adaptive fuzzy output feedback control for switched nonstrict feedback nonlinear systems with input nonlinearities this paper studies adaptive fuzzy output feedback tracking control problem for nonstrict feedback switched nonlinear systems the switched systems under consideration contain unknown nonlinearities unmeasured states and unknown deadzones fuzzy logic systems are utilized to approximate the unknown nonlinearities and a switched fuzzy state observer is designed and thus the immeasurable states are estimated via it in the framework of observer based output feedback control and by using the certainty equivalence deadzone inverse a novel adaptive fuzzy output feedback control design method with the parameters adaptation laws is developed the stability of the closed loop system and the convergence of the tracking error are proved based on lyapunov function and the average dwell time methods two simulation examples are provided to check the effectiveness of the proposed approach

an optimal fault detection approach for piecewise affine systems via diagnostic observers abstract in this paper the design issues of diagnostic observer based fault detection fd for piecewise affine systems are investigated to be specific the diagnostic observer based fd approaches are developed to satisfy the specified disturbance attenuation and optimize the fault detectability at the same time considering the fact that the measurements are generally corrupted with noises or disturbances the proposed approaches are mainly dedicated to the case that the process and its fd system are non synchronous in transition from one region to another moreover aiming at improving the fd performance a mode observer is integrated to relax the design condition for the residual generator an example is given in the end to show the effectiveness of the proposed approaches

analyticity and differentiability of semigroups associated with elastic systems with damping and gyroscopic forces abstract in this paper we consider a second order variational evolution equation in a hilbert space which can model an elastic system with damping and gyroscopic forces a new form of the corresponding first order evolution equation is introduced and its well posedness is proved by means of the semigroup theory we give sufficient conditions for analyticity and differentiablity of the associated semigroup the results are applied to several pdes with discontinuous coefficients and mechanical boundary conditions it is proved that russell s spacial hysteresis model of a vibrating beam 22 is associated with an exponentially stable analytic semigroup

on the mathematical model for linear elastic systems with analytic damping in the present paper we investigate linear elastic systems with damping ddot y b dot y ay 0 in hilbert spaces where a is a positive definite unbounded linear operator and b is a closed linear operator related in various ways to a alpha frac 1 2 leqq alpha leqq 1 we discuss the spectral property of these systems and obtain some fundamental results for the holomorphic property and the exponential stability of the semigroups associated with these systems

galerkin approximation in modeling of controlled distributed parameter flexible systems abstract numerical study of control problems for linear distributed parameter flexible mechanical systems requires finite dimensional modeling of the system we study the conditions for h covergence of the transfer functions of finite dimensional galerkin approximations this convergence ensures that control problems can be solved by using a galerkin model a stabilization problem for the angular position of a bernoulli euler beam illustrates the theoretical consideration the beam with an inertial drive represents a flexible manipulator link

weighted pseudo almost periodic solutions of second order neutral delay differential equations with piecewise constant argument by introducing the method of decomposition of weighted pseudo almost periodic sequence we present some existence theorems of weighted pseudo almost periodic solutions for second order neutral differential equations with piecewise constant argument of the form d 2dt 2 x t px t 1 qx 2 t 12 f t where p 1 denotes the greatest integer function q is a nonzero constant and f t is weighted pseudo almost periodic our results are new and can be regarded as a complement of some known results even in the special cases of almost periodicity and pseudo almost periodicity

finite frequency memory output feedback controller design for t s fuzzy dynamical systems in this paper we will investigate the problem of finite frequency memory fixed order output feedback controller design for takagi sugeno t s fuzzy affine systems it is assumed that the disturbances reside in a finite frequency range i e the low middle or high frequency range the objective is to design a memory piecewise affine pwa controller by using past output measurements to guarantee the asymptotic stability of the resulting closed loop system with a prescribed finite frequency mathscr h infty performance via the system state input augmentation a novel descriptor system approach is proposed to facilitate the controller design all the design conditions are formulated in the form of linear matrix inequalities it is also proven that the mathscr h infty performance can be improved with the memory control strategy finally simulation studies are presented to show the effectiveness of the proposed design method

