stability analysis and synthesis of nonlinear time delay systems via linear takagi sugeno fuzzy models abstract this paper concerns with the stability analysis and synthesis of nonlinear retarded systems via linear takagi sugeno ts fuzzy model approach first the ts fuzzy models with time delay are present and the stability conditions are derived using lyapunov razumikhin functional approach then a stabilization approach for nonlinear retarded systems through fuzzy state feedback and fuzzy observer based controller is proposed it shows that the analysis results provide an efficient technique for the design of fuzzy controllers sufficient conditions for the existence of fuzzy state feedback gain and fuzzy observer gain of the time delay systems are derived through the numerical solution of a set of coupled linear matrix inequalities

non fragile h filtering for delayed takagisugeno fuzzy systems with randomly occurring gain variations in this study we consider a non fragile h filter design for a class of continuous time delayed takagisugeno ts fuzzy systems the filter design is assumed to include randomly occurring gain variations according to the filter s implementation two independent bernoulli distributions are employed to describe these random phenomena we focus mainly on the design of a non fragile filter so the filtering error system is asymptotically mean square stable with the prescribed h performance in the presence of both randomly occurring gain variations and a time delay a sufficient condition is developed by employing the lyapunov functional approach based on this condition an improved h filter for delayed ts fuzzy system is described which is free of randomly occurring gain variations the filter parameters are obtained by solving a set of linear matrix inequalities the effectiveness and the advantages of the proposed techniques are demonstrated by two numerical examples

high lift aerodynamic computations with one and two equation turbulence models the spalart allmaras one equation turbulence model and the menter two equation turbulence model are assessed for navier stokes computations of high lift aerodynamic flows including cases with significant regions of separated flow cases considered include 1 separated flow over a single element airfoil at high lift 2 fully attached flows over the nlr 7301 airfoil and flap and 3 separated flow over the ga w 1 airfoil and flap for the single element case the menter model provides better agreement with the experimental pressure distribution and velocity profiles for the nlr 7301 airfoil and flap both turbulence models provide excellent agreement with experimental pressures and skin friction data velocity profiles are generally well predicted except in some parts of wakes turbulent shear stresses are not always well predicted the predictions of the spalart allmaras model are generally superior for this case especially when boundary layer confluence is important

reduced order generalized h_ infty filtering for linear discrete time systems with application to channel equalization this paper investigates the problem of reduced order generalized h infty filtering for linear discrete time systems generalized h infty filtering covers standard h infty filtering as a special case and can make use of the frequency domain characteristics of practical signals moreover reduced order filters are more attractive than full order ones regarding implementability by virtue of the generalized bounded real lemma a new necessary and sufficient condition is proposed for analyzing the generalized h infty performance of the filtering error system to compute reduced order generalized h infty filters a necessary and sufficient condition is then derived in terms of matrix inequalities to solve which iterative linear matrix inequality algorithms are further developed in addition the proposed filter design method is applied to cope with the channel equalization problem examples are finally presented for illustrating the proposed method

delay dependent decentralized h_ infty filtering for discrete time nonlinear interconnected systems with time varying delay based on the t s fuzzy model this paper is concerned with the problem of delay dependent h filter design for a class of discrete time nonlinear interconnected system with time varying delays via the takagi sugeno t s fuzzy model the t s fuzzy model consists of n time delay t s fuzzy subsystems and a decentralized h filter is designed for each subsystem based on the delay dependent piecewise lyapunov krasovskii functional ddplkf and with an improved free weighting matrix technique the delay dependent stability and a prescribed h performance index are guaranteed for the overall filtering error system a sufficient condition for the existence of such a filter is established by using linear matrix inequalities lmis that are numerically feasible two numerical examples are given to demonstrate the effectiveness and advantage of the proposed approach

