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Sample records for delay dependent stability

  1. Delay-slope-dependent stability results of recurrent neural networks.

    Science.gov (United States)

    Li, Tao; Zheng, Wei Xing; Lin, Chong

    2011-12-01

    By using the fact that the neuron activation functions are sector bounded and nondecreasing, this brief presents a new method, named the delay-slope-dependent method, for stability analysis of a class of recurrent neural networks with time-varying delays. This method includes more information on the slope of neuron activation functions and fewer matrix variables in the constructed Lyapunov-Krasovskii functional. Then some improved delay-dependent stability criteria with less computational burden and conservatism are obtained. Numerical examples are given to illustrate the effectiveness and the benefits of the proposed method.

  2. Improving Delay-Range-Dependent Stability Condition for Systems with Interval Time-Varying Delay

    Directory of Open Access Journals (Sweden)

    Wei Qian

    2013-01-01

    Full Text Available This paper discusses the delay-range-dependent stability for systems with interval time-varying delay. Through defining the new Lyapunov-Krasovskii functional and estimating the derivative of the LKF by introducing new vectors, using free matrices and reciprocally convex approach, the new delay-range-dependent stability conditions are obtained. Two well-known examples are given to illustrate the less conservatism of the proposed theoretical results.

  3. Delay-dependent exponential stability for neural networks with discrete and distributed time-varying delays

    International Nuclear Information System (INIS)

    Zhu Xunlin; Wang Youyi

    2009-01-01

    This Letter studies the exponential stability for a class of neural networks (NNs) with both discrete and distributed time-varying delays. Under weaker assumptions on the activation functions, by defining a more general type of Lyapunov functionals and developing a new convex combination technique, new less conservative and less complex stability criteria are established to guarantee the global exponential stability of the discussed NNs. The obtained conditions are dependent on both discrete and distributed delays, are expressed in terms of linear matrix inequalities (LMIs), and contain fewer decision variables. Numerical examples are given to illustrate the effectiveness and the less conservatism of the proposed conditions.

  4. Delay-Dependent Asymptotic Stability of Cohen-Grossberg Models with Multiple Time-Varying Delays

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    Xiaofeng Liao

    2007-01-01

    Full Text Available Dynamical behavior of a class of Cohen-Grossberg models with multiple time-varying delays is studied in detail. Sufficient delay-dependent criteria to ensure local and global asymptotic stabilities of the equilibrium of this network are derived by constructing suitable Lyapunov functionals. The obtained conditions are shown to be less conservative and restrictive than those reported in the known literature. Some numerical examples are included to demonstrate our results.

  5. Delay-dependent exponential stability of cellular neural networks with time-varying delays

    International Nuclear Information System (INIS)

    Zhang Qiang; Wei Xiaopeng; Xu Jin

    2005-01-01

    The global exponential stability of cellular neural networks (CNNs) with time-varying delays is analyzed. Two new sufficient conditions ensuring global exponential stability for delayed CNNs are obtained. The conditions presented here are related to the size of delay. The stability results improve the earlier publications. Two examples are given to demonstrate the effectiveness of the obtained results

  6. Delay-Dependent Exponential Stability for Discrete-Time BAM Neural Networks with Time-Varying Delays

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    Yonggang Chen

    2008-01-01

    Full Text Available This paper considers the delay-dependent exponential stability for discrete-time BAM neural networks with time-varying delays. By constructing the new Lyapunov functional, the improved delay-dependent exponential stability criterion is derived in terms of linear matrix inequality (LMI. Moreover, in order to reduce the conservativeness, some slack matrices are introduced in this paper. Two numerical examples are presented to show the effectiveness and less conservativeness of the proposed method.

  7. Improved Criteria on Delay-Dependent Stability for Discrete-Time Neural Networks with Interval Time-Varying Delays

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    O. M. Kwon

    2012-01-01

    Full Text Available The purpose of this paper is to investigate the delay-dependent stability analysis for discrete-time neural networks with interval time-varying delays. Based on Lyapunov method, improved delay-dependent criteria for the stability of the networks are derived in terms of linear matrix inequalities (LMIs by constructing a suitable Lyapunov-Krasovskii functional and utilizing reciprocally convex approach. Also, a new activation condition which has not been considered in the literature is proposed and utilized for derivation of stability criteria. Two numerical examples are given to illustrate the effectiveness of the proposed method.

  8. Robust and global delay-dependent stability for genetic regulatory networks with parameter uncertainties.

    Science.gov (United States)

    Tian, Li-Ping; Wang, Jianxin; Wu, Fang-Xiang

    2012-09-01

    The study of stability is essential for designing or controlling genetic regulatory networks, which can be described by nonlinear differential equations with time delays. Much attention has been paid to the study of delay-independent stability of genetic regulatory networks and as a result, many sufficient conditions have been derived for delay-independent stability. Although it might be more interesting in practice, delay-dependent stability of genetic regulatory networks has been studied insufficiently. Based on the linear matrix inequality (LMI) approach, in this study we will present some delay-dependent stability conditions for genetic regulatory networks. Then we extend these results to genetic regulatory networks with parameter uncertainties. To illustrate the effectiveness of our theoretical results, gene repressilatory networks are analyzed .

  9. Novel delay-distribution-dependent stability analysis for continuous-time recurrent neural networks with stochastic delay

    International Nuclear Information System (INIS)

    Wang Shen-Quan; Feng Jian; Zhao Qing

    2012-01-01

    In this paper, the problem of delay-distribution-dependent stability is investigated for continuous-time recurrent neural networks (CRNNs) with stochastic delay. Different from the common assumptions on time delays, it is assumed that the probability distribution of the delay taking values in some intervals is known a priori. By making full use of the information concerning the probability distribution of the delay and by using a tighter bounding technique (the reciprocally convex combination method), less conservative asymptotic mean-square stable sufficient conditions are derived in terms of linear matrix inequalities (LMIs). Two numerical examples show that our results are better than the existing ones. (general)

  10. New delay-dependent absolute stability criteria for Lur'e systems with time-varying delay

    Science.gov (United States)

    Chen, Yonggang; Bi, Weiping; Li, Wenlin

    2011-07-01

    In this article, the absolute stability problem is investigated for Lur'e systems with time-varying delay and sector-bounded nonlinearity. By employing the delay fractioning idea, the new augmented Lyapunov functional is first constructed. Then, by introducing some slack matrices and by reserving the useful term when estimating the upper bound of the derivative of Lyapunov functional, the new delay-dependent absolute stability criteria are derived in terms of linear matrix inequalities. Several numerical examples are presented to show the effectiveness and the less conservativeness of the proposed method.

  11. New Delay-Dependent Stability Criteria for Uncertain Neutral Systems with Mixed Time-Varying Delays and Nonlinear Perturbations

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    Hamid Reza Karimi

    2009-01-01

    Full Text Available The problem of stability analysis for a class of neutral systems with mixed time-varying neutral, discrete and distributed delays and nonlinear parameter perturbations is addressed. By introducing a novel Lyapunov-Krasovskii functional and combining the descriptor model transformation, the Leibniz-Newton formula, some free-weighting matrices, and a suitable change of variables, new sufficient conditions are established for the stability of the considered system, which are neutral-delay-dependent, discrete-delay-range-dependent, and distributed-delay-dependent. The conditions are presented in terms of linear matrix inequalities (LMIs and can be efficiently solved using convex programming techniques. Two numerical examples are given to illustrate the efficiency of the proposed method.

  12. Stability switches, Hopf bifurcation and chaos of a neuron model with delay-dependent parameters

    International Nuclear Information System (INIS)

    Xu, X.; Hu, H.Y.; Wang, H.L.

    2006-01-01

    It is very common that neural network systems usually involve time delays since the transmission of information between neurons is not instantaneous. Because memory intensity of the biological neuron usually depends on time history, some of the parameters may be delay dependent. Yet, little attention has been paid to the dynamics of such systems. In this Letter, a detailed analysis on the stability switches, Hopf bifurcation and chaos of a neuron model with delay-dependent parameters is given. Moreover, the direction and the stability of the bifurcating periodic solutions are obtained by the normal form theory and the center manifold theorem. It shows that the dynamics of the neuron model with delay-dependent parameters is quite different from that of systems with delay-independent parameters only

  13. Delay-dependent asymptotic stability of mobile ad-hoc networks: A descriptor system approach

    International Nuclear Information System (INIS)

    Yang Juan; Yang Dan; Zhang Xiao-Hong; Huang Bin; Luo Jian-Lu

    2014-01-01

    In order to analyze the capacity stability of the time-varying-propagation and delay-dependent of mobile ad-hoc networks (MANETs), in this paper, a novel approach is proposed to explore the capacity asymptotic stability for the delay-dependent of MANETs based on non-cooperative game theory, where the delay-dependent conditions are explicitly taken into consideration. This approach is based on the Lyapunov—Krasovskii stability theory for functional differential equations and the linear matrix inequality (LMI) technique. A corresponding Lyapunov—Krasovskii functional is introduced for the stability analysis of this system with use of the descriptor and “neutral-type” model transformation without producing any additional dynamics. The delay-dependent stability criteria are derived for this system. Conditions are given in terms of linear matrix inequalities, and for the first time referred to neutral systems with the time-varying propagation and delay-dependent stability for capacity analysis of MANETs. The proposed criteria are less conservative since they are based on an equivalent model transformation. Furthermore, we also provide an effective and efficient iterative algorithm to solve the constrained stability control model. Simulation experiments have verified the effectiveness and efficiency of our algorithm. (general)

  14. Delay-dependent asymptotic stability of a two-neuron system with different time delays

    International Nuclear Information System (INIS)

    Tu Fenghua; Liao Xiaofeng; Zhang Wei

    2006-01-01

    In this paper, we consider a two-neuron system with time-delayed connections between neurons. Based on the construction of Lyapunov functionals, we obtain sufficient criteria to ensure local and global asymptotic stability of the equilibrium of the neural network. The obtained conditions are shown to be less conservative and restrictive than those reported in the literature. Some examples are included to illustrate our results

  15. Delay-dependent exponential stability analysis of bi-directional associative memory neural networks with time delay: an LMI approach

    International Nuclear Information System (INIS)

    Li Chuandong; Liao Xiaofeng; Zhang Rong

    2005-01-01

    For bi-directional associative memory (BAM) neural networks (NNs) with different constant or time-varying delays, the problems of determining the exponential stability and estimating the exponential convergence rate are investigated in this paper. An approach combining the Lyapunov-Krasovskii functional with the linear matrix inequality (LMI) is taken to study the problems, which provide bounds on the interconnection matrix and the activation functions, so as to guarantee the system's exponential stability. Some criteria for the exponential stability, which give information on the delay-dependent property, are derived. The results obtained in this paper provide one more set of easily verified guidelines for determining the exponential stability of delayed BAM (DBAM) neural networks, which are less conservative and less restrictive than the ones reported so far in the literature. Some typical examples are presented to show the application of the criteria obtained in this paper

  16. Improved delay-dependent globally asymptotic stability of delayed uncertain recurrent neural networks with Markovian jumping parameters

    International Nuclear Information System (INIS)

    Yan, Ji; Bao-Tong, Cui

    2010-01-01

    In this paper, we have improved delay-dependent stability criteria for recurrent neural networks with a delay varying over a range and Markovian jumping parameters. The criteria improve over some previous ones in that they have fewer matrix variables yet less conservatism. In addition, a numerical example is provided to illustrate the applicability of the result using the linear matrix inequality toolbox in MATLAB. (general)

  17. Delay-Dependent Stability Criteria of Uncertain Periodic Switched Recurrent Neural Networks with Time-Varying Delays

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    Xing Yin

    2011-01-01

    uncertain periodic switched recurrent neural networks with time-varying delays. When uncertain discrete-time recurrent neural network is a periodic system, it is expressed as switched neural network for the finite switching state. Based on the switched quadratic Lyapunov functional approach (SQLF and free-weighting matrix approach (FWM, some linear matrix inequality criteria are found to guarantee the delay-dependent asymptotical stability of these systems. Two examples illustrate the exactness of the proposed criteria.

  18. Delay-dependent stability of neural networks of neutral type with time delay in the leakage term

    International Nuclear Information System (INIS)

    Li, Xiaodi; Cao, Jinde

    2010-01-01

    This paper studies the global asymptotic stability of neural networks of neutral type with mixed delays. The mixed delays include constant delay in the leakage term (i.e. 'leakage delay'), time-varying delays and continuously distributed delays. Based on the topological degree theory, Lyapunov method and linear matrix inequality (LMI) approach, some sufficient conditions are derived ensuring the existence, uniqueness and global asymptotic stability of the equilibrium point, which are dependent on both the discrete and distributed time delays. These conditions are expressed in terms of LMI and can be easily checked by the MATLAB LMI toolbox. Even if there is no leakage delay, the obtained results are less restrictive than some recent works. It can be applied to neural networks of neutral type with activation functions without assuming their boundedness, monotonicity or differentiability. Moreover, the differentiability of the time-varying delay in the non-neutral term is removed. Finally, two numerical examples are given to show the effectiveness of the proposed method

  19. Delay-Dependent Stability Criterion for Bidirectional Associative Memory Neural Networks with Interval Time-Varying Delays

    Science.gov (United States)

    Park, Ju H.; Kwon, O. M.

    In the letter, the global asymptotic stability of bidirectional associative memory (BAM) neural networks with delays is investigated. The delay is assumed to be time-varying and belongs to a given interval. A novel stability criterion for the stability is presented based on the Lyapunov method. The criterion is represented in terms of linear matrix inequality (LMI), which can be solved easily by various optimization algorithms. Two numerical examples are illustrated to show the effectiveness of our new result.

  20. Stability of a viral infection model with state-dependent delay, CTL and antibody immune responses

    Czech Academy of Sciences Publication Activity Database

    Rezunenko, Oleksandr

    2017-01-01

    Roč. 22, č. 4 (2017), s. 1547-1563 ISSN 1531-3492 R&D Projects: GA ČR(CZ) GA16-06678S Institutional support: RVO:67985556 Keywords : Evolution equations * Lyapunov stability * state-dependent delay * virus infection model Subject RIV: BC - Control Systems Theory OBOR OECD: Computer sciences, information science, bioinformathics (hardware development to be 2.2, social aspect to be 5.8) Impact factor: 0.994, year: 2016 http://library.utia.cas.cz/separaty/2017/AS/rezunenko-0476128.pdf

  1. Improved Delay-Dependent Robust Stability Criteria for a Class of Uncertain Neutral Type Lur’e Systems with Discrete and Distributed Delays

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    Kaibo Shi

    2014-01-01

    Full Text Available This paper is concerned with the problem of delay-dependent robust stability analysis for a class of uncertain neutral type Lur’e systems with mixed time-varying delays. The system has not only time-varying uncertainties and sector-bounded nonlinearity, but also discrete and distributed delays, which has never been discussed in the previous literature. Firstly, by employing one effective mathematical technique, some less conservative delay-dependent stability results are established without employing the bounding technique and the mode transformation approach. Secondly, by constructing an appropriate new type of Lyapunov-Krasovskii functional with triple terms, improved delay-dependent stability criteria in terms of linear matrix inequalities (LMIs derived in this paper are much brief and valid. Furthermore, both nonlinearities located in finite sector and infinite one have been also fully taken into account. Finally, three numerical examples are presented to illustrate lesser conservatism and the advantage of the proposed main results.

  2. Delay-Dependent Stability Analysis of Uncertain Fuzzy Systems with State and Input Delays under Imperfect Premise Matching

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    Zejian Zhang

    2013-01-01

    Full Text Available This paper discusses the stability and stabilization problem for uncertain T-S fuzzy systems with time-varying state and input delays. A new augmented Lyapunov function with an additional triple-integral term and different membership functions of the fuzzy models and fuzzy controllers are introduced to derive the stability criterion, which is less conservative than the existing results. Moreover, a new flexibility design method is also provided. Some numerical examples are given to demonstrate the effectiveness and less conservativeness of the proposed method.

  3. New Delay-Dependent Robust Exponential Stability Criteria of LPD Neutral Systems with Mixed Time-Varying Delays and Nonlinear Perturbations

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    Sirada Pinjai

    2013-01-01

    Full Text Available This paper is concerned with the problem of robust exponential stability for linear parameter-dependent (LPD neutral systems with mixed time-varying delays and nonlinear perturbations. Based on a new parameter-dependent Lyapunov-Krasovskii functional, Leibniz-Newton formula, decomposition technique of coefficient matrix, free-weighting matrices, Cauchy’s inequality, modified version of Jensen’s inequality, model transformation, and linear matrix inequality technique, new delay-dependent robust exponential stability criteria are established in terms of linear matrix inequalities (LMIs. Numerical examples are given to show the effectiveness and less conservativeness of the proposed methods.

  4. Stability and Global Hopf Bifurcation Analysis on a Ratio-Dependent Predator-Prey Model with Two Time Delays

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    Huitao Zhao

    2013-01-01

    Full Text Available A ratio-dependent predator-prey model with two time delays is studied. By means of an iteration technique, sufficient conditions are obtained for the global attractiveness of the positive equilibrium. By comparison arguments, the global stability of the semitrivial equilibrium is addressed. By using the theory of functional equation and Hopf bifurcation, the conditions on which positive equilibrium exists and the quality of Hopf bifurcation are given. Using a global Hopf bifurcation result of Wu (1998 for functional differential equations, the global existence of the periodic solutions is obtained. Finally, an example for numerical simulations is also included.

  5. On the stability and multi-stability of a TCP/RED congestion control model with state-dependent delay and discontinuous marking function

    Science.gov (United States)

    Zhang, Shu; Xu, Jian; Chung, Kwok-wai

    2015-05-01

    Random early detection (RED) is an effective algorithm to control the Internet congestion. However, researches on RED parameters are difficult since there are state-dependent delay and discontinuous terms on the right-hand side of the model. We smooth the model by hyperbolic tangent function and reformulate it by a switch function to keep state variables positive. Numerical simulations on the original system validates the reformulated model. The multi-stability phenomenon is observed and some suggestions on the selection of RED parameters are given to enhance the global stability of the model by numerical bifurcation continuation on the reformulated model.

  6. Stability and delay sensitivity of neutral fractional-delay systems.

    Science.gov (United States)

    Xu, Qi; Shi, Min; Wang, Zaihua

    2016-08-01

    This paper generalizes the stability test method via integral estimation for integer-order neutral time-delay systems to neutral fractional-delay systems. The key step in stability test is the calculation of the number of unstable characteristic roots that is described by a definite integral over an interval from zero to a sufficient large upper limit. Algorithms for correctly estimating the upper limits of the integral are given in two concise ways, parameter dependent or independent. A special feature of the proposed method is that it judges the stability of fractional-delay systems simply by using rough integral estimation. Meanwhile, the paper shows that for some neutral fractional-delay systems, the stability is extremely sensitive to the change of time delays. Examples are given for demonstrating the proposed method as well as the delay sensitivity.

  7. The design of delay-dependent wide-area DOFC with prescribed degree of stability α for damping inter-area low-frequency oscillations in power system.

    Science.gov (United States)

    Sun, Miaoping; Nian, Xiaohong; Dai, Liqiong; Guo, Hua

    2017-05-01

    In this paper, the delay-dependent wide-area dynamic output feedback controller (DOFC) with prescribed degree of stability is proposed for interconnected power system to damp inter-area low-frequency oscillations. Here, the prescribed degree of stability α is used to maintain all the poles on the left of s=-α in the s-plane. Firstly, residue approach is adopted to select input-output control signals and the schur balanced truncation model reduction method is utilized to obtain the reduced power system model. Secondly, based on Lyapunov stability theory and transformation operation in complex plane, the sufficient condition of asymptotic stability for closed-loop power system with prescribed degree of stability α is derived. Then, a novel method based on linear matrix inequalities (LMIs) is presented to obtain the parameters of DOFC and calculate delay margin of the closed-loop system considering the prescribed degree of stability α. Finally, case studies are carried out on the two-area four-machine system, which is controlled by classical wide-area power system stabilizer (WAPSS) in reported reference and our proposed DOFC respectively. The effectiveness and advantages of the proposed method are verified by the simulation results under different operating conditions. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  8. Exponential stability of delayed fuzzy cellular neural networks with diffusion

    International Nuclear Information System (INIS)

    Huang Tingwen

    2007-01-01

    The exponential stability of delayed fuzzy cellular neural networks (FCNN) with diffusion is investigated. Exponential stability, significant for applications of neural networks, is obtained under conditions that are easily verified by a new approach. Earlier results on the exponential stability of FCNN with time-dependent delay, a special case of the model studied in this paper, are improved without using the time-varying term condition: dτ(t)/dt < μ

  9. Stability analysis of delayed genetic regulatory networks with stochastic disturbances

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Qi, E-mail: zhouqilhy@yahoo.com.c [School of Automation, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu (China); Xu Shengyuan [School of Automation, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu (China); Chen Bing [Institute of Complexity Science, Qingdao University, Qingdao 266071, Shandong (China); Li Hongyi [Space Control and Inertial Technology Research Center, Harbin Institute of Technology, Harbin 150001 (China); Chu Yuming [Department of Mathematics, Huzhou Teacher' s College, Huzhou 313000, Zhejiang (China)

    2009-10-05

    This Letter considers the problem of stability analysis of a class of delayed genetic regulatory networks with stochastic disturbances. The delays are assumed to be time-varying and bounded. By utilizing Ito's differential formula and Lyapunov-Krasovskii functionals, delay-range-dependent and rate-dependent (rate-independent) stability criteria are proposed in terms of linear matrices inequalities. An important feature of the proposed results is that all the stability conditions are dependent on the upper and lower bounds of the delays. Another important feature is that the obtained stability conditions are less conservative than certain existing ones in the literature due to introducing some appropriate free-weighting matrices. A simulation example is employed to illustrate the applicability and effectiveness of the proposed methods.

  10. A novel delay-dependent criterion for delayed neural networks of neutral type

    International Nuclear Information System (INIS)

    Lee, S.M.; Kwon, O.M.; Park, Ju H.

    2010-01-01

    This Letter considers a robust stability analysis method for delayed neural networks of neutral type. By constructing a new Lyapunov functional, a novel delay-dependent criterion for the stability is derived in terms of LMIs (linear matrix inequalities). A less conservative stability criterion is derived by using nonlinear properties of the activation function of the neural networks. Two numerical examples are illustrated to show the effectiveness of the proposed method.

  11. Recent Progress in Stability and Stabilization of Systems with Time-Delays

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    Magdi S. Mahmoud

    2017-01-01

    Full Text Available This paper overviews the research investigations pertaining to stability and stabilization of control systems with time-delays. The prime focus is the fundamental results and recent progress in theory and applications. The overview sheds light on the contemporary development on the linear matrix inequality (LMI techniques in deriving both delay-independent and delay-dependent stability results for time-delay systems. Particular emphases will be placed on issues concerned with the conservatism and the computational complexity of the results. Key technical bounding lemmas and slack variable introduction approaches will be presented. The results will be compared and connections of certain delay-dependent stability results are also discussed.

  12. Transcriptional delay stabilizes bistable gene networks.

    Science.gov (United States)

    Gupta, Chinmaya; López, José Manuel; Ott, William; Josić, Krešimir; Bennett, Matthew R

    2013-08-02

    Transcriptional delay can significantly impact the dynamics of gene networks. Here we examine how such delay affects bistable systems. We investigate several stochastic models of bistable gene networks and find that increasing delay dramatically increases the mean residence times near stable states. To explain this, we introduce a non-Markovian, analytically tractable reduced model. The model shows that stabilization is the consequence of an increased number of failed transitions between stable states. Each of the bistable systems that we simulate behaves in this manner.

  13. Stability of Neutral Fractional Neural Networks with Delay

    Institute of Scientific and Technical Information of China (English)

    LI Yan; JIANG Wei; HU Bei-bei

    2016-01-01

    This paper studies stability of neutral fractional neural networks with delay. By introducing the definition of norm and using the uniform stability, the sufficient condition for uniform stability of neutral fractional neural networks with delay is obtained.

  14. Simplified Stability Criteria for Delayed Neutral Systems

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    Xinghua Zhang

    2014-01-01

    Full Text Available For a class of linear time-invariant neutral systems with neutral and discrete constant delays, several existing asymptotic stability criteria in the form of linear matrix inequalities (LMIs are simplified by using matrix analysis techniques. Compared with the original stability criteria, the simplified ones include fewer LMI variables, which can obviously reduce computational complexity. Simultaneously, it is theoretically shown that the simplified stability criteria and original ones are equivalent; that is, they have the same conservativeness. Finally, a numerical example is employed to verify the theoretic results investigated in this paper.

  15. Temperature Dependent Wire Delay Estimation in Floorplanning

    DEFF Research Database (Denmark)

    Winther, Andreas Thor; Liu, Wei; Nannarelli, Alberto

    2011-01-01

    Due to large variations in temperature in VLSI circuits and the linear relationship between metal resistance and temperature, the delay through wires of the same length can be different. Traditional thermal aware floorplanning algorithms use wirelength to estimate delay and routability. In this w......Due to large variations in temperature in VLSI circuits and the linear relationship between metal resistance and temperature, the delay through wires of the same length can be different. Traditional thermal aware floorplanning algorithms use wirelength to estimate delay and routability....... In this work, we show that using wirelength as the evaluation metric does not always produce a floorplan with the shortest delay. We propose a temperature dependent wire delay estimation method for thermal aware floorplanning algorithms, which takes into account the thermal effect on wire delay. The experiment...

  16. Robust stability of bidirectional associative memory neural networks with time delays

    Science.gov (United States)

    Park, Ju H.

    2006-01-01

    Based on the Lyapunov Krasovskii functionals combined with linear matrix inequality approach, a novel stability criterion is proposed for asymptotic stability of bidirectional associative memory neural networks with time delays. A novel delay-dependent stability criterion is given in terms of linear matrix inequalities, which can be solved easily by various optimization algorithms.

  17. Robust stability of bidirectional associative memory neural networks with time delays

    International Nuclear Information System (INIS)

    Park, Ju H.

    2006-01-01

    Based on the Lyapunov-Krasovskii functionals combined with linear matrix inequality approach, a novel stability criterion is proposed for asymptotic stability of bidirectional associative memory neural networks with time delays. A novel delay-dependent stability criterion is given in terms of linear matrix inequalities, which can be solved easily by various optimization algorithms

  18. Delay-Dependent Guaranteed Cost Control of an Interval System with Interval Time-Varying Delay

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    Xiao Min

    2009-01-01

    Full Text Available This paper concerns the problem of the delay-dependent robust stability and guaranteed cost control for an interval system with time-varying delay. The interval system with matrix factorization is provided and leads to less conservative conclusions than solving a square root. The time-varying delay is assumed to belong to an interval and the derivative of the interval time-varying delay is not a restriction, which allows a fast time-varying delay; also its applicability is broad. Based on the Lyapunov-Ktasovskii approach, a delay-dependent criterion for the existence of a state feedback controller, which guarantees the closed-loop system stability, the upper bound of cost function, and disturbance attenuation lever for all admissible uncertainties as well as out perturbation, is proposed in terms of linear matrix inequalities (LMIs. The criterion is derived by free weighting matrices that can reduce the conservatism. The effectiveness has been verified in a number example and the compute results are presented to validate the proposed design method.

  19. Asymptotic stability of discrete-time systems with time-varying delay subject to saturation nonlinearities

    International Nuclear Information System (INIS)

    Chen, S.-F.

    2009-01-01

    The asymptotic stability problem for discrete-time systems with time-varying delay subject to saturation nonlinearities is addressed in this paper. In terms of linear matrix inequalities (LMIs), a delay-dependent sufficient condition is derived to ensure the asymptotic stability. A numerical example is given to demonstrate the theoretical results.

  20. Exponential stability of switched linear systems with time-varying delay

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    Satiracoo Pairote

    2007-11-01

    Full Text Available We use a Lyapunov-Krasovskii functional approach to establish the exponential stability of linear systems with time-varying delay. Our delay-dependent condition allows to compute simultaneously the two bounds that characterize the exponential stability rate of the solution. A simple procedure for constructing switching rule is also presented.

  1. Delay-Dependent Control for Networked Control Systems with Large Delays

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    Yilin Wang

    2013-01-01

    Full Text Available We consider the problems of robust stability and control for a class of networked control systems with long-time delays. Firstly, a nonlinear discrete time model with mode-dependent time delays is proposed by converting the uncertainty of time delay into the uncertainty of parameter matrices. We consider a probabilistic case where the system is switched among different subsystems, and the probability of each subsystem being active is defined as its occurrence probability. For a switched system with a known subsystem occurrence probabilities, we give a stochastic stability criterion in terms of linear matrix inequalities (LMIs. Then, we extend the results to a more practical case where the subsystem occurrence probabilities are uncertain. Finally, a simulation example is presented to show the efficacy of the proposed method.

  2. Study of calculated and measured time dependent delayed neutron yields

    International Nuclear Information System (INIS)

    Waldo, R.W.

    1980-05-01

    Time-dependent delayed neutron emission is of interest in reactor design, reactor dynamics, and nuclear physics studies. The delayed neutrons from neutron-induced fission of 232 U, 237 Np, 238 Pu, 241 Am, /sup 242m/Am, 245 Cm, and 249 Cf were studied for the first time. The delayed neutron emission from 232 Th, 233 U, 235 U, 238 U, 239 Pu, 241 Pu, and 242 Pu were measured as well. The data were used to develop an empirical expression for the total delayed neutron yield. The expression gives accurate results for a large variety of nuclides from 232 Th to 252 Cf. The data measuring the decay of delayed neutrons with time were used to derive another empirical expression predicting the delayed neutron emission with time. It was found that nuclides with similar mass-to-charge ratios have similar decay patterns. Thus the relative decay pattern of one nuclide can be established by any measured nuclide with a similar mass-to-charge ratio. A simple fission product yield model was developed and applied to delayed neutron precursors. It accurately predicts observed yield and decay characteristics. In conclusion, it is possible to not only estimate the total delayed neutron yield for a given nuclide but the time-dependent nature of the delayed neutrons as well. Reactors utilizing recycled fuel or burning actinides are likely to have inventories of fissioning nuclides that have not been studied until now. The delayed neutrons from these nuclides can now be incorporated so that their influence on the stability and control of reactors can be delineated. 8 figures, 39 tables

  3. Control of Thermodynamical System with Input-Dependent State Delays

    DEFF Research Database (Denmark)

    Bendtsen, Jan Dimon; Krstic, Miroslav

    2013-01-01

    We consider control of a cooling system with several consumers that require cooling from a common source. The flow feeding coolant to the consumers can be controlled, but due to significant physical distances between the common source and the consumers, the coolant flow takes a non......-negligible amount of time to travel to the consumers, giving rise to input-dependent state delays. We first present a simple bilinear model of the system, followed by a state feedback control design that is able to stabilize the system at a chosen equilibrium in spite of the delays. We also present a heuristic...

  4. Stabilization of Teleoperation Systems with Communication Delays: An IMC Approach

    Directory of Open Access Journals (Sweden)

    Yuling Li

    2018-01-01

    Full Text Available The presence of time delays in communication introduces a limitation to the stability of bilateral teleoperation systems. This paper considers internal model control (IMC design of linear teleoperation system with time delays, and the stability of the closed-loop system is analyzed. It is shown that the stability is guaranteed delay-independently. The passivity assumption for external forces is removed for the proposed design of teleoperation systems. The behavior of the resulting teleoperation system is illustrated by simulations.

  5. Mean Square Exponential Stability of Stochastic Switched System with Interval Time-Varying Delays

    Directory of Open Access Journals (Sweden)

    Manlika Rajchakit

    2012-01-01

    Full Text Available This paper is concerned with mean square exponential stability of switched stochastic system with interval time-varying delays. The time delay is any continuous function belonging to a given interval, but not necessary to be differentiable. By constructing a suitable augmented Lyapunov-Krasovskii functional combined with Leibniz-Newton’s formula, a switching rule for the mean square exponential stability of switched stochastic system with interval time-varying delays and new delay-dependent sufficient conditions for the mean square exponential stability of the switched stochastic system are first established in terms of LMIs. Numerical example is given to show the effectiveness of the obtained result.

  6. Stability criteria for neutral delay differential-algebraic equations

    Directory of Open Access Journals (Sweden)

    FAN Ni

    2013-10-01

    Full Text Available The asymptotic stability of neutral delay differential-algebraic equations is studied in this paper.Two stability criteria described by evaluating a corresponding harmonic function on the boundary of a torus region are presented.

  7. Stability of neutral type descriptor system with mixed delays

    International Nuclear Information System (INIS)

    Li Hong; Li Houbiao; Zhong Shouming

    2007-01-01

    In this paper, the stability problems of general neutral type descriptor system with mixed delays are considered. Some new delay-independent stability and robust stability criteria, which are simpler and less conservative than existing results, are derived in terms of the stability of a new operator I and linear matrix inequalities (LMIs). Therefore, criteria can be easily checked by utilizing the Matlab LMI toolbox

  8. Improved result on stability analysis of discrete stochastic neural networks with time delay

    International Nuclear Information System (INIS)

    Wu Zhengguang; Su Hongye; Chu Jian; Zhou Wuneng

    2009-01-01

    This Letter investigates the problem of exponential stability for discrete stochastic time-delay neural networks. By defining a novel Lyapunov functional, an improved delay-dependent exponential stability criterion is established in terms of linear matrix inequality (LMI) approach. Meanwhile, the computational complexity of the newly established stability condition is reduced because less variables are involved. Numerical example is given to illustrate the effectiveness and the benefits of the proposed method.

  9. A stability criterion for HNFDE with non-uniform delays

    International Nuclear Information System (INIS)

    Liu Xingwen; Zhong Shouming; Zhang Fengli

    2005-01-01

    Stability of functional differential equations (FDE) is an increasingly important problem in both science and engineering. Delays, whether uniform or non-uniform, play an important role in the dynamics of a system. Since non-uniform delay is more general and less focused than uniform delay, this paper concentrates on the stability of high-order neutral functional differential equations (HNFDE) with non-uniform delay, and proposes a sufficient condition for it. This result may be widely helpful, thanks to the frequent emergence of a HNFDE with non-uniform delay in various fields. Its effectiveness is illustrated by some examples

  10. Stability analysis of linear switching systems with time delays

    International Nuclear Information System (INIS)

    Li Ping; Zhong Shouming; Cui Jinzhong

    2009-01-01

    The issue of stability analysis of linear switching system with discrete and distributed time delays is studied in this paper. An appropriate switching rule is applied to guarantee the stability of the whole switching system. Our results use a Riccati-type Lyapunov functional under a condition on the time delay. So, switching systems with mixed delays are developed. A numerical example is given to illustrate the effectiveness of our results.

  11. Stability analysis for cellular neural networks with variable delays

    International Nuclear Information System (INIS)

    Zhang Qiang; Wei Xiaopeng; Xu Jin

    2006-01-01

    Some sufficient conditions for the global exponential stability of cellular neural networks with variable delay are obtained by means of a method based on delay differential inequality. The method, which does not make use of Lyapunov functionals, is simple and effective for the stability analysis of neural networks with delay. Some previously established results in the literature are shown to be special cases of the presented result

  12. Analysis of stability for stochastic delay integro-differential equations.

    Science.gov (United States)

    Zhang, Yu; Li, Longsuo

    2018-01-01

    In this paper, we concern stability of numerical methods applied to stochastic delay integro-differential equations. For linear stochastic delay integro-differential equations, it is shown that the mean-square stability is derived by the split-step backward Euler method without any restriction on step-size, while the Euler-Maruyama method could reproduce the mean-square stability under a step-size constraint. We also confirm the mean-square stability of the split-step backward Euler method for nonlinear stochastic delay integro-differential equations. The numerical experiments further verify the theoretical results.

  13. Global robust exponential stability for interval neural networks with delay

    International Nuclear Information System (INIS)

    Cui Shihua; Zhao Tao; Guo Jie

    2009-01-01

    In this paper, new sufficient conditions for globally robust exponential stability of neural networks with either constant delays or time-varying delays are given. We show the sufficient conditions for the existence, uniqueness and global robust exponential stability of the equilibrium point by employing Lyapunov stability theory and linear matrix inequality (LMI) technique. Numerical examples are given to show the approval of our results.

  14. Globally exponential stability condition of a class of neural networks with time-varying delays

    International Nuclear Information System (INIS)

    Liao, T.-L.; Yan, J.-J.; Cheng, C.-J.; Hwang, C.-C.

    2005-01-01

    In this Letter, the globally exponential stability for a class of neural networks including Hopfield neural networks and cellular neural networks with time-varying delays is investigated. Based on the Lyapunov stability method, a novel and less conservative exponential stability condition is derived. The condition is delay-dependent and easily applied only by checking the Hamiltonian matrix with no eigenvalues on the imaginary axis instead of directly solving an algebraic Riccati equation. Furthermore, the exponential stability degree is more easily assigned than those reported in the literature. Some examples are given to demonstrate validity and excellence of the presented stability condition herein

  15. Global exponential stability of octonion-valued neural networks with leakage delay and mixed delays.

    Science.gov (United States)

    Popa, Călin-Adrian

    2018-06-08

    This paper discusses octonion-valued neural networks (OVNNs) with leakage delay, time-varying delays, and distributed delays, for which the states, weights, and activation functions belong to the normed division algebra of octonions. The octonion algebra is a nonassociative and noncommutative generalization of the complex and quaternion algebras, but does not belong to the category of Clifford algebras, which are associative. In order to avoid the nonassociativity of the octonion algebra and also the noncommutativity of the quaternion algebra, the Cayley-Dickson construction is used to decompose the OVNNs into 4 complex-valued systems. By using appropriate Lyapunov-Krasovskii functionals, with double and triple integral terms, the free weighting matrix method, and simple and double integral Jensen inequalities, delay-dependent criteria are established for the exponential stability of the considered OVNNs. The criteria are given in terms of complex-valued linear matrix inequalities, for two types of Lipschitz conditions which are assumed to be satisfied by the octonion-valued activation functions. Finally, two numerical examples illustrate the feasibility, effectiveness, and correctness of the theoretical results. Copyright © 2018 Elsevier Ltd. All rights reserved.

  16. Stability Analysis of Fractional-Order Nonlinear Systems with Delay

    Directory of Open Access Journals (Sweden)

    Yu Wang

    2014-01-01

    Full Text Available Stability analysis of fractional-order nonlinear systems with delay is studied. We propose the definition of Mittag-Leffler stability of time-delay system and introduce the fractional Lyapunov direct method by using properties of Mittag-Leffler function and Laplace transform. Then some new sufficient conditions ensuring asymptotical stability of fractional-order nonlinear system with delay are proposed firstly. And the application of Riemann-Liouville fractional-order systems is extended by the fractional comparison principle and the Caputo fractional-order systems. Numerical simulations of an example demonstrate the universality and the effectiveness of the proposed method.

  17. Stability analysis for discrete-time stochastic memristive neural networks with both leakage and probabilistic delays.

    Science.gov (United States)

    Liu, Hongjian; Wang, Zidong; Shen, Bo; Huang, Tingwen; Alsaadi, Fuad E

    2018-06-01

    This paper is concerned with the globally exponential stability problem for a class of discrete-time stochastic memristive neural networks (DSMNNs) with both leakage delays as well as probabilistic time-varying delays. For the probabilistic delays, a sequence of Bernoulli distributed random variables is utilized to determine within which intervals the time-varying delays fall at certain time instant. The sector-bounded activation function is considered in the addressed DSMNN. By taking into account the state-dependent characteristics of the network parameters and choosing an appropriate Lyapunov-Krasovskii functional, some sufficient conditions are established under which the underlying DSMNN is globally exponentially stable in the mean square. The derived conditions are made dependent on both the leakage and the probabilistic delays, and are therefore less conservative than the traditional delay-independent criteria. A simulation example is given to show the effectiveness of the proposed stability criterion. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Robust stability bounds for multi-delay networked control systems

    Science.gov (United States)

    Seitz, Timothy; Yedavalli, Rama K.; Behbahani, Alireza

    2018-04-01

    In this paper, the robust stability of a perturbed linear continuous-time system is examined when controlled using a sampled-data networked control system (NCS) framework. Three new robust stability bounds on the time-invariant perturbations to the original continuous-time plant matrix are presented guaranteeing stability for the corresponding discrete closed-loop augmented delay-free system (ADFS) with multiple time-varying sensor and actuator delays. The bounds are differentiated from previous work by accounting for the sampled-data nature of the NCS and for separate communication delays for each sensor and actuator, not a single delay. Therefore, this paper expands the knowledge base in multiple inputs multiple outputs (MIMO) sampled-data time delay systems. Bounds are presented for unstructured, semi-structured, and structured perturbations.

  19. On global stability criterion for neural networks with discrete and distributed delays

    International Nuclear Information System (INIS)

    Park, Ju H.

    2006-01-01

    Based on the Lyapunov functional stability analysis for differential equations and the linear matrix inequality (LMI) optimization approach, a new delay-dependent criterion for neural networks with discrete and distributed delays is derived to guarantee global asymptotic stability. The criterion is expressed in terms of LMIs, which can be solved easily by various convex optimization algorithms. Some numerical examples are given to show the effectiveness of proposed method

  20. Global robust asymptotical stability of multi-delayed interval neural networks: an LMI approach

    International Nuclear Information System (INIS)

    Li Chuandong; Liao Xiaofeng; Zhang Rong

    2004-01-01

    Based on the Lyapunov-Krasovskii stability theory for functional differential equations and the linear matrix inequality (LMI) technique, some delay-dependent criteria for interval neural networks (IDNN) with multiple time-varying delays are derived to guarantee global robust asymptotic stability. The main results are generalizations of some recent results reported in the literature. Numerical example is also given to show the effectiveness of our results

  1. On exponential stability of bidirectional associative memory neural networks with time-varying delays

    International Nuclear Information System (INIS)

    Park, Ju H.; Lee, S.M.; Kwon, O.M.

    2009-01-01

    For bidirectional associate memory neural networks with time-varying delays, the problems of determining the exponential stability and estimating the exponential convergence rate are investigated by employing the Lyapunov functional method and linear matrix inequality (LMI) technique. A novel criterion for the stability, which give information on the delay-dependent property, is derived. A numerical example is given to demonstrate the effectiveness of the obtained results.

  2. Novel global robust stability criterion for neural networks with delay

    International Nuclear Information System (INIS)

    Singh, Vimal

    2009-01-01

    A novel criterion for the global robust stability of Hopfield-type interval neural networks with delay is presented. An example illustrating the improvement of the present criterion over several recently reported criteria is given.

  3. ORIGINAL ARTICLE Stability Analysis of Delayed Cournot Model in ...

    African Journals Online (AJOL)

    HP

    and Lyapunov method of nonlinear stability analysis are employed. It is ascertained ... and the rival player makes decision without delay, it leads to instability of the dynamic system at ... phenomena such as economic growth, prediction and ...

  4. Delay-independent stability of genetic regulatory networks.

    Science.gov (United States)

    Wu, Fang-Xiang

    2011-11-01

    Genetic regulatory networks can be described by nonlinear differential equations with time delays. In this paper, we study both locally and globally delay-independent stability of genetic regulatory networks, taking messenger ribonucleic acid alternative splicing into consideration. Based on nonnegative matrix theory, we first develop necessary and sufficient conditions for locally delay-independent stability of genetic regulatory networks with multiple time delays. Compared to the previous results, these conditions are easy to verify. Then we develop sufficient conditions for global delay-independent stability for genetic regulatory networks. Compared to the previous results, this sufficient condition is less conservative. To illustrate theorems developed in this paper, we analyze delay-independent stability of two genetic regulatory networks: a real-life repressilatory network with three genes and three proteins, and a synthetic gene regulatory network with five genes and seven proteins. The simulation results show that the theorems developed in this paper can effectively determine the delay-independent stability of genetic regulatory networks.

  5. STABILITY OF STOCHASTIC DIFFERENTIAL EQUATIONS WITH UNBOUNDED DELAY

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In this paper,we obtain suffcient conditions for the stability in p-th moment of the analytical solutions and the mean square stability of a stochastic differential equation with unbounded delay proposed in [6,10] using the explicit Euler method.

  6. Global exponential stability for nonautonomous cellular neural networks with delays

    International Nuclear Information System (INIS)

    Zhang Qiang; Wei Xiaopeng; Xu Jin

    2006-01-01

    In this Letter, by utilizing Lyapunov functional method and Halanay inequalities, we analyze global exponential stability of nonautonomous cellular neural networks with delay. Several new sufficient conditions ensuring global exponential stability of the network are obtained. The results given here extend and improve the earlier publications. An example is given to demonstrate the effectiveness of the obtained results

  7. Mean square exponential stability of stochastic delayed Hopfield neural networks

    International Nuclear Information System (INIS)

    Wan Li; Sun Jianhua

    2005-01-01

    Stochastic effects to the stability property of Hopfield neural networks (HNN) with discrete and continuously distributed delay are considered. By using the method of variation parameter, inequality technique and stochastic analysis, the sufficient conditions to guarantee the mean square exponential stability of an equilibrium solution are given. Two examples are also given to demonstrate our results

  8. Stability analysis of a class of fractional delay differential equations

    Indian Academy of Sciences (India)

    Abstract. In this paper we analyse stability of nonlinear fractional order delay differential equa- tions of the form Dα y(t) = af (y(t − τ )) − by(t), where Dα is a Caputo fractional derivative of order 0 < α ≤ 1. We describe stability regions using critical curves. To explain the proposed theory, we discuss fractional order logistic ...

  9. Stability analysis of a class of fractional delay differential equations

    Indian Academy of Sciences (India)

    In this paper we analyse stability of nonlinear fractional order delay differential equations of the form D y ( t ) = a f ( y ( t − ) ) − by ( t ) , where D is a Caputo fractional derivative of order 0 < ≤ 1. We describe stability regions using critical curves. To explain the proposed theory, we discuss fractional order logistic ...

  10. Global exponential stability for discrete-time neural networks with variable delays

    International Nuclear Information System (INIS)

    Chen Wuhua; Lu Xiaomei; Liang Dongying

    2006-01-01

    This Letter provides new exponential stability criteria for discrete-time neural networks with variable delays. The main technique is to reduce exponential convergence estimation of the neural network solution to that of one component of the corresponding solution by constructing Lyapunov function based on M-matrix. By introducing the tuning parameter diagonal matrix, the delay-independent and delay-dependent exponential stability conditions have been unified in the same mathematical formula. The effectiveness of the new results are illustrated by three examples

  11. Delaying gratification depends on social trust

    Science.gov (United States)

    Michaelson, Laura; de la Vega, Alejandro; Chatham, Christopher H.; Munakata, Yuko

    2013-01-01

    Delaying gratification is hard, yet predictive of important life outcomes, such as academic achievement and physical health. Prominent theories focus on the role of self-control, hypersensitivity to immediate rewards, and the cost of time spent waiting. However, delaying gratification may also require trust in people delivering future rewards as promised. To test the role of social trust, participants were presented with character vignettes and faces that varied in trustworthiness, and then choose between hypothetical smaller immediate or larger delayed rewards from those characters. Across two experiments, participants were less willing to wait for delayed rewards from less trustworthy characters, and perceived trustworthiness predicted willingness to delay gratification. These findings provide the first demonstration of a causal role for social trust in willingness to delay gratification, independent of other relevant factors, such as self-control or reward history. Thus, delaying gratification requires choosing not only a later reward, but a reward that is potentially less likely to be delivered, when there is doubt about the person promising it. Implications of this work include the need to revise prominent theories of delay of gratification, and new directions for interventions with populations characterized by impulsivity. PMID:23801977

  12. Delaying gratification depends on social trust

    Directory of Open Access Journals (Sweden)

    Laura eMichaelson

    2013-06-01

    Full Text Available Delaying gratification is hard, yet predictive of important life outcomes, such as academic achievement and physical health. Prominent theories focus on the role of self-control, hypersensitivity to immediate rewards, and the cost of time spent waiting. However, delaying gratification may also require trust in people delivering future rewards as promised. To test the role of social trust, participants were presented with character vignettes and faces that varied in trustworthiness, and then chose between hypothetical smaller immediate or larger delayed rewards from those characters. Across two experiments, participants were less willing to wait for delayed rewards from less trustworthy characters, and perceived trustworthiness predicted willingness to delay gratification. These findings provide the first demonstration of a causal role for social trust in willingness to delay gratification, independent of other relevant factors, such as self-control or reward history. Thus, delaying gratification requires choosing not only a later reward, but a reward that is potentially less likely to be delivered, when there is doubt about the person promising it. Implications of this work include the need to revise prominent theories of delay of gratification, and new directions for interventions with populations characterized by impulsivity.

  13. Finite-Time Stability of Large-Scale Systems with Interval Time-Varying Delay in Interconnection

    Directory of Open Access Journals (Sweden)

    T. La-inchua

    2017-01-01

    Full Text Available We investigate finite-time stability of a class of nonlinear large-scale systems with interval time-varying delays in interconnection. Time-delay functions are continuous but not necessarily differentiable. Based on Lyapunov stability theory and new integral bounding technique, finite-time stability of large-scale systems with interval time-varying delays in interconnection is derived. The finite-time stability criteria are delays-dependent and are given in terms of linear matrix inequalities which can be solved by various available algorithms. Numerical examples are given to illustrate effectiveness of the proposed method.

  14. Delay-Range-Dependent H∞ Control for Automatic Mooring Positioning System with Time-Varying Input Delay

    Directory of Open Access Journals (Sweden)

    Xiaoyu Su

    2014-01-01

    Full Text Available Aiming at the economy and security of the positioning system in semi-submersible platform, the paper presents a new scheme based on the mooring line switching strategy. Considering the input delay in switching process, H∞ control with time-varying input delay is designed to calculate the control forces to resist disturbing forces. In order to reduce the conservativeness, the information of the lower bound of delay is taken into account, and a Lyapunov function which contains the range of delay is constructed. Besides, the input constraint is considered to avoid breakage of mooring lines. The sufficient conditions for delay-range-dependent stabilization are derived in terms of LMI, and the controller is also obtained. The effectiveness of the proposed approach is illustrated by a realistic design example.

