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 csm. The protection efficiencies of these compounds showed a certain relationship to highest occupied molecular orbital (HOMO) energy, Mulliken atomic charges and Fukui indices.
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
International Nuclear Information System (INIS)
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
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...
Extrapolation Method for Shell Model Calculations with Projected Deformed Basis
International Nuclear Information System (INIS)
Exact solution of large-scale shell model calculations can be obtained, in a well-controlled manner, by energy variance extrapolation method with spherical and deformed bases. The extrapolation formula including H3 matrix element is presented in shell model calculation. It is also shown that energy variance extrapolation with deformed basis is quite promising for huge shell model calculations, and its feasibility is shown in f p shell calculation
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.
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)
The absolute determination of activity by the efficiency extrapolation method
International Nuclear Information System (INIS)
As agent for the Commonwealth Scientific and Industrial Research Organisation, the Australian Atomic Energy Commission is responsible for the maintenance of the Australian standard of activity. The standard comprises activity measurement procedures involving the operation of 4 ? ?-? coincidence counting equipment. The coincidence method requires the application of correction factors which depend on detection efficiency, such as arise for complex decay schemes and internal conversion. These corrections approach unity as the detection efficiency in the ?-channel approaches 100 per cent. By performing activity determinations for a range of ? detection efficiencies, an 'efficiency extrapolation' analysis can be applied which eliminates the need to determine the absolute detection efficiency for each channel
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
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.
International Nuclear Information System (INIS)
The activity of electron capture radionuclides is usually determined by 4?(proportional counter, PC)-? coincidence counting. The corrections necessary for the final activity value calculation are obtained by an extrapolation method. Variation of the PC detection efficiency can be achieved through different methods, e.g. by changing the self-absorption of the source using absorbing foils or by adding carriers. Another possibility is a 'wet' extrapolation method, which utilises an absorption change during the drying of a water droplet added onto the source surface. In this paper, slopes of extrapolation curves and resulting activity values obtained by different methods are compared for several radionuclides (54Mn, 139Ce, 88Y, 57Co). In some cases a digital coincidence system was used for the analysis of measured data. The 'wet' extrapolation, due to its very simple procedure, seems to be convenient for routine measurement and its accuracy is similar to the other methods
Standardization of 65Zn by 4piPC-gamma coincidence counting method with efficiency extrapolation.
Sahagia, Maria; Ivan, C; Grigorescu, E L; Capogni, M; De Felice, P; Fazio, A
2004-01-01
A 65Zn solution was standardized by the 4piPC-gamma efficiency-extrapolation coincidence counting method. Theoretical aspects of coincidence equations, efficiency equations and linearity conditions are reviewed. Experimental measurements were performed for two low level discrimination thresholds for the PC channel (counting K+L or K X-rays or Auger electrons from EC decay) and for three different settings of the gamma window. Requirements on gamma channel set-up for linear extrapolation were established by using a Pb absorber or by proper gamma window setting. The measured activity values were discussed and found in good agreement with those obtained with a calibrated ionization chamber. PMID:14987679
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 ...
Precise Numerical Results of IR-vertex and box integration with Extrapolation Method
Yuasa, F; Fujimoro, J; Hamaguchi, N; Ishikawa, T; Shimizu, Y
2007-01-01
We present a new approach for obtaining very precise integration results for infrared vertex and box diagrams, where the integration is carried out directly without performing any analytic integration of Feynman parameters. Using an appropriate numerical integration routine with an extrapolation method, together with a multi-precision library, we have obtained integration results which agree with the analytic results to 10 digits even for such a very small photon mass as $10^{-150}$ GeV in the infrared vertex diagram.
Sommerfeld, Thomas; Ehara, Masahiro
2015-01-01
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 CO 2- , 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 CO 2- . It is important to emphasize that for both the model and for CO 2- , 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.
Sommerfeld, Thomas; Ehara, Masahiro
2015-01-21
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. PMID:25612687
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)
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.
Verloock, Leen; Joseph, Wout; Gati, Azeddine; Varsier, Nadège; Flach, Björn; Wiart, Joe; Martens, Luc
2013-06-01
An experimental validation of a low-cost method for extrapolation and estimation of the maximal electromagnetic-field exposure from long-term evolution (LTE) radio base station installations are presented. No knowledge on downlink band occupation or service characteristics is required for the low-cost method. The method is applicable in situ. It only requires a basic spectrum analyser with appropriate field probes without the need of expensive dedicated LTE decoders. The method is validated both in laboratory and in situ, for a single-input single-output antenna LTE system and a 2×2 multiple-input multiple-output system, with low deviations in comparison with signals measured using dedicated LTE decoders. PMID:23179190
International Nuclear Information System (INIS)
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)
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.
Mizusaki, Takahiro
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 energies and electro-magnetic transition strengths. Furthermore, by combining this VMC method with energy variance extrapolation, we can estimate exact shell-model energies.
Kebaier, A
2005-01-01
We study the approximation of $\\mathbb{E}f(X_T)$ by a Monte Carlo algorithm, where $X$ is the solution of a stochastic differential equation and $f$ is a given function. We introduce a new variance reduction method, which can be viewed as a statistical analogue of Romberg extrapolation method. Namely, we use two Euler schemes with steps $\\delta$ and $\\delta^{\\beta},0<\\beta<1$. This leads to an algorithm which, for a given level of the statistical error, has a complexity significantly lower than the complexity of the standard Monte Carlo method. We analyze the asymptotic error of this algorithm in the context of general (possibly degenerate) diffusions. In order to find the optimal $\\beta$ (which turns out to be $\\beta=1/2$), we establish a central limit type theorem, based on a result of Jacod and Protter for the asymptotic distribution of the error in the Euler scheme. We test our method on various examples. In particular, we adapt it to Asian options. In this setting, we have a CLT and, as a by-produc...
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.
Xie, Feng; Li, Xuesong; Dai, Yihua; Jiang, Wengang; He, Xiaobing; Yu, Gongshuo; Ni, Jianzhong
2015-03-01
Noble gas (41)Ar was measured with a 4??-4?? coincidence system, in which gamma- and beta-rays were respectively detected with a well-type NaI(Tl) and plastic scintillator (PS) detector. The activity of (41)Ar was determined from an efficiency extrapolation method, in which the beta detector efficiency was varied by electronic discrimination using the software developed under Visual basic. In addition, high resolution gamma spectroscopy with HPGe detector was also used for activity determination of (41)Ar, and the result was satisfactory in agreement with that obtain by the efficiency extrapolation method. This work demonstrated that the activity of (41)Ar can be accurately measured by efficiency extrapolation method. PMID:25527895
First-principles extrapolation method for accurate CO adsorption energies on metal surfaces
Mason, S E; Rappe, A M; Mason, Sara E.; Grinberg, Ilya; Rappe, Andrew M.
2003-01-01
We show that a simple first-principles correction based on the difference between the singlet-triplet CO excitation energy values obtained by DFT and high-level quantum chemistry methods yields accurate CO adsorption properties on a variety of metal surfaces. We demonstrate a linear relationship between the CO adsorption energy and the CO singlet-triplet splitting, similar to the linear dependence of CO adsorption energy on the energy of the CO 2$\\pi$* orbital found recently {[Kresse {\\em et al.}, Physical Review B {\\bf 68}, 073401 (2003)]}. Converged DFT calculations underestimate the CO singlet-triplet excitation energy $\\Delta E_{\\rm S-T}$, whereas coupled-cluster and CI calculations reproduce the experimental $\\Delta E_{\\rm S-T}$. The dependence of $E_{\\rm chem}$ on $\\Delta E_{\\rm S-T}$ is used to extrapolate $E_{\\rm chem}$ for the top, bridge and hollow sites for the (100) and (111) surfaces of Pt, Rh, Pd and Cu to the values that correspond to the coupled-cluster and CI $\\Delta E_{\\rm S-T}$ value. The c...
Direct activity determination of 54Mn and 65Zn by a non-extrapolation liquid scintillation method.
Simpson, B R S; Morris, W M
2004-01-01
The measurement of 54Mn and 65Zn by liquid scintillation coincidence counting results in low detection efficiencies. The activity obtained from the extrapolation of efficiency data can therefore become problematic if curvature is present. The simple decay scheme exhibited by these radionuclides, with the emission of an energetic gamma ray, allows the absolute activity to be determined from 4pie-gamma data by direct calculation without the need for efficiency extrapolation. The method, which relies on determining the probability of the gamma-ray interacting with the scintillator solution, is described and validated by measurements made on 60Co. PMID:14987688
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
International Nuclear Information System (INIS)
A program to investigate the possibility of track extrapolation and interpolation for drift chambers with the Principal Components Analysis and polynoms was written for SAPHIR. The results for the most significant configurations at SAPHIR were pointed out. It was shown that the Principal Components Analysis is a good basis to write a fast track reconstruction program for a drift chamber using a global track model in an inhomogeneous magnetic field. A data input/output package was written, too. (orig.)
Waheed, Umair bin
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.
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
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)
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.
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.
Alves, Vale?ria A.; Paquim, Ana M. Chiorcea; Cavaleiro, Albano; Brett, Christopher M. A.
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
Infrared extrapolations for atomic nuclei
Furnstahl, R J; Papenbrock, T; Wendt, K A
2014-01-01
Harmonic oscillator model-space truncations introduce systematic errors to the calculation of binding energies and other observables. We identify the relevant infrared scaling variable and give values for this nucleus-dependent quantity. We consider isotopes of oxygen computed with the coupled-cluster method from chiral nucleon-nucleon interactions at next-to-next-to-leading order and show that the infrared component of the error is sufficiently understood to permit controlled extrapolations. By employing oscillator spaces with relatively large frequencies, well above the energy minimum, the ultraviolet corrections can be suppressed while infrared extrapolations over tens of MeVs are accurate for ground-state energies. However, robust uncertainty quantification for extrapolated quantities that fully accounts for systematic errors is not yet developed.
Bhattacharyya, Surjendu; Wategaonkar, Sanjay
2014-10-01
In this work we have shown that the Birge-Sponer extrapolation method can be successfully used to determine the dissociation energies (D0) of noncovalently bound complexes. The O-H···S hydrogen-bonding interaction in the cationic state of the p-fluorophenol···H2S complex was characterized using zero kinetic energy (ZEKE) photoelectron spectroscopy. This is the first ZEKE report on the O-H···S hydrogen-bonding interaction. The adiabatic ionization energy (AIE) of the complex was determined as 65?542 cm(-1). Various intermolecular and intramolecular vibrational modes of the cation were assigned. A long progression was observed in the intermolecular stretching mode (?) of the complex with significant anharmonicity along this mode. The anharmonicity information was used to estimate the dissociation energy (D0) in the cationic state using the Birge-Sponer extrapolation method. The D0 was estimated as 9.72 ± 1.05 kcal mol(-1). The ZEKE photoelectron spectra of analogous complex FLP···H2O was also recorded for the sake of comparison. The AIE was determined as 64?082 cm(-1). The intermolecular stretching mode in this system, however, was found to be quite harmonic, unlike that in the H2S complex. The dissociation energies of both the complexes, along with those of a few benchmark systems, such as phenol···H2O and indole···benzene complexes, were computed at various levels of theory such as MP2 at the complete basis set limit, ?B97X-D, and CCSD(T). It was found that only the ?B97X-D level values were in excellent agreement with the experimental results for the benchmark systems for the ground as well as the cationic states. The dissociation energy of the (FLP···H2S)(+) complex determined by the Birge-Sponer extrapolation was about ?18% lower than that computed at the ?B97X-D level. PMID:25250474
Optimal analytical extrapolations revisite
International Nuclear Information System (INIS)
The problem of optimal analytic extrapolation of holomorphic functions from a finite set of interior data points to an other interior point is completely solved in the general case of data known with unequal errors. Simple and easily to handle algorithms are obtained. (author)
Coherence extrapolation for underwater ambient noise.
Quijano, Jorge E; Dosso, Stan E; Siderius, Martin; Muzi, Lanfranco
2014-06-01
This paper considers extrapolation of the vertical coherence of surface-generated oceanic ambient noise to simulate measurements made on a longer sensor array. The extrapolation method consists of projecting the noise coherence measured with a limited aperture array into the domain spanned by prolate spheroidal wave functions, which are an orthogonal basis defined by array parameters and the noise frequency. Using simulated data corresponding to selected multi-layered seabeds as ground truth, the performance of the extrapolation method is explored. Application of the technique is also demonstrated on experimental data. PMID:24907840
Morales-bautista, Carlos M.; Adams, Randy H.; 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...
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.
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.
Li, Gang; Xu, Jiayun; Zhang, Jie
2014-10-22
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 (3)He 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, (3)He 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. PMID:25464188
Energy Technology Data Exchange (ETDEWEB)
Subramaniam, Kolluru V., E-mail: ksubram@ce.ccny.cuny.ed [Civil Engineering Department, City College of the City University of New York, New York, NY 10031 (United States); Bi Mingdong [Weidlinger Associates Inc., New York, NY 10014 (United States)
2010-08-15
Inhomogeneous corrosion in reinforced concrete is investigated using a beam with a flexural crack intersecting the reinforcement. An Evans diagram representation of the macrocell corrosion system is developed. The relationship between the current density and the potentials relative to the crack obtained from the Tafel polarization responses of active and passive steel in concrete compares favorably with the experimental values. When both microcell and macrocell mechanisms contribute to metal loss at the crack, the Evans diagram representation indicates that an increase in the macrocell current density results in a decreasing contribution from the local microcell at the macrocell anode.
Extrapolating future Arctic ozone losses
Directory of Open Access Journals (Sweden)
B. M. Knudsen
2004-06-01
Full Text Available Future increases in the concentration of greenhouse gases and water vapour are likely to cool the stratosphere further and to increase the amount of polar stratospheric clouds (PSCs. Future Arctic PSC areas have been extrapolated using the highly significant trends in the temperature record from 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 losses increase until 2010–2020 and only decrease slightly up to 2030. This approach is an alternative method of prediction to that based on the complex coupled chemistry-climate models (CCMs.
Uncertainties of Euclidean time extrapolation in lattice effective field theory
Lähde, Timo A.; Epelbaum, Evgeny; Krebs, Hermann; Lee, Dean; Meißner, Ulf-G.; Rupak, Gautam
2015-03-01
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 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.
Energy Technology Data Exchange (ETDEWEB)
Boutoux, G., E-mail: guillaume.boutoux@cea.fr [CNRS, IN2P3, CENBG, UMR 5797, F-33175 Gradignan (France); University Bordeaux, CENBG, UMR 5797, F-33175 Gradignan (France); CEA DAM DIF, F-91297 Arpajon (France); Jurado, B.; Mathieu, L. [CNRS, IN2P3, CENBG, UMR 5797, F-33175 Gradignan (France); University Bordeaux, CENBG, UMR 5797, F-33175 Gradignan (France); Méot, V. [CEA DAM DIF, F-91297 Arpajon (France); Aïche, M.; Barreau, G. [CNRS, IN2P3, CENBG, UMR 5797, F-33175 Gradignan (France); University Bordeaux, CENBG, UMR 5797, F-33175 Gradignan (France); Blanc, A. [CEA DAM DIF, F-91297 Arpajon (France); Companis, I. [CNRS, IN2P3, CENBG, UMR 5797, F-33175 Gradignan (France); University Bordeaux, CENBG, UMR 5797, F-33175 Gradignan (France); Roig, O.; Théroine, C. [CEA DAM DIF, F-91297 Arpajon (France)
2013-02-01
The surrogate-reaction method is an indirect technique to extract neutron-induced cross-sections of short-lived nuclei. In the last years several experiments have been performed to investigate whether this technique can be applied to infer radiative-capture cross-sections. A major difficulty in this type of measurements is the determination of the gamma-cascade detection efficiency. The pulse-height weighting technique (PHWT) has been previously used to determine this quantity in surrogate experiments. In this work, we present a new method to determine the gamma-cascade detection efficiency in the vicinity of the neutron-separation energy that is much simpler than the PHWT. We also investigate the possibility to apply this new technique in standard experiments using neutron beams.
International Nuclear Information System (INIS)
The surrogate-reaction method is an indirect technique to extract neutron-induced cross-sections of short-lived nuclei. In the last years several experiments have been performed to investigate whether this technique can be applied to infer radiative-capture cross-sections. A major difficulty in this type of measurements is the determination of the gamma-cascade detection efficiency. The pulse-height weighting technique (PHWT) has been previously used to determine this quantity in surrogate experiments. In this work, we present a new method to determine the gamma-cascade detection efficiency in the vicinity of the neutron-separation energy that is much simpler than the PHWT. We also investigate the possibility to apply this new technique in standard experiments using neutron beams.
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.
Extrapolation of solar irradiation measurements: case study over Egypt
Energy Technology Data Exchange (ETDEWEB)
Wahab, M.A. [Cairo University (Egypt). Faculty of Science; Essa, K.S.M. [Atomic Energy Authority, Cairo (Egypt). Nuclear Research Center
1998-05-01
Relationships for determining the maximum permissible distance for extrapolating daily totals of solar irradiation from measurement sites are established for mesoscale monitoring networks in Egypt. The proposed method involves calculation of the standard deviation of the daily differences in solar radiation receipt for each couple of measurement stations to determine the variability coefficient. This is related to distance between station pairs to establish relationship due to extrapolation distance. Results indicate that the solar climate has much greater spatial coherence which permit data extrapolation of data over long distances. A comparison to temperature extrapolated data confirm the same finding. (author)
Martin, Sheppard A; McLanahan, Eva D; Bushnell, Philip J; Hunter, E Sidney; El-Masri, Hisham
2015-02-01
To provide useful alternatives to in vivo animal studies, in vitro assays for dose-response assessments of xenobiotic chemicals must use concentrations in media and target tissues that are within biologically-plausible limits. Determining these concentrations is a complex matter, which can be facilitated by applying physiologically-based pharmacokinetic (PBPK) models in an in vitro to in vivo extrapolation (IVIVE) paradigm. We used ethanol (EtOH), a ubiquitous chemical with defined metrics for in vivo and in vitro embryotoxicity, as a model chemical to evaluate this paradigm. A published series of life-stage PBPK models for rats was extended to mice, yielding simulations that adequately predicted in vivo blood EtOH concentrations (BECs) from oral, intraperitoneal, and intravenous routes in nonpregnant and pregnant adult mice. The models were then extrapolated to nonpregnant and pregnant humans, replicating BEC data within a factor of two. The rodent models were then used to conduct IVIVEs for rodent and whole-embryo culture embryotoxicity data (neural tube closure defects, morphological changes). A second IVIVE was conducted for exposure scenarios in pregnant women during critical windows of susceptibility for developmental toxicity, such as the first 6-to-8 weeks (prerecognition period) or mid-to-late pregnancy period, when EtOH consumption is associated with fetal alcohol spectrum disorders. Incorporation of data from human embryonic stem cell studies led to a model-supported linkage of in vitro concentrations with plausible exposure ranges for pregnant women. This effort demonstrates benefits and challenges associated with use of multispecies PBPK models to estimate in vivo tissue concentrations associated with in vitro embryotoxicity studies. PMID:25410581
Migration and velocity analysis by wavefield extrapolation
Sava, Paul Constantin
2005-07-01
The goal of this thesis is to design methods for imaging complex geologic structures of the Earth's Lithosphere. Seeing complex structures is important for both exploration and nonexploration studies of the Earth and it involves dealing with complex wave propagation in media with large velocity contrasts. The approach I use to achieve this goal is depth imaging using acoustic waves. This approach consists of two components: migration and migration velocity analysis. No accurate imaging is possible without accurate, robust and efficient solutions to both components. I address both migration and migration velocity analysis in the general framework of one-way wavefield extrapolation. In this context, both imaging components are consistent and use the entire acoustic wavefields with accurate, robust and computationally feasible techniques. The migration state-of-the-art involves downward continuation of wavefields recorded at the Earth's surface. I introduce Riemannian wavefield extrapolation as a general framework for wavefield extrapolation. This technique allows us to overcome the steep-dip limitation of downward continuation, while retaining the main characteristics of wave-equation techniques. Riemannian wavefield extrapolation propagates waves in semi-orthogonal coordinate systems that conform with the general direction of wave propagation. Therefore, extrapolation is done forward relative to the direction in which waves propagate, so we can achieve high-angle accuracy with small-angle operators. The velocity estimation state-of-the-art involves traveltime tomography from sparse reflectors picked on migrated images. I introduce wave-equation migration velocity analysis as a more accurate and robust alternative. With this technique, I overcome the instability of traveltime tomography caused by ray tracing in areas with high velocity contrasts. I formulate wave-equation MVA with an operator based on linearization of wavefield extrapolation using the first-order Born approximation. I define the optimization objective function in the space of migrated images. Since the entire images are sensitive to migration velocities, I use image perturbations for optimization, in contrast with traveltime tomography which employs traveltime perturbations picked at selected locations. I construct image perturbations with linearized residual migration operators by measuring angle-gather flatness or spatial focusing.
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.
Biosimilars: the science of extrapolation.
Weise, Martina; Kurki, Pekka; Wolff-Holz, Elena; Bielsky, Marie-Christine; Schneider, Christian K
2014-11-20
Despite the establishment of a specific approval pathway, the issuance of detailed scientific guidelines for the development of similar biological medicinal products (so-called "biosimilars") and the approval of several biosimilars in the European Union, acceptance of biosimilars in the medical community continues to be low. This is especially true in therapeutic indications for which no specific clinical trials with the biosimilar have been performed and that have been licensed based on extrapolation of efficacy and safety data from other indications. This article addresses the concerns frequently raised in the medical community about the use of biosimilars in such extrapolated indications and explains the underlying scientific and regulatory decision making including some real-life examples from recently licensed biosimilars. PMID:25298038
Renyi extrapolation of Shannon entropy
Zyczkowski, Karol
2003-01-01
Relations between Shannon entropy and Renyi entropies of integer order are discussed. For any N-point discrete probability distribution for which the Renyi entropies of order two and three are known, we provide an lower and an upper bound for the Shannon entropy. The average of both bounds provide an explicit extrapolation for this quantity. These results imply relations between the von Neumann entropy of a mixed quantum state, its linear entropy and traces.
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.
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.
Flavor extrapolation in lattice QCD
International Nuclear Information System (INIS)
Explicit calculation of the effect of virtual quark-antiquark pairs in lattice QCD has eluded researchers. To include their effect explicitly one must calculate the determinant of the fermion-fermion coupling matrix. Owing to the large number of sites in a continuum limit size lattice, direct evaluation of this term requires an unrealistic amount of computer time. The effect of the virtual pairs can be approximated by ignoring this term and adjusting lattice couplings to reproduce experimental results. This procedure is called the valence approximation since it ignores all but the minimal number of quarks needed to describe hadrons. In this work the effect of the quark-antiquark pairs has been incorporated in a theory with an effective negative number of quark flavors contributing to the closed loops. Various particle masses and decay constants have been calculated for this theory and for one with no virtual pairs. The author attempts to extrapolate results towards positive numbers of quark flavors. The results show approximate agreement with experimental measurements and demonstrate the smoothness of lattice expectations in the number of quark flavors
Chiral extrapolation beyond the power-counting regime
International Nuclear Information System (INIS)
Chiral effective field theory can provide valuable insight into the chiral physics of hadrons when used in conjunction with nonperturbative schemes such as lattice quantum chromodynamics (QCD). In this discourse, the attention is focused on extrapolating the mass of the ? meson to the physical pion mass in quenched QCD. 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. 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 regularization scale, which is embedded in the lattice QCD data themselves. This optimal scale is the value of the regularization scale at which the renormalization of the low-energy coefficients is approximately independent of the range of quark masses considered. By using recent precision, quenched lattice results, the extrapolation is tested directly by truncating the analysis to a set of points above 380 MeV, while temporarily disregarding the simulation results closer to the chiral regime. This tests the ability of the method to make predictions of the simulation results, without phenomenologically motivated bias. The result is a succally motivated bias. The result is a successful extrapolation to the chiral regime.
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.
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.
International Nuclear Information System (INIS)
The corrosion inhibition characteristics of non-ionic surfactants of the TRITON-X series, known as TRITON-X-100 (TX-100), TRITON-X-165 (TX-165) and TRITON-X-305 (TX-305), on iron in 1.0 M HCl solution were studied. Measurements were conducted in 1.0 M HCl solutions without and with various concentrations of the three selected surfactants using chemical (ICP-AES method of analysis of dissolved cations) and electrochemical (Tafel polarisation and EFM) techniques at 25 deg. C. These measurements were complemented with SEM and EDX examinations of the electrode surface. Polarisation data showed that the non-ionic surfactants used in this study acted as mixed-type inhibitors with cathodic predominance. The protection efficiency increased with increase in surfactant concentration. Maximum protection efficiency of the surfactant was observed at concentrations around its CMC. From their molecular structure, these surfactants may adsorb on the metal surface through two lone pairs of electrons on the oxygen atoms of the hydrophilic head group.
Cosmogony as an extrapolation of magnetospheric research
Energy Technology Data Exchange (ETDEWEB)
Alfven, H.
1984-10-01
A theory of the origin and evolution of the Solar System which considered electromagnetic forces and plasma effects is revised in light of information supplied by space research. In situ measurements in the magnetospheres and solar wind can be extrapolated outwards in space, to interstellar clouds, and backwards in time, to the formation of the solar system. The first extrapolation leads to a revision of cloud properties essential for the early phases in the formation of stars and solar nebulae. The latter extrapolation facilitates analysis of the cosmogonic processes by extrapolation of 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 is possible to reconstruct events 4 to 5 billion years ago with an accuracy of a few percent. 29 references.
Cosmogony as an extrapolation of magnetospheric research
Alfven, H.
1984-01-01
A theory of the origin and evolution of the Solar System which considered electromagnetic forces and plasma effects is revised in light of information supplied by space research. In situ measurements in the magnetospheres and solar wind can be extrapolated outwards in space, to interstellar clouds, and backwards in time, to the formation of the solar system. The first extrapolation leads to a revision of cloud properties essential for the early phases in the formation of stars and solar nebulae. The latter extrapolation facilitates analysis of the cosmogonic processes by extrapolation of 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 is possible to reconstruct events 4 to 5 billion years ago with an accuracy of a few percent.
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. ...
Motion Extrapolation in the Central Fovea
Shi, Zhuanghua; Nijhawan, Romi
2012-01-01
Neural transmission latency would introduce a spatial lag when an object moves across the visual field, if the latency was not compensated. A visual predictive mechanism has been proposed, which overcomes such spatial lag by extrapolating the position of the moving object forward. However, a forward position shift is often absent if the object abruptly stops moving (motion-termination). A recent "correction-for-extrapolation" hypothesis suggests that the absence of forward shifts is caused by...
Motion Extrapolation in the Central Fovea
Shi, Zhuanghua; Nijhawan, Romi
2012-01-01
Neural transmission latency would introduce a spatial lag when an object moves across the visual field, if the latency was not compensated. A visual predictive mechanism has been proposed, which overcomes such spatial lag by extrapolating the position of the moving object forward. However, a forward position shift is often absent if the object abruptly stops moving (motion-termination). A recent “correction-for-extrapolation” hypothesis suggests that the absence of forward shifts is caused by sensory signals representing ‘failed’ predictions. Thus far, this hypothesis has been tested only for extra-foveal retinal locations. We tested this hypothesis using two foveal scotomas: scotoma to dim light and scotoma to blue light. We found that the perceived position of a dim dot is extrapolated into the fovea during motion-termination. Next, we compared the perceived position shifts of a blue versus a green moving dot. As predicted the extrapolation at motion-termination was only found with the blue moving dot. The results provide new evidence for the correction-for-extrapolation hypothesis for the region with highest spatial acuity, the fovea. PMID:22438976
Ya?a, F.
2007-04-01
In this work the problem of extrapolation distances has been studied in one-speed neutron transport equation with isotropic scattering by using the Chebyshev polynomial approximation which is called TN method. Assuming neutrons of one speed, extrapolation distances are calculated for the uniform finite slab using Mark and Marshak type vacuum boundary conditions. It is shown that extrapolation of the flux of neutrons leaking from the medium, in low order TN method, gives very good results of low order spherical harmonics approximation which is known PN method and diffusion theory.
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)
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
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.
Experiences and extrapolations from Hiroshima and Nagasaki
International Nuclear Information System (INIS)
This chapter examines events following the atomic bombings of Hiroshima and Nagasaki in 1945 and extrapolates from these experiences in an attempt to understand the possible consequences of detonations on a local area from weapons in the current world nuclear arsenal. The limitations of drawing upon the Hiroshima and Nagasaki experiences are discussed. Comparison is made of the scale of effects from other major disasters for urban systems, such as damages from conventional bombings, consequences of major earthquakes, historical effects of the Black Plague, widespread famines and other extreme natural events. It is concluded that mere extrapolation from the experiences of Hiroshima and Nagasaki has consistently led to a gross underestimation of what the consequences of the next nuclear war would be for the global human population. (UK)
Universal properties of infrared oscillator basis extrapolations
More, S. N.; Ekstrom, A.; Furnstahl, R. J.; Hagen, G.; Papenbrock, T.
2013-01-01
Recent work has shown that a finite harmonic oscillator basis in nuclear many-body calculations effectively imposes a hard-wall boundary condition in coordinate space, motivating infrared extrapolation formulas for the energy and other observables. Here we further refine these formulas by studying two-body models and the deuteron. We accurately determine the box size as a function of the model space parameters, and compute scattering phase shifts in the harmonic oscillator b...
Surface dose extrapolation measurements with radiographic film
International Nuclear Information System (INIS)
Assessment of surface dose delivered from radiotherapy x-ray beams for optimal results should be performed both inside and outside the prescribed treatment fields. An extrapolation technique can be used with radiographic film to perform surface dose assessment for open field high energy x-ray beams. This can produce an accurate two-dimensional map of surface dose if required. Results have shown that the surface percentage dose can be estimated within ±3% of parallel plate ionization chamber results with radiographic film using a series of film layers to produce an extrapolated result. Extrapolated percentage dose assessment for 10 cm, 20 cm and 30 cm square fields was estimated to be 15% ± 2%, 29% ± 3% and 38% ± 3% at the central axis and relatively uniform across the treatment field. The corresponding parallel plate ionization chamber measurements are 16%, 27% and 37%, respectively. Surface doses are also measured outside the treatment field which are mainly due to scattered electron contamination. To achieve this result, film calibration curves must be irradiated to similar x-ray field sizes as the experimental film to minimize quantitative variations in film optical density caused by varying x-ray spectrum with field size. (note)
Surface dose extrapolation measurements with radiographic film.
Butson, Martin J; Cheung, Tsang; Yu, Peter K N; Currie, Michael
2004-07-01
Assessment of surface dose delivered from radiotherapy x-ray beams for optimal results should be performed both inside and outside the prescribed treatment fields. An extrapolation technique can be used with radiographic film to perform surface dose assessment for open field high energy x-ray beams. This can produce an accurate two-dimensional map of surface dose if required. Results have shown that the surface percentage dose can be estimated within +/-3% of parallel plate ionization chamber results with radiographic film using a series of film layers to produce an extrapolated result. Extrapolated percentage dose assessment for 10 cm, 20 cm and 30 cm square fields was estimated to be 15% +/- 2%, 29% +/- 3% and 38% +/- 3% at the central axis and relatively uniform across the treatment field. The corresponding parallel plate ionization chamber measurements are 16%, 27% and 37%, respectively. Surface doses are also measured outside the treatment field which are mainly due to scattered electron contamination. To achieve this result, film calibration curves must be irradiated to similar x-ray field sizes as the experimental film to minimize quantitative variations in film optical density caused by varying x-ray spectrum with field size. PMID:15285265
Radiographic film: surface dose extrapolation techniques
International Nuclear Information System (INIS)
Full text: Assessment of surface dose delivered from radiotherapy x-ray beams for optimal results should be performed both inside and outside the prescribed treatment fields An extrapolation technique can be used with radiographic film to perform surface dose assessment for open field high energy x-ray beams. This can produce an accurate 2 dimensional map of surface dose if required. Results have shown that surface % dose can be estimated within ±3% of parallel plate ionisation chamber results with radiographic film using a series of film layers to produce an extrapolated result. Extrapolated percentage dose assessment for 10cm, 20cmand 30cm square fields was estimated to be 15% ± 2%, 29% ± 3% and 38% ± 3% at the central axis and relatively uniform across the treatment field. Corresponding parallel plate ionisation chamber measurement are 16%, 27% and 37% respectively. Surface doses are also measured outside the treatment field which are mainly due to scattered electron contamination. To achieve this result, film calibration curves must be irradiated to similar x-ray field sizes as the experimental film to minimize quantitative variations in film optical density caused by varying x-ray spectrum with field size. Copyright (2004) Australasian College of Physical Scientists and Engineers in Medicine
In situ LTE exposure of the general public: Characterization and extrapolation.
Joseph, Wout; Verloock, Leen; Goeminne, Francis; Vermeeren, Günter; Martens, Luc
2012-09-01
In situ radiofrequency (RF) exposure of the different RF sources is characterized in Reading, United Kingdom, and an extrapolation method to estimate worst-case long-term evolution (LTE) exposure is proposed. All electric field levels satisfy the International Commission on Non-Ionizing Radiation Protection (ICNIRP) reference levels with a maximal total electric field value of 4.5 V/m. The total values are dominated by frequency modulation (FM). Exposure levels for LTE of 0.2 V/m on average and 0.5 V/m maximally are obtained. Contributions of LTE to the total exposure are limited to 0.4% on average. Exposure ratios from 0.8% (LTE) to 12.5% (FM) are obtained. An extrapolation method is proposed and validated to assess the worst-case LTE exposure. For this method, the reference signal (RS) and secondary synchronization signal (S-SYNC) are measured and extrapolated to the worst-case value using an extrapolation factor. The influence of the traffic load and output power of the base station on in situ RS and S-SYNC signals are lower than 1 dB for all power and traffic load settings, showing that these signals can be used for the extrapolation method. The maximal extrapolated field value for LTE exposure equals 1.9 V/m, which is 32 times below the ICNIRP reference levels for electric fields. PMID:22271226
Off-shell extrapolation for B ? ?+?- decay
International Nuclear Information System (INIS)
The inclusion of the strong interaction effects in the theory of exclusive nonleptonic B decays is a very difficult task. The problem has been investigated recently by many authors, in particular, for charmless decays into light pseudoscalar mesons, since the strong phases of these amplitudes are crucial for the determination of CP-violating phases in present and future experiments. Recent calculations of the B ? ?+?- decay amplitude were performed either in the generalized QCD factorization approach and the conventional perturbative QCD, or in a hadronic approach. We consider the decay amplitude A (p, k1,k2) + ?-, out|Hw(0)|Bd0, in>, where the 'in' and 'out' states are defined with respect to the strong interactions and Hw is the weak effective Hamiltonian. The decay amplitude can be split as A =Vud Vub* Au + Vcd Vcb* Ac, with the CP violating phase ? Arg(Vub*) appearing in the first term. The physical amplitude is calculated for p = k1+k2 at on-shell values of the momenta, p2 = mB2, k12= m?2, k22 = m?2. The extrapolation to off-shell external momenta can be achieved by the LSZ reduction formalism. Tby the LSZ reduction formalism. This procedure was applied to the first expression of the amplitude above. However, it is more convenient to start from the S-matrix element of the decay and apply the LSZ reduction to the B meson and one of the final pions. This method allows us to make an analytic continuation either with respect to in the squared momentum p2 of the B-meson, or with respect with the squared momentum k12 of one final pion. We obtain in both cases dispersion relations with spectral functions describing final state and initial state interactions, which involve complicated off-shell amplitudes. Actually, one can derive dispersion relations for each of the amplitudes Au and Ac appearing in the second expression of the amplitude above. In particular, the dispersion relations with respect to the momentum squared k12 of one final meson can be written as Aj = Aj,0 + ?j,FSI/? ln[m?2/(mB - m?)2-1], for j=u,c. In this relation, ?j,FSI is the on-shell spectral function describing the final state interactions ?j,FSI ??n ?(k1 + k2 - pn) M* (n? ??) Aj(B?n), where M (Aj) denote strong (weak) amplitudes, respectively, and Aj,0 is the amplitude in the limit of vanishing final state interactions. Using arguments based on quark-hadron duality, one can show that the dominant contribution to Aj,0 is given by the factorized amplitude. The representation given above as expression of Aj, combined with the Regge model for the high-energy strong interactions, can be used to derive corrections to the factorized amplitude, produced by the final state interactions in the heavy quark limit. We notice that in the hadronic formalism the real part of the final state interaction amplitude is suppressed by two powers of the heavy mass, compared to the imaginary part. The dominant corrections to the imaginary part are given by the next to leading logarithmic term of the pomeron contribution. Other sources of large power corrections to the factorized amplitude are not found, assuming that multiparticle effects are qualitatively taken into account by the Goldberger-Treiman method of calculating the spectral functions. Using for illustration a numerical input suggested by QCD factorization, the results indicate that the phase and the modulus of the ratio Ac/Au are not drastically modified by the final state interactions. With the improved results of QCD factorization calculations, expected in the future, it will be possible to test the dispersion relations conjectured in the present work and, more generally, the validity of quark-hadron duality. (authors)
Chiral and continuum extrapolation of partially-quenched hadron masses
International Nuclear Information System (INIS)
Using the finite-range regularization (FRR) of chiral effective field theory, the chiral extrapolation formula for the vector meson mass is derived for the case of partially-quenched QCD. We re-analyze the dynamical fermion QCD data for the vector meson mass from the CP-PACS collaboration. A global fit, including finite lattice spacing effects, of all 16 of their ensembles is performed. We study the FRR method together with a naive polynomial approach and find excellent agreement (?1%) with the experimental value of M? from the former approach. These results are extended to the case of the nucleon mass
A New Code for Nonlinear Force-Free Field Extrapolation of the Global Corona
Jiang, Chaowei; 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 extrapolation is still under developing. A high-performance global extrapolation code is in particular urgently needed considering that Solar Dynamics Observatory (SDO) can provide full-disk magnetogram with resolution up to $4096\\times 4096$. In this work, we present a new parallelized code for global NLFFF extrapolation with the photosphere magnetogram as input. The method is based on magnetohydrodynamics relaxation approach, the CESE-MHD numerical scheme and a Yin-Yang spherical grid that is used to overcome the polar problems of the sta...
The extrapolation of creep rupture data by PD6605 - An independent case study
International Nuclear Information System (INIS)
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 a nonlinear force-free field containing a highly twisted magnetic loop
Valori, G.; Kliem, B.; Keppens, R.
2005-04-01
The stress-and-relax method for the extrapolation of nonlinear force-free coronal magnetic fields from photospheric vector magnetograms is formulated and implemented in a manner analogous to the evolutionary extrapolation method. The technique is applied to a numerically constructed force-free equilibrium that has a simple bipolar structure of the normal field component in the bottom (magnetogram) plane but contains a highly twisted loop and a shear (current) layer, with a smooth but strong variation of the force-free parameter ? in the magnetogram. A standard linear force-free extrapolation of this magnetogram, using the so-called ?_best value, is found to fail in reproducing the twisted loop (or flux rope) and the shear layer; it yields a loop pair instead and the shear is not concentrated in a layer. With the nonlinear extrapolation technique, the given equilibrium is readily reconstructed to a high degree of accuracy if the magnetogram is sufficiently resolved. A parametric study quantifies the requirements on the resolution for a successful nonlinear extrapolation. Permitting magnetic reconnection by a controlled use of resistivity improved the extrapolation at a resolution comparable to the smallest structures in the magnetogram.
Universal properties of infrared oscillator basis extrapolations
More, S. N.; Ekström, A.; Furnstahl, R. J.; Hagen, G.; Papenbrock, T.
2013-04-01
Recent work has shown that a finite harmonic oscillator basis in nuclear many-body calculations effectively imposes a hard-wall boundary condition in coordinate space, motivating infrared extrapolation formulas for the energy and other observables. Here we further refine these formulas by studying two-body models and the deuteron. We accurately determine the box size as a function of the model space parameters, and compute scattering phase shifts in the harmonic oscillator basis. We show that the energy shift can be well approximated in terms of the asymptotic normalization coefficient and the bound-state momentum, discuss higher-order corrections for weakly bound systems, and illustrate this universal property using unitarily equivalent calculations of the deuteron.
Universal properties of infrared oscillator basis extrapolations
More, S N; Furnstahl, R J; Hagen, G; Papenbrock, T
2013-01-01
Recent work has shown that a finite harmonic oscillator basis in nuclear many-body calculations effectively imposes a hard-wall boundary condition in coordinate space, motivating infrared extrapolation formulas for the energy and other observables. Here we further refine these formulas by studying two-body models and the deuteron. We accurately determine the box size as a function of the model space parameters, and compute scattering phase shifts in the harmonic oscillator basis. We show that the energy shift can be well approximated in terms of the asymptotic normalization coefficient and the bound-state momentum, discuss higher-order corrections for weakly bound systems, and illustrate this universal property using unitarily equivalent calculations of the deuteron.
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...
Hard hadronic collisions: extrapolation of standard effects
International Nuclear Information System (INIS)
We study hard hadronic collisions for the proton-proton (pp) and the proton-antiproton (p anti p) option in the CERN LEP tunnel. Based on our current knowledge of hard collisions at the present CERN p anti p Collider, and with the help of quantum chromodynamics (QCD), we extrapolate to the next generation of hadron colliders with a centre-of-mass energy E/sub cm/ = 10 to 20 TeV. We estimate various signatures, trigger rates, event topologies, and associated distributions for a variety of old and new physical processes, involving prompt photons, leptons, jets, W+- and Z bosons in the final state. We also calculate the maximum fermion and boson masses accessible at the LEP Hadron Collider. The standard QCD and electroweak processes studied here, being the main body of standard hard collisions, quantify the challenge of extracting new physics with hadron colliders. We hope that our estimates will provide a useful profile of the final states, and that our experimental physics colleagues will find this of use in the design of their detectors. 84 references
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.)
Scaling and extrapolation of hydrogen distribution experiments
International Nuclear Information System (INIS)
The containment plays an important role in predicting the residual risk to the environment under severe accident conditions. Risk analyses show that massive fission product release from the reactor fuel can occur only if during a loss of coolant the core is severely damaged and a containment failure is anticipated. Large amounts of hydrogen inevitably, are formed during the core degradation and will be released into the containment. More combustible gases are produced later when the coremelt will contact the containment concrete. Thus a potential for an early containment failure exists if a massive hydrogen deflagration cannot be excluded. A more remote cause for early containment failure may be an energetic steam explosion which requires a number of independent conditions when the molten core material contacts residual coolant water. The prediction of the containment loads caused by a hydrogen combustion is dependent on the prediction of the combustion mode. In the paper an attempt is made to identify on basis of a dimensional analysis such areas for which particular care must be exercised when scale experimental evidence is interpreted and extrapolated with the aid of a computer code or a system of computer codes. The study is restricted to fluid dynamic phenomena of the gas distribution process within the containment atmosphere. The gas sources and the mechanical response of containment structures are considered as given boundary conditions under which the containmundary conditions under which the containment is to be analyzed
Energy Technology Data Exchange (ETDEWEB)
Crawford, D.J.; Richmond, C.R.
1980-01-01
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.
Wiegelmann, Thomas; Inhester, Bernd; Kliem, Bernhard; Valori, Gherardo; Neukirch, Thomas
2006-01-01
CONTEXT: As the coronal magnetic field can usually not be measured directly, it has to be extrapolated from photospheric measurements into the corona. AIMS: We test the quality of a non-linear force-free coronal magnetic field extrapolation code with the help of a known analytical solution. METHODS: The non-linear force-free equations are numerically solved with the help of an optimization principle. The method minimizes an integral over the force-free and solenoidal conditi...
Direct Extrapolation of Biota-sediment Accumulation Factors (BSAFs)
Biota-sediment accumulation factors (BSAFs) for fish and shellfish were extrapolated directly from one location and species to other species, to other locations within a site, to other sites, and their combinations. The median errors in the extrapolations across species at a loc...
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 typees 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.
Slow neutron flux extrapolation distances in R-5 and CIRUS reactors
International Nuclear Information System (INIS)
In order to calculate the core reactivity, fuel channel power outputs and neutron flux levels in the R-5 reactor at Trombay, axial flux extrapolation distances are required. For this, an analysis is carried out considering the reactor core as a two region neutron multiplying system in axial direction. The slow neutron diffusion equations for both the regions are solved analytically by applying suitable boundary conditions. Application of this method for the estimation of top extrapolation distances in CIRUS, has given results which agree well with accepted values for the reactor. (author)
Imaging of steep reflectors in anisotropic media by wavefield extrapolation
Shan, Guojian
Seismic migration based on isotropic downward continuation is an effective technique for imaging complex subsurface geologic structure. However, this approach has difficulty in imaging steep reflectors, such as faults and salt flanks, that are often important in hydrocarbon exploration. Waves illuminating steep reflectors usually have nearly horizontal or overturned raypaths. This thesis addresses two major challenges in propagating these types of waves using isotropic downward continuation methods. First, when anisotropy is present in the subsurface, the errors associated with propagating near-horizontal waves under the isotropic assumption become severe. Second, downward continuation methods using the one-way wave equation have difficulty propagating near-horizontal or overturned waves. In theory, both issues can be resolved by using anisotropic reverse-time migration, which uses the two-way wave-equation, but such schemes are significantly more computationally expensive. I present a new one-way wave-equation based method that efficiently images steep reflectors in anisotropic media. First, I incorporate anisotropy in wave propagation by developing a new one-way wavefield extrapolation scheme, optimized finite-difference, for anisotropic media. The scheme is designed by fitting the dispersion relation with a rational function using the weighted least-squares methods, and it propagates waves accurately and efficiently in anisotropic media. Synthetic data examples show that with anisotropy taken into account, reflectors are positioned correctly with this scheme. Second, I develop a new migration algorithm, plane-wave migration in tilted coordinates. The recorded surface data are transformed by slant stacking to a collection of plane-wave source datasets with all possible take-off angles. Each plane-wave source dataset is migrated independently in a tilted coordinate system with the tilting angle determined by the take-off angle of the plane-wave source. For waves illuminating steep reflectors, the propagation direction is close to the extrapolation direction, thus they are accurately propagated by plane-wave migration in tilted coordinates. For steep reflectors in tilted coordinates, the subsurface offset direction is close to the dip direction of reflectors, thus plane-wave migration in tilted coordinates generates robust angle-domain common-image gathers for steep reflectors. I apply plane-wave migration in tilted coordinates to synthetic and 3D field datasets. Results show that steep salt flanks and faults are well imaged.
