continuous takagi sugeno s models reduction of the number of lmi conditions in various fuzzy control design technics fuzzy models of the takagi sugeno type enable representation of a wide class of nonlinear models conditions about their stabilization can be derived systematically usually these conditions are written as linear matrix inequality lmi problems in this paper we use a collection of properties concerning matrices to extend the area of solutions involving the feedback control laws we will work out with continuous fuzzy models and supply results about the stabilization the regulator problem and also hinfin control solutions based on a reduced number of decision variables implying a reduced number of lmi conditions are also proposed we show that a good tradeoff can been obtained

disturbance rejection of left invertible systems abstract a new approach is presented for the study of the disturbance rejection of left invertible systems via proportional state feedback reducing the problem to that of solving a linear algebraic system of equations on the basis of this system of equations the necessary and sufficient conditions for the existence of a solution to the disturbance rejection problem are established in a form of simple algebraic criteria thus reducing the computational effort over known results and the general analytical expressions of all solutions of the controller matrices are derived these solutions are parameterized only by an arbitrary matrix

frequency domain conditions for disturbance rejection and decoupling with stability or pole placement the problem of disturbance rejection and disturbance rejection while decoupling with stability or pole placement is studied using a polynomial matrix approach necessary and sufficient conditions for the solvability of the problem of disturbance rejection as well as for the problem of disturbance rejection with input output decoupling are derived a number of poles of the closed loop system are proved to be fixed for both of the above problems and a procedure for placing all the remaining poles of the closed loop system is presented

the module structure of a controllable system it is proved that the system matrix p s of an l input m output controllable system can be brought by strict system equivalence transformations into a special form ptilde s such that the system is described by the module generated by the first l column vectors of the matrix ptilde s invariants of this module are determined and related to invariants of the system under similarity transformations such as the controllability indices and the controllability subspaces

brief an analysis and design method for linear systems subject to actuator saturation and disturbance we present a method for estimating the domain of attraction of the origin for a system under a saturated linear feedback a simple condition is derived in terms of an auxiliary feedback matrix for determining if a given ellipsoid is contractively invariant this condition is shown to be less conservative than the existing conditions which are based on the circle criterion or the vertex analysis moreover the condition can be expressed as linear matrix inequalities lmis in terms of all the varying parameters and hence can easily be used for controller synthesis this condition is then extended to determine the invariant sets for systems with persistent disturbances lmi based methods are developed for constructing feedback laws that achieve disturbance rejection with guaranteed stability requirements the effectiveness of the developed methods is illustrated with examples

model construction rule reduction and robust compensation for generalized form of takagi sugeno fuzzy systems this paper presents a systematic procedure of fuzzy control system design that consists of fuzzy model construction rule reduction and robust compensation for nonlinear systems the model construction part replaces the nonlinear dynamics of a system with a generalized form of takagi sugeno fuzzy systems which is newly developed by us the generalized form has a decomposed structure for each element of a sub i and b sub i matrices in consequent parts the key feature of this structure is that it is suitable for constructing if then rules and reducing the number of if then rules the rule reduction part provides a successive procedure to reduce the number of if then rules furthermore we convert the reduction error between reduced fuzzy models and a system to model uncertainties of reduced fuzzy models the robust compensation part achieves the decay rate controller design guaranteeing robust stability for the model uncertainties finally two examples demonstrate the utility of the systematic procedure developed

new stability conditions based on piecewise fuzzy lyapunov functions and tensor product transformations improvements of recent stability conditions for continuous time takagi sugeno t s fuzzy systems are proposed the key idea is to bring together the so called local transformations of membership functions and new piecewise fuzzy lyapunov functions by relying on these special local transformations the associated linear matrix inequalities that are used to prove the system s stability can be relaxed without increasing the number of conditions in addition to enhance the usefulness of the proposed methodology one can choose between two different sets of conditions characterized by independence or dependence on known bounds of the membership functions time derivatives a standard example is presented to illustrate that the proposed method is able to provide substantial improvements in some cases

