Minami S.,University of Tokyo |
Kawai H.,Tokyo University of Science, Suwa |
Yoshimura S.,University of Tokyo
Computational Mechanics | Year: 2012
Parallel BDD-based monolithic algorithms for acoustic fluid-structure interaction problems are developed. In a previous study, two schemes, NN-I + CGC-FULL and NN-I + CGC-DIAG, have been proven to be efficient among several BDD-type schemes for one processor. Thus, the parallelization of these schemes is discussed in the present study. These BDD-type schemes consist of the operations of the Schur complement matrix-vector (Sv) product, Neumann-Neumann (NN) preconditioning, and the coarse problem. In the present study, the Sv product and NN preconditioning are parallelized for both schemes, and the parallel implementation of the solid and fluid parts of the coarse problem is considered for NN-I + CGC-DIAG. The results of numerical experiments indicate that both schemes exhibit performances that are almost as good as those of single solid and fluid analyses in the Sv product and NN preconditioning. Moreover, NN-I + CGC-DIAG appears to become more efficient as the problem size becomes large due to the parallel calculation of the coarse problem. © 2012 Springer-Verlag.
Ooshima M.,Tokyo University of Science, Suwa |
Takeuchi C.,OGIHARA.MFG. Co.
IEEE Transactions on Industry Applications | Year: 2011
This paper presents the experiment results from the testing of a magnetic suspension system in a bearingless brushless dc motor. This machine is suitable for use in small liquid pumps. The bearingless motor structure, the principle of the suspension force generation, and the magnetic suspension control strategy are proposed by the author. A prototype bearingless brushless dc motor is designed using computed results from a finite-element method simulation of the system. The simulation is experimentally verified using a prototype machine where the rotor is successfully suspended without mechanical contact when it drives a liquid pump at the maximum rotational speed of 2200 r/min and the maximum fluid flow of 8.2 L/min. This result shows that the proposed bearingless brushless dc motor is suitable as the drive for small liquid pumps. © 2011 IEEE.
Nara M.,Tokyo University of Science, Suwa
Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B | Year: 2012
We researched concerning the new energy technology of producing the hydrogen gases with the organic refuse by using sunlight and phototropic bacteria. Electricity can be generated by supplying the produced hydrogen gases to the fuel cell. Hydrogen production efficiency enough to put it to practical use has not been obtained in the past though a full-scale experiment for the hydrogen production that uses algae and the microorganism that does the photosynthesis has been conducted. That is, the cost performance for practical use is not obtained. We did an experimental research that used the wavelength conversion material of sunlight and the optical reflection material of the aluminum foil as a method for the efficiency gain of the hydrogen production. As a result, the design parameter of the system to produce hydrogen with the waste fluid by using the purple non-sulfur bacteria that carried out photosynthesis was able to be decided. Substrate (The sugar manufacture waste fluid: [Molasses]) dosage in which the highest incidence of hydrogen was obtained was 0.4mg/100kcells * day for the pure culture system. Moreover, the improvement of the hydrogen production efficiency of about 15% was obtained in the maximum with a light wave length conversion net. A design parameter of the biomass hydrogen energy production system and basic data concerning the efficiency gain of the system were able to be obtained from the above-mentioned results. © 2012 The Japan Society of Mechanical Engineers.
Aihara S.I.,Tokyo University of Science, Suwa |
Bagchi A.,University of Twente
International Journal of Innovative Computing, Information and Control | Year: 2010
We consider a slight perturbation of the Hull-White short rate model and result in modified forward rate equation as studied in . We develop the general frame-work of the Kalman filter for the stochastic hyperbolic system for the factor process of bonds. The noise covariance parameters included in the systems are estimated by calcu-lating the quadratic variation of observation data. The market price of risk parameters are then identified with the aid of the maximum likelihood method. © 2010 ISSN.
Aihara S.,Tokyo University of Science, Suwa |
Bagchi A.,University of Twente
International Journal of Innovative Computing, Information and Control | Year: 2012
We consider the adaptive filtering problem for estimating the randomly changing risk premium and its system parameters for zero-coupon bond models. The term structure model for a zero-coupon bond is formulated including the stochastic risk-premium factor. We specify our observation data from the yield curve and bond data which are used to hedge some option claims. For the fixed system parameters, the Kalman filter for the risk-premium and the factor process is constructed first. Secondly, by using the parallel filtering technique and resampling technique commonly used in particle filters, the on-line estimation algorithm for model parameters is constructed. Some simulation studies are finally presented. © 2012 ISSN 1349-4198.