共查询到20条相似文献，搜索用时 31 毫秒
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《Journal of The Franklin Institute》2023,360(12):7770-7807
In this article, combining the transmission features of HPV infection and secondary cervical cancer in Xinjiang, China, a stochastic dynamical model for the HPV infection and secondary cervical cancer with environmental white noise is proposed. Firstly, the stochastic extinction of disease is investigated. A sufficient criterion for the asymptotic behavior of any positive solution of stochastic model revolving around the disease-free equilibrium of corresponding deterministic model is established. Secondly, a threshold criterion for the existence of unique ergodic stationary distribution is obtained by means of the auxiliary function. Furthermore, a new technique of partitioned matrix for the calculation of probability density function is proposed, the expression of a log-normal density function around the quasi-endemic equilibrium of stochastic model is calculated. Lastly, the best-fit parameter values in our model are identified by the MCMC algorithm on the basis of the cervical cancer data in Xinjiang province, China. The basic reproduction number is estimated as 1.3496 (95% CnI: (1.3458, 1.3716)). Then, to determine the key parameters of the model, the sensitivity analysis is explored. Some possible interventions and control measures are provided to reduce the HPV infection spread and cervical cancer in Xinjiang of China. 相似文献
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《Journal of The Franklin Institute》2023,360(7):5171-5210
In this study, we develop a vector-host transmission model with general incidence rates for the dynamics of pine wilt disease in deterministic and stochastic environments. The existence and local asymptotic stability of equilibria are investigated in the deterministic case. We show the required conditions for the ergodic stationary distribution and extinction of the model in the stochastic case by constructing appropriate Lyapunov functions. Furthermore, by solving the corresponding Fokker-Planck equation, we obtain exact expressions of probability density function around the quasi-equilibrium of the stochastic model. Finally, we employ comprehensive numerical simulations to support our results and compare deterministic and stochastic situations. 相似文献
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《Journal of The Franklin Institute》2019,356(10):5521-5540
The output-error model structure is often used in practice and its identification is important for analysis of output-error type systems. This paper considers the parameter identification of linear and nonlinear output-error models. A particle filter which approximates the posterior probability density function with a weighted set of discrete random sampling points is utilized to estimate the unmeasurable true process outputs. To improve the convergence rate of the proposed algorithm, the scalar innovations are grouped into an innovation vector, thus more past information can be utilized. The convergence analysis shows that the parameter estimates can converge to their true values. Finally, both linear and nonlinear results are verified by numerical simulation and engineering. 相似文献
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In this paper we consider a problem of controllability of discrete time linear system with randomly jumping parameters which can be described by finite state Markov chain. Necessary and sufficient conditions for existence of control which governs the system from any initial conditions to zero, from zero initial condition to any final value and from any initial condition to any final value in given time and with probability one are given. The relations between such kinds of controllability and stochastic stabilizability are discussed. 相似文献
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In this paper, sliding mode control for discrete time systems with stochastic noise in their input channel has been discussed. The idea of process control using control charts has influenced this new approach towards dealing with systems with stochastic noise. The new approach approximates the stochastic noise as a bounded uncertainty, similar to having bounds in the control charts for stochastic process control data. For discrete time systems, this results in a bounded stability in probability of the quasi sliding mode, which is referred to as the N-sigma bounded stability. The probability associated with the stability notions is not fixed and the control engineer may desire lower or higher degrees of stability in terms of this probability. Thus one has design flexibility while implementing the theory in practice, where one might have to adjust the desired degree of stability due to hardware limitations. 相似文献
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提出了用于有界动态随机系统的状态观测器设计方法.首先利用平方根B样条逼近系统的输出概率密度函数来构造残差,同时利用李亚普诺夫函数方法得到观测器增益的自适应调节规律,然后提出了新的对数B样条逼近模型并设计了新的自适应观测器,两个仿真例子表明了方法的有效性. 相似文献
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《Journal of The Franklin Institute》2019,356(12):6741-6756
This paper presents general, closed-form, and exact expressions for cumulative distribution function, probability density function and average value for the ratio of independent η-μ random variables, with arbitrary parameters. More specifically, the outage capacity with peak interference power constraint, the delay-limited capacity, and the ergodic capacity considering constraints on the interference power are derived for non-homogeneous environments containing multipath waves clusters. Numerical curves are presented to evaluate the effects of the general fading variables in spectrum sharing systems. Besides, the results are validated by performing Monte-Carlo simulations. Notably, the provided results find important applications in cognitive radio systems considering the spectrum sharing approach and channels modeled by η-μ distribution. 相似文献