  15. Global robust stability of delayed recurrent neural networks

    International Nuclear Information System (INIS)

    Cao Jinde; Huang Deshuang; Qu Yuzhong

    2005-01-01

    This paper is concerned with the global robust stability of a class of delayed interval recurrent neural networks which contain time-invariant uncertain parameters whose values are unknown but bounded in given compact sets. A new sufficient condition is presented for the existence, uniqueness, and global robust stability of equilibria for interval neural networks with time delays by constructing Lyapunov functional and using matrix-norm inequality. An error is corrected in an earlier publication, and an example is given to show the effectiveness of the obtained results

  16. A delay-dependent approach to robust control for neutral uncertain neural networks with mixed interval time-varying delays

    International Nuclear Information System (INIS)

    Lu, Chien-Yu

    2011-01-01

    This paper considers the problem of delay-dependent global robust stabilization for discrete, distributed and neutral interval time-varying delayed neural networks described by nonlinear delay differential equations of the neutral type. The parameter uncertainties are norm bounded. The activation functions are assumed to be bounded and globally Lipschitz continuous. Using a Lyapunov functional approach and linear matrix inequality (LMI) techniques, the stability criteria for the uncertain neutral neural networks with interval time-varying delays are established in the form of LMIs, which can be readily verified using the standard numerical software. An important feature of the result reported is that all the stability conditions are dependent on the upper and lower bounds of the delays. Another feature of the results lies in that it involves fewer free weighting matrix strategy, and upper bounds of the inner product between two vectors are not introduced to reduce the conservatism of the criteria. Two illustrative examples are provided to demonstrate the effectiveness and the reduced conservatism of the proposed method

  17. Delay-Dependent Guaranteed Cost H∞ Control of an Interval System with Interval Time-Varying Delay

    Directory of Open Access Journals (Sweden)

    Zhongke Shi

    2009-01-01

    Full Text Available This paper concerns the problem of the delay-dependent robust stability and guaranteed cost H∞ control for an interval system with time-varying delay. The interval system with matrix factorization is provided and leads to less conservative conclusions than solving a square root. The time-varying delay is assumed to belong to an interval and the derivative of the interval time-varying delay is not a restriction, which allows a fast time-varying delay; also its applicability is broad. Based on the Lyapunov-Ktasovskii approach, a delay-dependent criterion for the existence of a state feedback controller, which guarantees the closed-loop system stability, the upper bound of cost function, and disturbance attenuation lever for all admissible uncertainties as well as out perturbation, is proposed in terms of linear matrix inequalities (LMIs. The criterion is derived by free weighting matrices that can reduce the conservatism. The effectiveness has been verified in a number example and the compute results are presented to validate the proposed design method.

  18. Razumikhin-Type Stability Criteria for Differential Equations with Delayed Impulses.

    Science.gov (United States)

    Wang, Qing; Zhu, Quanxin

    2013-01-01

    This paper studies stability problems of general impulsive differential equations where time delays occur in both differential and difference equations. Based on the method of Lyapunov functions, Razumikhin technique and mathematical induction, several stability criteria are obtained for differential equations with delayed impulses. Our results show that some systems with delayed impulses may be exponentially stabilized by impulses even if the system matrices are unstable. Some less restrictive sufficient conditions are also given to keep the good stability property of systems subject to certain type of impulsive perturbations. Examples with numerical simulations are discussed to illustrate the theorems. Our results may be applied to complex problems where impulses depend on both current and past states.

  19. Razumikhin-type stability criteria for differential equations with delayed impulses

    Directory of Open Access Journals (Sweden)

    Qing Wang

    2013-01-01

    Full Text Available This paper studies stability problems of general impulsive differential equations where time delays occur in both differential and difference equations. Based on the method of Lyapunov functions, Razumikhin technique and mathematical induction, several stability criteria are obtained for differential equations with delayed impulses. Our results show that some systems with delayed impulses may be exponentially stabilized by impulses even if the system matrices are unstable. Some less restrictive sufficient conditions are also given to keep the good stability property of systems subject to certain type of impulsive perturbations. Examples with numerical simulations are discussed to illustrate the theorems. Our results may be applied to complex problems where impulses depend on both current and past states.

  20. Novel results for global robust stability of delayed neural networks

    International Nuclear Information System (INIS)

    Yucel, Eylem; Arik, Sabri

    2009-01-01

    This paper investigates the global robust convergence properties of continuous-time neural networks with discrete time delays. By employing suitable Lyapunov functionals, some sufficient conditions for the existence, uniqueness and global robust asymptotic stability of the equilibrium point are derived. The conditions can be easily verified as they can be expressed in terms of the network parameters only. Some numerical examples are also given to compare our results with previous robust stability results derived in the literature.

  1. Stability results for stochastic delayed recurrent neural networks with discrete and distributed delays

    Science.gov (United States)

    Chen, Guiling; Li, Dingshi; Shi, Lin; van Gaans, Onno; Verduyn Lunel, Sjoerd

    2018-03-01

    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.

  2. Stability of time-delay systems via Lyapunov functions

    Directory of Open Access Journals (Sweden)

    Carlos F. Alastruey

    2002-01-01

    Full Text Available In this paper, a Lyapunov function candidate is introduced for multivariable systems with inner delays, without assuming a priori stability for the nondelayed subsystem. By using this Lyapunov function, a controller is deduced. Such a controller utilizes an input–output description of the original system, a circumstance that facilitates practical applications of the proposed approach.

  3. Criteria for stability of linear dynamical systems with multiple delays ...

    African Journals Online (AJOL)

    In this study we considered a linear Dynamical system with multiple delays and find suitable conditions on the systems parameters such that for a given initial function, we can define a mapping in a carefully chosen complete metric space on which the mapping has a unique fixed point. An asymptotic stability theory for the ...

  4. Novel stability criteria for uncertain delayed Cohen-Grossberg neural networks using discretized Lyapunov functional

    International Nuclear Information System (INIS)

    Souza, Fernando O.; Palhares, Reinaldo M.; Ekel, Petr Ya.

    2009-01-01

    This paper deals with the stability analysis of delayed uncertain Cohen-Grossberg neural networks (CGNN). The proposed methodology consists in obtaining new robust stability criteria formulated as linear matrix inequalities (LMIs) via the Lyapunov-Krasovskii theory. Particularly one stability criterion is derived from the selection of a parameter-dependent Lyapunov-Krasovskii functional, which allied with the Gu's discretization technique and a simple strategy that decouples the system matrices from the functional matrices, assures a less conservative stability condition. Two computer simulations are presented to support the improved theoretical results.

  5. Stability analysis of impulsive fuzzy cellular neural networks with distributed delays and reaction-diffusion terms

    International Nuclear Information System (INIS)

    Li Zuoan; Li Kelin

    2009-01-01

    In this paper, we investigate a class of impulsive fuzzy cellular neural networks with distributed delays and reaction-diffusion terms. By employing the delay differential inequality with impulsive initial conditions and M-matrix theory, we find some sufficient conditions ensuring the existence, uniqueness and global exponential stability of equilibrium point for impulsive fuzzy cellular neural networks with distributed delays and reaction-diffusion terms. In particular, the estimate of the exponential converging index is also provided, which depends on the system parameters. An example is given to show the effectiveness of the results obtained here.

  6. A new delay-independent condition for global robust stability of neural networks with time delays.

    Science.gov (United States)

    Samli, Ruya

    2015-06-01

    This paper studies the problem of robust stability of dynamical neural networks with discrete time delays under the assumptions that the network parameters of the neural system are uncertain and norm-bounded, and the activation functions are slope-bounded. By employing the results of Lyapunov stability theory and matrix theory, new sufficient conditions for the existence, uniqueness and global asymptotic stability of the equilibrium point for delayed neural networks are presented. The results reported in this paper can be easily tested by checking some special properties of symmetric matrices associated with the parameter uncertainties of neural networks. We also present a numerical example to show the effectiveness of the proposed theoretical results. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Global robust stability of neural networks with multiple discrete delays and distributed delays

    International Nuclear Information System (INIS)

    Gao Ming; Cui Baotong

    2009-01-01

    The problem of global robust stability is investigated for a class of uncertain neural networks with both multiple discrete time-varying delays and distributed time-varying delays. The uncertainties are assumed to be of norm-bounded form and the activation functions are supposed to be bounded and globally Lipschitz continuous. Based on the Lyapunov stability theory and linear matrix inequality technique, some robust stability conditions guaranteeing the global robust convergence of the equilibrium point are derived. The proposed LMI-based criteria are computationally efficient as they can be easily checked by using recently developed algorithms in solving LMIs. Two examples are given to show the effectiveness of the proposed results.

  8. State-dependent neutral delay equations from population dynamics.

    Science.gov (United States)

    Barbarossa, M V; Hadeler, K P; Kuttler, C

    2014-10-01

    A novel class of state-dependent delay equations is derived from the balance laws of age-structured population dynamics, assuming that birth rates and death rates, as functions of age, are piece-wise constant and that the length of the juvenile phase depends on the total adult population size. The resulting class of equations includes also neutral delay equations. All these equations are very different from the standard delay equations with state-dependent delay since the balance laws require non-linear correction factors. These equations can be written as systems for two variables consisting of an ordinary differential equation (ODE) and a generalized shift, a form suitable for numerical calculations. It is shown that the neutral equation (and the corresponding ODE--shift system) is a limiting case of a system of two standard delay equations.

  9. Control of District Heating System with Flow-dependent Delays

    DEFF Research Database (Denmark)

    Bendtsen, Jan Dimon; Ledesma, Jorge Val; Kallesøe, Carsten Skovmose

    2017-01-01

    All flow systems are subject to transport delays, which are governed by the flow rates in the system. When the flow rates themselves are control inputs, the system becomes subject to input-dependent state delays, which poses significant theoretical problems. In an earlier paper, we proposed...

  10. Hopf bifurcation of a ratio-dependent predator-prey system with time delay

    International Nuclear Information System (INIS)

    Celik, Canan

    2009-01-01

    In this paper, we consider a ratio dependent predator-prey system with time delay where the dynamics is logistic with the carrying capacity proportional to prey population. By considering the time delay as bifurcation parameter, we analyze the stability and the Hopf bifurcation of the system based on the normal form approach and the center manifold theory. Finally, we illustrate our theoretical results by numerical simulations.

  11. Improved asymptotic stability analysis for uncertain delayed state neural networks

    International Nuclear Information System (INIS)

    Souza, Fernando O.; Palhares, Reinaldo M.; Ekel, Petr Ya.

    2009-01-01

    This paper presents a new linear matrix inequality (LMI) based approach to the stability analysis of artificial neural networks (ANN) subject to time-delay and polytope-bounded uncertainties in the parameters. The main objective is to propose a less conservative condition to the stability analysis using the Gu's discretized Lyapunov-Krasovskii functional theory and an alternative strategy to introduce slack matrices. Two computer simulations examples are performed to support the theoretical predictions. Particularly, in the first example, the Hopf bifurcation theory is used to verify the stability of the system when the origin falls into instability. The second example is presented to illustrate how the proposed approach can provide better stability performance when compared to other ones in the literature

  12. Thermal Aware Floorplanning Incorporating Temperature Dependent Wire Delay Estimation

    DEFF Research Database (Denmark)

    Winther, AndreasThor; Liu, Wei; Nannarelli, Alberto

    2015-01-01

    Temperature has a negative impact on metal resistance and thus wire delay. In state-of-the-art VLSI circuits, large thermal gradients usually exist due to the uneven distribution of heat sources. The difference in wire temperature can lead to performance mismatch because wires of the same length...... can have different delay. Traditional floorplanning algorithms use wirelength to estimate wire performance. In this work, we show that this does not always produce a design with the shortest delay and we propose a floorplanning algorithm taking into account temperature dependent wire delay as one...

  13. Exponential stability for stochastic delayed recurrent neural networks with mixed time-varying delays and impulses: the continuous-time case

    International Nuclear Information System (INIS)

    Karthik Raja, U; Leelamani, A; Raja, R; Samidurai, R

    2013-01-01

    In this paper, the exponential stability for a class of stochastic neural networks with time-varying delays and impulsive effects is considered. By constructing suitable Lyapunov functionals and by using the linear matrix inequality optimization approach, we obtain sufficient delay-dependent criteria to ensure the exponential stability of stochastic neural networks with time-varying delays and impulses. Two numerical examples with simulation results are provided to illustrate the effectiveness of the obtained results over those already existing in the literature. (paper)

  14. Event-Based Stabilization over Networks with Transmission Delays

    Directory of Open Access Journals (Sweden)

    Xiangyu Meng

    2012-01-01

    Full Text Available This paper investigates asymptotic stabilization for linear systems over networks based on event-driven communication. A new communication logic is proposed to reduce the feedback effort, which has some advantages over traditional ones with continuous feedback. Considering the effect of time-varying transmission delays, the criteria for the design of both the feedback gain and the event-triggering mechanism are derived to guarantee the stability and performance requirements. Finally, the proposed techniques are illustrated by an inverted pendulum system and a numerical example.

  15. Global Asymptotic Stability of Switched Neural Networks with Delays

    Directory of Open Access Journals (Sweden)

    Zhenyu Lu

    2015-01-01

    Full Text Available This paper investigates the global asymptotic stability of a class of switched neural networks with delays. Several new criteria ensuring global asymptotic stability in terms of linear matrix inequalities (LMIs are obtained via Lyapunov-Krasovskii functional. And here, we adopt the quadratic convex approach, which is different from the linear and reciprocal convex combinations that are extensively used in recent literature. In addition, the proposed results here are very easy to be verified and complemented. Finally, a numerical example is provided to illustrate the effectiveness of the results.

  16. Periodic oscillation and exponential stability of delayed CNNs

    Science.gov (United States)

    Cao, Jinde

    2000-05-01

    Both the global exponential stability and the periodic oscillation of a class of delayed cellular neural networks (DCNNs) is further studied in this Letter. By applying some new analysis techniques and constructing suitable Lyapunov functionals, some simple and new sufficient conditions are given ensuring global exponential stability and the existence of periodic oscillatory solution of DCNNs. These conditions can be applied to design globally exponentially stable DCNNs and periodic oscillatory DCNNs and easily checked in practice by simple algebraic methods. These play an important role in the design and applications of DCNNs.

  17. On exponential stability and periodic solutions of CNNs with delays

    Science.gov (United States)

    Cao, Jinde

    2000-03-01

    In this Letter, the author analyses further problems of global exponential stability and the existence of periodic solutions of cellular neural networks with delays (DCNNs). Some simple and new sufficient conditions are given ensuring global exponential stability and the existence of periodic solutions of DCNNs by applying some new analysis techniques and constructing suitable Lyapunov functionals. These conditions have important leading significance in the design and applications of globally stable DCNNs and periodic oscillatory DCNNs and are weaker than those in the earlier works [Phys. Rev. E 60 (1999) 3244], [J. Comput. Syst. Sci. 59 (1999)].

  18. Stability and bifurcation analysis in a delayed SIR model

    International Nuclear Information System (INIS)

    Jiang Zhichao; Wei Junjie

    2008-01-01

    In this paper, a time-delayed SIR model with a nonlinear incidence rate is considered. The existence of Hopf bifurcations at the endemic equilibrium is established by analyzing the distribution of the characteristic values. A explicit algorithm for determining the direction of the Hopf bifurcation and the stability of the bifurcating periodic solutions are derived by using the normal form and the center manifold theory. Numerical simulations to support the analytical conclusions are carried out

  19. Oscillation and stability of delay models in biology

    CERN Document Server

    Agarwal, Ravi P; Saker, Samir H

    2014-01-01

    Environmental variation plays an important role in many biological and ecological dynamical systems. This monograph focuses on the study of oscillation and the stability of delay models occurring in biology. The book presents recent research results on the qualitative behavior of mathematical models under different physical and environmental conditions, covering dynamics including the distribution and consumption of food. Researchers in the fields of mathematical modeling, mathematical biology, and population dynamics will be particularly interested in this material.

  20. Global asymptotic stability of delayed Cohen-Grossberg neural networks

    International Nuclear Information System (INIS)

    Wu Wei; Cui Baotong; Huang Min

    2007-01-01

    In this letter, the global asymptotic stability of a class of Cohen-Grossberg neural networks with time-varying delays is discussed. A new set of sufficient conditions for the neural networks are proposed to guarantee the global asymptotic convergence. Our criteria represent an extension of the existing results in literatures. An example is also presented to compare our results with the previous results

  1. Effects of time delays on stability and Hopf bifurcation in a fractional ring-structured network with arbitrary neurons

    Science.gov (United States)

    Huang, Chengdai; Cao, Jinde; Xiao, Min; Alsaedi, Ahmed; Hayat, Tasawar

    2018-04-01

    This paper is comprehensively concerned with the dynamics of a class of high-dimension fractional ring-structured neural networks with multiple time delays. Based on the associated characteristic equation, the sum of time delays is regarded as the bifurcation parameter, and some explicit conditions for describing delay-dependent stability and emergence of Hopf bifurcation of such networks are derived. It reveals that the stability and bifurcation heavily relies on the sum of time delays for the proposed networks, and the stability performance of such networks can be markedly improved by selecting carefully the sum of time delays. Moreover, it is further displayed that both the order and the number of neurons can extremely influence the stability and bifurcation of such networks. The obtained criteria enormously generalize and improve the existing work. Finally, numerical examples are presented to verify the efficiency of the theoretical results.

  2. Stability Analysis of Nonlinear Time–Delayed Systems with Application to Biological Models

    Directory of Open Access Journals (Sweden)

    Kruthika H.A.

    2017-03-01

    Full Text Available In this paper, we analyse the local stability of a gene-regulatory network and immunotherapy for cancer modelled as nonlinear time-delay systems. A numerically generated kernel, using the sum-of-squares decomposition of multivariate polynomials, is used in the construction of an appropriate Lyapunov–Krasovskii functional for stability analysis of the networks around an equilibrium point. This analysis translates to verifying equivalent LMI conditions. A delay-independent asymptotic stability of a second-order model of a gene regulatory network, taking into consideration multiple commensurate delays, is established. In the case of cancer immunotherapy, a predator–prey type model is adopted to describe the dynamics with cancer cells and immune cells contributing to the predator–prey population, respectively. A delay-dependent asymptotic stability of the cancer-free equilibrium point is proved. Apart from the system and control point of view, in the case of gene-regulatory networks such stability analysis of dynamics aids mimicking gene networks synthetically using integrated circuits like neurochips learnt from biological neural networks, and in the case of cancer immunotherapy it helps determine the long-term outcome of therapy and thus aids oncologists in deciding upon the right approach.

  3. Stability analysis for stochastic BAM nonlinear neural network with delays

    Science.gov (United States)

    Lv, Z. W.; Shu, H. S.; Wei, G. L.

    2008-02-01

    In this paper, stochastic bidirectional associative memory neural networks with constant or time-varying delays is considered. Based on a Lyapunov-Krasovskii functional and the stochastic stability analysis theory, we derive several sufficient conditions in order to guarantee the global asymptotically stable in the mean square. Our investigation shows that the stochastic bidirectional associative memory neural networks are globally asymptotically stable in the mean square if there are solutions to some linear matrix inequalities(LMIs). Hence, the global asymptotic stability of the stochastic bidirectional associative memory neural networks can be easily checked by the Matlab LMI toolbox. A numerical example is given to demonstrate the usefulness of the proposed global asymptotic stability criteria.

  4. Stability analysis for stochastic BAM nonlinear neural network with delays

    International Nuclear Information System (INIS)

    Lv, Z W; Shu, H S; Wei, G L

    2008-01-01

    In this paper, stochastic bidirectional associative memory neural networks with constant or time-varying delays is considered. Based on a Lyapunov-Krasovskii functional and the stochastic stability analysis theory, we derive several sufficient conditions in order to guarantee the global asymptotically stable in the mean square. Our investigation shows that the stochastic bidirectional associative memory neural networks are globally asymptotically stable in the mean square if there are solutions to some linear matrix inequalities(LMIs). Hence, the global asymptotic stability of the stochastic bidirectional associative memory neural networks can be easily checked by the Matlab LMI toolbox. A numerical example is given to demonstrate the usefulness of the proposed global asymptotic stability criteria

  5. Hopf bifurcations of a ratio-dependent predator–prey model involving two discrete maturation time delays

    International Nuclear Information System (INIS)

    Karaoglu, Esra; Merdan, Huseyin

    2014-01-01

    Highlights: • A ratio-dependent predator–prey system involving two discrete maturation time delays is studied. • Hopf bifurcations are analyzed by choosing delay parameters as bifurcation parameters. • When a delay parameter passes through a critical value, Hopf bifurcations occur. • The direction of bifurcation, the period and the stability of periodic solution are also obtained. - Abstract: In this paper we give a detailed Hopf bifurcation analysis of a ratio-dependent predator–prey system involving two different discrete delays. By analyzing the characteristic equation associated with the model, its linear stability is investigated. Choosing delay terms as bifurcation parameters the existence of Hopf bifurcations is demonstrated. Stability of the bifurcating periodic solutions is determined by using the center manifold theorem and the normal form theory introduced by Hassard et al. Furthermore, some of the bifurcation properties including direction, stability and period are given. Finally, theoretical results are supported by some numerical simulations

  6. Stability Tests of Positive Fractional Continuous-time Linear Systems with Delays

    Directory of Open Access Journals (Sweden)

    Tadeusz Kaczorek

    2013-06-01

    Full Text Available Necessary and sufficient conditions for the asymptotic stability of positive fractional continuous-time linear systems with many delays are established. It is shown that: 1 the asymptotic stability of the positive fractional system is independent of their delays, 2 the checking of the asymptotic stability of the positive fractional systems with delays can be reduced to checking of the asymptotic stability of positive standard linear systems without delays.

  7. Detection of dependence patterns with delay.

    Science.gov (United States)

    Chevallier, Julien; Laloë, Thomas

    2015-11-01

    The Unitary Events (UE) method is a popular and efficient method used this last decade to detect dependence patterns of joint spike activity among simultaneously recorded neurons. The first introduced method is based on binned coincidence count (Grün, 1996) and can be applied on two or more simultaneously recorded neurons. Among the improvements of the methods, a transposition to the continuous framework has recently been proposed by Muiño and Borgelt (2014) and fully investigated by Tuleau-Malot et al. (2014) for two neurons. The goal of the present paper is to extend this study to more than two neurons. The main result is the determination of the limit distribution of the coincidence count. This leads to the construction of an independence test between L≥2 neurons. Finally, we propose a multiple test procedure via a Benjamini and Hochberg approach (Benjamini and Hochberg, 1995). All the theoretical results are illustrated by a simulation study, and compared to the UE method proposed by Grün et al. (2002). Furthermore our method is applied on real data. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Finite-time stability of discrete fractional delay systems: Gronwall inequality and stability criterion

    Science.gov (United States)

    Wu, Guo-Cheng; Baleanu, Dumitru; Zeng, Sheng-Da

    2018-04-01

    This study investigates finite-time stability of Caputo delta fractional difference equations. A generalized Gronwall inequality is given on a finite time domain. A finite-time stability criterion is proposed for fractional differential equations. Then the idea is extended to the discrete fractional case. A linear fractional difference equation with constant delays is considered and finite-time stable conditions are provided. One example is numerically illustrated to support the theoretical result.

  9. Local bifurcations in differential equations with state-dependent delay.

    Science.gov (United States)

    Sieber, Jan

    2017-11-01

    A common task when analysing dynamical systems is the determination of normal forms near local bifurcations of equilibria. As most of these normal forms have been classified and analysed, finding which particular class of normal form one encounters in a numerical bifurcation study guides follow-up computations. This paper builds on normal form algorithms for equilibria of delay differential equations with constant delay that were developed and implemented in DDE-Biftool recently. We show how one can extend these methods to delay-differential equations with state-dependent delay (sd-DDEs). Since higher degrees of regularity of local center manifolds are still open for sd-DDEs, we give an independent (still only partial) argument which phenomena from the truncated normal must persist in the full sd-DDE. In particular, we show that all invariant manifolds with a sufficient degree of normal hyperbolicity predicted by the normal form exist also in the full sd-DDE.

  10. Local bifurcations in differential equations with state-dependent delay

    Science.gov (United States)

    Sieber, Jan

    2017-11-01

    A common task when analysing dynamical systems is the determination of normal forms near local bifurcations of equilibria. As most of these normal forms have been classified and analysed, finding which particular class of normal form one encounters in a numerical bifurcation study guides follow-up computations. This paper builds on normal form algorithms for equilibria of delay differential equations with constant delay that were developed and implemented in DDE-Biftool recently. We show how one can extend these methods to delay-differential equations with state-dependent delay (sd-DDEs). Since higher degrees of regularity of local center manifolds are still open for sd-DDEs, we give an independent (still only partial) argument which phenomena from the truncated normal must persist in the full sd-DDE. In particular, we show that all invariant manifolds with a sufficient degree of normal hyperbolicity predicted by the normal form exist also in the full sd-DDE.

  11. Delay-range-dependent exponential H∞ synchronization of a class of delayed neural networks

    International Nuclear Information System (INIS)

    Karimi, Hamid Reza; Maass, Peter

    2009-01-01

    This article aims to present a multiple delayed state-feedback control design for exponential H ∞ synchronization problem of a class of delayed neural networks with multiple time-varying discrete delays. On the basis of the drive-response concept and by introducing a descriptor technique and using Lyapunov-Krasovskii functional, new delay-range-dependent sufficient conditions for exponential H ∞ synchronization of the drive-response structure of neural networks are driven in terms of linear matrix inequalities (LMIs). The explicit expression of the controller gain matrices are parameterized based on the solvability conditions such that the drive system and the response system can be exponentially synchronized. A numerical example is included to illustrate the applicability of the proposed design method.

  12. Robust Stabilization of Discrete-Time Systems with Time-Varying Delay: An LMI Approach

    Directory of Open Access Journals (Sweden)

    Valter J. S. Leite

    2008-01-01

    Full Text Available Sufficient linear matrix inequality (LMI conditions to verify the robust stability and to design robust state feedback gains for the class of linear discrete-time systems with time-varying delay and polytopic uncertainties are presented. The conditions are obtained through parameter-dependent Lyapunov-Krasovskii functionals and use some extra variables, which yield less conservative LMI conditions. Both problems, robust stability analysis and robust synthesis, are formulated as convex problems where all system matrices can be affected by uncertainty. Some numerical examples are presented to illustrate the advantages of the proposed LMI conditions.

  13. Local and global stability for Lotka-Volterra systems with distributed delays and instantaneous negative feedbacks

    Science.gov (United States)

    Faria, Teresa; Oliveira, José J.

    This paper addresses the local and global stability of n-dimensional Lotka-Volterra systems with distributed delays and instantaneous negative feedbacks. Necessary and sufficient conditions for local stability independent of the choice of the delay functions are given, by imposing a weak nondelayed diagonal dominance which cancels the delayed competition effect. The global asymptotic stability of positive equilibria is established under conditions slightly stronger than the ones required for the linear stability. For the case of monotone interactions, however, sharper conditions are presented. This paper generalizes known results for discrete delays to systems with distributed delays. Several applications illustrate the results.

  14. Stabilization of Networked Control Systems with Variable Delays and Saturating Inputs

    Directory of Open Access Journals (Sweden)

    M. Mahmodi Kaleybar

    2014-06-01

    Full Text Available In this paper, improved conditions for the synthesis of static state-feedback controller are derived to stabilize networked control systems (NCSs subject to actuator saturation. Both of the data packet latency and dropout which deteriorate the performance of the closed-loop system are considered in the NCS model via variable delays. Two different techniques are employed to incorporate actuator saturation in the system description. Utilizing Lyapunov-Krasovskii Theorem, delay-dependent conditions are obtained in terms of linear matrix inequalities (LMIs to determine the static feedback gain. Moreover, an optimization problem is formulated in order to find the less conservative estimate for the region of attraction corresponding to different maximum allowable delays. Numerical examples are introduced to demonstrate the effectiveness and advantages of the proposed schemes.

  15. Modified Schur-Cohn Criterion for Stability of Delayed Systems

    Directory of Open Access Journals (Sweden)

    Juan Ignacio Mulero-Martínez

    2015-01-01

    Full Text Available A modified Schur-Cohn criterion for time-delay linear time-invariant systems is derived. The classical Schur-Cohn criterion has two main drawbacks; namely, (i the dimension of the Schur-Cohn matrix generates some round-off errors eventually resulting in a polynomial of s with erroneous coefficients and (ii imaginary roots are very hard to detect when numerical errors creep in. In contrast to the classical Schur-Cohn criterion an alternative approach is proposed in this paper which is based on the application of triangular matrices over a polynomial ring in a similar way as in the Jury test of stability for discrete systems. The advantages of the proposed approach are that it halves the dimension of the polynomial and it only requires seeking real roots, making this modified criterion comparable to the Rekasius substitution criterion.

  16. Time-dependent delayed signatures from energetic photon interrogations

    International Nuclear Information System (INIS)

    Norman, Daren R.; Jones, James L.; Blackburn, Brandon W.; Haskell, Kevin J.; Johnson, James T.; Watson, Scott M.; Hunt, Alan W.; Spaulding, Randy; Harmon, Frank

    2007-01-01

    Pulsed photonuclear interrogation environments generated by 8-24 MeV electron linac are rich with time-dependent, material-specific, radiation signatures. Nitrogen-based explosives and nuclear materials can be detected by exploiting these signatures in different delayed-time regions. Numerical and experimental results presented in this paper show the unique time and energy dependence of these signatures. It is shown that appropriate delayed-time windows are essential to acquire material-specific signatures in pulsed photonuclear assessment environments. These developments demonstrate that pulsed, high-energy, photon-inspection environments can be exploited for time-dependent, material-specific signatures through the proper operation of specialized detectors and detection methods

  17. Absolute stability of nonlinear systems with time delays and applications to neural networks

    Directory of Open Access Journals (Sweden)

    Xinzhi Liu

    2001-01-01

    Full Text Available In this paper, absolute stability of nonlinear systems with time delays is investigated. Sufficient conditions on absolute stability are derived by using the comparison principle and differential inequalities. These conditions are simple and easy to check. In addition, exponential stability conditions for some special cases of nonlinear delay systems are discussed. Applications of those results to cellular neural networks are presented.

  18. Padé approximation of delays in cooperative ACC based on string stability requirements

    NARCIS (Netherlands)

    Xing, H.; Ploeg, J.; Nijmeijer, H.

    2016-01-01

    Cooperative adaptive cruise control (CACC) improves road throughput by employing intervehicle wireless communications. The inherent communication time delay and vehicle actuator delay significantly limit the minimum intervehicle distance in view of string stability requirements. Hence, controller

  19. Global exponential stability of inertial memristor-based neural networks with time-varying delays and impulses.

    Science.gov (United States)

    Zhang, Wei; Huang, Tingwen; He, Xing; Li, Chuandong

    2017-11-01

    In this study, we investigate the global exponential stability of inertial memristor-based neural networks with impulses and time-varying delays. We construct inertial memristor-based neural networks based on the characteristics of the inertial neural networks and memristor. Impulses with and without delays are considered when modeling the inertial neural networks simultaneously, which are of great practical significance in the current study. Some sufficient conditions are derived under the framework of the Lyapunov stability method, as well as an extended Halanay differential inequality and a new delay impulsive differential inequality, which depend on impulses with and without delays, in order to guarantee the global exponential stability of the inertial memristor-based neural networks. Finally, two numerical examples are provided to illustrate the efficiency of the proposed methods. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Delay-distribution-dependent H∞ state estimation for delayed neural networks with (x,v)-dependent noises and fading channels.

    Science.gov (United States)

    Sheng, Li; Wang, Zidong; Tian, Engang; Alsaadi, Fuad E

    2016-12-01

    This paper deals with the H ∞ state estimation problem for a class of discrete-time neural networks with stochastic delays subject to state- and disturbance-dependent noises (also called (x,v)-dependent noises) and fading channels. The time-varying stochastic delay takes values on certain intervals with known probability distributions. The system measurement is transmitted through fading channels described by the Rice fading model. The aim of the addressed problem is to design a state estimator such that the estimation performance is guaranteed in the mean-square sense against admissible stochastic time-delays, stochastic noises as well as stochastic fading signals. By employing the stochastic analysis approach combined with the Kronecker product, several delay-distribution-dependent conditions are derived to ensure that the error dynamics of the neuron states is stochastically stable with prescribed H ∞ performance. Finally, a numerical example is provided to illustrate the effectiveness of the obtained results. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Exponential stability of fuzzy cellular neural networks with constant and time-varying delays

    International Nuclear Information System (INIS)

    Liu Yanqing; Tang Wansheng

    2004-01-01

    In this Letter, the global stability of delayed fuzzy cellular neural networks (FCNN) with either constant delays or time varying delays is proposed. Firstly, we give the existence and uniqueness of the equilibrium point by using the theory of topological degree and the properties of nonsingular M-matrix and the sufficient conditions for ascertaining the global exponential stability by constructing a suitable Lyapunov functional. Secondly, the criteria for guaranteeing the global exponential stability of FCNN with time varying delays are given and the estimation of exponential convergence rate with regard to speed of vary of delays is presented by constructing a suitable Lyapunov functional

  2. Stability Analysis for Fractional-Order Linear Singular Delay Differential Systems

    Directory of Open Access Journals (Sweden)

    Hai Zhang

    2014-01-01

    Full Text Available We investigate the delay-independently asymptotic stability of fractional-order linear singular delay differential systems. Based on the algebraic approach, the sufficient conditions are presented to ensure the asymptotic stability for any delay parameter. By applying the stability criteria, one can avoid solving the roots of transcendental equations. An example is also provided to illustrate the effectiveness and applicability of the theoretical results.

  3. Stability and Hopf bifurcation in a delayed competitive web sites model

    International Nuclear Information System (INIS)

    Xiao Min; Cao Jinde

    2006-01-01

    The delayed differential equations modeling competitive web sites, based on the Lotka-Volterra competition equations, are considered. Firstly, the linear stability is investigated. It is found that there is a stability switch for time delay, and Hopf bifurcation occurs when time delay crosses through a critical value. Then the direction and stability of the bifurcated periodic solutions are determined, using the normal form theory and the center manifold reduction. Finally, some numerical simulations are carried out to illustrate the results found

  4. Music-dependent memory in immediate and delayed word recall.

    Science.gov (United States)

    Balch, W R; Bowman, K; Mohler, L

    1992-01-01

    Undergraduate volunteers rated a series of words for pleasantness while hearing a particular background music. The subjects in Experiment 1 received, immediately or after a 48-h delay, an unexpected word-recall test in one of the following musical cue contexts: same cue (S), different cue (D), or no cue (N). For immediate recall, context dependency (S-D) was significant but same-cue facilitation (S-N) was not. No cue effects at all were found for delayed recall, and there was a significant interaction between cue and retention interval. A similar interaction was also found in Experiment 3, which was designed to rule out an alternative explanation with respect to distraction. When the different musical selection was changed specifically in either tempo or form (genre), only pieces having an altered tempo produced significantly lower immediate recall compared with the same pieces (Experiment 2). The results support a stimulus generalization view of music-dependent memory.

  5. Stochastic Stability for Time-Delay Markovian Jump Systems with Sector-Bounded Nonlinearities and More General Transition Probabilities

    Directory of Open Access Journals (Sweden)

    Dan Ye

    2013-01-01

    Full Text Available This paper is concerned with delay-dependent stochastic stability for time-delay Markovian jump systems (MJSs with sector-bounded nonlinearities and more general transition probabilities. Different from the previous results where the transition probability matrix is completely known, a more general transition probability matrix is considered which includes completely known elements, boundary known elements, and completely unknown ones. In order to get less conservative criterion, the state and transition probability information is used as much as possible to construct the Lyapunov-Krasovskii functional and deal with stability analysis. The delay-dependent sufficient conditions are derived in terms of linear matrix inequalities to guarantee the stability of systems. Finally, numerical examples are exploited to demonstrate the effectiveness of the proposed method.

  6. Robust Stability Analysis of Neutral-Type Hybrid Bidirectional Associative Memory Neural Networks with Time-Varying Delays

    OpenAIRE

    Wei Feng; Simon X. Yang; Haixia Wu

    2014-01-01

    The global asymptotic robust stability of equilibrium is considered for neutral-type hybrid bidirectional associative memory neural networks with time-varying delays and parameters uncertainties. The results we obtained in this paper are delay-derivative-dependent and establish various relationships between the network parameters only. Therefore, the results of this paper are applicable to a larger class of neural networks and can be easily verified when compared with the previously reported ...

  7. Stability of formation control using a consensus protocol under directed communications with two time delays and delay scheduling

    Science.gov (United States)

    Cepeda-Gomez, Rudy; Olgac, Nejat

    2016-01-01

    We consider a linear algorithm to achieve formation control in a group of agents which are driven by second-order dynamics and affected by two rationally independent delays. One of the delays is in the position and the other in the velocity information channels. These delays are taken as constant and uniform throughout the system. The communication topology is assumed to be directed and fixed. The formation is attained by adding a supplementary control term to the stabilising consensus protocol. In preparation for the formation control logic, we first study the stability of the consensus, using the recent cluster treatment of characteristic roots (CTCR) paradigm. This effort results in a unique depiction of the non-conservative stability boundaries in the domain of the delays. However, CTCR requires the knowledge of the potential stability switching loci exhaustively within this domain. The creation of these loci is done in a new surrogate coordinate system, called the 'spectral delay space (SDS)'. The relative stability is also investigated, which has to do with the speed of reaching consensus. This step leads to a paradoxical control design concept, called the 'delay scheduling', which highlights the fact that the group behaviour may be enhanced by increasing the delays. These steps lead to a control strategy to establish a desired group formation that guarantees spacing among the agents. Example case studies are presented to validate the underlying analytical derivations.

  8. Stability analysis of fractional-order Hopfield neural networks with time delays.

    Science.gov (United States)

    Wang, Hu; Yu, Yongguang; Wen, Guoguang

    2014-07-01

    This paper investigates the stability for fractional-order Hopfield neural networks with time delays. Firstly, the fractional-order Hopfield neural networks with hub structure and time delays are studied. Some sufficient conditions for stability of the systems are obtained. Next, two fractional-order Hopfield neural networks with different ring structures and time delays are developed. By studying the developed neural networks, the corresponding sufficient conditions for stability of the systems are also derived. It is shown that the stability conditions are independent of time delays. Finally, numerical simulations are given to illustrate the effectiveness of the theoretical results obtained in this paper. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Global stability for infectious disease models that include immigration of infected individuals and delay in the incidence

    Directory of Open Access Journals (Sweden)

    Chelsea Uggenti

    2018-03-01

    Full Text Available We begin with a detailed study of a delayed SI model of disease transmission with immigration into both classes. The incidence function allows for a nonlinear dependence on the infected population, including mass action and saturating incidence as special cases. Due to the immigration of infectives, there is no disease-free equilibrium and hence no basic reproduction number. We show there is a unique endemic equilibrium and that this equilibrium is globally asymptotically stable for all parameter values. The results include vector-style delay and latency-style delay. Next, we show that previous global stability results for an SEI model and an SVI model that include immigration of infectives and non-linear incidence but not delay can be extended to systems with vector-style delay and latency-style delay.

  10. Existence results for impulsive evolution differential equations with state-dependent delay

    OpenAIRE

    Eduardo Hernandez M.; Rathinasamy Sakthivel; Sueli Tanaka Aki

    2008-01-01

    We study the existence of mild solution for impulsive evolution abstract differential equations with state-dependent delay. A concrete application to partial delayed differential equations is considered.

  11. Stability analysis of Runge-Kutta methods for nonlinear neutral delay integro-differential equations

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The sufficient conditions for the stability and asymptotic stability of Runge-Kutta methods for nonlinear neutral delay integro-differential equations are derived. A numerical test that confirms the theoretical results is given in the end.

  12. On global exponential stability of high-order neural networks with time-varying delays

    International Nuclear Information System (INIS)

    Zhang Baoyong; Xu Shengyuan; Li Yongmin; Chu Yuming

    2007-01-01

    This Letter investigates the problem of stability analysis for a class of high-order neural networks with time-varying delays. The delays are bounded but not necessarily differentiable. Based on the Lyapunov stability theory together with the linear matrix inequality (LMI) approach and the use of Halanay inequality, sufficient conditions guaranteeing the global exponential stability of the equilibrium point of the considered neural networks are presented. Two numerical examples are provided to demonstrate the effectiveness of the proposed stability criteria

  13. On global exponential stability of high-order neural networks with time-varying delays

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Baoyong [School of Automation, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu (China)]. E-mail: baoyongzhang@yahoo.com.cn; Xu Shengyuan [School of Automation, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu (China)]. E-mail: syxu02@yahoo.com.cn; Li Yongmin [School of Automation, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu (China) and Department of Mathematics, Huzhou Teacher' s College, Huzhou 313000, Zhejiang (China)]. E-mail: ymlwww@163.com; Chu Yuming [Department of Mathematics, Huzhou Teacher' s College, Huzhou 313000, Zhejiang (China)

    2007-06-18

    This Letter investigates the problem of stability analysis for a class of high-order neural networks with time-varying delays. The delays are bounded but not necessarily differentiable. Based on the Lyapunov stability theory together with the linear matrix inequality (LMI) approach and the use of Halanay inequality, sufficient conditions guaranteeing the global exponential stability of the equilibrium point of the considered neural networks are presented. Two numerical examples are provided to demonstrate the effectiveness of the proposed stability criteria.

  14. Global exponential stability of uncertain fuzzy BAM neural networks with time-varying delays

    International Nuclear Information System (INIS)

    Syed Ali, M.; Balasubramaniam, P.

    2009-01-01

    In this paper, the Takagi-Sugeno (TS) fuzzy model representation is extended to the stability analysis for uncertain Bidirectional Associative Memory (BAM) neural networks with time-varying delays using linear matrix inequality (LMI) theory. A novel LMI-based stability criterion is obtained by LMI optimization algorithms to guarantee the exponential stability of uncertain BAM neural networks with time-varying delays which are represented by TS fuzzy models. Finally, the proposed stability conditions are demonstrated with numerical examples.

  15. Linear time delay methods and stability analyses of the human spine. Effects of neuromuscular reflex response.

    Science.gov (United States)

    Franklin, Timothy C; Granata, Kevin P; Madigan, Michael L; Hendricks, Scott L

    2008-08-01

    Linear stability methods were applied to a biomechanical model of the human musculoskeletal spine to investigate effects of reflex gain and reflex delay on stability. Equations of motion represented a dynamic 18 degrees-of-freedom rigid-body model with time-delayed reflexes. Optimal muscle activation levels were identified by minimizing metabolic power with the constraints of equilibrium and stability with zero reflex time delay. Muscle activation levels and associated muscle forces were used to find the delay margin, i.e., the maximum reflex delay for which the system was stable. Results demonstrated that stiffness due to antagonistic co-contraction necessary for stability declined with increased proportional reflex gain. Reflex delay limited the maximum acceptable proportional reflex gain, i.e., long reflex delay required smaller maximum reflex gain to avoid instability. As differential reflex gain increased, there was a small increase in acceptable reflex delay. However, differential reflex gain with values near intrinsic damping caused the delay margin to approach zero. Forward-dynamic simulations of the fully nonlinear time-delayed system verified the linear results. The linear methods accurately found the delay margin below which the nonlinear system was asymptotically stable. These methods may aid future investigations in the role of reflexes in musculoskeletal stability.

  16. Impulsive effect on global exponential stability of BAM fuzzy cellular neural networks with time-varying delays

    Science.gov (United States)

    Li, Kelin

    2010-02-01

    In this article, a class of impulsive bidirectional associative memory (BAM) fuzzy cellular neural networks (FCNNs) with time-varying delays is formulated and investigated. By employing delay differential inequality and M-matrix theory, some sufficient conditions ensuring the existence, uniqueness and global exponential stability of equilibrium point for impulsive BAM FCNNs with time-varying delays are obtained. In particular, a precise estimate of the exponential convergence rate is also provided, which depends on system parameters and impulsive perturbation intention. It is believed that these results are significant and useful for the design and applications of BAM FCNNs. An example is given to show the effectiveness of the results obtained here.

  17. Stability and Bifurcation Analysis in a Maglev System with Multiple Delays

    Science.gov (United States)

    Zhang, Lingling; Huang, Jianhua; Huang, Lihong; Zhang, Zhizhou

    This paper considers the time-delayed feedback control for Maglev system with two discrete time delays. We determine constraints on the feedback time delays which ensure the stability of the Maglev system. An algorithm is developed for drawing a two-parametric bifurcation diagram with respect to two delays τ1 and τ2. Direction and stability of periodic solutions are also determined using the normal form method and center manifold theory by Hassard. The complex dynamical behavior of the Maglev system near the domain of stability is confirmed by exhaustive numerical simulation.

  18. Global exponential stability of BAM neural networks with time-varying delays and diffusion terms

    International Nuclear Information System (INIS)

    Wan Li; Zhou Qinghua

    2007-01-01

    The stability property of bidirectional associate memory (BAM) neural networks with time-varying delays and diffusion terms are considered. By using the method of variation parameter and inequality technique, the delay-independent sufficient conditions to guarantee the uniqueness and global exponential stability of the equilibrium solution of such networks are established

  19. Global exponential stability of BAM neural networks with time-varying delays and diffusion terms

    Science.gov (United States)

    Wan, Li; Zhou, Qinghua

    2007-11-01

    The stability property of bidirectional associate memory (BAM) neural networks with time-varying delays and diffusion terms are considered. By using the method of variation parameter and inequality technique, the delay-independent sufficient conditions to guarantee the uniqueness and global exponential stability of the equilibrium solution of such networks are established.

  20. Global exponential stability of bidirectional associative memory neural networks with distributed delays

    Science.gov (United States)

    Song, Qiankun; Cao, Jinde

    2007-05-01

    A bidirectional associative memory neural network model with distributed delays is considered. By constructing a new Lyapunov functional, employing the homeomorphism theory, M-matrix theory and the inequality (a[greater-or-equal, slanted]0,bk[greater-or-equal, slanted]0,qk>0 with , and r>1), a sufficient condition is obtained to ensure the existence, uniqueness and global exponential stability of the equilibrium point for the model. Moreover, the exponential converging velocity index is estimated, which depends on the delay kernel functions and the system parameters. The results generalize and improve the earlier publications, and remove the usual assumption that the activation functions are bounded . Two numerical examples are given to show the effectiveness of the obtained results.

  1. Bifurcation and stability of an improved time-delayed fluid flow model in internet congestion control

    International Nuclear Information System (INIS)

    Yu-Liang, Liu; Jie, Zhu; Xiao-Shu, Luo

    2009-01-01

    Based on the fluid flow time-delayed model proposed by Misra et al in internet congestion control, one modified time-delayed model is presented, where the influence of the communication delay on the router queue length is investigated in detail. The main advantage of the new model is that its stability domain is larger even without an extra controller. By linear stability analysis and numerical simulation, the effectiveness and feasibility of the novel model in internet congestion control are verified

  2. Bifurcation and stability of an improved time-delayed fluid flow model in internet congestion control

    Science.gov (United States)

    Liu, Yu-Liang; Zhu, Jie; Luo, Xiao-Shu

    2009-09-01

    Based on the fluid flow time-delayed model proposed by Misra et al in internet congestion control, one modified time-delayed model is presented, where the influence of the communication delay on the router queue length is investigated in detail. The main advantage of the new model is that its stability domain is larger even without an extra controller. By linear stability analysis and numerical simulation, the effectiveness and feasibility of the novel model in internet congestion control are verified.

  3. Global robust stability of delayed neural networks: Estimating upper limit of norm of delayed connection weight matrix

    International Nuclear Information System (INIS)

    Singh, Vimal

    2007-01-01

    The question of estimating the upper limit of -parallel B -parallel 2 , which is a key step in some recently reported global robust stability criteria for delayed neural networks, is revisited ( B denotes the delayed connection weight matrix). Recently, Cao, Huang, and Qu have given an estimate of the upper limit of -parallel B -parallel 2 . In the present paper, an alternative estimate of the upper limit of -parallel B -parallel 2 is highlighted. It is shown that the alternative estimate may yield some new global robust stability results

  4. Finite-Time Stabilization and Adaptive Control of Memristor-Based Delayed Neural Networks.

    Science.gov (United States)

    Wang, Leimin; Shen, Yi; Zhang, Guodong

    Finite-time stability problem has been a hot topic in control and system engineering. This paper deals with the finite-time stabilization issue of memristor-based delayed neural networks (MDNNs) via two control approaches. First, in order to realize the stabilization of MDNNs in finite time, a delayed state feedback controller is proposed. Then, a novel adaptive strategy is applied to the delayed controller, and finite-time stabilization of MDNNs can also be achieved by using the adaptive control law. Some easily verified algebraic criteria are derived to ensure the stabilization of MDNNs in finite time, and the estimation of the settling time functional is given. Moreover, several finite-time stability results as our special cases for both memristor-based neural networks (MNNs) without delays and neural networks are given. Finally, three examples are provided for the illustration of the theoretical results.Finite-time stability problem has been a hot topic in control and system engineering. This paper deals with the finite-time stabilization issue of memristor-based delayed neural networks (MDNNs) via two control approaches. First, in order to realize the stabilization of MDNNs in finite time, a delayed state feedback controller is proposed. Then, a novel adaptive strategy is applied to the delayed controller, and finite-time stabilization of MDNNs can also be achieved by using the adaptive control law. Some easily verified algebraic criteria are derived to ensure the stabilization of MDNNs in finite time, and the estimation of the settling time functional is given. Moreover, several finite-time stability results as our special cases for both memristor-based neural networks (MNNs) without delays and neural networks are given. Finally, three examples are provided for the illustration of the theoretical results.

  5. Periodic solution for state-dependent impulsive shunting inhibitory CNNs with time-varying delays.

    Science.gov (United States)

    Şaylı, Mustafa; Yılmaz, Enes

    2015-08-01

    In this paper, we consider existence and global exponential stability of periodic solution for state-dependent impulsive shunting inhibitory cellular neural networks with time-varying delays. By means of B-equivalence method, we reduce these state-dependent impulsive neural networks system to an equivalent fix time impulsive neural networks system. Further, by using Mawhin's continuation theorem of coincide degree theory and employing a suitable Lyapunov function some new sufficient conditions for existence and global exponential stability of periodic solution are obtained. Previous results are improved and extended. Finally, we give an illustrative example with numerical simulations to demonstrate the effectiveness of our theoretical results. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Delay discounting of oral morphine and sweetened juice rewards in dependent and non-dependent rats.

