exponential stability of impulsive systems with application to uncertain sampled data systems we establish exponential stability of nonlinear time varying impulsive systems by employing lyapunov functions with discontinuity at the impulse times our stability conditions have the property that when specialized to linear impulsive systems the stability tests can be formulated as linear matrix inequalities lmis then we consider lti uncertain sampled data systems in which there are two sources of uncertainty the values of the process parameters can be unknown while satisfying a polytopic condition and the sampling intervals can be uncertain and variable we model such systems as linear impulsive systems and we apply our theorem to the analysis and state feedback stabilization we find a positive constant which determines an upper bound on the sampling intervals for which the stability of the closed loop is guaranteed the control design lmis also provide controller gains that can be used to stabilize the process we also consider sampled data systems with constant sampling intervals and provide results that are less conservative than the ones obtained for variable sampling intervals

an adaptive gmsfem for high contrast flow problems in this paper we derive an a posteriori error indicator for the generalized multiscale finite element method gmsfem framework this error indicator is further used to develop an adaptive enrichment algorithm for the linear elliptic equation with multiscale high contrast coefficients the gmsfem which has recently been introduced in 13 allows solving multiscale parameter dependent problems at a reduced computational cost by constructing a reduced order representation of the solution on a coarse grid the main idea of the method consists of 1 the construction of snapshot space 2 the construction of the offline space and 3 the construction of the online space the latter for parameter dependent problems in 13 it was shown that the gmsfem provides a flexible tool to solve multiscale problems with a complex input space by generating appropriate snapshot offline and online spaces in this paper we study an adaptive enrichment procedure and derive an a posteriori error indicator which gives an estimate of the local error over coarse grid regions we consider two kinds of error indicators where one is based on the l 2 norm of the local residual and the other is based on the weighted h 1 norm of the local residual where the weight is related to the coefficient of the elliptic equation we show that the use of weighted h 1 norm residual gives a more robust error indicator which works well for cases with high contrast media the convergence analysis of the method is given in our analysis we do not consider the error due to the fine grid discretization of local problems and only study the errors due to the enrichment numerical results are presented that demonstrate the robustness of the proposed error indicators

numerical analysis of elliptic hemivariational inequalities this paper is devoted to a study of the numerical solution of elliptic hemivariational inequalities with or without convex constraints by the finite element method for a general family of elliptic

discrete and intersample analysis of systems with aperiodic sampling this article addresses the stability analysis of linear time invariant systems with aperiodic sampled data control adopting a difference inclusion formalism we show that necessary and sufficient stability conditions are given by the existence of discrete time quasi quadratic lyapunov functions a constructive method for computing such functions is provided from the approximation of the necessary and sufficient conditions in practice this leads to sufficient stability criteria under lmi form the inter sampling behavior is discussed there based on differential inclusions we provide continuous time methods that use the advantages of the discrete time approach the results are illustrated by numerical examples that indicate the improvement with regard to the existing literature

towards human consistent multistage decision making and control models using fuzzy sets and fuzzy logic abstract fuzzy multistage decision making control models are presented two generations of them are distinguished the first consists of conventional models derived from bellman and zadeh s general framework fuzzy constraints goals decision etc the second consists of newer approaches which additionally allow for a more general aggregation of control stage scores outcomes e g at most of the control stages instead of at all conventionally used both generations have roots in papers co authored by bellman they are further steps towards human consistent soft models whose implementation should be much easier

optimal h filtering for singular markovian jump systems abstract this paper considers h filtering for continuous time singular markovian jump systems smjss while the existing researches in the literature suggested only sufficient conditions in terms of strict or non strict linear matrix inequalities lmis for sub optimal h filtering this paper successfully derives a necessary and sufficient condition in terms of strict lmis for optimal h filtering first the necessary and sufficient condition that guarantees the stochastic admissibility of the filtering error system is obtained in terms of matrix inequalities to reformulate it into strict lmis the congruence transformation by specially designed matrices is used two numerical examples show the validity of proposed h filtering

model approximation for discrete time state delay systems in the t s fuzzy framework this paper is concerned with the problem of h model approximation for discrete time takagi sugeno t s fuzzy time delay systems for a given stable t s fuzzy system our attention is focused on the construction of a reduced order model which not only approximates the original system well in an h performance but is also translated into a linear lower dimensional system by applying the delay partitioning approach a delay dependent sufficient condition is proposed for the asymptotic stability with an h error performance for the error system then the h model approximation problem is solved by using the projection approach which casts the model approximation into a sequential minimization problem subject to linear matrix inequality lmi constraints by employing the cone complementary linearization algorithm moreover by further extending the results h model approximation with special structures is obtained i e delay free model and zero order model finally two numerical examples are provided to illustrate the effectiveness of the proposed methods

