, P., Dayem, K.E., 2010. Major intracontinental strike-slip faults and contrasts in lithospheric strength. Geosphere, 6, 444-467.

Hsieh, Shang Yu; Neubauer, Franz; Cloetingh, Sierd; Willingshofer, Ernst; Sokoutis, Dimitrios

2014-05-01

344

Application of ecological models to ecological risk assessment. Extrapolation and the life history sensitivity analysis; Seitaigaku model no seitai risk bunseki eno tekiyo. Gaisoho to seikatsushi kando kaiseki no koyo  

Energy Technology Data Exchange (ETDEWEB)

This paper describes ecological risk analysis. Assessing ecological toxicity of chemical substances as a decrease in intrinsic rate of natural increase of groups of living organisms is important for the ecological risk assessment using extinction probability of the groups of living organisms. However, only few chemical substances and organism species have been identified of their detailed ecotoxicological data. It may be difficult to prepare a life table over an entire life history for many of the living organism species. Therefore, an extrapolation method is used, in which regression formulas are derived for acute toxicity (LC50, for example) and chronic toxicity (EC20, for example), and between chronic toxicity values for different living organism species. This is a method to infer unknown chronic toxicity from acute toxicity values or chronic toxicity values of relative species. The life history sensitivity analysis can quantify the effect (sensitivity) of changes in the life history components such as number of oviposition by age and survival ratio by age constituting the life table on change in the intrinsic rate of natural increase. Because the life history sensitivity analysis can specify which life history components are important for proliferation of groups of individuals, it can simplify the life table assessment method. 17 refs., 1 fig., 5 tabs.

Tanaka, Y. [Yokohama National University, Yokohama (Japan). Institute of Environmental Science and Technology; Nakanishi, J. [Japan Science and Technology Corp., Tokyo (Japan)

1998-09-10

345

Min-max Extrapolation Scheme for Fast Estimation of 3D Potts Field Partition Functions. Application to the Joint Detection-Estimation of Brain Activity in fMRI  

International Nuclear Information System (INIS)

In this paper, we propose a fast numerical scheme to estimate Partition Functions (PF) of symmetric Potts fields. Our strategy is first validated on 2D two-color Potts fields and then on 3D two- and three-color Potts fields. It is then applied to the joint detection-estimation of brain activity from functional Magnetic Resonance Imaging (fMRI) data, where the goal is to automatically recover activated, deactivated and inactivated brain regions and to estimate region dependent hemodynamic filters. For any brain region, a specific 3D Potts field indeed embodies the spatial correlation over the hidden states of the voxels by modeling whether they are activated, deactivated or inactive. To make spatial regularization adaptive, the PFs of the Potts fields over all brain regions are computed prior to the brain activity estimation. Our approach is first based upon a classical path-sampling method to approximate a small subset of reference PFs corresponding to pre-specified regions. Then, we propose an extrapolation method that allows us to approximate the PFs associated to the Potts fields defined over the remaining brain regions. In comparison with preexisting methods either based on a path sampling strategy or mean-field approximations, our contribution strongly alleviates the computational cost and makes spatially adaptive regularization of whole brain fMRI datasets feasible. It is also robust against grid inhomogeneities and efficient irrespective of the topological configurations of the brain regions. (authors)

2011-01-01

346

The concept of gene transfer-misrepair mechanism of radiation carcinogenesis may challenge the linear extrapolation model of risk estimation for low radiation doses  

International Nuclear Information System (INIS)

The recent demonstration that transformation of cultured cells can be induced by exposure to DNA fragments prepared from normal mouse tissues provides experimental support to the gene transfer-misrepair hypothesis of radiation carcinogenesis. It is predicted that the proposed mechanism implies a non-linear extrapolation model for the calculation of cancer risks caused by very low doses of ionizing radiation of low LET. It also follows from this hypothesis that X- and ?-radiation delivered at an extremely low dose rate will be less carcinogenic than at high dose rate, in particular where low total doses are concerned. (author)

1982-01-01

347

Concept of gene transfer-misrepair mechanism of radiation carcinogenesis may challenge the linear extrapolation model of risk estimation for low radiation doses  

Energy Technology Data Exchange (ETDEWEB)

The recent demonstration that transformation of cultured cells can be induced by exposure to DNA fragments prepared from normal mouse tissues provides experimental support to the gene transfer-misrepair hypothesis of radiation carcinogenesis. It is predicted that the proposed mechanism implies a non-linear extrapolation model for the calculation of cancer risks caused by very low doses of ionizing radiation of low LET. It also follows from this hypothesis that X- and ..gamma..-radiation delivered at an extremely low dose rate will be less carcinogenic than at high dose rate, in particular where low total doses are concerned.

van Bekkum, D.W.; Bentvelzen, P. (Gezondheidsorganisatie TNO, Rijswijk (Netherlands). Radiobiologisch Inst. TNO)

1982-08-01

348

New Synthesized Guanidine Derivative as a Green Corrosion Inhibitor for Mild Steel in Acidic Solutions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A new safe corrosion inhibitor namely N-(5,6-diphenyl-4,5-dihydro-[1,2,4]triazin- 3-yl)-guanidine (NTG) has been synthesized and its inhibitive performance towards the corrosion of mild steel in 1 M hydrochloric acid and 0.5 M sulphuric acid has been investigated. Corrosion inhibition was studied by chemical method (weight loss) and electrochemical techniques include Tafel extrapolation method and electrochemical impedance spectroscopy (EIS). These studies have shown that NTG was a very good ...

2008-01-01

349

Creep-rupture-test on the stainless steel X6crni1811 (Din 1.494.8) in the frame of the Extrapolation-Program. (Part III)  

International Nuclear Information System (INIS)

The austenitic stainless steel X6crni1811 (Din 1.4948) used as a structure material for the German Fast Breeder Reactor SNR 300 was creep tested in a temperature range of 550-650 degree centigree material condition as well as welded material condition. The main point of this program (Extrapolation-Program) lies in the knowledge of the creep-rupture-strength and creep-behaviour up to 3 x 104 hours higher temperatures in order to extrapolated up to ?105 hours for operating temperatures. In order to study the stress dependency of the minimum creep rate additional tests were carried out of 550 degree centigree - 750 degree centigree. The present report describes the state in the running program with test-times of 23.000 hours and results from tests up to 55.000 hours belonging to other parallel programs are taken into account. Besides the creep-rupture behaviour it is also made a study of ductility between 550 and 750 degree centigree. Extensive metallographic examinations have been made to study the fracture behaviour and changes in structure. (Author)

1982-01-01

350

Creep-rupture-tests on thestainless steel X6 CrNi1811 (DIN 1.4948) in the frame of the ''Extrapolation-Program'' Pt. 2  

International Nuclear Information System (INIS)

The austenitic stainless steel X6 CrNi 1811 (DIN 1.4948) that is used as a structure material for the German Fast Breeder Reactor SNR 300 was creep tested in a temperature range of 550-650 deg under base material condition as well as welded material condition. The main point of this program (''Extrapolation-Program'') lies in the knowledge of the cree-rupture-strength and creep-behaviour up to 3X10"-4 hours at higher temperatures in order to extrapolate up to (>=)10"5 hours for operating temperatures. In order to study the stress dependency of the minimum creep rate additional tests were carried out over temperature range 550 deg - 750 deg C. The present report describes the state in the running program with test-time up to 35.000 hours. Besides the cree-rupture behaviour it is possible to make a distinct quantitative statement for the creep-behaviour and ductility. Extensive metallographic examinations show the fracture behaviour and changes in structure. (author)

1979-01-01

351

Copper complex N(4)-ortho-toluyl-2-acetylpyridine thiosemicarbazone - (64Cu)(H2Ac4oT)Cl - internal dosimetry: animal model and human extrapolation  

International Nuclear Information System (INIS)

Thiosemicarbazones have attracted great pharmacological interest because of their biological properties, such as cytotoxic activity against multiple strains of human tumors. Due to the excellent properties of 64Cu, the copper complex N(4)-ortho-toluyl-2-acetylpyridine thiosemicarbazone ( (64Cu)(H2Ac4oT)Cl) was developed for tumor detection by positron emission tomography. The radiopharmaceuticals were produced in the nuclear reactor TRIGA-IPR-R1 from CDTN. At the present work, (64Cu)(H2Ac4oT)Cl biokinetic data (evaluated in mice bearing Ehrlich tumor) were treated by MIRD formalism to perform Internal Dosimetry studies. Doses in several organs of mice were determinate, as well as in implanted tumor, for (64Cu)(H2Ac4oT)Cl. Doses results obtained for animal model were extrapolated to humans assuming a similar concentration ratio among various tissues between mouse and human. In the extrapolation, it was used human organ masses from Cristy/Eckerman phantom. Both penetrating and non-penetrating radiation from 64Cu in the tissue were considered in dose calculations. (author)

