Considering the complexity of lag time and the convergence time, as well as the influence of the observer and the event-triggered mechanism, the prescribed-time lag bipartite consensus (PTLBC) control problem for nonlinear multi-agent systems (MASs) is researched in the paper. First of all, it designs the prescribed-time dynamic observer (PTDO) for followers to get the states of the leader within an arbitrarily prescribed time. Furthermore, to significantly decrease the communication consumption, the innovative event-triggered mechanism is studied for followers. To realize the lag bipartite consensus (LBC) of nonlinear MASs within an arbitrarily prescribed time, a PTLBC control scheme is presented via the aforementioned PTDO and event-triggered mechanism. With Lyapunov stability analysis method, sufficient conditions are obtained and detailed stability analysis is studied, which indicates that the nonlinear MASs can realize PTLBC. Furthermore, the analysis proves that the proposed event-triggered mechanism excludes Zeno behaviour. The theoretical analysis is validated by means of a simulation example.

This paper investigates the event-triggered prescribed-time bipartite consensus of nonlinear multi-agent systems. In order to significantly reduce the communication burden and energy consumption, a novel event-triggered mechanism and triggering condition are proposed. Then, a distributed prescribed-time control protocol is proposed for the discussed nonlinear multi-agent systems to achieve bipartite consensus within the prescribed time based on the event-triggered mechanism. Using the Lyapunov stability theory, the stability of the nonlinear multi-agent systems is proved and the corresponding sufficient conditions are obtained. Moreover, it is shown that the Zeno behavior can be excluded. Simulation results are presented to show the effectiveness of the theoretical results.

This paper investigates the observer-based prescribed-time time-varying output formation-containment (PT-TV-OFC) control problem for heterogeneous multi-agent systems in which the different agents have different state dimensions. The system comprises one tracking leader, multiple formation leaders, and followers, where two types of leaders are used to generate a reference trajectory for movement and achieve specific formation, respectively. Firstly, a prescribed-time dynamics observer is constructed for the formation leaders to estimate the tracking leader’s dynamic model and state. On this basis, a prescribed-time control protocol is designed for the formation leaders to achieve time-varying output formation. Then, a prescribed-time convex hull observer is designed for the followers to estimate information regarding the convex hull formed by the formation leaders. Using the estimated convex hull information, a prescribed-time containment control protocol is designed to ensure the followers converge into the convex hull. Furthermore, using Lyapunov stability theory, the stability of systems is proved in detail, which implies that the heterogeneous multi-agent systems can achieve PT-TV-OFC control. Finally, numerical simulations validate the feasibility of the theoretical results.

This paper concentrates on bipartite formation control for nonlinear leader-following multi-agent systems (MASs) with fixed and switching topologies under aperiodic Denial-of-Service (DoS) attacks. Firstly, distributed control protocols are proposed under the aperiodic DoS attacks based on fixed and switching topologies. Then, considering control gains, as well as attack frequency and attack length ratio of the aperiodic DoS attacks, using algebraic graph theory and the Lyapunov stability method, some criteria are acquired to ensure that the nonlinear leader-following MASs with either fixed or switching topologies can realize bipartite formation under aperiodic DoS attacks. Finally, numerical simulations are carried out to validate the correctness of the theoretical results.

Nowadays, online gambling has a great negative impact on the society. In order to study the effect of people’s psychological factors, anti-gambling policy, and social network topology on online gambling dynamics, a new SHGD (susceptible–hesitator–gambler–disclaimer) online gambling spreading model is proposed on scale-free networks. The spreading dynamics of online gambling is studied. The basic reproductive number $R_{0}$ is got and analyzed. The basic reproductive number $R_{0}$ is related to anti-gambling policy and the network topology. Then, gambling-free equilibrium $E_{0}$ and gambling-prevailing equilibrium $E_{ +} $ are obtained. The global stability of $E_{0}$ is analyzed. The global attractivity of $E_{ +} $ and the persistence of online gambling phenomenon are studied. Finally, the theoretical results are verified by some simulations.

