This paper presents necessary and sufficient conditions for the existence of a Lyapunov function in the Lur'e form that guarantees the absolute stability of a Lur'e control system with multiple nonlinearities. It simplifies the existence problem to one of solving a set of linear matrix inequalities (LMIs). If these inequalities are feasible, the free parameters in the Lyapunov function, such as the positive definite matrix and the coefficients of the integral terms,are given by the solution of the LMIs. Otherwise, there does not exist any Lyapunov function in the Lur'e form. Necessary and sufficient conditions are also obtained for the robust absolute stability of time-varying structured uncertain systems.

This paper deals with the problem of delay-dependent robust stability for systems with time-varying structured uncertainties and time-varying delays. Some new delay-dependent stability criteria are devised by taking the relationship between the terms in the Leibniz-Newton formula into account. Since free weighting matrices are used to express this relationship and since appropriate ones are selected by means of linear matrix inequalities, the new criteria are less conservative than existing ones. Numerical examples suggest that the proposed criteria are e;ective and are an improvement over previous ones.

A distributed computer energy management and control system (DCEMCS) has been established in a nonferrous metal smeltery. It consists of central computer system, local area computer system, real-time baseband local area network, and measurement and control mechanism. This paper presents the theory and techniques applied to the system design, espec-ially the hardware architecture and the main functions of DCEM CS, the hierarchical configu-ration and the dynamic coordination algorithm based on two level computers, the real-time local area network technique and the programming method, the distributed design technique for the applied software and the basic idea of designing and anaging the energy database.

This note concerns delay-dependent robust stability criteria and a design method for stabilizing neutral systems with time-varying structured uncertainties. A new way of deriving such criteria is presented that combines the parameterized model transformation method with a method that takes the relationships between the terms in the Leibniz-Newton formula into account. The relationships are expressed as free weighting matrices obtained by solving linear matrix inequalities. Moreover, the stability criteria are also used to design a stabilizing state-feedbackcontr oller. Numerical examples illustrate the effectiveness of the method and the improvement over some existing methods.

Two important aspects of the control of the coal blending process in the iron and steel industry are computation of the target percentage of each type of coal to be blended and the blending of the different types in the target percentages. This paper proposes an expert control strategy to compute and track the target percentages accurately. First, neural networks, mathematical models and rule models are constructed based on statistical data and empirical knowledge on the process. Then a methodology is proposed for computing the target percentages that combines the neural networks, mathematical models and rule models and uses forward chaining and model-based reasoning. Finally, the tracking control of the target percentages is carried out by a distributed PI control scheme. The expert control strategy proposed is implemented in an expert control system that contains an expert controller and a distributed controller. The results of actual runs show that the proposed expert control strategy is an effective way to control the coal blending process.