This paper addresses the energy saving problem in single-rod electro-hydraulic servo system (EHSS) driven by servo motor. Firstly, the performance of key components in EHSS is analyzed and tested locally and globally to pursue better control effect. Then, an energy saving controller containing three control variables is proposed. The servo valve controller is designed based on ARC to guarantee a prescribed output tracking transient performance and final tracking error. The relief valve controller is constructed based on disturbance observer to estimate the unknown disturbance-load force without a force sensor. The servo motor controller is designed via a grey model to predict the displacement of load. From these three sub controllers, the supply pressure and supply flow rate can be derived and controlled to achieve energy saving. Finally, the proposed method was validated by comparative experiments, which shows this control strategy can reduce about half of the power consumption.
Identifying network structures from dynamical observations is a fundamental problem currently pervading scientific research on complex systems, as understanding and modeling the structure of a complex network will lead to greater knowledge of its evolutionary mechanisms and to a better understanding of its functional behaviors. Usually, one needs to identify a network’s structure through a limited number of observations. Particularly, couplings of many real-world networks are sparse and continuously varying with time. In this study, a new framework is developed via optimization for identifying structures of continuously-varying weighted networks formed by sparsely-connected dynamical systems. Furthermore, a regularization technique is employed to increase the numerical stability of the parameter estimation algorithm. Three numerical examples are provided to illustrate the feasibility and effectiveness of the proposed identification method. In comparison with other existing techniques, the main advantages of our method include its ability to identify structures of continuously-varying weighted networks in addition to static ones, as well as its requirement of a relatively small number of observations. The proposed method has a potential applicability to a variety of evolving complex dynamical networks.
Many social and biological networks consist of communities–groups of nodes within which links are dense but among which links are sparse. It turns out that most of these networks are best described by weighted networks, whose properties and dynamics depend not only on their structures but also on the link weights among their nodes. Recently, there are considerable interests in the study of properties as well as modelling of such networks with community structures. To our knowledge, however, no study of any weighted network model with such a community structure has been presented in the literature to date. In this paper, we propose a weighted evolving network model with a community structure. The new network model is based on the inner-community and inter-community preferential attachments and preferential strengthening mechanism. Simulation results indicate that this network model indeed reflect the intrinsic community structure, with various power-law distributions of the node degrees, link weights, and node strengths.
This paper shows that there exists a contraction whose Zadeh's extension is not a contraction under the Skorokhod metric, answering negatively Problems 5.8 and 5.12 posted in [Jardón, Sánchez, and Sanchis, Some questions about Zadeh's extension on metric spaces, Fuzzy Sets and Systems, 2018].
No abstract is provided for this article.
In this paper, a new epidemic SIS model with nonlinear infectivity, as well as birth and death of nodes and edges, is investigated on heterogeneous networks. The global behavior of the model is studied mathematically. When the basic reproductive number is less than or equal to unity, it is verified that the disease dies out; otherwise, the model solutions lead to positive steady states. This paper provides a concise mathematical analysis to verify the global dynamics of the model.
Temporal networks are composed of individuals with on-and-off interactions. In the study of human dynamics, a typical interaction is interpreted as a coincidental or forced concurrence of two events. Since human beings' rationality is bounded, the interaction between sentient individuals is normally investigated under the framework of game theory in the past half a century. In this brief, a game model on social networks is introduced, in which individuals play a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times2$ </tex-math></inline-formula> divide-and-conquer game with their neighbors, which is a specific symmetric game based on the type of their interactions. The individuals in a network play with the game with a certain strategy. The duration of a continuous interaction is defined to be the number of the continuous rounds in which at least one of them receives a non-zero payoff. On the contrary, the inter-event time is measured by the number of the continuous rounds in which both players do not receive any payoff. A detailed analytical and numerical study of the model's dynamical properties is presented, showing that it reproduces the burstiness of the human coordinating system. The findings reveal that the burstiness is inducible by rational interactions of humans. The new model and analysis shed some new lights on the origin of the burstiness of human activities.