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《Journal of The Franklin Institute》2022,359(6):2541-2563
In this paper, the secure consensus control issue is investigated for a class of discrete time-varying stochastic multi-agent systems (MASs) subject to cyber-attacks. In order to give a comprehensive characterization of malicious threats against communication networks, a generic model is presented to take into account both random false data injection attacks (FDIAs) and replay attacks. The main objective of the problem under study is to design a control protocol via output feedback such that, despite the existence of mixed attacks, all the individual agents can be driven to reside within a desired ellipsoidal region in a pre-specified probability. Sufficient conditions are provided for the existence of the requested controller and the feedback gains are formulated in terms of the solution to certain matrix inequalities. Within the established framework, two optimization problems are considered with the aim to ensure the sub-optimal consensus performances from different perspectives. Finally, a simulation example is employed to illustrate the validity of the proposed control scheme. 相似文献
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A problem of stabilization about uncertain networked control systems (NCSs) with random but bounded delays is discussed in this paper. By using augmented state-space method, this class of problems can be modeled as discrete-time jump linear systems governed by finite-state Markov chains. A new switched model based on probability is proposed to research problems of reliable control when actuators become ageing or partially disabled. Using improved V-K iteration algorithm, a class of reliable controllers are designed to make systems asymptotically mean square stable under several stochastic disturbances such as random time-delay and stochastic actuator failure and the maximal redundancy degree is given through this method. 相似文献
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The purpose of fault diagnosis of stochastic distribution control (SDC) systems is to use the measured input and the system output probability density functions (PDFs) to obtain the fault information of the SDC system. When the target PDF is known, the purpose of fault tolerant control of stochastic distribution control system is to make the output PDF still track the given distribution using the fault tolerant controller. However, in practice, time delay may exist in the data (or image) processing, the modeling and transmission phases. When time delay is not considered, the effectiveness of the fault detection, diagnosis and fault tolerant control of stochastic distribution systems will be reduced. In this paper, the rational square-root B-spline is used to approach the output probability density function. In order to diagnose the fault in the dynamic part of such systems, it is then followed by the novel design of a nonlinear neural network observer-based fault diagnosis algorithm. The time delay term will be deleted in the stability proof of the observation error dynamic system. Based on the fault diagnosis information, a new fault tolerant controller based on PI tracking control is designed to make the post-fault probability density function still track the given distribution, which is dependent of the time delay term. Finally, simulations for the particle distribution control problem are given to show the effectiveness of the proposed approach. 相似文献
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《Journal of The Franklin Institute》2006,343(4-5):372-388
This paper describes a simulation-based parameter design (PD) approach for optimizing machine operating strategy under stochastic running conditions. The approach presents a Taguchi-based definition to the PD problem in which control factors include machine operating hours, operating pattern, scheduled shutdowns, maintenance level, and product changeovers. Random factors include machine random variables (RVs) of cycle time (CT), time-between-failure (TBF), time-to-repair (TTR), and defects rate (DR). Machine performance, as a complicated function of control and random factors, is defined in terms of net productivity (NP) based on three key performance indicators: gross throughput (GT), reliability rate (RR), and quality rate (QR). It is noticed that the resulting problem definition presents both modeling and optimization difficulties. Modeling complications result from the sensitivity of machine RVs to different settings of machine operating parameters and the difficulty to estimate machine performance in terms of NP under stochastic running conditions. Optimization complications result from the limited capability of mathematical modeling and experimental design in tackling the resulting large-in-space combinatorial optimization problem. To tackle such difficulties, therefore, the proposed approach presents a combined empirical modeling and Monte Carlo simulation (MCS) method to model the sensitive factors interdependencies and to estimate NP under stochastic running conditions. For combinatorial optimization, the approach utilizes a simulated-annealing (SA) heuristic to solve the defined PD problem and to provide optimal or near optimal settings to machine operating parameters. Approach procedure and potential benefits are illustrated through a case study example. 相似文献
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考虑在随机利率情形下由n个同质的被保人所组成的终身寿险组合的现值函数。在各被保人的未来余命随机变量相互独立的情形下,得到了现值函数的极限分布。并进一步考虑采用Dhaene等人所研究的Comonotonicity方法,给出了现值函数极限分布的上、下凸界。文章最后给出了一个数值模拟说明其主要结果。 相似文献
