bifurcations in an asymmetric vocal fold model a two mass model of vocal fold vibrations is analyzed with methods from nonlinear dynamics bifurcations are located in parameter planes of physiological interest subglottal pressure stiffness of the folds it is shown that a sufficiently large tension imbalance of the left and right vocal fold induces bifurcations to subharmonic regimes toroidal oscillations and chaos the corresponding attractors are characterized by phase portraits spectra and next maximum maps the relevance of these simulations for voice disorders such as laryngeal paralysis is discussed

phonation onset vocal fold modeling and high speed glottography phonation onset is discussed in the framework of dynamical systems as a hopf bifurcation i e as a transition from damped to sustained vocal fold oscillations due to changes of parameters defining the underlying laryngeal configuration e g adduction subglottal pressure muscular activity an analytic envelope curve of the oscillation onset is deduced by analyzing the hopf bifurcation in mathematical models of the vocal folds it is governed by a single time constant which can be identified with the physiological parameter phonation onset time this parameter reflects the laryngeal state prior to phonation and can be used as a quantitative classification criterion in order to assess the phonation onset in clinical diagnosis the extraction of the phonation onset time from simulated time series using a simplified two mass model and from digital high speed videos is described in detail it shows a good agreement between theory and measurement

robust h control for uncertain discrete stochastic time delay systems this paper deals with the problems of robust stabilization and robust h control for discrete stochastic systems with time varying delays and time varying norm bounded parameter uncertainties for the robust stabilization problem attention is focused on the design of a state feedback controller which ensures robust stochastic stability of the closed loop system for all admissible uncertainties while for the robust h control problem a state feedback controller is designed such that in addition to the requirement of the robust stochastic stability a prescribed h performance level is also required to be satisfied a linear matrix inequality lmi approach is developed to solve these problems and delay dependent conditions for the solvability are obtained it is shown that the desired state feedback controller can be constructed by solving certain lmis an example is provided to demonstrate the effectiveness of the proposed approach

simultaneous lotsizing and scheduling by combining local search with dual reoptimization abstract the contribution of this paper is twofold on the one hand the particular problem of integrating lotsizing and scheduling of several products on a single capacitated production line is modelled and solved taking into account sequence dependent setup times thereby continuous lotsizes meeting deterministic dynamic demands are to be determined and scheduled with the objective of minimizing inventory holding costs and sequence dependent setup costs on the other hand a new general algorithmic approach is presented a dual reoptimization algorithm is combined with a local search heuristic for solving a mixed integer programming problem this idea is applied to the above lotsizing and scheduling problem by embedding a dual network flow algorithm into threshold accepting and simulated annealing respectively computational tests show the effectiveness of the new solution method

robust h spl infin control for uncertain stochastic systems with state delay this note deals with the problems of robust stochastic stabilization and robust h control for uncertain stochastic systems with a time varying delay in the state the parameter uncertainties are assumed to be time varying norm bounded appearing in both the state and input matrices the purpose of the robust stochastic stabilization problem is the design of a memoryless state feedback controller such that the closed loop system is mean square asymptotically stable for all admissible uncertainties in the robust h control problem in addition to the mean square asymptotic stability requirement a prescribed h performance is required to be achieved in terms of a linear matrix inequality sufficient conditions for the solvability of these problems are proposed respectively the expressions of desired state feedback controllers are given an example illustrating the proposed approach is provided

reoptimization procedures for bounded variable primal simplex network algorithms abstract many algorithms and applications call for the use of a network subprogram which must be optimized numerous times with slight changes to the problem data bound and right hand side changes to an existing basis tree may yield an infeasible basic solution this report gives a sequence of steps that modify an existing basic solution to reflect such changes and streamline the reoptimization process