2011-10-24

352

Creep-rupture-tests on the stainless steel X6CrNi1811 (DIN 1.4948) in the frame of the 'Extrapolation-Program'. Pt. 2  

International Nuclear Information System (INIS)

The austenitic stainless steel X6CrNi1811 (DIN 1.4948) that is used as a structure material for the German Fast Breeder Reactor SNR 300 was creep tested in a temperature range of 550-6500C under base material condition as well as welded material condition. The main point of this program ('Extrapolation-Program') lies in the knowledge of the creep-rupture-strength and creep-behaviour up to 3 x 104 hours at higher temperatures in order to extrapolate up to >= 105 hours for operating temperatures. In order to study the stress dependency of the minimum creep rate additional tests were carried out over temperature range of 5500C - 7500C. The present report describes the state in the running program with test-times up to 35.000 hours. Besides the creep-rupture behaviour it is possible to make a distinct quantitativ statement for the creep-behaviour and ductility. Extensive metallographic examinations show the fracture behaviour and changes in structure. (orig.)

1978-01-01

353

Irradiation dose assessment in persons exposed to ionizing radiation through extrapolation of data from clinic-chemical changes in irradiated laboratory animals  

International Nuclear Information System (INIS)

An attempt is made to determine the dose within 24,48 and 72 hours of eventual exposure of healthy individuals to ionizing radiation through extrapolation of data retrieved from rats exposed to irradiation with 1, 3, 6 and 9 Gy X-rays. Seven clinic-chemical parameters are used: urea in the urine, taurine in the urine, urea in the serum, serum alkaline phosphatase, total serum lipids, sialic acid and thromboxane in the serum. A special formula is worked out and used for extrapolation of the experimental data, retrieved from irradiated rats, with due consideration to differences in the intensity of metabolic processes and species' radiosensitivity of rats and humans. The values of the aforementioned parameters that could be obtained upon eventual exposure of persons to ionizing irradiation are determined through computerization of the experimental data. It is believed that an accessible model for radiation dose assessment in the first three days after accidental exposure of human beings to ionizing irradiation is created. 5 refs., 4 figs. (author)

1995-01-01

354

Methods for the assessment of the toxicity of environmental chemicals to earthworms  

Energy Technology Data Exchange (ETDEWEB)

In view of the impending publication of standards for earthworm toxicity testing by the Commission of the European Communities, a review has been made of the recent literature on earthworm toxicology. Relevant studies are reviewed from the standpoints of methods used, reproducibility of results, and ability to extrapolate laboratory results to field situations. Eisenia foetida, a commonly used test species, is much less sensitive to agricultural chemicals than other, native earthworms and is of doubtful utility for extrapolating laboratory data to field conditions, but when native soil organisms are used, such extrapolations show good general agreement. Standardization of test conditions and broadening of the data base are encouraged.

Dean-Ross, D.

1983-03-01

355

Mathematical methods for physical and analytical chemistry  

CERN Multimedia

Mathematical Methods for Physical and Analytical Chemistry presents mathematical and statistical methods to students of chemistry at the intermediate, post-calculus level. The content includes a review of general calculus; a review of numerical techniques often omitted from calculus courses, such as cubic splines and Newton's method; a detailed treatment of statistical methods for experimental data analysis; complex numbers; extrapolation; linear algebra; and differential equations. With numerous example problems and helpful anecdotes, this text gives chemistry students the mathematical

Goodson, David Z

2011-01-01

356

Lits fluidisés pour l'industrie chimique. Extrapolation et amélioration des catalyseurs. Première partie : Etudes et modèles. Enseignements issus des pilotes Fluidized Beds in Chemical Industry. Scale Up and Catalysts Improvement. First Part: Studies, Models, Learning from Pilot Plants  

Directory of Open Access Journals (Sweden)

Full Text Available Les unités de production en lits fluidisés catalytiques sont apparues vers 1942 dans l'industrie pétrolière et vers 1960 dans l'industrie chimique. On se limitera ici au problème de l'extrapolation des lits fluidisés catalytiques pour l'industrie chimique, qui exigent de très hautes performances (> 99 % de conversion. Leur mise au point a, dans le passé, nécessité l'exploitation sur des sites industriels de coûteux pilotes de 0,5 m de diamètre et de plus de 10 m de hauteur. Nous montrerons que ces pilotes peuvent être évités et que le passage direct du laboratoire à l'échelle industrielle est réalisable. Cette possibilité offre en plus une méthode simple pour améliorer les catalyseurs des unités industrielles. Elle ouvre aussi cette technique, très appr?ciée en production, aux produits de petits tonnages. La présentation de cet article sera faite en trois parties : - La première, présentée ci-après, expose les problèmes majeurs posés par l'extrapolation, puis résume les études effectuées. Les travaux d'extrapolation relatifs à deux procédés effectués avec des pilotes sont ensuite présentés, ? titre d'exemples. De ces travaux sont déduites les performances que l'on peut espérer obtenir avec un réacteur catalytique à lit fluidisé, ainsi que les règles de tendances à suivre pour y parvenir. - La deuxième partie, intitulée Stratégie n'utilisant que des expériences de laboratoire , propose une stratégie expérimentale permettant d'obtenir en laboratoire les informations nécessaires pour passer directement à l'échelle industrielle avec des exp?riences suggérées en partie par les résultats exposés dans le premier article. Les relations expérimentales établies lors de ces études montrent que les propriétés d'un lit fluidisé ne dépendent (mis à part quelquefois le diam?tre du réacteur que d'un paramètre appel? vitesse minimum de fluidisation de comportement . - La troisième partie est intitulée Études théoriques, réalités expérimentales, suggestions . Les bulles des lits fluidisés ont fait l'objet de très nombreux travaux, dont les résultats sont très souvent explicités sous la forme de modèles mécanistiques à un paramètre qui est le diamètre des bulles. Pour confronter ces modèles à l'exp?rience, une relation est établie entre le diamètre des bulles et la vitesse minimum de fluidisation de comportement. Des suggestions sont alors faites pour améliorer les modèles, et l'on propose des conclusions générales sur les lits fluidisés. The firsts catalytic fluidized beds appear near 1942 in petroleum industry and near 1960 in chemical industry. We only consider very high performances chemical fluidized bed reactors (> 99%. In the past, they were developed through the use of very expensive pilot plants of about 0. 5 m diameter and 10 in high. We will demonstrate that direct scale up from laboratory data is possible. This possibility gives also a simple method to improve catalysts used into operating units and opens fluidized bed technique to products that need only low production. Presentation is made with three articles:- In the first, Studies, Models, Learning from Pilot Plants : after a description of the major scale-up problems, studies to solve then are summarized. Then scale-up works of two processes with the use of about 0. 5 m diameter pilot plant are given. From the results it is deduced the possible performances of a catalytic fluidized bed and how to operate to obtain then. - In the second*, Scale up with Only Laboratory Data , it is experimentally demonstrated that the information's scale-up can be obtained in a laboratory. A strategy to obtain them is suggested. An another result of theses experimental studies is that all physical properties of catalytic fluidized bed depends of only one parameter. It is called comportment incipient fluidization velocity . - In the third*, Theoretical Studies, Experimental Reality, Suggestionsresults of theoretical studies about bubbles of the fluidized beds are summarize

Botton R.