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In this paper, the event-triggered distributed H∞ state estimation problem is investigated for a class of state-saturated systems with randomly occurring mixed delays over sensor networks. The mixed delays, which comprise both discrete and distributed delays, are allowed to occur in a random manner governed by two mutually independent Bernoulli distributed random variables. In order to alleviate the communication burden, an event-triggered mechanism is utilized for each sensor node to decide whether or not its current information should be broadcasted to its neighbors. The aim of this paper is to design event-triggered state estimators such that the error dynamics of state estimation is exponentially mean-square stable with a prescribed H∞ performance index. By resorting to intensive stochastic analysis, sufficient conditions are first derived to guarantee the existence of the desired estimators, and the parameters of the desired distributed estimators are then obtained in light of the feasibility of a certain set of matrix inequalities. A numerical example is employed to illustrate the usefulness of the proposed distributed estimation algorithm. 相似文献
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This note is concerned with the static output feedback control problem for two-dimensional (2-D) uncertain stochastic nonlinear systems. The systems under consideration are subjected to time delays, multiplicative noises and randomly occurring missing measurements. A random variable sequence following the Bernoulli distribution with time-varying probability is employed to character the missing measurements which are assumed to occur in a random way. A new gain-scheduling method based on the time-varying probability parameter is proposed to accomplish the design task. By constructing a suitable Lyapunov functional, sufficient conditions to guarantee the systems to be mean-square asymptotically stable are established. The addressed 2-D controller design problem can be reduced to a convex optimization problem by some mathematical techniques. In the last section, a numerical example and the comparative analysis are provided to illustrate the efficiency of our proposed design approach. 相似文献
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The problem of the estimation of a discrete probability density from independent observations is considered. For a wide class of noises, a method is given for estimating a probability density when the measurements are corrupted by additive noise. This method is shown to be consistent, and several bounds on the error are given. An application to the detection of a (nonparametric) random signal is discussed. Finally, the estimation of a probability density is considered where the measurements are noisy and some of the measurements are incorrect. This situation may arise when a machine collecting the data fails part of the time. 相似文献
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This paper investigates the problem of secure control for networked control systems (NCSs) under randomly occurring zero-value attacks (ROZVAs). Specifically, ROZVAs only offset the true signal without injecting obfuscated information or noises, and possess the minimum energy of the added malicious information. To protect system stability against ROZVA, randomly occurring integrity check protection (ROICP) is introduced which prevents malicious data injection with less energy cost than persistently occurring protection. Besides the random phenomena of ROZVA and ROICP, which are characterized by two mutually independent random variables obeying the Bernoulli distribution, the randomly occurring time delays caused by ROICP are also considered in system modelling. According to the built stochastic linear system model, security analysis of the NCS with ROICP subject to ROZVA is carried out and sufficient condition for stochastic stability is derived via a linear matrix inequality (LMI) approach. Based on the proposed condition, a compensation feedback controller is designed to facilitate system stability. Finally, simulation results show the effectiveness of the proposed method. 相似文献
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Likang Feng Weihai Zhang Zhichun Yang Ju H. Park 《Journal of The Franklin Institute》2021,358(10):5426-5450
In this paper, the global asymptotic stability in probability and the exponential stability in th moment are investigated for random nonlinear systems with stochastic impulses, whose occurrence is determined by a Poisson process. The stochastic disturbances in the impulsive random nonlinear systems are driven by second-order processes, which have bounded mean power. Firstly, the improved Lyapunov approaches for the global asymptotic stability in probability and the exponential stability in th moment are established for impulsive random nonlinear systems based on the uniformly asymptotically stable function. Secondly, the improved results are further extended to the impulsive random nonlinear systems with Markovian switching. Finally, two examples are provided to verify the feasibility and effectiveness of the obtained results. 相似文献
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《Journal of The Franklin Institute》2021,358(15):7413-7425
This paper deals with the problem of stabilization via synchronous state-feedback control for two-dimensional (2-D) discrete-time Roesser systems with stochastic parameters involving switchings and multiplicative stochastic noises. The switching process is driven by an inhomogeneous Markov chain whose transition probability matrix is piecewise time-invariant and external disturbances are of the type of white noises, which get multiplied into both system state and input vectors. Stability and tractable controller design conditions are derived based on a 2-D mode-dependent Lyapunov function approach, which are validated by a numerical example with simulations. 相似文献