epidemic spreading in correlated complex networks we study a dynamical model of epidemic spreading on complex networks in which there are explicit correlations among the node s connectivities for the case of markovian complex networks showing only correlations between pairs of nodes we find an epidemic threshold inversely proportional to the largest eigenvalue of the connectivity matrix that gives the average number of links which from a node with connectivity k go to nodes with connectivity k ensuremath numerical simulations on a correlated growing network model provide support for our conclusions

disturbance decoupling for linear time invariant systems a matrix pencil approach we give a new systematic analysis of disturbance decoupling problems for standard linear time invariant systems based on the theory of matrix pencils this approach is based on the computation of condensed forms under orthogonal equivalence transformations from these forms which can be computed in a numerically stable way we obtain new necessary and sufficient conditions that are numerically verifiable and furthermore we immediately obtain numerically stable algorithms to compute the desired compensators we present a numerical example that demonstrates the properties of the new approach

use of reduced forms in the disturbance decoupling problem abstract specific algorithms such as those involving the supremal of the invariant subspaces contained in a suitable subspace are known to be able to test whether a disturbance decoupling problem ddp is solvable here by reducing the system to its molinari form we obtain an alternative description of this supremal object and compute its dimension hence we have a general result for solving the decoupling provided that a molinari basis is known in particular a necessary numerical condition for it is derived the same technique is applied to the ddps that is when stability of the decoupled closed loop system is required

fault detection for t s fuzzy systems with unknown membership functions this paper is concerned with the fault detection fd problem for takagi sugeno t s fuzzy systems with unknown membership functions if the membership functions are unknown the linear fd filter designs with fixed gains have been considered in the literature to reduce the conservatism of the existing results a switching mechanism that depends on the lower and upper bounds of the unknown membership functions is provided to construct an fd filter with varying gains it is shown that the switching type fd filter with varying gains can achieve a better fd performance than the linear fd filter with fixed gains in addition based on some time domain inequalities a novel weighting matrix design approach is introduced to transform the fault sensitivity specification into an h constraint finally two examples are given to show the advantages of the proposed fd method

stabilizing controller design for uncertain nonlinear systems using fuzzy models a lyapunov based stabilizing control design method for uncertain nonlinear dynamical systems using fuzzy models is proposed the controller is constructed using a design model of the dynamical process to be controlled the design model is obtained from the truth model using a fuzzy modeling approach the truth model represents a detailed description of the process dynamics the truth model is used in a simulation experiment to evaluate the performance of the controller design a method for generating local models that constitute the design model is proposed sufficient conditions for stability and stabilizability of fuzzy models using fuzzy state feedback controllers are given the results obtained are illustrated with a numerical example involving a four dimensional nonlinear model of a stick balancer

on the fixed poles for disturbance rejection we propose a geometric characterization of the fixed poles for the disturbance rejection problem by static state feedback and in the particular case when the system is controllable a structural characterization in terms of finite invariant zeros of certain open loop subsystems we propose solutions through which all the other poles can be freely assigned

mixing patterns in networks we study assortative mixing in networks the tendency for vertices in networks to be connected to other vertices that are like or unlike them in some way we consider mixing according to discrete characteristics such as language or race in social networks and scalar characteristics such as age as a special example of the latter we consider mixing according to vertex degree i e according to the number of connections vertices have to other vertices do gregarious people tend to associate with other gregarious people we propose a number of measures of assortative mixing appropriate to the various mixing types and apply them to a variety of real world networks showing that assortative mixing is a pervasive phenomenon found in many networks we also propose several models of assortatively mixed networks both analytic ones based on generating function methods and numerical ones based on monte carlo graph generation techniques we use these models to probe the properties of networks as their level of assortativity is varied in the particular case of mixing by degree we find strong variation with assortativity in the connectivity of the network and in the resilience of the network to the removal of vertices

fuzzy dynamic output feedback control through nonlinear takagi sugeno models we present a convex way to design a fuzzy dynamic output feedback compensator for locally stabilizing a class of nonlinear discrete time systems this class consists of the systems described by takagi sugeno t s models with a sector bounded nonlinear additive term and saturated control signals the local stabilization takes into account the domain of validity of these t s models which is a key issue for practical applications two types of nonlinear fuzzy compensators are considered one having all matrices of the controller depending on fuzzy grade membership functions and the other with only a subset of the matrices with such a dependency the controller design includes a fuzzy anti windup gain that handles saturating actuators besides a time performance index based on the contractivity of the level set of the fuzzy lyapunov function is proposed regarding the closed loop system examples are given to illustrate the effectiveness of this proposal