Pansini, F N N; Neto, A C; Varandas, A J C
2015-02-19
A method previously suggested to calculate the correlation energy at the complete one-electron basis set limit by reassigning the basis hierarchical numbers and using the unified singlet- and triplet-pair extrapolation scheme is here utilized to extrapolate tensorial properties, with specific use for the polarizabilities of eight molecules whose raw values are obtained with second-order Møller-Plesset perturbation theory and coupled-cluster singles and doubles excitation methods, both without and with inclusion of the perturbative triples correction. 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 reinforces our previous finding that there is no good reason to exclude double-? results in extrapolations, especially if the basis is calibrated to comply with the theoretical model. PMID:25619823
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...
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 SciELO Brazil | Language: Portuguese Abstract in portuguese O objetivo deste estudo foi avaliar o protocolo de contenção química com cetamina S(+) e midazolam em bugios-ruivos, comparando o cálculo de doses pelo método convencional e o método de extrapolação alométrica. Foram utilizados 12 macacos bugios (Alouatta guariba clamitans) hígidos, com peso médio d [...] e 4,84±0,97kg, de ambos os sexos. Após jejum alimentar de 12 horas e hídrico de seis horas, realizou-se contenção física manual e aferiram-se os seguintes parâmetros: frequência cardíaca (FC), frequência respiratória (f), tempo de preenchimento capilar (TPC), temperatura retal (TR), pressão arterial sistólica não invasiva (PANI) e valores de hemogasometria arterial. Posteriormente, os animais foram alocados em dois grupos: GC (Grupo Convencional, n=06), os quais receberam cetamina S(+) (5mg kg-1) e midazolam (0,5mg kg-1), pela via intramuscular, com doses calculadas pelo método convencional; e GA (Grupo Alometria, n=06), os quais receberam o mesmo protocolo, pela mesma via, utilizando-se as doses calculadas pelo método de extrapolação alométrica. Os parâmetros descritos foram mensurados novamente nos seguintes momentos: M5, M10, M20 e M30 (cinco, 10, 20 e 30 minutos após a administração dos fármacos, respectivamente). Também foram avaliados: qualidade de miorrelaxamento, reflexo podal e caudal, pinçamento interdigital, tempo para indução de decúbito, tempo hábil de sedação, qualidade de sedação, e tempo e qualidade de recuperação. O GA apresentou menor tempo para indução ao decúbito, maior grau e tempo de sedação, bem como redução significativa da FC e PANI de M5 até M30, quando comparado ao GC. Conclui-se que o grupo no qual o cálculo de dose foi realizado por meio da alometria (GA) apresentou melhor grau de relaxamento muscular e sedação, sem produzir depressão cardiorrespiratória significativa. Abstract in english The aim of this study was to evaluate a protocol of chemical restraint comparing the conventional method of calculation (weight dose) and allometric extrapolation. Twelve healthy red howler monkeys (Alouatta guariba clamitans), average weight 4.84±0.97kg, male and female, were used for this study. A [...] fter a 12-hour period of food restriction and 6 hours of water restriction, the animals were physically restraint and the following parameters were measured: heart rate (HR), respiratory rate (RR), capillary refill time (CRT), rectal temperature (RT), non invasive systolic arterial pressure (NISAP) and arterial blood gases analysis. The animals were distributed into two groups: CG (Conventional Group, n=6), in which the animals received S(+) ketamine (5mg kg-1) and midazolam (0.5mg kg-1), by intramuscular (IM) injection; and AG (Allometry Group, n=6), in which the animals also received S(+) ketamine and midazolan IM, but the doses were calculated by allometric extrapolation. Parameters were evaluated at the following moments: M5, M10, M20 and M30 (5, 10, 20 and 30 minutes after IM injection, respectively). Muscle relaxation, pedal and caudal reflexes, interdigital pinch, recumbency time, sedation's quality and duration, and recovery time and its quality were also evaluated. The AG had a faster time for recumbency, higher period and quality of sedation, and a significantly reduction on HR and SAP from M5 to M30 when compared to CG. It was concluded that allometric extrapolation presented a better muscle relaxation and sedation without significant cardiorespiratory depression.
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.
Determination of transmission factors in tissue using a standard extrapolation chamber
International Nuclear Information System (INIS)
A commercial ionization chamber, Böhm extrapolation chamber, PTW, model 23392, recommended for measurements in low energy X-rays and beta radiation fields, was tested in three different 90Sr+90Y beams to verify its performance as a primary standard system for the calibration and dosimetry of beta radiation sources and detectors. Characterization tests were performed, as determination of the chamber null depth using two methods (the results presented a difference of only 0.9%), transmission factors in tissue, in comparison with those of the certificate (the maximum difference was 2.1%), and absorbed dose rates of the 90Sr+90Y sources, in comparison with the values provided by the calibration certificates (the maximum difference was 4.90%). The results obtained confirmed that this extrapolation chamber presents a very good behavior in beta radiation fields as a primary standard system. - Highlights: • Böhm extrapolation chamber was tested to be used as a primary standard system. • The chamber was exposed to the three 90Sr+90Y secondary standard sources. • Transmission factors were obtained. • Absorbed dose rates were determined using the sources at certificate conditions. • The results showed the good performance of the extrapolation chamber
Gong, Lebing
2013-04-01
Estimation of world water resources under a changing climate is a key scientific issue for many environmental research areas with profound socio-economic significance. A new data-based scale-extrapolation method (Gong 2012) is proposed to estimate continental and regional water resources. The new method builds upon the assumption (Gong 2012) that, the dynamic interaction between climate and hydrology of a large river basin can be equally well resembled by multiple small regions, each characterized by a number of small river basins, which are typically two-orders-of-magnitude smaller than the large basin. Those small river basins contain sufficient information, not only on climate and land surface, but also on hydrological characteristics of the large region. Therefore, those multiple small regions can provide an ensemble of water recourse estimations for the large basin. The new method makes it possible for regional water resource estimations to benefit from a multitude of readily available measurements from small river basins. The scale-extrapolation methods also made it possible to study the interaction between climate and hydrology, and the climate change impact in un-gauged or partially gauged large river basins from data alone. The method offers ensemble predictions that bracket the estimation uncertainty. Because the scale-extrapolation uses different data and method compared to the modelling approach, it provides a unique opportunity to be compared with modelling results. Gong L., 2012. Data-based discharge extrapolation: estimating annual discharge for a partially gauged large river basin from its small sub-basins. Hydrol. Earth Syst. Sci. Discuss., 9, 6829-6856, 2012. doi:10.5194/hessd-9-6829-2012.
Resolution enhancement in digital holography by self-extrapolation of holograms
Latychevskaia, Tatiana; Fink, Hans-werner
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 rec...
Bopp, Matthias; Zellweger, Ulrich; Faeh, David
2011-01-01
OBJECTIVE Information on diabetes prevalence in the general population is scarce and often based on extrapolations. We evaluated whether prevalence could be estimated from routine data sources. RESEARCH DESIGN AND METHODS The sources were 1) hospital discharges (2008, n = 828,171), 2) death registry (2007/2008, n = 118,659), and 3) Swiss Health Survey (SHS; 2007, n = 18,665). Persons without diabetes as underlying cause of death (death registry) or principal diagnosis (hospital discharges) w...
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...
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
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.
Extrapolation of ASDEX Upgrade H-mode discharges to ITER
Tardini, G.; Kardaun, O. J. W. F.; Peeters, A. G.; Pereverzev, G. V.; Sips, A. C. C.; Stober, J.; ASDEX Upgrade Team
2009-07-01
In this paper we discuss a procedure to evaluate the fusion performance of ASDEX Upgrade discharges scaled up to ITER. The kinetic profile shape is taken from the measured profiles. Multiplication factors are used to obtain a fixed Greenwald fraction and an ITER normalized thermal pressure as in the corresponding ASDEX Upgrade discharge. The toroidal field and the plasma geometry are taken from the ITER-FEAT design (scenario 2), whereas q95 is taken from the experiment. The confinement time is inferred assuming that the measured H-factor with respect to several existing scaling laws also holds for ITER. While retaining the information contained in the multi-machine databases underlying the different scaling laws, this approach adds profile effects and confinement improvement with respect to the ITER baseline, thus including recent experimental evidence such as the prediction of peaked density profiles in ITER. Under this set of assumptions, of course not unique, we estimate the ITER performance on the basis of a wide database of ASDEX Upgrade H-mode discharges, in terms of fusion power, fusion gain and triple product. According to the three scalings considered, there is a finite probability of reaching ignition, while more than half of the discharges require less auxiliary power than the one foreseen for ITER. For all the scaling laws, high values of the thermal ?N up to 2.4 are accessible. A sensitivity study gives an estimate of the accuracy of the extrapolation. The impact of different levels of tungsten concentration on the fusion performance is also studied in this paper. This scaling method is used to verify some common 0D figures of merit of ITER's fusion performance.
Extrapolation of ASDEX Upgrade H-mode discharges to ITER
International Nuclear Information System (INIS)
In this paper we discuss a procedure to evaluate the fusion performance of ASDEX Upgrade discharges scaled up to ITER. The kinetic profile shape is taken from the measured profiles. Multiplication factors are used to obtain a fixed Greenwald fraction and an ITER normalized thermal pressure as in the corresponding ASDEX Upgrade discharge. The toroidal field and the plasma geometry are taken from the ITER-FEAT design (scenario 2), whereas q95 is taken from the experiment. The confinement time is inferred assuming that the measured H-factor with respect to several existing scaling laws also holds for ITER. While retaining the information contained in the multi-machine databases underlying the different scaling laws, this approach adds profile effects and confinement improvement with respect to the ITER baseline, thus including recent experimental evidence such as the prediction of peaked density profiles in ITER. Under this set of assumptions, of course not unique, we estimate the ITER performance on the basis of a wide database of ASDEX Upgrade H-mode discharges, in terms of fusion power, fusion gain and triple product. According to the three scalings considered, there is a finite probability of reaching ignition, while more than half of the discharges require less auxiliary power than the one foreseen for ITER. For all the scaling laws, high values of the thermal ?N up to 2.4 are accessible. A sensitivity study gives an estimate of the accuracy ostudy gives an estimate of the accuracy of the extrapolation. The impact of different levels of tungsten concentration on the fusion performance is also studied in this paper. This scaling method is used to verify some common 0D figures of merit of ITER's fusion performance.
Localization and extrapolation in Lorentz-Orlicz spaces.
Czech Academy of Sciences Publication Activity Database
Cruz-Uribe, D.; Krbec, Miroslav
Berlin : de Gruyter, 2002 - (Kufner, A.; Persson, L.; Sparr, M.), s. 389-401 ISBN 3-11-017117-1. [Function Spaces, Interpolation Theory and Related Topics. Lund (SE), 17.08.2001-22.08.2001] Institutional research plan: CEZ:AV0Z1019905 Keywords : extrapolation * localisation * Lorentz-Orlicz spaces Subject RIV: BA - General Mathematics
Freeze-out parameters from continuum extrapolated lattice data
Borsanyi, S; Katz, S D; Krieg, S; Ratti, C; Szabo, K K
2013-01-01
We present continuum extrapolated lattice results for the higher order fluctuations of conserved charges in high temperature Quantum Chromodynamics. Through the matching of the grand canonical ensemble on the lattice to the net charge and net baryon distribution realized in heavy ion experiments the temperature and the chemical potential may be estimated at the time of chemical freeze-out
Flux extrapolation models used in the DOT IV discrete ordinates neutron transport code
International Nuclear Information System (INIS)
The DOT IV code solves the Boltzmann transport equation in two dimensions using the method of discrete ordinates. Special techniques have been incorporated in this code to mitigate the effects of flux extrapolation error in space meshes of practical size. This report presents the flux extrapolation models as they appear in DOT IV. A sample problem is also presented to illustrate the effects of the various models on the resultant flux. Convergence of the various models to a single result as the mesh is refined is also examined. A detailed comparison with the widely used TWOTRAN II code is reported. The features which cause DOT and TWOTRAN to differ in the converged results are completely observed and explained
Taylor, Nicholas W; Reisswig, Christian; Scheel, Mark A; Chu, Tony; Kidder, Lawrence E; Szilagyi, Bela
2013-01-01
We extract gravitational waveforms from numerical simulations of black hole binaries computed using the Spectral Einstein Code. We compare two extraction methods: direct construction of the Newman-Penrose (NP) scalar $\\Psi_4$ at a finite distance from the source and Cauchy-characteristic extraction (CCE). The direct NP approach is simpler than CCE, but NP waveforms can be contaminated by near-zone effects---unless the waves are extracted at several distances from the source and extrapolated to infinity. Even then, the resulting waveforms can in principle be contaminated by gauge effects. In contrast, CCE directly provides, by construction, gauge-invariant waveforms at future null infinity. We verify the gauge invariance of CCE by running the same physical simulation using two different gauge conditions. We find that these two gauge conditions produce the same CCE waveforms but show differences in extrapolated-$\\Psi_4$ waveforms. We examine data from several different binary configurations and measure the domi...
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.
Error Analysis of Lattice Boltzmann BGK Model Based on Extrapolation Technique
Han, Shan-Ling; Lin, Zhong-Qin; Zhu, Ping; Lai, Xin-Min
The lattice Boltzmann method, which can simulate the macroscopic behavior of fluid flow, is a relatively new approach. The error analysis of the lattice Boltzmann BGK model is proposed based on extrapolation technique. According to the Filippova procedure, the error estimation formula is derived. The theory analysis shows that the error of lattice Boltzmann method is proportional to the lattice size and the relaxation parameter. The non-equilibrium part of the distribution function leads to the main error. Finally, the proposed error analysis method is validated by numerical simulation of the lid-driven flows in a square cavity. The numerical results agree well with the theory analysis results.
Patil, S.; Bardossy, A.; Singh, S. K.
2008-12-01
The scarcity of observed discharge limits the applicability of straight forward calibration of a hydrological model. Regionalization, extrapolation of model parameters from gauged catchments to hydrologic-similar ungauged catchments, is widely recognized as a potential approach to tackle the problem of predictions in ungauged catchments. But two major concerns regarding the currently established regionalization techniques have been pointed out. Firstly the problem of equifinality, due to non-uniqueness of the parameter sets that lead to a reasonable performance of a model the sub-sequent regional function fitting the parameters and regional extrapolators cannot be considered appropriate. Secondly, the hydrologic regimes in most of the inhabited regions are going through changes due to anthropogenic as well as natural influences, which bring the reliability of a hydrological model calibrated against past observed discharge under skepticism. The following investigation attempts to address the two concerns. During this study a semi-distributed Nash cascade unit hydrograph model was implemented to derive flood runoff hydrograph, regionalization was carried out for the Nash cascade parameters, number of reservoirs (N) and reservoir constant (K). For the regionalization the regional transfer functions for K and the coefficient (?) of the inter-parameter function were calibrated through a regional optimization procedure by using a regional objective function. To consider the influence of temporal changes, in addition to spatial extrapolators, time or event dependent extrapolators such as landuse, rainfall intensity and duration were also incorporated within the transfer functions. The investigation was carried out using a database of 210 rainfall-runoff events from 41 mesoscale catchments located in south-west Germany. The outcome of the investigations underlines the advantage of regionalizing inter-parameters relationship and the approach of regional optimization to tackle equifinality. Additionally it also sheds light on the sensitivity of the model parameters to the event dependent extrapolators.
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...
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.
Characterization of an extrapolation chamber as a primary standard dosimeter for beta radiation
International Nuclear Information System (INIS)
In beta or electron radiation fields, operational dose equivalent quantities, based on absorbed dose in tissue, are used for radiation protection of the workers. Low penetration and high scattering in matter are characteristics of beta radiation that make its dosimetry more complex. Reliable measurements of absorbed dose in tissue must be traceable to an extrapolation chamber, which is the only primary standard dosimeter available for beta radiation. This ionization chamber uses the extrapolation to zero volume as the method of measurement of absorbed doses in 0.07 mm of tissue, DT(0.07); its requires the determination of correction factors related to influences from the detector itself and from the radiation field geometry. In this work, a 23392 model PTW extrapolation chamber was characterized by determining its collector electrode area, its true-null depth and the influence in its response of temperature, humidity and chamber depth. Values of the true-null depth were 0.46±0.04 mm and 0.40±0.04 mm for 90Sr/90Y and 85Kr beta field sources, respectively. Corrections of the chamber ionization current, according to the ideal gas law significantly reduced the high influence of temperature; air humidity influence showed to be negligible within the 50% to 70% range. The high dependence of the chamber response with its volume addressed the need to determine accurately its true-null depth. These results are to be used as appropriate corrections for accurate absorbed dose in tissue determination. (author)
Extrapolation and optimal decompositions with applications to analysis
Milman, Mario
1994-01-01
This book develops a theory of extrapolation spaces with applications to classical and modern analysis. Extrapolation theory aims to provide a general framework to study limiting estimates in analysis. The book also considers the role that optimal decompositions play in limiting inequalities incl. commutator estimates. Most of the results presented are new or have not appeared in book form before. A special feature of the book are the applications to other areas of analysis. Among them Sobolev imbedding theorems in different contexts including logarithmic Sobolev inequalities are obtained, commutator estimates are connected to the theory of comp. compactness, a connection with maximal regularity for abstract parabolic equations is shown, sharp estimates for maximal operators in classical Fourier analysis are derived.
Low-energy particle physics and chiral extrapolations
Wittig, Hartmut
2012-01-01
In this review I discuss the role of chiral extrapolations for the determination of several phenomenologically relevant quantities, including light quark masses, meson decay constants and the axial charge of the nucleon. In particular, I investigate whether chiral extrapolations are sufficiently controlled in order to rightfully claim the accuracy which is quoted in recent compilations of these quantities. While this is the case for the masses of the light quarks and the ratio fK/fpi of decay constants, small inconsistencies in the chiral and continuum behaviour of individual decay constants fK and fpi, as well as the hadronic radii r0, r1 remain and must be clarified. In the case of the nucleon axial charge, gA, the chiral behaviour is still poorly understood due to the presence of other systematic effects.
TLD extrapolation for skin dose determination in vivo
International Nuclear Information System (INIS)
Prediction of skin reactions requires knowledge of the dose at various depths in the human skin. Using thermoluminescence dosimeters of three different thicknesses, the dose can be extrapolated to the surface and interpolated between the different depths. A TLD holder was designed for these TLD extrapolation measurements on patients during treatment which allowed measurements of entrance and exit skin dose with a day to day variability of ±7% (S.D. of mean reading). In a pilot study on 18 patients undergoing breast irradiation, it was found that the angle of incidence of the radiation beam is the most significant factor influencing skin entrance dose. In most of these measurements the beam exit dose contributed 50% more to the surface dose than the entrance dose
Limitations on wind-tunnel pressure signature extrapolation
Mack, Robert J.; Darden, Christine M.
1992-01-01
Analysis of some recent experimental sonic boom data has revived the hypothesis that there is a closeness limit to the near-field separation distance from which measured wind tunnel pressure signatures can be extrapolated to the ground as though generated by a supersonic-cruise aircraft. Geometric acoustic theory is used to derive an estimate of this distance and the sample data is used to provide a preliminary indication of practical separation distance values.
An efficient extrapolation to the (T)/CBS limit
International Nuclear Information System (INIS)
We extrapolate to the perturbative triples (T)/complete basis set (CBS) limit using double ? basis sets without polarization functions (Wesleyan-1-Triples-2? or “Wes1T-2Z”) and triple ? basis sets with a single level of polarization functions (Wesleyan-1-Triples-3? or “Wes1T-3Z”). These basis sets were optimized for 102 species representing the first two rows of the Periodic Table. The species include the entire set of neutral atoms, positive and negative atomic ions, as well as several homonuclear diatomic molecules, hydrides, rare gas dimers, polar molecules, such as oxides and fluorides, and a few transition states. The extrapolated Wes1T-(2,3)Z triples energies agree with (T)/CBS benchmarks to within ±0.65 mEh, while the rms deviations of comparable model chemistries W1, CBS-APNO, and CBS-QB3 for the same test set are ±0.23 mEh, ±2.37 mEh, and ±5.80 mEh, respectively. The Wes1T-(2,3)Z triples calculation time for the largest hydrocarbon in the G2/97 test set, C6H5Me+, is reduced by a factor of 25 when compared to W1. The cost-effectiveness of the Wes1T-(2,3)Z extrapolation validates the usefulness of the Wes1T-2Z and Wes1T-3Z basis sets which are now available for a more efficient extrapolation of the (T) component of any composite model chemistry
An efficient extrapolation to the (T)/CBS limit
Energy Technology Data Exchange (ETDEWEB)
Ranasinghe, Duminda S. [Hall-Atwater Laboratories of Chemistry, Wesleyan University, Middletown, Connecticut 06459-0180 (United States); Barnes, Ericka C., E-mail: barnese8@southernct.edu [Department of Chemistry, Southern Connecticut State University, 501 Crescent Street, New Haven, Connecticut 06515-1355 (United States)
2014-05-14
We extrapolate to the perturbative triples (T)/complete basis set (CBS) limit using double ? basis sets without polarization functions (Wesleyan-1-Triples-2? or “Wes1T-2Z”) and triple ? basis sets with a single level of polarization functions (Wesleyan-1-Triples-3? or “Wes1T-3Z”). These basis sets were optimized for 102 species representing the first two rows of the Periodic Table. The species include the entire set of neutral atoms, positive and negative atomic ions, as well as several homonuclear diatomic molecules, hydrides, rare gas dimers, polar molecules, such as oxides and fluorides, and a few transition states. The extrapolated Wes1T-(2,3)Z triples energies agree with (T)/CBS benchmarks to within ±0.65 mE{sub h}, while the rms deviations of comparable model chemistries W1, CBS-APNO, and CBS-QB3 for the same test set are ±0.23 mE{sub h}, ±2.37 mE{sub h}, and ±5.80 mE{sub h}, respectively. The Wes1T-(2,3)Z triples calculation time for the largest hydrocarbon in the G2/97 test set, C{sub 6}H{sub 5}Me{sup +}, is reduced by a factor of 25 when compared to W1. The cost-effectiveness of the Wes1T-(2,3)Z extrapolation validates the usefulness of the Wes1T-2Z and Wes1T-3Z basis sets which are now available for a more efficient extrapolation of the (T) component of any composite model chemistry.
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
Improved Richardson's extrapolation spreadsheet calculator for numerical differentiation
Tay, Kim Gaik; Kek, Sie Long; Abdul-Kahar, Rosmila
2014-07-01
In this paper, we have improved the limitations of our previous Richardson's extrapolation spreadsheet calculator for computing differentiations numerically. These limitations are the value of D(0,0) keyed in by users using 3-point central difference formula, and the fact that the previous spreadsheet calculator can only calculate the approximate definite differentiation up to level 4 × 4. If the function to be differentiated is complicated, calculating D(0,0) using 3-point central difference formula can be tedious as parentheses should be put in a proper order when writing the calculation command. Otherwise, the calculation command may lead to a wrong answer. In this improved Richardson's extrapolation spreadsheet calculator, we redesigned the Richardson's extrapolation spreadsheet calculator, where users are only required to give the value of x, the function to be differentiated f(x), and the step size h value without writing the command to obtain D(0,0). Consequently, the calculations will be done automatically to approximate the definite differentiation up to level 10 × 10.
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)
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)
High-level waste package licensing considerations for extrapolating test data
International Nuclear Information System (INIS)
Programs intended to provide supporting information for the high-level radioactive waste (HLW) repository program must consider the licensing requirements and the technical issues involved with extrapolation of short-term test data to periods of up to 10,000 years. The licensing requirements of the Nuclear Regulatory Commission (NRC), and the issues the NRC staff considers important for the development of predictive methods, are described. Because performance predictions of the geologic repository and particular components of the waste package must largely be based upon inference, a reasonable assurance, on the basis of the record before the Commission, is the general standard that will be required. 3 references, 2 figures
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 $\\e/\\rho$, where $\\rho$ is a typical macroscopic lengthscale and $\\e$ is the typical size of the heterogeneities. In the present work, we make a systematic use of regularization and extrapolation to reduce this resonance error at the level of the appr...
Optimisation of efficiency extrapolation functions in radioactivity standardisation
International Nuclear Information System (INIS)
When radioactivity is measured by 4??-? efficiency extrapolation the data is commonly fitted to a linear function, but also to a polynomial function of second or third order if this proves necessary. In order to justify the empirical fitting procedure, we compared the experimental results with some functions which could be expected on theoretical grounds. The most suitable function was a linear function at high 4? counting efficiencies joined on to a second-order function at low 4? counting efficiencies, while a third-order polynomial function without second-order term produced accurate results regardless of the fitting region. (author)
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,...
Carleson measures, trees, extrapolation, and $T(b)$ theorems
Auscher, P; Muscalu, C; Tao, T; Thiele, C; Auscher, Pascal; Hofmann, Steve; Muscalu, Camil; Tao, Terence; Thiele, Christoph
2001-01-01
The theory of Carleson measures, stopping time arguments, and atomic decompositions has been well-established in harmonic analysis. More recent is the theory of phase space analysis from the point of view of wave packets on tiles, tree selection algorithms, and tree size estimates. The purpose of this paper is to demonstrate that the two theories are in fact closely related, by taking existing results and reproving them in a unified setting. In particular we give a dyadic version of extrapolation for Carleson measures, as well as a two-sided local dyadic $T(b)$ theorem which generalizes earlier $T(b)$ theorems of David, Journe, Semmes, and Christ.
Chiral extrapolations on the lattice with strange sea quarks
International Nuclear Information System (INIS)
The (light but not-so-light) strange quark may play a special role in the low-energy dynamics of QCD. Strange sea-quark pairs may induce significant differences in the pattern of chiral symmetry breaking in the chiral limits of two and three massless flavours, in relation with the violation of the Zweig rule in the scalar sector. This effect could affect chiral extrapolations of unquenched lattice simulations with three dynamical flavours, and it could be detected through the quark-mass dependence of hadron observables [S. Descotes-Genon, hep-ph/0410233
Chiral extrapolations on the lattice with strange sea quarks
Descotes-Genon, Sébastien
2005-06-01
The (light but not-so-light) strange quark may play a special role in the low-energy dynamics of QCD. Strange sea-quark pairs may induce significant differences in the pattern of chiral symmetry breaking in the chiral limits of two and three massless flavours, in relation with the violation of the Zweig rule in the scalar sector. This effect could affect chiral extrapolations of unquenched lattice simulations with three dynamical flavours, and it could be detected through the quark-mass dependence of hadron observables [S. Descotes-Genon, hep-ph/0410233].
Properties of a commercial extrapolation chamber in beta radiation fields
International Nuclear Information System (INIS)
A commercial extrapolation chamber (PTW, Germany) was tested in different beta radiation fields and its properties investigated. Its usefulness for beta radiation calibration and dosimetry was demonstrated. The Beta Secondary Standard setup of the IPEN calibration laboratory was utilized. This system, developed by the Physikalisch-Tecknische Bundesanstalt, Brunswick (Germany) and manufactured by Buchler and Co., consists of a source stand, a control unit with timer and four interchangeable beta sources: 90Sr-90Y (1850 and 74 MBq), 204Tl (18,5 MBq) ionization current detection. The variable volume ionization chamber of cylindrical form is provided with different collecting electrodes of tissue equivalent material and Mylar entrance windows of different thickesses
3D-Euler calculations using characteristic flux extrapolation
Eberle, A.
1985-01-01
The characteristic-upwinding flux-extrapolation scheme developed by Eberle (1983 and 1984) for the numerical computation of solutions to the Euler equations is briefly characterized, and sample results are presented graphically. The technique requires no added artificial viscosity and only one grid sweep per iteration for the steady-state computation. The examples shown include the flow past an automobile, an ONERA M6 wing, a Dillner wing, an aircraft, and a Butler wing and demonstrate the promise of the technique in computations for low and high freestream Mach numbers, vortex flows, and unsteady flows.
The role of de-excitation electrons in measurements with graphite extrapolation chambers
International Nuclear Information System (INIS)
A method is described for determining the absorbed dose to graphite for medium energy x-rays (50-300 kV). The experimental arrangement consists of an extrapolation chamber which is part of a cylindrical graphite phantom of 30 cm diameter and 13 cm depth. The method presented is an extension of the so-called two-component model. In this model the absorbed dose to graphite is derived from the absorbed dose to the air of the cavity formed by the measuring volume. Considering separately the contributions of the absorbed dose to air in the cavity from electrons produced in Compton and photoelectric interactions this dose can be converted to the absorbed dose to graphite in the limit of zero plate separation. The extension of the two-component model proposed in this paper consists of taking into account the energy transferred to de-excitation electrons, i.e. Auger electrons, which are produced as a consequence of a photoelectric interaction or a Compton scattering process. For the system considered, these electrons have energies in the range between about 200 eV and 3 keV and hence a range in air at atmospheric pressure of 0.2 mm or less. As the amount of energy transferred to the de-excitation electrons is different per unit mass in air and in graphite, there is a region, about 0.2 mm thick, of disturbed electronic equilibrium at the graphite-to-air interface. By means of the extension proposed, the x-ray tube voltage range over which a graphite extrapolation chamber can bich a graphite extrapolation chamber can be used is lowered from 100 kV in the case of the two-component model down to at least 50 kV. (author)
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.
Classification of future 5 MW turbines by extrapolation of current trends
Energy Technology Data Exchange (ETDEWEB)
Thakoer, R.; Van Kuik, G.A.M.; Van Leeuwen, H.L.
1999-09-01
This report is part of the STABTOOL project. The goals of the STABTOOL project can be summarised as follows: (1) first establish the elastic configuration of the present megawatt scaled wind turbines, and making an inventory of the present design trends and trends for future wind turbine developments w.r.t changes in the elastic configuration; (2) to make an inventory of the different types of instabilities which can occur for the present and next generation wind turbines for both onshore and offshore applications; (3) to make an inventory of analysis and design methods and development or adjustment of calculation methods. The final objective of the STABTOOL project is to create STABility TOOLs: a simple set of calculation models and methods for specific forms of aeroelastic instabilities and vibration problems which are applicable for both present and future large wind turbines. This report concerns the up scaling of the selected elastic configurations described in ST-NW-1-004: 2-blade, (active)pitch controlled, fixed speed (Kvaerner WTS 80M); 3-blade, (active)stall controlled, fixed speed (Nedwind 62 ); 3-blade, pitch controlled variable speed (Lagerwey 50/1000). Based on scaling rules and extrapolation of trend figures, the characteristics of the future 5MW class of wind turbines is estimated. The Nedwind based extrapolation is considered to be an onshore turbine, whereas the others are offshore. 5 refs.
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.
Energy Technology Data Exchange (ETDEWEB)
Verwichte, E.; Foullon, C.; White, R. S. [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Van Doorsselaere, T., E-mail: Erwin.Verwichte@warwick.ac.uk [Centre for Plasma Astrophysics, Department of Mathematics, Katholieke Universiteit Leuven, Celestijnenlaan 200B, B-3001 Leuven (Belgium)
2013-04-10
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 Alfven speed inside these loops. Through the period of oscillation and loop length, information about the Alfven speed inside each loop is deduced seismologically. This is compared with the Alfven 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 Alfven 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.
Assessing ecological effects of radionuclides: data gaps and extrapolation issues
International Nuclear Information System (INIS)
By inspection of the FASSET database on radiation effects on non-human biota, one of the major difficulties in the implementation of ecological risk assessments for radioactive pollutants is found to be the lack of data for chronic low-level exposure. A critical review is provided of a number of extrapolation issues that arise in undertaking an ecological risk assessment: acute versus chronic exposure regime; radiation quality including relative biological effectiveness and radiation weighting factors; biological effects from an individual to a population level, including radiosensitivity and lifestyle variations throughout the life cycle; single radionuclide versus multi-contaminants. The specificities of the environmental situations of interest (mainly chronic low-level exposure regimes) emphasise the importance of reproductive parameters governing the demography of the population within a given ecosystem and, as a consequence, the structure and functioning of that ecosystem. As an operational conclusion to keep in mind for any site-specific risk assessment, the present state-of-the-art on extrapolation issues allows us to grade the magnitude of the uncertainties as follows: one species to another > acute to chronic = external to internal = mixture of stressors> individual to population> ecosystem structure to function
Molecular dynamics/order parameter extrapolation for bionanosystem simulations.
Miao, Yinglong; Ortoleva, Peter J
2009-02-01
A multiscale approach, molecular dynamics/order parameter extrapolation (MD/OPX), to the all-atom simulation of large bionanosystems is presented. The approach starts with the introduction of a set of order parameters (OPs) automatically generated with orthogonal polynomials to characterize the nanoscale features of bionanosystems. The OPs are shown to evolve slowly via Newton's equations, and the all-atom multiscale analysis (AMA) developed earlier (Miao and Ortoleva, J Chem Phys 2006, 125, 44901) demonstrates the existence of their stochastic dynamics, which serve as the justification for our MD/OPX approach. In MD/OPX, a short MD run estimates the rate of change of the OPs, which is then used to extrapolate the state of the system over time that is much longer than the 10(-14) second timescale of fast atomic vibrations and collisions. The approach is implemented in NAMD and demonstrated on cowpea chlorotic mottle virus (CCMV) capsid structural transitions (STs). It greatly accelerates the MD code and its underlying all-atom description of the nanosystems enables the use of a universal interatomic force field, avoiding recalibration with each new application as needed for coarse-grained models. The source code of MD/OPX is distributed free of charge at https://simtk.org/home/mdopx and a web portal will be available via http://sysbio.indiana.edu/virusx. PMID:18636559
The challenge of indication extrapolation for infliximab biosimilars.
Feagan, Brian G; Choquette, Denis; Ghosh, Subrata; Gladman, Dafna D; Ho, Vincent; Meibohm, Bernd; Zou, Guangyong; Xu, Zhenhua; Shankar, Gopi; Sealey, David C; Russell, Anthony S
2014-07-01
A biosimilar is intended to be highly similar to a reference biologic such that any differences in quality attributes (i.e., molecular characteristics) do not affect safety or efficacy. Achieving this benchmark for biologics, especially large glycoproteins such as monoclonal antibodies, is challenging given their complex structure and manufacturing. Regulatory guidance on biosimilars issued by the U.S. Food and Drug Administration, Health Canada and European Medicines Agency indicates that, in addition to a demonstration of a high degree of similarity in quality attributes, a reduced number of nonclinical and clinical comparative studies can be sufficient for approval. Following a tiered approach, clinical studies are required to address concerns about possible clinically significant differences that remain after laboratory and nonclinical evaluations. Consequently, a critical question arises: can clinical studies that satisfy concerns regarding safety and efficacy in one condition support "indication extrapolation" to other conditions? This question will be addressed by reviewing the case of a biosimilar to infliximab that was approved recently in South Korea, Europe, and Canada for multiple indications through extrapolation. The principles discussed should also apply to biosimilars of other monoclonal antibodies that are approved to treat multiple distinct conditions. PMID:24962198
Extrapolation from animals to the human for the retention of radiothallium in the blood
International Nuclear Information System (INIS)
The extrapolation of tissue distribution data from animal to human has implications in the clinical application of new radiopharmaceuticals, in studies of biodistribution and biokinetics, and in estimation of radiation absorbed dose. The extrapolative method described in this study is based on the assumption that the mechanism of tissue distribution of a radionuclide in different mammalian species is similar. This assumption implies that the fractional distribution function, ?/sub h/(t), of a radionuclide in a specific tissue of one species is related to the corresponding fractional distribution function in any other species by linear transformations in the activity and time variables. Hence, the successful application of the extrapolative technique requires determining a reference ?/sub h/(t) based on a conveniently studied species and finding the relationships between the factors of the transformations and one or more measurable species-dependent parameters. To test this approach, data for retention of T1-201 in the blood of several species were used. Detailed biokinetic data in mice, collected in our laboratory, were used to determine the reference ?/sub h/(t) mouse. Data for other species were extracted from the literature and compared with ?/sub h/(t) mouse to determine the transformation factors, using the least squares fitting technique. These factors appear, on the basis of the data available, to be power functions of body weight. Retention of activity in 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
Application of extrapolation chambers in low-energy X-rays as reference systems.
da Silva, Eric A B; Caldas, Linda V E
2012-07-01
Extrapolation chambers are instruments designed to measure doses of low-energy radiations, mainly beta radiation. In this work, a commercial extrapolation chamber and a homemade extrapolation chamber were applied in measurements using standard radiotherapy X-ray beams. Saturation curves and polarity effect as well as short- and medium-term stabilities were obtained, and these results are within the recommendations of the International Electrotechnical Commission (IEC). The response linearity and the extrapolation curves were also obtained, and they presented good behavior. The results show the usefulness of these extrapolation chambers in low-energy X-ray beams. PMID:22520689
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.
Image extrapolation for photo stitching using nonlocal patch-based inpainting
Voronin, V. V.; Marchuk, V. I.; Sherstobitov, A. I.; Semenischev, E. A.; Agaian, S.; Egiazarian, K.
2014-05-01
Image alignment and mosaicing are usually performed on a set of overlapping images, using features in the area of overlap for seamless stitching. In many cases such images have different size and shape. So we need to crop panoramas or to use image extrapolation for them. This paper focuses on novel image inpainting method based on modified exemplar-based technique. The basic idea is to find an example (patch) from an image using local binary patterns, and replacing non-existed (`lost') data with it. We propose to use multiple criteria for a patch similarity search since often in practice existed exemplar-based methods produce unsatisfactory results. The criteria for searching the best matching uses several terms, including Euclidean metric for pixel brightness and Chi-squared histogram matching distance for local binary patterns. A combined use of textural geometric characteristics together with color information allows to get more informative description of the patches. In particular, we show how to apply this strategy for image extrapolation for photo stitching. Several examples considered in this paper show the effectiveness of the proposed approach on several test images.
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)
Sigma terms from an SU(3) chiral extrapolation
Shanahan, P E; Young, R D
2012-01-01
We report a new analysis of lattice simulation results for octet baryon masses in 2+1-flavor QCD, with an emphasis on a precise determination of the strangeness nucleon sigma term. A controlled chiral extrapolation of a recent PACS-CS Collaboration data set yields baryon masses which exhibit remarkable agreement both with experimental values at the physical point and with the results of independent lattice QCD simulations at unphysical meson masses. Using the Feynman-Hellmann relation, we evaluate sigma commutators for all octet baryons. The small statistical uncertainty, and considerably smaller model-dependence, allows a signifcantly more precise determination of the pion-nucleon sigma commutator and the strangeness sigma term than hitherto possible, namely {\\sigma}{\\pi}N=45 \\pm 6 MeV and {\\sigma}s = 21 \\pm 6 MeV at the physical point.
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
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
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...
Mackie, Iain D.; DiLabio, Gino A.
2011-10-01
The first-principles calculation of non-covalent (particularly dispersion) interactions between molecules is a considerable challenge. In this work we studied the binding energies for ten small non-covalently bonded dimers with several combinations of correlation methods (MP2, coupled-cluster single double, coupled-cluster single double (triple) (CCSD(T))), correlation-consistent basis sets (aug-cc-pVXZ, X = D, T, Q), two-point complete basis set energy extrapolations, and counterpoise corrections. For this work, complete basis set results were estimated from averaged counterpoise and non-counterpoise-corrected CCSD(T) binding energies obtained from extrapolations with aug-cc-pVQZ and aug-cc-pVTZ basis sets. It is demonstrated that, in almost all cases, binding energies converge more rapidly to the basis set limit by averaging the counterpoise and non-counterpoise corrected values than by using either counterpoise or non-counterpoise methods alone. Examination of the effect of basis set size and electron correlation shows that the triples contribution to the CCSD(T) binding energies is fairly constant with the basis set size, with a slight underestimation with CCSD(T)/aug-cc-pVDZ compared to the value at the (estimated) complete basis set limit, and that contributions to the binding energies obtained by MP2 generally overestimate the analogous CCSD(T) contributions. Taking these factors together, we conclude that the binding energies for non-covalently bonded systems can be accurately determined using a composite method that combines CCSD(T)/aug-cc-pVDZ with energy corrections obtained using basis set extrapolated MP2 (utilizing aug-cc-pVQZ and aug-cc-pVTZ basis sets), if all of the components are obtained by averaging the counterpoise and non-counterpoise energies. With such an approach, binding energies for the set of ten dimers are predicted with a mean absolute deviation of 0.02 kcal/mol, a maximum absolute deviation of 0.05 kcal/mol, and a mean percent absolute deviation of only 1.7%, relative to the (estimated) complete basis set CCSD(T) results. Use of this composite approach to an additional set of eight dimers gave binding energies to within 1% of previously published high-level data. It is also shown that binding within parallel and parallel-crossed conformations of naphthalene dimer is predicted by the composite approach to be 9% greater than that previously reported in the literature. The ability of some recently developed dispersion-corrected density-functional theory methods to predict the binding energies of the set of ten small dimers was also examined.
Data-driven scale extrapolation : estimating yearly discharge for a large region by small sub-basins
Gong, Lebing
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 typically 1-2 orders of m...
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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)
Combating matrix effects in LC/ESI/MS: the extrapolative dilution approach.
Kruve, Anneli; Leito, Ivo; Herodes, Koit
2009-09-28
Liquid chromatography electrospray mass spectrometry--LC/ESI/MS--a primary tool for analysis of low volatility compounds in difficult matrices--suffers from the matrix effects in the ESI ionization. It is well known that matrix effects can be reduced by sample dilution. However, the efficiency of simple sample dilution is often limited, in particular by the limit of detection of the method, and can strongly vary from sample to sample. In this study matrix effect is investigated as the function of dilution. It is demonstrated that in some cases dilution can eliminate matrix effect, but often it is just reduced. Based on these findings we propose a new quantitation method based on consecutive dilutions of the sample and extrapolation of the analyte content to the infinite dilution, i.e. to matrix-free solution. The method was validated for LC/ESI/MS analysis of five pesticides (methomyl, thiabendazole, aldicarb, imazalil, methiocarb) in five matrices (tomato, cucumber, apple, rye and garlic) at two concentration levels (0.5 and 5.0 mg kg(-1)). Agreement between the analyzed and spiked concentrations was found for all samples. It was demonstrated that in terms of accuracy of the obtained results the proposed extrapolative dilution approach works distinctly better than simple sample dilution. The main use of this approach is envisaged for (a) method development/validation to determine the extent of matrix effects and the ways of overcoming them and (b) as a second step of analysis in the case of samples having analyte contents near the maximum residue limits (MRL). PMID:19733738
Bagust, Adrian; Beale, Sophie
2014-04-01
A recent publication includes a review of survival extrapolation methods used in technology appraisals of treatments for advanced cancers. The author of the article also noted shortcomings and inconsistencies in the analytical methods used in appraisals. He then proposed a survival model selection process algorithm to guide modelers' choice of projective models for use in future appraisals. This article examines the proposed algorithm and highlights various shortcomings that involve questionable assumptions, including researchers' access to patient-level data, the relevance of proportional hazards modeling, and the appropriateness of standard probability functions for characterizing risk, which may mislead practitioners into employing biased structures for projecting limited data in decision models. An alternative paradigm is outlined. This paradigm is based on the primacy of the experimental data and adherence to the scientific method through hypothesis formulation and validation. Drawing on extensive experience of survival modeling and extrapolation in the United Kingdom, practical advice is presented on issues of importance when using data from clinical trials terminated without complete follow-up as a basis for survival extrapolation. PMID:23901052
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
Characterization and application of two extrapolation chambers in standard X radiation beams
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The extrapolation chambers are ionization chambers with variable volume, and they are mainly utilized as beta radiation detectors. In this work two extrapolation chambers were characterized, a commercial PTW extrapolation chamber and another extrapolation chamber developed at the Calibration Laboratory of IPEN, for application as reference systems in mammography, conventional diagnostic radiology and radiotherapy beams. The results obtained from the characterization tests of the chamber response: leakage current, short- and medium terms stability, determination of the saturation currents and the ion collection efficiencies, angular and energy dependence, show that these extrapolation chambers may be utilized for low-energy X radiation beam dosimetry. The transmission factors in tissue and the calibration factors were also determined for all cited radiation qualities. Finally, a procedure was established for calibration of radiation detectors in standard X radiation beams, using the extrapolation chambers. (author)
Extrapolation from , vector-valued inequalities and applications in the Schrödinger settings
Tang, Lin
2014-04-01
In this paper, we generalize the A ? extrapolation theorem ( Cruz-Uribe-Martell-Pérez, Extrapolation from A ? weights and applications, J. Funct. Anal. 213 (2004), 412-439) and the A p extrapolation theorem of Rubio de Francia to Schrödinger settings. In addition, we also establish weighted vector-valued inequalities for Schrödinger-type maximal operators by using weights belonging to which includes A p . As applications, we establish weighted vector-valued inequalities for some Schrödinger-type operators.
Takahashi, Junichi; Ishii, Masahiro; Kouno, Hiroaki; Yahiro, Masanobu
2014-01-01
We evaluate quark number densities at imaginary chemical potential by lattice QCD with clover-improved two-flavor Wilson fermion. The quark number densities are extrapolated to the small real chemical potential region by assuming some function forms. The extrapolated quark number densities are consistent with those calculated at real chemical potential with the Taylor expansion method for the reweighting factors. In order to study the large real chemical potential region, we use the two-phase model consisting of the quantum hadrodynamics model for the hadron phase and the entanglement-PNJL model for the quark phase. The quantum hadrodynamics model is constructed to reproduce nuclear saturation properties, while the entanglement-PNJL model reproduces well lattice QCD data for the order parameters such as the Polyakov loop, the thermodynamic quantities and the screening masses. Then, we calculate the mass-radius relation of neutron stars and explore the hadron-quark phase transition with the two-phase model.