almost automorphic solutions of nonautonomous evolution equations abstract in this paper we establish some new theorems about the existence of almost automorphic solutions to nonautonomous evolution equations u t a t u t f t and u t a t u t f t u t in banach spaces as we will see our results allow for a more general a t to some extent an example is also given to illustrate our results in addition by means of an example we show that one cannot ensure the existence of almost automorphic solutions to u t a t u t f t even if the evolution family u t s generated by a t is exponentially stable and f a a x

relaxed stability and performance lmi conditions for takagi sugeno fuzzy systems with polynomial constraints on membership function shapes most linear matrix inequality lmi fuzzy control results in literature are valid for any membership function i e independent of the actual membership shape hence they are conservative with respect to other nonlinear control approaches when specific knowledge of the shapes is available this paper presents relaxed lmi conditions for fuzzy control that incorporate such shape information in the form of polynomial constraints generalizing previous works by the authors interesting particular cases are overlap product bounds and ellipsoidal regions numerical examples illustrate the achieved improvements as well as the possibilities of solving some multiobjective problems the results also apply to polynomial in membership takagi sugeno fuzzy systems

controllability of second order infinite dimensional systems in the paper the approximate controllability of linear abstract second order infinite dimensional dynamical systems is considered it is proved using the frequency domain method that approximate controllability of second order system can be verified by the approximate controllability conditions for the corresponding simplified first order system general results are then applied for approximate controllability investigation of a vibratory dynamical system modeling flexible mechanical structure some special cases are also considered moreover remarks and comments on the relationships between different concepts of controllability are given the paper extends earlier results on approximate controllability of second order abstract dynamical systems

stability analysis of partially loaded leipholz column carrying a lumped mass and resting on elastic foundation abstract in the present study the stability of a cantilever column resting on an elastic foundation under the action of a uniformly distributed tangential load is discussed a winkler type elastic foundation is considered moreover the effect of a lumped mass located in an arbitrary position on the stability of the system when the column is subjected to a partially distributed follower force is investigated the equations of motion are obtained using the extended hamilton s principle and the influences of the lumped mass and applied load are included in the equations using the generalized functions theories applying the ritz technique the resulting equations are transformed into a general eigenvalue problem the effects of several design parameters such as foundation elastic modulus ratio of the lumped mass to the column s mass position of the lumped mass and the distribution model of the follower force are examined the validity of the present analysis is confirmed by comparing the results with those obtained in literature and excellent agreement is observed the numerical results reveal that the load distribution length and model have significant effects on the flutter boundaries of the system

complete second order linear differential equations with almost periodic solutions abstract this paper characterizes equations of the type u t bu t au t 0 in a banach space where a b are densely defined closed linear operators and whose solutions are all almost periodic

entire solutions of higher order abstract cauchy problems abstract we consider the abstract cauchy problem for the higher order differential equation u n t i 0 n 1 a i u i t 0 t 0 u j 0 u j 0 j n 1 wherea0 an 1are closed linear operators in a complex banach spacee it is shown that if there exist 0 2 r 0 and a positive integerhsuch that nr and hakr 0 k n 1 are bounded in c arg e i 2 r wherer n n 1i 0 iai 1 then there exists a dense subsetgofensuch that for every initial value u0 un 1 g has a unique entire solution that is a solution which can be extended analytically to the whole complex plane as a corollary we get that the cauchy problems for the parabolic higher order linear differential equations have a unique entire solution for a dense set of initial data

