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.
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.
Extrapolation methods for vector sequences
Smith, David A.; Ford, William F.; Sidi, Avram
1987-01-01
This paper derives, describes, and compares five extrapolation methods for accelerating convergence of vector sequences or transforming divergent vector sequences to convergent ones. These methods are the scalar epsilon algorithm (SEA), vector epsilon algorithm (VEA), topological epsilon algorithm (TEA), minimal polynomial extrapolation (MPE), and reduced rank extrapolation (RRE). MPE and RRE are first derived and proven to give the exact solution for the right 'essential degree' k. Then, Brezinski's (1975) generalization of the Shanks-Schmidt transform is presented; the generalized form leads from systems of equations to TEA. The necessary connections are then made with SEA and VEA. The algorithms are extended to the nonlinear case by cycling, the error analysis for MPE and VEA is sketched, and the theoretical support for quadratic convergence is discussed. Strategies for practical implementation of the methods are considered.
Extrapolation methods theory and practice
Brezinski, C
1991-01-01
This volume is a self-contained, exhaustive exposition of the extrapolation methods theory, and of the various algorithms and procedures for accelerating the convergence of scalar and vector sequences. Many subroutines (written in FORTRAN 77) with instructions for their use are provided on a floppy disk in order to demonstrate to those working with sequences the advantages of the use of extrapolation methods. Many numerical examples showing the effectiveness of the procedures and a consequent chapter on applications are also provided - including some never before published results and applicat
? ? scattering by pole extrapolation methods
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A 25-inch hydrogen bubble chamber was used at the Lawrence Berkeley Laboratory Bevatron to produce 300,000 pictures of ?+p interactions at an incident momentum of the ?+ of 2.67 GeV/c. The 2-prong events were processed using the FSD and the FOG-CLOUDY-FAIR data reduction system. Events of the nature ?+p??+p?0 and ?+p??+?+n with values of momentum transfer to the proton of -t less than or equal to 0.238 GeV2 were selected. These events were used to extrapolate to the pion pole (t = m/sub ?/2) in order to investigate the ? ? interaction with isospins of both T=1 and T=2. Two methods were used to do the extrapolation: the original Chew-Low method developed in 1959 and the Durr-Pilkuhn method developed in 1965, which takes into account centrifugal barrier penetration factors. At first it seemed that, while the Durr-Pilkuhn method gave better values for the total ? ? cross section, the Chew-Low method gave better values for the angular distribution. Further analysis, however, showed that, if the requirement of total OPE (one-pion-exchange) was dropped, then the Durr-Pilkuhn method gave more reasonable values of the angular distribution as well as for the total ? ? cross section
Recursive algorithms for vector extrapolation methods
Ford, William F.; Sidi, Avram
1988-01-01
Three classes of recursion relations are devised for implementing some extrapolation methods for vector sequences. One class of recursion relations can be used to implement methods like the modified minimal polynomial extrapolation and the topological epsilon algorithm; another allows implementation of methods like minimal polynomial and reduced rank extrapolation; while the remaining class can be employed in the implementation of the vector E-algorithm. Operation counts and storage requirements for these methods are also discussed, and some related techniques for special applications are also presented. Included are methods for the rapid evaluations of the vector E-algorithm.
Implicit Extrapolation Methods for Variable Coefficient Problems
Jung, M.; Ruede, U.
1996-01-01
Implicit extrapolation methods for the solution of partial differential equations are based on applying the extrapolation principle indirectly. Multigrid tau-extrapolation is a special case of this idea. In the context of multilevel finite element methods, an algorithm of this type can be used to raise the approximation order, even when the meshes are nonuniform or locally refined. Here previous results are generalized to the variable coefficient case and thus become applicable for nonlinear problems. The implicit extrapolation multigrid algorithm converges to the solution of a higher order finite element system. This is obtained without explicitly constructing higher order stiffness matrices but by applying extrapolation in a natural form within the algorithm. The algorithm requires only a small change of a basic low order multigrid method.
Prajitno, Djoko Hadi
2015-09-01
The Effects of scan rate on the Tafel polarization curve that is obtained to determine corrosion rate are conducted. The tafel polarization curves are obtained at different scan rates for Stainless Steel 304 in nanofluids contain 0.01 gpl nano particle ZrO2. The corrosion stainless steel in nanofluid contains adm+0.01 gpl ZrO2 nanoparticles at different scan rate was performed by Tafel polarization. The results show that according corrosion potential examination of the stainless steel in nanofluid media 0.01gpl ZrO2 nanoparticle was actively corroded. The value of cathodic Tafel slope stainless steel in nanofluid at different scan rate relatively unchanged after polarization testing. Mean while the value of anodic Tafel slope stainless steel in nanofluid increase at different scan rate. The results of Tafel polarization technique show that corrosion rate of stainless steel in nanofluid increase with increasing scan rate. X ray diffraction examination of stainless steel after Tafel polarization depict that ? Fe phase is major phase in the surface of alloy.
An extrapolation method for shell model calculations
Mizusaki, Takahiro; Imada, Masatoshi
2002-01-01
We propose a new shell model method, combining the Lanczos digonalization and extrapolation method. This method can give accurate shell model energy from a series of shell model calculations with various truncation spaces, in a well-controlled manner. Its feasibility is demonstrated by taking the fp shell calculations.
Extrapolation theory for the real interpolation method
Carro Rossell, María Jesús; Martín i Pedret, Joaquim
2002-01-01
We develop an abstract extrapolation theory for the real interpolation method that covers and improves the most recent versions of the celebrated theorems of Yano and Zygmund. As a consequence of our method, we give new endpoint estimates of the embedding Sobolev theorem for an arbitrary domain Omega
The optimizied expansion method for wavefield extrapolation
Wu, Z.
2013-01-01
Spectral methods are fast becoming an indispensable tool for wave-field extrapolation, especially in anisotropic media, because of its dispersion and artifact free, as well as highly accurate, solutions of the wave equation. However, for inhomogeneous media, we face difficulties in dealing with the mixed space-wavenumber domain operator.In this abstract, we propose an optimized expansion method that can approximate this operator with its low rank representation. The rank defines the number of inverse FFT required per time extrapolation step, and thus, a lower rank admits faster extrapolations. The method uses optimization instead of matrix decomposition to find the optimal wavenumbers and velocities needed to approximate the full operator with its low rank representation.Thus,we obtain more accurate wave-fields using lower rank representation, and thus cheaper extrapolations. The optimization operation to define the low rank representation depends only on the velocity model, and this is done only once, and valid for a full reverse time migration (many shots) or one iteration of full waveform inversion. Applications on the BP model yielded superior results than those obtained using the decomposition approach. For transversely isotopic media, the solutions were free of the shear wave artifacts, and does not require that eta>0.
Extrapolation of Tikhonov and Lavrentiev regularization methods
International Nuclear Information System (INIS)
We consider solution of linear ill-posed problem Au = f by Tikhonov method and by Lavrentiev method. For increasing the qualification and accuracy of these methods we use extrapolation, taking for the approximate solution linear combination of n ? 2 approximations of Tikhonov or Lavrentiev methods with different parameters and with proper coefficients. If the solution u* belongs to R((A*A)n) and instead of f noisy data f? with ||f? - f|| ? ? are available, maximal guaranteed accuracy of Tikhonov and Lavrentiev approximations is O(?2/3) and O(?1/2), respectively, versus accuracy O(?2n/(2n+1)) and O(?n/(n+1)) of corresponding extrapolated approximations. We propose several new rules for a posteriori choice of the regularization parameter, including modifications of the monotone error rule. Extensive numerical experiments show that in case u* ? R(A*) the extrapolated Tikhonov approximation with a posteriori parameter choice (not using any smoothness information) is typically more accurate than Tikhonov approximation with optimal parameter.
Extrapolation methods for dynamic partial differential equations
Turkel, E.
1978-01-01
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.
An efficient method to evaluate energy variances for extrapolation methods
Puddu, G.
2012-01-01
The energy variance extrapolation method consists in relating the approximate energies in many-body calculations to the corresponding energy variances and inferring eigenvalues by extrapolating to zero variance. The method needs a fast evaluation of the energy variances. For many-body methods that expand the nuclear wave functions in terms of deformed Slater determinants, the best available method for the evaluation of energy variances scales with the sixth power of the numb...
Implicit extrapolation methods for multilevel finite element computations
Jung, M.; Rüde, U.
1998-01-01
Extrapolation methods for the solution of partial differential equations are commonly based on the existence of error expansions for the approximate solution. Implicit extrapolation, in the contrast, is based on applying extrapolation indirectly, by using it on quantities like the residual. In the context of multigrid methods, a special technique of this type is known as \\034 -extrapolation. For finite element systems this algorithm can be shown to be equivalent to higher order finite element...
Extrapolation Method for System Reliability Assessment
DEFF Research Database (Denmark)
Qin, Jianjun; Nishijima, Kazuyoshi; Faber, Michael Havbro
2012-01-01
The present paper presents a new scheme for probability integral solution for system reliability analysis, which takes basis in the approaches by Naess et al. (2009) and Bucher (2009). The idea is to evaluate the probability integral by extrapolation, based on a sequence of MC approximations of integrals with scaled domains. The performance of this class of approximation depends on the approach applied for the scaling and the functional form utilized for the extrapolation. A scheme for this task...
Determination of Tafel slopes from coulostatically induced transients using an integral algorithm
International Nuclear Information System (INIS)
The analysis of coulostatically induced transients (CITs) has been used as a tool to evaluate the corrosion rate of metallic materials, and a new algorithm has been developed to calculate the Tafel slopes (b a and b c). This new algorithm is based on the coulostatic strong polarization integration (CSPI) method. Experimental results for carbon steels exposed to 0.5 M H2SO and 1 M HCl show excellent agreement between the proposed method and the Tafel line extrapolation method with IR drop correction. Furthermore, the calculated average corrosion currents over 8 h tests are in good agreement with solution analysis data from atomic absorption spectroscopy. The improved CSPI algorithm shows superior performance over the differential algorithm and the conventional algorithm due to its simplicity and higher signal/noise ratio
An efficient method to evaluate energy variances for extrapolation methods
Puddu, G
2012-01-01
The energy variance extrapolation method consists in relating the approximate energies in many-body calculations to the corresponding energy variances and inferring eigenvalues by extrapolating to zero variance. The method needs a fast evaluation of the energy variances. For many-body methods that expand the nuclear wave functions in terms of deformed Slater determinants, the best available method for the evaluation of energy variances scales with the sixth power of the number of single-particle states. We propose a new method which depends on the number of single-particle orbits and the number of particles rather than the number of single-particle states. We discuss as an example the case of ${}^4He$ using the chiral N3LO interaction in a basis consisting up to 184 single-particle states.
Multiparameter extrapolation and deflation methods for solving equation systems
Directory of Open Access Journals (Sweden)
A. J. Hughes Hallett
1984-12-01
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.
Assessment of Load Extrapolation Methods for Wind Turbines
DEFF Research Database (Denmark)
Toft, Henrik Stensgaard; Sørensen, John Dalsgaard; Veldkamp, Dick
2011-01-01
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 wind-turbine 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 ...
Assessment of Load Extrapolation Methods for Wind Turbines
DEFF Research Database (Denmark)
Toft, Henrik Stensgaard; Sørensen, John Dalsgaard; Veldkamp, Dick
2011-01-01
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 s...
Assessment of Load Extrapolation Methods for Wind Turbines
DEFF Research Database (Denmark)
Toft, Henrik Stensgaard; Sørensen, John Dalsgaard
2010-01-01
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 flap bending moment of a wind turbine 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...
Extrapolation method in shell model calculations with deformed basis
Mizusaki, Takahiro
2004-01-01
An extrapolation method in shell model calculations with deformed basis is presented, which uses a scaling property of energy and energy variance for a series of systematically approximated wave functions to the true one. Such approximated wave functions are given by variation-after-projection method concerning the full angular momentum projection. This extrapolation needs energy variance, which amounts to the calculation of expectation value of square of Hamiltonian $\\hat{H...
Extrapolation Method for the No-Core Shell Model
Zhan, H; Nogga, A.; Barrett, B.R.; Vary, J. P.; Navratil, P
2004-01-01
Nuclear many-body calculations are computationally demanding. An estimate of their accuracy is often hampered by the limited amount of computational resources even on present-day supercomputers. We provide an extrapolation method based on perturbation theory, so that the binding energy of a large basis-space calculation can be estimated without diagonalizing the Hamiltonian in this space. The extrapolation method is tested for 3H and 6Li nuclei. It will extend our computatio...
Fully vectorial laser resonator modeling by vector extrapolation methods
Asoubar, Daniel; Kuhn, Michael; Wyrowski, Frank
2015-02-01
The optimization of multi-parameter resonators requires flexible simulation techniques beyond the scalar approximation. Therefore we generalize the scalar Fox and Li algorithm for the transversal eigenmode calculation to a fully vectorial model. This modified eigenvalue problem is solved by two polynomial-type vector extrapolation methods, namely the minimal polynomial extrapolation and the reduced rank extrapolation. Compared to other eigenvalue solvers these techniques can also be applied to resonators including nonlinear components. As an example we show the calculation of an azimuthally polarized eigenmode emitted by a resonator containing a discontinuous phase element and a nonlinear active medium. The simulation is verified by experiments.
Implicit extrapolation methods for multilevel finite element computations
Energy Technology Data Exchange (ETDEWEB)
Jung, M.; Ruede, U. [Technische Universitaet Chemnitz-Zwickau (Germany)
1994-12-31
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.
Analysis of accuracy of activity measurement for extrapolation coincidence methods
International Nuclear Information System (INIS)
Grounds have been presented as well as an order of actions in application of the methods of extrapolation of activity values depending on efficiency of counting in the case of absolute measurements of radioactivity concentration by the coincidence methods and application of the metrological labels technick. Influence has been shown of geometry of distribution of measurement points on the accuracy of determination of the value to be extrapolated. Results have been given of investigations of influ ence if straggling of counting efficiency on the results of extrapolation and on the value of the random error taking into account inclination of extrapolation curve. Methodology has been present ed of determination of statistical weight of points which had been used for plotting of the extrapolation curve. Dependence has bee n deducted of the random error in measurement of emitter's activity and activity of a label in a summary radiation source. This depe ndence permits to finde optimum conditions for measuring of the emi tter's activity in different systems of metrological label-emitter
Accurate Measurements of Drop Weights by the Extrapolation Method
International Nuclear Information System (INIS)
The extrapolation method, which is one of the two methods currently employed by standardizing laboratories for the weighing of drops of radioactive solutions, easily leads to errors. However, it is very convenient to store active solutions in rubber-capped vials and to use disposable syringes for extractions and depositions; it is then also convenient to use the extrapolation technique for weighing. Studies have been made with the aim of attaining accuracies for the extrapolation method of not less than the ± 10 ?g attainable with the pycnometer method. The following procedures were adopted: (a) The standard method, but with weighings started sufficiently early to account as much as possible for non-equilibrium effects; (b) The high humidity method; it was expected that the non-equilibrium effects would be reduced by operating as close as practicable to a relative humidity (rh) of 100%; and (c) The sleeve method where the non-equilibrium effects are reduced by cooling the active solution prior to the depositions. Within the range rh 50% - 75%, weighings with method (c) yield radioactive concentrations identical (within ± 0.1%) to the results obtained with the pycnometer method. Method (a) is somewhat less reliable than method (c), method (b) offers no advantages over measurements within the readily attainable range of rh 50% - 75%. (author)
Methods for Extrapolating Risk Equations Beyond Their Valid Intervals
Methods for Extrapolating Risk Equations Beyond Their Valid Intervals Griffin Weber, S.M., Nananda F. Col, M.D., M.P.P., M.P.H., F.A.C.P. Decision Systems Group, Division of Women’s Health, Harvard Medical School, Boston, MA Purpose: Decision models
Novel extrapolation method in the Monte Carlo shell model
Shimizu, Noritaka; Utsuno, Yutaka; Mizusaki, Takahiro; Otsuka, Taka; Abe, Takashi; Honma, Michio
2010-01-01
We propose an extrapolation method utilizing energy variance in the Monte Carlo shell model in order to estimate the energy eigenvalue and observables accurately. We derive a formula for the energy variance with deformed Slater determinants, which enables us to calculate the energy variance efficiently. The feasibility of the method is demonstrated for the full $pf$-shell calculation of $^{56}$Ni, and the applicability of the method to a system beyond current limit of exact ...
Novel Extrapolation Method in the Monte Carlo Shell Model
Shimizu, Noritaka; Utsuno, Yutaka; Mizusaki, Takahiro; Otsuka, Takaharu; Abe, Takashi; Honma, Michio
2010-01-01
We propose an extrapolation method utilizing energy variance in the Monte Carlo shell model in order to estimate the energy eigenvalue and observables accurately. We derive a formula for the energy variance with deformed Slater determinants, which enables us to calculate the energy variance efficiently. The feasibility of the method is demonstrated for the full $pf$-shell calculation of $^{56}$Ni, and the applicability of the method to a system beyond current limit of exact ...
Extrapolation Methods for the Dirac Inverter in Hybrid Monte Carlo
Brower, R. C.; Levi, A. R.; K. Orginos
1994-01-01
In Hybrid Monte Carlo(HMC) simulations for full QCD, the gauge fields evolve smoothly as a function of Molecular Dynamics (MD) time. Thus we investigate improved methods of estimating the trial solutions to the Dirac propagator as superpositions of the solutions in the recent past. So far our best extrapolation method reduces the number of Conjugate Gradient iterations per unit MD time by about a factor of 4. Further improvements should be forthcoming as we further exploit t...
Extrapolation methods for the Dirac inverter in hybrid Monte Carlo
International Nuclear Information System (INIS)
In Hybrid Monte Carlo (HMC) simulations for full QCD, the gauge fields evolve smoothly as a function of Molecular Dynamics (MD) time. Thus we investigate improved methods of estimating the trial solutions to the Dirac propagator as superpositions of the solutions in the recent past. So far our best extrapolation method reduces the number of Conjugate Gradient iterations per unit MD time by about a factor of 4. Further improvements should be forthcoming as we further exploit the information of past trajectories. ((orig.))
A Fitting Extrapolation Method for Calculation of ? Radioactive Ratio
International Nuclear Information System (INIS)
According to the overlap of 238Pu and 239Pu+240Pu in alpha spectrum,a fitting extrapolation method was introduced to analyze peak counts in the alpha energy spectrum for calculation of two-peak radioactivity. The method is based on the tailed trend of main peak in spectrum that the counts in the tailed channels decrease with the decrease of channel number. The total counts of main peak were obtained by fitting extrapolation according to the sum counts of main peak with the change of the tailed channels. This method is simple and applicable, and the results in more than 30 alpha energy spectra in our work are with accuracy. (authors)
A regularization method for extrapolation of solar potential magnetic fields
Gary, G. A.; Musielak, Z. E.
1992-01-01
The mathematical basis of a Tikhonov regularization method for extrapolating the chromospheric-coronal magnetic field using photospheric vector magnetograms is discussed. The basic techniques show that the Cauchy initial value problem can be formulated for potential magnetic fields. The potential field analysis considers a set of linear, elliptic partial differential equations. It is found that, by introducing an appropriate smoothing of the initial data of the Cauchy potential problem, an approximate Fourier integral solution is found, and an upper bound to the error in the solution is derived. This specific regularization technique, which is a function of magnetograph measurement sensitivities, provides a method to extrapolate the potential magnetic field above an active region into the chromosphere and low corona.
Extrapolation techniques applied to matrix methods in neutron diffusion problems
Mccready, Robert R
1956-01-01
A general matrix method is developed for the solution of characteristic-value problems of the type arising in many physical applications. The scheme employed is essentially that of Gauss and Seidel with appropriate modifications needed to make it applicable to characteristic-value problems. An iterative procedure produces a sequence of estimates to the answer; and extrapolation techniques, based upon previous behavior of iterants, are utilized in speeding convergence. Theoretically sound limits are placed on the magnitude of the extrapolation that may be tolerated. This matrix method is applied to the problem of finding criticality and neutron fluxes in a nuclear reactor with control rods. The two-dimensional finite-difference approximation to the two-group neutron fluxes in a nuclear reactor with control rods. The two-dimensional finite-difference approximation to the two-group neutron-diffusion equations is treated. Results for this example are indicated.
Novel extrapolation method in the Monte Carlo shell model
International Nuclear Information System (INIS)
We propose an extrapolation method utilizing energy variance in the Monte Carlo shell model to estimate the energy eigenvalue and observables accurately. We derive a formula for the energy variance with deformed Slater determinants, which enables us to calculate the energy variance efficiently. The feasibility of the method is demonstrated for the full pf-shell calculation of 56Ni, and the applicability of the method to a system beyond the current limit of exact diagonalization is shown for the pf+g9/2-shell calculation of 64Ge.
Novel Extrapolation Method in the Monte Carlo Shell Model
Shimizu, Noritaka; Mizusaki, Takahiro; Otsuka, Takaharu; Abe, Takashi; Honma, Michio
2010-01-01
We propose an extrapolation method utilizing energy variance in the Monte Carlo shell model in order to estimate the energy eigenvalue and observables accurately. We derive a formula for the energy variance with deformed Slater determinants, which enables us to calculate the energy variance efficiently. The feasibility of the method is demonstrated for the full $pf$-shell calculation of $^{56}$Ni, and the applicability of the method to a system beyond current limit of exact diagonalization is shown for the $pf$+$g_{9/2}$-shell calculation of $^{64}$Ge.
Precise estimation of shell model energy by second order extrapolation method
Mizusaki, Takahiro; Imada, Masatoshi
2003-01-01
A second order extrapolation method is presented for shell model calculations, where shell model energies of truncated spaces are well described as a function of energy variance by quadratic curves and exact shell model energies can be obtained by the extrapolation. This new extrapolation can give more precise energy than those of first order extrapolation method. It is also clarified that first order extrapolation gives a lower limit of shell model energy. In addition to th...
Efficient extrapolation methods for electro- and magnetoquasistatic field simulations
Directory of Open Access Journals (Sweden)
M. Clemens
2003-01-01
Full Text Available In magneto- and electroquasi-static time domain simulations with implicit time stepping schemes the iterative solvers applied to the large sparse (non-linear systems of equations are observed to converge faster if more accurate start solutions are available. Different extrapolation techniques for such new time step solutions are compared in combination with the preconditioned conjugate gradient algorithm. Simple extrapolation schemes based on Taylor series expansion are used as well as schemes derived especially for multi-stage implicit Runge-Kutta time stepping methods. With several initial guesses available, a new subspace projection extrapolation technique is proven to produce an optimal initial value vector. Numerical tests show the resulting improvements in terms of computational efficiency for several test problems. In quasistatischen elektromagnetischen Zeitbereichsimulationen mit impliziten Zeitschrittverfahren zeigt sich, dass die iterativen Lösungsverfahren für die großen dünnbesetzten (nicht-linearen Gleichungssysteme schneller konvergieren, wenn genauere Startlösungen vorgegeben werden. Verschiedene Extrapolationstechniken werden für jeweils neue Zeitschrittlösungen in Verbindung mit dem präkonditionierten Konjugierte Gradientenverfahren vorgestellt. Einfache Extrapolationsverfahren basierend auf Taylorreihenentwicklungen werden ebenso benutzt wie speziell für mehrstufige implizite Runge-Kutta-Verfahren entwickelte Verfahren. Sind verschiedene Startlösungen verfügbar, so erlaubt ein neues Unterraum-Projektion- Extrapolationsverfahren die Konstruktion eines optimalen neuen Startvektors. Numerische Tests zeigen die aus diesen Verfahren resultierenden Verbesserungen der numerischen Effizienz.
The solution of coupled Schroedinger equations using an extrapolation method
Goorvitch, D.; Galant, D. C.
1992-01-01
In this paper, extrapolation to the limit in a finite-difference method is applied to solve a system of coupled Schroedinger equations. This combination results in a method that only requires knowledge of the potential energy functions for the system. This numerical procedure has several distinct advantages over the more conventional methods. Namely, initial guesses for the term values are not needed; assumptions need be made about the behavior of the wavefunctions, such as the slope or magnitude in the nonclassical region; and the algorithm is easy to implement, has a firm mathematical foundation, and provides error estimates. Moreover, the method is less sensitive to round-off error than other methods since a small number of mesh points is used and it can be implemented on small computers. A comparison of the method with another numerical method shows results agreeing within 1 part in 10 exp 4.
Assessment of Load Extrapolation Methods for Wind Turbines
DEFF Research Database (Denmark)
Toft, Henrik Stensgaard; SØrensen, John Dalsgaard
2010-01-01
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 flap bending moment of a wind turbine 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 twelve mean wind speeds the ‘fitting before aggregation’ and ‘aggregation before fitting’ approaches are studied. The results show that the ‘fitting before aggregation’ approach gives the best results.
An Extrapolation Method for Estimating Truncation Errors in PSAs
International Nuclear Information System (INIS)
The quantification of a Probabilistic Safety Assessment (PSA) of a Nuclear Power Plant (NPP) is a complicated process and always has the Truncation Errors (TEs) in deleting low-probability cut sets. In practice it is extremely difficult to quantify PSA results without TEs. This paper proposes an approach to estimate the TEs in NPP PSAs which is based on the least square fitting and the extrapolation of risk increments. The proposed TE measure is reasonable and conservative. The proposed method can be helpful in demonstrating that the convergence of risk measures is sufficient
Comparison of methods for extrapolating breaking creep results
International Nuclear Information System (INIS)
Among all the methods of extrapolation, the following have been selected: - parametric methods (Larson-Miller, Dorn, Manson-Haferd); - digital and parametric method (minimum commitment); - digital method (finite differences); - descriptive method (Givar). The Larson-Miller, Dorn and Manson-Haferd methods are commonly used for analyzing the breaking creep results of materials for which the master curves can be described simply. The other methods have been developed in order to analyze the breaking creep results of materials where the structural changes over time modify the creep behaviour. In each case the assessment of the parameters is achieved by the least squares method. These methods were compared with each other on two steels, namely: Z6 CND 17-12 (316) and Z4 CND 35-20 (800 alloy). The various analyses performed show that (a) the predictions made as from the different methods are in good agreement between each other when there is a sufficient number of experimental values and (b) the predictions of the breaking times in the case of the 800 alloy differ from one method to the next. This result is due to the limited sampling data and to the complex behaviour of this alloy, the properties of which change with ageing
The extrapolated successive overrelaxation (ESOR method for consistently ordered matrices
Directory of Open Access Journals (Sweden)
D. J. Evans
1984-06-01
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, ÃŽÂ¼Ã‚Â¯ does not vanish, then ESOR attains faster rate of convergence than SOR when 1Ã¢ÂˆÂ’ÃŽÂ¼Ã‚Â¯2<(1Ã¢ÂˆÂ’ÃŽÂ¼Ã‚Â¯212, where ÃŽÂ¼Ã‚Â¯ denotes the spectral radius of B.
MMOC- MODIFIED METHOD OF CHARACTERISTICS SONIC BOOM EXTRAPOLATION
Darden, C. M.
1994-01-01
The Modified Method of Characteristics Sonic Boom Extrapolation program (MMOC) is a sonic boom propagation method which includes shock coalescence and incorporates the effects of asymmetry due to volume and lift. MMOC numerically integrates nonlinear equations from data at a finite distance from an airplane configuration at flight altitude to yield the sonic boom pressure signature at ground level. MMOC accounts for variations in entropy, enthalpy, and gravity for nonlinear effects near the aircraft, allowing extrapolation to begin nearer the body than in previous methods. This feature permits wind tunnel sonic boom models of up to three feet in length, enabling more detailed, realistic models than the previous six-inch sizes. It has been shown that elongated airplanes flying at high altitude and high Mach numbers can produce an acceptably low sonic boom. Shock coalescence in MMOC includes three-dimensional effects. The method is based on an axisymmetric solution with asymmetric effects determined by circumferential derivatives of the standard shock equations. Bow shocks and embedded shocks can be included in the near-field. The method of characteristics approach in MMOC allows large computational steps in the radial direction without loss of accuracy. MMOC is a propagation method rather than a predictive program. Thus input data (the flow field on a cylindrical surface at approximately one body length from the axis) must be supplied from calculations or experimental results. The MMOC package contains a uniform atmosphere pressure field program and interpolation routines for computing the required flow field data. Other user supplied input to MMOC includes Mach number, flow angles, and temperature. MMOC output tabulates locations of bow shocks and embedded shocks. When the calculations reach ground level, the overpressure and distance are printed, allowing the user to plot the pressure signature. MMOC is written in FORTRAN IV for batch execution and has been implemented on a CDC 170 series computer operating under NOS with a central memory requirement of approximately 223K of 60 bit words. This program was developed in 1983.
Efficient extrapolation methods for electro- and magnetoquasistatic field simulations
Clemens, M.; Wilke, M.; Weiland, T.
2003-01-01
In magneto- and electroquasi-static time domain simulations with implicit time stepping schemes the iterative solvers applied to the large sparse (non-)linear systems of equations are observed to converge faster if more accurate start solutions are available. Different extrapolation techniques for such new time step solutions are compared in combination with the preconditioned conjugate gradient algorithm. Simple extrapolation schemes based on Taylor series expansion are used as well as schem...
Efficient implementation of minimal polynomial and reduced rank extrapolation methods
Sidi, Avram
1990-01-01
The minimal polynomial extrapolation (MPE) and reduced rank extrapolation (RRE) are two effective techniques that have been used in accelerating the convergence of vector sequences, such as those that are obtained from iterative solution of linear and nonlinear systems of equation. Their definitions involve some linear least squares problems, and this causes difficulties in their numerical implementation. Timewise efficient and numerically stable implementations for MPE and RRE are developed. A computer program written in FORTRAN 77 is also appended and applied to some model problems.
Pan, Kejia; He, Dongdong; Hu, Hongling
2015-01-01
In this paper, we develop a new extrapolation cascadic multigrid (ECMG$_{jcg}$) method, which makes it possible to solve 3D elliptic boundary value problems on rectangular domains of over 100 million unknowns on a desktop computer in minutes. First, by combining Richardson extrapolation and tri-quadratic Serendipity interpolation techniques, we introduce a new extrapolation formula to provide a good initial guess for the iterative solution on the next finer grid, which is a ...
Extrapolation Method for System Reliability Assessment : A New Scheme
DEFF Research Database (Denmark)
Qin, Jianjun; Nishijima, Kazuyoshi
2012-01-01
The present paper presents a new scheme for probability integral solution for system reliability analysis, which takes basis in the approaches by Naess et al. (2009) and Bucher (2009). The idea is to evaluate the probability integral by extrapolation, based on a sequence of MC approximations of integrals with scaled domains. The performance of this class of approximation depends on the approach applied for the scaling and the functional form utilized for the extrapolation. A scheme for this task is derived here taking basis in the theory of asymptotic solutions to multinormal probability integrals. The scheme is extended so that it can be applied to cases where the asymptotic property may not be valid and/or the random variables are not normally distributed. The performance of the scheme is investigated by four principal series and parallel systems and some practical examples. The results indicate that the proposed scheme is efficient and adds to generality for this class of approximations for probability integrals.
An efficient wave extrapolation method for anisotropic media with tilt
Waheed, Umair bin
2015-03-23
Wavefield extrapolation operators for elliptically anisotropic media offer significant cost reduction compared with that for the transversely isotropic case, particularly when the axis of symmetry exhibits tilt (from the vertical). However, elliptical anisotropy does not provide accurate wavefield representation or imaging for transversely isotropic media. Therefore, we propose effective elliptically anisotropic models that correctly capture the kinematic behaviour of wavefields for transversely isotropic media. Specifically, we compute source-dependent effective velocities for the elliptic medium using kinematic high-frequency representation of the transversely isotropic wavefield. The effective model allows us to use cheaper elliptic wave extrapolation operators. Despite the fact that the effective models are obtained by matching kinematics using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including frequency dependency and caustics, if present, with reasonable accuracy. The methodology developed here offers a much better cost versus accuracy trade-off for wavefield computations in transversely isotropic media, particularly for media of low to moderate complexity. In addition, the wavefield solution is free from shear-wave artefacts as opposed to the conventional finite-difference-based transversely isotropic wave extrapolation scheme. We demonstrate these assertions through numerical tests on synthetic tilted transversely isotropic models.
Ezekiel Uba Nwose; Ross Stuart Richards
2011-01-01
Background: The first issue of this series proposed extrapolation chart with conventional reference range and suggested comparison of results with other methods. Aim: This work sets out to compare interpretative results from the extrapolation method with those from a digital viscometer method. Materials and Methods: Five cases in our archived clinical pathology database that were specifically tested for whole blood viscosity by the digital method, and had results for haematocrit and serum pro...
Definition of static magnetic characteristics of ferromagnetic specimens with extrapolation methods
International Nuclear Information System (INIS)
The problem of definition of static magnetic characteristics of ferromagnetic specimens on the basis of extrapolation treatment of the totality of dynamic characteristics recorded in low-frequency (1-25 Hz) magnetic fields is considered. The application of the extrapolation methods ensures a considerable increase in the productivity of control of the studied specimen magnetic properties
Tao, Lu
1995-01-01
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
Ismail, Amira; Gorgey, Annie
2015-10-01
Extrapolation involves taking a certain linear combination of the numerical solutions of a base method applied with different stepsizes to obtain greater accuracy. This linear combination is done so as to eliminate the leading error term. The technique of extrapolation in accelerating convergence has been successfully in numerical solution of ordinary differential equations. In this study, symmetric Runge-Kutta methods for solving linear and nonlinear stiff problem are considered. Symmetric methods admit asymptotic error expansion in even powers of the stepsize and are therefore of special interest because successive extrapolations can increase the order by two at time. Although extrapolation can give greater accuracy, due to the stepsize chosen, the numerical approximations are often destroy due to the accumulated round off errors. Therefore, it is important to control the rounding errors especially when applying extrapolation. One way to minimize round off errors is by applying compensated summation. In this paper, the numerical results are given for the symmetric Runge-Kutta methods Implicit Midpoint and Implicit Trapezoidal Rule applied with and without compensated summation. The result shows that symmetric methods with higher level extrapolation using compensated summation gives much smaller errors. On the other hand, symmetric methods without compensated summation when applied with extrapolation, the errors are affected badly by rounding errors.
Activity measurement of 60Co, 134Cs by using 4??-4?? sum efficiency extrapolation method
International Nuclear Information System (INIS)
A 4??-4?? detector configuration with a 4??(PC) flow proportional counter and a large size well-type 4?? NaI(Tl) crystal was described, and the theoretic function of sum efficiency extrapolation was established. The radioactivities of 60Co and 134Cs source were measured using this sum extrapolation method, 0.29% and 0.19% relative uncertainty obtained for each, and the result was compared with the value of coincidence efficiency extrapolation. The analysis indicates this method is fit for measuring the activity of complex decay nuclides. (authors)
Improvement of accuracy of efficiency extrapolation method in 4??-? coincidence counting
International Nuclear Information System (INIS)
A normalized efficiency function has been calculated (which includes the optimum upper limit of the fitting region, fitting order and ? gate setting) in order to determine the type B uncertainty introduced by extrapolating. The calculated results were applied in the efficiency extrapolation method. The type B uncertainty resulting from extrapolation can be eliminated including the components introduced by different ? gate settings and/or different fitting orders. This method has been applied to the efficiency trace technique, and the results are presented for 147Nd and 35S. The final uncertainties at the 99.7 confidence level were 0.1% and 0.5%, respectively. (orig.)
Directory of Open Access Journals (Sweden)
Ezekiel Uba Nwose
2011-07-01
Full Text Available Background: The first issue of this series proposed extrapolation chart with conventional reference range and suggested comparison of results with other methods. Aim: This work sets out to compare interpretative results from the extrapolation method with those from a digital viscometer method. Materials and Methods: Five cases in our archived clinical pathology database that were specifically tested for whole blood viscosity by the digital method, and had results for haematocrit and serum proteins were pooled. The values of haematocrit and serum proteins were used to derive extrapolated values. The interpretative results of the extrapolation method were compared with those of digital viscometer-based clinical reports. Non-Newtonian fluids such as whole blood have different viscosities at different shear rates. Comparative statement can only be based on interpreted outcome. Results: Two-fifth absolute concordance and one-fifth discordance is observed between extrapolation and viscometer-based clinical reports. The discordance is a case of hyperviscosity in the presence of neither hyperproteinaemia nor polycythemia. Conclusion: The extrapolation method may underestimate whole blood viscosity in some patients when compared with digital viscometer, which in turn may suggest hyperviscosity that cannot be explained by hyperproteinaemia or polycythemia concepts. The impact of oxidative stress is highlighted.
Extrapolation method in the Monte Carlo Shell Model and its applications
International Nuclear Information System (INIS)
We demonstrate how the energy-variance extrapolation method works using the sequence of the approximated wave functions obtained by the Monte Carlo Shell Model (MCSM), taking 56Ni with pf-shell as an example. The extrapolation method is shown to work well even in the case that the MCSM shows slow convergence, such as 72Ge with f5pg9-shell. The structure of 72Se is also studied including the discussion of the shape-coexistence phenomenon.
How useful are corpus-based methods for extrapolating psycholinguistic variables?
Mandera, Pawe?; Keuleers, Emmanuel; Brysbaert, Marc
2015-01-01
Subjective ratings for age of acquisition, concreteness, affective valence, and many other variables are an important element of psycholinguistic research. However, even for well-studied languages, ratings usually cover just a small part of the vocabulary. A possible solution involves using corpora to build a semantic similarity space and to apply machine learning techniques to extrapolate existing ratings to previously unrated words. We conduct a systematic comparison of two extrapolation techniques: k-nearest neighbours, and random forest, in combination with semantic spaces built using latent semantic analysis, topic model, a hyperspace analogue to language (HAL)-like model, and a skip-gram model. A variant of the k-nearest neighbours method used with skip-gram word vectors gives the most accurate predictions but the random forest method has an advantage of being able to easily incorporate additional predictors. We evaluate the usefulness of the methods by exploring how much of the human performance in a lexical decision task can be explained by extrapolated ratings for age of acquisition and how precisely we can assign words to discrete categories based on extrapolated ratings. We find that at least some of the extrapolation methods may introduce artefacts to the data and produce results that could lead to different conclusions that would be reached based on the human ratings. From a practical point of view, the usefulness of ratings extrapolated with the described methods may be limited. PMID:25695623
Mueller, David S.
2013-04-01
Selection of the appropriate extrapolation methods for computing the discharge in the unmeasured top and bottom parts of a moving-boat acoustic Doppler current profiler (ADCP) streamflow measurement is critical to the total discharge computation. The software tool, extrap, combines normalized velocity profiles from the entire cross section and multiple transects to determine a mean profile for the measurement. The use of an exponent derived from normalized data from the entire cross section is shown to be valid for application of the power velocity distribution law in the computation of the unmeasured discharge in a cross section. Selected statistics are combined with empirically derived criteria to automatically select the appropriate extrapolation methods. A graphical user interface (GUI) provides the user tools to visually evaluate the automatically selected extrapolation methods and manually change them, as necessary. The sensitivity of the total discharge to available extrapolation methods is presented in the GUI. Use of extrap by field hydrographers has demonstrated that extrap is a more accurate and efficient method of determining the appropriate extrapolation methods compared with tools currently (2012) provided in the ADCP manufacturers' software.
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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 Dedner et al. to effectively clean the numerical errors associated with ? · B . Second, the multigrid 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 Low and Lou 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 Magara. 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 S-shaped structure consisting of the sheared and twisted loops formed in the lower region can be captured well through our NLFFF extrapolation method. We further discuss how well these sheared and twisted fields are reconstructed by estimating the magnetic topology and twist quantitatively.