a mixed multiscale finite element method for elliptic problems with oscillating coefficients the recently introduced multiscale finite element method for solving elliptic equations with oscillating coefficients is designed to capture the large scale structure of the solutions without resolving all the fine scale structures motivated by the numerical simulation of flow transport in highly heterogeneous porous media we propose a mixed multiscale finite element method with an over sampling technique for solving second order elliptic equations with rapidly oscillating coefficients the multiscale finite element bases are constructed by locally solving neumann boundary value problems we provide a detailed convergence analysis of the method under the assumption that the oscillating coefficients are locally periodic while such a simplifying assumption is not required by our method it allows us to use homogenization theory to obtain the asymptotic structure of the solutions numerical experiments are carried out for flow transport in a porous medium with a random log normal relative permeability to demonstrate the efficiency and accuracy of the proposed method

convergence of a multiscale finite element method for elliptic problems with rapidly oscillating coefficients we propose a multiscale finite element method for solving second order elliptic equations with rapidly oscillating coefficients the main purpose is to design a numerical method which is capable of correctly capturing the large scale components of the solution on a coarse grid without accurately resolving all the small scale features in the solution this is accomplished by incorporating the local microstructures of the differential operator into the finite element base functions as a consequence the base functions are adapted to the local properties of the differential operator in this paper we provide a detailed convergence analysis of our method under the assumption that the oscillating coefficient is of two scales and is periodic in the fast scale while such a simplifying assumption is not required by our method it allows us to use homogenization theory to obtain a useful asymptotic solution structure the issue of boundary conditions for the base functions will be discussed our numerical experiments demonstrate convincingly that our multiscale method indeed converges to the correct solution independently of the small scale in the homogenization limit application of our method to problems with continuous scales is also considered

technical communique stability and stabilization of nonuniform sampling systems this paper is concerned with nonuniform sampling systems where the sampling interval is time varying within a certain known bound the system is transformed into a time varying discrete time system where time varying parts due to the sampling interval variation are treated as norm bounded uncertainties using robust control techniques to reduce conservatism arising from modeling time varying parts as a single uncertainty the time varying parts are modeled as n uncertainties with larger n a less conservative stability condition is derived at sacrifice of more computation it is shown through a numerical example that the proposed stability condition is better than existing stability conditions

stability analysis and performance design for fuzzy model based control system under imperfect premise matching this paper investigates the stability analysis and performance design of nonlinear systems to facilitate the stability analysis the takagi sugeno t s fuzzy model is employed to represent the nonlinear plant under the imperfect premise matching in which t s fuzzy model and fuzzy controller do not share the same membership functions a fuzzy controller with enhanced design flexibility and robustness property is proposed to control the nonlinear plant however the nice characteristic given by the perfect premise matching leading to conservative stability conditions vanishes in this paper under the imperfect premise matching information of membership functions of the fuzzy model and controller are considered in stability analysis with the introduction of slack matrices relaxed linear matrix inequality lmi based stability conditions are derived using lyapunov based approach furthermore lmi based performance conditions are provided to guarantee system performance simulation examples are given to illustrate the effectiveness of the proposed approach

convergence rate of multiscale finite element method for various boundary problems abstract in this paper we examine the effectiveness of classic multiscale finite element method msfem hou and wu 1997 hou et al 1999 for mixed dirichlet neumann robin and hemivariational inequality boundary problems constructing so called boundary correctors is a common technique in existing methods to prove the convergence rate of msfem while we think not reflects the essence of those problems instead we focus on the first order expansion structure through recently developed estimations in homogenization theory our convergence rate is provided with milder assumptions and in neat forms

on fuzzy implication in de morgan algebras the behaviour of some fuzzy implications with respect to measure of fuzziness and their deductive power is studied in a lattice framework the point of view of bandler and kohout 1 and willmott 7 is followed