Jiang, Chaowei
2013-01-01
Due to the absence of direct measurement, the magnetic field in the solar corona is usually extrapolated from the photosphere in numerical way. At the moment, the nonlinear force-free field (NLFFF) model dominates the physical models for field extrapolation in the low corona. Recently we have developed a new NLFFF model with MHD relaxation to reconstruct the coronal magnetic field. This method is based on CESE--MHD model with the conservation-element/solution-element (CESE) spacetime scheme. In this paper, we report the application of the CESE--MHD--NLFFF code to \\SDO/HMI data with magnetograms sampled for two active regions (ARs), NOAA AR 11158 and 11283, both of which were very non-potential, producing X-class flares and eruptions. The raw magnetograms are preprocessed to remove the force and then inputted into the extrapolation code. Qualitative comparison of the results with the \\SDO/AIA images shows that our code can reconstruct magnetic field lines resembling the EUV-observed coronal loops. Most importa...
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This document develops methods of measuring experimentally the limits of valid fracture mechanics data that can be obtained from small fracture mechanics specimens. The proposed technique generally shows that present ASTM limits are overly conservative and the new technique would allow almost a three fold increase in the amount of crack extension allowed in the testing of a surveillance specimen. Analytic relationships are then developed to allow use of the new experimentally measured limit to J controlled crack growth for design or failure analysis applications to pressure vessel structures. The new region of J controlled crack growth is shown to correlate best with the omega criterion which defines limits on both the maximum J level and the maximum crack extension allowable for a particular specimen size and material toughness combination. The final section looks at the problem of extrapolation of J-R curve data when needed for a structure fracture analysis. Several forms of extrapolation relationships are compared from the point of view of accurate and conservative extrapolation, particularly from the standpoint of tearing instability analysis of a growing, ductile crack on the material upper shelf. 35 refs., 38 figs., 12 tabs
Zhu, LiQin; Yang, JianWei; Zhang, Yuan; Wang, YongMing; Zhang, JianLei; Zhao, YuanYuan; Dong, WeiLin
2015-03-01
The aim of this study is to develop a physiologically based pharmacokinetic (PBPK) model in intra-abdominal infected rats, and extrapolate it to human to predict moxifloxacin pharmacokinetics profiles in various tissues in intra-abdominal infected human. 12 male rats with intra-abdominal infections, induced by Escherichia coli, received a single dose of 40 mg/kg body weight of moxifloxacin. Blood plasma was collected at 5, 10, 20, 30, 60, 120, 240, 480, 1440 min after drug injection. A PBPK model was developed in rats and extrapolated to human using GastroPlus software. The predictions were assessed by comparing predictions and observations. In the plasma concentration versus time profile of moxifloxcinin rats, Cmax was 11.151 µg/mL at 5 min after the intravenous injection and t1/2 was 2.936 h. Plasma concentration and kinetics in human were predicted and compared with observed datas. Moxifloxacin penetrated and accumulated with high concentrations in redmarrow, lung, skin, heart, liver, kidney, spleen, muscle tissues in human with intra-abdominal infection. The predicted tissue to plasma concentration ratios in abdominal viscera were between 1.1 and 2.2. When rat plasma concentrations were known, extrapolation of a PBPK model was a method to predict drug pharmacokinetics and penetration in human. Moxifloxacin has a good penetration into liver, kidney, spleen, as well as other tissues in intra-abdominal infected human. Close monitoring are necessary when using moxifloxacin due to its high concentration distribution. This pathological model extrapolation may provide reference to the PK/PD study of antibacterial agents. PMID:25729270
A new mini-extrapolation chamber for beta source uniformity measurements
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According to recent international recommendations, beta particle sources should be specified in terms of absorbed dose rates to water at the reference point. However, because of the clinical use of these sources, additional information should be supplied in the calibration reports. This additional information include the source uniformity. A new small volume extrapolation chamber was designed and constructed at the Calibration Laboratory at Instituto de Pesquisas Energeticas e Nucleares, IPEN, Brazil, for the calibration of 90Sr+90Y ophthalmic plaques. This chamber can be used as a primary standard for the calibration of this type of source. Recent additional studies showed the feasibility of the utilization of this chamber to perform source uniformity measurements. Because of the small effective electrode area, it is possible to perform independent measurements by varying the chamber position by small steps. The aim of the present work was to study the uniformity of a 90Sr+90Y plane ophthalmic plaque utilizing the mini extrapolation chamber developed at IPEN. The uniformity measurements were performed by varying the chamber position by steps of 2 mm in the source central axis (x-and y-directions) and by varying the chamber position off-axis by 3 mm steps. The results obtained showed that this small volume chamber can be used for this purpose with a great advantage: it is a direct method, being unnecessary a previously calibration of the measurement device in relation to a reference instrument, and it provides real -time results, reducing the time necessary for the study and the determination of the uncertainties related to the measurements. (authors)
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.
A New Global Heat Flow Map: An Extrapolation Based on a Multi-Observables Similarity Function
Poort, J.; Goutorbe, B.; Lucazeau, F.; Bonneville, A.; Raillard, S.
2009-04-01
Since the international heat flow commission published their world heat flow map in 1993, limited attempts have been undertaken to update it and ameliorate a global heat flow prediction. For oceanic crust, the plate-cooling model has been successfully applied to predict the large-scale measured heat flow variations at oceanic crust ages older than 37 Ma, but at younger ages its validity is disputed and heat flow average varies widely. For continents and continental margins, global averages have been more consistent, but the relation with thermo-tectonic age appears inadequate to predict the heat flow variability in many areas. An alternative approach of Shapiro and Ritzwoller (2004) using a global tomographic model to guide the extrapolation of the surface heat flux, resulted in a smooth global heat flow map that depicted for the first a particular uneven heat flow distribution for Antarctica. We developed a similar method of heat flow extrapolation, incorporating a large set of relevant geological and geophysical features and derivates (tectonic provinces, crustal structure, volcanism, heat production, etc.) which are used to build up heat flow probability distributions for blank heat flow nodes. The method is based on an updated world heat flow database that consists of almost 35000 stations and that covers 20.0% of the earth in a 1Ë? x1Ë? grid. Conform previous estimates based on measured heat flow, we attain a global heat loss of 31 TW and an average heat flow of 61 mW/m2 (nearly equal for oceans and continents). The resulting heat flow map depicts the main global trends at cratons, orogens and margins, but also shows, in for example Antarctica, northern Africa and South America, more heat flow variability than previously assumed. We performed blind tests by setting aside part of the heat flow data, which showed that the method and selected observables correctly account for the large scale trends of heat flow. The scale difference between global features and heat flow measurements explain the remaining biases. The similarity method may be extended to past times offering the perspective of paleo heat flow estimates.
International Nuclear Information System (INIS)
The Interface System for the Extrapolation Chamber (SICE) contains several devices handled by a personal computer (PC), it is able to get the required data to calculate the absorbed dose due to Beta radiation. The main functions of the system are: a) Measures the ionization current or charge stored in the extrapolation chamber. b) Adjusts the distance between the plates of the extrapolation chamber automatically. c) Adjust the bias voltage of the extrapolation chamber automatically. d) Acquires the data of the temperature, atmospheric pressure, relative humidity of the environment and the voltage applied between the plates of the extrapolation chamber. e) Calculates the effective area of the plates of the extrapolation chamber and the real distance between them. f) Stores all the obtained information in hard disk or diskette. A comparison between the desired distance and the distance in the dial of the extrapolation chamber, show us that the resolution of the system is of 20 ?m. The voltage can be changed between -399.9 V and +399.9 V with an error of less the 3 % with a resolution of 0.1 V. These uncertainties are between the accepted limits to be used in the determination of the absolute absorbed dose due to beta radiation. (Author)
Generalized multi-hit dose response model for low-dose extrapolation
International Nuclear Information System (INIS)
Man is exposed to a variety of natural and synthetic substances that are known to be harmful to experimental animals at high dose levels and consequently are under suspicion of being harmful to humans. The large number of animals required to obtain any positive response at low-dose levels makes it prohibitive to directly estimate the risk at the required dose levels. Thus, the most common method for establishing safe dose levels is to estimate a dose-response curve based on laboratory tests on a limited number of animals at exposure levels well beyond the human usage levels. Then, using such a dose-response curve, one attempts to establish a safe dose based on a statistical low-dose extrapolation procedure. This thesis introduces a generalized multi-hit dose-response model. A biological interpretation of the model in terms of the occurrence of k hits to cause the toxic response, and a statistical interpretation in terms of a gamma tolerance distribution are given. Other dose-response models in the literature are reviewed, with the one-hit or linear model being seen as a special case of the proposed model. The method of maximum likelihood for estimating the parameters of the model, their large sample properties, and their use in risk assessment through extrapolation to low-doses is presented. A method of point estimation of the virtual safe dose, along with its lower 100(1 - ?)% confidence limit is treated. The resulting procedures are then applied to twelve sets of tures are then applied to twelve sets of toxic response data from the literature. Based on these applications, it is seen that the peformance of the model for risk assessment is similar to that of the one-hit model under evidence of near linearity of the dose-response curve in the low-dose range. However, under evidence of concavity (convexity) in the low-dose range, the model is more (less) stringent in its risk assessment
Energy confinement scaling and the extrapolation to ITER
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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
Design for low dose extrapolation of carcinogenicity data. Technical report No. 24
Energy Technology Data Exchange (ETDEWEB)
Wong, S C
1979-06-01
Parameters for modelling dose-response relationships in carcinogenesis models were found to be very complicated, especially for distinguishing low dose effects. The author concluded that extrapolation always bears the danger of providing misleading information. (PCS)
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.
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
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 OF THE SOLAR CORONAL MAGNETIC FIELD FROM SDO/HMI MAGNETOGRAM BY A CESE-MHD-NLFFF CODE
Energy Technology Data Exchange (ETDEWEB)
Jiang Chaowei; Feng Xueshang, E-mail: cwjiang@spaceweather.ac.cn, E-mail: fengx@spaceweather.ac.cn [SIGMA Weather Group, State Key Laboratory for Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190 (China)
2013-06-01
Due to the absence of direct measurement, the magnetic field in the solar corona is usually extrapolated from the photosphere in a numerical way. At the moment, the nonlinear force-free field (NLFFF) model dominates the physical models for field extrapolation in the low corona. Recently, we have developed a new NLFFF model with MHD relaxation to reconstruct the coronal magnetic field. This method is based on CESE-MHD model with the conservation-element/solution-element (CESE) spacetime scheme. In this paper, we report the application of the CESE-MHD-NLFFF code to Solar Dynamics Observatory/Helioseismic and Magnetic Imager (SDO/HMI) data with magnetograms sampled for two active regions (ARs), NOAA AR 11158 and 11283, both of which were very non-potential, producing X-class flares and eruptions. The raw magnetograms are preprocessed to remove the force and then inputted into the extrapolation code. Qualitative comparison of the results with the SDO/AIA images shows that our code can reconstruct magnetic field lines resembling the EUV-observed coronal loops. Most important structures of the ARs are reproduced excellently, like the highly sheared field lines that suspend filaments in AR 11158 and twisted flux rope which corresponds to a sigmoid in AR 11283. Quantitative assessment of the results shows that the force-free constraint is fulfilled very well in the strong-field regions but apparently not that well in the weak-field regions because of data noise and numerical errors in the small currents.
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 typically 1-2 orders of magnitude smaller than the large region, is proposed. Those small sub-basins contain sufficient information, not only on climate and land surface, but also on hydrological characteristics for the large basin. In the Baltic Sea drainage basin, best discharge estimation for the gauged area was achieved with sub-basins that cover 5% of the gauged area. There exist multiple sets of sub-basins whose climate and hydrology resemble those of the gauged area equally well. Those multiple sets estimate annual discharge for the gauged area consistently well with 6 % average error. The scale-extrapolation method is completely data-driven; therefore it does not force any modelling error into the prediction. The multiple predictions are expected to bracket the inherent variations and uncertainties of the climate and hydrology of the basin.
International Nuclear Information System (INIS)
An intercomparison exercise sponsored by Eurados-Cendos was conducted among four European laboratories (NRPB, UK; PTB, FRG; CEA, France and Risoe National Laboratory, Denmark) in order to compare results and to standardise procedures for determining beta ray dose rates using extrapolation chambers. All the participants used 147Pm sources supplied by the same manufacturer. These were produced from the same batch and constructed to the same specification and are contained in identical holders. Two different types of extrapolation chambers were used for the characterisation of the beta radiation fields. Measurement procedures and evaluation methods differed in certain details between the laboratories. Sources were exchanged between the participating laboratories to enable measurements on the same source to be carried out with different types of chambers. Methods used for deriving correction factors for the effects of air absorption between the source and chamber are discussed. The procedures adopted for evaluating ionisation current at zero chamber volume and that for obtaining absorbed dose rate at the surface of the phantom are described. (author)
Wiegelmann, T; Kliem, B; Valori, G; Neukirch, T; Wiegelmann, Thomas; Inhester, Bernd; Kliem, Bernhard; Valori, Gherardo; Neukirch, Thomas
2006-01-01
CONTEXT: As the coronal magnetic field can usually not be measured directly, it has to be extrapolated from photospheric measurements into the corona. AIMS: We test the quality of a non-linear force-free coronal magnetic field extrapolation code with the help of a known analytical solution. METHODS: The non-linear force-free equations are numerically solved with the help of an optimization principle. The method minimizes an integral over the force-free and solenoidal condition. As boundary condition we use either the magnetic field components on all six sides of the computational box in Case I or only on the bottom boundary in Case II. We check the quality of the reconstruction by computing how well force-freeness and divergence-freeness are fulfilled and by comparing the numerical solution with the analytical solution. The comparison is done with magnetic field line plots and several quantitative measures, like the vector correlation, Cauchy Schwarz, normalized vector error, mean vector error and magnetic en...
Magnetic Field Extrapolations in the Corona: Success and Future Improvements
Regnier, S.
2013-01-01
The solar atmosphere being magnetic in nature, the understanding of the structure and evolution of the magnetic field in different regions of the solar atmosphere has been an important task over the past decades. This task has been made complicated by the difficulties to measure the magnetic field in the corona, while it is currently known with a good accuracy in the photosphere and/or chromosphere. Thus, to determine the coronal magnetic field, a mathematical method has bee...
International Nuclear Information System (INIS)
A GIS database was established for fertiliser recommendation domains in Kisii District by using FURP fertiliser trial results, KSS soils data and MDBP climatic data. These are manipulated in ESRI's (Personal Computer Environmental Systems Research Institute) ARCINFO and ARCVIEW softwares. The extrapolations were only done for the long rains season (March- August) with three to four years data. GIS technology was used to cluster fertiliser recommendation domains as a geographical area expressed in terms of variation over space and not limited to the site of experiment where a certain agronomic or economic fertiliser recommendation was made. The extrapolation over space was found to be more representative for any recommendation, the result being digital maps describing each area in the geographical space. From the results of the extrapolations, approximately 38,255 ha of the district require zero Nitrogen (N) fertilisation while 94,330 ha requires 75 kg ha-1 Nitrogen fertilisation during the (March-August) long rains. The extrapolation was made difficult since no direct relationships could be established to occur between the available-N, % Carbon (C) or any of the other soil properties with the obtained yields. Decision rules were however developed based on % C which was the soil variable with values closest to the obtained yields. 3% organic carbon was found to be the boundary between 0 application and 75 kg-N application. GIS techniques made it possible to ation. GIS techniques made it possible to model and extrapolates the results using the available data. The extrapolations still need to be verified with more ground data from fertiliser trials. Data gaps in the soil map left some soil mapping units with no recommendations. Elevation was observed to influence yields and it should be included in future extrapolation by clustering digital elevation models with rainfall data in a spatial model at the district scale
Fang, Lei; Yang, Jian
2014-12-01
The Landsat derived differenced Normalized Burn Ratio (dNBR) is widely used for burn severity assessments. Studies of regional wildfire trends in response to climate change require consistency in dNBR mapping across multiple image dates, which may vary in atmospheric condition. Conversion of continuous dNBR images into categorical burn severity maps often requires extrapolation of dNBR thresholds from present fires for which field severity measurements such as Composite Burn Index (CBI) data are available, to historical fires for which CBI data are typically unavailable. Although differential atmospheric effects between image collection dates could lead to biased estimates of historical burn severity patterns, little is known concerning the influence of atmospheric effects on dNBR performance and threshold extrapolation. In this study, we compared the performance of dNBR calculated from six atmospheric correction methods using an optimality approach. The six correction methods included one partial (Top of atmosphere reflectance, TOA), two absolute, and three relative methods. We assessed how the correction methods affected the CBI-dNBR correlation and burn severity mapping in a Chinese boreal forest fire which occurred in 2010. The dNBR thresholds of the 2010 fire for each of the correction methods were then extrapolated to classify a historical fire from 2000. Classification accuracies of threshold extrapolations were assessed based on Cohen's Kappa analysis with 73 field-based validation plots. Our study found most correction methods improved mean dNBR optimality of the two fires. The relative correction methods generated 32% higher optimality than both TOA and absolute correction methods. All the correction methods yielded high CBI-dNBR correlations (mean R2 = 0.847) but distinctly different dNBR thresholds for severity classification of 2010 fire. Absolute correction methods could substantially increase optimality score, but were insufficient to provide a consistent scale of radiometric condition between multi-temporal Landsat images, which resulted in lower severity classification accuracies (Kappa = 0.53) than those relative correction methods (Kappa = 0.72) for the 2000 fire. Consistent radiometric response in remote sensing datasets proved essential for accuracy in regional burn severity trends monitoring. Extrapolation of empirical dNBR thresholds to historical conditions without relative normalization will likely lead to biased burn severity classifications.
Extrapolation uncertainties in the importance-truncated No-Core Shell Model
Kruse, M K G; Navrátil, P; Barrett, B R; Ormand, W E
2013-01-01
We report on Li-6 calculations performed with the IT-NCSM and compare them to full NCSM calculations. We employ the Entem and Machleidt chiral two-body N3LO interaction (regulated at 500 MeV/c), which has been modified to a phase-shift equivalent potential by the similarity renormalization group (SRG) procedure. We investigate the dependence of the procedure on the technique employed to extrapolate to the complete Nmax space, the harmonic oscillator energy, and investigate the dependence on the momentum-decoupling scale (\\lambda) used in the SRG. We also investigate the use of one or several reference states from which the truncated basis is constructed. We find that the uncertainties generated from various extrapolating functions used to extrapolate to the complete Nmax space increase as Nmax increases. The extrapolation uncertainties range from a few keV for the smallest Nmax spaces to about 50 keV for the largest Nmax spaces. We note that the difference between extrapolated IT-NCSM and NCSM ground-state en...
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 expalculated 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)
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)
Characterization of low energy X-rays beams with an extrapolation chamber
International Nuclear Information System (INIS)
In laboratories involving Radiological Protection practices, it is usual to use reference radiations for calibrating dosimeters and to study their response in terms of energy dependence. The International Organization for Standardization (ISO) established four series of reference X-rays beams in the ISO- 4037 standard: the L and H series, as low and high air Kerma rates, respectively, the N series of narrow spectrum and W series of wide spectrum. The X-rays beams with tube potential below 30 kV, called 'low energy beams' are, in most cases, critical as far as the determination of their parameters for characterization purpose, such as half-value layer. Extrapolation chambers are parallel plate ionization chambers that have one mobile electrode that allows variation of the air volume in its interior. These detectors are commonly used to measure the quantity Absorbed Dose, mostly in the medium surface, based on the extrapolation of the linear ionization current as a function of the distance between the electrodes. In this work, a characterization of a model 23392 PTW extrapolation chamber was done in low energy X-rays beams of the ISO- 4037 standard, by determining the polarization voltage range through the saturation curves and the value of the true null electrode spacing. In addition, the metrological reliability of the extrapolation chamber was studied with measurements of the value of leakage current and repeatability tests; limit values were established for the proper use of the chamber. The PTW23392 extrapolation chamber was calibrated in terms of air Kerma in some of the ISO radiation series of low energy; the traceability of the chamber to the National Standard Dosimeter was established. The study of energy dependency of the extrapolation chamber and the assessment of the uncertainties related to the calibration coefficient were also done; it was shown that the energy dependence was reduced to 4% when the extrapolation technique was used. Finally, the first half-value layers were determined for the low energy ISO N series with the extrapolation chamber, in collimated and uncollimated beams and it was showed that this detector is feasible for such measurements. (author)
International Nuclear Information System (INIS)
This report describes the structure and application of an extrapolation ionisation chamber used for measuring dose-rates from plane and point beta-emitting sources. These measurements form the basis of the dosimetry for a collaborative radiobiological study of skin to study both stochastic and non-stochastic effects. A small sample from the wide range of measurements undertaken in the programme has been selected to illustrate the procedures involved. The extrapolation chamber is currently being automated and it is intended that this report should provide a source reference to the basis of the measurements made between 1977-86. (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 ishing 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.
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
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
International Nuclear Information System (INIS)
In a brief survey risks of corrosion of stainless steels are determined by four parameters: pH, Cl content, oxidative power and temperature. Electrochemical corrosion tests, screen tests and loss of weight in immersion tests are examined. An example of corrosion resistance to seawater is given
EXTRAPOLATION IN HUMAN HEALTH AND ECOLOGICAL RISK ASSESSMENTS: PROCEEDINGS OF A SYMPOSIUM
A symposium was conducted in April 1998 by the U.S. Environmental Protection Agency's National Health and Environmental Effects Research Laboratory (NHEERL) to explore issues of extrapolation in human health and ecological risk assessments. Over the course of three and one half d...
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.
Accurate Conformational Energy Differences of Carbohydrates: A Complete Basis Set Extrapolation.
Czech Academy of Sciences Publication Activity Database
Csonka, G. I.; Kaminský, Jakub
2011-01-01
Ro?. 7, ?. 4 (2011), s. 988-997. ISSN 1549-9618 Institutional research plan: CEZ:AV0Z40550506 Keywords : MP2 * basis set extrapolation * saccharides Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.215, year: 2011
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
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.
Kissling, Wilm Daniel; Dalby, Lars; Fløjgaard, Camilla; Lenoir, Jonathan; Sandel, Brody; Sandom, Christopher; Trøjelsgaard, Kristian; Svenning, Jens-Christian
2014-07-01
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. PMID:25165528
Boese, A Daniel; Jansen, Georg; Torheyden, Martin; Höfener, Sebastian; Klopper, Wim
2011-01-21
We study the combined effects of counterpoise correction and basis set extrapolation on the second-order Møller-Plesset (MP2) geometries of three hydrogen bonded dimers, namely (NH(3))(2), (H(2)O)(2) and (HF)(2). For (NH(3))(2), we study three characteristic structures on its potential energy surface. In addition, we look at the basis set convergence when diffuse functions on the hydrogen atoms are left out, as well as the errors introduced by including core correlation with valence-only correlation-consistent basis sets. Overall, the counterpoise-corrected and extrapolated geometries appear to be very reliable and are in convincing agreement with the geometries from explicitly correlated MP2-F12 calculations. Obtaining geometries with errors of less than 0.001 Ångstrom and 0.5 degrees compared to the basis set limit is, however, even with these advanced methods a difficult task. PMID:21103475
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.
Su, S. Y.; Lo, N. J.; Chang, W. I.; Huang, K. Y.
2012-07-01
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.
Mediatransformasie dek die tafel vir ’n nuwe joernalistiek
Directory of Open Access Journals (Sweden)
J. D. Froneman
1997-05-01
Full Text Available Media transformation sets the scene for a new journalismSince 1993 the South African media have been going through a period of fundamental transformation. This process has resulted in a phenomenon of black journalists and whites with credentials as anti-apartheid activists, moving into senior editorial positions at the South African Broadcasting Corporation (SABC as well as at newspapers. This article briefly describes the said transformational steps within the framework of existing media models, inter alia the developmental, social-responsibility and democratic-participatory models. Journalism covering the arts, culture and literature is thereby placed within a broader media context. It is concluded that the dominant media model(s will determine the kind of journalism we can expect in future.
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.
Standard electrode potential, Tafel equation, and the solvation thermodynamics
Matyushov, Dmitry V.
2009-06-01
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.
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)
131I-SPGP internal dosimetry: animal model and human extrapolation
International Nuclear Information System (INIS)
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 125ISPGP biokinetic data were treated by MIRD formalism to perform Internal Dosimetry studies. Absorbed doses due to the 131I-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 131I were considered. (author)
Infrared length scale and extrapolations for the no-core shell model
Wendt, K A; Papenbrock, T; Sääf, D
2015-01-01
We precisely determine the infrared (IR) length scale of the no-core shell model (NCSM). In the NCSM, the $A$-body Hilbert space is truncated by the total energy, and the IR length can be determined by equating the intrinsic kinetic energy of $A$ nucleons in the NCSM space to that of $A$ nucleons in a $3(A-1)$-dimensional hyper-radial well with a Dirichlet boundary condition for the hyper radius. We demonstrate that this procedure indeed yields a very precise IR length by performing large-scale NCSM calculations for $^{6}$Li. We apply our result and perform accurate IR extrapolations for bound states of $^{4}$He, $^{6}$He, $^{6}$Li, $^{7}$Li. We also attempt to extrapolate NCSM results for $^{10}$B and $^{16}$O with bare interactions from chiral effective field theory over tens of MeV.
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.
Electric form factors of the octet baryons from lattice QCD and chiral extrapolation
Shanahan, P. E.; Horsley, R.; Nakamura, Y.; Pleiter, D.; Rakow, P. E. L.; Schierholz, G.; Stüben, H.; Thomas, A. W.; Young, R. D.; Zanotti, J. M.; Cssm; Qcdsf/Ukqcd Collaborations
2014-08-01
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 relative to the uncertainties of the calculation. 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.
Electric form factors of the octet baryons from lattice QCD and chiral extrapolation
Shanahan, P E; Young, R D; Zanotti, J M; Horsley, R; Nakamura, Y; Pleiter, D; Rakow, P E L; Schierholz, G; Stüben, H
2014-01-01
We apply a formalism inspired by heavy baryon chiral perturbation theory with finite-range regularization to dynamical $2+1-$flavor CSSM/QCDSF/UKQCD Collaboration lattice QCD simulation results for the electric form factors of the octet baryons. The electric form factor of each octet baryon is extrapolated to the physical pseudoscalar masses, after finite-volume corrections have been applied, at six fixed values of $Q^2$ in the range 0.2-1.3 GeV$^2$. The extrapolated lattice results accurately reproduce the experimental form factors of the nucleon at the physical point, indicating that omitted disconnected quark loop contributions are small. Furthermore, using the results of a recent lattice study of the magnetic form factors, we determine the ratio $\\mu_p G^p_E/G^p_M$. This quantity decreases with $Q^2$ in a way qualitatively consistent with recent experimental results.
Chiral extrapolation and finite-volume dependence of the hyperon vector couplings
Geng, Li-Sheng; Li, Kai-Wen; Camalich, J. Martin
2014-06-01
The hyperon vector form factors at zero momentum transfer, f1(0), play an important role in a precise determination of the Cabibbo-Kobayashi-Maskawa matrix element Vus. Recent studies based on lattice chromodynamics (LQCD) simulations and covariant baryon chiral perturbation theory yield contradicting results. In this work, we study chiral extrapolation of and finite-volume corrections to the latest nf=2+1 LQCD simulations. Our results show that finite-volume corrections are relatively small and can be safely ignored at the present LQCD setup of m?L =4.6, but chiral extrapolation needs to be performed more carefully. Nevertheless, the discrepancy remains, and further studies are needed to fully understand it.
Chiral extrapolation and finite-volume dependence of the hyperon vector couplings
Geng, Li-Sheng; Camalich, J Martin
2014-01-01
The hyperon vector form factors at zero momentum transfer, $f_1(0)$, play an important role in a precise determination of the Cabibbo-Kobayashi-Maskawa matrix element $V_{us}$. Recent studies based on lattice chromodynamics (LQCD) simulations and covariant baryon chiral perturbation theory yield contradicting results. In this work, we study chiral extrapolation of and finite-volume corrections to the latest $n_f=2+1$ LQCD simulations. Our results show that finite-volume corrections are relatively small and can be safely ignored at the present LQCD setup of $m_\\pi L=4.6$ but chiral extrapolation needs to be performed more carefully. Nevertheless, the discrepancy remains and further studies are needed to fully understand it.
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.
{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)
High Energy Hadron-Nucleus Cross Sections and Their Extrapolation to Cosmic Ray Energies
Ball, James S.; Pantziris, Anthony
1995-01-01
Old models of the scattering of composite systems based on the Glauber model of multiple diffraction are applied to hadron-nucleus scattering. We obtain an excellent fit with only two free parameters to the highest energy hadron-nucleus data available. Because of the quality of the fit and the simplicity of the model it is argued that it should continue to be reliable up to the highest cosmic ray energies. Logarithmic extrapolations of proton-proton and proton-antiproton dat...
Molecular Dynamics/Order Parameter eXtrapolation (MD/OPX) for Bionanosystem Simulations
Miao, Yinglong; Ortoleva, Peter J.
2009-01-01
A multiscale approach, Molecular Dynamics/Order Parameter eXtrapolation (MD/OPX), to the all-atom simulation of large bionanosystems is presented. The approach starts with the introduction of a set of order parameters (OPs) automatically generated with orthogonal polynomials to characterize the nanoscale features of bionanosystems. The OPs are shown to evolve slowly via Newton’s equations and the all-atom multiscale analysis (AMA) developed earlier1 demonstrates the existence of their stoch...
Moura, A.; Yukalov, V. I.
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...
Extrapolation-based Path Invariants for Abstraction Re?nement of Fifo Systems
Heußner, Alexander; Sutre, Gre?goire; 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 abstracti...
Extrapolation-Based Path Invariants for Abstraction Refinement of Fifo Systems
Heußner, Alexander; Sutre, Gre?goire; 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...
Klein, Agnes V.; Jian Wang; Patrick Bedford
2014-01-01
The principles Health Canada use when extrapolating the indications and uses of a biosimilar product subsequent to a single clinical trial or limited number and scope of clinical trials during product development are discussed. The principles underlying the regulatory framework for Subsequent Entry Biologics (SEBs or biosimilars) in Canada explain the position taken by the regulator in respect of the substitutability and/or interchangeability of SEBs.
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 to) 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.
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 cass 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.
Varandas, A J C; Pansini, F N N
2014-12-14
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. PMID:25494738
Miao, Yinglong; Ortoleva, Peter J
2010-01-01
On the basis of an all-atom multiscale analysis theory of nanosystem dynamics, a multiscale molecular dynamics/order parameter extrapolation (MD/OPX) approach has recently been developed. It accelerates MD for long-time simulation of large bionanosystems and addresses rapid atomistic fluctuations and slowly varying coherent dynamics simultaneously. In this study, MD/OPX is optimized and implemented to simulate viral capsid structural transitions. Specifically, 200 ns MD/OPX simulation of the swollen state of cowpea chlorotic mottle virus capsid reveals that it undergoes significant energy-driven shrinkage in vacuum, which is a symmetry-breaking process involving local initiation and front propagation. PMID:19728362
Magnetic 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. (Australia). School of Chemistry and Physics; Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Nakamura, Y. [RIKEN Advanced Institute for Computational Science, Kobe, Hyogo (Japan); Pleiter, D. [Forschungszentrum Juelich GmbH (Germany). Juelich Supercomputing Centre (JSC); Regensburg Univ. (Germany). Institut fuer Theoretische Physik; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Division; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Stueben, H. [Hamburg Univ. (Germany). Regionales Rechenzentrum; Collaboration: CSSM and QCDSF/UKQCD Collaborations
2014-01-15
We present a 2+1-flavor lattice QCD calculation of the electromagnetic Dirac and Pauli form factors of the octet baryons. The magnetic Sachs form factor is extrapolated at six fixed values of Q{sup 2} to physical pseudoscalar masses and infinite volume using a formulation based on heavy baryon chiral perturbation theory with finite-range regularization. We properly account for omitted disconnected quark contractions using a partially-quenched effective field theory formalism. The results compare well with the experimental form factors of the nucleon and the magnetic moments of the octet baryons.
Extrapolation of electron correlation energies to finite and complete basis set targets
Bakowies, Dirk
2007-08-01
The electron correlation energy of two-electron atoms is known to converge asymptotically as ˜(L+1)-3 to the complete basis set limit, where L is the maximum angular momentum quantum number included in the basis set. Numerical evidence has established a similar asymptotic convergence ˜X-3 with the cardinal number X of correlation-consistent basis sets cc-pVXZ for coupled cluster singles and doubles (CCSD) and second order perturbation theory (MP2) calculations of molecules. The main focus of this article is to probe for deviations from asymptotic convergence behavior for practical values of X by defining a trial function X-? that for an effective exponent ? =?eff(X,X+1,X+N) provides the correct energy EX +N, when extrapolating from results for two smaller basis sets, EX and EX +1. This analysis is first applied to "model" expansions available from analytical theory, and then to a large body of finite basis set results (X=D,T,Q,5,6) for 105 molecules containing H, C, N, O, and F, complemented by a smaller set of 14 molecules for which accurate complete basis set limits are available from MP2-R12 and CCSD-R12 calculations. ?eff is generally found to vary monotonically with the target of extrapolation, X +N, making results for large but finite basis sets a useful addition to the limited number of cases where complete basis set limits are available. Significant differences in effective convergence behavior are observed between MP2 and CCSD (valence) correlation energies, between hydrogen-rich and hydrogen-free molecules, and, for He, between partial-wave expansions and correlation-consistent basis sets. Deviations from asymptotic convergence behavior tend to get smaller as X increases, but not always monotonically, and are still quite noticeable even for X =5. Finally, correlation contributions to atomization energies (rather than total energies) exhibit a much larger variation of effective convergence behavior, and extrapolations from small basis sets are found to be particularly erratic for molecules containing several electronegative atoms. Observed effects are discussed in the light of results known from analytical theory. A carefully calibrated protocol for extrapolations to the complete basis set limit is presented, based on a single "optimal" exponent ?opt(X,X+1,?) for the entire set of molecules, and compared to similar approaches reported in the literature.
Impact of new collider data on fits and extrapolations of cross sections and slopes
International Nuclear Information System (INIS)
The latest Collider data are compared with our earlier extrapolations. Fits that include the new data are made. Those for which sigma/sub tot/ grows as log2(s/s/sub o/) indefinitely give a significantly poorer chi2 than those for which sigma/sub tot/ eventually levels out. For the proposed SSC energy for the former fits predict sigma/sub tot/(?s = 40 TeV) approx. =200 mb while the latter give sigma/sub tot/(?s = 40 TeV) approx. = 100 mb. 6 refs
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.
Alessandria, F.; Andreotti, E.; Ardito, R.; Arnaboldi, C.; Avignone, F. T.; Balata, M.; Bandac, I.; Banks, T. I.; Bari, G.; Beeman, J.; 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. A.; Ferri, E.; Ferroni, F.; Fiorini, E.; Foggetta, L.; Freedman, S. J.; 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, Yu. 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. L.; 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. S.; Wang, H. W.; Whitten, C. A.; Wise, T.; Woodcraft, A.; Xu, N.; Zanotti, L.; Zarra, C.; Zhu, B. X.; Zucchelli, S.
2012-07-01
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 performance and the radiopurity of the TeO2 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.
CHARACTERISTICS OF THE H-MODE PEDESTAL AND EXTRAPOLATION TO ITER
International Nuclear Information System (INIS)
A271 CHARACTERISTICS OF THE H-MODE PEDESTAL AND EXTRAPOLATION TO ITER. The peeling-ballooning mode model for edge stability along with a model for the H-mode transport barrier width is used as an approach to estimating the H-mode pedestal conditions in ITER. Scalings of the barrier width based on ion-orbit loss, neutral penetration, and turbulence suppression are examined and empirical scalings of the barrier width are presented. An empirical scaling for the pedestal ? is derived based on ideas from stability and the empirical width scaling. The impact of the stability model and other factors on ELM size is discussed
Two photon decay of the pseudoscalars, the extrapolation to the mass-shell
Nasrallah, N F
2001-01-01
The extrapolation of the decay amplitude of the pseudoscalar mesons into two photons from the soft meson limit where it is obtained from the axial anomaly to the mass-shell involves the contribution of the 0 minus continuum. The corrections to the soft-meson limit is estimated and turns out to be very large for the eta and eta'. The results, however, remain consistent with the values of the singlet-octet mixing angle theta =-19.5 degree and the ratio f8/fpi=1.25 obtained from the chiral perturbation theory.
Extrapolating glacier mass balance to the mountain range scale: the European Alps 1900–2100
Huss, M.
2012-01-01
This study addresses the extrapolation of single glacier mass balance measurements to the mountain range scale and aims at deriving time series of area-averaged mass balance and ice volume change for all glaciers in the European Alps for the period 1900–2100. Long-term mass balance series for 50 Swiss glaciers based on a combination of field data and modelling, and WGMS data for glaciers in Austria, France and Italy are used. A complete glacier inventory is available for the year 2003. Mass...
Magnetic form factors of the octet baryons from lattice QCD and chiral extrapolation
Shanahan, P E; Young, R D; Zanotti, J M; Horsley, R; Nakamura, Y; Pleiter, D; Rakow, P E L; Schierholz, G; Stüben, H
2014-01-01
We present a 2+1--flavor lattice QCD calculation of the electromagnetic Dirac and Pauli form factors of the octet baryons. The magnetic Sachs form factor is extrapolated at six fixed values of $Q^2$ to physical pseudoscalar masses and infinite volume using a formulation based on heavy baryon chiral perturbation theory with finite-range regularization. We properly account for omitted disconnected quark contractions using a partially-quenched effective field theory formalism. The results compare well with the experimental form factors of the nucleon and the magnetic moments of the octet baryons.
Mack, Robert J.; Kuhn, Neil S.
2006-01-01
A study was performed to determine a limiting separation distance for the extrapolation of pressure signatures from cruise altitude to the ground. The study was performed at two wind-tunnel facilities with two research low-boom wind-tunnel models designed to generate ground pressure signatures with "flattop" shapes. Data acquired at the first wind-tunnel facility showed that pressure signatures had not achieved the desired low-boom features for extrapolation purposes at separation distances of 2 to 5 span lengths. However, data acquired at the second wind-tunnel facility at separation distances of 5 to 20 span lengths indicated the "limiting extrapolation distance" had been achieved so pressure signatures could be extrapolated with existing codes to obtain credible predictions of ground overpressures.
International Nuclear Information System (INIS)
Graphical abstract: The pseudo-cubic cobalt oxide microparticles have been successfully synthesized by a solution combustion method using Co(NO3)2·6H2O (oxidizer) and dextrose (sugar; fuel). The as-synthesized Co3O4 microparticles are crystalline and Rietveld refinement of calcined samples exhibited cubic structure with space group of Fm3m (No. 227). The generated Co3O4 microparticles were used to fabricate Zn–Co3O4 composite thin films for corrosion protection. Highlights: ? Synthesis of pseudo-cubic Co3O4 microparticles by solution combustion method. ? As-prepared Co3O4 compounds are calcined and structurally characterized. ? Prepared Co3O4 are utilized for the fabrication of Zn–Co3O4 composite thin films. - Abstract: Microcrystalline cobalt oxide (Co3O4) powder was successfully synthesized by a simple, fast, economical and eco-friendly solution-combustion method. The as-synthesized powder was calcined for an hour at temperatures ranging from 100 to 900 °C. The crystallite size, morphology, and chemical state of synthesized powders were characterized by powder XRD, TG-DTA, XPS, SEM/EDAX, TEM and FT-IR spectral methods. The as-synthesized Co3O4 powder was single-crystalline and Rietveld refinement of calcined samples exhibited cf calcined samples exhibited cubic structure with space group of Fm3m (No. 227). The effect of calcination temperature on crystallite size and morphology was assessed. Scanning electron micrographs show a uniform, randomly oriented pseudo-cubic particle with porous like morphology and EDAX measurement showed its chemical composition. Thermal behavior of as-synthesized compound was examined. The TEM result revealed that, the particles are pseudo-cubic in nature with diameter of 0.2–0.6 ?m and a length of 0.9–1.2 ?m. The crystallite size increased with increase of calcination temperature. The synthesized Co3O4 powder was used to fabricate Zn–Co3O4 composite thin films and its corrosion behavior was analyzed by anodic polarization, tafel extrapolation and electrochemical impedance spectroscopy. The results indicate that the Zn–Co3O4 composite thin films have potential applications to corrosion protection.
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...
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.
Extrapolation of the J-R curve for predicting reactor vessel integrity
International Nuclear Information System (INIS)
the work in this report was conducted in support of the issues studied by the US Nuclear Regulatory Commission (NRC) JD/JM Workers Group during the period 1987--1989. The major issues studies were the J-R curve extrapolation techniques for using small-specimen test results to predict ductile instability in larger structures where the extent of crack extension from the small-specimen test was not sufficient. This included the choice of parameter in characterizing the J-R curve, deformation J, or modified J, JM. These issues are studied both by comparing small- and large-specimen J-R curves and by using J-R curves from smaller specimens to predict the behavior of larger specimens and pressure vessel models. An additional issue was raised during the course of this work by the testing a low-upper-shelf A 302 shelf. The results from these tests were not typical of ductile fracture in many steel and suggested that small-specimen J-R curves may not predict the behavior of large structures in some cases. The causes of this behavior were studies as well as the consequences of using the J-R curve results from small specimens of this kind of material. Finally, a discussion and recommendations are given relating to the use of extrapolated J-R curves
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.
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)
Zhang, Lu-Lu; Gao, Shou-Bao; Meng, Qing-Tian; Song, Yu-Zhi
2015-01-01
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. Project supported by the National Natural Science Foundation of China (Grant Nos. 11304185 and 11074151).
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.
High energy hadron-nucleus cross sections and their extrapolation to cosmic ray energies
Ball, James S.; Pantziris, Anthony
1996-02-01
Old models of the scattering of composite systems based on the Glauber model of multiple diffraction are applied to hadron-nucleus scattering. We obtain an excellent fit iwht only two free parameters to the highest energy hadron-nucleus data available. Because of the quality of the fit and the simplicity of the model it is argued that it should continue to be reliable up to the highest cosmic ray energies. Logarithmic extrapolations of p-p and p¯-p data are used to calculate the proton-air cross sections at very high energy. Finally, it is observed that if the exponential behavior of the p¯-p diffraction peak continues into the few TeV energy range it will violate partial wave unitarity. We propose a simple modification that will guarantee unitarity throughout the cosmic ray energy region.
High energy hadron-nucleus cross sections and their extrapolation to cosmic ray energies
Ball, J S; Ball, James S; Pantziris, Anthony
1996-01-01
Old models of the scattering of composite systems based on the Glauber model of multiple diffraction are applied to hadron-nucleus scattering. We obtain an excellent fit with only two free parameters to the highest energy hadron-nucleus data available. Because of the quality of the fit and the simplicity of the model it is argued that it should continue to be reliable up to the highest cosmic ray energies. Logarithmic extrapolations of proton-proton and proton-antiproton data are used to calculate the proton-air cross sections at very high energy. Finally, it is observed that if the exponential behavior of the proton-antiproto diffraction peak continues into the few TeV energy range it will violate partial wave unitarity. We propose a simple modification that will guarantee unitarity throughout the cosmic ray energy region.
High energy hadron-nucleus cross sections and their extrapolation to cosmic ray energies
International Nuclear Information System (INIS)
Old models of the scattering of composite systems based on the Glauber model of multiple diffraction are applied to hadron-nucleus scattering. We obtain an excellent fit iwht only two free parameters to the highest energy hadron-nucleus data available. Because of the quality of the fit and the simplicity of the model it is argued that it should continue to be reliable up to the highest cosmic ray energies. Logarithmic extrapolations of p-p and bar p-p data are used to calculate the proton-air cross sections at very high energy. Finally, it is observed that if the exponential behavior of the bar p-p diffraction peak continues into the few TeV energy range it will violate partial wave unitarity. We propose a simple modification that will guarantee unitarity throughout the cosmic ray energy region. copyright 1996 The American Physical Society
Determination of Extrapolation Distance with Measured Pressure Signatures from Two Low-Boom Models
Mack, Robert J.; Kuhn, Neil
2004-01-01
A study to determine a limiting distance to span ratio for the extrapolation of near-field pressure signatures is described and discussed. This study was to be done in two wind-tunnel facilities with two wind-tunnel models. At this time, only the first half had been completed, so the scope of this report is limited to the design of the models, and to an analysis of the first set of measured pressure signatures. The results from this analysis showed that the pressure signatures measured at separation distances of 2 to 5 span lengths did not show the desired low-boom shapes. However, there were indications that the pressure signature shapes were becoming 'flat-topped'. This trend toward a 'flat-top' pressure signatures shape was seen to be a gradual one at the distance ratios employed in this first series of wind-tunnel tests.
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.
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.
Hematological responses after inhaling 238PuO2: An extrapolation from beagle dogs to humans
International Nuclear Information System (INIS)
The alpha emitter plutonium-238 (238Pu), which is produced in uranium-fueled, light-water reactors, is used as a thermoelectric power source for space applications. Inhalation of a mixed oxide form of Pu is the most likely mode of exposure of workers and the general public. Occupational exposures to 238PuO2 have occurred in association with the fabrication of radioisotope thermoelectric generators. Organs and tissue at risk for deterministic and stochastic effects of 238Pu-alpha irradiation include the lung, liver, skeleton, and lymphatic tissue. Little has been reported about the effects of inhaled 238PuO2 on peripheral blood cell counts in humans. The purpose of this study was to investigate hematological responses after a single inhalation exposure of Beagle dogs to alpha-emitting 238PuO2 particles and to extrapolate results to humans
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
Continuum extrapolation of finite temperature meson correlation functions in quenched lattice QCD
Francis, Anthony
2010-01-01
We explore the continuum limit $a\\rightarrow 0$ of meson correlation functions at finite temperature. In detail we analyze finite volume and lattice cut-off effects in view of possible consequences for continuum physics. We perform calculations on quenched gauge configurations using the clover improved Wilson fermion action. We present and discuss simulations on isotropic $N_\\sigma^3\\times 16$ lattices with $N_\\sigma=32,48,64,128$ and $128^3 \\times N_\\tau$ lattices with $N_\\tau=16,24,32,48$ corresponding to lattice spacings in the range of $0.01 fm \\lsim a \\lsim\\ 0.031 fm$ at $T\\simeq1.45T_c$. Continuum limit extrapolations of vector meson and pseudo scalar correlators are performed and their large distance expansion in terms of thermal moments is introduced. We discuss consequences of this analysis for the calculation of the electrical conductivity of the QGP at this temperature.
