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Koji YAMANAKA Yasunori SUZUKI Shoichi NARAHASHI Takaya WADA Makoto KAWASHIMA Ken TAKEI Kazutaka TAKAGI Atsushi HONDA Zhengyi LI Liang ZHOU Yoji OHASHI Wataru HATTORI Yusuke TAKAHASHI
This invited paper is dedicated to introduce recent activities of Japanese microwave industries. 7 topics are introduced from major microwave companies in Japan. All topics are from invited talks in 2014 Asia-Pacific microwave conference (APMC2014) held in Sendai, November, 2014.
Yoshiaki ANDO Yusuke TAKAHASHI
This paper presents an application of the constained interpolation profile basis set (CIP-BS) method to electromagnetic fields analyses. Electromagnetic fields can be expanded in terms of multi-dimensional CIP basis functions, and the Galerkin method can then be applied to obtain a system of linear equations. In the present study, we focus on a two-dimensional problem with TMz polarization. In order to examine the precision of the CIP-BS method, TE202 resonant mode in a rectangular cavity is analyzed. The numerical results show that CIP-BS method has better performance than the finite-difference time-domain (FDTD) method when the time step is small. Then an absorbing boundary condition based on the perfectly matched layer (PML) is formulated, and the absorption performance is demonstrated. Finally, the propagation in an inhomogeneous medium is computed by using the proposed method, and it is observed that in the CIP-BS method, smooth variation of material constants is effectively formulated without additional computational costs, and that accurate results are obtained in comparison with the FDTD method even if the permittivity is high.
Yusuke TAKAHASHI Taisuke IZUMI Hirotsugu KAKUGAWA Toshimitsu MASUZAWA
Using Bloom filters is one of the most popular and efficient lookup methods in P2P networks. A Bloom filter is a representation of data item indices, which achieves small memory requirement by allowing one-sided errors (false positive). In the lookup scheme besed on the Bloom filter, each peer disseminates a Bloom filter representing indices of the data items it owns in advance. Using the information of disseminated Bloom filters as a clue, each query can find a short path to its destination. In this paper, we propose an efficient extension of the Bloom filter, called a Deterministic Decay Bloom Filter (DDBF) and an index dissemination method based on it. While the index dissemination based on a standard Bloom filter suffers performance degradation by containing information of too many data items when its dissemination radius is large, the DDBF can circumvent such degradation by limiting information according to the distance between the filter holder and the items holders, i.e., a DDBF contains less information for faraway items and more information for nearby items. Interestingly, the construction of DDBFs requires no extra cost above that of standard filters. We also show by simulation that our method can achieve better lookup performance than existing ones.