convergence of a nonconforming multiscale finite element method the multiscale finite element method msfem t y hou x h wu and z cai math comp 1998 to appear t y hou and x h wu j comput phys 134 1997 pp 169 189 has been introduced to capture the large scale solutions of elliptic equations with highly oscillatory coefficients this is accomplished by constructing the multiscale base functions from the local solutions of the elliptic operator our previous study reveals that the leading order error in this approach is caused by the resonant sampling which leads to large error when the mesh size is close to the small scale of the continuous problem similar difficulty also arises in numerical upscaling methods an oversampling technique has been introduced to alleviate this difficulty t y hou and x h wu j comput phys 134 1997 pp 169 189 a consequence of the oversampling method is that the resulting finite element method is no longer conforming here we give a detailed analysis of the nonconforming error our analysis also reveals a new cell resonance error which is caused by the mismatch between the mesh size and the wavelength of the small scale we show that the cell resonance error is of lower order our numerical experiments demonstrate that the cell resonance error is generically small and is difficult to observe in practice

an error analysis for the finite element method applied to convection diffusion problems abstract this paper analyzes the finite element method applied to a convection diffusion model problem linear elements are used for the trial space the error is measured in a norm closely related to the l sup p norm when the test space is composed of linear elements with parabolic upwinding the method is shown to be optimal when the input data is piecewise smooth a condition which is usually observed in practice without these smoothness assumptions the method is shown to be non optimal even if the class of test spaces is extended to include any elements which have a shape independent of the mesh size author

generalized multiscale finite element methods gmsfem in this paper we propose a general approach called generalized multiscale finite element method gmsfem for performing multiscale simulations for problems without scale separation over a complex input space as in multiscale finite element methods msfems the main idea of the proposed approach is to construct a small dimensional local solution space that can be used to generate an efficient and accurate approximation to the multiscale solution with a potentially high dimensional input parameter space in the proposed approach we present a general procedure to construct the offline space that is used for a systematic enrichment of the coarse solution space in the online stage the enrichment in the online stage is performed based on a spectral decomposition of the offline space in the online stage for any input parameter a multiscale space is constructed to solve the global problem on a coarse grid the online space is constructed via a spectral decomposition of the offline space and by choosing the eigenvectors corresponding to the largest eigenvalues the computational saving is due to the fact that the construction of the online multiscale space for any input parameter is fast and this space can be re used for solving the forward problem with any forcing and boundary condition compared with the other approaches where global snapshots are used the local approach that we present in this paper allows us to eliminate unnecessary degrees of freedom on a coarse grid level we present various examples in the paper and some numerical results to demonstrate the effectiveness of our method

nonfragile distributed filtering for t s fuzzy systems in sensor networks this paper is concerned with the nonfragile distributed h infty filtering problem for a class of discrete time takagi sugeno t s systems in sensor networks additive filter gain uncertainties that reflect imprecision in filter implementation are considered based on the robust control approach sufficient conditions are obtained to ensure that the filtering error system is asymptotically stable with a prescribed h infty performance level and the eigenvalues of the filtering error system in a given circular region the filter parameters are determined by solving a set of linear matrix inequalities a simulation study on the nonlinear tunnel diode circuit system is presented to show the effectiveness of the proposed design method

dissipativity based sampled data control for fuzzy switched markovian jump systems in this paper the dissipativity based sampled data control problem is studied for fuzzy switched markovian jump systems fsmjs by considering the problem of the asynchronous switching caused by the subsystems switching occurred during the sampling intervals constructing novel time dependent lyapunov functional and using average dwell time adt approach sufficient mean square exponential stability criteria and strictly mathcal q s r gamma dissipativity criteria are proposed under the constraints on that the maximum sampling period is no larger than the dwell time between the transition rates switching instants meanwhile a relationship between adt and sampling period is revealed for fsmjs based on the strictly mathcal q s r gamma dissipativity criteria the sampled data controller is designed for fsmjss a circuit simulation example is provided to illustrate the effectiveness of the proposed method

dynamic output feedback dissipative control for t s fuzzy systems with time varying input delay and output constraints this paper develops a new fuzzy dynamic output feedback control scheme for takagi sugeno t s fuzzy systems with time varying input delay and output constraints based on q s r alpha dissipativity the proposed controller called a q s r alpha dissipative output feedback fuzzy controller takes into consideration the abstract energy storage function and supply rate for the disturbance attenuation and provides a unified framework that can incorporate existing results for mathcal h infty and passivity controllers as special cases for t s fuzzy systems with time varying input delay and output constraints a dynamic parallel distributed compensator is used to design the q s r alpha dissipative output feedback fuzzy controller to ensure the asymptotic stability and strict q s r alpha dissipativity of closed loop systems described by a t s fuzzy model that satisfies some output constraints by employing the reciprocally convex approach a new set of delay dependent conditions for the desired controller is formulated in terms of the linear matrix inequality the effectiveness and the applicability of the proposed design techniques are validated by an example of control for active suspension systems for different road conditions

