design of capacity approaching irregular low density parity check codes we design low density parity check ldpc codes that perform at rates extremely close to the shannon capacity the codes are built from highly irregular bipartite graphs with carefully chosen degree patterns on both sides our theoretical analysis of the codes is based on the work of richardson and urbanke see ibid vol 47 no 2 p 599 618 2000 assuming that the underlying communication channel is symmetric we prove that the probability densities at the message nodes of the graph possess a certain symmetry using this symmetry property we then show that under the assumption of no cycles the message densities always converge as the number of iterations tends to infinity furthermore we prove a stability condition which implies an upper bound on the fraction of errors that a belief propagation decoder can correct when applied to a code induced from a bipartite graph with a given degree distribution our codes are found by optimizing the degree structure of the underlying graphs we develop several strategies to perform this optimization we also present some simulation results for the codes found which show that the performance of the codes is very close to the asymptotic theoretical bounds

global stabilization for a class of switched nonlinear feedforward systems abstract the problem of global stabilization for a class of switched nonlinear feedforward systems under arbitrary switchings is investigated in this paper based on the integrator forwarding technique and the common lyapunov function method we design bounded state feedback controllers of individual subsystems to guarantee asymptotic stability of the closed loop system a common coordinate transformation of all subsystems is exploited to avoid individual coordinate transformations for subsystems that are required when applying the forwarding recursive design scheme an example is provided to demonstrate the effectiveness of the proposed design method

improved linear matrix inequality approach to stability analysis of linear systems with interval time varying delays this paper investigates the problem of stability analysis for a class of linear systems with interval time varying delay in order to develop a less conservative stability condition a lyapunov krasovskii functional comprising novel integral terms is introduced convex combination idea is utilized to derive a stability criterion in terms of linear matrix inequalities lmis without any additional free weighting matrices which increase drastically the computational burden of the stability test numerical examples are presented to illustrate the superiority of the proposed approach compared to some existing ones in the literature

generalizations of the fkkm theorem and the ky fan minimax inequality with applications to maximal elements price equilibrium and complementarity abstract this paper generalizes the fan knaster kuratowski mazurkiewicz fkkm theorem of ky fan game theory and related topics pp 151 156 north holland amsterdam 1979 and math ann 266 1984 519 537 and the ky fan minimax inequality by introducing a class of the generalized closedness and continuity conditions which are called the transfer closedness and transfer continuities we then apply these results to prove the existence of maximal elements of binary relations under very weak assumptions we also prove the existence of price equilibrium and the complementarity problem without the continuity assumptions thus our results generalize many of the existence theorems in the literature

set valued versions of ky fan s inequality with application to variational inclusion theory in this paper we prove two set valued versions of ky fan s minimax inequality from these results versions of schauder s and kakutani s fixed point theorems can be deduced we formulate a variational inclusion problem for set valued maps and a differential inclusion problem concerning the contingent derivative sufficient conditions for the existence of solution for these inclusion problems are obtained generalizing classical variational inequality problems

a new control method for state constrained nonlinear switched systems with application to chemical process this paper presents a new control method for a class of nonlinear switched systems in strict feedback form with a state constraint in the proposed approach a nonlinear mapping is first introduced to transform the problem of controlling the switched system with state constraint to a new problem of regulating the transformed system without a constraint by using the backstepping technique the designed state feedback controller ensures that the corresponding closed loop system is asymptotically stable without violation of the constraint and that all closed loop signals keep bounded furthermore we explore the use of a coordinate transformation to deal with an asymmetric state constraint as a generalised approach in the end an application example on a chemical process is shown to demonstrate the efficacy of the obtained results

variational conclusions of set valued bifunctions on convex subsets of banach spaces with applications in this paper variational conclusions of set valued bifunctions on convex subsets of banach spaces are investigated and several new results are obtained the results are applied to the fixed point theory and variational inequalities we obtain two fixed point theorems and existence theorems of solutions of variational inequalities