2006-12-01

357

‘Als de tafel danst, dan wankelt de wetenschap’. De relatie tussen spiritisme en wetenschap rond 1900  

Directory of Open Access Journals (Sweden)

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'If the table turns, science will stagger'. The relationship between spiritualism and science in the Netherlands around 1900


Spiritualism is the belief that living men can keep contact, usually through an intermediary called a 'medium', with spirits of the dead. The history of modern spiritualism started in 1848 in America and in the decades that followed it spread all over the world. Especially as a result of British influences modern Anglo-Saxon spiritualism is characterized by a search for scientific proof of the so-called spiritualist phenomena. In the 1920s the Netherlands were late in comparison with neighbouring countries to institutionalize the scientific study of these phenomena. But this does not imply that there was no earlier discussion about it. Indeed, around 1900 there were attempts for a debate about the scientific underpinning of spiritualism and the main stage for it was the journal Het toekomstig leven [The future life]. In the historical conceptualization of this debate it has long been common to see the spiritualists as an anti-modern counterculture and the scientists as the representatives of modernity. Recently this dichotomic order has been replaced for a nuanced view that does more justice to the historical reality. Although Het toekomstig leven often used rhetoric strategies that emphasized the confrontation with science, the journal also lavishly incorporated scientific elements and made inexhaustible attempts for a scientific debate and study of the paranormal phenomena. Unlike in neighbouring countries there were hardly any natural scientists who responded, but there were some physicians as well as pioneers of the new field of parapsychology who pleaded for scientific research of spiritualism. This research eventually became reality in 1920 under the direction of some heavyweight scientists, but just as Het toekomstig leven the Dutch Society for Psychical Research was also marked by the difference between the critical-scientific approach and the not so critical approach of the believers. In my contribution I have showed that this demarcation was however not the same as the one between science and spiritualism, because these boundaries were considerably permeable.

Leonieke Vermeer

2007-01-01

358

Corrosion Behaviour of 18%Ni M250 Grade Maraging Steel under Welded Condition in Hydrochloric Acid Medium  

Scientific Electronic Library Online (English)

Full Text Available SciELO Portugal | Language: English Abstract in english The corrosion behaviour of welded maraging steel in hydrochloric acid solutions was studied over a range of acid concentration and solution temperature by electrochemical techniques like Tafel extrapolation method and electrochemical impedance spectroscopy. The corrosion rate of welded maraging stee [...] l increases with the increase in temperature and concentration of hydrochloric acid in the medium. The energies of activation, enthalpy of activation and entropy of activation for the corrosion process were calculated. The surface morphology of the corroded sample was evaluated by surface examination using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS).

Pradeep, Kumar; A. Nityananda, Shetty.

359

Corrosion inhibition of brass by aliphatic amines  

International Nuclear Information System (INIS)

Aliphatic amines hexylamine (HCA), octylamine (OCA) and decylamine (DCA) have been used as corrosion inhibitors for (70/30) brass in 0.I M HCIO4. The inhibitor efficiency (%P) calculated using weight loss, Tafel extrapolation, linear polarization and impedance methods was found to be in the order DCA> OCA> HCA. These adsorb on brass surface following bockris-swinkels' isotherm. DCA, OCA and HCA displaced 4, 3 and 2 molecules of water from interface respectively. Displacement of water molecules brought a great reorganization of double layer at the interface. These amines during corrosion form complexes with dissolved zinc and copper ions.(Author)

2005-03-01

360

A study of iteration method for 2-dimensional 2-group diffusion problems  

International Nuclear Information System (INIS)

It is shown that the Shanks sequence Esub(k)-transformation and the conventional extrapolation method are theoretically related. The Esub(1)sup(2)-transformation method is then applied for the multigroup diffusion probems. The diffusion code, CITATION, is modified for this study and the computing time is compared for each iteration tactics. The Equipose method, in which only single inner iteration for each energy group is carried for an outer iteration, has been known as the fastest iteration method. However, in the case of 2-group problems, the proposed method, in which the number of inner iteration for the fast and thermal group is 2 and 1 respectively, gives better convergency than the Equipose method by about 12 %. The double extrapolation method results in faster computing time than the single extrapolation method without computing storage problem. It is, however, to note that this method is verfied only for a two-group treatment. (Author)

1983-01-01

 
 
 
 
361

Extrapolating Zernike Moments to Predict Future Optical Wave-fronts in Adaptive Optics Using Real Time Data Mining  

CERN Document Server

We present the details of predicting atmospheric turbulence by mining Zernike moment data obtained from simulations as well as experiments. Temporally correlated optical wave-fronts were simulated such that they followed Kolmogorov phase statistics. The wave-fronts reconstructed either by modal or zonal methods can be represented in terms of Zernike moments. The servo lag error in adaptive optics is minimized by predicting Zernike moments in the near future by using the data from the immediate past. It is shown statistically that the prediction accuracy depends on the number of past phase screens used for prediction and servo lag time scales. The algorithm is optimized in terms of these parameters for real time and efficient operation of the adaptive optics system. On an average, we report more than 3% improvement in the wave-front compensation after prediction. This analysis helps in optimizing the design parameters for sensing and correction in closed loop adaptive optics systems.

Vyas, Akondi; Prasad, B Raghavendra

2010-01-01

362

Precision ground state mass of 12Be and an isobaric multiplet mass equation (IMME) extrapolation for 2+ and 02+ states in the T=2, A=12 multiplet  

International Nuclear Information System (INIS)

We report the mass measurement of the short-lived 12Be nuclide (T1/2=21.5 ms) performed using the Penning trap mass spectrometer TITAN at TRIUMF. Our mass excess value of 25 078.0(2.1) keV is in agreement with previous measurements, but is a factor of 7 more precise than the Atomic Mass Evaluation of 2003. To address an unresolved discussion on the spin assignment of isospin T=2 states in 12C and 12O, we reevaluate the isobaric mass multiplet equation for the lowest lying T=2 multiplet in the A=12 system and use the extracted parameters to extrapolate from the known excited 2+ and 0+ states in 12Be. Though this analysis favors the second known T=2 state in 12C to be 2+, 0+ cannot be excluded.

2010-02-01

363

The concept of gene transfer-misrepair mechanism of radiation carcinogenesis may challenge the linear extrapolation model of risk estimation for low radiation doses  

Energy Technology Data Exchange (ETDEWEB)

The recent demonstration that transformation of cultured cells can be induced by exposure to DNA fragments prepared from normal mouse tissues provides experimental support to the gene transfer-misrepair hypothesis of radiation carcinogenesis. Employing various assumptions with regard to the generation of oncogenic DNA fragments and of cells which are susceptible to incorporate these fragments into their genome, it is predicted that the proposed mechanism implies a non-linear extrapolation model for the calculation of cancer risks caused by very low doses of ionizing radiation of low LET. It also follows from this hypothesis that X- and gamma-radiation delivered at an extremely low dose rate will be less carcinogenic than at high dose rate, in particular where low total doses are concerned. Several aspects of the hypothesis can be verified experimentally by the use of in vitro cultured cell systems.

van Bekkum, D.W.; Bentvelzen, P.

1982-08-01

364

Dispersion relation approach to the extrapolation towards negative energy of the optical potential in "4"0Ca and "2"0"8Pb  

International Nuclear Information System (INIS)

Accurate empirical information on the nuclear mean field V(r; E) is available at positive energy but is lacking at negative energy. A dispersion relation approach is used to extrapolate the radial moments [r"q]_V(E)=(4?/A)?V(r; E)r"q dr(q=0.8, 2, 4) of V(r; E) from positive to negative energies. The quantity V(r; E) is the sum of a Hartree-Fock type contribution V_H_F(r; E) and of a dispersive contribution ?V(r; E) which arises from the coupling between the elastic and nonelastic channels. A dispersion relation is used to evaluate [r"q]_?_V(E) from the radial moments [r"q]_W(E) of the imaginary part of empirical optical-model potentials, in the case of protons and neutrons on "2"0"8Pb and of protons on "4"0Ca. It is assumed that the radial moments of V_H_F are either linear or quadratic functions of energy, whose parameters are determined by fitting the empirical values of [r"q]_V(E) associated with optical-model potentials which yield very good fits to the experimental cross sections; close agreement is found between the calculated and empirical values of [r"q]_V(E) for E>0. The dispersive corrections give rise to a characteristic energy dependence of the ratios [r"q]_V(E)/[r"q]_V(E) at low energy in particular of the mean square radius. The reliability of the extrapolation of the calculated [r"q]_V(E) towards negative energy is discussed by studying its sensitivity to the inputs of the model. This sensitivity can be reduced when one introduces a constraint at the Fermi energy E_F. The meaningfulness of this type of constraint is discussed. (orig.)