Track Extrapolation and Distribution for the CDF-II Trigger System
Downing, R; Holloway, L; Kasten, M; Kim, H; Kraus, J; Marino, C; Pitts, K; Strologas, J; Taffard, A; Downing, Robert; Eddy, Nathan; Holloway, Lee; Kasten, Mike; Kim, Hyunsoo; Kraus, James; Marino, Christopher; Pitts, Kevin; Strologas, John; Taffard, Anyes
2006-01-01
The CDF-II experiment is a multipurpose detector designed to study a wide range of processes observed in the high energy proton-antiproton collisions produced by the Fermilab Tevatron. With event rates greater than 1MHz, the CDF-II trigger system is crucial for selecting interesting events for subsequent analysis. This document provides an overview of the Track Extrapolation System (XTRP), a component of the CDF-II trigger system. The XTRP is a fully digital system that is utilized in the track-based selection of high momentum lepton and heavy flavor signatures. The design of the XTRP system includes five different custom boards utilizing discrete and FPGA technology residing in a single VME crate. We describe the design, construction, commissioning and operation of this system.
Track extrapolation and distribution for the CDF-II trigger system
International Nuclear Information System (INIS)
The CDF-II experiment is a multipurpose detector designed to study a wide range of processes observed in the high energy proton-antiproton collisions produced by the Fermilab Tevatron. With event rates greater than 1 MHz, the CDF-II trigger system is crucial for selecting interesting events for subsequent analysis. This document provides an overview of the Track Extrapolation System (XTRP), a component of the CDF-II trigger system. The XTRP is a fully digital system that is utilized in the track-based selection of high momentum lepton and heavy flavor signatures. The design of the XTRP system includes five different custom boards utilizing discrete and FPGA technology residing in a single VME crate. We describe the design, construction, commissioning and operation of this system
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.
DEFF Research Database (Denmark)
Thorndahl, SØren Liedtke; Grum, M.
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 runoff forecast in the drainage system is based on a fully distributed MOUSE model which is auto-calibrated on flow measurements in order to produce the best possible forecast for the drainage system at all times. The system shows great potential for the implementation of real time control in drainage systems and forecasting flows and water levels.
Verner, Marc-André; Gaspar, Fraser W; Chevrier, Jonathan; Gunier, Robert B; Sjödin, Andreas; Bradman, Asa; Eskenazi, Brenda
2015-03-17
Study sample size in prospective birth cohorts of prenatal exposure to persistent organic pollutants (POPs) is limited by costs and logistics of follow-up. Increasing sample size at the time of health assessment would be beneficial if predictive tools could reliably back-extrapolate prenatal levels in newly enrolled children. We evaluated the performance of three approaches to back-extrapolate prenatal levels of p,p'-dichlorodiphenyltrichloroethane (DDT), p,p'-dichlorodiphenyldichloroethylene (DDE) and four polybrominated diphenyl ether (PBDE) congeners from maternal and/or child levels 9 years after delivery: a pharmacokinetic model and predictive models using deletion/substitution/addition or Super Learner algorithms. Model performance was assessed using the root mean squared error (RMSE), R(2), and slope and intercept of the back-extrapolated versus measured levels. Super Learner outperformed the other approaches with RMSEs of 0.10 to 0.31, R(2)s of 0.58 to 0.97, slopes of 0.42 to 0.93 and intercepts of 0.08 to 0.60. Typically, models performed better for p,p'-DDT/E than PBDE congeners. The pharmacokinetic model performed well when back-extrapolating prenatal levels from maternal levels for compounds with longer half-lives like p,p'-DDE and BDE-153. Results demonstrate the ability to reliably back-extrapolate prenatal POP levels from levels 9 years after delivery, with Super Learner performing best based on our fit criteria. PMID:25698216
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
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.
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.
Tadesse, Tilaye; Inhester, B; Pevtsov, A
2010-01-01
Routine measurements of the solar magnetic field are mainly carried out in the photosphere. Therefore, one has to infer the field strength in the higher layers of the solar atmosphere from the measured photospheric field based on the assumption that the corona is force-free. Meanwhile, those measured data are inconsistent with the above force-free assumption. Therefore, one has to apply some transformations to these data before nonlinear force-free extrapolation codes can be applied. Extrapolation codes in cartesian geometry for modelling the magnetic field in the corona do not take the curvature of the Sun's surface into account and can only be applied to relatively small areas, e.g., a single active region. Here we apply a method for nonlinear force-free coronal magnetic field modelling and preprocessing of photospheric vector magnetograms in spherical geometry using the optimization procedure.We solve the nonlinear force-free field equations by minimizing a functional in spherical coordinates over a restri...
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
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)
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
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
Omelyan, Igor; Kovalenko, Andriy
2013-12-01
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.
Energy Technology Data Exchange (ETDEWEB)
Omelyan, Igor, E-mail: omelyan@ualberta.ca, E-mail: omelyan@icmp.lviv.ua [National Institute for Nanotechnology, 11421 Saskatchewan Drive, Edmonton, Alberta T6G 2M9 (Canada); Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta T6G 2G8 (Canada); Institute for Condensed Matter Physics, National Academy of Sciences of Ukraine, 1 Svientsitskii Street, Lviv 79011 (Ukraine); Kovalenko, Andriy, E-mail: andriy.kovalenko@nrc-cnrc.gc.ca [National Institute for Nanotechnology, 11421 Saskatchewan Drive, Edmonton, Alberta T6G 2M9 (Canada); Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta T6G 2G8 (Canada)
2013-12-28
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.
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The concentrations and the organ distribution patterns of 228Th, 230Th and 232Th in two 9-y-old dogs of our beagle colony were determined. The dogs were exposed only to background environmental levels of Th isotopes through ingestion (food and water) and inhalation as are humans. The organ distribution patterns of the isotopes in the beagles were compared to the organ distribution patterns in humans to determine if it is appropriate to extrapolate the beagle organ burden data to humans. Among soft tissues, only the lungs, lymph nodes, kidney and liver, and skeleton contained measurable amounts of Th isotopes. The organ distribution pattern of Th isotopes in humans and dog are similar, the majority of Th being in the skeleton of both species. The average skeletal concentrations of 228Th in dogs were 30 to 40 times higher than the average skeletal concentrations of the parent 232Th, whereas the concentration of 228Th in human skeleton was only four to five times higher than 232Th. This suggests that dogs have a higher intake of 228Ra through food than humans. There is a similar trend in the accumulations of 232Th, 230Th and 228Th in the lungs of dog and humans. The percentages of 232Th, 230Th and 228Th in human lungs are 26, 9.7 and 4.8, respectively, compared to 4.2, 2.6 and 0.48, respectively, in dog lungs. The larger percentages of Th isotopes in human lungs may be due simply to the longer life span of humans. If the burdens of Th isotopes in human lungs are normalizof Th isotopes in human lungs are normalized to an exposure time of 9.2 y (mean age of dogs at the time of sacrifice), the percent burden of 232Th, 230Th and 228Th in human lungs are estimated to be 3.6, 1.3 and 0.66, respectively. These results suggest that the beagle may be an appropriate experimental animal for extrapolating the organ distribution pattern of Th in humans
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Silva, Eric Alexandre Brito da
2011-07-01
The extrapolation chambers are ionization chambers with variable volume, and they are mainly utilized as beta radiation detectors. In this work two extrapolation chambers were characterized, a commercial PTW extrapolation chamber and another extrapolation chamber developed at the Calibration Laboratory of IPEN, for application as reference systems in mammography, conventional diagnostic radiology and radiotherapy beams. The results obtained from the characterization tests of the chamber response: leakage current, short- and medium terms stability, determination of the saturation currents and the ion collection efficiencies, angular and energy dependence, show that these extrapolation chambers may be utilized for low-energy X radiation beam dosimetry. The transmission factors in tissue and the calibration factors were also determined for all cited radiation qualities. Finally, a procedure was established for calibration of radiation detectors in standard X radiation beams, using the extrapolation chambers. (author)
How far can you go ? Surprises and pitfalls in three-flavour chiral extrapolations
Descotes-Genon, S
2007-01-01
The increasing accuracy of experimental data in flavour physics requires a corresponding improvement on the theoretical side, in particular concerning the non-perturbative dynamics of QCD. This has prompted the lattice community to aim at an unprecedented accuracy in form factors and matrix elements. However, in the light sector, the meson masses remain too heavy for an interpolation, which makes it necessary to rely on Chiral Perturbation Theory to perform extrapolations in the light quark masses. This makes it all the more necessary to assess precisely the range of validity of this theory. More precisely,the presence of strange sea quark pairs may have a significant impact of the pattern of chiral symmetry breaking : in particular large differences can occur between the chiral limits of two and three massless flavours (i.e., whether $m_s$ is kept at its physical value or sent to zero). We recall some indications of such a scenario in QCD, in relation with the peculiar dynamics of the scalar sector. We expla...
Krishnan, Kannan; Haddad, Sami; Béliveau, Martin; Tardif, Robert
2002-12-01
The available data on binary interactions are yet to be considered within the context of mixture risk assessment because of our inability to predict the effect of a third or a fourth chemical in the mixture on the interacting binary pairs. Physiologically based pharmacokinetic (PBPK) models represent a potentially useful framework for predicting the consequences of interactions in mixtures of increasing complexity. This article highlights the conceptual basis and validity of PBPK models for extrapolating the occurrence and magnitude of interactions from binary to more complex chemical mixtures. The methodology involves the development of PBPK models for all mixture components and interconnecting them at the level of the tissue where the interaction is occurring. Once all component models are interconnected at the binary level, the PBPK framework simulates the kinetics of all mixture components, accounting for the interactions occurring at various levels in more complex mixtures. This aspect was validated by comparing the simulations of a binary interaction-based PBPK model with experimental data on the inhalation kinetics of m-xylene, toluene, ethyl benzene, dichloromethane, and benzene in mixtures of varying composition and complexity. The ability to predict the kinetics of chemicals in complex mixtures by accounting for binary interactions alone within a PBPK model is a significant step toward the development of interaction-based risk assessment for chemical mixtures. PMID:12634130
Evidence for Solar Tether-cutting Magnetic Reconnection from Coronal Field Extrapolations
Liu, Chang; Lee, Jeongwoo; Wiegelmann, Thomas; Moore, Ronald L; Wang, Haimin
2013-01-01
Magnetic reconnection is one of the primary mechanisms for triggering solar eruptive events, but direct observation of its rapid process has been of challenge. In this Letter we present, using a nonlinear force-free field (NLFFF) extrapolation technique, a visualization of field line connectivity changes resulting from tether-cutting reconnection over about 30 minutes during the 2011 February 13 M6.6 flare in NOAA AR 11158. Evidence for the tether-cutting reconnection was first collected through multiwavelength observations and then by the analysis of the field lines traced from positions of four conspicuous flare 1700 A footpoints observed at the event onset. Right before the flare, the four footpoints are located very close to the regions of local maxima of magnetic twist index. Especially, the field lines from the inner two footpoints form two strongly twisted flux bundles (up to ~1.2 turns), which shear past each other and reach out close to the outer two footpoints, respectively. Immediately after the fl...
Extrapolation of experimental data on late effects of low-dose radionuclides in man
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The situation of living of population on radionuclide contamination areas was simulated in the experimental study using white strainless rats of different ages. The significance of age for late stochastic effects of internal radionuclide contamination with low doses of 131I, 137Cs, 144Ce and 106Ru was studied. Some common regularities and differences in late effects formation depending on age were found. Results of the study showed that the number of tumors developed increased in groups of animals exposed at the youngest age. The younger animal at the moment of internal radionuclide contamination, the higher percentage of malignant tumors appeared. It was especially so for tumors of endocrine glands (pituitary, suprarenal,- and thyroid). Differences in late effects formation related to different type of radionuclide distribution within the body were estimated. On the base of extrapolation the conclusion was made that human organism being exposed at early postnatal or pubertal period could be the most radiosensitive (1.5-2.0 or sometimes even 3-5 times higher than adults). Data confirmed the opinion that children are the most critical part of population even in case of low dose radiation exposure. (author)
Marshall, H.; Sturm, M.; Elder, K.; Yueh, S. H.
2013-12-01
Calibration and validation of radar remote sensing of snow requires information about bulk snow properties such as depth, density, and SWE. Microwave remote sensing observations are sensitive to these bulk properties, but also to the vertical profile of microstructure, requiring in-situ stratigraphic observations of density, grain size and grain shape. Depth measurements can be performed rapidly without excavation, however detailed vertical snow profile information requires careful observations by an experienced observer, which can only be performed in relatively few locations. We use high resolution ground-based radar to extrapolate snow stratigraphy and SWE from snowpits, quantifying the spatial variability of major layer boundaries which cause significant radar reflections, in addition to high resolution radar estimates of SWE, and relating these to in-situ snowpits. The sub-footprint variability is used to help interpret coincident airborne radar backscatter and other remote sensing observations collected during the ESA/NASA AlpSAR campaign in Austria and Alaska-Canada Campaign in 2013.
Extrapolation ionization chamber for determining surface dose rate of beta applicators
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The design principle, structure, performance and experimental results of two types of extrapolation ionization chamber are described. Both of them are used for measuring the surface dose rate of beta medical applicators. The collecting electrode and guard ring of one chamber were made of polystyrene with 0.05 mm graphite surface coating, while, the collecting electrode and guard ring of another chamber were constructed by a separate concentric circle with graphite block. For both chambers, the range of 0-10 mm of the gap between the high-voltage electrode and the collecting electrode is adjusted. The groove width or the spacing between the collecting electrode and the surrounding guard ring are less than 0.3 mm. The incidence window was made of aluminizing mylay film. It is very easy to exchange the collecting electrode (different sizes and material) and to adjust the space between electrodes. For the former, after several decades of Gy irradiation, and about one hour later, its leakage current could be recovered to normal background level; while for the latter, in the same irradiation situation the leakage current can be recovered to normal background level immediately. Therefore, the problems dealing with very high dose rate measurement--'memory effect', has been solved
Spatial extrapolation of light use efficiency model parameters to predict gross primary production
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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.
Hartree-Fock mass formulas and extrapolation to new mass data
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The two previously published Hartree-Fock (HF) mass formulas, HFBCS-1 and HFB-1 (HF-Bogoliubov), are shown to be in poor agreement with new Audi-Wapstra mass data. The problem lies first with the prescription adopted for the cutoff of the single-particle spectrum used with the ?-function pairing force, and second with the Wigner term. We find an optimal mass fit if the spectrum is cut off both above EF+15 MeV and below EF-15 MeV, EF being the Fermi energy of the nucleus in question. In addition to the Wigner term of the form VW exp(-?|N-Z|/A) already included in the two earlier HF mass formulas, we find that a second Wigner term linear in |N-Z| leads to a significant improvement in lighter nuclei. These two features are incorporated into our new Hartree-Fock-Bogoliubov model, which leads to much improved extrapolations. The 18 parameters of the model are fitted to the 2135 measured masses for N,Z?8 with an rms error of 0.674 MeV. With this parameter set a complete mass table, labeled HFB-2, has been constructed, going from one drip line to the other, up to Z=120. The new pairing-cutoff prescription favored by the new mass data leads to weaker neutron-shell gaps in neutron-rich nuclei
The risk of extrapolation in neuroanatomy: the case of the mammalian vomeronasal system
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IgnacioSalazar
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.
Extrapolation of stress rupture data on 9 to 12% Cr steels
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In this document the stress rupture strengths at times of up to 300 000h have been evaluated. In relation to the stress rupture strength, data from four steels, namely 9Cr1Mo, 9Cr2MoNbV, 9Cr1MoVNb and 12CrMoV, were examined and in each case four different parameters (Larson-Miller, Orr-Sherby-Dorn (original), Orr-Sherby-Dorn (ORNL) and Manson-Haferd) were employed to extrapolate the data out to 300 000h. At temperatures relevant to steam generators (c. 500OC) there was found to be little difference in predicted long-term strength values using the four approaches. However, the lower 95% confidence limits have been evaluated and it was found that for some of the steels these were different to the often assumed minimum set at 80% of the average. The rupture ductility values have been statistically evaluated at specific temperatures to establish the trend in ductility with increasing rupture time
Natural basaltic glass analogue for the long-term extrapolation of nuclear waste glass aging
International Nuclear Information System (INIS)
Increased confidence is provided to the extrapolation of long-term waste form behavior by comparing the alteration of experimentally aged natural basaltic glass to the condition of the same glass as it has been geologically aged. The similarity between the laboratory and geologic alterations indicates that important aging variables have been identified and incorporated into the laboratory experiments. This provides credibility to the long-term predictions made for waste form borosilicate glasses using similar experimental procedures. In addition, these experiments have demonstrated that the aging processes for natural basaltic glass are relevant to the alteration of nuclear waste glasses, as both appear to react via similar processes. The alteration of a synthetic basaltic glass was measured in MCC-1 tests done at 900C, a SA/V of 0.1 cm-1 and time periods up to 182 days. Tests were also done using (1) MCC-2 procedures at 1900C, a SA/V of 0.1 cm-1 and time periods up to 91 days and (2) hydration tests in saturated water vapor at 2400C, a SA/V of approx. 106 cm-1, and time periods up to 63 days. These results are compared to alteration observed in natural basaltic glasses of great age. 6 references, 6 figures, 1 table
Tsiftsoglou, Asterios S; Trouvin, Jean Hugues; Calvo, Gonzalo; Ruiz, Sol
2014-12-01
The regulatory framework for biosimilars was established across Europe in 2005 based on the concept of biosimilarity. This legislation secures the manufacturing, evaluation, and market authorization (MA) of high-quality safe and efficacious biopharmaceuticals that are highly similar to their reference medicinal product (biosimilars). Demonstration of biosimilarity is documented by full-scale comparability exercises between the biosimilar and the reference product at quality, preclinical, and clinical level. However, the complexity, diversity, and heterogeneity of biosimilars, both in structure and manufacturing, combined with the scientific knowledge accumulated in biotechnological analysis of recombinant therapeutic proteins requires continuous improvement of the regulatory framework based on the evolution and experience gained in this field. This current opinion article presents the concept of biosimilarity, discusses the extrapolation of indications that is acceptable based on a case-by-case basis by CHMP/EMA and uncovers other challenges lying ahead in the development of biosimilars. Biosimilars are still quite 'young' products that require worldwide attention. PMID:25391420
Linear extrapolation of ultrarelativistic nucleon-nucleon scattering to nucleus-nucleus collisions
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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
Kinetics of HMX and CP Decomposition and Their Extrapolation for Lifetime Assessment
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Burnham, A K; Weese, R K; Andrzejewski, W J
2004-11-18
Decomposition kinetics are determined for HMX (nitramine octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) and CP (2-(5-cyanotetrazalato) pentaammine cobalt (III) perchlorate) separately and together. For high levels of thermal stress, the two materials decompose faster as a mixture than individually. This effect is observed both in high-temperature thermal analysis experiments and in long-term thermal aging experiments. An Arrhenius plot of the 10% level of HMX decomposition by itself from a diverse set of experiments is linear from 120 to 260 C, with an apparent activation energy of 165 kJ/mol. Similar but less extensive thermal analysis data for the mixture suggests a slightly lower activation energy for the mixture, and an analogous extrapolation is consistent with the amount of gas observed in the long-term detonator aging experiments, which is about 30 times greater than expected from HMX by itself for 50 months at 100 C. Even with this acceleration, however, it would take {approx}10,000 years to achieve 10% decomposition at {approx}30 C. Correspondingly, negligible decomposition is predicted by this kinetic model for a few decades aging at temperatures slightly above ambient. This prediction is consistent with additional sealed-tube aging experiments at 100-120 C, which are estimated to have an effective thermal dose greater than that from decades of exposure to temperatures slightly above ambient.
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Indirect justification for extrapolating the Goff-Gratch formula for saturation vapor pressure over liquid water to temperatures as low as -600C has been obtained during a recent study of ice nucleation on aerosol particles in a laboratory cloud chamber
The National Center for Environmental Assessment-Washington Division, Office of Research and Development, prepared this document on the Extrapolation of the Benzene Inhalation Unit Risk Estimate to the Oral Route of Exposure. This document will serve as a source for updating the ...
Zhang, Lu-Lu; Zhang, Jing; Meng, Qing-Tian; Song, Yu-Zhi
2015-03-01
The potential energy curves (PECs) of the {{b}1}\\sum g+ state of {{S}2} have been calculated using a multi-reference configuration interaction method with the Davidson correction and a series of Dunning’s correlation-consistent basis sets: aug-c.c.-pVXZ and aug-c.c.-pV(X + d)Z (X = Q, 5 and 6). The calculated PECs are subsequently extrapolated to the complete basis set limit. Such PECs are then used to deduce the analytical potential energy functions (APEFs), which show small root mean square derivations. Based on the APEFs, we have calculated the spectroscopic parameters and compared them with the experimental data available at present. By solving the Schrödinger equation numerically, we also obtain the complete set of vibrational levels, classical turning points and rotation and centrifugal distortion constants when J=0. The present results can serve as a useful reference for future experimental and dynamics studies.
Accelerated aging embrittlement of cast duplex stainless steel: Activation energy for extrapolation
International Nuclear Information System (INIS)
Cast duplex stainless steels, used extensively in LWR systems for primary pressure boundary components such as primary coolant pipes, valves, and pumps, are susceptible to thermal aging embrittlement at reactor operating or higher temperatures. Since a realistic aging embrittlement for end-of-life or life-extension conditions (i.e., 32--50 yr of aging at 280--320 degree C) cannot be produced, it is customary to simulate the metallurgical structure by accelerated aging at ?400 degree C. Over the past several years, extensive data on accelerated aging have been reported from a number of laboratories. The most important information from these studies is the activation energy, namely, the temperature dependence of the aging kinetics between 280 and 400 degree C, which is used to extrapolate the aging characteristics to reactor operating conditions. The activation energies (in the range of 18--50 kcal/mole) are, in general, sensitive to material grade, chemical composition, and fabrication process, and a few empirical correlations, obtained as a function of bulk chemical composition, have been reported. In this paper, a mechanistic understanding of the activation energy is described on the basis of the results of microstructural characterization of various heats of CF-3, -8, and -8M grades that were used in aging studies at different laboratories. The primary mechanism of aging embrittlement at temperatures between 280 and 400 degree C is the spinodal decomposition of the ferrite phase, and M23C6 carbide precipitation on the ferrite/austenite boundaries is the secondary mechanism for high-carbon CF-8 grade. 20 refs., 10 figs., 3 tabs
Measurement of absorbed dose with a bone-equivalent extrapolation chamber
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A hybrid phantom-embedded extrapolation chamber (PEEC) made of Solid Water trade mark sign and bone-equivalent material was used for determining absorbed dose in a bone-equivalent phantom irradiated with clinical radiation beams (cobalt-60 gamma rays; 6 and 18 MV x rays; and 9 and 15 MeV electrons). The dose was determined with the Spencer-Attix cavity theory, using ionization gradient measurements and an indirect determination of the chamber air-mass through measurements of chamber capacitance. The collected charge was corrected for ionic recombination and diffusion in the chamber air volume following the standard two-voltage technique. Due to the hybrid chamber design, correction factors accounting for scatter deficit and electrode composition were determined and applied in the dose equation to obtain absorbed dose in bone for the equivalent homogeneous bone phantom. Correction factors for graphite electrodes were calculated with Monte Carlo techniques and the calculated results were verified through relative air cavity dose measurements for three different polarizing electrode materials: graphite, steel, and brass in conjunction with a graphite collecting electrode. Scatter deficit, due mainly to loss of lateral scatter in the hybrid chamber, reduces the dose to the air cavity in the hybrid PEEC in comparison with full bone PEEC by 0.7% to ?2% depending on beam quality and energy. In megavoltage photon and electron beams, graphite electrodes do not affect the dosraphite electrodes do not affect the dose measurement in the Solid Water trade mark sign PEEC but decrease the cavity dose by up to 5% in the bone-equivalent PEEC even for very thin graphite electrodes (<0.0025 cm). In conjunction with appropriate correction factors determined with Monte Carlo techniques, the uncalibrated hybrid PEEC can be used for measuring absorbed dose in bone material to within 2% for high-energy photon and electron beams
Extrapolation of the relative risk of radiogenic neoplasms across mouse strains and to man
International Nuclear Information System (INIS)
We have examined two interrelated questions: is the susceptibility for radiogenic cancer related to the natural incidence, and are the responses of cancer induction by radiation described better by an absolute or a relative risk model. Also, we have examined whether it is possible to extrapolate relative risk estimates across species, from mice to humans. The answers to these questions were obtained from determinations of risk estimates for nine neoplasms in female and male C3Hf/Bd and C57BL/6 Bd mice and from data obtained from previous experiments with female BALB/c Bd and RFM mice. The mice were exposed to 137Cs gamma rays at 0.4 Gy/min to doses of 0, 0.5, 1.0, or 2.0 Gy. When tumors that were considered the cause of death were examined, both the control and induced mortality rates for the various tumors varied considerably among sexes and strains. The results suggest that in general susceptibility is determined by the control incidence. The relative risk model was significantly superior in five of the tumor types: lung, breast, liver, ovary, and adrenal. Both models appeared to fit myeloid leukemia and Harderian gland tumors, and neither provided good fits for thymic lymphoma and reticulum cell sarcoma. When risk estimates of radiation-induced tumors in humans and mice were compared, it was found that the relative risk estimates for lung, breast, and leukemia were not significantly different between humans and mice. In the case of liver tumors, mice hadice. In the case of liver tumors, mice had a higher risk than humans. These results indicate that the relative risk model is the appropriate approach for risk estimation for a number of tumors. The apparent concordance of relative risk estimates between humans and mice for the small number of cancers examined encourages us to undertake further studies
Deposition of inhaled radionuclides in bronchial airways: Implications for extrapolation modeling
International Nuclear Information System (INIS)
The laboratory rat has frequently been used as a human surrogate to estimate potential health effects following the inhalation of radioactive aerosol particles. Interspecies differences in biological response are commonly related to interspecies differences in particle deposition efficiencies. In addition, the documented site selectivity of bronchial carcinomas suggests that localized particle deposition patterns within bronchial airway bifurcations may have important implications for inhalation risk assessments. Interspecies differences in particle deposition patterns may be related primarily to differences in airway morphometries. Thus the validity of extrapolating rat deposition data to human inhalation conditions depends on their morphometric similarities and differences. It is well known that there are significant structural differences between the human - rather symmetric - and the rat - monopodial - airway systems. In the present approach, we focus on localized deposition patterns and deposition efficiencies in selected asymmetric bronchial airway bifurcations, whose diameters, lengths and branching angles were derived from the stochastic airway models of human and rat lungs (Koblinger and Hofmann, 1985;1988), which are based on the morphometric data of Raabe et al. (1976). The effects of interspecies differences in particle deposition patterns are explored in this study for two asymmetric bifurcation geometries in segmental bronchi and terminal bronchioles of both the human and rat lungs at different particle sizes. In order to examine the effect of flow rate on particle deposition in the human lung, we selected two different minute volumes, i.e., 10 and 60 1 min-1 , which are representative of low and heavy physical activity breathing conditions. In the case of the rat we used a minute volume of 0.234 1 min-1 (Hofmann et al., 1993)
Energy Technology Data Exchange (ETDEWEB)
Silva, Eric A.B. da; Caldas, Linda V.E., E-mail: ebrito@usp.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)
2011-10-26
The extrapolation chamber is a ionization chamber used for detection low energy radiation and can be used as an standard instrument for beta radiation beams. This type of ionization chamber have as main characteristic the variation of sensible volume. This paper performs a study of characterization of a PTW commercial extrapolation chamber, in the energy interval of the qualities of conventional radiodiagnostic
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
DEFF Research Database (Denmark)
Thorndahl, SØren Liedtke; Rasmussen, Michael R.
2013-01-01
Model based short-term forecasting of urban storm water runoff can be applied in realtime control of drainage systems in order to optimize system capacity during rain and minimize combined sewer overflows, improve wastewater treatment or activate alarms if local flooding is impending. A novel online system, which forecasts flows and water levels in real-time with inputs from extrapolated radar rainfall data, has been developed. The fully distributed urban drainage model includes auto-calibration using online in-sewer measurements which is seen to improve forecast skills significantly. The radar rainfall extrapolation (nowcast) limits the lead time of the system to two hours. In this paper, the model set-up is tested on a small urban catchment for a period of 1.5 years. The 50 largest events are presented.
International Nuclear Information System (INIS)
The previously developed energy density mass formula is extrapolated to the superheavy region and to the neutron drip line. Fission barriers, ?-decay and ?-decay energies of isotons with N=184 are computed and half-lives are estimated by using simple corrections to the half-lives obtained by Fiset and Nix. According to the assumption made to extrapolate the pairing parameters, the most stable nucleus at N=184 is found to be either 184X294110 with a half-life of 67 years, or 184X292108 with a half-life of 13 years. The position of the neutron drip line for 8<=Z<=44 is also studied and compared to the predictions of other mass formulae. Important differences are found, particularly for the influence of the shell effects in this region. (orig.)
International Nuclear Information System (INIS)
The formulae are presented permitting to calculate, by the regression analysis, the values of n, D0, Dsub(q1, D37, D50, etc., and D0MF,Dsub(q)MF, D37MF, D50MF, etc., and their errors. The ratios between different doses and DMF were determined. It seemed expedient to use the variance analysis in determining the linearity of exponential parts of the dose-survival curves in the lg S-D coordinates, and the parallelism between them. Eight variants of changes in the main parameters of the dose-survival curves are discussed. New indices are proposed: the extrapolation number modification factor and the extrapolation number logarithm modification factor; the expedience of using thereof is reasoned
Croom, Edward L; Shafer, Timothy J; Evans, Marina V; Mundy, William R; Eklund, Chris R; Johnstone, Andrew F M; Mack, Cina M; Pegram, Rex A
2015-02-15
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 neurotoxicity. Lindane cell and media concentrations in vitro, together with in vitro concentration-response data for lindane effects on neuronal network firing rates, were compared to in vivo data and model simulations as an exercise in extrapolation for chemical-induced neurotoxicity in rodents and humans. Time- and concentration-dependent lindane dosimetry was determined in primary cultures of rat cortical neurons in vitro using "faux" (without electrodes) microelectrode arrays (MEAs). In vivo data were derived from literature values, and physiologically based pharmacokinetic (PBPK) modeling was used to extrapolate from rat to human. The previously determined EC50 for increased firing rates in primary cultures of cortical neurons was 0.6?g/ml. Media and cell lindane concentrations at the EC50 were 0.4?g/ml and 7.1?g/ml, respectively, and cellular lindane accumulation was time- and concentration-dependent. Rat blood and brain lindane levels during seizures were 1.7-1.9?g/ml and 5-11?g/ml, respectively. Brain lindane levels associated with seizures in rats and those predicted for humans (average=7?g/ml) by PBPK modeling were very similar to in vitro concentrations detected in cortical cells at the EC50 dose. PBPK model predictions matched literature data and timing. These findings indicate that in vitro MEA results are predictive of in vivo responses to lindane and demonstrate a successful modeling approach for IVIVE of rat and human neurotoxicity. PMID:25529470
Gong, Qi; Fang, Liang
2012-01-01
Asymptotic distribution of the mean survival time based on the Kaplan-Meier curve with an extrapolated 'tail' is derived. A closed formula of the variance estimate is provided. Asymptotic properties of the estimator were studied in a simulation study, which showed that this estimator was unbiased with proper coverage probability and followed a normal distribution. An example is used to demonstrate the application of this estimator. PMID:22323424
Directory of Open Access Journals (Sweden)
J. J. Vélez
2007-04-01
Full Text Available A Regional Water Resources study was performed at basins within and draining to the Basque Country Region (N of Spain, with a total area of approximately 8500 km^{2}. The objective was to obtain daily and monthly long-term discharges in 567 points, most of them ungauged, with basin areas ranging from 0.25 to 1850 km^{2}. In order to extrapolate the calibrations at gauged points to the ungauged ones, a distributed and conceptually based model called TETIS was used. In TETIS the runoff production is modelled using five linked tanks at each cell with different outflow relationships at each tank, which represents the main hydrological processes as snowmelt, evapotranspiration, surface runoff, interflow and base flow. The routing along the channels' network couples its geomorphologic characteristics with the kinematic wave approach. The parameter estimation methodology tries to distinguish between the effective parameter used in the model at cell scale, and the watershed characteristic estimated from the available information, being the best estimation without losing its physical meaning. The relationship between them can be considered as a correction function or, in its simple form, a correction factor. The correction factor can take into account the model input errors, the temporal and spatial scale effects and the watershed characteristics. Therefore, it is reasonable to assume the correction factor is the same for each parameter to all cells within the watershed. This approach reduces dramatically the number of parameter to be calibrated, because only the common correction factors are calibrated instead of parameter maps (number of parameters times the number of cells. In this way, the calibration can be performed using automatic methodologies. In this work, the Shuffled Complex Evolution – University of Arizona, SCE-UA algorithm was used. The available recent year's data was used to calibrate the model in 20 of the most representative flow gauge stations in 18 basins with a Nash-Sutcliffe index higher than 0.6 (10 higher than 0.8. The calibrated correction factors at each basin were similar but not equal. The validation process (in time and space was performed using the remaining data in all flow gauge stations (62, with 42 basins with a Nash-Sutcliffe index higher than 0.5 (25 higher than 0.7. Deficient calibration and validations were always related with flow gauge stations very close to the karstic springs. These results confirmed that it was feasible and efficient to use the SCE-UA algorithm for the automatic calibration of distributed conceptual models and the calibrated model could be used at ungauged basins. Finally, meteorological information from the past 50 years at a daily scale was used to generate a daily discharges series at 567 selected points.
Directory of Open Access Journals (Sweden)
J. J. Vélez
2009-02-01
Full Text Available A Regional Water Resources study was performed at basins within and draining to the Basque Country Region (N of Spain, with a total area of approximately 8500 km^{2}. The objective was to obtain daily and monthly long-term discharges in 567 points, most of them ungauged, with basin areas ranging from 0.25 to 1850 km^{2}. In order to extrapolate the calibrations at gauged points to the ungauged ones, a distributed and conceptually based model called TETIS was used. In TETIS the runoff production is modelled using five linked tanks at the each cell with different outflow relationships at each tank, which represents the main hydrological processes as snowmelt, evapotranspiration, overland flow, interflow and base flow. The routing along the channels' network couples its geomorphologic characteristics with the kinematic wave approach. The parameter estimation methodology tries to distinguish between the effective parameter used in the model at the cell scale, and the watershed characteristic estimated from the available information, being the best estimation without losing its physical meaning. The relationship between them can be considered as a correction function or, in its simple form, a correction factor. The correction factor can take into account the model input errors, the temporal and spatial scale effects and the watershed characteristics. Therefore, it is reasonable to assume the correction factor is the same for each parameter to all cells within the watershed. This approach reduces drastically the number of parameter to be calibrated, because only the common correction factors are calibrated instead of parameter maps (number of parameters times the number of cells. In this way, the calibration can be performed using automatic methodologies. In this work, the Shuffled Complex Evolution – University of Arizona, SCE-UA algorithm was used. The available recent year's data was used to calibrate the model in 20 of the most representative flow gauge stations in 18 basins with a Nash-Sutcliffe index higher than 0.6 (10 higher than 0.8. The calibrated correction factors at each basin were similar but not equal. The validation process (in time and space was performed using the remaining data in all flow gauge stations (62, with 42 basins with a Nash-Sutcliffe index higher than 0.5 (25 higher than 0.7. Deficient calibration and validations were always related with flow gauge stations very close to the karstic springs. These results confirmed that it was feasible and efficient to use the SCE-UA algorithm for the automatic calibration of distributed conceptual models and the calibrated model could be used at ungauged basins. Finally, meteorological information from the past 50 years at a daily scale was used to generate a daily discharges series at 567 selected points.
Electrocatalytic properties of lanthanum manganite-based oxides obtained by a low temperature method
International Nuclear Information System (INIS)
Pure and Sr doped lanthanum manganites have been synthesized by a non-conventional hydroxide solid solution precursor route at 500 degC. Their electrochemical and electrocatalytic properties in relation to O2 evolution in KOH solutions have been investigated as film electrodes by cyclic voltammetry, AC impedance and Tafel polarization techniques. The oxide powders have been used to obtain catalytic films on the nickel supports by painting with a slurry of the oxide followed by sintering at 400 degC. The electrochemically active area vis-a-vis the electrocatalytic activity of the oxides increases considerably with increasing Sr content from 0.1 to 0.4 mole in the perovskite lattice. Both, the apparent as well as the true, catalytic activities of the oxide are found to be many times higher than those of the samples prepared by conventional ceramic methods. The electrolytic evolution of O2 follows approximately first order kinetics in OH- concentration. The Tafel slopes are in the range 90-140 mV decade-1. (author)
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...
Energy Technology Data Exchange (ETDEWEB)
Meyer, M.; Lerjen, M.; Menth, S. [emkamatik GmbH, Wettingen (Switzerland); Luethi, M. [Swiss Federal Insitute of Technology (ETHZ), Institute for Transport Planning and Systems (IVT), Zuerich (Switzerland); Tuchschmid, M. [SBB AG, BahnUmwelt-Center, 3000 Bern (Switzerland)
2009-11-15
This appendix to a final report for the Swiss Federal Office of Energy (SFOE) presents the results of measurements made on trains and presents and discusses extrapolations made on the basis of these measurements. The evaluation and selection of the trains on which the measurements were to be made is discussed. Mainly passenger trains were selected as only few goods engines have the necessary equipment and equipping them would be costly. Measurements made on a Re 460 locomotive are presented and discussed. The methods used in the energy analysis are described and the results obtained on several itineraries that include partial single-track working are presented and discussed.
Ravichandran, R; Binukumar, J P; Sivakumar, S S; Krishnamurthy, K; Davis, C A
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 used for calibrations. Photon beams 6 MV and 15 MV and electron beams 6 MeV and 15 MeV from Varian Clinac linacs were calibrated. Absorbed Dose estimates to Perspex were converted into dose to solid water for comparison with FC 65 ionisation chamber measurements in water. Measurements made during the period December 2006 to June 2008 are considered for evaluation. Uncorrected ionization readings of EC for all the radiation beams over the entire period were within 2% showing the consistency of measurements. Absorbed doses estimated by EC were in good agreement with in-water calibrations within 2% for photons and electron beams. The present results suggest that extrapolation chambers can be considered as an independent measuring system for absorbed dose in addition to Farmer type ion chambers. In the absence of standard beam quality (Co-60 radiations as reference Quality for Nd,water) the possibility of keeping EC as Primary Standards for absorbed dose calibrations in high energy radiation beams from linacs should be explored. As there are neither Standard Laboratories nor SSDL available in our country, we look forward to keep EC as Local Standard for hospital chamber calibrations. We are also participating in the IAEA mailed TLD intercomparison programme for quality audit of existing status of radiation dosimetry in high energy linac beams. The performance of EC has to be confirmed with cobalt-60 beams by a separate study, as linacs are susceptible for minor variations in dose output on different days. PMID:20126563
Richmond, Orien M W; McEntee, Jay P; Hijmans, Robert J; Brashares, Justin S
2010-01-01
Species distribution models (SDMs) are increasingly used for extrapolation, or predicting suitable regions for species under new geographic or temporal scenarios. However, SDM predictions may be prone to errors if species are not at equilibrium with climatic conditions in the current range and if training samples are not representative. Here the controversial "Pleistocene rewilding" proposal was used as a novel example to address some of the challenges of extrapolating modeled species-climate relationships outside of current ranges. Climatic suitability for three proposed proxy species (Asian elephant, African cheetah and African lion) was extrapolated to the American southwest and Great Plains using Maxent, a machine-learning species distribution model. Similar models were fit for Oryx gazella, a species native to Africa that has naturalized in North America, to test model predictions. To overcome biases introduced by contracted modern ranges and limited occurrence data, random pseudo-presence points generated from modern and historical ranges were used for model training. For all species except the oryx, models of climatic suitability fit to training data from historical ranges produced larger areas of predicted suitability in North America than models fit to training data from modern ranges. Four naturalized oryx populations in the American southwest were correctly predicted with a generous model threshold, but none of these locations were predicted with a more stringent threshold. In general, the northern Great Plains had low climatic suitability for all focal species and scenarios considered, while portions of the southern Great Plains and American southwest had low to intermediate suitability for some species in some scenarios. The results suggest that the use of historical, in addition to modern, range information and randomly sampled pseudo-presence points may improve model accuracy. This has implications for modeling range shifts of organisms in response to climate change. PMID:20877563
Barman, Stephen L; Jean, Gary W; Dinsfriend, William M; Gerber, David E
2014-07-25
The treatment of adults who present with rare pediatric tumors is not characterized well in the literature. We report an instance of a 40-year-old African American woman with a diagnosis of choroid plexus carcinoma admitted to the intensive care unit for severe sepsis seven days after receiving chemotherapy consisting of carboplatin (350?mg/m(2) on Days 1 and 2 plus etoposide 100?mg/m(2) on Days 1-5). Her laboratory results were significant for an absolute neutrophil count of 0/µL and blood cultures positive for Capnocytophagia species. She was supported with broad spectrum antibiotics and myeloid growth factors. She eventually recovered and was discharged in stable condition. The management of adults with malignancies most commonly seen in pediatric populations presents substantial challenges. There are multiple age-specific differences in renal and hepatic function that explain the need for higher dosing in pediatric patients without increasing the risk of toxicity. Furthermore, differences in pharmacokinetic parameters such as absorption, distribution, and clearance are present but are less likely to affect patients. It is expected that the pediatric population will have more bone marrow reserve and, therefore, less susceptible to myelosuppression. The extrapolation of pediatric dosing to an adult presents a problematic situation in treating adults with malignancies that primarily effect pediatric patients. We recommend extrapolating from adult treatment regimens with similar agents rather than extrapolating from pediatric treatment regimens to reduce the risk of toxicity. We also recommend the consideration of adding myeloid growth factors. If the treatment is tolerated without significant toxicity, dose escalation can be considered. PMID:25063761
Directory of Open Access Journals (Sweden)
Ravichandran R
2009-01-01
Full Text Available The objective of the present study is to establish radiation standards for absorbed doses, for clinical high energy linear accelerator beams. In the nonavailability of a cobalt-60 beam for arriving at Nd, water values for thimble chambers, we investigated the efficacy of perspex mounted extrapolation chamber (EC used earlier for low energy x-rays and beta dosimetry. Extrapolation chamber with facility for achieving variable electrode separations 10.5mm to 0.5mm using micrometer screw was used for calibrations. Photon beams 6 MV and 15 MV and electron beams 6 MeV and 15 MeV from Varian Clinac linacs were calibrated. Absorbed Dose estimates to Perspex were converted into dose to solid water for comparison with FC 65 ionisation chamber measurements in water. Measurements made during the period December 2006 to June 2008 are considered for evaluation. Uncorrected ionization readings of EC for all the radiation beams over the entire period were within 2% showing the consistency of measurements. Absorbed doses estimated by EC were in good agreement with in-water calibrations within 2% for photons and electron beams. The present results suggest that extrapolation chambers can be considered as an independent measuring system for absorbed dose in addition to Farmer type ion chambers. In the absence of standard beam quality (Co-60 radiations as reference Quality for Nd,water the possibility of keeping EC as Primary Standards for absorbed dose calibrations in high energy radiation beams from linacs should be explored. As there are neither Standard Laboratories nor SSDL available in our country, we look forward to keep EC as Local Standard for hospital chamber calibrations. We are also participating in the IAEA mailed TLD intercomparison programme for quality audit of existing status of radiation dosimetry in high energy linac beams. The performance of EC has to be confirmed with cobalt-60 beams by a separate study, as linacs are susceptible for minor variations in dose output on different days.
International Nuclear Information System (INIS)
This paper describes the methodology and the results obtained at 1304 A wavelength from an analysis of the AFGL Polar Bear experiment. The basic measurement equipment provided data of a spatial resolution of 20 km over a large portion of the earth. The instrumentation also provided sampled outputs as the footprint scanned along the measurement track. The combination of the fine scanning and large area coverage provided opportunity for a spatial power spectral analysis that in turn provided a means for extrapolation to finer spatial scale
Extrapolation of the FOM 1 MW free-electron maser to a multi-megawatt millimeter microwave source
Caplan, M.; Valentini, M.; Verhoeven, A.; Urbanus, W.; Tulupov, A.
1997-02-01
A Free-Electron Maser is now under test at the FOM Institute (Rijnhuizen, Netherlands) with the goal of producing 1 MW long pulse to CW microwave output in the range 130-250 GHz with wall plug efficiencies of 60%. An extrapolated version of this device is proposed, which by scaling up beam current and voltage, would produce microwave power levels of up to 5 MW CW, thus reducing the cost per kilowatt and increasing the power per module. This would allow for practical applications in such diverse areas such as space power beaming, heating of fusion plasmas and heating of high Mach number wind tunnels.
