an algebraic approach to the time optimal output regulator the time optimal output regulator is considered for a special class of linear time invariant discrete time systems it is shown that a simple state feedback law achieves time optimal output regulator response in one sampling period for a square system the state feedback law always assigns the invariant zeros as closed loop poles for a non square system time optimal regulator response is achieved even if the set of invariant zeros is empty if the set of invariant zeros is not empty the control law always assigns these zeros as closed loop poles the method of this paper for the discrete system described by the state and output equations x k 1 ax k bu k and z k cx k does not require that a be invertible and that the open loop system s a b c be state controllable furthermore the only requirement is the existence of a right inverse for the matrix cb which is sufficient for output controllability

calculation of 3d internal displacement fields from 3d x ray computer tomographic images we present a new method for computing the internal displacement fields associated with permanent deformations of 3d composite objects with complex internal structure for fields satisfying the small displacement gradient approximation of continuum mechanics we compute the displacement fields from a sequence of 3d x ray computed tomography ct images by assuming that the intensity of the tomographic images represents a conserved property which is incompressible we develop a constrained nonlinear regression model for estimation of the displacement field successive linear approximation is then employed and each linear subsidiary problem is solved using variational calculus we approximate the resulting euler lagrange equations using a finite set of linear equations using finite differencing methods we solve these equations using a conjugate gradient algorithm in a multiresolution framework we validate our method using pairs of synthetic images of plane shear flow finally we determine the 3d displacement field in the interior of a cylindrical asphalt aggregate core loaded to a state of permanent deformation

a new approach to the perfect regulation and the bounded peaking in linear multivariable control systems this paper presents a new approach to the perfect regulation p r and the bounded peaking b p in linear multivariable control systems based on the pole and the eigenvector assignment technique roughly speaking the p r represents an ideal control action which reduces the settling time to 0 while the b p simply means the bounded overshoot in this ideal situation simple frequency domain characterizations of the p r and the b p are derived they reveal some invariance properties of the p r and the b p that provide a powerful tool for achieving the p r and the b p the existence condition for the p r is derived which turns out to be identical to the result obtained in the optimal regulator theory this result is extended to a more general control objective of attaining the p r for one output while keeping the b p for another output a condition on which the p r is realized by an output feedback is also derived a simple design algorithm is proposed for achieving the p r which is essentially the eigenvector assignment procedure finally an application to a real system is discussed

a unified method for the design of nonovershooting linear multivariable state feedback tracking controllers we consider the use of linear multivariable feedback control to achieve a nonovershooting step response a method is given for designing a linear time invariant state feedback controller to asymptotically track a constant step reference with zero overshoot and arbitrarily small rise time under some mild assumptions we present a unified design method that can be applied to continuous and discrete time systems square and non square systems minimum and nonminimum phase systems and also strictly proper and nonstrictly proper systems

a new domain decomposition method for an hjb equation in this paper we propose a new domain decompostion method for solving a hamilton jacobi bellman equation of second order the basic idea is to solve an equivalent quasivariational inequality instead of the original discretized hjb equation

capabilities and limitations of multirate control schemes abstract a fundamental obstacle in control system design is the presence of plant zeros recently it has been suggested that in digital control systems such problems may be overcome by using multirate sampling in this paper we describe the capabilities of such multirate control schemes with regard to pole and zero assignment we also point out a limitation of the approach due to degradation in the intersample behavior in mita and chida 1988 proc 27th conf on dec and control pp 1883 1888 it is shown that with a two delay input control scheme it is possible to assign all the poles and zeros of the closed loop system using state feedback in this paper we generalize this result to the case of n delay input control using dynamic compensators in an n delay input control scheme the input to the continuous system is changed n times more often than the output is sampled using such a scheme we show how to design output feedback controllers for siso systems that ensure arbitrary placement of all the poles and zeros of the closed loop system corresponding results for the mimo regulator and the siso servomechanism are given we also show that a hidden cost associated with the use of n delay input control is a degradation in the intersample behavior we demonstrate this via simulation and present an analysis which explains why this degradation arises

additive schwarz algorithm for the nonlinear complementarity problem with m function in this paper an additive schwarz algorithm is considered for solving the finite dimensional nonlinear complementarity problem with m function the monotone convergence of the algorithm is obtained with special choices of initial values moreover the weighted max norm bound is obtained for the iterative errors

on fixed modes in decentralized control systems this paper investigates the conditions for existence and the characterization of fixed modes in decentralized multivariable control systems employing local controllers it is shown that for scalar local controllers in the diagonal control structure the necessary and sufficient condition for a system polo at s to be a fixed mode is that s be a transmission zero of all subsystems formed by selecting the same inputs and outputs of the system the results are applied to scalar controllers in any arbitrary control structure and also to non scalar local controllers and similar conditions are obtained examples are discussed for illustration

shaping of the output response in a class of linear multivariable systems a state feedback controller is designed to regulate as desired the output response of minimum phase linear multivariable square plants with cb having full rank b input matrix and c output matrix properties of the controller are given and an example is worked out for illustration

computation of 3 d velocity fields from 3 d cine ct images of a human heart a method of computing the three dimensional 3 d velocity field from 3 d cine computer tomographs cts of a beating heart is proposed using continuum theory the authors develop two constraints on the 3 d velocity field generated by a beating heart with these constraints the computation of the 3 d velocity field is formulated as an optimization problem and a solution to the optimization problem is developed using the euler lagrange method the solution is then discretized for computer implementation the authors present the results for both simulated images and clinical cine ct images of a beating heart

