基于规则推理的输电网络故障诊断方法

当输电网络有故障发生,如果处理不当,或者报警信息错误,就会产生难以预计的损失和后果,故电网故障诊断成了重要的研究对象?针对上述问题,文中提出了一种基于规则推理的输电网络故障诊断方法,通过建立电力网络的Petri网模型,分析故障变迁的可诊断子网结构信息和内部托肯的流动形式,经过相关故障规则推理来定位故障元件位置,并运用IEEE-14局部电路图进行了故障仿真运算。仿真结果表明,规则推理故障诊断方法能够对输电网络故障进行精确迅速的故障定位与分析,是一种有效可行的故障诊断方法?

基于Dijkstra算法的最短路径的实现

通过Dijkstra算法编程计算出了青海省西宁市至海东各县之间的最短距离,目的是能为出行的人们提供参考,节省更多时间和交通费用。

胶印机输墨系统动态着墨率研究

传统着墨率的计算方法只表示不同着墨辊的着墨比率,其值与墨辊排列方式无关,属于静态指标。因此对不同的墨辊排列结构,动态着墨率对输墨性能的评价更有实际意义。文章以罗兰Roland 700及其2种改变分流结构的输墨系统为对象,将输墨系统抽象为有向网,并对油墨传递过程离散化。经计算机仿真,得到3种排列结构下输墨系统的动态着墨率,从而为输墨系统的结构设计及优化提供一定理论依据。

基于加权策略的最优公交车路径检索模型

人们在出行前常会规划出行线路,将距离、时间及线路等作为主要的考虑因素,其路径检索模型是一种集距离、目标和交通模式为一体的复杂检索模型。该文基于有向网构建一种新的检索模型,该模型不仅能通过加权策略来满足出行者多目标检索的需求,且能通过改变速度来实现多种交通工具的换乘。最后,以真实数据建模验证了该模型的有效性和实用性。

Support vector regression-based internal model control

This paper proposes a design of internal model control systems for process with delay by using support vector regression(SVR).The proposed system fully uses the excellent nonlinear estimation performance of SVR with the structural risk minimization principle.Closed-system stability and steady error are analyzed for the existence of modeling errors.The simulations show that the proposed control systems have the better control performance than that by neural networks in the cases of the training samples with small size and noises.

Correspondence Between Bell Bases and Oriented Links in Knot Theory

From the comparison of correlation tensor in the theory of quantum network, the Alexander relation matrix in the theory of knot crystals and the identical inversion relations under the action of Pauli matrices, we show that there is a one to one correspondence between four Bell bases and four oriented links of the linkage in knot theory.

Comparison of flow behaviors of near beta Ti-55511 alloy during hot compression based on SCA and BPANN models

The flow behavior of Ti-55511 alloy was studied by hot compression tests at temperatures of 973−1123 K and strain rates of 0.01−10 s^(−1).Strain-compensated Arrhenius(SCA)and back-propagation artificial neural network(BPANN)methods were selected to model the constitutive relationship,and the models were further evaluated by statistical analysis and cross-validation.The stress−strain data extended by two models were implanted into finite element to simulate hot compression test.The results indicate that the flow stress is sensitive to deformation temperature and strain rate,and increases with increasing strain rate and decreasing temperature.Both the SCA model fitted by quintic polynomial and the BPANN model with 12 neurons can describe the flow behaviors,but the fitting accuracy of BPANN is higher than that of SCA.Sixteen cross-validation tests also confirm that the BPANN model has high prediction accuracy.Both models are effective and feasible in simulation,but BPANN model is superior in accuracy.

Applications of Graph Theory to Gross Error Detection for GPS Geodetic Control Networks

This paper describes a broad perspective of the application of graph theory to establishment of GPS control networks whereby the GPS network is considered as a connected and directed graph with three components.In this algorithm the gross error detection is undertaken through loops of different spanning trees using the "Loop Law" in which the individual components Δ X, Δ Y and Δ Z sum up to zero.If the sum of the respective vector components ∑X,∑Y and ∑Z in a loop is not zero and if the error is beyond the tolerable limit (ε>w),it indicates the existence of gross errors in one of the baselines in the loop and therefore the baseline must be removed or re_observed.After successful screening of errors by graph theory,network adjustment can be carried out.In this paper,the GPS data from the control network established as reference system for the HP Dam at Baishan county in Liaoning province is presented to illustrate the algorithm.

Optimal Rate Allocation Based on Cross-Layer Design and End-to-End Congestion Control in WCDMA Networks

In this paper, a novel idea for rate allocation combining both vertical coupling and horizontal coupling constraints is proposed, and a unified utility function to balance two paradoxical issues: efficiency and fairness, revenue and cost is elaborated in WCDMA networks. Then, the optimal rate allocation problem is formulated as a network utility maximization(NUM) model based on cross-layer design and end-to-end congestion control, aiming at exploring the impacts of wired networks and the characteristics of radio access networks(RANs) on rate allocation. Furthermore, a distributed algorithm is derived, which can effectively match load states between RANs and wired networks, followed by a detailed illustration of the practical implementations. Numerical results demonstrate a signifi cant performance improvement in the end-to-end throughput.

一种基于网络最大可控子图的导航搜索模型

基于网络可控性模型提出了最大可控子图的概念,在此基础上提出了一种基于最大可控子图的导航搜索模型.模型中基于最大可控子图的加边策略用最小的代价解决了有向网络搜索中存在的粒子因"无路可走"而终止搜索的问题;基于最大可控子图部署导航节点,仅用节点总数2%左右的导航点,就使全网搜索时间接近导航网络的平均最短路径.通过在ER和SF网络上的实验表明,全网搜索时间与网络的可控性有关,可控性越好,添加的边数量越少,同时会使网络中导航节点分布越多,越能提高网络的搜索效率.