Extrapolation of sonic boom pressure signatures by the waveform parameter method
Thomas, C. L.
1972-01-01
The waveform parameter method of sonic boom extrapolation is derived and shown to be equivalent to the F-function method. A computer program based on the waveform parameter method is presented and discussed, with a sample case demonstrating program input and output.
A variable metric forward--backward method with extrapolation
Bonettini, Silvia; Porta, Federica; Ruggiero, Valeria
2015-01-01
Forward-backward methods are a very useful tool for the minimization of a functional given by the sum of a differentiable term and a nondifferentiable one and their investigation has experienced several efforts from many researchers in the last decade. In this paper we focus on the convex case and, inspired by recent approaches for accelerating first-order iterative schemes, we develop a scaled inertial forward-backward algorithm which is based on a metric changing at each i...
International Nuclear Information System (INIS)
Technique of critical current density measurement (Jc) of HTc bulk ceramic superconductor has been performed by using linear extrapolation with four-point probes method. The measurement of critical current density HTc bulk ceramic superconductor usually causes damage in contact resistance. In order to decrease this damage factor, we introduce extrapolation method. The extrapolating data show that the critical current density Jc for YBCO (123) and BSCCO (2212) at 77 K are 10,85(6) Amp.cm-2 and 14,46(6) Amp.cm-2, respectively. This technique is easier, simpler, and the use of the current flow is low, so it will not damage the contact resistance of the sample. We expect that the method can give a better solution for bulk superconductor application. Key words. : superconductor, critical temperature, and critical current density
A hybrid method without extrapolation step for solving variational inequality problems
Malitsky, Yu. V.; Semenov, V. V.
2015-01-01
In this paper, we introduce a new method for solving variational inequality problems with monotone and Lipschitz-continuous mapping in Hilbert space. The iterative process is based on two well-known projection method and the hybrid (or outer approximation) method. However we do not use an extrapolation step in the projection method. The absence of one projection in our method is explained by slightly different choice of sets in hybrid method. We prove a strong convergence of...
Choice of order and extrapolation method in Aarseth-type N-body algorithms
International Nuclear Information System (INIS)
The force-versus-time history of a typical particle in a 50-body King model is taken as input data, and its extrapolatability is measured. Extrapolatability means how far the force can be extrapolated, measured in units of a locally defined rate-of-change time scale, and still be within a specified fractional accuracy of the true values. Greater extrapolatability means larger step size, hence greater efficiency, in an Aarseth-type N-body code. Extrapolatability is found to depend systematically on the order of the extrapolation method, but it goes to a finite limit in the limit of large order. A formula for choosing the optimal (most efficient) order for any desired accuracy is given; higher orders than are presently in use are indicated. Neither rational function extrapolation nor a somewhat vector-regularized polynomial method is found to be systematically better than component-wise polynomial extrapolation, indicating that extrapolatability can be viewed as an intrinsic property of the underlying N-body forces, independent of the extrapolation method. 13 references
The Thematic-Extrapolation Method: Incorporating Career Patterns into Career Counseling.
Jepsen, David A.
1994-01-01
Focuses on Super's concept of career model, idea that one person's sequence of work positions constitutes whole and unique career. Describes Thematic-Extrapolation Method (TEM), method for predicting career patterns developed by Super in 1954 and summarizes TEM in 3 identifiable steps. Concludes that modified TEM remains promising, but largely…
The optimized expansion based low-rank method for wavefield extrapolation
Wu, Zedong
2014-03-01
Spectral methods are fast becoming an indispensable tool for wavefield extrapolation, especially in anisotropic media because it tends to be dispersion and artifact free as well as highly accurate when solving the wave equation. However, for inhomogeneous media, we face difficulties in dealing with the mixed space-wavenumber domain extrapolation operator efficiently. To solve this problem, we evaluated an optimized expansion method that can approximate this operator with a low-rank variable separation representation. The rank defines the number of inverse Fourier transforms for each time extrapolation step, and thus, the lower the rank, the faster the extrapolation. The method uses optimization instead of matrix decomposition to find the optimal wavenumbers and velocities needed to approximate the full operator with its explicit low-rank representation. As a result, we obtain lower rank representations compared with the standard low-rank method within reasonable accuracy and thus cheaper extrapolations. Additional bounds set on the range of propagated wavenumbers to adhere to the physical wave limits yield unconditionally stable extrapolations regardless of the time step. An application on the BP model provided superior results compared to those obtained using the decomposition approach. For transversely isotopic media, because we used the pure P-wave dispersion relation, we obtained solutions that were free of the shear wave artifacts, and the algorithm does not require that n > 0. In addition, the required rank for the optimization approach to obtain high accuracy in anisotropic media was lower than that obtained by the decomposition approach, and thus, it was more efficient. A reverse time migration result for the BP tilted transverse isotropy model using this method as a wave propagator demonstrated the ability of the algorithm.
A least square extrapolation method for improving solution accuracy of PDE computations
International Nuclear Information System (INIS)
Richardson extrapolation (RE) is based on a very simple and elegant mathematical idea that has been successful in several areas of numerical analysis such as quadrature or time integration of ODEs. In theory, RE can be used also on PDE approximations when the convergence order of a discrete solution is clearly known. But in practice, the order of a numerical method often depends on space location and is not accurately satisfied on different levels of grids used in the extrapolation formula. We propose in this paper a more robust and numerically efficient method based on the idea of finding automatically the order of a method as the solution of a least square minimization problem on the residual. We introduce a two-level and three-level least square extrapolation method that works on nonmatching embedded grid solutions via spline interpolation. Our least square extrapolation method is a post-processing of data produced by existing PDE codes, that is easy to implement and can be a better tool than RE for code verification. It can be also used to make a cascade of computation more numerically efficient. We can establish a consistent linear combination of coarser grid solutions to produce a better approximation of the PDE solution at a much lower cost than direct computation on a finer grid. To illustrate the performance of the method, examples including two-dimensional turning point problem with sharp transition layer and the Navier-Stokes flow inside a lid-driven cavity are adopted
New method for the extrapolation of finite-size data to infinite volume
International Nuclear Information System (INIS)
We present a simple and powerful method for extrapolating finite-volume Monte Carlo data to infinite volume based on finite-size-scaling theory. We discuss carefully its systematic and statistical errors, and we illustrate it using three examples: the two-dimensional three-state Potts antiferromagnet on the square lattice, and the two-dimensional O(3) and O(?) ?-models. In favorable cases it is possible to obtain reliable extrapolations (errors of a few percent) even when the correlation length is 1000 times larger than the lattice. ((orig.))
Nonlinear Force-Free Extrapolation of the Coronal Magnetic Field Based on the MHD Relaxation Method
Inoue, S; Pandey, V S; Shiota., D; Kusano, K; Choe, G S; Kim, K S
2013-01-01
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 ...
A comparison of preprocessing methods for solar force-free magnetic field extrapolation
Fuhrmann, M.; Seehafer, N.; Valori, G (Gherardo); T. Wiegelmann
2010-01-01
Extrapolations of solar photospheric vector magnetograms into three-dimensional magnetic fields in the chromosphere and corona are usually done under the assumption that the fields are force-free. The field calculations can be improved by preprocessing the photospheric magnetograms. We compare two preprocessing methods presently in use, namely the methods of Wiegelmann et al. (2006) and Fuhrmann et al. (2007). The two preprocessing methods were applied to a recently observed...
Nonlinear Force-Free Extrapolation of the Coronal Magnetic Field Based on the MHD Relaxation Method
Inoue, S.; Magara, T.; Pandey, V. S.; Shiota., D.; Kusano, K.; Choe, G. S.; Kim, K S
2013-01-01
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 ...
A Multi-Step Richardson-Romberg Extrapolation Method For Stochastic Approximation
Frikha, Noufel; Huang, Lorick
2014-01-01
We obtain an expansion of the implicit weak discretization error for the target of stochastic approximation algorithms introduced and studied in [Frikha2013]. This allows us to extend and develop the Richardson-Romberg extrapolation method for Monte Carlo linear estimator (introduced in [Talay & Tubaro 1990] and deeply studied in [Pag{\\`e}s 2007]) to the framework of stochastic optimization by means of stochastic approximation algorithm. We notably apply the method to the es...
International Nuclear Information System (INIS)
The parametric methods of Larsen-Miller, Sherby-Dorn, Menson-Sakkop, Konrad-and Korchinsky-Klauss are compared in terms of their advisability to be applied to description and extrapolation of long-term strength characteristics for alloy 21 on the base of refractory metals. It is shown that the most adequate description of longterm strength for the studied materials may be obtained by the Menson-Sakkop and Sherby-Dorn methods
The boundary integral equation method for the extrapolation of field measurement
Duthoit, F.; Krähenbühl, Laurent; Nicolas, Alain
1985-01-01
How to extrapolate measured filed values in respect to the physical equations ? The authors expose the concrete problem they had to solve and the solution they proposed, by using the Boundary Integral Equation Method (BIEM). First, fictitious sources are constructed giving exactly the measured values of the field; then we compute the field in other points as for the field of these fictitious sources. In association with l.s. techniques, this method permits also in part the correction of the m...
Senjean, Bruno; Alam, Md Mehboob; Knecht, Stefan; Fromager, Emmanuel
2015-01-01
The combination of a recently proposed linear interpolation method (LIM) [Senjean et al., Phys. Rev. A 92, 012518 (2015)], which enables the calculation of weight-independent excitation energies in range-separated ensemble density-functional approximations, with the extrapolation scheme of Savin [J. Chem. Phys. 140, 18A509 (2014)] is presented in this work. It is shown that LIM excitation energies vary quadratically with the inverse of the range-separation parameter mu when the latter is large. As a result, the extrapolation scheme, which is usually applied to long-range interacting energies, can be adapted straightforwardly to LIM. This extrapolated LIM (ELIM) has been tested on a small test set consisting of He, Be, H2 and HeH+. Relatively accurate results have been obtained for the first singlet excitation energies with the typical mu=0.4 value. The improvement of LIM after extrapolation is remarkable, in particular for the doubly-excited 2^1Sigma+g state in the stretched H2 molecule. Three-state ensemble ...
Jiang, Chaowei; Feng, Xueshang
2012-01-01
Magnetic field in the solar corona is usually extrapolated from photospheric vector magnetogram using a nonlinear force-free field (NLFFF) model. NLFFF extrapolation needs a considerable effort to be devoted for its numerical realization. In this paper we present a new implementation of the magnetohydrodynamics (MHD)-relaxation method for NLFFF extrapolation. The magneto-frictional approach which is introduced for speeding the relaxation of the MHD system is novelly realized...
New method of extrapolation of the resistance of a model planing boat to full size
Sottorf, W
1942-01-01
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.
Dynamics of Variable Valve Trains and Extrapolation Methods for Time-Stepping Schemes
Huber, Robert
2013-01-01
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...
G Wu; A.K Skidmore; Leeuw, J. de; Liu, X.; Prins, H.H.T.
2010-01-01
Measurements of photosynthetically active radiation (PAR), which are indispensable for simulating plant growth and productivity, are generally very scarce. This study aimed to compare two extrapolation and one interpolation methods for estimating daily PAR reaching the earth surface within the Poyang Lake national nature reserve, China. The daily global solar radiation records at Nanchang meteorological station and daily sunshine duration measurements at nine meteorological stations around Po...
Study on two Methods for Nonlinear Force-free Extrapolation Based on Semi-Analytical Field
S., Liu; Q., Zhang H.; T, Su J. T. Song M.
2014-01-01
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 i...
Wu, S. T.; Sun, M. T.; Sakurai, Takashi
1990-01-01
This paper presents a comparison between two numerical methods for the extrapolation of nonlinear force-free magnetic fields, viz the Iterative Method (IM) and the Progressive Extension Method (PEM). The advantages and disadvantages of these two methods are summarized, and the accuracy and numerical instability are discussed. On the basis of this investigation, it is claimed that the two methods do resemble each other qualitatively.
International Nuclear Information System (INIS)
The energy of a temporary anion can be computed by adding a stabilizing potential to the molecular Hamiltonian, increasing the stabilization until the temporary state is turned into a bound state, and then further increasing the stabilization until enough bound state energies have been collected so that these can be extrapolated back to vanishing stabilization. The lifetime can be obtained from the same data, but only if the extrapolation is done through analytic continuation of the momentum as a function of the square root of a shifted stabilizing parameter. This method is known as analytic continuation of the coupling constant, and it requires—at least in principle—that the bound-state input data are computed with a short-range stabilizing potential. In the context of molecules and ab initio packages, long-range Coulomb stabilizing potentials are, however, far more convenient and have been used in the past with some success, although the error introduced by the long-rang nature of the stabilizing potential remains unknown. Here, we introduce a soft-Voronoi box potential that can serve as a short-range stabilizing potential. The difference between a Coulomb and the new stabilization is analyzed in detail for a one-dimensional model system as well as for the 2?u resonance of CO2?, and in both cases, the extrapolation results are compared to independently computed resonance parameters, from complex scaling for the model, and from complex absorbing potential calculations for CO2?. It is important to emphasize that for both the model and for CO2?, all three sets of results have, respectively, been obtained with the same electronic structure method and basis set so that the theoretical description of the continuum can be directly compared. The new soft-Voronoi-box-based extrapolation is then used to study the influence of the size of diffuse and the valence basis sets on the computed resonance parameters
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We propose some new, efficient, and practical extrapolation methods to obtain a few low-lying eigenenergies of a large-dimensional Hamiltonian matrix in the nuclear shell model. We obtain those energies at the desired accuracy by extrapolation after diagonalizing small-dimensional submatrices of the sorted Hamiltonian matrix.
Evaluation of functioning of an extrapolation chamber using Monte Carlo method
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The extrapolation chamber is a parallel plate chamber and variable volume based on the Braff-Gray theory. It determines in absolute mode, with high accuracy the dose absorbed by the extrapolation of the ionization current measured for a null distance between the electrodes. This camera is used for dosimetry of external beta rays for radiation protection. This paper presents a simulation for evaluating the functioning of an extrapolation chamber type 23392 of PTW, using the MCNPX Monte Carlo method. In the simulation, the fluence in the air collector cavity of the chamber was obtained. The influence of the materials that compose the camera on its response against beta radiation beam was also analysed. A comparison of the contribution of primary and secondary radiation was performed. The energy deposition in the air collector cavity for different depths was calculated. The component with the higher energy deposition is the Polymethyl methacrylate block. The energy deposition in the air collector cavity for chamber depth 2500 ?m is greater with a value of 9.708E-07 MeV. The fluence in the air collector cavity decreases with depth. It's value is 1.758E-04 1/cm2 for chamber depth 500 ?m. The values reported are for individual electron and photon histories. The graphics of simulated parameters are presented in the paper. (Author)
Temperature-extrapolation method for Implicit Monte Carlo - Radiation hydrodynamics calculations
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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)
International Nuclear Information System (INIS)
During physical start-up of nuclear reactor, the curve got by lifting the con- trol rods to extrapolate to the critical state is often in protruding shape, by which the supercritical phenomena is led. In the paper, the reason why the curve was in protruding was analyzed. A correction method was introduced, and the calculations were carried out by the practical data used in a nuclear power plant. The results show that the correction method reverses the protruding shape of the extrapolating curve, and the risk of reactor supercritical phenomena can be reduced using the extrapolated curve got by the correction method during physical start-up of the reactor. (authors)
Ketcheson, David I.; Waheed, Umair bin
2013-01-01
We compare the three main types of high-order one-step initial value solvers: extrapolation, spectral deferred correction, and embedded Runge--Kutta pairs. We consider orders four through twelve, including both serial and parallel implementations. We cast extrapolation and deferred correction methods as fixed-order Runge--Kutta methods, providing a natural framework for the comparison. The stability and accuracy properties of the methods are analyzed by theoretical measures,...
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The angular multigrid (ANMG) acceleration method and the Lyusternik-Wagner extrapolation acceleration technique are applied to accelerate the neutron transport equation solver DNTR, which was developed by using SN nodal method in triangular-z meshes. Some numerical results demonstrate that the ANMG acceleration method applied to DNTR is effective, even in strong anisotropic scattering and high scattering ratio situations,especially combined with the Lyusternik-Wagner extrapolation acceleration technique. (authors)
Sun, Shuyu
2013-06-01
This paper introduces an efficient technique to generate new molecular simulation Markov chains for different temperature and density conditions, which allow for rapid extrapolation of canonical ensemble averages at a range of temperatures and densities different from the original conditions where a single simulation is conducted. Obtained information from the original simulation are reweighted and even reconstructed in order to extrapolate our knowledge to the new conditions. Our technique allows not only the extrapolation to a new temperature or density, but also the double extrapolation to both new temperature and density. The method was implemented for Lennard-Jones fluid with structureless particles in single-gas phase region. Extrapolation behaviors as functions of extrapolation ranges were studied. Limits of extrapolation ranges showed a remarkable capability especially along isochors where only reweighting is required. Various factors that could affect the limits of extrapolation ranges were investigated and compared. In particular, these limits were shown to be sensitive to the number of particles used and starting point where the simulation was originally conducted.
The Impacts of Atmospheric Stability on the Accuracy of Wind Speed Extrapolation Methods
Jennifer F. Newman; Petra M. Klein
2014-01-01
The building of utility-scale wind farms requires knowledge of the wind speed climatology at hub height (typically 80–100 m). As most wind speed measurements are taken at 10 m above ground level, efforts are being made to relate 10-m measurements to approximate hub-height wind speeds. One common extrapolation method is the power law, which uses a shear parameter to estimate the wind shear between a reference height and hub height. The shear parameter is dependent on atmospheric stability and ...
Sidi, Avram
1987-01-01
In a recent work by the author an extrapolation method, the W-transformation, was developed, by which a large class of oscillatory infinite integrals can be computed very efficiently. The results of this work are extended to a class of divergent oscillatory infinite integrals in the present paper. It is shown in particular that these divergent integrals exist in the sense of Abel summability and that the W-transformation can be applied to them without any modifications. Convergence results are stated and numerical examples given.
Counter-extrapolation method for conjugate interfaces in computational heat and mass transfer
Le, Guigao; Oulaid, Othmane; Zhang, Junfeng
2015-03-01
In this paper a conjugate interface method is developed by performing extrapolations along the normal direction. Compared to other existing conjugate models, our method has several technical advantages, including the simple and straightforward algorithm, accurate representation of the interface geometry, applicability to any interface-lattice relative orientation, and availability of the normal gradient. The model is validated by simulating the steady and unsteady convection-diffusion system with a flat interface and the steady diffusion system with a circular interface, and good agreement is observed when comparing the lattice Boltzmann results with respective analytical solutions. A more general system with unsteady convection-diffusion process and a curved interface, i.e., the cooling process of a hot cylinder in a cold flow, is also simulated as an example to illustrate the practical usefulness of our model, and the effects of the cylinder heat capacity and thermal diffusivity on the cooling process are examined. Results show that the cylinder with a larger heat capacity can release more heat energy into the fluid and the cylinder temperature cools down slower, while the enhanced heat conduction inside the cylinder can facilitate the cooling process of the system. Although these findings appear obvious from physical principles, the confirming results demonstrates the application potential of our method in more complex systems. In addition, the basic idea and algorithm of the counter-extrapolation procedure presented here can be readily extended to other lattice Boltzmann models and even other computational technologies for heat and mass transfer systems.
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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 down-link 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 2x2 multiple-input multiple-output system, with low deviations in comparison with signals measured using dedicated LTE decoders. (authors)
Pan, Kejia; He, Dongdong; Hu, Hongling
2015-01-01
In this paper, we develop a new extrapolation cascadic multigrid (ECMG) method to solve the 3D Poisson equation using the compact finite difference (FD) method. First, a 19-point fourth-order compact difference scheme with unequal meshsizes in different coordinate directions is employed to discretize the 3D Poisson equation on rectangular domains. By combining the Richardson extrapolation and tri-quartic Lagrange interpolation, we are able to obtain a quite good initial gues...
Dantas, Christine C.; Rezende, Mirabel. C.; Simone de S. Pinto
2014-01-01
We describe a method of extrapolation based on a "truncated" Kramers-Kronig relation for the complex permittivity ($\\epsilon$) and permeability ($\\mu$) parameters of a material, based on finite frequency data. Considering a few assumptions, such as the behavior of the loss tangent and the overall nature of corrections, the method is robust within a small relative error, if the assumed hypotheses hold at the extrapolated frequency range.
A two-grid method with Richardson extrapolation for a semilinear convection-diffusion problem
Tikhovskaya, S. V.; Zadorin, A. I.
2015-10-01
A boundary value problem for a second-order semilinear singularly perturbed ordinary differential equation is considered. We use Newton and Picard iterations for a linearization. To solve the problem at each iteration we apply the difference scheme with the property of uniform with respect to the singular perturbation parameter convergence. A modified Samarskii and central difference schemes on Shishkin mesh are considered. It is known that these schemes are almost second order accuracy uniformly with respect to the singular perturbation parameter. To decrease the required number of arithmetical operations for resolving the difference scheme, a two-grid method is proposed. To increase the accuracy of difference scheme, we investigate the possibility to apply Richardson extrapolation using known solutions of the difference scheme on both meshes. The comparison of modified Samarskii and central difference schemes is carried out. The results of some numerical experiments are discussed.
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To improve the efficiency of neutron transport computation, the angular multigrid (ANMG) acceleration method and the Lyusternik-Wagner extrapolation acceleration technique are utilized to accelerate the source iteration process. They are successfully applied to the LESFES code, which is developed to solve the neutron transport equation by the least-squares finite-element method. The numerical results demonstrate that the ANMG acceleration method can save much computation time not only for isotropic scattering problems but also for the highly anisotropic scattering problems. Furthermore, when the Lyusternik-Wagner extrapolation acceleration technique is applied to the ANMG acceleration method, the acceleration effect can be significantly improved. (authors)
First principles Tafel kinetics of methanol oxidation on Pt(111)
Fang, Ya-Hui; Liu, Zhi-Pan
2015-01-01
Electrocatalytic methanol oxidation is of fundamental importance in electrochemistry and also a key reaction in direct methanol fuel cell. To resolve the kinetics at the atomic level, this work investigates the potential-dependent reaction kinetics of methanol oxidation on Pt(111) using the first principles periodic continuum solvation model based on modified-Poisson-Boltzmann equation (CM-MPB), focusing on the initial dehydrogenation elementary steps. A theoretical model to predict Tafel kinetics (current vs potential) is established by considering that the rate-determining step of methanol oxidation (to CO) is the first Csbnd H bond breaking (CH3OH(aq) ? CH2OH* + H*) according to the computed free energy profile. The first Csbnd H bond breaking reaction needs to overcome a large entropy loss during methanol approaching to the surface and replacing the adsorbed water molecules. While no apparent charge transfer is involved in this elementary step, the charge transfer coefficient of the reaction is calculated to be 0.36, an unconventional value for charge transfer reactions, and the Tafel slope is deduced to be 166 mV. The results show that the metal/adsorbate interaction and the solvation environment play important roles on influencing the Tafel kinetics. The knowledge learned from the potential-dependent kinetics of methanol oxidation can be applied in general for understanding the electrocatalytic reactions of organic molecules at the solid-liquid interface.
Ketcheson, David I.
2014-04-11
In practical computation with Runge--Kutta methods, the stage equations are not satisfied exactly, due to roundoff errors, algebraic solver errors, and so forth. We show by example that propagation of such errors within a single step can have catastrophic effects for otherwise practical and well-known methods. We perform a general analysis of internal error propagation, emphasizing that it depends significantly on how the method is implemented. We show that for a fixed method, essentially any set of internal stability polynomials can be obtained by modifying the implementation details. We provide bounds on the internal error amplification constants for some classes of methods with many stages, including strong stability preserving methods and extrapolation methods. These results are used to prove error bounds in the presence of roundoff or other internal errors.
Manson, S. S.; Ensign, C. R.
1979-01-01
Developments in the analysis of creep-rupture data are reviewed with particular reference to time temperature relations for the correlation and extrapolation of creep and stress rupture data, the minimum commitment method, and successive regression methods. Some contributions to the development of time-temperature parameters are noted.
Justin Steven Prentice
2011-01-01
Stepwise local error control using local extrapolation in Runge-Kutta methods is well-known. In this paper, we introduce an algorithm, designated RK$rv$Q$z,$ that is capable of controlling local and global errors in a stepwise manner. The algorithm utilizes three Runge-Kutta methods, of orders $r,v$ and $z$, with $r
New extrapolation method for low-lying states of nuclei in the sd and the pf shells
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We study extrapolation approaches to evaluate energies of low-lying states for nuclei in the sd and pf shells, by sorting the diagonal matrix elements of the nuclear shell-model Hamiltonian. We introduce an extrapolation method with perturbation and apply our new method to predict both low-lying state energies and E2 transition rates between low-lying states. Our predicted results arrive at an accuracy of the root-mean-squared deviations ?40-60 keV for low-lying states of these nuclei.
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The magnetic field in the solar corona is usually extrapolated from a photospheric vector magnetogram using a nonlinear force-free field (NLFFF) model. NLFFF extrapolation needs considerable effort to be devoted to its numerical realization. In this paper, we present a new implementation of the magnetohydrodynamics (MHD) relaxation method for NLFFF extrapolation. The magnetofrictional approach, which is introduced for speeding the relaxation of the MHD system, is realized for the first time by the spacetime conservation-element and solution-element scheme. A magnetic field splitting method is used to further improve the computational accuracy. The bottom boundary condition is prescribed by incrementally changing the transverse field to match the magnetogram, and all other artificial boundaries of the computational box are simply fixed. We examine the code using two types of NLFFF benchmark tests, the Low and Lou semi-analytic force-free solutions and a more realistic solar-like case constructed by van Ballegooijen et al. The results show that our implementation is successful and versatile for extrapolations of either the relatively simple cases or the rather complex cases that need significant rebuilding of the magnetic topology, e.g., a flux rope. We also compute a suite of metrics to quantitatively analyze the results and demonstrate that the performance of our code in extrapolation accuracy basically reaches the same level of the present best-performing code, i.e., that developed by Wiegelmann.
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This study uses ultrasound in combination with tomography to obtain three-dimensional temperature measurements using projection data obtained from limited projection angle. The main feature of the new computerized tomography (CT) reconstruction algorithm is to employ extrapolation scheme to make up for the incomplete projection data, it is based on the conventional filtered back projection (FBP) method while on top of that taking into account the correlation between the projection data and Fourier transform-based extrapolation. Computer simulation is conducted to verify the above algorithm. An experimental 3D temperature distribution measurement is also carried out to validate the proposed algorithm. The simulation and experimental results demonstrate that the extrapolated FBP CT algorithm is highly effective in dealing with projection data from limited projection angle
Mueller, David S.
2013-01-01
Selection of the appropriate extrapolation methods for computing the discharge in the unmeasured top and bottom parts of a moving-boat acoustic Doppler current pro?ler (ADCP) stream?ow measurement is critical to the total discharge computation. The software tool, extrap, combines normalized velocity
Mizusaki, Takahiro; Shimizu, Noritaka
2012-01-01
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 energ...
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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.
Comparison of precipitation nowcasting by extrapolation and statistical-advection methods.
Czech Academy of Sciences Publication Activity Database
Sokol, Zbyn?k; Kitzmiller, D.; Pešice, Petr; Mejsnar, Jan
2013-01-01
Ro?. 123, 1 April (2013), s. 17-30. ISSN 0169-8095 R&D Projects: GA MŠk ME09033 Institutional support: RVO:68378289 Keywords : Precipitation forecast * Statistical models * Regression * Quantitative precipitation forecast * Extrapolation forecast Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 2.421, year: 2013 http://www.sciencedirect.com/science/article/pii/S0169809512003390
Extrapolation of Stationary Random Fields
Spodarev, Evgeny; Shmileva, Elena; Roth, Stefan
2013-01-01
We introduce basic statistical methods for the extrapolation of stationary random fields. For square integrable fields, we set out basics of the kriging extrapolation techniques. For (non--Gaussian) stable fields, which are known to be heavy tailed, we describe further extrapolation methods and discuss their properties. Two of them can be seen as direct generalizations of kriging.
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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)
Comparison of extrapolation methods for creep rupture stresses of 12Cr and 18Cr10NiTi steels
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As a part of a Soviet-Swedish research programme the creep rupture properties of two heat resisting steels namely a 12% Cr steel and an 18% Cr12% Ni titanium stabilized steel have been studied. One heat from each country of both steels were creep tested. The strength of the 12% Cr steels was similar to earlier reported strength values, the Soviet steel being some-what stronger due to a higher tungsten content. The strength of the Swedish 18/12 Ti steel agreed with earlier results, while the properties of the Soviet steel were inferior to those reported from earlier Soviet creep testings. Three extrapolation methods were compared on creep rupture data collected in both countries. Isothermal extrapolation and an algebraic method of Soviet origin gave in many cases rather similar results, while the parameter method recommended by ISO resulted in higher rupture strength values at longer times. (author)
Ketcheson, David I.
2014-06-13
We compare the three main types of high-order one-step initial value solvers: extrapolation, spectral deferred correction, and embedded Runge–Kutta pairs. We consider orders four through twelve, including both serial and parallel implementations. We cast extrapolation and deferred correction methods as fixed-order Runge–Kutta methods, providing a natural framework for the comparison. The stability and accuracy properties of the methods are analyzed by theoretical measures, and these are compared with the results of numerical tests. In serial, the eighth-order pair of Prince and Dormand (DOP8) is most efficient. But other high-order methods can be more efficient than DOP8 when implemented in parallel. This is demonstrated by comparing a parallelized version of the wellknown ODEX code with the (serial) DOP853 code. For an N-body problem with N = 400, the experimental extrapolation code is as fast as the tuned Runge–Kutta pair at loose tolerances, and is up to two times as fast at tight tolerances.
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
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The activity concentration of 125I was determined by X-(X-?) coincidence counting method and efficiency extrapolation curve. The measurement system consists of 2 thin NaI(T1) scintillation detectors which are horizontally movable on a track. The efficiency curve is obtained by symmetricaly changing the distance between the source and the detectors and the activity is determined by applying a linear efficiency extrapolation curve. All sum-coincidence events are included between 10 and 100 KeV window counting and the main source of uncertainty is coming from poor counting statistic around zero efficiency. The consistence of results with other methods shows that this technique can be applied to photon cascade emitters and are not discriminating by the detectors. It has been also determined the 35,5 KeV gamma-ray emission probability of 125I by using a Gamma-X type high purity germanium detector. (author)
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The potential energy curve (PEC) for the ground state of CO(X1?+) has been investigated by the highly accurate valence internally contracted multi-reference configuration interaction with the Davidson correction (MRCI+Q) method in combination with a series of correlation-consistent basis sets of Dunning and co-workers. The scheme proposed by Varandas, which enables high-quality molecular potentials to be obtained from small basis set calculations via scaling and extrapolation of the electron correlation to the complete basis set limit plus extrapolation to the complete basis set limit of the complete-active-space self-consistent field energy, has been applied to the system under consideration here. The present results are compared with the other theoretical and experimental data, and show that the present methods are credible and accurate.
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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.)
Measurement of the surface field on open magnetic samples by the extrapolation method.
Czech Academy of Sciences Publication Activity Database
Perevertov, Oleksiy
2005-01-01
Ro?. 76, - (2005), 104701/1-104701/7. ISSN 0034-6748 R&D Projects: GA ?R(CZ) GP202/04/P010; GA AV ?R(CZ) 1QS100100508 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnetic field measurement * extrapolation * air gaps * magnetic permeability Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.235, year: 2005
Czech Academy of Sciences Publication Activity Database
Mejsnar, Jan; Sokol, Zbyn?k; Pešice, Petr
Toulouse : Météo France, 2012. [ERAD 2012 - European Conference on Radar in Meteorology and Hydrology /7./. Toulouse (FR), 24.06.2012-29.06.2012] R&D Projects: GA MŠk ME09033 Institutional support: RVO:68378289 Keywords : precipitation nowcasting * Lagrangien extrapolation * uncertainty in precipitation Subject RIV: DG - Athmosphere Sciences, Meteorology http://www.meteo.fr/cic/meetings/2012/ERAD/extended_abs/NOW_250_ext_abs.pdf
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
Xie, Hehu
2006-01-01
In this paper, we derive an asymptotic error expansion for the eigenvalue approximations by the lowest order Raviart-Thomas mixed finite element method for the general second order elliptic eigenvalue problems. Extrapolation based on such an expansion is applied to improve the accuracy of the eigenvalue approximations. Furthermore, we also prove the superclose property between the finite element projection with the finite element approximation of the eigenvalue problems by m...
Louka, M. A.; Missirlis, N. M.
2015-01-01
In this paper we study the impact of two types of preconditioning on the numerical solution of large sparse augmented linear systems. The first preconditioning matrix is the lower triangular part whereas the second is the product of the lower triangular part with the upper triangular part of the augmented system's coefficient matrix. For the first preconditioning matrix we form the Generalized Modified Extrapolated Successive Overrelaxation (GMESOR) method, whereas the secon...
Waheed, Umair bin
2014-08-01
The wavefield extrapolation operator for ellipsoidally anisotropic (EA) media offers significant cost reduction compared to that for the orthorhombic case, especially when the symmetry planes are tilted and/or rotated. However, ellipsoidal anisotropy does not provide accurate focusing for media of orthorhombic anisotropy. Therefore, we develop effective EA models that correctly capture the kinematic behavior of the wavefield for tilted orthorhombic (TOR) media. Specifically, we compute effective source-dependent velocities for the EA model using kinematic high-frequency representation of the TOR wavefield. The effective model allows us to use the cheaper EA wavefield extrapolation operator to obtain approximate wavefield solutions for a TOR model. Despite the fact that the effective EA models are obtained by kinematic matching using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including the frequency dependency and caustics, if present, with reasonable accuracy. The methodology developed here offers a much better cost versus accuracy tradeoff for wavefield computations in TOR media, particularly for media of low to moderate complexity. We demonstrate applicability of the proposed approach on a layered TOR model.
International Nuclear Information System (INIS)
We present a new method for the calculation of above-threshold ionization (ATI) cross sections based on a description of the atomic structure through a discretized basis. This new approach handles the divergent terms within the discretized continuum by assigning a width ? to the nearest discretized continuum level and then extrapolating to the value of the amplitude as ? goes to zero. The method is in principle applicable to any discretized basis and to atoms with more than one electron. We demonstrate its usefulness through the calculation of up to four photons absorbed above threshold in helium. (author)
Evaluation of external quality factor of the superconducting cavity using extrapolation method
International Nuclear Information System (INIS)
The estimation of the external quality factor is important for designing coupling devices for the cavities. A new representation of the external quality factor calculations for single-cell cavity coupled to a coaxial transmission line is derived based on analytic analysis and numeric analysis with the help of 3D electromagnetic code, and verified with experimental measurements at room temperature. In logarithmic scale the results for the external quality factor were quasi-linear over the limited range, and the simulated and measured data could be used and extrapolated to the superconducting case. For the unpolished 1.5 GHz 3rd harmonic superconducting cavity, the discrepancy between the evaluation value and measurement result is less than 25% within an acceptable deviation. (authors)
International Nuclear Information System (INIS)
Starting from a method of series analysis, usually adopted in statistical mechanics, and from some results of potential theory, an approximation procedure for the calculation of the high-energy two-body elastic-scattering amplitude is proposed. The input is the perturbative expansion of the relevant S-matrix element in powers of a renormalized coupling constant. The method reproduces the lower perturbative terms and gives an extrapolation of the higher ones, which is appropriate in the high-energy region. In the framework of the phi4 model, the total cross-section, the ratio of the real to the imaginary part of the elastic two-body scattering amplitude and the elastic differential cross-section are calculated. The results show some general features of the two-body high-energy hadronic collisions. (author)
DEFF Research Database (Denmark)
Robbe, Joost Roger
2015-01-01
This article investigates the relationship between Dirc van Delft’s Tafel vanden kersten ghelove (1404) and earlier traditional medieval literature on death and dying. Two chapters in the Tafel contain a treatise on death: Somerstuc XXXVIII and XLVIII. Their sources include not only Anselm of Canterbury’s Admonitio morientis (c. 1100) and Henry Suso’s Horologium aeternae sapientiae (1331-34), but also the popular 14th-century Verses of Saint Bernard. The article demonstrates that the treatises a...
Manson, S. S.; Ensign, C. R.
1978-01-01
An outline is presented of a new procedure, termed the oblique translation method, which emerged in the development of the focal point convergence method. Approaches for implementing the oblique translation method are discussed. It is shown that the new method is essentially a minimum commitment method when manually-graphically implemented, in the sense that the form of the functions involved are not forced into particular analytical forms. The individual constants and functions are independently determined. The minimum commitment concept is extended to the analysis of creep rupture data wherein each isothermal is to be generated by an oblique translation of the 'master curve' when plotted. Attention is given to a manual-graphical analysis, the preassessment of data, and an analysis by computer code.
International Nuclear Information System (INIS)
We undertake an attempt to reconstruct the Sun's non-force-free magnetic field. The solar corona is often considered to be magnetohydrostatic. We solve the full MHD equations with a semi-realistic atmosphere model to attain this stationary state. Our method is tested with a Sun-like model which simulates the emergence of a magnetic flux rope passing from below the photosphere into the corona. Detailed diagnostics shows that our method can model the forced field more successfully than the optimization and potential method, but it still needs to be applied to real data.
Sidi, Avram; Shapira, Yair
1992-01-01
The application of the minimal polynomial extrapolation (MPE) and the reduced rank extrapolation (RRE) to a vector sequence obtained by the linear iterative technique x(sub j) + 1 = Ax(sub j) = b,j = 1,2,..., is considered. Both methods produce a two dimensional array of approximations s(sub n,k) to the solution of the system (I - A)x = b. Here, s(sub n,k) is obtained from the vectors x(sub j), n is less than or equal to j is less than or equal to n + k + 1. It was observed in an earlier publication by the first author that the sequence s(sub n,k), k = 1,2,..., for n greater than 0, but fixed, possesses better convergence properties than the sequence s(sub 0,k), k = 1,2,.... A detailed theoretical explanation for this phenomenon is provided in the present work. This explanation is heavily based on approximations by incomplete polynomials. It is demonstrated by numerical examples when the matrix A is sparse that cycling with s(sub n,k) for n greater than 0, but fixed, produces better convergence rates and costs less computationally than cycling with s(sub 0,k). It is also illustrated numerically with a convection-diffusion problem that the former may produce excellent results where the latter may fail completely. As has been shown in an earlier publication, the results produced by s(sub 0,k) are identical to the corresponding results obtained by applying the Arnoldi method or generalized minimal residual scheme (GMRES) to the system (I - A)x = b.
On an accelerated procedure of extrapolation
A. Yeyios
1981-01-01
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.
Manson, S. S.; Ensign, C. R.
1978-01-01
An outline is presented of approaches for treating multiheats on the basis of the focal point convergence method. The method has been employed in the case of two highly characterized multiheats, including a 304 stainless steel studied in Japan and a low alloy carbon steel studied in England. The method makes use of the same functional form for all materials. Only the constants are varied for each multiheat. Completely computerized procedures are employed for the determination of the constants. Once the basic analysis has been performed, the representation of various members in the same system is achieved by adding linear expressions of log stress, changing only two constants in the equations to represent a selected heat.
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)
Goldhirsh, J.
1982-01-01
The first absolute rain fade distribution method described establishes absolute fade statistics at a given site by means of a sampled radar data base. The second method extrapolates absolute fade statistics from one location to another, given simultaneously measured fade and rain rate statistics at the former. Both methods employ similar conditional fade statistic concepts and long term rain rate distributions. Probability deviations in the 2-19% range, with an 11% average, were obtained upon comparison of measured and predicted levels at given attenuations. The extrapolation of fade distributions to other locations at 28 GHz showed very good agreement with measured data at three sites located in the continental temperate region.
