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Transformation Method (transformation + method)
Selected AbstractsFluctuating Helium Emission in Optically Thick Divertor PlasmasCONTRIBUTIONS TO PLASMA PHYSICS, Issue 1-3 2008F. B. Rosmej Abstract Simulations of the helium radiative properties carried out with the recently developed multi-level meta-stable resolved collisional-radiative code SOPHIA discovered new unique emission lines to analyze optically thick divertor plasmas relevant for ITER. The comparison of their time dependent line emission obtained from the NAGDIS-II plasma simulator experiments with time dependent temperature probe measurements shows a strong correlation. This indicates that line intensity fluctuations can be transformed to the important quantities of density and temperature fluctuations. A transformation method based on integral line intensity ratios which can be recorded with high time resolution is discussed. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Kinematic transformations for planar multi-directional pseudodynamic testingEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 9 2009Oya Mercan Abstract The pseudodynamic (PSD) test method imposes command displacements to a test structure for a given time step. The measured restoring forces and displaced position achieved in the test structure are then used to integrate the equations of motion to determine the command displacements for the next time step. Multi-directional displacements of the test structure can introduce error in the measured restoring forces and displaced position. The subsequently determined command displacements will not be correct unless the effects of the multi-directional displacements are considered. This paper presents two approaches for correcting kinematic errors in planar multi-directional PSD testing, where the test structure is loaded through a rigid loading block. The first approach, referred to as the incremental kinematic transformation method, employs linear displacement transformations within each time step. The second method, referred to as the total kinematic transformation method, is based on accurate nonlinear displacement transformations. Using three displacement sensors and the trigonometric law of cosines, this second method enables the simultaneous nonlinear equations that express the motion of the loading block to be solved without using iteration. The formulation and example applications for each method are given. Results from numerical simulations and laboratory experiments show that the total transformation method maintains accuracy, while the incremental transformation method may accumulate error if the incremental rotation of the loading block is not small over the time step. A procedure for estimating the incremental error in the incremental kinematic transformation method is presented as a means to predict and possibly control the error. Copyright © 2009 John Wiley & Sons, Ltd. [source] Heat transfer characteristics in a two-dimensional channel with an oscillating wallHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 4 2001Masahide Nakamura Abstract Numerical calculations have been carried out for the laminar heat transfer in a two-dimensional channel bounded by a fixed wall and an oscillating wall. In this calculation, the moving boundary problem was transformed into a fixed boundary problem using the coordinate transformation method, and the fully implicit finite difference method was used to solve the mass, momentum, and energy conservation equations. The calculated results are summarized as follows: (i) The wall oscillation has an effect of enhancing the heat transfer and an effect of increasing the additional pressure loss. (ii) An optimum Strouhal number for the enhancement of heat transfer exists, and this optimum value is strongly affected by the amplitude of wall oscillation. © 2001 Scripta Technica, Heat Trans Asian Res, 30(4): 280,292, 2001 [source] Poroelastic model for pile,soil interaction in a half-space porous medium due to seismic wavesINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 1 2008Jian-Fei Lu Abstract In this paper, frequency domain dynamic response of a pile embedded in a half-space porous medium and subjected to P, SV seismic waves is investigated. According to the fictitious pile methodology, the problem is decomposed into an extended poroelastic half-space and a fictitious pile. The extended porous half-space is described by Biot's theory, while the fictitious pile is treated as a bar and a beam and described by the conventional 1-D structure vibration theory. Using the Hankel transformation method, the fundamental solutions for a half-space porous medium subjected to a vertical or a horizontal circular patch load are established. Based on the obtained fundamental solutions and free wave fields, the second kind of Fredholm integral equations describing the vertical and the horizontal interaction between the pile and the poroelastic half-space are established. Solution of the integral equations yields the dynamic response of the pile to plane P, SV waves. Numerical results show the parameters of the porous medium, the pile and incident waves have direct influences on the dynamic response of the pile,half-space system. Significant differences between conventional single-phase elastic model and the poroelastic model for the surrounding medium of the pile are found. Copyright © 2007 John Wiley & Sons, Ltd. [source] Analysis of velocity equation of steady flow of a viscous incompressible fluid in channel with porous wallsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 9 