technical communique stabilization for takagi sugeno fuzzy systems based on partitioning the range of fuzzy weights in this note the state feedback stabilization for continuous time takagi sugeno t s fuzzy systems is addressed where the fuzzy weighting functions are assumed to be differentiable and their ranges of variation are possibly bounded by some parameters by utilizing the matrix elimination lemma and introducing a polyhedral partition to the range of the fuzzy weights the quadratically parameterized condition is transformed to being piecewise linear in both the fuzzy weights and their derivatives then a switching control based on the partition is considered by utilizing the extreme points in each partition to address the constraints of the fuzzy weights and their derivatives the simulation shows that finer subdivision in the partition leads to better stability and stabilization margins

on the implication operator in fuzzy logic abstract we investigate the different possible ways of translating an implication proposition in approximate reasoning we study a general class of these operators

first order corrections to the homogenized eigenvalues of a periodic composite medium this paper studies the eigenvalue problem associated with the vibration of a com posite medium assumed to have a periodic microstructure the investigation concentrates on the first order correction to the homogenized eigenvalues a major difficulty arises due to the interaction of the periodic microstructure with the boundary of the medium the way in which the boundary intersects the underlying periodic structure strongly influences the value of the correction a rigorous derivation is given of the eigenvalue correction formula the properties of the eigenvalue correction are studied in one and two dimensional numerical calculations

generalized finite element methods their performance and their relation to mixed methods the notion of a generalized finite element method is introduced this class of methods is analyzed and their relation to mixed methods is discussed the class of generalized finite element methods offers a wide variety of computational procedures from which particular procedures can be selected for particular problems a particular generalized finite element method which is very effective for problems with rough coefficients is discussed in detail

taking into account period variations and actuators saturation in sampled data systems this paper deals with the problem of stability and stabilization of sampled data systems under asynchronous samplings and actuators saturation the method is based on the first hand on the use of a novel class of lyapunov functionals whose derivative is negative along the trajectories of the continuous time model of the sampled data system it is shown that this fact guarantees that a quadratic lyapunov function is strictly decreasing for the discrete time asynchronous system on the other side the control saturation is taken into account from the use of a modified sector condition these ingredients lead to the formulation of improved lmi conditions that can be cast in optimization problems aiming at enlarging estimates of the region of attraction of the closed loop system or maximizing the bounds on the sampling period jitter for which stability and stabilization are ensured

a modeling of search oriented thesaurus use based on multivalued logical inference abstract the recovery of incomplete information in an uncontrolled vocabulary system by the use of a search oriented thesaurus is formulated on the basis of multivalued logical inference the method consists of two parts to obtain several inference results for a given pair of a document and a keyword and to aggregate them by material implication as well as possibility implication newly introduced significantly the latter leads to less influence of meaningless evidence than the former

periodic homogenization of green and neumann functions for a family of second order elliptic operators with rapidly oscillating periodic coefficients we study the asymptotic behavior of the green and neumann functions using dirichlet and neumann correctors as a result we obtain asymptotic expansions of poisson kernels and the dirichlet to neumann maps as well as optimal convergence rates in lp and w1 p for solutions with dirichlet or neumann boundary conditions 2014 wiley periodicals inc

a local regularization operator for triangular and quadrilateral finite elements this paper develops a local regularization operator on triangular or quadrilateral finite elements built on structured or unstructured meshes this operator is a variant of the regularization operator of clement however ours is constructed via a local projection in a reference domain we prove in this paper that it has the same optimal approximation properties as the standard interpolation operator and we present some applications

dissipativity based sampled data fuzzy control design and its application to truck trailer system this paper is concerned with the problem of dissipative control for takagi sugeno fuzzy systems under time varying sampling with a known upper bound on the sampling intervals based on the time dependent lyapunov krasovskii functional approach which makes full use of the available information about the actual sampling pattern a sufficient condition is established to guarantee the sampled data systems to be exponentially stable and strictly mathcal q mathcal s mathcal r gamma dissipative based on the criterion a design algorithm for the desired sampled data controller is proposed the effectiveness and benefits of the results developed in this paper is demonstrated by a controller design for a truck trailer system

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