robust passivity and passification of stochastic fuzzy time delay systems in this paper the passivity and passification problems are investigated for a class of uncertain stochastic fuzzy systems with time varying delays the fuzzy system is based on the takagi sugeno t s model that is often used to represent the complex nonlinear systems in terms of fuzzy sets and fuzzy reasoning to reflect more realistic dynamical behaviors of the system both the parameter uncertainties and the stochastic disturbances are considered where the parameter uncertainties enter into all the system matrices and the stochastic disturbances are given in the form of a brownian motion we first propose the definition of robust passivity in the sense of expectation then by utilizing the lyapunov functional method the ito differential rule and the matrix analysis techniques we establish several sufficient criteria such that for all admissible parameter uncertainties and stochastic disturbances the closed loop stochastic fuzzy time delay system is robustly passive in the sense of expectation the derived criteria which are either delay independent or delay dependent are expressed in terms of linear matrix inequalities lmis that can be easily checked by using the standard numerical software illustrative examples are presented to demonstrate the effectiveness and usefulness of the proposed results

razumikhin method and exponential stability of hybrid stochastic delay interval systems this paper deals with the exponential stability of hybrid stochastic delay interval systems also known as stochastic delay interval systems with markovian switching the known results in this area see e g x mao exponential stability of stochastic delay interval systems with markovian switching ieee trans automat control 47 10 2002 1604 1612 require the time delay to be a constant or a differentiable function and the main reason for such a restriction is due to the analysis of mathematics the main aim of this paper is to remove this restriction to allow the time delay to be a bounded variable only the razumikhin method is developed to cope with the difficulty arisen from the nondifferentiability of the time delay

stability of interval matrices the real eigenvalue case c v hollot and a c bartlett 1987 showed that testing at most 2 to the n sup 2 certain matrices for stability is sufficient for verifying stability of an n n interval matrix with real eigenvalues it is proven that this upper bound can be reduced to 2 sup 2n 1 and a special case where testing only two matrices is needed is considered

dual algorithms for pure network problems this paper reports the development of a new algorithmic implementation of the dual algorithm for the capacitated minimum cost network flow problem furthermore it introduces dual reoptimization procedures and compares primal and dual algorithms for the optimization and reoptimization of network problems the implementation makes use of cut sets for the efficient execution of the entering variable selection and the selection of the leaving variable is tied to the basis structure at an iteration empirical testing of the dual algorithm for optimization shows that it dominates the primal procedure for assignment problems with 400 nodes transportation problems with more than 600 nodes and transshipment problems with more than 1500 nodes computational testing with typical changes found in decomposition and relaxation procedures indicates the superiority of dual reoptimization over primal reoptimization for a sequence of parametric changes as would be typical in large scale programming techniques on the

exponential stability of stochastic delay interval systems with markovian switching in the past few years a lot of research has been dedicated to the stability of interval systems as well as the stability of systems with markovian switching however little research has been on the stability of interval systems with markovian switching which is the topic of this paper the system discussed is the stochastic delay interval system with markovian switching it is a very advanced system and takes all the features of interval systems ito equations and markovian switching as well as time lag into account the theory developed is applicable in many different and complicated situations so the importance of the paper is clear

finite time dissipative control for stochastic interval systems with time delay and markovian switching the finite time stochastically boundedness ftsb and the finite time strictly stochastically exponential dissipative ftssed control problems for the stochastic interval systems which are encountered the time delay and markovian switching are investigated in this paper the stochastic delayed interval systems with markovian switching sdisswms are equivalently transformed into a kind of stochastic uncertain time delay systems with markovian switching by interval matrix transformation some sufficient conditions of ftsb and ftssed for the stochastic delayed interval systems with markovian switching are obtained and the ftsb and ftssed controllers are designed by solving a series of linear matrix inequalities which are solvable by lmis toolbox finally a numerical example with simulations is given to illustrate the correctness of the obtained results and the effectiveness of the designed controller