2010M. Babaelahi Abstract Steady flow of a viscous incompressible fluid in a channel, driven by suction or injection of the fluid through the channel walls, is investigated. The velocity equation of this problem is reduced to nonlinear ordinary differential equation with two boundary conditions by appropriate transformation and convert the two-point boundary-value problem for the similarity function into an initial-value problem in which the position of the upper channel. Then obtained differential equation is solved analytically using differential transformation method and compare with He's variational iteration method and numerical solution. These methods can be easily extended to other linear and nonlinear equations and so can be found widely applicable in engineering and sciences. Copyright © 2009 John Wiley & Sons, Ltd. [source] Isospectral potentials for the Schrödinger equation with a position-dependent mass: Free-particle potential modelINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 14 2009J. Morales Abstract In this work, a method to obtain exactly solvable potentials for the one-dimensional Schrödinger equation with a position-dependent mass (SEPDM) and a procedure to determine their isospectral potential partners are presented. In the first case, the problem of exactly solvable SEPDM is worked by means of the point canonical transformation method which permit to convert the SEPDM problem into a standard Schrödinger-like equation with a position-independent mass (SLEPIM). In the second case, the procedure to obtain the partner isospectral potentials that fulfill with the SEPDM involves the Darboux transform applied to the SLEPIM. As example of the usefulness of the proposals, it is considered the special case of the free particle potential model as former potential of the SEPDM which leads to different exactly solvable potentials, and to their isospectral partners, depending on the choice of the position-dependent mass distribution. The proposals are general and can be used in the search of those potentials leading to exactly solvable SEPDM and their isospectral partners, which could be useful in the modeling of quantum chemical properties in condensed matter applications. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] A new non-linear sliding-mode torque and flux control method for an induction machine incorporating a sliding-mode flux observerINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 5 2004Fang Chen Abstract In this paper a novel sliding-mode control algorithm, based on the differential geometry state-co-ordinates transformation method, is proposed to control motor torque directly. Non-linear feedback linearization theory is employed to decouple the control of rotor flux magnitude and motor torque. The advantages of this method are: (1) The rotor flux and the generated torque can be accurately controlled. (2) Robustness with respect to matched and mismatched uncertainties is obtained. Additionally, a varying continuous control term is proposed. As a result, chattering is eliminated without sacrificing robustness and precision. The control strategy is based on all motor states being available. In practice the rotor fluxes are not usually measurable, and a sliding-mode observer is derived to estimate the rotor flux. The observer is designed to possess invariant dynamic modes which can be assigned independently to achieve the desired performance. Furthermore, it can be shown that the observer is robust against model uncertainties and measurement noise. Simulation and practical results are presented to confirm the characteristics of the proposed control law and rotor flux observer. Copyright © 2004 John Wiley & Sons, Ltd. [source] Evaluation of double-crystal SANS data influenced by multiple scatteringJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-1 2000aroun Evaluation of small-angle neutron scattering (SANS) data is often complicated by multiple scattering effects if large particles of relatively high volume fraction have to be studied and dilution or contrast reduction is impossible. The use of pin-hole SANS instruments is often limited due to the contradictory requirements of high resolution and short wavelength needed to keep scattering contrast as low as possible. Double crystal (DC) SANS diffractometers of Bonse-Hart and bent-crystal type are useful alternatives in such cases, as they permit reaching very high resolution with thermal neutrons. A method for SANS data evaluation suited to DC instruments is presented. It includes the common scheme of the indirect Fourier transformation method, but takes multiple scattering into account. The scattering medium is described by the frequency function g(x) defined as the cosine Fourier transform of slit-smeared data. Although a simplistic model of polydisperse spheres is used to represent g(x), resulting g(x) function and some integral parameters are independent of this model. Tests on simulated data show, that the method reproduce well true values of microstructural parameters, though systematic errors are observed in the cases when the unscattered part of incident beam completely disappears. If the scattering power A variable time transformation method for mixed-integer optimal control problemsOPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 3 2006Matthias Gerdts Abstract The article discusses a variable time transformation method for the approximate solution of mixed-integer non-linear optimal control problems (MIOCP). Such optimal control problems enclose real-valued and discrete-valued controls. The method transforms MIOCP using a discretization into