SVD-MPE: An SVD-Based Vector Extrapolation Method of Polynomial Type
Sidi, Avram
2015-01-01
An important problem that arises in different areas of science and engineering is that of computing the limits of sequences of vectors $\\{\\xx_m\\}$, where $\\xx_m\\in \\C^N$, $N$ being very large. Such sequences arise, for example, in the solution of systems of linear or nonlinear equations by fixed-point iterative methods, and $\\lim_{m\\to\\infty}\\xx_m$ are simply the required solutions. In most cases of interest, however, these sequences converge to their limits extremely slowly...
Ducasse, Q; Mathieu, L; Marini, P; Morillon, B; Aiche, M; Tsekhanovich, I
2015-01-01
The study of transfer-induced gamma-decay probabilities is very useful for understanding the surrogate-reaction method and, more generally, for constraining statistical-model calculations. One of the main difficulties in the measurement of gamma-decay probabilities is the determination of the gamma-cascade detection efficiency. In [Nucl. Instrum. Meth. A 700, 59 (2013)] we developed the Extrapolated Efficiency Method (EXEM), a new method to measure this quantity. In this work, we have applied, for the first time, the EXEM to infer the gamma-cascade detection efficiency in the actinide region. In particular, we have considered the 238U(d,p)239U and 238U(3He,d)239Np reactions. We have performed Hauser-Feshbach calculations to interpret our results and to verify the hypothesis on which the EXEM is based. The determination of fission and gamma-decay probabilities of 239Np below the neutron separation energy allowed us to validate the EXEM.
International Nuclear Information System (INIS)
Corrosion is one of the major problems in petroleum mining and processing industry. The pipelines used to transport crude oil from reservoir to the processing installation were made from carbon steel that is susceptible towards corrosion. One of the best methods to prevent corrosion that occurred at the inner parts of carbon steel pipelines is to use organic corrosion inhibitor. One of the potent organic corrosion inhibitors is amino acids derivatives. In this study, dipeptide compound namely benzoylalanylglycine methyl ester and benzoylalanylglycine have been synthesized. The structure elucidation of the products was performed by IR, MS and NMR spectroscopy. The determination of corrosion inhibition activity utilized the Tafel method. The corrosion inhibition efficiency of glycine methyl ester, benzoyl alanine, dipeptide benzoylalanylglycine methyl ester and dipeptide benzoylalanylglycine were 63.34 %, 35.86 %, 68.40 % and 27.72 %, respectively. These results showed that the formation of dipeptide benzoylalanylglycine methyl ester, derived from carboxylic protected glycine and amine protected alanine, increased the corrosion inhibition activity due to the loss of acidity center in the structure of glycine and L-alanine that would induce the corrosive environment towards carbon steel. (author)
Shinagawa, Tatsuya
2015-09-08
Microkinetic analyses of aqueous electrochemistry involving gaseous H2 or O2, i.e., hydrogen evolution reaction (HER), hydrogen oxidation reaction (HOR), oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), are revisited. The Tafel slopes used to evaluate the rate determining steps generally assume extreme coverage of the adsorbed species (????0 or??1), although, in practice, the slopes are coverage-dependent. We conducted detailed kinetic analyses describing the coverage-dependent Tafel slopes for the aforementioned reactions. Our careful analyses provide a general benchmark for experimentally observed Tafel slopes that can be assigned to specific rate determining steps. The Tafel analysis is a powerful tool for discussing the rate determining steps involved in electrocatalysis, but our study also demonstrated that overly simplified assumptions led to an inaccurate description of the surface electrocatalysis. Additionally, in many studies, Tafel analyses have been performed in conjunction with the Butler-Volmer equation, where its applicability regarding only electron transfer kinetics is often overlooked. Based on the derived kinetic description of the HER/HOR as an example, the limitation of Butler-Volmer expression in electrocatalysis is also discussed in this report.
Accelerating Distributed Consensus Using Extrapolation
Kokiopoulou, Effrosyni; Frossard, Pascal
2007-01-01
In the past few years, the problem of distributed consensus has received a lot of attention, particularly in the framework of ad hoc sensor networks. Most methods proposed in the literature attack this problem by distributed linear iterative algorithms, with asymptotic convergence of the consensus solution. In this paper, we propose the use of extrapolation methods in order to accelerate distributed linear iterations. The extrapolation methods are guaranteed to converge in a finite numb...
International Nuclear Information System (INIS)
Model error is one of the key factors restricting the accuracy of numerical weather prediction (NWP). Considering the continuous evolution of the atmosphere, the observed data (ignoring the measurement error) can be viewed as a series of solutions of an accurate model governing the actual atmosphere. Model error is represented as an unknown term in the accurate model, thus NWP can be considered as an inverse problem to uncover the unknown error term. The inverse problem models can absorb long periods of observed data to generate model error correction procedures. They thus resolve the deficiency and faultiness of the NWP schemes employing only the initial-time data. In this study we construct two inverse problem models to estimate and extrapolate the time-varying and spatial-varying model errors in both the historical and forecast periods by using recent observations and analogue phenomena of the atmosphere. Numerical experiment on Burgers' equation has illustrated the substantial forecast improvement using inverse problem algorithms. The proposed inverse problem methods of suppressing NWP errors will be useful in future high accuracy applications of NWP. (geophysics, astronomy, and astrophysics)
DEFF Research Database (Denmark)
Kofoed, Peter; Nielsen, Peter V.
1990-01-01
The design of a displacement ventilation system involves determination of the flow rate in the thermal plumes. The flow rate in the plumes and the vertical temperature gradient influence each other, and they are influenced by many factors. This paper shows some descriptions of these effects. Free turbulent plumes from different heated bodies are investigated. The measurements have taken place in a full-scale test room where the vertical temperature gradient have been changed. The velocity and the temperature distribution in the plume are measured. Large scale plume axis wandering is taken into account and the temperature excess and the velocity distribution are calculated by use of an extrapolation method. In the case with a concentrated heat source (dia 50mm, 343W) and nearly uniform surroundings the model of a plume above a point heat source is verified. It represents a borderline case with the smallest entrainment factor and the smallest angle of spread. Due to the measuring method and data processing the velocity and temperature excess profiles are observed more narrowly than those reported by previous authors. In the case with an extensive heat source (dia 400mm, lOOW) the model of a plume above a point heat source cannot be used. This is caused either by the way of generating the plume including a long intermediate region or by the environmental conditions where vertical temperature gradients are present. The flow has a larger angle of spread and the entrainment factor is greather than for a point heat source. The exact knowledge of the vertical temperature gradient is essential to predict the flow propagation due to its influence on the entrainment, e.g. in an integral method of plume calculation • Since the flow from different heated bodies is individual full-scale measurements seem to be the only possible approach to obtain the volume flow in: thermal plumes in ventilated rooms.
The approaches described in this paper will substantially improve risk assessments for compounds that undergo biotransformation. The purpose of this report is to review methods used by mammalian researchers to perform in vitro-in vivo metabolism extrapolations, discuss how these ...
Alves, Valéria A.; Paquim, Ana M. Chiorcea; Cavaleiro, Albano; Christopher M. A. Brett
2005-01-01
The influence of chemical composition and heat treatment on a low-carbon steel, chromium steel and high speed steel has been examined by polarisation curves and electrochemical parameters deduced from the Tafel plots. The electrochemical corrosion resistance, which is small between the as-received steels become greater after heat treatment, following the order: carbon steelÂ
Ketcheson, David I.; Lóczi, Lajos; Parsani, Matteo
2013-01-01
In practical computation with Runge--Kutta methods, the stage equations are not satisfied exactly, due to roundoff errors, algebraic solver errors, and so forth. We show by example that propagation of such errors within a single step can have catastrophic effects for otherwise practical and well-known methods. We perform a general analysis of internal error propagation, emphasizing that it depends significantly on how the method is implemented. We show that for a fixed metho...
International Nuclear Information System (INIS)
Graphite materials are used as core components in the High-Temperature Gas-Cooled Reactor (HTGR) and Very High Temperature Reactor (VHTR). The authors prepared technical documents for design, material, products, in-service inspection and maintenance of the graphite components for the HTGR/VHTR, which were summarized as a draft of standard for the graphite components through discussion made in a 'Special committee on research on preparation for codes for graphite components in HTGR' set up within AESJ. The draft of standard contains graphical expressions for the irradiated material properties of IG-110 graphite. It is possible to use the graphical expressions for the components design of VHTR. The graphs were obtained based on the interpolation and extrapolation of the irradiation data. The irradiation-induced dimensional change of IG-110 graphite was obtained through the interpolation and extrapolation of the irradiation data with a quadratic equation of fast neutron fluence. The irradiation data for H-451 and ATR-2E graphites were used for the evaluation of the interpolation and extrapolation of irradiation data for IG-110. It was shown in this study that the proposed interpolation and extrapolation method is reasonable for IG-110 with regard to the database available at present. (author)
On an accelerated procedure of extrapolation
Directory of Open Access Journals (Sweden)
A. Yeyios
1981-12-01
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.
Jiang, Chaowei; Feng, Xueshang
2013-01-01
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 Sak...
A. Zlotnik; Zlotnik, I.
2014-01-01
We consider the Cauchy problem for the 1D generalized Schr\\"odinger equation on the whole axis. To solve it, any order finite element in space and the Crank-Nicolson in time method with the discrete transparent boundary conditions (TBCs) has recently been constructed. Now we engage the Richardson extrapolation to improve significantly the accuracy in time step. To study its properties, we give results of numerical experiments and enlarged practical error analysis for three t...
Li-O2 Kinetic Overpotentials: Tafel Plots from Experiment and First-Principles Theory.
Viswanathan, V; Nørskov, J K; Speidel, A; Scheffler, R; Gowda, S; Luntz, A C
2013-02-21
We report the current dependence of the fundamental kinetic overpotentials for Li-O2 discharge and charge (Tafel plots) that define the optimal cycle efficiency in a Li-air battery. Comparison of the unusual experimental Tafel plots obtained in a bulk electrolysis cell with those obtained by first-principles theory is semiquantitative. The kinetic overpotentials for any practical current density are very small, considerably less than polarization losses due to iR drops from the cell impedance in Li-O2 batteries. If only the kinetic overpotentials were present, then a discharge-charge voltaic cycle efficiency of ?85% should be possible at ?10 mA/cm(2) superficial current density in a battery of ?0.1 m(2) total cathode area. We therefore suggest that minimizing the cell impedance is a more important problem than minimizing the kinetic overpotentials to develop higher current Li-air batteries. PMID:26281865
Terk, Erik, 1952-
2009-01-01
Eestis korraldatud uuringu "Eesti loomemajanduse potentsiaal ja arenguks vajalikud riikud toetusmeetmed" tulemustest lähtudes püütakse leida optimaalseid suhteid loovinimeste toetusmeetmete ja iseorganiseerumise vahel. Vestlusringis Eesti Tuleviku-uuringute Instituudi direktor Erik Terk ja teadurid Silja Lassur ja Külliki Tafel-Viia
DEFF Research Database (Denmark)
Robbe, Joost Roger
2015-01-01
This article investigates the relationship between Dirc van Delft’s Tafel vanden kersten ghelove (1404) and earlier traditional medieval literature on death and dying. Two chapters in the Tafel contain a treatise on death: Somerstuc XXXVIII and XLVIII. Their sources include not only Anselm of Canterbury’s Admonitio morientis (c. 1100) and Henry Suso’s Horologium aeternae sapientiae (1331-34), but also the popular 14th-century Verses of Saint Bernard. The article demonstrates that the treatises are much more than simple compilations. Within the context of the sacrament of the sick in the first treatise, Dirc van Delft presents a veritable ars moriendi which provides practical guidance for the dying and those attending them. The treatise culminates in a vivid drama in which the soul, being subject to three temptations of the devil, can benefit from the protection of its guardian angel as well as the Verses of Saint Bernard. In the second treatise, inspired by Henry Suso, Dirc van Delft addresses the danger of asudden and unprepared death, concluding with an original ars vivendi for a life of moral perfection.
Weniger, Ernst Joachim; Kirtman, Bernard
2000-01-01
Quasi-onedimensional stereoregular polymers as for example polyacetylene are currently of considerable interest. There are basically two different approaches for doing electronic structure calculations: One method is essentially based on concepts of solid state theory. The other method is essentially a quantum chemical method since it approximates the polymer by oligomers consisting of a finite number of monomer units. In this way, the highly developed technology of quantum ...
Builtin vs. auxiliary detection of extrapolation risk.
Energy Technology Data Exchange (ETDEWEB)
Munson, Miles Arthur; Kegelmeyer, W. Philip,
2013-02-01
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.
Manson, S. S.; Ensign, C. R.
1978-01-01
The minimum commitment method has been applied to the analysis of creep-rupture data. The method is based on a parameter representing the focal point of convergence of all isothermals when extended to the long or short times necessary for such convergence to occur. The technique may be applied by manual-graphic analysis on computer code. It is illustrated for the nickel-base alloy Astroloy.
Carlos M. Morales-Bautista; Randy H. Adams; Francisco Guzmán-Osorio; Deysi Marín-García
2012-01-01
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 A...
International Nuclear Information System (INIS)
The report resumes the calculation basia given by Walter Gloyer in his different papers and adds certain improvements acquired by long experience in thermal calculation engineering. The following points, necessary for the calculations, are examined in detail: verification of the thermal balances; calculation of the average temperature difference between the vapour and liquid, taking into account the efficiency of the exchanger; pressure loss of the phase stream; calculation of the various thermal resistances; calculation of the exchange surface. The basis of calculation being thus defined, a numerical application of the cooler calculation for hydrocarbon vapour + liquid mixtures with partial condensation is treated and enables the general use of this method to be considered for transfer problems in two-phase streams
Allodji, Rodrigue S; Schwartz, Boris; Diallo, Ibrahima; Agbovon, Césaire; Laurier, Dominique; de Vathaire, Florent
2015-08-01
Analyses of the Life Span Study (LSS) of Japanese atomic bombing survivors have routinely incorporated corrections for additive classical measurement errors using regression calibration. Recently, several studies reported that the efficiency of the simulation-extrapolation method (SIMEX) is slightly more accurate than the simple regression calibration method (RCAL). In the present paper, the SIMEX and RCAL methods have been used to address errors in atomic bomb survivor dosimetry on solid cancer and leukaemia mortality risk estimates. For instance, it is shown that using the SIMEX method, the ERR/Gy is increased by an amount of about 29 % for all solid cancer deaths using a linear model compared to the RCAL method, and the corrected EAR 10(-4) person-years at 1 Gy (the linear terms) is decreased by about 8 %, while the corrected quadratic term (EAR 10(-4) person-years/Gy(2)) is increased by about 65 % for leukaemia deaths based on a linear-quadratic model. The results with SIMEX method are slightly higher than published values. The observed differences were probably due to the fact that with the RCAL method the dosimetric data were partially corrected, while all doses were considered with the SIMEX method. Therefore, one should be careful when comparing the estimated risks and it may be useful to use several correction techniques in order to obtain a range of corrected estimates, rather than to rely on a single technique. This work will enable to improve the risk estimates derived from LSS data, and help to make more reliable the development of radiation protection standards. PMID:25894839
One-step lowrank wave extrapolation
Sindi, G.
2014-01-01
Wavefield extrapolation is at the heart of modeling, imaging, and Full waveform inversion. Spectral methods gained well deserved attention due to their dispersion free solutions and their natural handling of anisotropic media. We propose a scheme a modified one-step lowrank wave extrapolation using Shanks transform in isotropic, and anisotropic media. Specifically, we utilize a velocity gradient term to add to the accuracy of the phase approximation function in the spectral implementation. With the higher accuracy, we can utilize larger time steps and make the extrapolation more efficient. Applications to models with strong inhomogeneity and considerable anisotropy demonstrates the utility of the approach.
Directory of Open Access Journals (Sweden)
Gérard Meunier
2013-03-01
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.
Manson, S. S.; Ensign, C. R.
1978-01-01
The Minimum Commitment Method was applied to two sets of data for which multiple heat information was available. For one alloy, a 304 stainless steel studied in Japan, data on nine well characterized heats were used, while for a proprietary low alloy carbon steel studied in the United Kingdom data were available on seven heats - in many cases to very long rupture times. For this preliminary study no instability factors were used. It was discovered that heat-to-heat variations would be accounted for by introducing heat identifiers in the form A + B log sigma where sigma is the stress and the constants A and B depend only on the heat. With these identifiers all the data could be collapsed onto a single master curve, even though there was considerable scatter among heats. Using these identifiers together with the average behavior of all heats made possible the determination of an accurate constitutive equation for each individual heat. Two basic approaches are discussed for applying the results of the analysis.
Gauging station rating curve extrapolation using HEC-RAS
Šupek, Miha
2008-01-01
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 ...
A fast marching approach to multidimensional extrapolation
McCaslin, Jeremy O.; Courtine, Émilien; Desjardins, Olivier
2014-10-01
A computationally efficient approach to extrapolating a data field with second order accuracy is presented. This is achieved through the sequential solution of non-homogeneous linear static Hamilton-Jacobi equations, which can be performed rapidly using the fast marching methodology. In particular, the method relies on a fast marching calculation of the distance from the manifold ? that separates the subdomain ?in over which the quanity is known from the subdomain ?out over which the quantity is to be extrapolated. A parallel algorithm is included and discussed in the appendices. Results are compared to the multidimensional partial differential equation (PDE) extrapolation approach of Aslam (Aslam (2004) [31]). It is shown that the rate of convergence of the extrapolation within a narrow band near ? is controlled by both the number of successive extrapolations performed and the order of accuracy of the spatial discretization. For m successive extrapolating steps and a spatial discretization scheme of order N, the rate of convergence in a narrow band is shown to be min(N+1,m+1). Results show that for a wide range of error levels, the fast marching extrapolation strategy leads to dramatic improvements in computational cost when compared to the PDE approach.
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.
Ecotoxicological effects extrapolation models
Energy Technology Data Exchange (ETDEWEB)
Suter, G.W. II
1996-09-01
One of the central problems of ecological risk assessment is modeling the relationship between test endpoints (numerical summaries of the results of toxicity tests) and assessment endpoints (formal expressions of the properties of the environment that are to be protected). For example, one may wish to estimate the reduction in species richness of fishes in a stream reach exposed to an effluent and have only a fathead minnow 96 hr LC50 as an effects metric. The problem is to extrapolate from what is known (the fathead minnow LC50) to what matters to the decision maker, the loss of fish species. Models used for this purpose may be termed Effects Extrapolation Models (EEMs) or Activity-Activity Relationships (AARs), by analogy to Structure-Activity Relationships (SARs). These models have been previously reviewed in Ch. 7 and 9 of and by an OECD workshop. This paper updates those reviews and attempts to further clarify the issues involved in the development and use of EEMs. Although there is some overlap, this paper does not repeat those reviews and the reader is referred to the previous reviews for a more complete historical perspective, and for treatment of additional extrapolation issues.
Load Extrapolation During Operation for Wind Turbines
Toft, Henrik Stensgaard; Sørensen, John Dalsgaard
2008-01-01
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 meth...
SPATIAL EXTRAPOLATION OF ANISOTROPIC ROAD TRAFFIC DATA
Hans Braxmeier; Volker Schmidt; Evgueni Spodarev
2011-01-01
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...
International Nuclear Information System (INIS)
Neutron radiation protection is an important research area because of the strong radiation biological effect of neutron field. The radiation dose of neutron is closely related to the neutron energy, and the connected relationship is a complex function of energy. For the low-level neutron radiation field (e.g. the Am–Be source), the commonly used commercial neutron dosimeter cannot always reflect the low-level dose rate, which is restricted by its own sensitivity limit and measuring range. In this paper, the intensity distribution of neutron field caused by a curie level Am–Be neutron source was investigated by measuring the count rates obtained through a 3He proportional counter at different locations around the source. The results indicate that the count rates outside of the source room are negligible compared with the count rates measured in the source room. In the source room, 3He proportional counter and neutron dosimeter were used to measure the count rates and dose rates respectively at different distances to the source. The results indicate that both the count rates and dose rates decrease exponentially with the increasing distance, and the dose rates measured by a commercial dosimeter are in good agreement with the results calculated by the Geant4 simulation within the inherent errors recommended by ICRP and IEC. Further studies presented in this paper indicate that the low-level neutron dose equivalent rates in the source room increase exponentially with the increasing low-energy neutron count rates when the source is lifted from the shield with different radiation intensities. Based on this relationship as well as the count rates measured at larger distance to the source, the dose rates can be calculated approximately by the extrapolation method. This principle can be used to estimate the low level neutron dose values in the source room which cannot be measured directly by a commercial dosimeter. - Highlights: • The scope of the affected area for a curie-level Am–Be neutron source was measured. • The low-level neutron dose-equivalent rates around the source increase exponentially with the increasing count rates when the source is in different shielding state. • This principle can be used to estimate the low level neutron dose values in the source room which cannot be measured directly by a commercial dosimeter
SPATIAL EXTRAPOLATION OF ANISOTROPIC ROAD TRAFFIC DATA
Directory of Open Access Journals (Sweden)
Hans Braxmeier
2011-05-01
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.
A model-free approach to low-dose extrapolation.
Krewski, D; Gaylor, D; Szyszkowicz, M
1991-01-01
Estimates of risk associated with exposure to low levels of carcinogenic substances present in the environment are generally obtained by linear extrapolation from higher exposure levels at which risks can be estimated directly. In this paper, we examine the scientific basis for the assumption of low-dose linearity in carcinogenic risk assessment and the different statistical methods that have been proposed for linear extrapolation. A model-free approach to linear extrapolation is described an...
Uncertainties of Euclidean Time Extrapolation in Lattice Effective Field Theory
Lähde, Timo A; Krebs, Hermann; Lee, Dean; Meißner, Ulf-G; Rupak, Gautam
2014-01-01
Extrapolations in Euclidean time form a central part of Nuclear Lattice Effective Field Theory (NLEFT) calculations using the Projection Monte Carlo method, as the sign problem in many cases prevents simulations at large Euclidean time. We review the next-to-next-to-leading order NLEFT results for the alpha nuclei up to $^{28}$Si, with emphasis on the Euclidean time extrapolations, their expected accuracy and potential pitfalls. We also discuss possible avenues for improving the reliability of Euclidean time extrapolations in NLEFT.
Extrapolated implicit-explicit time stepping.
Energy Technology Data Exchange (ETDEWEB)
Constantinescu, E. M.; Sandu, A.; Mathematics and Computer Science; Virginia Polytechnic Inst. and State Univ.
2010-01-01
This paper constructs extrapolated implicit-explicit time stepping methods that allow one to efficiently solve problems with both stiff and nonstiff components. The proposed methods are based on Euler steps and can provide very high order discretizations of ODEs, index-1 DAEs, and PDEs in the method-of-lines framework. Implicit-explicit schemes based on extrapolation are simple to construct, easy to implement, and straightforward to parallelize. This work establishes the existence of perturbed asymptotic expansions of global errors, explains the convergence orders of these methods, and studies their linear stability properties. Numerical results with stiff ODE, DAE, and PDE test problems confirm the theoretical findings and illustrate the potential of these methods to solve multiphysics multiscale problems.
Wavefield extrapolation in pseudodepth domain
Ma, Xuxin
2013-02-01
Wavefields are commonly computed in the Cartesian coordinate frame. Its efficiency is inherently limited due to spatial oversampling in deep layers, where the velocity is high and wavelengths are long. To alleviate this computational waste due to uneven wavelength sampling, we convert the vertical axis of the conventional domain from depth to vertical time or pseudodepth. This creates a nonorthognal Riemannian coordinate system. Isotropic and anisotropic wavefields can be extrapolated in the new coordinate frame with improved efficiency and good consistency with Cartesian domain extrapolation results. Prestack depth migrations are also evaluated based on the wavefield extrapolation in the pseudodepth domain.© 2013 Society of Exploration Geophysicists. All rights reserved.
Chiral extrapolation and physical insights
Young, R.D.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, University of Adelaide, Adelaide, SA 5005, Australia); Leinweber, D. B.; Thomas, A.W.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, The University of Adelaide, Australia)
2003-01-01
It has recently been established that finite-range regularisation in chiral effective field theory enables the accurate extrapolation of modern lattice QCD results to the chiral regime. We review some of the highlights of extrapolations of quenched lattice QCD results, including spectroscopy and magnetic moments. The $\\Delta$ resonance displays peculiar chiral features in the quenched theory which can be exploited to demonstrate the presence of significant chiral corrections.
Load Extrapolation During Operation for Wind Turbines
DEFF Research Database (Denmark)
Toft, Henrik Stensgaard; SØrensen, John Dalsgaard
2008-01-01
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.
Modified Extrapolation Length Renormalization Group Equation
Morris, Jacob; Rudnick, Joseph
1999-01-01
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} = -...
Statistical modeling and extrapolation of carcinogenesis data
International Nuclear Information System (INIS)
Mathematical models of carcinogenesis are reviewed, including pharmacokinetic models for metabolic activation of carcinogenic substances. Maximum likelihood procedures for fitting these models to epidemiological data are discussed, including situations where the time to tumor occurrence is unobservable. The plausibility of different possible shapes of the dose response curve at low doses is examined, and a robust method for linear extrapolation to low doses is proposed and applied to epidemiological data on radiation carcinogenesis
Novel Extrapolation for Strong Coupling Expansions
Schmidt, K. P.; Knetter, C.; Uhrig, G.S.
2002-01-01
We present a novel extrapolation scheme for high order series expansions. The idea is to express the series, obtained in orders of an external variable, in terms of an internal parameter of the system. Here we apply this method to the 1-triplet dispersion in an antiferromagnetic $S=1/2$ Heisenberg ladder. By the use of the internal parameter the accuracy of the truncated series is enhanced tremendously.
Efficient depth extrapolation of waves in elastic isotropic media
Maharramov, Musa
2012-01-01
We propose a computationally efficient technique for extrapolating seismic waves in an arbitrary isotropic elastic medium. The method is based on factorizing the full elastic wave equation into a product of pseudo-differential operators. The method extrapolates displacement fields, hence can be used for modeling both pressure and shear waves. The proposed method can achieve a significant reduction in the cost of elastic modeling compared to the currently prevalent time- and ...
Energy Technology Data Exchange (ETDEWEB)
Juengst, H.G.
1991-04-01
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.). [Deutsch] Mit Fertigstellung dieser Arbeit wurde fuer SAPHIR die Anbindung einzelner Detektorkomponenten mit minimal erforderlichem Rechenaufwand bei der Datenauswertung geschaffen. Es wruden Studien fuer die wichtigsten Anbindungen untersucht und die erreichbaren Fehler dargestellt. Dabei wurden die Moeglichkeiten und Grenzen der Principal Components Analysis (PCA) und der Polynome an konkreten und fuer SAPHIR wichtigen Fragestellungen aufgezeigt. Ausserdem wurde gezeigt, dass die PCA und Polynome die Grundlage fuer eine Spurrekonstruktion mit einem globalen Spurmodell sein kann, wobei wichtig ist, dass dies trotz eines inhomogenen Magnetfeldes mit wenig Rechenbedarf verwirklicht werden kann. Nebenbei entstand das Paket ZFAST mit Routinen zur maschinenunabhaengigen Speicherung von Datenstrukturen. Dieses Paket laesst sich sehr leicht an verschiedenste Rechner anpassen. Interessant ist ZFAST wegen seiner Implementierung der Maschinenunabhaengigkeit. ZFAST wird mit dem seit langer Zeit existierenden Speicherverwaltungsprogramm ZBOOK zu einer Einheit, ohne dass Programme fuer ZFAST angepasst werden muessen. (orig.).
On extrapolation of virial coefficients of hard spheres
Directory of Open Access Journals (Sweden)
M. On?ák
2012-06-01
Full Text Available Several methods of extrapolating the virial coefficients, including those proposed in this work, are discussed. The methods are demonstrated on predicting higher virial coefficients of one-component hard spheres. Estimated values of the eleventh to fifteenth virial coefficients are suggested. It has been speculated that the virial coefficients, Bn, beyond B14 may decrease with increasing n, and may reach negative values at large n. The extrapolation techniques may be utilized in other fields of science where the art of extrapolation plays a role.
An algorithm for a generalization of the Richardson extrapolation process
Ford, William F.; Sidi, Avram
1987-01-01
The paper presents a recursive method, designated the W exp (m)-algorithm, for implementing a generalization of the Richardson extrapolation process. Compared to the direct solution of the linear sytems of equations defining the extrapolation procedure, this method requires a small number of arithmetic operations and very little storage. The technique is also applied to solve recursively the coefficient problem associated with the rational approximations obtained by applying a d-transformation to power series. In the course of development a new recursive algorithm for implementing a very general extrapolation procedure is introduced, for solving the same problem. A FORTRAN program for the W exp (m)-algorithm is also appended.
Cross rules of some extrapolation algorithms
International Nuclear Information System (INIS)
In this paper, we present the cross rules of some extrapolation algorithms. These new cross rules are similar in their spirit to the cross rule for the scalar ?-algorithm and the rhov-algorithm. The first interest of such rules is that, in the algorithms for implementing sequence transformations for the acceleration of the convergence, they allow us to compute only the quantities which have a signification for extrapolation and to jump over the intermediate ones. The second interest comes out from the link between convergence acceleration methods, soliton theory and discrete integrable systems. In some cases, cross rules directly lead to physically significant integrable systems. For example, the cross rule of the confluent qd-algorithm leads to the celebrated Toda equation, which is known to have physical applications
Chiral extrapolations for nucleon magnetic moments
Hall, J M M; Young, R D
2012-01-01
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.
Residual extrapolation operators for efficient wavefield construction
Alkhalifah, T.
2013-02-27
Solving the wave equation using finite-difference approximations allows for fast extrapolation of the wavefield for modelling, imaging and inversion in complex media. It, however, suffers from dispersion and stability-related limitations that might hamper its efficient or proper application to high frequencies. Spectral-based time extrapolation methods tend to mitigate these problems, but at an additional cost to the extrapolation. I investigate the prospective of using a residual formulation of the spectral approach, along with utilizing Shanks transform-based expansions, that adheres to the residual requirements, to improve accuracy and reduce the cost. Utilizing the fact that spectral methods excel (time steps are allowed to be large) in homogeneous and smooth media, the residual implementation based on velocity perturbation optimizes the use of this feature. Most of the other implementations based on the spectral approach are focussed on reducing cost by reducing the number of inverse Fourier transforms required in every step of the spectral-based implementation. The approach here fixes that by improving the accuracy of each, potentially longer, time step.
On extrapolation of virial coefficients of hard spheres
M. On?ák; Malijevský, A.; Kolafa, J; Labík, S.
2012-01-01
Several methods of extrapolating the virial coefficients, including those proposed in this work, are discussed. The methods are demonstrated on predicting higher virial coefficients of one-component hard spheres. Estimated values of the eleventh to fifteenth virial coefficients are suggested. It has been speculated that the virial coefficients, Bn, beyond B14 may decrease with increasing n, and may reach negative values at large n. The extrapolation techniques may be utilized in other fields ...
Methodology for extrapolation of rock mass deformability parameters in tunneling
Zafirovski Zlatko; Peševski Igor; Papi? Jovan Br.
2012-01-01
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...
Energy Technology Data Exchange (ETDEWEB)
Nichols, John W.; Schultz, Irv R.; Fitzsimmons, Patrick N..
2006-06-10
Mammalian researchers have developed a stepwise approach to predict in vivo hepatic clearance from measurements of in vitro hepatic metabolism. The resulting clearance estimates have been used to screen drug candidates, identify potential drug-drug interactions, investigate idiosyncratic drug responses, and support toxicology risk assessments. In this report we review these methods, discuss their potential application to studies with fish, and describe how extrapolated values could be incorporated into well-known compartmental kinetic models. Empirical equations that relate extrapolation factors to chemical log Kow are given to facilitate the incorporation of metabolism data into bioconcentration and bioaccumulation models. Because they explicitly incorporate the concept of clearance, compartmental clearance volume models are particularly well suited for incorporating hepatic clearance estimates. The manner in which these clearance values are incorporated into a given model depends, however, on the measurement frame of reference. Procedures for the incorporation of in vitro metabolism data into physiologically based toxicokinetic (PBTK) models are also described. Unlike most compartmental models, PBTK models are developed to describe the effects of metabolism in the tissue where it occurs. In addition, PBTK models are well suited to modeling metabolism in more than one tissue.
Effective orthorhombic anisotropic models for wavefield extrapolation
Ibanez-Jacome, W.
2014-07-18
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, we generate effective isotropic inhomogeneous models that are capable of reproducing the firstarrival kinematic aspects of the orthorhombic wavefield. First, in order to compute traveltimes in vertical orthorhombic media, we 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 ones, is represented by a sixth order polynomial equation with 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, and using them to explicitly evaluate 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. We 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.
Effective orthorhombic anisotropic models for wavefield extrapolation
Ibanez-Jacome, Wilson; Alkhalifah, Tariq; Waheed, Umair bin
2014-09-01
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, we 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, we 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 ones, is represented by a sixth order polynomial equation with 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, and using them to explicitly evaluate 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. We 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.
Uncertainties of Euclidean time extrapolation in lattice effective field theory
International Nuclear Information System (INIS)
Extrapolations in Euclidean time form a central part of nuclear lattice effective field theory (NLEFT) calculations using the projection Monte Carlo method, as the sign problem in many cases prevents simulations at large Euclidean time. We review the next-to-next-to-leading order NLEFT results for the alpha nuclei up to 28Si, with emphasis on the Euclidean time extrapolations, their expected accuracy and potential pitfalls. We also discuss possible avenues for improving the reliability of Euclidean time extrapolations in NLEFT. (paper)
3D Hail Size Distribution Interpolation/Extrapolation Algorithm
Lane, John
2013-01-01
Radar data can usually detect hail; however, it is difficult for present day radar to accurately discriminate between hail and rain. Local ground-based hail sensors are much better at detecting hail against a rain background, and when incorporated with radar data, provide a much better local picture of a severe rain or hail event. The previous disdrometer interpolation/ extrapolation algorithm described a method to interpolate horizontally between multiple ground sensors (a minimum of three) and extrapolate vertically. This work is a modification to that approach that generates a purely extrapolated 3D spatial distribution when using a single sensor.
Optimization of Coronal Magnetic Field Extrapolations Using Images
Jones, Shaela; Davila, Joseph M.; Uritsky, Vadim M.
2015-04-01
The coronal magnetic field plays a significant role in every major question we have asked about the corona, as well as about other systems and bodies throughout the heliosphere. Knowledge of the magnetic field is essential for understanding and predicting many phenomena. Despite its importance, the coronal magnetic field is not well measured, due to the tenuous nature of the coronal plasma. In the absence of reliable coronal measurements, solar physicists have developed many methods for extrapolating the photospheric magnetic field out into the corona. However, these extrapolation methods must incorporate many assumptions, and it has been shown that they do not always match observed coronal features well.Here we present a new method we are developing for altering an extrapolated magnetic field to better agree with features identified in coronal images. Our method proceeds by iteratively altering the boundary condition (the photospheric magnetogram) and comparing the extrapolated field to features observed in coronal images until optimal agreement is reached. This technique can be used in combination with any extrapolation method, depending on computational capabilities. By comparing the extrapolations with coronagraph images (see related submission by Uritsky et al.), it will be possible to improve determination of sources of open flux in the inner heliosphere.
UFOs: Observations, Studies and Extrapolations
Baer, T; Barnes, M J; Bartmann, W; Bracco, C; Carlier, E; Cerutti, F; Dehning, B; Ducimetière, L; Ferrari, A; Ferro-Luzzi, M; Garrel, N; Gerardin, A; Goddard, B; Holzer, E B; Jackson, S; Jimenez, J M; Kain, V; Zimmermann, F; Lechner, A; Mertens, V; Misiowiec, M; Nebot Del Busto, E; Morón Ballester, R; Norderhaug Drosdal, L; Nordt, A; Papotti, G; Redaelli, S; Uythoven, J; Velghe, B; Vlachoudis, V; Wenninger, J; Zamantzas, C; Zerlauth, M; Fuster Martinez, N
2012-01-01
UFOs (“ Unidentified Falling Objects”) could be one of the major performance limitations for nominal LHC operation. Therefore, in 2011, the diagnostics for UFO events were significantly improved, dedicated experiments and measurements in the LHC and in the laboratory were made and complemented by FLUKA simulations and theoretical studies. The state of knowledge is summarized and extrapolations for LHC operation in 2012 and beyond are presented. Mitigation strategies are proposed and related tests and measures for 2012 are specified.
Extrapolating future Arctic ozone losses
Knudsen, B. M.; Andersen, S B; Christiansen, B; Larsen, N.; Rex, M.; Harris, N R P; Naujokat, B.
2004-01-01
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...
Self-similar extrapolation from weak to strong coupling
GLUZMAN, S; V.I. Yukalov
2010-01-01
The problem is addressed of defining the values of functions, whose variables tend to infinity, from the knowledge of these functions at asymptotically small variables close to zero. For this purpose, the extrapolation by means of different types of self-similar approximants is employed. Two new variants of such an extrapolation are suggested. The methods are illustrated by several examples of systems typical of chemical physics, statistical physics, and quantum physics. The...
Extrapolations of nuclear binding energies from new linear mass relations
DEFF Research Database (Denmark)
Hove, D.; Jensen, A. S.; Riisager, K.
2013-01-01
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 ...
Edwards, A. R.
1998-01-01
Als toepassingsgericht en multidisciplinaire wetenschap behoeft de bestuurskunde een eigen methodologie, naast de algemene sociaalwetenschappelijke methodologie voor het doen van empirisch onderzoek. Deze eigen bestuurskundige methodologie zou kunnen uitgaan van een argumentatieve benadering, gericht op versterking van de kwaliteit van de praktijkredeneringen die aan bestuurlijk handelen ten grondslag liggen. In dit artikel wordt aangegeven hoe de door Brasz ontwikkelde praxeologische methode...
International Nuclear Information System (INIS)
Study of the reaction ?-p ? ?-?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 ?-p ? ?-p channel. The high statistics allow us to specify the mass and the width of the ?- resonance. In other hand, if the ?- production parameters are independent of the ?- 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 ?-?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)
Schroedinger's radial equation - Solution by extrapolation
Goorvitch, D.; Galant, D. C.
1992-01-01
A high-accuracy numerical method for the solution of a 1D Schroedinger equation that is suitable for a diatomic molecule, obtained by combining a finite-difference method with iterative extrapolation to the limit, is presently shown to have several advantages over more conventional methods. Initial guesses for the term values are obviated, and implementation of the algorithm is straightforward. The method is both less sensitive to round-off error, and faster than conventional methods for equivalent accuracy. These advantages are illustrated through the solution of Schroedinger's equation for a Morse potential function suited for HCl and a numerically derived Rydberg-Klein-Rees potential function for the X 1Sigma(+) state of CO.
Manson, S. S.; Ensign, C. R.
1978-01-01
The framework in which minimum-commitment analyses of creep-rupture data can be implemented is outlined. The approach is termed the focal point convergence method (FPCM) because the basic parameter A, also known as stability factor, is geometrically the (imaginary) focal point of convergence of all isothermals when extended to the very long or very short times necessary for such convergence to occur. The method can be implemented either by manual-graphical analysis or by computer code. The method is illustrated in detail for the nickel-base alloy Astroloy, as well as for steels, other nickel-base alloys, and aluminum alloys. The minimum-commitment concept is extended to the analysis of creep-rupture data where each isothermal is generated by an oblique translation of the 'master curve' when plotted on log rupture time and log stress axes. The oblique translation method uses the same types of functions in the FPCM. Approaches for treating multiheats on the basis of the FPCM are discussed in detail.
