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Stability Criterion (stability + criterion)
Selected AbstractsA New Delay-Dependent Stability Criterion For Neutral Delay-Differential SystemsASIAN JOURNAL OF CONTROL, Issue 3 2003Bin Yang ABSTRACT This paper investigates the problem of asymptotic stability for neutral delay-differential systems. Using the Lyapunov method, we derive a new delay-dependent sufficient condition for the stability of systems in terms of the linear matrix inequality (LMI). Numerical examples show that the results obtained in this paper significantly improve the estimate of stability limit over some existing results reported previously in the literature. [source] Silicon Nanowires: A Review on Aspects of their Growth and their Electrical PropertiesADVANCED MATERIALS, Issue 25-26 2009Volker Schmidt Abstract This paper summarizes some of the essential aspects of silicon-nanowire growth and of their electrical properties. In the first part, a brief description of the different growth techniques is given, though the general focus of this work is on chemical vapor deposition of silicon nanowires. The advantages and disadvantages of the different catalyst materials for silicon-wire growth are discussed at length. Thereafter, in the second part, three thermodynamic aspects of silicon-wire growth via the vapor,liquid,solid mechanism are presented and discussed. These are the expansion of the base of epitaxially grown Si wires, a stability criterion regarding the surface tension of the catalyst droplet, and the consequences of the Gibbs,Thomson effect for the silicon wire growth velocity. The third part is dedicated to the electrical properties of silicon nanowires. First, different silicon nanowire doping techniques are discussed. Attention is then focused on the diameter dependence of dopant ionization and the influence of interface trap states on the charge carrier density in silicon nanowires. It is concluded by a section on charge carrier mobility and mobility measurements. [source] Manoeuvring and vibration reduction of a flexible spacecraft integrating optimal sliding mode controller and distributed piezoelectric sensors/actuatorsINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 6 2007Qinglei Hu Abstract This investigation is to apply optimal sliding mode (OSM) control theory and distributed piezoelectric sensor/actuator technology to vibration control of a flexible spacecraft. An approximate analytical dynamic model of a slewing flexible spacecraft with surface-bonded piezoelectric sensors/actuators is developed using Hamilton's principle with discretization by assumed model method. To satisfy pointing requirements and simultaneously suppress vibration, two separate control loops are adopted. The first uses the piezoceramics as sensors and actuators to actively suppress certain flexible modes by designing a positive position feedback (PPF) compensators that add damping to the flexible structures in certain critical modes in the inner feedback loop; then a second feedback loop is designed using OSM control to slew the spacecraft. The OSM controller minimizes the expected value of a quadratic objective function consisting of only the states with the constraints that the error states always remain on the intersection of sliding surfaces. The advantage in this method is that the vibration reduction and attitude control are achieved separately in the two separate feedback loops, allowing the pointing requirements and simultaneous vibrations suppression to be satisfied independently of one another. An additional attraction of the design method is that the selection of PPF gain is determined by introducing a cost function to be minimized by the feedback gains which are subject to the stability criterion at the same time, such that the feedback gains are selected in a more systematical way to avoid the arbitrary selecting of feedback gains. The proposed control strategy has been implemented on a flexible spacecraft, which is a hub with a cantilever flexible beam appendage and can undergo a single axis rotation. Both analytical and numerical results are presented to show the theoretical and practical merits of this approach. Copyright © 2006 John Wiley & Sons, Ltd. [source] Improved exponential stability for stochastic Markovian jump systems with nonlinearity and time-varying delayINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 1 2010Yong He Abstract This paper is concerned with delay-dependent exponential stability for stochastic Markovian jump systems with nonlinearity and time-varying delay. An improved exponential stability criterion for stochastic Markovian jump systems with nonlinearity and time-varying delay is proposed without ignoring any terms by considering the relationship among the time-varying delay, its upper bound and their difference, and using both Itô's differential formula and Lyapunov stability theory. A numerical example is given to illustrate the effectiveness and the benefits of the proposed method. Copyright © 2009 John Wiley & Sons, Ltd. [source] Delay-dependent robust stability for stochastic time-delay systems with polytopic uncertaintiesINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 15 2008Hongyi Li Abstract This paper considers a delay-dependent and parameter-dependent robust stability criterion for stochastic time-delay systems with polytopic uncertainties. The delay-dependent