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Search Results: 1 - 10 of 1069 matches for " Masashi Wakaiki "
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Quantized Output Feedback Stabilization of Switched Linear Systems
Masashi Wakaiki,Yutaka Yamamoto
Mathematics , 2014,
Abstract: This paper studies the problem of stabilizing a continuous-time switched linear system by quantized output feedback. We assume that the quantized outputs and the switching signal are available to the controller at all time. We develop an encoding strategy by using multiple Lyapunov functions and an average dwell time property. The encoding strategy is based on the results in the case of a single mode, and it requires an additional adjustment of the "zoom" parameter at every switching time.
Quantized Feedback Stabilization of Sampled-Data Switched Linear Systems
Masashi Wakaiki,Yutaka Yamamoto
Computer Science , 2014,
Abstract: We propose a stability analysis method for sampled-data switched linear systems with quantization. The available information to the controller is limited: the quantized state and switching signal at each sampling time. Switching between sampling times can produce the mismatch of the modes between the plant and the controller. Moreover, the coarseness of quantization makes the trajectory wander around, not approach, the origin. Hence the trajectory may leave the desired neighborhood if the mismatch leads to instability of the closed-loop system. For the stability of the switched systems, we develop a sufficient condition characterized by the total mismatch time. The relationship between the mismatch time and the dwell time of the switching signal is also discussed.
Stabilization of continuous-time switched linear systems with quantized output feedback
Masashi Wakaiki,Yutaka Yamamoto
Computer Science , 2015,
Abstract: In this paper, we study the problem of stabilizing continuous-time switched linear systems with quantized output feedback. We assume that the observer and the control gain are given for each mode. Also, the plant mode is known to the controller and the quantizer. Extending the result in the non-switched case, we develop an update rule of the quantizer to achieve asymptotic stability of the closed-loop system under the average dwell-time assumption. To avoid quantizer saturation, we adjust the quantizer at every switching time.
Stability analysis of sampled-data switched systems with quantization
Masashi Wakaiki,Yutaka Yamamoto
Computer Science , 2015,
Abstract: We propose a stability analysis method for sampled-data switched linear systems with finite-level static quantizers. In the closed-loop system, information on the active mode of the plant is transmitted to the controller only at each sampling time. This limitation of switching information leads to a mode mismatch between the plant and the controller, and the system may become unstable. A mode mismatch also makes it difficult to find an attractor set to which the state trajectory converges. A switching condition for stability is characterized by the total time when the modes of the plant and the controller are different. Under the condition, we derive an ultimate bound on the state trajectories by using a common Lyapunov function computed from a randomized algorithm. The switching condition can be reduced to a dwell-time condition.
Stabilization of discrete-time piecewise affine systems with quantized signals
Masashi Wakaiki,Yutaka Yamamoto
Computer Science , 2015,
Abstract: This paper studies quantized control for discrete-time piecewise affine systems. For given stabilizing feedback controllers, we propose an encoding strategy for local stability. If the quantized state is near the boundaries of quantization regions, then the controller can recompute a better quantization value. For the design of quantized feedback controllers, we also consider the stabilization of piecewise affine systems with bounded disturbances. In order to derive a less conservative design method with low computational cost, we investigate a region to which the state belong in the next step.
Output Feedback Stabilization of Switched Linear Systems with Limited Information
Masashi Wakaiki,Yutaka Yamamoto
Computer Science , 2014,
Abstract: We propose an encoding and control strategy for the stabilization of switched systems with limited information, supposing the controller is given for each mode. Only the quantized output and the active mode of the plant at each sampling time are transmitted to the controller. Due to switching, the active mode of the plant may be different from that of the controller in the closed-loop system. Hence if switching occurs, the quantizer must recalculate a bounded set containing the estimation error for quantization at the next sampling time. We establish the global asymptotic stability under a slow-switching assumption on dwell time and average dwell time. To this end, we construct multiple discrete-time Lyapunov functions with respect to the estimated state and the size of the bounded set.
Distribution of Deviation Distance to Alternative Fuel Stations  [PDF]
Masashi Miyagawa
American Journal of Operations Research (AJOR) , 2013, DOI: 10.4236/ajor.2013.33033
Abstract: This paper derives the distribution of the deviation distance to visit an alternative fuel station. Distance is measured as the Euclidean distance on a continuous plane. The distribution explicitly considers the vehicle range and whether the round trip between origin and destination can be made. Three cases are examined: fuel is available at both origin and destination, fuel is available at either origin or destination, and fuel is available at neither origin nor destination. The analytical expressions for the distribution demonstrate how the vehicle range, the shortest distance, and the refueling availability at origin and destination affect the deviation distance. The distribution will thus be useful to estimate the number of vehicles refueled at a station.

Weak Values Influenced by Environment  [PDF]
Masashi Ban
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.411A1001

A weak value of an observable is studied for a quantum system which is placed under the influence of an environment, where a quantum system irreversibly evolves from a pre-selected state to a post-selected state. A general expression for a weak value influenced by an environment is provided. For a Markovian environment, the weak value is calculated in terms of the predictive and retrodictive density matrices, or by means of the quantum regression theorem. For a non-Markovian environment, a weak value is examined by making use of exactly solvable models. It is found that although the anomalous property is significantly suppressed by a Markovian environment, it can survive a non-Markovian environment.

Visceral Ischemia Caused by Extra-Anatomical Bypass for Coral Reef Aorta  [PDF]
Masashi Kawabori
World Journal of Cardiovascular Surgery (WJCS) , 2015, DOI: 10.4236/wjcs.2015.57012
Abstract: A 72-year-old woman was presented with intermittent claudication of bilateral lower extremities, refractory hypertension, and mild renal impairment. Computed tomographic angiography showed severe aortic stenosis caused by calcifications protruding into the aortic lumen proximal and distal to the visceral and renal branches, so-called coral reef aorta. An axillo-iliac bypass was performed. Postoperatively, the patient developed ileus and acute renal failure, presumably caused by a steal phenomenon to the lower extremities. Endovascular stenting of the aorta increased forward blood flow and dramatically improved the patient’s condition. This case study illustrates potential hemodynamic complications after extra-anatomical axillo-iliac bypass for coral reef aorta.
Aortic Valve Replacement in Bicuspid Aortic Valve with a Single Coronary Artery  [PDF]
Masashi Kawabori
World Journal of Cardiovascular Surgery (WJCS) , 2015, DOI: 10.4236/wjcs.2015.512020
Abstract: Coronary artery anomalies combined with bicuspid aortic valve are rare but cause perioperative complications if not detected on time. Because anomalous coronary arteries vary with respect to the ostium’s origin and transverse route, the precise anatomy should be identified preoperatively and the procedure modified. We describe a severely stenotic bicuspid aortic valve and anomalous coronary artery corrected successfully with a modified valve replacement procedure, illustrating the importance of analyzing coronary anatomy preoperatively, regardless of age, to avoid occluding an anomalous artery’s ostium and to address the anomalies. We describe our modified procedure based on the artery’s location for a safe operation.
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