on the possible multiplicities of the eigenvalues of a hermitian matrix whose graph is a tree we consider the general problem of determining which lists of multiplicities for the eigenvalues occur among hermitian matrices the graph of whose off diagonal entries is a given tree several restrictions are cited and a construction strategy is given together these are sufficient to characterize all lists for each tree in two infinite classes the double paths and generalized stars and to tabulate all lists for trees on fewer than nine vertices such tables should be useful for formulating and dispelling general conjectures

new results on h_ infty filter design for nonlinear systems with time delay via t s fuzzy models this paper focuses on the problem of designing h filters for nonlinear systems with time varying delay via takagi sugeno t s fuzzy models some new results on h filter design are proposed by estimating the upper bounds of the derivatives of lyapunov functionals without ignoring some useful terms which improve the existing ones in addition a sufficient condition for the existence of such an h filter is established in terms of solutions to a set of linear matrix inequalities lmis finally two examples are given to demonstrate the effectiveness of the proposed method

nonfragile h_ infty filtering of continuous time fuzzy systems this paper is concerned with the problem of nonfragile h filtering for a class of continuous time fuzzy systems attention is focused on the design of a filter such that the filtering error system preserves a prescribed h performance where the filter to be designed is assumed to have gain variations by using the quadratic lyapunov function approach and adding slack matrix variables sufficient conditions for designing the nonfragile h filter are proposed in terms of solutions to a set of linear matrix inequalities lmis finally a simulation example will be given to show the efficiency of the proposed design methods

robust filtering under stochastic parametric uncertainties this paper is concerned with a polynomial approach to robust deconvolution filtering of linear discrete time systems with random modeling uncertainties the modeling errors appear in the coefficients of the numerators and denominators of both the input signal and system transfer function models in the form of random variables with zero means and known upper bounds of the covariances the robust filtering problem is to find an estimator that minimizes the maximum mean square estimation error over the random parameter uncertainties and input and measurement noises the key to our solution is to quantify the effect of the random parameter uncertainties by introducing two fictitious noises for which a simple way is given to calculate their covariances the optimal robust estimator is then computed by solving one spectral factorization and one polynomial equation as in the standard optimal estimator design using a polynomial approach an example of signal detection in mobile communication is given to illustrate the effectiveness of our approach

stability of fuzzy control systems with bounded uncertain delays global exponential stability of fuzzy control systems with delays is studied these delays in the fuzzy control systems are assumed to be any uncertain bounded continuous functions stability of systems with uncertain delays is interesting since in practical applications it is not easy to know the delays exactly conditions for global exponential stability of free fuzzy systems with uncertain delays are derived criteria for design of nonlinear fuzzy controllers to feedback control the stability of global nonlinear fuzzy systems are given theorems are proved via the method of functional differential inequalities analysis

robust kalman filtering for discrete time varying uncertain systems with multiplicative noises in this paper a robust finite horizon kalman filter is designed for discrete time varying uncertain systems with both additive and multiplicative noises the system under consideration is subject to both deterministic and stochastic uncertainties sufficient conditions for the filter to guarantee an optimized upper bound on the state estimation error variance for admissible uncertainties are established in terms of two discrete riccati difference equations a numerical example is given to show the applicability of the presented 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

output feedback robust h sup spl infin control of uncertain fuzzy dynamic systems with time varying delay this paper presents an output feedback robust h sup spl infin control problem for a class of uncertain fuzzy dynamic systems with time varying delayed state the takagi sugeno fuzzy model is employed to represent an uncertain nonlinear systems with time varying delayed state using a single quadratic lyapunov function the globally exponential stability and disturbance attenuation of the closed loop fuzzy control system are discussed sufficient conditions for the existence of robust h sup spl infin controllers are given in terms of matrix inequalities constructive algorithm for design of robust h sup spl infin controller is also developed the resulting controller is nonlinear and automatically tuned based on fuzzy operation