parameter space methods for robust control design a guided tour the results obtained in studies of robust stability and stabilizability of control systems with parametric structured uncertainties are reviewed both the algebraic methods based upon characteristic equations and the methods using lyapunov functions and riccati equations are discussed and compared in the context of algebraic methods most promising are the kharitonov type approach and the optimization procedure of embedding a geometric figure of some kind inside the stability regions of the parameter space maximizing its size using minimax or some other mathematical programming technique in the framework of lyapunov s direct method the dominant approach has been a quadratic function estimation of stability regions in the parameter space in large sale systems the concept of vector lyapunov functions has been used with the possibility of choosing quadratic forms norm like functions and their combinations

stability results for stochastic delayed recurrent neural networks with discrete and distributed delays we present new conditions for asymptotic stability and exponential stability of a class of stochastic recurrent neural networks with discrete and distributed time varying delays our approach is based on the method using fixed point theory which do not resort to any liapunov function or liapunov functional our results neither require the boundedness monotonicity and differentiability of the activation functions nor differentiability of the time varying delays in particular a class of neural networks without stochastic perturbations is also considered examples are given to illustrate our main results

algorithms for network piecewise linear programs a comparative study abstract piecewise linear programming plp is an important area of mathematical programming and concerns the minimisation of a convex separable piecewise linear objective function subject to linear constraints in this paper a subarea of plp called network piecewise linear programming nplp is explored the paper presents four specialised algorithms for nplp strongly feasible primal simplex dual method out of kilter and strongly polynomial cost scaling and their relative efficiency is studied a statistically designed experiment is used to perform a computational comparison of the algorithms the response variable observed in the experiment is the cpu time to solve randomly generated network piecewise linear problems classified according to problem class transportation transshipment and circulation problem size extent of capacitation and number of breakpoints per arc results and conclusions on performance of the algorithms are reported

on delay dependent stability for a class of nonlinear stochastic systems with multiple state delays abstract global asymptotic stability conditions for nonlinear stochastic systems with multiple state delays are obtained based on the convergence theorem for semimartingale inequalities without assuming the lipschitz conditions for nonlinear drift functions the lyapunov krasovskii and degenerate functionals techniques are used the derived stability conditions are directly expressed in terms of the system coefficients nontrivial examples of nonlinear systems satisfying the obtained stability conditions are given

robust stochastic stabilization and h control of uncertain neutral stochastic time delay systems this paper investigates the problems of robust stochastic stabilization and robust h control for uncertain neutral stochastic time delay systems with time varying norm bounded parameter uncertainties appearing in both the state and input matrices the time delay is assumed to be unknown sufficient conditions for the existence of state feedback controllers are proposed which ensure mean square asymptotic stability of the resulting closed loop system and reduce the effect of the disturbance input on the controlled output to a prescribed level for all admissible uncertainties a linear matrix inequality approach is employed to design the desired state feedback controllers furthermore in the case when time delays appear in both the state and control input results on the robust stochastic stabilization and robust h control are also presented an illustrative example is provided to show the potential of the proposed techniques

obtaining a good primal solution to the uncapacitated transportation problem abstract sharma and sharma european journal of operational research 122 3 2000 37 have given a new procedure to solve the dual of the well known uncapacitated transportation problem this is expected to enhance the performance of dual based optimizing algorithms for solving the transportation problems in this paper we give a heuristic that obtains a very good starting solution with a duality gap of less than 2 for the primal transportation problem in o n 3 time and this is expected to enhance the performance of network simplex algorithm that obtains the optimal solution and runs in o n 3 log n time empirical investigation revealed that our heuristic gave significantly better solutions than the well known vogel s approximation method that runs in o n 2 time

a new dual based procedure for the transportation problem abstract we pose the transportation problem in a slightly different form to obtain a dual problem that has a special structure we exploit the structure of the dual problem to give a new heuristic that runs in o cn 2 time n is number of nodes in the network and c is a constant to improve the dual solution our heuristic obtained the optimal solution to several small sized transportation problems that we attempted and for large sized problems it obtained solutions that were within 82 of the optimal solution on average our approach gives good starting solutions for dual based approaches used for solving transportation problems and thus is expected to enhance their computational performance