International Nuclear Information System (INIS)
We developed a coronal nonlinear force-free field (COR-NLFFF) forward-fitting code that fits an approximate nonlinear force-free field (NLFFF) solution to the observed geometry of automatically traced coronal loops. In contrast to photospheric NLFFF codes, which calculate a magnetic field solution from the constraints of the transverse photospheric field, this new code uses coronal constraints instead, and this way provides important information on systematic errors of each magnetic field calculation method, as well as on the non-force-freeness in the lower chromosphere. In this study we applied the COR-NLFFF code to NOAA Active Region 11158, during the time interval of 2011 February 12-17, which includes an X2.2 GOES-class flare plus 35 M- and C-class flares. We calculated the free magnetic energy with a 6 minute cadence over 5 days. We find good agreement between the two types of codes for the total nonpotential EN and potential energy EP but find up to a factor of 4 discrepancy in the free energy E free = EN – EP and up to a factor of 10 discrepancy in the decrease of the free energy ?E free during flares. The coronal NLFFF code exhibits a larger time variability and yields a decrease of free energy during the flare that is sufficient to satisfy the flare energy budget, while the photospheric NLFFF code shows much less time variability and an order of magnitude less free-energy decrease during flares. The discrepancy may partly be due to the preprocessing of photospheric vector data but more likely is due to the non-force-freeness in the lower chromosphere. We conclude that the coronal field cannot be correctly calculated on the basis of photospheric data alone and requires additional information on coronal loop geometries.
Extrapolation Technique Pitfalls in Asymmetry Measurements at Colliders
Colletti, Katrina; Toback, David; Wilson, Jonathan S
2015-01-01
Asymmetry measurements are common in collider experiments and can sensitively probe particle properties. Typically, data can only be measured in a finite region covered by the detector, so an extrapolation from the visible asymmetry to the inclusive asymmetry is necessary. Often a constant multiplicative factor is more than adequate for the extrapolation and this factor can be readily determined using simulation methods. However, there is a potential, avoidable pitfall involved in the determination of this factor when the asymmetry in the simulated data sample is small. We find that to obtain a reliable estimate of the extrapolation factor, the number of simulated events required rises as the inverse square of the simulated asymmetry; this can mean that an unexpectedly large sample size is required when determining its value.
Chiral extrapolation beyond the power-counting regime
Hall, J M M; Leinweber, D B; Liu, K F; Mathur, N; Young, R D; Zhang, J B
2011-01-01
Chiral effective field theory can provide valuable insight into the chiral physics of hadrons when used in conjunction with non-perturbative schemes such as lattice QCD. In this discourse, the attention is focused on extrapolating the mass of the rho meson to the physical pion mass in quenched QCD (QQCD). With the absence of a known experimental value, this serves to demonstrate the ability of the extrapolation scheme to make predictions without prior bias. By using extended effective field theory developed previously, an extrapolation is performed using quenched lattice QCD data that extends outside the chiral power-counting regime (PCR). The method involves an analysis of the renormalization flow curves of the low energy coefficients in a finite-range regularized effective field theory. The analysis identifies an optimal regulator, which is embedded in the lattice QCD data themselves. This optimal regulator is the regulator value at which the renormalization of the low energy coefficients is approximately i...
Extrapolations of nuclear binding energies from new linear mass relations
DEFF Research Database (Denmark)
Hove, D.; Jensen, A. S.
2013-01-01
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 Q? 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.
The determination of the order parameters of nematic liquid crystals by mean field extrapolation
Tough, R.J.A.; Bradshaw, M J
1983-01-01
An improved method for the determination of the order parameter of a nematic liquid crystal from the anisotropy in its macroscopic physical properties is described. This method, which exploits an extrapolation technique based on the mean field theory of nematic ordering, is compared with the more conventional Haller extrapolation technique and is found to give much more consistent and reliable results.
Extrapolation of power series by self-similar factor and root approximants
V.I. Yukalov; GLUZMAN, S
2004-01-01
The problem of extrapolating the series in powers of small variables to the region of large variables is addressed. Such a problem is typical of quantum theory and statistical physics. A method of extrapolation is developed based on self-similar factor and root approximants, suggested earlier by the authors. It is shown that these approximants and their combinations can effectively extrapolate power series to the region of large variables, even up to infinity. Several exampl...
Chiral extrapolations of nucleon properties from lattice QCD
Hemmert, Thomas R.; Procura, Massimiliano; Weise, Wolfram(Physik Department, Technische Universität München, Garching, D-85747, Germany)
2003-01-01
We report on recent work about the study of quark mass dependence of nucleon magnetic moments and axial-vector coupling constant. We examine the feasibility of chiral effective field theory methods for the extrapolation of lattice QCD data obtained at relative large pion masses down to the physical values.
Fuzzy Model Comparison to Extrapolate Rainfall Data
Directory of Open Access Journals (Sweden)
C. Tzimopoulos
2008-01-01
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.
Outlier robustness for wind turbine extrapolated extreme loads
DEFF Research Database (Denmark)
Natarajan, Anand; Verelst, David Robert
2012-01-01
Methods for extrapolating extreme loads to a 50 year probability of exceedance, which display robustness to the presence of outliers in simulated loads data set, are described. Case studies of isolated high extreme out-of-plane loads are discussed to emphasize their underlying physical reasons. Stochastic identification of numerical artifacts in simulated loads is demonstrated using the method of principal component analysis. The extrapolation methodology is made robust to outliers through a weighted loads approach, whereby the eigenvalues of the correlation matrix obtained using the loads with its dependencies is utilized to estimate a probability for the largest extreme load to occur at a specific mean wind speed. This inherently weights extreme loads that occur frequently within mean wind speed bins higher than isolated occurrences of extreme loads. Primarily, the results for the blade root out-of-plane loads are presented here as those extrapolated loads have shown wide variability in literature, but the method can be generalized to any other component load. The convergence of the 1 year extrapolated extreme blade root out-of-plane load with the number of turbulent wind samples used in the loads simulation is demonstrated and compared with published results. Further effects of varying wind inflow angles and shear exponent is brought out. Parametric fitting techniques that consider all extreme loads including ‘outliers’ are proposed, and the physical reasons that result in isolated high extreme loads are highlighted, including the effect of the wind turbine controls system. Copyright © 2011 John Wiley & Sons, Ltd.
Reexamination of Finite-Lattice Extrapolation of Haldane Gaps
Nakano, Hiroki; Terai, Akira
2008-01-01
We propose two methods of estimating a systematic error in extrapolation to the infinite-size limit in the study of measuring the Haldane gaps of the one-dimensional Heisenberg antiferromagnet with the integer spin up to S=5. The finite-size gaps obtained by numerical diagonalizations based on Lanczos algorithm are presented for sizes that have not previously been reported. The changes of boundary conditions are also examined. We successfully demonstrate that our methods of ...
Extrapolation procedures in Mott electron polarimetry
Gay, T. J.; Khakoo, M. A.; Brand, J. A.; Furst, J. E.; Wijayaratna, W. M. K. P.; Meyer, W. V.; Dunning, F. B.
1992-01-01
In standard Mott electron polarimetry using thin gold film targets, extrapolation procedures must be used to reduce the experimentally measured asymmetries A to the values they would have for scattering from single atoms. These extrapolations involve the dependent of A on either the gold film thickness or the maximum detected electron energy loss in the target. A concentric cylindrical-electrode Mott polarimeter, has been used to study and compare these two types of extrapolations over the electron energy range 20-100 keV. The potential systematic errors which can result from such procedures are analyzed in detail, particularly with regard to the use of various fitting functions in thickness extrapolations, and the failure of perfect energy-loss discrimination to yield accurate polarizations when thick foils are used.
Endangered species toxicity extrapolation using ICE models
The National Research Council’s (NRC) report on assessing pesticide risks to threatened and endangered species (T&E) included the recommendation of using interspecies correlation models (ICE) as an alternative to general safety factors for extrapolating across species. ...
Extrapolation Algorithms for Infrared Divergent Integrals
de Doncker, Elise; Fujimoto, Junpei; Hamaguchi, Nobuyuki; Ishikawa, Tadashi; Kurihara, Yoshimasa; Ljucovic, Marko; Shimizu, Yoshimitsu; Yuasa, Fukuko
2011-01-01
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 extr...
Infrared extrapolations of quadrupole moments and transitions
Odell, D; Platter, L
2015-01-01
We study the convergence of bound-state quadrupole moments in finite harmonic oscillator spaces. We derive an expression for the infrared extrapolation for the quadrupole moment of a nucleus and benchmark our results using different model interactions for the deuteron. We find good agreement between the analytically derived and numerically obtained convergence behavior. We also derive an extrapolation formula for electric quadrupole transitions and find good agreement with the numerical calculation of a simple system.
Effective wavefield extrapolation in anisotropic media: Accounting for resolvable anisotropy
Alkhalifah, Tariq Ali
2014-04-30
Spectral methods provide artefact-free and generally dispersion-free wavefield extrapolation in anisotropic media. Their apparent weakness is in accessing the medium-inhomogeneity information in an efficient manner. This is usually handled through a velocity-weighted summation (interpolation) of representative constant-velocity extrapolated wavefields, with the number of these extrapolations controlled by the effective rank of the original mixed-domain operator or, more specifically, by the complexity of the velocity model. Conversely, with pseudo-spectral methods, because only the space derivatives are handled in the wavenumber domain, we obtain relatively efficient access to the inhomogeneity in isotropic media, but we often resort to weak approximations to handle the anisotropy efficiently. Utilizing perturbation theory, I isolate the contribution of anisotropy to the wavefield extrapolation process. This allows us to factorize as much of the inhomogeneity in the anisotropic parameters as possible out of the spectral implementation, yielding effectively a pseudo-spectral formulation. This is particularly true if the inhomogeneity of the dimensionless anisotropic parameters are mild compared with the velocity (i.e., factorized anisotropic media). I improve on the accuracy by using the Shanks transformation to incorporate a denominator in the expansion that predicts the higher-order omitted terms; thus, we deal with fewer terms for a high level of accuracy. In fact, when we use this new separation-based implementation, the anisotropy correction to the extrapolation can be applied separately as a residual operation, which provides a tool for anisotropic parameter sensitivity analysis. The accuracy of the approximation is high, as demonstrated in a complex tilted transversely isotropic model. © 2014 European Association of Geoscientists & Engineers.
Multilevel Richardson-Romberg extrapolation
Lemaire, Vincent; Pagès, Gilles
2014-01-01
We propose and analyze a Multilevel Richardson-Romberg ($MLRR$) estimator which combines the higher order bias cancellation of the Multistep Richardson-Romberg ($MSRR$) method introduced in [Pages 07] and the variance control resulting from the stratification in the Multilevel Monte Carlo ($MLMC$) method (see [Heinrich, 01] and [Giles, 08]). Thus we show that in standard frameworks like discretization schemes of diffusion processes an assigned quadratic error $\\varepsilon$ can be obtained wit...
Frequency extrapolation by nonconvex compressive sensing
International Nuclear Information System (INIS)
Tomographic imaging modalities sample subjects with a discrete, finite set of measurements, while the underlying object function is continuous. Because of this, inversion of the imaging model, even under ideal conditions, necessarily entails approximation. The error incurred by this approximation can be important when there is rapid variation in the object function or when the objects of interest are small. In this work, we investigate this issue with the Fourier transform (FT), which can be taken as the imaging model for magnetic resonance imaging (MRl) or some forms of wave imaging. Compressive sensing has been successful for inverting this data model when only a sparse set of samples are available. We apply the compressive sensing principle to a somewhat related problem of frequency extrapolation, where the object function is represented by a super-resolution grid with many more pixels than FT measurements. The image on the super-resolution grid is obtained through nonconvex minimization. The method fully utilizes the available FT samples, while controlling aliasing and ringing. The algorithm is demonstrated with continuous FT samples of the Shepp-Logan phantom with additional small, high-contrast objects.
Methodology for extrapolation of rock mass deformability parameters in tunneling
Directory of Open Access Journals (Sweden)
Zafirovski Zlatko
2012-01-01
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.
Calculating excitation energies by extrapolation along adiabatic connections
Rebolini, Elisa; Toulouse, Julien; Teale, Andrew M.; Helgaker, Trygve; Savin, Andreas
2015-01-01
In this paper, an alternative method to range-separated linear-response time-dependent density-functional theory and perturbation theory is proposed to improve the estimation of the energies of a physical system from the energies of a partially interacting system. Starting from the analysis of the Taylor expansion of the energies of the partially interacting system around the physical system, we use an extrapolation scheme to improve the estimation of the energies of the phy...
Extrapolation of animal carcinogenicity data: limitations and pitfalls.
Hogan, M D
1983-01-01
Laboratory-generated animal bioassay data often serve as the basis for estimating potential human cancer risk. However, there is no single procedure that has been universally accepted as the method of choice for extrapolating experimentally observed results to the low exposure levels that are generally of public health concern. All of the models proposed to date suffer from various limitations. Therefore, the most prudent approach may be to rely primarily on the more conservative procedures s...
Visek, W. J.
1988-01-01
The Life Sciences Research Office (LSRO) of the Federation of American Societies for Experimental Biology (FASEB) is conducting this symposium under contract with the Center for Food Safety and Applied Nutrition (CFSAN) of the Food and Drug Administration (FDA). The FDA has requested information on the strengths and weaknesses of current interspecies extrapolation methods using metabolic and pharmacokinetic data, identity of data for these methods, bases for choice of extrapolation method and...
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)
International Nuclear Information System (INIS)
180000 pictures taken in the 2 m CERN hydrogen bubble chamber with an incident beam of 2.77 GeV/e were examined. High statistics obtained in the whole angular production range allowed to study the d?/dt differential cross section behaviour, the mass and width of the ? meson, and the multipole parameters of this resonance. Nevertheless, the aim of this experiment was the application of the CHEW - LOW extrapolation method. Different types of extrapolation procedures were compared. Phase shift analysis of the elastic ?? scattering between 500 and 1100 MeV, performed with conformal mappings, allowed to determine the values of the S0, S2, P1, D0, D2 waves. Forward dispersion relations were used to obtain scattering length values of the S2 and P1 phase shifts. (author)
Extrapolation Algorithms for Infrared Divergent Integrals
de Doncker, Elise; Hamaguchi, Nobuyuki; Ishikawa, Tadashi; Kurihara, Yoshimasa; Ljucovic, Marko; Shimizu, Yoshimitsu; Yuasa, Fukuko
2011-01-01
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.
Wavefield extrapolation in pseudo-depth domain
Ma, Xuxin
2012-01-01
Extrapolating seismic waves in Cartesian coordinate is prone to uneven spatial sampling, because the seismic wavelength tends to grow with depth, as velocity increase. We transform the vertical depth axis to a pseudo one using a velocity weighted mapping, which can effectively mitigate this wavelength variation. We derive acoustic wave equations in this new domain based on the direct transformation of the Laplacian derivatives, which admits solutions that are more accurate and stable than those derived from the kinematic transformation. The anisotropic versions of these equations allow us to isolate the vertical velocity influence and reduce its impact on modeling and imaging. The major benefit of extrapolating wavefields in pseudo-depth space is its near uniform wavelength as opposed to the normally dramatic change of wavelength with the conventional approach. Time wavefield extrapolation on a complex velocity shows some of the features of this approach.
A. J. C. Varandas
2008-01-01
The relationship between the triplet- and singlet-pair interaction coefficients in the uniform singlet- and triplet-pair extrapolation method recently suggested for extrapolating ab initio energies to the one-electron basis set limit is analyzed. Based on the premise that such a ratio is invariant over the configuration space of the molecule, generalizations of the method are investigated and their performance tested on extrapolations with MP2, CCD, CCSD, and MRCI(Q) energies. The best varian...
On the basis-set extrapolation
Chandra, Suresh
2015-01-01
A possible solution for the problem of memory-size and computer-time, is the extrapolation of basis-set$^1$. This extrapolation has two exponents $\\alpha$ and $\\beta$, corresponding to the HF (reference energy) and the energy of correlations (EC), respectively. For a given system, the exponents are taken as constant$^2$, and potential energy surfaces (PES) are generated. We have found that the values of $\\alpha$ and $\\beta$ are not constant, but vary from position to position in the system. How to deal with such situation and get very accurate PES, is discussed.
Interpolation and Extrapolation of Precipitation Quantities in Serbia
Directory of Open Access Journals (Sweden)
Rastislav Stojsavljevi?
2013-01-01
Full Text Available The aim of this paper is to indicate the problems with filling the missing data in precipitation database using interpolation and extrapolation methods. Investigated periods were from 1981 to 2010 for Northern (Autonomous Province of Vojvodina and Proper Serbia and from 1971 to 2000 for Southern Serbia (Autonomous Province of Kosovo and Metohia. Database included time series from 78 meteorological stations that had less than 20% of missing data. Interpolation was performed if station had missing data for five consecutive months or less. If station had missing data for six consecutive months or more, extrapolation was performed. For every station with mising data correlation with at least three surrounding stations was performed. The lowest acceptable value of correlation coefficient for precipitation was set at 0,300
Extrapolated HPGe efficiency estimates based on a single calibration measurement
International Nuclear Information System (INIS)
Gamma spectroscopists often must analyze samples with geometries for which their detectors are not calibrated. The effort to experimentally recalibrate a detector for a new geometry can be quite time consuming, causing delay in reporting useful results. Such concerns have motivated development of a method for extrapolating HPGe efficiency estimates from an existing single measured efficiency. Overall, the method provides useful preliminary results for analyses that do not require exceptional accuracy, while reliably bracketing the credible range. The estimated efficiency element-of for a uniform sample in a geometry with volume V is extrapolated from the measured element-of 0 of the base sample of volume V0. Assuming all samples are centered atop the detector for maximum efficiency, element-of decreases monotonically as V increases about V0, and vice versa. Extrapolation of high and low efficiency estimates element-of h and element-of L provides an average estimate of element-of = 1/2 [element-of h + element-of L] ± 1/2 [element-of h - element-of L] (general) where an uncertainty D element-of = 1/2 (element-of h - element-of L] brackets limits for a maximum possible error. The element-of h and element-of L both diverge from element-of 0 as V deviates from V0, causing D element-of to increase accordingly. The above concepts guided development of both conservative and refined estimates for element-of
DEFF Research Database (Denmark)
Toft, Henrik Stensgaard; Naess, Arvid
2011-01-01
The paper explores a recently developed method for statistical response load (load effect) extrapolation for application to extreme response of wind turbines during operation. The extrapolation method is based on average conditional exceedance rates and is in the present implementation restricted to cases where the Gumbel distribution is the appropriate asymptotic extreme value distribution. However, two extra parameters are introduced by which a more general and flexible class of extreme value distributions is obtained with the Gumbel distribution as a subclass. The general method is implemented within a hierarchical model where the variables that influence the loading are divided into ergodic variables and time-invariant non-ergodic variables. The presented method for statistical response load extrapolation was compared with the existing methods based on peak extrapolation for the blade out-of-plane bending moment and the tower mudline bending moment of a pitch-controlled wind turbine. In general, the results show that the method based on average conditional exceedance rates predicts the extrapolated characteristic response loads at the individual mean wind speeds well and results in more consistent estimates than the methods based on peak extrapolation.
Self-Similar Extrapolation of Asymptotic Series and Forecasting for Time Series
V.I. Yukalov
2001-01-01
The method of extrapolating asymptotic series, based on the Self-Similar Approximation Theory, is developed. Several important questions are answered, which makes the foundation of the method unambiguous and its application straightforward. It is shown how the extrapolation of asymptotic series can be reformulated as forecasting for time series. The probability measure is introduced characterizing the ensemble of forecasted scenarios. The way of choosing the complete family ...
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)
A simple extrapolation of thermodynamic perturbation theory to infinite order
Ghobadi, Ahmadreza F.; Elliott, J. Richard
2015-09-01
Recent analyses of the third and fourth order perturbation contributions to the equations of state for square well spheres and Lennard-Jones chains show trends that persist across orders and molecular models. In particular, the ratio between orders (e.g., A3/A2, where Ai is the ith order perturbation contribution) exhibits a peak when plotted with respect to density. The trend resembles a Gaussian curve with the peak near the critical density. This observation can form the basis for a simple recursion and extrapolation from the highest available order to infinite order. The resulting extrapolation is analytic and therefore cannot fully characterize the critical region, but it remarkably improves accuracy, especially for the binodal curve. Whereas a second order theory is typically accurate for the binodal at temperatures within 90% of the critical temperature, the extrapolated result is accurate to within 99% of the critical temperature. In addition to square well spheres and Lennard-Jones chains, we demonstrate how the method can be applied semi-empirically to the Perturbed Chain - Statistical Associating Fluid Theory (PC-SAFT).
Effective Orthorhombic Anisotropic Models for Wave field Extrapolation
Ibanez Jacome, Wilson
2013-05-01
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.
Chiral extrapolations for nucleon electric charge radii
Hall, J M M; Young, R D
2013-01-01
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...
Local Map Extrapolation in Dynamic Environments
Drouilly, Romain; Papadakis, Panagiotis; Rives, Patrick; Morisset, Benoit
2014-01-01
We present a generative approach to perform robot mapping that is based on an intelligent integration of static and dynamic entity classes within an environment, in order to extrap-olate map information at various resolutions. Our framework differentiates from the conventional standpoint where different mapping levels are overlaid on one another, by fusing information from different mapping levels that allows us to infer new information within partially mapped environments. Towards this goal,...
Chiral extrapolation of nucleon magnetic form factors
Wang, P.; Leinweber, D. B.; Thomas, A.W.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, The University of Adelaide, Australia); Young, R.D.(ARC Centre of Excellence for Particle Physics at the Terascale, CSSM, School of Chemistry and Physics, University of Adelaide, Adelaide, SA, 5005, Australia)
2007-01-01
The extrapolation of nucleon magnetic form factors calculated within lattice QCD is investigated within a framework based upon heavy baryon chiral effective-field theory. All one-loop graphs are considered at arbitrary momentum transfer and all octet and decuplet baryons are included in the intermediate states. Finite range regularisation is applied to improve the convergence in the quark-mass expansion. At each value of the momentum transfer ($Q^2$), a separate extrapolatio...
Universality of Mixed Action Extrapolation Formulae
Chen, Jiunn-Wei; O'Connell, Donal; Walker-Loud, Andre
2007-01-01
Mixed action theories with chirally symmetric valence fermions exhibit very desirable features both at the level of the lattice calculations as well as in the construction and implementation of the low energy mixed action effective field theory. In this work we show that when such a mixed action effective field theory is projected onto the valence sector, both the Lagrangian and the extrapolation formulae become universal in form through next to leading order, for all varian...
Knowledge-based antenna pattern extrapolation
Robinson, Michael
2012-01-01
We describe a theoretically-motivated algorithm for extrapolation of antenna radiation patterns from a small number of measurements. This algorithm exploits constraints on the antenna's underlying design to avoid ambiguities, but is sufficiently general to address many different antenna types. A theoretical basis for the robustness of this algorithm is developed, and its performance is verified in simulation using a number of popular antenna designs.
Ardekani, Mohammad Ali; Nafisi, Vahid Reza; Farhani, Foad
2012-01-01
Hot-wire spirometer is a kind of constant temperature anemometer (CTA). The working principle of CTA, used for the measurement of fluid velocity and flow turbulence, is based on convective heat transfer from a hot-wire sensor to a fluid being measured. The calibration curve of a CTA is nonlinear and cannot be easily extrapolated beyond its calibration range. Therefore, a method for extrapolation of CTA calibration curve will be of great practical application. In this paper, a novel approach b...
Extrapolation procedure for low-temperature series for the square lattice spin-1 Ising model
Jensen, I; Guttmann, A J
1996-01-01
The finite-lattice method of series expansions has been combined with a new extrapolation procedure to extend the low-temperature series for the specific heat, spontaneous magnetisation and susceptibility of the spin-1 Ising model on the square lattice. The extended series were derived by directly calculating the series to order 99 (in the variable $u=\\exp[-J/k_B T])$ and using the new extrapolation procedure to calculate an additional 13--14 terms.
Chiral and Continuum Extrapolation of Partially-Quenched Hadron Masses
Allton, C R; Leinweber, D B; Thomas, A W; Young, R D
2005-01-01
Using the finite-range regularisation (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-analyse 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_rho from the former approach. These results are extended to the case of the nucleon mass.
International Nuclear Information System (INIS)
A virial equation was used for approximation of experimental molar volumes at high and low pressures for experimental temperatures. It was shown that the virial equation can be used for wide pressure and temperature intervals in distinction of the Tait, logarithm and other equations. The obtained under fitting of experimental data virial parameters were used for their following extrapolations on wide temperature intervals. The direct solution of the third order linear virial equations relative to molar volumes using the Kardano or Newton methods was employed for extrapolation of experimental dependences from high pressure to low pressure and from low pressure to high and superhigh pressures. A quite good agreement between experimental values of molar volumes versus pressures and extrapolating ones allows one to conclude that for a definite temperature interval with high probability and proof it is possible to make extrapolations on superhigh pressures
International Nuclear Information System (INIS)
90Sr+90Y clinical applicators are used for brachytherapy in Brazilian clinics even though they are not manufactured anymore. Such sources must be calibrated periodically, and one of the calibration methods in use is ionometry with extrapolation ionization chambers. 90Sr+90Y clinical applicators were calibrated using an extrapolation minichamber developed at the Calibration Laboratory at IPEN. The obtained results agree satisfactorily with the data provided in calibration certificates of the sources. - Highlights: • 90Sr+90Y clinical applicators were calibrated using a mini-extrapolation chamber. • An extrapolation curve was obtained for each applicator during its calibration. • The results were compared with those provided by the calibration certificates. • All results of the dermatological applicators presented lower differences than 5%
The extrapolation of creep rupture data by PD6605 - An independent case study
Energy Technology Data Exchange (ETDEWEB)
Bolton, J., E-mail: john.bolton@uwclub.net [65 Fisher Avenue, Rugby, Warks CV22 5HW (United Kingdom)
2011-04-15
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.
Extrapolation of Extreme Response for Wind Turbines based on FieldMeasurements
DEFF Research Database (Denmark)
Toft, Henrik Stensgaard; SØrensen, John Dalsgaard
2009-01-01
The characteristic loads on wind turbines during operation are among others dependent on the mean wind speed, the turbulence intensity and the type and settings of the control system. These parameters must be taken into account in the assessment of the characteristic load. The characteristic load is normally determined by statistical extrapolation of the simulated response during operation according to IEC 61400-1 2005. However, this method assumes that the individual 10 min. time series are independent and that peaks extracted are independent. In the present paper two new methods for loads extrapolation are presented. The first method is based on the same assumptions as the existing method but the statistical extrapolation is only performed for a limited number of mean wind speeds where the extreme load is likely to occur. For the second method the mean wind speeds are divided into storms which are assumed independent and the characteristic loads are determined from the extreme load in each storm.
On extrapolation blowups in the scale
Directory of Open Access Journals (Sweden)
Fiorenza Alberto
2006-01-01
Full Text Available Yano's extrapolation theorem dated back to 1951 establishes boundedness properties of a subadditive operator acting continuously in for close to and/or taking into as and/or with norms blowing up at speed and/or , . Here we give answers in terms of Zygmund, Lorentz-Zygmund and small Lebesgue spaces to what happens if as . The study has been motivated by current investigations of convolution maximal functions in stochastic analysis, where the problem occurs for . We also touch the problem of comparison of results in various scales of spaces.
Smooth extrapolation of unknown anatomy via statistical shape models
Grupp, R. B.; Chiang, H.; Otake, Y.; Murphy, R. J.; Gordon, C. R.; Armand, M.; Taylor, R. H.
2015-03-01
Several methods to perform extrapolation of unknown anatomy were evaluated. The primary application is to enhance surgical procedures that may use partial medical images or medical images of incomplete anatomy. Le Fort-based, face-jaw-teeth transplant is one such procedure. From CT data of 36 skulls and 21 mandibles separate Statistical Shape Models of the anatomical surfaces were created. Using the Statistical Shape Models, incomplete surfaces were projected to obtain complete surface estimates. The surface estimates exhibit non-zero error in regions where the true surface is known; it is desirable to keep the true surface and seamlessly merge the estimated unknown surface. Existing extrapolation techniques produce non-smooth transitions from the true surface to the estimated surface, resulting in additional error and a less aesthetically pleasing result. The three extrapolation techniques evaluated were: copying and pasting of the surface estimate (non-smooth baseline), a feathering between the patient surface and surface estimate, and an estimate generated via a Thin Plate Spline trained from displacements between the surface estimate and corresponding vertices of the known patient surface. Feathering and Thin Plate Spline approaches both yielded smooth transitions. However, feathering corrupted known vertex values. Leave-one-out analyses were conducted, with 5% to 50% of known anatomy removed from the left-out patient and estimated via the proposed approaches. The Thin Plate Spline approach yielded smaller errors than the other two approaches, with an average vertex error improvement of 1.46 mm and 1.38 mm for the skull and mandible respectively, over the baseline approach.
Experiences and extrapolations from Hiroshima and Nagasaki
International Nuclear Information System (INIS)
This paper examines the events following the atomic bombings of Hiroshima and Nagasaki in 1945 and extrapolates from these experiences to further understand the possible consequences of detonations on a local area from weapons in the current world nuclear arsenal. The first section deals with a report of the events that occurred in Hiroshima and Nagasaki just after the 1945 bombings with respect to the physical conditions of the affected areas, the immediate effects on humans, the psychological response of the victims, and the nature of outside assistance. Because there can be no experimental data to validate the effects on cities and their populations of detonations from current weapons, the data from the actual explosions on Hiroshima and Nagasaki provide a point of departure. The second section examines possible extrapolations from and comparisons with the Hiroshima and Nagasaki experiences. The limitations of drawing upon the Hiroshima and Nagasaki experiences are discussed. A comparison is made of the scale of effects from other major disasters for urban systems, such as damages from the conventional bombings of cities during World War II, the consequences of major earthquakes, the historical effects of the Black Plague and widespread famines, and other extreme natural events. The potential effects of detonating a modern 1 MT warhead on the city of Hiroshima as it exists today are simulated. This is extended to the local effects on a targeted city from a global nuclear war, and attention is directed to problems of estimating the societal effects from such a war
Calculating excitation energies by extrapolation along adiabatic connections
Rebolini, Elisa; Teale, Andrew M; Helgaker, Trygve; Savin, Andreas
2015-01-01
In this paper, an alternative method to range-separated linear-response time-dependent density-functional theory and perturbation theory is proposed to improve the estimation of the energies of a physical system from the energies of a partially interacting system. Starting from the analysis of the Taylor expansion of the energies of the partially interacting system around the physical system, we use an extrapolation scheme to improve the estimation of the energies of the physical system at an intermediate point of the range-separated or linear adiabatic connection where either the electron--electron interaction is scaled or only the long-range part of the Coulomb interaction is included. The extrapolation scheme is first applied to the range-separated energies of the helium and beryllium atoms and of the hydrogen molecule at its equilibrium and stretched geometries. It improves significantly the convergence rate of the energies toward their exact limit with respect to the range-separation parameter. The range...
Extrapolating W -associated jet-production ratios at the LHC
Bern, Z.; Dixon, L. J.; Febres Cordero, F.; Höche, S.; Ita, H.; Kosower, D. A.; Maître, D.
2015-07-01
Electroweak vector-boson production, accompanied by multiple jets, is an important background to searches for physics beyond the standard model. A precise and quantitative understanding of this process is helpful in constraining deviations from known physics. We study four key ratios in W +n -jet production at the LHC. We compute the ratio of cross sections for W +n - to W +(n -1 )-jet production as a function of the minimum jet transverse momentum. We also study the ratio differentially, as a function of the W -boson transverse momentum; as a function of the scalar sum of the jet transverse energy, HTjets; and as a function of certain jet transverse momenta. We show how to use such ratios to extrapolate differential cross sections to W +6 -jet production at next-to-leading order, and we cross-check the method against a direct calculation at leading order. We predict the differential distribution in HTjets for W +6 jets at next-to-leading order using such an extrapolation. We use the BlackHat software library together with SHERPA to perform the computations.
Scintillation counting: an extrapolation into the future
International Nuclear Information System (INIS)
Progress in scintillation counting is intimately related to advances in a variety of other disciplines such as photochemistry, photophysics, and instrumentation. And while there is steady progress in the understanding of luminescent phenomena, there is a virtual explosion in the application of semiconductor technology to detectors, counting systems, and data processing. The exponential growth of this technology has had, and will continue to have, a profound effect on the art of scintillation spectroscopy. This paper will review key events in technology that have had an impact on the development of scintillation science (solid and liquid) and will attempt to extrapolate future directions based on existing and projected capability in associated fields. Along the way there have been occasional pitfalls and several false starts; these too will be discussed as a reminder that if you want the future to be different than the past, study the past
Nuclear lattice simulations using symmetry-sign extrapolation
Lähde, Timo A.; Luu, Thomas; Lee, Dean; Meißner, Ulf-G.; Epelbaum, Evgeny; Krebs, Hermann; Rupak, Gautam
2015-07-01
Projection Monte Carlo calculations of lattice Chiral Effective Field Theory suffer from sign oscillations to a varying degree dependent on the number of protons and neutrons. Hence, such studies have hitherto been concentrated on nuclei with equal numbers of protons and neutrons, and especially on the alpha nuclei where the sign oscillations are smallest. Here, we introduce the "symmetry-sign extrapolation" method, which allows us to use the approximate Wigner SU(4) symmetry of the nuclear interaction to systematically extend the Projection Monte Carlo calculations to nuclear systems where the sign problem is severe. We benchmark this method by calculating the ground-state energies of the 12C, 6He and 6Be nuclei, and discuss its potential for studies of neutron-rich halo nuclei and asymmetric nuclear matter.
Nuclear lattice simulations using symmetry-sign extrapolation
International Nuclear Information System (INIS)
Projection Monte Carlo calculations of lattice Chiral Effective Field Theory suffer from sign oscillations to a varying degree dependent on the number of protons and neutrons. Hence, such studies have hitherto been concentrated on nuclei with equal numbers of protons and neutrons, and especially on the alpha nuclei where the sign oscillations are smallest. Here, we introduce the ''symmetry-sign extrapolation'' method, which allows us to use the approximate Wigner SU(4) symmetry of the nuclear interaction to systematically extend the Projection Monte Carlo calculations to nuclear systems where the sign problem is severe. We benchmark this method by calculating the ground-state energies of the 12C, 6He and 6Be nuclei, and discuss its potential for studies of neutron-rich halo nuclei and asymmetric nuclear matter. (orig.)
Mendelson, A.; Manson, S. S.
1960-01-01
A method using finite-difference recurrence relations is presented for direct extrapolation of families of curves. The method is illustrated by applications to creep-rupture data for several materials and it is shown that good results can be obtained without the necessity for any of the usual parameter concepts.
Increased identification of veterinary pharmaceutical contaminants in aquatic environments has raised concerns regarding potential adverse effects of these chemicals on non-target organisms. The purpose of this work was to develop a method for predictive species extrapolation ut...
Extrapolating gravitational-wave data from numerical simulations
Boyle, Michael; Mroué, Abdul H.
2009-01-01
Two complementary techniques are developed for obtaining the asymptotic form of gravitational-wave data at large radii from numerical simulations, in the form of easily implemented algorithms. It is shown that, without extrapolation, near-field effects produce errors in extracted waveforms that can significantly affect LIGO data analysis. The extrapolation techniques are discussed in the context of Newman--Penrose data applied to extrapolation of waveforms from an equal-mass...
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
Faugeras, Blaise; Blum, Jacques; Boulbe, Cédric; Moreau, Philippe; Nardon, Eric
2014-01-01
We present a method based on the use of toroidal harmonics and on a modelization of the poloidal field coils and divertor coils for the 2D interpolation and extrapolation of discrete magnetic measurements in a Tokamak. The method is generic and can be used to provide Cauchy boundary conditions needed as input by a fixed domain equilibrium reconstruction code like Equinox. It can also be used to extrapolate the magnetic measurements in order to compute the plasma boundary itself. The proposed ...
Nuclear Lattice Simulations using Symmetry-Sign Extrapolation
Lähde, Timo A; Lee, Dean; Meißner, Ulf-G; Epelbaum, Evgeny; Krebs, Hermann; Rupak, Gautam
2015-01-01
Projection Monte Carlo calculations of lattice Chiral Effective Field Theory suffer from sign oscillations to a varying degree dependent on the number of protons and neutrons. Hence, such studies have hitherto been concentrated on nuclei with equal numbers of protons and neutrons, and especially on the alpha nuclei where the sign oscillations are smallest. We now introduce the technique of "symmetry-sign extrapolation" which allows us to use the approximate Wigner SU(4) symmetry of the nuclear interaction to control the sign oscillations without introducing unknown systematic errors. We benchmark this method by calculating the ground-state energies of the $^{12}$C, $^6$He and $^6$Be nuclei, and discuss its potential for studies of neutron-rich halo nuclei and asymmetric nuclear matter.
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 (panti p) option in the CERN LEP tunnel. Based on our current knowledge of hard collisions at the present CERN panti 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 Esub(cm) = 10-20 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, Wsup(+-) 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. (orig.)
Ultraviolet extrapolations in finite oscillator bases
König, S; Furnstahl, R J; More, S N; Papenbrock, T
2014-01-01
The use of finite harmonic oscillator spaces in many-body calculations introduces both infrared (IR) and ultraviolet (UV) errors. The IR effects are well approximated by imposing a hard-wall boundary condition at a properly identified radius L_eff. We show that duality of the oscillator implies that the UV effects are equally well described by imposing a sharp momentum cutoff at a momentum Lambda_eff complementary to L_eff. By considering two-body systems with separable potentials, we show that the UV energy corrections depend on details of the potential, in contrast to the IR energy corrections, which depend only on the S-matrix. An adaptation of the separable treatment to more general interactions is developed and applied to model potentials as well as to the deuteron with realistic potentials. The previous success with a simple phenomenological form for the UV error is also explained. Possibilities for controlled extrapolations for A > 2 based on scaling arguments are discussed.
Latychevskaia, Tatiana
2015-01-01
In coherent diffractive imaging (CDI) the resolution with which the reconstructed object can be obtained is limited by the numerical aperture of the experimental setup. We present here a theoretical and numerical study for achieving super-resolution by post-extrapolation of coherent diffraction images, such as diffraction patterns or holograms. We proof that a diffraction pattern can unambiguously be extrapolated from just a fraction of the entire pattern and that the ratio of the extrapolated signal to the originally available signal, is linearly proportional to the oversampling ratio. While there could be in principle other methods to achieve extrapolation, we devote our discussion to employing phase retrieval methods and demonstrate their limits. We present two numerical studies; namely the extrapolation of diffraction patterns of non-binary and that of phase objects together with a discussion of the optimal extrapolation procedure.