adaptive methods for linear programming decoding detectability of failures of linear programming lp decoding and the potential for improvement by adding new constraints motivate the use of an adaptive approach in selecting the constraints for the underlying lp problem in this paper we make a first step in studying this method and show that by starting from a simple lp problem and adaptively adding the necessary constraints the complexity of lp decoding can be significantly reduced in particular we observe that with adaptive lp decoding the sizes of the lp problems that need to be solved become practically independent of the density of the parity check matrix we further show that adaptively adding extra constraints such as constraints based on redundant parity checks can provide large gains in the performance

robust exponential stability of uncertain systems with time varying delays focuses on the problem of robust exponential stability of a class of uncertain systems described by functional differential equations with time varying delays the uncertainties are assumed to be continuous time varying nonlinear and norm bounded sufficient conditions for robust exponential stability are given for both single and multiple delays cases

switched observer based adaptive neural control of mimo switched nonlinear systems with unknown control gains in this paper the problem of adaptive neural output feedback control is addressed for a class of multi input multioutput mimo switched uncertain nonlinear systems with unknown control gains neural networks nns are used to approximate unknown nonlinear functions in order to avoid the conservativeness caused by adoption of a common observer for all subsystems an mimo nn switched observer is designed to estimate unmeasurable states a new switched observer based adaptive neural control technique for the problem studied is then provided by exploiting the classical average dwell time adt method and the backstepping method and the nussbaum gain technique it effectively handles the obstacle about the coexistence of multiple nussbaum type function terms and improves the classical adt method since the exponential decline property of lyapunov functions for individual subsystems is no longer satisfied it is shown that the technique proposed is able to guarantee semiglobal uniformly ultimately boundedness of all the signals in the closed loop system under a class of switching signals with adt and the tracking errors converge to a small neighborhood of the origin the effectiveness of the approach proposed is illustrated by its application to a two inverted pendulum system

analysis of sum product decoding of low density parity check codes using a gaussian approximation density evolution is an algorithm for computing the capacity of low density parity check ldpc codes under message passing decoding for memoryless binary input continuous output additive white gaussian noise awgn channels and sum product decoders we use a gaussian approximation for message densities under density evolution to simplify the analysis of the decoding algorithm we convert the infinite dimensional problem of iteratively calculating message densities which is needed to find the exact threshold to a one dimensional problem of updating the means of the gaussian densities this simplification not only allows us to calculate the threshold quickly and to understand the behavior of the decoder better but also makes it easier to design good irregular ldpc codes for awgn channels for various regular ldpc codes we have examined thresholds can be estimated within 0 1 db of the exact value for rates between 0 5 and 0 9 codes designed using the gaussian approximation perform within 0 02 db of the best performing codes found so far by using density evolution when the maximum variable degree is 10 we show that by using the gaussian approximation we can visualize the sum product decoding algorithm we also show that the optimization of degree distributions can be understood and done graphically using the visualization

constructing free energy approximations and generalized belief propagation algorithms important inference problems in statistical physics computer vision error correcting coding theory and artificial intelligence can all be reformulated as the computation of marginal probabilities on factor graphs the belief propagation bp algorithm is an efficient way to solve these problems that is exact when the factor graph is a tree but only approximate when the factor graph has cycles we show that bp fixed points correspond to the stationary points of the bethe approximation of the free energy for a factor graph we explain how to obtain region based free energy approximations that improve the bethe approximation and corresponding generalized belief propagation gbp algorithms we emphasize the conditions a free energy approximation must satisfy in order to be a valid or maxent normal approximation we describe the relationship between four different methods that can be used to generate valid approximations the bethe method the junction graph method the cluster variation method and the region graph method finally we explain how to tell whether a region based approximation and its corresponding gbp algorithm is likely to be accurate and describe empirical results showing that gbp can significantly outperform bp

new results on stability of discrete time systems with time varying state delay this note is concerned with the stability analysis of discrete time systems with time varying state delay by defining new lyapunov functions and by making use of novel techniques to achieve delay dependence several new conditions are obtained for the asymptotic stability of these systems the merit of the proposed conditions lies in their less conservativeness which is achieved by circumventing the utilization of some bounding inequalities for cross products between two vectors and by paying careful attention to the subtle difference between the terms sigmam k dk k 1 middot and sigma m k dm k 1 middot which is largely ignored in the existing literature these conditions are shown via several examples to be much less conservative than some existing result