    Science.gov (United States)

    Harvey-Lewis, Colin; Perdrizet, Johnna; Franklin, Keith B J

    2014-07-01

    Opioid-dependent humans are reported to show accelerated delay discounting of opioid rewards when compared to monetary rewards. It has been suggested that this may reflect a difference in discounting of consumable and non-consumable goods not specific to dependent individuals. Here, we evaluate the discounting of similar morphine and non-morphine oral rewards in dependent and non-dependent rats We first tested the analgesic and rewarding effects of our morphine solution. In a second experiment, we assigned rats randomly to either dependent or non-dependent groups that, 30 min after daily testing, received 30 mg/kg subcutaneous dose of morphine, or saline, respectively. Delay discounting of drug-free reward was examined prior to initiation of the dosing regimen. We tested discounting of the morphine reward in half the rats and retested the discounting of the drug-free reward in the other half. All tests were run 22.5 h after the daily maintenance dose. Rats preferred the morphine cocktail to the drug-free solution and consumed enough to induce significant analgesia. The control quinine solution did not produce these effects. Dependent rats discounted morphine rewards more rapidly than before dependence and when compared to discounting drug-free rewards. In non-dependent rats both reward types were discounted similarly. These results show that morphine dependence increases impulsiveness specifically towards a drug reward while morphine experience without dependence does not.

  7. LMI optimization approach to stabilization of time-delay chaotic systems

    International Nuclear Information System (INIS)

    Park, Ju H.; Kwon, O.M.

    2005-01-01

    Based on the Lyapunov stability theory and linear matrix inequality (LMI) technique, this paper proposes a novel control method for stabilization of a class of time-delay chaotic systems. A stabilization criterion is derived in terms of LMIs which can be easily solved by efficient convex optimization algorithms. A numerical example is included to show the advantage of the result derived

  8. Stability and bifurcation analysis of a generalized scalar delay differential equation.

    Science.gov (United States)

    Bhalekar, Sachin

    2016-08-01

    This paper deals with the stability and bifurcation analysis of a general form of equation D(α)x(t)=g(x(t),x(t-τ)) involving the derivative of order α ∈ (0, 1] and a constant delay τ ≥ 0. The stability of equilibrium points is presented in terms of the stability regions and critical surfaces. We provide a necessary condition to exist chaos in the system also. A wide range of delay differential equations involving a constant delay can be analyzed using the results proposed in this paper. The illustrative examples are provided to explain the theory.

  9. Stabilizing embedology: Geometry-preserving delay-coordinate maps

    Science.gov (United States)

    Eftekhari, Armin; Yap, Han Lun; Wakin, Michael B.; Rozell, Christopher J.

    2018-02-01

    Delay-coordinate mapping is an effective and widely used technique for reconstructing and analyzing the dynamics of a nonlinear system based on time-series outputs. The efficacy of delay-coordinate mapping has long been supported by Takens' embedding theorem, which guarantees that delay-coordinate maps use the time-series output to provide a reconstruction of the hidden state space that is a one-to-one embedding of the system's attractor. While this topological guarantee ensures that distinct points in the reconstruction correspond to distinct points in the original state space, it does not characterize the quality of this embedding or illuminate how the specific parameters affect the reconstruction. In this paper, we extend Takens' result by establishing conditions under which delay-coordinate mapping is guaranteed to provide a stable embedding of a system's attractor. Beyond only preserving the attractor topology, a stable embedding preserves the attractor geometry by ensuring that distances between points in the state space are approximately preserved. In particular, we find that delay-coordinate mapping stably embeds an attractor of a dynamical system if the stable rank of the system is large enough to be proportional to the dimension of the attractor. The stable rank reflects the relation between the sampling interval and the number of delays in delay-coordinate mapping. Our theoretical findings give guidance to choosing system parameters, echoing the tradeoff between irrelevancy and redundancy that has been heuristically investigated in the literature. Our initial result is stated for attractors that are smooth submanifolds of Euclidean space, with extensions provided for the case of strange attractors.

  10. Novel criteria for global exponential periodicity and stability of recurrent neural networks with time-varying delays

    International Nuclear Information System (INIS)

    Song Qiankun

    2008-01-01

    In this paper, the global exponential periodicity and stability of recurrent neural networks with time-varying delays are investigated by applying the idea of vector Lyapunov function, M-matrix theory and inequality technique. We assume neither the global Lipschitz conditions on these activation functions nor the differentiability on these time-varying delays, which were needed in other papers. Several novel criteria are found to ascertain the existence, uniqueness and global exponential stability of periodic solution for recurrent neural network with time-varying delays. Moreover, the exponential convergence rate index is estimated, which depends on the system parameters. Some previous results are improved and generalized, and an example is given to show the effectiveness of our method

  11. Delay-enhanced stability and stochastic resonance in perception bistability under non-Gaussian noise

    International Nuclear Information System (INIS)

    Yang, Tao; Zeng, Chunhua; Liu, Ruifen; Wang, Hua; Mei, Dongcheng

    2015-01-01

    In this paper we investigate the effect of time delay in an attractor network model of perception bistability driven by non-Gaussian noise. Using delay Langevin and Fokker–Planck approaches, the theoretical analysis of the model is presented. It is found that the mean first-passage time (MFPT) as a function of the time delay exhibits a maximum, which is identified as the characteristic of the delay-enhanced stability of the system. This is different to the case of noise-enhanced stability. The non-Gaussian noise-enhanced stability of the system is also analyzed. The signal-to-noise ratio (SNR) as a function of the noise intensity exhibits a maximum. This maximum implies the identifying characteristic of stochastic resonance (SR), and the time delay and non-Gaussian noise can enhance the SR phenomenon. (paper)

  12. Delay induced stability switch, multitype bistability and chaos in an intraguild predation model.

    Science.gov (United States)

    Shu, Hongying; Hu, Xi; Wang, Lin; Watmough, James

    2015-12-01

    In many predator-prey models, delay has a destabilizing effect and induces oscillations; while in many competition models, delay does not induce oscillations. By analyzing a rather simple delayed intraguild predation model, which combines both the predator-prey relation and competition, we show that delay in intraguild predation models promotes very complex dynamics. The delay can induce stability switches exhibiting a destabilizing role as well as a stabilizing role. It is shown that three types of bistability are possible: one stable equilibrium coexists with another stable equilibrium (node-node bistability); one stable equilibrium coexists with a stable periodic solution (node-cycle bistability); one stable periodic solution coexists with another stable periodic solution (cycle-cycle bistability). Numerical simulations suggest that delay can also induce chaos in intraguild predation models.

  13. Exponential stability of uncertain stochastic neural networks with mixed time-delays

    International Nuclear Information System (INIS)

    Wang Zidong; Lauria, Stanislao; Fang Jian'an; Liu Xiaohui

    2007-01-01

    This paper is concerned with the global exponential stability analysis problem for a class of stochastic neural networks with mixed time-delays and parameter uncertainties. The mixed delays comprise discrete and distributed time-delays, the parameter uncertainties are norm-bounded, and the neural networks are subjected to stochastic disturbances described in terms of a Brownian motion. The purpose of the stability analysis problem is to derive easy-to-test criteria under which the delayed stochastic neural network is globally, robustly, exponentially stable in the mean square for all admissible parameter uncertainties. By resorting to the Lyapunov-Krasovskii stability theory and the stochastic analysis tools, sufficient stability conditions are established by using an efficient linear matrix inequality (LMI) approach. The proposed criteria can be checked readily by using recently developed numerical packages, where no tuning of parameters is required. An example is provided to demonstrate the usefulness of the proposed criteria

  14. The influences of delay time on the stability of a market model with stochastic volatility

    Science.gov (United States)

    Li, Jiang-Cheng; Mei, Dong-Cheng

    2013-02-01

    The effects of the delay time on the stability of a market model are investigated, by using a modified Heston model with a cubic nonlinearity and cross-correlated noise sources. These results indicate that: (i) There is an optimal delay time τo which maximally enhances the stability of the stock price under strong demand elasticity of stock price, and maximally reduces the stability of the stock price under weak demand elasticity of stock price; (ii) The cross correlation coefficient of noises and the delay time play an opposite role on the stability for the case of the delay time τo. Moreover, the probability density function of the escape time of stock price returns, the probability density function of the returns and the correlation function of the returns are compared with other literatures.

  15. Globally exponential stability of neural network with constant and variable delays

    International Nuclear Information System (INIS)

    Zhao Weirui; Zhang Huanshui

    2006-01-01

    This Letter presents new sufficient conditions of globally exponential stability of neural networks with delays. We show that these results generalize recently published globally exponential stability results. In particular, several different globally exponential stability conditions in the literatures which were proved using different Lyapunov functionals are generalized and unified by using the same Lyapunov functional and the technique of inequality of integral. A comparison between our results and the previous results admits that our results establish a new set of stability criteria for delayed neural networks. Those conditions are less restrictive than those given in the earlier references

  16. Global robust stability for shunting inhibitory CNNs with delays.

    Science.gov (United States)

    Wang, Lingna; Lin, Yiping

    2004-08-01

    In this paper, the problem of global robust stability for shunting inhibitory cellular neural networks (SICNNs) is studied. A sufficient condition guaranteeing the network's global robust stability is established. The result can easily be used to verify globally robust stable networks. An example is given to illustrate that the conditions of our results are feasible.

  17. Impulsive effects on global asymptotic stability of delay BAM neural networks

    International Nuclear Information System (INIS)

    Chen Jun; Cui Baotong

    2008-01-01

    Based on the proper Lyapunov functions and the Jacobsthal liner inequality, some sufficient conditions are presented in this paper for global asymptotic stability of delay bidirectional associative memory neural networks with impulses. The obtained results are independently of the delay parameters and can be easily verified. Also, some remarks and an illustrative example are given to demonstrate the effectiveness of the obtained results

  18. Global exponential stability of reaction-diffusion recurrent neural networks with time-varying delays

    International Nuclear Information System (INIS)

    Liang Jinling; Cao Jinde

    2003-01-01

    Employing general Halanay inequality, we analyze the global exponential stability of a class of reaction-diffusion recurrent neural networks with time-varying delays. Several new sufficient conditions are obtained to ensure existence, uniqueness and global exponential stability of the equilibrium point of delayed reaction-diffusion recurrent neural networks. The results extend and improve the earlier publications. In addition, an example is given to show the effectiveness of the obtained result

  19. Global exponential stability of mixed discrete and distributively delayed cellular neural network

    International Nuclear Information System (INIS)

    Yao Hong-Xing; Zhou Jia-Yan

    2011-01-01

    This paper concernes analysis for the global exponential stability of a class of recurrent neural networks with mixed discrete and distributed delays. It first proves the existence and uniqueness of the balance point, then by employing the Lyapunov—Krasovskii functional and Young inequality, it gives the sufficient condition of global exponential stability of cellular neural network with mixed discrete and distributed delays, in addition, the example is provided to illustrate the applicability of the result. (general)

  20. Exponential p-stability of impulsive stochastic differential equations with delays

    International Nuclear Information System (INIS)

    Yang Zhiguo; Xu Daoyi; Xiang Li

    2006-01-01

    In this Letter, we establish a method to study the exponential p-stability of the zero solution of impulsive stochastic differential equations with delays. By establishing an L-operator inequality and using the properties of M-cone and stochastic analysis technique, we obtain some new conditions ensuring the exponential p-stability of the zero solution of impulsive stochastic differential equations with delays. Two illustrative examples have been provided to show the effectiveness of our results

  1. Globally exponential stability and periodic solutions of CNNS with variable coefficients and variable delays

    International Nuclear Information System (INIS)

    Liu Haifei; Wang Li

    2006-01-01

    In this Letter, by using the inequality method and the Lyapunov functional method, we analyze the globally exponential stability and the existence of periodic solutions of a class of cellular neutral networks with delays and variable coefficients. Some simple and new sufficient conditions ensuring the existence and uniqueness of globally exponential stability of periodic solutions for cellular neutral networks with variable coefficients and delays are obtained. In addition, one example is also worked out to illustrate our theory

  2. Global robust stability of bidirectional associative memory neural networks with multiple time delays.

    Science.gov (United States)

    Senan, Sibel; Arik, Sabri

    2007-10-01

    This correspondence presents a sufficient condition for the existence, uniqueness, and global robust asymptotic stability of the equilibrium point for bidirectional associative memory neural networks with discrete time delays. The results impose constraint conditions on the network parameters of the neural system independently of the delay parameter, and they are applicable to all bounded continuous nonmonotonic neuron activation functions. Some numerical examples are given to compare our results with the previous robust stability results derived in the literature.

  3. Global exponential stability for reaction-diffusion recurrent neural networks with multiple time varying delays

    International Nuclear Information System (INIS)

    Lou, X.; Cui, B.

    2008-01-01

    In this paper we consider the problem of exponential stability for recurrent neural networks with multiple time varying delays and reaction-diffusion terms. The activation functions are supposed to be bounded and globally Lipschitz continuous. By means of Lyapunov functional, sufficient conditions are derived, which guarantee global exponential stability of the delayed neural network. Finally, a numerical example is given to show the correctness of our analysis. (author)

  4. Mittag-Leffler Stability Theorem for Fractional Nonlinear Systems with Delay

    Directory of Open Access Journals (Sweden)

    S. J. Sadati

    2010-01-01

    Full Text Available Fractional calculus started to play an important role for analysis of the evolution of the nonlinear dynamical systems which are important in various branches of science and engineering. In this line of taught in this paper we studied the stability of fractional order nonlinear time-delay systems for Caputo's derivative, and we proved two theorems for Mittag-Leffler stability of the fractional nonlinear time delay systems.

  5. Globally exponential stability and periodic solutions of CNNS with variable coefficients and variable delays

    Energy Technology Data Exchange (ETDEWEB)

    Liu Haifei [School of Management and Engineering, Nanjing University, Nanjing 210093 (China)]. E-mail: hfliu80@126.com; Wang Li [School of Management and Engineering, Nanjing University, Nanjing 210093 (China)

    2006-09-15

    In this Letter, by using the inequality method and the Lyapunov functional method, we analyze the globally exponential stability and the existence of periodic solutions of a class of cellular neutral networks with delays and variable coefficients. Some simple and new sufficient conditions ensuring the existence and uniqueness of globally exponential stability of periodic solutions for cellular neutral networks with variable coefficients and delays are obtained. In addition, one example is also worked out to illustrate our theory.

  6. Constructing Hopf bifurcation lines for the stability of nonlinear systems with two time delays

    Science.gov (United States)

    Nguimdo, Romain Modeste

    2018-03-01

    Although the plethora real-life systems modeled by nonlinear systems with two independent time delays, the algebraic expressions for determining the stability of their fixed points remain the Achilles' heel. Typically, the approach for studying the stability of delay systems consists in finding the bifurcation lines separating the stable and unstable parameter regions. This work deals with the parametric construction of algebraic expressions and their use for the determination of the stability boundaries of fixed points in nonlinear systems with two independent time delays. In particular, we concentrate on the cases for which the stability of the fixed points can be ascertained from a characteristic equation corresponding to that of scalar two-delay differential equations, one-component dual-delay feedback, or nonscalar differential equations with two delays for which the characteristic equation for the stability analysis can be reduced to that of a scalar case. Then, we apply our obtained algebraic expressions to identify either the parameter regions of stable microwaves generated by dual-delay optoelectronic oscillators or the regions of amplitude death in identical coupled oscillators.

  7. Bioavailability and stability of erythromycin delayed release tablets.

    Science.gov (United States)

    Ogwal, S; Xide, T U

    2001-12-01

    Erythromycin is available as the free base, ethylsuccinate, estolate, stearate, gluceptate, and lactobionate derivatives. When given orally erythromycin and its derivatives except the estolate are inactivated to some extent by the gastric acid and poor absorption may result. To establish whether delayed release erythromycin tablets meet the bioequivalent requirement for the market. Sectrophotometric analysis was used to determine the dissolution percentage of the tablets in vitro. High performance liquid chromatography and IBM/XT microcomputer was used to determine the bioavailability and pharmacokinetic parameters in vivo. Dissolution percentage in thirty minutes reached 28.9% and in sixty minutes erythromycin was completely released. The parameters of the delayed release tablets were Tlag 2.3 hr, Tmax.4.5 hr, and Cmax 2.123 g/ml Ka 0.38048 hr(-1) T (1/2) 1.8 hr, V*C/F 49.721 AUC 12.9155. The relative bioavailability of erythromycin delayed release tablet to erythromycin capsules was 105.31% The content, appearance, and dissolution bioavailability of delayed release erythromycin tablets conforms to the United States pharmacopoeia standards. The tablets should be stored in a cool and dry place in airtight containers and the shelf life is temporarily assigned two years.

  8. Stability Criteria for Differential Equations with Variable Time Delays

    Science.gov (United States)

    Schley, D.; Shail, R.; Gourley, S. A.

    2002-01-01

    Time delays are an important aspect of mathematical modelling, but often result in highly complicated equations which are difficult to treat analytically. In this paper it is shown how careful application of certain undergraduate tools such as the Method of Steps and the Principle of the Argument can yield significant results. Certain delay…

  9. Robust stability analysis for Markovian jumping interval neural networks with discrete and distributed time-varying delays

    International Nuclear Information System (INIS)

    Balasubramaniam, P.; Lakshmanan, S.; Manivannan, A.

    2012-01-01

    Highlights: ► Robust stability analysis for Markovian jumping interval neural networks is considered. ► Both linear fractional and interval uncertainties are considered. ► A new LKF is constructed with triple integral terms. ► MATLAB LMI control toolbox is used to validate theoretical results. ► Numerical examples are given to illustrate the effectiveness of the proposed method. - Abstract: This paper investigates robust stability analysis for Markovian jumping interval neural networks with discrete and distributed time-varying delays. The parameter uncertainties are assumed to be bounded in given compact sets. The delay is assumed to be time-varying and belong to a given interval, which means that the lower and upper bounds of interval time-varying delays are available. Based on the new Lyapunov–Krasovskii functional (LKF), some inequality techniques and stochastic stability theory, new delay-dependent stability criteria have been obtained in terms of linear matrix inequalities (LMIs). Finally, two numerical examples are given to illustrate the less conservative and effectiveness of our theoretical results.

  10. Stability Analysis of Networked Control Systems with Random Time Delays and Packet Dropouts Modeled by Markov Chains

    Directory of Open Access Journals (Sweden)

    Li Qiu

    2013-01-01

    unified Markov jump model. The random time delays and packet dropouts existed in feedback communication link are modeled by two independent Markov chains; the resulting closed-loop system is described by a new Markovian jump linear system (MJLS with Markov delays. Sufficient conditions of the stochastic stability for NCSs is obtained by constructing a novel Lyapunov functional, and the mode-dependent output feedback controller design method is presented based on linear matrix inequality (LMI technique. A numerical example is given to illustrate the effectiveness of the proposed method.

  11. Robust Stability Analysis of Neutral-Type Hybrid Bidirectional Associative Memory Neural Networks with Time-Varying Delays

    Directory of Open Access Journals (Sweden)

    Wei Feng

    2014-01-01

    Full Text Available The global asymptotic robust stability of equilibrium is considered for neutral-type hybrid bidirectional associative memory neural networks with time-varying delays and parameters uncertainties. The results we obtained in this paper are delay-derivative-dependent and establish various relationships between the network parameters only. Therefore, the results of this paper are applicable to a larger class of neural networks and can be easily verified when compared with the previously reported literature results. Two numerical examples are illustrated to verify our results.

  12. Global Asymptotic Stability of Impulsive CNNs with Proportional Delays and Partially Lipschitz Activation Functions

    Directory of Open Access Journals (Sweden)

    Xueli Song

    2014-01-01

    Full Text Available This paper researches global asymptotic stability of impulsive cellular neural networks with proportional delays and partially Lipschitz activation functions. Firstly, by means of the transformation vi(t=ui(et, the impulsive cellular neural networks with proportional delays are transformed into impulsive cellular neural networks with the variable coefficients and constant delays. Secondly, we provide novel criteria for the uniqueness and exponential stability of the equilibrium point of the latter by relative nonlinear measure and prove that the exponential stability of equilibrium point of the latter implies the asymptotic stability of one of the former. We furthermore obtain a sufficient condition to the uniqueness and global asymptotic stability of the equilibrium point of the former. Our method does not require conventional assumptions on global Lipschitz continuity, boundedness, and monotonicity of activation functions. Our results are generalizations and improvements of some existing ones. Finally, an example and its simulations are provided to illustrate the correctness of our analysis.

  13. A delay-dependent LMI approach to dynamics analysis of discrete-time recurrent neural networks with time-varying delays

    International Nuclear Information System (INIS)

    Song, Qiankun; Wang, Zidong

    2007-01-01

    In this Letter, the analysis problem for the existence and stability of periodic solutions is investigated for a class of general discrete-time recurrent neural networks with time-varying delays. For the neural networks under study, a generalized activation function is considered, and the traditional assumptions on the boundedness, monotony and differentiability of the activation functions are removed. By employing the latest free-weighting matrix method, an appropriate Lyapunov-Krasovskii functional is constructed and several sufficient conditions are established to ensure the existence, uniqueness, and globally exponential stability of the periodic solution for the addressed neural network. The conditions are dependent on both the lower bound and upper bound of the time-varying time delays. Furthermore, the conditions are expressed in terms of the linear matrix inequalities (LMIs), which can be checked numerically using the effective LMI toolbox in MATLAB. Two simulation examples are given to show the effectiveness and less conservatism of the proposed criteria

  14. Stability and Hopf Bifurcation for a Delayed SLBRS Computer Virus Model

    Directory of Open Access Journals (Sweden)

    Zizhen Zhang

    2014-01-01

    Full Text Available By incorporating the time delay due to the period that computers use antivirus software to clean the virus into the SLBRS model a delayed SLBRS computer virus model is proposed in this paper. The dynamical behaviors which include local stability and Hopf bifurcation are investigated by regarding the delay as bifurcating parameter. Specially, direction and stability of the Hopf bifurcation are derived by applying the normal form method and center manifold theory. Finally, an illustrative example is also presented to testify our analytical results.

  15. Global exponential stability of fuzzy cellular neural networks with delays and reaction-diffusion terms

    International Nuclear Information System (INIS)

    Wang Jian; Lu Junguo

    2008-01-01

    In this paper, we study the global exponential stability of fuzzy cellular neural networks with delays and reaction-diffusion terms. By constructing a suitable Lyapunov functional and utilizing some inequality techniques, we obtain a sufficient condition for the uniqueness and global exponential stability of the equilibrium solution for a class of fuzzy cellular neural networks with delays and reaction-diffusion terms. The result imposes constraint conditions on the network parameters independently of the delay parameter. The result is also easy to check and plays an important role in the design and application of globally exponentially stable fuzzy neural circuits

  16. Stability and Hopf bifurcation for a delayed SLBRS computer virus model.

    Science.gov (United States)

    Zhang, Zizhen; Yang, Huizhong

    2014-01-01

    By incorporating the time delay due to the period that computers use antivirus software to clean the virus into the SLBRS model a delayed SLBRS computer virus model is proposed in this paper. The dynamical behaviors which include local stability and Hopf bifurcation are investigated by regarding the delay as bifurcating parameter. Specially, direction and stability of the Hopf bifurcation are derived by applying the normal form method and center manifold theory. Finally, an illustrative example is also presented to testify our analytical results.

  17. The global stability of a delayed predator-prey system with two stage-structure

    International Nuclear Information System (INIS)

    Wang Fengyan; Pang Guoping

    2009-01-01

    Based on the classical delayed stage-structured model and Lotka-Volterra predator-prey model, we introduce and study a delayed predator-prey system, where prey and predator have two stages, an immature stage and a mature stage. The time delays are the time lengths between the immature's birth and maturity of prey and predator species. Results on global asymptotic stability of nonnegative equilibria of the delay system are given, which generalize and suggest that good continuity exists between the predator-prey system and its corresponding stage-structured system.

  18. A new criterion for global robust stability of interval neural networks with discrete time delays

    International Nuclear Information System (INIS)

    Li Chuandong; Chen Jinyu; Huang Tingwen

    2007-01-01

    This paper further studies global robust stability of a class of interval neural networks with discrete time delays. By introducing an equivalent transformation of interval matrices, a new criterion on global robust stability is established. In comparison with the results reported in the literature, the proposed approach leads to results with less restrictive conditions. Numerical examples are also worked through to illustrate our results

  19. Almost sure exponential stability of stochastic fuzzy cellular neural networks with delays

    International Nuclear Information System (INIS)

    Zhao Hongyong; Ding Nan; Chen Ling

    2009-01-01

    This paper is concerned with the problem of exponential stability analysis for fuzzy cellular neural network with delays. By constructing suitable Lyapunov functional and using stochastic analysis we present some sufficient conditions ensuring almost sure exponential stability for the network. Moreover, an example is given to demonstrate the advantages of our method.

  20. Global Stability of Complex-Valued Genetic Regulatory Networks with Delays on Time Scales

    Directory of Open Access Journals (Sweden)

    Wang Yajing

    2016-01-01

    Full Text Available In this paper, the global exponential stability of complex-valued genetic regulatory networks with delays is investigated. Besides presenting conditions guaranteeing the existence of a unique equilibrium pattern, its global exponential stability is discussed. Some numerical examples for different time scales.

  1. Stability and Hopf bifurcations in a competitive Lotka-Volterra system with two delays

    International Nuclear Information System (INIS)

    Song Yongli; Han Maoan; Peng Yahong

    2004-01-01

    We consider a Lotka-Volterra competition system with two delays. We first investigate the stability of the positive equilibrium and the existence of Hopf bifurcations, and then using the normal form theory and center manifold argument, derive the explicit formulas which determine the stability, direction and other properties of bifurcating periodic solutions

  2. Stability of Nonlinear Systems with Unknown Time-varying Feedback Delay

    Science.gov (United States)

    Chunodkar, Apurva A.; Akella, Maruthi R.

    2013-12-01

    This paper considers the problem of stabilizing a class of nonlinear systems with unknown bounded delayed feedback wherein the time-varying delay is 1) piecewise constant 2) continuous with a bounded rate. We also consider application of these results to the stabilization of rigid-body attitude dynamics. In the first case, the time-delay in feedback is modeled specifically as a switch among an arbitrarily large set of unknown constant values with a known strict upper bound. The feedback is a linear function of the delayed states. In the case of linear systems with switched delay feedback, a new sufficiency condition for average dwell time result is presented using a complete type Lyapunov-Krasovskii (L-K) functional approach. Further, the corresponding switched system with nonlinear perturbations is proven to be exponentially stable inside a well characterized region of attraction for an appropriately chosen average dwell time. In the second case, the concept of the complete type L-K functional is extended to a class of nonlinear time-delay systems with unknown time-varying time-delay. This extension ensures stability robustness to time-delay in the control design for all values of time-delay less than the known upper bound. Model-transformation is used in order to partition the nonlinear system into a nominal linear part that is exponentially stable with a bounded perturbation. We obtain sufficient conditions which ensure exponential stability inside a region of attraction estimate. A constructive method to evaluate the sufficient conditions is presented together with comparison with the corresponding constant and piecewise constant delay. Numerical simulations are performed to illustrate the theoretical results of this paper.

  3. Analysis of stability and Hopf bifurcation for a viral infectious model with delay

    International Nuclear Information System (INIS)

    Sun Chengjun; Cao Zhijie; Lin Yiping

    2007-01-01

    In this paper, a four-dimensional viral infectious model with delay is considered. The stability of the two equilibria and the existence of Hopf bifurcation are investigated. It is found that there are stability switches and Hopf bifurcations occur when the delay τ passes through a sequence of critical values. Using the normal form theory and center manifold argument [Hassard B, Kazarino D, Wan Y. Theory and applications of Hopf bifurcation. Cambridge: Cambridge University Press; 1981], the explicit formulaes which determine the stability, the direction and the period of bifurcating periodic solutions are derived. Numerical simulations are carried out to illustrate the validity of the main results

  4. New results on global exponential stability of recurrent neural networks with time-varying delays

    International Nuclear Information System (INIS)

    Xu Shengyuan; Chu Yuming; Lu Junwei

    2006-01-01

    This Letter provides new sufficient conditions for the existence, uniqueness and global exponential stability of the equilibrium point of recurrent neural networks with time-varying delays by employing Lyapunov functions and using the Halanay inequality. The time-varying delays are not necessarily differentiable. Both Lipschitz continuous activation functions and monotone nondecreasing activation functions are considered. The derived stability criteria are expressed in terms of linear matrix inequalities (LMIs), which can be checked easily by resorting to recently developed algorithms solving LMIs. Furthermore, the proposed stability results are less conservative than some previous ones in the literature, which is demonstrated via some numerical examples

  5. New results on global exponential stability of recurrent neural networks with time-varying delays

    Energy Technology Data Exchange (ETDEWEB)

    Xu Shengyuan [Department of Automation, Nanjing University of Science and Technology, Nanjing 210094 (China)]. E-mail: syxu02@yahoo.com.cn; Chu Yuming [Department of Mathematics, Huzhou Teacher' s College, Huzhou, Zhejiang 313000 (China); Lu Junwei [School of Electrical and Automation Engineering, Nanjing Normal University, 78 Bancang Street, Nanjing, 210042 (China)

    2006-04-03

    This Letter provides new sufficient conditions for the existence, uniqueness and global exponential stability of the equilibrium point of recurrent neural networks with time-varying delays by employing Lyapunov functions and using the Halanay inequality. The time-varying delays are not necessarily differentiable. Both Lipschitz continuous activation functions and monotone nondecreasing activation functions are considered. The derived stability criteria are expressed in terms of linear matrix inequalities (LMIs), which can be checked easily by resorting to recently developed algorithms solving LMIs. Furthermore, the proposed stability results are less conservative than some previous ones in the literature, which is demonstrated via some numerical examples.

  6. A heterogenous Cournot duopoly with delay dynamics: Hopf bifurcations and stability switching curves

    Science.gov (United States)

    Pecora, Nicolò; Sodini, Mauro

    2018-05-01

    This article considers a Cournot duopoly model in a continuous-time framework and analyze its dynamic behavior when the competitors are heterogeneous in determining their output decision. Specifically the model is expressed in the form of differential equations with discrete delays. The stability conditions of the unique Nash equilibrium of the system are determined and the emergence of Hopf bifurcations is shown. Applying some recent mathematical techniques (stability switching curves) and performing numerical simulations, the paper confirms how different time delays affect the stability of the economy.

  7. Stochastic stability analysis for delayed neural networks of neutral type with Markovian jump parameters

    International Nuclear Information System (INIS)

    Lou Xuyang; Cui Baotong

    2009-01-01

    In this paper, the problem of stochastic stability for a class of delayed neural networks of neutral type with Markovian jump parameters is investigated. The jumping parameters are modelled as a continuous-time, discrete-state Markov process. A sufficient condition guaranteeing the stochastic stability of the equilibrium point is derived for the Markovian jumping delayed neural networks (MJDNNs) with neutral type. The stability criterion not only eliminates the differences between excitatory and inhibitory effects on the neural networks, but also can be conveniently checked. The sufficient condition obtained can be essentially solved in terms of linear matrix inequality. A numerical example is given to show the effectiveness of the obtained results.

  8. Some criteria for robust stability of Cohen-Grossberg neural networks with delays

    International Nuclear Information System (INIS)

    Xiong Weili; Xu Baoguo

    2008-01-01

    This paper considers the problem of robust stability of Cohen-Grossberg neural networks with time-varying delays. Based on the Lyapunov stability theory and linear matrix inequality (LMI) technique, some sufficient conditions are derived to ensure the global robust convergence of the equilibrium point. The proposed LMI conditions can be checked easily by recently developed algorithms solving LMIs. Comparisons between our results and previous results admits our results establish a new set of stability criteria for delayed Cohen-Grossberg neural networks. Numerical examples are given to illustrate the effectiveness of our results

  9. An analysis of global robust stability of uncertain cellular neural networks with discrete and distributed delays

    International Nuclear Information System (INIS)

    Park, Ju H.

    2007-01-01

    This paper considers the robust stability analysis of cellular neural networks with discrete and distributed delays. Based on the Lyapunov stability theory and linear matrix inequality (LMI) technique, a novel stability criterion guaranteeing the global robust convergence of the equilibrium point is derived. The criterion can be solved easily by various convex optimization algorithms. An example is given to illustrate the usefulness of our results

  10. Stability with respect to initial time difference for generalized delay differential equations

    Directory of Open Access Journals (Sweden)

    Ravi Agarwal

    2015-02-01

    Full Text Available Stability with initial data difference for nonlinear delay differential equations is introduced. This type of stability generalizes the known concept of stability in the literature. It gives us the opportunity to compare the behavior of two nonzero solutions when both initial values and initial intervals are different. Several sufficient conditions for stability and for asymptotic stability with initial time difference are obtained. Lyapunov functions as well as comparison results for scalar ordinary differential equations are employed. Several examples are given to illustrate the theory.

  11. Aging-dependent reduction in glyoxalase 1 delays wound healing.

    Science.gov (United States)

    Fleming, Thomas H; Theilen, Till-Martin; Masania, Jinit; Wunderle, Marius; Karimi, Jamshid; Vittas, Spiros; Bernauer, Rainer; Bierhaus, Angelika; Rabbani, Naila; Thornalley, Paul J; Kroll, Jens; Tyedmers, Jens; Nawrotzki, Ralph; Herzig, Stephan; Brownlee, Michael; Nawroth, Peter P

    2013-01-01

    Methylglyoxal (MG), the major dicarbonyl substrate of the enzyme glyoxalase 1 (GLO1), is a reactive metabolite formed via glycolytic flux. Decreased GLO1 activity in situ has been shown to result in an accumulation of MG and increased formation of advanced glycation endproducts, both of which can accumulate during physiological aging and at an accelerated rate in diabetes and other chronic degenerative diseases. To determine the physiological consequences which result from elevated MG levels and the role of MG and GLO1 in aging, wound healing in young (≤12 weeks) and old (≥52 weeks) wild-type mice was studied. Old mice were found to have a significantly slower rate of wound healing compared to young mice (74.9 ± 2.2 vs. 55.4 ± 1.5% wound closure at day 6; 26% decrease; p wounds of young mice, decreased wound healing by 24% compared to untreated mice, whereas application of BSA modified minimally by MG had no effect. Treatment of either young or old mice with aminoguanidine, a scavenger of free MG, significantly increased wound closure by 16% (66.8 ± 1.6 vs. 77.2 ± 3.1%; p wound healing in the old mice was restored to the level observed in the young mice. These findings were confirmed in vitro, as MG reduced migration and proliferation of fibroblasts derived from young and old, wild-type mice. The data demonstrate that the balance between MG and age-dependent GLO1 downregulation contributes to delayed wound healing in old mice. Copyright © 2013 S. Karger AG, Basel.

  12. Wavelength dependent delay in the onset of FEL tissue ablation

    International Nuclear Information System (INIS)

    Tribble, J.A.; Edwards, G.S.; Lamb, J.A.

    1995-01-01

    We are investigating the wavelength dependence of the onset of laser tissue ablation in the IR Visible and UV ranges. Toward this end, we have made simultaneous measurements of the ejected material (using a HeNe probe beam tangential to the front surface) and the residual stress transient in the tissue (using traditional piezoelectric detection behind the thin samples). For the IR studies we have used the Vanderbilt FEL and for the UV and Vis range we have used a Q-switched ND:Yag with frequency doubling and quadrupling. To satisfy the conditions of the near field limit for the detection of the stress transient, the duration of the IR FEL macropulse must be as short as possible. We have obtained macropulses as short as 100 ns using Pockels Cell technology. The recording of the signals from both the photodiode monitoring the HeNe probe beam and the acoustic detector are synchronized with the arrival of the 100 ns macropulse. With subablative intensities, the resulting stress transient is bipolar with its positive peak separated from its negative peak by 100 ns in agreement with theory. Of particular interest is the comparison of ablative results using 3 μm and 6.45 μm pulses. Both the stress transient and the ejection of material suffer a greater delay (with respect to the arrival of the 100 ns pulse) when the FEL is tuned to 3 μm as compared to 6.45 μm. A comparison of IR Vis and UV data will be discussed in terms of microscopic mechanisms governing the laser ablation process

  13. Time-dependent solutions for stochastic systems with delays: Perturbation theory and applications to financial physics

    International Nuclear Information System (INIS)

    Frank, T.D.

    2006-01-01

    First-order approximations of time-dependent solutions are determined for stochastic systems perturbed by time-delayed feedback forces. To this end, the theory of delay Fokker-Planck equations is applied in combination with Bayes' theorem. Applications to a time-delayed Ornstein-Uhlenbeck process and the geometric Brownian walk of financial physics are discussed

  14. Delay-Dependent Exponential Optimal Synchronization for Nonidentical Chaotic Systems via Neural-Network-Based Approach

    Directory of Open Access Journals (Sweden)

    Feng-Hsiag Hsiao

    2013-01-01

    Full Text Available A novel approach is presented to realize the optimal exponential synchronization of nonidentical multiple time-delay chaotic (MTDC systems via fuzzy control scheme. A neural-network (NN model is first constructed for the MTDC system. Then, a linear differential inclusion (LDI state-space representation is established for the dynamics of the NN model. Based on this LDI state-space representation, a delay-dependent exponential stability criterion of the error system derived in terms of Lyapunov's direct method is proposed to guarantee that the trajectories of the slave system can approach those of the master system. Subsequently, the stability condition of this criterion is reformulated into a linear matrix inequality (LMI. According to the LMI, a fuzzy controller is synthesized not only to realize the exponential synchronization but also to achieve the optimal performance by minimizing the disturbance attenuation level at the same time. Finally, a numerical example with simulations is given to demonstrate the effectiveness of our approach.

  15. Local Stability of AIDS Epidemic Model Through Treatment and Vertical Transmission with Time Delay

    Science.gov (United States)

    Novi W, Cascarilla; Lestari, Dwi

    2016-02-01

    This study aims to explain stability of the spread of AIDS through treatment and vertical transmission model. Human with HIV need a time to positively suffer AIDS. The existence of a time, human with HIV until positively suffer AIDS can be delayed for a time so that the model acquired is the model with time delay. The model form is a nonlinear differential equation with time delay, SIPTA (susceptible-infected-pre AIDS-treatment-AIDS). Based on SIPTA model analysis results the disease free equilibrium point and the endemic equilibrium point. The disease free equilibrium point with and without time delay are local asymptotically stable if the basic reproduction number is less than one. The endemic equilibrium point will be local asymptotically stable if the time delay is less than the critical value of delay, unstable if the time delay is more than the critical value of delay, and bifurcation occurs if the time delay is equal to the critical value of delay.

  16. Global exponential stability of neutral high-order stochastic Hopfield neural networks with Markovian jump parameters and mixed time delays.

    Science.gov (United States)

    Huang, Haiying; Du, Qiaosheng; Kang, Xibing

    2013-11-01

    In this paper, a class of neutral high-order stochastic Hopfield neural networks with Markovian jump parameters and mixed time delays is investigated. The jumping parameters are modeled as a continuous-time finite-state Markov chain. At first, the existence of equilibrium point for the addressed neural networks is studied. By utilizing the Lyapunov stability theory, stochastic analysis theory and linear matrix inequality (LMI) technique, new delay-dependent stability criteria are presented in terms of linear matrix inequalities to guarantee the neural networks to be globally exponentially stable in the mean square. Numerical simulations are carried out to illustrate the main results. © 2013 ISA. Published by ISA. All rights reserved.

  17. Impulsive stabilization and impulsive synchronization of discrete-time delayed neural networks.

    Science.gov (United States)

    Chen, Wu-Hua; Lu, Xiaomei; Zheng, Wei Xing

    2015-04-01

    This paper investigates the problems of impulsive stabilization and impulsive synchronization of discrete-time delayed neural networks (DDNNs). Two types of DDNNs with stabilizing impulses are studied. By introducing the time-varying Lyapunov functional to capture the dynamical characteristics of discrete-time impulsive delayed neural networks (DIDNNs) and by using a convex combination technique, new exponential stability criteria are derived in terms of linear matrix inequalities. The stability criteria for DIDNNs are independent of the size of time delay but rely on the lengths of impulsive intervals. With the newly obtained stability results, sufficient conditions on the existence of linear-state feedback impulsive controllers are derived. Moreover, a novel impulsive synchronization scheme for two identical DDNNs is proposed. The novel impulsive synchronization scheme allows synchronizing two identical DDNNs with unknown delays. Simulation results are given to validate the effectiveness of the proposed criteria of impulsive stabilization and impulsive synchronization of DDNNs. Finally, an application of the obtained impulsive synchronization result for two identical chaotic DDNNs to a secure communication scheme is presented.

  18. Synchronization of delay-coupled nonlinear oscillators: an approach based on the stability analysis of synchronized equilibria.

    Science.gov (United States)

    Michiels, Wim; Nijmeijer, Henk

    2009-09-01

    We consider the synchronization problem of an arbitrary number of coupled nonlinear oscillators with delays in the interconnections. The network topology is described by a directed graph. Unlike the conventional approach of deriving directly sufficient synchronization conditions, the approach of the paper starts from an exact stability analysis in a (gain, delay) parameter space of a synchronized equilibrium and extracts insights from an analysis of its bifurcations and from the corresponding emerging behavior. Instrumental to this analysis a factorization of the characteristic equation is employed that not only facilitates the analysis and reduces computational cost but also allows to determine the precise role of the individual agents and the topology of the network in the (in)stability mechanisms. The study provides an algorithm to perform a stability and bifurcation analysis of synchronized equilibria. Furthermore, it reveals fundamental limitations to synchronization and it explains under which conditions on the topology of the network and on the characteristics of the coupling the systems are expected to synchronize. In the second part of the paper the results are applied to coupled Lorenz systems. The main results show that for sufficiently large coupling gains, delay-coupled Lorenz systems exhibit a generic behavior that does not depend on the number of systems and the topology of the network, as long as some basic assumptions are satisfied, including the strong connectivity of the graph. Here the linearized stability analysis is strengthened by a nonlinear stability analysis which confirms the predictions based on the linearized stability and bifurcation analysis. This illustrates the usefulness of the exact linearized analysis in a situation where a direct nonlinear stability analysis is not possible or where it yields conservative conditions from which it is hard to get qualitative insights in the synchronization mechanisms and their scaling properties

  19. Exponential Antisynchronization Control of Stochastic Memristive Neural Networks with Mixed Time-Varying Delays Based on Novel Delay-Dependent or Delay-Independent Adaptive Controller

    Directory of Open Access Journals (Sweden)

    Minghui Yu

    2017-01-01

    Full Text Available The global exponential antisynchronization in mean square of memristive neural networks with stochastic perturbation and mixed time-varying delays is studied in this paper. Then, two kinds of novel delay-dependent and delay-independent adaptive controllers are designed. With the ability of adapting to environment changes, the proposed controllers can modify their behaviors to achieve the best performance. In particular, on the basis of the differential inclusions theory, inequality theory, and stochastic analysis techniques, several sufficient conditions are obtained to guarantee the exponential antisynchronization between the drive system and response system. Furthermore, two numerical simulation examples are provided to the validity of the derived criteria.

  20. Stability and bifurcation of a discrete BAM neural network model with delays

    International Nuclear Information System (INIS)

    Zheng Baodong; Zhang Yang; Zhang Chunrui

    2008-01-01

    A map modelling a discrete bidirectional associative memory neural network with delays is investigated. Its dynamics is studied in terms of local analysis and Hopf bifurcation analysis. By analyzing the associated characteristic equation, its linear stability is investigated and Hopf bifurcations are demonstrated. It is found that there exist Hopf bifurcations when the delay passes a sequence of critical values. Numerical simulation is performed to verify the analytical results

  1. Stability analysis of delayed Cohen-Grossberg BAM neural networks with impulses via nonsmooth analysis

    International Nuclear Information System (INIS)

    Wen Zhen; Sun Jitao

    2009-01-01

    In this paper, we investigate the existence and uniqueness of equilibrium point for delayed Cohen-Grossberg bidirectional associative memory (BAM) neural networks with impulses, based on nonsmooth analysis method. And we give the criteria of global exponential stability of the unique equilibrium point for the delayed BAM neural networks with impulses using Lyapunov method. The new sufficient condition generalizes and improves the previously known results. Finally, we present examples to illustrate that our results are effective.

  2. Finite-Time Stability for Fractional-Order Bidirectional Associative Memory Neural Networks with Time Delays

    International Nuclear Information System (INIS)

    Xu Chang-Jin; Li Pei-Luan; Pang Yi-Cheng

    2017-01-01

    This paper is concerned with fractional-order bidirectional associative memory (BAM) neural networks with time delays. Applying Laplace transform, the generalized Gronwall inequality and estimates of Mittag–Leffler functions, some sufficient conditions which ensure the finite-time stability of fractional-order bidirectional associative memory neural networks with time delays are obtained. Two examples with their simulations are given to illustrate the theoretical findings. Our results are new and complement previously known results. (paper)

  3. Global asymptotic stability of hybrid bidirectional associative memory neural networks with time delays

    International Nuclear Information System (INIS)

    Arik, Sabri

    2006-01-01

    This Letter presents a sufficient condition for the existence, uniqueness and global asymptotic stability of the equilibrium point for bidirectional associative memory (BAM) neural networks with distributed time delays. The results impose constraint conditions on the network parameters of neural system independently of the delay parameter, and they are applicable to all bounded continuous non-monotonic neuron activation functions. The results are also compared with the previous results derived in the literature

  4. Global asymptotic stability of hybrid bidirectional associative memory neural networks with time delays

    Science.gov (United States)

    Arik, Sabri

    2006-02-01

    This Letter presents a sufficient condition for the existence, uniqueness and global asymptotic stability of the equilibrium point for bidirectional associative memory (BAM) neural networks with distributed time delays. The results impose constraint conditions on the network parameters of neural system independently of the delay parameter, and they are applicable to all bounded continuous non-monotonic neuron activation functions. The results are also compared with the previous results derived in the literature.

  5. Existence and stability of periodic solution in impulsive Hopfield neural networks with finite distributed delays

    International Nuclear Information System (INIS)

    Yang Xiaofan; Liao Xiaofeng; Evans, David J.; Tang Yuanyan

    2005-01-01

    In this Letter, we introduce a class of Hopfield neural networks with periodic impulses and finite distributed delays. We then derive a sufficient condition for the existence and global exponential stability of a unique periodic solution of the networks, which assumes neither the differentiability nor the monotonicity of the activation functions. Our condition extends and generalizes a known condition for the global exponential periodicity of continuous Hopfield neural networks with finite distributed delays

  6. Improved Robust Stability Criterion of Networked Control Systems with Transmission Delays and Packet Loss

    Directory of Open Access Journals (Sweden)

    Shenping Xiao

    2014-01-01

    Full Text Available The problem of stability analysis for a class of networked control systems (NCSs with network-induced delay and packet dropout is investigated in this paper. Based on the working mechanism of zero-order holder, the closed-loop NCS is modeled as a continuous-time linear system with input delay. By introducing a novel Lyapunov-Krasovskii functional which splits both the lower and upper bounds of the delay into two subintervals, respectively, and utilizes reciprocally convex combination technique, a new stability criterion is derived in terms of linear matrix inequalities. Compared with previous results in the literature, the obtained stability criterion is less conservative. Numerical examples demonstrate the validity and feasibility of the proposed method.

  7. Controllability and stability of primary frequency control from thermostatic loads with delays

    DEFF Research Database (Denmark)

    Ziras, Charalampos; Vrettos, Evangelos; You, Shi

    2017-01-01

    There is an increasing interest in exploiting the flexibility of loads to provide ancillary services to the grid. In this paper we study how response delays and lockout constraints affect the controllability of an aggregation of refrigerators offering primary frequency control (PFC). First we...... examine the effect of delays in PFC provision from an aggregation of refrigerators, using a two-area power system. We propose a framework to systematically address frequency measurement and response delays and we determine safe values for the total delays via simulations. We introduce a controllability...... index to evaluate PFC provision under lockout constraints of refrigerators compressors. We conduct extensive simulations to study the effects of measurement delay, ramping times, lockout durations and rotational inertia on the controllability of the aggregation and system stability. Finally, we discuss...

  8. Globally Asymptotic Stability of Stochastic Nonlinear Systems with Time-Varying Delays via Output Feedback Control

    Directory of Open Access Journals (Sweden)

    Mingzhu Song

    2016-01-01

    Full Text Available We address the problem of globally asymptotic stability for a class of stochastic nonlinear systems with time-varying delays. By the backstepping method and Lyapunov theory, we design a linear output feedback controller recursively based on the observable linearization for a class of stochastic nonlinear systems with time-varying delays to guarantee that the closed-loop system is globally asymptotically stable in probability. In particular, we extend the deterministic nonlinear system to stochastic nonlinear systems with time-varying delays. Finally, an example and its simulations are given to illustrate the theoretical results.

  9. Global asymptotic stability of Cohen-Grossberg neural networks with constant and variable delays

    International Nuclear Information System (INIS)

    Wu Wei; Cui Baotong; Huang Min

    2007-01-01

    Global asymptotic stability of Cohen-Grossberg neural networks with constant and variable delays is studied. Some sufficient conditions for the neural networks are proposed to guarantee the global asymptotic convergence by using different Lyapunov functionals. Our criteria represent an extension of the existing results in literatures. A comparison between our results and the previous results admits that our results establish a new set of stability criteria for delayed Cohen-Grossberg neural networks. Those conditions are less restrictive than those given in the earlier reference

  10. Stability and bifurcation analysis in a kind of business cycle model with delay

    International Nuclear Information System (INIS)

    Zhang Chunrui; Wei Junjie

    2004-01-01

    A kind of business cycle model with delay is considered. Firstly, the linear stability of the model is studied and bifurcation set is drawn in the appropriate parameter plane. It is found that there exist Hopf bifurcations when the delay passes a sequence of critical values. Then the explicit algorithm for determining the direction of the Hopf bifurcations and the stability of the bifurcating periodic solutions are derived, using the normal form method and center manifold theorem. Finally, a group conditions to guarantee the global existence of periodic solutions is given, and numerical simulations are performed to illustrate the analytical results found

  11. Robust stability and ℋ ∞ -estimation for uncertain discrete systems with state-delay

    Directory of Open Access Journals (Sweden)

    Mahmoud Magdi S.