A physically based methodology to extrapolate performance maps of radial turbines
International Nuclear Information System (INIS)
Highlights: ? Physical based methodology to extrapolate radial turbine efficiency measured data. ? Equation relating efficiency versus blade to speed ratio (?) have been developed. ? Developed efficiency equation takes into account turbine mass flow parameter. ? Efficiency versus ? at constant pressure ratio is discussed, also at constant speed. ? The methodology has been validated with a broad range of experimental results. - Abstract: This paper details a physically based methodology to perform an extrapolation of the radial turbine performance maps, both mass flow characteristics and the efficiency curve. This method takes into account a narrow range of experimental data, which is usually the data available when such turbines are part of a turbocharger. Therefore, the extrapolation methodology is especially useful when data from third parties are being used or when the compressor of a turbocharger is used as the turbine brake in a gas stand. The nozzle equation is used to develop an interpolation and extrapolation of the mass flow rate trough the turbine. Then, specific information is extracted from this extrapolation and is fed into a total-to-static efficiency equation to carry out an extension of the efficiency curve. This equation is developed using the definition of the total-to-static efficiency, velocity triangles and thermodynamic and fluid fundamental equations. This procedure has been applied to five radial turbines of different sizes and types. Results are compared against experimental information available in the literature or provided by the turbine manufacturers and a good agreement has been found between theoretical and experimentally estimated data.
Calculation of the extrapolation length in shifting control elements within the control channel
International Nuclear Information System (INIS)
On the basis of a one-group model a method is presented for calculating the extrapolation length at the surface of a cylindrical control channel when the axis of the control organ is shifted against the axis of the control channel. In comparison to the central position a correction of the extrapolation length is obtained in first-order approximation, which depends on the angle at the circumference of the control channel and is proportional to the deflection of the control organ. (author)
Herzberg, Frederik S
2005-01-01
A number of Bermudan option pricing methods that are applicable to options on multiple assets are studied in this thesis, one of the dominating questions being the natural scaling needed to extrapolate from Bermudan to American (both approximate and ``exact'') option prices.
Quark Mass Dependence of Nucleon Properties and Extrapolation from Lattice QCD
Hemmert, Thomas R.; Procura, Massimiliano; Weise, Wolfram(Physik Department, Technische Universität München, Garching, D-85747, Germany)
2003-01-01
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.
Extrapolation of the T(dn)4 He reaction cross section into E = 0
International Nuclear Information System (INIS)
Method of threshold theory was used to continue the analysis of experimental data on T(dn)4 He reaction cross section in deuteron energy range Ed = (8 - 16) keV. Resonance parameters were determined and reaction cross section was extrapolated into Ed = 0 region. 16 refs., 2 tabs
Chiral extrapolation and determination of low-energy constants from lattice data
Ecker, Gerhard; Masjuan, Pere; Neufeld, Helmut
2010-01-01
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.
Iacovella, Christopher R.; Rogers, Reginald R.; Glotzer, Sharon C; Solomon, Michael J.
2010-01-01
A method for measuring the pair interaction potential between colloidal particles by extrapolation measurement of collective structure to infinite dilution is presented and explored using simulation and experiment. The method is particularly well suited to systems in which the colloid is fluorescent and refractive index matched with the solvent. The method involves characterizing the potential of mean force between colloidal particles in suspension by measurement of the radi...
Latychevskaia, Tatiana; Chushkin, Yuriy; Zontone, Federico; Fink, Hans-Werner
2015-01-01
Coherent X-ray diffraction imaging is a promising high-resolution imaging technique whose potential can be greatly enhanced by applying the extrapolation method presented here. We demonstrate enhancement in resolution of a noncrystalline object reconstructed from an experimental X-ray diffraction pattern by extrapolating the measured diffraction intensities beyond the detector area. The experimental record contains about 10% missing information, including the pixels in the c...
Limitations of force-free magnetic field extrapolations: Revisiting basic assumptions
Peter, H.; Warnecke, J.; Chitta, L. P.; Cameron, R. H.
2015-12-01
Context. Force-free extrapolations are widely used to study the magnetic field in the solar corona based on surface measurements. Aims: The extrapolations assume that the ratio of internal energy of the plasma to magnetic energy, the plasma ?, is negligible. Despite the widespread use of this assumption observations, models, and theoretical considerations show that ? is of the order of a few percent to more than 10%, and thus not small. We investigate what consequences this has for the reliability of extrapolation results. Methods: We use basic concepts starting with force and energy balance to infer relations between plasma ? and free magnetic energy to study the direction of currents in the corona with respect to the magnetic field, and to estimate the errors in the free magnetic energy by neglecting effects of the plasma (? ? 1). A comparison with a 3D magneto-hydrodynamics (MHD) model supports our basic considerations. Results: If plasma ? is of the order of the relative free energy (the ratio of the free magnetic energy to the total magnetic energy) then the pressure gradient can balance the Lorentz force. This is the case in solar corona, and therefore the currents are not properly described. In particular, the error in terms of magnetic energy by neglecting the plasma is of the order of the free magnetic energy, so that the latter cannot be reliably determined by an extrapolation. Conclusions: While a force-free extrapolation might capture the magnetic structure and connectivity of the coronal magnetic field, the derived currents and free magnetic energy are not reliable. Thus quantitative results of extrapolations on the location and amount of heating in the corona (through current dissipation) and on the energy storage of the magnetic field (e.g. for eruptive events) are limited.
Extrapolation and phase correction of non-uniformly broadened signals
Rodts, Stéphane; Bytchenkoff, Dimitri
2013-08-01
The initial part of FID-signals cannot always be acquired experimentally. This is particularly true for signals characterised by strong inhomogeneous broadening, such as those in porous materials, e.g. cements, soils and rocks, those measured by portable NMR-apparatus, or EPR-signals. Here we report on a numerical method we designed to extrapolate those initial missing parts, i.e. to retrieve their amplitude and phase. Should the entire signal be available from an experiment, the algorithm can still be used as an automatic phase-corrector and a low-pass filter. The method is based on the use of cardinal series, applies to any oversampled signals and requires no prior knowledge of the system under study. We show that the method can also be used to restore entire one-dimensional MRI-data sets from those in which less than half of the k-space was sampled, thus not only potentially allowing to speed up data acquisition - when extended to two or three dimensions, but also to circumvent phase-distortions usually encountered when exploring the k-space near its origin.
Revealing individual differences in strategy selection through visual motion extrapolation.
Fulvio, Jacqueline M; Maloney, Laurence T; Schrater, Paul R
2015-12-01
Humans are constantly challenged to make use of internal models to fill in missing sensory information. We measured human performance in a simple motion extrapolation task where no feedback was provided in order to elucidate the models of object motion incorporated into observers' extrapolation strategies. There was no "right" model for extrapolation in this task. Observers consistently adopted one of two models, linear or quadratic, but different observers chose different models. We further demonstrate that differences in motion sensitivity impact the choice of internal models for many observers. These results demonstrate that internal models and individual differences in those models can be elicited by unconstrained, predictive-based psychophysical tasks. PMID:25654543
Source-receiver two-way wave extrapolation for prestack exploding-reflector modelling and migration
Alkhalifah, Tariq Ali
2014-10-08
Most modern seismic imaging methods separate input data into parts (shot gathers). We develop a formulation that is able to incorporate all available data at once while numerically propagating the recorded multidimensional wavefield forward or backward in time. This approach has the potential for generating accurate images free of artiefacts associated with conventional approaches. We derive novel high-order partial differential equations in the source-receiver time domain. The fourth-order nature of the extrapolation in time leads to four solutions, two of which correspond to the incoming and outgoing P-waves and reduce to the zero-offset exploding-reflector solutions when the source coincides with the receiver. A challenge for implementing two-way time extrapolation is an essential singularity for horizontally travelling waves. This singularity can be avoided by limiting the range of wavenumbers treated in a spectral-based extrapolation. Using spectral methods based on the low-rank approximation of the propagation symbol, we extrapolate only the desired solutions in an accurate and efficient manner with reduced dispersion artiefacts. Applications to synthetic data demonstrate the accuracy of the new prestack modelling and migration approach.
Directory of Open Access Journals (Sweden)
Joana Aurora Braun Chagas
2010-02-01
Full Text Available 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 de 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.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. After 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.
Scientific Electronic Library Online (English)
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.
2010-02-01
Full Text Available 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.
Amir, Sahar Z.
2013-05-01
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.
Montiel, Ariadna(Departamento de Física, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 14-740, México, DF, 07000, Mexico); Lazkoz, Ruth(Departamento de Física Teórica e Historia de la Ciencia, Universidad del País Vasco (UPV/EHU), Apdo. 644, Bilbao, E-48080, Spain); Sendra, Irene; Escamilla-Rivera, Celia; SALZANO, VINCENZO
2014-01-01
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 ...
Variational procedure for nuclear shell-model calculations and energy-variance extrapolation
Shimizu, Noritaka; Utsuno, Yutaka; Mizusaki, Takahiro; Honma, Michio; Tsunoda, Yusuke; Otsuka, Takaharu
2012-01-01
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 gener...
Zero-dose extrapolation as part of macromolecular synchrotron data reduction
Diederichs, Kay; McSweeney, Sean (Irish painter, b. 1935); Ravelli, Raimond B G
2003-01-01
Radiation damage to macromolecular crystals at third-generation synchrotron sites constitutes a major source of systematic error in X-ray data collection. Here, a computational method to partially correct the observed intensities during data reduction is described and investigated. The method consists of a redundancy-based zero-dose extrapolation of a decay function that is fitted to the intensities of all observations of a unique reflection as a function of dose. It is shown in a test case w...
Chiral Extrapolation: An Analogy with Effective Field Theory
Dunne, Gerald V.; Anthony W. Thomas; Wright, Stewart V.
2001-01-01
We draw an analogy between the chiral extrapolation of lattice QCD calculations from large to small quark masses and the interpolation between the large mass (weak field) and small mass (strong field) limits of the Euler--Heisenberg QED effective action. In the latter case, where the exact answer is known, a simple extrapolation of a form analogous to those proposed for the QCD applications is shown to be surprisingly accurate over the entire parameter range.
Bayesian estimation of medium properties in wavefield downward extrapolation problems
Pitas, I.; Venetsanopoulos, A.N.
2010-01-01
When acoustic waves are used for nondestructive imaging of the interior of objects such as the Earth the human body, etc., the wavefield measurements recorded on the surface of the object are extrapolated according to the wave equation to give an image of the object. The extrapolation propagates backward the noise present in the measurements, so that the quality of the final image is degraded, unless statistical restoration techniques are used. Another source of degradation of the image is th...
Application of Curve Fitting Extrapolation in Measuring Transient Surface Temperature
Xiaojian Hao; Lina Hao; Hanchang Zhou; Sanping Jiang; Yanfeng Li
2013-01-01
The engine inner wall surface temperature was measured by the plug blind-hole extrapolation, and multiple thermocouples were installed at different depths in the substrate. The engine wall extrapolation model of transient high temperature was established according to the basic principles of heat transfer. The transient temperatures were measured by thermocouples buried at different depths of the engine wall and fitting curve was got. The transient temperature field which was generated by the ...
Chiral extrapolation beyond the power-counting regime
Hall, J. M. M.; Lee, F.X.; Leinweber, D. B.; Liu, K. F.; Mathur, N.; Young, R.D.(ARC Centre of Excellence for Particle Physics at the Terascale, CSSM, School of Chemistry and Physics, University of Adelaide, Adelaide, SA, 5005, Australia); Zhang, J.B.
2011-01-01
Chiral effective field theory can provide valuable insight into the chiral physics of hadrons when used in conjunction with non-perturbative schemes such as lattice QCD. In this discourse, the attention is focused on extrapolating the mass of the rho meson to the physical pion mass in quenched QCD (QQCD). With the absence of a known experimental value, this serves to demonstrate the ability of the extrapolation scheme to make predictions without prior bias. By using extended...
Convergence and stability properties of minimal polynomial and reduced rank extrapolation algorithms
Sidi, A.
1983-01-01
The minimal polynomial and reduced rank extrapolation algorithms are two acceleration of convergence methods for sequences of vectors. In a recent survey these methods were tested and compared with the scalar, vector, topological epsilon algorithms, and were observed to be more efficient than the latter. It was also observed that the two methods have similar convergence properties. The convergence and stability properties of these methods are analyzed and the performance of the acceleration methods when applied to a class of vector sequences that includes those sequences obtained from systems of linear equations by using matrix iterative methods is discussed.
Extrapolation of lattice gauge theories to the continuum limit
International Nuclear Information System (INIS)
The problem of extrapolating lattice gauge theories from the strong-coupling phase to the continuum critical point is studied for the Abelian (U(1)) and non-Abelian (SU(2)) theories in three (space--time) dimensions. A method is described for obtaining the asymptotic behavior, for large ?, of such thermodynamic quantities and correlation functions as the free energy and Wilson loop function. Certain general analyticity and positivity properties (in the complex ?-plane) are shown to lead, after appropriate analytic remappings, to a Stieltjes property of these functions. Rigorous theorems then guarantee uniform and monotone convergence of the Pade approximants, with exact pointwise upper and lower bounds. The first three Pade's are computed for both the free energy and the Wilson function. For the free energy, satisfactory agreement is with the asymptotic behavior computed by an explicit lattice calculation. The strong-coupling series for the Wilson function is found to be considerably more unstable in the lower order terms - correspondingly, convergence of the Pade's is found to be slower than in the free-energy case. It is suggested that higher-order calculations may allow a reasonably accurate determination of the string constant for the SU(2) theory. 14 references
Interspecies Gene Name Extrapolation—A New Approach
Petric, Roxana Cojocneanu; Braicu, Cornelia; Bassi, Cristian; Pop, Laura; Taranu, Ionelia; Dragos, Nicolae; Dumitrascu, Dan
2015-01-01
The use of animal models has facilitated numerous scientific developments, especially when employing “omics” technologies to study the effects of various environmental factors on humans. Our study presents a new bioinformatics pipeline suitable when the generated microarray data from animal models does not contain the necessary human gene name annotation. We conducted single color gene expression microarray on duodenum and spleen tissue obtained from pigs which have been exposed to zearalenone and Escherichia coli contamination, either alone or combined. By performing a combination of file format modifications and data alignments using various online tools as well as a command line environment, we performed the pig to human gene name extrapolation with an average yield of 58.34%, compared to 3.64% when applying more simple methods. In conclusion, while online data analysis portals on their own are of great importance in data management and assessment, our new pipeline provided a more effective approach for a situation which can be frequently encountered by researchers in the “omics” era. PMID:26407293
Spackman, Peter R.; Karton, Amir
2015-05-01
Coupled cluster calculations with all single and double excitations (CCSD) converge exceedingly slowly with the size of the one-particle basis set. We assess the performance of a number of approaches for obtaining CCSD correlation energies close to the complete basis-set limit in conjunction with relatively small DZ and TZ basis sets. These include global and system-dependent extrapolations based on the A + B/L? two-point extrapolation formula, and the well-known additivity approach that uses an MP2-based basis-set-correction term. We show that the basis set convergence rate can change dramatically between different systems(e.g.it is slower for molecules with polar bonds and/or second-row elements). The system-dependent basis-set extrapolation scheme, in which unique basis-set extrapolation exponents for each system are obtained from lower-cost MP2 calculations, significantly accelerates the basis-set convergence relative to the global extrapolations. Nevertheless, we find that the simple MP2-based basis-set additivity scheme outperforms the extrapolation approaches. For example, the following root-mean-squared deviations are obtained for the 140 basis-set limit CCSD atomization energies in the W4-11 database: 9.1 (global extrapolation), 3.7 (system-dependent extrapolation), and 2.4 (additivity scheme) kJ mol-1. The CCSD energy in these approximations is obtained from basis sets of up to TZ quality and the latter two approaches require additional MP2 calculations with basis sets of up to QZ quality. We also assess the performance of the basis-set extrapolations and additivity schemes for a set of 20 basis-set limit CCSD atomization energies of larger molecules including amino acids, DNA/RNA bases, aromatic compounds, and platonic hydrocarbon cages. We obtain the following RMSDs for the above methods: 10.2 (global extrapolation), 5.7 (system-dependent extrapolation), and 2.9 (additivity scheme) kJ mol-1.
Chiral extrapolations for nucleon magnetic moments
Hall, J. M. M.; Leinweber, D. B.; Young, R.D.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, University of Adelaide, Adelaide, SA 5005, Australia)
2012-01-01
Lattice 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 extr...
Variational procedure for nuclear shell-model calculations and energy-variance extrapolation
Shimizu, Noritaka; Mizusaki, Takahiro; Honma, Michio; Tsunoda, Yusuke; Otsuka, Takaharu
2012-01-01
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.
3D density inversion of gravity gradient data using the extrapolated Tikhonov regularization
Liu, Jin-Zhao; Liu, Lin-Tao; Liang, Xing-Hui; Ye, Zhou-Run
2015-06-01
We use the extrapolated Tikhonov regularization to deal with the ill-posed problem of 3D density inversion of gravity gradient data. The use of regularization parameters in the proposed method reduces the deviations between calculated and observed data. We also use the depth weighting function based on the eigenvector of gravity gradient tensor to eliminate undesired effects owing to the fast attenuation of the position function. Model data suggest that the extrapolated Tikhonov regularization in conjunction with the depth weighting function can effectively recover the 3D distribution of density anomalies. We conduct density inversion of gravity gradient data from the Australia Kauring test site and compare the inversion results with the published research results. The proposed inversion method can be used to obtain the 3D density distribution of underground anomalies.
Reduction of the resonance error in numerical homogenisation II: correctors and extrapolation
Gloria, Antoine; Habibi, Zakaria
2014-01-01
This paper is the companion article of [Gloria, M3AS, 21 (2011), No. 3, pp 1601-1630]. One common drawback among numerical homogenization methods is the presence of the so-called resonance error, which roughly speaking is a function of the ratio $\\frac{\\varepsilon}{\\rho}$, where $\\rho$ is a typical macroscopic lengthscale and $\\varepsilon$ is the typical size of the heterogeneities. In the present work, we make a systematic use of regularization and extrapolation to reduce t...
Extrapolation and interpolation of asymptotic series by self-similar approximants
V.I. Yukalov; Yukalova, E. P.; GLUZMAN, S
2010-01-01
The problem of extrapolation and interpolation of asymptotic series is considered. Several new variants of improving the accuracy of the self-similar approximants are suggested. The methods are illustrated by examples typical of chemical physics, when one is interested in finding the equation of state for a strongly interacting system. A special attention is payed to the study of the basic properties of fluctuating fluid membranes. It is shown that these properties can be we...
Extrapolation of Extreme Response for Wind Turbines based on FieldMeasurements
Toft, Henrik Stensgaard; Sørensen, John Dalsgaard
2009-01-01
The characteristic loads on wind turbines during operation are among others dependent on the mean wind speed, the turbulence intensity and the type and settings of the control system. These parameters must be taken into account in the assessment of the characteristic load. The characteristic load is normally determined by statistical extrapolation of the simulated response during operation according to IEC 61400-1 2005. However, this method assumes that the individual 10 min. time series are ...
Extrapolation of Extreme Response for Wind Turbines based on FieldMeasurements
DEFF Research Database (Denmark)
Toft, Henrik Stensgaard; Sørensen, John Dalsgaard
2009-01-01
The characteristic loads on wind turbines during operation are among others dependent on the mean wind speed, the turbulence intensity and the type and settings of the control system. These parameters must be taken into account in the assessment of the characteristic load. The characteristic load is normally determined by statistical extrapolation of the simulated response during operation according to IEC 61400-1 2005. However, this method assumes that the individual 10 min. time series are ind...
Boundary layers, Rellich estimates and extrapolation of solvability for elliptic systems
Auscher, Pascal, 1963-; Mourgoglou, Mihalis
2013-01-01
The purpose of this article is to study extrapolation of solvability for boundary value problems of elliptic systems in divergence form on the upper half-space assuming De Giorgi type conditions. We develop a method allowing to treat each boundary value problem independently of the others. We shall base our study on solvability for energy solutions, estimates for boundary layers, equivalence of certain boundary estimates with interior control so that solvability reduces to a...
Moraitis, Kostas; Archontis, Vasilis; Tziotziou, Konstantinos; Georgoulis, Manolis K.
We calculate the instantaneous free magnetic energy and relative magnetic helicity of solar active regions using two independent approaches: a) a non-linear force-free (NLFF) method that requires only a single photospheric vector magnetogram, and b) well known semi-analytical formulas that require the full three-dimensional (3D) magnetic field structure. The 3D field is obtained either from MHD simulations, or from observed magnetograms via respective NLFF field extrapolations. We find qualitative agreement between the two methods and, quantitatively, a discrepancy not exceeding a factor of 4. The comparison of the two methods reveals, as a byproduct, two independent tests for the quality of a given force-free field extrapolation. We find that not all extrapolations manage to achieve the force-free condition in a valid, divergence-free, magnetic configuration. This research has been co-financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: Thales. Investing in knowledge society through the European Social Fund.
Statistical atlas based extrapolation of CT data
Chintalapani, Gouthami; Murphy, Ryan; Armiger, Robert S.; Lepisto, Jyri; Otake, Yoshito; Sugano, Nobuhiko; Taylor, Russell H.; Armand, Mehran
2010-02-01
We present a framework to estimate the missing anatomical details from a partial CT scan with the help of statistical shape models. The motivating application is periacetabular osteotomy (PAO), a technique for treating developmental hip dysplasia, an abnormal condition of the hip socket that, if untreated, may lead to osteoarthritis. The common goals of PAO are to reduce pain, joint subluxation and improve contact pressure distribution by increasing the coverage of the femoral head by the hip socket. While current diagnosis and planning is based on radiological measurements, because of significant structural variations in dysplastic hips, a computer-assisted geometrical and biomechanical planning based on CT data is desirable to help the surgeon achieve optimal joint realignments. Most of the patients undergoing PAO are young females, hence it is usually desirable to minimize the radiation dose by scanning only the joint portion of the hip anatomy. These partial scans, however, do not provide enough information for biomechanical analysis due to missing iliac region. A statistical shape model of full pelvis anatomy is constructed from a database of CT scans. The partial volume is first aligned with the statistical atlas using an iterative affine registration, followed by a deformable registration step and the missing information is inferred from the atlas. The atlas inferences are further enhanced by the use of X-ray images of the patient, which are very common in an osteotomy procedure. The proposed method is validated with a leave-one-out analysis method. Osteotomy cuts are simulated and the effect of atlas predicted models on the actual procedure is evaluated.
Weights, Extrapolation and the Theory of Rubio de Francia
Cruz-Uribe, David; Perez, Carlos
2011-01-01
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
A study on extrapolation algorithm of percent depth dose
International Nuclear Information System (INIS)
A mathematical model of extrapolating percent depth dose (PDD) was presented according to the principle of interaction between X-ray and water. The difference of extrapolated PDD by the model and measured PDD by 3D radiation field analyzer is very small. For fields of different sizes within 20cm depth, the maximum absolute difference is 0.006 x 100% and the maximum relative difference is 1.1%. With the mathematical model, appropriate PDD values for different field sizes can be abstained without 3D radiation field analyses
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.
International Nuclear Information System (INIS)
Previously reported crystalline structures obtained by an iterative phase retrieval reconstruction of their diffraction patterns seem to be free from displaying any irregularities or defects in the lattice, which appears to be unrealistic. We demonstrate here that the structure of a nanocrystal including its atomic defects can unambiguously be recovered from its diffraction pattern alone by applying a direct phase retrieval procedure not relying on prior information of the object shape. Individual point defects in the atomic lattice are clearly apparent. Conventional phase retrieval routines assume isotropic scattering. We show that when dealing with electrons, the quantitatively correct transmission function of the sample cannot be retrieved due to anisotropic, strong forward scattering specific to electrons. We summarize the conditions for this phase retrieval method and show that the diffraction pattern can be extrapolated beyond the original record to even reveal formerly not visible Bragg peaks. Such extrapolated wave field pattern leads to enhanced spatial resolution in the reconstruction
Extrapolation and Local Acceleration of an Iterative Process for Common Fixed Point Problems
Cegielski, Andrzej
2012-01-01
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.
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
GPatt: Fast Multidimensional Pattern Extrapolation with Gaussian Processes
Wilson, Andrew Gordon; Gilboa, Elad; Nehorai, Arye; Cunningham, John P.
2013-01-01
Gaussian processes are typically used for smoothing and interpolation on small datasets. We introduce a new Bayesian nonparametric framework -- GPatt -- enabling automatic pattern extrapolation with Gaussian processes on large multidimensional datasets. GPatt unifies and extends highly expressive kernels and fast exact inference techniques. Without human intervention -- no hand crafting of kernel features, and no sophisticated initialisation procedures -- we show that GPatt ...
Energy-variance extrapolation for importance-truncated no-core and valence-space shell model
International Nuclear Information System (INIS)
The no-core shell model (NCSM) and valence-space shell model (SM) are successful tools for the description of the nuclear spectroscopy. Both methods are computationally demanding and are limited by the model-space dimensions. To extend the NCSM and SM to larger model spaces, we apply an importance-truncation (IT) scheme based on a perturbative importance measure reducing the model spaces to the relevant basis states for the description of one or a few target eigenstates. This IT scheme necessitates an extrapolation to vanishing importance measure. Since the dependence of the energies on the importance measure can be highly non-linear, the extrapolation can give rise to large uncertainties. We present a more sophisticated extrapolation technique based on the energy variance, which vanishes in the limit of the full model space. We demonstrate the efficiency of the IT-NCSM and IT-SM with energy-variance extrapolation for ground-state and excitation energies of p-shell nuclei (IT-NCSM) and pf-shell nuclei (IT-SM) by comparing the results to both, full and importance-truncated NCSM and SM calculations with the conventional threshold extrapolation.
SU-E-J-145: Geometric Uncertainty in CBCT Extrapolation for Head and Neck Adaptive Radiotherapy
International Nuclear Information System (INIS)
Purpose: One primary limitation of using CBCT images for H'N adaptive radiotherapy (ART) is the limited field of view (FOV) range. We propose a method to extrapolate the CBCT by using a deformed planning CT for the dose of the day calculations. The aim was to estimate the geometric uncertainty of our extrapolation method. Methods: Ten H'N patients, each with a planning CT (CT1) and a subsequent CT (CT2) taken, were selected. Furthermore, a small FOV CBCT (CT2short) was synthetically created by cropping CT2 to the size of a CBCT image. Then, an extrapolated CBCT (CBCTextrp) was generated by deformably registering CT1 to CT2short and resampling with a wider FOV (42mm more from the CT2short borders), where CT1 is deformed through translation, rigid, affine, and b-spline transformations in order. The geometric error is measured as the distance map ||DVF|| produced by a deformable registration between CBCTextrp and CT2. Mean errors were calculated as a function of the distance away from the CBCT borders. The quality of all the registrations was visually verified. Results: Results were collected based on the average numbers from 10 patients. The extrapolation error increased linearly as a function of the distance (at a rate of 0.7mm per 1 cm) away from the CBCT borders in the S/I direction. The errors (?±?) at the superior and inferior boarders were 0.8 ± 0.5mm and 3.0 ± 1.5mm respectively, and increased to 2.7 ± 2.2mm and 5.9 ± 1.9mm at 4.2cm away. The mean error within CBCT borders was 1.16 ± 0.54mm . The overall errors within 4.2cm error expansion were 2.0 ± 1.2mm (sup) and 4.5 ± 1.6mm (inf). Conclusion: The overall error in inf direction is larger due to more large unpredictable deformations in the chest. The error introduced by extrapolation is plan dependent. The mean error in the expanded region can be large, and must be considered during implementation. This work is supported in part by Varian Medical Systems, Palo Alto, CA
Directory of Open Access Journals (Sweden)
Bressler B
2015-06-01
Full Text Available Brian Bressler,1 Theo Dingermann2 1St Paul’s Hospital, University of British Columbia, Vancouver, BC, Canada; 2Institute of Pharmaceutical Biology, Frankfurt, Germany Abstract: Despite their enormous value for our health care system, biopharmaceuticals have become a serious threat to the system itself due to their high cost. Costs may be warranted if the medicine is new and innovative; however, it is no longer an innovation when its patent protection expires. As patents and exclusivities expire on biological drugs, biosimilar products defined as highly similar to reference biologics are being marketed. The goal of biosimilar development is to establish a high degree of biosimilarity, not to reestablish clinical efficacy and safety. Current sophisticated analytical methods allow the detection of even small changes in quality attributes and can therefore enable sensitive monitoring of the batch-to-batch consistency and variability of the manufacturing process. The European Medicines Agency (EMA, US Food and Drug Administration (FDA, and Health Canada have determined that a reduced number of nonclinical and clinical comparative studies can be sufficient for approval with clinical data from the most sensitive indication extrapolated to other indications. Extrapolation of data is a scientifically based principle, guided by specific criteria, and if approved by the EMA, FDA, and/or Health Canada is appropriate. Enablement of extrapolation of data is a core principle of biosimilar development, based on principles of comparability and necessary to fully realize cost savings for these drugs. Keywords: biosimilars, Inflectra, infliximab, pharmacoeconomics, Canada, Europe
Three dimensional image guided extrapolation for cone-beam CT image reconstruction
Nett, Brian
2014-03-01
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.
Chaouche, L Yelles; Pillet, V Martínez; Moreno-Insertis, F
2012-01-01
The 3D structure of an active region (AR) filament is studied using nonlinear force-free field (NLFFF) extrapolations based on simultaneous observations at a photospheric and a chromospheric height. To that end, we used the Si I 10827 \\AA\\ line and the He I 10830 \\AA\\ triplet obtained with the Tenerife Infrared Polarimeter (TIP) at the VTT (Tenerife). The two extrapolations have been carried out independently from each other and their respective spatial domains overlap in a considerable height range. This opens up new possibilities for diagnostics in addition to the usual ones obtained through a single extrapolation from, typically, a photospheric layer. Among those possibilities, this method allows the determination of an average formation height of the He I 10830 \\AA\\ signal of \\approx 2 Mm above the surface of the sun. It allows, as well, to cross-check the obtained 3D magnetic structures in view of verifying a possible deviation from the force- free condition especially at the photosphere. The extrapolati...
A variational principle for the Milne problem linear extrapolation length
International Nuclear Information System (INIS)
Highlights: • Bilinear functional F is both null and stationary at true flux and adjoint. • Null F gives best discrete mode amplitudes without differentiation. • Optimum amplitude ratio gotten as a solution to a simple quadratic. • All subcritical canonical lengths numerically matched to within 0.5%. - Abstract: A simple bilinear functional F is introduced on behalf of the Milne subcritical problem with replication parameter 0?c?1. This functional depends upon two arguments, respectively intended to be the neutron flux and its adjoint, and is stationary about the true solution pair where, in addition, it vanishes. The stationarity and null value can then be united as a basis for the demand that F continue to vanish even when flux and adjoint are both approximated by just the two modes from the discrete eigenvalue spectrum, a representation akin to what is known as the asymptotic portion of the neutron flux, and one which is clearly incapable of matching interface boundary conditions. The stationarity of F, however, renders it tolerant of such boundary defect, as a result of which one can expect the persisting null demand, F=0, to yield the best possible value for the ratio of the two discrete mode amplitudes. We go on to implement this program, and find as its outcome that the optimum amplitude ratio is determined as one preferred solution of a simple quadratic equation. With that solution in hand, it is an easy step then to a computation of the linear extrapolation length ?. We follow through with a numerical embodiment of these ideas, obtaining the discrete, real and positive eigenvalue ?0 on the run via a Newton–Raphson tangent encroachment root hunt. With sufficient start-up care the Newton–Raphson root hunt proves here to be exceedingly rapid, and it, together with the quadratic underpinning, provides for ? a string of values that differ by less than 0.5% from those found in the classic compendium on neutron transport from the pens of Case, de Hoffmann, and Placzek. In particular, we are able to bypass in this way, and with quite elementary tools indeed, a known canonical machinery of far greater weight and sophistication, be it based upon the Wiener–Hopf method, or else upon flux decomposition along both discrete and singular eigenfunction modes. To our way of thinking, such a simple alternative is aesthetically pleasing in its own right, and both provides a measure of confirmation to, and is itself checked by, the more formidable apparatus
A new design of beta ray extrapolation ion chamber
International Nuclear Information System (INIS)
In U.K. National Health Service Hospitals a widely used dosimeter system is the type 37C electrometer amplifier together with an air equivalent wall ionization chamber developed by Osborne at the time of the Adrian Committee survey of diagnostic X-ray doses. This paper describes the development and use of an extrapolation ion chamber which is interchangeable with Osborne's X-ray chamber and which, together with the type 37 electrometer amplifier, is suitable for the calibration of beta ray personnel dosimeters. A particular feature of this chamber is that the variable electrode separation is obtained by locating a spring loaded peg on a mechanical step wedge. This enables readings for a series of accurately known separations to be obtained very quickly, and the appropriate extrapolation dose to be deduced immediately. Evaluation work carried out on the new chamber, including measurements of beta depth dose distributions, is also reported
Survival extrapolation using the poly-Weibull model
Demiris, Nikolaos; Lunn, David; Sharples, Linda D.
2015-01-01
Recent studies of (cost-) effectiveness in cardiothoracic transplantation have required estimation of mean survival over the lifetime of the recipients. In order to calculate mean survival, the complete survivor curve is required but is often not fully observed, so that survival extrapolation is necessary. After transplantation, the hazard function is bathtub-shaped, reflecting latent competing risks which operate additively in overlapping time periods. The poly-Weibull distribution is a flex...
Delayed inhibition of an anticipatory action during motion extrapolation
Riek Stephan; Plooy Annaliese M; Reid Campbell S; Marinovic Welber; Tresilian James R
2010-01-01
Abstract Background Continuous visual information is important for movement initiation in a variety of motor tasks. However, even in the absence of visual information people are able to initiate their responses by using motion extrapolation processes. Initiation of actions based on these cognitive processes, however, can demand more attentional resources than that required in situations in which visual information is uninterrupted. In the experiment reported we sought to determine whether the...
Properties of a commercial extrapolation chamber in ? radiation fields
International Nuclear Information System (INIS)
A commercial extrapolation chamber was tested in different ? radiation fields and its properties investigated. Its usefulness for ? radiation calibration and dosimetry was verified. Experiments were performed in order to obtain the main characteristics such as the calibration factors (and consequently the energy dependence) for all chamber collecting electrodes (between 10 and 40 mm diameter), the transmission factors in tissue and the useful source-detector distance range
Extrapolation of zircon fission-track annealing models
International Nuclear Information System (INIS)
One of the purposes of this study is to give further constraints on the temperature range of the zircon partial annealing zone over a geological time scale using data from borehole zircon samples, which have experienced stable temperatures for ?1 Ma. In this way, the extrapolation problem is explicitly addressed by fitting the zircon annealing models with geological timescale data. Several empirical model formulations have been proposed to perform these calibrations and have been compared in this work. The basic form proposed for annealing models is the Arrhenius-type model. There are other annealing models, that are based on the same general formulation. These empirical model equations have been preferred due to the great number of phenomena from track formation to chemical etching that are not well understood. However, there are two other models, which try to establish a direct correlation between their parameters and the related phenomena. To compare the response of the different annealing models, thermal indexes, such as closure temperature, total annealing temperature and the partial annealing zone, have been calculated and compared with field evidence. After comparing the different models, it was concluded that the fanning curvilinear models yield the best agreement between predicted index temperatures and field evidence. - Highlights: ? Geological data were used along with lab data for improving model extrapolation. ? Index temperatures were simulated for testing model extrapolation. ? Curvilinear Arrhenius models produced better geological temperature predictions
Efficient anisotropic wavefield extrapolation using effective isotropic models
Alkhalifah, Tariq Ali
2013-06-10
Isotropic wavefield extrapolation is more efficient than anisotropic extrapolation, and this is especially true when the anisotropy of the medium is tilted (from the vertical). We use the kinematics of the wavefield, appropriately represented in the high-frequency asymptotic approximation by the eikonal equation, to develop effective isotropic models, which are used to efficiently and approximately extrapolate anisotropic wavefields using the isotropic, relatively cheaper, operators. These effective velocity models are source dependent and tend to embed the anisotropy in the inhomogeneity. Though this isotropically generated wavefield theoretically shares the same kinematic behavior as that of the first arrival anisotropic wavefield, it also has the ability to include all the arrivals resulting from a complex wavefield propagation. In fact, the effective models reduce to the original isotropic model in the limit of isotropy, and thus, the difference between the effective model and, for example, the vertical velocity depends on the strength of anisotropy. For reverse time migration (RTM), effective models are developed for the source and receiver fields by computing the traveltime for a plane wave source stretching along our source and receiver lines in a delayed shot migration implementation. Applications to the BP TTI model demonstrates the effectiveness of the approach.
Extrapolation and unitarity bounds for the B ? ? form factor
Imsong, I. Sentitemsu; Khodjamirian, Alexander; Mannel, Thomas; van Dyk, Danny
2015-02-01
We address the problem of extrapolating the vector form factor f {/B? +}, which is relevant to B ? ??? ? decays, from the region of small to the region of large momentum transfer. As input, we use the QCD light-cone sum rule at small momentum transfer. We carry out a comprehensive Bayesian uncertainty analysis and obtain correlated uncertainties for the normalization and shape parameters of the form factor. The z-series parametrization for f {/B? +} is employed to extrapolate our results to large momentum transfer, and to compare with the lattice QCD results. To test the validity of our extrapolation we use the upper and lower bounds from the unitarity and positivity of the two-point correlator of heavy-light quark currents. This correlator is updated by including the NNLO perturbative term and the NLO correction to the quark condensate contribution. We demonstrate that an additional input including the form factor, its first and second derivative calculated at one value of momentum transfer from the light-cone sum rules, considerably improves the bounds. This only holds when the correlations between the form factor parameters are taken into account. We further combine our results with the latest experimental measurements of B ? ??? ? by the BaBar and Belle collaborations, and obtain | V ub | = (3. 32{-/0.22 + 0.26}) ? 10- 3 from a Bayesian analysis.
International Nuclear Information System (INIS)
Several analytical-numerical methods of sequence extrapolation and their main convergence properties are considered with a view to their use for the evaluation at asymptotic times of the effects of the nonlinear beam-beam interaction on the motion of a test particle in an intersecting storage ring. The test-particle betatron-synchrotron modulated motion (for bunched and unbunched beams) and its spin precession and polarization are properly modeled in order to derive expressions suited to numerical extrapolation. (author)
Energy Technology Data Exchange (ETDEWEB)
Alvarez R, M. T.; Morales P, J. R. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)
2001-01-15
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)
Resolution enhancement in digital holography by self-extrapolation of holograms
Latychevskaia, Tatiana
2013-01-01
It is generally believed that the resolution in digital holography is limited by the size of the captured holographic record. Here, we present a method to circumvent this limit by self-extrapolating experimental holograms beyond the area that is actually captured. This is done by first padding the surroundings of the hologram and then conducting an iterative reconstruction procedure. The wavefront beyond the experimentally detected area is thus retrieved and the hologram reconstruction shows enhanced resolution. To demonstrate the power of this concept, we apply it to simulated as well as experimental holograms.
Wouters, Sebastian; Van Neck, Dimitri; Ayers, Paul W
2012-01-01
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.
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)
Multi-step Richardson-Romberg Extrapolation: Remarks on Variance Control and complexity
Pagès, Gilles
2007-01-01
We propose a multi-step Richardson-Romberg extrapolation method for the computation of expectations $E f(X_{_T})$ of a diffusion $(X_t)_{t\\in [0,T]}$ when the weak time discretization error induced by the Euler scheme admits an expansion at an order $R\\ge 2$. The complexity of the estimator grows as $R^2$ (instead of $2^R$) and its variance is asymptotically controlled by considering some consistent Brownian increments in the underlying Euler schemes. Some Monte carlo simula...