The distribution characteristics of zooplankton in shallow urban lakes of Lingnan that in the tropics and subtropics were studied. The results showed that Brachionus, Trichocerea, and Lecane were dominant species of composition and abundance. The abundance of large Cladocera was low, which was affected by high water temperature, food restriction, and predation pressure of fish. Rotifera, small Cladocera, and Nauplius were the main zooplankton. Combined with the analysis of typical tropical shallow urban lakes, the dominant zooplankton tended to have a small individual population. It was expected to provide a reference for the ecological restoration of tropical shallow-water urban lakes.
No abstract is provided for this article.
Current specifications do not stipulate the time criteria for opening the movable guardrails fast. This results in a number of application issues of movable guardrails on the expressway, one of which is that the connection structure is complex and difficult to open. As a result, the movable guardrail lost the important function of opening quickly which significantly affects emergency management on the expressway. According to the application conditions and the characteristics of emergency management of the movable guardrail, this paper analyzes and calculates the time difference between the emergency routes and the normal routes which the emergency vehicles take to reach the site of incident. The results show that it can save time at least 24 minutes if the vehicles travel the emergency route. Finally, considering the existing technical and economic conditions, we propose the maximum time to open the movable guardrail quickly is 12 minutes, which is equal to half of the minimum time difference. It can improve the performance index system of the movable guardrail.
The authors study how to design a conventional nonlinear feedback controller to drive a chaotic trajectory of the well-known (continuous-time) Duffing system to any of its inherent periodic orbits. The motivation for this research is twofold. First, the controller's design for driving a chaotic trajectory to a periodic orbit is more difficult and hence more interesting from a theoretical point of view. Second, it has a more significant physical meaning, for example, when a periodic oscillation of a machine is expected to be recovered from its chaotic situations during the motion and then to be maintained thereafter.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
The stochastically perturbed Chen system is studied within the parameter region which permits both regular and chaotic oscillations. As noise intensity increases and passes some threshold value, noise-induced hopping between close portions of the stochastic cycle can be observed. Through these transitions, the stochastic cycle is deformed to be a stochastic attractor that looks like chaotic. In this paper for investigation of these transitions, a constructive method based on the stochastic sensitivity function technique with confidence ellipses is suggested and discussed in detail. Analyzing a mutual arrangement of these ellipses, we estimate the threshold noise intensity corresponding to chaotization of the stochastic attractor. Capabilities of this geometric method for detailed analysis of the noise-induced hopping which generates chaos are demonstrated on the stochastic Chen system.
We obtain sufficient conditions for the oscillation of all solutions of the linear partial difference equations with positive and negative coefficients of the form A m-1,n + A m,n-1 - A mn + pA m+k - qA m+k' = 0, n+1 n+l' and A m-1,n + A m,n-1 - A mh + p mn A m+k - q mn A m+k' = 0, n+l n+l' where m,n = 0, 1,..., and k, k', l', l are nonnegative integers p, q ∈ (0, oo), and coefficients {q mn } and {p mn } are sequences of nonnegative real numbers. In this paper A mn = A m,n .
A problem of reducing a general three-dimensional (3-D) autonomousquadratic system to a Lorenz-type system is studied. Firstly, undersome necessary conditions for preserving the basic qualitativeproperties of the Lorenz system, the general 3-D autonomousquadratic system is converted to an extended Lorenz-type system(ELTS) which contains a large class of existing chaotic dynamicalsystems. Secondly, some different canonical forms of the ELTS areobtained with the aid of various nonsingular linear transformationsand normalization techniques. Thirdly, the conjugate systems of theELTS are defined and discussed. Finally, a sufficient condition forthe nonexistence of chaos in such ELTS is derived.
This article briefly reviews the topic of complex network synchronization, with its graph-theoretic criterion, showing that the homogeneous and symmetrical network structures are essential for optimal synchronization. Furthermore, it briefly reviews the notion of higher-order network topologies and shows their promising potential in application to evaluating the optimality of network synchronizability.