an optimal control problem with only real-valued controls. The latter can be solved efficiently by direct shooting methods. Numerical results are obtained for a problem from automobile test-driving that involves a discrete-valued control for the gear shift of the car. The results are compared to those obtained by Branch&Bound and show a drastic reduction of computation time. This very good performance makes the suggested method applicable even for many discretization points. Copyright © 2006 John Wiley & Sons, Ltd. [source] Production of antibodies in plants: status after twenty yearsPLANT BIOTECHNOLOGY JOURNAL, Issue 5 2010Benoit De Muynck Summary Thanks to their potential to bind virtually all types of molecules; monoclonal antibodies are in increasing demand as therapeutics and diagnostics. To overcome the overloading of current production facilities, alternative expression systems have been developed, of which plants appear the most promising. In this review, we focus on the expression of monoclonal IgG or IgM in plant species. We analyse the data for 32 different antibodies expressed in various ways, differing in DNA construction, transformation method, signal peptide source, presence or absence of an endoplasmic reticulum retention sequence, host species and the organs tested, together resulting in 98 reported combinations. A large heterogeneity is found in the quantity and quality of the antibody produced. We discuss in more detail the strategy used to express both chains, the nature of the transcription promoters, subcellular localization and unintended proteolysis, when encountered. [source] Accelerated fatigue properties of unidirectional carbon/epoxy composite materialsPOLYMER COMPOSITES, Issue 2 2006Hsing-Sung Chen It has been confirmed that polymer matrix composites possess viscoelastic behavior. This means that one could accelerate the fatigue testing by changing the stress amplitude, frequency, or temperature. This study is to investigate the accelerated fatigue properties, which are resulted from the viscoelastic behavior, of carbon/epoxy composites and to predict their fatigue life. For this purpose, a series of fatigue tests of unidirectional specimens are conducted at room temperature under different stress ratios and stress frequencies. A group of sigmoid S-N curves, which are suitable for the whole fatigue life, and the corresponding parameters are developed for different cyclic loading conditions. A transformation method, which can transform a reference S-N curve to the corresponding S-N curve of the assigned fatigue conditions, is established by the parameters. And this S-N curve can be utilized to predict the fatigue life of the composite at the assigned stress ratio or stress frequency. The comparison between the linear and sigmoid S-N curves is also carried out to show the advantages of the latter model in the whole fatigue life. POLYM. COMPOS., 27:138,146, 2006. © 2006 Society of Plastics Engineers [source] Is Post-War Economic Growth Exponential?THE AUSTRALIAN ECONOMIC REVIEW, Issue 2 2006Sören Wibe In this article, we argue that there are strong reasons for using linear instead of exponential models when analysing post-war economic growth. Incorrect model specifications will lead to misinterpretations of the underlying economic reality and to erroneous economic forecasts. Our argument is based on an empirical investigation of real GDP per capita growth in 25 OECD countries (and three country aggregates) during the post-war period using the Box-Cox transformation method. The conclusion is that per capita growth is generally (more or less) linear (and definitely not exponential) for the level of economic development represented by these countries. Based on this we argue that analyses of growth should use linear instead of exponential models. This change of model could give new insights into problems connected with economic growth. [source] Production of the Tubulin Destabilizer Disorazol in Sorangium cellulosum: Biosynthetic Machinery and Regulatory GenesCHEMBIOCHEM, Issue 7 2005Maren Kopp Dipl.-Pharm. Abstract Myxobacteria show a high potential for the production of natural compounds that exhibit a wide variety of antibiotic, antifungal, and cytotoxic activities.1,,2 The genus Sorangium is of special biotechnological interest because it produces almost half of the secondary metabolites isolated from these microorganisms. We describe a transposon-mutagenesis approach to identifying the disorazol biosynthetic gene cluster in Sorangium cellulosum So ce12, a producer of multiple natural products. In addition to the highly effective disorazol-type tubulin destabilizers,3,5 S. cellulosum So ce12 produces sorangicins, potent eubacterial RNA polymerase inhibitors,6 bactericidal sorangiolides, and the antifungal chivosazoles.7,,8 To obtain a transposon library of sufficient size suitable for the identification of the presumed biosynthetic gene clusters, an efficient transformation method was developed. We present here the first electroporation protocol for a strain of the genus Sorangium. The transposon library was screened for disorazol-negative mutants. This approach led to the identification of the corresponding trans-acyltransferase core biosynthetic gene cluster together with a region in the chromosome that is likely to be involved in disorazol biosynthesis. A third region in the genome harbors another gene that is presumed to be involved in the regulation of disorazol production. A detailed analysis of the biosynthetic and regulatory genes is presented in this paper. [source]
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