    2001-01-01

    Full Text Available In this paper, we investigate the problems of robust stability and ℋ ∞ -estimation for a class of linear discrete-time systems with time-varying norm-bounded parameter uncertainty and unknown state-delay. We provide complete results for robust stability with prescribed performance measure and establish a version of the discrete Bounded Real Lemma. Then, we design a linear estimator such that the estimation error dynamics is robustly stable with a guaranteed ℋ ∞ -performance irrespective of the parameteric uncertainties and unknown state delays. A numerical example is worked out to illustrate the developed theory.

  12. Stability, bifurcation and a new chaos in the logistic differential equation with delay

    International Nuclear Information System (INIS)

    Jiang Minghui; Shen Yi; Jian Jigui; Liao Xiaoxin

    2006-01-01

    This Letter is concerned with bifurcation and chaos in the logistic delay differential equation with a parameter r. The linear stability of the logistic equation is investigated by analyzing the associated characteristic transcendental equation. Based on the normal form approach and the center manifold theory, the formula for determining the direction of Hopf bifurcation and the stability of bifurcation periodic solution in the first bifurcation values is obtained. By theoretical analysis and numerical simulation, we found a new chaos in the logistic delay differential equation

  13. Global Stability of an Eco-Epidemiological Model with Time Delay and Saturation Incidence

    Directory of Open Access Journals (Sweden)

    Shuxue Mao

    2011-01-01

    Full Text Available We investigate a delayed eco-epidemiological model with disease in predator and saturation incidence. First, by comparison arguments, the permanence of the model is discussed. Then, we study the local stability of each equilibrium of the model by analyzing the corresponding characteristic equations and find that Hopf bifurcation occurs when the delay τ passes through a sequence of critical values. Next, by means of an iteration technique, sufficient conditions are derived for the global stability of the disease-free planar equilibrium and the positive equilibrium. Numerical examples are carried out to illustrate the analytical results.

  14. Global asymptotic stability analysis of bidirectional associative memory neural networks with time delays.

    Science.gov (United States)

    Arik, Sabri

    2005-05-01

    This paper presents a sufficient condition for the existence, uniqueness and global asymptotic stability of the equilibrium point for bidirectional associative memory (BAM) neural networks with distributed time delays. The results impose constraint conditions on the network parameters of neural system independently of the delay parameter, and they are applicable to all continuous nonmonotonic neuron activation functions. It is shown that in some special cases of the results, the stability criteria can be easily checked. Some examples are also given to compare the results with the previous results derived in the literature.

  15. New results for global robust stability of bidirectional associative memory neural networks with multiple time delays

    International Nuclear Information System (INIS)

    Senan, Sibel; Arik, Sabri

    2009-01-01

    This paper presents some new sufficient conditions for the global robust asymptotic stability of the equilibrium point for bidirectional associative memory (BAM) neural networks with multiple time delays. The results we obtain impose constraint conditions on the network parameters of neural system independently of the delay parameter, and they are applicable to all bounded continuous non-monotonic neuron activation functions. We also give some numerical examples to demonstrate the applicability and effectiveness of our results, and compare the results with the previous robust stability results derived in the literature.

  16. Stability and Hopf bifurcation in a delayed model for HIV infection of CD4{sup +}T cells

    Energy Technology Data Exchange (ETDEWEB)

    Cai Liming [Department of Mathematics, Xinyang Normal University, Xinyang, 464000 Henan (China); Beijing Institute of Information Control, Beijing 100037 (China)], E-mail: lmcai06@yahoo.com.cn; Li Xuezhi [Department of Mathematics, Xinyang Normal University, Xinyang, 464000 Henan (China)

    2009-10-15

    In this paper, we consider a delayed mathematical model for the interactions of HIV infection and CD4{sup +}T cells. We first investigate the existence and stability of the Equilibria. We then study the effect of the time delay on the stability of the infected equilibrium. Criteria are given to ensure that the infected equilibrium is asymptotically stable for all delay. Moreover, by applying Nyquist criterion, the length of delay is estimated for which stability continues to hold. Finally by using a delay {tau} as a bifurcation parameter, the existence of Hopf bifurcation is also investigated. Numerical simulations are presented to illustrate the analytical results.

  17. Stability Analysis of a Predecessor-Following Platoon of Vehicles With Two Time Delays

    Directory of Open Access Journals (Sweden)

    Ali Ghasemi

    2015-03-01

    Full Text Available The problem of controlling a platoon of vehicles moving in one dimension is considered so that they all follow a lead vehicle with constant spacing between successive vehicles. The stability and the string stability of a platoon of vehicles with two independent and uncertain delays, one in the inter-vehicle distance and the other in the relative velocity information channels, are considered. The main objectives of this paper are: (1 using a simplifying factorization procedure and deploying the cluster treatment of characteristic roots (CTCR paradigm to obtain exact stability boundaries in the domain of the delays, and (2 for the purpose of disturbance attenuation, the string stability analysis is examined. Finally, a simulation example of multiple vehicle platoon control is used to demonstrate the effectiveness of the proposed method.

  18. Effect of state-dependent delay on a weakly damped nonlinear oscillator.

    Science.gov (United States)

    Mitchell, Jonathan L; Carr, Thomas W

    2011-04-01

    We consider a weakly damped nonlinear oscillator with state-dependent delay, which has applications in models for lasers, epidemics, and microparasites. More generally, the delay-differential equations considered are a predator-prey system where the delayed term is linear and represents the proliferation of the predator. We determine the critical value of the delay that causes the steady state to become unstable to periodic oscillations via a Hopf bifurcation. Using asymptotic averaging, we determine how the system's behavior is influenced by the functional form of the state-dependent delay. Specifically, we determine whether the branch of periodic solutions will be either sub- or supercritical as well as an accurate estimation of the amplitude. Finally, we choose a few examples of state-dependent delay to test our analytical results by comparing them to numerical continuation.

  19. Estimation of time- and state-dependent delays and other parameters in functional differential equations

    Science.gov (United States)

    Murphy, K. A.

    1990-01-01

    A parameter estimation algorithm is developed which can be used to estimate unknown time- or state-dependent delays and other parameters (e.g., initial condition) appearing within a nonlinear nonautonomous functional differential equation. The original infinite dimensional differential equation is approximated using linear splines, which are allowed to move with the variable delay. The variable delays are approximated using linear splines as well. The approximation scheme produces a system of ordinary differential equations with nice computational properties. The unknown parameters are estimated within the approximating systems by minimizing a least-squares fit-to-data criterion. Convergence theorems are proved for time-dependent delays and state-dependent delays within two classes, which say essentially that fitting the data by using approximations will, in the limit, provide a fit to the data using the original system. Numerical test examples are presented which illustrate the method for all types of delay.

  20. Estimation of exponential convergence rate and exponential stability for neural networks with time-varying delay

    International Nuclear Information System (INIS)

    Tu Fenghua; Liao Xiaofeng

    2005-01-01

    We study the problem of estimating the exponential convergence rate and exponential stability for neural networks with time-varying delay. Some criteria for exponential stability are derived by using the linear matrix inequality (LMI) approach. They are less conservative than the existing ones. Some analytical methods are employed to investigate the bounds on the interconnection matrix and activation functions so that the systems are exponentially stable

  1. Well-posedness and exponential stability for a wave equation with nonlocal time-delay condition

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    Carlos Alberto Raposo

    2017-11-01

    Full Text Available Well-posedness and exponential stability of nonlocal time-delayed of a wave equation with a integral conditions of the 1st kind forms the center of this work. Through semigroup theory we prove the well-posedness by the Hille-Yosida theorem and the exponential stability exploring the dissipative properties of the linear operator associated to damped model using the Gearhart-Huang-Pruss theorem.

  2. Stability and Hopf Bifurcation in a Delayed SEIRS Worm Model in Computer Network

    Directory of Open Access Journals (Sweden)

    Zizhen Zhang

    2013-01-01

    Full Text Available A delayed SEIRS epidemic model with vertical transmission in computer network is considered. Sufficient conditions for local stability of the positive equilibrium and existence of local Hopf bifurcation are obtained by analyzing distribution of the roots of the associated characteristic equation. Furthermore, the direction of the local Hopf bifurcation and the stability of the bifurcating periodic solutions are determined by using the normal form theory and center manifold theorem. Finally, a numerical example is presented to verify the theoretical analysis.

  3. Existence and exponential stability of almost periodic solution for stochastic cellular neural networks with delay

    International Nuclear Information System (INIS)

    Huang Zaitang; Yang Qigui

    2009-01-01

    The paper considers the problems of existence of quadratic mean almost periodic and global exponential stability for stochastic cellular neural networks with delays. By employing the Holder's inequality and fixed points principle, we present some new criteria ensuring existence and uniqueness of a quadratic mean almost periodic and global exponential stability. These criteria are important in signal processing and the design of networks. Moreover, these criteria are also applied in others stochastic biological neural systems.

  4. Existence and stability of periodic solutions for a delayed prey-predator model with diffusion effects

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    Hongwei Liang

    2016-01-01

    Full Text Available Existence and stability of spatially periodic solutions for a delay prey-predator diffusion system are concerned in this work. We obtain that the system can generate the spatially nonhomogeneous periodic solutions when the diffusive rates are suitably small. This result demonstrates that the diffusion plays an important role on deriving the complex spatiotemporal dynamics. Meanwhile, the stability of the spatially periodic solutions is also studied. Finally, in order to verify our theoretical results, some numerical simulations are also included.

  5. Stability regions for synchronized τ-periodic orbits of coupled maps with coupling delay τ

    Energy Technology Data Exchange (ETDEWEB)

    Karabacak, Özkan, E-mail: ozkan2917@gmail.com [Department of Electronics and Communication Engineering, Istanbul Technical University, 34469 Istanbul (Turkey); Department of Electronic Systems, Aalborg University, 9220 Aalborg East (Denmark); Alikoç, Baran, E-mail: alikoc@itu.edu.tr [Department of Control and Automation Engineering, Istanbul Technical University, 34469 Istanbul (Turkey); Atay, Fatihcan M., E-mail: atay@member.ams.org [Department of Mathematics, Bilkent University, 06800 Ankara (Turkey)

    2016-09-15

    Motivated by the chaos suppression methods based on stabilizing an unstable periodic orbit, we study the stability of synchronized periodic orbits of coupled map systems when the period of the orbit is the same as the delay in the information transmission between coupled units. We show that the stability region of a synchronized periodic orbit is determined by the Floquet multiplier of the periodic orbit for the uncoupled map, the coupling constant, the smallest and the largest Laplacian eigenvalue of the adjacency matrix. We prove that the stabilization of an unstable τ-periodic orbit via coupling with delay τ is possible only when the Floquet multiplier of the orbit is negative and the connection structure is not bipartite. For a given coupling structure, it is possible to find the values of the coupling strength that stabilizes unstable periodic orbits. The most suitable connection topology for stabilization is found to be the all-to-all coupling. On the other hand, a negative coupling constant may lead to destabilization of τ-periodic orbits that are stable for the uncoupled map. We provide examples of coupled logistic maps demonstrating the stabilization and destabilization of synchronized τ-periodic orbits as well as chaos suppression via stabilization of a synchronized τ-periodic orbit.

  6. Stability and oscillation of two coupled Duffing equations with time delay state feedback

    International Nuclear Information System (INIS)

    El-Bassiouny, A F

    2006-01-01

    This paper presents an analytical study of the simultaneous principal parametric resonances of two coupled Duffing equations with time delay state feedback. The concept of an equivalent damping related to the delay feedback is proposed and the appropriate choice of the feedback gains and the time delay is discussed from the viewpoint of vibration control. The method of multiple scales is used to determine a set of ordinary differential equations governing the modulation of the amplitudes and phases of the two modes. The first order approximation of the resonances are derived and the effect of time delay on the resonances is investigated. The fixed points correspond to a periodic motion for the starting system and we show the frequency-response curves. We analyse the effect of time delay and the other different parameters on these oscillations. The stability of the fixed points is examined by using the variational method. Numerical solutions are carried out and graphical representations of the results are presented and discussed. Increasing in the time delay τ given decreasing and increasing in the regions of definition and stability respectively and the first mode has decreased magnitudes. The multivalued solutions disappear when decreasing the coefficients of cubic nonlinearities of the second mode α 3 and the detuning parameter σ 2 respectively. Both modes shift to the left for increasing linear feedback gain v 1 and the coefficient of parametric excitation f 1 respectively

  7. Oscillation and asymptotic stability of a delay differential equation with Richard's nonlinearity

    Directory of Open Access Journals (Sweden)

    Leonid Berezansky

    2005-04-01

    Full Text Available We obtain sufficient conditions for oscillation of solutions, and for asymptotical stability of the positive equilibrium, of the scalar nonlinear delay differential equation $$ frac{dN}{dt} = r(tN(tBig[a-Big(sum_{k=1}^m b_k N(g_k(tBig^{gamma}Big], $$ where $ g_k(tleq t$.

  8. Stabilization of the Wave Equation with Boundary Time-Varying Delay

    Directory of Open Access Journals (Sweden)

    Hao Li

    2014-01-01

    Full Text Available We study the stabilization of the wave equation with variable coefficients in a bounded domain and a time-varying delay term in the time-varying, weakly nonlinear boundary feedbacks. By the Riemannian geometry methods and a suitable assumption of nonlinearity, we obtain the uniform decay of the energy of the closed loop system.

  9. Stability of Delayed Hopfield Neural Networks with Variable-Time Impulses

    Directory of Open Access Journals (Sweden)

    Yangjun Pei

    2014-01-01

    Full Text Available In this paper the globally exponential stability criteria of delayed Hopfield neural networks with variable-time impulses are established. The proposed criteria can also be applied in Hopfield neural networks with fixed-time impulses. A numerical example is presented to illustrate the effectiveness of our theoretical results.

  10. W-transform for exponential stability of second order delay differential equations without damping terms.

    Science.gov (United States)

    Domoshnitsky, Alexander; Maghakyan, Abraham; Berezansky, Leonid

    2017-01-01

    In this paper a method for studying stability of the equation [Formula: see text] not including explicitly the first derivative is proposed. We demonstrate that although the corresponding ordinary differential equation [Formula: see text] is not exponentially stable, the delay equation can be exponentially stable.

  11. Stability and square integrability of derivatives of solutions of nonlinear fourth order differential equations with delay.

    Science.gov (United States)

    Korkmaz, Erdal

    2017-01-01

    In this paper, we give sufficient conditions for the boundedness, uniform asymptotic stability and square integrability of the solutions to a certain fourth order non-autonomous differential equations with delay by using Lyapunov's second method. The results obtained essentially improve, include and complement the results in the literature.

  12. Global asymptotic stability of Cohen-Grossberg neural network with continuously distributed delays

    International Nuclear Information System (INIS)

    Wan Li; Sun Jianhua

    2005-01-01

    The convergence dynamical behaviors of Cohen-Grossberg neural network with continuously distributed delays are discussed. By using Brouwer's fixed point theorem, matrix theory and analysis techniques such as Gronwall inequality, some new sufficient conditions guaranteeing the existence, uniqueness of an equilibrium point and its global asymptotic stability are obtained. An example is given to illustrate the theoretical results

  13. Stabilization of wave equations with variable coefficient and delay in the dynamical boundary feedback

    Directory of Open Access Journals (Sweden)

    Dandan Guo

    2017-08-01

    Full Text Available In this article we consider the boundary stabilization of a wave equation with variable coefficients. This equation has an acceleration term and a delayed velocity term on the boundary. Under suitable geometric conditions, we obtain the exponential decay for the solutions. Our proof relies on the geometric multiplier method and the Lyapunov approach.

  14. New stability and boundedness results to Volterra integro-differential equations with delay

    Directory of Open Access Journals (Sweden)

    Cemil Tunç

    2016-04-01

    Full Text Available In this paper, we consider a certain non-linear Volterra integro-differential equations with delay. We study stability and boundedness of solutions. The technique of proof involves defining suitable Lyapunov functionals. Our results improve and extend the results obtained in literature.

  15. Stability and square integrability of derivatives of solutions of nonlinear fourth order differential equations with delay

    Directory of Open Access Journals (Sweden)

    Erdal Korkmaz

    2017-06-01

    Full Text Available Abstract In this paper, we give sufficient conditions for the boundedness, uniform asymptotic stability and square integrability of the solutions to a certain fourth order non-autonomous differential equations with delay by using Lyapunov’s second method. The results obtained essentially improve, include and complement the results in the literature.

  16. Global exponential stability of cellular neural networks with mixed delays and impulses

    International Nuclear Information System (INIS)

    Xiong Wanmin; Zhou Qiyuan; Xiao Bing; Yu Yuehua

    2007-01-01

    In this paper cellular neural networks with mixed delays and impulses are considered. Sufficient conditions for the existence and global exponential stability of a unique equilibrium point are established by using the fixed point theorem and differential inequality technique. The results of this paper are new and they complement previously known results

  17. Global exponential stability of cellular neural networks with continuously distributed delays and impulses

    International Nuclear Information System (INIS)

    Wang Yixuan; Xiong Wanmin; Zhou Qiyuan; Xiao Bing; Yu Yuehua

    2006-01-01

    In this Letter cellular neural networks with continuously distributed delays and impulses are considered. Sufficient conditions for the existence and global exponential stability of a unique equilibrium point are established by using the fixed point theorem and differential inequality techniques. The results of this Letter are new and they complement previously known results

  18. A fixed point approach towards stability of delay differential equations with applications to neural networks

    NARCIS (Netherlands)

    Chen, Guiling

    2013-01-01

    This thesis studies asymptotic behavior and stability of determinsitic and stochastic delay differential equations. The approach used in this thesis is based on fixed point theory, which does not resort to any Liapunov function or Liapunov functional. The main contribution of this thesis is to study

  19. Stability and Hopf bifurcation for a business cycle model with expectation and delay

    Science.gov (United States)

    Liu, Xiangdong; Cai, Wenli; Lu, Jiajun; Wang, Yangyang

    2015-08-01

    According to rational expectation hypothesis, the government will take into account the future capital stock in the process of investment decision. By introducing anticipated capital stock into an economic model with investment delay, we construct a mixed functional differential system including delay and advanced variables. The system is converted to the one containing only delay by variable substitution. The equilibrium point of the system is obtained and its dynamical characteristics such as stability, Hopf bifurcation and its stability and direction are investigated by using the related theories of nonlinear dynamics. We carry out some numerical simulations to confirm these theoretical conclusions. The results indicate that both capital stock's anticipation and investment lag are the certain factors leading to the occurrence of cyclical fluctuations in the macroeconomic system. Moreover, the level of economic fluctuation can be dampened to some extent if investment decisions are made by the reasonable short-term forecast on capital stock.

  20. Stability and Hopf Bifurcation of a Reaction-Diffusion Neutral Neuron System with Time Delay

    Science.gov (United States)

    Dong, Tao; Xia, Linmao

    2017-12-01

    In this paper, a type of reaction-diffusion neutral neuron system with time delay under homogeneous Neumann boundary conditions is considered. By constructing a basis of phase space based on the eigenvectors of the corresponding Laplace operator, the characteristic equation of this system is obtained. Then, by selecting time delay and self-feedback strength as the bifurcating parameters respectively, the dynamic behaviors including local stability and Hopf bifurcation near the zero equilibrium point are investigated when the time delay and self-feedback strength vary. Furthermore, the direction of the Hopf bifurcation and the stability of bifurcating periodic solutions are obtained by using the normal form and the center manifold theorem for the corresponding partial differential equation. Finally, two simulation examples are given to verify the theory.

  1. Finite-time stability of neutral-type neural networks with random time-varying delays

    Science.gov (United States)

    Ali, M. Syed; Saravanan, S.; Zhu, Quanxin

    2017-11-01

    This paper is devoted to the finite-time stability analysis of neutral-type neural networks with random time-varying delays. The randomly time-varying delays are characterised by Bernoulli stochastic variable. This result can be extended to analysis and design for neutral-type neural networks with random time-varying delays. On the basis of this paper, we constructed suitable Lyapunov-Krasovskii functional together and established a set of sufficient linear matrix inequalities approach to guarantee the finite-time stability of the system concerned. By employing the Jensen's inequality, free-weighting matrix method and Wirtinger's double integral inequality, the proposed conditions are derived and two numerical examples are addressed for the effectiveness of the developed techniques.

  2. Robust stability analysis of uncertain stochastic neural networks with interval time-varying delay

    International Nuclear Information System (INIS)

    Feng Wei; Yang, Simon X.; Fu Wei; Wu Haixia

    2009-01-01

    This paper addresses the stability analysis problem for uncertain stochastic neural networks with interval time-varying delays. The parameter uncertainties are assumed to be norm bounded, and the delay factor is assumed to be time-varying and belong to a given interval, which means that the lower and upper bounds of interval time-varying delays are available. A sufficient condition is derived such that for all admissible uncertainties, the considered neural network is robustly, globally, asymptotically stable in the mean square. Some stability criteria are formulated by means of the feasibility of a linear matrix inequality (LMI), which can be effectively solved by some standard numerical packages. Finally, numerical examples are provided to demonstrate the usefulness of the proposed criteria.

  3. Robust stability of interval bidirectional associative memory neural network with time delays.

    Science.gov (United States)

    Liao, Xiaofeng; Wong, Kwok-wo

    2004-04-01

    In this paper, the conventional bidirectional associative memory (BAM) neural network with signal transmission delay is intervalized in order to study the bounded effect of deviations in network parameters and external perturbations. The resultant model is referred to as a novel interval dynamic BAM (IDBAM) model. By combining a number of different Lyapunov functionals with the Razumikhin technique, some sufficient conditions for the existence of unique equilibrium and robust stability are derived. These results are fairly general and can be verified easily. To go further, we extend our investigation to the time-varying delay case. Some robust stability criteria for BAM with perturbations of time-varying delays are derived. Besides, our approach for the analysis allows us to consider several different types of activation functions, including piecewise linear sigmoids with bounded activations as well as the usual C1-smooth sigmoids. We believe that the results obtained have leading significance in the design and application of BAM neural networks.

  4. Robust stability for stochastic bidirectional associative memory neural networks with time delays

    Science.gov (United States)

    Shu, H. S.; Lv, Z. W.; Wei, G. L.

    2008-02-01

    In this paper, the asymptotic stability is considered for a class of uncertain stochastic bidirectional associative memory neural networks with time delays and parameter uncertainties. The delays are time-invariant and the uncertainties are norm-bounded that enter into all network parameters. The aim of this paper is to establish easily verifiable conditions under which the delayed neural network is robustly asymptotically stable in the mean square for all admissible parameter uncertainties. By employing a Lyapunov-Krasovskii functional and conducting the stochastic analysis, a linear matrix inequality matrix inequality (LMI) approach is developed to derive the stability criteria. The proposed criteria can be easily checked by the Matlab LMI toolbox. A numerical example is given to demonstrate the usefulness of the proposed criteria.

  5. Discrete-time recurrent neural networks with time-varying delays: Exponential stability analysis

    International Nuclear Information System (INIS)

    Liu, Yurong; Wang, Zidong; Serrano, Alan; Liu, Xiaohui

    2007-01-01

    This Letter is concerned with the analysis problem of exponential stability for a class of discrete-time recurrent neural networks (DRNNs) with time delays. The delay is of the time-varying nature, and the activation functions are assumed to be neither differentiable nor strict monotonic. Furthermore, the description of the activation functions is more general than the recently commonly used Lipschitz conditions. Under such mild conditions, we first prove the existence of the equilibrium point. Then, by employing a Lyapunov-Krasovskii functional, a unified linear matrix inequality (LMI) approach is developed to establish sufficient conditions for the DRNNs to be globally exponentially stable. It is shown that the delayed DRNNs are globally exponentially stable if a certain LMI is solvable, where the feasibility of such an LMI can be easily checked by using the numerically efficient Matlab LMI Toolbox. A simulation example is presented to show the usefulness of the derived LMI-based stability condition

  6. Robust Stability and H∞ Stabilization of Switched Systems with Time-Varying Delays Using Delta Operator Approach

    Directory of Open Access Journals (Sweden)

    Chen Qin

    2013-01-01

    Full Text Available This paper considers the problems of the robust stability and robust H∞ controller design for time-varying delay switched systems using delta operator approach. Based on the average dwell time approach and delta operator theory, a sufficient condition of the robust exponential stability is presented by choosing an appropriate Lyapunov-Krasovskii functional candidate. Then, a state feedback controller is designed such that the resulting closed-loop system is exponentially stable with a guaranteed H∞ performance. The obtained results are formulated in the form of linear matrix inequalities (LMIs. Finally, a numerical example is provided to explicitly illustrate the feasibility and effectiveness of the proposed method.

  7. Stability analysis for a delay differential equations model of a hydraulic turbine speed governor

    Science.gov (United States)

    Halanay, Andrei; Safta, Carmen A.; Dragoi, Constantin; Piraianu, Vlad F.

    2017-01-01

    The paper aims to study the dynamic behavior of a speed governor for a hydraulic turbine using a mathematical model. The nonlinear mathematical model proposed consists in a system of delay differential equations (DDE) to be compared with already established mathematical models of ordinary differential equations (ODE). A new kind of nonlinearity is introduced as a time delay. The delays can characterize different running conditions of the speed governor. For example, it is considered that spool displacement of hydraulic amplifier might be blocked due to oil impurities in the oil supply system and so the hydraulic amplifier has a time delay in comparison to the time control. Numerical simulations are presented in a comparative manner. A stability analysis of the hydraulic control system is performed, too. Conclusions of the dynamic behavior using the DDE model of a hydraulic turbine speed governor are useful in modeling and controlling hydropower plants.

  8. Sharp conditions for global stability of Lotka-Volterra systems with distributed delays

    Science.gov (United States)

    Faria, Teresa

    We give a criterion for the global attractivity of a positive equilibrium of n-dimensional non-autonomous Lotka-Volterra systems with distributed delays. For a class of autonomous Lotka-Volterra systems, we show that such a criterion is sharp, in the sense that it provides necessary and sufficient conditions for the global asymptotic stability independently of the choice of the delay functions. The global attractivity of positive equilibria is established by imposing a diagonal dominance of the instantaneous negative feedback terms, and relies on auxiliary results showing the boundedness of all positive solutions. The paper improves and generalizes known results in the literature, namely by considering systems with distributed delays rather than discrete delays.

  9. Stability and bifurcation in a simplified four-neuron BAM neural network with multiple delays

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available We first study the distribution of the zeros of a fourth-degree exponential polynomial. Then we apply the obtained results to a simplified bidirectional associated memory (BAM neural network with four neurons and multiple time delays. By taking the sum of the delays as the bifurcation parameter, it is shown that under certain assumptions the steady state is absolutely stable. Under another set of conditions, there are some critical values of the delay, when the delay crosses these critical values, the Hopf bifurcation occurs. Furthermore, some explicit formulae determining the stability and the direction of periodic solutions bifurcating from Hopf bifurcations are obtained by applying the normal form theory and center manifold reduction. Numerical simulations supporting the theoretical analysis are also included.

  10. Stability Analysis and Application for Delayed Neural Networks Driven by Fractional Brownian Noise.

    Science.gov (United States)

    Zhou, Wuneng; Zhou, Xianghui; Yang, Jun; Zhou, Jun; Tong, Dongbing

    2018-05-01

    This paper deals with two types of the stability problem for the delayed neural networks driven by fractional Brownian noise (FBN). The existence and the uniqueness of the solution to the main system with respect to FBN are proved via fixed point theory. Based on Hilbert-Schmidt operator theory and analytic semigroup principle, the mild solution of the stochastic neural networks is obtained. By applying the stochastic analytic technique and some well-known inequalities, the asymptotic stability criteria and the exponential stability condition are established. Both numerical example and practical application for synchronization control of multiagent system are provided to illustrate the effectiveness and potential of the proposed techniques.

  11. Stability and bifurcation analysis for a discrete-time bidirectional ring neural network model with delay

    Directory of Open Access Journals (Sweden)

    Yan-Ke Du

    2013-09-01

    Full Text Available We study a class of discrete-time bidirectional ring neural network model with delay. We discuss the asymptotic stability of the origin and the existence of Neimark-Sacker bifurcations, by analyzing the corresponding characteristic equation. Employing M-matrix theory and the Lyapunov functional method, global asymptotic stability of the origin is derived. Applying the normal form theory and the center manifold theorem, the direction of the Neimark-Sacker bifurcation and the stability of bifurcating periodic solutions are obtained. Numerical simulations are given to illustrate the main results.

  12. A mathematical model for the control of carrier-dependent infectious diseases with direct transmission and time delay

    International Nuclear Information System (INIS)

    Misra, A.K.; Mishra, S.N.; Pathak, A.L.; Srivastava, P.K.; Chandra, Peeyush

    2013-01-01

    In this paper, a non-linear delay mathematical model for the control of carrier-dependent infectious diseases through insecticides is proposed and analyzed. In the modeling process, it is assumed that disease spreads due to direct contact between susceptibles and infectives as well as through carriers (indirect contact). Further, it is assumed that insecticides are used to kill carriers and the rate of introduction of insecticides is proportional to the density of carriers with some time lag. The model analysis suggests that as delay in using insecticides exceeds some critical value, the system loses its stability and Hopf-bifurcation occurs. The direction, stability and period of the bifurcating periodic solutions arising through Hopf-bifurcation are also analyzed using normal form concept and center manifold theory. Numerical simulation is carried out to confirm the obtained analytical results

  13. Stability Control of Force-Reflected Nonlinear Multilateral Teleoperation System under Time-Varying Delays

    Directory of Open Access Journals (Sweden)

    Da Sun

    2016-01-01

    Full Text Available A novel control algorithm based on the modified wave-variable controllers is proposed to achieve accurate position synchronization and reasonable force tracking of the nonlinear single-master-multiple-slave teleoperation system and simultaneously guarantee overall system’s stability in the presence of large time-varying delays. The system stability in different scenarios of human and environment situations has been analyzed. The proposed method is validated through experimental work based on the 3-DOF trilateral teleoperation system consisting of three different manipulators. The experimental results clearly demonstrate the feasibility of the proposed algorithm to achieve high transparency and robust stability in nonlinear single-master-multiple-slave teleoperation system in the presence of time-varying delays.

  14. Predictor-based stabilization for chained form systems with input time delay

    Directory of Open Access Journals (Sweden)

    Mnif Faïçal

    2016-12-01

    Full Text Available This note addresses the stabilization problem of nonlinear chained-form systems with input time delay. We first employ the so-called σ-process transformation that renders the feedback system under a linear form. We introduce a particular transformation to convert the original system into a delay-free system. Finally, we apply a state feedback control, which guarantees a quasi-exponential stabilization to all the system states, which in turn converge exponentially to zero. Then we employ the so-called -type control to achieve a quasi-exponential stabilization of the subsequent system. A simulation example illustrated on the model of a wheeled mobile robot is provided to demonstrate the effectiveness of the proposed approach.

  15. Exponential Stability for Impulsive BAM Neural Networks with Time-Varying Delays and Reaction-Diffusion Terms

    Directory of Open Access Journals (Sweden)

    Qiankun Song

    2007-06-01

    Full Text Available Impulsive bidirectional associative memory neural network model with time-varying delays and reaction-diffusion terms is considered. Several sufficient conditions ensuring the existence, uniqueness, and global exponential stability of equilibrium point for the addressed neural network are derived by M-matrix theory, analytic methods, and inequality techniques. Moreover, the exponential convergence rate index is estimated, which depends on the system parameters. The obtained results in this paper are less restrictive than previously known criteria. Two examples are given to show the effectiveness of the obtained results.

  16. Exponential Stability for Impulsive BAM Neural Networks with Time-Varying Delays and Reaction-Diffusion Terms

    Directory of Open Access Journals (Sweden)

    Cao Jinde

    2007-01-01

    Full Text Available Impulsive bidirectional associative memory neural network model with time-varying delays and reaction-diffusion terms is considered. Several sufficient conditions ensuring the existence, uniqueness, and global exponential stability of equilibrium point for the addressed neural network are derived by M-matrix theory, analytic methods, and inequality techniques. Moreover, the exponential convergence rate index is estimated, which depends on the system parameters. The obtained results in this paper are less restrictive than previously known criteria. Two examples are given to show the effectiveness of the obtained results.

  17. Existence and Stability of Traveling Waves for Degenerate Reaction-Diffusion Equation with Time Delay

    Science.gov (United States)

    Huang, Rui; Jin, Chunhua; Mei, Ming; Yin, Jingxue

    2018-01-01

    This paper deals with the existence and stability of traveling wave solutions for a degenerate reaction-diffusion equation with time delay. The degeneracy of spatial diffusion together with the effect of time delay causes us the essential difficulty for the existence of the traveling waves and their stabilities. In order to treat this case, we first show the existence of smooth- and sharp-type traveling wave solutions in the case of c≥c^* for the degenerate reaction-diffusion equation without delay, where c^*>0 is the critical wave speed of smooth traveling waves. Then, as a small perturbation, we obtain the existence of the smooth non-critical traveling waves for the degenerate diffusion equation with small time delay τ >0 . Furthermore, we prove the global existence and uniqueness of C^{α ,β } -solution to the time-delayed degenerate reaction-diffusion equation via compactness analysis. Finally, by the weighted energy method, we prove that the smooth non-critical traveling wave is globally stable in the weighted L^1 -space. The exponential convergence rate is also derived.

  18. Existence and Stability of Traveling Waves for Degenerate Reaction-Diffusion Equation with Time Delay

    Science.gov (United States)

    Huang, Rui; Jin, Chunhua; Mei, Ming; Yin, Jingxue

    2018-06-01

    This paper deals with the existence and stability of traveling wave solutions for a degenerate reaction-diffusion equation with time delay. The degeneracy of spatial diffusion together with the effect of time delay causes us the essential difficulty for the existence of the traveling waves and their stabilities. In order to treat this case, we first show the existence of smooth- and sharp-type traveling wave solutions in the case of c≥c^* for the degenerate reaction-diffusion equation without delay, where c^*>0 is the critical wave speed of smooth traveling waves. Then, as a small perturbation, we obtain the existence of the smooth non-critical traveling waves for the degenerate diffusion equation with small time delay τ >0. Furthermore, we prove the global existence and uniqueness of C^{α ,β }-solution to the time-delayed degenerate reaction-diffusion equation via compactness analysis. Finally, by the weighted energy method, we prove that the smooth non-critical traveling wave is globally stable in the weighted L^1-space. The exponential convergence rate is also derived.

  19. Proportional Retarded Controller to Stabilize Underactuated Systems with Measurement Delays: Furuta Pendulum Case Study

    Directory of Open Access Journals (Sweden)

    T. Ortega-Montiel

    2017-01-01

    Full Text Available The design and tuning of a simple feedback strategy with delay to stabilize a class of underactuated mechanical systems with dead time are presented. A linear time-invariant (LTI model with time delay of fourth order and a Proportional Retarded (PR controller are considered. The PR controller is shown as an appealing alternative to the application of observer-based controllers. This paper gives a step forward to obtain a better understanding of the effect of output delays and related phenomena in mechatronic systems, making it possible to design resilient control laws under the presence of uncertain time delays in measurements and obtain an acceptable performance without using a derivative action. The Furuta pendulum is a standard two-degrees-of-freedom benchmark example from the class of underactuated mechanical systems. The configuration under study includes an inherent output delay due to wireless communication used to transmit measurements of the pendulum’s angular position. Our approach offers a constructive design and a procedure based on a combination of root loci and Mikhailov methods for the analysis of stability. Experiments over a laboratory platform are reported and a comparison with a standard linear state feedback control law shows the advantages of the proposed scheme.

  20. H∞ Filtering for Discrete Markov Jump Singular Systems with Mode-Dependent Time Delay Based on T-S Fuzzy Model

    Directory of Open Access Journals (Sweden)

    Cheng Gong

    2014-01-01

    Full Text Available This paper investigates the H∞ filtering problem of discrete singular Markov jump systems (SMJSs with mode-dependent time delay based on T-S fuzzy model. First, by Lyapunov-Krasovskii functional approach, a delay-dependent sufficient condition on H∞-disturbance attenuation is presented, in which both stability and prescribed H∞ performance are required to be achieved for the filtering-error systems. Then, based on the condition, the delay-dependent H∞ filter design scheme for SMJSs with mode-dependent time delay based on T-S fuzzy model is developed in term of linear matrix inequality (LMI. Finally, an example is given to illustrate the effectiveness of the result.

  1. Stability and Bifurcation of a Computer Virus Propagation Model with Delay and Incomplete Antivirus Ability

    Directory of Open Access Journals (Sweden)

    Jianguo Ren

    2014-01-01

    Full Text Available A new computer virus propagation model with delay and incomplete antivirus ability is formulated and its global dynamics is analyzed. The existence and stability of the equilibria are investigated by resorting to the threshold value R0. By analysis, it is found that the model may undergo a Hopf bifurcation induced by the delay. Correspondingly, the critical value of the Hopf bifurcation is obtained. Using Lyapunov functional approach, it is proved that, under suitable conditions, the unique virus-free equilibrium is globally asymptotically stable if R01. Numerical examples are presented to illustrate possible behavioral scenarios of the mode.

  2. Stability and attractive basins of multiple equilibria in delayed two-neuron networks

    International Nuclear Information System (INIS)

    Huang Yu-Jiao; Zhang Hua-Guang; Wang Zhan-Shan

    2012-01-01

    Multiple stability for two-dimensional delayed recurrent neural networks with piecewise linear activation functions of 2r (r ≥ 1) corner points is studied. Sufficient conditions are established for checking the existence of (2r + 1) 2 equilibria in delayed recurrent neural networks. Under these conditions, (r + 1) 2 equilibria are locally exponentially stable, and (2r + 1) 2 — (r + 1) 2 — r 2 equilibria are unstable. Attractive basins of stable equilibria are estimated, which are larger than invariant sets derived by decomposing state space. One example is provided to illustrate the effectiveness of our results. (general)

  3. Global stability, periodic solutions, and optimal control in a nonlinear differential delay model

    Directory of Open Access Journals (Sweden)

    Anatoli F. Ivanov

    2010-09-01

    Full Text Available A nonlinear differential equation with delay serving as a mathematical model of several applied problems is considered. Sufficient conditions for the global asymptotic stability and for the existence of periodic solutions are given. Two particular applications are treated in detail. The first one is a blood cell production model by Mackey, for which new periodicity criteria are derived. The second application is a modified economic model with delay due to Ramsey. An optimization problem for a maximal consumption is stated and solved for the latter.

  4. Global asymptotic stability analysis of bidirectional associative memory neural networks with distributed delays and impulse

    International Nuclear Information System (INIS)

    Huang Zaitang; Luo Xiaoshu; Yang Qigui

    2007-01-01

    Many systems existing in physics, chemistry, biology, engineering and information science can be characterized by impulsive dynamics caused by abrupt jumps at certain instants during the process. These complex dynamical behaviors can be model by impulsive differential system or impulsive neural networks. This paper formulates and studies a new model of impulsive bidirectional associative memory (BAM) networks with finite distributed delays. Several fundamental issues, such as global asymptotic stability and existence and uniqueness of such BAM neural networks with impulse and distributed delays, are established

  5. Global Exponential Stability of Periodic Oscillation for Nonautonomous BAM Neural Networks with Distributed Delay

    Directory of Open Access Journals (Sweden)

    Hongli Liu

    2009-01-01

    Full Text Available We derive a new criterion for checking the global stability of periodic oscillation of bidirectional associative memory (BAM neural networks with periodic coefficients and distributed delay, and find that the criterion relies on the Lipschitz constants of the signal transmission functions, weights of the neural network, and delay kernels. The proposed model transforms the original interacting network into matrix analysis problem which is easy to check, thereby significantly reducing the computational complexity and making analysis of periodic oscillation for even large-scale networks.

  6. Robust stability for uncertain stochastic fuzzy BAM neural networks with time-varying delays

    Science.gov (United States)

    Syed Ali, M.; Balasubramaniam, P.

    2008-07-01

    In this Letter, by utilizing the Lyapunov functional and combining with the linear matrix inequality (LMI) approach, we analyze the global asymptotic stability of uncertain stochastic fuzzy Bidirectional Associative Memory (BAM) neural networks with time-varying delays which are represented by the Takagi-Sugeno (TS) fuzzy models. A new class of uncertain stochastic fuzzy BAM neural networks with time varying delays has been studied and sufficient conditions have been derived to obtain conservative result in stochastic settings. The developed results are more general than those reported in the earlier literatures. In addition, the numerical examples are provided to illustrate the applicability of the result using LMI toolbox in MATLAB.

  7. Robust stability for uncertain stochastic fuzzy BAM neural networks with time-varying delays

    International Nuclear Information System (INIS)

    Syed Ali, M.; Balasubramaniam, P.

    2008-01-01

    In this Letter, by utilizing the Lyapunov functional and combining with the linear matrix inequality (LMI) approach, we analyze the global asymptotic stability of uncertain stochastic fuzzy Bidirectional Associative Memory (BAM) neural networks with time-varying delays which are represented by the Takagi-Sugeno (TS) fuzzy models. A new class of uncertain stochastic fuzzy BAM neural networks with time varying delays has been studied and sufficient conditions have been derived to obtain conservative result in stochastic settings. The developed results are more general than those reported in the earlier literatures. In addition, the numerical examples are provided to illustrate the applicability of the result using LMI toolbox in MATLAB

  8. Robust Stability of Scaled-Four-Channel Teleoperation with Internet Time-Varying Delays

    Directory of Open Access Journals (Sweden)

    Emma Delgado

    2016-04-01

    Full Text Available We describe the application of a generic stability framework for a teleoperation system under time-varying delay conditions, as addressed in a previous work, to a scaled-four-channel (γ-4C control scheme. Described is how varying delays are dealt with by means of dynamic encapsulation, giving rise to mu-test conditions for robust stability and offering an appealing frequency technique to deal with the stability robustness of the architecture. We discuss ideal transparency problems and we adapt classical solutions so that controllers are proper, without single or double differentiators, and thus avoid the negative effects of noise. The control scheme was fine-tuned and tested for complete stability to zero of the whole state, while seeking a practical solution to the trade-off between stability and transparency in the Internet-based teleoperation. These ideas were tested on an Internet-based application with two Omni devices at remote laboratory locations via simulations and real remote experiments that achieved robust stability, while performing well in terms of position synchronization and force transparency.

  9. Robust Stability of Scaled-Four-Channel Teleoperation with Internet Time-Varying Delays.

    Science.gov (United States)

    Delgado, Emma; Barreiro, Antonio; Falcón, Pablo; Díaz-Cacho, Miguel

    2016-04-26

    We describe the application of a generic stability framework for a teleoperation system under time-varying delay conditions, as addressed in a previous work, to a scaled-four-channel (γ-4C) control scheme. Described is how varying delays are dealt with by means of dynamic encapsulation, giving rise to mu-test conditions for robust stability and offering an appealing frequency technique to deal with the stability robustness of the architecture. We discuss ideal transparency problems and we adapt classical solutions so that controllers are proper, without single or double differentiators, and thus avoid the negative effects of noise. The control scheme was fine-tuned and tested for complete stability to zero of the whole state, while seeking a practical solution to the trade-off between stability and transparency in the Internet-based teleoperation. These ideas were tested on an Internet-based application with two Omni devices at remote laboratory locations via simulations and real remote experiments that achieved robust stability, while performing well in terms of position synchronization and force transparency.

  10. Local Properties of Solutions to Non-Autonomous Parabolic PDEs with State-Dependent Delays

    Czech Academy of Sciences Publication Activity Database

    Rezunenko, Oleksandr

    2012-01-01

    Roč. 2, č. 2 (2012), s. 56-71 ISSN 2158-611X R&D Projects: GA ČR(CZ) GAP103/12/2431 Institutional support: RVO:67985556 Keywords : partial differential equations * state-dependent delay * invariance principle Subject RIV: BC - Control Systems Theory http://library.utia.cas.cz/separaty/2012/AS/rezunenko- local properties of solutions to non-autonomous parabolic PDEs with state-dependent delay s.pdf

  11. Convergence and stability of the exponential Euler method for semi-linear stochastic delay differential equations.

    Science.gov (United States)

    Zhang, Ling

    2017-01-01

    The main purpose of this paper is to investigate the strong convergence and exponential stability in mean square of the exponential Euler method to semi-linear stochastic delay differential equations (SLSDDEs). It is proved that the exponential Euler approximation solution converges to the analytic solution with the strong order [Formula: see text] to SLSDDEs. On the one hand, the classical stability theorem to SLSDDEs is given by the Lyapunov functions. However, in this paper we study the exponential stability in mean square of the exact solution to SLSDDEs by using the definition of logarithmic norm. On the other hand, the implicit Euler scheme to SLSDDEs is known to be exponentially stable in mean square for any step size. However, in this article we propose an explicit method to show that the exponential Euler method to SLSDDEs is proved to share the same stability for any step size by the property of logarithmic norm.

  12. Convergence and stability of the exponential Euler method for semi-linear stochastic delay differential equations

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    Ling Zhang

    2017-10-01

    Full Text Available Abstract The main purpose of this paper is to investigate the strong convergence and exponential stability in mean square of the exponential Euler method to semi-linear stochastic delay differential equations (SLSDDEs. It is proved that the exponential Euler approximation solution converges to the analytic solution with the strong order 1 2 $\\frac{1}{2}$ to SLSDDEs. On the one hand, the classical stability theorem to SLSDDEs is given by the Lyapunov functions. However, in this paper we study the exponential stability in mean square of the exact solution to SLSDDEs by using the definition of logarithmic norm. On the other hand, the implicit Euler scheme to SLSDDEs is known to be exponentially stable in mean square for any step size. However, in this article we propose an explicit method to show that the exponential Euler method to SLSDDEs is proved to share the same stability for any step size by the property of logarithmic norm.

  13. Bifurcation and Stability in a Delayed Predator-Prey Model with Mixed Functional Responses

    Science.gov (United States)

    Yafia, R.; Aziz-Alaoui, M. A.; Merdan, H.; Tewa, J. J.

    2015-06-01

    The model analyzed in this paper is based on the model set forth by Aziz Alaoui et al. [Aziz Alaoui & Daher Okiye, 2003; Nindjin et al., 2006] with time delay, which describes the competition between the predator and prey. This model incorporates a modified version of the Leslie-Gower functional response as well as that of Beddington-DeAngelis. In this paper, we consider the model with one delay consisting of a unique nontrivial equilibrium E* and three others which are trivial. Their dynamics are studied in terms of local and global stabilities and of the description of Hopf bifurcation at E*. At the third trivial equilibrium, the existence of the Hopf bifurcation is proven as the delay (taken as a parameter of bifurcation) that crosses some critical values.

  14. Relationship between Social Media Dependency, Perceived Parenting Style, Delay of Gratification, and Narcissism

    OpenAIRE

    Derebaşı, Muhammet Burak

    2015-01-01

    Worldwide, there is an increasing interest to study social media dependency. Currently, most of the researches compare social media dependency with other dependencies such as substance abuse and gambling. Although, there is limited research to investigate the effect of personality on social media dependency. Therefore, the main aim of the current study was to examine the predictor roles of narcissism, perceived parenting styles and delay of gratification on social media dependency. A total of...

  15. Stability analysis and synchronization in discrete-time complex networks with delayed coupling

    Science.gov (United States)

    Cheng, Ranran; Peng, Mingshu; Yu, Weibin; Sun, Bo; Yu, Jinchen

    2013-12-01

    A new network of coupled maps is proposed in which the connections between units involve no delays but the intra-neural communication does, whereas in the work of Atay et al. [Phys. Rev. Lett. 92, 144101 (2004)], the focus is on information processing delayed by the inter-neural communication. We show that the synchronization of the network depends on not only the intrinsic dynamical features and inter-connection topology (characterized by the spectrum of the graph Laplacian) but also the delays and the coupling strength. There are two main findings: (i) the more neighbours, the easier to be synchronized; (ii) odd delays are easier to be synchronized than even ones. In addition, compared with those discussed by Atay et al. [Phys. Rev. Lett. 92, 144101 (2004)], our model has a better synchronizability for regular networks and small-world variants.

  16. Exponential Stability of the Monotubular Heat Exchanger Equation with Time Delay in Boundary Observation

    Directory of Open Access Journals (Sweden)

    Xue-Lian Jin

    2017-01-01

    Full Text Available The exponential stability of the monotubular heat exchanger equation with boundary observation possessing a time delay and inner control was investigated. Firstly, the close-loop system was translated into an abstract Cauchy problem in the suitable state space. A uniformly bounded C0-semigroup generated by the close-loop system, which implies that the unique solution of the system exists, was shown. Secondly, the spectrum configuration of the closed-loop system was analyzed and the eventual differentiability and the eventual compactness of the semigroup were shown by the resolvent estimates on some resolvent sets. This implies that the spectrum-determined growth assumption holds. Finally, a sufficient condition, which is related to the physical parameters in the system and is independent of the time delay, of the exponential stability of the closed-loop system was given.

  17. Stability in a Simple Food Chain System with Michaelis-Menten Functional Response and Nonlocal Delays

    Directory of Open Access Journals (Sweden)

    Wenzhen Gan

    2013-01-01

    Full Text Available This paper is concerned with the asymptotical behavior of solutions to the reaction-diffusion system under homogeneous Neumann boundary condition. By taking food ingestion and species' moving into account, the model is further coupled with Michaelis-Menten type functional response and nonlocal delay. Sufficient conditions are derived for the global stability of the positive steady state and the semitrivial steady state of the proposed problem by using the Lyapunov functional. Our results show that intraspecific competition benefits the coexistence of prey and predator. Furthermore, the introduction of Michaelis-Menten type functional response positively affects the coexistence of prey and predator, and the nonlocal delay is harmless for stabilities of all nonnegative steady states of the system. Numerical simulations are carried out to illustrate the main results.