《信息处理系统》课程设计是锻炼和强化学生专业综合设计能力的重要教学环节.以长江大学电子信息工程专业为例,结合湖北省卓越计划建设目标,针对目前《信息处理系统》课程设计的现状及存在的问题,探讨以协同创新能力培养的《信息处理系统》课程设计的改革措施及实施内容.新形式、新思想的课程设计体现以人为本、以学生为主的理念,将协同创新理念引入课程设计,扩充课程设计内容的数量和类型,以团队协作方式共同完成课程设计,激发学生的创新意识,提高学习的积极性和主动性.

With the development of the Internet, online shopping has become a popular way of life in contemporary society. In recent years, online group booking has become an important strategy for e-commerce to promote commodities. In order to study the impact of the products’ discount rate, customer’s repurchase intention and the heterogeneity of the networks on the spreading of group booking preferential information, we present a novel $CPFB$ (customer-participant-forwarder-beneficiary) group booking preferential information spreading model based on scale-free networks. The dynamic propagation of preferential information in group booking online is analyzed in detail by the mean-field theory. The basic reproductive number $R_{0} $ and the two equilibriums are obtained. Then, locally asymptotical stability of equilibriums is discussed based on the Routh–Hurwitz criterion. The global asymptotic stability of the group booking free equilibrium, the permanence of preferential information spreading and the global attractivity of the group booking equilibrium is proved in detail. Theoretical results show that the basic reproductive number $R_{0} $ depends mainly on the discount rate and the topology of the underlying networks. And the size of the repurchase intention rate $\eta $ can promote the spreading of preferential information about online group booking, but do not affect the size of the basic reproductive number $R_{0} $ . Finally, numerical simulations confirm the analytical results of the theories.

Aiming at the problem that the digital watermark is vulnerable to be attacked, a digital watermark algorithm based on QR code is proposed in this paper. Firstly, encoding the text information to QR code as digital watermark, then host image is decomposed by discrete wavelet transform, and then the low-frequency sub-band have singular value decomposition, and the watermark information is embedded into the image. The experimental results show that the proposed method can resist the common attacks such as rotation, shearing, noise and so on, and it also has a good robustness to the change of histogram equalization and contrast ratio. QR code watermark is scrambled, which not only increases the anti-attack of digital watermark, but also make the watermark image to carry more information and has confidentiality, so digital watermark technology can be widely applied in the copyright protection for digital products.

In this paper, a modified SIS (susceptible-infected-susceptible) model with infective medium and feedback mechanism on scale-free networks is presented.The model is suited to describe some epidemic spreading which are not only transmitting by medium but also spreading between individuals by direct contacts.Considering biological relevance and people's subjective consciousness, we introduce medium and feedback to describe the epidemic spreading.By mathematical analysis, we obtain the epidemic threshold and equilibriums.Simulation shows that the medium parameter can change the threshold, and the bigger it is, the easier epidemic breaks.Feedback parameter cannot change the basic reproductive number, but it can reduce the endemic level and weaken the epidemic spreading.

传统的数字图像处理课堂教学中存在着板书教学讲解形式单一,学生不易理解的不足,文中提出以MATLAB作为教学辅助手段改革图像处理课程的教学方法,提高学生的学习兴趣和教学效果.主要通过对图像小波变换及噪声滤除两方面的问题展开分析,运用MATLAB实现图像的小波变换和滤除噪声的仿真,其结果以图像形式生动地表现出来.结果表明MATLAB在多媒体教学中的重要的辅助作用,学生能真实地体会图像理论知识及具体应用不断激发学习的兴趣,提高教学效果.

In this paper, we present a SARS (susceptible-adopted-removed-susceptible) social information spreading model with overlapping community structures on complex networks.Using the mean field theory, the spreading dynamic of the model has been studied.At first, we derived the spreading critical threshold value and equilibriums.Theoretical results indicate that the existence of equilibriums is determined by threshold value.The threshold value is obviously dependent on the topology of underlying networks.Furthermore, the globally asymptotically stable equilibriums are proved in detail.The overlap parameter of community structures can't change the threshold value, but it can influence the extent of the social information spreading.Numerical simulations confirmed the analytical results.

