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Article type: Cover
2008 Volume 18 Issue 3 Pages
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Article type: Cover
2008 Volume 18 Issue 3 Pages
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Article type: Index
2008 Volume 18 Issue 3 Pages
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Article type: Appendix
2008 Volume 18 Issue 3 Pages
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[in Japanese]
Article type: Article
2008 Volume 18 Issue 3 Pages
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Published: September 25, 2008
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Kensuke Aishima, Takayasu Matsuo, Kazuo Murota, Masaaki Sugihara
Article type: Article
2008 Volume 18 Issue 3 Pages
285-302
Published: September 25, 2008
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Algorithms of quotient-difference type for computing singular values have recently attracted revived interest. In particular, the dqds algorithm, being numerically stable, is now recognized as an effective method in practice, where an appropriate setting of the shifts is indispensable for accelerating the convergence. In this report we propose a simple shift strategy that is theoretically guaranteed to render asymptotic superquadratic convergence. We also present a numerical example demonstrating the superquadratic convergence.
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Takashi Komori, Nobito Yamamoto
Article type: Article
2008 Volume 18 Issue 3 Pages
303-319
Published: September 25, 2008
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We propose a numerical verification method for initial value problems(IVP) of ODEs in order to enclose the solutions at the end time by considerably small bounds. The method is based on Nakao's theory which is established for numerical verification methods for PDEs. We construct boundary value problems(BVP) of ODEs whose solutions can be used to define the bounds of the solutions to the IVP. Then Nakao's theory is applied to the BVPs. Numerical examples are shown to compare our method with existing validated computation methods for ODEs.
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Kiyoshi Osawa, Kento Aida
Article type: Article
2008 Volume 18 Issue 3 Pages
321-346
Published: September 25, 2008
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In this paper, we propose a method to calculate winning percentages in baseball games. In conventional methods the probabilities derived from batting statistics are applied to Markov chain with the D'Esopo and Lefkowitz runner advancement model in order to calculate the percentage. The proposed method calculates the percentage by analyzing not only batting statistics but also runners' advancement statistics. The experimental results show that the percentage calculated by the proposed method is closer to the actual results compared to the conventional methods. In addition, we evaluate the effect of batting statistics and runners' statistics on the winning percentage.
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Keichiro Kashiwagi, Shinya Miyajima, Masahide Kashiwagi
Article type: Article
2008 Volume 18 Issue 3 Pages
347-362
Published: September 25, 2008
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We are able to obtain all solutions of the systems of nonlinear equations with guaranteed accuracy applying a known algorithm using interval analysis. But this algorithm has serious problem of calculating cost. On the other hand, numerical calculation using GPU is also active recently, which is called GPGPU. The purpose of this paper is to propose the fast parallel all solution algorithm using GPU and CPU. Moreover this paper shows the efficiency of this all solution algorithm through some numerical examples.
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Masahiro Kimura, Kazumi Saito
Article type: Article
2008 Volume 18 Issue 3 Pages
363-388
Published: September 25, 2008
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We propose a new unsupervised learning method called PMM-PCA for efficiently extracting the major latent topics in a document stream based on the "bag-of-words" (BOW) representation of a document. Unlike PCA, PMM-PCA follows a suitable probabilistic generative model for the document stream represented as time-series of word-frequency vectors. Using real data of document streams on the Web, we experimentally demonstrate the effectiveness of the proposed method.
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Motoki Katayama, Kinji Kimura, Masami Takata, Hiroaki Tsuboi, Masashi ...
Article type: Article
2008 Volume 18 Issue 3 Pages
389-407
Published: September 25, 2008
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In this paper, computation of left singular vectors by the I-SVD algorithm for fast bidagonal SVD is improved so that the computed left singular vectors have better orthogonality and accuracy. The efficiency of improved I-SVD is evaluated through numerical experimentations.
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Akiko Fukuda, Emiko Ishiwata, Masashi Iwasaki, Yoshimasa Nakamura
Article type: Article
2008 Volume 18 Issue 3 Pages
409-425
Published: September 25, 2008
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The discrete hungry Lotka-Volterra (dhLV) system is a generalization of the discrete Lotka-Volterra (dLV) system which stands for a prey-predator model in mathematical biology. In this paper, we show an existence of some invariants, which are independent of the discrete time n, expressed by dhLV variables and the asymptotic behavior of dhLV variables as n→∞, Some characteristic polynomials are then factorized with the help of dhLV system. We design an algorithm for computing complex eigenvalues of a certain band matrix.
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Hirofumi Notsu, Masahisa Tabata
Article type: Article
2008 Volume 18 Issue 3 Pages
427-445
Published: September 25, 2008
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A combined finite element scheme with a pressure stabilization and a characteristic-curve method of first order in time increment is presented for the Navier-Stokes equations. We use P1/P1 element and the resulting linear system is symmetric. Numerical results in two and three dimensional problems are presented.
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Takaharu Yaguchi
Article type: Article
2008 Volume 18 Issue 3 Pages
447-471
Published: September 25, 2008
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Since the computational resources are finite, one must truncate the computational domain into finite when he/she simulates waves in an unbounded region. However this truncation gives rise to artificial boundaries and boundary conditions on such the artificial boundaries greatly affect the quality of the numerical solutions. In this paper restricting ourselves to compressible inviscid isentropic flows we derive an artificial boundary condition and an energy-type estimate under that condition. Futhermore the obtained boundary condition is shown to be equivalent to the well-known Thompson boundary condition.
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Takafumi Suzuki, Shingo Iwami, Yasuhiro Takeuchi
Article type: Article
2008 Volume 18 Issue 3 Pages
473-486
Published: September 25, 2008
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In China, government commenced a compulsory program for the vaccination of all poultry in September 2005. We construct a simple mathematical model about the vaccination strategy. Our mathematical analysis, interestingly, reveals a situation that an increase of vaccination rate can lead to an increase of the number of total infected birds. This implies that the vaccination strategy which is aimed at preventing the disease spread assists the disease spread. In this paper, we investigate the "paradox of vaccination strategy" and obtain conditions of the paradox.
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Takayuki Yamada, Shintaro Yamasaki, Shinji Nishiwaki, Kazuhiro Izui, M ...
Article type: Article
2008 Volume 18 Issue 3 Pages
487-505
Published: September 25, 2008
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Structural optimization based on the level set method is a relatively new type of structural optimization that implicitly represents the outlines of a target structure, and allows topological changes as well as shape changes during the optimization process. One current major issue concerning this optimization method is that material boundaries in the admissible domain are unintentionally fixed when the level set function is updated, and as a result, inappropriate optimal configurations are obtained. To mitigate this problem, this paper proposes a new boundary setting method incorporating Dirichlet boundary conditions for the level set function.
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Article type: Appendix
2008 Volume 18 Issue 3 Pages
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Article type: Appendix
2008 Volume 18 Issue 3 Pages
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Article type: Appendix
2008 Volume 18 Issue 3 Pages
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Article type: Index
2008 Volume 18 Issue 3 Pages
Toc2-
Published: September 25, 2008
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Article type: Cover
2008 Volume 18 Issue 3 Pages
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Published: September 25, 2008
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Article type: Cover
2008 Volume 18 Issue 3 Pages
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