1986-01-01

365

Vasectomy as a proxy: extrapolating health system lessons to male circumcision as an HIV prevention strategy in Papua New Guinea  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Male circumcision (MC has been shown to reduce the risk of HIV acquisition among heterosexual men, with WHO recommending MC as an essential component of comprehensive HIV prevention programs in high prevalence settings since 2007. While Papua New Guinea (PNG has a current prevalence of only 1%, the high rates of sexually transmissible diseases and the extensive, but unregulated, practice of penile cutting in PNG have led the National Department of Health (NDoH to consider introducing a MC program. Given public interest in circumcision even without active promotion by the NDoH, examining the potential health systems implications for MC without raising unrealistic expectations presents a number of methodological issues. In this study we examined health systems lessons learned from a national no-scalpel vasectomy (NSV program, and their implications for a future MC program in PNG. Methods Fourteen in-depth interviews were conducted with frontline health workers and key government officials involved in NSV programs in PNG over a 3-week period in February and March 2011. Documentary, organizational and policy analysis of HIV and vasectomy services was conducted and triangulated with the interviews. All interviews were digitally recorded and later transcribed. Application of the WHO six building blocks of a health system was applied and further thematic analysis was conducted on the data with assistance from the analysis software MAXQDA. Results Obstacles in funding pathways, inconsistent support by government departments, difficulties with staff retention and erratic delivery of training programs have resulted in mixed success of the national NSV program. Conclusions In an already vulnerable health system significant investment in training, resources and negotiation of clinical space will be required for an effective MC program. Focused leadership and open communication between provincial and national government, NGOs and community is necessary to assist in service sustainability. Ensuring clear policy and guidance across the entire sexual and reproductive health sector will provide opportunities to strengthen key areas of the health system.

Tynan Anna

2012-09-01

366

Extrapolating Ground-Based Aircraft Engine Exhaust Emissions to Cruise Conditions: Lessons From the 2013 ACCESS Chase Plane Experiment  

Science.gov (United States)

Aircraft engine emissions constitute a tiny fraction of the global black carbon mass, but can have a disproportionate climatic impact because they are emitted high in the troposphere and in remote regions with otherwise low aerosol concentrations. Consequently, these particles are likely to strongly influence cirrus and contrail formation by acting as ice nuclei (IN). However, the ice nucleating properties of aircraft exhaust at relevant atmospheric conditions are not well known, and thus, the overall impact of aviation on cloud formation remains very uncertain. While a number of aircraft engine emissions studies have previously been conducted at sea level temperature and pressure (e.g., APEX, AAFEX-1 and 2), it unclear the extent to which exhaust emissions on the ground translate to emissions at cruise conditions with much lower inlet gas temperatures and pressures. To address this need, the NASA Alternative Fuel Effects on Contrails and Cruise Emissions (ACCESS) was conducted in February-April, 2013 to examine the aerosol and gas emissions from the NASA DC-8 under a variety of different fuel types, engine power, and altitude/meteorological conditions. Two different fuel types were studied: a traditional JP-8 fuel and a 50:50 blend of JP-8 and a camelina-based hydro-treated renewable jet (HRJ) fuel. Emissions were sampled using a comprehensive suite of gas- and aerosol-phase instrumentation integrated on an HU-25 Falcon jet that was positioned in the DC-8 exhaust plume at approximately 100-500m distance behind the engines. In addition, a four-hour ground test was carried out with sample probes positioned at 30 m behind each of the inboard engines. Measurements of aerosol concentration, size distribution, soot mass, and hygroscopicity were carried out along with trace gas measurements of CO2, NO, NO2, O3, and water vapor. NOx emissions were reconciled by employing the well-established Boeing method for normalizing engine fuel flow rates to STP; however, comparison of aerosol emissions between ground and altitude is less straight forward. The implications of these factors for developing new aviation emissions factors / inventories related to aerosol species will be discussed.

Moore, R.; Shook, M.; Thornhill, K. L.; Winstead, E.; Anderson, B. E.

2013-12-01

367

The Trojan horse method in nuclear astrophysics  

International Nuclear Information System (INIS)

Because of the Coulomb barrier, reaction cross sections in astrophysics cannot be accessed directly at the relevant Gamow energies, unless very favourable conditions are met (e.g. LUNA--underground experiments). Theoretical extrapolations of available data are then needed to derive the astrophysical S(0)-factor. Various indirect processes have been used in order to obtain additional information on the parameters entering these extrapolations. The Trojan Horse Method is an indirect method which might help to bypass some of the problems typically encountered in direct measurements, namely the presence of the Coulomb barrier and the effect of the electron screening. However, a comparison with direct data in an appropriate energy region (e.g. around the Coulomb barrier) is crucial before extending the method to the relevant Gamow energy. Additionally, experimental and theoretical tests are needed to validate the assumptions underlying the method. The application of the Trojan Horse Method to some cases of interest is discussed

2001-04-19

368

HIV infection in older adults in sub-Saharan Africa: extrapolating prevalence from existing data / Infection à VIH chez les adultes âgés en Afrique subsaharienne: extrapolation de la prévalence à partir de données existantes / Infección por el VIH entre los adultos de mayor edad en el África subsahariana: extrapolación de la prevalencia a partir de los datos existentes  

Scientific Electronic Library Online (English)

Full Text Available SciELO Public Health | Language: English Abstract in spanish OBJETIVO: Cuantificar el número de casos y la prevalencia de la infección por el virus de la inmunodeficiencia humana (VIH) entre los adultos de mayor edad en el África subsahariana. MÉTODOS: Se han analizado los datos procedentes de las Encuestas demográficas y de salud (EDS). Aunque en estos estud [...] ios todas las mujeres entrevistadas son menores de 50 años, 18 de estas encuestas contenían datos sobre la infección por VIH en hombres con una edad igual o superior a los 50 años. Para calcular el porcentaje de adultos de mayor edad (es decir, personas de 50 o más años de edad) con positividad al VIH (VIH+), se extrapolaron los datos procedentes del Programa Conjunto de las Naciones Unidas sobre el VIH/SIDA sobre la cantidad estimada de personas con el VIH y sobre la prevalencia de la infección por este virus entre los adultos con edades comprendidas entre 15 y 49 años. RESULTADOS: En 2007, en el África subsahariana había unos 3 millones de personas de 50 años o mayores con el VIH. La prevalencia de la infección por el VIH en este grupo fue del 4,0%, en comparación con el 5,0% correspondiente al grupo con edades comprendidas entre 15 y 49 años. De la cantidad aproximada de 21 millones de personas > 15 años con VIH en el África subsahariana, el 14,3% tenía 50 años de edad o más. CONCLUSIÓN: Para poder reflejar mejor la mayor supervivencia de las personas con VIH y el envejecimiento de la población VIH+, se deben ampliar los indicadores de la prevalencia de la infección por el VIH, de manera que incluyan a las personas mayores de 49 años. Se sabe poco sobre la morbilidad asociada y el comportamiento sexual de los adultos VIH+ de mayor edad o acerca de los factores biológicos y culturales que aumentan el riesgo de transmisión. Los servicios relacionados con el VIH deben orientarse mejor para responder a las necesidades crecientes de los adultos de edad más avanzada que se ven afectados por esta enfermedad. Abstract in english OBJECTIVE: To quantify the number of cases and prevalence of human immunodeficiency virus (HIV) infection among older adults in sub-Saharan Africa. METHODS: We reviewed data from Demographic and Health Surveys (DHS). Although in these surveys all female respondents are [...] urveys contained data on HIV infection among men aged > 50 years. To estimate the percentage of older adults (i.e. people > 50 years of age) who were positive for HIV (HIV+), we extrapolated from data from the Joint United Nations Programme on HIV/AIDS on the estimated number of people living with HIV and on HIV infection prevalence among adults aged 15-49 years. FINDINGS: In 2007, approximately 3 million people aged > 50 years were living with HIV in sub-Saharan Africa. The prevalence of HIV infection in this group was 4.0%, compared with 5.0% among those aged 15-49 years. Of the approximately 21 million people in sub-Saharan Africa aged > 15 years that were HIV+, 14.3% were > 50 years old. CONCLUSION: To better reflect the longer survival of people living with HIV and the ageing of the HIV+ population, indicators of the prevalence of HIV infection should be expanded to include people > 49 years of age. Little is known about comorbidity and sexual behaviour among HIV+ older adults or about the biological and cultural factors that increase the risk of transmission. HIV services need to be better targeted to respond to the growing needs of older adults living with HIV.

Joel, Negin; Robert G, Cumming.

