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Volume 21, Issue 11
Displaying 1-4 of 4 articles from this issue
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Minghua LI, Takashi HIKIHARA2008 Volume 21 Issue 11 Pages 343-348
Published: November 15, 2008
Released on J-STAGE: October 13, 2011
JOURNAL FREE ACCESSA power supply with high voltage and large current is used to be achieved by connecting several batteries in series or parallel. In this paper, a model of coupled redox flow (RF) batteries is derived based on chemical reaction. The model clearly shows the influences of imbalance of battery's unit. The numerical discussion leads us to dynamic design of the redox flow batteries.View full abstractDownload PDF (1093K) -
Yasunori SUGITA, Ryo ISOBE, Toshinori YOSHIKAWA, Naoyuki AIKAWA2008 Volume 21 Issue 11 Pages 349-357
Published: November 15, 2008
Released on J-STAGE: October 13, 2011
JOURNAL FREE ACCESSThis paper presents a quadratic kernel with four variable parameters for image enlargement. The proposed kernel can generate peak and valley information of the signals by considering the characteristics of the image and by changing these parameters. Moreover, as the proposed kernel is the extension of the linear interpolation and the nearest-neighbor interpolation, the forms of the proposed kernel are also used selectively depending on the characteristics of signal points which are used for parameter estimation. The various standard images are enlarged using the proposed kernel, and the performance of the proposed kernel is evaluated with MSE of the enlarged images. It has been shown that the performance of the proposed kernel is better than the other methods, such as the cubic interpolations that are often used in image processing.View full abstractDownload PDF (3519K) -
Daisuke BANJO, Hiroyuki TAMURA, Tadahiko MURATA2008 Volume 21 Issue 11 Pages 358-367
Published: November 15, 2008
Released on J-STAGE: October 13, 2011
JOURNAL FREE ACCESSIn this paper, we propose transferring methods from the present pay-as-you-go scheme to a generation-based funding scheme. We make a mathematical model for the public pension system consisting of national pension, employee pension and mutual pension. Simulating the mathematical model the necessary government contribution is evaluated for the case with or without transferring to the generation-based funding scheme where we take into account the demographic structural change and the variation in economic situation.View full abstractDownload PDF (1611K) -
Yoshihiko SUSUKI, Takashi HIKIHARA2008 Volume 21 Issue 11 Pages 368-376
Published: November 15, 2008
Released on J-STAGE: October 13, 2011
JOURNAL FREE ACCESSAnalysis of voltage instability of power systems is of basic importance for prevention of cascading outages and large blackouts. We propose to use reachability analysis of hybrid automaton for voltage instability analysis of power systems. Hybrid automaton is a well-known mathematical model of hybrid systems. Reachability analysis is performed by computing forward or backward reach sets for unsafe sets of a hybrid automaton. The automaton can represent the interaction between continuous voltage oscillation and discrete control of power equipments. The unsafe sets are also subsets of state space in which system voltages show unacceptable levels such as low or high values. For single machine-load bus (SMLB) system with controlled route switching, we show that computation of backward reach sets of hybrid automaton makes it possible to determine voltage instability in the SMLB system. The obtained result implies that voltage instability leading to cascading outages can be detected before its occurrence.View full abstractDownload PDF (1698K)
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