Amharar, Youness; Curtin, Vincent; Gallagher, Kieran H; Healy, Anne Marie
2014-09-10
Pharmaceutical applications which require knowledge of the solubility of a crystalline compound in an amorphous matrix are abundant in the literature. Several methods that allow the determination of such data have been reported, but so far have only been applicable to amorphous polymers above the glass transition of the resulting composites. The current work presents, for the first time, a reliable method for the determination of the solubility of crystalline pharmaceutical compounds in high and low molecular weight amorphous matrices at the glass transition and at room temperature (i.e. below the glass transition temperature), respectively. The solubilities of mannitol and indomethacin in polyvinyl pyrrolidone (PVP) K15 and PVP K25, respectively were measured at different temperatures. Mixtures of undissolved crystalline solute and saturated amorphous phase were obtained by annealing at a given temperature. The solubility at this temperature was then obtained by measuring the melting enthalpy of the crystalline phase, plotting it as a function of composition and extrapolating to zero enthalpy. This new method yielded results in accordance with the predictions reported in the literature. The method was also adapted for the measurement of the solubility of crystalline low molecular weight excipients in amorphous active pharmaceutical ingredients (APIs). The solubility of mannitol, glutaric acid and adipic acid in both indomethacin and sulfadimidine was experimentally determined and successfully compared with the difference between their respective calculated Hildebrand solubility parameters. As expected from the calculations, the dicarboxylic acids exhibited a high solubility in both amorphous indomethacin and sulfadimidine, whereas mannitol was almost insoluble in the same amorphous phases at room temperature. This work constitutes the first report of the methodology for determining an experimentally measured solubility for a low molecular weight crystalline solute in a low molecular weight amorphous matrix. PMID:24968139
Directory of Open Access Journals (Sweden)
T. Gerken
2011-11-01
Full Text Available This paper introduces a surface model with two soil-layers for use in a high-resolution circulation model that has been modified with an extrapolated surface temperature, to be used for the calculation of turbulent fluxes. A quadratic temperature profile based on the layer mean and base temperature is assumed in each layer and extended to the surface. The model is tested at two sites on the Tibetan Plateau near Nam Co Lake during four days during the 2009 Monsoon season. In comparison to a two-layer model without explicit surface temperature estimate, there is a greatly reduced delay in diurnal flux cycles and the modelled surface temperature is much closer to observations. Comparison with a SVAT model and eddy covariance measurements shows an overall reasonable model performance based on RMSD and cross correlation comparisons between the modified and original model. A potential limitation of the model is the need for careful initialisation of the initial soil temperature profile, that requires field measurements. We show that the modified model is capable of reproducing fluxes of similar magnitudes and dynamics as the more complex methods chosen as reference.
Directory of Open Access Journals (Sweden)
T. Gerken
2012-04-01
Full Text Available This paper introduces a surface model with two soil-layers for use in a high-resolution circulation model that has been modified with an extrapolated surface temperature, to be used for the calculation of turbulent fluxes. A quadratic temperature profile based on the layer mean and base temperature is assumed in each layer and extended to the surface. The model is tested at two sites on the Tibetan Plateau near Nam Co Lake during four days during the 2009 Monsoon season. In comparison to a two-layer model without explicit surface temperature estimate, there is a greatly reduced delay in diurnal flux cycles and the modelled surface temperature is much closer to observations. Comparison with a SVAT model and eddy covariance measurements shows an overall reasonable model performance based on RMSD and cross correlation comparisons between the modified and original model. A potential limitation of the model is the need for careful initialisation of the initial soil temperature profile, that requires field measurements. We show that the modified model is capable of reproducing fluxes of similar magnitudes and dynamics when compared to more complex methods chosen as a reference.
Transport equation solving methods
International Nuclear Information System (INIS)
This work is mainly devoted to Csub(N) and Fsub(N) methods. CN method: starting from a lemma stated by Placzek, an equivalence is established between two problems: the first one is defined in a finite medium bounded by a surface S, the second one is defined in the whole space. In the first problem the angular flux on the surface S is shown to be the solution of an integral equation. This equation is solved by Galerkin's method. The Csub(N) method is applied here to one-velocity problems: in plane geometry, slab albedo and transmission with Rayleigh scattering, calculation of the extrapolation length; in cylindrical geometry, albedo and extrapolation length calculation with linear scattering. Fsub(N) method: the basic integral transport equation of the Csub(N) method is integrated on Case's elementary distributions; another integral transport equation is obtained: this equation is solved by a collocation method. The plane problems solved by the Csub(N) method are also solved by the Fsub(N) method. The Fsub(N) method is extended to any polynomial scattering law. Some simple spherical problems are also studied. Chandrasekhar's method, collision probability method, Case's method are presented for comparison with Csub(N) and Fsub(N) methods. This comparison shows the respective advantages of the two methods: a) fast convergence and possible extension to various geometries for Csub(N) method; b) easy calculations and easy extension to polynomial scattering for Fsub(N) method
Chao, Anne; Gotelli, Nicholas; Hsieh, T. C.; Sander, Elizabeth; Ma, K. H.; Colwell, Robert K.; Ellison, Aaron M.
2013-01-01
Quantifying and assessing changes in biological diversity are central aspects of many ecological studies, yet accurate methods of estimating biological diversity from sampling data have been elusive. Hill numbers, or the effective number of species, are increasingly used to characterize the taxonomic, phylogenetic or functional diversity of an assemblage. However, empirical estimates of Hill numbers, including species richness, tend to be an increasing function of sampling effort and thus ten...
Taylor, Nicholas W.; Boyle, Michael; Reisswig, Christian; Scheel, Mark A.; Chu, Tony; Kidder, Lawrence E.; Szilagyi, Bela
2013-01-01
We extract gravitational waveforms from numerical simulations of black hole binaries computed using the Spectral Einstein Code. We compare two extraction methods: direct construction of the Newman-Penrose (NP) scalar $\\Psi_4$ at a finite distance from the source and Cauchy-characteristic extraction (CCE). The direct NP approach is simpler than CCE, but NP waveforms can be contaminated by near-zone effects---unless the waves are extracted at several distances from the source ...
Inflammatory findings on species extrapolations: humans are definitely no 70-kg mice
Leist, Marcel; Hartung, Thomas
2013-01-01
Modern toxicology has embraced in vitro methods, and major hopes are based on the Omics technologies and systems biology approaches they bring along (Hartung and McBride in ALTEX 28(2):83–93, 2011; Hartung et al. in ALTEX 29(2):119–28, 2012). A culture of stringent validation has been developed for such approaches (Leist et al. in ALTEX 27(4):309–317, 2010; ALTEX 29(4):373–88, 2012a; Toxicol Res 1:8–22, 2012b), while the quality and usefulness of animal experiments have been little ...
Inflammatory findings on species extrapolations : humans are definitely no 70-kg mice
Leist, Marcel; Hartung, Thomas
2013-01-01
Modern toxicology has embraced in vitro methods, and major hopes are based on the Omics technologies and systems biology approaches they bring along (Hartung and McBride in ALTEX 28(2):83–93, 2011; Hartung et al. in ALTEX 29(2):119–28, 2012). A culture of stringent validation has been developed for such approaches (Leist et al. in ALTEX 27(4):309–317, 2010; ALTEX 29(4):373–88, 2012a; Toxicol Res 1:8–22, 2012b), while the quality and usefulness of animal experiments have been little ...
International Nuclear Information System (INIS)
We formulate a pair of coupled integral equations for the neutron flux in an infinite cylinder of arbitrary cross-sectional shape. Linearly anisotropic scattering in the medium is assumed. These equations are reduced to a tractable form for a circular cross-section whose properties depend only on the radius vector. Considering the case of isotropic scattering, we compare the accuracy of two variational functionals for calculating the extrapolation distance of a black cylinder. These are the Marshak functional and the Kushneriuk and McKay functional. We find, in contrast to the results obtained by Sahni and Marshak for black spheres, that Marshak's functional is the least accurate and we therefore conclude that the efficiency of a particular functional will depend to some extent on the geometry of the problem. (orig.)
Full-disk nonlinear force-free field extrapolation of SDO/HMI and SOLIS/VSM magnetograms
Tadesse, Tilaye; Inhester, B; MacNeice, P; Pevtsov, A; Sun, X
2012-01-01
Extrapolation codes in Cartesian geometry for modelling the magnetic field in the corona do not take the curvature of the Sun's surface into account and can only be applied to relatively small areas, e.g., a single active region. We compare the analysis of the photospheric magnetic field and subsequent force-free modeling based on full-disk vector maps from Helioseismic and Magnetic Imager (HMI) on board solar dynamics observatory (SDO) and Vector Spectromagnetograph (VSM) of the Synoptic Optical Long-term Investigations of the Sun (SOLIS). We use Helioseismic and Magnetic Imager and Vector Spectromagnetograph photospheric magnetic field measurements to model the force-free coronal field above multiple solar active regions, assuming magnetic forces to dominate. We solve the nonlinear force-free field equations by minimizing a functional in spherical coordinates over a full disk excluding the poles. After searching for the optimum modeling parameters for the particular data sets, we compare the resulting nonli...
Energy Technology Data Exchange (ETDEWEB)
Scott, B.R.; Muggenburg, B.A.; Welsh, C.A.; Angerstein, D.A.
1994-11-01
The alpha emitter plutonium-238 ({sup 238}Pu), which is produced in uranium-fueled, light-water reactors, is used as a thermoelectric power source for space applications. Inhalation of a mixed oxide form of Pu is the most likely mode of exposure of workers and the general public. Occupational exposures to {sup 238}PuO{sub 2} have occurred in association with the fabrication of radioisotope thermoelectric generators. Organs and tissue at risk for deterministic and stochastic effects of {sup 238}Pu-alpha irradiation include the lung, liver, skeleton, and lymphatic tissue. Little has been reported about the effects of inhaled {sup 238}PuO{sub 2} on peripheral blood cell counts in humans. The purpose of this study was to investigate hematological responses after a single inhalation exposure of Beagle dogs to alpha-emitting {sup 238}PuO{sub 2} particles and to extrapolate results to humans.
Extrapolation of Urn Models via Poissonization: Accurate Measurements of the Microbial Unknown
Lladser, Manuel; Reeder, Jens; 10.1371/journal.pone.0021105
2011-01-01
The availability of high-throughput parallel methods for sequencing microbial communities is increasing our knowledge of the microbial world at an unprecedented rate. Though most attention has focused on determining lower-bounds on the alpha-diversity i.e. the total number of different species present in the environment, tight bounds on this quantity may be highly uncertain because a small fraction of the environment could be composed of a vast number of different species. To better assess what remains unknown, we propose instead to predict the fraction of the environment that belongs to unsampled classes. Modeling samples as draws with replacement of colored balls from an urn with an unknown composition, and under the sole assumption that there are still undiscovered species, we show that conditionally unbiased predictors and exact prediction intervals (of constant length in logarithmic scale) are possible for the fraction of the environment that belongs to unsampled classes. Our predictions are based on a P...
Wang, Gaili; Wong, Wai-Kin; Hong, Yang; Liu, Liping; Dong, Jili; Xue, Ming
2015-03-01
The primary objective of this study is to improve the performance of deterministic high resolution rainfall forecasts caused by severe storms by merging an extrapolation radar-based scheme with a storm-scale Numerical Weather Prediction (NWP) model. Effectiveness of Multi-scale Tracking and Forecasting Radar Echoes (MTaRE) model was compared with that of a storm-scale NWP model named Advanced Regional Prediction System (ARPS) for forecasting a violent tornado event that developed over parts of western and much of central Oklahoma on May 24, 2011. Then the bias corrections were performed to improve the forecast accuracy of ARPS forecasts. Finally, the corrected ARPS forecast and radar-based extrapolation were optimally merged by using a hyperbolic tangent weight scheme. The comparison of forecast skill between MTaRE and ARPS in high spatial resolution of 0.01° × 0.01° and high temporal resolution of 5 min showed that MTaRE outperformed ARPS in terms of index of agreement and mean absolute error (MAE). MTaRE had a better Critical Success Index (CSI) for less than 20-min lead times and was comparable to ARPS for 20- to 50-min lead times, while ARPS had a better CSI for more than 50-min lead times. Bias correction significantly improved ARPS forecasts in terms of MAE and index of agreement, although the CSI of corrected ARPS forecasts was similar to that of the uncorrected ARPS forecasts. Moreover, optimally merging results using hyperbolic tangent weight scheme further improved the forecast accuracy and became more stable.
Cai, H.; Kessinger, C.; Rehak, N.; Pinto, J. O.; Megenhardt, D.; Albo, D.; Phillips, C.; Bankert, R.; Hawkins, J.
2012-12-01
Deep convection over the ocean poses a potentially great danger for trans-oceanic flights, as tragically demonstrated by the Air France Flight 447 accident of 2009. This paper describes a forecasting system that will produce 0-12 hr convective forecasts over the Gulf of Mexico domain using a blending technique that combines satellite-based extrapolation forecasts with Numerical Weather Prediction (NWP) model forecasts. Closely following the steps of the Federal Aviation Administration (FAA) Aviation Weather Research Program (AWRP) CoSPA development, a forecasting system is being developed to blend satellite-derived rain rate and cloud top height with their corresponding fields derived from the Global Forecasting System (GFS) NWP model. Forecasts will be computed over the 0-12 hr time frame within a domain that encompasses the greater Gulf of Mexico and parts of the continental United States. Tests of various extrapolation techniques have been completed and an optimum technique has been selected. Both the extrapolated and the GFS rain rate forecast performance statistics have been compiled. Considering the relative strength of the NWP model and the satellite-based extrapolation forecasts, a dynamical-weighting technique, similar to what is being used in CoSPA, has been tested. The weights are determined by past performance of extrapolation and model forecasts as a function of forecast lead time. A prototype blended forecasting system for oceanic convection using dynamical-weighting techniques has been developed and preliminary results of the blended forecasting system will be reported at the conference.
Burkhard, Lawrence P; Cook, Philip M; Lukasewycz, Marta T
2006-07-01
An approach is presented for extrapolating field-measured biota-sediment accumulation factors (BSAFs) and bioaccumulation factors (BAFs) across species, time, and/or ecosystems. This approach, called the hybrid bioaccumulation modeling approach, uses mechanistic bioaccumulation models to extrapolate field-measured bioaccumulation data (i.e., BSAFs and BAFs) to new sets of ecological conditions. The hybrid approach predicts relative differences in bioaccumulation using food web models with two sets of ecological conditions and parameters: One set for the ecosystem where the BSAFs and/or BAFs were measured, and the other set for the ecological conditions and parameters for which the extrapolated BSAFs and/or BAFs are desired. The field-measured BSAF (or BAF) is extrapolated by adjusting the measured BSAF (or BAF) by the predicted relative difference, which is derived from two separate solutions of the food web model. Extrapolations of polychlorinated biphenyl BSAFs and BAFs for lake trout (Salvelinus namaycush) from southern Lake Michigan to Green Bay of Lake Michigan (Green Bay, WI, USA) walleye (Stizostedion vitreum) and brown trout (Salmo trutta), as well as Hudson River largemouth bass (Micropterus salmoides) and yellow perch (Perca flavescens), resulted in generally better agreement between measured and predicted BSAFs and BAFs with the hybrid approach. PMID:16833159
DEFF Research Database (Denmark)
Hui, Cang; McGeoch, Melodie A.
2009-01-01
The estimation of species abundances at regional scales requires a cost-efficient method that can be applied to existing broadscale data. We compared the performance of eight models for estimating species abundance and community structure from presence-absence maps of the southern African avifauna. Six models were based on the intraspecific occupancy-abundance relationship (OAR); the other two on the scaling pattern of species occupancy (SPO), which quantifies the decline in species range size when measured across progressively finer scales. The performance of these models was examined using five tests: the first three compared the predicted community structure against well-documented macroecological patterns; the final two compared published abundance estimates for rare species and the total regional abundance estimate against predicted abundances. Approximately two billion birds were estimated as occurring in South Africa, Lesotho, and Swaziland. SPO models outperformed the OAR models, due to OAR models assuming environmental homogeneity and yielding scale-dependent estimates. Therefore, OAR models should only be applied across small, homogenous areas. By contrast, SPO models are suitable for data at larger spatial scales because they are based on the scale dependence of species range size and incorporate environmental heterogeneity (assuming fractal habitat structure or performing a Bayesian estimate of occupancy). Therefore, SPO models are recommended for assemblage-scale regional abundance estimation based on spatially explicit presence-absence data.
Explanation, Extrapolation, and Existence
Yablo, Stephen
2012-01-01
Mark Colyvan (2010) raises two problems for ‘easy road’ nominalism about mathematical objects. The first is that a theory’s mathematical commitments may run too deep to permit the extraction of nominalistic content. Taking the math out is, or could be, like taking the hobbits out of Lord of the Rings. I agree with the ‘could be’, but not (or not yet) the ‘is’. A notion of logical subtraction is developed that supports the possibility, questioned by Colyvan, of bracketing a theor...
International Nuclear Information System (INIS)
Large edge localized modes (ELMs) typically accompany good H-mode confinement in fusion devices, but can present problems for plasma facing components because of high transient heat loads. Here the range of techniques for ELM control deployed in fusion devices is reviewed. Two strategies in the ITER baseline design are emphasized: rapid ELM triggering and peak heat flux control via pellet injection, and the use of magnetic perturbations to suppress or mitigate ELMs. While both of these techniques are moderately well developed, with reasonable physical bases for projecting to ITER, differing observations between multiple devices are also discussed to highlight the needed community R and D. In addition, recent progress in ELM-free regimes, namely quiescent H-mode, I-mode, and enhanced pedestal H-mode is reviewed, and open questions for extrapolability are discussed. Finally progress and outstanding issues in alternate ELM control techniques are reviewed: supersonic molecular beam injection, edge electron cyclotron heating, lower hybrid heating and/or current drive, controlled periodic jogs of the vertical centroid position, ELM pace-making via periodic magnetic perturbations, ELM elimination with lithium wall conditioning, and naturally occurring small ELM regimes. (paper)
Schreiber, René; Gündel, Ulrike; Franz, Stephanie; Küster, Anette; Rechenberg, Bettina; Altenburger, Rolf
2011-12-01
Thousands of drugs are currently in use, but only for a few of them experimental chronic fish data exist. Therefore, Huggett et al. (Human Ecol Risk Assess 2003; 9:1789-1799) proposed the fish plasma model (FPM) to extrapolate the potential of unintended long-term effects in fish. The FPM compares human therapeutic plasma concentrations (HPC(T)) with estimated fish steady-state concentrations (FPC(ss)), under the assumption that biological drug targets may be conserved across the species. In this study, the influence of using different input parameters on the model result was characterised for 42 drugs. The existence of structurally and functionally conserved protein targets in zebrafish could not be refuted. Thus, the FPM model application was not in contradiction to its basic assumption. Further, dissociation of drugs was shown to be important in determining the output and model robustness. As the proposed model for FPC(ss) estimation was considered to predict accurate values for neutral and lipophilic chemicals only, a modified bioconcentration model was used with D(OW) as predictor. Using reasonable worst case assumptions, a hazard was indicated for one third of the selected drugs. Our results support the notion that this approach might help to prioritise among in use drugs to identify compounds where follow up evidence should be considered. PMID:21889559
Energy Technology Data Exchange (ETDEWEB)
Maingi, R [PPPL
2014-07-01
Large edge localized modes (ELMs) typically accompany good H-mode confinement in fusion devices, but can present problems for plasma facing components because of high transient heat loads. Here the range of techniques for ELM control deployed in fusion devices is reviewed. The two baseline strategies in the ITER baseline design are emphasized: rapid ELM triggering and peak heat flux control via pellet injection, and the use of magnetic perturbations to suppress or mitigate ELMs. While both of these techniques are moderately well developed, with reasonable physical bases for projecting to ITER, differing observations between multiple devices are also discussed to highlight the needed community R & D. In addition, recent progress in ELM-free regimes, namely Quiescent H-mode, I-mode, and Enhanced Pedestal H-mode is reviewed, and open questions for extrapolability are discussed. Finally progress and outstanding issues in alternate ELM control techniques are reviewed: supersonic molecular beam injection, edge electron cyclotron heating, lower hybrid heating and/or current drive, controlled periodic jogs of the vertical centroid position, ELM pace-making via periodic magnetic perturbations, ELM elimination with lithium wall conditioning, and naturally occurring small ELM regimes.
Directory of Open Access Journals (Sweden)
B. Deutsch
2010-04-01
Full Text Available Rates of denitrification in sediments were measured with the isotope pairing technique at different sites in the southern and central Baltic Sea. They varied between 0.5 ?mol m^{?2} h^{?1} in sands and 28.7 ?mol m^{?2} h^{?1} in muddy sediments and showed a good correlation to the organic carbon contents of the surface sediments. N-removal rates via sedimentary denitrification were estimated for the entire Baltic Sea calculating sediment specific denitrification rates and interpolating them to the whole Baltic Sea area. Another approach was carried out by using the relationship between the organic carbon content and the rate of denitrification. For the entire Baltic Sea the N-removal by denitrification in sediments varied between 426–652 kt N a^{?1}, which is around 48–73% of the external N inputs delivered via rivers, coastal point sources and atmospheric deposition. Moreover, an expansion of the anoxic bottom areas was considered under the assumption of a rising oxycline from 100 to 80 m water depth. This leads to an increase of the area with anoxic conditions and an overall decrease in sedimentary denitrification by 14%. Overall we can show here that this type of data extrapolation is a powerful tool to estimate the nitrogen losses for a whole coastal sea and may be applicable to other coastal regions and enclosed seas, too.
What you see may not always be what you get : Bioavailability and extrapolation from in vitro tests
DEFF Research Database (Denmark)
Nielsen, Jesper Bo
2008-01-01
In human risk assessment, bioavailability needs to be considered when relying on in vitro toxicity results. For single chemicals, this quantitative challenge is often handled through a bioavailability factor. For mixtures, however, things are more complicated. Thus, individual constituents may not only interact toxicodynamically and toxicokinetically, but the composition of constituents reaching the target site may also differ from what was present at the site of exposure due to the differences in their bioavailabilities. A recent study concluded on the in vivo potential of Australian tea-tree oil (TTO) to act as an endocrine disruptor based on an in vitro protocol measuring the growth of MCF-7 cells following chemical exposure to TTO. TTO is primarily used topically in humans, and is not a single chemical but is a mixture with some constituents penetrating the skin which others do not. The present study evaluated in an identical in vitro model to what extent TTO and its skin penetrating constituents affected the growth of MCF-7 cells. The estrogenic potency of TTO was confirmed, but none of the bioavailable TTO constituents demonstrated estrogenicity. The present study, therefore, cautions in vitro to in vivo extrapolations from the mixtures of constituents with potentially varying bioavailabilities. Udgivelsesdato: June
Tassis, Konstantinos
2014-01-01
Recent Planck results have shown that the path to isolating an inflationary B-mode signal in microwave polarization passes through understanding and modeling the interstellar dust polarized emission foreground, even in regions of the sky with the lowest level of dust emission. One of the most commonly used ways to remove the dust foreground is to extrapolate the polarized dust emission signal from frequencies where it dominates (e.g., 350 GHz) to frequencies commonly targeted by cosmic microwave background experiments (e.g., 150 GHz). We show, using a simple 2-cloud model, that if more than one cloud is present along the line-of-sight, with even mildly different temperature and dust column density, but severely misaligned magnetic field, then the 350 GHz polarized sky map is not predictive of that at 150 GHz. This problem is intrinsic to all microwave experiments and is due to information loss due to line-of-sight integration. However, it can be alleviated through interstellar medium tomography: a reconstruct...
Maingi, R.
2014-11-01
Large edge localized modes (ELMs) typically accompany good H-mode confinement in fusion devices, but can present problems for plasma facing components because of high transient heat loads. Here the range of techniques for ELM control deployed in fusion devices is reviewed. Two strategies in the ITER baseline design are emphasized: rapid ELM triggering and peak heat flux control via pellet injection, and the use of magnetic perturbations to suppress or mitigate ELMs. While both of these techniques are moderately well developed, with reasonable physical bases for projecting to ITER, differing observations between multiple devices are also discussed to highlight the needed community R&D. In addition, recent progress in ELM-free regimes, namely quiescent H-mode, I-mode, and enhanced pedestal H-mode is reviewed, and open questions for extrapolability are discussed. Finally progress and outstanding issues in alternate ELM control techniques are reviewed: supersonic molecular beam injection, edge electron cyclotron heating, lower hybrid heating and/or current drive, controlled periodic jogs of the vertical centroid position, ELM pace-making via periodic magnetic perturbations, ELM elimination with lithium wall conditioning, and naturally occurring small ELM regimes.
Scientific Electronic Library Online (English)
José Francisco dos, Reis Sobrinho; Levi de Oliveira, Bueno.
2014-04-01
Full Text Available Hot tensile and creep data were obtained for 2.25Cr-1Mo steel, ASTM A387 Gr.22CL2, at the temperatures of 500-550-600-650-700 °C. Using the concept of equivalence between hot tensile data and creep data, the results were analyzed according to the methodology based on Kachanov Continuum Damage Mechan [...] ics proposed by Penny, which suggests the possibility of using short time creep data obtained in laboratory for extrapolation to long operating times corresponding to tens of thousands hours. The hot tensile data (converted to creep) define in a better way the region where ?=0 and the creep data define the region where ?=1, according to the methodology. Extrapolation to 10,000 h and 100,000 h is performed and the results compared with results obtained by other extrapolation procedures such as the Larson-Miller and Manson-Haferd methodologies. Extrapolation from ASTM and NIMS Datasheets for 10,000 h and 100,000 h as well as data from other authors on 2.25Cr-1Mo steel are used for assessing the reliability of the results.
cDNA Cloning of Fathead minnow (Pimephales promelas) Estrogen and Androgen Receptors for Use in Steroid Receptor Extrapolation Studies for Endocrine Disrupting Chemicals. Wilson, V.S.1,, Korte, J.2, Hartig P. 1, Ankley, G.T.2, Gray, L.E., Jr 1, , and Welch, J.E.1. 1U.S...
Grafting of HEMA onto dopamine coated stainless steel by 60Co-? irradiation method
Jin, Wanqin; Yang, Liming; Yang, Wei; Chen, Bin; Chen, Jie
2014-12-01
A novel method for grafting of 2-hydroxyethyl methacrylate (HEMA) onto the surface of stainless steel (SS) was explored by using 60Co-? irradiation. The surface of SS was modified by coating of dopamine before radiation grafting. The grafting reaction was performed in a simultaneous irradiation condition. The chemical structures change of the surface before and after grafting was demonstrated by Fourier transform infrared (FTIR) spectrometer. The hydrophilicity of the samples was determined by water contact angle measurement in the comparison of the stainless steel in the conditions of pristine, dopamine coated and HEMA grafted. Surface morphology of the samples was characterized by atomic force microscope (AFM) and scanning electron microscope (SEM). The corrosion resistance properties of the samples were evaluated by Tafel polarization curve. The hemocompatibility of the samples were tested by platelet adhesion assay.
International Nuclear Information System (INIS)
Testing was performed to determine if gravel particles will creep into and puncture the high-density polyethylene (HDPE) liner in the catch basin of a grout vault over a nominal 30-year period. Testing was performed to support a design without a protective geotextile cover after the geotextile was removed from the design. Recently, a protective geotextile cover over the liner was put back into the design. The data indicate that the geotextile has an insignificant effect on the creep of gravel into the liner. However, the geotextile may help to protect the liner during construction. Two types of tests were performed to evaluate the potential for creep-related puncture. In the first type of test, a very sensitive instrument measured the rate at which a probe crept into HDPE over a 20-minute period at temperatures of 176 degrees F to 212 degrees F (80 degrees C to 100 degrees C). The second type of test consisted of placing the liner between gravel and mortar at 194 degrees F (90 degrees C) and 45.1 psi overburden pressure for periods up to 1 year. By combining data from the two tests, the long-term behavior of the creep was extrapolated to 30 years of service. After 30 years of service, the liner will be in a nearly steady condition and further creep will be extremely small. The results indicate that the creep of gravel into the liner will not create a puncture during service at 194 degrees F (90 degrees C). The estimated creep over 30 years is expected to be less than 25 mils out of the total initial thickness of 60 mils. The test temperature of 194 degrees F (90 degrees C) corresponds to the design basis temperature of the vault. Lower temperatures are expected at the liner, which makes the test conservative. Only the potential for failure of the liner resulting from creep of gravel is addressed in this report
Directory of Open Access Journals (Sweden)
Leonieke Vermeer
2007-01-01
Full Text Available
'If the table turns, science will stagger'. The relationship between spiritualism and science in the Netherlands around 1900
Spiritualism is the belief that living men can keep contact, usually through an intermediary called a 'medium', with spirits of the dead. The history of modern spiritualism started in 1848 in America and in the decades that followed it spread all over the world. Especially as a result of British influences modern Anglo-Saxon spiritualism is characterized by a search for scientific proof of the so-called spiritualist phenomena. In the 1920s the Netherlands were late in comparison with neighbouring countries to institutionalize the scientific study of these phenomena. But this does not imply that there was no earlier discussion about it. Indeed, around 1900 there were attempts for a debate about the scientific underpinning of spiritualism and the main stage for it was the journal Het toekomstig leven [The future life]. In the historical conceptualization of this debate it has long been common to see the spiritualists as an anti-modern counterculture and the scientists as the representatives of modernity. Recently this dichotomic order has been replaced for a nuanced view that does more justice to the historical reality. Although Het toekomstig leven often used rhetoric strategies that emphasized the confrontation with science, the journal also lavishly incorporated scientific elements and made inexhaustible attempts for a scientific debate and study of the paranormal phenomena. Unlike in neighbouring countries there were hardly any natural scientists who responded, but there were some physicians as well as pioneers of the new field of parapsychology who pleaded for scientific research of spiritualism. This research eventually became reality in 1920 under the direction of some heavyweight scientists, but just as Het toekomstig leven the Dutch Society for Psychical Research was also marked by the difference between the critical-scientific approach and the not so critical approach of the believers. In my contribution I have showed that this demarcation was however not the same as the one between science and spiritualism, because these boundaries were considerably permeable.
Mathematical methods for physical and analytical chemistry
Goodson, David Z
2011-01-01
Mathematical Methods for Physical and Analytical Chemistry presents mathematical and statistical methods to students of chemistry at the intermediate, post-calculus level. The content includes a review of general calculus; a review of numerical techniques often omitted from calculus courses, such as cubic splines and Newton's method; a detailed treatment of statistical methods for experimental data analysis; complex numbers; extrapolation; linear algebra; and differential equations. With numerous example problems and helpful anecdotes, this text gives chemistry students the mathematical
Energy Technology Data Exchange (ETDEWEB)
Schabel, C.; Bongers, M.; Grosse, U.; Mangold, S.; Claussen, C.D.; Thomas, C. [University Hospital of Tuebingen (Germany). Dept. of Diagnostic and Interventional Radiology; Sedlmair, M. [Siemens AG, Forchheim (Germany). Healthcare; Korn, A. [University Hospital of Tuebingen (Germany). Dept. of Diagnostic and Interventional Neuroradiology
2014-06-15
Purpose: To evaluate a novel monoenergetic post-processing algorithm (MEI+) in patients with poor intrahepatic contrast enhancement. Materials and Methods: 25 patients were retrospectively included in this study. Late-phase imaging of the upper abdomen, which was acquired in dual-energy mode (100/140 kV), was used as a model for poor intrahepatic contrast enhancement. Traditional monoenergetic images (MEI), linearly weighted mixed images with different mixing ratios (MI), sole 100 and 140 kV and MEI+ images were calculated. MEI+ is a novel technique which applies frequency-based mixing of the low keV images and an image of optimal keV from a noise perspective to combine the benefits of both image stacks. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the intrahepatic vasculature (IHV) and liver parenchyma (LP) were objectively measured and depiction of IHV was subjectively rated and correlated with portal venous imaging by two readers in consensus. Results: MEI+ was able to increase the SNR of the IHV (5.7 ± 0.4 at 40 keV) and LP (4.9 ± 1.0 at 90 keV) and CNR (2.1 ± 0.6 at 40 keV) greatly compared to MEI (5.1 ± 1.1 at 80 keV, 4.7 ± 1.0 at 80 keV, 1.0 ± 0.4 at 70 keV), MI (5.2 ± 1.1 M5:5, 4.8 ± 1.0 M5:5, 1.0 ± 3.5 M9:1), sole 100 kV images (4.4 ± 1.0, 3.7 ± 0.8, 1.0 ± 0.3) and 140 kV images (2.8 ± 0.5, 3.1 ± 0.6, 0.1 ± 0.2). Subjective assessment rated MEI+ of virtual 40 keV superior to all other images. Conclusion: MEI+ is a very promising algorithm for monoenergetic extrapolation which is able to overcome noise limitations associated with traditional monoenergetic techniques at low virtual keV levels and consequently does not suffer from a decline of SNR and CNR at low keV values. This algorithm allows an improvement of IHV depiction in the presence of poor contrast. (orig.)
International Nuclear Information System (INIS)
Purpose: To evaluate a novel monoenergetic post-processing algorithm (MEI+) in patients with poor intrahepatic contrast enhancement. Materials and Methods: 25 patients were retrospectively included in this study. Late-phase imaging of the upper abdomen, which was acquired in dual-energy mode (100/140 kV), was used as a model for poor intrahepatic contrast enhancement. Traditional monoenergetic images (MEI), linearly weighted mixed images with different mixing ratios (MI), sole 100 and 140 kV and MEI+ images were calculated. MEI+ is a novel technique which applies frequency-based mixing of the low keV images and an image of optimal keV from a noise perspective to combine the benefits of both image stacks. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the intrahepatic vasculature (IHV) and liver parenchyma (LP) were objectively measured and depiction of IHV was subjectively rated and correlated with portal venous imaging by two readers in consensus. Results: MEI+ was able to increase the SNR of the IHV (5.7 ± 0.4 at 40 keV) and LP (4.9 ± 1.0 at 90 keV) and CNR (2.1 ± 0.6 at 40 keV) greatly compared to MEI (5.1 ± 1.1 at 80 keV, 4.7 ± 1.0 at 80 keV, 1.0 ± 0.4 at 70 keV), MI (5.2 ± 1.1 M5:5, 4.8 ± 1.0 M5:5, 1.0 ± 3.5 M9:1), sole 100 kV images (4.4 ± 1.0, 3.7 ± 0.8, 1.0 ± 0.3) and 140 kV images (2.8 ± 0.5, 3.1 ± 0.6, 0.1 ± 0.2). Subjective assessment rated MEI+ of virtual 40 keV superior to all other images. Conclusion: MEI+ is a very promising algorithm for monoenergetic extrapolation which is able to overcome noise limitations associated with traditional monoenergetic techniques at low virtual keV levels and consequently does not suffer from a decline of SNR and CNR at low keV values. This algorithm allows an improvement of IHV depiction in the presence of poor contrast. (orig.)
Kujur, Alice; Bajaj, Deepak; Upadhyaya, Hari D.; Das, Shouvik; Ranjan, Rajeev; Shree, Tanima; Saxena, Maneesha S.; Badoni, Saurabh; Kumar, Vinod; Tripathi, Shailesh; Gowda, C. L. L.; Sharma, Shivali; Singh, Sube; Tyagi, Akhilesh K.; Parida, Swarup K.
2015-01-01
The genome-wide discovery and high-throughput genotyping of SNPs in chickpea natural germplasm lines is indispensable to extrapolate their natural allelic diversity, domestication, and linkage disequilibrium (LD) patterns leading to the genetic enhancement of this vital legume crop. We discovered 44,844 high-quality SNPs by sequencing of 93 diverse cultivated desi, kabuli, and wild chickpea accessions using reference genome- and de novo-based GBS (genotyping-by-sequencing) assays that were physically mapped across eight chromosomes of desi and kabuli. Of these, 22,542 SNPs were structurally annotated in different coding and non-coding sequence components of genes. Genes with 3296 non-synonymous and 269 regulatory SNPs could functionally differentiate accessions based on their contrasting agronomic traits. A high experimental validation success rate (92%) and reproducibility (100%) along with strong sensitivity (93–96%) and specificity (99%) of GBS-based SNPs was observed. This infers the robustness of GBS as a high-throughput assay for rapid large-scale mining and genotyping of genome-wide SNPs in chickpea with sub-optimal use of resources. With 23,798 genome-wide SNPs, a relatively high intra-specific polymorphic potential (49.5%) and broader molecular diversity (13–89%)/functional allelic diversity (18–77%) was apparent among 93 chickpea accessions, suggesting their tremendous applicability in rapid selection of desirable diverse accessions/inter-specific hybrids in chickpea crossbred varietal improvement program. The genome-wide SNPs revealed complex admixed domestication pattern, extensive LD estimates (0.54–0.68) and extended LD decay (400–500 kb) in a structured population inclusive of 93 accessions. These findings reflect the utility of our identified SNPs for subsequent genome-wide association study (GWAS) and selective sweep-based domestication trait dissection analysis to identify potential genomic loci (gene-associated targets) specifically regulating important complex quantitative agronomic traits in chickpea. The numerous informative genome-wide SNPs, natural allelic diversity-led domestication pattern, and LD-based information generated in our study have got multidimensional applicability with respect to chickpea genomics-assisted breeding.
International Nuclear Information System (INIS)
The removal of dissolved gas in the vacuum in combination with the chemical oxygen absorption with sodium hydrosulfate (Na2-S2O4) and/or its radiation absorption permits to remove all traces of hydrogen from cells, if they are cultivated on glass cups. In the case of X-ray irradiation of these cells, the extrapolation number does not depend on whether irradiation is carried out under aerobic or anaerobic conditions, with oxygen effect value being 3.0
Hicks, R. M.; Mendoza, J. P.; Thomas, C. L.
1972-01-01
Wind tunnel pressure signatures measured at Mach 10.1 for model of the Apollo Command Module and at Mach numbers from 3.01 to 7.91 for two models of the Saturn launch configuration are presented. The signatures for the command module were obtained at roll angles ranging from 0 deg to 180 deg. A brief discussion of the extrapolation of strong pressure signatures is included in the report.
Ciambella, J; Paolone, A; Vidoli, S
2014-09-01
We report about the experimental identification of viscoelastic constitutive models for frequencies ranging within 0-10Hz. Dynamic moduli data are fitted forseveral materials of interest to medical applications: liver tissue (Chatelin et al., 2011), bioadhesive gel (Andrews et al., 2005), spleen tissue (Nicolle et al., 2012) and synthetic elastomer (Osanaiye, 1996). These materials actually represent a rather wide class of soft viscoelastic materials which are usually subjected to low frequencies deformations. We also provide prescriptions for the correct extrapolation of the material behavior at higher frequencies. Indeed, while experimental tests are more easily carried out at low frequency, the identified viscoelastic models are often used outside the frequency range of the actual test. We consider two different classes of models according to their relaxation function: Debye models, whose kernel decays exponentially fast, and fractional models, including Cole-Cole, Davidson-Cole, Nutting and Havriliak-Negami, characterized by a slower decay rate of the material memory. Candidate constitutive models are hence rated according to the accurateness of the identification and to their robustness to extrapolation. It is shown that all kernels whose decay rate is too fast lead to a poor fitting and high errors when the material behavior is extrapolated to broader frequency ranges. PMID:24967977
Corrosion inhibition of brass by aliphatic amines
International Nuclear Information System (INIS)
Aliphatic amines hexylamine (HCA), octylamine (OCA) and decylamine (DCA) have been used as corrosion inhibitors for (70/30) brass in 0.I M HCIO4. The inhibitor efficiency (%P) calculated using weight loss, Tafel extrapolation, linear polarization and impedance methods was found to be in the order DCA> OCA> HCA. These adsorb on brass surface following bockris-swinkels' isotherm. DCA, OCA and HCA displaced 4, 3 and 2 molecules of water from interface respectively. Displacement of water molecules brought a great reorganization of double layer at the interface. These amines during corrosion form complexes with dissolved zinc and copper ions.(Author)
Scientific Electronic Library Online (English)
Pradeep, Kumar; A. Nityananda, Shetty.
2013-01-01
Full Text Available The corrosion behaviour of welded maraging steel in hydrochloric acid solutions was studied over a range of acid concentration and solution temperature by electrochemical techniques like Tafel extrapolation method and electrochemical impedance spectroscopy. The corrosion rate of welded maraging stee [...] l increases with the increase in temperature and concentration of hydrochloric acid in the medium. The energies of activation, enthalpy of activation and entropy of activation for the corrosion process were calculated. The surface morphology of the corroded sample was evaluated by surface examination using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS).
The proposed paradigm for ?Toxicity Testing in the 21st Century? supports the development of mechanistically-based, high-throughput in vitro assays as a potential cost effective and scientifically-sound alternative to some whole animal hazard testing. To accomplish this long-term...
International Nuclear Information System (INIS)
The following report has as objective to present the obtained results of measuring - with a camera of extrapolation of variable electrodes (CE) - the dose speed absorbed in equivalent fabric given by the group of sources of the secondary pattern of radiation Beta Nr. 86, (PSB), and to compare this results with those presented by the calibration certificates that accompany the PSB extended by the primary laboratory Physikalisch Technische Bundesanstalt, (PTB), of the R.F.A. as well as the uncertainties associated to the measure process. (Author)
International Nuclear Information System (INIS)
Thiosemicarbazones have attracted great pharmacological interest because of their biological properties, such as cytotoxic activity against multiple strains of human tumors. Due to the excellent properties of 64Cu, the copper complex N(4)-ortho-toluyl-2-acetylpyridine thiosemicarbazone ( (64Cu)(H2Ac4oT)Cl) was developed for tumor detection by positron emission tomography. The radiopharmaceuticals were produced in the nuclear reactor TRIGA-IPR-R1 from CDTN. At the present work, (64Cu)(H2Ac4oT)Cl biokinetic data (evaluated in mice bearing Ehrlich tumor) were treated by MIRD formalism to perform Internal Dosimetry studies. Doses in several organs of mice were determinate, as well as in implanted tumor, for (64Cu)(H2Ac4oT)Cl. Doses results obtained for animal model were extrapolated to humans assuming a similar concentration ratio among various tissues between mouse and human. In the extrapolation, it was used human organ masses from Cristy/Eckerman phantom. Both penetrating and non-penetrating radiation from 64Cu in the tissue were considered in dose calculations. (author)
International Nuclear Information System (INIS)
The austenitic stainless steel X6CrNi1811 (DIN 1.4948) used as a structure material for the German Fast Breeder Reactor SNR 300 was creep tested in a temperature range of 550-650 deg under base material condition as well as welded material condition. The main point of this program (''Extrapolation-Program'') lies in the knowledge of the creep-rupture-strength and creepbehaviour up to 3 x 104 hours at higher temperatures in order to extrapolate up to >=105 hours for operating temperatures. In order to study the stress dependency of the minimum creep rate additional tests were carried out of 550 deg - 750 deg C. The present report describes the state in the running program with test-times of 23.000 hours and results from tests up to 55.000 hours belonging to other parallel programs are taken into account. Besides the creep-rupture behaviour it is also made a study of ductility between 550 and 750 deg C. Extensive metallographic examinations have been made to study the fracture behaviour and changes in structure. (author)
International Nuclear Information System (INIS)
The austenitic stainless steel X6CrNi1811 (DIN 1.4948) that is used as a structure material for the German Fast Breeder Reactor SNR 300 was creep-tested in a temperature range of 550-6500C under base material condition as well as welded material condition. The main point of this program ( Extrapolation Program ) lies in the knowledge of the creep-rupture-strength and creep-behaviour up to 3 x 104 hours at higher temperatures in order to extrapolate up to >= 105 hours for operating temperatures. In order to study the stress dependency of the minimum creep rate additional tests were carried out over temperature range of 550-7500C. The present report describes the state in the total running program with test-times up to 55 000 hours. Besides the creep-rupture behaviour it is possible to make a distinct quantitativ statement for the creep-behaviour and ductility. Extensive metallographic and electronmicroscopic examinations show the fracture behaviour and changes in structure. (orig.)
International Nuclear Information System (INIS)
The austenitic stainless steel X6CrNi1811 (DIN 1.4948) that is used as a structure material for the German Fast Breeder Reactor SNR 300 was creep tested in a temperature range of 550-6500C under base material condition as well as welded material condition. The main point of this program ('Extrapolation-Program') lies in the knowledge of the creep-rupture-strength and creep-behaviour up to 3 x 104 hours at higher temperatures in order to extrapolate up to >= 105 hours for operating temperatures. In order to study the stress dependency of the minimum creep rate additional tests were carried out over temperature range of 5500C - 7500C. The present report describes the state in the running program with test-times up to 35.000 hours. Besides the creep-rupture behaviour it is possible to make a distinct quantitativ statement for the creep-behaviour and ductility. Extensive metallographic examinations show the fracture behaviour and changes in structure. (orig.)
International Nuclear Information System (INIS)
The austenitic stainless steel X6 CrNi 1811 (DIN 1.4948) that is used as a structure material for the German Fast Breeder Reactor SNR 300 was creep tested in a temperature range of 550-650 deg under base material condition as well as welded material condition. The main point of this program (''Extrapolation-Program'') lies in the knowledge of the cree-rupture-strength and creep-behaviour up to 3X10-4 hours at higher temperatures in order to extrapolate up to (>=)105 hours for operating temperatures. In order to study the stress dependency of the minimum creep rate additional tests were carried out over temperature range 550 deg - 750 deg C. The present report describes the state in the running program with test-time up to 35.000 hours. Besides the cree-rupture behaviour it is possible to make a distinct quantitative statement for the creep-behaviour and ductility. Extensive metallographic examinations show the fracture behaviour and changes in structure. (author)
The HBOM Method for Unfolding Detector Effects
Monk, James W.; Oropeza-barrera, Cristina
2011-01-01
We present the Hit Backspace Once More (HBOM) method for correcting a measurement for the effect of an imperfect detector. The HBOM method is a model-independent and potentially data-driven technique that repeatedly applies a parameterisation of the detector effect to observed data. The correction is determined by extrapolating the data so-obtained to a detector effect of zero. We demonstrate this technique using the two particle correlation function, which is an observable ...
Directory of Open Access Journals (Sweden)
Botton R.