new results on h_ infty tracking control based on the t s fuzzy model for sampled data networked control system this study deals with the problem of h infty tracking control for a sampled data networked control system based on a takagi sugeno fuzzy model an error model is established by combining the input delay and parallel distributed compensation techniques so as to transform the sampling period of a sampler a signal transmission delay and data packet dropouts to the refreshing interval of a zero order hold the method introduces a new augmented lyapunov krasovskii functional to derive a sufficient condition to ensure a prescribed h infty tracking performance with less conservativeness than others a fuzzy controller can easily be designed using the condition a numerical example demonstrates the validity of the method

fuzzy affine model based memory filter design of nonlinear systems with time varying delay this paper studies the piecewise affine memory mathscr h infty filtering problem for nonlinear systems with time varying delay in a delay dependent framework the nonlinear plant is characterized by a continuous time takagi sugeno fuzzy affine model with parametric uncertainties the purpose is to develop a new approach for filter synthesis procedure with less conservatism specifically by constructing a novel lyapunov krasovskii functional together with a wirtinger based integral inequality reciprocally convex inequality and s procedure an improved criterion is first attained for analyzing the mathscr h infty performance of the filtering error system and then via some linearization techniques the piecewise affine memory filter synthesis is carried out it is shown that the existence of desired filter gains can be explicitly determined by the solution of a convex optimization problem finally simulation studies are presented to reveal the effectiveness and less conservatism of the developed approaches it is anticipated that the proposed scheme can be further extended to the analysis and synthesis of continuous time fuzzy affine dynamic systems with integrated communication delays in the networked circumstance

high order linear and non linear residual distribution schemes for turbulent compressible flows a high order residual distribution scheme for the solution of the compressible rans equations is developed the one equation spalart allmaras turbulence model is solved in a fully coupled approach the mean flow equations as well as the turbulence equation are solved with high order of accuracy a continuous approximation of the solution is adopted and standard lagrangian basis functions are used to construct the discrete space since viscous terms involve the gradient of the numerical solution which has a discontinuous normal component across the faces of the elements a continuous approximation of the gradient of the numerical solution is recovered at each degree of freedom of the grid and then interpolated with the same basis functions used for the solution the non linear system of equations resulting from the numerical discretization is solved with the non linear lu sgs method several numerical experiments are performed to verify the accuracy of the numerical method these are based on both subsonic and transonic flows in two and three spatial dimensions

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

prediction of nonequilibrium turbulent flows with explicit algebraic stress models an explicit algebraic stress equation developed by gatski and speziale is used in the framework of the k uj and k e formulations to predict two dimensional separated turbulent flows the nonequilibrium effects are modeled through coefficients that depend nonlinearly on both rotational and irrotational strains the proposed models were implemented in the courant friedrichs lewy three dimensional navier stokes code comparisons with the experimental data are presented which clearly demonstrate that explicit algebraic stress models improve the response of standard two equation models to nonequilibrium effects i introduction

active flow separation control on wall mounted hump at high reynolds numbers an active separation control experiment was conducted in a cryogenic pressurized wind tunnel on a wall mounted bump at chord reynolds numbers from 2 4 x 10 6 to 26 x 106 and a mach number of 0 25 the model simulates the upper surface of a 20 thick glauert goldschmied type airfoil at zero incidence the turbulent boundary layer of the tunnel sidewall flows over the model and eliminates laminar turbulent transition from the problem indeed the reynolds number either based on the chord or boundary layer thickness had a negligible effect on the flow and its control without control a large turbulent separation bubble is formed at the lee side of the model periodic excitation and steady suction or blowing were applied to eliminate gradually the separation bubble detailed effects due to variations in the excitation frequency amplitude and the steady mass flux are described and compared to those of steady suction or blowing