rate of convergence for some constraint decomposition methods for nonlinear variational inequalities some general subspace correction algorithms are proposed for a convex optimization problem over a convex constraint subset one of the nontrivial applications of the algorithms is the solving of some obstacle problems by multilevel domain decomposition and multigrid methods for domain decomposition and multigrid methods the rate of convergence for the algorithms for obstacle problems is of the same order as the rate of convergence for jump coefficient linear elliptic problems in order to analyse the convergence rate we need to decompose a finite element function into a sum of functions from the subspaces and also satisfying some constraints a special nonlinear interpolation operator is introduced for decomposing the functions

convergence analysis ofgeneralized schwarz algorithms for solving obstacle problems with t monotone operator this paper proves the convergence of some generalized schwarz algorithms for solvingthe obstacle problems with a t monotone operator numerical results show that the generalized schwarz algorithms converge faster than the classical schwarz algorithms

on monotone and geometric convergence of schwarz methods for two sided obstacle problems convergence of schwarz methods is discussed for certain discretizations of two sided obstacle problems monotone and especially geometrical convergence are established if the stiffness matrix is a kind of m matrix and an h independent convergence rate is proved for uniformly overlapping decomposition

monotonic iterative algorithms for an implicit two sided obstacle problem abstract in this paper we present some iterative algorithms mainly schwarz algorithms for an implicit two sided obstacle problem the monotonic convergence of the algorithms is proved

an investigation of smoothness constraints for the estimation of displacement vector fields from image sequences a mapping between one frame from an image sequence and the preceding or following frame can be represented as a displacement vector field in most situations the mere gray value variations do not provide sufficient information in order to estimate such a displacement vector field supplementary constraints are necessary for example the postulate that a displacement vector field varies smoothly as a function of the image position taken as a general requirement this creates difficulties at gray value transitions which correspond to occluding contours nagel therefore introduced the oriented smoothness requirement which restricts variations of the displacement vector field only in directions with small or no variation of gray values this contribution reports results of an investigation about how such an oriented smoothness constraint may be formulated and evaluated

decoupling of continuous time linear time invariant systems using generalized sampled data hold functions abstract we investigate the possibility of input output decoupling without stability a square continuous time lti plant c a b by designing discrete devices the generalized sampled data hold functions by adopting sequential design procedures for the resulting diagonalizing problem two cases are found to be solvable and yield nontrivial solutions 1 cb nonsingular 2 m n 2m rk c b n m where n m are the number of states and inputs outputs respectively c i n c t cc t 1 c

linear matrix inequalities for globally monotonic tracking control this paper addresses the problem of achieving monotonic tracking control for any initial condition also referred to as global monotonic tracking control this property is shown to be equivalent to global non overshooting as well as to global non undershooting i e non overshooting and non undershooting for any initial condition respectively the main objective of this paper is to prove that a stable system is globally monotonic if and only if all the rows of the output matrix are left eigenvectors of the space transition matrix this property allows one to formulate the design of a controller which ensures global monotonic tracking as a convex optimization problem described by a set of linear matrix inequalities lmis

an iterative algorithm for a quasivariational inequality system related to hjb equation this paper presents a new iterative algorithm for a quasivariational inequality system related to hjb equation a domain decomposition method based on this algorithm is proposed the convergence theorems have been established

determining optical flow optical flow cannot be computed locally since only one independent measurement is available from the image sequence at a point while the flow velocity has two components a second constraint is needed a method for finding the optical flow pattern is presented which assumes that the apparent velocity of the brightness pattern varies smoothly almost everywhere in the image an iterative implementation is shown which successfully computes the optical flow for a number of synthetic image sequences the algorithm is robust in that it can handle image sequences that are quantized rather coarsely in space and time it is also insensitive to quantization of brightness levels and additive noise examples are included where the assumption of smoothness is violated at singular points or along lines in the image

on the schwarz alternating method with more than two subdomains for nonlinear monotone problems in a hilbert space an iterative process is defined which generalizes the schwarz alternating method for nonlinear monotone problems to more than two subdomains and the convergence of this process is proved in the case of the problems with the solution in a convex of h 0 1 omega it is proved that the method converges geometrically numerical results are given concerning the problem of elastic plastic torsion of prismatic bars and the problem of seepage of fluids through porous media

a multiplicative schwarz iteration scheme for solving the linear complementarity problem with an h matrix in this paper we consider an algebraic multiplicative schwarz iteration scheme for solving the linear complementarity problem that involves an h matrix we show that the sequence generated by the multiplicative schwarz iteration scheme converges to the unique solution of the problem without any restriction on the initial point for different overlapping sizes the convergence rate of the proposed method is analyzed in an algebraic setting moreover we establish monotone convergence of the proposed method under appropriate conditions numerical results show that efficiency can be achieved by the multiplicative schwarz iteration scheme

convergence analysis of p1 finite element method for free boundary problems on non overlapping subdomains abstract the paper applies a conforming p1 finite element method to general variational inequalities derived from free boundary problems the domain of the free boundary problem can be properly split into two non overlapping subdomains where the free boundary is located in only one subdomain the variational inequality is reduced to a partial differential equation in the subdomain which does not contain the free boundary but still keeps its original form in the other subdomain therefore the original variational inequality can be discretized separately with p1 finite element in different subdomains a non overlapping domain decomposition method is introduced to solve these two discretized sub problems by p1 finite element method iteratively while a robin type boundary condition is utilized for the data transfer on the common boundary we show that the sequence of such finite element solutions converges to the discretized solution of the original problem application to a free seepage problem verifies the theory