369

Analytical method for determining the internal resistance and electrocatalyst utilization of fuel cells  

Energy Technology Data Exchange (ETDEWEB)

Two analytical methods are developed that each allows one to determine: (i) the internal resistance of fuel cell electrodes, and (ii) the fraction of the electrocatalyst that is effectively used. To apply either method requires knowledge of the Tafel parameters for the electrocatalyst-electrolyte combination. In addition, one method - the maximum power method - requires that the potential and current of a fuel cell be measured when the cell is operating under steady-state conditions and at maximum power. Thus, its application is limited to fuel cells that are not damaged by operating at these conditions. The second method is approximate, but it does not require that the voltage and current be measured at the maximum power condition. To apply the second method - approximate maximum power method - requires the mesurement of the fuel cell potential and slope of the potential-current relation of the fuel cell at a current that is less than the current corresponding to the maximum power condition. Using data available from the literature, the two techniques are used to evaluate these characteristics for a KOH fuel cell. They are also used to predict the voltage-current relation for the fuel cell. The results are found to be in close agreement with the reported measurements over a range of currents. The range is larger for the `maximum power method` than for the `approximate maximum power method`. (orig.)

Ward, C.A. [Thermodynamics and Kinetics Lab., Dept. of Mechanical Engineering, Toronto Univ., ON (Canada); Garcia, J.A. [Thermodynamics and Kinetics Lab., Dept. of Mechanical Engineering, Toronto Univ., ON (Canada)

1997-05-01

370

Cancer dose-response extrapolations  

Energy Technology Data Exchange (ETDEWEB)

Quantitative dose-response modeling is an important contributor to cancer risk assessment; hence, it is a major factor in cancer risk management and the regulatory process. The dose-response models now used in the regulatory process are overly simplistic, probabilistic representations of highly complex biological phenomena; these models are not biological models. Several of these simplistic models provide similar fits to the high-dose data generated in chronic animal bioassays but provide dissimilar projections of risk at the lower doses of interest to man. The possibilities for the low-dose behavior of a simplistic model can be so independent of the fit of that model to the experimental data that an upper confidence limit, or upper bound, on the risk at a low dose can be orders of magnitude larger than the fitted model. The potency measures, such as unit risks and relative risks, cited by the regulatory agencies are based on upper bounds and not on fitted model values. These measurements do not differentiate between carcinogens on the basis of available experimental data about the shapes of the dose-response relationship. In order to obtain more useful quantitative dose-response assessments, the plethora of simplistic models must be replaced by more biologically reflective dose-response models that utilize the available scientific information. New dose-response modeling techniques can incorporate representations of the exposure in terms of dose scales based on cell turnover rates, repair processes, immune system responses, and physiological and pharmacokinetic models of the absorption, delivery, metabolism, and elimination of chemicals.

Sielken, R.L. Jr.

1987-11-01

371

Predicting human exposure of active drug after oral prodrug administration, using a joined in vitro/in silico-in vivo extrapolation and physiologically-based pharmacokinetic modeling approach.  

Science.gov (United States)

Introduction: Predicting the pharmacokinetics (PK) of prodrugs and their corresponding active drugs is challenging, as there are many variables to consider. Prodrug conversion characteristics in different tissues are generally measured, but integrating these variables to a PK profile is not a common practice. In this paper, a joined in vitro/in silico-in vivo extrapolation (IVIVE) and physiologically-based pharmacokinetic (PBPK) modeling approach is presented to predict active drug exposure in human after oral prodrug administration. Methods: Physico-chemical and in vitro assays as well as in silico predictions were proposed to characterize key pharmacokinetic properties (e.g. clearance, volume of distribution, conversion rates) of three marketed prodrugs. These data were used to parameterize a PBPK model for simulating human PK profiles of the active drugs after prodrug administration, which were compared to literature data by evaluating the accuracy and uncertainty of the predictions. Results: For mycophenate mofetil and midodrine the PK of their active moieties could be adequately predicted. The assumptions of the PBPK-IVIVE approach were valid, i.e. being hepatically cleared, converted in the gut lumen, blood and liver and not metabolized in the gut wall. However, the observed profiles after oral bambuterol administration clearly fell outside the prediction interval as the PBPK model failed to predict the observed bioavailability. Discussion: Adding quantitative information about prodrug conversion in the gut, liver and blood to a PBPK model for the absorption, distribution, metabolism and excretion (ADME) properties of prodrugs and their active moieties resulted, retrospectively, in reasonable predictions of the human PK when the ADME properties are well understood. Also in a prospective compound selection process, this integrative approach can improve decision making on prodrug candidates by putting relative differences in prodrug conversion of a large number of candidates into the perspective of their human PK profile, before conducting any in vivo experiments. PMID:23280406

Malmborg, Jonas; Ploeger, Bart A

2013-01-01

372

Numerical Evaluation of Feynman Integrals by a Direct Computation Method  

CERN Document Server

A purely numerical method, Direct ComputationMethod is applied to evaluate Feynman integrals. This method is based on the combination of an efficient numerical integration and an efficient extrapolation. In addition, high-precision arithmetic and parallelization technique can be used in this method if required. We present the recent progress in development of this method and show results such as one-loop 5-point and two-loop 3-point integrals.

Yuasa, F; Fujimoto, J; Hamaguchi, N; de Doncker, E; Shimizu, Y

2009-01-01

373

The efficiency variation method for 4{pi}{beta}-{gamma} coincidence counting by ink-jet printing  

Energy Technology Data Exchange (ETDEWEB)

In order to vary the counting efficiencies in the 4{pi}{beta}-{gamma} coincidence extrapolation technique, a radioactive source was coated directly with varying amounts of an electrical conducting pigment using an ink-jet printer. This method can be used to efficiently prepare the multiple sources needed to generate efficiency extrapolation curves, and was successfully applied to the standardization of a {sup 54}Mn source.

Sato, Y. [National Metrology Institute of Japan, Central 2, 1-1-1 Umezono, Tsukuba (Japan)], E-mail: yss.sato@aist.go.jp; Yamada, T. [National Metrology Institute of Japan, Central 2, 1-1-1 Umezono, Tsukuba (Japan); Japan Radioisotopes Association, 2-28-45 komagome, Bunkyo, Tokyo (Japan); Hata, T.; Moriyama, K.; Yunoki, A.; Hino, Y. [National Metrology Institute of Japan, Central 2, 1-1-1 Umezono, Tsukuba (Japan)

2008-06-15

374

Numerical methods for eigenvalue problem solution  

International Nuclear Information System (INIS)

Some problems which present interest for theoretical physics problems and the development of operator-difference schemes are considered. The solution of the scattering problem as eigenvalue problem is given. It is shown that the above method of the scattering problem solution provides the possibility to derive new functional dependences for scattering matrix parameters. It is shown as well that the complex organization of the calculation may by 15-20% reduce the calculation volume. In the iteration process one can effecively employ methods for specifying solutions for succession of condensing lattices, such as Richardson extrapolation, Pade-extrapolation and others. Newton schemes and those of perturbation theory are considered. Investigation trends presenting interest for development of numerical methods for eigenvalue problem solution in computerized models of nuclear physics are enumerated

1980-10-02

375

Hydrophobicity/hydrophilicity descriptors obtained from extrapolated chromatographic retention data as modeling tools for biological distribution: application to some oxime-type acetylcholinesterase reactivators.  

Science.gov (United States)

Chromatographic retention data obtained from interactions between some oxime-type compounds and different stationary phases (involving hydrophobic interaction, ion pairing formation availability, pi-pi, H-bonding, dipole-dipole, ion-dipole, electrostatic interaction and glycoprotein binding ability) have been studied. The logarithms of the capacity factors extrapolated at 0% or 100% organic solvent, resulting from the functional dependencies between retention and mobile phase composition, were used for estimation of different kind of hydrophobicity or hydrophilicity descriptors (HHDs) of these compounds. The conditions of the chromatographic separation were chosen as close as possible to in-vivo conditions (the aqueous component of the mobile phase has a pH in the physiologic interval 6.8-7.2, 0.9% sodium chloride was added to reproduce ionic strength and isotonic character, and the temperature was set at 37 degrees C). These descriptors characterizing the partition between stationary/mobile phases through specific interactions may be directly used for correlation to biological distribution processes, such as penetration of the blood/brain barrier. Oxime-type compounds used as acetylcholinesterase (AChE, E.C.3.1.1.7) reactivators have been considered for the retention study. The choice is supported by their use in the therapy of acute intoxication with organophosphorus AChE inhibitors (OPIs, especially nerve agents and pesticides), a rather complicated chemistry in solution and a relative lack of data about computational molecular descriptors used for modeling biological partition/distribution. Some correlations between the determined descriptors and computational values have also been discussed. PMID:20202777

Voicu, Victor; Sora, Iuliana; Sârbu, Costel; David, Victor; Medvedovici, Andrei

2010-08-01

376

Research on the test method of using injection as an equivalent substitute for electromagnetic radiation  

International Nuclear Information System (INIS)

This paper presents a method to carry out high intensity radiated field (HIRF) effect experiments by using injection as an equivalent substitute for electromagnetic radiation. In allusion to typical interconnected system, the equal response voltage on the equipment cable port is regarded as an equivalent basis of injection and radiation methods. The equivalent relation formula between injected voltage and radiated field is derived theoretically. The conditions needed for extrapolating injected voltage in HIRF are confirmed, and the extrapolation method is proposed. On the basis of the above research, the electromagnetic environment effect test new method combined injection with radiation for interconnected system is summarized. The typical nonlinear interconnected system is selected as equipment under test, and the single frequency continuous wave radiation and injection effect experiments are carried out separately. The test results indicate that the relation between radiated field and injected voltage is linear, and the equivalent injected voltage used to substitute HIRF can be obtained by linear extrapolation.