sampled data fuzzy control for a class of nonlinear systems with missing data and disturbances this paper considers the sampled data fuzzy control of nonlinear systems in strict feedback form with disturbances and random missing input data we propose a novel method in which a state observer and a disturbance observer are combined to construct a sampled data fuzzy output feedback controller the stochastic variables with a bernoulli distributed sequence are used to model missing input data fuzzy logic systems are applied to approximate nonlinearities without requiring prior knowledge the relation between observer gain and sampling period is established the output feedback controller designed guarantees that the nonlinear system is globally stable a simulation example of four degrees of freedom robotic arm is used to demonstrate the effectiveness and applicability of the proposed control scheme

using linear programming to decode binary linear codes a new method is given for performing approximate maximum likelihood ml decoding of an arbitrary binary linear code based on observations received from any discrete memoryless symmetric channel the decoding algorithm is based on a linear programming lp relaxation that is defined by a factor graph or parity check representation of the code the resulting lp decoder generalizes our previous work on turbo like codes a precise combinatorial characterization of when the lp decoder succeeds is provided based on pseudocodewords associated with the factor graph our definition of a pseudocodeword unifies other such notions known for iterative algorithms including stopping sets irreducible closed walks trellis cycles deviation sets and graph covers the fractional distance d sub frac of a code is introduced which is a lower bound on the classical distance it is shown that the efficient lp decoder will correct up to spl lceil d sub frac 2 spl rceil 1 errors and that there are codes with d sub frac spl omega n sup 1 spl epsi an efficient algorithm to compute the fractional distance is presented experimental evidence shows a similar performance on low density parity check ldpc codes between lp decoding and the min sum and sum product algorithms methods for tightening the lp relaxation to improve performance are also provided

synchronization of sampled data coupled harmonic oscillators with control inputs missing abstract this paper is concerned with the synchronization problem of sampled data coupled harmonic oscillators with control inputs missing a distributed algorithm for synchronization in undirected networks of coupled harmonic oscillators is proposed based on the sampled data measurement with controller failures some generic criteria for such algorithm over respectively undirected fixed and switching network topologies are derived analytically compared with some existing works a distinctive feature of this work is to solve synchronization problem in undirected networks even if each oscillator intermittently exchanges the velocity information with its neighbors in terms of sampled data setting only at discrete moments subsequently numerical examples illustrate and visualize the effectiveness and feasibility of the theoretical results

a parameter dependent approach to robust h_ infty filtering for time delay systems this paper is concerned with the problem of robust h infin filtering for linear continuous time systems with polytopic parameter uncertainties and time varying delay in the state we utilize the polynomially parameter dependent idea to solve the robust h infin filtering problem with new linear matrix inequality conditions obtained for the existence of admissible filters these conditions are developed based on homogeneous polynomially parameter dependent matrices of arbitrary degree the delay dependence and polynomial parameter dependence guarantee the proposed approach to be potentially less conservative which is shown via a numerical example

technical communique absolute stability of time delay systems with sector bounded nonlinearity this paper deals with the problem of absolute stability of time delay systems with sector bounded nonlinearity some new delay dependent stability criteria are obtained and formulated in the form of linear matrix inequalities lmis neither model transformation nor bounding technique for cross terms is involved through derivation of the stability criteria numerical examples show that the results obtained in this paper improve the estimate of the stability limit over some existing result

stabilization of sampled data control systems with control inputs missing this note is concerned with the stabilization problem for sampled data control systems with control inputs missing a sufficient condition is derived for the existence of exponentially stabilizing state feedback controllers via the switched system approach the obtained condition establishes several quantitative relations among some system parameters such as the sampling period and the exponential decay rate the actual data missing rate and the admissible data missing rate bound two illustrative examples are given to show the effectiveness of the proposed results

delay dependent stabilization of linear systems with time varying state and input delays the integral inequality method is a new way of tackling the delay dependent stabilization problem for a linear system with time varying state and input delays email protected t ax t a 1x t h 1 t b 1u t b 2u t h 2 t in this paper a new integral inequality for quadratic terms is first established then it is used to obtain a new state and input delay dependent criterion that ensures the stability of the closed loop system with a memoryless state feedback controller finally some numerical examples are presented to demonstrate that control systems designed based on the criterion are effective even though neither a b 1 nor a a 1 b 1 is stabilizable