an approach to fuzzy control of nonlinear systems stability and design issues presents a design methodology for stabilization of a class of nonlinear systems first the authors represent a nonlinear plant with a takagi sugeno fuzzy model then a model based fuzzy controller design utilizing the concept of the so called parallel distributed compensation is employed the main idea of the controller design is to derive each control rule so as to compensate each rule of a fuzzy system the design procedure is conceptually simple and natural moreover the stability analysis and control design problems can be reduced to linear matrix inequality lmi problems therefore they can be solved efficiently in practice by convex programming techniques for lmis the design methodology is illustrated by application to the problem of balancing and swing up of an inverted pendulum on a cart

resilience to damage of graphs with degree correlations the existence or nonexistence of a percolation threshold on power law correlated graphs is a fundamental question for which a general criterion is lacking in this work we investigate the problems of site and bond percolation on graphs with degree correlations and their connection with spreading phenomena we obtain some general expressions that allow the computation of the transition thresholds or their bounds using these results we study the effects of assortative and disassortative correlations on the resilience to damage of networks

disturbance and input output decoupling of singular systems the disturbance decoupling and the simultaneous disturbance and input output decoupling problems for singular systems are considered in the context of the matrix fraction description mfd of the system solvability conditions are obtained in terms of the composite matrix of a column reduced mfd of the system a characterisation of the fixed poles of both problems is given and it is shown that the remaining poles can be arbitrarily assigned

a robust h observer based controller design for uncertain t s fuzzy systems with unknown premise variables via lmi this paper addresses the problem of robust h fuzzy observer based controller design for the takagi sugeno t s fuzzy systems with unmeasurable premise variables the proposed design method considers uncertainty for such a problem for the first time using some linear transformations for the output matrices of each local model of the t s fuzzy system and employing finsler s lemma the robust stability conditions in the form of linear matrix inequalities lmis are derived two numerical simulations are provided to show the validity of the proposed method

asymptotically necessary and sufficient conditions for takagisugeno models using generalized non quadratic parameter dependent controller design results in this paper generalize recent approaches on non quadratic controller design for takagisugeno models based on a matrix transformation conditions thus obtained depend on a single parameter which allows an efficient search of feasible solutions via linear matrix inequalities moreover they include and outperform former advances such as polya s approaches on the same framework some examples are included to illustrate the proposed generalization

percolation in directed scale free networks many complex networks in nature have directed links a property that affects the network s navigability and large scale topology here we study the percolation properties of such directed scale free networks with correlated in and out degree distributions we derive a phase diagram that indicates the existence of three regimes determined by the values of the degree exponents in the first regime we regain the known directed percolation mean field exponents in contrast the second and third regimes are characterized by anomalous exponents which we calculate analytically in the third regime the network is resilient to random dilution i e the percolation threshold is pc 1

the fixed poles of the disturbance decoupling problem and almost stability subspace mathcal v star_ b g rm ker c this paper is concerned with the fixed poles of the disturbance decoupling problem for linear time invariant systems by state feedback and measurement feedback algebraic characterizations for these fixed poles are given using the reducing subspace technique in numerical linear algebra these algebraic characterizations lead that the fixed poles can be directly computed by numerically reliable algorithms as an additional application of the reducing subspace technique we also develop a numerically stable method for computing the almost stability subspace mathcal v star b g rm ker c which is an extension of the method given by van dooren for computing the invariant subspaces in geometric control theory

fault estimation and tolerant control for fuzzy stochastic systems this paper deals with the problem of fault estimation and fault tolerant control for takagi sugeno t s fuzzy stochastic systems with sensor failures where the system under consideration contains ito type stochastic disturbances a new robust observer technique is presented to obtain the estimates of the system states and the sensor faults simultaneously and a fuzzy fault tolerant control scheme is developed to guarantee the closed loop system to be exponentially stable in mean square sufficient conditions are obtained for the existence of admissible controllers and it is shown that the reachability of the sliding mode dynamics can be guaranteed under the proposed control techniques finally a numerical example is provided to illustrate the effectiveness and applicability of the theoretic results obtained