2006-12-01
Full Text Available Les unités de production en lits fluidisés catalytiques sont apparues vers 1942 dans l'industrie pétrolière et vers 1960 dans l'industrie chimique. On se limitera ici au problème de l'extrapolation des lits fluidisés catalytiques pour l'industrie chimique, qui exigent de très hautes performances (> 99 % de conversion. Leur mise au point a, dans le passé, nécessité l'exploitation sur des sites industriels de coûteux pilotes de 0,5 m de diamètre et de plus de 10 m de hauteur. Nous montrerons que ces pilotes peuvent être évités et que le passage direct du laboratoire à l'échelle industrielle est réalisable. Cette possibilité offre en plus une méthode simple pour améliorer les catalyseurs des unités industrielles. Elle ouvre aussi cette technique, très appréciée en production, aux produits de petits tonnages. La présentation de cet article sera faite en trois parties : - La première, présentée ci-après, expose les problèmes majeurs posés par l'extrapolation, puis résume les études effectuées. Les travaux d'extrapolation relatifs à deux procédés effectués avec des pilotes sont ensuite présentés, à titre d'exemples. De ces travaux sont déduites les performances que l'on peut espérer obtenir avec un réacteur catalytique à lit fluidisé, ainsi que les règles de tendances à suivre pour y parvenir. - La deuxième partie, intitulée Stratégie n'utilisant que des expériences de laboratoire , propose une stratégie expérimentale permettant d'obtenir en laboratoire les informations nécessaires pour passer directement à l'échelle industrielle avec des expériences suggérées en partie par les résultats exposés dans le premier article. Les relations expérimentales établies lors de ces études montrent que les propriétés d'un lit fluidisé ne dépendent (mis à part quelquefois le diamètre du réacteur que d'un paramètre appelé vitesse minimum de fluidisation de comportement . - La troisième partie est intitulée Études théoriques, réalités expérimentales, suggestions . Les bulles des lits fluidisés ont fait l'objet de très nombreux travaux, dont les résultats sont très souvent explicités sous la forme de modèles mécanistiques à un paramètre qui est le diamètre des bulles. Pour confronter ces modèles à l'expérience, une relation est établie entre le diamètre des bulles et la vitesse minimum de fluidisation de comportement. Des suggestions sont alors faites pour améliorer les modèles, et l'on propose des conclusions générales sur les lits fluidisés. The firsts catalytic fluidized beds appear near 1942 in petroleum industry and near 1960 in chemical industry. We only consider very high performances chemical fluidized bed reactors (> 99%. In the past, they were developed through the use of very expensive pilot plants of about 0. 5 m diameter and 10 in high. We will demonstrate that direct scale up from laboratory data is possible. This possibility gives also a simple method to improve catalysts used into operating units and opens fluidized bed technique to products that need only low production. Presentation is made with three articles:- In the first, Studies, Models, Learning from Pilot Plants : after a description of the major scale-up problems, studies to solve then are summarized. Then scale-up works of two processes with the use of about 0. 5 m diameter pilot plant are given. From the results it is deduced the possible performances of a catalytic fluidized bed and how to operate to obtain then. - In the second*, Scale up with Only Laboratory Data , it is experimentally demonstrated that the information's scale-up can be obtained in a laboratory. A strategy to obtain them is suggested. An another result of theses experimental studies is that all physical properties of catalytic fluidized bed depends of only one parameter. It is called comportment incipient fluidization velocity . - In the third*, Theoretical Studies, Experimental Reality, Suggestionsresults of theoretical studies about bubbles of the fluidized beds are summarize
Escobedo, Fernando A.
2014-03-01
In this work, a variant of the Gibbs-Duhem integration (GDI) method is proposed to trace phase coexistence lines that combines some of the advantages of the original GDI methods such as robustness in handling large system sizes, with the ability of histogram-based methods (but without using histograms) to estimate free-energies and hence avoid the need of on-the-fly corrector schemes. This is done by fitting to an appropriate polynomial function not the coexistence curve itself (as in GDI schemes) but the underlying free-energy function of each phase. The availability of a free-energy model allows the post-processing of the simulated data to obtain improved estimates of the coexistence line. The proposed method is used to elucidate the phase behavior for two non-trivial hard-core mixtures: a binary blend of spheres and cubes and a system of size-polydisperse cubes. The relative size of the spheres and cubes in the first mixture is chosen such that the resulting eutectic pressure-composition phase diagram is nearly symmetric in that the maximum solubility of cubes in the sphere-rich solid (˜20%) is comparable to the maximum solubility of spheres in the cube-rich solid. In the polydisperse cube system, the solid-liquid coexistence line is mapped out for an imposed Gaussian activity distribution, which produces near-Gaussian particle-size distributions in each phase. A terminal polydispersity of 11.3% is found, beyond which the cubic solid phase would not be stable, and near which significant size fractionation between the solid and isotropic phases is predicted.
Density-of-states calculations within the recursion method
International Nuclear Information System (INIS)
We investigate methods to calculate projected density of states from a finite set of recursion coefficients. We consider tight-binding Hamiltonians describing the diamond-structure semiconductors ?-Sn, Ge, Si, and C. Coefficients for about 110 levels of recursion are available for these Hamiltonians. Thus, we have coefficients for a sufficient number of recursion levels so that their asymptotic behavior is apparent. We first extrapolate the calculated coefficients using a linear predictive analysis suggested by Allan. This extrapolation is based on a perturbation theory that assumes that band gaps are small compared to the bandwidth. For ?-Sn, Ge, and Si, which have band gap to bandwidth ratios (for the model Hamiltonians) of less than 0.05, the extrapolation procedure is found to be very successful. For C, however, with a band gap to bandwidth ratio of 0.106, large spurious features, which can be clearly associated with second-order perturbation terms, appear in the calculated density of states. We modify the extrapolation procedure using nonperturbative results for the asymptotic behavior of the recursion coefficients. The new extrapolation procedure gives good densities of states for C. Also, the calculated Green's function has the correct analytic structure
Li, Li; Kantor, Angela; Warne, Nicholas
2013-01-01
Previous publications demonstrated that the extrapolated solubility by polyethylene glycol (PEG) precipitation method (Middaugh et al., J Biol Chem 1979; 254:367–370; Juckes, Biochim Biophys Acta 1971; 229:535–546; Foster et al., Biochim Biophys Acta 1973; 317:505; Mahadevan and Hall, AIChE J 1990; 36:1517–1528; Stevenson and Hageman, Pharm Res 1995; 12:1671–1676) has a strong correlation to experimentally measured solubility of proteins. Here, we explored the utility of extrapolated ...
Gangodagamage, Chandana; Rowland, Joel C; Hubbard, Susan S; Brumby, Steven P; Liljedahl, Anna K; Wainwright, Haruko; Wilson, Cathy J; Altmann, Garrett L; Dafflon, Baptiste; Peterson, John; Ulrich, Craig; Tweedie, Craig E; Wullschleger, Stan D
2014-01-01
Landscape attributes that vary with microtopography, such as active layer thickness (ALT), are labor intensive and difficult to document effectively through in situ methods at kilometer spatial extents, thus rendering remotely sensed methods desirable. Spatially explicit estimates of ALT can provide critically needed data for parameterization, initialization, and evaluation of Arctic terrestrial models. In this work, we demonstrate a new approach using high-resolution remotely sensed data for estimating centimeter-scale ALT in a 5 km2 area of ice-wedge polygon terrain in Barrow, Alaska. We use a simple regression-based, machine learning data-fusion algorithm that uses topographic and spectral metrics derived from multisensor data (LiDAR and WorldView-2) to estimate ALT (2 m spatial resolution) across the study area. Comparison of the ALT estimates with ground-based measurements, indicates the accuracy (r2?=?0.76, RMSE ±4.4 cm) of the approach. While it is generally accepted that broad climatic variability associated with increasing air temperature will govern the regional averages of ALT, consistent with prior studies, our findings using high-resolution LiDAR and WorldView-2 data, show that smaller-scale variability in ALT is controlled by local eco-hydro-geomorphic factors. This work demonstrates a path forward for mapping ALT at high spatial resolution and across sufficiently large regions for improved understanding and predictions of coupled dynamics among permafrost, hydrology, and land-surface processes from readily available remote sensing data. PMID:25558114
Gangodagamage, Chandana; Rowland, Joel C.; Hubbard, Susan S.; Brumby, Steven P.; Liljedahl, Anna K.; Wainwright, Haruko; Wilson, Cathy J.; Altmann, Garrett L.; Dafflon, Baptiste; Peterson, John; Ulrich, Craig; Tweedie, Craig E.; Wullschleger, Stan D.
2014-08-01
Landscape attributes that vary with microtopography, such as active layer thickness (ALT), are labor intensive and difficult to document effectively through in situ methods at kilometer spatial extents, thus rendering remotely sensed methods desirable. Spatially explicit estimates of ALT can provide critically needed data for parameterization, initialization, and evaluation of Arctic terrestrial models. In this work, we demonstrate a new approach using high-resolution remotely sensed data for estimating centimeter-scale ALT in a 5 km2 area of ice-wedge polygon terrain in Barrow, Alaska. We use a simple regression-based, machine learning data-fusion algorithm that uses topographic and spectral metrics derived from multisensor data (LiDAR and WorldView-2) to estimate ALT (2 m spatial resolution) across the study area. Comparison of the ALT estimates with ground-based measurements, indicates the accuracy (r2 = 0.76, RMSE ±4.4 cm) of the approach. While it is generally accepted that broad climatic variability associated with increasing air temperature will govern the regional averages of ALT, consistent with prior studies, our findings using high-resolution LiDAR and WorldView-2 data, show that smaller-scale variability in ALT is controlled by local eco-hydro-geomorphic factors. This work demonstrates a path forward for mapping ALT at high spatial resolution and across sufficiently large regions for improved understanding and predictions of coupled dynamics among permafrost, hydrology, and land-surface processes from readily available remote sensing data.
Ravishankaran, Praveen; Krishnamurthy, Arvind
2014-01-01
Background: Transthoracic esophagectomy (TTE) and transhiatal esophagectomy (THE) are the two most common surgical approaches for carcinoma esophagus. Several studies have shown lymph nodal involvement to be one of the most important prognostic factors in carcinoma esophagus. Aims: The primary objective of this study was to explore the effectiveness of the ratio of positive lymph nodes to excised lymph nodes, namely the metastatic lymph nodal ratio (MLNR) as a prognostic factor in the survival of patients with carcinoma esophagus. Settings and Design: Retrospective analysis of a prospective database. Materials and Methods: A review of the operated esophageal cancer patients treated at a tertiary cancer center in South India between January 2002 and December 2006. Statistical analysis was done with the help of SPSS version 17 software (SPSS Inc., Chicago, IL). Proportions were compared using the Chi-square test. Survival data was generated using life table methods. Differences in survival estimates were compared using log-rank test. Results and Conclusions: Our study emphatically showed that the survival outcomes of patients with squamous cell carcinoma of the esophagus can be discriminated based on the MLNR groups, and it can be a reliable prognostic indicator. The overall survival for patients undergoing TTE, or THE for the entire cohort of patients was however not statistically significant. Whether a more aggressive TTE is a better esophageal cancer operation or whether MLNR is the factor that can significantly impact survival regardless of the technique is an issue that would require further investigation. PMID:25422807
International Nuclear Information System (INIS)
A transient tritium hold-up and permeation model is developed and applied to a simplified conceptual design of a water cooled Li17Pb83 blanket. Tritium inventories in the blanket associated with diffusivity, solubility and trapping effects are estimated. The model is applied to the INTOR/NET LiPb blanket design. Assuming a daily LiPb reprocessing frequency a tritium production rate of 64 grams per day yields a total tritium inventory in the blanket comparable to that of the tritium system or trapped in the first wall. The diffusion-limited permeation rate (neglecting oxide layers effects) reaches 4.2 g/day. The extrapolation of these results to reactor relevant conditions aggravates the permeation and the associated problems. (author)
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Estimates and techniques that are valid to calculate the linear extrapolation distance for an infinitely long circular cylindrical absorbing region are reviewed. Two estimates, in particular, are put into consideration, that is the most probable and the value resulting from an approximate technique based on matching the integral transport equation inside the absorber with the diffusion approximation in the surrounding infinite scattering medium. Consequently, the effective diffusion parameters and the blackness of the cylinder are derived and subjected to comparative studies. A computer code is set up to calculate and compare the different parameters, which is useful in reactor analysis and serves to establish a beneficial estimates that are amenable to direct application to reactor design codes
Borsányi, Szabolcs; Katz, Sándor D; Pásztor, Attila; Szabó, Kálmán K; Török, Csaba
2015-01-01
We study the correlators of Polyakov loops, and the corresponding gauge invariant free energy of a static quark-antiquark pair in 2+1 flavor QCD at finite temperature. Our simulations were carried out on $N_t$ = 6, 8, 10, 12, 16 lattices using Symanzik improved gauge action and a stout improved staggered action with physical quark masses. The free energies calculated from the Polyakov loop correlators are extrapolated to the continuum limit. For the free energies we use a two step renormalization procedure that only uses data at finite temperature. We also measure correlators with definite Euclidean time reversal and charge conjugation symmetry to extract two different screening masses, one in the magnetic, and one in the electric sector, to distinguish two different correlation lengths in the full Polyakov loop correlator.
Energy Technology Data Exchange (ETDEWEB)
Montero Prieto, M.; Vidania Munoz, R. de
1994-07-01
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.
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We report the mass measurement of the short-lived 12Be nuclide (T1/2=21.5 ms) performed using the Penning trap mass spectrometer TITAN at TRIUMF. Our mass excess value of 25 078.0(2.1) keV is in agreement with previous measurements, but is a factor of 7 more precise than the Atomic Mass Evaluation of 2003. To address an unresolved discussion on the spin assignment of isospin T=2 states in 12C and 12O, we reevaluate the isobaric mass multiplet equation for the lowest lying T=2 multiplet in the A=12 system and use the extracted parameters to extrapolate from the known excited 2+ and 0+ states in 12Be. Though this analysis favors the second known T=2 state in 12C to be 2+, 0+ cannot be excluded.
International Nuclear Information System (INIS)
This report addresses questions that arose after having completed a detailed study of a simulant-material experimental investigation of flow dynamics in the Upper Core Structures during a Core Disruptive Accident of a Liquid-Metal Fast Breeder Reactor. The main findings of the experiments were about the reduction of work potential of the expanding fuel by the presence of the Upper Core Structures. This report describes how the experimental data can be extrapolated to prototypic conditions, which phenomena modelled in code predictions by SIMMER-II are different for simulant and prototypic transients, and how the experimental results compare to effects of prototypic phenomena which could not be modelled in the experiment. (orig.)
Vyas, Akondi; Prasad, B Raghavendra
2010-01-01
We present the details of predicting atmospheric turbulence by mining Zernike moment data obtained from simulations as well as experiments. Temporally correlated optical wave-fronts were simulated such that they followed Kolmogorov phase statistics. The wave-fronts reconstructed either by modal or zonal methods can be represented in terms of Zernike moments. The servo lag error in adaptive optics is minimized by predicting Zernike moments in the near future by using the data from the immediate past. It is shown statistically that the prediction accuracy depends on the number of past phase screens used for prediction and servo lag time scales. The algorithm is optimized in terms of these parameters for real time and efficient operation of the adaptive optics system. On an average, we report more than 3% improvement in the wave-front compensation after prediction. This analysis helps in optimizing the design parameters for sensing and correction in closed loop adaptive optics systems.
International Nuclear Information System (INIS)
Concentrations and organ distribution patterns of alpha-emitting isotopes of U (238U and 234U), Th (232Th, 230Th, and 228Th), and Pu (239,240Pu) were determined for beagle dogs of our colony. The dogs were exposed to environmental levels of U and Th isotopes through ingestion (food and water) and inhalation to stimulate environmental exposures of the general human population. The organ distribution patterns of these radionuclides in beagles are compared to patterns in humans to determine if it is appropriate to extrapolate organ content data from beagles to humans. The results indicated that approximately 80% of the U and Th accumulated in bone in both species. The organ content percentages of these radionuclides in soft tissues such as liver, kidney, etc. of both species were comparable. The human lung contained higher percentages of U and Th than the beagle lung, perhaps because the longer life span of humans resulted in a longer exposure time. If the U and Th content of dog lung is normalized to an exposure time of 58 y and 63 y, median ages of the U and Th study populations, respectively, the lung content for both species is comparable. The organ content of 239,240Pu in humans and beagles differed slightly. In the beagle, the liver contained more than 60%, and the skeleton contained less than 40% of the Pu body content. In humans, the liver contained approximately 37%, and the skeleton contained approximately 58% of the body content. This difference may have been dy content. This difference may have been due to differences in the mode of intake of Pu in each species or to differences in the chemical form of Pu. In general, the results suggest that the beagle may be an appropriate experimental animal from which to extrapolate data to humans with reference to the percentage of U, Th, and Pu found in the organs
Pottenger, Lynn H; Becker, Richard A; Moran, Elizabeth J; Swenberg, James A
2011-04-01
The report of an Expert Panel convened by the National Research Council (NRC) of the National Academy of Sciences (NAS), entitled Science and Decisions: Advancing Risk Assessment (National Research Council, 2009a), includes a recommendation to use, as a default approach, low-dose linear extrapolation for systemic toxicity. This recommendation represents a significant departure from long-standing risk assessment practices for non-cancer toxicity, where the most appropriate No Observed Adverse Effect Level (NOAEL) or Benchmark Dose (BMD) of the critical effect in the key study is selected, and then a "safe exposure" level is derived by applying uncertainty factors to account for dataset completeness, potential greater sensitivity of humans when compared with experimental animals, and for potential variability of sensitivity in humans. A workshop was held to "frame" issues raised by the NAS report that needed further study. Workshop objectives included the following: (1) identify the issues raised by the 2009 NRC report and discuss the extent to which existing science may (or may not) align with the NAS analyses and recommendations, and (2) identify/develop possible actions to assist in advancing deeper and broader considerations of some of the critical issues presented by the 2009 NAS Panel. Experts invited to this "Framing" Workshop encompassed a full spectrum of toxicology and risk assessment disciplines; in particular, expertise in molecular interactions and dose-response of biological systems were well represented. The recommendations developed at this Framing Workshop provide specific ideas on possible further steps to facilitate deeper and broader consideration of the issues underpinning dose-response extrapolation in the risk assessment of systemic toxicants. PMID:21256913
International Nuclear Information System (INIS)
This paper presents a method to carry out high intensity radiated field (HIRF) effect experiments by using injection as an equivalent substitute for electromagnetic radiation. In allusion to typical interconnected system, the equal response voltage on the equipment cable port is regarded as an equivalent basis of injection and radiation methods. The equivalent relation formula between injected voltage and radiated field is derived theoretically. The conditions needed for extrapolating injected voltage in HIRF are confirmed, and the extrapolation method is proposed. On the basis of the above research, the electromagnetic environment effect test new method combined injection with radiation for interconnected system is summarized. The typical nonlinear interconnected system is selected as equipment under test, and the single frequency continuous wave radiation and injection effect experiments are carried out separately. The test results indicate that the relation between radiated field and injected voltage is linear, and the equivalent injected voltage used to substitute HIRF can be obtained by linear extrapolation.
Application of Rossi-? method to the critical experiment
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The prompt neutron decay constant ? is measured with different loading by Rossi-? method. Relation formula between loading and ? can be given. The critical mass is also given from the formula with prompt neutron decay constant ?c at critical. The critical mass from formula with ?c is in better agreement with one of extrapolation and interpolation
Interpolation Method Needed for Numerical Uncertainty Analysis of Computational Fluid Dynamics
Groves, Curtis; Ilie, Marcel; Schallhorn, Paul
2014-01-01
Using Computational Fluid Dynamics (CFD) to predict a flow field is an approximation to the exact problem and uncertainties exist. There is a method to approximate the errors in CFD via Richardson's Extrapolation. This method is based off of progressive grid refinement. To estimate the errors in an unstructured grid, the analyst must interpolate between at least three grids. This paper describes a study to find an appropriate interpolation scheme that can be used in Richardson's extrapolation or other uncertainty method to approximate errors. Nomenclature
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Tynan Anna
2012-09-01
Full Text Available Abstract Background Male circumcision (MC has been shown to reduce the risk of HIV acquisition among heterosexual men, with WHO recommending MC as an essential component of comprehensive HIV prevention programs in high prevalence settings since 2007. While Papua New Guinea (PNG has a current prevalence of only 1%, the high rates of sexually transmissible diseases and the extensive, but unregulated, practice of penile cutting in PNG have led the National Department of Health (NDoH to consider introducing a MC program. Given public interest in circumcision even without active promotion by the NDoH, examining the potential health systems implications for MC without raising unrealistic expectations presents a number of methodological issues. In this study we examined health systems lessons learned from a national no-scalpel vasectomy (NSV program, and their implications for a future MC program in PNG. Methods Fourteen in-depth interviews were conducted with frontline health workers and key government officials involved in NSV programs in PNG over a 3-week period in February and March 2011. Documentary, organizational and policy analysis of HIV and vasectomy services was conducted and triangulated with the interviews. All interviews were digitally recorded and later transcribed. Application of the WHO six building blocks of a health system was applied and further thematic analysis was conducted on the data with assistance from the analysis software MAXQDA. Results Obstacles in funding pathways, inconsistent support by government departments, difficulties with staff retention and erratic delivery of training programs have resulted in mixed success of the national NSV program. Conclusions In an already vulnerable health system significant investment in training, resources and negotiation of clinical space will be required for an effective MC program. Focused leadership and open communication between provincial and national government, NGOs and community is necessary to assist in service sustainability. Ensuring clear policy and guidance across the entire sexual and reproductive health sector will provide opportunities to strengthen key areas of the health system.
Peterson, J. B., Jr.; Mann, M. J.; Sorrells, R. B., III; Sawyer, W. C.; Fuller, D. E.
1980-01-01
The results of calculations necessary to extrapolate performance data on an XB-70-1 wind tunnel model to full scale at Mach numbers from 0.76 to 2.53 are presented. The extrapolation was part of a joint program to evaluate performance prediction techniques for large flexible supersonic airplanes similar to a supersonic transport. The extrapolation procedure included: interpolation of the wind tunnel data at the specific conditions of the flight test points; determination of the drag increments to be applied to the wind tunnel data, such as spillage drag, boundary layer trip drag, and skin friction increments; and estimates of the drag items not represented on the wind tunnel model, such as bypass doors, roughness, protuberances, and leakage drag. In addition, estimates of the effects of flexibility of the airplane were determined.
On boundary conditions in lattice Boltzmann methods
International Nuclear Information System (INIS)
A lattice Boltzmann boundary condition for simulation of fluid flow using simple extrapolation is proposed. Numerical simulations, including two-dimensional Poiseuille flow, unsteady Couette flow, lid-driven square cavity flow, and flow over a column of cylinders for a range of Reynolds numbers, are carried out, showing that this scheme is of second order accuracy in space discretization. Applications of the method to other boundary conditions, including pressure condition and flux condition are discussed. copyright 1996 American Institute of Physics
On boundary conditions in lattice Boltzmann methods
Chen, Shiyi; Martínez, Daniel; Mei, Renwei
1996-09-01
A lattice Boltzmann boundary condition for simulation of fluid flow using simple extrapolation is proposed. Numerical simulations, including two-dimensional Poiseuille flow, unsteady Couette flow, lid-driven square cavity flow, and flow over a column of cylinders for a range of Reynolds numbers, are carried out, showing that this scheme is of second order accuracy in space discretization. Applications of the method to other boundary conditions, including pressure condition and flux condition are discussed.
Scientific Electronic Library Online (English)
Joel, Negin; Robert G, Cumming.
2010-11-01
Full Text Available SciELO Public Health | Language: English Abstract in spanish OBJETIVO: Cuantificar el número de casos y la prevalencia de la infección por el virus de la inmunodeficiencia humana (VIH) entre los adultos de mayor edad en el África subsahariana. MÉTODOS: Se han analizado los datos procedentes de las Encuestas demográficas y de salud (EDS). Aunque en estos estud [...] ios todas las mujeres entrevistadas son menores de 50 años, 18 de estas encuestas contenían datos sobre la infección por VIH en hombres con una edad igual o superior a los 50 años. Para calcular el porcentaje de adultos de mayor edad (es decir, personas de 50 o más años de edad) con positividad al VIH (VIH+), se extrapolaron los datos procedentes del Programa Conjunto de las Naciones Unidas sobre el VIH/SIDA sobre la cantidad estimada de personas con el VIH y sobre la prevalencia de la infección por este virus entre los adultos con edades comprendidas entre 15 y 49 años. RESULTADOS: En 2007, en el África subsahariana había unos 3 millones de personas de 50 años o mayores con el VIH. La prevalencia de la infección por el VIH en este grupo fue del 4,0%, en comparación con el 5,0% correspondiente al grupo con edades comprendidas entre 15 y 49 años. De la cantidad aproximada de 21 millones de personas > 15 años con VIH en el África subsahariana, el 14,3% tenía 50 años de edad o más. CONCLUSIÓN: Para poder reflejar mejor la mayor supervivencia de las personas con VIH y el envejecimiento de la población VIH+, se deben ampliar los indicadores de la prevalencia de la infección por el VIH, de manera que incluyan a las personas mayores de 49 años. Se sabe poco sobre la morbilidad asociada y el comportamiento sexual de los adultos VIH+ de mayor edad o acerca de los factores biológicos y culturales que aumentan el riesgo de transmisión. Los servicios relacionados con el VIH deben orientarse mejor para responder a las necesidades crecientes de los adultos de edad más avanzada que se ven afectados por esta enfermedad. Abstract in english OBJECTIVE: To quantify the number of cases and prevalence of human immunodeficiency virus (HIV) infection among older adults in sub-Saharan Africa. METHODS: We reviewed data from Demographic and Health Surveys (DHS). Although in these surveys all female respondents are [...] urveys contained data on HIV infection among men aged > 50 years. To estimate the percentage of older adults (i.e. people > 50 years of age) who were positive for HIV (HIV+), we extrapolated from data from the Joint United Nations Programme on HIV/AIDS on the estimated number of people living with HIV and on HIV infection prevalence among adults aged 15-49 years. FINDINGS: In 2007, approximately 3 million people aged > 50 years were living with HIV in sub-Saharan Africa. The prevalence of HIV infection in this group was 4.0%, compared with 5.0% among those aged 15-49 years. Of the approximately 21 million people in sub-Saharan Africa aged > 15 years that were HIV+, 14.3% were > 50 years old. CONCLUSION: To better reflect the longer survival of people living with HIV and the ageing of the HIV+ population, indicators of the prevalence of HIV infection should be expanded to include people > 49 years of age. Little is known about comorbidity and sexual behaviour among HIV+ older adults or about the biological and cultural factors that increase the risk of transmission. HIV services need to be better targeted to respond to the growing needs of older adults living with HIV.
Fast, simple method for the reduction of truncation artifacts in MR images
International Nuclear Information System (INIS)
The standard Fourier transform (FT) method of reconstruction provides fast, stable solutions to the MR inverse problem. However, when reconstructing images from limited data sets, the FT introduces significant truncation artifacts throughout the image. These artifacts may either obscure or mimic true pathologic features. The authors have therefore developed a method of data extrapolation for truncation artifact reduction. The algorithm is simple to use and is fast, involving only three FTs. Prominent features of the initial magnitude image are extracted, enhanced, and then used to extrapolate the original data, which can then be reconstructed using the standard FT. The algorithm does not require extensive computer modeling
International Nuclear Information System (INIS)
This letter is written in response to a paper in which the author discusses the inverse dose-rate dependence of oncogenic transformation by high-LET radiation. The author asserts that, as a consequence, the extrapolation of results from miners exposed to high levels of radon daughters could overestimate the risk due to environmental exposures. By using a model increased cell sensitivity in one part of the cell cycle, the author assumes an inverse dose-rate effect should occur only at high doses, but the author of this letter points out that this does not imply a lower risk per unit dose at low doses. According to this letter, the existence of an inverse dose-rate effect for high-LET radiation provides no grounds for projecting lower lung cancer risks per unit exposure at environmental radon levels than at the higher radon level in mines. Failure to adjust for any inverse dose-rate effect in the studies of miners can only lead to an underestimation of the environmental risk
Scientific Electronic Library Online (English)
Jorge A, Calderón; Carmen P, Buitrago.
2007-12-01
Full Text Available La corrosión de recipientes fabricados en hojalata expuestos a diferentes soluciones fue evaluada usando técnicas eletroquímicas. Los recipientes con y sin la aplicación de barniz fueron expuestos a diferentes soluciones. La susceptibilidad a sufrir corrosión se evaluó utilizando voltametría cíclica [...] , curvas de polarización y espectroscopia de impedancia electroquímica. La posibilidad de formación de películas pasivas en la superfi cie de los recipientes se evaluó según la histéresis presente en el primer ciclo de las medidas de voltametría. Las curvas de polarización revelaron que el comportamiento del recubrimiento de estaño puede cambiar de anódico a catódico según la naturaleza de la solución en contacto con el recipiente, alertando sobre el riesgo de corrosión localizada. Mediante impedancia electroquímica se evaluó el efecto del uso de un aditivo en las soluciones o productos empacados en dos recipientes. Las medidas de impedancia mostraron un efecto perjudicial del aditivo utilizado y una rápida aparición de procesos corrosivos cuando se usó la solución modifi cada con el aditivo. Abstract in english Corrosion of lacquered tinplate cans in different solutions was assessed using electrochemical methods. Samples with and without lacquer coating were exposed to different solutions and their susceptibility to corrosion was evaluated using cyclic voltammetry, Tafel curves and electrochemical impedanc [...] e spectroscopy. The possible formation of a passive layer on the container surface was evaluated according to the kind of hysteresis presented in the fi rst cycle of voltammeter measurements. Tafel plots showed how the behaviour of the tin layer can change from anodic to cathodic depending on the nature of the solution in contact with it, revealing the risk of localized corrosion. The effect of one additive in the solutions on the electrochemical performance containers was evaluated by electrochemical impedance. The impedance showed a deleterious effect of the additive, and corrosion processes appeared more quickly in containers packed with solutions modifi ed with additive.
CORRECTING ACCOUNTING RESULTS OF TENSIONS USING FEM BY HSS METHOD
Directory of Open Access Journals (Sweden)
D. O. Bannikov
2011-05-01
Full Text Available The usage of the Hot Spot Stress (HSS method by means of linear surface extrapolation (LSE approach was analyzed for the correction of results of the Finite-Element Method (FEM in case of singularity of stresses. The given examples of structures and testing examples were computed on the base of design-and-computation software SCAD for Windows (version 11.3.
Lang, M; Vain, A; Bunce, R G H; Jongman, R H G; Raet, J; Sepp, K; Kuusemets, V; Kikas, T; Liba, N
2015-03-01
Habitat surveillance and subsequent monitoring at a national level is usually carried out by recording data from in situ sample sites located according to predefined strata. This paper describes the application of remote sensing to the extension of such field data recorded in 1-km squares to adjacent squares, in order to increase sample number without further field visits. Habitats were mapped in eight central squares in northeast Estonia in 2010 using a standardized recording procedure. Around one of the squares, a special study site was established which consisted of the central square and eight surrounding squares. A Landsat-7 Enhanced Thematic Mapper Plus (ETM+) image was used for correlation with in situ data. An airborne light detection and ranging (lidar) vegetation height map was also included in the classification. A series of tests were carried out by including the lidar data and contrasting analytical techniques, which are described in detail in the paper. Training accuracy in the central square varied from 75 to 100 %. In the extrapolation procedure to the surrounding squares, accuracy varied from 53.1 to 63.1 %, which improved by 10 % with the inclusion of lidar data. The reasons for this relatively low classification accuracy were mainly inherent variability in the spectral signatures of habitats but also differences between the dates of imagery acquisition and field sampling. Improvements could therefore be made by better synchronization of the field survey and image acquisition as well as by dividing general habitat categories (GHCs) into units which are more likely to have similar spectral signatures. However, the increase in the number of sample kilometre squares compensates for the loss of accuracy in the measurements of individual squares. The methodology can be applied in other studies as the procedures used are readily available. PMID:25648761
International Nuclear Information System (INIS)
The paper presents the main characteristics of the plasma/implantation/recycling experiment been carried out at the IAM, JRC-Ispra. The modelling aspects for the case of deuterium bombardment in martensitic steel DIN 1.9141 (MANET) are detailed. Once verified that release is surface-limited the surface constants, recombination (K2) and dissociation (K1) constants are determined by fitting the experimental pressure due to the gas desorbed in the measuring chamber. The values obtained for the dissociation constant are: K1=7.10''-6 (mol.Pa''-1.m''-2.s''-1). The recombination constant K2 follows the Arrhenius law:?.K2=2.414* exp(-1571/RT) (m''4.mol''-1.s''-1), R=8.314 J.mol''-1. K''-1 (?:sticking factor). We have obtained quite high reflection coefficients (R>80%) in good agreement with other existing results and with the classical low-energy scattering theory. For temperatures ranging between: 300 and 600 K, ionic fluxes between: 2.10''20??(m''-2 s''-1)?1.10''21 and ion energies for D3 ''+ from 150 to 300 eV the obtained results for K2, K1 and R show a light dispersion. Activation energies for dissociation and recombination are comparable to those obtained from permeation experiments. The design of our experiment allows simple but accurate scale-extrapolations for the tracking of tritium at the First Wall of fusion reactor DEMO. Without taking into consideration other structura into consideration other structural phenomena (erosion. redeposition,...) having synergistic effects, the results obtained would minimise the negative impact of tritium related problems for the design of the First Wall of fusion reactor DEMO. (Author) 6 refs
Tafel, Külliki
2006-01-01
Äriühingute valitsemine postsotsialistlikes riikides - teoreetilised dilemmad, eripärad, uurimisvõimalused. Skeemid: Internal and external relations of corporate governanace; The changing context of corporate governance
The HBOM method for unfolding detector effects
Energy Technology Data Exchange (ETDEWEB)
Monk, J.W., E-mail: jmonk@cern.ch [Department of Physics and Astronomy, University College London, Gower Street, London, England (United Kingdom); Oropeza-Barrera, C., E-mail: cristina.oropeza.barrera@cern.ch [School of Physics and Astronomy, University of Glasgow, Glasgow, Scotland (United Kingdom)
2013-02-11
We present the Hit Backspace Once More (HBOM) method for correcting a measurement for the effect of an imperfect detector. The HBOM method is a model-independent and potentially data-driven technique that repeatedly applies a parameterisation of the detector effects to observed data. The correction is determined, after applying the detector parameterisation, by extrapolating the data to a detector effect of zero. We demonstrate this technique using the two particle correlation function, which is an observable that can otherwise be difficult to correct for systematic shifts introduced by the detector.
The HBOM method for unfolding detector effects
International Nuclear Information System (INIS)
We present the Hit Backspace Once More (HBOM) method for correcting a measurement for the effect of an imperfect detector. The HBOM method is a model-independent and potentially data-driven technique that repeatedly applies a parameterisation of the detector effects to observed data. The correction is determined, after applying the detector parameterisation, by extrapolating the data to a detector effect of zero. We demonstrate this technique using the two particle correlation function, which is an observable that can otherwise be difficult to correct for systematic shifts introduced by the detector.
Production and characterization of TI/PbO2 electrodes by a thermal-electrochemical method
Directory of Open Access Journals (Sweden)
Laurindo Edison A.
2000-01-01
Full Text Available Looking for electrodes with a high overpotential for the oxygen evolution reaction (OER, useful for the oxidation of organic pollutants, Ti/PbO2 electrodes were prepared by a thermal-electrochemical method and their performance was compared with that of electrodeposited electrodes. The open-circuit potential for these electrodes in 0.5 mol L-1 H2SO4 presented quite stable similar values. X-ray diffraction analyses showed the thermal-electrochemical oxide to be a mixture of ort-PbO, tetr-PbO and ort-PbO2. On the other hand, the electrodes obtained by electrodeposition were in the tetr-PbO2 form. Analyses by scanning electron microscopy showed that the basic morphology of the thermal-electrochemical PbO2 is determined in the thermal step, being quite distinct from that of the electrodeposited electrodes. Polarization curves in 0.5 mol L-1 H2SO4 showed that in the case of the thermal-electrochemical PbO2 electrodes the OER was shifted to more positive potentials. However, the values of the Tafel slopes, quite high, indicate that passivating films were possibly formed on the Ti substrates, which could eventually explain the somewhat low current values for OER.
International Nuclear Information System (INIS)
NECD Method and runge-Kutta method for large system of second order ordinary differential equations in comparing algorithm. The paper introduce a extrapolation method used for solving the large system of second order ordinary differential equation. We call this method the modified extrapolated central difference (MECD) method. for the accuracy and efficiency MECD method. we compare the method with 4-th order runge-Kutta method. The comparison results show that, this method has almost the same accuracy as the 4-th order runge-Kutta method, but the computation time is about half of runge-Kutta. The MECD was declare by the author and Tetsuhiko Miyoshi of the Dept. Applied Science Yamaguchi University Japan
Concepts and Methods in the Cross-Cultural Study of Personality Development.
Holtzman, W. H.
1979-01-01
Reviews the research methods, design, and main findings of the Austin-Mexico City cross-cultural study of personality and intellectual development using an overlapping longitudinal design. A span of 12 years of development was extrapolated from six years of repeated testing with children ages 6, 9, and 12 years. (SS)
Extending the charge-flipping method towards structure solution from incomplete data sets.
Czech Academy of Sciences Publication Activity Database
Palatinus, Lukáš; Steurer, W.; Chapuis, G.
2007-01-01
Ro?. 40, - (2007), s. 456-462. ISSN 0021-8898 Institutional research plan: CEZ:AV0Z10100521 Keywords : ab initio structure solution * density modification * maximum entropy method * intensity extrapolation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.629, year: 2007
Report on the uncertainty methods study
International Nuclear Information System (INIS)
The Uncertainty Methods Study (UMS) Group, following a mandate from CSNI, has compared five methods for calculating the uncertainty in the predictions of advanced 'best estimate' thermal-hydraulic codes: the Pisa method (based on extrapolation from integral experiments) and four methods identifying and combining input uncertainties. Three of these, the GRS, IPSN and ENUSA methods, use subjective probability distributions, and one, the AEAT method, performs a bounding analysis. Each method has been used to calculate the uncertainty in specified parameters for the LSTF SB-CL-18 5% cold leg small break LOCA experiment in the ROSA-IV Large Scale Test Facility (LSTF). The uncertainty analysis was conducted essentially blind and the participants did not use experimental measurements from the test as input apart from initial and boundary conditions. Participants calculated uncertainty ranges for experimental parameters including pressurizer pressure, primary circuit inventory and clad temperature (at a specified position) as functions of time
Copper corrosion inhibition in O{sub 2}-saturated H{sub 2}SO{sub 4} solutions
Energy Technology Data Exchange (ETDEWEB)
Amin, Mohammed A. [Materials and Corrosion Lab (MCL), Department of Chemistry, Faculty of Science, Taif University, 888 Hawiya, KSA (Egypt); Chemistry Department, Faculty of Science, Ain Shams University, Abbassia, Cairo (Egypt)], E-mail: maaismail@yahoo.com; Khaled, K.F. [Materials and Corrosion Lab (MCL), Department of Chemistry, Faculty of Science, Taif University, 888 Hawiya, KSA (Egypt); Electrochemistry Research Laboratory, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt)
2010-04-15
Corrosion inhibition of copper in O{sub 2}-saturated 0.50 M H{sub 2}SO{sub 4} solutions by four selected amino acids, namely glycine (Gly), alanine (Ala), valine (Val), or tyrosine (Tyr), was studied using Tafel polarization, linear polarization, impedance, and electrochemical frequency modulation (EFM) at 30 deg. C. Protection efficiencies of almost 98% and 91% were obtained with 50 mM Tyr and Gly, respectively. On the other hand, Ala and Val reached only about 75%. Corrosion rates determined by the Tafel extrapolation method were in good agreement with those obtained by EFM and an independent chemical (i.e., non-electrochemical) method. The chemical method of confirmation of the corrosion rates involved determination of the dissolved Cu{sup 2+}, using ICP-AES (inductively coupled plasma atomic emission spectrometry) method of chemical analysis. Nyquist plots exhibited a high frequency depressed semicircle followed by a straight line portion (Warburg diffusion tail) in the low-frequency region. The impedance data were interpreted according to two suitable equivalent circuits. The kinetics of dissolved O{sub 2} reduction and hydrogen evolution reactions on copper surface were also studied in O{sub 2}-saturated 0.50 M H{sub 2}SO{sub 4} solutions using polarization measurements combined with the rotating disc electrode (RDE). The Koutecky-Levich plot indicated that the dissolved O{sub 2} reduction at the copper electrode was an apparent 4-electron process.
Splitting methods for Levitron Problems
Geiser, Juergen
2012-01-01
In this paper we describe splitting methods for solving Levitron, which is motivated to simulate magnetostatic traps of neutral atoms or ion traps. The idea is to levitate a magnetic spinning top in the air repelled by a base magnet. The main problem is the stability of the reduced Hamiltonian, while it is not defined at the relative equilibrium. Here it is important to derive stable numerical schemes with high accuracy. For the numerical studies, we propose novel splitting schemes and analyze their behavior. We deal with a Verlet integrator and improve its accuracy with iterative and extrapolation ideas. Such a Hamiltonian splitting method, can be seen as geometric integrator and saves computational time while decoupling the full equation system. Experiments based on the Levitron model are discussed.
Quick Method for Determining Plant Available Water
International Nuclear Information System (INIS)
For the first few days after heavy rain or irrigations, water drains from the soil profile until its water content approaches a relatively stable value called the drained upper limit or field capacity. When plants have extracted all of the water available to them, the root zone water content approaches a lower limit of available water, or permanent wilting water content. The water held by the soil between these two limits is called plant available water. These two limits are often associated with water content values at specific soil water potentials, (a measure of pressure at soil water is extracted). Field capacity is often taken as the water content of a soil at -33 kPa water potential. Permanent wilt is taken as the water content at -1500 kPa. The methods typically used to determine plant available water are slow and inaccurate. We present here (1) a method for measuring field capacity using a tensiometer and an extrapolation technique, and (2) a method for measuring permanent wilting water content with a dew point potentiameter and an extrapolation method which are much faster and more accurate than traditional methods. (author)
Forecasting international bandwidth capacity using linear and ANN methods
Madden, Gary G.; Tan, Joachim
2008-01-01
An artificial neural network (ANN) can improve forecasts through pattern recognition of historical data. This article evaluates the reliability of ANN methods, as opposed to simple extrapolation techniques, to forecast Internet bandwidth index data that is bursty in nature. A simple feedforward ANN model is selected as a nonlinear alternative, as it is flexible enough to model complex linear or nonlinear relationships without any prior assumptions about the data generating process. These d...
On the equivalence of LIST and DIIS methods for convergence acceleration
Garza, Alejandro J
2014-01-01
Self-consistent field extrapolation methods play a pivotal role in quantum chemistry and electronic structure theory. We here demonstrate the mathematical equivalence between the recently proposed family of LIST methods [J. Chem. Phys. 134, 241103 (2011); J. Chem. Theory Comput. 7, 3045 (2011)] with Pulay's DIIS [Chem. Phys. Lett. 73, 393 (1980)]. Our results also explain the differences in performance among the various LIST methods.
An empirical method to correlate and predict solute distribution in ternary liquid-liquid systems
Scientific Electronic Library Online (English)
J.M., Zamaro; E.A., Campanella.
2002-07-01
Full Text Available SciELO Brazil | Language: English Abstract in english This paper presents a method that combines activity coefficient models with Hand's equation for tie lines. The proposed method calculates solute distribution in liquid-liquid ternary systems. The combination improves the calculated solute distributions using activity coefficient models while Hand's [...] equation gives a good correlation of the experimental tie lines. The method could be used to extrapolate experimental information.
