On the l_2-stability of time-varying linear and nonlinear discrete-time MIMO systems

New conditions are derived for the 2-stability of time-varying linear and nonlinear discrete-time multiple-input multipleoutput(MIMO) systems, having a linear time time-invariant block with the transfer function Γ(z), in negative feedback with a matrix of periodic/aperiodic gains A(k), k = 0, 1, 2,... and a vector of certain classes of non-monotone/monotone nonlinearities■(■), without restrictions on their slopes and also not requiring path-independence of their line integrals. The stability conditions,which are derived in the frequency domain, have the following features: i) They involve the positive definiteness of the real part(as evaluated on |z| = 1) of the product of Γ(z) and a matrix multiplier function of z. ii) For periodic A(k), one class of multiplier functions can be chosen so as to impose no constraint on the rate of variations A(k), but for aperiodic A(k), which allows a more general multiplier function, constraints are imposed on certain global averages of the generalized eigenvalues of(A(k + 1), A(k)), k = 1, 2,.... iii) They are distinct from and less restrictive than recent results in the literature.     

Frequency-domain $L_2$-stability conditions for time-varying linear and nonlinear MIMO systems

The paper deals with the g2-stability analysis of multi-input-multi-output （MIMO） systems, governed by integral equations, with a matrix of periodic/aperiodic time-varying gains and a vector of monotone, non-monotone and quasi-monotone nonlin- earities. For nonlinear MIMO systems that are described by differential equations, most of the literature on stability is based on an application of quadratic forms as Lyapunov-function candidates. In contrast, a non-Lyapunov framework is employed here to derive new and more general g2-stability conditions in the frequency domain. These conditions have the following features： i） They are expressed in terms of the positive definiteness of the real part of matrices involving the transfer function of the linear time-invariant block and a matrix multiplier function that incorporates the minimax properties of the time-varying linear/nonlinear block, ii） For certain cases of the periodic time-varying gain, they contain, depending on the multiplier function chosen, no restrictions on the normalized rate of variation of the time-varying gain, but, for other periodic/aperiodic time-varying gains, they do. Overall, even when specialized to periodic-coefficient linear and nonlinear MIMO systems, the stability conditions are distinct from and less restrictive than recent results in the literature. No comparable results exist in the literature for aperiodic time-varying gains. Furthermore, some new stability results concerning the dwell-time problem and time-varying gain switching in linear and nonlinear MIMO systems with periodic/aperiodic matrix gains are also presented. Examples are given to illustrate a few of the stability theorems.     

GH 2 control for uncertain discrete-time-delay fuzzy systems based on a switching fuzzy model and piecewise Lyapunov function

Generalized H2 （GH2） stability analysis and controller design of the uncertain discrete-time Takagi-Sugeno （T-S） fuzzy systems with state delay are studied based on a switching fuzzy model and piecewise Lyapunov function. GH2 stability sufficient conditions are derived in terms of linear matrix inequalities （LMIs）. The interactions among the fuzzy subsystems are considered. Therefore, the proposed conditions are less conservative than the previous results. Since only a set of LMIs is involved, the controller design is quite simple and numerically tractable. To illustrate the validity of the proposed method, a design example is provided.     

Optimal guaranteed cost control for an uncertain discrete T-S fuzzy system with time-delay

This paper considers the guaranteed cost control problem for a class of uncertain discrete T-S fuzzy systems with time delay and a given quadratic cost function. Sufficient conditions for the existence of such controllers are derived based on the linear matrix inequalities （LMI） approach by constructing a specific nonquadratic Lyapunov-Krasovskii functional and a nonlinear PDC-like control law. A convex optimization problem is also formulated to select the optimal guaranteed cost controller that minimizes the upper bound of the closed-loop cost function. Finally, numerical examples are presented to demonstrate the effectiveness of the proposed approaches.     

Frequency-domain stability criteria for SISO and MIMO nonlinear feedback systems with constant and variable time-delays

New frequency-domain criteria are proposed for the $L_2$-stability of both nonlinear single-input-single-output (SISO) and nonlinear multiple-input-multiple-output (MIMO) feedback systems, described by nonlinear integral equations. For SISO systems, the feedback block is a constant scalar gain in product with a linear combination of first-and-third-quadrant scalar nonlinearities (FATQNs) with time-delay argument functions; and, for MIMO systems, it is a constant matrix gain in product with a linear combination of vector FATQNs also with time-delay argument functions. In both the cases, the delay function in the arguments of the nonlinearities may be, in general, i) zero, ii) a constant, iii) variable-time and iv) fixed-history (only for SISO systems). The stability criteria are derived from certain recently introduced algebraic inequalities concerning the scalar and vector nonlinearities, and involve the causal+anticausal O''Shea-Zames-Falb multiplier function (scalar for SISO systems and matrix for MIMO systems). Its time-domain $L_1$-norm is constrained by the coefficients and characteristic parameters (CPs) of the nonlinearities and, in the case of the time-varying delay, by its rate of variation also. The stability criteria, which are independent of Lyapunov-Krasovskii or Lyapunov-Razumikhin functions and do not seem to be derivable by invoking linear matrix inequalities, seem to be the first of their kind. Two numerical examples for each of SISO and MIMO systems illustrate the criteria.     