robust stability analysis and fuzzy scheduling control for nonlinear systems subject to actuator saturation takagi sugeno ts fuzzy models can provide an effective representation of complex nonlinear systems in terms of fuzzy sets and fuzzy reasoning applied to a set of linear input output submodels in this paper the ts fuzzy modeling approach is utilized to carry out the stability analysis and control design for nonlinear systems with actuator saturation the ts fuzzy representation of a nonlinear system subject to actuator saturation is presented in our ts fuzzy representation the modeling error is also captured by norm bounded uncertainties a set invariance condition for the system in the ts fuzzy representation is first established based on this set invariance condition the problem of estimating the domain of attraction of a ts fuzzy system under a constant state feedback law is formulated and solved as a linear matrix inequality lmi optimization problem by viewing the state feedback gain as an extra free parameter in the lmi optimization problem we arrive at a method for designing state feedback gain that maximizes the domain of attraction a fuzzy scheduling control design method is also introduced to further enlarge the domain of attraction an inverted pendulum is used to show the effectiveness of the proposed fuzzy controller

fuzzy regulators and fuzzy observers relaxed stability conditions and lmi based designs this paper presents new relaxed stability conditions and lmi linear matrix inequality based designs for both continuous and discrete fuzzy control systems they are applied to design problems of fuzzy regulators and fuzzy observers first takagi and sugeno s fuzzy models and some stability results are recalled to design fuzzy regulators and fuzzy observers nonlinear systems are represented by takagi sugeno s ts fuzzy models the concept of parallel distributed compensation is employed to design fuzzy regulators and fuzzy observers from the ts fuzzy models new stability conditions are obtained by relaxing the stability conditions derived in previous papers lmi based design procedures for fuzzy regulators and fuzzy observers are constructed using the parallel distributed compensation and the relaxed stability conditions other lmi s with respect to decay rate and constraints on control input and output are also derived and utilized in the design procedures design examples for nonlinear systems demonstrate the utility of the relaxed stability conditions and the lmi based design procedures

a new lmi based approach to relaxed quadratic stabilization of t s fuzzy control systems this paper proposes a new quadratic stabilization condition for takagi sugeno t s fuzzy control systems the condition is represented in the form of linear matrix inequalities lmis and is shown to be less conservative than some relaxed quadratic stabilization conditions published recently in the literature a rigorous theoretic proof is given to show that the proposed condition can include previous results as special cases in comparison with conventional conditions the proposed condition is not only suitable for designing fuzzy state feedback controllers but also convenient for fuzzy static output feedback controller design the latter design work is quite hard for t s fuzzy control systems based on the lmi based conditions derived one can easily synthesize controllers for stabilizing t s fuzzy control systems since only a set of lmis is involved the controller design is quite simple and numerically tractable finally the validity and applicability of the proposed approach are successfully demonstrated in the control of a continuous time nonlinear system

new approaches to h controller designs based on fuzzy observers for t s fuzzy systems via lmi the problems of relaxed quadratic stability conditions fuzzy observer designs and h controller designs for t s fuzzy systems have been studied first new stability conditions are obtained by relaxing the stability conditions derived in previous papers secondly new fuzzy observers based on the relaxed stability conditions for the t s fuzzy systems have been proposed thirdly two sufficient lmi conditions which guarantee the existence of the h controllers based on fuzzy observers for the t s fuzzy systems have been proposed the conditions are not only simple but also consider the interactions among the fuzzy subsystems finally by some examples using the lmi technique we show that the regulators the fuzzy observers and the h controller designs based on new observers for the t s fuzzy systems are very practical and efficient

oscillatory epidemic prevalence in growing scale free networks we study the persistent epidemic prevalence with oscillatory behavior and the extinction of computer viruses via e mails on a contact relational network growing with new users for which scale free structure is estimated from real data typical oscillatory phenomenon is simulated in a stochastic model for the execution and detection of viruses the conditions of extinction by random and targeted immunizations for hubs are derived through bifurcation analysis for simpler deterministic models by using a mean field approximation without the connectivity correlations we can qualitatively understand the mechanisms of the spread in linearly growing scale free networks