delay dependent guaranteed cost control for t s fuzzy systems with time delays this study introduces a guaranteed cost control method for nonlinear systems with time delays which can be represented by takagi sugeno t s fuzzy models with time delays the state feedback and generalized dynamic output feedback approaches are considered the generalized dynamic output feedback controller is presented by a new fuzzy controller architecture which is of dual indexed rule base it considers both the dynamic part and the output part of t s fuzzy model which guarantees that the controller without any delay information can stabilize time delay t s fuzzy systems based on delay dependent lyapunov functional approach some sufficient conditions for the existence of state feedback controller are provided via parallel distributed compensation pdc first second the corresponding conditions are extended into the generalized dynamic output feedback closed loop system via so called generalized pdc technique the upper bound of time delay can be obtained using convex optimization such that the system can be stabilized for all time delays whose sizes are not larger than the bound the minimizing method is also proposed to search the suboptimal upper bound of guaranteed cost function the effectiveness of the proposed method can be shown by the simulation examples

compressible linear stability of confluent wake boundary layers the linear stability of a compressible confluent wake boundary layer is studied the base flow model considered is the superposition of a compressible boundary layer and a gaussian like wake located above the boundary layer the linear stability equations have been solved by using a global numerical method the stability modes of interest have been identified as the boundary layer modes the antisymmetric wake mode and the symmetric wake mode the effects of wake height on the first tollmien shlichting mode and the second mode associated with the boundary layer are discussed results for unstable modes associated with the wake are also presented

on the relative position of multiple eigenvalues in the spectrum of an hermitian matrix with a given graph for hermitian matrices whose graph is a given tree the relationships among vertex degrees multiple eigenvalues and the relative position of the underlying eigenvalue in the ordered spectrum are discussed in detail in the process certain aspects of special vertices whose removal results in an increase in multiplicity are investigated

a near optimal multiuser detector for ds cdma systems using semidefinite programming relaxation a multiuser detector for direct sequence code division multiple access systems based on semidefinite programming sdp is proposed it is shown that maximum likelihood ml detection can be carried out by relaxing the associated integer programming problem to a dual sdp problem which leads to a detector of polynomial complexity computer simulations that demonstrate that the proposed detector offers near optimal performance with considerably reduced computational complexity compared with that of existing primal sdp relaxation based detectors are presented

fuzzy filter design for nonlinear systems in finite frequency domain this paper is concerned with the problem of fuzzy filter design for discrete time nonlinear systems in the takagi sugeno t s form different from existing fuzzy filters the proposed ones are designed in finite frequency domain first a so called finite frequency l2 gain is defined that extends the standard l2 gain then a sufficient condition for the filtering error system with a finite frequency l2 gain is derived based on the obtained condition three fuzzy filters are designed to deal with noises in the low middle and high frequency domain respectively the proposed fuzzy filtering method can get a better noise attenuation performance when frequency ranges of noises are known beforehand an example about a tunnel diode circuit is given to illustrate its effectiveness

stabilization and separation principle of networked control systems using the t s fuzzy model approach this paper is concerned with the stabilization problem for a class of discrete time networked control systems ncss with bounded time delays and packet losses the controlled plant is represented by a takagi sugeno fuzzy model and both the state feedback control and output feedback control cases are considered by guaranteeing the decrement of lyapunov functional at each control signal updating step a less conservative stability condition for the state feedback ncss is derived and the corresponding stabilizing controller design method is also presented under an observer based framework the output feedback stabilization problem is further studied where the main contribution is the development of the separation principle for ncss illustrative examples are provided to show the advantage and effectiveness of the developed results

h_ bm infty fuzzy filtering of nonlinear systems with intermittent measurements this paper is concerned with the problem of h infin fuzzy filtering of nonlinear systems with intermittent measurements the nonlinear plant is represented by a takagi sugeno t s fuzzy model the measurements transmission from the plant to the filter is assumed to be imperfect and a stochastic variable satisfying the bernoulli random binary distribution is utilized to model the phenomenon of the missing measurements attention is focused on the design of an h infin filter such that the filter error system is stochastically stable and preserves a guaranteed h infin performance a basis dependent lyapunov function approach is developed to design the h infin filter by introducing some slack matrix variables the coupling between the lyapunov matrix and the system matrices is eliminated which greatly facilitates the filter design procedure the developed theoretical results are in the form of linear matrix inequalities lmis finally an illustrative example is provided to show the effectiveness of the proposed approach