  18. Stability in Cohen Grossberg-type bidirectional associative memory neural networks with time-varying delays

    Science.gov (United States)

    Cao, Jinde; Song, Qiankun

    2006-07-01

    In this paper, the exponential stability problem is investigated for a class of Cohen-Grossberg-type bidirectional associative memory neural networks with time-varying delays. By using the analysis method, inequality technique and the properties of an M-matrix, several novel sufficient conditions ensuring the existence, uniqueness and global exponential stability of the equilibrium point are derived. Moreover, the exponential convergence rate is estimated. The obtained results are less restrictive than those given in the earlier literature, and the boundedness and differentiability of the activation functions and differentiability of the time-varying delays are removed. Two examples with their simulations are given to show the effectiveness of the obtained results.

  19. A general framework for global asymptotic stability analysis of delayed neural networks based on LMI approach

    International Nuclear Information System (INIS)

    Cao Jinde; Ho, Daniel W.C.

    2005-01-01

    In this paper, global asymptotic stability is discussed for neural networks with time-varying delay. Several new criteria in matrix inequality form are given to ascertain the uniqueness and global asymptotic stability of equilibrium point for neural networks with time-varying delay based on Lyapunov method and Linear Matrix Inequality (LMI) technique. The proposed LMI approach has the advantage of considering the difference of neuronal excitatory and inhibitory efforts, which is also computationally efficient as it can be solved numerically using recently developed interior-point algorithm. In addition, the proposed results generalize and improve previous works. The obtained criteria also combine two existing conditions into one generalized condition in matrix form. An illustrative example is also given to demonstrate the effectiveness of the proposed results

  20. Novel global robust stability criteria for interval neural networks with multiple time-varying delays

    International Nuclear Information System (INIS)

    Xu Shengyuan; Lam, James; Ho, Daniel W.C.

    2005-01-01

    This Letter is concerned with the problem of robust stability analysis for interval neural networks with multiple time-varying delays and parameter uncertainties. The parameter uncertainties are assumed to be bounded in given compact sets and the activation functions are supposed to be bounded and globally Lipschitz continuous. A sufficient condition is obtained by means of Lyapunov functionals, which guarantees the existence, uniqueness and global asymptotic stability of the delayed neural network for all admissible uncertainties. This condition is in terms of a linear matrix inequality (LMI), which can be easily checked by using recently developed algorithms in solving LMIs. Finally, a numerical example is provided to demonstrate the effectiveness of the proposed method

  1. Stability and Hopf bifurcation analysis of a prey-predator system with two delays

    International Nuclear Information System (INIS)

    Li Kai; Wei Junjie

    2009-01-01

    In this paper, we have considered a prey-predator model with Beddington-DeAngelis functional response and selective harvesting of predator species. Two delays appear in this model to describe the time that juveniles take to mature. Its dynamics are studied in terms of local analysis and Hopf bifurcation analysis. By analyzing the associated characteristic equation, its linear stability is investigated and Hopf bifurcations are demonstrated. The stability and direction of the Hopf bifurcation are determined by applying the normal form method and the center manifold theory. Numerical simulation results are given to support the theoretical predictions.

  2. Stochastic exponential stability of the delayed reaction-diffusion recurrent neural networks with Markovian jumping parameters

    International Nuclear Information System (INIS)

    Wang Linshan; Zhang Zhe; Wang Yangfan

    2008-01-01

    Some criteria for the global stochastic exponential stability of the delayed reaction-diffusion recurrent neural networks with Markovian jumping parameters are presented. The jumping parameters considered here are generated from a continuous-time discrete-state homogeneous Markov process, which are governed by a Markov process with discrete and finite state space. By employing a new Lyapunov-Krasovskii functional, a linear matrix inequality (LMI) approach is developed to establish some easy-to-test criteria of global exponential stability in the mean square for the stochastic neural networks. The criteria are computationally efficient, since they are in the forms of some linear matrix inequalities

  3. Boundedness and stability for recurrent neural networks with variable coefficients and time-varying delays

    International Nuclear Information System (INIS)

    Liang Jinling; Cao Jinde

    2003-01-01

    In this Letter, the problems of boundedness and stability for a general class of non-autonomous recurrent neural networks with variable coefficients and time-varying delays are analyzed via employing Young inequality technique and Lyapunov method. Some simple sufficient conditions are given for boundedness and stability of the solutions for the recurrent neural networks. These results generalize and improve the previous works, and they are easy to check and apply in practice. Two illustrative examples and their numerical simulations are also given to demonstrate the effectiveness of the proposed results

  4. Stability and periodicity of solutions for delay dynamic systems on time scales

    Directory of Open Access Journals (Sweden)

    Zhi-Qiang Zhu

    2014-04-01

    Full Text Available This article concerns the stability and periodicity of solutions to the delay dynamic system $$ x^{\\triangle}(t=A(t x(t + F(t, x(t, x(g(t+C(t $$ on a time scale. By the inequality technique for vectors, we obtain some stability criteria for the above system. Then, by using the Horn fixed point theorem, we present some conditions under which our system is asymptotically periodic and its periodic solution is unique. In particular, the periodic solution is positive under proper assumptions.

  5. Stability and Hopf bifurcation in a simplified BAM neural network with two time delays.

    Science.gov (United States)

    Cao, Jinde; Xiao, Min

    2007-03-01

    Various local periodic solutions may represent different classes of storage patterns or memory patterns, and arise from the different equilibrium points of neural networks (NNs) by applying Hopf bifurcation technique. In this paper, a bidirectional associative memory NN with four neurons and multiple delays is considered. By applying the normal form theory and the center manifold theorem, analysis of its linear stability and Hopf bifurcation is performed. An algorithm is worked out for determining the direction and stability of the bifurcated periodic solutions. Numerical simulation results supporting the theoretical analysis are also given.

  6. Global exponential stability analysis on impulsive BAM neural networks with distributed delays

    Science.gov (United States)

    Li, Yao-Tang; Yang, Chang-Bo

    2006-12-01

    Using M-matrix and topological degree tool, sufficient conditions are obtained for the existence, uniqueness and global exponential stability of the equilibrium point of bidirectional associative memory (BAM) neural networks with distributed delays and subjected to impulsive state displacements at fixed instants of time by constructing a suitable Lyapunov functional. The results remove the usual assumptions that the boundedness, monotonicity, and differentiability of the activation functions. It is shown that in some cases, the stability criteria can be easily checked. Finally, an illustrative example is given to show the effectiveness of the presented criteria.

  7. Nonlinear Stability and Convergence of Two-Step Runge-Kutta Methods for Volterra Delay Integro-Differential Equations

    Directory of Open Access Journals (Sweden)

    Haiyan Yuan

    2013-01-01

    Full Text Available This paper introduces the stability and convergence of two-step Runge-Kutta methods with compound quadrature formula for solving nonlinear Volterra delay integro-differential equations. First, the definitions of (k,l-algebraically stable and asymptotically stable are introduced; then the asymptotical stability of a (k,l-algebraically stable two-step Runge-Kutta method with 0depends on the compound quadrature formula.

  8. Stability and Sensitive Analysis of a Model with Delay Quorum Sensing

    Directory of Open Access Journals (Sweden)

    Zhonghua Zhang

    2015-01-01

    Full Text Available This paper formulates a delay model characterizing the competition between bacteria and immune system. The center manifold reduction method and the normal form theory due to Faria and Magalhaes are used to compute the normal form of the model, and the stability of two nonhyperbolic equilibria is discussed. Sensitivity analysis suggests that the growth rate of bacteria is the most sensitive parameter of the threshold parameter R0 and should be targeted in the controlling strategies.

  9. Stabilization of a Wireless Networked Control System with Packet Loss and Time Delay: An ADS Approach

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2012-01-01

    Full Text Available The stabilization problem of a wireless networked control system is considered in this paper. Both time delay and packet loss exist simultaneously in the wireless network. The system is modeled as an asynchronous dynamic system (ADS with unstable subsystems. A sufficient condition for the system to be stable is presented. A numerical example is given to demonstrate the effectiveness of the proposed approach.

  10. T-Stability of the Heun Method and Balanced Method for Solving Stochastic Differential Delay Equations

    Directory of Open Access Journals (Sweden)

    Xiaolin Zhu

    2014-01-01

    Full Text Available This paper studies the T-stability of the Heun method and balanced method for solving stochastic differential delay equations (SDDEs. Two T-stable conditions of the Heun method are obtained for two kinds of linear SDDEs. Moreover, two conditions under which the balanced method is T-stable are obtained for two kinds of linear SDDEs. Some numerical examples verify the theoretical results proposed.

  11. Global exponential stability of fuzzy BAM neural networks with time-varying delays

    International Nuclear Information System (INIS)

    Zhang Qianhong; Luo Wei

    2009-01-01

    In this paper, a class of fuzzy bidirectional associated memory (BAM) neural networks with time-varying delays are studied. Employing fixed point theorem, matrix theory and inequality analysis, some sufficient conditions are established for the existence, uniqueness and global exponential stability of equilibrium point. The sufficient conditions are easy to verify at pattern recognition and automatic control. Finally, an example is given to show feasibility and effectiveness of our results.

  12. Global exponential stability of periodic solution for shunting inhibitory CNNs with delays [rapid communication

    Science.gov (United States)

    Li, Yongkun; Liu, Chunchao; Zhu, Lifei

    2005-03-01

    By using the continuation theorem of coincidence degree theory and constructing suitable Lyapunov functions, we study the existence and stability of periodic solution for shunting inhibitory cellular neural networks (SICNNs) with delays x˙ij(t)=-aij(t)xij(t)-∑Bkl∈Nr(i,j)Bijkl(t)fij(xkl(t))xij(t)-∑Ckl∈Nr(i,j)Cijkl(t)gij(xkl(t-τkl))xij(t)+Lij(t).

  13. Exponential stability of delayed recurrent neural networks with Markovian jumping parameters

    International Nuclear Information System (INIS)

    Wang Zidong; Liu Yurong; Yu Li; Liu Xiaohui

    2006-01-01

    In this Letter, the global exponential stability analysis problem is considered for a class of recurrent neural networks (RNNs) with time delays and Markovian jumping parameters. The jumping parameters considered here are generated from a continuous-time discrete-state homogeneous Markov process, which are governed by a Markov process with discrete and finite state space. The purpose of the problem addressed is to derive some easy-to-test conditions such that the dynamics of the neural network is stochastically exponentially stable in the mean square, independent of the time delay. By employing a new Lyapunov-Krasovskii functional, a linear matrix inequality (LMI) approach is developed to establish the desired sufficient conditions, and therefore the global exponential stability in the mean square for the delayed RNNs can be easily checked by utilizing the numerically efficient Matlab LMI toolbox, and no tuning of parameters is required. A numerical example is exploited to show the usefulness of the derived LMI-based stability conditions

  14. Stability analysis for a general age-dependent vaccination model

    International Nuclear Information System (INIS)

    El Doma, M.

    1995-05-01

    An SIR epidemic model of a general age-dependent vaccination model is investigated when the fertility, mortality and removal rates depends on age. We give threshold criteria of the existence of equilibriums and perform stability analysis. Furthermore a critical vaccination coverage that is sufficient to eradicate the disease is determined. (author). 12 refs

  15. Robust stability analysis of Takagi—Sugeno uncertain stochastic fuzzy recurrent neural networks with mixed time-varying delays

    International Nuclear Information System (INIS)

    Ali, M. Syed

    2011-01-01

    In this paper, the global stability of Takagi—Sugeno (TS) uncertain stochastic fuzzy recurrent neural networks with discrete and distributed time-varying delays (TSUSFRNNs) is considered. A novel LMI-based stability criterion is obtained by using Lyapunov functional theory to guarantee the asymptotic stability of TSUSFRNNs. The proposed stability conditions are demonstrated through numerical examples. Furthermore, the supplementary requirement that the time derivative of time-varying delays must be smaller than one is removed. Comparison results are demonstrated to show that the proposed method is more able to guarantee the widest stability region than the other methods available in the existing literature. (general)

  16. The stochastic characteristics stability in the problem of the dynamic filtration with delay

    Science.gov (United States)

    Chashnikov, Mikhail

    2017-07-01

    In this paper thesolution's calculation of linear differential equation with delay is considered. It is supposed that initial conditions are the set with random error and we have chance of updating the solution in periodic timepointswith the same error. The dependence between the estimate dispersion and the measuring error dispersion is recieved.

  17. Robust stability of uncertain Markovian jumping Cohen-Grossberg neural networks with mixed time-varying delays

    International Nuclear Information System (INIS)

    Sheng Li; Yang Huizhong

    2009-01-01

    This paper considers the robust stability of a class of uncertain Markovian jumping Cohen-Grossberg neural networks (UMJCGNNs) with mixed time-varying delays. The parameter uncertainties are norm-bounded and the mixed time-varying delays comprise discrete and distributed time delays. Based on the Lyapunov stability theory and linear matrix inequality (LMI) technique, some robust stability conditions guaranteeing the global robust convergence of the equilibrium point are derived. An example is given to show the effectiveness of the proposed results.

  18. Stability and Hopf Bifurcation of Fractional-Order Complex-Valued Single Neuron Model with Time Delay

    Science.gov (United States)

    Wang, Zhen; Wang, Xiaohong; Li, Yuxia; Huang, Xia

    2017-12-01

    In this paper, the problems of stability and Hopf bifurcation in a class of fractional-order complex-valued single neuron model with time delay are addressed. With the help of the stability theory of fractional-order differential equations and Laplace transforms, several new sufficient conditions, which ensure the stability of the system are derived. Taking the time delay as the bifurcation parameter, Hopf bifurcation is investigated and the critical value of the time delay for the occurrence of Hopf bifurcation is determined. Finally, two representative numerical examples are given to show the effectiveness of the theoretical results.

  19. Positivity of Fundamental Matrix and Exponential Stability of Delay Differential System

    Directory of Open Access Journals (Sweden)

    Alexander Domoshnitsky

    2014-01-01

    Full Text Available The classical Wazewski theorem established that nonpositivity of all nondiagonal elements pij  (i≠j,  i,j=1,…,n is necessary and sufficient for nonnegativity of the fundamental (Cauchy matrix and consequently for applicability of the Chaplygin approach of approximate integration for system of linear ordinary differential equations xi′t+∑j=1n‍pijtxjt=fit,   i=1,…,n. Results on nonnegativity of the Cauchy matrix for system of delay differential equations xi′t+∑j=1n‍pijtxjhijt=fit,   i=1,…,n, which were based on nonpositivity of all diagonal elements, were presented in the previous works. Then examples, which demonstrated that nonpositivity of nondiagonal coefficients pij is not necessary for systems of delay equations, were found. In this paper first sufficient results about nonnegativity of the Cauchy matrix of the delay system without this assumption are proven. A necessary condition of nonnegativity of the Cauchy matrix is proposed. On the basis of these results on nonnegativity of the Cauchy matrix, necessary and sufficient conditions of the exponential stability of the delay system are obtained.

  20. Global stability of stochastic high-order neural networks with discrete and distributed delays

    International Nuclear Information System (INIS)

    Wang Zidong; Fang Jianan; Liu Xiaohui

    2008-01-01

    High-order neural networks can be considered as an expansion of Hopfield neural networks, and have stronger approximation property, faster convergence rate, greater storage capacity, and higher fault tolerance than lower-order neural networks. In this paper, the global asymptotic stability analysis problem is considered for a class of stochastic high-order neural networks with discrete and distributed time-delays. Based on an Lyapunov-Krasovskii functional and the stochastic stability analysis theory, several sufficient conditions are derived, which guarantee the global asymptotic convergence of the equilibrium point in the mean square. It is shown that the stochastic high-order delayed neural networks under consideration are globally asymptotically stable in the mean square if two linear matrix inequalities (LMIs) are feasible, where the feasibility of LMIs can be readily checked by the Matlab LMI toolbox. It is also shown that the main results in this paper cover some recently published works. A numerical example is given to demonstrate the usefulness of the proposed global stability criteria

  1. Local stability and Hopf bifurcation in small-world delayed networks

    International Nuclear Information System (INIS)

    Li Chunguang; Chen Guanrong

    2004-01-01

    The notion of small-world networks, recently introduced by Watts and Strogatz, has attracted increasing interest in studying the interesting properties of complex networks. Notice that, a signal or influence travelling on a small-world network often is associated with time-delay features, which are very common in biological and physical networks. Also, the interactions within nodes in a small-world network are often nonlinear. In this paper, we consider a small-world networks model with nonlinear interactions and time delays, which was recently considered by Yang. By choosing the nonlinear interaction strength as a bifurcation parameter, we prove that Hopf bifurcation occurs. We determine the stability of the bifurcating periodic solutions and the direction of the Hopf bifurcation by applying the normal form theory and the center manifold theorem. Finally, we show a numerical example to verify the theoretical analysis

  2. Local stability and Hopf bifurcation in small-world delayed networks

    Energy Technology Data Exchange (ETDEWEB)

    Li Chunguang E-mail: cgli@uestc.edu.cn; Chen Guanrong E-mail: gchen@ee.cityu.edu.hk

    2004-04-01

    The notion of small-world networks, recently introduced by Watts and Strogatz, has attracted increasing interest in studying the interesting properties of complex networks. Notice that, a signal or influence travelling on a small-world network often is associated with time-delay features, which are very common in biological and physical networks. Also, the interactions within nodes in a small-world network are often nonlinear. In this paper, we consider a small-world networks model with nonlinear interactions and time delays, which was recently considered by Yang. By choosing the nonlinear interaction strength as a bifurcation parameter, we prove that Hopf bifurcation occurs. We determine the stability of the bifurcating periodic solutions and the direction of the Hopf bifurcation by applying the normal form theory and the center manifold theorem. Finally, we show a numerical example to verify the theoretical analysis.

  3. Stability diagrams for continuous wide-range control of two mutually delay-coupled semiconductor lasers

    International Nuclear Information System (INIS)

    Junges, Leandro; Gallas, Jason A C

    2015-01-01

    The dynamics of two mutually delay-coupled semiconductor lasers has been frequently studied experimentally, numerically, and analytically either for weak or strong detuning between the lasers. Here, we present a systematic numerical investigation spanning all detuning ranges. We report high-resolution stability diagrams for wide ranges of the main control parameters of the laser, as described by the Lang–Kobayashi model. In particular, we detail the parameter influence on dynamical performance and map the distribution of chaotic pulsations and self-generated periodic spiking with arbitrary periodicity. Special attention is given to the unfolding of regular pulse packages for both symmetric and non-symmetric configurations with respect to detuning. The influence of the delay –time on the self-organization of periodic and chaotic laser phases as a function of the coupling and detuning is also described in detail. (paper)

  4. Stability of a general delayed virus dynamics model with humoral immunity and cellular infection

    Science.gov (United States)

    Elaiw, A. M.; Raezah, A. A.; Alofi, A. S.

    2017-06-01

    In this paper, we investigate the dynamical behavior of a general nonlinear model for virus dynamics with virus-target and infected-target incidences. The model incorporates humoral immune response and distributed time delays. The model is a four dimensional system of delay differential equations where the production and removal rates of the virus and cells are given by general nonlinear functions. We derive the basic reproduction parameter R˜0 G and the humoral immune response activation number R˜1 G and establish a set of conditions on the general functions which are sufficient to determine the global dynamics of the models. We use suitable Lyapunov functionals and apply LaSalle's invariance principle to prove the global asymptotic stability of the all equilibria of the model. We confirm the theoretical results by numerical simulations.

  5. Finite-Time Stability for Fractional-Order Bidirectional Associative Memory Neural Networks with Time Delays

    Science.gov (United States)

    Xu, Chang-Jin; Li, Pei-Luan; Pang, Yi-Cheng

    2017-02-01

    This paper is concerned with fractional-order bidirectional associative memory (BAM) neural networks with time delays. Applying Laplace transform, the generalized Gronwall inequality and estimates of Mittag-Leffler functions, some sufficient conditions which ensure the finite-time stability of fractional-order bidirectional associative memory neural networks with time delays are obtained. Two examples with their simulations are given to illustrate the theoretical findings. Our results are new and complement previously known results. Supported by National Natural Science Foundation of China under Grant Nos.~61673008, 11261010, 11101126, Project of High-Level Innovative Talents of Guizhou Province ([2016]5651), Natural Science and Technology Foundation of Guizhou Province (J[2015]2025 and J[2015]2026), 125 Special Major Science and Technology of Department of Education of Guizhou Province ([2012]011) and Natural Science Foundation of the Education Department of Guizhou Province (KY[2015]482)

  6. Global Exponential Stability of Positive Almost Periodic Solutions for a Fishing Model with a Time-Varying Delay

    Directory of Open Access Journals (Sweden)

    Hong Zhang

    2014-01-01

    Full Text Available This paper is concerned with a nonautonomous fishing model with a time-varying delay. Under proper conditions, we employ a novel argument to establish a criterion on the global exponential stability of positive almost periodic solutions of the model with almost periodic coefficients and delays. Moreover, an example and its numerical simulation are given to illustrate the main results.

  7. Analysis of incident-energy dependence of delayed neutron yields in actinides

    Energy Technology Data Exchange (ETDEWEB)

    Nasir, Mohamad Nasrun bin Mohd, E-mail: monasr211@gmail.com; Metorima, Kouhei, E-mail: kohei.m2420@hotmail.co.jp; Ohsawa, Takaaki, E-mail: ohsawa@mvg.biglobe.ne.jp; Hashimoto, Kengo, E-mail: kengoh@pp.iij4u.or.jp [Graduate School of Science and Engineering, Kindai University, Kowakae, Higashi-Osaka, 577-8502 (Japan)

    2015-04-29

    The changes of delayed neutron yields (ν{sub d}) of Actinides have been analyzed for incident energy up to 20MeV using realized data of precursor after prompt neutron emission, from semi-empirical model, and delayed neutron emission probability data (P{sub n}) to carry out a summation method. The evaluated nuclear data of the delayed neutron yields of actinide nuclides are still uncertain at the present and the cause of the energy dependence has not been fully understood. In this study, the fission yields of precursor were calculated considering the change of the fission fragment mass yield based on the superposition of fives Gaussian distribution; and the change of the prompt neutrons number associated with the incident energy dependence. Thus, the incident energy dependent behavior of delayed neutron was analyzed.The total number of delayed neutron is expressed as ν{sub d}=∑Y{sub i} • P{sub ni} in the summation method, where Y{sub i} is the mass yields of precursor i and P{sub ni} is the delayed neutron emission probability of precursor i. The value of Y{sub i} is derived from calculation of post neutron emission mass distribution using 5 Gaussian equations with the consideration of large distribution of the fission fragments. The prompt neutron emission ν{sub p} increases at higher incident-energy but there are two different models; one model says that the fission fragment mass dependence that prompt neutron emission increases uniformly regardless of the fission fragments mass; and the other says that the major increases occur at heavy fission fragments area. In this study, the changes of delayed neutron yields by the two models have been investigated.

  8. Dependence of stability of metastable superconductors on copper fraction

    International Nuclear Information System (INIS)

    Elrod, S.A.; Lue, J.W.; Miller, J.R.; Dresner, L.

    1980-12-01

    The stability of composite superconductors operating in the metastable regime depends upon such factors as matrix resistivity, cooled surface dimensions, fraction of critical current, and volume fraction of stabilizer. By assuming constant thermophysical properties, we developed analytic expressions for the energy and voltage of the minimum propagating zone (MPZ). With other factors held constant, these expressions have been used to predict composite superconductor stability as a function of copper fraction: lower copper fractions lead to higher MPZ energies. MPZ voltages have been measured for three NbTi/Cu composites having different copper fractions and different critical current densities for several magnetic fields and transport currents. Experimental MPZ voltages have been used to calculate an effective heat transfer coefficient, which is subsequently used to calculate the MPZ energy. The experimental MPZ energies support the theoretical expectation that lower copper fractions lead to higher stability in the metastable regime

  9. Existence and exponential stability of traveling waves for delayed reaction-diffusion systems

    Science.gov (United States)

    Hsu, Cheng-Hsiung; Yang, Tzi-Sheng; Yu, Zhixian

    2018-03-01

    The purpose of this work is to investigate the existence and exponential stability of traveling wave solutions for general delayed multi-component reaction-diffusion systems. Following the monotone iteration scheme via an explicit construction of a pair of upper and lower solutions, we first obtain the existence of monostable traveling wave solutions connecting two different equilibria. Then, applying the techniques of weighted energy method and comparison principle, we show that all solutions of the Cauchy problem for the considered systems converge exponentially to traveling wave solutions provided that the initial perturbations around the traveling wave fronts belong to a suitable weighted Sobolev space.

  10. The breaking of a delayed ring neural network contributes to stability: The rule and exceptions.

    Science.gov (United States)

    Khokhlova, T N; Kipnis, M M

    2013-12-01

    We prove that in our mathematical model the breaking of a delayed ring neural network extends the stability region in the parameters space, if the number of the neurons is sufficiently large. If the number of neurons is small, then a "paradoxical" region exists in the parameters space, wherein the ring neural configuration is stable, while the linear one is unstable. We study the conditions under which the paradoxical region is nonempty. We discuss how our mathematical modeling reflects neurosurgical operations with the severing of particular connections in the brain. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. New exponential stability conditions for linear delayed systems of differential equations

    Directory of Open Access Journals (Sweden)

    Leonid Berezansky

    2016-08-01

    where $t\\ge 0$, $m$ and $r_{ij}$, $i,j=1,\\dots,m$ are natural numbers, $a_{ij}^{k}\\colon [0,\\infty\\to\\mathbb{R}$ are measurable coefficients, and $h_{ij}^{k}\\colon [0,\\infty\\to\\mathbb{R}$ are measurable delays. The progress was achieved by using a new technique making it possible to replace the constant $1$ by the constant $1+{1}/{\\mathrm{e}}$ on the right-hand sides of crucial inequalities ensuring exponential stability.

  12. Global exponential stability of BAM neural networks with transmission delays and nonlinear impulses

    International Nuclear Information System (INIS)

    Huang Zhenkun; Xia Yonghui

    2008-01-01

    In this paper, a class of bidirectional associative memory (BAM) networks with transmission delays and nonlinear impulses are studied. Some new sufficient conditions are established for the existence and global exponential stability of a unique equilibrium, which generalize and improve the previously known results. The sufficient conditions are easy to verify and when the impulsive jumps are linear or absent the results reduce to those of common impulsive or non-impulsive systems. Finally, an example is given to show the feasibility and effectiveness of our results

  13. Global Exponential Stability of Delayed Cohen-Grossberg BAM Neural Networks with Impulses on Time Scales

    Directory of Open Access Journals (Sweden)

    Yongkun Li

    2009-01-01

    Full Text Available Based on the theory of calculus on time scales, the homeomorphism theory, Lyapunov functional method, and some analysis techniques, sufficient conditions are obtained for the existence, uniqueness, and global exponential stability of the equilibrium point of Cohen-Grossberg bidirectional associative memory (BAM neural networks with distributed delays and impulses on time scales. This is the first time applying the time-scale calculus theory to unify the discrete-time and continuous-time Cohen-Grossberg BAM neural network with impulses under the same framework.

  14. Exponential p-stability of delayed Cohen-Grossberg-type BAM neural networks with impulses

    International Nuclear Information System (INIS)

    Xia Yonghui; Huang Zhenkun; Han Maoan

    2008-01-01

    An impulsive Cohen-Grossberg-type bidirectional associative memory (BAM) neural networks with distributed delays is studied. Some new sufficient conditions are established for the existence and global exponential stability of a unique equilibrium without strict conditions imposed on self regulation functions. The approaches are based on Laypunov-Kravsovskii functional and homeomorphism theory. When our results are applied to the BAM neural networks, our results generalize some previously known results. It is believed that these results are significant and useful for the design and applications of Cohen-Grossberg-type bidirectional associative memory networks

  15. Global exponential stability of periodic solution for shunting inhibitory CNNs with delays

    International Nuclear Information System (INIS)

    Li Yongkun; Liu Chunchao; Zhu Lifei

    2005-01-01

    By using the continuation theorem of coincidence degree theory and constructing suitable Lyapunov functions, we study the existence and stability of periodic solution for shunting inhibitory cellular neural networks (SICNNs) with delays x-bar ij (t)=-a ij (t)x ij (t)--bar B kl -bar Nr(i,j)B ij kl (t)f ij (x kl (t))x ij (t)--bar C kl -bar Nr(i,j)C ij kl (t)g ij (x kl (t-τ kl ))x ij (t)+L ij (t)

  16. Global exponential stability and existence of periodic solutions of CNNs with delays

    Science.gov (United States)

    Dong, Meifang

    2002-07-01

    In this Letter, we establish general sufficient conditions for global exponential stability and existence of periodic solutions of a class of cellular neural networks (CNNs) with delays. The key to proving the sufficient conditions is the construction of a new Lyapunov functional. An elementary inequality, which may be of independent interest, has been employed in the proof. Checking the sufficient conditions is often reduced to checking some algebraic relations among certain set of parameter. Our sufficient conditions recover the known results in literature as special cases. Finally, we give two examples to illustrate the usage of our main results.

  17. Global stability and existence of periodic solutions of discrete delayed cellular neural networks

    International Nuclear Information System (INIS)

    Li Yongkun

    2004-01-01

    We use the continuation theorem of coincidence degree theory and Lyapunov functions to study the existence and stability of periodic solutions for the discrete cellular neural networks (CNNs) with delays xi(n+1)=xi(n)e-bi(n)h+θi(h)-bar j=1maij(n)fj(xj(n))+θi(h)-bar j=1mbij(n)fj(xj(n- τij(n)))+θi(h)Ii(n),i=1,2,...,m. We obtain some sufficient conditions to ensure that for the networks there exists a unique periodic solution, and all its solutions converge to such a periodic solution

  18. Stability Analysis and H∞ Model Reduction for Switched Discrete-Time Time-Delay Systems

    Directory of Open Access Journals (Sweden)

    Zheng-Fan Liu

    2014-01-01

    Full Text Available This paper is concerned with the problem of exponential stability and H∞ model reduction of a class of switched discrete-time systems with state time-varying delay. Some subsystems can be unstable. Based on the average dwell time technique and Lyapunov-Krasovskii functional (LKF approach, sufficient conditions for exponential stability with H∞ performance of such systems are derived in terms of linear matrix inequalities (LMIs. For the high-order systems, sufficient conditions for the existence of reduced-order model are derived in terms of LMIs. Moreover, the error system is guaranteed to be exponentially stable and an H∞ error performance is guaranteed. Numerical examples are also given to demonstrate the effectiveness and reduced conservatism of the obtained results.

  19. Global asymptotic stability to a generalized Cohen-Grossberg BAM neural networks of neutral type delays.

    Science.gov (United States)

    Zhang, Zhengqiu; Liu, Wenbin; Zhou, Dongming

    2012-01-01

    In this paper, we first discuss the existence of a unique equilibrium point of a generalized Cohen-Grossberg BAM neural networks of neutral type delays by means of the Homeomorphism theory and inequality technique. Then, by applying the existence result of an equilibrium point and constructing a Lyapunov functional, we study the global asymptotic stability of the equilibrium solution to the above Cohen-Grossberg BAM neural networks of neutral type. In our results, the hypothesis for boundedness in the existing paper, which discussed Cohen-Grossberg neural networks of neutral type on the activation functions, are removed. Finally, we give an example to demonstrate the validity of our global asymptotic stability result for the above neural networks. Copyright © 2011 Elsevier Ltd. All rights reserved.

  20. Analysis of stability and Hopf bifurcation for a delayed logistic equation

    International Nuclear Information System (INIS)

    Sun Chengjun; Han Maoan; Lin Yiping

    2007-01-01

    The dynamics of a logistic equation with discrete delay are investigated, together with the local and global stability of the equilibria. In particular, the conditions under which a sequence of Hopf bifurcations occur at the positive equilibrium are obtained. Explicit algorithm for determining the stability of the bifurcating periodic solutions and the direction of the Hopf bifurcation are derived by using the theory of normal form and center manifold [Hassard B, Kazarino D, Wan Y. Theory and applications of Hopf bifurcation. Cambridge: Cambridge University Press; 1981.]. Global existence of periodic solutions is also established by using a global Hopf bifurcation result of Wu [Symmetric functional differential equations and neural networks with memory. Trans Amer Math Soc 350:1998;4799-38.

  1. Singular Hopf bifurcation in a differential equation with large state-dependent delay.

    Science.gov (United States)

    Kozyreff, G; Erneux, T

    2014-02-08

    We study the onset of sustained oscillations in a classical state-dependent delay (SDD) differential equation inspired by control theory. Owing to the large delays considered, the Hopf bifurcation is singular and the oscillations rapidly acquire a sawtooth profile past the instability threshold. Using asymptotic techniques, we explicitly capture the gradual change from nearly sinusoidal to sawtooth oscillations. The dependence of the delay on the solution can be either linear or nonlinear, with at least quadratic dependence. In the former case, an asymptotic connection is made with the Rayleigh oscillator. In the latter, van der Pol's equation is derived for the small-amplitude oscillations. SDD differential equations are currently the subject of intense research in order to establish or amend general theorems valid for constant-delay differential equation, but explicit analytical construction of solutions are rare. This paper illustrates the use of singular perturbation techniques and the unusual way in which solvability conditions can arise for SDD problems with large delays.

  2. State estimation for discrete-time Markovian jumping neural networks with mixed mode-dependent delays

    International Nuclear Information System (INIS)

    Liu Yurong; Wang Zidong; Liu Xiaohui

    2008-01-01

    In this Letter, we investigate the state estimation problem for a new class of discrete-time neural networks with Markovian jumping parameters as well as mode-dependent mixed time-delays. The parameters of the discrete-time neural networks are subject to the switching from one mode to another at different times according to a Markov chain, and the mixed time-delays consist of both discrete and distributed delays that are dependent on the Markovian jumping mode. New techniques are developed to deal with the mixed time-delays in the discrete-time setting, and a novel Lyapunov-Krasovskii functional is put forward to reflect the mode-dependent time-delays. Sufficient conditions are established in terms of linear matrix inequalities (LMIs) that guarantee the existence of the state estimators. We show that both the existence conditions and the explicit expression of the desired estimator can be characterized in terms of the solution to an LMI. A numerical example is exploited to show the usefulness of the derived LMI-based conditions

  3. An experimental field study of delayed density dependence in natural populations of Aedes albopictus.

    Directory of Open Access Journals (Sweden)

    Rachael K Walsh

    Full Text Available Aedes albopictus, a species known to transmit dengue and chikungunya viruses, is primarily a container-inhabiting mosquito. The potential for pathogen transmission by Ae. albopictus has increased our need to understand its ecology and population dynamics. Two parameters that we know little about are the impact of direct density-dependence and delayed density-dependence in the larval stage. The present study uses a manipulative experimental design, under field conditions, to understand the impact of delayed density dependence in a natural population of Ae. albopictus in Raleigh, North Carolina. Twenty liter buckets, divided in half prior to experimentation, placed in the field accumulated rainwater and detritus, providing oviposition and larval production sites for natural populations of Ae. albopictus. Two treatments, a larvae present and larvae absent treatment, were produced in each bucket. After five weeks all larvae were removed from both treatments and the buckets were covered with fine mesh cloth. Equal numbers of first instars were added to both treatments in every bucket. Pupae were collected daily and adults were frozen as they emerged. We found a significant impact of delayed density-dependence on larval survival, development time and adult body size in containers with high larval densities. Our results indicate that delayed density-dependence will have negative impacts on the mosquito population when larval densities are high enough to deplete accessible nutrients faster than the rate of natural food accumulation.

  4. Simulation of the Nonlinear Dose Dependence of Stabilized Point Defects

    International Nuclear Information System (INIS)

    Chen, R; Pagonis, V; Lawless, J L

    2010-01-01

    The dose dependence of the concentration of point defects in alkali-halides as well as other crystals, as exhibited by the dependence of the thermoluminescence (TL), optical absorption and ESR on the dose of non-ionizing UV excitation is studied using numerical simulation. The relevant set of coupled rate equations are first written and plausible sets of trapping parameters are chosen. Instead of using simplifying assumptions previously used for reaching conclusions concerning this dose behavior, exact numerical solutions have now been reached. Depending on the parameters chosen, different dose dependencies are seen. In some cases, linear dose dependence is reached in a broad range. Sublinear dose dependence, close to a D 1/2 dependence when D is the dose of excitation can be reached when retrapping is stronger than trapping in other traps stabilizing the defects. When strong competition between stabilizing traps takes place, an initial linear range is observed followed by strong superlinearity and an approach to saturation. All these behaviors have been observed experimentally in TL measurements as well as ESR and optical absorption in different materials. Similarities and dissimilarities to linear and non-linear dose dependencies obtained experimentally and by simulations when ionizing irradiation is used for excitation are discussed.

  5. Stability Analysis and Stabilization of T-S Fuzzy Delta Operator Systems with Time-Varying Delay via an Input-Output Approach

    Directory of Open Access Journals (Sweden)

    Zhixiong Zhong

    2013-01-01

    Full Text Available The stability analysis and stabilization of Takagi-Sugeno (T-S fuzzy delta operator systems with time-varying delay are investigated via an input-output approach. A model transformation method is employed to approximate the time-varying delay. The original system is transformed into a feedback interconnection form which has a forward subsystem with constant delays and a feedback one with uncertainties. By applying the scaled small gain (SSG theorem to deal with this new system, and based on a Lyapunov Krasovskii functional (LKF in delta operator domain, less conservative stability analysis and stabilization conditions are obtained. Numerical examples are provided to illustrate the advantages of the proposed method.

  6. Stability and Hopf bifurcation on a model for HIV infection of CD4{sup +} T cells with delay

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xia [College of Mathematics and Information Science, Xinyang Normal University, Xinyang, Henan 464000 (China)], E-mail: xywangxia@163.com; Tao Youde [College of Mathematics and Information Science, Xinyang Normal University, Xinyang, Henan 464000 (China); Beijing Institute of Information Control, Beijing 100037 (China); Song Xinyu [College of Mathematics and Information Science, Xinyang Normal University, Xinyang, Henan 464000 (China) and Research Institute of Forest Resource Information Techniques, Chinese Academy of Forestry, Beijing 100091 (China)], E-mail: xysong88@163.com

    2009-11-15

    In this paper, a delayed differential equation model that describes HIV infection of CD4{sup +} T cells is considered. The stability of the positive equilibrium and the existence of Hopf bifurcation are investigated. In succession, using the normal form theory and center manifold argument, we derive the explicit formulas which determine the stability, direction and other properties of bifurcating periodic solutions.

  7. A new criterion on the global exponential stability for cellular neural networks with multiple time-varying delays

    International Nuclear Information System (INIS)

    Jiang Haijun; Teng Zhidong

    2005-01-01

    In this Letter, based on the Lyapunov stability theorem as well as some facts about the positive definiteness and inequality of matrices, a new sufficient condition to ensure the global exponential stability of equilibrium point for autonomous delayed CNNs is obtained. This condition is less restrictive than given in the earlier references

  8. Permanence for a Delayed Nonautonomous SIR Epidemic Model with Density-Dependent Birth Rate

    Directory of Open Access Journals (Sweden)

    Li Yingke

    2011-01-01

    Full Text Available Based on some well-known SIR models, a revised nonautonomous SIR epidemic model with distributed delay and density-dependent birth rate was considered. Applying some classical analysis techniques for ordinary differential equations and the method proposed by Wang (2002, the threshold value for the permanence and extinction of the model was obtained.

  9. Hopf bifurcation in a partial dependent predator-prey system with delay

    International Nuclear Information System (INIS)

    Zhao Huitao; Lin Yiping

    2009-01-01

    In this paper, a partial dependent predator-prey model with time delay is studied by using the theory of functional differential equation and Hassard's method, the condition on which positive equilibrium exists and Hopf bifurcation occurs are given. Finally, numerical simulations are performed to support the analytical results, and the chaotic behaviors are observed.

  10. Existence of periodic solutions for Rayleigh equations with state-dependent delay

    Directory of Open Access Journals (Sweden)

    Jehad O. Alzabut

    2012-05-01

    Full Text Available We establish sufficient conditions for the existence of periodic solutions for a Rayleigh-type equation with state-dependent delay. Our approach is based on the continuation theorem in degree theory, and some analysis techniques. An example illustrates that our approach to this problem is new.

  11. Existence of Mild Solutions for Impulsive Fractional Integro-Differential Inclusions with State-Dependent Delay

    Directory of Open Access Journals (Sweden)

    Selvaraj Suganya

    2017-01-01

    Full Text Available In this manuscript, we implement Bohnenblust–Karlin’s fixed point theorem to demonstrate the existence of mild solutions for a class of impulsive fractional integro-differential inclusions (IFIDI with state-dependent delay (SDD in Banach spaces. An example is provided to illustrate the obtained abstract results.

  12. Controllability Results For First Order Impulsive Stochastic Functional Differential Systems with State-Dependent Delay

    Directory of Open Access Journals (Sweden)

    C. Parthasarathy

    2013-03-01

    Full Text Available In this paper, we study the controllability results of first order impulsive stochastic differential and neutral differential systems with state-dependent delay by using semigroup theory. The controllability results are derived by the means of Leray-SchauderAlternative fixed point theorem. An example is provided to illustrate the theory.

  13. Existence results for impulsive neutral functional differential equations with state-dependent delay

    Directory of Open Access Journals (Sweden)

    Mani Mallika Arjunan

    2009-04-01

    Full Text Available In this article, we study the existence of mild solutions for a class of impulsive abstract partial neutral functional differential equations with state-dependent delay. The results are obtained by using Leray-Schauder Alternative fixed point theorem. Example is provided to illustrate the main result.

  14. Development of a new esomeprazole delayed release gastro-resistant pellet formulation with improved storage stability.

    Science.gov (United States)

    Barmpalexis, Panagiotis; Grypioti, Agni

    2018-06-01

    This study describes the development of a new esomeprazole (ESO) delayed release gastro-resistant formulation with improved storage stability. A three-step (drug-, sub(seal)- and enteric-) coating process was employed with the aid of a fluid bed coater. Several formulation factors (namely, size and quantity of starting non-pareil sugar spheres, binder quantity during drug-layering, sub(seal)-coating polymer type, and quantity and enteric coating quantity) were evaluated and the whole process was modeled with the aid of feed-forward back-propagation artificial neural networks (ANNs). Results showed that the selection of small-sized starting spheres (45/60 mesh size) leads to pellet agglomeration, while as sub(seal)-coating weight gain increases a reduction in ESO dissolution rate is observed. The enteric-coating applied (Eudragit L30D-55) showed good gastro-resistant performance in both 0.1 N HCl and pH 4.5 media, while immediate release profiles with more than 85% of ESO being released in less than 30 min were obtained. The effect of cellulose-based sub(seal)-coating polymers, (namely, hydroxypropyl cellulose and hydroxypropylmethyl cellulose) on formulation's storage stability at 40 ± 2 °C/75 ± 5%RH indicated that only hydroxypropylmethyl cellulose was able to stabilize ESO delayed-release formulations in terms of assay, dissolution, impurities, and gastro-resistance performance. Finally, scanning electron microscopy (SEM) analysis revealed smooth and homogeneous external surface/coating layers in all three levels (drug-, sub(seal)-, and enteric- coating), while x-ray diffraction showed no polymorphic transformations.

  15. The Application of Time-Delay Dependent H∞ Control Model in Manufacturing Decision Optimization

    Directory of Open Access Journals (Sweden)

    Haifeng Guo

    2015-01-01

    Full Text Available This paper uses a time-delay dependent H∞ control model to analyze the effect of manufacturing decisions on the process of transmission from resources to capability. We establish a theoretical framework of manufacturing management process based on three terms: resource, manufacturing decision, and capability. Then we build a time-delay H∞ robust control model to analyze the robustness of manufacturing management. With the state feedback controller between manufacturing resources and decision, we find that there is an optimal decision to adjust the process of transmission from resources to capability under uncertain environment. Finally, we provide an example to prove the robustness of this model.

  16. Boundary layer phenomena for differential-delay equations with state-dependent time lags: III

    Science.gov (United States)

    Mallet-Paret, John; Nussbaum, Roger D.

    We consider a class of singularly perturbed delay-differential equations of the form ɛ ẋ(t)=f(x(t),x(t-r)), where r= r( x( t)) is a state-dependent delay. We study the asymptotic shape, as ɛ→0, of slowly oscillating periodic solutions. In particular, we show that the limiting shape of such solutions can be explicitly described by the solution of a pair of so-called max-plus equations. We are able thereby to characterize both the regular parts of the solution graph and the internal transition layers arising from the singular perturbation structure.

  17. Perceived object stability depends on multisensory estimates of gravity.

    Science.gov (United States)

    Barnett-Cowan, Michael; Fleming, Roland W; Singh, Manish; Bülthoff, Heinrich H

    2011-04-27

    How does the brain estimate object stability? Objects fall over when the gravity-projected centre-of-mass lies outside the point or area of support. To estimate an object's stability visually, the brain must integrate information across the shape and compare its orientation to gravity. When observers lie on their sides, gravity is perceived as tilted toward body orientation, consistent with a representation of gravity derived from multisensory information. We exploited this to test whether vestibular and kinesthetic information affect this visual task or whether the brain estimates object stability solely from visual information. In three body orientations, participants viewed images of objects close to a table edge. We measured the critical angle at which each object appeared equally likely to fall over or right itself. Perceived gravity was measured using the subjective visual vertical. The results show that the perceived critical angle was significantly biased in the same direction as the subjective visual vertical (i.e., towards the multisensory estimate of gravity). Our results rule out a general explanation that the brain depends solely on visual heuristics and assumptions about object stability. Instead, they suggest that multisensory estimates of gravity govern the perceived stability of objects, resulting in objects appearing more stable than they are when the head is tilted in the same direction in which they fall.

  18. Perceived object stability depends on multisensory estimates of gravity.

    Directory of Open Access Journals (Sweden)

    Michael Barnett-Cowan

    Full Text Available BACKGROUND: How does the brain estimate object stability? Objects fall over when the gravity-projected centre-of-mass lies outside the point or area of support. To estimate an object's stability visually, the brain must integrate information across the shape and compare its orientation to gravity. When observers lie on their sides, gravity is perceived as tilted toward body orientation, consistent with a representation of gravity derived from multisensory information. We exploited this to test whether vestibular and kinesthetic information affect this visual task or whether the brain estimates object stability solely from visual information. METHODOLOGY/PRINCIPAL FINDINGS: In three body orientations, participants viewed images of objects close to a table edge. We measured the critical angle at which each object appeared equally likely to fall over or right itself. Perceived gravity was measured using the subjective visual vertical. The results show that the perceived critical angle was significantly biased in the same direction as the subjective visual vertical (i.e., towards the multisensory estimate of gravity. CONCLUSIONS/SIGNIFICANCE: Our results rule out a general explanation that the brain depends solely on visual heuristics and assumptions about object stability. Instead, they suggest that multisensory estimates of gravity govern the perceived stability of objects, resulting in objects appearing more stable than they are when the head is tilted in the same direction in which they fall.

  19. Global asymptotic stability of density dependent integral population projection models.

    Science.gov (United States)

    Rebarber, Richard; Tenhumberg, Brigitte; Townley, Stuart

    2012-02-01

    Many stage-structured density dependent populations with a continuum of stages can be naturally modeled using nonlinear integral projection models. In this paper, we study a trichotomy of global stability result for a class of density dependent systems which include a Platte thistle model. Specifically, we identify those systems parameters for which zero is globally asymptotically stable, parameters for which there is a positive asymptotically stable equilibrium, and parameters for which there is no asymptotically stable equilibrium. Copyright © 2011 Elsevier Inc. All rights reserved.

  20. Noise enhanced stability effect in a metastable system with two different kinds of time delays and cross-correlated noises

    International Nuclear Information System (INIS)

    Jia Zhenglin; Mei Dongcheng

    2011-01-01

    We numerically investigate the influences of the time delay τ simultaneously existing in both the deterministic and fluctuating forces, the time delay τ r existing only in the fluctuating force and the cross-correlation strength λ on the enhancement of the mean first-passage time (MFPT) as a function of the additive D and the multiplicative α noise intensities in a metastable system. The results indicate that both the multiplicative and additive noises can induce the noise-enhanced stability (NES) effect. An increase of λ can enhance or weaken the NES effect induced by the additive noise, depending on the value of τ. However, it weakens the NES effect induced by the multiplicative noise with a suppression of the effect of λ caused by increasing τ. The τ-induced critical behavior on both NES effects can be observed, i.e. an increase of τ can enhance or restrain the NES effects induced by the two kinds of noises. With an increase of λ and τ, MFPT versus D shows a transition from one peak to two peaks and finally one peak, implying the multiple NES effect caused by λ and τ. An increase of τ r can enhance the NES effect induced by the additive noise and weaken the NES effect induced by the multiplicative noise.

  1. Stability Switches, Hopf Bifurcations, and Spatio-temporal Patterns in a Delayed Neural Model with Bidirectional Coupling

    Science.gov (United States)

    Song, Yongli; Zhang, Tonghua; Tadé, Moses O.

    2009-12-01

    The dynamical behavior of a delayed neural network with bi-directional coupling is investigated by taking the delay as the bifurcating parameter. Some parameter regions are given for conditional/absolute stability and Hopf bifurcations by using the theory of functional differential equations. As the propagation time delay in the coupling varies, stability switches for the trivial solution are found. Conditions ensuring the stability and direction of the Hopf bifurcation are determined by applying the normal form theory and the center manifold theorem. We also discuss the spatio-temporal patterns of bifurcating periodic oscillations by using the symmetric bifurcation theory of delay differential equations combined with representation theory of Lie groups. In particular, we obtain that the spatio-temporal patterns of bifurcating periodic oscillations will alternate according to the change of the propagation time delay in the coupling, i.e., different ranges of delays correspond to different patterns of neural activities. Numerical simulations are given to illustrate the obtained results and show the existence of bursts in some interval of the time for large enough delay.