a case study for the open question disturbance decoupling problem for singular systems by output feedback we study the disturbance decoupling problem for singular systems ex spl dot ax bu gd y cx z hx with left invertibility we give necessary and sufficient conditions for the existence of a solution to the disturbance decoupling problem with or without stability by output feedback that also makes the resulting closed loop system regular and or of index at most one all results are proved based on a condensed form that can be computed using orthogonal transformations i e can be computed in a numerically stable way

condensed structural solutions to the disturbance rejection and decoupling problems with stability in this paper it is shown that a static state feedback control law rejects the disturbance and simultaneously performs input output decoupling while ensuring internal stability of the closed loop system if and only if an integer equality holds for the global undisturbed system and the row subsystems of the combined plant where the disturbance is handled as a control input namely in terms of their respective total contents sums of the orders of the multiplicities of its infinite and finite unstable invariant zeros

relaxed stabilization criterion for t s fuzzy systems by minimum type piecewise lyapunov function based switching fuzzy controller this paper proposes the minimum type piecewise lyapunov function based switching fuzzy controller that switches accompanying the piecewise lyapunov function by applying this switching fuzzy controller with the minimum type piecewise lyapunov function the relaxed stabilization criterion is obtained for continuous takagi sugeno t s fuzzy systems some conditions of the relaxed stabilization criterion are represented by bilinear matrix inequalities bmis which contain some bilinear terms as the product of a full matrix and a scalar according to the literature the path following method is very effective for this kind of bmi problem hence it is utilized to obtain solutions of the criterion xie et al in 1997 chose two types i e minimum type and maximum type of piecewise lyapunov functions as the lyapunov function candidates the reasons for why this study only chooses the minimum type piecewise lyapunov function as the lyapunov function candidate are illustrated moreover the numerical example shows the relaxation of the proposed criterion

convergent lmi relaxations for quadratic stabilizability and mathscr h _ infty control of takagi sugeno fuzzy systems this paper investigates the quadratic stabilizability of takagi sugeno t s fuzzy systems by means of parallel distributed state feedback compensators using finsler s lemma a new design condition assuring the existence of such a controller is formulated as a parameter dependent linear matrix inequality lmi with extra matrix variables and parameters in the unit simplex algebraic properties of the system parameters and recent results of positive polynomials are used to construct lmi relaxations that differently from most relaxations in the literature provide certificates of convergence to solve the control design problem due to the degrees of freedom obtained with the extra variables the conditions presented in this paper are an improvement over earlier results based only on polya s theorem and can be viewed as an alternative to the use of techniques based on the relaxation of quadratic forms an extension to cope with guaranteed h infin attenuation levels is also given with proof of asymptotic convergence to the global optimal controller under quadratic stability the efficiency of the proposed approach in terms of precision and computational effort is demonstrated by means of numerical comparisons with other methods from the literature

on local h switched controller design for uncertain t s fuzzy systems subject to actuator saturation with unknown membership functions abstract this manuscript proposes a local h switched controller design for a class of uncertain nonlinear plants described by takagi sugeno t s fuzzy models with unknown membership functions the control design requires only the lower and upper bounds of the system nonlinearities and of the system linear parameters which can depend on uncertain parameters the switched control law chooses a state feedback controller gain which belongs to a given set of gains that minimizes the time derivative of a quadratic lyapunov function this procedure eliminates the necessity of finding the membership function expressions to implement the control law guarantees an h performance and ensures that the state trajectory remains within a region in which the t s fuzzy model is valid due to the h control design that frequently results in very large control inputs it is considered that the switched control law is subject to actuator saturation finally two examples are presented the first example studies the control of a chaotic lorenz system it shows that for disturbances with large magnitude the proposed procedures provided better results than the obtained with another recent method found in the literature that considers full access to the membership functions in the second example a practical implementation of an active nonlinear suspension control system considering an uncertain bounded mass and a fault in the actuator confirms the effectiveness of the proposed approach

