Robust H∞ control of uncertain Markovian jump systems with time-delay

This correspondence is concerned with the robust stochastic stabilizability and robust H∞ disturbance attenuation for a class of uncertain linear systems with time delay and randomly jumping parameters The transition of the jumping parameters is governed by a finite-state Markov process. Sufficient conditionson the existence of a robust stochastic stabilizing and γ-suboptimal H∞ state-feedback controller are presented using the Lyapunov functional approach. It isshown that a robust stochastically stabilizing H∞ state-feedback controller can be constructed through the numerical solution of a set of coupled linear matrix inequalities. © 2000 IEEE.published_or_final_versio

A computational method for simultaneous LQ optimal control design via piecewise constant output feedback

This paper is concerned with simultaneous linear-quadratic (LQ) optimal control design for a set of LTI systems via piecewise constant output feedback. First, the discrete-time simultaneous LQ optimal control design problem is reduced to solving a set of coupled matrix inequalities and an iterative LMI algorithm is presented to compute the feedback gain. Then, simultaneous stabilization and simultaneous LQ optimal control design of a set of LTI continuous-time systems are considered via periodic piecewise constant feedback gain. It is shown that the design of a periodic piecewise constant feedback gain simultaneously minimizing a set of given continuous-time performance indexes can be reduced to that of a constant feedback gain minimizing a set of equivalent discrete-time performance indexes. Explicit formulas for computing the equivalent discrete-time systems and performance indexes are derived. Examples are used to demonstrate the effectiveness of the proposed method.published_or_final_versio

Necessary and sufficient conditions for stable H∞ stabilizability

In this paper, the stable H∞ control problem is addressed. It is shown that the stable H∞ control problem is reduced to finding a unimodular matrix such that a two block H∞ optimization problem is solvable. And then it can be solved if an unimodular matrix is selected such that a Nehari problem is solvable. In fact, if the unimodular matrix is selected as a constant matrix, then a previous result is obtained.published_or_final_versio

Simultaneous stabilization via static output feedback and state feedback

In this paper, the simultaneous stabilization problem is considered using the matrix inequality approach. Some necessary and sufficient conditions for simultaneous stabilizability of r strictly proper multi-input/multi-output (MIMO) plants via static output feedback and state feedback are obtained in the form of coupled ARI's. It is shown that any such stabilizing feedback gain is the solution of some coupled linear quadratic control problems where every cost functional has a suitable cross term. A heuristic iterative algorithm based on the linear matrix inequality (LMI) technique is presented to solve the coupled matrix inequalities. The effectiveness of the approach is illustrated by numerical example.published_or_final_versio

A linear matrix inequality (LMI) approach to robust H2 sampled-data control for linear uncertain systems

In this paper, we consider the H2 sampled-data control for uncertain linear systems by the impulse response interpretation of the H2 norm. Two H2 measures for sampled-data systems are considered. The robust optimal control procedures subject to these two H2 criteria are proposed. The development is primarily concerned with a multirate treatment in which a periodic time-varying robust optimal control for uncertain linear systems is presented. To facilitate multirate control design, a new result of stability of hybrid system is established. Moreover, the single-rate case is also obtained as a special case. The sampling period is explicitly involved in the result which is superior to traditional methods. The solution procedures proposed in this paper are formulated as an optimization problem subject to linear matrix inequalities. Finally, we present a numerical example to demonstrate the proposed techniques.published_or_final_versio

E2F1 Downregulation by Arsenic Trioxide in Lung Adenocarcinoma

Lung cancer is one of the most common cancers worldwide. Arsenic trioxide (ATO) has been approved by the U.S. Food and Drug Administration for the treatment of acute promyelocytic leukemia. Nonetheless preliminary data have suggested potential activity of ATO in solid tumors including lung cancer. This study aimed to examine the underlying mechanisms of ATO in the treatment of lung adenocarcinoma. Using a panel of 7 lung adenocarcinoma cell lines, the effects of ATO treatment on cell viability, expression of E2F1 and its downstream targets, phosphatidylserine externalization, mitochondrial membrane depolarization and alteration of apoptotic/anti-apoptotic factors were studied. Tumor growth inhibition in vivo was investigated using a nude mouse xenograft model. ATO decreased cell viability with clinically achievable concentrations (8 uM) in all cell lines investigated. This was accompanied by reduced expression of E2F1, cyclin A2, skp2, c-myc, thymidine kinase and ribonucleotide reductase M1, while p-c-Jun was upregulated. Cell viability was significantly decreased with E2F1 knockdown. Treatment with ATO resulted in phosphatidylserine externalization in H23 cells and mitochondrial membrane depolarization in all cell lines, associated with truncation of Bid, downregulation of Bcl-2, upregulation of Bax and Bak, caspase-9 and caspase-3 activation and PARP cleavage. Using a H358 xenograft model, the tumor growth was suppressed in the ATO treatment group during 8 days of treatment, associated with downregulation of E2F1 and upregulation of truncated Bid and cleaved caspase-3. In conclusion, ATO has potent in vitro and in vivo activity in lung adenocarcinoma, partially mediated through E2F1 downregulation and apoptosis.published_or_final_versio

A cluster analysis of patterns of objectively measured physical activity in Hong Kong

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An analysis on reasons of non-compliant to cardiac rehabilitation programme

Abstract no. 09published_or_final_versio

Transfusion-refractory anaemia in liver cirrhosis

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Return to work after cardiac rehabilitation

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