2013-03-22

377

Application of Rossi-? method to the critical experiment  

International Nuclear Information System (INIS)

The prompt neutron decay constant ? is measured with different loading by Rossi-? method. Relation formula between loading and ? can be given. The critical mass is also given from the formula with prompt neutron decay constant ?c at critical. The critical mass from formula with ?c is in better agreement with one of extrapolation and interpolation

1996-09-01

378

Measurement of low corrosion rates: comparison of a.c. impedance and thin layer activation methods  

International Nuclear Information System (INIS)

The very low corrosion rate (0.05-1 ?m per year) of 18Cr-13Ni-1Nb stainless steel in 7.8 M HNO3 at room temperature was determined with some confidence in a period of a few days by the combination of a.c. impedance and a radiotracer technique, Thin-Layer Activation. Both techniques were taken to their limits. It is argued that the a.c. method gives an upper estimate for the corrosion rate whilst the tracer method gives a lower estimate. Application of the a.c. method requires an estimate of the Tafel parameter relating corrosion rate and polarization resistance: an approximate method, utilizing the variation of the apparent value of the polarization resistance with the amplitude of the a.c. signal, is given in this paper. The corrosion rate decreased steadily with time over the first few days of exposure of the polished steel surface to the acid. Comparison of the results of the two methods suggested that there was a burst of active dissolution within the first few seconds of exposure, and some speculation about causes and consequences of this phenomenon is made. (author)

1982-01-04

379

Deve-se extrapolar o tratamento de bronquiectasias em pacientes com fibrose cística para aqueles com bronquiectasias de outras etiologias? Should the bronchiectasis treatment given to cystic fibrosis patients be extrapolated to those with bronchiectasis from other causes?  

Directory of Open Access Journals (Sweden)

Full Text Available OBJETIVO: Conhecer o perfil de pacientes adultos com bronquiectasias, comparando portadores de fibrose cística (FC com aqueles com bronquiectasias de outra etiologia, a fim de determinar se é racional extrapolar terapêuticas instituídas em fibrocísticos para aqueles com bronquiectasias de outras etiologias. MÉTODOS: Análise retrospectiva dos prontuários de 87 pacientes adultos com diagnóstico de bronquiectasia em acompanhamento em nosso serviço. Pacientes com doença secundária a infecção por tuberculose corrente ou no passado foram excluídos. Foram avaliados dados clínicos, funcionais e terapêuticos dos pacientes. RESULTADOS: Dos 87 pacientes com bronquiectasias, 38 (43,7% tinham diagnóstico confirmado de FC através de dosagem de sódio e cloro no suor ou análise genética, enquanto 49 (56,3% apresentavam a doença por outra etiologia, 34 (39,0% desses com bronquiectasia idiopática. Os pacientes com FC apresentavam média de idade ao diagnóstico mais baixa (14,2 vs. 24,2 anos; p OBJECTIVE: To profile the characteristics of adult patients with bronchiectasis, drawing comparisons between cystic fibrosis (CF patients and those with bronchiectasis from other causes in order to determine whether it is rational to extrapolate the bronchiectasis treatment given to CF patients to those with bronchiectasis from other causes. METHODS: A retrospective analysis of the medical charts of 87 patients diagnosed with bronchiectasis and under follow-up treatment at our outpatient clinic. Patients who had tuberculosis (current or previous were excluded. We evaluated the clinical, functional, and treatment data of the patients. RESULTS: Of the 87 patients with bronchiectasis, 38 (43.7% had been diagnosed with CF, through determination of sweat sodium and chloride concentrations or through genetic analysis, whereas the disease was due to another etiology in 49 (56.3%, of whom 34 (39.0% had been diagnosed with idiopathic bronchiectasis. The mean age at diagnosis was lower in the patients with CF than in those without (14.2 vs. 24.2 years; p < 0.05. The prevalence of symptoms (cough, expectoration, hemoptysis, and wheezing was similar between the groups. Colonization by Pseudomonas aeruginosa or Staphylococcus aureus was more common in the CF patients (82.4 vs. 29.7% and 64.7 vs. 5.4%, respectively. CONCLUSIONS: The causes and clinical manifestations of bronchiectasis are heterogeneous, and it is important to identify the differences. It is crucial that these differences be recognized so that new strategies for the management of patients with bronchiectasis can be developed.

Rodrigo Abensur Athanazio

2010-08-01

380

Deve-se extrapolar o tratamento de bronquiectasias em pacientes com fibrose cística para aqueles com bronquiectasias de outras etiologias? / Should the bronchiectasis treatment given to cystic fibrosis patients be extrapolated to those with bronchiectasis from other causes?  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese OBJETIVO: Conhecer o perfil de pacientes adultos com bronquiectasias, comparando portadores de fibrose cística (FC) com aqueles com bronquiectasias de outra etiologia, a fim de determinar se é racional extrapolar terapêuticas instituídas em fibrocísticos para aqueles com bronquiectasias de outras et [...] iologias. MÉTODOS: Análise retrospectiva dos prontuários de 87 pacientes adultos com diagnóstico de bronquiectasia em acompanhamento em nosso serviço. Pacientes com doença secundária a infecção por tuberculose corrente ou no passado foram excluídos. Foram avaliados dados clínicos, funcionais e terapêuticos dos pacientes. RESULTADOS: Dos 87 pacientes com bronquiectasias, 38 (43,7%) tinham diagnóstico confirmado de FC através de dosagem de sódio e cloro no suor ou análise genética, enquanto 49 (56,3%) apresentavam a doença por outra etiologia, 34 (39,0%) desses com bronquiectasia idiopática. Os pacientes com FC apresentavam média de idade ao diagnóstico mais baixa (14,2 vs. 24,2 anos; p Abstract in english OBJECTIVE: To profile the characteristics of adult patients with bronchiectasis, drawing comparisons between cystic fibrosis (CF) patients and those with bronchiectasis from other causes in order to determine whether it is rational to extrapolate the bronchiectasis treatment given to CF patients to [...] those with bronchiectasis from other causes. METHODS: A retrospective analysis of the medical charts of 87 patients diagnosed with bronchiectasis and under follow-up treatment at our outpatient clinic. Patients who had tuberculosis (current or previous) were excluded. We evaluated the clinical, functional, and treatment data of the patients. RESULTS: Of the 87 patients with bronchiectasis, 38 (43.7%) had been diagnosed with CF, through determination of sweat sodium and chloride concentrations or through genetic analysis, whereas the disease was due to another etiology in 49 (56.3%), of whom 34 (39.0%) had been diagnosed with idiopathic bronchiectasis. The mean age at diagnosis was lower in the patients with CF than in those without (14.2 vs. 24.2 years; p

Rodrigo Abensur, Athanazio; Samia Zahi, Rached; Ciro, Rohde; Regina Carvalho, Pinto; Frederico Leon Arrabal, Fernandes; Rafael, Stelmach.

 
 
 
 
381

Determination of corrosion rate from electrode kinetic measurement  

International Nuclear Information System (INIS)

Electrode kinetic measurements provide a valuable technique for determining the corrosion rates of metals. The processes controlled by activation polarization are described by an exponential type of relation involving three unknowns. Corrosion behaviour of a metal can be fully described if these three parameters i.e. corrosion current, Ic and the two Tafel constants Beta/sub a/ and Beta/sub c/ are known. Experimentally the current density is measured as a function of the applied over relationship is such that an accurate determination of the three parameters by Ordinary Least Squares Fit is generally not possible. Various attempts have been made to simplify the equation using approximations. These are reflected in the well known methods such as Tafel Line Extrapolation and Linear Polarization. In Three Point and Four Point methods, selected data points are used which transform the original equation into similar relation such as a quadratic equation. Recently some computer based methods have been developed such as BETACRUNCH in which the method of averages is used. We have developed a new method to analyze experimental polarization data and determine the unknown parameters. We have formulated three independent relationships to solve for Ic, Ba and Beta/sub c/. In addition to the original version we have improved the methods by using some additional numerical approaches. These methods are robust and give accurate determination of Tafel constants and the corrosion current density for a wide range of systems. Using the suggested scheme, it is also possible to avoid data corresponding to very low and very high over potentials and yet obtain excellent results. These methods are less sensitive to experimental errors as compared to other existing methods. (author)

1993-01-01

382

Offnormal Incidence Reflection-Coefficient Determination for Thick Underwater Acoustic Panels Using a Generalized ONION Method.  