prediction of high lift flows using turbulent closure models the flow over two different multi element airfoil configurations is computed using linear eddy viscosity turbulence models and a nonlinear explicit algebraic stress model a subset of recently measured transition locations using hot film on a mcdonnell douglas configuration is presented and the effect of transition location on the computed solutions is explored deficiencies in wake profile computations are found to be attributable in large part to poor boundary layer prediction on the generating element and not necessarily inadequate turbulence modeling in the wake using measured transition locations for the main element improves the prediction of its boundary layer thickness skin friction and wake profile shape however using measured transition locations on the slat still yields poor slat wake predictions the computation of the slat flow field represents a key roadblock to successful predictions of multi element flows in general the nonlinear explicit algebraic stress turbulence model gives very similar results to the linear eddy viscosity models

the change in multiplicity of an eigenvalue due to adding or removing edges abstract we investigate the change in the multiplicities of the eigenvalues of a hermitian matrix with a simple graph g when edges are inserted into g or removed from g we focus upon cases in which the multiplicity of the eigenvalue does not change due to inserting or removing edges incident to a vertex furthermore we show how the change in the multiplicities of the eigenvalues occur when two disjoint graphs are connected with one edge based upon the status of the vertices that are connected lastly we give the possible classifications of cut edges in a graph and characterize the occurrence of each possible status

spectral multiplicity and splitting results for a class of qualitative matrices abstract this paper presents some results concerning the location and multiplicity of eigenvalues of sign symmetric matrices whose associated graphs are trees in particular it extends previous spectral multiplicity and splitting results proved by others

robustness design of nonlinear dynamic systems via fuzzy linear control this study introduces a fuzzy linear control design method for nonlinear systems with optimal h sup spl infin robustness performance first the takagi and sugeno fuzzy linear model 1985 is employed to approximate a nonlinear system next based on the fuzzy linear model a fuzzy controller is developed to stabilize the nonlinear system and at the same time the effect of external disturbance on control performance is attenuated to a minimum level thus based on the fuzzy linear model h sup spl infin performance design can be achieved in nonlinear control systems in the proposed fuzzy linear control method the fuzzy linear model provides rough control to approximate the nonlinear control system while the h sup spl infin scheme provides precise control to achieve the optimal robustness performance linear matrix inequality lmi techniques are employed to solve this robust fuzzy control problem in the case that state variables are unavailable a fuzzy observer based h sup spl infin control is also proposed to achieve a robust optimization design for nonlinear systems a simulation example is given to illustrate the performance of the proposed design method

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

nonsynchronized state estimation of multichannel networked nonlinear systems with multiple packet dropouts via t s fuzzy affine dynamic models this paper investigates the problem of robust h state estimation for a class of multichannel networked nonlinear systems with multiple packet dropouts the nonlinear plant is represented by takagi sugeno t s fuzzy affine dynamic models with norm bounded uncertainties and stochastic variables with general probability distributions are adopted to characterize the data missing phenomenon in output channels the objective is to design an admissible state estimator guaranteeing the stochastic stability of the resulting estimation error system with a prescribed h disturbance attenuation level it is assumed that the plant premise variables which are often the state variables or their functions are not measurable so that the estimator implementation with state space partition may not be synchronized with the state trajectories of the plant based on a piecewise quadratic lyapunov function combined with s procedure and some matrix inequality convexifying techniques two different approaches are developed to robust filtering design for the underlying t s fuzzy affine systems with unreliable communication links all the solutions to the problem are formulated in the form of linear matrix inequalities lmis finally simulation examples are provided to illustrate the effectiveness of the proposed approaches