Guaranteed cost control for saturated uncertain linear systems

In this paper, we discuss the problem of guaranteed cost control for uncertain linear systems subject to actuator saturation. Based on the quadratic and non-quadratic Lyapunov functions, sufficient conditions for the robust stability and performance are derived. Moreover, all the conditions can be expressed as linear matrix inequalities （LMIs） or bilinear matrix inequalities （BMIs） in terms of the feedback gain. Thus, the static controller can be effectively synthesized via convex optimization. A numerical example illustrates the effectiveness of the method.     

Relaxed delay-dependent stabilization criteria for discrete-time fuzzy systems based on a switching fuzzy model and piecewise Lyapunov functions

This paper presents delay-dependent stability analysis and controller synthesis methods for discrete-time Takagi-Sugeno （T-S） fuzzy systems with time delays. The T-S fuzzy system is transformed to an equivalent switching fuzzy system. Consequently, the delay-dependent stabilization criteria are derived for the switching fuzzy system based on the piecewise Lyapunov function. The proposed conditions are given in terms of linear matrix inequalities （LMIs）. The interactions among the fuzzy subsystems are considered in each subregion, and accordingly the proposed conditions are less conservative than the previous results. Since only a set of LMIs is involved, the controller design is quite simple and numerically tractable. Finally, a design example is given to show the validity of the proposed method.     

Robust H_∞ control for discrete-time polytopic uncertain systems with linear fractional vertices

The robust H∞ control problem for discrete-time uncertain systems is investigated in this paper. The uncertain systems are modelled as a polytopic type with linear fractional uncertainty in the vertices. A new linear matrix inequality (LMI) characterization of the H∞ performance for discrete systems is given by introducing a matrix slack variable which decouples the matrix of a Lyapunov function candidate and the parametric matrices of the system. This feature enables one to derive sufficient conditions for discrete uncertain systems by using parameter-dependent Lyapunov functions with less conservativeness. Based on the result, H∞ performance analysis and controller design are carried out. A numerical example is included to demonstrate the effectiveness of the proposed results.     

Robust H-infinity filtering for time-delay systems with missing measurements： a parameter-dependent approach

Robust H-infinity filtering for a class of uncertain discrete-time linear systems with time delays and missing measurements is studied in this paper. The uncertain parameters are supposed to reside in a convex polytope and the missing measurements are described by a binary switching sequence satisfying a Bernoulli distribution. Our attention is focused on the analysis and design of robust H-infinity filters such that, for all admissible parameter uncertainties and all possible missing measurements, the filtering error system is exponentially mean-square stable with a prescribed H-infinity disturbance attenuation level. A parameter-dependent approach is proposed to derive a less conservative result. Sufficient conditions are established for the existence of the desired filter in terms of certain linear matrix inequalities （LMIs）. When these LMIs are feasible, an explicit expression of the desired filter is also provided. Finally, a numerical example is presented to illustrate the effectiveness and applicability of the proposed method.     

On absolute stability of Lur''''e control systems with multiple non-linearities using linear matrix inequalities

Necessary and suffcient conditions for the existence of a Lyapunov function in the Lur'e form to guarantee the absolute stability of Lur'e control systems with multiple non-linearities are discussed in this paper. It simplifies the existence problem to one of solving a set of linear matrix inequalities (LMIs), If those LMIs are feasible, 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, this Lyapunov function does not exist. Some sufficient conditions are also obtained for the robust absolute stability of uncertain systems.A numerical example is provided to demonstrate the effectiveness of the proposed method.     

Managing behavioral academic self-esteem using FuzzyXteem

Behavioral academic self-esteem （BASE） has been used with children of preschool, elementary, and junior high school classes, both individually and in groups. In this study, BASE is used to estimate the factor structures and determine the levels of academic self-esteem of the student. The current practice of the existing system using BASE scale may be scored by hand or by computer based on the rigid crisp values to represent rating number one through five. Since BASE requires the ability for estimating the factor structure and also the ability to explain how the conclusion is derived, therefore artificial intelligent techniques that are required to perform BASE must be able to perform estimation and provide reasoning. For this purpose, fuzzy logic and expert system have been integrated in a web-based environment to demonstrate the use of hybrid system on BASE factor structure and levels of academic self-esteem. For each BASE factor, the sub score is provided based on the classifications of academic self-esteem and their respective ranges. In FuzzyXteem, users in particular teachers, counselors, or parent are allowed to measure students＇ self-esteem at early age using real time computation. FuzzyXteem facilitates user by automatically evaluating BASE factors and helps the user diagnoses their students＇ levels of academic self-esteem in 3 ratings： low, moderate and high. It is also able to provide explanation and describe how the conclusion can be derived. The system has been successfully tested by the counselors and conforms to the BASE factor rating scale and sub-scores. FuzzyXteem can be used as an aid to decision making in improving a person＇s self esteem, and indirectly increases an individual for productivity. The same system functions can be applied to business organization for managing and improving the organizations performance.     