robust stability criterion, as expressed in terms of linear matrix inequalities (LMIs), is obtained by using parameter-dependent Lyapunov functions. It is shown that the result derived by a parameter-dependent Lyapunov functional is less conservative. Numerical examples are provided to illustrate the effectiveness of the proposed method. Copyright © 2008 John Wiley & Sons, Ltd. [source] Robust stabilizers for an implicit dynamical delay system of the neutral typeINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 4 2006D. P. GoodallArticle first published online: 28 DEC 200 Abstract A feedback stabilization problem is investigated for a class of imperfectly known implicit systems with discrete and distributed delays. The imperfections acting on the systems, which may be time-, state-, delayed state-, and/or input-dependent, are modelled as additive nonlinear perturbations influencing a known set of nonlinear functional differential equations of the neutral type. Sufficient conditions, which include a delay-dependent matrix inequality and a delay-dependent stability criterion involving some bounding parameters for the uncertainty in the system, are presented and a class of robust feedback stabilizers, including both memoryless and those with memory, are designed to guarantee a prescribed stability property for the class of implicit systems. Copyright © 2005 John Wiley & Sons, Ltd. [source] Further results on delay-dependent robust stability conditions of uncertain neutral systemsINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 5 2005Shengyuan Xu Abstract This paper deals with the problem of robust stability analysis for uncertain neutral systems. In terms of a linear matrix inequality (LMI), an improved delay-dependent asymptotic stability criterion is developed without using bounding techniques on the related cross product terms. Based on this, a new delay-dependent LMI condition for robust stability is obtained. Numerical examples are provided to show that the proposed results significantly improve the allowed upper bounds of the delay size over some existing ones in the literature. Copyright © 2005 John Wiley & Sons, Ltd. [source] Composition cascade control for chemical reactorsINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 13 2002Jose Alvarez-Ramirez Abstract Eventhough the composition control of chemical reactors is an old, widely studied, and still relevant problem in chemical process control, it still presents some aspects that remain unexplored or unresolved. For instance, a unifying approach is needed to systematize the existing ad hoc controller constructions, to rigorously explain their remarkable robustness property, and to explore the possibility of improving their construction and functioning. In this paper, some aspects of these control problems are addressed by resorting to recently developed approaches in constructive non-linear control, yielding a systematic controller construction coupled to a simple tuning scheme that can be executed with standard tuning rules, a closed-loop stability criterion, and an explanation of the closed-loop dynamics behaviour. Specifically, a linear cascade (master/slave) control configuration is proposed, which leads to global internal stability of the controlled system with asymptotic regulation of the output-stream composition about a given desired setpoint. A simulation example is used to illustrate the results. Copyright © 2002 John Wiley & Sons, Ltd. [source] A team algorithm for robust stability analysis and control design of uncertain time-varying linear systems using piecewise quadratic Lyapunov functionsINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 4 2001H. L. S. Almeida Abstract A team algorithm based on piecewise quadratic simultaneous Lyapunov functions for robust stability analysis and control design of uncertain time-varying linear systems is introduced. The objective is to use robust stability criteria that are less conservative than the usual quadratic stability criterion. The use of piecewise quadratic Lyapunov functions leads to a non-convex optimization problem, which is decomposed into a convex subproblem in a selected subset of decision variables, and a lower-dimensional non-convex subproblem in the remaining decision variables. A team algorithm that combines genetic algorithms (GA) for the non-convex subproblem and interior-point methods for the solution of linear matrix inequalities (LMI), which form the convex subproblem, is proposed. Numerical examples are given, showing the advantages of the proposed method. Copyright © 2001 John Wiley & Sons, Ltd. [source] Can vertebrate predation alter aggregation of risk in an insect host,parasitoid system?JOURNAL OF ANIMAL ECOLOGY, Issue 3 2002William F. Fagan Summary 1,Insect host,parasite systems allow investigations of the trophodynamics of ecological communities within a well-formed theoretical context. A little explored feature of such systems involves the interplay between generalized consumers and host,parasitoid dynamics. I report a study investigating how the impacts of generalized consumers, viewed here as interaction modifications, may influence the stability of a particular interspecific interaction. 