Comparative study among calibration methods of clinical applicators of beta radiation
International Nuclear Information System (INIS)
90Sr+90Y clinical applicators are instruments used in brachytherapy procedures and they have to be periodically calibrated, according to international standards and recommendations. In this work, four calibration methods of dermatological and ophthalmic applicators were studied, comparing the results with those given by the calibration certificates of the manufacturers. The methods included the use of the standard applicator of the Calibration Laboratory (LCI), calibrated by the National Institute of Standards and Technology; an Amersham applicator (LCI) as reference; a mini-extrapolation chamber developed at LCI as an absolute standard; and thermoluminescent dosimetry. The mini-extrapolation chamber and a PTW commercial extrapolation chamber were studied in relation to their performance through quality control tests of their response, as leakage current, repeatability and reproducibility. The distribution of the depth dose in water, that presents high importance in dosimetry of clinical applicators, was determined using the mini extrapolation chamber and the thermoluminescent dosimeters. The results obtained were considered satisfactory for the both cases, and comparable to the data of the IAEA (2002) standard. Furthermore, a dosimetry postal kit was developed for the calibration of clinical applicators using the thermoluminescent technique, to be sent to clinics and hospitals, without the need of the transport of the sources to IPEN for calibration. (author)
Energy Technology Data Exchange (ETDEWEB)
Castillo, Jhonny Antonio Benavente
2011-07-01
The metrological coherence among standard systems is a requirement for assuring the reliability of dosimetric quantities measurements in ionizing radiation field. Scientific and technologic improvements happened in beta radiation metrology with the installment of the new beta secondary standard BSS2 in Brazil and with the adoption of the internationally recommended beta reference radiations. The Dosimeter Calibration Laboratory of the Development Center for Nuclear Technology (LCD/CDTN), in Belo Horizonte, implemented the BSS2 and methodologies are investigated for characterizing the beta radiation fields by determining the field homogeneity, the accuracy and uncertainties in the absorbed dose in air measurements. In this work, a methodology to be used for verifying the metrological coherence among beta radiation fields in standard systems was investigated; an extrapolation chamber and radiochromic films were used and measurements were done in terms of absorbed dose in air. The reliability of both the extrapolation chamber and the radiochromic film was confirmed and their calibrations were done in the LCD/CDTN in {sup 90}Sr/{sup 90}Y, {sup 85}Kr and {sup 147}Pm beta radiation fields. The angular coefficients of the extrapolation curves were determined with the chamber; the field mapping and homogeneity were obtained from dose profiles and isodose with the radiochromic films. A preliminary comparison between the LCD/CDTN and the Instrument Calibration Laboratory of the Nuclear and Energy Research Institute / Sao Paulo (LCI/IPEN) was carried out. Results with the extrapolation chamber measurements showed in terms of absorbed dose in air rates showed differences between both laboratories up to de -I % e 3%, for {sup 90}Sr/{sup 90}Y, {sup 85}Kr and {sup 147}Pm beta radiation fields, respectively. Results with the EBT radiochromic films for 0.1, 0.3 and 0.15 Gy absorbed dose in air, for the same beta radiation fields, showed differences up to 3%, -9% and -53%. The beta radiation field mappings with radiochromic films in both BSS2 showed that some of them were not geometrically aligned. (author)
Summary of existing uncertainty methods
International Nuclear Information System (INIS)
A summary of existing and most used uncertainty methods is presented, and the main features are compared. One of these methods is the order statistics method based on Wilks' formula. It is applied in safety research as well as in licensing. This method has been first proposed by GRS for use in deterministic safety analysis, and is now used by many organisations world-wide. Its advantage is that the number of potential uncertain input and output parameters is not limited to a small number. Such a limitation was necessary for the first demonstration of the Code Scaling Applicability Uncertainty Method (CSAU) by the United States Regulatory Commission (USNRC). They did not apply Wilks' formula in their statistical method propagating input uncertainties to obtain the uncertainty of a single output variable, like peak cladding temperature. A Phenomena Identification and Ranking Table (PIRT) was set up in order to limit the number of uncertain input parameters, and consequently, the number of calculations to be performed. Another purpose of such a PIRT process is to identify the most important physical phenomena which a computer code should be suitable to calculate. The validation of the code should be focused on the identified phenomena. Response surfaces are used in some applications replacing the computer code for performing a high number of calculations. The second well known uncertainty method is the Uncertainty Methodology Based on Accuracy Extrapolation (UMAE) and the follow-up method 'Code with the Capability of Internal Assessment of Uncertainty (CIAU)' developed by the University Pisa. Unlike the statistical approaches, the CIAU does compare experimental data with calculation results. It does not consider uncertain input parameters. Therefore, the CIAU is highly dependent on the experimental database. The accuracy gained from the comparison between experimental data and calculated results are extrapolated to obtain the uncertainty of the system code predictions for a nuclear power plant. A high effort is needed to provide the data base for deviations between experiment and calculation results in CIAU. That time and resource consuming process has been performed only by University of Pisa for the codes CATHARE and RELAP5 up to now. The data base is available only there. That is the reason why this method is only used by University of Pisa. (author)
The direct current method for measuring charged membrane conductance
International Nuclear Information System (INIS)
This paper deals with a method for measuring electrical resistance in charged membranes. The method is based on the application of a step change in direct current and on the analysis of the potential transient subsequent to the application of the current step. Membrane electrical resistance was determined by an extrapolation to zero time of potential differences measured after the current step. Experimental results obtained with commercial ion-exchange membranes were in good agreement with those computed from the Fick equation. The method developed gives more accurate values with a standard deviation lower than traditional techniques and allows the resistance of an asymmetrical membrane to be determined in both current directions. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Rodrigues, Josianne L.; Silva, Paulo R.O.; Santos, Raquel G.; Ferreira, Andrea V., E-mail: jlr@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)
2011-07-01
Thiosemicarbazones have attracted great pharmacological interest because of their biological properties, such as cytotoxic activity against multiple strains of human tumors. Due to the excellent properties of {sup 64}Cu, the copper complex N(4)-ortho-toluyl-2-acetylpyridine thiosemicarbazone (({sup 64}Cu)(H2Ac4oT)Cl) was developed for tumor detection by positron emission tomography. The radiopharmaceuticals were produced in the nuclear reactor TRIGA-IPR-R1 from CDTN. At the present work, ({sup 64}Cu)(H2Ac4oT)Cl biokinetic data (evaluated in mice bearing Ehrlich tumor) were treated by MIRD formalism to perform Internal Dosimetry studies. Doses in several organs of mice were determinate, as well as in implanted tumor, for ({sup 64}Cu)(H2Ac4oT)Cl. Doses results obtained for animal model were extrapolated to humans assuming a similar concentration ratio among various tissues between mouse and human. In the extrapolation, it was used human organ masses from Cristy/Eckerman phantom. Both penetrating and non-penetrating radiation from {sup 64}Cu in the tissue were considered in dose calculations. (author)
International Nuclear Information System (INIS)
The basic methods of the determination of asymptotic normalization coefficient for A+a?B of astrophysical interest are briefly presented. The results of the application of the specific asymptotic normalization coefficients derived within these methods for the extrapolation of the astrophysical S factors to experimentally inaccessible energy regions (E ? 25 keV) for the some specific radiative capture A(a,?)B reactions of the pp-chain and the CNO cycle are presented
The use of objects and methods of colloid chemistry in nanochemistry
Summ, Boris D.; Ivanova, Nina I.
2000-11-01
Experimental methods and theoretical concepts of colloid chemistry regarding their possible use in nanochemistry and nanotechnology are considered. The main types of disperse systems which can be regarded as nanosystems are distinguished. Some methods for the preparation of colloidal nanosystems are described. Conditions for extrapolation of phenomenological laws of colloid chemistry to nanosize objects are considered. Examples of self-organised colloidal structures are given. The bibliography includes 205 references.
International Nuclear Information System (INIS)
A simple method has been developed for determining the immunoreactivity of radiolabelled monoclonal antibodies to the TAG-72 antigen. The method involves binding of a constant small amount of the antibody to increasing concentrations of bovine submaxillary mucin. The immunoreactive fraction (IRF) is then determined by linear extrapolation of binding to infinite antigen excess. Using this assay, the IRF of radioiodinated anti-TAG-72 antibodies ranged from 0.22-0.48. (author)
Virtual Power Extraction Method of Designing Starting Control Law of Turbofan Engine
Yuchun Chen; Yiming Zhang; Fu Hu; Siyuan Xu; Qiuye Tu
2009-01-01
Virtual power extraction method (VPEM) of designing starting control law of turbofan engine was presented, and the computer program was developed. The VPEM of designing starting control law is based on the principle of VPEM of designing acceleration control law of turbofan engine, and combined with the method of extrapolation of component maps. The starting control law of some turbofan engine at single flight state and in whole starting envelope was designed by using the program, some computi...
Mechanical Properties and Corrosion Behavior of Low Carbon Steel Weldments
Directory of Open Access Journals (Sweden)
Mohamed Mahdy
2013-01-01
Full Text Available This research involves studying the mechanical properties and corrosion behavior of ?low carbon steel? (0.077wt% C before and after welding using Arc, MIG and TIG welding. The mechanical properties include testing of microhardness, tensile strength, the results indicate that microhardness of TIG, MIG welding is more than arc welding, while tensile strength in arc welding more than TIG and MIG.The corrosion behavior of low carbon weldments was performed by potentiostat at scan rate 3mV.sec-1 in 3.5% NaCl to show the polarization resistance and calculate the corrosion rate from data of linear polarization by ?Tafel extrapolation method?. The results indicate that the TIG welding increase the corrosion current density and anodic Tafel slop, while decrease the polarization resistance compared with unwelded low carbon steel. Cyclic polarization were measured to show resistance of specimens to pitting corrosion and to calculate the forward and reveres potentials. The results show shifting the forward, reverse and pitting potentials toward active direction for weldments samples compared with unwelded sample.
Preparation of ultrafine tungsten wire via electrochemical method in an ionic liquid
International Nuclear Information System (INIS)
Highlights: ? The method of electrochemical corrosion is used to prepare ultra-fine tungsten wire less than 10 ?m in diameter. ? Ionic liquid as a non-aqueous electrolyte was used in electrochemical corrosion experiments. ? The situation of anode polarization was different from the usual situation. ? Diameter of tungsten wire has been cut down to 8.5 ?m uniformly under the optimized electric potential. - Abstract: Ultrafine tungsten wire less than 10 ?m in diameter is often used as wire array load applied in Inertial Confinement Fusion (ICF) physical experiments. In order to obtain a higher yield of X-ray, both initial radius and line quality of metal wire were required to be of high quality simultaneously. This paper has studied the electrochemical method to corrode tungsten wires uniformly in an ionic liquid electrolyte containing 1 wt% sodium hydroxide. A three electrode system composed of a tungsten anode electrode, a stainless steel cathode and a saturated calomel electrode as a reference electrode, was used in the electrochemical experiments. Liner sweep voltammetry (LSV) and Tafel experiments were used to investigate the electrochemical behaviors of tungsten wires in ionic liquid and aqueous solution. Based on scanning electron microscope (SEM) observation, the morphologies of tungsten wire surface with uniform corrosion under different applied voltages have been demonstrated. X-ray diffraction (XRD) methods were employed to track the evolution of thed to track the evolution of the crystal structure before and after corrosions, and there is an obvious difference in peak intensities. The ultrafine tungsten wire with a uniform diameter of 8.5 ?m was obtained under the optimized electric potential (2.5 V) applied for decreasing diameter at 30 °C.
International Nuclear Information System (INIS)
X-ray diffraction, Raman spectroscopy and Optical absorption estimates of the thickness of graphene multi layer stacks (number of graphene layers) are presented for three different growth techniques. The objective of this work was focused on comparison and reconciliation of the two already widely used methods for thickness estimates (Raman and Absorption) with the calibration of the X-ray method as far as Scherer constant K is concerned and X-ray based Wagner-Aqua extrapolation method
Full scale assessment of pansharpening methods and data products
Aiazzi, B.; Alparone, L.; Baronti, S.; Carlà, R.; Garzelli, A.; Santurri, L.
2014-10-01
Quality assessment of pansharpened images is traditionally carried out either at degraded spatial scale by checking the synthesis property ofWald's protocol or at the full spatial scale by separately checking the spectral and spatial consistencies. The spatial distortion of the QNR protocol and the spectral distortion of Khan's protocol may be combined into a unique quality index, referred to as hybrid QNR (HQNR), that is calculated at full scale. Alternatively, multiscale measurements of indices requiring a reference, like SAM, ERGAS and Q4, may be extrapolated to yield a quality measurement at the full scale of the fusion product, where a reference does not exist. Experiments on simulated P?eiades data, of which reference originals at full scale are available, highlight that quadratic polynomials having three-point support, i.e. fitting three measurements at as many progressively doubled scales, are adequate. Q4 is more suitable for extrapolation than ERGAS and SAM. The Q4 value predicted from multiscale measurements and the Q4 value measured at full scale thanks to the reference original, differ by very few percents for six different state-of-the-art methods that have been compared. HQNR is substantially comparable to the extrapolated Q4.
Energy Technology Data Exchange (ETDEWEB)
Amin, Mohammed A., E-mail: maaismail@yahoo.co [Department of Chemistry, Faculty of Science, Ain Shams University, 11566 Abbassia, Cairo (Egypt); Materials and Corrosion Lab (MCL), Chemistry Department, Faculty of Science, Taif University, 888 Hawiya (Saudi Arabia)
2010-10-15
A newly synthesized glycine derivative (termed GlyD), 2-(4-(dimethylamino)benzylamino)acetic acid hydrochloride, was used to inhibit uniform and pitting corrosion processes of Al in 0.50 M KSCN solutions (pH 6.8) at 25 {sup o}C. For uniform corrosion inhibition study, Tafel extrapolation, linear polarization resistance and impedance methods were used, complemented with SEM examinations. 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. GlyD inhibited uniform corrosion, even at low concentrations, reaching a value of inhibition efficiency up to 97% at a concentration of 5 x 10{sup -3} M. Results obtained from the different corrosion evaluation techniques were in good agreement. This new synthesized glycine derivative was also used to control pit nucleation and growth on the pitted Al surface based on cyclic polarization, potentiostatic and galvanostatic measurements. The pitting potential (E{sub pit}) and the repassivation potential (E{sub rp}) increased by the addition of GlyD. Thus GlyD suppressed pit nucleation and propagation. Nucleation of pit was found to take place after an incubation time (t{sub i}). The rate of pit nucleation and growth decreased with increase in inhibitor concentration. Morphology of pitting was also studied as a function of the applied anodic potential and solution temperature. Cross-sectional view of pitted surface revealed the formation of large distorted hemispherical and narrow deep pits. GlyD was much better than Gly in controlling uniform and pitting corrosion processes of Al in these solutions.
Dissolution of chromium in sulfuric acid
Directory of Open Access Journals (Sweden)
J. P. POPIC
2002-11-01
Full Text Available By combining electrochemical corrosion rate measurements and spectrophotometric analysis of the electrolyte it was shown that at room temperature chromium dissolves in deaerated 0.1 M Na2SO4 + H2SO4 (pH 1 solution as Cr(II and Cr(III ions in he ratio Cr(II : Cr(III @ 7 : 1. This process was stable over 4 h without any detectable change. The total corrosion rate of chromium calculated from the analytical data is about 12 times higher, than that determined electrochemically by cathodic Tafel line extrapolation to the corrosion potential. This finding was confirmed by applying the weight-loss method for the determination of the corrosion rate. This enormous difference between these experimentally determined corrosion rates can be explained by the rather fast, ?anomalous? dissolution process proposed by Kolotyrkin and coworkers (chemical reaction of Cr with H2O molecules occurring simultaneously with the electrochemical corrosion process.
International Nuclear Information System (INIS)
The effect of small addition of Al on the electrochemical performances was investigated by open circuit potential and Tafel Extrapolation method. The results show that open circuit potential reveals as-cast Mg containing Ca alloys with minor content of Al maintained highly negative potential with the range of -1.68 to -1.63 VSCE in comparison to both pure Mg (-1.60VSCE) and commercial high potential Mg content. Corrosion rate for the as-cast samples remains higher (30-17 mpy) than pure Mg (3 mpy) and commercial high potential Mg anode (14 mpy). The increasing small content of Al results in the reduction of corrosion rate significantly. Therefore, it proves that the performance of Mg containing Ca alloy is strongly influenced by the concentration of Al. (author)
Mutlu, Ilven
2014-07-01
Highly porous Ti-Cu alloy foams were produced by powder metallurgy method for implant applications. Ti-Cu alloys were prepared with 3, 5, 7, and 10 wt pct Cu contents in order to determine optimum Cu addition. Cu addition enhances sinterability, and the Ti-Cu compacts were sintered at lower temperatures and times than pure Ti. Specimens were coated with a TiN film to enhance wear and corrosion resistance. Sintered specimens were precipitation hardened (aged) in order to increase mechanical properties. Corrosion properties of foams were examined by electrochemical techniques, such as potentiodynamic polarization, cyclic polarization, Tafel extrapolation, linear polarization resistance, and open-circuit potential measurement. Effect of Cu content, TiN coating, pH, and fluoride content of artificial saliva on electrochemical corrosion behavior of specimens was investigated.
Bambynek, M
2002-01-01
The prototype of a primary standard has been developed, built and tested, which enables the realization of the unit of the absorbed dose to water for beta brachytherapy sources. In the course of the development of the prototype, the recommendations of the American Association of Physicists in Medicine (AAPM) Task Group 60 (TG60) and the Deutsche Gesellschaft fuer Medizinische Physik (DGMP) Arbeitskreis 18 (AK18) were taken into account. The prototype is based on a new multi-electrode extrapolation chamber (MEC) which meets, in particular, the requirements on high spatial resolution and small uncertainty. The central part of the MEC is a segmented collecting electrode which was manufactured in the clean room center of PTB by means of electron beam lithography on a wafer. A precise displacement device consisting of three piezoelectric macrotranslators has been incorporated to move the wafer collecting electrode against the entrance window. For adjustment of the wafer collecting electrode parallel to the entranc...
Effects of lump characteristics on plutonium self absorption correction methods
International Nuclear Information System (INIS)
An evaluation study has been undertaken to assess the robustness of several published Pu self-absorption correction methods against variation in size, shape, density etc. for use in the gamma assay of nuclear waste. The correction methods studied are a numerical plutonium self absorption correction (PuSAC) technique, the Fleissner 2-line, Fleissner 3-line and Infinite Energy Extrapolation methods with both linear and polynomial extrapolation to 1/E=0. The performance of these methods has been compared for a limited set of measured encapsulated PuO2 sources plus a range of modelled unencapsulated Pu lumps. An indication of the magnitude of the uncertainties of the numerical PuSAC method has been determined for cases of blind assays where the Pu material, shape and distribution are unknown with the aim of ultimately applying it to real waste. The importance of the range of Pu lumps used in the baseline modelled dataset has been examined. Data are presented to illustrate how the uncertainties in the method are affected by the shape, composition, density, number and mass distribution of Pu particles in a sample for a given modelled base dataset. (authors)
Internal Error Propagation in Explicit Runge--Kutta Methods
Ketcheson, David I.
2014-09-11
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.
Interpolation methods and their use in radiation protection
International Nuclear Information System (INIS)
The presentation summarizes results of using various interpolation methods for getting spatial data from point measurements. These methods were evaluated within the State Office for Nuclear Safety (SONS) Science and Research Project No. 2/2008 'Methods and Measures to Limit Generation and Liquidation of Consequences of Radioactive Matter Misuse by Terrorists'. Several field tests in which the short life-time radioactive matter was released by explosion were realized and the measured data were processed. The essential goal is to find the most realistic method for radiation events assessment. Within the research project, three methods were used: Multilevel B-Spline, Triangulation and Kriging, using freely available SAGA GIS software. The best solution for this sort of radiation events appears to be the Multilevel B-Spline method. It is quick and produces good quality output data comparable with the much slower Kriging method and allows extrapolation in contrast to Triangulation. (author)
Voortman, B.; Bartholomeus, R.; Witte, J. M.
2012-12-01
Lysimeters are often used to measure evapotranspiration (Et) by changes in mass of a volume of soil. Precision lysimeters generate data of Et at a high resolution in the order of 0.02 to 0.05 mm. This resolution is often reported as the accuracy of the lysimeter, which is in fact the accuracy of the weighing device. Improper installation or design of lysimeters is often not accounted for when assessing their accuracy. In general, measurement errors due to improper environmental conditions will decrease with increasing surface area and depth of the lysimeter. This is primarily because a larger part of the lysimeter is unaffected by its boundaries and because heterogeneities in soil hydraulic properties and micro-climate are more averaged out. However, the cost of large systems make them unattractive and scientists often choose for more economical solutions, optimizing between lysimeter dimensions and costs. One of the difficulties when designing a lysimeter is controlling the boundary condition at the base of the lysimeter. In case of a freely draining lysimeter (atmospheric pressure at the bottom), the lower portion of the lysimeter must saturate to generate a hydraulic gradient in downward direction, after which the lysimeter starts to drain. In groundwater independent sites this will lead to a higher soil moisture content in the lysimeter in comparison with the surrounding soil. One could overcome this problem by using suction plates and vacuum pumps to set a suction level at the base of the lysimeter equal to the surrounding soil., In dry soils, however, suction plates may dry out beyond the air entry value of the ceramic material, which neutralizes the suction pressure. Furthermore, a sophisticated drainage system will increase the maintenance and construction cost of the lysimeter. Moisture conditions in lysimeters are difficult to control and whenever this affects the available water for rooting plants this will lead to erroneous measurements of Et. We developed a method to overcome the drawbacks of lysimeters by combining mini-lysimeters with ground-based remote sensing techniques. By comparison of the surface energy balance of the environment under study with the energy balance of mini-lysimeters we are able to derive the latent heat flux of the area outside the mini-lysimeters. The advantages of this method are that (1) measurements of evapotranspiration can be derived for much larger areas than most conventional lysimeters, (2) the measurements are not affected by the lysimeter design and (3) Et can be split into soil evaporation and transpiration, which allows us to study the effects of the vegetation structure on the water balance.
International Nuclear Information System (INIS)
The method is based on perturbation of the reactor cell from a few up to few tens of percent. Measurements were performed for square lattice calls of zero power reactors Anna, NORA and RB, with metal uranium and uranium oxide fuel elements, water, heavy water and graphite moderators. Character and functional dependence of perturbations were obtained from the experimental results. Zero perturbation was determined by extrapolation thus obtaining the real physical neutron flux distribution in the reactor cell. Simple diffusion theory for partial plate cell perturbation was developed for verification of the perturbation method. The results of these calculation proved that introducing the perturbation sample in the fuel results in flattening the thermal neutron density dependent on the amplitude of the applied perturbation. Extrapolation applied for perturbed distributions was found to be justified
Standardization of Y-90 by tracing method
International Nuclear Information System (INIS)
This paper describes the procedure followed by the Nuclear Metrology Laboratory (LMN) at IPEN - CNEN/SP, in Sao Paulo, Brazil, for the standardization of the 90Y, undertaken by the tracer technique using the 24Na beta-gamma emitter as the tracer. The measurements were carried out, by means of a 4???? coincidence system. For the observed events registration was used the TAC method. A Monte Carlo simulation for generating the extrapolation curve was applied to obtain the correction of the efficiency for determining the solution activity. The correction factor of the efficiency was also calculated by means of a semi-empirical formula. The 90Y activity results obtained by both methods were compared. (author)
Standardization of Y-90 by tracing method
Energy Technology Data Exchange (ETDEWEB)
Nascimento, Tatiane S.; Koskinas, Marina F.; Matos, Izabela T.; Yamazaki, Ione M.; Dias, Mauro S., E-mail: tatianenas@usp.br, E-mail: koskinas@ipen.br, E-mail: izabelateles@gmail.br, E-mail: iomay1621@yahoo.com.br, E-mail: msdias@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Rajput, Mohamed U., E-mail: usman_rajput60@hotmail.com [Pakistan Institute of Nuclear Science and Technology, Nilore, Islamabad (Pakistan)
2013-07-01
This paper describes the procedure followed by the Nuclear Metrology Laboratory (LMN) at IPEN - CNEN/SP, in Sao Paulo, Brazil, for the standardization of the {sup 90}Y, undertaken by the tracer technique using the {sup 24}Na beta-gamma emitter as the tracer. The measurements were carried out, by means of a 4???? coincidence system. For the observed events registration was used the TAC method. A Monte Carlo simulation for generating the extrapolation curve was applied to obtain the correction of the efficiency for determining the solution activity. The correction factor of the efficiency was also calculated by means of a semi-empirical formula. The {sup 90}Y activity results obtained by both methods were compared. (author)
Computational methods for improving the resolution of subsurface seismic images
Energy Technology Data Exchange (ETDEWEB)
Larner, K.; Hale, D.; Bleistein, N.; Cohen, J.
1990-05-01
We have implemented two-dimensional (2-D) finite difference modeling of elastic waves for study of seismic waves that propagate rather parallel to bedding, as in cross-well seismic surveys and reflections from steep reflectors in surface-seismic surveys. Snapshots of the propagating waves generated and displayed during the course of computation on a high-speed, interactive workstation show tunneling of evanescent waves, a phenomenon not predictable from the ray theory that is the basis of current velocity-determination methods. Accurate solutions from this program will be our standard for analysis of the more efficient, approximate methods that we are developing. We have also developed an interactive algorithm that characterizes geologic structure as a Deluaney mesh, an optimum triangulation of a medium based on supplied node points. Current work is aimed at determining the data structure best suited for efficient ray tracing in 2-D and three-dimensional (3-D) models, for use in high-resolution imaging and interactive estimation of velocity in media in which velocity varies both laterally and vertically. We have developed two new methods for more accurate and more computationally efficient imaging of the subsurface. The first is a stable, accurate, and computationally efficient method for extrapolation 2-D seismic wavefields in depth. The second is an extension of this new depth extrapolation method to 3-D seismic surveys through a digital signal-processing device known as the McClellan transformation. 7 refs., 10 figs.
International Nuclear Information System (INIS)
When solving the problem of radial distribution function (RDF) restoration according to experimentally determined structural factor neutron diffraction), various numerical methods were used and compared. Using as an example the data on neutron diffraction for amorphous alloy Re90Ta10, it was shown that regularizing algorithms (RA) (2)-(4) permit to obtain RDF solution, as regards minor perturbations of initial diffraction data. The possibility of stable RDF extrapolation g(r) to the range of higher r values was evaluated
A simple way of estimation of the mitosis duration by the radiation method
International Nuclear Information System (INIS)
In the curve of mitotic index drop of cell population immediately after irradiation there is a linear section the extrapolation of which to horizontal line of the mitotic index initial level and to ''time'' abscissa axis permits to separate the time interval equal to average mitosis duration. The given parameter estimation for fibroblasts culture by the above method coincided with its value calculated by mitotic index and time of doubling cell number determined experimentally
First criticality prediction of the HTTR by 1/M interposition method
International Nuclear Information System (INIS)
The HTTR's first criticality was achieved in an annular core configuration . It was difficult to predict the first criticality by extrapolation of 1/M. The number of fuel columns at the first criticality was predicted comparing the measured and calculated values of 1/M. The calculated values were obtained by the calculation which achieve the criticality at arbitrary number of fuel loaded core. The number of fuel column to achieve the first criticality was evaluated precisely by the method. (author)
Scientific Electronic Library Online (English)
Francisco Javier, Ozores Suárez.
2013-09-01
Full Text Available SciELO Cuba | Language: Spanish Abstract in spanish Introducción: la excursión sistólica del plano lateral del anillo tricuspídeo (TAPSE) es un parámetro útil en la evaluación de la función del ventrículo derecho en pacientes pediátricos. Objetivos: mostrar los valores normales del TAPSE en niños cubanos según grupos etarios, y describir su relación [...] con la edad, gasto del ventrículo izquierdo, tiempo de aceleración pulmonar y la fracción de eyección del ventrículo izquierdo. Métodos: se realizó un estudio prospectivo en el que se incluyeron 102 niños normales, a cuya medición del TAPSE se les realizó adaptando el programa para la mensuración de la distancia entre el punto E y el septum interventricular. Resultados: el TAPSE medio fue de 19,4 mm (DS±6) con valores medios en la primera semana de 9,5 mm hasta 21,2 a los 5 años y 24,1 en niños mayores. Se encontró correlación positiva significativa entre el TAPSE y la edad (r= 0,679) descrita por la ecuación TAPSE= 13,2787 + 5,2354 log (X). Se mostraron los valores del TAPSE en 5 grupos de edades. Se encontró también una correlación significativa entre el TAPSE, el tiempo de aceleración pulmonar y el gasto sistólico del ventrículo izquierdo. Conclusiones: existen 5 grupos etarios bien definidos, los mayores cambios del TAPSE se presentan antes de los 5 años de edad, y se encontró una relación logarítmica entre el TAPSE, la edad y el tiempo de aceleración pulmonar. Se recomienda el programa utilizado como alternativa en la medición del TAPSE. Abstract in english Introduction: the tricuspid annular plane systolic excursion (TAPSE) is a useful parameter to evaluate the right ventricular function in pediatric patients. Objectives: to show the normal values of TAPSE in Cuban children by age groups, and to describe their relationship with the age, the left ventr [...] icular output, the pulmonary acceleration time and the ejection fraction of the left ventricle. Methods: a prospective study included 102 normal children to whom TAPSE was measured by adapting the program for distance mensuration between point E and the interventricular septum. Results: average TAPSE was 19.4 mm (DS±6) with mean values equal to 9.5 mm in the first week up to 21.2 mm at 5 years and 24.1 in older children. There was significant positive correlation between TAPSE figures and age (r= 0.679) described in equation TAPSE= 13.2787 + 5.2354 log (X). The TAPSE values were presented in five age groups. It was also found that there was significant correlation among TAPSE, pulmonary acceleration time and systolic output of the left ventricle. Conclusions: there exist five well-defined age groups, the major changes occur before 5 years of age and log relation was found among TAPSE, age and pulmonary acceleration time. The used program is recommended as an alternative to measure TAPSE.
New field-theoretic method for the virial expansion.
Kaplan, David B; Sun, Sichun
2011-07-15
We develop a graphical method for computing the virial expansion coefficients for a nonrelativistic quantum field theory. As an example we compute the third virial coefficient b3 for unitary fermions, a nonperturbative system. By calculating several graphs and performing an extrapolation, we arrive at b3=-0.2930, within 0.7% of a recent computation b3=-0.290?952?95 by Liu, Hu, and Drummond, which involved summing 10,000 energy levels for three unitary fermions in a harmonic trap. PMID:21838343
Tracing method applied to the standardization of 137Cs
International Nuclear Information System (INIS)
The procedure followed by the Laboratorio de Metrologia Nuclear at the IPEN, in Sao Paulo, for the standardization of 137Cs is described. The activity measurement was carried out in a 4??-? coincidence system, by the tracing method. The radionuclide 134Cs is a ?-? emitter and was chosen as tracer because of its end-point beta-ray energy which is similar to 137Cs. Some sources were prepared by dropping ? pure and ?-? solutions directly on Collodion film, and other sources were prepared from a 134Cs + 137Cs solution mixed previously in equal proportions. The activity of the solution was determined by the extrapolation technique. (author)
Linearity-independent method for a safety factor profile
International Nuclear Information System (INIS)
This paper proposes a new method to calculate a safety factor, q, profile from gridded data of a poloidal flux, ?, efficiently and accurately. Difficulties of calculating q are derived from a difficulty of specifying a contour line of ? and a singularity at a magnetic axis. In order to solve the first difficulty, the proposed method interpolates knots, which are located on a target ?, by utilizing a normalized arc length and constraints expressed by a magnetic field. Regarding the second difficulty, the proposed method identifies q0 by extrapolating a q profile around a magnetic axis with a constraint of dq/d? = 0 at the magnetic axis. Accuracy assessments of the proposed method are carried out by utilizing the Solov'ev-type equilibrium. The results show the validity and high performance of the proposed method. (paper)
Timing discriminator using leading-edge extrapolation
Gottschalk, Bernard (Palo Alto, CA)
1983-01-01
A discriminator circuit to recover timing information from slow-rising pulses by means of an output trailing edge, a fixed time after the starting corner of the input pulse, which is nearly independent of risetime and threshold setting. This apparatus comprises means for comparing pulses with a threshold voltage; a capacitor to be charged at a certain rate when the input signal is one-third threshold voltage, and at a lower rate when the input signal is two-thirds threshold voltage; current-generating means for charging the capacitor; means for comparing voltage capacitor with a bias voltage; a flip-flop to be set when the input pulse reaches threshold voltage and reset when capacitor voltage reaches the bias voltage; and a clamping means for discharging the capacitor when the input signal returns below one-third threshold voltage.
Wavefield Extrapolation in Pseudo-depth Domain
Ma, Xuxin
2011-12-11
Wave-equation based seismic migration and inversion tools are widely used by the energy industry to explore hydrocarbon and mineral resources. By design, most of these techniques simulate wave propagation in a space domain with the vertical axis being depth measured from the surface. Vertical depth is popular because it is a straightforward mapping of the subsurface space. It is, however, not computationally cost-effective because the wavelength changes with local elastic wave velocity, which in general increases with depth in the Earth. As a result, the sampling per wavelength also increases with depth. To avoid spatial aliasing in deep fast media, the seismic wave is oversampled in shallow slow media and therefore increase the total computation cost. This issue is effectively tackled by using the vertical time axis instead of vertical depth. This is because in a vertical time representation, the "wavelength" is essentially time period for vertical rays. This thesis extends the vertical time axis to the pseudo-depth axis, which features distance unit while preserving the properties of the vertical time representation. To explore the potentials of doing wave-equation based imaging in the pseudo-depth domain, a Partial Differential Equation (PDE) is derived to describe acoustic wave in this new domain. This new PDE is inherently anisotropic because the use of a constant vertical velocity to convert between depth and vertical time. Such anisotropy results in lower reflection coefficients compared with conventional space domain modeling results. This feature is helpful to suppress the low wavenumber artifacts in reverse-time migration images, which are caused by the widely used cross-correlation imaging condition. This thesis illustrates modeling acoustic waves in both conventional space domain and pseudo-depth domain. The numerical tool used to model acoustic waves is built based on the lowrank approximation of Fourier integral operators. To investigate the potential of seismic imaging in the pseudo-depth domain, examples of zero-offset migration are implemented in pseudo-depth domain and compared with conventional space domain imaging results.
Model Mixing for Long-Term Extrapolation.
Czech Academy of Sciences Publication Activity Database
Ettler, P.; Kárný, Miroslav; Nedoma, Petr
Vienna : ARGESIM-ARGE Simulation News, 2007. s. 275-275. [EUROSIM Congress on Modelling and Simulation /6./. 09.09.2007-13.09.2007, Ljubljana] R&D Projects: GA AV ?R 1ET100750401; GA MŠk 1M0572 Institutional research plan: CEZ:AV0Z10750506 Keywords : Simulation * Modelling * Estimation * Multiple models Subject RIV: BB - Applied Statistics, Operational Research http://as.utia.cz/publications/2007/EttKarNed_07b.pdf
FEASIBILITY OF ROUTE EXTRAPOLATION IN RISK ASSESSMENT
For the protection of public health, it is often necessary to estimate acceptable concentrations of chemicals present in the environment when data are lacking for the appropriate route of human exposure. The use of uncertainty factors to protect against potential differences in p...
Energy Technology Data Exchange (ETDEWEB)
Romero, Vicente Jose
2011-11-01
This report explores some important considerations in devising a practical and consistent framework and methodology for utilizing experiments and experimental data to support modeling and prediction. A pragmatic and versatile 'Real Space' approach is outlined for confronting experimental and modeling bias and uncertainty to mitigate risk in modeling and prediction. The elements of experiment design and data analysis, data conditioning, model conditioning, model validation, hierarchical modeling, and extrapolative prediction under uncertainty are examined. An appreciation can be gained for the constraints and difficulties at play in devising a viable end-to-end methodology. Rationale is given for the various choices underlying the Real Space end-to-end approach. The approach adopts and refines some elements and constructs from the literature and adds pivotal new elements and constructs. Crucially, the approach reflects a pragmatism and versatility derived from working many industrial-scale problems involving complex physics and constitutive models, steady-state and time-varying nonlinear behavior and boundary conditions, and various types of uncertainty in experiments and models. The framework benefits from a broad exposure to integrated experimental and modeling activities in the areas of heat transfer, solid and structural mechanics, irradiated electronics, and combustion in fluids and solids.
International Nuclear Information System (INIS)
Comparative measurements of the beta-particle depth dose distribution for a planar 147Pm source were determined using an extrapolation chamber (ECH), radiochromic dye films (RDF) and 7LiF ultra thin thermoluminescence dosemeters (utTLD). The absolute dose estimates provided by the ECH are in excellent agreement with respect to those obtained from RDF dosemeters. In general the agreement between the ECH and the RDF were within 10%. The depth doses initially obtained using 7LiF utTLD dosemeters assuming the dosemeter centre as the effective point of measurement exhibited an overestimation from 18% for the first 10 mg.cm-2 up to 60% at 30 mg.cm-2 with respect to the ECH measurements. However in this assumption the utTLD estimations neglected the dose gradient inside the dosemeter. In order to take this into account the observed relation between the dose rate measured for each utTLD disc and its corresponding mass thickness was used to calculate the dose rate at the disc surface. A significant improvement in terms of agreement with the absolute measurements was achieved using this approach. The much higher sensitivity of utTLDs compared with ECH and RDF make this technique particularly useful for absorbed dose measurements for low activity beta particle sources. (author)
International Nuclear Information System (INIS)
The austenitic stainless steel X6CrNi 1811 (DIN 1.4948) which is used as a structural material for the German Fast Breeder Reactor SNR 300 was creep-tested in a temperature range of 550-7500 under base material condition and as welded material. The results of the creep rupture strength and creep behaviour up to >= 30 000 hrs support experimentally the extrapolation up to operating times >= 105 hours. The microstructure in the basic material of the broken test-specimens was studied by light and transmission electron microscopy and partly evaluated in a quantitative form. All precipitates found at the grain boundaries and inside the grains belong to the type M23C6. Their nucleation is bound to the defects of the crystal lattice and hence depends on the configuration and movement of the dislocations. Therefore a mutual correlation between the creep process and the nucleation of precipitates exists. This explains the divergence of the plot log epsilonsub(min) vs. log sigmasub(o) from a straight line and influences the ductility values. The precipitates at the grain boundaries, which nucleate in competition with the matrix precipitates favour the intercrystalline rupture. (orig.)
Method of continued fractions for on- and off-shell t matrix of local and nonlocal potentials
International Nuclear Information System (INIS)
The method of continued fractions recently proposed by the authors is generalized to an off-shell t-matrix calculation for any nonlocal nonsymmetric interaction. The efficiency of the method is demonstrated for some examples in nuclear physics. The method is not only very efficient, but yields very accurate results when it is combined with the Romberg extrapolation method. A new separable approximation of a potential and the off-shell t matrix is proposed in connection with the method of continued fractions
A semi-empirical method to correct for multiple scattering effects in compton profile measurements
International Nuclear Information System (INIS)
We describe a semi-empirical method to correct experimental Compton profiles for the effect of multiple scattering which is applicable in those cases where it is possible to collect data on samples of more than one thickness. The method consists of calculating the total amount of multiple scattering for each sample thickness using the Monte-Carlo technique, followed by a linear extrapolation of each momentum point in the profiles to 'zero multiple scattering'. The method is tested for experimental results on silicon and water measured with primary radiations of 412 and 60 keV, respectively. (orig.)
International Nuclear Information System (INIS)
Historically, geophysical methods have been used extensively to successfully explore the subsurface for petroleum, gas, mineral, and geothermal resources. Their application, however, for site characterization, and monitoring the performance of near surface waste sites or repositories has been somewhat limited. Presented here is an overview of the geophysical methods that could contribute to defining the subsurface heterogeneity and extrapolating point measurements at the surface and in boreholes to volumetric descriptions in a fractured rock. In addition to site characterization a significant application of geophysical methods may be in performance assessment and in monitoring the repository to determine if the performance is as expected
Eng, Alex Yong Sheng; Ambrosi, Adriano; Sofer, Zden?k; Šimek, Petr; Pumera, Martin
2014-12-23
Beyond MoS2 as the first transition metal dichalcogenide (TMD) to have gained recognition as an efficient catalyst for the hydrogen evolution reaction (HER), interest in other TMD nanomaterials is steadily beginning to proliferate. This is particularly true in the field of electrochemistry, with a myriad of emerging applications ranging from catalysis to supercapacitors and solar cells. Despite this rise, current understanding of their electrochemical characteristics is especially lacking. We therefore examine the inherent electroactivities of various chemically exfoliated TMDs (MoSe2, WS2, WSe2) and their implications for sensing and catalysis of the hydrogen evolution and oxygen reduction reactions (ORR). The TMDs studied are found to possess distinctive inherent electroactivities and together with their catalytic effects for the HER are revealed to strongly depend on the chemical exfoliation route and metal-to-chalcogen composition particularly in MoSe2. Despite its inherent activity exhibiting large variations depending on the exfoliation procedure, it is also the most efficient HER catalyst with a low overpotential of -0.36 V vs RHE (at 10 mA cm(-2) current density) and fairly low Tafel slope of ?65 mV/dec after BuLi exfoliation. In addition, it demonstrates a fast heterogeneous electron transfer rate with a k0obs of 9.17×10(-4) cm s(-1) toward ferrocyanide, better than that seen for conventional glassy carbon electrodes. Knowledge of TMD electrochemistry is essential for the rational development of future applications; inherent TMD activity may potentially limit certain purposes, but intended objectives can nonetheless be achieved by careful selection of TMD compositions and exfoliation methods. PMID:25453501
Tafel, Külliki
2006-01-01
Tippjuhtide mõju organisatsioonisistele suhetele ning juhimistegevusele. Skeemid: The content and overlap of the terms of corporate governance and management; The theoretical framework for the study; The degree of involvement of the board of directors in the strategic management process; Framework for treatment of the owner-CEO-employee chain of relations
Directory of Open Access Journals (Sweden)
Sie S. T.
2006-11-01
Full Text Available Research and development studies in a laboratory are necessarily conducted on a scale which is orders of magnitude smaller than that in commercial practice. In the case of the development and commercialization of an unprecedented novel process technology, available laboratory results have to be translated into envisaged technology on a commercial scale, i. e. the problem is that of scaling-up. However, in many circumstances the commercial technology is more or less defined as far as type of reactor is concerned and laboratory studies are concerned with the generation of predictive information on the behaviour of new catalysts, alternative feedstocks, etc. , in such a reactor. In many cases the complexity of feed composition and reaction kinetics preclude the prediction to be made on the basis of a combination of fundamental kinetic data and computer models, so that there is no other option than to simulate the commercial reactor on a laboratory scale, i. e. the problem is that of scaling-down. From the point of view of R & D Defficiency, the scale of the laboratory experiments should be as small as possible without detracting from the meaningfulness of the results. In the present paper some problems in the scaling-down of a trickle-flow reactor as applied in hydrotreating processes to kinetically equivalent laboratory reactors of different sizes will be discussed. Two main aspects relating to inequalities in fluid dynamics resulting from the differences in scale will be treated in more detail, viz. deviations from ideal plug flow and non ideal wetting or irrigation of the catalyst particles. Although a laboratory reactor can never be a true small-scale replica of a commercial trickle-flow reactor in all respects, it can nevertheless be made to provide representative data as far as the catalytic conversion aspects are concerned. By ressorting to measures such as catalyst bed dilution with fine catalytically inert material it proves possible to carry out meaningful process research on hydrotreating processes on the scale of micro-reactors. Les études et mises au point effectuées en laboratoire sont nécessairement effectuées à plus petite échelle que les réalisations commerciales. Dans le cas de la mise au point et de la commercialisation de la technologie d'un procédé nouveau, il faudra traduire les résultats obtenus en laboratoire pour la technologie envisagée à l'échelle commerciale; le problème est donc l'extrapolation vers le haut. Cependant, bien souvent, la technologie commerciale, pour ce qui touche au type de réacteur, est plus ou moins bien définie et les études de laboratoire s'attachent à produire des données permettant de prévoir le comportement qu'auront dans ce réacteur des catalyseurs nouveaux, de matières premières de substitution, etc. Dans bien des cas, étant donné la complexité de la composition de la matière première et la cinétique de réaction, il est impossible de mener la prévision en s'appuyant sur les données cinétiques et les modèles informatiques, de sorte qu'il n'y a pas d'autre solution que la simulation du réacteur commercial à l'échelle du laboratoire; le problème est donc l'extrapolation vers le bas. Du point de vue de l'efficacité des études de recherche et développement, pour les expériences en laboratoire, l'échelle devra être aussi petite que possible sans nuire à la signification des résultats. Le présent article examine certains problèmes liés à l'extrapolation vers le bas d'un réacteur à écoulement ruisselant telle qu'elle est appliquée dans les procédés d'hydrotraitement à des réacteurs de laboratoire de tailles différentes cinétiquement équivalents. Deux aspects principaux relatifs à des inégalités de dynamique des fluides résultant de différences d'échelle sont décrits plus en détail, i. e. les écarts par rapport à un écoulement idéal donnant lieu à un effet bouchon et au mouillage ou à l'irrigation non-idéal des particules de catalyseur. Bien qu'un réacteur de laboratoire ne puisse jam
McCormack, Drew A.; Kroes, Geert-Jan; Neuhauser, Daniel
1998-10-01
We apply two hybrid methods for solving scattering problems affected by resonances, to a four-dimensional reactive surface scattering system. In each method the solution of the problem is divided into two parts: a wave packet propagation, and a resonance calculation; results of the resonance calculation are used to extrapolate the long-time behavior of the system. In the first hybrid method, the propagation is by the multistep Chebyshev method, with calculation of resonances performed by the Lanczos method. In the second, the propagation is done using an implementation of the absorbing boundary condition (ABC) evolution operator, and the resonance calculation by filter diagonalization (FDG). Each method produces accurate scattering results in much less computation time than standard long-time wave packet propagation. The Chebyshev-Lanczos approach proves most capable for the calculation of resonances, but is computationally expensive. The ABC-FDG method is much cheaper to implement, but could not be made to extract accurate data for certain broad, overlapping resonances. This was overcome by propagating longer (still much shorter than for long-time propagation) to allow the elusive resonances time to decay.
Methods for measuring arctic and alpine shrub growth : a review
DEFF Research Database (Denmark)
Myers-Smith, Isla; Hallinger, Martin
2015-01-01
Shrubs have increased in abundance and dominance in arctic and alpine regions in recent decades. This often dramatic change, likely due to climate warming, has the potential to alter both the structure and function of tundra ecosystems. The analysis of shrub growth is improving our understanding of tundra vegetation dynamics and environmental changes. However, dendrochronological methods developed for trees, need to be adapted for the morphology and growth eccentricity of shrubs. Here, we review current and developing methods to measure radial and axial growth, estimate age, and assess growth dynamics in relation to environmental variables. Recent advances in sampling methods, analysis and applications have improved our ability to investigate growth and recruitment dynamics of shrubs. However, to extrapolate findings to the biome scale, future dendroecologicalwork will require improved approaches that better address variation in growth within parts of the plant, among individuals within populations and between species.
Alternating proximal gradient method for nonnegative matrix factorization
Xu, Yangyang
2011-01-01
Nonnegative matrix factorization has been widely applied in face recognition, text mining, as well as spectral analysis. This paper proposes an alternating proximal gradient method for solving this problem. With a uniformly positive lower bound assumption on the iterates, any limit point can be proved to satisfy the first-order optimality conditions. A Nesterov-type extrapolation technique is then applied to accelerate the algorithm. Though this technique is at first used for convex program, it turns out to work very well for the non-convex nonnegative matrix factorization problem. Extensive numerical experiments illustrate the efficiency of the alternating proximal gradient method and the accleration technique. Especially for real data tests, the accelerated method reveals high superiority to state-of-the-art algorithms in speed with comparable solution qualities.
International Nuclear Information System (INIS)
TiO2–NiO nanocomposite thin films were deposited on the 316L stainless steel using sol–gel method by a dip coating technique. Different techniques such as differential thermal analysis, thermogravimetric analysis, X-ray diffraction, Fourier transform infrared spectrometry, scanning electron microscopy and scanning probe microscopy were carried out in order to characterize the structure of the coatings. The corrosion resistance of the coatings was evaluated by using Tafel polarization and electrochemical impedance spectroscopy tests of uncoated and coated specimens in a 3.5% NaCl solution at room temperature. It was found that to obtain desirable structure in coatings, the coatings should be calcined at 600 °C for one and half hour. NiTiO3, anatase and rutile were the phases obtained in different calcination conditions in air atmosphere. The results of corrosion tests indicated that with increasing the dipping times from 2 to 4, the corrosion current density first decreases but when increasing the dipping times to 6, it increases. Also the corrosion current density decreased from 186.7 nA.cm?2 (uncoated steel) to 34.21 nA.cm?2 (80%TiO2–20%NiO) and corrosion potential increased from ? 150.2 mV (uncoated steel) to ? 107.3 mV (67%TiO2–33%NiO). - Highlights: ? TiO2–NiO thin films were deposited on the 316L stainless steel using sol–gel method. ? Different compositions, anncompositions, annealing times and temperatures resulted in various phases. ? Films having different compositions showed various surface morphologies. ? Films having a composition of 80%TiO2–20%NiO showed a good corrosion protection.