  2. Micromachined silicon acoustic delay line with improved structural stability and acoustic directivity for real-time photoacoustic tomography

    Science.gov (United States)

    Cho, Young; Kumar, Akhil; Xu, Song; Zou, Jun

    2017-03-01

    Recent studies have shown that micromachined silicon acoustic delay lines can provide a promising solution to achieve real-time photoacoustic tomography without the need for complex transducer arrays and data acquisition electronics. However, as its length increases to provide longer delay time, the delay line becomes more vulnerable to structural instability due to reduced mechanical stiffness. In addition, the small cross-section area of the delay line results in a large acoustic acceptance angle and therefore poor directivity. To address these two issues, this paper reports the design, fabrication, and testing of a new silicon acoustic delay line enhanced with 3D printed polymer micro linker structures. First, mechanical deformation of the silicon acoustic delay line (with and without linker structures) under gravity was simulated by using finite element method. Second, the acoustic crosstalk and acoustic attenuation caused by the polymer micro linker structures were evaluated with both numerical simulation and ultrasound transmission testing. The result shows that the use of the polymer micro linker structures significantly improves the structural stability of the silicon acoustic delay lines without creating additional acoustic attenuation and crosstalk. In addition, a new tapered design for the input terminal of the delay line was also investigate to improve its acoustic directivity by reducing the acoustic acceptance angle. These two improvements are expected to provide an effective solution to eliminate current limitations on the achievable acoustic delay time and out-of-plane imaging resolution of micromachined silicon acoustic delay line arrays.

  3. Distributed Containment Control of Networked Fractional-Order Systems with Delay-Dependent Communications

    Directory of Open Access Journals (Sweden)

    Xueliang Liu

    2012-01-01

    Full Text Available This paper is concerned with a containment problem of networked fractional-order system with multiple leaders under a fixed directed interaction graph. Based on the neighbor rule, a distributed protocol is proposed in delayed communication channels. By employing the algebraic graph theory, matrix theory, Nyquist stability theorem, and frequency domain method, it is analytically proved that the whole follower agents will flock to the convex hull which is formed by the leaders. Furthermore, a tight upper bound on the communication time-delay that can be tolerated in the dynamic network is obtained. As a special case, the interconnection topology under the undirected case is also discussed. Finally, some numerical examples with simulations are presented to demonstrate the effectiveness and correctness of the theoretical results.

  4. Existence and Globally Asymptotic Stability of Equilibrium Solution for Fractional-Order Hybrid BAM Neural Networks with Distributed Delays and Impulses

    Directory of Open Access Journals (Sweden)

    Hai Zhang

    2017-01-01

    Full Text Available This paper investigates the existence and globally asymptotic stability of equilibrium solution for Riemann-Liouville fractional-order hybrid BAM neural networks with distributed delays and impulses. The factors of such network systems including the distributed delays, impulsive effects, and two different fractional-order derivatives between the U-layer and V-layer are taken into account synchronously. Based on the contraction mapping principle, the sufficient conditions are derived to ensure the existence and uniqueness of the equilibrium solution for such network systems. By constructing a novel Lyapunov functional composed of fractional integral and definite integral terms, the globally asymptotic stability criteria of the equilibrium solution are obtained, which are dependent on the order of fractional derivative and network parameters. The advantage of our constructed method is that one may directly calculate integer-order derivative of the Lyapunov functional. A numerical example is also presented to show the validity and feasibility of the theoretical results.

  5. Delayed Ego Strength Development in Opioid Dependent Adolescents and Young Adults

    Science.gov (United States)

    Abramoff, Benjamin A.; Lange, Hannah L. H.; Matson, Steven C.; Cottrill, Casey B.; Bridge, Jeffrey A.; Abdel-Rasoul, Mahmoud; Bonny, Andrea E.

    2015-01-01

    Objective. To evaluate ego strengths, in the context of Erikson's framework, among adolescents and young adults diagnosed with opioid dependence as compared to non-drug using youth. Methods. Opioid dependent (n = 51) and non-drug using control (n = 31) youth completed the self-administered Psychosocial Inventory of Ego Strengths (PIES). The PIES assesses development in the framework of Erikson's ego strength stages. Multivariate linear regression modeling assessed the independent association of the primary covariate (opioid dependent versus control) as well as potential confounding variables (e.g., psychiatric comorbidities, intelligence) with total PIES score. Results. Mean total PIES score was significantly lower in opioid dependent youth (231.65 ± 30.39 opioid dependent versus 270.67 ± 30.06 control; p development. A treatment approach acknowledging this delay may be needed in the counseling and treatment of adolescents with opioid dependence. PMID:26664819

  6. Robust stability analysis of switched Hopfield neural networks with time-varying delay under uncertainty

    International Nuclear Information System (INIS)

    Huang He; Qu Yuzhong; Li Hanxiong

    2005-01-01

    With the development of intelligent control, switched systems have been widely studied. Here we try to introduce some ideas of the switched systems into the field of neural networks. In this Letter, a class of switched Hopfield neural networks with time-varying delay is investigated. The parametric uncertainty is considered and assumed to be norm bounded. Firstly, the mathematical model of the switched Hopfield neural networks is established in which a set of Hopfield neural networks are used as the individual subsystems and an arbitrary switching rule is assumed; Secondly, robust stability analysis for such switched Hopfield neural networks is addressed based on the Lyapunov-Krasovskii approach. Some criteria are given to guarantee the switched Hopfield neural networks to be globally exponentially stable for all admissible parametric uncertainties. These conditions are expressed in terms of some strict linear matrix inequalities (LMIs). Finally, a numerical example is provided to illustrate our results

  7. Optimal robust stabilizer design based on UPFC for interconnected power systems considering time delay

    Directory of Open Access Journals (Sweden)

    Koofigar Hamid Reza

    2017-09-01

    Full Text Available A robust auxiliary wide area damping controller is proposed for a unified power flow controller (UPFC. The mixed H2 / H∞ problem with regional pole placement, resolved by linear matrix inequality (LMI, is applied for controller design. Based on modal analysis, the optimal wide area input signals for the controller are selected. The time delay of input signals, due to electrical distance from the UPFC location is taken into account in the design procedure. The proposed controller is applied to a multi-machine interconnected power system from the IRAN power grid. It is shown that the both transient and dynamic stability are significantly improved despite different disturbances and loading conditions.

  8. Global exponential stability of periodic solution for shunting inhibitory CNNs with delays

    Energy Technology Data Exchange (ETDEWEB)

    Li Yongkun [Department of Mathematics, Yunnan University, Kunming, Yunnan 650091 (China)]. E-mail: yklie@ynu.edu.cn; Liu Chunchao [Department of Mathematics, Yunnan University, Kunming, Yunnan 650091 (China); Zhu Lifei [Department of Mathematics, Yunnan University, Kunming, Yunnan 650091 (China)

    2005-03-28

    By using the continuation theorem of coincidence degree theory and constructing suitable Lyapunov functions, we study the existence and stability of periodic solution for shunting inhibitory cellular neural networks (SICNNs) with delays x-bar {sub ij}(t)=-a{sub ij}(t)x{sub ij}(t)--bar B{sup kl}-bar Nr(i,j)B{sub ij}{sup kl}(t)f{sub ij}(x{sub kl}(t))x{sub ij}(t)--bar C{sup kl}-bar Nr(i,j)C{sub ij}{sup kl}(t)g{sub ij}(x{sub kl}(t-{tau}{sub kl}))x{sub ij}(t)+L{sub ij}(t)

  9. NON NEUROLOGICAL OUTCOME COMPARISON OF EARLY AND DELAYED SURGICAL STABILIZATION IN C-SPINE FRACTURES

    Directory of Open Access Journals (Sweden)

    T. G. B. Mahadewa

    2014-01-01

    Full Text Available Background: Non neurological outcome postsurgical stabilization in C-spine injury has not been reported. Non neurological outcome i.e. the risk of lung infection (pneumonia, systemic inflammation response syndrome (SIRS, length of postoperative care (LOPOC which can compromise the recovery process and treatment period. This study aims to investigate non neurological outcome comparison after early surgical stabilization (ESS and delayed surgical stabilization (DSS in patients with C-spine fractures. Methods: The author retrospectively reviews 59 of 108 consecutive patients who met the inclusion criteria with C-spine fractures who underwent surgical stabilization at the Sanglah General Hospital, between 2007 and 2010. Consisting of 25 patients underwent ESS and 34 patients were treated by DSS. The last follow up period range was 3-36 months. Non neurological outcome were evaluated and compared; the risk of pneumonia, SIRS and LOPOC. Results: Significant statistically between ESS and DSS in; the risk of pneumonia (ESS: DSS= 1:9 by Chi-square-test (p=0.023; the risk of SIRS (ESS: DSS= 1:11 by Chi-square-test (p=0.008; and the LOPOC (ESS: DSS= 6.84:9.97 by independent t-test (p=0.000. Application of ESS for C-spine fractures could provide early mobilization, prompt treatment and facilitate early rehabilitation thus significantly reduces complications due to prolong immobilization and reduces LOPOC. Conclussion: It can be concluded that the ESS strategy is effective and efficient thus may propose an option of surgical timing in C-spine fractures.

  10. Continuous solutions to a viral infection model with general incidence rate, discrete state-dependent delay, CTL and antibody immune responses

    Czech Academy of Sciences Publication Activity Database

    Rezunenko, Oleksandr

    2016-01-01

    Roč. 2016, č. 79 (2016), s. 1-15 ISSN 1417-3875 R&D Projects: GA ČR(CZ) GA16-06678S Institutional support: RVO:67985556 Keywords : evolution equations * Lyapunov stability * state-dependent delay * virus infection model Subject RIV: BC - Control Systems Theory Impact factor: 0.926, year: 2016 http://library.utia.cas.cz/separaty/2016/AS/rezunenko-0464066.pdf

  11. Improved Stabilization Conditions for Nonlinear Systems with Input and State Delays via T-S Fuzzy Model

    Directory of Open Access Journals (Sweden)

    Chang Che

    2018-01-01

    Full Text Available This paper focuses on the problem of nonlinear systems with input and state delays. The considered nonlinear systems are represented by Takagi-Sugeno (T-S fuzzy model. A new state feedback control approach is introduced for T-S fuzzy systems with input delay and state delays. A new Lyapunov-Krasovskii functional is employed to derive less conservative stability conditions by incorporating a recently developed Wirtinger-based integral inequality. Based on the Lyapunov stability criterion, a series of linear matrix inequalities (LMIs are obtained by using the slack variables and integral inequality, which guarantees the asymptotic stability of the closed-loop system. Several numerical examples are given to show the advantages of the proposed results.

  12. Stability and Complexity Analysis of a Dual-Channel Closed-Loop Supply Chain with Delayed Decision under Government Intervention

    Directory of Open Access Journals (Sweden)

    Daoming Dai

    2017-10-01

    Full Text Available This paper constructs a continuous dual-channel closed-loop supply chain (DCLSC model with delayed decision under government intervention. The existence conditions of the local stability of the equilibrium point are discussed. We analyze the influence of delay parameters, the adjustment speed of wholesale price, recovery rate of waste products, direct price, carbon quota subsidy, and carbon tax on the stability and complexity of model by using bifurcation diagram, entropy diagram, attractor, and time series diagram and so on. Besides, the delay feedback control method is adopted to control the unstable or chaotic system effectively. The main conclusions of this paper show that the variables mentioned above must be within a reasonable range. Otherwise, the model will lose stability or enter chaos. The government can effectively adjust manufacturers' profit through carbon tax and carbon quota subsidy, and encourage manufacturers to reduce carbon emissions and increase the remanufacturing of waste products.

  13. Parabolic partial differential equations with discrete state-dependent delay: Classical solutions and solution manifold

    Czech Academy of Sciences Publication Activity Database

    Krisztin, T.; Rezunenko, Oleksandr

    2016-01-01

    Roč. 260, č. 5 (2016), s. 4454-4472 ISSN 0022-0396 R&D Projects: GA ČR GAP103/12/2431 Institutional support: RVO:67985556 Keywords : Parabolic partial differential equations * State dependent delay * Solution manifold Subject RIV: BC - Control Systems Theory Impact factor: 1.988, year: 2016 http://library.utia.cas.cz/separaty/2016/AS/rezunenko-0457879.pdf

  14. On time transformations for differential equations with state-dependent delay

    Czech Academy of Sciences Publication Activity Database

    Rezunenko, Oleksandr

    2014-01-01

    Roč. 12, č. 2 (2014), s. 298-307 ISSN 1895-1074 R&D Projects: GA ČR GAP103/12/2431 Institutional support: RVO:67985556 Keywords : differential equations * state-dependent delay * time transformations Subject RIV: BD - Theory of Information Impact factor: 0.578, year: 2014 http://library.utia.cas.cz/separaty/2014/AS/rezunenko-0429130.pdf

  15. Dynamics of second order in time evolution equations with state-dependent delay

    Czech Academy of Sciences Publication Activity Database

    Chueshov, I.; Rezunenko, Oleksandr

    123-124, č. 1 (2015), s. 126-149 ISSN 0362-546X R&D Projects: GA ČR GAP103/12/2431 Institutional support: RVO:67985556 Keywords : Second order evolution equations * State dependent delay * Nonlinear plate * Finite-dimensional attractor Subject RIV: BD - Theory of Information Impact factor: 1.125, year: 2015 http://library.utia.cas.cz/separaty/2015/AS/rezunenko-0444708.pdf

  16. Finite-dimensional global attractors for parabolic nonlinear equations with state-dependent delay

    Czech Academy of Sciences Publication Activity Database

    Chueshov, I.; Rezunenko, Oleksandr

    2015-01-01

    Roč. 14, č. 5 (2015), s. 1685-1704 ISSN 1534-0392 R&D Projects: GA ČR GAP103/12/2431 Institutional support: RVO:67985556 Keywords : Parabolic evolution equations * state-dependent delay * global attractor * finite-dimension * exponential attractor Subject RIV: BC - Control Systems Theory Impact factor: 0.926, year: 2015 http://library.utia.cas.cz/separaty/2015/AS/rezunenko-0444705.pdf

  17. Existence results for fractional integro-differential inclusions with state-dependent delay

    Directory of Open Access Journals (Sweden)

    Siracusa Giovana

    2017-10-01

    Full Text Available In this paper we are concerned with a class of abstract fractional integro-differential inclusions with infinite state-dependent delay. Our approach is based on the existence of a resolvent operator for the homogeneous equation.We establish the existence of mild solutions using both contractive maps and condensing maps. Finally, an application to the theory of heat conduction in materials with memory is given.

  18. Stability analysis of Markovian jumping stochastic Cohen—Grossberg neural networks with discrete and distributed time varying delays

    International Nuclear Information System (INIS)

    Ali, M. Syed

    2014-01-01

    In this paper, the global asymptotic stability problem of Markovian jumping stochastic Cohen—Grossberg neural networks with discrete and distributed time-varying delays (MJSCGNNs) is considered. A novel LMI-based stability criterion is obtained by constructing a new Lyapunov functional to guarantee the asymptotic stability of MJSCGNNs. Our results can be easily verified and they are also less restrictive than previously known criteria and can be applied to Cohen—Grossberg neural networks, recurrent neural networks, and cellular neural networks. Finally, the proposed stability conditions are demonstrated with numerical examples

  19. Note: Large active area solid state photon counter with 20 ps timing resolution and 60 fs detection delay stability

    Science.gov (United States)

    Prochazka, Ivan; Kodet, Jan; Eckl, Johann; Blazej, Josef

    2017-10-01

    We are reporting on the design, construction, and performance of a photon counting detector system, which is based on single photon avalanche diode detector technology. This photon counting device has been optimized for very high timing resolution and stability of its detection delay. The foreseen application of this detector is laser ranging of space objects, laser time transfer ground to space and fundamental metrology. The single photon avalanche diode structure, manufactured on silicon using K14 technology, is used as a sensor. The active area of the sensor is circular with 200 μm diameter. Its photon detection probability exceeds 40% in the wavelength range spanning from 500 to 800 nm. The sensor is operated in active quenching and gating mode. A new control circuit was optimized to maintain high timing resolution and detection delay stability. In connection to this circuit, timing resolution of the detector is reaching 20 ps FWHM. In addition, the temperature change of the detection delay is as low as 70 fs/K. As a result, the detection delay stability of the device is exceptional: expressed in the form of time deviation, detection delay stability of better than 60 fs has been achieved. Considering the large active area aperture of the detector, this is, to our knowledge, the best timing performance reported for a solid state photon counting detector so far.

  20. Horseshoes chaos and stability of a delayed van der Pol-Duffing oscillator under a bounded double well potential

    International Nuclear Information System (INIS)

    Kwuimy, C.A. Kitio; Woafo, P.

    2009-06-01

    In this paper a van der Pol-Duffing oscillator with a bounded double well potential and a delayed (positive and negative) position and velocity feedback is considered. Attention is focussed on the effects of time delay on stability, escape motion and horseshoes chaos. Using Forde and Nelson's theorem, harmonic balance and Melnikov criterion for chaos, the boundary conditions for such phenomena are derived. It appears that, time delay can be used as simple switch to avoid and/or create complex behavior of the model. (author)

  1. Global exponential stability of impulsive fuzzy cellular neural networks with mixed delays and reaction-diffusion terms

    International Nuclear Information System (INIS)

    Wang Xiaohu; Xu Daoyi

    2009-01-01

    In this paper, the global exponential stability of impulsive fuzzy cellular neural networks with mixed delays and reaction-diffusion terms is considered. By establishing an integro-differential inequality with impulsive initial condition and using the properties of M-cone and eigenspace of the spectral radius of nonnegative matrices, several new sufficient conditions are obtained to ensure the global exponential stability of the equilibrium point for fuzzy cellular neural networks with delays and reaction-diffusion terms. These results extend and improve the earlier publications. Two examples are given to illustrate the efficiency of the obtained results.

  2. Stability Analysis of Positive Polynomial Fuzzy-Model-Based Control Systems with Time Delay under Imperfect Premise Matching

    OpenAIRE

    Li, Xiaomiao; Lam, Hak Keung; Song, Ge; Liu, Fucai

    2017-01-01

    This paper deals with the stability and positivity analysis of polynomial-fuzzy-model-based ({PFMB}) control systems with time delay, which is formed by a polynomial fuzzy model and a polynomial fuzzy controller connected in a closed loop, under imperfect premise matching. To improve the design and realization flexibility, the polynomial fuzzy model and the polynomial fuzzy controller are allowed to have their own set of premise membership functions. A sum-of-squares (SOS)-based stability ana...

  3. Global exponential stability of BAM neural networks with time-varying delays: The discrete-time case

    Science.gov (United States)

    Raja, R.; Marshal Anthoni, S.

    2011-02-01

    This paper deals with the problem of stability analysis for a class of discrete-time bidirectional associative memory (BAM) neural networks with time-varying delays. By employing the Lyapunov functional and linear matrix inequality (LMI) approach, a new sufficient conditions is proposed for the global exponential stability of discrete-time BAM neural networks. The proposed LMI based results can be easily checked by LMI control toolbox. Moreover, an example is also provided to demonstrate the effectiveness of the proposed method.

  4. Global exponential stability and periodicity of reaction-diffusion delayed recurrent neural networks with Dirichlet boundary conditions

    International Nuclear Information System (INIS)

    Lu Junguo

    2008-01-01

    In this paper, the global exponential stability and periodicity for a class of reaction-diffusion delayed recurrent neural networks with Dirichlet boundary conditions are addressed by constructing suitable Lyapunov functionals and utilizing some inequality techniques. We first prove global exponential converge to 0 of the difference between any two solutions of the original reaction-diffusion delayed recurrent neural networks with Dirichlet boundary conditions, the existence and uniqueness of equilibrium is the direct results of this procedure. This approach is different from the usually used one where the existence, uniqueness of equilibrium and stability are proved in two separate steps. Furthermore, we prove periodicity of the reaction-diffusion delayed recurrent neural networks with Dirichlet boundary conditions. Sufficient conditions ensuring the global exponential stability and the existence of periodic oscillatory solutions for the reaction-diffusion delayed recurrent neural networks with Dirichlet boundary conditions are given. These conditions are easy to check and have important leading significance in the design and application of reaction-diffusion recurrent neural networks with delays. Finally, two numerical examples are given to show the effectiveness of the obtained results

  5. Exponential mean-square stability of two classes of theta Milstein methods for stochastic delay differential equations

    Science.gov (United States)

    Rouz, Omid Farkhondeh; Ahmadian, Davood; Milev, Mariyan

    2017-12-01

    This paper establishes exponential mean square stability of two classes of theta Milstein methods, namely split-step theta Milstein (SSTM) method and stochastic theta Milstein (STM) method, for stochastic differential delay equations (SDDEs). We consider the SDDEs problem under a coupled monotone condition on drift and diffusion coefficients, as well as a necessary linear growth condition on the last term of theta Milstein method. It is proved that the SSTM method with θ ∈ [0, ½] can recover the exponential mean square stability of the exact solution with some restrictive conditions on stepsize, but for θ ∈ (½, 1], we proved that the stability results hold for any stepsize. Then, based on the stability results of SSTM method, we examine the exponential mean square stability of the STM method and obtain the similar stability results to that of the SSTM method. In the numerical section the figures show thevalidity of our claims.

  6. Does a deformation of special relativity imply energy dependent photon time delays?

    Science.gov (United States)

    Carmona, J. M.; Cortés, J. L.; Relancio, J. J.

    2018-01-01

    Theoretical arguments in favor of energy dependent photon time delays from a modification of special relativity (SR) have met with recent gamma ray observations that put severe constraints on the scale of such deviations. We review the case of the generality of this theoretical prediction in the case of a deformation of SR and find that, at least in the simple model based on the analysis of photon worldlines which is commonly considered, there are many scenarios compatible with a relativity principle which do not contain a photon time delay. This will be the situation for any modified dispersion relation which reduces to E=\\vert p\\vert for photons, independently of the quantum structure of spacetime. This fact opens up the possibility of a phenomenologically consistent relativistic generalization of SR with a new mass scale many orders of magnitude below the Planck mass.

  7. MODICO, 1-D Time-Dependent 1 Group, 2 Group Neutron Diffusion with Delayed Neutron Precursors

    International Nuclear Information System (INIS)

    Camiciola, P.; Cundari, D.; Montagnini, B.

    1992-01-01

    1 - Description of program or function: The program solves the 1-D time-dependent one and two group coarse-mesh neutron diffusion equations, coupled with the equations for the delayed-neutron precursor, in plane geometry. 2 - Method of solution: The program is based on a simple coarse-mesh cubic approximation formula for the spatial behaviour of the flux inside each interval. An implicit scheme (the time-integrated method) is used for the advancement of the solution. The resulting (block three-diagonal) matrix is inverted at each time step by Thomas' method. 3 - Restrictions on the complexity of the problem: Number of coarse- mesh intervals LE 80; number of material regions LE 10; number of delayed-neutron precursor groups LE 10. Typical mesh sizes range from 5 cm to 20 cm; typical step length (non-prompt critical transients) ranges from 0.005 to 0.1 seconds

  8. Stability switches, oscillatory multistability, and spatio-temporal patterns of nonlinear oscillations in recurrently delay coupled neural networks.

    Science.gov (United States)

    Song, Yongli; Makarov, Valeri A; Velarde, Manuel G

    2009-08-01

    A model of time-delay recurrently coupled spatially segregated neural assemblies is here proposed. We show that it operates like some of the hierarchical architectures of the brain. Each assembly is a neural network with no delay in the local couplings between the units. The delay appears in the long range feedforward and feedback inter-assemblies communications. Bifurcation analysis of a simple four-units system in the autonomous case shows the richness of the dynamical behaviors in a biophysically plausible parameter region. We find oscillatory multistability, hysteresis, and stability switches of the rest state provoked by the time delay. Then we investigate the spatio-temporal patterns of bifurcating periodic solutions by using the symmetric local Hopf bifurcation theory of delay differential equations and derive the equation describing the flow on the center manifold that enables us determining the direction of Hopf bifurcations and stability of the bifurcating periodic orbits. We also discuss computational properties of the system due to the delay when an external drive of the network mimicks external sensory input.

  9. Why trace and delay conditioning are sometimes (but not always) hippocampal dependent: A computational model

    Science.gov (United States)

    Moustafa, Ahmed A.; Wufong, Ella; Servatius, Richard J.; Pang, Kevin C. H.; Gluck, Mark A.; Myers, Catherine E.

    2013-01-01

    A recurrent-network model provides a unified account of the hippocampal region in mediating the representation of temporal information in classical eyeblink conditioning. Much empirical research is consistent with a general conclusion that delay conditioning (in which the conditioned stimulus CS and unconditioned stimulus US overlap and co-terminate) is independent of the hippocampal system, while trace conditioning (in which the CS terminates before US onset) depends on the hippocampus. However, recent studies show that, under some circumstances, delay conditioning can be hippocampal-dependent and trace conditioning can be spared following hippocampal lesion. Here, we present an extension of our prior trial-level models of hippocampal function and stimulus representation that can explain these findings within a unified framework. Specifically, the current model includes adaptive recurrent collateral connections that aid in the representation of intra-trial temporal information. With this model, as in our prior models, we argue that the hippocampus is not specialized for conditioned response timing, but rather is a general-purpose system that learns to predict the next state of all stimuli given the current state of variables encoded by activity in recurrent collaterals. As such, the model correctly predicts that hippocampal involvement in classical conditioning should be critical not only when there is an intervening trace interval, but also when there is a long delay between CS onset and US onset. Our model simulates empirical data from many variants of classical conditioning, including delay and trace paradigms in which the length of the CS, the inter-stimulus interval, or the trace interval is varied. Finally, we discuss model limitations, future directions, and several novel empirical predictions of this temporal processing model of hippocampal function and learning. PMID:23178699

  10. Polynomial two-parameter eigenvalue problems and matrix pencil methods for stability of delay-differential equations

    NARCIS (Netherlands)

    Jarlebring, E.; Hochstenbach, M.E.

    2009-01-01

    Several recent methods used to analyze asymptotic stability of delay-differential equations (DDEs) involve determining the eigenvalues of a matrix, a matrix pencil or a matrix polynomial constructed by Kronecker products. Despite some similarities between the different types of these so-called

  11. Analysis of stability and bifurcations of fixed points and periodic solutions of a lumped model of neocortex with two delays

    NARCIS (Netherlands)

    Visser, Sid; Meijer, Hil G.E.; van Putten, Michel J.A.M.; van Gils, Stephan A.

    2012-01-01

    A lumped model of neural activity in neocortex is studied to identify regions of multi-stability of both steady states and periodic solutions. Presence of both steady states and periodic solutions is considered to correspond with epileptogenesis. The model, which consists of two delay differential

  12. Global exponential stability and lag synchronization for delayed memristive fuzzy Cohen-Grossberg BAM neural networks with impulses.

    Science.gov (United States)

    Yang, Wengui; Yu, Wenwu; Cao, Jinde; Alsaadi, Fuad E; Hayat, Tasawar

    2018-02-01

    This paper investigates the stability and lag synchronization for memristor-based fuzzy Cohen-Grossberg bidirectional associative memory (BAM) neural networks with mixed delays (asynchronous time delays and continuously distributed delays) and impulses. By applying the inequality analysis technique, homeomorphism theory and some suitable Lyapunov-Krasovskii functionals, some new sufficient conditions for the uniqueness and global exponential stability of equilibrium point are established. Furthermore, we obtain several sufficient criteria concerning globally exponential lag synchronization for the proposed system based on the framework of Filippov solution, differential inclusion theory and control theory. In addition, some examples with numerical simulations are given to illustrate the feasibility and validity of obtained results. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Stability of small-amplitude periodic solutions near Hopf bifurcations in time-delayed fully-connected PLL networks

    Science.gov (United States)

    Ferruzzo Correa, Diego P.; Bueno, Átila M.; Castilho Piqueira, José R.

    2017-04-01

    In this paper we investigate stability conditions for small-amplitude periodic solutions emerging near symmetry-preserving Hopf bifurcations in a time-delayed fully-connected N-node PLL network. The study of this type of systems which includes the time delay between connections has attracted much attention among researchers mainly because the delayed coupling between nodes emerges almost naturally in mathematical modeling in many areas of science such as neurobiology, population dynamics, physiology and engineering. In a previous work it has been shown that symmetry breaking and symmetry preserving Hopf bifurcations can emerge in the parameter space. We analyze the stability along branches of periodic solutions near fully-synchronized Hopf bifurcations in the fixed-point space, based on the reduction of the infinite-dimensional space onto a two-dimensional center manifold in normal form. Numerical results are also presented in order to confirm our analytical results.

  14. An Exponential Stability Result of a Timoshenko System with Thermoelasticity with Second Sound and in the Presence of Delay

    Energy Technology Data Exchange (ETDEWEB)

    Apalara, Tijani A., E-mail: tijani@kfupm.edu.sa [King Fahd University of Petroleum and Minerals, Affiliated Colleges at Hafr Al-Batin, General Science and Studies Unit-Mathematics (Saudi Arabia); Messaoudi, Salim A., E-mail: messaoud@kfupm.edu.sa [King Fahd University of Petroleum and Minerals, Department of Mathematics and Statistics (Saudi Arabia)

    2015-06-15

    In this paper, we consider a one-dimensional linear thermoelastic system of Timoshenko type with a delay, where the heat flux is given by Cattaneo’s law. We prove an exponential decay result under a smallness condition on the delay and a stability number introduced first in Santos et al. (J Diff Eqs 253:2715–2733, 2012), using a method different from that of Santos et al. (J Diff Eqs 253:2715–2733, 2012). We also reproduce the polynomial decay of Santos et al. (J Diff Eqs 253:2715–2733, 2012) using the multiplier method in the case of absence of delay. The polynomial decay issue in the presence of a small delay is an open question.

  15. Boundedness and global robust stability analysis of delayed complex-valued neural networks with interval parameter uncertainties.

    Science.gov (United States)

    Song, Qiankun; Yu, Qinqin; Zhao, Zhenjiang; Liu, Yurong; Alsaadi, Fuad E

    2018-07-01

    In this paper, the boundedness and robust stability for a class of delayed complex-valued neural networks with interval parameter uncertainties are investigated. By using Homomorphic mapping theorem, Lyapunov method and inequality techniques, sufficient condition to guarantee the boundedness of networks and the existence, uniqueness and global robust stability of equilibrium point is derived for the considered uncertain neural networks. The obtained robust stability criterion is expressed in complex-valued LMI, which can be calculated numerically using YALMIP with solver of SDPT3 in MATLAB. An example with simulations is supplied to show the applicability and advantages of the acquired result. Copyright © 2018 Elsevier Ltd. All rights reserved.

  16. Role of Ku80-dependent end-joining in delayed genomic instability in mammalian cells surviving ionizing radiation

    International Nuclear Information System (INIS)

    Suzuki, Keiji; Kodama, Seiji; Watanabe, Masami

    2010-01-01

    Ionizing radiation induces delayed destabilization of the genome in the progenies of surviving cells. This phenomenon, which is called radiation-induced genomic instability, is manifested by delayed induction of radiation effects, such as cell death, chromosome aberration, and mutation in the progeny of cells surviving radiation exposure. Previously, there was a report showing that delayed cell death was absent in Ku80-deficient Chinese hamster ovary (CHO) cells, however, the mechanism of their defect has not been determined. We found that delayed induction of DNA double strand breaks and chromosomal breaks were intact in Ku80-deficient cells surviving X-irradiation, whereas there was no sign for the production of chromosome bridges between divided daughter cells. Moreover, delayed induction of dicentric chromosomes was significantly compromised in those cells compared to the wild-type CHO cells. Reintroduction of the human Ku86 gene complimented the defective DNA repair and recovered delayed induction of dicentric chromosomes and delayed cell death, indicating that defective Ku80-dependent dicentric induction was the cause of the absence of delayed cell death. Since DNA-PKcs-defective cells showed delayed phenotypes, Ku80-dependent illegitimate rejoining is involved in delayed impairment of the integrity of the genome in radiation-survived cells.

  17. Role of Ku80-dependent end-joining in delayed genomic instability in mammalian cells surviving ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Keiji, E-mail: kzsuzuki@nagasaki-u.ac.jp [Course of Life Sciences and Radiation Research, Graduate School of Biomedical Sciences, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523 (Japan); Kodama, Seiji [Research Institute for Advanced Science and Technology, Osaka Prefecture University, 1-2 Gakuen-machi, Sakai 599-8570 (Japan); Watanabe, Masami [Kyoto University Research Reactor Institute, Kumatori-cho Sennan-gun, Osaka 590-0494 (Japan)

    2010-01-05

    Ionizing radiation induces delayed destabilization of the genome in the progenies of surviving cells. This phenomenon, which is called radiation-induced genomic instability, is manifested by delayed induction of radiation effects, such as cell death, chromosome aberration, and mutation in the progeny of cells surviving radiation exposure. Previously, there was a report showing that delayed cell death was absent in Ku80-deficient Chinese hamster ovary (CHO) cells, however, the mechanism of their defect has not been determined. We found that delayed induction of DNA double strand breaks and chromosomal breaks were intact in Ku80-deficient cells surviving X-irradiation, whereas there was no sign for the production of chromosome bridges between divided daughter cells. Moreover, delayed induction of dicentric chromosomes was significantly compromised in those cells compared to the wild-type CHO cells. Reintroduction of the human Ku86 gene complimented the defective DNA repair and recovered delayed induction of dicentric chromosomes and delayed cell death, indicating that defective Ku80-dependent dicentric induction was the cause of the absence of delayed cell death. Since DNA-PKcs-defective cells showed delayed phenotypes, Ku80-dependent illegitimate rejoining is involved in delayed impairment of the integrity of the genome in radiation-survived cells.

  18. Angular dependence of the attosecond time delay in the H 2 + ion

    Science.gov (United States)

    Kheifets, Anatoli; Serov, Vladislav

    2016-05-01

    Angular dependence of attosecond time delay relative to polarization of light can now be measured using combination of RABBITT and COLTRIMS techniques. This dependence brings particularly useful information in molecules where it is sensitive to the orientation of the molecular axis. Here we extend the theoretical studies of and consider a molecular ion H2+in combination of an attosecond pulse train and a dressing IR field which is a characteristic set up of a RABBIT measurement. We solve the time-dependent Schrödinger equation using a fast spherical Bessel transformation (SBT) for the radial variable, a discrete variable representation for the angular variables and a split-step technique for the time evolution. The use of SBT ensures correct phase of the wave function for a long time evolution which is especially important in time delay calculations. To speed up computations, we implement an expanding coordinate (EC) system which allows us to reach space sizes and time periods unavailable by other techniques. Australian Research Council DP120101805.

  19. Spin-dependent delay time and Hartman effect in asymmetrical graphene barrier under strain

    Science.gov (United States)

    Sattari, Farhad; Mirershadi, Soghra

    2018-01-01

    We study the spin-dependent tunneling time, including group delay and dwell time, in a graphene based asymmetrical barrier with Rashba spin-orbit interaction in the presence of strain, sandwiched between two normal leads. We find that the spin-dependent tunneling time can be efficiently tuned by the barrier width, and the bias voltage. Moreover, for the zigzag direction strain although the oscillation period of the dwell time does not change, the oscillation amplitude increases by increasing the incident electron angle. It is found that for the armchair direction strain unlike the zigzag direction the group delay time at the normal incidence depends on the spin state of electrons and Hartman effect can be observed. In addition, for the armchair direction strain the spin polarization increases with increasing the RSOI strength and the bias voltage. The magnitude and sign of spin polarization can be manipulated by strain. In particular, by applying an external electric field the efficiency of the spin polarization is improved significantly in strained graphene, and a fully spin-polarized current is generated.

  20. Output regulation control for switched stochastic delay systems with dissipative property under error-dependent switching

    Science.gov (United States)

    Li, L. L.; Jin, C. L.; Ge, X.

    2018-01-01

    In this paper, the output regulation problem with dissipative property for a class of switched stochastic delay systems is investigated, based on an error-dependent switching law. Under the assumption that none subsystem is solvable for the problem, a sufficient condition is derived by structuring multiple Lyapunov-Krasovskii functionals with respect to multiple supply rates, via designing error feedback regulators. The condition is also established when dissipative property reduces to passive property. Finally, two numerical examples are given to demonstrate the feasibility and efficiency of the present method.

  1. Temporal framing and the hidden-zero effect: rate-dependent outcomes on delay discounting.

    Science.gov (United States)

    Naudé, Gideon P; Kaplan, Brent A; Reed, Derek D; Henley, Amy J; DiGennaro Reed, Florence D

    2018-05-01

    Recent research suggests that presenting time intervals as units (e.g., days) or as specific dates, can modulate the degree to which humans discount delayed outcomes. Another framing effect involves explicitly stating that choosing a smaller-sooner reward is mutually exclusive to receiving a larger-later reward, thus presenting choices as an extended sequence. In Experiment 1, participants (N = 201) recruited from Amazon Mechanical Turk completed the Monetary Choice Questionnaire in a 2 (delay framing) by 2 (zero framing) design. Regression suggested a main effect of delay, but not zero, framing after accounting for other demographic variables and manipulations. We observed a rate-dependent effect for the date-framing group, such that those with initially steep discounting exhibited greater sensitivity to the manipulation than those with initially shallow discounting. Subsequent analyses suggest these effects cannot be explained by regression to the mean. Experiment 2 addressed the possibility that the null effect of zero framing was due to within-subject exposure to the hidden- and explicit-zero conditions. A new Amazon Mechanical Turk sample completed the Monetary Choice Questionnaire in either hidden- or explicit-zero formats. Analyses revealed a main effect of reward magnitude, but not zero framing, suggesting potential limitations to the generality of the hidden-zero effect. © 2018 Society for the Experimental Analysis of Behavior.

  2. Global Robust Stability of Switched Interval Neural Networks with Discrete and Distributed Time-Varying Delays of Neural Type

    Directory of Open Access Journals (Sweden)

    Huaiqin Wu

    2012-01-01

    Full Text Available By combing the theories of the switched systems and the interval neural networks, the mathematics model of the switched interval neural networks with discrete and distributed time-varying delays of neural type is presented. A set of the interval parameter uncertainty neural networks with discrete and distributed time-varying delays of neural type are used as the individual subsystem, and an arbitrary switching rule is assumed to coordinate the switching between these networks. By applying the augmented Lyapunov-Krasovskii functional approach and linear matrix inequality (LMI techniques, a delay-dependent criterion is achieved to ensure to such switched interval neural networks to be globally asymptotically robustly stable in terms of LMIs. The unknown gain matrix is determined by solving this delay-dependent LMIs. Finally, an illustrative example is given to demonstrate the validity of the theoretical results.

  3. Comorbid depression, antisocial personality, and substance dependence: Relationship with delay discounting.

    Science.gov (United States)

    Moody, Lara; Franck, Christopher; Bickel, Warren K

    2016-03-01

    Within the field of addiction, as many as four-fifths of individuals in treatment for substance use disorder have co-existing lifetime psychopathology and as high as two-thirds have current psychopathology. Among substance-dependent individuals, excessive delay discounting is pervasive. Despite evidence of excessive discounting across substance use disorders, few studies have investigated the impact of co-occurring psychopathologies and SUD on delay discounting. We compared delay discounting in currently abstaining substance users with (a) SUD (n=166), (b) SUD and managed major depressive disorder (MDD; n=44), (c) SUD and antisocial personality disorder (APD; n=35), (d) SUD and managed MDD and APD (n=22) and (e) no SUD or co-occurring psychopathology (n=60). All groups with SUD discounted future delayed rewards significantly more than healthy controls (p<0.001 in each case, d=0.686, 0.835, 1.098 and 1.650, respective to groups a-d above). Individuals with both APD and SUD and individuals with MDD, APD, and SUD discounted future rewards significantly more than substance users without comorbid psychopathology (p=0.029, d=0.412 and p<0.001, d=0.964, respectively). Overall, individuals with multiple psychopathologies in addition to substance use have exacerbated deficits in discounting of the future, above and beyond that observed in substance use alone. Increased discounting in combined substance and psychopathology profiles suggest a greater chance of treatment failure and therefore may necessitate individualized treatment using adjunctive interventions to achieve better treatment outcomes. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  4. Delay differential equations and the dose-time dependence of early radiotherapy reactions

    International Nuclear Information System (INIS)

    Fenwick, John D.

    2006-01-01

    The dose-time dependence of early radiotherapy reactions impacts on the design of accelerated fractionation schedules--oral mucositis, for example, can be dose limiting for short treatments designed to avoid tumor repopulation. In this paper a framework for modeling early reaction dose-time dependence is developed. Variation of stem cell number with time after the start of a radiation schedule is modeled using a first-order delay differential equation (DDE), motivated by experimental observations linking the speed of compensatory proliferation in early reacting tissues to the degree of tissue damage. The modeling suggests that two types of early reaction radiation response are possible, stem cell numbers either monotonically approaching equilibrium plateau levels or overshooting before returning to equilibrium. Several formulas have been derived from the delay differential equation, predicting changes in isoeffective total radiation dose with schedule duration for different types of fractionation scheme. The formulas have been fitted to a wide range of published animal early reaction data, the fits all implying a degree of overshoot. Results are presented illustrating the scope of the delay differential model: most of the data are fitted well, although the model struggles with a few datasets measured for schedules with distinctive dose-time patterns. Ways of extending the current model to cope with these particular dose-time patterns are briefly discussed. The DDE approach is conceptually more complex than earlier descriptive dose-time models but potentially more powerful. It can be used to study issues not addressed by simpler models, such as the likely effects of increasing or decreasing the dose-per-day over time, or of splitting radiation courses into intense segments separated by gaps. It may also prove useful for modeling the effects of chemoirradiation

  5. Delay differential equations and the dose-time dependence of early radiotherapy reactions.

    Science.gov (United States)

    Fenwick, John D

    2006-09-01

    The dose-time dependence of early radiotherapy reactions impacts on the design of accelerated fractionation schedules--oral mucositis, for example, can be dose limiting for short treatments designed to avoid tumor repopulation. In this paper a framework for modeling early reaction dose-time dependence is developed. Variation of stem cell number with time after the start of a radiation schedule is modeled using a first-order delay differential equation (DDE), motivated by experimental observations linking the speed of compensatory proliferation in early reacting tissues to the degree of tissue damage. The modeling suggests that two types of early reaction radiation response are possible, stem cell numbers either monotonically approaching equilibrium plateau levels or overshooting before returning to equilibrium. Several formulas have been derived from the delay differential equation, predicting changes in isoeffective total radiation dose with schedule duration for different types of fractionation scheme. The formulas have been fitted to a wide range of published animal early reaction data, the fits all implying a degree of overshoot. Results are presented illustrating the scope of the delay differential model: most of the data are fitted well, although the model struggles with a few datasets measured for schedules with distinctive dose-time patterns. Ways of extending the current model to cope with these particular dose-time patterns are briefly discussed. The DDE approach is conceptually more complex than earlier descriptive dose-time models but potentially more powerful. It can be used to study issues not addressed by simpler models, such as the likely effects of increasing or decreasing the dose-per-day over time, or of splitting radiation courses into intense segments separated by gaps. It may also prove useful for modeling the effects of chemoirradiation.

  6. The existence and global exponential stability of a periodic solution of a class of delay differential equations

    International Nuclear Information System (INIS)

    Tang, X H; Zou, Xingfu

    2009-01-01

    By employing Schauder's fixed point theorem and a non-Liapunov method (matrix theory, inequality analysis), we obtain some new criteria that ensure existence and global exponential stability of a periodic solution to a class of functional differential equations. Applying these criteria to a cellular neural network with time delays (delayed cellular neural network, DCNN) under a periodic environment leads to some new results that improve and generalize many existing ones we know on this topic. These results are of great significance in designs and applications of globally stable periodic DCNNs

  7. Stability analysis for an age-dependent vaccination model

    International Nuclear Information System (INIS)

    El-Doma, M.

    1993-05-01

    The stability of an SIR epidemic model with vaccination is investigated. We determine the steady states and examine their stability. Furthermore, a critical vaccination coverage that will eventually eradicate the disease is determined. (author). 9 refs

  8. Stability of Almost Periodic Solution for a General Class of Discontinuous Neural Networks with Mixed Time-Varying Delays

    Directory of Open Access Journals (Sweden)

    Yingwei Li

    2013-01-01

    Full Text Available The global exponential stability issues are considered for almost periodic solution of the neural networks with mixed time-varying delays and discontinuous neuron activations. Some sufficient conditions for the existence, uniqueness, and global exponential stability of almost periodic solution are achieved in terms of certain linear matrix inequalities (LMIs, by applying differential inclusions theory, matrix inequality analysis technique, and generalized Lyapunov functional approach. In addition, the existence and asymptotically almost periodic behavior of the solution of the neural networks are also investigated under the framework of the solution in the sense of Filippov. Two simulation examples are given to illustrate the validity of the theoretical results.

  9. Stability and bifurcation of numerical discretization of a second-order delay differential equation with negative feedback

    International Nuclear Information System (INIS)

    Ding Xiaohua; Su Huan; Liu Mingzhu

    2008-01-01

    The paper analyzes a discrete second-order, nonlinear delay differential equation with negative feedback. The characteristic equation of linear stability is solved, as a function of two parameters describing the strength of the feedback and the damping in the autonomous system. The existence of local Hopf bifurcations is investigated, and the direction and stability of periodic solutions bifurcating from the Hopf bifurcation of the discrete model are determined by the Hopf bifurcation theory of discrete system. Finally, some numerical simulations are performed to illustrate the analytical results found

  10. Neural Network Based Finite-Time Stabilization for Discrete-Time Markov Jump Nonlinear Systems with Time Delays

    Directory of Open Access Journals (Sweden)

    Fei Chen

    2013-01-01

    Full Text Available This paper deals with the finite-time stabilization problem for discrete-time Markov jump nonlinear systems with time delays and norm-bounded exogenous disturbance. The nonlinearities in different jump modes are parameterized by neural networks. Subsequently, a linear difference inclusion state space representation for a class of neural networks is established. Based on this, sufficient conditions are derived in terms of linear matrix inequalities to guarantee stochastic finite-time boundedness and stochastic finite-time stabilization of the closed-loop system. A numerical example is illustrated to verify the efficiency of the proposed technique.

  11. A study on stability and medical implications for a complex delay model for CML with cell competition and treatment.

    Science.gov (United States)

    Rădulescu, I R; Cândea, D; Halanay, A

    2014-12-21

    We study a mathematical model describing the dynamics of leukemic and normal cell populations (stem-like and differentiated) in chronic myeloid leukemia (CML). This model is a system of four delay differential equations incorporating three types of cell division. The competition between normal and leukemic stem cell populations for the common microenvironment is taken into consideration. The stability of one steady state is investigated. The results are discussed via their medical interpretation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Psilocybin dose-dependently causes delayed, transient headaches in healthy volunteers.

    Science.gov (United States)

    Johnson, Matthew W; Sewell, R Andrew; Griffiths, Roland R

    2012-06-01

    Psilocybin is a well-characterized classic hallucinogen (psychedelic) with a long history of religious use by indigenous cultures, and nonmedical use in modern societies. Although psilocybin is structurally related to migraine medications, and case studies suggest that psilocybin may be efficacious in treatment of cluster headache, little is known about the relationship between psilocybin and headache. This double-blind study examined a broad range of psilocybin doses (0, 5, 10, 20, and 30 mg/70 kg) on headache in 18 healthy participants. Psilocybin frequently caused headache, the incidence, duration, and severity of which increased in a dose-dependent manner. All headaches had delayed onset, were transient, and lasted no more than a day after psilocybin administration. Possible mechanisms for these observations are discussed, and include induction of delayed headache through nitric oxide release. These data suggest that headache is an adverse event to be expected with the nonmedical use of psilocybin-containing mushrooms as well as the administration of psilocybin in human research. Headaches were neither severe nor disabling, and should not present a barrier to future psilocybin research. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  13. Adaptive fuzzy observer-based stabilization of a class of uncertain time-delayed chaotic systems with actuator nonlinearities

    International Nuclear Information System (INIS)

    Shahnazi, Reza; Haghani, Adel; Jeinsch, Torsten

    2015-01-01

    An observer-based output feedback adaptive fuzzy controller is proposed to stabilize a class of uncertain chaotic systems with unknown time-varying time delays, unknown actuator nonlinearities and unknown external disturbances. The actuator nonlinearity can be backlash-like hysteresis or dead-zone. Based on universal approximation property of fuzzy systems the unknown nonlinear functions are approximated by fuzzy systems, where the consequent parts of fuzzy rules are tuned with adaptive schemes. The proposed method does not need the availability of the states and an observer based output feedback approach is proposed to estimate the states. To have more robustness and at the same time to alleviate chattering an adaptive discontinuous structure is suggested. Semi-global asymptotic stability of the overall system is ensured by proposing a suitable Lyapunov–Krasovskii functional candidate. The approach is applied to stabilize the time-delayed Lorenz chaotic system with uncertain dynamics amid significant disturbances. Analysis of simulations reveals the effectiveness of the proposed method in terms of coping well with the modeling uncertainties, nonlinearities in actuators, unknown time-varying time-delays and unknown external disturbances while maintaining asymptotic convergence

  14. Global Stability of Polytopic Linear Time-Varying Dynamic Systems under Time-Varying Point Delays and Impulsive Controls

    Directory of Open Access Journals (Sweden)

    M. de la Sen

    2010-01-01

    Full Text Available This paper investigates the stability properties of a class of dynamic linear systems possessing several linear time-invariant parameterizations (or configurations which conform a linear time-varying polytopic dynamic system with a finite number of time-varying time-differentiable point delays. The parameterizations may be timevarying and with bounded discontinuities and they can be subject to mixed regular plus impulsive controls within a sequence of time instants of zero measure. The polytopic parameterization for the dynamics associated with each delay is specific, so that (q+1 polytopic parameterizations are considered for a system with q delays being also subject to delay-free dynamics. The considered general dynamic system includes, as particular cases, a wide class of switched linear systems whose individual parameterizations are timeinvariant which are governed by a switching rule. However, the dynamic system under consideration is viewed as much more general since it is time-varying with timevarying delays and the bounded discontinuous changes of active parameterizations are generated by impulsive controls in the dynamics and, at the same time, there is not a prescribed set of candidate potential parameterizations.

  15. Unconditionally stable difference methods for delay partial differential equations

    OpenAIRE

    Huang, Chengming; Vandewalle, Stefan

    2012-01-01

    This paper is concerned with the numerical solution of parabolic partial differential equations with time-delay. We focus in particular on the delay dependent stability analysis of difference methods that use a non-constrained mesh, i.e., the time step-size is not required to be a submultiple of the delay. We prove that the fully discrete system unconditionally preserves the delay dependent asymptotic stability of the linear test problem under consideration, when the following discretizati...