Automatic Virtual Entity Simulation of Conceptual Design Results Part I： Symbolic Scheme Generation and Identification

The development of new products of high quality, low unit cost, and short lead time to market are the key elements required for any enterprise to obtain a competitive advantage. For shorting the lead time to market and improving the creativity and performances of the product, a rule-based conceptual design approach and a methodology to simulate the conceptual design results generated in conceptual design process in automatical virtual entity form are presented in this paper. This part of paper presents a rule-based conceptual design method for generating creative conceptual design schemes of mechanisms based on Yan＇s kinematic chain regeneration creative design method. The design rules are adopted to describe the design requirements of the functional characteristics, the connection relationships and topological characteristics among mechanisms. Through the graphs-based reasoning process, the conceptual design space is expanded extremely, and the potential creative conceptual design results are then dug out. By refining the design rules, the solution exploration problem is avioded, and the tendentious conceptual design schemes are generated. Since mechanical, electrical and hydraulic subsystems can be transformed into general mechansims, the conceptual design method presented in this paper can also be applied in the conceptual design problem of complex mechatronic systems. And then the method to identify conceptual design schemes is given.     

Multi-agent based evolutional algorithm in medicine image segmentation

When we analyses medicine image, many research objects （such as human brain and heart, et al） have no obvious brim, it is nature texture image and hasn＇t clear boundary between different organizations. An evolutional algorithm of medicine image segmentation based on multi-agent system is proposed in this paper. The agent is designed to be distributed calculation entities of the four entities of the calculation of the distribution in the algorithm, it presence at the two-dimensional grid in the medicine image, using the priori knowledge to guide its evolution. Through the human brain MR image segmentation experiment, compare to maximum likelihood segmentation and Conjugate Gradient Square segmentation, our method is more suitable for clinical.     

Cluster synchronization of a class of multi-agent systems with a bipartite graph topology

This paper investigates cluster synchronization of a class of multi-agent systems with a directed bipartite graph topology,and presents a number of new results by using the neighbor’s rules for the following two cases:I)there is competition among the agents of diferent clusters,and II)there are both competition and cooperation among the agents.Firstly,for case I),a linear control protocol is designed for cluster synchronization of multi-agent systems,and a method is presented to determine the final state with the initial conditions based on state-space decomposition.Secondly,we study case II),and design a control protocol based on the information of neighbors and that of two-hop neighbors(that is,neighbors’neighbors).Finally,two examples are studied by using our presented results.The study of illustrative examples with simulations shows that our results as well as designed control protocols work very well in studying the cluster synchronization of this class of multi-agent systems.     

Research on immune algorithm for mobile phone viruses detection

In responds to the problem that mobile phone viruses is much more serious but the detection technology for them is not maturity, there is a new way for mobile phone viruses detection. Which is based on the viruses＇ work principle and infection ways, introduced immune algorithm into computer viruses defense detection and set up mobile phone viruses detection model based on minus select immune algorithm. At the same time, it also made analysis on immune algorithm viruses detection and found an approach to probing to mobile phone viruses.     

A study of the employment of higher institutions based on the decision tree model

The employment of the graduates is a major index to measure the achievements of higher institutions. And the academic grades of the students at school are a very important factor in obtaining employment. In this essay, a classified model of decision tree between the grades of the graduates and their employment is established, and the model is also optimized and well researched. Therefore, this model can be a scientific and rational resource for an institution when setting up the achievement goal to increase the employment rate of the students.     

Learning by doing： Software project management course education

One of the key factors influencing project success or failure is project management. Unfortunately, effective management of software projects is not in practice. To meet the requirements of enterprises, majors in computer in more and more universities offer software project management course. However, as Reif and Marti put it, ＂successful software project management, like programming, is not a skill that students will master from a single course of instruction＂. In this work, we present a teaching mode based on project-driven for software project management course, and describe it from the aspects of training objectives, teaching implementation, the student＇s job, and assessment mechanism, and finally provide a summary and analysis of the characteristics of this teaching mode as well as the effect of the curriculum practice.     

Context-awareness approach in game style application

By combining training content with Game AI, Game Style Training can provide a rich, interactive and engaging educational substance. It supports experiential learning-bydoing. And it can contribute to promote interest and motivation of trainees. In this paper, a Context-Awareness Approach （CAA） is put forward for earthquake rescue training by applying the concept of ambient intelligence. The CAA takes advantage of player profile to monitor player states, utilizes time sensor and location sensor to supervise environment changes. And then, a Reinforcement Learning model based on MAS is designed to update game AI system.     

Solving Strategy for Repetitious Simulation of Multi-domain Physical System Based on Modelica

Repetitious simulation after modifying parameters of multi-domain physical system based on Modelica often appears in model experiment and optimization design. At present, the solvers based on Modelica need calculate all the coupled blocks during every simulation run after updating parameters. Based on discussing scale decomposition methods of simulation model, subdivision solving strategy and minimum solving strategy are put forward to improve the efficiency of repetitious simulation, by which the numerical solution of the simulation model can be achieved by only calculating the solving sequence influenced by altered parameters. A simplified model of aircraft is used to demonstrate the efficiency of the strategies presented.