International Nuclear Information System (INIS)
We present a method based on the use of toroidal harmonics and on a modelization of the poloidal field coils and divertor coils for the 2D interpolation and extrapolation of discrete magnetic measurements in a tokamak. The method is generic and can be used to provide the Cauchy boundary conditions needed as input by a fixed domain equilibrium reconstruction code like Equinox (Blum et al 2012 J. Comput. Phys. 231 960–80). It can also be used to extrapolate the magnetic measurements in order to compute the plasma boundary itself. The proposed method and algorithm are detailed in this paper and results from numerous numerical experiments are presented. The method is foreseen to be used in the real-time plasma control loop on the WEST tokamak (Bucalossi et al 2011 Fusion Eng. Des. 86 684–8). (paper)
Faugeras, Blaise; Blum, Jacques; Boulbe, Cedric; Moreau, Philippe; Nardon, Eric
2014-11-01
We present a method based on the use of toroidal harmonics and on a modelization of the poloidal field coils and divertor coils for the 2D interpolation and extrapolation of discrete magnetic measurements in a tokamak. The method is generic and can be used to provide the Cauchy boundary conditions needed as input by a fixed domain equilibrium reconstruction code like Equinox (Blum et al 2012 J. Comput. Phys. 231 960–80). It can also be used to extrapolate the magnetic measurements in order to compute the plasma boundary itself. The proposed method and algorithm are detailed in this paper and results from numerous numerical experiments are presented. The method is foreseen to be used in the real-time plasma control loop on the WEST tokamak (Bucalossi et al 2011 Fusion Eng. Des. 86 684–8).
International Nuclear Information System (INIS)
Two transversely oscillating coronal loops are investigated in detail during a flare on the 2011 September 6 using data from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory. We compare two independent methods to determine the Alfvén speed inside these loops. Through the period of oscillation and loop length, information about the Alfvén speed inside each loop is deduced seismologically. This is compared with the Alfvén speed profiles deduced from magnetic extrapolation and spectral methods using AIA bandpass. We find that for both loops the two methods are consistent. Also, we find that the average Alfvén speed based on loop travel time is not necessarily a good measure to compare with the seismological result, which explains earlier reported discrepancies. Instead, the effect of density and magnetic stratification on the wave mode has to be taken into account. We discuss the implications of combining seismological, extrapolation, and spectral methods in deducing the physical properties of coronal loops.
Tiruneh, Ababu Teklemariam
2013-01-01
Aitken extrapolation normally applied to convergent fixed point iteration is extended to extrapolate the solution of a divergent iteration. In addition, higher order Aitken extrapolation is introduced that enables successive decomposition of high Eigen values of the iteration matrix to enable convergence. While extrapolation of a convergent fixed point iteration using a geometric series sum is a known form of Aitken acceleration, it is shown in this paper that the same formu...
Kaltenboeck, Rudolf; Kerschbaum, Markus; Hennermann, Karin; Mayer, Stefan
2013-04-01
Nowcasting of precipitation events, especially thunderstorm events or winter storms, has high impact on flight safety and efficiency for air traffic management. Future strategic planning by air traffic control will result in circumnavigation of potential hazardous areas, reduction of load around efficiency hot spots by offering alternatives, increase of handling capacity, anticipation of avoidance manoeuvres and increase of awareness before dangerous areas are entered by aircraft. To facilitate this rapid update forecasts of location, intensity, size, movement and development of local storms are necessary. Weather radar data deliver precipitation analysis of high temporal and spatial resolution close to real time by using clever scanning strategies. These data are the basis to generate rapid update forecasts in a time frame up to 2 hours and more for applications in aviation meteorological service provision, such as optimizing safety and economic impact in the context of sub-scale phenomena. On the basis of tracking radar echoes by correlation the movement vectors of successive weather radar images are calculated. For every new successive radar image a set of ensemble precipitation fields is collected by using different parameter sets like pattern match size, different time steps, filter methods and an implementation of history of tracking vectors and plausibility checks. This method considers the uncertainty in rain field displacement and different scales in time and space. By validating manually a set of case studies, the best verification method and skill score is defined and implemented into an online-verification scheme which calculates the optimized forecasts for different time steps and different areas by using different extrapolation ensemble members. To get information about the quality and reliability of the extrapolation process additional information of data quality (e.g. shielding in Alpine areas) is extrapolated and combined with an extrapolation-quality-index. Subsequently the probability and quality information of the forecast ensemble is available and flexible blending to numerical prediction model for each subarea is possible. Simultaneously with automatic processing the ensemble nowcasting product is visualized in a new innovative way which combines the intensity, probability and quality information for different subareas in one forecast image.
Energy Technology Data Exchange (ETDEWEB)
Kim, B.H.; Velas, J.P.; Lee, K.Y [Pennsylvania State Univ., University Park, PA (United States). Dept. of Electrical Engineering
2006-07-01
This paper presented a mathematical method that power plant operators can use to estimate rotational mass unbalance, which is the most common source of vibration in turbine generators. An unbalanced rotor or driveshaft causes vibration and stress in the rotating part and in its supporting structure. As such, balancing the rotating part is important to minimize structural stress, minimize operator annoyance and fatigue, increase bearing life, or minimize power loss. The newly proposed method for estimating vibration on a turbine generator uses mass unbalance extrapolation based on a modified system-type neural network architecture, notably the semigroup theory used to study differential equations, partial differential equations and their combinations. Rather than relying on inaccurate vibration measurements, this method extrapolates a set of reliable mass unbalance readings from a common source of vibration. Given a set of empirical data with no analytic expression, the authors first developed an analytic description and then extended that model along a single axis. The algebraic decomposition which was used to obtain the analytic description of empirical data in the semigroup form involved the product of a coefficient vector and a basis set of vectors. The proposed approach was simulated on empirical data. The concept can also be tested in many other engineering and non-engineering problems. 23 refs., 11 figs.
True amplitude migration using common-shot one-way wavefield extrapolation
Energy Technology Data Exchange (ETDEWEB)
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
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.
Determination of dose rates in beta radiation fields using extrapolation chamber and GM counter
DEFF Research Database (Denmark)
Borg, J.; Christensen, P.
1995-01-01
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.
On the extrapolation to ITER of discharges in present tokamaks
Peeters, A.G.; Angioni, C.; Sips, A. C. C.
2007-01-01
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,...
QCD thermodynamics with continuum extrapolated dynamical overlap fermions
Borsanyi, Sz; Lippert, T; Nogradi, D; Pittler, F; Szabo, K K; Toth, B C
2015-01-01
We study the finite temperature transition in QCD with two flavors of dynamical fermions at a pseudoscalar pion mass of about 350 MeV. We use lattices with temporal extent of $N_t$=8, 10 and 12. For the first time in the literature a continuum limit is carried out for several observables with dynamical overlap fermions. These findings are compared with results obtained within the staggered fermion formalism at the same pion masses and extrapolated to the continuum limit. The presented results correspond to fixed topology and its effect is studied in the staggered case. Nice agreement is found between the overlap and staggered results.
Energy Technology Data Exchange (ETDEWEB)
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
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.
3D Drop Size Distribution Extrapolation Algorithm Using a Single Disdrometer
Lane, John
2012-01-01
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.
DEFF Research Database (Denmark)
Ambühl, Simon; Sterndorff, Martin
2014-01-01
Mooring systems for floating wave energy converters (WECs) are a major cost driver. Failure of mooring systems often occurs due to extreme loads. This paper introduces an extrapolation method for extreme response which accounts for the control system of a WEC that controls the loads onto the structure and the harvested power of the device as well as the fact that extreme loads may occur during operation and not at extreme wave states when the device is in storm protection mode. The extrapolation method is based on shortterm load time series and applied to a case study where up-scaled surge load measurements from lab-scaled WEPTOS WEC are taken. Different catenary anchor leg mooring (CALM) systems as well as single anchor legmooring (SALM)mooring systemsare implemented for a dynamic simulation with different number of mooring lines. Extreme tension loads with a return period of 50 years are assessed for the hawser as well as at the different mooring lines. Furthermore, the extreme load impact given failure of one mooring line is assessed and compared with extreme loads given no system failure.
Biokinetic modeling and in vitro-in vivo extrapolations.
Blaauboer, Bas J
2010-02-01
The introduction of in vitro methodologies in the toxicological risk assessment process requires a number of prerequisites regarding both the toxicodynamics and the biokinetics of the compounds under study. In vitro systems will need to be relevant for measuring those structural and physiological changes that are good indicators for adverse effects. Furthermore, the dose metric found to have an effect in the in vitro system should be relevant. One element in defining the appropriate dose metric is related to the kinetic behavior of the compound in the in vitro system: binding to proteins, binding to plastic, evaporation, and the interaction between the culture medium and the cells. Ways to measure and model "in vitro biokinetics" are described. Second, the appropriate dose metric in vitro, e.g., the effective concentration, will need to be extrapolated to relevant in vivo exposure scenarios. The application of physiologically based biokinetic modelling is essential in such extrapolations. The parameters needed to build these models often can be estimated based on nonanimal data, namely chemical properties (QSARs) and in vitro experiments. PMID:20574900
Effective Elliptic Models for Efficient Wavefield Extrapolation in Anisotropic Media
Waheed, Umair bin
2014-05-01
Wavefield extrapolation operator for elliptically anisotropic media offers significant cost reduction compared to that of transversely isotropic media (TI), especially when the medium exhibits tilt in the symmetry axis (TTI). However, elliptical anisotropy does not provide accurate focusing for TI media. Therefore, we develop effective elliptically anisotropic models that correctly capture the kinematic behavior of the TTI wavefield. Specifically, we use an iterative elliptically anisotropic eikonal solver that provides the accurate traveltimes for a TI model. The resultant coefficients of the elliptical eikonal provide the effective models. These effective models allow us to use the cheaper wavefield extrapolation operator for elliptic media to obtain approximate wavefield solutions for TTI media. Despite the fact that the effective elliptic models are obtained by kinematic matching using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including the frequency dependency and caustics, if present, with reasonable accuracy. The methodology developed here offers a much better cost versus accuracy tradeoff for wavefield computations in TTI media, considering the cost prohibitive nature of the problem. We demonstrate the applicability of the proposed approach on the BP TTI model.
Making the most of what we have: application of extrapolation approaches in wildlife transfer models
Energy Technology Data Exchange (ETDEWEB)
Beresford, Nicholas A.; Barnett, Catherine L.; Wells, Claire [NERC Centre for Ecology and Hydrology, Lancaster Environment Center, Library Av., Bailrigg, Lancaster, LA1 4AP (United Kingdom); School of Environment and Life Sciences, University of Salford, Manchester, M4 4WT (United Kingdom); Wood, Michael D. [School of Environment and Life Sciences, University of Salford, Manchester, M4 4WT (United Kingdom); Vives i Batlle, Jordi [Belgian Nuclear Research Centre, Boeretang 200, 2400 Mol (Belgium); Brown, Justin E.; Hosseini, Ali [Norwegian Radiation Protection Authority, P.O. Box 55, N-1332 Oesteraas (Norway); Yankovich, Tamara L. [International Atomic Energy Agency, Vienna International Centre, 1400, Vienna (Austria); Bradshaw, Clare [Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-10691 (Sweden); Willey, Neil [Centre for Research in Biosciences, University of the West of England, Coldharbour Lane, Frenchay, Bristol BS16 1QY (United Kingdom)
2014-07-01
Radiological environmental protection models need to predict the transfer of many radionuclides to a large number of organisms. There has been considerable development of transfer (predominantly concentration ratio) databases over the last decade. However, in reality it is unlikely we will ever have empirical data for all the species-radionuclide combinations which may need to be included in assessments. To provide default values for a number of existing models/frameworks various extrapolation approaches have been suggested (e.g. using data for a similar organism or element). This paper presents recent developments in two such extrapolation approaches, namely phylogeny and allometry. An evaluation of how extrapolation approaches have performed and the potential application of Bayesian statistics to make best use of available data will also be given. Using a Residual Maximum Likelihood (REML) mixed-model regression we initially analysed a dataset comprising 597 entries for 53 freshwater fish species from 67 sites to investigate if phylogenetic variation in transfer could be identified. The REML analysis generated an estimated mean value for each species on a common scale after taking account of the effect of the inter-site variation. Using an independent dataset, we tested the hypothesis that the REML model outputs could be used to predict radionuclide activity concentrations in other species from the results of a species which had been sampled at a specific site. The outputs of the REML analysis accurately predicted {sup 137}Cs activity concentrations in different species of fish from 27 lakes. Although initially investigated as an extrapolation approach the output of this work is a potential alternative to the highly site dependent concentration ratio model. We are currently applying this approach to a wider range of organism types and different ecosystems. An initial analysis of these results will be presented. The application of allometric, or mass-dependent, relationships within radioecology has increased with the evolution of models to predict the exposure of wildlife as it presents a method of addressing the lack of empirical data. Among the parameters which scale allometrically is radionuclide biological half-life. However, sufficient data across a range of species with different masses are required to establish allometric relationships for biological half-life and this is not always available. We have recently derived an alternative allometric approach to predict the biological half-life of radionuclides in homeothermic vertebrates which does not require such data. Predicted biological half-life values for four radionuclides compared well to available data for a range of species. The potential to further develop these approaches will be discussed. (authors)
Making the most of what we have: application of extrapolation approaches in wildlife transfer models
International Nuclear Information System (INIS)
Radiological environmental protection models need to predict the transfer of many radionuclides to a large number of organisms. There has been considerable development of transfer (predominantly concentration ratio) databases over the last decade. However, in reality it is unlikely we will ever have empirical data for all the species-radionuclide combinations which may need to be included in assessments. To provide default values for a number of existing models/frameworks various extrapolation approaches have been suggested (e.g. using data for a similar organism or element). This paper presents recent developments in two such extrapolation approaches, namely phylogeny and allometry. An evaluation of how extrapolation approaches have performed and the potential application of Bayesian statistics to make best use of available data will also be given. Using a Residual Maximum Likelihood (REML) mixed-model regression we initially analysed a dataset comprising 597 entries for 53 freshwater fish species from 67 sites to investigate if phylogenetic variation in transfer could be identified. The REML analysis generated an estimated mean value for each species on a common scale after taking account of the effect of the inter-site variation. Using an independent dataset, we tested the hypothesis that the REML model outputs could be used to predict radionuclide activity concentrations in other species from the results of a species which had been sampled at a specific site. The outputs of the REML analysis accurately predicted 137Cs activity concentrations in different species of fish from 27 lakes. Although initially investigated as an extrapolation approach the output of this work is a potential alternative to the highly site dependent concentration ratio model. We are currently applying this approach to a wider range of organism types and different ecosystems. An initial analysis of these results will be presented. The application of allometric, or mass-dependent, relationships within radioecology has increased with the evolution of models to predict the exposure of wildlife as it presents a method of addressing the lack of empirical data. Among the parameters which scale allometrically is radionuclide biological half-life. However, sufficient data across a range of species with different masses are required to establish allometric relationships for biological half-life and this is not always available. We have recently derived an alternative allometric approach to predict the biological half-life of radionuclides in homeothermic vertebrates which does not require such data. Predicted biological half-life values for four radionuclides compared well to available data for a range of species. The potential to further develop these approaches will be discussed. (authors)
Extrapolating W-Associated Jet-Production Ratios at the LHC
Bern, Z; Cordero, F Febres; Hoeche, S; Kosower, D A; Ita, H; Maitre, D
2014-01-01
Electroweak vector-boson production, accompanied by multiple jets, is an important background to searches for physics beyond the Standard Model. A precise and quantitative understanding of this process is helpful in constraining deviations from known physics. We study four key ratios in $W + n$-jet production at the LHC. We compute the ratio of cross sections for $W + n$- to $W + (n-1)$-jet production as a function of the minimum jet transverse momentum. We also study the ratio differentially, as a function of the $W$-boson transverse momentum; as a function of the scalar sum of the jet transverse energy, $H_T^{\\rm jets}$; and as a function of certain jet transverse momenta. We show how to use such ratios to extrapolate differential cross sections to $W+6$-jet production at next-to-leading order, and we cross-check the method against a direct calculation at leading order. We predict the differential distribution in $H_T^{\\rm jets}$ for $W+6$ jets at next-to-leading order using such an extrapolation. We use th...
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.
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
International Nuclear Information System (INIS)
The work presented covers different parts of a repository system such as near and far field aspects. Investigations are reported for the degradation of HLW glass, for the corrosion of container materials, for changes of geochemical environment in geological repositories, and for the thermo-mechanical behaviour of granitic host rock. Extrapolation methods are developed and applied for temperature and stress development in the host rock and for the radionuclide transport through a fractured system. (author)
Data-driven scale extrapolation : estimating yearly discharge for a large region by small sub-basins
Gong, L
2014-01-01
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 typical...
UFOs in the LHC: Observations, studies and extrapolations
Baer, T; Cerutti, F; Ferrari, A; Garrel, N; Goddard, B; Holzer, EB; Jackson, S; Lechner, A; Mertens, V; Misiowiec, M; Nebot del Busto, E; Nordt, A; Uythoven, J; Vlachoudis, V; Wenninger, J; Zamantzas, C; Zimmermann, F; Fuster, N
2012-01-01
Unidentified falling objects (UFOs) are potentially a major luminosity limitation for nominal LHC operation. They are presumably micrometer sized dust particles which lead to fast beam losses when they interact with the beam. With large-scale increases and optimizations of the beam loss monitor (BLM) thresholds, their impact on LHC availability was mitigated from mid 2011 onwards. For higher beam energy and lower magnet quench limits, the problem is expected to be considerably worse, though. In 2011/12, the diagnostics for UFO events were significantly improved: dedicated experiments and measurements in the LHC and in the laboratory were made and complemented by FLUKA simulations and theoretical studies. The state of knowledge, extrapolations for nominal LHC operation and mitigation strategies are presented
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.
Entanglement entropy and negativity of disjoint intervals in CFT: Some numerical extrapolations
De Nobili, Cristiano; Tonni, Erik
2015-01-01
The entanglement entropy and the logarithmic negativity can be computed in quantum field theory through a method based on the replica limit. Performing these analytic continuations in some cases is beyond our current knowledge, even for simple models. We employ a numerical method based on rational interpolations to extrapolate the entanglement entropy of two disjoint intervals for the conformal field theories given by the free compact boson and the Ising model. The case of three disjoint intervals is studied for the Ising model and the non compact free massless boson. For the latter model, the logarithmic negativity of two disjoint intervals has been also considered. Some of our findings have been checked against existing numerical results obtained from the corresponding lattice models.
Entanglement entropy and negativity of disjoint intervals in CFT: some numerical extrapolations
De Nobili, Cristiano; Coser, Andrea; Tonni, Erik
2015-06-01
The entanglement entropy and the logarithmic negativity can be computed in quantum field theory through a method based on the replica limit. Performing these analytic continuations in some cases is beyond our current knowledge, even for simple models. We employ a numerical method based on rational interpolations to extrapolate the entanglement entropy of two disjoint intervals for the conformal field theories given by the free compact boson and the Ising model. The case of three disjoint intervals is studied for the Ising model and the non compact free massless boson. For the latter model, the logarithmic negativity of two disjoint intervals has been also considered. Some of our findings have been checked against existing numerical results obtained from the corresponding lattice models.
Epistemological considerations in the extrapolation of metabolic data from non-humans to humans
International Nuclear Information System (INIS)
The rationale underlying interspecies extrapolation of metabolic data has been based primarily on pragmatic concerns. Little attention has been given to the extent to which such extrapolations have a firm epistemological basis. The strength of this approach for model-free (purely empirical) extrapolation and for extrapolation involving a variety of theoretical constructs is examined in this paper. An attempt is made to provide some understanding of the degree of confidence that can be placed in the extrapolation of metabolic data from one species to another. Published results for a wide variety of radionuclides are analyzed and the importance of these results to the field of nuclear medicine is explored. Problems inherent in the logic of extrapolation are then delineated in view of these historical data
Ullemeyer, K.; Lokají?ek, T.; Keppler, R.; Vasin, R. N.; Behrmann, J. H.
2015-04-01
The elastic anisotropy of bulk rock depends on the mineral textures, the crack fabric and external parameters like, e.g., confining pressure. The texture-related contribution to elastic anisotropy can be predicted from the mineral textures, the largely sample-dependent contribution of the other parameters must be determined experimentally. Laboratory measurements of the elastic wave velocities are mostly limited to pressures of the intermediate crust. We describe a method, how the elastic wave velocity trends and, by this means, the elastic constants can be extrapolated to the pressure conditions of the lower crust. The extrapolated elastic constants are compared to the texture-derived ones. Pronounced elastic anisotropy is evident for phyllosilicate minerals, hence, the approach is demonstrated for two phyllosilicate-rich gneisses with approximately identical volume fractions of the phyllosilicates but different texture types.
Patient-bounded extrapolation using low-dose priors for volume-of-interest imaging in C-arm CT
International Nuclear Information System (INIS)
Purpose: Three-dimensional (3D) volume-of-interest (VOI) imaging with C-arm systems provides anatomical information in a predefined 3D target region at a considerably low x-ray dose. However, VOI imaging involves laterally truncated projections from which conventional reconstruction algorithms generally yield images with severe truncation artifacts. Heuristic based extrapolation methods, e.g., water cylinder extrapolation, typically rely on techniques that complete the truncated data by means of a continuity assumption and thus appear to be ad-hoc. It is our goal to improve the image quality of VOI imaging by exploiting existing patient-specific prior information in the workflow. Methods: A necessary initial step prior to a 3D acquisition is to isocenter the patient with respect to the target to be scanned. To this end, low-dose fluoroscopic x-ray acquisitions are usually applied from anterior–posterior (AP) and medio-lateral (ML) views. Based on this, the patient is isocentered by repositioning the table. In this work, we present a patient-bounded extrapolation method that makes use of these noncollimated fluoroscopic images to improve image quality in 3D VOI reconstruction. The algorithm first extracts the 2D patient contours from the noncollimated AP and ML fluoroscopic images. These 2D contours are then combined to estimate a volumetric model of the patient. Forward-projecting the shape of the model at the eventually acquired C-arm rotation views gives the patient boundary information in the projection domain. In this manner, we are in the position to substantially improve image quality by enforcing the extrapolated line profiles to end at the known patient boundaries, derived from the 3D shape model estimate. Results: The proposed method was evaluated on eight clinical datasets with different degrees of truncation. The proposed algorithm achieved a relative root mean square error (rRMSE) of about 1.0% with respect to the reference reconstruction on nontruncated data, even in the presence of severe truncation, compared to a rRMSE of 8.0% when applying a state-of-the-art heuristic extrapolation technique. Conclusions: The method we proposed in this paper leads to a major improvement in image quality for 3D C-arm based VOI imaging. It involves no additional radiation when using fluoroscopic images that are acquired during the patient isocentering process. The model estimation can be readily integrated into the existing interventional workflow without additional hardware
Patient-bounded extrapolation using low-dose priors for volume-of-interest imaging in C-arm CT
Energy Technology Data Exchange (ETDEWEB)
Xia, Y.; Maier, A.; Berger, M.; Hornegger, J. [Pattern Recognition Lab, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen 91058 (Germany); Bauer, S. [Siemens AG, Healthcare Sector, Forchheim 91301 (Germany)
2015-04-15
Purpose: Three-dimensional (3D) volume-of-interest (VOI) imaging with C-arm systems provides anatomical information in a predefined 3D target region at a considerably low x-ray dose. However, VOI imaging involves laterally truncated projections from which conventional reconstruction algorithms generally yield images with severe truncation artifacts. Heuristic based extrapolation methods, e.g., water cylinder extrapolation, typically rely on techniques that complete the truncated data by means of a continuity assumption and thus appear to be ad-hoc. It is our goal to improve the image quality of VOI imaging by exploiting existing patient-specific prior information in the workflow. Methods: A necessary initial step prior to a 3D acquisition is to isocenter the patient with respect to the target to be scanned. To this end, low-dose fluoroscopic x-ray acquisitions are usually applied from anterior–posterior (AP) and medio-lateral (ML) views. Based on this, the patient is isocentered by repositioning the table. In this work, we present a patient-bounded extrapolation method that makes use of these noncollimated fluoroscopic images to improve image quality in 3D VOI reconstruction. The algorithm first extracts the 2D patient contours from the noncollimated AP and ML fluoroscopic images. These 2D contours are then combined to estimate a volumetric model of the patient. Forward-projecting the shape of the model at the eventually acquired C-arm rotation views gives the patient boundary information in the projection domain. In this manner, we are in the position to substantially improve image quality by enforcing the extrapolated line profiles to end at the known patient boundaries, derived from the 3D shape model estimate. Results: The proposed method was evaluated on eight clinical datasets with different degrees of truncation. The proposed algorithm achieved a relative root mean square error (rRMSE) of about 1.0% with respect to the reference reconstruction on nontruncated data, even in the presence of severe truncation, compared to a rRMSE of 8.0% when applying a state-of-the-art heuristic extrapolation technique. Conclusions: The method we proposed in this paper leads to a major improvement in image quality for 3D C-arm based VOI imaging. It involves no additional radiation when using fluoroscopic images that are acquired during the patient isocentering process. The model estimation can be readily integrated into the existing interventional workflow without additional hardware.
Miga, Michael I.; Dumpuri, Prashanth; Simpson, Amber L.; Weis, Jared A.; Jarnagin, William R.
2011-03-01
The problem of extrapolating cost-effective relevant information from distinctly finite or sparse data, while balancing the competing goals between workflow and engineering design, and between application and accuracy is the 'sparse data extrapolation problem'. Within the context of open abdominal image-guided liver surgery, one realization of this problem is compensating for non-rigid organ deformations while maintaining workflow for the surgeon. More specifically, rigid organ-based surface registration between CT-rendered liver surfaces and laser-range scanned intraoperative partial surface counterparts resulted in an average closest-point residual 6.1 +/- 4.5 mm with maximumsigned distances ranging from -13.4 to 16.2 mm. Similar to the neurosurgical environment, there is a need to correct for soft tissue deformation to translate image-guided interventions to the abdomen (e.g. liver, kidney, pancreas, etc.). While intraoperative tomographic imaging is available, these approaches are less than optimal solutions to the sparse data extrapolation problem. In this paper, we compare and contrast three sparse data extrapolation methods to that of datarich interpolation for the correction of deformation within a liver phantom containing 43 subsurface targets. The findings indicate that the subtleties in the initial alignment pose following rigid registration can affect correction up to 5- 10%. The best deformation compensation achieved was approximately 54.5% (target registration error of 2.0 +/- 1.6 mm) while the data-rich interpolative method was 77.8% (target registration error of 0.6 +/- 0.5 mm).
Extrapolative Analysis of Fast-Switching Free Energy Estimates in a Molecular System
Zuckerman, D M; Zuckerman, Daniel M.; Woolf, Thomas B.
2001-01-01
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.
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The Intelligent Extrapolation Criticality Device is used for automatic counting and automatic extrapolation during the criticality experiment on the reactor. Test must be performed on the zero-power reactor or other reactor before the Device is used. The paper describes the test situation and test results of the Device on the zero-power reactor. The test results show that the Device has the function of automatic counting and automatic extrapolation, the deviation of the extrapolation data is small, and it can satisfy the requirements of physical startup on the reactor. (author)
Fridolin, Ivo; Karai, Deniss; Kostin, Sergei; Ubar, Raimund
2013-05-01
The aim of this study was to propose an improved method for accurate dialysis dose evaluation and extrapolation by means of Kt/ V from online UV-absorbance measurements for real time and continuous treatment monitoring. The study included a total of 24 treatments from ten uremic patients, seven of whom were male and three females. All patients were on chronic thrice-weekly hemodialysis therapy. The study included both stable and unstable treatments. A known signal processing algorithm, Levenberg-Marquardt, and the newly developed SMART were utilized for the removal of disturbances not relevant for dialysis dose evaluation. Finally, the results were compared with the Kt/ V values based on the blood samples. The new data processing algorithm, SMART, removes disturbances, helps estimate the online Kt/ V with significant precision increase and without any time delay, and more effectively predicts the end Kt/ V for the treatment than the known algorithms. PMID:23268379
Sato, A.; Yomogida, K.
2014-12-01
The early warning system operated by Japan Meteorological Agency (JMA) has been available in public since October 2007.The present system is still not effective in cases, that we cannot assume a nearly circular wavefront expansion from a source. We propose a new approach based on the extrapolation of the early observed wavefield alone without estimating its epicenter. The idea is similar to the migration method in exploration seismology, but we use not only the information of wave field at an early stage (i.e., at time T2 in Figure, but also its normal derivatives the difference between T1 and T2), that is, we utilize the apparent velocity and direction of early-stage wave propagation to predict the wavefield later (at T3 in Fig.). For the extrapolation of wavefield, we need a reliable Green's function from the observed point to a target point at which the wave arrives later. Since the complete 3-D wave propagation is extremely complex, particularly in and around Japan of highly heterogeneous structures, we shall consider a phenomenological 2-D Green's function, that is, a wavefront propagates on the surface with a certain apparent velocity and direction of P wave. This apparent velocity and direction may vary significantly depending on, for example, event depth and an area of propagation, so we examined those of P wave propagating in Japan in various situations. For example, the velocity of shallow events in Hokkaido is 7.1km/s while that in Nagano prefecture is about 5.5km/s. In addition, the apparent velocity depends on event depth, 7.1km/s for the depth of 10km and 8.9km/s for 100km in Hokkaido. We also conducted f-k array analyses of adjacent five or six stations where we can accurately estimate the apparent velocity and direction of P wave. For deep events with relatively simple waveforms, they are easily obtained, but we may need site corrections to enhance correlations of waveforms among stations for shallow ones. In the above extrapolation scheme, we can only estimate the arrival times of P wave at remote stations, but we need to estimate S wave arrival time and intensity in practice. We compare the actual S wave arrival times with P wave ones for various epicenter distances, event depths and regions, so that some empirical relations between them are listed for our final goal of S wave estimations.
CT image construction of a totally deflated lung using deformable model extrapolation
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Purpose: A novel technique is proposed to construct CT image of a totally deflated lung from a free-breathing 4D-CT image sequence acquired preoperatively. Such a constructed CT image is very useful in performing tumor ablative procedures such as lung brachytherapy. Tumor ablative procedures are frequently performed while the lung is totally deflated. Deflating the lung during such procedures renders preoperative images ineffective for targeting the tumor. Furthermore, the problem cannot be solved using intraoperative ultrasound (U.S.) images because U.S. images are very sensitive to small residual amount of air remaining in the deflated lung. One possible solution to address these issues is to register high quality preoperative CT images of the deflated lung with their corresponding low quality intraoperative U.S. images. However, given that such preoperative images correspond to an inflated lung, such CT images need to be processed to construct CT images pertaining to the lung's deflated state. Methods: To obtain the CT images of deflated lung, we present a novel image construction technique using extrapolated deformable registration to predict the deformation the lung undergoes during full deflation. The proposed construction technique involves estimating the lung's air volume in each preoperative image automatically in order to track the respiration phase of each 4D-CT image throughout a respiratory cycle; i.e., the technique does not need any external marker to form a respiratory signal in the process of curve fitting and extrapolation. The extrapolated deformation field is then applied on a preoperative reference image in order to construct the totally deflated lung's CT image. The technique was evaluated experimentally using ex vivo porcine lung. Results: The ex vivo lung experiments led to very encouraging results. In comparison with the CT image of the deflated lung we acquired for the purpose of validation, the constructed CT image was very similar. The intensity mean absolute difference between these two images was calculated to be at 1%. Tumor center as well as a number of anatomical fiducial markers were traced in different corresponding slices of the two images. The average misalignment obtained for the constructed CT image was (0.64, 0.39, 0.11) mm, which indicates a very desirable accuracy for lung brachytherapy applications. Conclusions: The image construction accuracy obtained in this research is suitable for intraoperative tasks; e.g., tumor localization and fusing with real time navigation data in lung brachytherapy. These applications involve image registration with intraoperative U.S. images in order to enhance their poor quality. The proposed technique is also useful for preoperative tasks such as planning of lung brachytherapy treatment.
Directory of Open Access Journals (Sweden)
Ezekiel Uba Nwose
2010-04-01
Full Text Available Background: There are many different methods for the assessment of whole blood viscosity, but not every pathology unit has equipment for any of the methods. However, a validated arithmetic method exists whereby whole blood viscosity can be extrapolated from haematocrit and total serum proteins. Aims: The objective of this work is to develop an algorithm in the form of a chart by which clinicians can easily extrapolate whole blood viscosity values in their consulting rooms or on the ward. Another objective is to suggest normal, subnormal and critical reference ranges applicable to this method. Materials and Methods: Whole blood viscosity at high shear stress was determined, from various possible pairs of haematocrit and total proteins. A chart was formulated so that whole blood viscosity can be extrapolated. After determination of two standard deviations from the mean and ascertainment of symmetric distribution, normal and abnormal reference ranges were defined. Results: The clinicians’ user-friendly chart is presented. Considering presumptive lower and upper limits, the continuum of ?14.28, 14.29 – 15.00, 15.01 – 19.01, 19.02 – 19.39 and ?19.40 (208 Sec-1 is obtained as reference ranges for critically low, subnormal low, normal, subnormal high and critically high whole blood viscosity levels respectively. Conclusion: This article advances a validated method to provide a user-friendly chart that would enable clinicians to assess whole blood viscosity for any patients who has results for full blood count and total proteins. It would make the assessment of whole blood viscosity costless and the neglect of a known cardiovascular risk factor less excusable.
International Nuclear Information System (INIS)
Highlights: ? The DPE method predicts temperature and density profiles in a fusion reactor. ? This method is based on the gyro-Bohm type parameter dependence. ? The size of fusion reactor is determined to fulfill the power balance. ? The reactor size is proportional to a factor and ?4/3 power of the magnetic field. ? This factor can be a measure of plasma performance like the fusion triple product. - Abstract: A new method named direct profile extrapolation (DPE) has been developed to estimate the radial profiles of temperature and density in a fusion reactor. This method directly extrapolates the radial profiles observed in present experiments to the fusion reactor condition assuming gyro-Bohm type parameter dependence. The magnetohydrodynamic equilibrium that fits the experimental profile data is used to determine the plasma volume. Four enhancement factors for the magnetic field strength, the density, the plasma beta, and the energy confinement are assumed. Then, the plasma size is determined so as to fulfill the power balance in the reactor plasma. The plasma performance can be measured by an index, Cexp, introduced in the DPE method. The minimum magnetic stored energy of the fusion reactor to achieve self-ignition is shown to be proportional to the cube of Cexp and inversely proportional to the square of magnetic field strength. Using this method, the design window of a self-ignited fusion reactor that can be extrapolated from recent experimental results in the Large Helical Device (LHD) is considered. Also discussed is how large an enhancement is needed for the LHD experiment to ensure the helical reactor design of FFHR2m2.
Wilk-Zasadna, Iwona; Bernasconi, Camilla; Pelkonen, Olavi; Coecke, Sandra
2015-06-01
Early consideration of the multiplicity of factors that govern the biological fate of foreign compounds in living systems is a necessary prerequisite for the quantitative in vitro-in vivo extrapolation (QIVIVE) of toxicity data. Substantial technological advances in in vitro methodologies have facilitated the study of in vitro metabolism and the further use of such data for in vivo prediction. However, extrapolation to in vivo with a comfortable degree of confidence, requires continuous progress in the field to address challenges such as e.g., in vitro evaluation of chemical-chemical interactions, accounting for individual variability but also analytical challenges for ensuring sensitive measurement technologies. This paper discusses the current status of in vitro metabolism studies for QIVIVE extrapolation, serving today's hazard and risk assessment needs. A short overview of the methodologies for in vitro metabolism studies is given. Furthermore, recommendations for priority research and other activities are provided to ensure further widespread uptake of in vitro metabolism methods in 21st century toxicology. The need for more streamlined and explicitly described integrated approaches to reflect the physiology and the related dynamic and kinetic processes of the human body is highlighted i.e., using in vitro data in combination with in silico approaches. PMID:25456264
Pellenq, Roland J.-M.; Los, J.H.
2010-01-01
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 experi...
Cross-species extrapolation of chemical effects: Challenges and new insights
One of the greatest uncertainties in chemical risk assessment is extrapolation of effects from tested to untested species. While this undoubtedly is a challenge in the human health arena, species extrapolation is a particularly daunting task in ecological assessments, where it is...
Yurkin, Maxim A.; Maltsev, Valeri P.; Hoekstra, Alfons G.
2007-01-01
We propose an extrapolation technique that allows accuracy improvement of the discrete dipole approximation computations. The performance of this technique was studied empirically based on extensive simulations for 5 test cases using many different discretizations. The quality of the extrapolation improves with refining discretization reaching extraordinary performance especially for cubically shaped particles. A two order of magnitude decrease of error was demonstrated. We ...
Characterization of an extrapolation chamber in a 90Sr/90Y beta radiation field
International Nuclear Information System (INIS)
The extrapolation chamber is a parallel plate chamber and variable volume based on the Bragg-Gray theory. It determines in absolute mode, with high accuracy the dose absorbed by the extrapolation of the ionization current measured for a null distance between the electrodes. This camera is used for dosimetry of external beta rays for radiation protection. This paper presents the characterization of an extrapolation chamber in a 90Sr/90Y beta radiation field. The absorbed dose rate to tissue at a depth of 0.07 mm was calculated and is (0.13206±0.0028) ?Gy. The extrapolation chamber null depth was determined and its value is 60 ?m. The influence of temperature, pressure and humidity on the value of the corrected current was also evaluated. Temperature is the parameter that has more influence on this value and the influence of pressure and the humidity is not very significant. Extrapolation curves were obtained. (Author)
International Nuclear Information System (INIS)
A method previously suggested to calculate the correlation energy at the complete one-electron basis set limit by reassignment of the basis hierarchical numbers and use of the unified singlet- and triplet-pair extrapolation scheme is applied to a test set of 106 systems, some with up to 48 electrons. The approach is utilized to obtain extrapolated correlation energies from raw values calculated with second-order Møller-Plesset perturbation theory and the coupled-cluster singles and doubles excitations method, some of the latter also with the perturbative triples corrections. The calculated correlation energies have also been used to predict atomization energies within an additive scheme. Good agreement is obtained with the best available estimates even when the (d, t) pair of hierarchical numbers is utilized to perform the extrapolations. This conceivably justifies that there is no strong reason to exclude double-zeta energies in extrapolations, especially if the basis is calibrated to comply with the theoretical model
Balabin, Roman M; Smirnov, Sergey V
2012-04-01
Modern analytical chemistry of industrial products is in need of rapid, robust, and cheap analytical methods to continuously monitor product quality parameters. For this reason, spectroscopic methods are often used to control the quality of industrial products in an on-line/in-line regime. Vibrational spectroscopy, including mid-infrared (MIR), Raman, and near-infrared (NIR), is one of the best ways to obtain information about the chemical structures and the quality coefficients of multicomponent mixtures. Together with chemometric algorithms and multivariate data analysis (MDA) methods, which were especially created for the analysis of complicated, noisy, and overlapping signals, NIR spectroscopy shows great results in terms of its accuracy, including classical prediction error, RMSEP. However, it is unclear whether the combined NIR + MDA methods are capable of dealing with much more complex interpolation or extrapolation problems that are inevitably present in real-world applications. In the current study, we try to make a rather general comparison of linear, such as partial least squares or projection to latent structures (PLS); "quasi-nonlinear", such as the polynomial version of PLS (Poly-PLS); and intrinsically non-linear, such as artificial neural networks (ANNs), support vector regression (SVR), and least-squares support vector machines (LS-SVM/LSSVM), regression methods in terms of their robustness. As a measure of robustness, we will try to estimate their accuracy when solving interpolation and extrapolation problems. Petroleum and biofuel (biodiesel) systems were chosen as representative examples of real-world samples. Six very different chemical systems that differed in complexity, composition, structure, and properties were studied; these systems were gasoline, ethanol-gasoline biofuel, diesel fuel, aromatic solutions of petroleum macromolecules, petroleum resins in benzene, and biodiesel. Eighteen different sample sets were used in total. General conclusions are made about the applicability of ANN- and SVM-based regression tools in the modern analytical chemistry. The effectiveness of different multivariate algorithms is different when going from classical accuracy to robustness. Neural networks, which are capable of producing very accurate results with respect to classical RMSEP, are not able to solve interpolation problems or, especially, extrapolation problems. The chemometric methods that are based on the support vector machine (SVM) ideology are capable of solving both classical regression and interpolation/extrapolation tasks. PMID:22337290
Fuel cycle design for ITER and its extrapolation to DEMO
Energy Technology Data Exchange (ETDEWEB)
Konishi, Satoshi [Institute of Advanced Energy, Kyoto University, Kyoto 611-0011 (Japan)], E-mail: s-konishi@iae.kyoto-u.ac.jp; Glugla, Manfred [Forschungszentrum Karlsruhe, P.O. Box 3640, D 76021 Karlsruhe (Germany); Hayashi, Takumi [Apan Atomic Energy AgencyTokai, Ibaraki 319-0015 Japan (Japan)
2008-12-15
ITER is the first fusion device that continuously processes DT plasma exhaust and supplies recycled fuel in a closed loop. All the tritium and deuterium in the exhaust are recovered, purified and returned to the tokamak with minimal delay, so that extended burn can be sustained with limited inventory. To maintain the safety of the entire facility, plant scale detritiation systems will also continuously run to remove tritium from the effluents at the maximum efficiency. In this entire tritium plant system, extremely high decontamination factor, that is the ratio of the tritium loss to the processing flow rate, is required for fuel economy and minimized tritium emissions, and the system design based on the state-of-the-art technology is expected to satisfy all the requirements without significant technical challenges. Considerable part of the fusion tritium system will be verified with ITER and its decades of operation experiences. Toward the DEMO plant that will actually generate energy and operate its closed fuel cycle, breeding blanket and power train that caries high temperature and pressure media from the fusion device to the generation system will be the major addition. For the tritium confinement, safety and environmental emission, particularly blanket, its coolant, and generation systems such as heat exchanger, steam generator and turbine will be the critical systems, because the tritium permeation from the breeder and handling large amount of high temperature, high pressure coolant will be further more difficult than that required for ITER. Detritiation of solid waste such as used blanket and divertor will be another issue for both tritium economy and safety. Unlike in the case of ITER that is regarded as experimental facility, DEMO will be expected to demonstrate the safety, reliability and social acceptance issue, even if economical feature is excluded. Fuel and environmental issue to be tested in the DEMO will determine the viability of the fusion as a future energy source. Some of the subjects cannot be expected to be within the extrapolation of ITER technology and require long term efforts paralleling ITER.