Energy Technology Data Exchange (ETDEWEB)
Cheraghi, H., E-mail: hoch2020@yahoo.com [Materials Science and Engineering Department, Iran University of Science and Technology (IUST), P.O. Box: 16765163, Narrmak Street, Tehran (Iran, Islamic Republic of); Shahmiri, M., E-mail: mshahmiri@iust.ac.ir [Materials Science and Engineering Department, Iran University of Science and Technology (IUST), P.O. Box: 16765163, Narrmak Street, Tehran (Iran, Islamic Republic of); Sadeghian, Z. [Research Institute of Petroleum Industry (RIPI), P.O. Box: 14857-3311, West Blvd. Azadi Sport Complex, Tehran (Iran, Islamic Republic of)
2012-11-01
TiO{sub 2}-NiO nanocomposite thin films were deposited on the 316L stainless steel using sol-gel method by a dip coating technique. Different techniques such as differential thermal analysis, thermogravimetric analysis, X-ray diffraction, Fourier transform infrared spectrometry, scanning electron microscopy and scanning probe microscopy were carried out in order to characterize the structure of the coatings. The corrosion resistance of the coatings was evaluated by using Tafel polarization and electrochemical impedance spectroscopy tests of uncoated and coated specimens in a 3.5% NaCl solution at room temperature. It was found that to obtain desirable structure in coatings, the coatings should be calcined at 600 Degree-Sign C for one and half hour. NiTiO{sub 3}, anatase and rutile were the phases obtained in different calcination conditions in air atmosphere. The results of corrosion tests indicated that with increasing the dipping times from 2 to 4, the corrosion current density first decreases but when increasing the dipping times to 6, it increases. Also the corrosion current density decreased from 186.7 nA.cm{sup -2} (uncoated steel) to 34.21 nA.cm{sup -2} (80%TiO{sub 2}-20%NiO) and corrosion potential increased from - 150.2 mV (uncoated steel) to - 107.3 mV (67%TiO{sub 2}-33%NiO). - Highlights: Black-Right-Pointing-Pointer TiO{sub 2}-NiO thin films were deposited on the 316L stainless steel using sol-gel method. Black-Right-Pointing-Pointer Different compositions, annealing times and temperatures resulted in various phases. Black-Right-Pointing-Pointer Films having different compositions showed various surface morphologies. Black-Right-Pointing-Pointer Films having a composition of 80%TiO{sub 2}-20%NiO showed a good corrosion protection.
International Nuclear Information System (INIS)
The homotopy perturbation method is used to formulate a new analytic solution of the neutron diffusion equation both for a sphere and a hemisphere of fissile material. Different boundary conditions are investigated; including zero flux on boundary, zero flux on extrapolated boundary, and radiation boundary condition. The interaction between two hemispheres with opposite flat faces is also presented. Numerical results are provided for one-speed fast neutrons in 235U. A comparison with Bessel function based solutions demonstrates that the homotopy perturbation method can exactly reproduce the results. The computational implementation of the analytic solutions was found to improve the numeric results when compared to finite element calculations.
Energy Technology Data Exchange (ETDEWEB)
Khasawneh, Kafa [Prince Abdullah Bin Ghazi Faculty of Science and IT, Al-Balqa Applied University, P.O. Box 7051, Salt 19117 (Jordan); Dababneh, Saed, E-mail: dababneh@bau.edu.j [Prince Abdullah Bin Ghazi Faculty of Science and IT, Al-Balqa Applied University, P.O. Box 7051, Salt 19117 (Jordan); Jordan Nuclear Regulatory Commission, P.O. Box 2587, Amman 11941 (Jordan); Odibat, Zaid [Prince Abdullah Bin Ghazi Faculty of Science and IT, Al-Balqa Applied University, P.O. Box 7051, Salt 19117 (Jordan)
2009-11-15
The homotopy perturbation method is used to formulate a new analytic solution of the neutron diffusion equation both for a sphere and a hemisphere of fissile material. Different boundary conditions are investigated; including zero flux on boundary, zero flux on extrapolated boundary, and radiation boundary condition. The interaction between two hemispheres with opposite flat faces is also presented. Numerical results are provided for one-speed fast neutrons in {sup 235}U. A comparison with Bessel function based solutions demonstrates that the homotopy perturbation method can exactly reproduce the results. The computational implementation of the analytic solutions was found to improve the numeric results when compared to finite element calculations.
Virtual Power Extraction Method of Designing Starting Control Law of Turbofan Engine
Directory of Open Access Journals (Sweden)
Yuchun Chen
2009-07-01
Full Text Available Virtual power extraction method (VPEM of designing starting control law of turbofan engine was presented, and the computer program was developed. The VPEM of designing starting control law is based on the principle of VPEM of designing acceleration control law of turbofan engine, and combined with the method of extrapolation of component maps. The starting control law of some turbofan engine at single flight state and in whole starting envelope was designed by using the program, some computing results were analyzed. Computing results showed that VPEM is accurate and effective for designing starting control law of turbofan engine.
Murariu, Gabriel; Condurache-Bota, Simona; Tigau, Nicolae
2012-07-01
The optical reflectance of Bi2O3 was measured, and the optical properties were estimated by Kramers-Kronig analysis. The novelty of the present study is due to the implementation of a MAPLE software approach to the complex computations implied by this extrapolation. The analytical fit of the reflectance spectrum is applied, accompanied by a careful extrapolation, which is necessary within the Kramers-Kronig method. In this way starting from the reflectance samples data, using this transformation, a very good agreement is obtained between the main optical parameters, namely the refractive index and the absorbtion coefficient. The study is implemented for Bi2O3 films deposited by thermal vacuum evaporation at different temperatures of the glass substrates and the comparison with the experimental data set being made using the transmission and the reflection optical spectra.
Examining the accumulated oxygen deficit method in front crawl swimming.
Reis, V M; Marinho, D A; Policarpo, F B; Carneiro, A L; Baldari, C; Silva, A J
2010-06-01
The present study investigated the Accumulated Oxygen Deficit (AOD) method in front crawl swimming with the aims to assess the robustness of the oxygen uptake/swimming velocity regression line and to quantify the precision of the AOD. Twenty-nine male swimmers performed two swimming tests in different days, with a 24 h recovery between tests: a graded test and an all-out test. The all-out test was performed either in 100 m (n=11), 200 m (n=13) or 400 m (n=5). Through all testing expired gases were collected breath by breath and analysed with a K4b2 Gas Analyser (Cosmed, Rome, Italy) connected to an AquaTrainer Valve (Cosmed, Rome, Italy). The error of oxygen uptake/swimming velocity regression lines was approximately 4-5 ml x kg (-1) x min (-1)) and the regressions allowed an extrapolation of the energy cost to higher intensities with a standard error of prediction of approximately 3-4 ml x kg (-1) x min (-1). However, the data variability was considerable (95% confidence intervals of the linear extrapolation larger than 13 ml x kg (-1) x min (-1)). The AOD imprecision varied among the three distance events from approximately 3-13 ml x kg (-1). These absolute errors are small, considering the time that subjects took to cover the three distances, but relative to the AOD values that were estimated they can be considered high, especially in the 400 m bout. PMID:20301045
An evaluation of rise time characterization and prediction methods
Robinson, Leick D.
1994-01-01
One common method of extrapolating sonic boom waveforms from aircraft to ground is to calculate the nonlinear distortion, and then add a rise time to each shock by a simple empirical rule. One common rule is the '3 over P' rule which calculates the rise time in milliseconds as three divided by the shock amplitude in psf. This rule was compared with the results of ZEPHYRUS, a comprehensive algorithm which calculates sonic boom propagation and extrapolation with the combined effects of nonlinearity, attenuation, dispersion, geometric spreading, and refraction in a stratified atmosphere. It is shown there that the simple empirical rule considerably overestimates the rise time estimate. In addition, the empirical rule does not account for variations in the rise time due to humidity variation or propagation history. It is also demonstrated that the rise time is only an approximate indicator of perceived loudness. Three waveforms with identical characteristics (shock placement, amplitude, and rise time), but with different shock shapes, are shown to give different calculated loudness. This paper is based in part on work performed at the Applied Research Laboratories, the University of Texas at Austin, and supported by NASA Langley.
Activity standardization of 152Eu by anti-coincidence method
International Nuclear Information System (INIS)
152Eu has a complex decay scheme, which decays 27.9% by ?- emission and 72.1% by electron capture. The nuclide emits more than 140 ?-rays which include 12 main y-rays in the range of 122-1408 keV. 152Eu is an important radionuclide for the energy and efficiency calibration of the HPGe gamma-spectrometers. It is very important to study the absolute measurement methods of the activity. A solution of 152Eu was absolutely standardized by the 4??(PPC)-?(HPGe) anti-coincidence counting system and the results were compared with that by 4??-4?? coincidence counting efficiency extrapolation, HPGe gamma-spectrometer and 4?? high pressurized ionization chamber. It is shown that all the results from the above methods are in good agreements within the uncertainties. (authors)
Method of characteristics calculations within the CMFD framework
Energy Technology Data Exchange (ETDEWEB)
Cho, Jin Young; Joo, Han Gyu; Kim, Ha Young; Zee, Sung Quun; Chang, Moon Hee [Korea Atomic Energy Research Institute, Taejeon (Korea)
2002-03-01
This report describes the detailed approximation of the well-established coarse mesh finite difference(CMFD) method to the method of characteristics(MOC) transport calculation as an acceleration scheme. The CMFD formulation is based on the current conservation at the node surface. Therefore, the cell based multi-group currents at the cell interfaces are calculated during the MOC calculation. The pin-cell level multi-group CMFD problem is first formulated from the multi-group MOC transport problem using the multi-group current and cell homogenization procedure. To solve the cell-based multi-group CMFD problem efficiently, a two-group CMFD formulation is also derived from the multi-group CMFD formulation. The cell averaged scalar fluxes and boundary currents from the two-level (multi-group/two group) CMFD calculation are again used to update the regional scalar fluxes and boundary angular fluxes that are unknowns in the MOC transport calculation. The performance of the two-level CMFD acceleration is examined for three test problems with different sizes including a realistic quarter core PWR problem, and compared against the power iteration using Chebyshev two-parameter extrapolation and pin-cell based CMR acceleration. The CMFD formulation provides a significant reduction in the number of ray tracings. About 9 MOC ray tracing iterations are enough to obtain converged solutions in all the test cases. The computational results show that the CMFD formulation reduces the number of ray tracing by a factor of 6-55 compared with the Chebyshev two-parameter extrapolation and 2-3 compared with the CMR acceleration method. Consequently, the CMFD formulation provides a speedup of 2.5 in computing time over the most commonly used CMR acceleration method. These results indicate that the new CMFD acceleration scheme is very effective in whole core MOC transport calculations. 10 refs., 20 figs., 5 tabs. (Author)
Methods to estimate the genetic risk
International Nuclear Information System (INIS)
The estimation of the radiation-induced genetic risk to human populations is based on the extrapolation of results from animal experiments. Radiation-induced mutations are stochastic events. The probability of the event depends on the dose; the degree of the damage dose not. There are two main approaches in making genetic risk estimates. One of these, termed the direct method, expresses risk in terms of expected frequencies of genetic changes induced per unit dose. The other, referred to as the doubling dose method or the indirect method, expresses risk in relation to the observed incidence of genetic disorders now present in man. The advantage of the indirect method is that not only can Mendelian mutations be quantified, but also other types of genetic disorders. The disadvantages of the method are the uncertainties in determining the current incidence of genetic disorders in human and, in addition, the estimasion of the genetic component of congenital anomalies, anomalies expressed later and constitutional and degenerative diseases. Using the direct method we estimated that 20-50 dominant radiation-induced mutations would be expected in 19 000 offspring born to parents exposed in Hiroshima and Nagasaki, but only a small proportion of these mutants would have been detected with the techniques used for the population study. These methods were used to predict the genetic damage from the fallout of the reactor accident at Chernobyl in the vicinity of Southern Germany. Tbyl in the vicinity of Southern Germany. The lack of knowledge for the interaction of chemicals with ionizing radiation and the discrepancy between the high safety standards for radiation protection and the low level of knowledge for the toxicological evaluation of chemical mutagens will be emphasized. (author)
International Nuclear Information System (INIS)
We calculate the ground-state properties of an unpolarized two-component Fermi gas with the aid of the diffusion quantum Monte Carlo (DMC) methods. Using an extrapolation to the zero effective range of the attractive two-particle interaction, we find E/Efree in the unitary limit to be 0.212(2), 0.407(2), 0.409(3), and 0.398(3) for 4, 14, 38, and 66 atoms, respectively. Our calculations indicate that the dependence of the total energy on the effective range of the interaction Reff is sizable and the extrapolation to Reff=0 is therefore important for reaching the true unitary limit. To test the quality of nodal surfaces and to estimate the impact of the fixed-node approximation, we perform released-node DMC calculations for 4 and 14 atoms. Analysis of the released-node and the fixed-node results suggests that the main sources of the fixed-node errors are long-range correlations, which are difficult to sample in the released-node approaches due to the fast growth of the bosonic noise. Besides energies, we evaluate the two-body density matrix and the condensate fraction. We find that the condensate fraction for the 66-atom system converges to 0.56(1) after the extrapolation to the zero interaction range.
International Nuclear Information System (INIS)
The author presents a review about the application of the methods of classical statistical mechanics to quantum field theory. As examples he discusses ferromagnets and Yang-Mills theories on a lattice. He concentrates on expansion methods for the calculation of the partition functions. (HSI)
B-physics from the ratio method with Wilson twisted mass fermions
Carrasco, N; Frezzotti, R; Gimenez, V; Lubicz, G Herdoiza V; Martinelli, G; Michael, C; Palao, D; Rossi, G C; Sanfilippo, F; Shindler, A; Simula, S; Tarantino, C
2012-01-01
We present a precise lattice QCD determination of the b-quark mass, of the B and Bs decay constants and first preliminary results for the B-mesons bag parameter. Simulations are performed with Nf = 2 Wilson twisted mass fermions at four values of the lattice spacing and the results are extrapolated to the continuum limit. Our calculation benefits from the use of improved interpolating operators for the B-mesons and employs the so-called ratio method. The latter allows a controlled interpolation at the b-quark mass between the relativistic data around and above the charm quark mass and the exactly known static limit.
A method for determining the selectivity of solvents for purifying oils
Energy Technology Data Exchange (ETDEWEB)
Marushkina, V.A.; Marushkin, A.B.; Zolotarev, P.A.
1983-01-01
In the method for determining the selectivity of solvents for purifying oils through comparing the refraction coefficients of the products of extraction, in order to increase the precision of identification in conditions of counter flow extraction, the content of the solvents in the extract (E) and the refinate (R) are identified, the contaminating impurities are removed from them through shifting the phase equilibrium and from the refraction indicator of the isolated impurities the selectivity of the solvents is judged through extrapolation to the zero conclusion.
A Systematic Method For Tracer Test Analysis: An Example Using Beowawe Tracer Data
Energy Technology Data Exchange (ETDEWEB)
G. Michael Shook
2005-01-01
Quantitative analysis of tracer data using moment analysis requires a strict adherence to a set of rules which include data normalization, correction for thermal decay, deconvolution, extrapolation, and integration. If done correctly, the method yields specific information on swept pore volume, flow geometry and fluid velocity, and an understanding of the nature of reservoir boundaries. All calculations required for the interpretation can be done in a spreadsheet. The steps required for moment analysis are reviewed in this paper. Data taken from the literature is used in an example calculation.
Measurement of dynamic parameter of sub-critical facility with Rossi-? method
International Nuclear Information System (INIS)
This paper presents the Rossi-a method for the micro-noise analysis in the reactor physics experiments, which is applied in the study of measurement of the kinetic parameter, ? eigen value, of Tsinghua University's Sub-Critical Facility. The measurement is performed under extremely low flux condition, and ?c, the critical ? eigenvalue, is obtained by the way of extrapolation. Meanwhile, the theoretical calculation has been carried out based on MCNP and TMCC codes. Results from measurement and calculation agree well with each other. (authors)
DEFF Research Database (Denmark)
McLaughlin, W.L.; Miller, A.
2003-01-01
Chemical and physical radiation dosimetry methods, used for the measurement of absorbed dose mainly during the practical use of ionizing radiation, are discussed with respect to their characteristics and fields of application.
Method and apparatus for determining minority carrier diffusion length in semiconductors
Goldstein, Bernard (Princeton, NJ); Dresner, Joseph (Princeton, NJ); Szostak, Daniel J. (Mercerville, NJ)
1983-07-12
Method and apparatus are provided for determining the diffusion length of minority carriers in semiconductor material, particularly amorphous silicon which has a significantly small minority carrier diffusion length using the constant-magnitude surface-photovoltage (SPV) method. An unmodulated illumination provides the light excitation on the surface of the material to generate the SPV. A manually controlled or automatic servo system maintains a constant predetermined value of the SPV. A vibrating Kelvin method-type probe electrode couples the SPV to a measurement system. The operating optical wavelength of an adjustable monochromator to compensate for the wavelength dependent sensitivity of a photodetector is selected to measure the illumination intensity (photon flux) on the silicon. Measurements of the relative photon flux for a plurality of wavelengths are plotted against the reciprocal of the optical absorption coefficient of the material. A linear plot of the data points is extrapolated to zero intensity. The negative intercept value on the reciprocal optical coefficient axis of the extrapolated linear plot is the diffusion length of the minority carriers.
A review of experimental methods for determining residual creep life
International Nuclear Information System (INIS)
Experimental methods available for determining how much creep life remains at a particular time in the high temperature service of a component are reviewed. After a brief consideration of the limitations of stress rupture extrapolation techniques, the application of post-exposure creep testing is considered. Ways of assessing the effect of microstructural degradation on residual life are then reviewed. It is pointed out that while this type of work will be useful for certain materials, there are other materials in which 'mechanical damage' such as cavitation will be more important. Cavitation measurement techniques are therefore reviewed. The report ends with a brief consideration of the use of crack growth measurements in assessing the residual life of cracked components. (author)
Radiative neutron capture cross section measurements using the spectrum method
International Nuclear Information System (INIS)
The capture cross section is determined through the ? ray spectrum emitted by the sample. The ? rays are detected with a central NaI scintillator surrounded by a NaI annulus. The spectrometer is used both in the anti-Compton and first escape modes at the same time. The time-of-flight technique is used to reduce the background. The pulse-height spectrum is unfolded and corrected for the spectrometer efficiency. A theoretical calculation is used to extrapolate the capture ?-ray spectrum below the experimental threshold or in the region containing ?-rays from the (n,n'?) reaction. The radiative capture cross section is then deduced from the capture spectrum. The method is applied to the capture cross section measurements of gold for 0.5 to 3.0 MeV neutrons
Scattering from finite size methods in lattice QCD
International Nuclear Information System (INIS)
Using two flavors of maximally twisted mass fermions, we calculate the S-wave pion-pion scattering length in the isospin I=2 channel and the P-wave pion-pion scattering phase in the isospin I=1 channel. In the former channel, the lattice calculations are performed at pion masses ranging from 270 MeV to 485 MeV. We use chiral perturbation theory at next-to-leading order to extrapolate our results. At the physical pion mass, we find m?aI=2??=-0.04385(28)(38) for the scattering length. In the latter channel, the calculation is currently performed at a single pion mass of 391 MeV. Making use of finite size methods, we evaluate the scattering phase in both the center of mass frame and the moving frame. The effective range formula is employed to fit our results, from which the rho resonance mass and decay width are evaluated. (orig.)
Historical Sulfur Dioxide Emissions 1850-2000: Methods and Results
Energy Technology Data Exchange (ETDEWEB)
Smith, Steven J.; Andres, Robert; Conception , Elvira; Lurz, Joshua
2004-01-25
A global, self-consistent estimate of sulfur dioxide emissions over the last one and a half century were estimated by using a combination of bottom-up and best available inventory methods including all anthropogenic sources. We find that global sulfur dioxide emissions peaked about 1980 and have generally declined since this time. Emissions were extrapolated to a 1{sup o} x 1{sup o} grid for the time period 1850-2000 at annual resolution with two emission height levels and by season. Emissions are somewhat higher in the recent past in this new work as compared with some comprehensive estimates. This difference is largely due to our use of emissions factors that vary with time to account for sulfur removals from fossil fuels and industrial smelting processes.
Directory of Open Access Journals (Sweden)
Maria Kikila
2012-01-01
Full Text Available Child discipline is one of the most important elements of successful parenting. As discipline is defined the process that help children to learn appropriate behaviors and make good choices. Aim: The aim of the present study was to review the literature about the discipline methods. The method ?f this study included bibliography research from both the review and the research literature, mainly in the pubmed data base which referred to the discipline methods. Results: In the literature it is cited that discipline is not the same as punishment because is more related to teaching. The ultimate goal of effective punishment is to help the child in exercising self-control, accountability and respect. Children raised without proper discipline, are at risk for a variety of behavioral and emotional problems. Over the last decades, many child discipline techniques have been suggested that vary according to the age of the child, the parenting style and the severity of the behavior. The most effective methods are giving rewards and guidance to make good choices, explaining negative consequences for disobedience without issuing threats, teaching of moral behaviors by displaying parents' good and moral behaviors. Another commonly accepted discipline method is "the consequences' which permits children to have the dignity of dealing with results of their behavior. Conclusions: Discipline consists a tool for parents for the reason that it trains children to think their improper behavior and the following consequences as well as the possible solutions to each problem.
Shen, Jie; Wang, Li-Lian
2011-01-01
Along with finite differences and finite elements, spectral methods are one of the three main methodologies for solving partial differential equations on computers. This book provides a detailed presentation of basic spectral algorithms, as well as a systematical presentation of basic convergence theory and error analysis for spectral methods. Readers of this book will be exposed to a unified framework for designing and analyzing spectral algorithms for a variety of problems, including in particular high-order differential equations and problems in unbounded domains. The book contains a large
Szulc, Stefan
2014-01-01
Statistical Methods provides a discussion of the principles of the organization and technique of research, with emphasis on its application to the problems in social statistics. This book discusses branch statistics, which aims to develop practical ways of collecting and processing numerical data and to adapt general statistical methods to the objectives in a given field.Organized into five parts encompassing 22 chapters, this book begins with an overview of how to organize the collection of such information on individual units, primarily as accomplished by government agencies. This text then
Halberstam, Heine
2013-01-01
Derived from the techniques of analytic number theory, sieve theory employs methods from mathematical analysis to solve number-theoretical problems. This text by a noted pair of experts is regarded as the definitive work on the subject. It formulates the general sieve problem, explores the theoretical background, and illustrates significant applications.""For years to come, Sieve Methods will be vital to those seeking to work in the subject, and also to those seeking to make applications,"" noted prominent mathematician Hugh Montgomery in his review of this volume for the Bulletin of the Ameri
An estimation method of full scale performance for pulling type podded propellers
Park, Hyoung-Gil; Choi, Jung-Kyu; Kim, Hyoung-Tae
2014-12-01
This paper presents a new estimation method of full scale propulsive performance for the pulling type podded propeller. In order to estimate the drag of pod housing, a drag velocity ratio, which includes the effects of podded propeller loading and Reynolds number, is presented and evaluated through the comparison of model test and numerical analysis. By separating the thrust of propeller blade and the drag of pod housing, extrapolation method of pod housing drag to full scale is deduced, and correction method of propeller blade thrust and torque to full scale is presented. This study utilized the drag coefficient ratio of the pod housing as a measure for expanding it to full scale, but in order to increase the accuracy of performance evaluation, additional study is necessary on the method for the full scale expansion via separating the drag of pod body, strut and fin which consist the pod housing.
Energy Technology Data Exchange (ETDEWEB)
Solano, R.; Schirra, M.; Rivas, M. de la; Barroso, S.; Seith, B.
1982-07-01
The austenitic stainless steel X6crni1811 (Din 1.4948) used as a structure material for the German Fast Breeder Reactor SNR 300 was creep tested in a temperature range of 550-650 degree centigree material condition as well as welded material condition. The main point of this program (Extrapolation-Program) lies in the knowledge of the creep-rupture-strength and creep-behaviour up to 3 x 10{sup 4} hours higher temperatures in order to extrapolated up to {>=}10{sup 5} hours for operating temperatures. In order to study the stress dependency of the minimum creep rate additional tests were carried out of 550 degree centigree - 750 degree centigree. The present report describes the state in the running program with test-times of 23.000 hours and results from tests up to 55.000 hours belonging to other parallel programs are taken into account. Besides the creep-rupture behaviour it is also made a study of ductility between 550 and 750 degree centigree. Extensive metallographic examinations have been made to study the fracture behaviour and changes in structure. (Author)
Saar, E.
2006-01-01
The lecture introduces a trous wavelet transforms, explains how to estimate the spatial density for galaxy distributions, and, finally, how to describe the morphology of cosmological density fields. An example application of these methods to the 2dFGRS gives unexpected results.
Reid, M M; Campbell, Amity C; Elliott, B C
2012-02-01
Tennis stroke mechanics have attracted considerable biomechanical analysis, yet current filtering practice may lead to erroneous reporting of data near the impact of racket and ball. This research had three aims: (1) to identify the best method of estimating the displacement and velocity of the racket at impact during the tennis serve, (2) to demonstrate the effect of different methods on upper limb kinematics and kinetics and (3) to report the effect of increased noise on the most appropriate treatment method. The tennis serves of one tennis player, fit with upper limb and racket retro-reflective markers, were captured with a Vicon motion analysis system recording at 500 Hz. The raw racket tip marker displacement and velocity were used as criterion data to compare three different endpoint treatments and two different filters. The 2nd-order polynomial proved to be the least erroneous extrapolation technique and the quintic spline filter was the most appropriate filter. The previously performed "smoothing through impact" method, using a quintic spline filter, underestimated the racket velocity (9.1%) at the time of impact. The polynomial extrapolation method remained effective when noise was added to the marker trajectories. PMID:21975124
Functional renormalization group methods in quantum chromodynamics
Energy Technology Data Exchange (ETDEWEB)
Braun, J.
2006-12-18
We apply functional Renormalization Group methods to Quantum Chromodynamics (QCD). First we calculate the mass shift for the pion in a finite volume in the framework of the quark-meson model. In particular, we investigate the importance of quark effects. As in lattice gauge theory, we find that the choice of quark boundary conditions has a noticeable effect on the pion mass shift in small volumes. A comparison of our results to chiral perturbation theory and lattice QCD suggests that lattice QCD has not yet reached volume sizes for which chiral perturbation theory can be applied to extrapolate lattice results for low-energy observables. Phase transitions in QCD at finite temperature and density are currently very actively researched. We study the chiral phase transition at finite temperature with two approaches. First, we compute the phase transition temperature in infinite and in finite volume with the quark-meson model. Though qualitatively correct, our results suggest that the model does not describe the dynamics of QCD near the finite-temperature phase boundary accurately. Second, we study the approach to chiral symmetry breaking in terms of quarks and gluons. We compute the running QCD coupling for all temperatures and scales. We use this result to determine quantitatively the phase boundary in the plane of temperature and number of quark flavors and find good agreement with lattice results. (orig.)
Functional renormalization group methods in quantum chromodynamics
International Nuclear Information System (INIS)
We apply functional Renormalization Group methods to Quantum Chromodynamics (QCD). First we calculate the mass shift for the pion in a finite volume in the framework of the quark-meson model. In particular, we investigate the importance of quark effects. As in lattice gauge theory, we find that the choice of quark boundary conditions has a noticeable effect on the pion mass shift in small volumes. A comparison of our results to chiral perturbation theory and lattice QCD suggests that lattice QCD has not yet reached volume sizes for which chiral perturbation theory can be applied to extrapolate lattice results for low-energy observables. Phase transitions in QCD at finite temperature and density are currently very actively researched. We study the chiral phase transition at finite temperature with two approaches. First, we compute the phase transition temperature in infinite and in finite volume with the quark-meson model. Though qualitatively correct, our results suggest that the model does not describe the dynamics of QCD near the finite-temperature phase boundary accurately. Second, we study the approach to chiral symmetry breaking in terms of quarks and gluons. We compute the running QCD coupling for all temperatures and scales. We use this result to determine quantitatively the phase boundary in the plane of temperature and number of quark flavors and find good agreement with lattice results. (orig.)
Computational Thermochemistry and Benchmarking of Reliable Methods
Energy Technology Data Exchange (ETDEWEB)
Feller, David F.; Dixon, David A.; Dunning, Thom H.; Dupuis, Michel; McClemore, Doug; Peterson, Kirk A.; Xantheas, Sotiris S.; Bernholdt, David E.; Windus, Theresa L.; Chalasinski, Grzegorz; Fosada, Rubicelia; Olguim, Jorge; Dobbs, Kerwin D.; Frurip, Donald; Stevens, Walter J.; Rondan, Nelson; Chase, Jared M.; Nichols, Jeffrey A.
2006-06-20
During the first and second years of the Computational Thermochemistry and Benchmarking of Reliable Methods project, we completed several studies using the parallel computing capabilities of the NWChem software and Molecular Science Computing Facility (MSCF), including large-scale density functional theory (DFT), second-order Moeller-Plesset (MP2) perturbation theory, and CCSD(T) calculations. During the third year, we continued to pursue the computational thermodynamic and benchmarking studies outlined in our proposal. With the issues affecting the robustness of the coupled cluster part of NWChem resolved, we pursued studies of the heats-of-formation of compounds containing 5 to 7 first- and/or second-row elements and approximately 10 to 14 hydrogens. The size of these systems, when combined with the large basis sets (cc-pVQZ and aug-cc-pVQZ) that are necessary for extrapolating to the complete basis set limit, creates a formidable computational challenge, for which NWChem on NWMPP1 is well suited.
International Nuclear Information System (INIS)
This book presents the analytical uses of radioactive isotopes within the context of radiochemistry as a whole. It is designed for scientists with relatively little background knowledge of the subject. Thus the initial emphasis is on developing the basic concepts of radioactive decay, particularly as they affect the potential usage of radioisotopes. Discussion of the properties of various types of radiation, and of factors such as half-life, is related to practical considerations such as counting and preparation methods, and handling/disposal problems. Practical aspects are then considered in more detail, and the various radioanalytical methods are outlined with particular reference to their applicability. The approach is 'user friendly' and the use of self assessment questions allows the reader to test his/her understanding of individual sections easily. For those who wish to develop their knowledge further, a reading list is provided. (author)
Discretization error estimation and exact solution generation using the method of nearby problems.
Energy Technology Data Exchange (ETDEWEB)
Sinclair, Andrew J. (Auburn University Auburn, AL); Raju, Anil (Auburn University Auburn, AL); Kurzen, Matthew J. (Virginia Tech Blacksburg, VA); Roy, Christopher John (Virginia Tech Blacksburg, VA); Phillips, Tyrone S. (Virginia Tech Blacksburg, VA)
2011-10-01
The Method of Nearby Problems (MNP), a form of defect correction, is examined as a method for generating exact solutions to partial differential equations and as a discretization error estimator. For generating exact solutions, four-dimensional spline fitting procedures were developed and implemented into a MATLAB code for generating spline fits on structured domains with arbitrary levels of continuity between spline zones. For discretization error estimation, MNP/defect correction only requires a single additional numerical solution on the same grid (as compared to Richardson extrapolation which requires additional numerical solutions on systematically-refined grids). When used for error estimation, it was found that continuity between spline zones was not required. A number of cases were examined including 1D and 2D Burgers equation, the 2D compressible Euler equations, and the 2D incompressible Navier-Stokes equations. The discretization error estimation results compared favorably to Richardson extrapolation and had the advantage of only requiring a single grid to be generated.
Failure Analysis of Wind Turbines by Probability Density Evolution Method
DEFF Research Database (Denmark)
Sichani, Mahdi Teimouri; Nielsen, SØren R.K.
2013-01-01
The aim of this study is to present an efficient and accurate method for estimation of the failure probability of wind turbine structures which work under turbulent wind load. The classical method for this is to fit one of the extreme value probability distribution functions to the extracted maxima of the response of wind turbine. However this approach may contain high amount of uncertainty due to the arbitrariness of the data and the distributions chosen. Therefore less uncertain methods are meaningful in this direction. The most natural approach in this respect is Monte Carlo (MC) simulation. This is not practical due to its excessive computational load. This problem can alternatively be tackled if the evolution of the probability density function (PDF) of the response process can be realized. The evolutionary PDF can then be integrated on the boundaries of the problem. For this reason we propose to use the Probability Density Evolution Method (PDEM). PDEM can alternatively be used to obtain the distribution of the extreme values of the response process by simulation. This approach requires less computational effort than integrating the evolution of the PDF; but may be less accurate. In this paper we present the results of failure probability estimation using PDEM. The results will then be compared to extrapolated values obtained from extreme value distribution fits to the sample response values. The results approve the feasibility of this approach for reliability analysis of wind turbines however they convey the potential for improving accuracy of the method in low probability areas
International Nuclear Information System (INIS)
Methods for the collection of soil samples to determine levels of 137Cs and other fallout radionuclides, such as excess 210Pb and 7Be, will depend on the purposes (aims) of the project, site and soil characteristics, analytical capacity, the total number of samples that can be analysed and the sample mass required. The latter two will depend partly on detector type and capabilities. A variety of field methods have been developed for different field conditions and circumstances over the past twenty years, many of them inherited or adapted from soil science and sedimentology. The use of them inherited or adapted from soil science and sedimentology. The use of 137Cs in erosion studies has been widely developed, while the application of fallout 210Pb and 7Be is still developing. Although it is possible to measure these nuclides simultaneously, it is common for experiments to designed around the use of 137Cs along. Caesium studies typically involve comparison of the inventories found at eroded or sedimentation sites with that of a 'reference' site. An accurate characterization of the depth distribution of these fallout nuclides is often required in order to apply and/or calibrate the conversion models. However, depending on the tracer involved, the depth distribution, and thus the sampling resolution required to define it, differs. For example, a depth resolution of 1 cm is often adequate when usiolution of 1 cm is often adequate when using 137Cs. However, fallout 210Pb and 7Be commonly has very strong surface maxima that decrease exponentially with depth, and fine depth increments are required at or close to the soil surface. Consequently, different depth incremental sampling methods are required when using different fallout radionuclides. Geomorphic investigations also frequently require determination of the depth-distribution of fallout nuclides on slopes and depositional sites as well as their total inventories
Examining the accumulated oxygen deficit method in breaststroke swimming.
Reis, Victor Machado; Marinho, Daniel Almeida; Barbosa, Fernando Policarpo; Reis, António Malvas; Guidetti, Laura; Silva, António José
2010-08-01
The present study investigated the accumulated oxygen deficit (AOD) method in breaststroke swimming with the aims to assess the reliability of the oxygen uptake/swimming velocity regression line and to quantify the precision of the AOD. Sixteen male swimmers performed two swimming tests in different days, with a 24-h recovery between tests: a graded swimming test and an all-out test. The all-out test was performed in one of two distances: 100 m (n = 7) or 200 m (n = 9). Through all testing, expired gases were collected breath by breath and analysed with a K4b2 Gas Analyser (Cosmed, Rome, Italy) connected to an AquaTrainer Valve (Cosmed, Rome, Italy). The standard error of the regression lines was approximately 5-6 ml kg(-1) min(-1) and the regressions allowed an extrapolation of the energy cost to higher intensities with a standard error of the predicted value that was lower in the 200-m bout (approximately 3.5 ml kg(-1) min(-1)) comparatively to the 100-m bout (approximately 6 ml kg(-1) min(-1)). The AOD imprecision was calculated as the square root of the sum of the oxygen uptake measurement error and the standard error of the predicted value for energy cost. AOD imprecision was smaller in the 200-m bout (approximately 9 ml kg(-1) min(-1)) comparatively to the 100-m bout (approximately 12 ml kg(-1) min(-1)). However, since the AOD values during the two distances were small, the AOD relative errors can be viewed as high. Additionally, the data variability was considerable (95% confidence intervals of the linear extrapolation larger than 20 ml kg(-1) min(-1)). PMID:20373107
Estimates of tropical bromoform emissions using an inversion method
Ashfold, M. J.; Harris, N. R. P.; Manning, A. J.; Robinson, A. D.; Warwick, N. J.; Pyle, J. A.
2014-01-01
Bromine plays an important role in ozone chemistry in both the troposphere and stratosphere. When measured by mass, bromoform (CHBr3) is thought to be the largest organic source of bromine to the atmosphere. While seaweed and phytoplankton are known to be dominant sources, the size and the geographical distribution of CHBr3 emissions remains uncertain. Particularly little is known about emissions from the Maritime Continent, which have usually been assumed to be large, and which appear to be especially likely to reach the stratosphere. In this study we aim to reduce this uncertainty by combining the first multi-annual set of CHBr3 measurements from this region, and an inversion process, to investigate systematically the distribution and magnitude of CHBr3 emissions. The novelty of our approach lies in the application of the inversion method to CHBr3. We find that local measurements of a short-lived gas like CHBr3 can be used to constrain emissions from only a relatively small, sub-regional domain. We then obtain detailed estimates of CHBr3 emissions within this area, which appear to be relatively insensitive to the assumptions inherent in the inversion process. We extrapolate this information to produce estimated emissions for the entire tropics (defined as 20° S-20° N) of 225 Gg CHBr3 yr-1. The ocean in the area we base our extrapolations upon is typically somewhat shallower, and more biologically productive, than the tropical average. Despite this, our tropical estimate is lower than most other recent studies, and suggests that CHBr3 emissions in the coastline-rich Maritime Continent may not be stronger than emissions in other parts of the tropics.
International Nuclear Information System (INIS)
An equation of state based on the properties of normal fluids, the law of rectilinear averages, and the second law of thermodynamics can be derived for advanced LMFBR fuels on the basis of the vapor pressure, enthalpy of vaporization, change in heat capacity upon vaporization, and liquid density at the melting point. The method consists of estimating an equation of state by means of the law of rectilinear averages and the second law of thermodynamics, integrating by means of the second law until an instability is reached, and then extrapolating by means of a self-consistent estimation of the enthalpy of vaporization
The numerical solution of differential-algebraic systems by Runge-Kutta methods
Hairer, Ernst; Lubich, Christian
1989-01-01
The term differential-algebraic equation was coined to comprise differential equations with constraints (differential equations on manifolds) and singular implicit differential equations. Such problems arise in a variety of applications, e.g. constrained mechanical systems, fluid dynamics, chemical reaction kinetics, simulation of electrical networks, and control engineering. From a more theoretical viewpoint, the study of differential-algebraic problems gives insight into the behaviour of numerical methods for stiff ordinary differential equations. These lecture notes provide a self-contained and comprehensive treatment of the numerical solution of differential-algebraic systems using Runge-Kutta methods, and also extrapolation methods. Readers are expected to have a background in the numerical treatment of ordinary differential equations. The subject is treated in its various aspects ranging from the theory through the analysis to implementation and applications.
International Nuclear Information System (INIS)
Purpose: To sufficiently and reliably remove contaminating materials such as residual activated materials deposited to the inner wall surfaces of a container containing radioactive materials. Method: Electrolytic cleaning is at first conducted in an electrolyte solution to release most of contaminating materials deposited to decontaminants from the surface. Then, the decontaminants after with electrolytic cleaning is subjected to ultrasonic cleaning in a poor solvent to the contaminating materials to separate the contaminating materials remaining on the surface of decontaminants or re-adsorbed contaminating materials from the electrolyte solution from the surfaces and disperse them in the poor solvent. In this way, it is possible to sufficiently and reliably remove the contaminating materials from the surface of the decontaminants. According to this method, it is no more required for the frequent replace of the electrolyte solution or the poor solvent used for the ultrasonic cleaning and minimize the amount of the decontaminating liquid wastes. Further, since water can be used as the poor solvent for use in the ultrasonic cleaning depending on the contaminating material, the decontaminating operation can be facilitated. (Kamimura, M.)
Corrosion rate measurements of welded parts of stainless steel using electrochemical method
International Nuclear Information System (INIS)
Corrosion rates of three types of welded 304 stainless steel specimens immersed in 1 N H2SO4 solution at room temperature were obtained from potentiodynamic polarization curves, Tafel plots and polarization resistance curves. Corrosion rate measurements by using AC impedance technique were also carried out in order to investigate whether these values agreed fairly well with the values obtained from other electrochemical techniques. Corrosion rates of welded specimens were increased with increasing frequency of GTAW and decreasing current density of GTAW. It was concluded that an A.C. impedance technique could be successfully utilized for determining a local corrosion rate of welded parts. (Author)
A simple and accurate method for high-temperature PEM fuel cell characterization
Kulikovsky, Andrei; Wannek, Christoph; Oetjen, Hans-friedrich
2010-01-01
Abstract A set of basic parameters for any polymer electrolyte membrane fuel cell (PEMFC) includes the Tafel slope $b$ and the exchange current density $j_*$ of the cathode catalyst, the oxygen diffusion coefficient $D_b$ in the cathode gas--diffusion layer and the cell resistivity $R_{cell}$. Based on the analytical model of a PEMFC (A.A.Kulikovsky. {\\em Electrochimica Acta} {\\bf 49} (2004) 617), we propose a two--step procedure allowing to evaluate these parameters for a high--te...
Structural Reliability of Wind Turbine Blades : Design Methods and Evaluation
DEFF Research Database (Denmark)
Dimitrov, Nikolay Krasimirov
2013-01-01
In the past decade the use of wind energy has expanded significantly, transforming a niche market into a practically mainstream energy generation industry. With the advance of turbine technology the search for more efficient solutions has lead to increased focus on probabilistic modelling and design. Reliability-based analysis methods have the potential of being a valuable tool which can improve the state of knowledge by explaining the uncertainties, and form the probabilistic basis for calibration of deterministic design tools. The present thesis focuses on reliability-based design of wind turbine blades. The main purpose is to draw a clear picture of how reliability-based design of wind turbines can be done in practice. The objectives of the thesis are to create methodologies for efficient reliability assessment of composite materials and composite wind turbine blades, and to map the uncertainties in the processes, materials and external conditions that have an effect on the health of a composite structure. The study considers all stages in a reliability analysis, from defining models of structural components to obtaining the reliability index and calibration of partial safety factors. In a detailed demonstration of the process of estimating the reliability of a wind turbine blade and blade components, a number of probabilistic load and strength models are formulated, and the following scientific and practical questions are answered: a) What material, load and uncertainty models need to be used b) How can different failure modes be taken into account c) What reliability methods are most suitable for the particular task d) Are there any factors specific to wind turbines such as materials and operating conditions that need to be taken into account e) Are there ways for improvement by developing new models and standards or carrying out tests The following aspects are covered in detail: ? The probabilistic aspects of ultimate strength of composite laminates are addressed. Laminated plates are considered asa general structural reliability system where each layer in a laminate is a separate system component. Methods for solving the system reliability are discussed in an example problem. ? Probabilistic models for fatigue life of laminates and sandwich core are developed and calibrated against measurement data. A modified, nonlinear S-N relationship is formulated where the static strength of the material is included as a parameter. A Bayesian inference model predicting the fatigue resistance of face laminates based on the static and fatigue strength of individual lamina is developed. A series of tests of the fatigue life of balsa wood core material are carried out, and a probabilistic model for the fatigue strength of balsa core subjected to transverse shear loading is calibrated to the test data. ? A review study evaluates and compares several widely-used statistical extrapolation methods for their capability of modelling the short-term statistical distribution of blade loads and tip deflection. The best performing methods are selected, and several improvements are suggested, including a procedure for automatic determination of tail threshold level, which allows for efficient automated use of peaks-over-threshold methods. ? The problem of obtaining the long-term statistical distribution of load extremes is discussed by comparing the method of integrating extrapolated short-term statistical distributions against extrapolation of data directly sampled from the long-term distribution. The comparison is based on the long-term distribution of wind speed, turbulence, and wind shear, where a model of the wind shear distribution is specifically developed for the purpose. ? Uncertainties in load and material modelling are considered. A quantitative assessment of the in uence of a number of uncertainties is done based on modelled and measured data. ? Example analyses demonstrate the process of estimating the reliability against several modes of failure in two different structures. This includes reliability against blade-to
Marsden, Kenneth C.; Meyer, Mitchell K.; Grover, Blair K.; Fielding, Randall S.; Wolfensberger, Billy W.
2012-12-18
A casting device includes a covered crucible having a top opening and a bottom orifice, a lid covering the top opening, a stopper rod sealing the bottom orifice, and a reusable mold having at least one chamber, a top end of the chamber being open to and positioned below the bottom orifice and a vacuum tap into the chamber being below the top end of the chamber. A casting method includes charging a crucible with a solid material and covering the crucible, heating the crucible, melting the material, evacuating a chamber of a mold to less than 1 atm absolute through a vacuum tap into the chamber, draining the melted material into the evacuated chamber, solidifying the material in the chamber, and removing the solidified material from the chamber without damaging the chamber.
International Nuclear Information System (INIS)
MRI has become the imaging method of choice in special regions of the head and neck (e.g. nasopharynx, oropharynx, oral cavity, floor of the mouth). Superconducting MR-equipment with field strengths of 1.0-1.5 T are appropriate for the evaluation of the head and neck region.. Signal acquisition is optimal with circular polarized head coils or with specially designed surface coils; the body coil is insufficient. When imaging tumors we need T1 contrast, T2 contrast and contrast medium information (enhancement information). For the T1 contrast T1-spin-echo is and remains the best sequence. For T2-contrast T2 turbo-spin-echo with fat suppression has replaced the T2 spin-echo sequences because it is faster and shows good contrast between tumor and saturated fat tissue. Fat saturated T1 turbo-spin-echo enables best tissue contrast after Gd-DTPA application