robust h control for nonlinear systems over network a piecewise analysis method a piecewise analysis method pam is proposed to investigate the h performance analysis and h control design for nonlinear networked control systems nncss which are presented in the form of t s fuzzy model with time varying input delay different from the existing method in dealing with the time varying delay the whole variation interval of the delay is divided into two subintervals with equal length respecting for the delay belonging each subinterval new criteria on h performance analysis of the nncss are obtained by checking the variation of the derivative of the lyapunov functional in the two subintervals then criteria for the h controller design are obtained by using the convexity properties of the matrix inequality and some other new analysis techniques which are shown in terms of nonlinear matrix inequalities and can be solved by using a cone complementarity liberalization method as application of the derived results h controller design is carried out for the nonlinear mass spring system discussion shows that the proposed method is less conservative than the existing references

stabilization of uncertain fuzzy time delay systems via variable structure control approach in view of a recent new application of variable structure control vsc to the stabilization problem for takagi sugeno t s fuzzy models this paper aims to study the stabilization of uncertain fuzzy time delay systems in t s fuzzy model via vsc approach there are mainly two features in this paper one lies in the incorporation of time delays both smooth and nonsmooth delays in which case lyapunov functionals and razumikhin theorem are required to solve the stabilization problem the other feature is that not only matched uncertainties but also mismatched uncertainties in the state variables are considered as a sequence the contribution of this paper consists of various control schemes proposed for the vsc design and the present results are in terms of linear matrix inequalities lmis an illustrative example is given to show the effectiveness of our various results

navier stokes computations of vortical flows over low aspect ratio wings an upwind biased finite volume algorithm is applied to the low speed laminar flow over a low aspect ratio delta wing from 0 to 40 deg angle of attack the differencing is second order accurate spatially and a multigrid algorithm is used to promote convergence to the steady state the results compare well with the detailed experiments of hummel and others for an ret of 0 95 x 106 the predicted maximum lift coefficient of 1 10 at 35 deg angle of attack agrees closely with the measured maximum lift of 1 06 at 33 deg at 40 deg angle of attack a bubble type of vortex breakdown is evident in the computations extending from 0 6 of the root chord to just downstream of the trailing edge

turbulence model predictions of strongly curved flow in a u duct the ability of three types of turbulence models to accurately predict the effects of curvature on the flow in a u duct is studied an explicit algebraic stress model performs slightly better than one or two equation linear eddy viscosity models although it is necessary to fully account for the variation of the production to dissipation rate ratio in the algebraic stress model formulation in their original formulations none of these turbulence models fully captures the suppressed turbulence near the convex wall whereas a full reynolds stress model does some of the underlying assumptions used in the development of algebraic stress models are investigated and compared with the computed flowfield from the full reynolds stress model through this analysis the assumption of reynolds stress anisotropy equilibrium used in the algebraic stress model formulation is found to be incorrect in regions of strong curvature by the accounting for the local variation of the principal axes of the strain rate tensor the explicit algebraic stress model correctly predicts the suppressed turbulence in the outer part of the boundary layer near the convex wall

analysis and synthesis of nonlinear time delay systems via fuzzy control approach takagi sugeno ts fuzzy models 1985 1992 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 i o submodels in this paper the ts fuzzy model approach is extended to the stability analysis and control design for both continuous and discrete time nonlinear systems with time delay the ts fuzzy models with time delay are presented and the stability conditions are derived using lyapunov krasovskii approach we also present a stabilization approach for nonlinear time delay systems through fuzzy state feedback and fuzzy observer based controller sufficient conditions for the existence of fuzzy state feedback gain and fuzzy observer gain are derived through the numerical solution of a set of coupled linear matrix inequalities an illustrative example based on the cstr model is given to design a fuzzy controller