2,In a study involving overwintering oothecae of the praying mantis Stagmomantis limbata (Hahn), birds damaged 36% of oothecae, 85% of which had also been parasitized by winter-active, multivoltine torymid wasps of the genus Podagrion. Birds preferentially preyed upon oothecae oviposited high on trees, but such predation was often incomplete, leaving both viable and parasitized mantid eggs inside damaged oothecae. 3,Two factors allowed bird damage to influence the distribution of risk of parasitism among oothecae and among hosts. These were (1) that some parasites , but no mantids , emerged successfully prior to bird predation and (2) that extensive post-damage foraging by parasitoids occurred, but that the nature of this foraging was altered little by oothecal damage. 4,In all, bird damage engendered a fourfold increase (from 1·5 to 6·5) in the CV2 of parasitism risk among hosts (a stability criterion that has been proposed for host,parasitoid interactions) and increased the relative importance of host-density-dependent parasitism. The role of timing of the two natural enemy impacts for stability of the host,parasitoid interaction is discussed. [source] Planning and controlling cooperating robots through distributed impedanceJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 6 2002Jérôme Szewczyk This article presents distributed impedance as a new approach for multiple robot system control. In this approach, each cooperating manipulator is controlled by an independent impedance controller. In addition, along selected degrees of freedom, force control is achieved through an external loop, to improve control of the object's internal loading. Extensive stability analysis is performed, based on a realistic model that includes robot impedance and object dynamics. Experiments are performed using two cooperating industrial robots holding an object through point contacts. Force and position control actions are suitably dispatched to achieve both internal loading control and object position control. Individual impedance parameters are specified according to the theoritical stability criterion. The performance of the system is demonstrated for transportation and contact tasks. © 2002 Wiley Periodicals, Inc. [source] A dual extremum principle in thermodynamics ,AICHE JOURNAL, Issue 8 2007Alexander Mitsos Abstract Phase equilibria of multicomponent mixtures are considered and a reinterpretation of the Gibbs tangent plane stability criterion is proposed via Lagrangian duality. The starting point is the natural primal problem of minimizing the Gibbs free energy subject to material balance. The stable phase split is the solution of the corresponding dual problem, providing a necessary and sufficient dual extremum principle. Only in the absence of duality gap is the physical phase split also the solution of the primal problem. The only requirements are continuity of the Gibbs free energy and the trivial requirement that each species is present in the overall composition. The number of phases is permitted to be infinite, and does not need to be known a priori. No assumption is made on the presence of all species in all phases. Case studies are presented based on the NRTL and UNIQUAC activity coefficient model. © 2007 American Institute of Chemical Engineers AIChE J, 2007 [source] An age-dependent population equation with delayed birth processMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 4 2004Susanna Piazzera Abstract Within a semigroup framework, we discuss well posedness and qualitative behaviour of an age-dependent population equation with delay in the birth process. Using positivity and Perron,Frobenius theory we obtain an explicit stability criterion. Copyright © 2004 John Wiley & Sons, Ltd. [source] Stability Structure for Lattice Boltzmann Equations: Some Computational ResultsPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2003M.K. Banda The Lattice Boltzmann equations are usually constructed to satisfy physical requirements like Galilean invariance and isotropy as well as to possess a velocity-independent pressure, no compressible effects, just to mention a few. In this paper, a stability criterion for such constructions is introduced and is used to derive a new relation of the parameters in a parametrized 2-dimensional 9-velocity model. [source] An application of Routh stability criterion to derive the necessary conditions for multiplicity of a CSTRTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2009Yu-Shu Chien Abstract It is well known that the Routh stability criterion (RSC) is a powerful method for analyzing control system stability. A new RSC finding that can aid the tangent analysis method (TAM) to determine the necessary conditions for multiplicity is presented. Adding RSC to TAM can find the bifurcation start point which cannot be obtained using TAM alone. To the author's knowledge, the above new RSC application has not been discussed in past literatures. Our results are helpful for chemical reactor design. We used two examples of the binary reaction in a non-adiabatic CSTR to demonstrate the merit of our methods. Il est bien connu que le critère de stabilité de Routh (RSC) est une méthode puissante pour l'analyse de la stabilité des systèmes de contrôle. On présente un nouveau résultat de RSC pouvant aider la méthode d'analyse des tangentes (TAM) à déterminer les conditions nécessaires pour la multiplicité. L'ajout de RSC à TAM permet de trouver le point de départ de la bifurcation qui ne peut pas être obtenu uniquement avec TAM. À la connaissance de l'auteur, cette nouvelle application RSC n'a pas été examinée dans la