2,312 publications from this institution
This paper studies synchronization via pinning control on general multi-agent systems with strongly connected topologies. A criterion for reaching network synchronization on strongly connected networks is given. It is found that the vertices with very small in-degrees should be pinned first and the vertices with very large out-degrees may be pinned from the reformulated lower-order condition. Finally, a simulation example is given to verify the proposed pinning scheme.
The paper discusses the basic problem of chaos synchronization and derives some simple yet explicit conditions for its global convergence verification.
A new chaotic system is reported, which has asymmetry and non-similarity associated with its linearizing characteristics. Within a large range of parameters, the system has a very large positive Lyapunov exponent (LE) and an extremely small negative LE. Correspondingly, system orbits strongly expand in one direction but rapidly shrink in another direction. The expanding, shrinking, asymmetry and non-similarity of the system orbits increase its degrees of disorder and randomness. Bifurcation analysis further shows that the system has very rich bifurcations in different directions and extremely complicated dynamics. An electronic circuit of the new system has been built, which physically demonstrates the chaotic attractor in existence. Spectral analysis shows that the system in the chaotic mode has extremely broad-band frequencies, verifying its very strong randomness and indicating its good potential for technological applications.
No abstract is provided for this article.
A model reduction problem of certain large-scale Markov chains under an optimal criterion for Hankel-norm approximation is discussed. The multi-dimensional Markov chain under investigation is assumed to have a finite-dimensional stationary state-transition matrix, which is first reformulated as a multi-input/multi-output (MIMO) linear time-invariant (LT1) stochastic system. Consequently, the resulting large-scale MIMO LTI stochastic system has a closed-form best approximant in the Hankel-norm from a specified class of stable lower-dimensional MIMO LTI systems.
No abstract is provided for this article.
No abstract is provided for this article.
We often need to identify the colors of such objects as buildings, clothing, photos, and traffic signs in everyday life. Some people cannot distinguish among such colors. This study proposes a method to help people, including colorblind people, identify colors. We establish a platform for color identification that is connected by the Internet of Things (IoT). The Espressif Systems 32 (ESP32) single chip is connected to a Wi-Fi communication network to transmit data to the color identification platform. The system interface is displayed in the form of color code and color name display. The speech synthesis module Speech Synthesizer Node 6288 (SYN6288) is used to broadcast color-related information. Since there are many color conversion technologies in modern times, or other color recognition methods are not applicable to the guide-blind function. Therefore, the authors use the method of reading out color-related information to directly enable colorblind people to conveniently identify the colors of objects. After experiments: the accuracy of various colors, the accuracy of environmental impact, the comparison of the original sensing experiment and the effect of adding interference light sources, the time required for color sensing to identify various colors, and the interference test results of any color light source, it is proved that the research mentioned in this research. The proposed method can not only improve the rate of recognition of the system in different environments, but can also accurately identify a variety of colors. The platform is integrated with the IoT to allow users to quickly monitor the displayed data.
The heterogeneous patterns of interactions within a population are often described by contact networks, but the variety and adaptivity of contact strengths are usually ignored. This paper proposes a modified epidemic SIS model with a birth–death process and nonlinear infectivity on an adaptive and weighted contact network. The links' weights, named as ‘adaptive weights’, which indicate the intimacy or familiarity between two connected individuals, will reduce as the disease develops. Through mathematical and numerical analyses, conditions are established for population extermination, disease extinction and infection persistence. Particularly, it is found that the fixed weights setting can trigger the epidemic incidence, and that the adaptivity of weights cannot change the epidemic threshold but it can accelerate the disease decay and lower the endemic level. Finally, some corresponding control measures are suggested.
No abstract is provided for this article.
In this paper, we study a susceptible-infected-susceptible (SIS) model with time delay on complex heterogeneous networks. Here, the delay describes the incubation period in the vector population. We calculate the epidemic threshold by using a Lyapunov functional and some analytical methods, and find that adding delay increases the epidemic threshold. Then, we prove the global stability of disease-free and endemic equilibria by using the theory of functional differential equations. Furthermore, we show numerically that the epidemic threshold of the new model may change along with other factors, such as the infectivity function, the heterogeneity of the network, and the degrees of nodes. Finally, we find numerically that the delay can affect the convergence speed at which the disease reaches equilibria.
No abstract is provided for this article.
Congestion control in the Internet consists of two main components: the TCP Additive-Increase Multiplicative-Decrease (AIMD) mechanism on sending windows implemented by end-users, and the Active Queue Management (AQM) scheme implemented in the routers which improves the effectiveness of congestion control. TCP connection is regarded as a feedback control system. Comparably, AQM is classified as a flow controller. There are several kinds of time delays in the network, such as propagation delay, queuing delay in the buffer of the router, etc. The time delays cause degradation of performance and instability of the network. A Smith Predictor is commonly used in feedback control of plants with significant time delays to implement effective compensation. In this paper, a Smith Predictor-based PI-controller for AQM (SPPA) is proposed, which uses a TCP reference model and an average Round-Trip Time (RTT) to reduce unfavorable effects of time delays in TCP networks. The drop probability is calculated by a Proportional-Integral (PI) controller based on the prediction error. When a mismatch exists in between the actual model of the TCP process and the reference model employed by the SPPA, we demonstrate conditions under which the network is stable. The performance, robustness and effectiveness of the proposed SPPA are all evaluated using simulations. The performance of the SPPA is compared with some typical AQMs, such as the Adaptive RED, the PI-controller, and the Proportional-Differential (PD) controller.