a multiple lyapunov function approach to stabilization of fuzzy control systems this paper addresses stability analysis and stabilization for takagi sugeno fuzzy systems via a so called fuzzy lyapunov function which is a multiple lyapunov function the fuzzy lyapunov function is defined by fuzzily blending quadratic lyapunov functions based on the fuzzy lyapunov function approach we give stability conditions for open loop fuzzy systems and stabilization conditions for closed loop fuzzy systems to take full advantage of a fuzzy lyapunov function we propose a new parallel distributed compensation pdc scheme that feedbacks the time derivatives of premise membership functions the new pdc contains the ordinary pdc as a special case a design example illustrates the utility of the fuzzy lyapunov function approach and the new pdc stabilization method

fuzzy weighting dependent approach to h_ infty filter design for time delay fuzzy systems this correspondence is concerned with the hinfin filter design for takagi sugeno t s fuzzy systems with state delay a delay dependent design method is proposed in terms of linear matrix inequalities lmi the main contribution is the use of fuzzy weighting dependent lyapunov functionals which can reduce the conservatism arisen from the quadratic lyapunov functional approach an illustrative example is given to show the effectiveness of the present method

delay dependent robust h sub spl infin control for t s fuzzy systems with time delay this paper focuses on the problem of delay dependent robust fuzzy control for a class of nonlinear delay systems via state feedback the takagi sugeno t s fuzzy model is adopted for representing a nonlinear system with time delayed state a delay dependent stabilization criterion is first presented then the methods of robust stabilization and robust h sub spl infin control are developed which are dependent on the size of the delay and are based on the solutions of linear matrix inequalities lmis finally a design example of robust h sub spl infin controller for uncertain nonlinear systems is given to illustrate the effectiveness of the approaches proposed in this paper

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

a multigrid overset grid flow solver with implicit hole cutting method in the computation of flow over complex configurations the use of overset grids eases the grid generation process but the non trivial task of ensuring communication between the overlapping grids must first be established this need is efficiently addressed by using a new practically useful implicit hole cutting ihc method introduced by lee and baeder this approach is a cell selection process based on the main criterion of cell size and all grid points including hole interior points and hole fringe points are treated indiscriminately in the flow computation potentially these features ease the implementation of the multigrid algorithms which are rarely used in overset methods the present study addresses the use of ihc method as an inter grid communication method within a hybrid multi block framework amenable for the implementation of a multigrid method and parallel computation the convergence accuracy and efficiency of the current solver are assessed particularly for the large scale computations of realistic aerodynamic configurations

the structure of matrices with a maximum multiplicity eigenvalue there is remarkable and distinctive structure among hermitian matrices whose graph is a given tree t and that have an eigenvalue of multiplicity that is a maximum for t among such structure we give several new results 1 no vertex of t may be neutral 2 neutral vertices may occur if the largest multiplicity is less than the maximum 3 every parter vertex has at least two downer branches 4 removal of a parter vertex changes the status of no other vertex and 5 every set of parter vertices forms a parter set statements 3 4 and 5 are also not generally true when the multiplicity is less than the maximum some of our results are used to give further insights into prior results and both the review of necessary background and the development of new structural lemmas may be of independent interest

non fragile h filter design for discrete time fuzzy systems with multiplicative gain variations this paper investigates the problem of non fragile h filter design for discrete time takagi sugeno t s fuzzy systems the filter to be designed is assumed to have two type of multiplicative gain variations by introducing additional matrix variables a relaxed h filtering analysis criterion is presented for the fuzzy system based on the fuzzy lyapunov function a filter state transformation approach is adopted to design the non fragile h filter and the filter gains are given in terms of the feasible solutions of a set of linear matrix inequalities lmis a simulation example is given to show the efficiency of the proposed methods