anomalous percolation properties of growing networks we describe the anomalous phase transition of the emergence of the giant connected component in scale free networks growing under mechanism of preferential linking we obtain exact results for the size of the giant connected component and the distribution of vertices among connected components we show that all the derivatives of the giant connected component size s over the rate b of the emergence of new edges are zero at the percolation threshold b c and s ensuremath propto mathrm exp ensuremath d ensuremath gamma b ensuremath b c ensuremath 1 2 where the coefficient d is a function of the degree distribution exponent ensuremath gamma in the entire phase without the giant component these networks are in a critical state the probability mathcal p k that a vertex belongs to a connected component of a size k is of a power law form at the phase transition point mathcal p k ensuremath sim 1 k mathrm ln k 2 in the phase with the giant component mathcal p k has an exponential cutoff at k c ensuremath propto 1 s in the simplest particular case we present exact results for growing exponential networks

anti windup control design for exponentially unstable lti systems with actuator saturation in this paper a new saturation control technique in the framework of anti windup compensation is developed for exponentially unstable linear time invariant systems subject to input nonlinearities the proposed control algorithm guarantees regional stability in the existence of input saturation and provides less conservative performance than most existing anti windup schemes moreover an explicit form of anti windup controller with its order no more than the order of the plant is derived an inverted pendulum example is used to demonstrate the advantages of the newly proposed anti windup control technique

parameterized linear matrix inequality techniques in fuzzy control system design this paper proposes different parameterized linear matrix inequality plmi characterizations for fuzzy control systems these plmi characterizations are in turn relaxed into pure lmi programs which provides tractable and effective techniques for the design of suboptimal fuzzy control systems the advantages of the proposed methods over earlier ones are then discussed and illustrated through numerical examples and simulations

on switched regulator design of uncertain nonlinear systems using takagi sugeno fuzzy models this paper is concerned with the design of state feedback switched controllers for a class of uncertain nonlinear plants described by takagi sugeno t s fuzzy models the proposed methodology eliminates the need to find the membership function expressions to implement the control law which is relevant in cases where the membership function depends on uncertain parameters the design of the switched controllers is based on a minimum type lyapunov function and the minimization of the time derivative of this lyapunov function the conditions of the new stability criterion are represented by a kind of bilinear matrix inequalities bmis that has been solved by the path following method a numerical example and the nonlinear control design of a magnetic levitator with uncertainties illustrate the procedure

giant strongly connected component of directed networks we describe how to calculate the sizes of all giant connected components of a directed graph including the strongly connected one in particular the world wide web is a directed network the results are obtained for graphs with statistically uncorrelated vertices and an arbitrary joint in and out degree distribution p k i k o we show that if p k i k o does not factorize the relative size of the giant strongly connected component deviates from the product of the relative sizes of the giant in and out components the calculations of the relative sizes of all the giant components are demonstrated using the simplest examples we explain that the giant strongly connected component may be less resilient to random damage than the giant weakly connected one

input output decoupling by output feedback with disturbance attenuation of h control for any square system the combined problem of diagonal decoupling by output feedback with disturbance attenuation performance for any square system is formulated a sufficient condition which is more general than the necessary and sufficient one of static state feedback for the existence of the controller is determined the necessary and sufficient conditions for the controller and decoupled system that are both stable are presented an analytical form and a numerical computable method for the controller are obtained for the first time when the condition is satisfied the correctness of our method is tested by simulations for an example

simultaneous decoupling and disturbance rejection a structural approach abstract the combined problem of disturbance rejection and decoupling for linear systems is considered new necessary and sufficient conditions are derived for the existence of a state feedback controller that rejects the disturbances and simultaneously decouples the closed loop system these conditions are simple intuitively appealing and are expressed in terms of system structural invariants such as infinite zero orders then we consider the disturbance rejection with simultaneous decoupling problem for structured linear systems necessary and sufficient conditions for the generic solvability of this problem are provided they are expressed in terms of input output path length comparisons on the system associated graph