  16. Stability analysis of stochastic delayed cellular neural networks by LMI approach

    International Nuclear Information System (INIS)

    Zhu Wenli; Hu Jin

    2006-01-01

    Some sufficient mean square exponential stability conditions for a class of stochastic DCNN model are obtained via the LMI approach. These conditions improve and generalize some existing global asymptotic stability conditions for DCNN model

  17. A novel stabilization condition for T-S polynomial fuzzy system with time-delay:A sum-of-squares approach

    OpenAIRE

    Tsai, Shun Hung; Chen, Yu-An; Chen, Yu-Wen; Lo, Ji-Chang; Lam, Hak-Keung

    2017-01-01

    A novel stabilization problem for T-S polynomial fuzzy system with time-delay is investigated in this paper. Firstly, a polynomial fuzzy controller for T-S polynomial fuzzy system with time-delay is proposed. In addition, based on polynomial Lyapunov-Krasovskii function and the developed polynomial slack variable matrices, a novel stabilization condition for T-S polynomial fuzzy system with time-delay is presented in terms of sum-of-square (SOS) form. Lastly, nonlinear system with time-delay ...

  18. Treatment-time-dependence models of early and delayed radiation injury in rat small intestine

    International Nuclear Information System (INIS)

    Denham, James W.; Hauer-Jensen, Martin; Kron, Tomas; Langberg, Carl W.

    2000-01-01

    Background: The present study modeled data from a large series of experiments originally designed to investigate the influence of time, dose, and fractionation on early and late pathologic endpoints in rat small intestine after localized irradiation. The objective was to obtain satisfactory descriptions of the regenerative response to injury together with the possible relationships between early and late endpoints. Methods: Two- and 26-week pathologic radiation injury data in groups of Sprague-Dawley rats irradiated with 27 different fractionation schedules were modeled using the incomplete repair (IR) version of the linear-quadratic model with or without various time correction models. The following time correction models were tested: (1) No time correction; (2) A simple exponential (SE) regenerative response beginning at an arbitrary time after starting treatment; and (3) A bi-exponential response with its commencement linked to accumulated cellular depletion and fraction size (the 'intelligent response model' [INTR]). Goodness of fit of the various models was assessed by correlating the predicted biological effective dose for each dose group with the observed radiation injury score. Results: (1) The incomplete repair model without time correction did not provide a satisfactory description of either the 2- or 26-week data. (2) The models using SE time correction performed better, providing modest descriptions of the data. (3) The INTR model provided reasonable descriptions of both the 2- and 26-week data, confirming a treatment time dependence of both early and late pathological endpoints. (4) The most satisfactory descriptions of the data by the INTR model were obtained when the regenerative response was assumed to cease 2 weeks after irradiation rather than at the end of irradiation. A fraction-size-dependent delay of the regenerative response was also suggested in the best fitting models. (5) Late endpoints were associated with low-fractionation sensitivity

  19. Is there an association between suicide attempt and delay of initiation of mood stabilizers in bipolar I disorder?

    Science.gov (United States)

    Nery-Fernandes, Fabiana; Quarantini, Lucas C; Guimarães, José L; de Oliveira, Irismar R; Koenen, Karestan C; Kapczinski, Flavio; Miranda-Scippa, Ângela

    2012-02-01

    Little is known about the extent to which delay of initiation of mood-stabilizing treatment may influence outcomes in bipolar patients (BP). In this study, our aim was to investigate the association between delay of mood stabilizer treatment in bipolar patients and lifetime history of suicide attempts. A consecutive sample of 268 bipolar I outpatients from two teaching hospitals in Brazil was recruited. The assessment included a socio-demographic history form, a clinical interview regarding clinical variables and the Structured Clinical Interview for DSM-IV. Participants were divided into three groups: BP that initiated the first mood stabilizer in the same year of the first episode of the disease (FMS≤1), between 1 and 5 years after the first episode of the disease (15). The mean time from the first episode until the first mood stabilizer medication was 8.6 years (SD 9.8 years). The FMS>5 group, showed a higher lifetime prevalence of suicide attempts than the other two groups (PR=1.75, 95% CI: 1.24-2.47), p=0.001. These results remained significant after adjusting for potential confounders, (PR=1.82, 95% CI: 1.29-2.60), p=0.001. This study evaluated patients retrospectively and does not permit a cause-effect relationship. The present study supports the importance of early diagnosis and early intervention for BP in order to limit the potentially lethal impact of the disease. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. STABILITY THEOREM FOR A CLASS OF PERTURBED NONAUTONOMOUS NEUTRAL DIFFERENTIAL EQUATION WITH UNBOUNDED DELAY

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this paper, we consider a one-dimensional nonautonomous neutral differential equation. We obtain sufficient conditions under which the zero solution to this equation with unbounded delay and perturbation is uniformly asymptotically stable.

  1. Anticipation from sensation: using anticipating synchronization to stabilize a system with inherent sensory delay.

    Science.gov (United States)

    Eberle, Henry; Nasuto, Slawomir J; Hayashi, Yoshikatsu

    2018-03-01

    We present a novel way of using a dynamical model for predictive tracking control that can adapt to a wide range of delays without parameter update. This is achieved by incorporating the paradigm of anticipating synchronization (AS), where a 'slave' system predicts a 'master' via delayed self-feedback. By treating the delayed output of the plant as one half of a 'sensory' AS coupling, the plant and an internal dynamical model can be synchronized such that the plant consistently leads the target's motion. We use two simulated robotic systems with differing arrangements of the plant and internal model ('parallel' and 'serial') to demonstrate that this form of control adapts to a wide range of delays without requiring the parameters of the controller to be changed.

  2. When Delays Improve Memory: Stabilizing Memory in Children May Require Time

    OpenAIRE

    Darby, Kevin P.; Sloutsky, Vladimir M.

    2015-01-01

    Memory is critical for learning, cognition and cognitive development. Recent work has suggested that preschool-aged children are vulnerable to catastrophic levels of memory interference, in which new learning dramatically attenuates memory for previously acquired knowledge. Work reported here investigates the effects of consolidation on children’s memory by introducing a 48- hours-long delay between learning and testing. In Experiment 1, the delay improved children’s memory and eliminated int...

  3. Stability result of the Timoshenko system with delay and boundary feedback

    KAUST Repository

    Said-Houari, Belkacem; Soufyane, Abdelaziz

    2012-01-01

    Our interest in this paper is to analyse the asymptotic behaviour of a Timoshenko beam system together with two boundary controls, with delay terms in the first and second equation. Assuming the weights of the delay are small enough, we show that the system is well-posed using the semigroup theory. Furthermore, we introduce a Lyapunov functional that gives the exponential decay of the total energy. © 2012 The author.

  4. Stability result of the Timoshenko system with delay and boundary feedback

    KAUST Repository

    Said-Houari, Belkacem

    2012-01-06

    Our interest in this paper is to analyse the asymptotic behaviour of a Timoshenko beam system together with two boundary controls, with delay terms in the first and second equation. Assuming the weights of the delay are small enough, we show that the system is well-posed using the semigroup theory. Furthermore, we introduce a Lyapunov functional that gives the exponential decay of the total energy. © 2012 The author.

  5. Global exponential stability and periodicity of reaction-diffusion recurrent neural networks with distributed delays and Dirichlet boundary conditions

    International Nuclear Information System (INIS)

    Lu Junguo; Lu Linji

    2009-01-01

    In this paper, global exponential stability and periodicity of a class of reaction-diffusion recurrent neural networks with distributed delays and Dirichlet boundary conditions are studied by constructing suitable Lyapunov functionals and utilizing some inequality techniques. We first prove global exponential convergence to 0 of the difference between any two solutions of the original neural networks, the existence and uniqueness of equilibrium is the direct results of this procedure. This approach is different from the usually used one where the existence, uniqueness of equilibrium and stability are proved in two separate steps. Secondly, we prove periodicity. Sufficient conditions ensuring the existence, uniqueness, and global exponential stability of the equilibrium and periodic solution are given. These conditions are easy to verify and our results play an important role in the design and application of globally exponentially stable neural circuits and periodic oscillatory neural circuits.

  6. pth moment exponential stability of stochastic memristor-based bidirectional associative memory (BAM) neural networks with time delays.

    Science.gov (United States)

    Wang, Fen; Chen, Yuanlong; Liu, Meichun

    2018-02-01

    Stochastic memristor-based bidirectional associative memory (BAM) neural networks with time delays play an increasingly important role in the design and implementation of neural network systems. Under the framework of Filippov solutions, the issues of the pth moment exponential stability of stochastic memristor-based BAM neural networks are investigated. By using the stochastic stability theory, Itô's differential formula and Young inequality, the criteria are derived. Meanwhile, with Lyapunov approach and Cauchy-Schwarz inequality, we derive some sufficient conditions for the mean square exponential stability of the above systems. The obtained results improve and extend previous works on memristor-based or usual neural networks dynamical systems. Four numerical examples are provided to illustrate the effectiveness of the proposed results. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. When Delays Improve Memory: Stabilizing Memory in Children May Require Time.

    Science.gov (United States)

    Darby, Kevin P; Sloutsky, Vladimir M

    2015-12-01

    Memory is critical for learning, cognition, and cognitive development. Recent work has suggested that preschool-age children are vulnerable to catastrophic levels of memory interference, in which new learning dramatically attenuates memory for previously acquired knowledge. In the work reported here, we investigated the effects of consolidation on children's memory by introducing a 48-hr delay between learning and testing. In Experiment 1, the delay improved children's memory and eliminated interference. Results of Experiment 2 suggest that the benefit of this delay is limited to situations in which children are given enough information to form complex memory structures. These findings have important implications for understanding consolidation processes and memory development. © The Author(s) 2015.

  8. Existence and asymptotic stability of a viscoelastic wave equation with a delay

    KAUST Repository

    Kirane, Mokhtar

    2011-07-07

    In this paper, we consider the viscoelastic wave equation with a delay term in internal feedbacks; namely, we investigate the following problem, together with initial conditions and boundary conditions of Dirichlet type. Here (x, t) ∈ Ω × (0, ∞), g is a positive real valued decreasing function and μ1, μ2 are positive constants. Under an hypothesis between the weight of the delay term in the feedback and the weight of the term without delay, using the Faedo-Galerkin approximations together with some energy estimates, we prove the global existence of the solutions. Under the same assumptions, general decay results of the energy are established via suitable Lyapunov functionals. © 2011 Springer Basel AG.

  9. Existence and asymptotic stability of a viscoelastic wave equation with a delay

    KAUST Repository

    Kirane, Mokhtar; Said-Houari, Belkacem

    2011-01-01

    In this paper, we consider the viscoelastic wave equation with a delay term in internal feedbacks; namely, we investigate the following problem, together with initial conditions and boundary conditions of Dirichlet type. Here (x, t) ∈ Ω × (0, ∞), g is a positive real valued decreasing function and μ1, μ2 are positive constants. Under an hypothesis between the weight of the delay term in the feedback and the weight of the term without delay, using the Faedo-Galerkin approximations together with some energy estimates, we prove the global existence of the solutions. Under the same assumptions, general decay results of the energy are established via suitable Lyapunov functionals. © 2011 Springer Basel AG.

  10. Non-fragile robust stabilization and H{sub {infinity}} control for uncertain stochastic nonlinear time-delay systems

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Jinhui [Department of Automatic Control, Beijing Institute of Technology, Beijing 100081 (China)], E-mail: jinhuizhang82@gmail.com; Shi Peng [Faculty of Advanced Technology, University of Glamorgan, Pontypridd CF37 1DL (United Kingdom); ILSCM, School of Science and Engineering, Victoria University, Melbourne, Vic. 8001 (Australia); School of Mathematics and Statistics, University of South Australia, Mawson Lakes, SA 5095 (Australia)], E-mail: pshi@glam.ac.uk; Yang Hongjiu [Department of Automatic Control, Beijing Institute of Technology, Beijing 100081 (China)], E-mail: yanghongjiu@gmail.com

    2009-12-15

    This paper deals with the problem of non-fragile robust stabilization and H{sub {infinity}} control for a class of uncertain stochastic nonlinear time-delay systems. The parametric uncertainties are real time-varying as well as norm bounded. The time-delay factors are unknown and time-varying with known bounds. The aim is to design a memoryless non-fragile state feedback control law such that the closed-loop system is stochastically asymptotically stable in the mean square and the effect of the disturbance input on the controlled output is less than a prescribed level for all admissible parameter uncertainties. New sufficient conditions for the existence of such controllers are presented based on the linear matrix inequalities (LMIs) approach. Numerical example is given to illustrate the effectiveness of the developed techniques.

  11. Stability of abstract nonlinear nonautonomous differential-delay equations with unbounded history-responsive operators

    Science.gov (United States)

    Gil', M. I.

    2005-08-01

    We consider a class of nonautonomous functional-differential equations in a Banach space with unbounded nonlinear history-responsive operators, which have the local Lipshitz property. Conditions for the boundedness of solutions, Lyapunov stability, absolute stability and input-output one are established. Our approach is based on a combined usage of properties of sectorial operators and spectral properties of commuting operators.

  12. Delay selection by spike-timing-dependent plasticity in recurrent networks of spiking neurons receiving oscillatory inputs.

    Directory of Open Access Journals (Sweden)

    Robert R Kerr

    Full Text Available Learning rules, such as spike-timing-dependent plasticity (STDP, change the structure of networks of neurons based on the firing activity. A network level understanding of these mechanisms can help infer how the brain learns patterns and processes information. Previous studies have shown that STDP selectively potentiates feed-forward connections that have specific axonal delays, and that this underlies behavioral functions such as sound localization in the auditory brainstem of the barn owl. In this study, we investigate how STDP leads to the selective potentiation of recurrent connections with different axonal and dendritic delays during oscillatory activity. We develop analytical models of learning with additive STDP in recurrent networks driven by oscillatory inputs, and support the results using simulations with leaky integrate-and-fire neurons. Our results show selective potentiation of connections with specific axonal delays, which depended on the input frequency. In addition, we demonstrate how this can lead to a network becoming selective in the amplitude of its oscillatory response to this frequency. We extend this model of axonal delay selection within a single recurrent network in two ways. First, we show the selective potentiation of connections with a range of both axonal and dendritic delays. Second, we show axonal delay selection between multiple groups receiving out-of-phase, oscillatory inputs. We discuss the application of these models to the formation and activation of neuronal ensembles or cell assemblies in the cortex, and also to missing fundamental pitch perception in the auditory brainstem.

  13. Investigation of capture reactions far off stability by β-delayed neutron emission

    International Nuclear Information System (INIS)

    Wiescher, M.; Leist, B.; Ziegert, W.; Gabelmann, H.; Steinmueller, B.; Ohm, H.; Kratz, K.h.; Thielemann, F.h.; Hillebrandt, W.

    1985-01-01

    Beta-delayed neutron spectroscopy is applied to determine reaction rates of neutron capture on several neutron rich nuclei. The results of these experiments are presented and discussed in the light of their astrophysical implications. Furthermore, the experimental possibilities and limits of planned measurements are advertised

  14. Asymptotic behavior and stability of second order neutral delay differential equations

    NARCIS (Netherlands)

    Chen, G.L.; van Gaans, O.W.; Verduyn Lunel, Sjoerd

    2014-01-01

    We study the asymptotic behavior of a class of second order neutral delay differential equations by both a spectral projection method and an ordinary differential equation method approach. We discuss the relation of these two methods and illustrate some features using examples. Furthermore, a fixed

  15. Chikungunya virus–induced autophagy delays caspase-dependent cell death

    Science.gov (United States)

    Joubert, Pierre-Emmanuel; Werneke, Scott W.; de la Calle, Claire; Guivel-Benhassine, Florence; Giodini, Alessandra; Peduto, Lucie; Levine, Beth; Schwartz, Olivier; Lenschow, Deborah J.

    2012-01-01

    Autophagy is an important survival pathway and can participate in the host response to infection. Studying Chikungunya virus (CHIKV), the causative agent of a major epidemic in India, Southeast Asia, and southern Europe, we reveal a novel mechanism by which autophagy limits cell death and mortality after infection. We use biochemical studies and single cell multispectral assays to demonstrate that direct infection triggers both apoptosis and autophagy. CHIKV-induced autophagy is mediated by the independent induction of endoplasmic reticulum and oxidative stress pathways. These cellular responses delay apoptotic cell death by inducing the IRE1α–XBP-1 pathway in conjunction with ROS-mediated mTOR inhibition. Silencing of autophagy genes resulted in enhanced intrinsic and extrinsic apoptosis, favoring viral propagation in cultured cells. Providing in vivo evidence for the relevance of our findings, Atg16LHM mice, which display reduced levels of autophagy, exhibited increased lethality and showed a higher sensitivity to CHIKV-induced apoptosis. Based on kinetic studies and the observation that features of apoptosis and autophagy were mutually exclusive, we conclude that autophagy inhibits caspase-dependent cell death but is ultimately overwhelmed by viral replication. Our study suggests that inducers of autophagy may limit the pathogenesis of acute Chikungunya disease. PMID:22508836

  16. Numerical Bifurcation Analysis of Delayed Recycle Stream in a Continuously Stirred Tank Reactor

    Science.gov (United States)

    Gangadhar, Nalwala Rohitbabu; Balasubramanian, Periyasamy

    2010-10-01

    In this paper, we present the stability analysis of delay differential equations which arise as a result of transportation lag in the CSTR-mechanical separator recycle system. A first order irreversible elementary reaction is considered to model the system and is governed by the delay differential equations. The DDE-BIFTOOL software package is used to analyze the stability of the delay system. The present analysis reveals that the system exhibits delay independent stability for isothermal operation of the CSTR. In the absence of delay, the system is dynamically unstable for non-isothermal operation of the CSTR, and as a result of delay, the system exhibits delay dependent stability.

  17. Robust Stability for Nonlinear Systems with Time-Varying Delay and Uncertainties via the H∞ Quasi-Sliding Mode Control

    Directory of Open Access Journals (Sweden)

    Yi-You Hou

    2014-01-01

    Full Text Available This paper considers the problem of the robust stability for the nonlinear system with time-varying delay and parameters uncertainties. Based on the H∞ theorem, Lyapunov-Krasovskii theory, and linear matrix inequality (LMI optimization technique, the H∞ quasi-sliding mode controller and switching function are developed such that the nonlinear system is asymptotically stable in the quasi-sliding mode and satisfies the disturbance attenuation (H∞-norm performance. The effectiveness and accuracy of the proposed methods are shown in numerical simulations.

  18. Convergence and Stability of the Split-Step θ-Milstein Method for Stochastic Delay Hopfield Neural Networks

    Directory of Open Access Journals (Sweden)

    Qian Guo

    2013-01-01

    Full Text Available A new splitting method designed for the numerical solutions of stochastic delay Hopfield neural networks is introduced and analysed. Under Lipschitz and linear growth conditions, this split-step θ-Milstein method is proved to have a strong convergence of order 1 in mean-square sense, which is higher than that of existing split-step θ-method. Further, mean-square stability of the proposed method is investigated. Numerical experiments and comparisons with existing methods illustrate the computational efficiency of our method.

  19. Existence and global exponential stability of periodic solution to BAM neural networks with periodic coefficients and continuously distributed delays

    International Nuclear Information System (INIS)

    Zhou Tiejun; Chen Anping; Zhou Yuyuan

    2005-01-01

    By using the continuation theorem of coincidence degree theory and Liapunov function, we obtain some sufficient criteria to ensure the existence and global exponential stability of periodic solution to the bidirectional associative memory (BAM) neural networks with periodic coefficients and continuously distributed delays. These results improve and generalize the works of papers [J. Cao, L. Wang, Phys. Rev. E 61 (2000) 1825] and [Z. Liu, A. Chen, J. Cao, L. Huang, IEEE Trans. Circuits Systems I 50 (2003) 1162]. An example is given to illustrate that the criteria are feasible

  20. Existence and global exponential stability of periodic solution to BAM neural networks with periodic coefficients and continuously distributed delays

    Science.gov (United States)

    Zhou, distributed delays [rapid communication] T.; Chen, A.; Zhou, Y.

    2005-08-01

    By using the continuation theorem of coincidence degree theory and Liapunov function, we obtain some sufficient criteria to ensure the existence and global exponential stability of periodic solution to the bidirectional associative memory (BAM) neural networks with periodic coefficients and continuously distributed delays. These results improve and generalize the works of papers [J. Cao, L. Wang, Phys. Rev. E 61 (2000) 1825] and [Z. Liu, A. Chen, J. Cao, L. Huang, IEEE Trans. Circuits Systems I 50 (2003) 1162]. An example is given to illustrate that the criteria are feasible.

  1. Synchronization stability of memristor-based complex-valued neural networks with time delays.

    Science.gov (United States)

    Liu, Dan; Zhu, Song; Ye, Er

    2017-12-01

    This paper focuses on the dynamical property of a class of memristor-based complex-valued neural networks (MCVNNs) with time delays. By constructing the appropriate Lyapunov functional and utilizing the inequality technique, sufficient conditions are proposed to guarantee exponential synchronization of the coupled systems based on drive-response concept. The proposed results are very easy to verify, and they also extend some previous related works on memristor-based real-valued neural networks. Meanwhile, the obtained sufficient conditions of this paper may be conducive to qualitative analysis of some complex-valued nonlinear delayed systems. A numerical example is given to demonstrate the effectiveness of our theoretical results. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Oxygenation measurement by multi-wavelength oxygen-dependent phosphorescence and delayed fluorescence: catchment depth and application in intact heart

    NARCIS (Netherlands)

    Balestra, Gianmarco M.; Aalders, Maurice C. G.; Specht, Patricia A. C.; Ince, Can; Mik, Egbert G.

    2015-01-01

    Oxygen delivery and metabolism represent key factors for organ function in health and disease. We describe the optical key characteristics of a technique to comprehensively measure oxygen tension (PO(2)) in myocardium, using oxygen-dependent quenching of phosphorescence and delayed fluorescence of

  3. About the Existence Results of Fractional Neutral Integrodifferential Inclusions with State-Dependent Delay in Fréchet Spaces

    Directory of Open Access Journals (Sweden)

    Selvaraj Suganya

    2016-01-01

    Full Text Available A recent nonlinear alternative for multivalued contractions in Fréchet spaces thanks to Frigon fixed point theorem consolidated with semigroup theory is utilized to examine the existence results for fractional neutral integrodifferential inclusions (FNIDI with state-dependent delay (SDD. An example is described to represent the hypothesis.

  4. Very Long Baseline Interferometry: Dependencies on Frequency Stability

    Science.gov (United States)

    Nothnagel, Axel; Nilsson, Tobias; Schuh, Harald

    2018-04-01

    Very Long Baseline Interferometry (VLBI) is a differential technique observing radiation of compact extra-galactic radio sources with pairs of radio telescopes. For these observations, the frequency standards at the telescopes need to have very high stability. In this article we discuss why this is, and we investigate exactly how precise the frequency standards need to be. Four areas where good clock performance is needed are considered: coherence, geodetic parameter estimation, correlator synchronization, and UT1 determination. We show that in order to ensure the highest accuracy of VLBI, stability similar to that of a hydrogen maser is needed for time-scales up to a few hours. In the article, we are considering both traditional VLBI where extra-galactic radio sources are observed, as well as observation of man-made artificial radio sources emitted by satellites or spacecrafts.

  5. Dependence of the Stabilization of -Alumina on the Spray Process

    Czech Academy of Sciences Publication Activity Database

    Stahr, C.Ch.; Saaro, S.; Berger, L.-M.; Herrmann, M.; Dubský, Jiří; Neufuss, Karel

    2007-01-01

    Roč. 16, 5-6 (2007), s. 822-830 ISSN 1059-9630 R&D Projects: GA ČR(CZ) GA106/05/0483 Institutional research plan: CEZ:AV0Z20430508 Keywords : -Al2O3 stabilization * alumina * chromia * solid solution * X-ray diffraction Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.204, year: 2007

  6. Introducing conjoint analysis method into delayed lotteries studies: its validity and time stability are higher than in adjusting.

    Science.gov (United States)

    Białek, Michał; Markiewicz, Łukasz; Sawicki, Przemysław

    2015-01-01

    The delayed lotteries are much more common in everyday life than are pure lotteries. Usually, we need to wait to find out the outcome of the risky decision (e.g., investing in a stock market, engaging in a relationship). However, most research has studied the time discounting and probability discounting in isolation using the methodologies designed specifically to track changes in one parameter. Most commonly used method is adjusting, but its reported validity and time stability in research on discounting are suboptimal. The goal of this study was to introduce the novel method for analyzing delayed lotteries-conjoint analysis-which hypothetically is more suitable for analyzing individual preferences in this area. A set of two studies compared the conjoint analysis with adjusting. The results suggest that individual parameters of discounting strength estimated with conjoint have higher predictive value (Study 1 and 2), and they are more stable over time (Study 2) compared to adjusting. We discuss these findings, despite the exploratory character of reported studies, by suggesting that future research on delayed lotteries should be cross-validated using both methods.

  7. Introducing conjoint analysis method into delayed lotteries studies: Its validity and time stability are higher than in adjusting

    Directory of Open Access Journals (Sweden)

    Michal eBialek

    2015-01-01

    Full Text Available The delayed lotteries are much more common in everyday life than are pure lotteries. Usually, we need to wait to find out the outcome of the risky decision (e.g., investing in a stock market, engaging in a relationship. However, most research has studied the time discounting and probability discounting in isolation using the methodologies designed specifically to track changes in one parameter. Most commonly used method is adjusting, but its reported validity and time stability in research on discounting are suboptimal.The goal of this study was to introduce the novel method for analyzing delayed lotteries - conjoint analysis - which hypothetically is more suitable for analyzing individual preferences in this area. A set of two studies compared the conjoint analysis with adjusting. The results suggest that individual parameters of discounting strength estimated with conjoint have higher predictive value (Study 1 & 2, and they are more stable over time (Study 2 compared to adjusting. We discuss these findings, despite the exploratory character of reported studies, by suggesting that future research on delayed lotteries should be cross-validated using both methods.

  8. Periodicity and global exponential stability of generalized Cohen-Grossberg neural networks with discontinuous activations and mixed delays.

    Science.gov (United States)

    Wang, Dongshu; Huang, Lihong

    2014-03-01

    In this paper, we investigate the periodic dynamical behaviors for a class of general Cohen-Grossberg neural networks with discontinuous right-hand sides, time-varying and distributed delays. By means of retarded differential inclusions theory and the fixed point theorem of multi-valued maps, the existence of periodic solutions for the neural networks is obtained. After that, we derive some sufficient conditions for the global exponential stability and convergence of the neural networks, in terms of nonsmooth analysis theory with generalized Lyapunov approach. Without assuming the boundedness (or the growth condition) and monotonicity of the discontinuous neuron activation functions, our results will also be valid. Moreover, our results extend previous works not only on discrete time-varying and distributed delayed neural networks with continuous or even Lipschitz continuous activations, but also on discrete time-varying and distributed delayed neural networks with discontinuous activations. We give some numerical examples to show the applicability and effectiveness of our main results. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Distance Dependent Model for the Delay Power Spectrum of In-room Radio Channels

    DEFF Research Database (Denmark)

    Steinböck, Gerhard; Pedersen, Troels; Fleury, Bernard Henri

    2013-01-01

    A model based on experimental observations of the delay power spectrum in closed rooms is proposed. The model includes the distance between the transmitter and the receiver as a parameter which makes it suitable for range based radio localization. The experimental observations motivate the proposed...... model of the delay power spectrum with a primary (early) component and a reverberant component (tail). The primary component is modeled as a Dirac delta function weighted according to an inverse distance power law (d-n). The reverberant component is an exponentially decaying function with onset equal...... to the propagation time between transmitter and receiver. Its power decays exponentially with distance. The proposed model allows for the prediction of e.g. the path loss, mean delay, root mean squared (rms) delay spread, and kurtosis versus the distance. The model predictions are validated by measurements...

  10. Effect of toxic substance on delayed competitive allelopathic phytoplankton system with varying parameters through stability and bifurcation analysis

    International Nuclear Information System (INIS)

    Pal, D.; Mahapatra, G.S.

    2016-01-01

    Highlights: • We study a delayed two species competitive system with imprecise biological parameters. • We consider impreciseness in the form of interval number. • We introduce parametric functional form of interval number to study the model. • We study the effect of toxicant and time delay under impreciseness. • We discuss the chaotic behavior of the model. - Abstract: We have studied the combined effect of toxicant and fluctuation of the biological parameters on the dynamical behaviors of a delayed two-species competitive system with imprecise biological parameters. Due to the global increase of harmful phytoplankton blooms, the study of dynamic interactions between two competing phytoplankton species in the presence of toxic substances is an active field of research now days. The ordinary mathematical formulation of models for two competing phytoplankton species, when one or both the species liberate toxic substances, is unable to capture the oscillatory and highly variable growth of phytoplankton populations. The deterministic model never predicts the sudden localized behavior of certain species. These obstacles of mathematical modeling can be overcomed if we include interval variability of biological parameters in our modeling approach. In this investigation, we construct imprecise models of allelopathic interactions between two competing phytoplankton species as a parametric differential equation model. We incorporate the effect of toxicant on the species in two different cases known as toxic inhibition and toxic stimulatory system. We have discussed the existence of various equilibrium points and stability of the system at these equilibrium points. In case of toxic stimulatory system, the delay model exhibits a stable limit cycle oscillation. Analytical findings are supported through exhaustive numerical simulations.

  11. Permanence of a Semi-Ratio-Dependent Predator-Prey System with Nonmonotonic Functional Response and Time Delay

    Directory of Open Access Journals (Sweden)

    Xuepeng Li

    2009-01-01

    Full Text Available Sufficient conditions for permanence of a semi-ratio-dependent predator-prey system with nonmonotonic functional response and time delay ̇1(=1([1(−11(1(−(−12(2(/(2+21(],  ̇2(=2([2(−21(2(/1(], are obtained, where 1( and 2( stand for the density of the prey and the predator, respectively, and ≠0 is a constant. (≥0 stands for the time delays due to negative feedback of the prey population.

  12. Dependence of the cutoff in lithium plasma harmonics on the delay between the prepulse and the main pulse

    International Nuclear Information System (INIS)

    Suzuki, M; Baba, M; Kuroda, H; Ganeev, R A; Bom, L B Elouga; Ozaki, T

    2012-01-01

    We demonstrated the generation of the 43rd harmonic at the wavelength of 18.49 nm (67 eV photon energy) by using laser-ablation lithium plasma irradiated by a Ti:sapphire laser pulse. We found that for low-Z material, such as lithium, the cutoff energy depends strongly on the delay time between the prepulse and the main pulse, due to rapid recombination. As a result, the maximum cutoff energy was obtained at a relatively short delay of 24 ns. From the theoretical cutoff rule and hydrodynamic simulations, we show that these harmonics were generated from singly charged lithium ions. (paper)

  13. Exponential stability of continuous-time and discrete-time bidirectional associative memory networks with delays

    International Nuclear Information System (INIS)

    Liang Jinling; Cao Jinde

    2004-01-01

    First, convergence of continuous-time Bidirectional Associative Memory (BAM) neural networks are studied. By using Lyapunov functionals and some analysis technique, the delay-independent sufficient conditions are obtained for the networks to converge exponentially toward the equilibrium associated with the constant input sources. Second, discrete-time analogues of the continuous-time BAM networks are formulated and studied. It is shown that the convergence characteristics of the continuous-time systems are preserved by the discrete-time analogues without any restriction imposed on the uniform discretionary step size. An illustrative example is given to demonstrate the effectiveness of the obtained results

  14. Almost Surely Asymptotic Stability of Numerical Solutions for Neutral Stochastic Delay Differential Equations

    Directory of Open Access Journals (Sweden)

    Zhanhua Yu

    2011-01-01

    convergence theorem. It is shown that the Euler method and the backward Euler method can reproduce the almost surely asymptotic stability of exact solutions to NSDDEs under additional conditions. Numerical examples are demonstrated to illustrate the effectiveness of our theoretical results.

  15. Inventory model with cash flow oriented and time-dependent holding cost under permissible delay in payments

    Directory of Open Access Journals (Sweden)

    Tripathi R.P.

    2013-01-01

    Full Text Available This study develops an inventory model for determining an optimal ordering policy for non-deteriorating items and time-dependent holding cost with delayed payments permitted by the supplier under inflation and time-discounting. The discounted cash flows approach is applied to study the problem analysis. Mathematical models have been derived under two different situations i.e. case I: The permissible delay period is less than cycle time for settling the account and case II: The permissible delay period is greater than or equal to cycle time for settling the account. An algorithm is used to obtain minimum total present value of the costs over the time horizon H. Finally, numerical example and sensitivity analysis demonstrate the applicability of the proposed model. The main purpose of this paper is to investigate the optimal cycle time and optimal payment time for an item so that annual total relevant cost is minimized.

  16. Global exponential stability of BAM neural networks with delays and impulses

    International Nuclear Information System (INIS)

    Li Yongkun

    2005-01-01

    Sufficient conditions are obtained for the existence and global exponential stability of a unique equilibrium of a class of two-layer heteroassociative networks called bidirectional associative memory (BAM) networks with Lipschitzian activation functions without assuming their boundedness, monotonicity or differentiability and subjected to impulsive state displacements at fixed instants of time. An illustrative example is given to demonstrate the effectiveness of the obtained results

  17. Some new results on stability and synchronization for delayed inertial neural networks based on non-reduced order method.

    Science.gov (United States)

    Li, Xuanying; Li, Xiaotong; Hu, Cheng

    2017-12-01

    In this paper, without transforming the second order inertial neural networks into the first order differential systems by some variable substitutions, asymptotic stability and synchronization for a class of delayed inertial neural networks are investigated. Firstly, a new Lyapunov functional is constructed to directly propose the asymptotic stability of the inertial neural networks, and some new stability criteria are derived by means of Barbalat Lemma. Additionally, by designing a new feedback control strategy, the asymptotic synchronization of the addressed inertial networks is studied and some effective conditions are obtained. To reduce the control cost, an adaptive control scheme is designed to realize the asymptotic synchronization. It is noted that the dynamical behaviors of inertial neural networks are directly analyzed in this paper by constructing some new Lyapunov functionals, this is totally different from the traditional reduced-order variable substitution method. Finally, some numerical simulations are given to demonstrate the effectiveness of the derived theoretical results. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. TDTORT: Time-Dependent, 3-D, Discrete Ordinates, Neutron Transport Code System with Delayed Neutrons

    International Nuclear Information System (INIS)

    2002-01-01

    1 - Description of program or function: TDTORT solves the time-dependent, three-dimensional neutron transport equation with explicit representation of delayed neutrons to estimate the fission yield from fissionable material transients. This release includes a modified version of TORT from the C00650MFMWS01 DOORS3.1 code package plus the time-dependent TDTORT code. GIP is also included for cross-section preparation. TORT calculates the flux or fluence of particles due to particles incident upon the system from extraneous sources or generated internally as a result of interaction with the system in two- or three-dimensional geometric systems. The principle application is to the deep-penetration transport of neutrons and photons. Reactor eigenvalue problems can also be solved. Numerous printed edits of the results are available, and results can be transferred to output files for subsequent analysis. TDTORT reads ANISN-format cross-section libraries, which are not included in the package. Users may choose from several available in RSICC's data library collection which can be identified by the keyword 'ANISN FORMAT'. 2 - Methods:The time-dependent spatial flux is expressed as a product of a space-, energy-, and angle-dependent shape function, which is usually slowly varying in time and a purely time-dependent amplitude function. The shape equation is solved for the shape using TORT; and the result is used to calculate the point kinetics parameters (e.g., reactivity) by using their inner product definitions, which are then used to solve the time-dependent amplitude and precursor equations. The amplitude function is calculated by solving the kinetics equations using the LSODE solver. When a new shape calculation is needed, the flux is calculated using the newly computed amplitude function. The Boltzmann transport equation is solved using the method of discrete ordinates to treat the directional variable and weighted finite-difference methods, in addition to Linear Nodal

  19. Micromachined silicon acoustic delay line with 3D-printed micro linkers and tapered input for improved structural stability and acoustic directivity

    International Nuclear Information System (INIS)

    Cho, Y; Kumar, A; Xu, S; Zou, J

    2016-01-01

    Recent studies have shown that micromachined silicon acoustic delay lines can provide a promising solution to achieve real-time photoacoustic tomography without the need for complex transducer arrays and data acquisition electronics. To achieve deeper imaging depth and wider field of view, a longer delay time and therefore delay length are required. However, as the length of the delay line increases, it becomes more vulnerable to structural instability due to reduced mechanical stiffness. In this paper, we report the design, fabrication, and testing of a new silicon acoustic delay line enhanced with 3D printed polymer micro linker structures. First, mechanical deformation of the silicon acoustic delay line (with and without linker structures) under gravity was simulated by using finite element method. Second, the acoustic crosstalk and acoustic attenuation caused by the polymer micro linker structures were evaluated with both numerical simulation and ultrasound transmission testing. The result shows that the use of the polymer micro linker structures significantly improves the structural stability of the silicon acoustic delay lines without creating additional acoustic attenuation and crosstalk. In addition, the improvement of the acoustic acceptance angle of the silicon acoustic delay lines was also investigated to better suppress the reception of unwanted ultrasound signals outside of the imaging plane. These two improvements are expected to provide an effective solution to eliminate current limitations on the achievable acoustic delay time and out-of-plane imaging resolution of micromachined silicon acoustic delay line arrays. (paper)

  20. Effects of linear and nonlinear time-delayed feedback on the noise-enhanced stability phenomenon in a periodically driven bistable system

    International Nuclear Information System (INIS)

    Jia, Zheng-Lin; Mei, Dong-Cheng

    2011-01-01

    We investigate numerically the effects of time delay on the phenomenon of noise-enhanced stability (NES) in a periodically modulated bistable system. Three types of time-delayed feedback, including linear delayed feedback, nonlinear delayed feedback and global delayed feedback, are considered. We find a non-monotonic behaviour of the mean first-passage time (MFPT) as a function of the delay time τ, with a maximum in the case of linear delayed feedback and with a minimum in the case of nonlinear delayed feedback. There are two peculiar values of τ around which the NES phenomenon is enhanced or weakened. For the case of global delayed feedback, the increase of τ always weakens the NES phenomenon. Moreover, we also show that the amplitude A and the frequency Ω of the periodic forcing play an opposite role in the NES phenomenon, i.e. the increase of A weakens the NES effect while the increase of Ω enhances it. These observations demonstrate that the time-delayed feedback can be used as a feasible control scheme for the NES phenomenon

  1. Temporal stability of diagnostic criteria for antisocial personality disorder in male alcohol dependent patients

    NARCIS (Netherlands)

    Verheul, R.; van den Brink, W.; Koeter, M. W.

    1998-01-01

    We evaluated the temporal stability of diagnostic criteria for antisocial personality disorder in 432 male alcohol dependent patients. Indicators for temporal stability were criterion continuation (i.e., the proportion of current or recent diagnoses among those with a lifetime diagnosis) and

  2. Stability analysis of nonlinear integro-differential equations arising in age-dependent epidemic models

    International Nuclear Information System (INIS)

    El Doma, M.

    1995-05-01

    An age-structured epidemic model of an SI type that incorporate vertical transmission is investigated when the fertility and mortality rates depend on age. We determine the steady states and examine their stabilities. (author). 13 refs

  3. Existence and global exponential stability of periodic solution of memristor-based BAM neural networks with time-varying delays.

    Science.gov (United States)

    Li, Hongfei; Jiang, Haijun; Hu, Cheng

    2016-03-01

    In this paper, we investigate a class of memristor-based BAM neural networks with time-varying delays. Under the framework of Filippov solutions, boundedness and ultimate boundedness of solutions of memristor-based BAM neural networks are guaranteed by Chain rule and inequalities technique. Moreover, a new method involving Yoshizawa-like theorem is favorably employed to acquire the existence of periodic solution. By applying the theory of set-valued maps and functional differential inclusions, an available Lyapunov functional and some new testable algebraic criteria are derived for ensuring the uniqueness and global exponential stability of periodic solution of memristor-based BAM neural networks. The obtained results expand and complement some previous work on memristor-based BAM neural networks. Finally, a numerical example is provided to show the applicability and effectiveness of our theoretical results. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Stability of 99Tcsup(m)-DTPA injection: effect of delay after preparation, dilution, generator oxidant, air and oxygen

    International Nuclear Information System (INIS)

    Sampson, C.B.; Keegan, J.

    1985-01-01

    99 Tcsup(m)-DTPA injection is widely used in different activity concentrations and the parent solution may require dilution to achieve the correct activity and dose volume. The stability was studied after dilution of six makes of commercially available DTPA kits and it has been demonstrated that levels of free pertechnetate may reach as high as 95%. It has also been demonstrated that levels are increased by subdivision of the parent solution into vials containing air or high quantities of oxygen, by reconstitution with generator eluate containing oxidant, and by delay between preparation and injection into patients. Out of six makes tested only two were stable over a wide variety of conditions. (author)

  5. Existence and controllability results for damped second order impulsive functional differential systems with state-dependent delay

    Directory of Open Access Journals (Sweden)

    M. Mallika Arjunan

    2014-01-01

    Full Text Available In this paper, we investigate the existence and controllability of mild solutions for a damped second order impulsive functional differential equation with state-dependent delay in Banach spaces. The results are obtained by using Sadovskii's fixed point theorem combined with the theories of a strongly continuous cosine family of bounded linear operators. Finally, an example is provided to illustrate the main results.

  6. Peculiar time dependence of unexpected lines in delayed beam-foil X-ray spectra of V, Fe and Ni

    International Nuclear Information System (INIS)

    Ahmad, Nissar; Karn, Ranjeet K.; Marketos, Pan; Nandi, T.

    2005-01-01

    Delayed beam-foil X-ray spectra of highly charged ions of V, Fe and Ni show a few lines at energies higher than the H-like Lyman α-line of the respective projectile ions. These can only be attributed to heavier ions. Further the time dependence of such unexpected lines display a peculiar behavior. This work presents the experimental observations systematically

  7. Position-dependent radiative transfer as a tool for studying Anderson localization: Delay time, time-reversal and coherent backscattering

    Science.gov (United States)

    van Tiggelen, B. A.; Skipetrov, S. E.; Page, J. H.

    2017-05-01

    Previous work has established that the localized regime of wave transport in open media is characterized by a position-dependent diffusion coefficient. In this work we study how the concept of position-dependent diffusion affects the delay time, the transverse confinement, the coherent backscattering, and the time reversal of waves. Definitions of energy transport velocity of localized waves are proposed. We start with a phenomenological model of radiative transfer and then present a novel perturbational approach based on the self-consistent theory of localization. The latter allows us to obtain results relevant for realistic experiments in disordered quasi-1D wave guides and 3D slabs.

  8. Global stability results for a generalized Lotka-Volterra system with distributed delays. Applications to predator-prey and to epidemic systems.

    Science.gov (United States)

    Beretta, E; Capasso, V; Rinaldi, F

    1988-01-01

    The paper contains an extension of the general ODE system proposed in previous papers by the same authors, to include distributed time delays in the interaction terms. The new system describes a large class of Lotka-Volterra like population models and epidemic models with continuous time delays. Sufficient conditions for the boundedness of solutions and for the global asymptotic stability of nontrivial equilibrium solutions are given. A detailed analysis of the epidemic system is given with respect to the conditions for global stability. For a relevant subclass of these systems an existence criterion for steady states is also given.

  9. Boundary layer phenomena for differential-delay equations with state-dependent time lags, I.

    Science.gov (United States)

    Mallet-Paret, John; Nussbaum, Roger D.

    1992-11-01

    In this paper we begin a study of the differential-delay equation \\varepsilon x'(t) = - x(t) + f(x(t - r)), r = r(x(t)) . We prove the existence of periodic solutions for 0equations. In a companion paper these results will be used to investigate the limiting profile and corresponding boundary layer phenomena for periodic solutions as ɛ approaches zero.

  10. Strong Delayed Interactive Effects of Metal Exposure and Warming: Latitude-Dependent Synergisms Persist Across Metamorphosis.

    Science.gov (United States)

    Debecker, Sara; Dinh, Khuong V; Stoks, Robby

    2017-02-21

    As contaminants are often more toxic at higher temperatures, predicting their impact under global warming remains a key challenge for ecological risk assessment. Ignoring delayed effects, synergistic interactions between contaminants and warming, and differences in sensitivity across species' ranges could lead to an important underestimation of the risks. We addressed all three mechanisms by studying effects of larval exposure to zinc and warming before, during, and after metamorphosis in Ischnura elegans damselflies from high- and low-latitude populations. By integrating these mechanisms into a single study, we could identify two novel patterns. First, during exposure zinc did not affect survival, whereas it induced mild to moderate postexposure mortality in the larval stage and at metamorphosis, and very strongly reduced adult lifespan. This severe delayed effect across metamorphosis was especially remarkable in high-latitude animals, as they appeared almost insensitive to zinc during the larval stage. Second, the well-known synergism between metals and warming was manifested not only during the larval stage but also after metamorphosis, yet notably only in low-latitude damselflies. These results highlight that a more complete life-cycle approach that incorporates the possibility of delayed interactions between contaminants and warming in a geographical context is crucial for a more realistic risk assessment in a warming world.

  11. Stability analysis of a general age-dependent vaccination model of a vertically transmitted disease

    International Nuclear Information System (INIS)

    El Doma, M.

    1995-07-01

    An SIR epidemic model of a general age-dependent vaccination of a vertically as well as horizontally transmitted disease is investigated when the population is in steady state and the fertility, mortality and removal rates depends on age. We determine the steady states and examine their stabilities. (author). 24 refs

  12. Photobiomodulation delays the onset of skeletal muscle fatigue in a dose-dependent manner.

    Science.gov (United States)

    Larkin-Kaiser, Kelly A; Borsa, Paul A; Baweja, Harsimran S; Moore, Molly A; Tillman, Mark D; George, Steven Z; Christou, Evangelos A

    2016-09-01

    Photobiomodulation (PBM) therapy has been implicated as an effective ergogenic aid to delay the onset of muscle fatigue. The purpose of this study was to examine the dose-response ergogenic properties of PBM therapy and its ability to prolong time to task failure by enhancing muscle activity and delaying the onset of muscle fatigue using a static positioning task. Nine participants (24.3 ± 4.9 years) received three doses of near-infrared (NIR) light therapy randomly on three separate sessions (sham, 240, and 480 J). For the positioning task, participants held a 30 % one-repetition maximum (1-RM) load using the index finger until volitional fatigue. Surface electromyography (sEMG) of the first dorsal interosseous muscle was recorded for the length of the positioning task. Outcomes included time to task failure (TTF), muscle fatigue, movement accuracy, motor output variability, and muscle activity (sEMG). The 240-J dose significantly extended TTF by 26 % (p = 0.032) compared with the sham dose. TTF for the 240-J dose was strongly associated with a decrease in muscle fatigue (R (2) = 0.54, p = 0.024). Our findings show that a 240-J dose of NIR light therapy is efficacious in delaying the onset and extent of muscle fatigue during submaximal isometric positioning tasks. Our findings suggest that NIR light therapy may be used as an ergogenic aid during functional tasks or post-injury rehabilitation.

  13. Power Optimization of Multimode Mobile Embedded Systems with Workload-Delay Dependency

    Directory of Open Access Journals (Sweden)

    Hoeseok Yang

    2016-01-01

    Full Text Available This paper proposes to take the relationship between delay and workload into account in the power optimization of microprocessors in mobile embedded systems. Since the components outside a device continuously change their values or properties, the workload to be handled by the systems becomes dynamic and variable. This variable workload is formulated as a staircase function of the delay taken at the previous iteration in this paper and applied to the power optimization of DVFS (dynamic voltage-frequency scaling. In doing so, a graph representation of all possible workload/mode changes during the lifetime of a device, Workload Transition Graph (WTG, is proposed. Then, the power optimization problem is transformed into finding a cycle (closed walk in WTG which minimizes the average power consumption over it. Out of the obtained optimal cycle of WTG, one can derive the optimal power management policy of the target device. It is shown that the proposed policy is valid for both continuous and discrete DVFS models. The effectiveness of the proposed power optimization policy is demonstrated with the simulation results of synthetic and real-life examples.

  14. On dependence of stability of lanthanum complexes with aminopolycarboxylic acids on the complex structure

    International Nuclear Information System (INIS)

    Poluehktov, N.S.; Meshkova, S.B.; Danilkovich, M.M.; Topilova, Z.M.

    1985-01-01

    Regularities in changes of stability constants of lanthanum complexes with aminopolycarboxylic acids (APA) versus their structure are studied, The stability of lathanum-APA complexes depends mainly on the number of carboxyl groups in a ligand molecule. At that, the highest stability constant is characteristic of a complex with a ligand, containing 3 nitrogen atoms and 5 carboxyl groups, in the presenoe of which the lanthanum ion coordination sphere gets satupated. The oxyethy group introduction into a ligand molecule also improves the lanthanum complex stability but to a lesser degree than during the introduction of a carboxyl group. The number of nitrogen atoms in a ligand polecule affects insignificantly the complex stability constant value, and the elongation of a chain of CH 2 groups, separating nitrogen atoms, reduces the constant to a -0.6 power

  15. Stability of the Filter Equation for a Time-Dependent Signal on Rd

    International Nuclear Information System (INIS)

    Stannat, Wilhelm

    2005-01-01

    Stability of the pathwise filter equation for a time-dependent signal process induced by a d-dimensional stochastic differential equation and a linear observation is studied, using a variational approach. A lower bound for the rate of stability is identified in terms of the mass-gap of a parabolic ground state transform associated with the generator of the signal process and the square of the observation. The lower bound can be easily calculated a priori and provides hints on how precisely to measure the signal in order to reach a certain rate of stability. Ergodicity of the signal process is not needed

  16. Delay discounting, impulsiveness, and addiction severity in opioid-dependent patients.

    Science.gov (United States)

    Robles, Elias; Huang, B Emma; Simpson, Pippa M; McMillan, Donald E

    2011-12-01

    Individuals who abuse drugs show higher delay discounting (DD) rate and impulsiveness scores compared with controls; however, it is unclear if DD rate covaries with severity of the addiction or if an individual's discounting rate can be changed by effective substance abuse treatment. This study compared methadone maintenance treatment (MMT) patients (n = 30) who had not used illegal drugs for 2 years with drug-using MMT patients (n = 30) and controls (n = 25) in terms of addiction severity, DD rate, and impulsiveness. Methadone patients abstinent from illegal drugs scored significantly lower on a number of addiction severity measures than the drug-using methadone patients. In addition, both groups of MMT patients showed significantly higher rates of DD and impulsiveness than the control group; however, no differences in DD rate or impulsiveness were found between the groups of patients. Results suggest that DD rate and impulsiveness may not covary with indicators of addiction severity in MMT patients. Published by Elsevier Inc.