synchronization control of stochastic delayed neural networks abstract in this paper synchronization control of stochastic neural networks with time varying delays has been considered a novel control method is given using the lyapunov functional method and linear matrix inequality lmi approach several sufficient conditions have been derived to ensure the global asymptotical stability in mean square for the error system and thus the drive system synchronize with the response system also the estimation gains can be obtained with these new and effective methods synchronization can be achieved simulation results are given to verify the theoretical analysis in this paper

a comprehensive review of stability analysis of continuous time recurrent neural networks stability problems of continuous time recurrent neural networks have been extensively studied and many papers have been published in the literature the purpose of this paper is to provide a comprehensive review of the research on stability of continuous time recurrent neural networks including hopfield neural networks cohen grossberg neural networks and related models since time delay is inevitable in practice stability results of recurrent neural networks with different classes of time delays are reviewed in detail for the case of delay dependent stability the results on how to deal with the constant variable delay in recurrent neural networks are summarized the relationship among stability results in different forms such as algebraic inequality forms m matrix forms linear matrix inequality forms and lyapunov diagonal stability forms is discussed and compared some necessary and sufficient stability conditions for recurrent neural networks without time delays are also discussed concluding remarks and future directions of stability analysis of recurrent neural networks are given

necessary and sufficient conditions for the hurwitz and schur stability of interval matrices establishes a set of new sufficient conditions for the hurwitz and schur stability of interval matrices the authors use these results to establish necessary and sufficient conditions for the hurwitz and schur stability of interval matrices the authors relate the above results to the existence of quadratic lyapunov functions for linear time invariant systems with interval valued coefficient matrices using the above results the authors develop an algorithm to determine the hurwitz and the schur stability properties of interval matrices the authors demonstrate the applicability of their results by means of two specific examples

exponential stability of stochastic delay interval systems abstract although deterministic interval systems have received a great deal of attention so far there is no work on stochastic interval systems the main aim of this paper is to initiate the study of stochastic interval systems of course there are many properties of such systems to be investigated but this paper will concentrate on the study of exponential stability of stochastic interval systems with time varying delays the main technique used in this paper is the razumikhin type theorem established recently by mao stochastic process appl 65 1996 233 250

dynamics of the two mass model of the vocal folds equilibria bifurcations and oscillation region the dynamics of the large amplitude oscillation of the vocal folds is analyzed using the two mass model first the equilibrium positions are determined in the case of a rectangular prephonatory glottis and the existence of two equilibrium positions besides the rest position is shown their stability is examined and a bifurcation diagram is derived with a normalized subglottal pressure and a coupling coefficient as control parameters phase plane plots are shown to illustrate the results the cases of convergent and divergent prephonatory glottis are then briefly considered the main results are finally discussed relative to previous analytical works it is shown that they disprove the previous oscillation theory based on the existence of a glottal negative differential resistance

representing inverses in pure network flow optimization abstract a basis for a pure network flow problem always exhibits special structure whose exploitation has led to the development of extremely efficient network optimization software the backbone of these programs is a data structure which represents the basis as a tree and is used to perform the linear algebraic steps required for optimization we demonstrate that the basis inverse also possesses a special structure which we call the inverse tree we develop a data structure to represent the inverse tree and we show that it obeys a symmetric relationship with the basis tree data structure the predecessor function of the inverse tree is the preorder link function of the basis tree and vice versa we develop efficient computational procedures for exploiting these results and show that using the inverse tree requires computation of the same order as the basis tree

on delay dependent stability for vector nonlinear stochastic delay difference equations with volterra diffusion term global asymptotic stability conditions for discrete vector nonlinear stochastic systems with state delay and volterra diffusion term are obtained based on the convergence theorem for semimartingale inequalities without assuming the lipschitz conditions for nonlinear drift functions the derived stability conditions are directly expressed in terms of the system coefficients a number of nontrivial examples of nonlinear systems satisfying the obtained stability conditions are given the obtained results are compared to some previously known asymptotic stability conditions for discrete nonlinear stochastic systems