The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Ekkard Schnedermann - One of the best experts on this subject based on the ideXlab platform.
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the Inverse Laplace Transform as the ultimate tool for transverse mass spectra
European Physical Journal C, 1994Co-Authors: Ekkard SchnedermannAbstract:New high statistics data from the second generation of ultrarelativistic heavy-ion experiments open up new possibilities in terms of data analysis. To fully utilize the potential we propose to analyze them⊥-spectra of hadrons using the Inverse Laplace Transform. The problems with its inherent ill-definedness can be overcome and several applications in other fields like biology, chemistry or optics have already shown its feasibility. Moreover the method also promises to deliver upper bounds on the total information content of the spectra, which is of big importance for all other means of analysis. Here we compute several Laplace inversions from different thermal scenarios both analytically and numerically to test the efficiency of the method. Especially the case of a two component structure, related to a possible first order phase transition to a quark gluon plasma, is closer investigated and it is shown that at least a signal to noise ratio of 104 is necessary to resolve two individual components.
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the Inverse Laplace Transform as the ultimate tool for transverse mass spectra
arXiv: Nuclear Theory, 1994Co-Authors: Ekkard SchnedermannAbstract:New high statistics data from the second generation of ultrarelativistic heavy-ion experiments open up new possibilities in terms of data analysis. To fully utilize the potential we propose to analyze the $m_\perp$-spectra of hadrons using the Inverse Laplace Transform. The problems with its inherent ill-definedness can be overcome and several applications in other fields like biology, chemistry or optics have already shown its feasability. Moreover, the method also promises to deliver upper bounds on the total information content of the spectra, which is of big importance for all other means of analysis. Here we compute several Laplace inversions from different thermal scenarios, both analytically and numerically, to test the efficiency of the method. Especially the case of a two component structure, related to a possible first order phase transition to a quark gluon plasma, is closer investigated and it is shown that at least a signal to noise ratio of $10^4$ is necessary to resolve two individual components.
Jerdvisanop Chakarothai - One of the best experts on this subject based on the ideXlab platform.
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novel fdtd scheme for analysis of frequency dependent medium using fast Inverse Laplace Transform and prony s method
IEEE Transactions on Antennas and Propagation, 2019Co-Authors: Jerdvisanop ChakarothaiAbstract:A novel finite-difference time-domain (FDTD) approach is proposed for the analysis of wave propagation in a general frequency-dependent medium. In the proposed method, formulation of the fractional derivatives in the time-domain representation is circumvented by using the fast Inverse Laplace Transform (FILT) and Prony’s method. The FILT is used to Transform the dispersion expressed in a frequency-domain response into a time-domain response, and Prony’s method is utilized to extract the parameters and Transform the time-domain responses into those in the z -domain so that they can be incorporated into the FDTD method directly. The update equation of the electric field in the FDTD method is then formulated by using the z -Transformation. Stability analysis of the proposed scheme is also investigated by means of the root-locus method. Reflection coefficients of dispersive media, such as Debye, Cole–Cole, Davidson–Cole, and Havriliak–Negami media simulated in a 1-D domain and a three-layered biological medium of skin, fat, and muscle tissues inside a waveguide with a TE10 fundamental mode in a 2-D domain, are found to be in good agreement with those obtained by an analytical method over a broad frequency range, demonstrating the validity of the proposed FDTD scheme.
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Novel FDTD Scheme for Analysis of Frequency- Dependent Medium Using Fast Inverse Laplace Transform and Prony’s Method
IEEE Transactions on Antennas and Propagation, 2019Co-Authors: Jerdvisanop ChakarothaiAbstract:A novel finite-difference time-domain (FDTD) approach is proposed for the analysis of wave propagation in a general frequency-dependent medium. In the proposed method, formulation of the fractional derivatives in the time-domain representation is circumvented by using the fast Inverse Laplace Transform (FILT) and Prony's method. The FILT is used to Transform the dispersion expressed in a frequency-domain response into a time-domain response, and Prony's method is utilized to extract the parameters and Transform the time-domain responses into those in the z-domain so that they can be incorporated into the FDTD method directly. The update equation of the electric field in the FDTD method is then formulated by using the z-Transformation. Stability analysis of the proposed scheme is also investigated by means of the root-locus method. Reflection coefficients of dispersive media, such as Debye, Cole-Cole, Davidson-Cole, and Havriliak-Negami media simulated in a 1-D domain and a three-layered biological medium of skin, fat, and muscle tissues inside a waveguide with a TE10 fundamental mode in a 2-D domain, are found to be in good agreement with those obtained by an analytical method over a broad frequency range, demonstrating the validity of the proposed FDTD scheme.
