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Symbolic/Numeric Computations for Feedback Control System Design
Shinji Hara 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
This paper focuses on symbolic/numeric hybrid computations for feedback control system design. Three resent approaches along this research directions, namely robust controller design by a parameter space approach, Sum of Root(SoR) characterization of H2 optimal control design, and symbolic-numeric hybrid integrated design, are reviewed.
Hidetake Hara,Hiroshi Muraishi,Hiroki Matsuzawa,Toshiyuki Inoue,Yasuo Nakajima,Hitoshi Satoh,Shinji Abe 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.1
We have recently developed a phantom that simulates acute ischemic stroke. We attempted to visualize an acute-stage cerebral infarction by using dual-energy Computed tomography (DECT) to obtain virtual monochromatic images of this phantom. Virtual monochromatic images were created by using DECT voltages from 40 to 100 keV in steps of 10 keV and from 60 to 80 keV in steps of 1 keV, under three conditions of the tube voltage with thin (Sn) filters. Calculation of the CNR values allowed us to evaluate the visualization of acute-stage cerebral infarction. The CNR value of a virtual monochromatic image was the highest at 68 keV under 80 kV / Sn 140 kV, at 72 keV under 100 kV / Sn 140 kV, and at 67 keV under 140 kV / 80 kV. The CNR values of virtual monochromatic images at voltages between 65 and 75 keV were significantly higher than those obtained for all other created images. Therefore, the optimal conditions for visualizing acute ischemic stroke were achievable.
Hierarchical Modeling for Diffusion Systems
Daisuke Tsubakino,Shinji Hara 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
In this paper, we propose a hierarchical modeling of the systems described by conservation laws. A conservation law on a hierarchically parted domain can be considered as a subsystem which interacts with neighbor elements through fluxes. Therefore, we regard the system as a networked system of each subsystem. The important idea is to weaken the interconnection in the sense of a rank. For detailed analysis of our method, we apply the proposed method to a diffusion equation. The hierarchical model is described by a non-circulant block Toeplitz matrix. Because the resulting system is symmetrically-networked system, we can show that the eigenvalues of the system consist of those of related uniform models. We also show that our method relaxes the stability condition of the fully discretized model. Finally we examine the performance of the hierarchical model by numerical simulations.
Hierarchical Consensus for Multi-Agent Systems with Low-rank Interconnection
Hikaru Shimizu,Shinji Hara 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
This paper deals with a hierarchical consensus problem in large scale systems. We first define the hierarchical consensus and propose a fairly general model of the system. We then define the interconnection matrix which expresses interconnection property between layers, where we focus on the rank of this matrix. In order to examine the relationship between the rank of interconnection matrix and stability degree of the system, we analytically derive the eigenvalue distribution of the system matrix. The resultant distribution shows that the low-rank interconnection leads to the faster consensus in terms of rate of convergence and damping, which is confirmed by numerical examples with simulations.