consensus tracking for higher order multi agent systems with switching directed topologies and occasionally missing control inputs abstract this paper studies the distributed consensus tracking problem of linear higher order multi agent systems with switching directed topologies and occasionally missing control inputs in this framework the underlying topology of dynamic agents may switch among several directed graphs each having a directed spanning tree rooted at the leader furthermore the control inputs to the followers may be temporally missed due to actuator failures and network induced packet loss to guarantee asymptotic consensus tracking in such a multi agent system several distributed controllers are constructed based only on the relative state information of neighboring agents by appropriately constructing a switching lyapunov function and using tools from the m matrix theory some sufficient conditions for achieving distributed consensus tracking are provided finally some numerical simulations are given to illustrate the theoretical analysis

applications of ky fan s inequality on σ compact set to variational inclusion and n person game theory in this paper ky fan s inequality on compact set is applied to variational inclusions and n person game theory we give results of some variational inclusions and existence of non cooperative equilibrium in n person game on compact set

on the stability of linear systems with uncertain delay this paper focuses on the stability of some class of delay systems including uncertainty in the delays more precisely we are interested in guaranteeing the stability of perturbed delay systems by assuming the stability of the nominal system if the delay perturbation is constant necessary and sufficient conditions are derived in terms of generalized eigenvalue distribution of some finite dimensional constant matrix pencil if the delay perturbation is time varying some sufficient stability conditions are derived using exact lyapunov krasovskii functionals illustrative examples are also included

stability and l2 gain analysis for switched delay systems a delay dependent method in this paper we study stability and l 2 gain for a class of switched systems with time varying delays sufficient conditions for exponential stability and weighted l 2 gain are developed for a class of switching signals with average dwell time these conditions are delay dependent and are given in the form of linear matrix inequalities lmis as a special case of such switching signals we can obtain exponential stability and normal l 2 gain under arbitrary switching signals the state decay estimate is explicitly given two examples illustrate the effectiveness and applicability of the proposed method

on the decomposition method for linear programming decoding of ldpc codes in this paper we focus on solving the linear programming lp problem that arises in the decoding of low density parity check ldpc codes by means of the revised simplex method in order to take advantage of the structure of the lp problem we reformulate the dual lp and apply the idea of dantzig wolfe d w decomposition method to solve the problem each subproblem in the d w decomposition method is an lp over a convex polyhedral cone we define the convex polyhedral cone as local parity check cone and discuss its special structures then we enumerate its extreme rays and use these extreme rays to design an efficient method for the general lp decoding problem the proposed method exhibits advantages in reducing both the storage and computational requirements

on h control for linear systems with interval time varying delay this paper deals with the problem of delay dependent robust h control for linear time delay systems with norm bounded and possibly time varying uncertainty the time delay is assumed to be a time varying continuous function belonging to a given interval which means that the lower and upper bounds for the time varying delay are available and no restriction on the derivative of the time varying delay is needed which allows the time delay to be a fast time varying function based on an integral inequality which is introduced in this paper and lyapunov krasovskii functional approach a delay dependent bounded real lemma brl is first established without using model transformation and bounding techniques on the related cross product terms then employing the obtained brl a delay dependent condition for the existence of a state feedback controller which ensures asymptotic stability and a prescribed h performance level of the closed loop systems for all admissible uncertainties is proposed in terms of a linear matrix inequality lmi a numerical example is also given to illustrate the effectiveness of the proposed method

effects of mixed modes on the stability analysis of switched time varying delay systems a phenomenon known as mixed mode occurs naturally in switched delay systems and it makes the stability analysis for such systems a challenge especially for the case of time varying delays this note aims to investigate the effects of mixed modes on the stability analysis of switched time varying delay systems which are motivated from networked control applications by constructing a lyapunov krasovskii functional and using the estimation of quadrature as well as the average dwell time approach new exponential stability conditions are given for the switched time varying delay systems with both stable and unstable subsystems this can be seen as a generalization of existing results that mainly focus on the cases of constant delay and all stable subsystems finally simulation examples are presented to illustrate the developed results