Richard G. Spencer - One of the best experts on this subject based on the ideXlab platform.
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Stabilization of the Inverse Laplace Transform of multiexponential decay through introduction of a second dimension.
Journal of Magnetic Resonance, 2013Co-Authors: Hasan Celik, Mustapha Bouhrara, David A. Reiter, Kenneth W. Fishbein, Richard G. SpencerAbstract:We propose a new approach to stabilizing the Inverse Laplace Transform of a multiexponential decay signal, a classically ill-posed problem, in the context of nuclear magnetic resonance relaxometry. The method is based on extension to a second, indirectly detected, dimension, that is, use of the established framework of two-dimensional relaxometry, followed by projection onto the desired axis. Numerical results for signals comprised of discrete T1 and T2 relaxation components and experiments performed on agarose gel phantoms are presented. We find markedly improved accuracy, and stability with respect to noise, as well as insensitivity to regularization in quantifying underlying relaxation components through use of the two-dimensional as compared to the one-dimensional Inverse Laplace Transform. This improvement is demonstrated separately for two different inversion algorithms, non-negative least squares and non-linear least squares, to indicate the generalizability of this approach. These results may have wide applicability in approaches to the Fredholm integral equation of the first kind.
Terumichi Nakagawa - One of the best experts on this subject based on the ideXlab platform.
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Analysis of arterial–venous blood concentration difference of drugs based on recirculatory theory with fast Inverse Laplace Transform (FILT)
Journal of pharmacokinetics and biopharmaceutics, 1991Co-Authors: Yoshitaka Yano, Kiyoshi Yamaoka, Hiroyuki Yasui, Terumichi NakagawaAbstract:An arterial and venous blood (or plasma) concentration difference of drugs across the lung of rats was evaluated based on the recirculatory concept. The recirculatory system is given by the combination of the transfer functions for the pulmonary and the systemic circulations and is described by a Laplace-Transformed equation, i.e., an image equation. For the manipulation of the image equations, the fast Inverse Laplace Transform (FILT) was adopted and MULTI(FILT) was used for the simultaneous curve fitting to estimate the pharmacokinetic parameters in the recirculatory model. Metoprolol as a test drug and cephalexin as a control drag were infused, respectively into the femoral vein for 30 min, and arterial and venous blood samples were collected simultaneously through the cannula at the femoral artery and at right atrium during and after the infusion. Exponential functions were assumed for the weight functions through both the pulmonary and systemic circulations. Results of the curve fitting showed that the single-pass extraction ratio through the pulmonary circulation (Ep)of meloprolol was about 0.2, whereas that of cephalexin was negligible. The mean transit times through the pulmonary circulation (¯tpof metoprolol and cephalexin were both about 0.5 min, which is small. The singlepass extraction ratios through the systemic circulation (Es)of metoprolol and cephalexin were both about 0.1. and the mean transit times through the systemic circulation (¯tswere 11.5 min and 8.2 min, respectively.
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analysis of arterial venous blood concentration difference of drugs based on recirculatory theory with fast Inverse Laplace Transform filt
Journal of Pharmacokinetics and Biopharmaceutics, 1991Co-Authors: Yoshitaka Yano, Kiyoshi Yamaoka, Hiroyuki Yasui, Terumichi NakagawaAbstract:An arterial and venous blood (or plasma) concentration difference of drugs across the lung of rats was evaluated based on the recirculatory concept. The recirculatory system is given by the combination of the transfer functions for the pulmonary and the systemic circulations and is described by a Laplace-Transformed equation, i.e., an image equation. For the manipulation of the image equations, the fast Inverse Laplace Transform (FILT) was adopted and MULTI(FILT) was used for the simultaneous curve fitting to estimate the pharmacokinetic parameters in the recirculatory model. Metoprolol as a test drug and cephalexin as a control drag were infused, respectively into the femoral vein for 30 min, and arterial and venous blood samples were collected simultaneously through the cannula at the femoral artery and at right atrium during and after the infusion. Exponential functions were assumed for the weight functions through both the pulmonary and systemic circulations. Results of the curve fitting showed that the single-pass extraction ratio through the pulmonary circulation (Ep)of meloprolol was about 0.2, whereas that of cephalexin was negligible. The mean transit times through the pulmonary circulation (¯tpof metoprolol and cephalexin were both about 0.5 min, which is small. The singlepass extraction ratios through the systemic circulation (Es)of metoprolol and cephalexin were both about 0.1. and the mean transit times through the systemic circulation (¯tswere 11.5 min and 8.2 min, respectively.