the application of chebyshev polynomials to the solution of the nonprismatic timoshenko beam vibration problem abstract chebyshev series approximation is applied to solve the problem of vibration of the nonprismatic timoshenko beam resting on a two parameter elastic foundation as a result a system of equations whose coefficients have a closed form for calculating the coefficients of the sought solution is obtained the method is used to solve the free vibration problem for simple supported and clamped free nonprismatic beams the results are compared with the results obtained by other authors also the nonprismatic beam stability problem is solved and the results are compared with those obtained for euler beams to demonstrate the method s applicability to more complex systems the problem of stability of a frame system is solved

super exponential convergence of the karnik mendel algorithms for computing the centroid of an interval type 2 fuzzy set computing the centroid of an interval t2 fs is an important operation in a type 2 fuzzy logic system where it is called type reduction but it is also a potentially time consuming operation the karnik mendel km iterative algorithms are widely used for doing this in this paper we prove that these algorithms converge monotonically and super exponentially fast both properties are highly desirable for iterative algorithms and explain why in practice the km algorithms have been observed to converge very fast thereby making them very practical to use

non conservative instability of a timoshenko beam resting on winkler elastic foundation abstract the transfer matrix method is used to investigate the influence of a winkler elastic foundation on the non conservative instability of uniform timoshenko beams it is found that the critical flutter load for a cantilever timoshenko beam subjected to an end concentrated or linearly distributed tangential follower force will first decrease as the elastic foundation modulus is increased and as the elastic foundation modulus increases beyond the corresponding critical value which corresponds to the lowest critical flutter load it will increase instead it is also observed that when the elastic foundation modulus is large enough the critical flutter load for a cantilever timoshenko beam can be greater than that of a bernoulli euler beam and there exists a corresponding critical turning point for the critical flutter load at this critical turning point the instability mechanism changes the instability mechanisms for a beam subjected to end concentrated and linearly distributed tangential follower force are different

norm continuity fort 0 of propagators of arbitrary order abstract differential equations in hilbert spaces let acpn u n t n 1k 0aku k t 0 t 0 u k 0 uk 0 k n 1 be strongly wellposed where theak 0 k n 1 are densely defined closed linear operators in a hilbert space letsk t 0 k n 1 be the propagators of acpn andp ni n 1k 0 kak it is shown thats k k t 0 k n 1 is norm continuous fort 0 if and only if lim omega to infty left tau 0 i omega n 1 p tau 0 i omega 1 right 0 lim omega to infty left tau 0 i omega k 1 overline p tau 0 i omega 1 a k right 0 qquad 1 le k n le n 1 for a suitable real number 0

semigroups arising from elastic systems with dissipation abstract in this paper we investigate the properties norm continuity differentiability analyticity and exponential stability of semigroups arising from elastic systems with dissipation the resulting theorems are complete in a sense extensions of 1 theorem 1 1 and 2 theorem 1 1

existence results for some damped second order volterra integro differential equations abstract in this paper we make a subtle use of operator theory techniques and the well known schauder fixed point principle to establish the existence of pseudo almost automorphic solutions to some second order damped integro differential equations with pseudo almost automorphic coefficients in order to illustrate our main results we will study the existence of pseudo almost automorphic solutions to a structurally damped plate like boundary value problem

integrated semigroups and higher order abstract equations abstract let e be a banach space b 0 b n 1 closed linear operators on e and f 0 e this paper is devoted to the study of well posedness of the cauchy problem for higher order abstract differential equations formula using the theory of integrated semigroups we obtain some concise and useful criteria

numerical approach to the non linear diofantic equations with applications to the controllability of infinite dimensional dynamical systems the article is devoted to the analysis of the approximate controllability of a given type of second order infinite dimensional system defined by the hyperbolic type partial differential equation with dirichlet like type zero boundary conditions defined in the n dimensional rectangular prism following this aim spectral theory for linear unbounded operators is involved new numerical algorithms for solving some kind of non linear diofantic equations corresponding with the spectral properties of the unbounded operators are presented and proved an algorithm is optimized for eliminating the symmetrical solutions not interesting in the scope of verification of the controllability next the limit which shows that the direct application of the analytical methods of verifying the controllability in the numerical approach is impossible is proved finally so called partial approximate controllability is defined and the numerical algorithm for its verification is presented finally proven theorems are applied

a characterization of norm continuity of propagators for second order abstract differential equations abstract in this paper we obtain a concise characterization of norm continuity for t 0 of propagators for the complete second order abstract differential equation on a banach space e u t bu t au t 0 t 0 where b l e as a consequence we discover that a strongly continuous cosine operator function or operator group is norm continuous for t 0 if and only if its generator is bounded