The rumor spreading has been widely studied by scholars. However, there exist some people who will persuade infected individuals to resist and counterattack the rumor propagation in our social life. In this paper, a new SICS (susceptible-infected-counter...

Image is often easily polluted by noise in the process of image processing, so image de-noising is an important step in the field of image processing. Based on the wavelet threshold de-noising algorithm, an improved image de-noising algorithm based on wavelet and Wiener filter is proposed in this paper, which can effectively reduce the Gaussian white noise. Firstly we use wavelet soft threshold to reduce noise, then use Wiener filter to process the image and get the valuation of the image. Experimental results show that the proposed algorithm on image de-noising not only can effectively suppress Gaussian white noise, but also can well retain the details of image edges.

In order to study the influence of the preferential degree and the heterogeneity of underlying networks on the spread of preferential e-commerce information, we propose a novel susceptible–infected–beneficial model based on scale-free networks. The spreading dynamics of the preferential information are analyzed in detail using the mean-field theory. We determine the basic reproductive number and equilibria. The theoretical analysis indicates that the basic reproductive number depends mainly on the preferential degree and the topology of the underlying networks. We prove the global stability of the information-elimination equilibrium. The permanence of preferential information and the global attractivity of the information-prevailing equilibrium are also studied in detail. Some numerical simulations are presented to verify the theoretical results.

A SIRS epidemic model with feedback mechanism on adaptive scale-free networks is presented. Using the mean field theory the spreading dynamics of the epidemic is studied in detail. The basic reproductive number and equilibriums are derived. Theoretical results indicate that the basic reproductive number is significantly dependent on the topology of the underlying networks. The existence of equilibriums is determined by the basic reproductive number. The global stability of disease-free equilibrium and the epidemic permanence are proved in detail. The feedback mechanism cannot change the basic reproductive number, but it can reduce the endemic level and weaken the epidemic spreading. Numerical simulations confirmed the analytical results.

In order to effectively improve the image encryption effect and safety, on the base of studying tradition image scrambling algorithm, an improved scrambling algorithm of digital image based on chaotic systems and bit operation is proposed. By using XOR operation, the algorithm used the self-f-relativity of image to scramble image. Experimental results show that the improved algorithm has good encryption effect and safety.

There has a constant barrage of worms over the internet in recent years. In order to effectively prevent worm spreading, researchers are trying to understand the behavior of the worm propagation with the aid of epidemiological models. In this paper a worm propagation model with time delay and quarantine strategy is proposed and discussed. The spreading dynamics of the worms is analyzed, the spreading critical threshold and equilibriums are derived. The global stability of equilibriums is proved and numerical simulations are presented to confirmed the analytical results.

A modified spreading dynamic model with feedback-mechanism based on scale-free networks is presented in this study. Using the mean field theory, the spreading dynamics of the model is analyzed. The spreading threshold and equilibriums are derived. The relationship between the spreading threshold, the epidemic steady-state and the feedback-mechanism is analyzed in detail. Theoretical results indicate the feedback-mechanism can increase the spreading threshold, resulting in effectively controlling the epidemic spreading.

In order to investigate the influence of heterogeneity of the underlying networks and quarantine strategy on epidemic spreading, a SIQRS epidemic model on the scale-free networks is presented. Using the mean field theory the spreading dynamics of the virus is analyzed. The spreading critical threshold and equilibria are derived. Theoretical results indicate that the critical threshold value is significantly dependent on the topology of the underlying networks and quarantine rate. The existence of equilibria is determined by threshold value. The stability of disease-free equilibrium and the permanence of the disease are proved. Numerical simulations confirmed the analytical results. (C) 2013 Elsevier B.V. All rights reserved.

In the SIR model once a node is cured after infection it becomes permanently immune,but we assume this immunity to be temporary. So we obtain an epidemic model with time delay on scale-free networks. Using the mean field theory the spreading threshold and the spreading dynamics is analyzed. Theoretical results indicate that the threshold is significantly dependent on the topology of scale-free networks and time delay. Numerical simulations confirmed the theoretical results.