  17. Size and temperature dependent stability and phase transformation in single-crystal zirconium nanowire

    International Nuclear Information System (INIS)

    Sutrakar, Vijay Kumar; Roy Mahapatra, D.

    2011-01-01

    A novel size dependent FCC (face-centered-cubic) → HCP (hexagonally-closed-pack) phase transformation and stability of an initial FCC zirconium nanowire are studied. FCC zirconium nanowires with cross-sectional dimensions 20 Å, in which surface stresses are not enough to drive the phase transformation, show meta-stability. In such a case, an external kinetic energy in the form of thermal heating is required to overcome the energy barrier and achieve FCC → HCP phase transformation. The FCC-HCP transition pathway is also studied using Nudged Elastic Band (NEB) method, to further confirm the size dependent stability/metastability of Zr nanowires. We also show size dependent critical temperature, which is required for complete phase transformation of a metastable-FCC nanowire.

  18. Delayed self-regulation and time-dependent chemical drive leads to novel states in epigenetic landscapes

    Science.gov (United States)

    Mitra, Mithun K.; Taylor, Paul R.; Hutchison, Chris J.; McLeish, T. C. B.; Chakrabarti, Buddhapriya

    2014-01-01

    The epigenetic pathway of a cell as it differentiates from a stem cell state to a mature lineage-committed one has been historically understood in terms of Waddington's landscape, consisting of hills and valleys. The smooth top and valley-strewn bottom of the hill represent their undifferentiated and differentiated states, respectively. Although mathematical ideas rooted in nonlinear dynamics and bifurcation theory have been used to quantify this picture, the importance of time delays arising from multistep chemical reactions or cellular shape transformations have been ignored so far. We argue that this feature is crucial in understanding cell differentiation and explore the role of time delay in a model of a single-gene regulatory circuit. We show that the interplay of time-dependent drive and delay introduces a new regime where the system shows sustained oscillations between the two admissible steady states. We interpret these results in the light of recent perplexing experiments on inducing the pluripotent state in mouse somatic cells. We also comment on how such an oscillatory state can provide a framework for understanding more general feedback circuits in cell development. PMID:25165605

  19. Scale dependence of the diversity-stability relationship in a temperate grassland.

    Science.gov (United States)

    Zhang, Yunhai; He, Nianpeng; Loreau, Michel; Pan, Qingmin; Han, Xingguo

    2018-05-01

    A positive relationship between biodiversity and ecosystem stability has been reported in many ecosystems; however, it has yet to be determined whether and how spatial scale affects this relationship. Here, for the first time, we assessed the effects of alpha, beta and gamma diversity on ecosystem stability and the scale dependence of the slope of the diversity-stability relationship.By employing a long-term (33 years) dataset from a temperate grassland, northern China, we calculated the all possible spatial scales with the complete combination from the basic 1-m 2 plots.Species richness was positively associated with ecosystem stability through species asynchrony and overyielding at all spatial scales (1, 2, 3, 4 and 5 m 2 ). Both alpha and beta diversity were positively associated with gamma stability.Moreover, the slope of the diversity-area relationship was significantly higher than that of the stability-area relationship, resulting in a decline of the slope of the diversity-stability relationship with increasing area. Synthesis. With the positive species diversity effect on ecosystem stability from small to large spatial scales, our findings demonstrate the need to maintain a high biodiversity and biotic heterogeneity as insurance against the risks incurred by ecosystems in the face of global environmental changes.

  20. Adjustment of Adaptive Gain with Bounded Linear Stability Analysis to Improve Time-Delay Margin for Metrics-Driven Adaptive Control

    Science.gov (United States)

    Bakhtiari-Nejad, Maryam; Nguyen, Nhan T.; Krishnakumar, Kalmanje Srinvas

    2009-01-01

    This paper presents the application of Bounded Linear Stability Analysis (BLSA) method for metrics driven adaptive control. The bounded linear stability analysis method is used for analyzing stability of adaptive control models, without linearizing the adaptive laws. Metrics-driven adaptive control introduces a notion that adaptation should be driven by some stability metrics to achieve robustness. By the application of bounded linear stability analysis method the adaptive gain is adjusted during the adaptation in order to meet certain phase margin requirements. Analysis of metrics-driven adaptive control is evaluated for a linear damaged twin-engine generic transport model of aircraft. The analysis shows that the system with the adjusted adaptive gain becomes more robust to unmodeled dynamics or time delay.

  1. Discrete-time BAM neural networks with variable delays

    Science.gov (United States)

    Liu, Xin-Ge; Tang, Mei-Lan; Martin, Ralph; Liu, Xin-Bi

    2007-07-01

    This Letter deals with the global exponential stability of discrete-time bidirectional associative memory (BAM) neural networks with variable delays. Using a Lyapunov functional, and linear matrix inequality techniques (LMI), we derive a new delay-dependent exponential stability criterion for BAM neural networks with variable delays. As this criterion has no extra constraints on the variable delay functions, it can be applied to quite general BAM neural networks with a broad range of time delay functions. It is also easy to use in practice. An example is provided to illustrate the theoretical development.

  2. Discrete-time BAM neural networks with variable delays

    International Nuclear Information System (INIS)

    Liu Xinge; Tang Meilan; Martin, Ralph; Liu Xinbi

    2007-01-01

    This Letter deals with the global exponential stability of discrete-time bidirectional associative memory (BAM) neural networks with variable delays. Using a Lyapunov functional, and linear matrix inequality techniques (LMI), we derive a new delay-dependent exponential stability criterion for BAM neural networks with variable delays. As this criterion has no extra constraints on the variable delay functions, it can be applied to quite general BAM neural networks with a broad range of time delay functions. It is also easy to use in practice. An example is provided to illustrate the theoretical development

  3. Aldosterone downregulates delayed rectifier potassium currents through an angiotensin type 1 receptor-dependent mechanism.

    Science.gov (United States)

    Lv, Yankun; Wang, Yanjun; Zhu, Xiaoran; Zhang, Hua

    2018-01-01

    We have previously shown that aldosterone downregulates delayed rectifier potassium currents (I Ks ) via activation of the mineralocorticoid receptor (MR) in adult guinea pig cardiomyocytes. Here, we investigate whether angiotensin II/angiotensin type 1 receptor (AngII/AT1R) and intracellular calcium also play a role in these effects. Ventricular cardiomyocytes were isolated from adult guinea pigs and incubated with aldosterone (1 μmol·L -1 ) either alone or in combination with enalapril (1 μmol·L -1 ), losartan (1 μmol·L -1 ), nimodipine (1 μmol·L -1 ), or BAPTA-AM (2.5 μmol·L -1 ) for 24 h. We used the conventional whole cell patch-clamp technique to record the I Ks component. In addition, we evaluated expression of the I Ks subunits KCNQ1 and KCNE1 using Western blotting. Our results showed that both enalapril and losartan, but not nimodipine or BAPTA-AM, completely reversed the aldosterone-induced inhibition of I Ks and its effects on KCNQ1/KCNE1 protein levels. Furthermore, we found that AngII/AT1R mediates the inhibitory effects of aldosterone on I Ks . Finally, the downregulation of I Ks induced by aldosterone did not occur secondarily to a change in intracellular calcium concentrations. Taken together, our findings demonstrate that crosstalk between MR and AT1R underlies the effects of aldosterone, and provide new insights into the mechanism underlying potassium channels.

  4. Quantitative analysis of the Ca2+ -dependent regulation of delayed rectifier K+ current IKs in rabbit ventricular myocytes.

    Science.gov (United States)

    Bartos, Daniel C; Morotti, Stefano; Ginsburg, Kenneth S; Grandi, Eleonora; Bers, Donald M

    2017-04-01

    [Ca 2+ ] i enhanced rabbit ventricular slowly activating delayed rectifier K + current (I Ks ) by negatively shifting the voltage dependence of activation and slowing deactivation, similar to perfusion of isoproterenol. Rabbit ventricular rapidly activating delayed rectifier K + current (I Kr ) amplitude and voltage dependence were unaffected by high [Ca 2+ ] i . When measuring or simulating I Ks during an action potential, I Ks was not different during a physiological Ca 2+ transient or when [Ca 2+ ] i was buffered to 500 nm. The slowly activating delayed rectifier K + current (I Ks ) contributes to repolarization of the cardiac action potential (AP). Intracellular Ca 2+ ([Ca 2+ ] i ) and β-adrenergic receptor (β-AR) stimulation modulate I Ks amplitude and kinetics, but details of these important I Ks regulators and their interaction are limited. We assessed the [Ca 2+ ] i dependence of I Ks in steady-state conditions and with dynamically changing membrane potential and [Ca 2+ ] i during an AP. I Ks was recorded from freshly isolated rabbit ventricular myocytes using whole-cell patch clamp. With intracellular pipette solutions that controlled free [Ca 2+ ] i , we found that raising [Ca 2+ ] i from 100 to 600 nm produced similar increases in I Ks as did β-AR activation, and the effects appeared additive. Both β-AR activation and high [Ca 2+ ] i increased maximally activated tail I Ks , negatively shifted the voltage dependence of activation, and slowed deactivation kinetics. These data informed changes in our well-established mathematical model of the rabbit myocyte. In both AP-clamp experiments and simulations, I Ks recorded during a normal physiological Ca 2+ transient was similar to I Ks measured with [Ca 2+ ] i clamped at 500-600 nm. Thus, our study provides novel quantitative data as to how physiological [Ca 2+ ] i regulates I Ks amplitude and kinetics during the normal rabbit AP. Our results suggest that micromolar [Ca 2+ ] i , in the submembrane or

  5. Intense field stabilization in circular polarization: Three-dimensional time-dependent dynamics

    International Nuclear Information System (INIS)

    Choi, Dae-Il; Chism, Will

    2002-01-01

    We investigate the stabilization of hydrogen atoms in a circularly polarized laser field. We use a three-dimensional, time-dependent approach to study the quantum dynamics of hydrogen atoms subject to high-intensity, short-wavelength, laser pulses. We find an enhanced survival probability as the field is increased under fixed envelope conditions. We also confirm wave packet behaviors previously seen in two-dimensional time-dependent computations

  6. 一类含非线性扰动的区间变时滞系统鲁棒稳定性判据%Robust Stability Criteria for Systems with Interval Time-varying Delay and Nonlinear Perturbations

    Institute of Scientific and Technical Information of China (English)

    惠俊军; 张合新; 周鑫; 孟飞; 张金生

    2014-01-01

    Interval time delay is an important delay type in practical systems. In such sys-tems, the delay may vary in a range for which the lower bound is not restricted to being zero. In this paper, we consider the robust stability for a class of linear systems with interval time-varying delay and nonlinear perturbations. Based on the delay decomposition approach, both the lower and upper bounds of the interval time-varying delay are proposed. By applying a new Lyapunov-Krasovskii (L-K) functional, and free-weighing matrix approach, a less conservative delay-dependent stability criteria are obtained, which are established in the forms of linear matrix inequalities (LMIs). The main advantage of the method is that more information of the interval delay is employed, and hence yields less conservative. Finally, numerical examples indicate the effectiveness and superiority of the proposed method.%区间时滞是在实际应用当中一类重要的时滞类型。在这类系统当中,时滞往往处于一个变化的区间之内,而时滞的下界不一定为零。本文讨论一类含非线性扰动的区间变时滞系统的稳定性问题。基于时滞分解法,把时滞下界分成两个相等的子区间,通过构造包含时滞区间下界和上界新Lyapunov-Krasovskii (L-K)泛函,结合改进的自由权矩阵技术,建立了线性矩阵不等式(LMI)形式的时滞相关稳定性判据。该方法充分利用了系统的时滞信息,因而具有更低的保守性。数值算例说明了该方法的有效性和优越性。

  7. On geometry-dependent vortex stability and topological spin excitations on curved surfaces with cylindrical symmetry

    International Nuclear Information System (INIS)

    Carvalho-Santos, V.L.; Apolonio, F.A.; Oliveira-Neto, N.M.

    2013-01-01

    We study the Heisenberg model on cylindrically symmetric curved surfaces. Two kinds of excitations are considered. The first is given by the isotropic regime, yielding the sine-Gordon equation and π solitons are predicted. The second one is given by the XY model, leading to a vortex turning around the surface. Helical states are also considered, however, topological arguments cannot be used to ensure its stability. The energy and the anisotropy parameter which stabilizes the vortex state are explicitly calculated for two surfaces: catenoid and hyperboloid. The results show that the anisotropy and the vortex energy depends on the underlying geometry. -- Highlights: •Applying the anisotropic Heisenberg model on curved surfaces. •Appearance of topological solitons on curved surfaces with cylindrical symmetry. •Calculus of the vortex energy, which depends on curvature. •Discussion on features of non-topological helical-like states. •Vortex stability ensured by the anisotropy parameter value

  8. Scale dependence of the diversity–stability relationship in a temperate grassland

    Science.gov (United States)

    Zhang, Yunhai; He, Nianpeng; Loreau, Michel; Pan, Qingmin; Han, Xingguo

    2018-01-01

    A positive relationship between biodiversity and ecosystem stability has been reported in many ecosystems; however, it has yet to be determined whether and how spatial scale affects this relationship. Here, for the first time, we assessed the effects of alpha, beta and gamma diversity on ecosystem stability and the scale dependence of the slope of the diversity–stability relationship.By employing a long-term (33 years) dataset from a temperate grassland, northern China, we calculated the all possible spatial scales with the complete combination from the basic 1-m2 plots.Species richness was positively associated with ecosystem stability through species asynchrony and overyielding at all spatial scales (1, 2, 3, 4 and 5 m2). Both alpha and beta diversity were positively associated with gamma stability.Moreover, the slope of the diversity–area relationship was significantly higher than that of the stability–area relationship, resulting in a decline of the slope of the diversity–stability relationship with increasing area.Synthesis. With the positive species diversity effect on ecosystem stability from small to large spatial scales, our findings demonstrate the need to maintain a high biodiversity and biotic heterogeneity as insurance against the risks incurred by ecosystems in the face of global environmental changes. PMID:29725139

  9. The Lyapunov-Krasovskii theorem and a sufficient criterion for local stability of isochronal synchronization in networks of delay-coupled oscillators

    Science.gov (United States)

    Grzybowski, J. M. V.; Macau, E. E. N.; Yoneyama, T.

    2017-05-01

    This paper presents a self-contained framework for the stability assessment of isochronal synchronization in networks of chaotic and limit-cycle oscillators. The results were based on the Lyapunov-Krasovskii theorem and they establish a sufficient condition for local synchronization stability of as a function of the system and network parameters. With this in mind, a network of mutually delay-coupled oscillators subject to direct self-coupling is considered and then the resulting error equations are block-diagonalized for the purpose of studying their stability. These error equations are evaluated by means of analytical stability results derived from the Lyapunov-Krasovskii theorem. The proposed approach is shown to be a feasible option for the investigation of local stability of isochronal synchronization for a variety of oscillators coupled through linear functions of the state variables under a given undirected graph structure. This ultimately permits the systematic identification of stability regions within the high-dimensionality of the network parameter space. Examples of applications of the results to a number of networks of delay-coupled chaotic and limit-cycle oscillators are provided, such as Lorenz, Rössler, Cubic Chua's circuit, Van der Pol oscillator and the Hindmarsh-Rose neuron.

  10. Lyapunov functions and global stability for SIR and SEIR models with age-dependent susceptibility

    KAUST Repository

    Korobeinikov, Andrei; Melnik, Andrey V.

    2013-01-01

    We consider global asymptotic properties for the SIR and SEIR age structured models for infectious diseases where the susceptibility depends on the age. Using the direct Lyapunov method with Volterra type Lyapunov functions, we establish conditions for the global stability of a unique endemic steady state and the infection-free steady state.

  11. Stability properties of a heat equation with state-dependent parameters and asymmetric boundary conditions

    DEFF Research Database (Denmark)

    Backi, Christoph Josef; Bendtsen, Jan Dimon; Leth, John

    2015-01-01

    In this work the stability properties of a partial differential equation (PDE) with state-dependent parameters and asymmetric boundary conditions are investigated. The PDE describes the temperature distribution inside foodstuff, but can also hold for other applications and phenomena. We show...

  12. Delayed entry into first marriage and marital stability: Further evidence on the Becker-Landes-Michael hypothesis

    Directory of Open Access Journals (Sweden)

    Evelyn Lehrer

    2013-09-01

    Full Text Available BACKGROUND In their pioneering research, Becker, Landes, and Michael (1977 found that beyond age 30 there is a positive relationship between women's age at first marriage and marital instability. They interpreted this finding as a "poor-match effect" emerging when the biological clock begins to tick. OBJECTIVE Our objective was to ascertain with more recent data whether or not there is evidence of a poor match effect and if so, whether it is associated with higher marital instability. METHODS We used data on non-Hispanic white women from the 2006-2010 National Surveys of Family Growth (NSFG (N = 3,184. RESULTS We found evidence of the existence of a poor-match effect: women who delay marriage disproportionately make unconventional matches, which are generally associated with high marital instability. We also found, however, that their unions are very solid. Both of these results were consistent with earlier findings for the 1995 and 2002-2003 NSFG cycles. In attempting to explain this puzzle, we proposed and tested competing hypotheses. We found that the destabilizing effects associated with indicators of unconventional matches are also present in marriages contracted late, but are dwarfed by the stabilizing influences associated with higher levels of education and older ages. CONCLUSIONS This paper contributes to our understanding of the determinants of marital instability and the poor match effect by providing a new interpretation for the puzzle described above. COMMENTS Our findings have implications for analyses of changes over time in the extent of positive assortative mating in the marriage market, and for the extensive literature showing that heterogamy in traits that are complementary in the context of marriage is destabilizing -- heterogamous marriages contracted at a late age are likely to be stable.

  13. Exponential convergence rate estimation for uncertain delayed neural networks of neutral type

    International Nuclear Information System (INIS)

    Lien, C.-H.; Yu, K.-W.; Lin, Y.-F.; Chung, Y.-J.; Chung, L.-Y.

    2009-01-01

    The global exponential stability for a class of uncertain delayed neural networks (DNNs) of neutral type is investigated in this paper. Delay-dependent and delay-independent criteria are proposed to guarantee the robust stability of DNNs via LMI and Razumikhin-like approaches. For a given delay, the maximal allowable exponential convergence rate will be estimated. Some numerical examples are given to illustrate the effectiveness of our results. The simulation results reveal significant improvement over the recent results.

  14. State-dependent sensorimotor processing: gaze and posture stability during simulated flight in birds.

    Science.gov (United States)

    McArthur, Kimberly L; Dickman, J David

    2011-04-01

    Vestibular responses play an important role in maintaining gaze and posture stability during rotational motion. Previous studies suggest that these responses are state dependent, their expression varying with the environmental and locomotor conditions of the animal. In this study, we simulated an ethologically relevant state in the laboratory to study state-dependent vestibular responses in birds. We used frontal airflow to simulate gliding flight and measured pigeons' eye, head, and tail responses to rotational motion in darkness, under both head-fixed and head-free conditions. We show that both eye and head response gains are significantly higher during flight, thus enhancing gaze and head-in-space stability. We also characterize state-specific tail responses to pitch and roll rotation that would help to maintain body-in-space orientation during flight. These results demonstrate that vestibular sensorimotor processing is not fixed but depends instead on the animal's behavioral state.

  15. BMAL1-dependent regulation of the mTOR signaling pathway delays aging.

    Science.gov (United States)

    Khapre, Rohini V; Kondratova, Anna A; Patel, Sonal; Dubrovsky, Yuliya; Wrobel, Michelle; Antoch, Marina P; Kondratov, Roman V

    2014-01-01

    The circadian clock, an internal time-keeping system, has been linked with control of aging, but molecular mechanisms of regulation are not known. BMAL1 is a transcriptional factor and core component of the circadian clock; BMAL1 deficiency is associated with premature aging and reduced lifespan. Here we report that activity of mammalian Target of Rapamycin Complex 1 (mTORC1) is increased upon BMAL1 deficiency both in vivo and in cell culture. Increased mTOR signaling is associated with accelerated aging; in accordance with that, treatment with the mTORC1 inhibitor rapamycin increased lifespan of Bmal1-/- mice by 50%. Our data suggest that BMAL1 is a negative regulator of mTORC1 signaling. We propose that the circadian clock controls the activity of the mTOR pathway through BMAL1-dependent mechanisms and this regulation is important for control of aging and metabolism.

  16. Beam stability in synchrotrons with digital transverse feedback systems in dependence on beam tunes

    International Nuclear Information System (INIS)

    Zhabitskij, V.M.

    2011-01-01

    The beam stability problem in synchrotrons with a digital transverse feedback system (TFS) is studied. The TFS damper kicker (DK) corrects the transverse momentum of a bunch in proportion to its displacement from the closed orbit measured at the location of the beam position monitor (BPM). It is shown that the area and configuration of the beam stability separatrix depend on the beam tune, the feedback gain, the phase balance between the phase advance from BPM to DK and the phase response of the feedback chain at the betatron frequency

  17. B16 melanoma tumor growth is delayed in mice in an age-dependent manner

    Directory of Open Access Journals (Sweden)

    Christina Pettan-Brewer

    2012-08-01

    Full Text Available A major risk factor for cancer is increasing age, which suggests that syngeneic tumor implants in old mice would grow more rapidly. However, various reports have suggested that old mice are not as permissive to implanted tumor cells as young mice. In order to determine and characterize the age-related response to B16 melanoma, we implanted 5×105 tumor cells into 8, 16, 24, and 32-month-old male C57BL/6 (B6 and C57BL/6×BALB/c F1 (CB6 F1 mice subcutaneously in the inguinal and axillary spaces, or intradermally in the lateral flank. Results showed decreased tumor volume with increasing age, which varied according to mouse genetic background and the implanted site. The B6 strain showed robust tumor growth at 8 months of age at the inguinal implantation site, with an average tumor volume of 1341.25 mm3. The 16, 24, and 32-month age groups showed a decrease in tumor growth with tumor volumes of 563.69, 481.02, and 264.55 mm3, respectively (p≤0.001. The axillary implantation site was less permissive in 8-month-old B6 mice with an average tumor volume of 761.52 mm3. The 24- and 32-month age groups showed a similar decrease in tumor growth with tumor volumes of 440 and 178.19 mm3, respectively (p≤0.01. The CB6F1 strain was not as tumor permissive at 8 months of age as B6 mice with average tumor volumes of 446.96 and 426.91 mm3 for the inguinal and axillary sites, respectively. There was a decrease in tumor growth at 24 months of age at both inguinal and axillary sites with an average tumor volume of 271.02 and 249.12 mm3, respectively (p≤0.05. The strain dependence was not apparent in 8-month-old mice injected intradermally with B16 melanoma cells, with average tumor volumes of 736.82 and 842.85 mm3 for B6 and CB6 F1, respectively. However, a strain difference was seen in 32-month-old B6 mice with an average decrease in tumor volume of 250.83 mm3 (p≤0.01. In contrast, tumor growth significantly decreased earlier in CB6 F1 mice with average

  18. Delay-Dependent Finite-Time H∞ Controller Design for a Kind of Nonlinear Descriptor Systems via a T-S Fuzzy Model

    Directory of Open Access Journals (Sweden)

    Baoyan Zhu

    2015-01-01

    Full Text Available Delay-dependent finite-time H∞ controller design problems are investigated for a kind of nonlinear descriptor system via a T-S fuzzy model in this paper. The solvable conditions of finite-time H∞ controller are given to guarantee that the loop-closed system is impulse-free and finite-time bounded and holds the H∞ performance to a prescribed disturbance attenuation level γ. The method given is the ability to eliminate the impulsive behavior caused by descriptor systems in a finite-time interval, which confirms the existence and uniqueness of solutions in the interval. By constructing a nonsingular matrix, we overcome the difficulty that results in an infeasible linear matrix inequality (LMI. Using the FEASP solver and GEVP solver of the LMI toolbox, we perform simulations to validate the proposed methods for a nonlinear descriptor system via the T-S fuzzy model, which shows the application of the T-S fuzzy method in studying the finite-time control problem of a nonlinear system. Meanwhile the method was also applied to the biological economy system to eliminate impulsive behavior at the bifurcation value, stabilize the loop-closed system in a finite-time interval, and achieve a H∞ performance level.

  19. Energy dependence of average half-life of delayed neutron precursors in fast neutron induced fission of 235U and 236U

    International Nuclear Information System (INIS)

    Isaev, S.G.; Piksaikin, L.E.; Kazakov, L.E.; Tarasko, M.Z.

    2000-01-01

    The measurements of relative abundances and periods of delayed neutrons from fast neutron induced fission of 235 U and 236 U have been made at the electrostatic accelerator CG-2.5 at IPPE. The preliminary results were obtained and discussed in the frame of the systematics of the average half-life of delayed neutron precursors. It was shown that the average half-life value in both reactions depends on the energy of primary neutrons [ru

  20. Nuclei far from the beta stability line. High-energy beta decay and delayed-particle emission

    International Nuclear Information System (INIS)

    Hansen, R.G.; Hornshj, P.

    1976-01-01

    Progress in on-line mass separation together with improved proton accelerators now permit the production of secondary ion-beams of the order of 10 11 atoms per second. Applications to the study of delayed-proton and delayed-alpha emission are discussed. These effects have been used for the estimation of alpha-emission strength functions at 4-6 MeV excitation energy, and for the determination of level densities through fluctuation analysis

  1. Delay-dependent working memory impairment in young-adult and aged 5-HT1BKO mice as assessed in a radial-arm water maze.

    Science.gov (United States)

    Wolff, Mathieu; Benhassine, Narimane; Costet, Pierre; Hen, Rene; Segu, Louis; Buhot, Marie-Christine

    2003-01-01

    Serotonin (5-HT) plays a modulatory role in mnemonic functions, especially by interacting with the cholinergic system. The 5-HT1B receptor is a key target of this interaction. The 5-HT1B receptor knockout mice were found previously to exhibit a facilitation in hippocampal-dependent spatial reference memory learning. In the present study, we submitted mice to a delayed spatial working memory task, allowing the introduction of various delays between an exposure trial and a test trial. The 5-HT1BKO and wild-type mice learned the task in a radial-arm water maze (returning to the most recent presented arm containing the escape platform), and exhibited a high level of performance at delays of 0 and 5 min. However, at the delay of 60 min, only 5-HT1BKO mice exhibited an impairment. At a delay of 90 min, all mice were impaired. Treatment by scopolamine (0.8 mg/kg) induced the same pattern of performance in wild type as did the mutation for short (5 min, no impairment) and long (60 min, impairment) delays. The 22-month-old wild-type and knockout mice exhibited an impairment at short delays (5 and 15 min). The effect of the mutation affected both young-adult and aged mice at delays of 15, 30, and 60 min. Neurobiological data show that stimulation of the 5-HT1B receptor inhibits the release of acetylcholine in the hippocampus, but stimulates this in the frontal cortex. This dual function might, at least in part, explain the opposite effect of the mutation on reference memory (facilitation) and delay-dependent working memory (impairment). These results support the idea that cholinergic-serotonergic interactions play an important role in memory processes.

  2. Reaction rate and composition dependence of the stability of thermonuclear burning on accreting neutron stars

    International Nuclear Information System (INIS)

    Keek, L.; Cyburt, R. H.; Heger, A.

    2014-01-01

    The stability of thermonuclear burning of hydrogen and helium accreted onto neutron stars is strongly dependent on the mass accretion rate. The burning behavior is observed to change from Type I X-ray bursts to stable burning, with oscillatory burning occurring at the transition. Simulations predict the transition at a 10 times higher mass accretion rate than observed. Using numerical models we investigate how the transition depends on the hydrogen, helium, and CNO mass fractions of the accreted material, as well as on the nuclear reaction rates of 3α and the hot-CNO breakout reactions 15 O(α, γ) 19 Ne and 18 Ne(α, p) 21 Na. For a lower hydrogen content the transition is at higher accretion rates. Furthermore, most experimentally allowed reaction rate variations change the transition accretion rate by at most 10%. A factor 10 decrease of the 15 O(α, γ) 19 Ne rate, however, produces an increase of the transition accretion rate of 35%. None of our models reproduce the transition at the observed rate, and depending on the true 15 O(α, γ) 19 Ne reaction rate, the actual discrepancy may be substantially larger. We find that the width of the interval of accretion rates with marginally stable burning depends strongly on both composition and reaction rates. Furthermore, close to the stability transition, our models predict that X-ray bursts have extended tails where freshly accreted fuel prolongs nuclear burning.

  3. Decentralized H∞ Control of Interconnected Systems with Time-varying Delays

    Directory of Open Access Journals (Sweden)

    Amal Zouhri

    2017-01-01

    Full Text Available This paper focuses on the problem of delay dependent stability/stabilization of interconnected systems with time-varying delays. The approach is based on a new Lyapunov-Krasovskii functional. A decentralized delay-dependent stability analysis is performed to characterize linear matrix inequalities (LMIs based on the conditions under which every local subsystem of the linear interconnected delay system is asymptotically stable. Then we design a decentralized state-feedback stabilization scheme such that the family of closedloop feedback subsystems enjoys the delay-dependent asymptotic stability for each subsystem. The decentralized feedback gains are determined by convex optimization over LMIs. All the developed results are tested on a representative example and compared with some recent previous ones.

  4. Establishing nursery estuary otolith geochemical tags for Sea Bass (Dicentrarchus labrax): Is temporal stability estuary dependent?

    Science.gov (United States)

    Ryan, Diarmuid; Wögerbauer, Ciara; Roche, William

    2016-12-01

    The ability to determine connectivity between juveniles in nursery estuaries and adult populations is an important tool for fisheries management. Otoliths of juvenile fish contain geochemical tags, which reflect the variation in estuarine elemental chemistry, and allow discrimination of their natal and/or nursery estuaries. These tags can be used to investigate connectivity patterns between juveniles and adults. However, inter-annual variability of geochemical tags may limit the accuracy of nursery origin determinations. Otolith elemental composition was used to assign a single cohort of 0-group sea bass Dicentrarchus labrax to their nursery estuary thus establishing an initial baseline for stocks in waters around Ireland. Using a standard LDFA model, high classification accuracies to nursery sites (80-88%) were obtained. Temporal stability of otolith geochemical tags was also investigated to assess if annual sampling is required for connectivity studies. Geochemical tag stability was found to be strongly estuary dependent.

  5. Deficiency of the Cyclin-Dependent Kinase Inhibitor, CDKN1B, Results in Overgrowth and Neurodevelopmental Delay

    Science.gov (United States)

    Grey, William; Izatt, Louise; Sahraoui, Wafa; Ng, Yiu-Ming; Ogilvie, Caroline; Hulse, Anthony; Tse, Eric; Holic, Roman; Yu, Veronica

    2013-01-01

    Germline mutations in the cyclin-dependent kinase inhibitor, CDKN1B, have been described in patients with multiple endocrine neoplasia (MEN), a cancer predisposition syndrome with adult onset neoplasia and no additional phenotypes. Here, we describe the first human case of CDKN1B deficiency, which recapitulates features of the murine CDKN1B knockout mouse model, including gigantism and neurodevelopmental defects. Decreased mRNA and protein expression of CDKN1B were confirmed in the proband's peripheral blood, which is not seen in MEN syndrome patients. We ascribed the decreased protein level to a maternally derived deletion on chromosome 12p13 encompassing the CDKN1B locus (which reduced mRNA expression) and a de novo allelic variant (c.-73G>A) in the CDKN1B promoter (which reduced protein translation). We propose a recessive model where decreased dosage of CDKN1B during development in humans results in a neuronal phenotype akin to that described in mice, placing CDKN1B as a candidate gene involved in developmental delay. PMID:23505216

  6. The novel dehydroepiandrosterone (DHEA) derivative BNN27 counteracts delay-dependent and scopolamine-induced recognition memory deficits in rats.

    Science.gov (United States)

    Pitsikas, Nikolaos; Gravanis, Achille

    2017-04-01

    Experimental evidence indicates that the neurosteroids dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulphate (DHEAS) are involved in cognition. BNN27 is a novel 17C spiroepoxy-DHEA derivative, which devoid of steroidogenic activity. The neuroprotective effects of BNN27 have been recently reported. The present study was designed to investigate the effects of BNN27 on recognition memory in rats. For this purpose, the novel object task (NOT), a procedure assessing non-spatial recognition memory and the novel location task (NLT), a procedure evaluating spatial recognition memory were used. Intraperitoneal (i.p.) administration of BNN27 (3 and 10mg/kg) antagonized delay-dependent deficits in the NOT in the normal rat, suggesting that this DHEA derivative affected acquisition, storage and retrieval of information. In addition, BNN27 (3 and 10mg/kg, i.p.) counteracted the scopolamine [0.2mg/kg, subcutaneously (s.c.)]-induced non-spatial and spatial recognition memory deficits. These findings suggest that BNN27 may modulate different aspects of recognition memory, potentially interacting with the cholinergic system, relevant to cognition. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. TIMEX, 1-D Time-Dependent Multigroup Transport Theory with Delayed Neutron, Planar Cylindrical and Spherical Geometry

    International Nuclear Information System (INIS)

    Hill, T. R.; Reed, W. H.

    1980-01-01

    1 - Description of problem or function: TIMEX solves the time- dependent, one-dimensional multigroup transport equation with delayed neutrons in plane, cylindrical, spherical, and two-angle plane geometries. Both regular and adjoint, inhomogeneous and homogeneous problems subject to vacuum, reflective, periodic, white, albedo or inhomogeneous boundary flux conditions are solved. General anisotropic scattering is allowed and anisotropic inhomogeneous sources are permitted. 2 - Method of solution: The discrete ordinates approximation for the angular variable is used with the diamond (central) difference approximation for the angular extrapolation in curved geometries. A linear discontinuous finite element representation for the angular flux in each spatial mesh cell is used. Negative fluxes are eliminated by a local set-to-zero and correct algorithm. The time variable is differenced by an explicit technique that is unconditionally stable so that arbitrarily large time-steps can be taken. Two acceleration methods, exponential extrapolation and re-balance, are utilized to improve the accuracy of the time differencing scheme. 3 - Restrictions on the complexity of the problem: Variable dimensioning is used so that any combination of problem parameters leading to a container array less than MAXCOR can be accommodated. In addition, the CDC version permits the use of extended core storage less than MAXECS

  8. Forskolin suppresses delayed-rectifier K+ currents and enhances spike frequency-dependent adaptation of sympathetic neurons.

    Directory of Open Access Journals (Sweden)

    Luis I Angel-Chavez

    Full Text Available In signal transduction research natural or synthetic molecules are commonly used to target a great variety of signaling proteins. For instance, forskolin, a diterpene activator of adenylate cyclase, has been widely used in cellular preparations to increase the intracellular cAMP level. However, it has been shown that forskolin directly inhibits some cloned K+ channels, which in excitable cells set up the resting membrane potential, the shape of action potential and regulate repetitive firing. Despite the growing evidence indicating that K+ channels are blocked by forskolin, there are no studies yet assessing the impact of this mechanism of action on neuron excitability and firing patterns. In sympathetic neurons, we find that forskolin and its derivative 1,9-Dideoxyforskolin, reversibly suppress the delayed rectifier K+ current (IKV. Besides, forskolin reduced the spike afterhyperpolarization and enhanced the spike frequency-dependent adaptation. Given that IKV is mostly generated by Kv2.1 channels, HEK-293 cells were transfected with cDNA encoding for the Kv2.1 α subunit, to characterize the mechanism of forskolin action. Both drugs reversible suppressed the Kv2.1-mediated K+ currents. Forskolin inhibited Kv2.1 currents and IKV with an IC50 of ~32 μM and ~24 µM, respectively. Besides, the drug induced an apparent current inactivation and slowed-down current deactivation. We suggest that forskolin reduces the excitability of sympathetic neurons by enhancing the spike frequency-dependent adaptation, partially through a direct block of their native Kv2.1 channels.

  9. Forskolin suppresses delayed-rectifier K+ currents and enhances spike frequency-dependent adaptation of sympathetic neurons.

    Science.gov (United States)

    Angel-Chavez, Luis I; Acosta-Gómez, Eduardo I; Morales-Avalos, Mario; Castro, Elena; Cruzblanca, Humberto

    2015-01-01

    In signal transduction research natural or synthetic molecules are commonly used to target a great variety of signaling proteins. For instance, forskolin, a diterpene activator of adenylate cyclase, has been widely used in cellular preparations to increase the intracellular cAMP level. However, it has been shown that forskolin directly inhibits some cloned K+ channels, which in excitable cells set up the resting membrane potential, the shape of action potential and regulate repetitive firing. Despite the growing evidence indicating that K+ channels are blocked by forskolin, there are no studies yet assessing the impact of this mechanism of action on neuron excitability and firing patterns. In sympathetic neurons, we find that forskolin and its derivative 1,9-Dideoxyforskolin, reversibly suppress the delayed rectifier K+ current (IKV). Besides, forskolin reduced the spike afterhyperpolarization and enhanced the spike frequency-dependent adaptation. Given that IKV is mostly generated by Kv2.1 channels, HEK-293 cells were transfected with cDNA encoding for the Kv2.1 α subunit, to characterize the mechanism of forskolin action. Both drugs reversible suppressed the Kv2.1-mediated K+ currents. Forskolin inhibited Kv2.1 currents and IKV with an IC50 of ~32 μM and ~24 µM, respectively. Besides, the drug induced an apparent current inactivation and slowed-down current deactivation. We suggest that forskolin reduces the excitability of sympathetic neurons by enhancing the spike frequency-dependent adaptation, partially through a direct block of their native Kv2.1 channels.

  10. TIMEX: a time-dependent explicit discrete ordinates program for the solution of multigroup transport equations with delayed neutrons

    International Nuclear Information System (INIS)

    Hill, T.R.; Reed, W.H.

    1976-01-01

    TIMEX solves the time-dependent, one-dimensional multigroup transport equation with delayed neutrons in plane, cylindrical, spherical, and two-angle plane geometries. Both regular and adjoint, inhomogeneous and homogeneous problems subject to vacuum, reflective, periodic, white, albedo or inhomogeneous boundary flux conditions are solved. General anisotropic scattering is allowed and anisotropic inhomogeneous sources are permitted. The discrete ordinates approximation for the angular variable is used with the diamond (central) difference approximation for the angular extrapolation in curved geometries. A linear discontinuous finite element representation for the angular flux in each spatial mesh cell is used. The time variable is differenced by an explicit technique that is unconditionally stable so that arbitrarily large time steps can be taken. Because no iteration is performed the method is exceptionally fast in terms of computing time per time step. Two acceleration methods, exponential extrapolation and rebalance, are utilized to improve the accuracy of the time differencing scheme. Variable dimensioning is used so that any combination of problem parameters leading to a container array less than MAXCOR can be accommodated. The running time for TIMEX is highly problem-dependent, but varies almost linearly with the total number of unknowns and time steps. Provision is made for creation of standard interface output files for angular fluxes and angle-integrated fluxes. Five interface units (use of interface units is optional), five output units, and two system input/output units are required. A large bulk memory is desirable, but may be replaced by disk, drum, or tape storage. 13 tables, 9 figures

  11. The delay in the development of experimental colitis from isomaltosyloligosaccharides in rats is dependent on the degree of polymerization.

    Directory of Open Access Journals (Sweden)

    Hitoshi Iwaya

    Full Text Available Isomaltosyloligosaccharides (IMO and dextran (Dex are hardly digestible in the small intestine and thus influence the luminal environment and affect the maintenance of health. There is wide variation in the degree of polymerization (DP in Dex and IMO (short-sized IMO, S-IMO; long-sized IMO, L-IMO, and the physiological influence of these compounds may be dependent on their DP.Five-week-old male Wistar rats were given a semi-purified diet with or without 30 g/kg diet of the S-IMO (DP = 3.3, L-IMO (DP = 8.4, or Dex (DP = 1230 for two weeks. Dextran sulfate sodium (DSS was administered to the rats for one week to induce experimental colitis. We evaluated the clinical symptoms during the DSS treatment period by scoring the body weight loss, stool consistency, and rectal bleeding. The development of colitis induced by DSS was delayed in the rats fed S-IMO and Dex diets. The DSS treatment promoted an accumulation of neutrophils in the colonic mucosa in the rats fed the control, S-IMO, and L-IMO diets, as assessed by a measurement of myeloperoxidase (MPO activity. In contrast, no increase in MPO activity was observed in the Dex-diet-fed rats even with DSS treatment. Immune cell populations in peripheral blood were also modified by the DP of ingested saccharides. Dietary S-IMO increased the concentration of n-butyric acid in the cecal contents and the levels of glucagon-like peptide-2 in the colonic mucosa.Our study provided evidence that the physiological effects of α-glucosaccharides on colitis depend on their DP, linkage type, and digestibility.

  12. Synchronization of delay-coupled nonlinear oscillators : an approach based on the stability analysis of synchronized equilibria

    NARCIS (Netherlands)

    Michiels, W.; Nijmeijer, H.

    2009-01-01

    We consider the synchronization problem of an arbitrary number of coupled nonlinear oscillators with delays in the interconnections. The network topology is described by a directed graph. Unlike the conventional approach of deriving directly sufficient synchronization conditions, the approach of the

  13. The exploration of stability of two-dimensional nanocrystalline metallic composites depending on temperature

    International Nuclear Information System (INIS)

    Poletayev, G.M.; Starostenkov, M.D.; Popova, G.V.; Skakov, M.K.

    2004-01-01

    Full text: In nanocrystalline compositional materials the borders of phase separation play special role. The detection of stability of the borders of phase separation depending on external conditions, such pressure, temperature of alloying is the important task in the case of nanocrystalline materials. In the current paper the stability of two-dimensional nanocrystal, composite on the basis of Ni-Al system, depending on the structure of compositional material and vacancy availability is studied. Atomic packing in two-dimensional crystal corresponds to the plane (111) of fee crystal structure, or the plane (111) of superstructure L1 2 of intermetallide system Ni-Al. The interaction between atoms is set by pair potential functions of Morse, that consider interatomic bonding in the first six coordinate spheres. The calculated block was expressed in atomic packing in the cell 40x40. Beyond the bounds of the calculated block crystal is repeated with the help of periodical border conditions. Computer modeling is performed according to the method of molecular dynamics, when speeds of atom dislocations depending on temperature are set in accidental way, according to Boltzmann allocation. Two-dimensional material was represented by different packs of phases, clean Ni, Al and intermetallic superstructure NiAl in accordance with concentrations, structures and forms. It was understood that when the concentration in composite of phase of clean Al increases, or when the number of Al atoms in intermetallide rises, the initial temperature of thermo activated diffusing destruction of interphase borders turns out to be very low. On the other hand, when the part of clean nickel increases or when the concentration of clean Ni atoms in the structure (L1 2 ) rises, diffusion stability of interphase borders is observes right up to high temperatures. According to the results, basic diffusion processes take place right on interphase borders

  14. Delay discounting, treatment motivation and treatment retention among substance-dependent individuals attending an in inpatient detoxification program

    NARCIS (Netherlands)

    Stevens, Laura; Verdejo-García, Antonio; Roeyers, Herbert; Goudriaan, Anna E.; Vanderplasschen, Wouter

    2015-01-01

    Recent studies consistently indicate high rates of delay discounting in drug users, which refers to a strong tendency to devaluate delayed rewards. Many addiction treatment programs however, place high demands on the ability to postpone immediate gratification. Therefore, these programs may be

  15. Vascular Steal Explains Early Paradoxical Blood Oxygen Level-Dependent Cerebrovascular Response in Brain Regions with Delayed Arterial Transit Times

    Directory of Open Access Journals (Sweden)

    Julien Poublanc

    2013-04-01

    Full Text Available Introduction: Blood oxygen level-dependent (BOLD magnetic resonance imaging (MRI during manipulation of inhaled carbon dioxide (CO2 can be used to measure cerebrovascular reactivity (CVR and map regions of exhausted cerebrovascular reserve. These regions exhibit a reduced or negative BOLD response to inhaled CO2. In this study, we sought to clarify the mechanism behind the negative BOLD response by investigating its time delay (TD. Dynamic susceptibility contrast (DSC MRI with the injection of a contrast agent was used as the gold standard in order to provide measurement of the blood arrival time to which CVR TD could be compared. We hypothesize that if negative BOLD responses are the result of a steal phenomenon, they should be synchronized with positive BOLD responses from healthy brain tissue, even though the blood arrival time would be delayed. Methods: On a 3-tesla MRI system, BOLD CVR and DSC images were collected in a group of 19 patients with steno-occlusive cerebrovascular disease. For each patient, we generated a CVR magnitude map by regressing the BOLD signal with the end-tidal partial pressure of CO2 (PETCO2, and a CVR TD map by extracting the time of maximum cross-correlation between the BOLD signal and PETCO2. In addition, a blood arrival time map was generated by fitting the DSC signal with a gamma variate function. ROI masks corresponding to varying degrees of reactivity were constructed. Within these masks, the mean CVR magnitude, CVR TD and DSC blood arrival time were extracted and averaged over the 19 patients. CVR magnitude and CVR TD were then plotted against DSC blood arrival time. Results: The results show that CVR magnitude is highly correlated to DSC blood arrival time. As expected, the most compromised tissues with the longest blood arrival time have the lowest (most negative CVR magnitude. However, CVR TD shows a noncontinuous relationship with DSC blood arrival time. CVR TD is well correlated to DSC blood arrival time

  16. Load-Dependent Increases in Delay-Period Alpha-Band Power Track the Gating of Task-Irrelevant Inputs to Working Memory

    Directory of Open Access Journals (Sweden)

    Andrew J. Heinz

    2017-05-01

    Full Text Available Studies exploring the role of neural oscillations in cognition have revealed sustained increases in alpha-band power (ABP during the delay period of verbal and visual working memory (VWM tasks. There have been various proposals regarding the functional significance of such increases, including the inhibition of task-irrelevant cortical areas as well as the active retention of information in VWM. The present study examines the role of delay-period ABP in mediating the effects of interference arising from on-going visual processing during a concurrent VWM task. Specifically, we reasoned that, if set-size dependent increases in ABP represent the gating out of on-going task-irrelevant visual inputs, they should be predictive with respect to some modulation in visual evoked potentials resulting from a task-irrelevant delay period probe stimulus. In order to investigate this possibility, we recorded the electroencephalogram while subjects performed a change detection task requiring the retention of two or four novel shapes. On a portion of trials, a novel, task-irrelevant bilateral checkerboard probe was presented mid-way through the delay. Analyses focused on examining correlations between set-size dependent increases in ABP and changes in the magnitude of the P1, N1 and P3a components of the probe-evoked response and how such increases might be related to behavior. Results revealed that increased delay-period ABP was associated with changes in the amplitude of the N1 and P3a event-related potential (ERP components, and with load-dependent changes in capacity when the probe was presented during the delay. We conclude that load-dependent increases in ABP likely play a role in supporting short-term retention by gating task-irrelevant sensory inputs and suppressing potential sources of disruptive interference.

  17. Convergence Analysis of Semi-Implicit Euler Methods for Solving Stochastic Age-Dependent Capital System with Variable Delays and Random Jump Magnitudes

    Directory of Open Access Journals (Sweden)

    Qinghui Du

    2014-01-01

    Full Text Available We consider semi-implicit Euler methods for stochastic age-dependent capital system with variable delays and random jump magnitudes, and investigate the convergence of the numerical approximation. It is proved that the numerical approximate solutions converge to the analytical solutions in the mean-square sense under given conditions.

  18. Context-dependent Dynamic Processes in Attention Deficit/Hyperactivity Disorder : Differentiating Common and Unique Effects of State Regulation Deficits and Delay Aversion

    NARCIS (Netherlands)

    Sonuga-Barke, Edmund J. S.; Wiersema, Jan R.; van der Meere, Jacob J.; Roeyers, Herbert

    The ability to specify differential predictions is a mark of a scientific models' value. State regulation deficits (SRD) and delay aversion (DAv) have both been hypothesized as context-dependent dynamic dysfunctions in ADHD. However, to date there has been no systematic comparison of their common

  19. EXPOSURE TO DIETHYL HEXYL PHTHALATE (DEHP) DELAYS PUBERTY AND REDUCES ANDROGEN-DEPENDENT TISSUE WEIGHTS IN LONG EVANS HOODED AND SPRAGUE DAWLEY MALE RATS

    Science.gov (United States)

    DEHP is a plasticizer that alters sexual differentiation in the male rat by reducing fetal Leydig cell testosterone synthesis and insl3 mRNA levels. When exposure includes the pubertal stage of life, DEHP and other phthalates delay puberty and reduce androgen-dependent tissue wei...

  20. Collisionality dependence of Mercier stability in LHD equilibria with bootstrap currents

    International Nuclear Information System (INIS)

    Ichiguchi, Katsuji.

    1997-02-01

    The Mercier stability of the plasmas carrying bootstrap currents with different plasma collisionality is studied in the Large Helical Device (LHD). In the LHD configuration, the direction of the bootstrap current depends on the collisionality of the plasma through the change in the sign of the geometrical factor. When the beta value is raised by increasing the density of the plasma with a fixed low temperature, the plasma becomes more collisional and the collisionality approaches the plateau regime. In this case, the bootstrap current can flow in the direction so as to decrease the rotational transform. Then, the large Shafranov shift enhances the magnetic well and the magnetic shear, and therefore, the Mercier stability is improved. On the other hand, when the beta value is raised by increasing the temperature of the plasma with a fixed low density, the plasma collisionality becomes reduced to enter the 1/ν collisionality regime and the bootstrap current flows so that the rotational transform should be increased, which is unfavorable for the Mercier stability. Hence, the beta value should be raised by increasing the density rather than the temperature in order to obtain a high beta plasma. (author)