Science.gov (United States)

The ONION method is a reflection-coefficient measurement technique designed for use on data acquired from thick underwater acoustic panels in the frequency range 1-10 kHz, but may be used to frequencies as high as 25 kHz. The method extrapolates transient...

J. C. Piquette

1990-01-01

383

Preconditioning the power method for reactor calculations  

International Nuclear Information System (INIS)

Several preconditioning techniques were applied to the power method in conjunction with a symmetric variational acceleration strategy, to facilitate solution of reactor problems. First, the drawbacks in an approximate inversion were corrected by fitting an error recovery term to the power method. Second, a variational extrapolation technique that does not require knowledge of the dominance ratio was introduced. Validation results are reported for the International Atomic Energy Agency two- and three-dimensional benchmarks and for a two-dimensional pressurized water reactor representation

1986-01-01

384

Copper complex N(4)-ortho-toluyl-2-acetylpyridine thiosemicarbazone - ({sup 64}Cu)(H2Ac4oT)Cl - internal dosimetry: animal model and human extrapolation  

Energy Technology Data Exchange (ETDEWEB)

Thiosemicarbazones have attracted great pharmacological interest because of their biological properties, such as cytotoxic activity against multiple strains of human tumors. Due to the excellent properties of {sup 64}Cu, the copper complex N(4)-ortho-toluyl-2-acetylpyridine thiosemicarbazone (({sup 64}Cu)(H2Ac4oT)Cl) was developed for tumor detection by positron emission tomography. The radiopharmaceuticals were produced in the nuclear reactor TRIGA-IPR-R1 from CDTN. At the present work, ({sup 64}Cu)(H2Ac4oT)Cl biokinetic data (evaluated in mice bearing Ehrlich tumor) were treated by MIRD formalism to perform Internal Dosimetry studies. Doses in several organs of mice were determinate, as well as in implanted tumor, for ({sup 64}Cu)(H2Ac4oT)Cl. Doses results obtained for animal model were extrapolated to humans assuming a similar concentration ratio among various tissues between mouse and human. In the extrapolation, it was used human organ masses from Cristy/Eckerman phantom. Both penetrating and non-penetrating radiation from {sup 64}Cu in the tissue were considered in dose calculations. (author)

Rodrigues, Josianne L.; Silva, Paulo R.O.; Santos, Raquel G.; Ferreira, Andrea V., E-mail: jlr@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2011-07-01

385

Copper corrosion inhibition in O{sub 2}-saturated H{sub 2}SO{sub 4} solutions  

Energy Technology Data Exchange (ETDEWEB)

Corrosion inhibition of copper in O{sub 2}-saturated 0.50 M H{sub 2}SO{sub 4} solutions by four selected amino acids, namely glycine (Gly), alanine (Ala), valine (Val), or tyrosine (Tyr), was studied using Tafel polarization, linear polarization, impedance, and electrochemical frequency modulation (EFM) at 30 deg. C. Protection efficiencies of almost 98% and 91% were obtained with 50 mM Tyr and Gly, respectively. On the other hand, Ala and Val reached only about 75%. Corrosion rates determined by the Tafel extrapolation method were in good agreement with those obtained by EFM and an independent chemical (i.e., non-electrochemical) method. The chemical method of confirmation of the corrosion rates involved determination of the dissolved Cu{sup 2+}, using ICP-AES (inductively coupled plasma atomic emission spectrometry) method of chemical analysis. Nyquist plots exhibited a high frequency depressed semicircle followed by a straight line portion (Warburg diffusion tail) in the low-frequency region. The impedance data were interpreted according to two suitable equivalent circuits. The kinetics of dissolved O{sub 2} reduction and hydrogen evolution reactions on copper surface were also studied in O{sub 2}-saturated 0.50 M H{sub 2}SO{sub 4} solutions using polarization measurements combined with the rotating disc electrode (RDE). The Koutecky-Levich plot indicated that the dissolved O{sub 2} reduction at the copper electrode was an apparent 4-electron process.

Amin, Mohammed A. [Materials and Corrosion Lab (MCL), Department of Chemistry, Faculty of Science, Taif University, 888 Hawiya, KSA (Egypt); Chemistry Department, Faculty of Science, Ain Shams University, Abbassia, Cairo (Egypt)], E-mail: maaismail@yahoo.com; Khaled, K.F. [Materials and Corrosion Lab (MCL), Department of Chemistry, Faculty of Science, Taif University, 888 Hawiya, KSA (Egypt); Electrochemistry Research Laboratory, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt)

2010-04-15

386

Copper corrosion inhibition in O2-saturated H2SO4 solutions  

International Nuclear Information System (INIS)

Corrosion inhibition of copper in O2-saturated 0.50 M H2SO4 solutions by four selected amino acids, namely glycine (Gly), alanine (Ala), valine (Val), or tyrosine (Tyr), was studied using Tafel polarization, linear polarization, impedance, and electrochemical frequency modulation (EFM) at 30 deg. C. Protection efficiencies of almost 98% and 91% were obtained with 50 mM Tyr and Gly, respectively. On the other hand, Ala and Val reached only about 75%. Corrosion rates determined by the Tafel extrapolation method were in good agreement with those obtained by EFM and an independent chemical (i.e., non-electrochemical) method. The chemical method of confirmation of the corrosion rates involved determination of the dissolved Cu2+, using ICP-AES (inductively coupled plasma atomic emission spectrometry) method of chemical analysis. Nyquist plots exhibited a high frequency depressed semicircle followed by a straight line portion (Warburg diffusion tail) in the low-frequency region. The impedance data were interpreted according to two suitable equivalent circuits. The kinetics of dissolved O2 reduction and hydrogen evolution reactions on copper surface were also studied in O2-saturated 0.50 M H2SO4 solutions using polarization measurements combined with the rotating disc electrode (RDE). The Koutecky-Levich plot indicated that the dissolved O2 reduction at the copper electrode was an apparent 4-electron process.

2010-04-01

387

Corporate Governance in Post-Socialist Countries - Theoretical Dilemmas, Peculiarities, Research Opportunities / Külliki Tafel, Erik Terk, Alari Purju  

Index Scriptorium Estoniae

Äriühingute valitsemine postsotsialistlikes riikides - teoreetilised dilemmad, eripärad, uurimisvõimalused. Skeemid: Internal and external relations of corporate governanace; The changing context of corporate governance

Tafel, Külliki

2006-01-01

388

Kolm linna ja kolm lähenemist loovusele ja kultuuri arendamisele : Tartu, Turu ja Bergen : loomemajandus / Külliki Tafel, Erik Terk  

Index Scriptorium Estoniae

Tartu, Turu ja Bergen koostasid Põhjamaade Innovatsioonikeskuse projekti "Nordic Model for Creative Industries Development Center" raames oma linnade loomemajanduse arendamise dokumendi. Võrreldakse valminud dokumente

Tafel, Külliki

2008-01-01

389

Abnormalities Of Larval Male Gonads Of SPODOPTERA LITTORALIS (BOISD.) After Exposure To GAMMA Radiation In Combined With Tafel Leaves Extract  

International Nuclear Information System (INIS)

The effect of sub-sterilizing dose of gamma radiation (125 Gy) alone or in joint with different concentrations of tafla leaves extract Nerium oleander on the histology and histochemistry of the larval male reproductive system were studied. The treatment caused histopathological changes in the testes including necrosis of spermatocytes, retardation of sperm maturation, bursting of sperm bundles and the vacuolated area resulting from depletion of spermatogonia that increased in size.Histochemical studies showed that protein contents and RNA were increased while DNA content was decreased in male gonads.