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

characterizations of almost periodic strongly continuous cosine operator functions abstract we characterize in terms of the infinitesimal generator those cosine operator functions which are almost periodic or uniformly almost periodic

generalized kyp lemma unified frequency domain inequalities with design applications the celebrated kalman yakubovic spl caron popov kyp lemma establishes the equivalence between a frequency domain inequality fdi and a linear matrix inequality and has played one of the most fundamental roles in systems and control theory this paper first develops a necessary and sufficient condition for an s procedure to be lossless and uses the result to generalize the kyp lemma in two aspects the frequency range and the class of systems and to unify various existing versions by a single theorem in particular our result covers fdis in finite frequency intervals for both continuous discrete time settings as opposed to the standard infinite frequency range the class of systems for which fdis are considered is no longer constrained to be proper and nonproper transfer functions including polynomials can also be treated we study implications of this generalization and develop a proper interface between the basic result and various engineering applications specifically it is shown that our result allows us to solve a certain class of system design problems with multiple specifications on the gain phase properties in several frequency ranges the method is illustrated by numerical design examples of digital filters and proportional integral derivative controllers

fuzzy fault detection filter design for t s fuzzy systems in the finite frequency domain this paper deals with the fault detection filter design for a nonlinear discrete time system in the takagi sugeno fuzzy form with faults and unknown inputs both unknown input and fault frequencies are assumed to be known and to reside in low middle high frequency ranges a filter is proposed in the finite frequency domain to reduce the conservatism generated by those designed in the entire frequency domain in order to guarantee the best robustness to disturbances and sensitivity to faults the developed filter combines the h h infty performances the asymptotic stability of the filtering error dynamics is ensured by using a fuzzy lyapunov function and a linear matrix inequality approach finally two examples are presented to validate the proposed new design techniques

membership dependent stability conditions for type 1 and interval type 2 t s fuzzy systems abstract this paper presents an idea to simplify and relax the stability conditions of takagi sugeno t s fuzzy systems based on the membership function extrema 1 by considering the distribution of membership functions in a unified membership space a graphical approach is provided to analyze the conservativeness of membership dependent stability conditions membership function extrema are used to construct a simple and tighter convex polyhedron that encloses the membership trajectory and produces less conservative linear matrix inequality lmi conditions the cases of both type 1 and interval type 2 t s fuzzy systems are considered and comparison with existing methods is made in the proposed membership vector framework

sub tangentially loaded and damped beck s columns on two parameter elastic foundation the dynamic stability of the damped beck s column on two parameter elastic foundation is investigated by using hermitian beam elements for this purpose based on the extended hamilton s principle the dimensionless finite element fe formulation using the hermitian interpolation function is presented first the mass matrix the external and internal damping matrices the elastic and the geometric stiffness matrices winkler and pasternak foundation matrices and the load correction stiffness matrix due to the sub tangential follower force are obtained then evaluation procedure for the flutter and divergence loads of the non conservative system and the time history analysis using the newmark method are shortly described finally the influences of various parameters on the dynamic stability of non conservative systems are newly addressed 1 variation of the second flutter load due to sub tangentiality 2 influences of the external and the internal damping on flutter loads by analysis of complex natural frequencies 3 the effect of the growth rate of motion in a finite time interval using time history analysis and 4 fluctuation of divergence and flutter loads due to winkler and pasternak foundations