littérature scientifique antérieure. Nos résultats sont utiles pour la conception des réacteurs chimiques. Nous utilisons deux exemples de réaction binaire dans un CSTR non adiabatique pour démontrer le mérite de nos méthodes. [source] Stabilization for a class of complex interlaced systems using asymptotical gain,ASIAN JOURNAL OF CONTROL, Issue 2 2010Huawen Ye Abstract This paper addresses the stabilization problem of a class of interlaced systems that are not in a strict-feedforward form and contain some severe nonlinear terms. Bounded control laws in a fractional form are explicitly constructed. The feature of stability analysis allows the closed-loop system, when it is proven to have no finite escape time, to employ the asymptotical gain, which is obtained from an input-to-state stable (ISS) subsystem, to calculate the severe nonlinear terms, and the related estimate in turn guides the assignment of small controls. Together with the use of the passivity theory and the ISS-based stability criterion, the proposed method requires no small gain analysis although the asymptotical gain is used, and differs from the state-dependent saturation scheme since the controls do not include saturation functions. As an application, a new stabilizing control law is presented for the well-known friction ball-and-beam system. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source] Control Routh Array And Its ApplicationsASIAN JOURNAL OF CONTROL, Issue 1 2003Daizhan Cheng ABSTRACT In this paper the Routh stability criterion [16] has been developed into control Routh array. Some formulas for calculating the array are provided. Certain properties are investigated. Using it, the problem of stabilization of bilinear systems via constant controls is solved. Then by converting the problems, the method of control Routh array is also used to solve some other stability related problems, such as the stabilization of control systems, the stability of uncertain Hurwitz matrix and the stability of interval matrices. Several algorithms have been developed to provide numerical solutions. [source] Robust Analysis of Discrete-Time Lur'e Systems with Slope Restrictions Using Convex OptimizationASIAN JOURNAL OF CONTROL, Issue 2 2002David Banjerdpongchai ABSTRACT This paper considers robust stability and robust performance analysis for discrete-time linear systems subject to nonlinear uncertainty. The uncertainty set is described by memoryless, time-invariant, sector bounded, and slope restricted nonlinearities. We first give an overview of the absolute stability criterion based on the Lur'e-Postkinov Lyapunov function, along with a frequency domain condition. Subsequently, we derive sufficient conditions to compute the upper bounds of the worst case H2 and worst case H, performance. For both robust stability testing and robust performance computation, we show that these sufficient conditions can be readily and efficiently determined by performing convex optimization over linear matrix inequalities. [source] Ideelle Biegedrillknicklasten von Kreisbogenbindern aus Brettschichtholz mit gebundener KippachseBAUTECHNIK, Issue 12 2006Siegfried Eilering Prof. Dr.-Ing. Unter Verwendung des statischen Stabilitätskriteriums wird in Verbindung mit der Energiemethode eine spezielle stabbezogene Finite-Elemente-Formulierung entwickelt, mit deren Hilfe ideelle Biegeknick- und Biegedrillknicklasten von BSH-Bogenbindern bequem berechnet werden können. Wegen des geringen numerischen Aufwandes ist diese Formulierung hervorragend für Parameterstudien geeignet, die aufwendige Einzeluntersuchungen auf der Basis von zwei- oder dreidimensionalen FE-Modellen im Normalfall überflüssig machen. Die Ergebnisse einer solchen Studie an BSH-Kreisbogenbindern mit gebundener Obergurt-Kippachse werden im letzten Teil der Arbeit vorgestellt. Bifurcation loads of circular curved beams of glued-laminated timber with continuous lateral support. On the basis of the energy method in connection with the static stability criterion a specific finite element formulation is developed with which bifurcation loads of curved beams of glued-laminated timber can be determined easily. Because of the small numeric effort this procedure is excellently suitable for parameter studies. Extensive single investigations on the basis of two or three-dimensional finite element models become normally superfluous. In the last part of the paper the results of a study are presented at circular curved beams of glued-laminated timber. On condition of a continuous lateral support at the upper chord bifurcation loads are determined and presented graphically. [source] Linear stability and instability of relativistic Vlasov-Maxwell systemsCOMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 5 2007Zhiwu Lin We consider the linear stability problem for a symmetric equilibrium of the relativistic Vlasov-Maxwell (RVM) system. For an equilibrium whose distribution function depends monotonically on the particle energy, we obtain a sharp linear stability criterion. The growing mode is proved to be purely growing, and we get a sharp estimate of the maximal growth rate. In this paper we specifically treat the periodic 1½D case and the 3D whole-space case with cylindrical symmetry. We explicitly illustrate, using the linear stability criterion in the 1½D case, several stable and unstable examples. © 2006 Wiley Periodicals, Inc. [source] | |||||||||||||||||||