random graphs with arbitrary degree distributions and their applications recent work on the structure of social networks and the internet has focused attention on graphs with distributions of vertex degree that are significantly different from the poisson degree distributions that have been widely studied in the past in this paper we develop in detail the theory of random graphs with arbitrary degree distributions in addition to simple undirected unipartite graphs we examine the properties of directed and bipartite graphs among other results we derive exact expressions for the position of the phase transition at which a giant component first forms the mean component size the size of the giant component if there is one the mean number of vertices a certain distance away from a randomly chosen vertex and the average vertex vertex distance within a graph we apply our theory to some real world graphs including the worldwide web and collaboration graphs of scientists and fortune 1000 company directors we demonstrate that in some cases random graphs with appropriate distributions of vertex degree predict with surprising accuracy the behavior of the real world while in others there is a measurable discrepancy between theory and reality perhaps indicating the presence of additional social structure in the network that is not captured by the random graph

robust observer design for unknown inputs takagi sugeno models this paper deals with the observer design for takagi sugeno t s fuzzy models subject to unknown inputs and disturbance affecting both states and outputs of the system sufficient conditions to design an unknown input t s observer are given in linear matrix inequality lmi terms both continuous time and discrete time cases are studied relaxations are introduced by using intermediate variables extension to the case of unmeasured decision variables is also given a numerical example is given to illustrate the effectiveness of the given results

interfaces and the edge percolation map of random directed networks the traditional node percolation map of directed networks is reanalyzed in terms of edges in the percolated phase edges can mainly organize into five distinct giant connected components interfaces bridging the communication of nodes in the strongly connected component and those in the in and out components formal equations for the relative sizes in the number of edges of these giant structures are derived for arbitrary joint degree distributions in the presence of local and two point correlations the uncorrelated null model is fully solved analytically and compared against simulations finding an excellent agreement interfaces and their particular conformations giving place from hairy ball percolation landscapes to bottleneck straits could bring new light to the discussion of how a structure is interwoven with functionality in flow networks

technical communique fixed poles of simultaneous disturbance rejection and decoupling a geometric approach when the simultaneous disturbance rejection and regular block decoupling problem by static state feedback is solvable and under some unrestrictive minimality assumption all the poles of the closed loop system can be placed except the so called fixed poles which are present for any solution we present here a geometric characterization for this set of fixed poles as well as a constructive procedure based on geometric tools for designing a feedback solution of the problem which assigns the remaining poles to arbitrary prespecified locations

local analysis of continuous time takagi sugeno fuzzy system with disturbances bounded by magnitude or energy a lagrange multiplier method abstract this paper is concerned with the problem of computing the bounds of disturbances for continuous time takagi sugeno fuzzy model two kinds of disturbances are investigated by applying the non parallel distributed compensation non pdc law non quadratic lyapunov function and lagrange multiplier method one is bounded by magnitude the other is bounded by energy if the exogenous disturbances are bounded by magnitude the maximal value of the magnitude under which the closed loop system can be controlled is obtained by solving an optimization problem on the other hand if the disturbances are bounded by energy except for the maximal bound some conditions are derived to get two local regions a smaller and a bigger such that all the trajectories starting from the smaller region will remain in the bigger one which is required to be contained in a specific compact set where the original system can be represented as t s model exactly in the end the effectiveness of the proposed results is demonstrated by two examples

switching type h filter design for t s fuzzy systems with unknown or partially unknown membership functions this paper is concerned with the h filter design problem for takagi sugeno t s fuzzy systems with unknown or partially unknown membership functions if the membership functions are allowed to be unknown or partially unknown then a fuzzy system may describe a wide class of nonlinear systems however in this case the filter design of fuzzy systems which is based on parallel distributed compensator strategy is infeasible to tackle this difficulty a switching mechanism which depends on the lower and upper bounds of the unknown membership functions is introduced to construct the h filter with varying gains some examples given in the simulation section show that the proposed method can achieve a better disturbance attenuation performance than a simple fixed gain filter design approach

generalized percolation in random directed networks we develop a general theory for percolation in directed random networks with arbitrary two point correlations and bidirectional edges that is edges pointing in both directions simultaneously these two ingredients alter the previously known scenario and open new views and perspectives on percolation phenomena equations for the percolation threshold and the sizes of the giant components are derived in the most general case we also present simulation results for a particular example of uncorrelated network with bidirectional edges confirming the theoretical predictions