Epidemic routing can deliver messages in the case where there is never a connected path from source to destination. By using Epidemic routing repeatedly, the technique called Information Floating can maintain information in specific area. Information Floating is more effective when there are many mobile nodes. We consider effect of public space on information floating. A public space is a social space and mobile nodes are easy to gather in the space. If we can identify a place that is not a public space but where information tends to stay, it will maintain more information. We introduce to use a covering problem to identify this place. A covering problem is one of location problems that find the best place on road networks, communication networks, etc. In this paper, we identify where to put the fixed stations with information by applying a covering problem, and we show its effectiveness in computer simulation.

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  A variety of Krylov subspace methods for solving linear systems with nonsymmetric coefficient matrix have been proposed by many researchers. For example, BiCGStab method, BiCGSafe method and Rutishauser type of GPBiCG method and so on are listed. In this paper, we focus on Rutishauser type of BiCGSafe method for solving linear systems with nonsymmetric coefficient matrix which appear in various engineering simulations. As a result, it turned out that our proposed variant of BiCGSafe method can stabilizedly solve nonsymmetric problems in engineering simulations.

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  This study examined a novel intra-body communication method using magnetic coupling. In order to design a communication device using magnetically coupled intra-body communication, it is important to well understand the signal path loss characteristics in a human body and develop a technology so as to minimize its path loss. This study calculated the signal path loss in a variety of magnetic couplings by computer simulation. The magnetic couplings analyzed include normal inductive coupling (non-resonant coupling) and two types of resonant couplings. The 3D finite element model incorporating circuit elements was used for the examination. Results of the frequency characteristics of the signal path loss reveal that the optimal frequency band was between 2 MHz and 4 MHz for inductive coupling. In addition, one of the resonant couplings could improve the signal path loss by approximately 20 dB at a resonant frequency of 2 MHz. Also, in order to verify the validity of the simulation results, this study actually measured the signal path loss. As a result, it was confirmed that the simulation and the measurement results almost agreed.

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  For gainging high speedup of Conjugate Gradient method on parallel computer, it is cricial to reduce the number of synchro. points which stem from the operation of inner point. Therefore, we consider on relationship between rounding error and CG method with reduction of the number of synchro. points in parallel computing. Through numerical experimnts, it turned out that CG method with reduction of the number of synchro. points by A. Chronopoulos is greatly affected by rounding error caused by finite floating-point arithmetics of inner products.

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