Nonconforming Finite Element Approximation on Anisotropic Meshes with Numerical Quadrature

In this paper we mainly discuss the nonconforming fimte element method for second order elliptic boundary value problems on anisotropic meshes. By changing thediscretization form（i.e., by use of numerical quadrature in the procedure of computing the left load）, we obtain the optimal estimate O（h）, which is as same as in the traditionalfinite element analysis when the load f ∈ H1 （Ω）η Co（Ω） which is weaker than the previousstudies. The results obtained in this paper are also valid to the conforming triangular elementand nonconforming Carey＇s element.

The Extension of Infinitesimal Prolongation Theorem and Its Application

Infinitesimal prolongation theorem is extended from sequences to nets based on κ-saturated nonstandard model. As its an application, a main property about topology of uniform convergence is proved. The proof is much simpler than it was, meanwhile the nonstandard characteristics of convergence with respect to u.c. topology is given.

Unnormalized and normalized forms of gefura measures in directed and undirected networks

In some networks nodes belong to predefined groups （e.g., authors belong to institutions）. Common network cen- trality measures do not take this structure into account. Gefura measures are designed as indicators of a node＇s brokerage role between such groups. They are defined as variants of betweeuness centrality and consider to what extent a node belongs to shortest paths between nodes from different groups. In this article we make the following new contributions to their study： （1） We systematically study unnormalized gefura measures and show that, next to the ＇structural＇ normalization that has hitherto been applied, a ＇basic＇ normalization procedure is possible. While the former normalizes at the level of groups, the latter normalizes at the level of nodes. （2） Treating undirected networks as equivalent to symmetric directed networks, we expand the definition of gefura measures to the directed case. （3） It is shown how Brandes＇ algorithm for betweenness centrality can be adjusted to cover these cases.

Designing a novel consensus protocol for multiagent systems with general dynamics under directed networks

The consensus problem for general linear multi-agent systems （MASs） under directed topology is investigated. First, a novel consensus protocol based on proportional-integral-derivative （PID） control is proposed. Second, the consensus problem is converted into an asymptotic stability problem through transformations. Third, through a state projection method the consensus condition is proved and the explicit expression of the consensus function is given. Then, a Lyapunov function is constructed and the gain matrices of the protocol are given based on the linear matrix inequality. Finally, two experiments are conducted to explain the advantages of the method. Simulation results show the effectiveness of the proposed algorithm.

Global Systemic Financial Risk Spillovers and Their External Shocks

The shock of the global financial crisis sparked widespread concern across the world about systemic financial risk and led to the reexamination of regulatory mechanisms.The traditional principle of“too big to fail”underwent a transformation into the new idea of“too interconnected to fail.”We used Directed Acyclic Graph(DAG)technology and network topology analysis to examine the dynamic evolution of global systemic financial risk and the risk trends in global financial markets from the perspective of network connectivity.Our findings show that financial markets in the Chinese Mainland are net receivers of risk spillovers and that systemic financial risk has a clear cross-market contagion effect due to a global volatility spillover scale of 64 percent.To maintain the stability and security of China’s financial markets,consideration should be given to the regulatory precept of“too interconnected to fail”in establishing macro-prudential risk prevention mechanisms.

PARAMETER-UNIFORM FINITE DIFFERENCE SCHEME FOR A SYSTEM OF COUPLED SINGULARLY PERTURBED CONVECTION-DIFFUSION EQUATIONS

A coupled system of singularly perturbed convection-diffusion equations is considered. The leading term of each equation is multiplied by a small positive parameter, but these parameters may have different magnitudes. The solutions to the system have boundary layers that overlap and interact. The structure of these layers is analyzed, and this leads to the construction of a piecewise-uniform mesh that is a variant of the usual Shishkin mesh. On this mesh an upwind difference scheme is proved to be almost first- order accurate, uniformly in both small parameters. We present the results of numerical experiments to confirm our theoretical results.

MULTI-FACILITY ORDERED MEDIAN PROBLEMS IN DIRECTED NETWORKS

This paper uses a finite dominating set （FDS） to investigate the multi-facility ordered median problem （OMP） in a strongly connected directed network. The authors first prove that the multi-facility OMP has an FDS in the node set, which not only generalizes the FDS result provided by Kalcsics, et al. （2002）, but also extends the FDS result from the single-facility Case to the multiple case, filling an important gap. Then, based on this FDS result, the authors develop an exact algorithm to solve the problem. However, if the number of facilities is large, it is not practical to find the optimal solution, because the multi-facility OMP in directed networks is NP-hard. Hence, we present a constant-approximation algorithm for the p-median problem in directed networks. Finally, we pose an open problem for future research.

AN ANISOTROPIC NONCONFORMING FINITE ELEMENT SCHEME WITH MOVING GRIDS FOR PARABOLIC INTEGRO-DIFFERENTIAL EQUATIONS

A Crank-Nicolson scheme based on nonconforming finite element with moving grids is dis- cussed for a class of parabolic integro-differential equations under anisotropic meshes. The corresponding convergence analysis is presented and the error estimates are obtained by using the interpolation operator instead of the conventional elliptic projection which is an indispensable tool in the convergence analysis of traditional finite element methods in previous literature.