Shinichiro Ohnuki - One of the best experts on this subject based on the ideXlab platform.
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Optimal Parallel Algorithm of Fast Inverse Laplace Transform for Electromagnetic Analysis
IEEE Antennas and Wireless Propagation Letters, 2020Co-Authors: Seiya Kishimoto, Shinichiro OhnukiAbstract:Fast Inverse Laplace Transform (FILT) is a simple and concise technique for performing Inverse Laplace Transforms. This letter develops an efficient parallel algorithm for FILT for solving various electromagnetic problems. This algorithm can be easily combined with existing computational methods used in electromagnetics to realize efficient time- and frequency-domain analyses.
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time domain analysis of electromagnetic fields using the fast Inverse Laplace Transform
Progress in Electromagnetic Research Symposium, 2016Co-Authors: Shinichiro Ohnuki, S Watanabe, K NagasawaAbstract:Time-domain analysis of electromagnetic fields is indispensable for developing target identification, designing microwave devices, studying optical properties of materials, and so on. Many commercial softwares based on time-domain solvers are available and they are useful for practical applications of industrial design and modeling. However, it is still difficult to evaluate accuracy and reliability, since reference solutions of time-domain responses are quite limited. In this presentation, time domain responses of scattered waves from canonical structures are investigated using the fast Inverse Laplace Transform (FILT). In our method, the waves are firstly obtained in the complex frequency s domain. Next, the waves in the s domain are numerically Transformed into the time domain using FILT. Our method has advantage to estimate and control computational error easily, and arbitrary sampling points in time can be selected. We demonstrate that time domain responses of scattered waves from canonical structures are computed for various shapes of the incident pulses and materials. Our results are reliable and highly accurate, and they are considered as reference solutions of time-domain electromagnetic fields.
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efficient analysis of electromagnetic fields for designing nanoscale antennas by using a boundary integral equation method with fast Inverse Laplace Transform
Progress in Electromagnetics Research-pier, 2014Co-Authors: Seiya Kishimoto, Shinichiro Ohnuki, Yoshito Ashizawa, Tatsuichiro Okada, Katsuji NakagawaAbstract:In this paper, we investigate electromagnetic problems for nanoscale antennas by using a boundary integral equation method with fast Inverse Laplace Transform. The antennas are designed for realizing ultra-fast and high-density magnetic recording. Characteristics of nanoscale antennas are discussed in terms of eigenmodes and time domain responses of electric flelds. Our computational method is highly e-cient and the computational cost can be reduced by selecting coarse time-step size and performing parallel computation.
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Time-domain analysis of electromagnetic problems for nanoscale objects by integral equation methods with fast Inverse Laplace Transform
2013 USNC-URSI Radio Science Meeting (Joint with AP-S Symposium), 2013Co-Authors: Seiya Kishimoto, Shinichiro Ohnuki, Yoshito Ashizawa, Katsuji Nakagawa, Shao Ying Huang, Weng Cho ChewAbstract:Summary form only given: For ultra-fast and ultra-high density magnetic recording, all-optical magnetic recording has attracted attention. This state-of-the-art technology needs circularly polarized light. In this report, we propose a novel computational method to design the plasmonic antennas which generate localized circular polarized light for high-density recording. We will discuss characteristics of the antenna in terms of the time response of electromagnetic fields and Stokes parameters. Our proposed method is based on the combination of integral equation methods and fast Inverse Laplace Transform (FILT). The integral equation method, the boundary integral equation method (BIEM) using the static approximation or Poggio-Miller-Chang-Harrigton-Wu-Tsai (PMCHWT) method, is considered and extended in the complex frequency. The electromagnetic fields in the complex frequency domain can be obtained by the integral equation methods and Transformed into the time-domain by using fast Inverse Laplace Transform (FILT). Our method can perform reliable and fast simulation, with the following advantages: (1) the computational error is easy to be controlled; (2) the solution at each observation time can be calculated independently; (3) the time step size can be selected as an arbitrary number; and (4) high parallel efficiency can be obtained.