decomposition methods for large scale lp decoding when binary linear error correcting codes are used over symmetric channels a relaxed version of the maximum likelihood decoding problem can be stated as a linear program lp this lp decoder can be used to decode error correcting codes at bit error rates comparable to state of the art belief propagation bp decoders but with significantly stronger theoretical guarantees however lp decoding when implemented with standard lp solvers does not easily scale to the block lengths of modern error correcting codes in this paper we draw on decomposition methods from optimization theory specifically the alternating direction method of multipliers admm to develop efficient distributed algorithms for lp decoding the key enabling technical result is a two slice characterization of the parity polytope the polytope formed by taking the convex hull of all codewords of the single parity check code this new characterization simplifies the representation of points in the polytope using this simplification we develop an efficient algorithm for euclidean norm projection onto the parity polytope this projection is required by the admm decoder and its solution allows us to use lp decoding with all its theoretical guarantees to decode large scale error correcting codes efficiently we present numerical results for ldpc codes of lengths more than 1000 the waterfall region of lp decoding is seen to initiate at a slightly higher snr than for sum product bp however an error floor is not observed for lp decoding which is not the case for bp our implementation of lp decoding using the admm executes as fast as our baseline sum product bp decoder is fully parallelizable and can be seen to implement a type of message passing with a particularly simple schedule

parameter dependent lyapunov functional for stability of time delay systems with polytopic type uncertainties this note concerns the problem of the robust stability of a linear system with a time varying delay and polytopic type uncertainties in order to construct a parameter dependent lyapunov functional for the system we first devised a new method of dealing with a time delay system without uncertainties in this method the derivative terms of the state which is in the derivative of the lyapunov functional are retained and some free weighting matrices are used to express the relationships among the system variables and among the terms in the leibniz newton formula as a result the lyapunov matrices are not involved in any product terms of the system matrices in the derivative of the lyapunov functional this method is then easily extended to a system with polytopic type uncertainties numerical examples demonstrate the validity of the proposed criteria

delay independent stabilization of a class of time delay systems via periodically intermittent control the problem of delay independently periodically intermittent stabilization for a class of time delay systems is examined first the stability of the considered periodically intermittently controlled time delay systems is analyzed by using the piecewise switching time dependent lyapunov function functional the introduced lyapunov function functional is nonincreasing at switching instants which can guarantee the exponential stability of the considered systems irrespective of the sizes of the state delays next based on the newly established stability criteria sufficient conditions for the existence of delay independently periodically intermittent state feedback controllers are derived finally two illustrative examples are presented to show the validity of the obtained results

stability of systems with controller failure and time varying delay this paper studies the stability for a class of systems with time varying delay subject to controller failure it explores under what conditions of controller failure the system is still exponentially stable the concept of controller failure frequency is introduced first the delay system with failed controller is modelled as a class of switched delay systems next based on two lemmas developed in this paper and the piecewise lyapunov functional method sufficient conditions are provided to guarantee the exponential stability of the system when controller failure occurs which is in terms of the solvability of a set of linear matrix inequalities lmis finally an example of a networked control system is given to illustrate the effectiveness of the proposed method

h_ infty control of switched nonlinear systems in p normal form using multiple lyapunov functions the problem of h control of switched nonlinear systems in p normal form is investigated in this technical note where the solvability of the h control problem for individual subsystems is unnecessary using the generalized multiple lyapunov functions method and the adding a power integrator technique we design a switching law and construct continuous state feedback controllers of subsystems explicitly by a recursive design algorithm to produce global asymptotical stability and a prescribed h performance level multiple lyapunov functions are exploited to reduce the conservativeness caused by adoption of a common lyapunov function for all subsystems which is usually required when applying the backstepping like recursive design scheme an example is provided to demonstrate the effectiveness of the proposed design method

on the existence of solutions of variational inequalities in banach spaces abstract in this paper we study the existence of the solution of the variational inequality tx y x 0 by applying the generalized projection operator k b b where b is a banach space with dual space b and by using the well known fankkm theorem