2009-01-01

390

Investigation of kinetics of zirconium hydroxide thermolysis by the derivatographic method  

International Nuclear Information System (INIS)

As a result of processing the thermolysis derivatograms of Zr(OH)4x1.305, it has been established that the process proceeds in six stages. The activation energies and the rates of thermolysis have been found with the help of the step-wise kinetic analysis of the process and the extrapolation method

1977-08-01

391

Reply to ``Comment on `Determination of the bulk melting temperature of nickel using Monte Carlo simulations: Inaccuracy of extrapolation from cluster melting temperatures' ''  

Science.gov (United States)

The thermodynamic integration (TI) method for determining the melting temperature has to be performed with great care to ensure accuracy. Since the slopes of the Gibbs free energy curves as a function of temperature (or pressure) are usually rather close, small shifts in the free energy curves can lead to a large change in the calculated melting temperature. In this Reply to a Comment by Harvey and Gheribi [Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.84.096102 84, 096102 (2011)] on our paper [Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.81.064112 81, 064112 (2010)], we show that the error in the calculated melting temperature of nickel induced by some technical imperfections in our application of the TI method, as noticed and described in the Comment, is small compared to the error bar given in our paper. We also clarify supposed doubts about the accuracy of the TI method based on Johnson's free energy expression and parametrization [Johnson , Mol. Phys.MOPHAM0026-897610.1080/00268979300100411 78, 591 (1993)] of the Lennard-Jones fluid.

Los, J. H.; Pellenq, R. J. M.

2011-09-01

392

Report on the uncertainty methods study  

International Nuclear Information System (INIS)

The Uncertainty Methods Study (UMS) Group, following a mandate from CSNI, has compared five methods for calculating the uncertainty in the predictions of advanced 'best estimate' thermal-hydraulic codes: the Pisa method (based on extrapolation from integral experiments) and four methods identifying and combining input uncertainties. Three of these, the GRS, IPSN and ENUSA methods, use subjective probability distributions, and one, the AEAT method, performs a bounding analysis. Each method has been used to calculate the uncertainty in specified parameters for the LSTF SB-CL-18 5% cold leg small break LOCA experiment in the ROSA-IV Large Scale Test Facility (LSTF). The uncertainty analysis was conducted essentially blind and the participants did not use experimental measurements from the test as input apart from initial and boundary conditions. Participants calculated uncertainty ranges for experimental parameters including pressurizer pressure, primary circuit inventory and clad temperature (at a specified position) as functions of time

1998-01-01

393

A method for measuring light ion reaction cross sections  

Energy Technology Data Exchange (ETDEWEB)

An experimental procedure for measuring reaction cross sections of light ions in the energy range 20-50 MeV/nucleon, using a modified attenuation technique, is described. The detection method incorporates a forward detector that simultaneously measures the reaction cross sections for five different sizes of the solid angles in steps from 99.1 to 99.8% of the total solid angle. The final reaction cross section values are obtained by extrapolation to the full solid angle.

Carlson, R.F. [Univ. of Redlands, CA (United States). Dept. of Physics; Ingemarsson, A.; Lantz, M. [Uppsala Univ. (Sweden). Dept. of Radiation Sciences] [and others

2005-03-01

394

Capacity for work researching method in animal experiment  

International Nuclear Information System (INIS)

The existing methods of examining the work capacity of animals are discussed with reference to extrapolation of animal data to man. A modified procedure for measuring maximal physical strength is proposed, whereby static endurance of animals at a given exercise rate can be measured. For an integrated evaluation of work capacity, a formula of absolute work capacity is suggested. The proposed procedure may be used to study the working capacity of animals exposed to unfavorable factors of radiation or nonradiation nature

1978-01-01

395

Splitting methods for Levitron Problems  

CERN Document Server

In this paper we describe splitting methods for solving Levitron, which is motivated to simulate magnetostatic traps of neutral atoms or ion traps. The idea is to levitate a magnetic spinning top in the air repelled by a base magnet. The main problem is the stability of the reduced Hamiltonian, while it is not defined at the relative equilibrium. Here it is important to derive stable numerical schemes with high accuracy. For the numerical studies, we propose novel splitting schemes and analyze their behavior. We deal with a Verlet integrator and improve its accuracy with iterative and extrapolation ideas. Such a Hamiltonian splitting method, can be seen as geometric integrator and saves computational time while decoupling the full equation system. Experiments based on the Levitron model are discussed.

Geiser, Juergen

2012-01-01

396

Reply to “Comment on ‘Determination of the bulk melting temperature of nickel using Monte Carlo simulations: Inaccuracy of extrapolation from cluster melting temperatures' ”  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The thermodynamic integration (TI) method for determining the melting temperature has to be performed with great care to ensure accuracy. Since the slopes of the Gibbs free energy curves as a function of temperature (or pressure) are usually rather close, small shifts in the free energy curves can lead to a large change in the calculated melting temperature. In this Reply to a Comment by Harvey and Gheribi [ Phys. Rev. B 84 096102 (2011)] on our paper [ Phys. Rev. B 81 064112 (2010)], we show...

Los, J. H.; Pellenq, Roland J. -m

2011-01-01

397

Quick Method for Determining Plant Available Water  

International Nuclear Information System (INIS)

For the first few days after heavy rain or irrigations, water drains from the soil profile until its water content approaches a relatively stable value called the drained upper limit or field capacity. When plants have extracted all of the water available to them, the root zone water content approaches a lower limit of available water, or permanent wilting water content. The water held by the soil between these two limits is called plant available water. These two limits are often associated with water content values at specific soil water potentials, (a measure of pressure at soil water is extracted). Field capacity is often taken as the water content of a soil at -33 kPa water potential. Permanent wilt is taken as the water content at -1500 kPa. The methods typically used to determine plant available water are slow and inaccurate. We present here (1) a method for measuring field capacity using a tensiometer and an extrapolation technique, and (2) a method for measuring permanent wilting water content with a dew point potentiameter and an extrapolation method which are much faster and more accurate than traditional methods. (author)

2010-07-01

398

Development of a multi-electrode extrapolation chamber as a prototype of a primary standard for the realization of the unit of the absorbed dose to water for beta brachytherapy sources  

CERN Document Server

The prototype of a primary standard has been developed, built and tested, which enables the realization of the unit of the absorbed dose to water for beta brachytherapy sources. In the course of the development of the prototype, the recommendations of the American Association of Physicists in Medicine (AAPM) Task Group 60 (TG60) and the Deutsche Gesellschaft fuer Medizinische Physik (DGMP) Arbeitskreis 18 (AK18) were taken into account. The prototype is based on a new multi-electrode extrapolation chamber (MEC) which meets, in particular, the requirements on high spatial resolution and small uncertainty. The central part of the MEC is a segmented collecting electrode which was manufactured in the clean room center of PTB by means of electron beam lithography on a wafer. A precise displacement device consisting of three piezoelectric macrotranslators has been incorporated to move the wafer collecting electrode against the entrance window. For adjustment of the wafer collecting electrode parallel to the entranc...

Bambynek, M

2002-01-01

399

An improved Compton scattering method for determination of concentration of solutions  

International Nuclear Information System (INIS)

An improved Compton scattering method for determination of concentration of low-Z solutions is presented. The Monte Carlo (MC) numerical simulation of the scattering phenomena is done using the MCNP code. A unique non-linear extrapolation method is followed in correcting the scattered intensity for self-absorption and multiple scattering. The density ratios obtained using non linear extrapolated scattered intensity values are free from self-absorption and multiple scattering and agree well with the standard ones within experimental errors. The sensitivity study of transmission and scattering methods for determination of concentration of solutions having closer attenuation parameters at 661.6 keV is carried out to predict the range of effectiveness and suitability of these methods. The slopes (sensitivity/unit concentration) of the curves obtained from scattering method are higher by a factor of 1.26 compared to those of the transmission method in the measured range of concentrations. - Highlights: ? Improved Compton scattering method for determination of concentration of solutions. ? The Monte Carlo (MC) numerical simulation of the scattering phenomena is done. ? A unique extrapolation method of correcting self-absorption and multiple scattering. ? The sensitivity of the scattering method is higher compared to the transmission method.

2012-10-01

400

Research of method for activity measurement of neutron-activation-foil  

International Nuclear Information System (INIS)

This paper puts forward a new method measuring the activity of neutron-activation-foil using 4??-? coincidence equipment without making thin film source. By changing the voltage of photomultiplier tube, keeping the same efficiency of the ? detector in detection of ? photon and X ray of K shell, we can obtain the activity of neutron-activation-foil, without using efficiency extrapolation method. Theory analysis indicates that the method is feasible. (authors)

2007-08-01

 
 
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