Montiel, Ariadna; Sendra, Irene; Escamilla-Rivera, Celia; Salzano, Vincenzo
2014-01-01
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...
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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)
Schuddeboom, W; Wübbenhorst, Michael
1996-01-01
A model has been constructed to describe ball-bond corrosion in HTSL stress testing. In this model ion-mobility has been believed to be the rate determining step and has been found to be non-linear for the anti-popcorn plastic. In HTSL testing an Arrhenius type extrapolation of the mean-time to failure (MTTF) at high temperature has been used, to predict the value at lower temperatures. This method proves to be correct for a low-stress plastic. However possibly it underestimates the value for...
Faria, F. P.; Reynaldo, S.; Fonseca, T. C. F.; Lacerda, M. A. S.; Da Silva, T. A.
2015-11-01
An extrapolation chamber is a parallel-plate ionization chamber with an adjustable air-cavity volume through the variation of the distance between the collecting electrode and the entrance foil. The measured ionization currents can be obtained for different chamber depths, and extrapolated towards zero chamber depth. In this work, results of Monte Carlo simulations using MCNP5 and MCNPX codes are reported for 90Sr/90Y and 85Kr beta radiation spectra incident on a 23392 model PTW extrapolation chamber. The results for transmission factor, absorbed dose rate in tissue as well as the chamber response as a function of the chamber depth are in good agreement with experimental data.
International Nuclear Information System (INIS)
In this paper, we apply Aitken extrapolation and epsilon algorithm as acceleration technique for the solution of a weakly singular nonlinear Volterra integral equation of the second kind. In this paper, based on Tao and Yong (2006 J. Math. Anal. Appl. 324 225-37.) the integral equation is solved by Navot's quadrature formula. Also, Tao and Yong (2006) for the first time applied Richardson extrapolation to accelerating convergence for the weakly singular nonlinear Volterra integral equations of the second kind. To our knowledge, this paper may be the first attempt to apply Aitken extrapolation and epsilon algorithm for the weakly singular nonlinear Volterra integral equations of the second kind.
Effect of extrapolation length on the phase transformation of epitaxial ferroelectric thin films
International Nuclear Information System (INIS)
Effects of extrapolation length on the phase transformation of epitaxial ferroelectric thin films on dissimilar cubic substrates have been studied on the basis of the mean-field Landau-Ginzburg-Devonshire (LGD) thermodynamic theory by taking an uneven distribution of the interior stress with thickness into account. It was found that the polarization of epitaxial ferroelectric thin films is strongly dependent on the extrapolation length of films. The physical origin of the extrapolation length during the phase transformation from paraelectric to ferroelectric was revealed in the case of ferroelectric thin films
Quantitative in vitro-to-in vivo extrapolation in a high-throughput environment.
Wetmore, Barbara A
2015-06-01
High-throughput in vitro toxicity screening provides an efficient way to identify potential biological targets for environmental and industrial chemicals while conserving limited testing resources. However, reliance on the nominal chemical concentrations in these in vitro assays as an indicator of bioactivity may misrepresent potential in vivo effects of these chemicals due to differences in clearance, protein binding, bioavailability, and other pharmacokinetic factors. Development of high-throughput in vitro hepatic clearance and protein binding assays and refinement of quantitative in vitro-to-in vivo extrapolation (QIVIVE) methods have provided key tools to predict xenobiotic steady state pharmacokinetics. Using a process known as reverse dosimetry, knowledge of the chemical steady state behavior can be incorporated with HTS data to determine the external in vivo oral exposure needed to achieve internal blood concentrations equivalent to those eliciting bioactivity in the assays. These daily oral doses, known as oral equivalents, can be compared to chronic human exposure estimates to assess whether in vitro bioactivity would be expected at the dose-equivalent level of human exposure. This review will describe the use of QIVIVE methods in a high-throughput environment and the promise they hold in shaping chemical testing priorities and, potentially, high-throughput risk assessment strategies. PMID:24907440
Melting of “non-magic” argon clusters and extrapolation to the bulk limit
International Nuclear Information System (INIS)
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
Can Tauc plot extrapolation be used for direct-band-gap semiconductor nanocrystals?
Energy Technology Data Exchange (ETDEWEB)
Feng, Y., E-mail: yu.feng@unsw.edu.au; Lin, S.; Huang, S.; Shrestha, S.; Conibeer, G. [School of Photovoltaic and Renewable Energy Engineering, UNSW Australia, Sydney, NSW 2052 (Australia)
2015-03-28
Despite that Tauc plot extrapolation has been widely adopted for extracting bandgap energies of semiconductors, there is a lack of theoretical support for applying it to nanocrystals. In this paper, direct-allowed optical transitions in semiconductor nanocrystals have been formulated based on a purely theoretical approach. This result reveals a size-dependant transition of the power factor used in Tauc plot, increasing from one half used in the 3D bulk case to one in the 0D case. This size-dependant intermediate value of power factor allows a better extrapolation of measured absorption data. Being a material characterization technique, the generalized Tauc extrapolation gives a more reasonable and accurate acquisition of the intrinsic bandgap, while the unjustified purpose of extrapolating any elevated bandgap caused by quantum confinement is shown to be incorrect.
Melting of “non-magic” argon clusters and extrapolation to the bulk limit
Energy Technology Data Exchange (ETDEWEB)
Senn, Florian, E-mail: f.senn@massey.ac.nz; Wiebke, Jonas; Schumann, Ole; Gohr, Sebastian; Schwerdtfeger, Peter, E-mail: p.a.schwerdtfeger@massey.ac.nz [Centre for Theoretical Chemistry and Physics, The New Zealand Institute for Advanced Study, Massey University Albany, Private Bag 102904, Auckland 0745 (New Zealand); Pahl, Elke, E-mail: e.pahl@massey.ac.nz [Centre for Theoretical Chemistry and Physics, Institute of Natural and Mathematical Sciences, Massey University Albany, Private Bag 102904, Auckland 0745 (New Zealand)
2014-01-28
The melting of argon clusters Ar{sub N} 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.
Can Tauc plot extrapolation be used for direct-band-gap semiconductor nanocrystals?
International Nuclear Information System (INIS)
Despite that Tauc plot extrapolation has been widely adopted for extracting bandgap energies of semiconductors, there is a lack of theoretical support for applying it to nanocrystals. In this paper, direct-allowed optical transitions in semiconductor nanocrystals have been formulated based on a purely theoretical approach. This result reveals a size-dependant transition of the power factor used in Tauc plot, increasing from one half used in the 3D bulk case to one in the 0D case. This size-dependant intermediate value of power factor allows a better extrapolation of measured absorption data. Being a material characterization technique, the generalized Tauc extrapolation gives a more reasonable and accurate acquisition of the intrinsic bandgap, while the unjustified purpose of extrapolating any elevated bandgap caused by quantum confinement is shown to be incorrect
Standardization of 131I by 4 ??-? anti-coincidence method
International Nuclear Information System (INIS)
This work applies 4 ??-? anti-coincidence method, which scarcely need to do efficiency extrapolation, at the same time shorten the measurement process, thus reduced the effects of extrapolation, at the same time shorten the measurement process, thus reduced the effects of extrapolation and half-life corrections. The combined standard uncertainty is about 0.3%
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
Dienes, Keith R.; Lennek, Michael
2005-01-01
In this paper, we discuss the important question of how to extrapolate a given zero-temperature string model to finite temperature. It turns out that this issue is surprisingly subtle, and we show that many of the standard results require modification. For concreteness, we focus on the case of the ten-dimensional SO(32) heterotic string, and show that the usual finite-temperature extrapolation for this string is inconsistent at the level of a proper worldsheet theory. We the...
Fabiano, E.; della Sala, F.
2012-01-01
We construct a reference benchmark set for atomic and molecular random-phase-approximation (RPA) correlation energies in a density functional theory (DFT) framework at the complete basis set limit. This set is used to evaluate the accuracy of some popular extrapolation schemes for RPA all-electron molecular calculations. The results indicate that for absolute energies accurate results, clearly outperforming raw data, are achievable with two-point extrapolation schemes based ...
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.
International Nuclear Information System (INIS)
Recent investigations on mechanisms of carcinogenesis have demonstrated important quantitative relationships between the induction of neoplasia, the molecular dose of promutagenic DNA adducts and their efficiency for causing base-pair mismatch, and the extent of cell proliferation in target organ. These factors are involved in the multistage process of carcinogenesis, including initiation, promotion, and progression. The molecular dose of DNA adducts can exhibit supralinear, linear, or sublinear relationships to external dose due to differences in absorption, biotransformation, and DNA repair at high versus low doses. In contrast, increased cell proliferation is a common phenomena that is associated with exposures to relatively high doses of toxic chemicals. As such, it enhances the carcinogenic response at high doses, but has little effect at low doses. Since data on cell proliferation can be obtained for any exposure scenario and molecular dosimetry studies are beginning to emerge on selected chemical carcinogens, methods are needed so that these critical factors can be utilized in extrapolation from high to low doses and across species. The use of such information may provide a scientific basis for quantitative risk assessment
Extrapolation and minimization procedures for the PageRank vector
Brezinski, Claude; Redivo-Zaglia, Michela
2007-01-01
An important problem in Web search is to determine the importance of each page. This problem consists in computing, by the power method, the left principal eigenvector (the PageRank vector) of a matrix depending on a parameter $c$ which has to be chosen close to 1. However, when $c$ is close to 1, the problem is ill-conditioned, and the power method converges slowly. So, the idea developed in this paper consists in computing the PageRank vector for several values of $c$, ...
Rank regularization and Bayesian inference for tensor completion and extrapolation
Bazerque, Juan Andres; Mateos, Gonzalo; Giannakis, Georgios B.
2013-01-01
A novel regularizer of the PARAFAC decomposition factors capturing the tensor's rank is proposed in this paper, as the key enabler for completion of three-way data arrays with missing entries. Set in a Bayesian framework, the tensor completion method incorporates prior information to enhance its smoothing and prediction capabilities. This probabilistic approach can naturally accommodate general models for the data distribution, lending itself to various fitting criteria that...
Developing and utilizing the wavefield kinematics for efficient wavefield extrapolation
Waheed, Umair bin
2015-08-01
Natural gas and oil from characteristically complex unconventional reservoirs, such as organic shale, tight gas and oil, coal-bed methane; are transforming the global energy market. These conventional reserves exist in complex geologic formations where conventional seismic techniques have been challenged to successfully image the subsurface. To acquire maximum benefits from these unconventional reserves, seismic anisotropy must be at the center of our modeling and inversion workflows. I present algorithms for fast traveltime computations in anisotropic media. Both ray-based and finite-difference solvers of the anisotropic eikonal equation are developed. The proposed algorithms present novel techniques to obtain accurate traveltime solutions for anisotropic media in a cost-efficient manner. The traveltime computation algorithms are then used to invert for anisotropy parameters. Specifically, I develop inversion techniques by using diffractions and diving waves in the seismic data. The diffraction-based inversion algorithm can be combined with an isotropic full-waveform inversion (FWI) method to obtain a high-resolution model for the anellipticity anisotropy parameter. The inversion algorithm based on diving waves is useful for building initial anisotropic models for depth-migration and FWI. I also develop the idea of \\'effective elliptic models\\' for obtaining solutions of the anisotropic two-way wave equation. The proposed technique offers a viable alternative for wavefield computations in anisotropic media using a computationally cheaper wave propagation operator. The methods developed in the thesis lead to a direct cost savings for imaging and inversion projects, in addition to a reduction in turn-around time. With an eye on the next generation inversion methods, these techniques allow us to incorporate more accurate physics into our modeling and inversion framework.
Extrapolation of animal radionuclide retention data to man: Use of similarity ratios
International Nuclear Information System (INIS)
A major problem in toxicology is the need for testing a myriad possible substances on several animal species as an aid in establishing standards for man. Particular interest in the problem of extrapolation to man is linked to a need for a method of obtaining transfer coefficients in food-chain models of ecosystems. Such a method could circumvent the necessity to test many species and compounds. Because of their particular interest in radioecology, the authors' studies were initiated using radionuclide retention data available in the literature. Since radionuclide retention should be a function of metabolism it follows that direct or indirect measures could be described by a ''power law'' based on body weight of the organism(s). However, when such power laws have been extended to interspecies comparisons the resulting power coefficients are usually substantially less than the value anticipated and seem to be different for each radionuclide. This paper proposes that interspecies comparisons ought to be based on the proportionality coefficient rather than the power parameter of the power function model and have called pairwise comparisons amongst species ''similarity ratios''. Retention data were examined from five non-ruminant species (including man) where several radionuclides with different physical properties were fed. Subsequently an expression was devised whereby an estimate of biological equilibrium level in man could be calculated using similar estimates from experiments using mice, rats or dogs. There are some statistical questions to resolve which have to do with the assumed frequency distribution for estimates of the proportionality coefficient. In addition, repeated use was made of the same data sets. (author)
Mean field extrapolations of microscopic nuclear equations of state
Rrapaj, Ermal; Holt, Jeremy W
2015-01-01
We explore the use of mean field models to approximate microscopic nuclear equations of state derived from chiral effective field theory across the densities and temperatures relevant for simulating astrophysical phenomena such as core-collapse supernovae and binary neutron star mergers. We consider both relativistic mean field theory with scalar and vector meson exchange as well as energy density functionals based on Skyrme phenomenology and compare to thermodynamic equations of state derived from chiral two- and three-nucleon forces in many-body perturbation theory. Quantum Monte Carlo simulations of symmetric nuclear matter and pure neutron matter are used to determine the density regimes in which perturbation theory with chiral nuclear forces is valid. Within the theoretical uncertainties associated with the many-body methods, we find that select mean field models describe well microscopic nuclear thermodynamics. As an additional consistency requirement, we study as well the single-particle properties of ...
Possible sharp quantization of extrapolated high temperature viscosity- theory and experiment
Nussinov, Z; Blodgett, M; Kelton, K F
2014-01-01
Quantum effects in material systems are often pronounced at low energies and become insignificant at high temperatures. We find that, perhaps counterintuitively, certain quantum effects may follow the opposite route and become progressively sharper when extrapolated to the "classical" high temperature limit. In the current work, we derive basic relations, extend standard kinetic theory by taking into account a possible fundamental quantum time scale, find new general equalities connecting semi-classical dynamics and thermodynamics to Planck's constant, and compute current correlation functions. Our analysis suggests that, on average, the extrapolated high temperature viscosity of general liquids may tend to a value set by the product of the particle number density ${\\sf n}$ and Planck's constant $h$. We compare this theoretical result with experimental measurements of an ensemble of 23 metallic fluids where this seems to indeed be the case. The extrapolated high temperature viscosity of each of these liquids ...
Comparison between the response of two extrapolation chambers in low energy X-rays
International Nuclear Information System (INIS)
Full text: Extrapolation chambers are important metrological instruments for detection of beta radiation and low energy X-rays, since they are able to determine absolute measurements of radiations of soft penetration. These chambers are very useful, because they allow the determination of superficial doses through the variation of the air mass in its sensible volume. In this work, two extrapolation chambers were tested in order to establish which chamber presents the best response in some standard qualities of X-ray beams, radiotherapy level. For comparison, a commercial PTW extrapolation chamber model 23391 and an extrapolation chamber designed and constructed at the Radiation Metrology Laboratory of Instituto de Pesquisas Energeticas e Nucleares, were studied. The commercial chamber has a collecting electrode (40 mm diameter) and guard rings made of aluminum, and entrance window (0.025 mm thick) made of polyamide; the developed chamber presents a collecting electrode (10 mm diameter) and guard rings made of graphite, and entrance window (0,84 mg/cm2 thick) made of aluminized polyethylene terephthalate. Both chambers were positioned at 50 cm from the X-ray system focus. The ionization currents were measured at negative and positive polarities, and the mean values were considered. A Keithley 617 electrometer was utilized. The main characteristics of the extrapolation chambers, as ion collection efficiency, saturation curve, polarity effect, repeatability, long time stability, stabilization time, linearity response, extrapolation curve, energy dependency, and transmission factors were determined. The results show that both chambers present adequate responses for the verified X-ray beam qualities, confirming previous studies realized with these detectors. In conclusion, both chambers can be used for accurate measurements in low energy X-ray beams. (author)
EFFECTS OF PARTITIONING AND EXTRAPOLATION ON THE CONNECTIVITY OF POTENTIAL MAGNETIC FIELDS
International Nuclear Information System (INIS)
Coronal magnetic field may be characterized by how its field lines interconnect regions of opposing photospheric flux-its connectivity. Connectivity can be quantified as the net flux connecting pairs of opposing regions, once such regions are identified. One existing algorithm will partition a typical active region into a number of unipolar regions ranging from a few dozen to a few hundred, depending on algorithmic parameters. This work explores how the properties of the partitions depend on some algorithmic parameters, and how connectivity depends on the coarseness of partitioning for one particular active region magnetogram. We find the number of connections among them scales with the number of regions even as the number of possible connections scales with its square. There are several methods of generating a coronal field, even a potential field. The field may be computed inside conducting boundaries or over an infinite half-space. For computation of connectivity, the unipolar regions may be replaced by point sources or the exact magnetogram may be used as a lower boundary condition. Our investigation shows that the connectivities from these various fields differ only slightly-no more than 15%. The greatest difference is between fields within conducting walls and those in the half-space. Their connectivities grow more different as finer partitioning creates more source regions. This also gives a quantitative means of establishing how far away conducting boundaries must be placed in order not to significantly affect the extrapolation. For identical outer boundaries, the use of point sources instead of the exact magnetogram makes a smaller difference in connectivity: typically 6% independent of the number of source regions.
International Nuclear Information System (INIS)
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. (orig.)
Amore, Paolo; Fernandez, Francisco M; Rösler, Boris
2015-01-01
We apply second order finite difference to calculate the lowest eigenvalues of the Helmholtz equation, for complicated non-tensor domains in the plane, using different grids which sample exactly the border of the domain. We show that the results obtained applying Richardson and Pad\\'e-Richardson extrapolation to a set of finite difference eigenvalues corresponding to different grids allows to obtain extremely precise values. When possible we have assessed the precision of our extrapolations comparing them with the highly precise results obtained using the method of particular solutions. Our empirical findings suggest an asymptotic nature of the FD series. In all the cases studied, we are able to report numerical results which are more precise than those available in the literature.
Study of the vortex conditions of wings with large sweepback by extrapolation of the Jones method
Hirsch, P.
1980-01-01
The pockets of separation originating on the leading edges are surrounded by vortex sheets. Their configuration and intensity were determined by four conditions with the JONES approximation, which is itself corrected by a simple logic. Field pressures and stresses were computed for different cases and are compared with test results (pure deltas, swallow tails, truncations, strakes, ducks, fuselage).
Czech Academy of Sciences Publication Activity Database
Stupakov, Oleksandr
2006-01-01
Ro?. 307, - (2006), s. 279-287. ISSN 0304-8853 R&D Projects: GA AV ?R(CZ) 1QS100100508 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnetic measurement * open magnetic sample * surface field determination * single-yoke setup * magnetic non-destructive testing Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.212, year: 2006
Extrapolation method of the elimination of instrumental broadening of diffraction lines.
Czech Academy of Sciences Publication Activity Database
?er?anský, Marian
2000-01-01
Ro?. 7, ?. 1 (2000), s. 3-5. ISSN 1211-5894 Institutional research plan: CEZ:AV0Z1010914 Keywords : XRD line brodening * instrumental broadening * powder diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism
Czech Academy of Sciences Publication Activity Database
Mejsnar, Jan; Sokol, Zbyn?k; Pešice, Petr
Oberpfaffenhofen-Wessling : Institut für Physik der Atmosphäre, 2014. [ERAD 2014 - 8th European Conference on Radar in Meteorology and Hydrology. 01.09.2014-05.09.2014, Garmisch-Partenkirchen] Institutional support: RVO:68378289 Subject RIV: DG - Athmosphere Sciences, Meteorology http://www.pa.op.dlr.de/erad2014/programme/ShortAbstracts/262_short.pdf
Latychevskaia, Tatiana; Zontone, Federico; Fink, Hans-Werner
2015-01-01
We demonstrate enhancement in resolution of a noncrystalline object reconstructed from an experimental X-ray diffraction pattern by extrapolating the measured diffraction intensities beyond the detector area. The experimental record contains about 10% missing information, including the pixels in the center of the diffraction pattern. The extrapolation is done by applying an iterative routine. The optimal parameters for implementing the iterative routine, including initial padding distribution and an object support, are studied. Extrapolation results in resolution enhancement and better matching between the recovered and experimental amplitudes in the Fourier domain. The limits of the extrapolation procedure are discussed.
Rong, Lu; Wang, Dayong; Zhou, Xun; Huang, Haochong; Li, Zeyu; Wang, Yunxin
2014-01-01
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.
Rudenko, G V
2000-01-01
This paper is concerned with the Laplace boundary-value problem with the directional derivative, corresponding to the specific nature of measurements of the longitudinal component of the photospheric magnetic field. Boundary conditions are specified by a distribution on the sphere of projection of the magnetic field vector unto a given direction. It is shown that the solution of this problem exists in the form of a spherical harmonic expansion, and uniqueness of this solution is proved. A conceptual sketch of numerical determination of the harmonic series coefficients is given. The field of application of the method is analyzed having regard to the peculiarities of actual data. Finally, we present differences in results derived from extrapolating the magnetic field from a synoptic map and a full-disk magnetogram.
International Nuclear Information System (INIS)
The absorbed dose for equivalent soft tissue is determined,it is imparted by ophthalmologic applicators, (90 Sr/90 Y, 1850 MBq) using an extrapolation chamber of variable electrodes; when estimating the slope of the extrapolation curve using a simple lineal regression model is observed that the dose values are underestimated from 17.7 percent up to a 20.4 percent in relation to the estimate of this dose by means of a regression model polynomial two grade, at the same time are observed an improvement in the standard error for the quadratic model until in 50%. Finally the global uncertainty of the dose is presented, taking into account the reproducibility of the experimental arrangement. As conclusion it can infers that in experimental arrangements where the source is to contact with the extrapolation chamber, it was recommended to substitute the lineal regression model by the quadratic regression model, in the determination of the slope of the extrapolation curve, for more exact and accurate measurements of the absorbed dose. (Author)
Potential Hydraulic Modelling Errors Associated with Rheological Data Extrapolation in Laminar Flow
International Nuclear Information System (INIS)
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
Buckler, Denny R., Foster L. Mayer, Mark R. Ellersieck and Amha Asfaw. 2003. Evaluation of Minimum Data Requirements for Acute Toxicity Value Extrapolation with Aquatic Organisms. EPA/600/R-03/104. U.S. Environmental Protection Agency, National Health and Environmental Effects Re...
Kinetic energy of solid neon by Monte Carlo with improved Trotter- and finite-size extrapolation
Cuccoli, Alessandro; Macchi, Alessandro; Pedrolli, Gaia; Tognetti, Valerio; Vaia, Ruggero
1997-01-01
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.
Nowcasting of precipitation by an NWP model using assimilation of extrapolated radar reflectivity.
Czech Academy of Sciences Publication Activity Database
Sokol, Zbyn?k; Zacharov, Petr, jr.
2012-01-01
Ro?. 138, ?. 665 (2012), s. 1072-1082. ISSN 0035-9009 Institutional support: RVO:68378289 Keywords : precipitation forecast * radar extrapolation Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 3.327, year: 2012 http://onlinelibrary.wiley.com/doi/10.1002/qj.970/abstract
The human brain's algorithm for extrapolating motion, and its possible gender-dependence.
Ehrlich, Robert
2005-02-01
Some athletes accomplish feats requiring a timing accuracy 100 times better than their reaction time. This capability implies that the brain can accurately extrapolate the motion of objects. We hypothesize that the brain uses a simple algorithm to accomplish this extrapolation, and that the algorithm is influenced by the subject's gender and recent observations of motion. We describe an experiment in timing the motion of a dot across a computer screen designed to discover the motion extrapolation algorithm. Different types of motion of the dot were studied. The experiment was conducted with 126 college students (two-thirds female), who each performed 1000 trials. By using as many as 126,000 trials, the random noise inherent in individual trials averages out, allowing the underlying algorithm to be revealed. The results show that motion extrapolation is done using the average velocity of a moving object with no correction for changes in velocity during the motion, but with an ad hoc adjustment based on recently observed motions and on gender-males having on average a smaller error than females. A future controlled experiment will be needed to establish whether the observed gender difference is due to the greater experience of males with such related tasks as video games and sports. PMID:15631893
DEFF Research Database (Denmark)
Kissling, W. Daniel; Dalby, Lars
2014-01-01
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 species’ 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 (“MammalDIET”). 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 (“Animal”, “Mammal”, “Invertebrate”, “Plant”, “Seed”, “Fruit”, and “Leaf”) 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.
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.
Energy Technology Data Exchange (ETDEWEB)
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
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.
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.
Directory of Open Access Journals (Sweden)
S. Y. Su
2012-07-01
Full Text Available Spatial extrapolation has become a sine qua non and an ad hoc major research focus in applied ecology in the latter half 20th century. Progressive innovations in data acquisition and processing technologies over the last few decades, especially in the fields of 3S (RS, GIS and GPS and statistical modeling method, have greatly enhanced ecologists' capacity to face the challenge by enabling them to to describe patterns in nature over larger spatial scales and a greater level of details than ever before. Elaeocarpus japonicas (Japanese Elaeocarpus tree, JET was selected for applying in the concurrent developed technology, such as ecological distribution modeling and ecological extrapolation. The GPS-located JET samples were introduced in a GIS for overlaying with five environmental layers (elevation, slope, aspect, terrain position and vegetation index derived from two-date SPOT-5 images for ecological information extraction and model building. We created three sampling designs (SD, Tong-Feng samples for SD1, Kuan-Dau samples for SD2, and the merge of the two former datasets for SD3, according to watersheds, and the three SDs were used individually to test the extrapolation ability of predictive models. The results of the two-way extrapolation indicated it is hard to extend the predicted distribution patterns through different watersheds. The main reasons resulting in this outcome were the difference in microclimate and micro-terrain between these two watersheds. Consequently, the models built with SD3 were the more robust. The information of vegetation index in this study poorly improved the models, so we will adopt the hyperspectral data to overcome the shortage of the SPOT-5 images.
Approaches for extrapolating in vitro toxicity testing results for prediction of human in vivo outcomes are needed. The purpose of this case study was to employ in vitro toxicokinetics and PBPK modeling to perform in vitro to in vivo extrapolation (IVIVE) of lindane neurotoxicit...
Directory of Open Access Journals (Sweden)
Dalila Khalfa
2014-01-01
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.
{sup 131}I-SPGP internal dosimetry: animal model and human extrapolation
Energy Technology Data Exchange (ETDEWEB)
Andrade, Henrique Martins de; Ferreira, Andrea Vidal; Soprani, Juliana; Santos, Raquel Gouvea dos [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN-CNEN-MG), Belo Horizonte, MG (Brazil)], e-mail: hma@cdtn.br; Figueiredo, Suely Gomes de [Universidade Federal do Espirito Santo, (UFES), Vitoria, ES (Brazil). Dept. de Ciencias Fisiologicas. Lab. de Quimica de Proteinas
2009-07-01
Scorpaena plumieri is commonly called moreia-ati or manganga and is the most venomous and one of the most abundant fish species of the Brazilian coast. Soprani 2006, demonstrated that SPGP - an isolated protein from S. plumieri fish- possess high antitumoral activity against malignant tumours and can be a source of template molecules for the development (design) of antitumoral drugs. In the present work, Soprani's {sup 125}ISPGP biokinetic data were treated by MIRD formalism to perform Internal Dosimetry studies. Absorbed doses due to the {sup 131}I-SPGP uptake were determinate in several organs of mice, as well as in the implanted tumor. Doses obtained for animal model were extrapolated to humans assuming a similar ratio for various mouse and human tissues. For the extrapolation, it was used human organ masses from Cristy/Eckerman phantom. Both penetrating and non-penetrating radiation from {sup 131}I were considered. (author)
Electric form factors of the octet baryons from lattice QCD and chiral extrapolation
Energy Technology Data Exchange (ETDEWEB)
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
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.
131I-CRTX internal dosimetry: animal model and human extrapolation
International Nuclear Information System (INIS)
Snake venoms molecules have been shown to play a role not only in the survival and proliferation of tumor cells but also in the processes of tumor cell adhesion, migration and angiogenesis. 125I-Crtx, a radiolabeled version of a peptide derived from Crotalus durissus terrificus snake venom, specifically binds to tumor and triggers apoptotic signalling. At the present work, 125I-Crtx biokinetic data (evaluated in mice bearing Erlich 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 131I-Crtx. 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 131I in the tissue were considered in dose calculations. (author)
{sup 131}I-CRTX internal dosimetry: animal model and human extrapolation
Energy Technology Data Exchange (ETDEWEB)
Andrade, Henrique Martins de; Ferreira, Andrea Vidal; Soares, Marcella Araugio; Silveira, Marina Bicalho; Santos, Raquel Gouvea dos [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN-CNEN-MG), Belo Horizonte, MG (Brazil)], e-mail: hma@cdtn.br
2009-07-01
Snake venoms molecules have been shown to play a role not only in the survival and proliferation of tumor cells but also in the processes of tumor cell adhesion, migration and angiogenesis. {sup 125}I-Crtx, a radiolabeled version of a peptide derived from Crotalus durissus terrificus snake venom, specifically binds to tumor and triggers apoptotic signalling. At the present work, {sup 125}I-Crtx biokinetic data (evaluated in mice bearing Erlich 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 131}I-Crtx. 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 131}I in the tissue were considered in dose calculations. (author)
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.
DEFF Research Database (Denmark)
Thorndahl, Søren Liedtke; Grum, M.; Rasmussen, Michael R.; Schaarup-Jensen, Kjeld
2011-01-01
Forecasting of flows, overflow volumes, water levels, etc. in drainage systems can be applied in real time control of drainage systems in the future climate in order to fully utilize system capacity and thus save possible construction costs. An online system for forecasting flows and water levels in a small urban catchment has been developed. The forecast is based on application of radar rainfall data, which by a correlation based technique, is extrapolated with a lead time up to two hours. The ...
Measurements of surface dose using build-up curves obtained with an extrapolation chamber
International Nuclear Information System (INIS)
Surface dose was measured in an extrapolation chamber and was found to be less than previously reported. The slope of the build-up curve was less steep with the Clinac 4 than with 60Co and much steeper with the Clinac 35 at 25 MV than with the betatron at the same energy. The gradient of the depth-dose curve in the build-up region is probably the best indicator of skin damage. (U.S.)
Moura, A A
2002-01-01
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 expression for the energy release.
Moura, A.; V.I. Yukalov
2003-01-01
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...
Practical band-limited extrapolation relying on Slepian series and compressive sampling
Gosse, Laurent
2010-01-01
We consider a rather simple algorithm to address the fascinating field of numerical extrapolation of (analytic) band-limited functions. It relies on two main elements: namely, the lower frequencies are treated by projecting the known part of the signal to be extended onto the space generated by ``Prolate Spheroidal Wave Functions" (PSWF, as originally proposed by Slepian), whereas the higher ones can be handled by the recent so--called ``Compressive Sampling" (CS, proposed by Candès) algorith...
Extrapolation-Based Path Invariants for Abstraction Refinement of Fifo Systems
Heußner, Alexander; Sutre, Grégoire; Le Gall, Tristan
2009-01-01
The technique of counterexample-guided abstraction refinement (CEGAR) has been successfully applied in the areas of software and hardware verification. Automatic abstraction refinement is also desirable for the safety verification of complex infinite-state models. This paper investigates CEGAR in the context of formal models of network protocols, in our case, the verification of FIFO systems. Our main contribution is the introduction of extrapolation-based path invariants for abstraction refi...
Méthodologie de l'extrapolation des réacteurs chimiques Methodology for Scaling Up Chemical Reactors
Trambouze P.
2006-01-01
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....
Zhang, Yan-Bin; Sun, Wei-Min; Lü, Xiao-Fu; Zong, Hong-Shi
2009-08-01
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.
A New Code for Nonlinear Force-Free Field Extrapolation of the Global Corona
Jiang, Chaowei; Feng, Xueshang; Xiang, Changqing
2012-01-01
Reliable measurements of the solar magnetic field are still restricted to the photosphere, and our present knowledge of the three-dimensional coronal magnetic field is largely based on extrapolation from photospheric magnetogram using physical models, e.g., the nonlinear force-free field (NLFFF) model as usually adopted. Most of the currently available NLFFF codes have been developed with computational volume like Cartesian box or spherical wedge while a global full-sphere e...
Limitations of force-free magnetic field extrapolations: revisiting basic assumptions
Peter, H; Chitta, L P; Cameron, R H
2015-01-01
Force-free extrapolations are widely used to study the magnetic field in the solar corona based on surface measurements. The extrapolations assume that the ratio of internal energy of the plasma to magnetic energy, the plasma-beta is negligible. Despite the widespread use of this assumption observations, models, and theoretical considerations show that beta is of the order of a few percent to more than 10%, and thus not small. We investigate what consequences this has for the reliability of extrapolation results. We use basic concepts starting with the force and the energy balance to infer relations between plasma-beta and free magnetic energy, to study the direction of currents in the corona with respect to the magnetic field, and to estimate the errors in the free magnetic energy by neglecting effects of the plasma (beta<<1). A comparison with a 3D MHD model supports our basic considerations. If plasma-beta is of the order of the relative free energy (the ratio of the free magnetic energy to the total...
Choi, Youngchol; Chun, Joohwan; Bae, Jinho
2011-04-25
The discrete layer-peeling algorithm (DLPA) requires to discretize the continuous medium into discrete reflectors to synthesize nonuniform fiber Bragg gratings (FBG), and the discretization step of this discrete model should be sufficiently small for synthesis with high accuracy. However, the discretization step cannot be made arbitrarily small to decrease the discretization error, because the number of multiplications needed with the DLPA is proportional to the inverse square of the layer thickness. We propose a numerically extrapolated time domain DLPA (ETDLPA) to resolve this tradeoff between the numerical accuracy and the computational complexity. The accuracy of the proposed ETDLPA is higher than the conventional time domain DLPA (TDLPA) by an order of magnitude or more, with little computational overhead. To be specific, the computational efficiency of the ETDLPA is achieved through numerical extrapolation, and each addition of the extrapolation depth improves the order of accuracy by one. Therefore, the ETDLPA provides us with computationally more efficient and accurate methodology for the nonuniform FBG synthesis than the TDLPA. PMID:21643075
Testing magnetofrictional extrapolation with the Titov-Démoulin model of solar active regions
Valori, G.; Kliem, B.; Török, T.; Titov, V. S.
2010-09-01
We examine the nonlinear magnetofrictional extrapolation scheme using the solar active region model by Titov and Démoulin as test field. This model consists of an arched, line-tied current channel held in force-free equilibrium by the potential field of a bipolar flux distribution in the bottom boundary. A modified version with a parabolic current density profile is employed here. We find that the equilibrium is reconstructed with very high accuracy in a representative range of parameter space, using only the vector field in the bottom boundary as input. Structural features formed in the interface between the flux rope and the surrounding arcade - “hyperbolic flux tube” and “bald patch separatrix surface” - are reliably reproduced, as are the flux rope twist and the energy and helicity of the configuration. This demonstrates that force-free fields containing these basic structural elements of solar active regions can be obtained by extrapolation. The influence of the chosen initial condition on the accuracy of reconstruction is also addressed, confirming that the initial field that best matches the external potential field of the model quite naturally leads to the best reconstruction. Extrapolating the magnetogram of a Titov-Démoulin equilibrium in the unstable range of parameter space yields a sequence of two opposing evolutionary phases, which clearly indicate the unstable nature of the configuration: a partial buildup of the flux rope with rising free energy is followed by destruction of the rope, losing most of the free energy.
International Nuclear Information System (INIS)
Purpose: Currently there is no primary calibration standard for determining the absorbed dose rate-to-water at the surface of ?-emitting concave ophthalmic applicators and plaques. Machining tolerances involved in the design of concave window extrapolation chambers are a limiting factor for development of such a standard. Use of a windowless extrapolation chamber avoids these window-machining tolerance issues. As a windowless extrapolation chamber has never been attempted, this work focuses on proof of principle measurements with a planar, windowless extrapolation chamber to verify the accuracy in comparison to initial calibration, which could be extended to the design of a hemispherical, windowless extrapolation chamber. Methods: The window of an extrapolation chamber defines the electrical field, aids in aligning the source parallel to the collector-guard assembly, and decreases the backscatter due to attenuation of lower electron energy. To create a uniform and parallel electric field in this research, the source was made common to the collector-guard assembly. A precise positioning protocol was designed to enhance the parallelism of the source and collector-guard assembly. Additionally, MCNP5 was used to determine a backscatter correction factor to apply to the calibration. With these issues addressed, the absorbed dose rate-to-water of a Tracerlab 90Sr planar ophthalmic applicator was determined using National Institute of Standards and Technology's (NIST) calibration formalism, and the results of five trials with this source were compared to measurements at NIST with a traditional extrapolation chamber. Results: The absorbed dose rate-to-water of the planar applicator was determined to be 0.473 Gy/s ±0.6%. Comparing these results to NIST's determination of 0.474 Gy/s yields a ?0.6% difference. Conclusion: The feasibility of a planar, windowless extrapolation chamber has been demonstrated. A similar principle will be applied to developing a primary calibration standard for concave applicators and plaques. This research is funded by the customers of the University of Wisconsin Accredited Dosimetry Calibration Laboratory
Wiegelmann, T.; Thalmann, J. K.; Inhester, B.; Tadesse, T.; Sun, X.; Hoeksema, J. T.