the generalized projection operator on reflexive banach spaces and its applications abstract in this paper we extend the definition of the generalized projection operator k b k where b is a reflexive banach space with dual space b and k is a nonempty closed and convex subset of b and we study its properties and applications to solving variational inequality

the mann and ishikawa iterative approximation of solutions to variational inclusions with accretive type mappings abstract the purpose of this paper is to introduce and study the existence of solutions and convergence of mann and ishikawa iterative processes for a class of variational inclusions with accretive type mappings in banach spaces the results presented in this paper extend and improve the corresponding results of 1 9

systems of nonempty intersection theorems with applications in this paper we study the systems of nonempty intersection theorems by the systems of nonempty intersection theorems we can study the existence theorem of systems of quasi kkm problems the existence theorems of systems of quasi variational inclusions problems the existence theorems of systems of quasi variational disclusions problems and fixed point theorem we also establish some of their equivalent relations

delay dependent robust stabilization of uncertain state delayed systems this paper concerns a problem of robust stabilization of uncertain state delayed systems a new delay dependent stabilization condition using a memoryless controller is formulated in terms of matrix inequalities an algorithm involving convex optimization is proposed to design a controller guaranteeing a suboptimal maximal delay such that the system can be stabilized for all admissible uncertainties

improved delay dependent stability criteria for time delay systems this note provides an improved asymptotic stability condition for time delay systems in terms of a strict linear matrix inequality unlike previous methods the mathematical development avoids bounding certain cross terms which often leads to conservatism when time varying norm bounded uncertainties appear in a delay system an improved robust delay dependent stability condition is also given examples are provided to demonstrate the reduced conservatism of the proposed conditions

adaptive tracking control for discrete time switched nonlinear systems with dead zone inputs abstract this paper studies the adaptive tracking control problem of a discrete time switched nonlinear system with dead zone input under a class of switching signals with average dwell time due to the complicated structure of the discrete time switched nonlinear systems and the existence of the dead zone it makes a great obstacle for controlling such a class of systems the fuzzy logic systems are employed to approximate the unknown terms of each subsystem in addition both stable subsystems and unstable subsystems are considered the controllers of subsystems update laws and switching signals are designed such that the closed loop system is stable and all the signals are bounded finally a simulation example is employed to illustrate the effectiveness of the proposed method

a delay dependent stability criterion for systems with uncertain time invariant delays this paper provides a new stability criterion for systems with time invariant uncertain delays based on an improved upper bound for the inner product of two vectors a new delay dependent robust stability criterion is derived which is shown by an example less conservative than existing stability criteria

variational inclusions for contingent derivative of set valued maps in this paper we give two versions of ky fan s inequality for set valued maps acting between normed vector spaces and we consider sufficient conditions to solve a variational inclusion problem concerning derivatives of set valued maps a selection result for set valued maps between finite dimensional vector spaces and its contingent derivative is obtained as well from this result we derive some conditions for the existence of a solution of a generalized variational inequality problem

new results on a delay derivative dependent fuzzy h infty filter design for t s fuzzy systems this paper focuses on the fuzzy h filter design problem for takagi sugeno t s fuzzy systems with interval time varying delays two cases of the time varying delays are considered 1 the delays are differentiable and have both the lower and upper bounds of the delay derivatives and 2 the delays are bounded but not necessary to be differentiable since we employ a new fuzzy lyapunov krasovskii functional lkf and estimate a tighter upper bound of its derivative the proposed delay derivative dependent bound real lemma brl condition has advantages over some previous results in that it enlarges the application scope but has less conservatism which is established theoretically the brl condition that depends on both the upper and lower bounds of the delay derivatives is derived then based on the aforesaid brl a new fuzzy h filter scheme is proposed and a sufficient condition for the existence of such a filter is established in terms of linear matrix inequalities lmis finally some numerical examples and an application to the truck trailer system are utilized to demonstrate the effectiveness and reduced conservatism of our results