robust nonfragile h_ infty filtering of fuzzy systems with linear fractional parametric uncertainties this paper is concerned with the h filtering problem for continuous time takagi sugeno t s fuzzy systems different from existing results for fuzzy h filtering the proposed ones are toward uncertain fuzzy systems with linear fractional parametric uncertainties attention is focused on the design of a fuzzy filter such that the filtering error system preserves a prescribed h performance where the filter to be designed is assumed to have gain variations by a descriptor representation approach two sufficient conditions for the h filter design are proposed in terms of linear matrix inequalities lmis when these lmis are feasible an explicit expression of the desired filter is given a simulation example will be given to show the efficiency of the proposed methods

h_ infty filter design for nonlinear systems with time delay through t s fuzzy model approach this paper is concerned with the hinfin filter design for nonlinear systems with time varying delay via takagi sugeno fuzzy model approach delay dependent design method is proposed in terms of linear matrix inequalities lmis which forms the main contribution of this paper the main technique used is the free weighting matrix method combined with a matrix decoupling approach the results for rate independent case delay independent case and delay free case are also given as easy corollaries an illustrative example is given to show the effectiveness of the present method

zonal detached eddy simulation of the flow around a high lift configuration a zonal hybrid reynolds averaged navier stokes large eddy simulation rans les approach called zonal des used to handle a two dimensional high lift configuration with deployed slat and flap is presented this method allows to reduce significantly the cost of an accurate numerical prediction of the unsteady flow around wings compared to a complete les some issues concerning grid generation as well as the use of zonal detached eddy simulation for a multi element airfoil are discussed the basic planar grid has 250 000 points and the finest spanwise grid has 31 points with az c 0 002 the effort is geared toward detailed comparison of the numerical results with the europiv2 experimental particle image velocimetry data including both mean and fluctuating properties of the velocity field arnott and al

h sub spl infin fuzzy estimation for a class of nonlinear discrete time dynamic systems this paper studies h sub spl infin fuzzy filtering design for state estimation of nonlinear discrete time systems with bounded but unknown disturbances first the takagi and sugeno 1985 fuzzy model is proposed to represent a nonlinear system next using a linear matrix inequality lmi approach the h sub spl infin fuzzy filtering problems are characterized in terms of a linear matrix inequality problem lmip the lmip can be efficiently solved using convex optimization techniques simulation examples are given to illustrate the design procedure and the applicability of the proposed method the results indicate that the proposed method is suitable for practical applications

a new fuzzy h filter design for nonlinear continuous time dynamic systems with time varying delays this paper focuses on the problem of h filter design for nonlinear systems with time varying delays a new approach of filter design is proposed the proposed results may improve the existing ones due to estimate the upper bound of the derivative of lyapunov functional without ignoring some useful terms a sufficient condition for the existence of such a filter is established by using the linear matrix inequality lmi approach finally two examples are given to demonstrate the effectiveness and the benefits of the proposed method

robust h infinity filtering for a class of non linear systems with state delay and parameter uncertainty this paper deals with the problem of robust h infinity filtering for a class of state delayed non linear systems with normbounded parameter uncertainty appearing in all the matrices of the linear part of the system model the non linearities are assumed to satisfy the global lipschitz conditions and appear in both the state and measured output equations attention is focused on the design of a non linear filter which ensures both the robust stability and a prescribed h infinity performance of the filtering error dynamics for all admissible uncertainties a sufficient condition for the existence of such a filter is given in terms of a linear matrix inequality lmi when this lmi is feasible the expression of a desired h infinity filter is also presented a numerical example is provided to demonstrate the applicability of the proposed approach

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

decentralized h_ infty filter design for discrete time interconnected fuzzy systems this paper describes a decentralized h infin filter design for discrete time interconnected fuzzy systems based on piecewise quadratic lyapunov functions the systems consist of j discrete time interconnected takagi sugeno t s fuzzy subsystems and a decentralized h infin filter is designed for each subsystem it is shown that the stability of the overall filtering error system with h infin performance can be established if a piecewise quadratic lyapunov function can be constructed moreover the parameters of filters can be obtained by solving a set of linear matrix inequalities that are numerically feasible two simulation examples are given to show the effectiveness of the proposed approach