2012-11-01
The Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) provides photospheric vector magnetograms with a high spatial and temporal resolution. Our intention is to model the coronal magnetic field above active regions with the help of a nonlinear force-free extrapolation code. Our code is based on an optimization principle and has been tested extensively with semianalytic and numeric equilibria and applied to vector magnetograms from Hinode and ground-based observations. Recently we implemented a new version which takes into account measurement errors in photospheric vector magnetograms. Photospheric field measurements are often affected by measurement errors and finite nonmagnetic forces inconsistent for use as a boundary for a force-free field in the corona. To deal with these uncertainties, we developed two improvements: i) preprocessing of the surface measurements to make them compatible with a force-free field, and ii) new code which keeps a balance between the force-free constraint and deviation from the photospheric field measurements. Both methods contain free parameters, which must be optimized for use with data from SDO/HMI. In this work we describe the corresponding analysis method and evaluate the force-free equilibria by how well force-freeness and solenoidal conditions are fulfilled, by the angle between magnetic field and electric current, and by comparing projections of magnetic field lines with coronal images from the Atmospheric Imaging Assembly (SDO/AIA). We also compute the available free magnetic energy and discuss the potential influence of control parameters.
Standard electrode potential, Tafel equation, and the solvation thermodynamics
International Nuclear Information System (INIS)
Equilibrium in the electronic subsystem across the solution-metal interface is considered to connect the standard electrode potential to the statistics of localized electronic states in solution. We argue that a correct derivation of the Nernst equation for the electrode potential requires a careful separation of the relevant time scales. An equation for the standard metal potential is derived linking it to the thermodynamics of solvation. The Anderson-Newns model for electronic delocalization between the solution and the electrode is combined with a bilinear model of solute-solvent coupling introducing nonlinear solvation into the theory of heterogeneous electron transfer. We therefore are capable of addressing the question of how nonlinear solvation affects electrochemical observables. The transfer coefficient of electrode kinetics is shown to be equal to the derivative of the free energy, or generalized force, required to shift the unoccupied electronic level in the bulk. The transfer coefficient thus directly quantifies the extent of nonlinear solvation of the redox couple. The current model allows the transfer coefficient to deviate from the value of 0.5 of the linear solvation models at zero electrode overpotential. The electrode current curves become asymmetric in respect to the change in the sign of the electrode overpotential.
Mis tekitab paksu verd juhi ja omaniku vahel / Külliki Tafel
Tafel, Külliki
2006-01-01
EBSi ja Tulevikuuringute Instituudi uuring näitab, et Eestis ei ole juhtide ja omanike vahel teravaid erimeelsusi. Soovitused tippjuhtidele ja omanikele konfliktide ärahoidmiseks. Lisa: EBSi ja ETI ühine uurimisprogramm
Loomemajandus - loovus pluss äri / Erik Terk, Külliki Tafel
Terk, Erik
2006-01-01
Kui kultuuripoliitika käsitleb kultuuri valdavalt toetuse vajaja ja saajana, siis loomemajanduslik mõte näeb kultuuri ja loovust kui väärtuslikku sisendit majandusele ning selles mõttes kui võrdväärset partnerit, kirjutavad autorid
Eco-label - simple environmental choice / Andres Viia, Külliki Tafel
Viia, Andres
2003-01-01
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
Scientific Electronic Library Online (English)
E., Ortiz-Rascón; N. C., Bruce; A. A., Rodríguez-Rosales; J., Garduño-Mejía; R., Ortega-Martínez.
2014-02-01
Full Text Available 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.
Directory of Open Access Journals (Sweden)
L. Gong
2012-06-01
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.
International Nuclear Information System (INIS)
Several methods of coincidence counting of 129I are examined. Efficiency functions are estimated for these different methods and compared with the results of experiments leading to the indication of the most suitable conditions of measurements. It was also found that the ?-efficiency of the 4?? methane flow counter for photons near 32 keV was 0.024 +- 0.005. Finally some general remarks are made on the extrapolation technique as used for coincidence counting. (author)
On the problem of extrapolating the data on Sr90 behaviour in dogs to a human organism
International Nuclear Information System (INIS)
Regularities in the metabolism of radiostrontium have been comparatively studied in dogs and man. The fact revealed that they are the same makes it possible to extrapolate the radiostrontium doses used for dogs to a human organism
Ravichandran R; Binukumar J; Sivakumar S; Krishnamurthy K; Davis C
2009-01-01
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...
Impact of new collider data on fits and extrapolations of cross sections and slopes
Energy Technology Data Exchange (ETDEWEB)
Block, M.M.; Cahn, R.N.
1985-08-01
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/sup 2/(s/s/sub o/) indefinitely give a significantly poorer chi/sup 2/ than those for which sigma/sub tot/ eventually levels out. For the proposed SSC energy for the former fits predict sigma/sub tot/(..sqrt..s = 40 TeV) approx. =200 mb while the latter give sigma/sub tot/(..sqrt..s = 40 TeV) approx. = 100 mb. 6 refs.
Extrapolation-based Path Invariants for Abstraction Re?nement of Fifo Systems
Heußner, Alexander; Sutre, Grégoire; Le Gall, Tristan
2009-01-01
The technique of counterexample-guided abstraction re?nement (Cegar) has been successfully applied in the areas of software and hardware veri?cation. Automatic abstraction re?nement is also desirable for the safety veri?cation of complex in?nite-state models. This paper investigates Cegar in the context of formal models of network protocols, in our case, the veri?cation of ?fo systems. Our main contribution is the introduction of extrapolation-based path invariants for abstraction re?nement. ...
Extrapolation and Local Acceleration of an Iterative Process for Common Fixed Point Problems
Cegielski, Andrzej; Censor, Yair
2012-01-01
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 a...
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
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.
Challenges for In vitro to in Vivo Extrapolation of Nanomaterial Dosimetry for Human Risk Assessment
Energy Technology Data Exchange (ETDEWEB)
Smith, Jordan N.
2013-11-01
The proliferation in types and uses of nanomaterials in consumer products has led to rapid application of conventional in vitro approaches for hazard identification. Unfortunately, assumptions pertaining to experimental design and interpretation for studies with chemicals are not generally appropriate for nanomaterials. The fate of nanomaterials in cell culture media, cellular dose to nanomaterials, cellular dose to nanomaterial byproducts, and intracellular fate of nanomaterials at the target site of toxicity all must be considered in order to accurately extrapolate in vitro results to reliable predictions of human risk.
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.
Extrapolation of the Dutch 1 MW tunable free electron maser to a 5 MW ECRH source
International Nuclear Information System (INIS)
A Free Electron Maser (FEM) is now under construction at the FOM Institute (Rijnhuizen) Netherlands with the goal of producing 1 MW long pulse to CW microwave output in the range 130 GHz to 250 GHz with wall plug efficiencies of 50% (Verhoeven, et al EC-9 Conference). An extrapolated version of this device is proposed which by scaling up the beam current, would produce microwave power levels of up to 5 MW CW in order to reduce the cost per watt and increase the power per module, thus providing the fusion community with a practical ECRH source
Model of a realistic InP surface quantum dot extrapolated from atomic force microscopy results
International Nuclear Information System (INIS)
We report on numerical simulations of a zincblende InP surface quantum dot (QD) on In0.48Ga0.52P buffer. Our model is strictly based on experimental structures, since we extrapolated a three-dimensional dot directly by atomic force microscopy results. Continuum electromechanical, k-vector ? p-vector 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 k-vector ? p-vector 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. (papers)
Some numerical methods for integrating systems of first-order ordinary differential equations
Clark, N. W.
1969-01-01
Report on numerical methods of integration includes the extrapolation methods of Bulirsch-Stoer and Neville. A comparison is made nith the Runge-Kutta and Adams-Moulton methods, and circumstances are discussed under which the extrapolation method may be preferred.
International Nuclear Information System (INIS)
The potential energy curves (PECs) of the first electronic excited state of S2(ã1?g) are calculated employing a multi-reference configuration interaction method with the Davidson correction in combination with a series of correlation-consistent basis sets from Dunning: aug-cc-pVXZ (X = T, Q, 5, 6). In order to obtain PECs with high accuracy, PECs calculated with aug-cc-pV(Q, 5)Z basis sets are extrapolated to the complete basis set limit. The resulting PECs are then fitted to the analytical potential energy function (APEF) using the extended Hartree-Fock approximate correlation energy method. By utilizing the fitted APEF, accurate and reliable spectroscopic parameters are obtained, which are consistent with both experimental and theoretical results. By solving the Schrödinger equation numerically with the APEFs obtained at the AV6Z and the extrapolated AV(Q, 5)Z level of theory, we calculate the complete set of vibrational levels, classical turning points, inertial rotation and centrifugal distortion constants. (paper)
International Nuclear Information System (INIS)
A reference solution to a benchmark problem for a three-dimensional mixed-convection flow in a horizontal rectangular channel differentially heated (Poiseuille-Rayleigh-Benard flow) has been proposed in Part 1 of the present article (Numer. Heat Transfer B, vol. 60, pp. 325-345, 2011). Since mixed Dirichlet and Neumann thermal boundary conditions are used on the horizontal walls of the channel, a temperature gradient discontinuity is generated. The aim of this article is to analyze the consequences of this singularity on Richardson extrapolation (RE) of the numerical solutions. The convergence orders of the numerical methods used (finite difference, finite volume, finite element), observed from RE of local and integral quantities are discussed with an emphasis on singularity influence. With the grids used, it is shown that RE can increase the accuracy of the discrete solutions preferentially with the discretization methods of low space accuracy order, but only in some part of the channel and for a restricted range of the extrapolation coefficient. A correction to the Taylor expansion involved in the RE formalism is proposed to take into account the singularity and to explain the majority of the RE behaviors observed. (authors)
Finite-Element Extrapolation of Myocardial Structure Alterations Across the Cardiac Cycle in Rats.
David Gomez, Arnold; Bull, David A; Hsu, Edward W
2015-10-01
Myocardial microstructures are responsible for key aspects of cardiac mechanical function. Natural myocardial deformation across the cardiac cycle induces measurable structural alteration, which varies across disease states. Diffusion tensor magnetic resonance imaging (DT-MRI) has become the tool of choice for myocardial structural analysis. Yet, obtaining the comprehensive structural information of the whole organ, in 3D and time, for subject-specific examination is fundamentally limited by scan time. Therefore, subject-specific finite-element (FE) analysis of a group of rat hearts was implemented for extrapolating a set of initial DT-MRI to the rest of the cardiac cycle. The effect of material symmetry (isotropy, transverse isotropy, and orthotropy), structural input, and warping approach was observed by comparing simulated predictions against in vivo MRI displacement measurements and DT-MRI of an isolated heart preparation at relaxed, inflated, and contracture states. Overall, the results indicate that, while ventricular volume and circumferential strain are largely independent of the simulation strategy, structural alteration predictions are generally improved with the sophistication of the material model, which also enhances torsion and radial strain predictions. Moreover, whereas subject-specific transversely isotropic models produced the most accurate descriptions of fiber structural alterations, the orthotropic models best captured changes in sheet structure. These findings underscore the need for subject-specific input data, including structure, to extrapolate DT-MRI measurements across the cardiac cycle. PMID:26299478
The use of natural analogues in the long-term extrapolation of glass corrosion processes
International Nuclear Information System (INIS)
One of the most critical aspects of nuclear waste management is the extrapolation of materials and systems behavior from short term experiments, typically on the order of one year, over comparatively very long periods of time. Safety and risk analyses have to rely on extrapolations and the respective findings have to be evaluated in the frame of licensing procedures. In this unique situation, any source of information that can lend support to the credibility of predicted behavior, should be exploited and investigated with great care. There are natural systems, e.g. the Oklo reactor, which can provide evidence of radionuclide migration over very long periods of time and thus help to answer specific questions of interest. Natural glasses and minerals can serve as analogues for both glass and crystalline nuclear waste forms, and the alteration of the natural materials can be studied to infer information on the behavior of the man-made products in geologic environments. This paper reviews most of the work performed by the authors and their colleagues in this field together with information available from literature and discusses the extent to which natural glasses can be used to validate or verify predictions. (author)
Testing magnetofrictional extrapolation with the Titov-D\\'emoulin model of solar active regions
Valori, G; Török, T; Titov, V S
2010-01-01
We examine the nonlinear magnetofrictional extrapolation scheme using the solar active region model by Titov and D\\'emoulin as test field. This model consists of an arched, line-tied current channel held in force-free equilibrium by the potential field of a bipolar flux distribution in the bottom boundary. A modified version, having a parabolic current density profile, is employed here. We find that the equilibrium is reconstructed with very high accuracy in a representative range of parameter space, using only the vector field in the bottom boundary as input. Structural features formed in the interface between the flux rope and the surrounding arcade-"hyperbolic flux tube" and "bald patch separatrix surface"-are reliably reproduced, as are the flux rope twist and the energy and helicity of the configuration. This demonstrates that force-free fields containing these basic structural elements of solar active regions can be obtained by extrapolation. The influence of the chosen initial condition on the accuracy...
Directory of Open Access Journals (Sweden)
Fleming D
2006-01-01
Full Text Available Background : Therapeutic drug monitoring for mycophenolic acid (MPA is increasingly being advocated. Thepresent therapeutic range relates to the 12-hour area under the serum concentration time profile (AUC.However, this is a cumbersome, tedious, cost restricting procedure. Is it possible to reduce this samplingperiod? Aim : To compare the AUC from a reduced sampling strategy with the full 12-hour profile for MPA. Settings and Design : Clinical Pharmacology Unit of a tertiary care hospital in South India. Retrospective, paireddata. Materials and Methods : Thirty-four 12-hour profiles from post-renal transplant patients on Cellcept ® wereevaluated. Profiles were grouped according to steroid and immunosuppressant co-medication and the timeafter transplant. MPA was estimated by high performance liquid chromatography with UV detection. From the12-hour profiles the AUC up to only six hours was calculated by the trapezoidal rule and a correction factorapplied. These two AUCs were then compared. Statistical Analysis : Linear regression, intra-class correlations (ICC and a two-tailed paired t-test were appliedto the data. Results : Comparing the 12-hour AUC with the paired 6-hour extrapolated AUC, the ICC and linear regression(r2 were very good for all three groups. No statistical difference was found by a two-tailed paired t-test. Nobias was seen with a Bland Altman plot or by calculation. Conclusion : For patients on Cellcept ® with prednisolone ± cyclosporine the 6-hour corrected is an accuratemeasure of the full 12-hour AUC.
Directory of Open Access Journals (Sweden)
Choi Kwok
2011-05-01
Full Text Available Abstract Background False discovery rate (FDR control is commonly accepted as the most appropriate error control in multiple hypothesis testing problems. The accuracy of FDR estimation depends on the accuracy of the estimation of p-values from each test and validity of the underlying assumptions of the distribution. However, in many practical testing problems such as in genomics, the p-values could be under-estimated or over-estimated for many known or unknown reasons. Consequently, FDR estimation would then be influenced and lose its veracity. Results We propose a new extrapolative method called Constrained Regression Recalibration (ConReg-R to recalibrate the empirical p-values by modeling their distribution to improve the FDR estimates. Our ConReg-R method is based on the observation that accurately estimated p-values from true null hypotheses follow uniform distribution and the observed distribution of p-values is indeed a mixture of distributions of p-values from true null hypotheses and true alternative hypotheses. Hence, ConReg-R recalibrates the observed p-values so that they exhibit the properties of an ideal empirical p-value distribution. The proportion of true null hypotheses (?0 and FDR are estimated after the recalibration. Conclusions ConReg-R provides an efficient way to improve the FDR estimates. It only requires the p-values from the tests and avoids permutation of the original test data. We demonstrate that the proposed method significantly improves FDR estimation on several gene expression datasets obtained from microarray and RNA-seq experiments. Reviewers The manuscript was reviewed by Prof. Vladimir Kuznetsov, Prof. Philippe Broet, and Prof. Hongfang Liu (nominated by Prof. Yuriy Gusev.
Kadoura, Ahmad; Sun, Shuyu; Salama, Amgad
2014-08-01
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.
International Nuclear Information System (INIS)
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
Energy Technology Data Exchange (ETDEWEB)
Kadoura, Ahmad; Sun, Shuyu, E-mail: shuyu.sun@kaust.edu.sa; Salama, Amgad
2014-08-01
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
2014-08-01
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. © 2014 Elsevier Inc.
Modeling of systematic retention of beryllium in rats. Extrapolation to humans
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 other 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 other previously published
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
Andriessen, J. H. T. H.; van der Horst-Bruinsma, I. E.; ter Haar Romeny, B. M.
1989-05-01
The present phase of the clinical evaluation within the Dutch PACS project mainly focuses on the development and evaluation of a PACSystem for a few departments in the Utrecht University hospital (UUH). A report on the first clinical experiences and a detailed cost/savings analysis of the PACSystem in the UUH are presented elsewhere. However, an assessment of the wider fmancial and organizational implications for hospitals and for the health sector is also needed. To this end a model for (financial) cost assessment of PACSystems is being developed by BAZIS. Learning from the actual pilot implementation in UUH we realized that general Technology Assessment (TA) also calls for an extra-polation of the medical and organizational effects. After a short excursion into the various approaches towards TA, this paper discusses the (inter) organizational dimensions relevant to the development of the necessary exttapolationmodels.
Extrapolation of lattice QCD results beyond the power-counting regime
Leinweber, D B; Young, R D
2005-01-01
Resummation of the chiral expansion is necessary to make accurate contact with current lattice simulation results of full QCD. Resummation techniques including relativistic formulations of chiral effective field theory and finite-range regularization (FRR) techniques are reviewed, with an emphasis on using lattice simulation results to constrain the parameters of the chiral expansion. We illustrate how the chiral extrapolation problem has been solved and use FRR techniques to identify the power-counting regime (PCR) of chiral perturbation theory. To fourth-order in the expansion at the 1% tolerance level, we find $0 \\le m_\\pi \\le 0.18$ GeV for the PCR, extending only a small distance beyond the physical pion mass.
Linear Extrapolation of Ultrarelativistic Nucleon-Nucleon Scattering to Nucleus-Nucleus Collisions
Jeon, S; Jeon, Sangyong; Kapusta, Joseph
1997-01-01
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.
Linear extrapolation of ultrarelativistic nucleon-nucleon scattering to nucleus-nucleus collisions
Jeon, Sangyong; Kapusta, Joseph
1997-07-01
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.
Energy Technology Data Exchange (ETDEWEB)
Dowding, Kevin J.; Hills, Richard Guy (New Mexico State University, Las Cruces, NM)
2005-04-01
Numerical models of complex phenomena often contain approximations due to our inability to fully model the underlying physics, the excessive computational resources required to fully resolve the physics, the need to calibrate constitutive models, or in some cases, our ability to only bound behavior. Here we illustrate the relationship between approximation, calibration, extrapolation, and model validation through a series of examples that use the linear transient convective/dispersion equation to represent the nonlinear behavior of Burgers equation. While the use of these models represents a simplification relative to the types of systems we normally address in engineering and science, the present examples do support the tutorial nature of this document without obscuring the basic issues presented with unnecessarily complex models.
EVIDENCE FOR SOLAR TETHER-CUTTING MAGNETIC RECONNECTION FROM CORONAL FIELD EXTRAPOLATIONS
Energy Technology Data Exchange (ETDEWEB)
Liu, Chang; Deng, Na; Lee, Jeongwoo; Wang, Haimin [Space Weather Research Laboratory, Center for Solar-Terrestrial Research, New Jersey Institute of Technology, University Heights, Newark, NJ 07102-1982 (United States); Wiegelmann, Thomas [Max-Planck-Institut für Sonnensystemforschung, Max-Planck-Strasse 2, D-37191 Katlenburg-Lindau (Germany); Moore, Ronald L., E-mail: chang.liu@njit.edu [Heliophysics and Planetary Science Office, ZP13, Marshall Space Flight Center, Huntsville, AL 35812-9900 (United States)
2013-12-01
Magnetic reconnection is one of the primary mechanisms for triggering solar eruptive events, but direct observation of this rapid process has been a challenge. In this Letter, using a nonlinear force-free field (NLFFF) extrapolation technique, we present 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 analysis of the field lines traced from positions of four conspicuous flare 1700 Å footpoints observed at the event onset. Right before the flare, the four footpoints are located very close to the regions of local maxima of the magnetic twist index. In particular, 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 flare, the twist index of regions around the footpoints diminishes greatly and the above field lines become low-lying and less twisted (?0.6 turns), overarched by loops linking the two flare ribbons formed later. About 10% of the flux (?3 × 10{sup 19} Mx) from the inner footpoints undergoes a footpoint exchange. This portion of flux originates from the edge regions of the inner footpoints that are brightened first. These rapid changes of magnetic field connectivity inferred from the NLFFF extrapolation are consistent with the tether-cutting magnetic reconnection model.
EVIDENCE FOR SOLAR TETHER-CUTTING MAGNETIC RECONNECTION FROM CORONAL FIELD EXTRAPOLATIONS
International Nuclear Information System (INIS)
Magnetic reconnection is one of the primary mechanisms for triggering solar eruptive events, but direct observation of this rapid process has been a challenge. In this Letter, using a nonlinear force-free field (NLFFF) extrapolation technique, we present 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 analysis of the field lines traced from positions of four conspicuous flare 1700 Å footpoints observed at the event onset. Right before the flare, the four footpoints are located very close to the regions of local maxima of the magnetic twist index. In particular, 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 flare, the twist index of regions around the footpoints diminishes greatly and the above field lines become low-lying and less twisted (?0.6 turns), overarched by loops linking the two flare ribbons formed later. About 10% of the flux (?3 × 1019 Mx) from the inner footpoints undergoes a footpoint exchange. This portion of flux originates from the edge regions of the inner footpoints that are brightened first. These rapid changes of magnetic field connectivity inferred from the NLFFF extrapolation are consistent with the tether-cutting magnetic reconnection model
(Solid + liquid) solubility of organic compounds in organic solvents – Correlation and extrapolation
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Highlights: • A novel, robust semi-empirical model for regression of solubility is presented. • The model fulfils thermodynamic boundary conditions at the melting point. • The activity coefficient is modelled with a scaled three-parameter Weibull function. • A three-parameter regression equation is derived from the semi-empirical model. • This equation provides good accuracy and robustness compared to standard models. - Abstract: A semi-empirical model is developed for the regression of (solid + liquid) solubility data with temperature. The model fulfils the required boundary conditions, allowing for robust extrapolation to higher and lower temperatures. The model combines a representation of the solid-state activity which accommodates a temperature-dependent heat capacity difference contribution with a scaled three-parameter Weibull function representing the temperature dependence of the solution activity coefficient at equilibrium. Evaluation of the model is based on previously published experimental calorimetric and solubility data of four organic compounds, fenoxycarb, fenofibrate, risperidone and butyl paraben, in five common organic solvents, methanol, ethyl acetate, acetone, acetonitrile, and toluene. The temperature dependence of the van’t Hoff enthalpy of solution and its components is analysed and discussed. Among the four compounds the influence of temperature on the enthalpy of fusion varies from moderate to substantial. Based on the semi-empirical model, a new equation containing three adjustable parameters is proposed for regression and extrapolation of solubility data for cases when only melting data and solubility data is available. The equation is shown to provide good accuracy and robustness when evaluated against the full semi-empirical model as well as against commonly used, more simple empirical equations. It is shown how such a model can be used to obtain an estimate of the heat capacity difference for cases where accurate solubility data is available in multiple solvents
QUANTITATIVE METHODS FOR CROSS-SPECIES MAPPING (CSM)
Cross species extrapolation will be defined as prediction from one species to another without empirical verification. ross species mapping (CSM) is the same except empirical verification is performed. SM may be viewed as validation of methods for extrapolation. Algorithms for CSM...
Energy Technology Data Exchange (ETDEWEB)
Rothe, R.E.
1997-12-01
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.
International Nuclear Information System (INIS)
Epidemiological surveys can play an important role in answering the question whether the risk of lung cancer by radon exposure in houses can be estimated on the basis of linear extrapolation of miner data or not. Recently, some of those surveys have been evaluated. It was concluded that linear extrapolation is subject to great doubts. A reliable epidemiological survey was carried out by means of a Finnish cohort of lung cancer patients and controls, who lived in the same house for at least 18 years. For one year radon concentrations were measured in their houses. The odds ratio (comparable to relative risk) for long cancer was 1.01 per 100 Bq·m-3, which value is significantly different from the value of 1.15, calculated on the basis of linear extrapolation of miner data. 3 tabs., 18 refs
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
Lu, Yi-chun; Gasteiger, Hubert A.; Shao-Horn, Yang
2010-01-01
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...
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
International Nuclear Information System (INIS)
The numerical analysis of practically all existing formulae such as expansion series, Tait, logarithm, Van der Waals and virial equations for interpolation of experimental molar volumes versus high pressure was carried out. One can conclude that extrapolating dependences of molar volumes versus pressure and temperature can be valid. It was shown that virial equations can be used for fitting experimental data at relatively low pressures P<3 kbar too in distinction to other equations. Direct solving of a linear equation of the third order relatively to volume using extrapolated virial coefficients allows us to obtain good agreement between existing experimental data for high pressure and calculated values
TANG, LIN
2011-01-01
In this paper, we generalize the $A_\\fz$ extrapolation theorem in \\cite{cmp} and the $A_p$ extrapolation theorem of Rubio de Francia to Schr\\"odinger settings. In addition, we also establish the weighted vector-valued inequalities for Schr\\"odinger type maximal operators by using weights belonging to $ A_p^{\\rho,\\tz}$ which includes $A_p$. As their applications, we establish the weighted vector-valued inequalities for some Sch\\"odinger type operators and pseudo-differential ...
Top-down workforce demand extrapolation based on an EC energy road-map scenario
International Nuclear Information System (INIS)
The EHRO-N team of JRC-IET provides the EC with essential data related to supply and demand for nuclear experts based on bottom-up information from the nuclear industry. The current paper deals with an alternative approach to derive figures for the demand side information of the nuclear workforce. Complementary to the bottom-up approach, a top-down modelling approach extrapolation of an EC Energy road-map nuclear energy demand scenario is followed here in addition to the survey information. In this top-down modelling approach, the number of nuclear power plants that are in operation and under construction is derived as a function of time from 2010 up to 2050 assuming that the current reactor park will be replaced by generic third generation reactors of 1400 MWe or 1000 MWe. Depending on the size of new build reactors, the analysis shows the number of new reactors required to fulfil the demand for nuclear energy. Based on workforce models for operation and construction of nuclear power plants, the model allows an extrapolation of these respective work-forces. Using the nuclear skills pyramid, the total workforce employed at a plant is broken down in a nuclear (experts), nuclearized, and nuclear aware workforce. With retirement profiles for nuclear power plants derived from the bottom-up EHRO-N survey, the replacement of the current workforce is taken into account. The peak of the new workforce (partly replacing the retiring workforce and additionally keeping up with the growing total workforce demand) for nuclear experts and nuclearized employees is to be expected at the end of the considered period (2050). However, the peak workforce for nuclear aware employees is to be expected around 2020. When comparing to historical data for the nuclear capacity being installed at the same time in Europe, it is clear that the expected future capacity to be installed at the same time in Europe is significantly lower (factor of 2) than in the early 1980's. However, it should be realized that the skills demand might have been more relaxed in those days. Furthermore, a steep rise in construction is to be expected within 10 to 15 years. This is due to the fact that not only additional nuclear power plants need to be built to keep up with the growing nuclear energy demand, but also the current nuclear reactor park needs to be replaced. In order to deal with this steep rise, the nuclear industry may consider buying time by extending the lifetime of the current nuclear reactor park. (authors)
Hybrid superconducting a.c. current limiter extrapolation 63 kV-1 250 A
Tixador, P.; Levêque, J.; Brunet, Y.; Pham, V. D.
1994-04-01
Following the developement of a.c. superconducting wires a.c. current superconducting limiters have emerged. These limiters limit the fault currents nearly instantaneously, without detection nor order giver and may be suitable for high voltages. They are based on the natural transition from the superconducting state to the normal resistive state by overstepping the critical current of a superconducting coil which limits or triggers the limitation. Our limiter device consists essentially of two copper windings coupled through a saturable magnetic circuit and of a non inductively wound superconducting coil with a reduced current compared to the line current. This design allows a simple superconducting cable and reduced cryogenic losses but the dielectric stresses are high during faults. A small model (150 V/50 A) has experimentally validated our design. An industrial scale current limiter is designed and the comparisons between this design and other superconducting current limiters are given. Les courants de court-circuit sur les grands réseaux électriques ne cessent d'augmenter. Dans ce contexte sont apparus les limiteurs supraconducteurs de courant suite au développement des brins supraconducteurs alternatifs. Ces limiteurs peuvent limiter les courants de défaut presque instantanément, sans détection de défaut ni donneur d'ordre et ils sont extrapolables aux hautes tensions. Ils sont fondés sur la transition naturelle de l'état supraconducteur à l'état normal très résistif par dépassement du courant critique d'un enroulement supraconducteur qui limite ou déclenche la limitation. Notre limiteur est composé de deux enroulements en cuivre couplés par un circuit magnétique saturable et d'une bobine supraconductrice à courant réduit par rapport au courant de la ligne. Cette conception permet un câble supraconducteur simple et des pertes cryogéniques réduites mais les contraintes diélectriques en régime de défaut sont importantes. Une maquette (150 V/50 A) a permis de valider expérimentalement cette conception. Nous aborderons l'extrapolation d'un limiteur de taille industrielle (63 kV/1 250 A). Les résultats seront comparés à des limiteurs supraconducteurs résistifs et de type DASC.
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
Yang, X; Zhou, Y-F; Yu, Y; Zhao, D-H; Shi, W; Fang, B-H; Liu, Y-H
2015-02-01
A multi-compartment physiologically based pharmacokinetic (PBPK) model to describe the disposition of cyadox (CYX) and its metabolite quinoxaline-2-carboxylic acid (QCA) after a single oral administration was developed in rats (200 mg/kg b.w. of CYX). Considering interspecies differences in physiology and physiochemistry, the model efficiency was validated by pharmacokinetic data set in swine. The model included six compartments that were blood, muscle, liver, kidney, adipose, and a combined compartment for the rest of tissues. The model was parameterized using rat plasma and tissue concentration data that were generated from this study. Model simulations were achieved using a commercially available software program (ACSLXL ibero version 3.0.2.1). Results supported the validity of the model with simulated tissue concentrations within the range of the observations. The correlation coefficients of the predicted and experimentally determined values for plasma, liver, kidney, adipose, and muscles in rats were 0.98, 0.98, 0.98, 0.99, and 0.95, respectively. The rat model parameters were then extrapolated to pigs to estimate QCA disposition in tissues and validated by tissue concentration of QCA in swine. The correlation coefficients between the predicted and observed values were over 0.90. This model could provide a foundation for developing more reliable pig models once more data are available. PMID:25378053
[Extrapolation of dose-effect relationships for cytogenetic aberrations from high to low doses].
Eidus, L Kh
1999-01-01
It is known, that extrapolation of dose response curve for cytogenic lesions, based on the linear non-threshold concept is not correct due to anomalies in the low dose region, among them the dose intervals of the so-called "low dose effects" (LDE) and "plato"-effect. As a rule they are attributed to assumed heterogeneity of cell populations or to existence of several repair systems. Analysing the data on modification the cytogenetic lesions we concluded, that in the whole low-dose range functions one on the same repair system, but it "switches on" only at sufficient reorganization of chromatin (accompanied by expression of before "silent" genes), caused by radiation-induced increase of the membranes permeability. In the dose interval of LDE this occurs only in vary narrow diapason of dose rate (approximately(1-30) cGy/min for many cell kinds); in the "plato" dose interval--in its beginning. By the assessment of cancerogenic risk the linear non threshold concept can be used only for dose dependence, obtained when repair is absent or inhibited. PMID:10347611
Evaluation of simple in vitro to in vivo extrapolation approaches for environmental compounds.
Yoon, Miyoung; Efremenko, Alina; Blaauboer, Bas J; Clewell, Harvey J
2014-03-01
As part of an effort to support in silico/in vitro based risk assessment, we evaluated the accuracy associated with conducting simple in vitro to in vivo extrapolation (IVIVE) for environmental compounds using available in vitro human metabolism data. The IVIVE approach was applied to a number of compounds with a wide range of properties spanning the diversity of characteristics of environmental compounds, and where possible the resulting estimates of the in vivo steady-state blood concentration were compared with estimates derived on the basis of human in vivo kinetic data. There appears to be a systematic bias in the estimation of intrinsic clearance (Clint) from in vitro versus in vivo data, with in vitro based estimates underestimating in vivo clearance for small values of Clint but with the opposite relationship at large values of Clint. Nevertheless, the resulting estimates of Css were in good agreement. The chief drawback of the simple approach used in this study, which performs the IVIVE prediction for the parent compound only, is that it is not applicable for toxicity associated with a metabolite. PMID:24216301
Cui, Jie; Li, Zhiying; Krems, Roman V.
2015-10-01
We consider a problem of extrapolating the collision properties of a large polyatomic molecule A-H to make predictions of the dynamical properties for another molecule related to A-H by the substitution of the H atom with a small molecular group X, without explicitly computing the potential energy surface for A-X. We assume that the effect of the -H ?-X substitution is embodied in a multidimensional function with unknown parameters characterizing the change of the potential energy surface. We propose to apply the Gaussian Process model to determine the dependence of the dynamical observables on the unknown parameters. This can be used to produce an interval of the observable values which corresponds to physical variations of the potential parameters. We show that the Gaussian Process model combined with classical trajectory calculations can be used to obtain the dependence of the cross sections for collisions of C6H5CN with He on the unknown parameters describing the interaction of the He atom with the CN fragment of the molecule. The unknown parameters are then varied within physically reasonable ranges to produce a prediction uncertainty of the cross sections. The results are normalized to the cross sections for He — C6H6 collisions obtained from quantum scattering calculations in order to provide a prediction interval of the thermally averaged cross sections for collisions of C6H5CN with He.
The risk of extrapolation in neuroanatomy: the case of the mammalian vomeronasal system
Directory of Open Access Journals (Sweden)
Ignacio Salazar
2009-10-01
Full Text Available The sense of smell plays a crucial role in mammalian social and sexual behaviour, identification of food, and detection of predators. Nevertheless, mammals vary in their olfactory ability. One reason for this concerns the degree of development of their pars basalis rhinencephali, an anatomical feature that has has been considered in classifying this group of animals as macrosmatic, microsmatic or anosmatic. In mammals, different structures are involved in detecting odours: the main olfactory system, the vomeronasal system (VNS, and two subsystems, namely the ganglion of Grüneberg and the septal organ. Here, we review and summarise some aspects of the comparative anatomy of the VNS and its putative relationship to other olfactory structures. Even in the macrosmatic group, morphological diversity is an important characteristic of the VNS, specifically of the vomeronasal organ and the accessory olfactory bulb. We conclude that it is a big mistake to extrapolate anatomical data of the VNS from species to species, even in the case of relatively close evolutionary proximity between them. We propose to study other mammalian VNS than those of rodents in depth as a way to clarify its exact role in olfaction. Our experience in this field leads us to hypothesise that the VNS, considered for all mammalian species, could be a system undergoing involution or regression, and could serve as one more integrated olfactory subsystem.
Cui, Jie; Krems, Roman V
2015-01-01
We consider a problem of extrapolating the collision properties of a large polyatomic molecule A-H to make predictions of the dynamical properties for another molecule related to A-H by the substitution of the H atom with a small molecular group X, without explicitly computing the potential energy surface for A-X. We assume that the effect of the $-$H $\\rightarrow$ $-$X substitution is embodied in a multidimensional function with unknown parameters characterizing the change of the potential energy surface. We propose to apply the Gaussian Process model to determine the dependence of the dynamical observables on the unknown parameters. This can be used to produce an interval of the observable values that corresponds to physical variations of the potential parameters. We show that the Gaussian Process model combined with classical trajectory calculations can be used to obtain the dependence of the cross sections for collisions of C$_6$H$_5$CN with He on the unknown parameters describing the interaction of the H...
Cui, Jie; Li, Zhiying; Krems, Roman V
2015-10-21
We consider a problem of extrapolating the collision properties of a large polyatomic molecule A-H to make predictions of the dynamical properties for another molecule related to A-H by the substitution of the H atom with a small molecular group X, without explicitly computing the potential energy surface for A-X. We assume that the effect of the -H ?-X substitution is embodied in a multidimensional function with unknown parameters characterizing the change of the potential energy surface. We propose to apply the Gaussian Process model to determine the dependence of the dynamical observables on the unknown parameters. This can be used to produce an interval of the observable values which corresponds to physical variations of the potential parameters. We show that the Gaussian Process model combined with classical trajectory calculations can be used to obtain the dependence of the cross sections for collisions of C6H5CN with He on the unknown parameters describing the interaction of the He atom with the CN fragment of the molecule. The unknown parameters are then varied within physically reasonable ranges to produce a prediction uncertainty of the cross sections. The results are normalized to the cross sections for He - C6H6 collisions obtained from quantum scattering calculations in order to provide a prediction interval of the thermally averaged cross sections for collisions of C6H5CN with He. PMID:26493891
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
Spatial extrapolation of light use efficiency model parameters to predict gross primary production
Directory of Open Access Journals (Sweden)
Karsten Schulz
2011-12-01
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.
Alternative to the Romberg Method of Estimating the Definite Integral
Youngberg, Michael Brandon
2012-01-01
Using elementary methods, we define and derive a particular weighted average of the trapezoidal and composite trapezoidal rules and show that this approximation, as well as its composite, is straightforward in computation. This approximation and its composite, in their general forms, are shown to have predictable error patterns; thus, an extrapolation method can be used to increase the accuracy. We then derive the necessary weights to use an extrapolation method to reduce er...
Li, Yong-Qing; Song, Yu-Zhi; Joaquim de Campos Varandas, António
2015-01-01
An accurate single-sheeted double many-body expansion potential energy surface is reported for the title system. It is obtained by using the aug-cc-pVTZ and aug-cc-pVQZ basis sets with extrapolation of the electron correlation energy to the complete basis set limit, plus extrapolation to the complete basis set limit of the complete-active-space self-consistent field energy. The collinear and bending barrier heights of the new global potential energy surface is 2.301 and 1.768 kcal mol-1, in very good agreement with the values of 2.222 and 1.770 kcal mol-1 from the current best potential energy surface. In particular, the new potential energy surface describes well the important van der Waals interactions which is very useful for investigating the dynamics of the title system. Thus, the new potential energy surface can both be recommended for dynamics studies of the F + H2 reaction and as building block for constructing the potential energy surfaces of larger fluorine/hydrogen containing systems. Based on the new potential energy surface, a preliminary theoretical study of the reaction F(2P) + H2 (X1 ?g+) ? FH(X1?+) + H(2S) has been carried out with the methods of quasi-classical trajectory and quantum mechanical. The results have shown that the new PES is suitable for any kind of dynamics studies. Supplementary material in the form of one pdf file available from the Journal web page at http://dx.doi.org/10.1140/epjd/e2014-50445-3