technical communique delay range dependent stability for systems with time varying delay this paper is concerned with the stability analysis for systems with time varying delay in a range an appropriate type of lyapunov functionals is proposed to investigate the delay range dependent stability problem the present results may improve the existing ones due to a method to estimate the upper bound of the derivative of lyapunov functional without ignoring some useful terms and the introduction of additional terms into the proposed lyapunov functional which take into account the range of delay numerical examples are given to demonstrate the effectiveness and the benefits of the proposed method

stability analysis and failure tolerant control for discrete time linear systems with controller failure in this paper the stability and failure tolerant control are investigated for discrete time time invariant linear systems with occasional controller failure due to physical or purposeful reason by introducing the conceptions of minimal controller reliable time and maximal controller failure time a novel time varying piecewise quadratic lyapunov function tpqlf approach is proposed to analyse the stability property of closed loop system in presence of controller failure the presented tpqlf method combines both merits of previous lyapunov function based results such as common lyapunov function and piecewise lyapunov function approaches furthermore based on tpqlf the feasible region described by pairs of minimal controller reliable time and maximal controller failure time can be easily computed by an iterative algorithm then on the basis of the analysis results time varying state feedback gains are formulated to construct failure tolerant controller it is demonstrated that the time varying struct

improved delay dependent robust stability criteria for uncertain time delay systems abstract this paper deals with the robust stability analysis for uncertain systems with time varying delay new delay dependent robust stability criteria of uncertain time delay systems are proposed by exploiting appropriate lyapunov functional candidate these developed results have advantages over some previous ones in that they have fewer matrix variables yet less conservatism due to the introduction of a method to estimate the upper bound of the derivative of lyapunov functional candidate without ignoring the additional useful terms numerical examples are given to demonstrate the effectiveness and the advantage of the proposed method

further improvement of free weighting matrices technique for systems with time varying delay a novel method is proposed in this note for stability analysis of systems with a time varying delay appropriate lyapunov functional and augmented lyapunov functional are introduced to establish some improved delay dependent stability criteria less conservative results are obtained by considering the additional useful terms which are ignored in previous methods when estimating the upper bound of the derivative of lyapunov functionals and introducing the new free weighting matrices the resulting criteria are extended to the stability analysis for uncertain systems with time varying structured uncertainties and polytopic type uncertainties numerical examples are given to demonstrate the effectiveness and the benefits of the proposed method

brief paper a novel stability analysis of linear systems under asynchronous samplings this article proposes a novel approach to assess the stability of continuous linear systems with sampled data inputs the method which is based on the discrete time lyapunov theorem provides easy tractable stability conditions for the continuous time model sufficient conditions for asymptotic and exponential stability are provided dealing with synchronous and asynchronous samplings and uncertain systems an additional stability analysis is provided for the cases of multiple sampling periods and packet losses several examples show the efficiency of the method

impulsive practical tracking synchronization of networked uncertain lagrangian systems without and with time delays abstract this paper presents a procedure for studying tracking synchronization of networked lagrangian systems via impulsive control where each agent is allowed to be nonidentical even uncertain dynamics some algebraic criteria for tracking synchronization without and with time delays are established respectively it turns out that these criteria can provide a novel impulsive control strategy to synchronize globally networked lagrangian systems to a given time varying target trajectory with a desired tracking error bound called as practical tracking synchronization a distinctive feature of the developed control strategy is fully to take into account the effects of impulsive constraints and thereby to yield impulsive synchronization motion of networked lagrangian systems provided that each agent instantaneously interacts with its neighbors only at some discrete moments as a direct application of the theoretical results practical tracking synchronization of nonidentical 3 dof mobile robots without and with time delays is discussed in detail simulation results illustrate and visualize the effectiveness and feasibility of the proposed control technique

spectral necessary and sufficient conditions for sampling period independent stabilisation of periodic and aperiodic sampled data systems using a class of generalised sampled data hold functions sampling period independent spi stabilisation of both periodic and aperiodic sampled data systems using a class of generalised sampled data hold functions is addressed it is proved that for this specific class of hold functions a continuous time linear system with rank minimal input matrix and with non defective eigenvalues on the imaginary axis is spi stabilisable if and only if the spectrum of the system is contained in the closed left half plane a systematic procedure for constructing suitable state feedback controllers is also provided several examples are finally discussed for illustration