基于状态转移系统的安全协议形式模型

提出一种基于状态转移系统的安全协议模型,以Dolev-Yao攻击者模型为前提假设,以状态转移系统为框架,用语义编码的方式定义消息和事件,用重写关系定义协议规则,用事件的集合来描述协议的安全属性,并给出安全属性的检验策略。该模型能够对安全协议进行精确的形式化描述,且便于实现自动化分析。

基于系统状态转移抽样的含分布式电源配电网可靠性评估

基于系统状态转移抽样法,提出了含高渗透率分布式电源(DG)的配电网序贯蒙特卡洛模拟法可靠性评估方法,可以同时计算系统的发电类和配电类可靠性指标。分别建立了非电源元件和DG的状态模型,考虑了时序变化的风电出力、光伏出力、负荷以及上级电源容量约束。在不同充电策略下,蓄电池荷电状态变化情况采用KiBaM模型模拟。将系统的状态空间集合分为发电系统状态和配电系统状态2个部分,当存在非电源元件处于故障状态时,调用配电系统模拟过程,当所有非电源元件均正常时,则调用发电系统模拟过程。通过算例对比,表明了所提出方法的有效性。该方法能够为含DG的配电网优化规划提供参考。

基于系统短期时序状态转移抽样法的孤岛运行微电网可靠性评估

孤岛运行微电网完全利用自身的分布式电源(DG)和储能装置满足微电网内负荷的供电需求,因此有必要对其进行充裕度可靠性评估。本文针对孤岛运行微电网未来短期可靠性具有时变性,及可靠性评估解析法难以获得故障持续时间信息的问题,提出一种孤岛运行微电网短期可靠性评估的模拟法。首先,提出系统短期时序状态转移抽样法,以获得微电网时序系统状态;再建立考虑控制策略的DG装置出力模型,并计及故障解列、孤岛系统切负荷及静态安全约束的影响进行孤岛运行微电网短期可靠性评估,得到包括负荷点平均停电时间在内的短期可靠性指标值。算例系统的短期可靠性评估结果及分析验证了所提方法的正确性和有效性,具有一定的工程应用价值。

基于Petri网的自主式交通系统映射关系评价

自主式交通系统多维架构映射关系用于评价系统功能、逻辑与物理架构之间数据传输与结构构成的复杂集成关系,传统的映射关系评价方法忽视了系统的开放复杂特点。为此引入状态等级划分和状态转移的概念,以广义随机Petri网作为建模工具,将映射关系模型评价问题转化为系统可靠运行时间问题,并以自动驾驶车辆通过交叉路口场景为例,构建多维架构映射关系,验证了提出的方法的有效性。

N个不同部件并联可修系统的可用度分析

由N个不同部件并联组成系统,各部件失效率分别为(λ1,λ2,…,λn),修复率分别为(μ1,μ2,…,μn)。假定在Δt时间内系统不会同时出现两个以上部件失效,若只有一组维修人员且不能同时修复两个以上失效部件,根据基于马尔可夫过程的系统状态转移图,则共有(n+1)个状态。

不确定规划中非循环可达关系的求解方法

对一个不确定状态转移系统求多个规划问题,那么获得不确定状态转移系统的状态可达关系可以方便求解规划问题,减少冗余计算,建立系统的引导信息。提出一个关于矩阵求不确定领域的状态可达性关系的方法,主要思想是以矩阵乘法来模拟状态转移系统中状态转移,对不确定动作带来的扩散和确定关系带来的聚合进行了统计和处理,从而获得状态可达信息。证明了方法的正确性和有效性。在不确定规划中确定了状态之间的可达性关系,可以在求规划解时删除对规划没有用的状态节点和状态动作序偶;选择能到达目标节点的状态节点和状态动作序偶;进行启发式正向搜索;减少大量冗余计算;提高求解效率。

不确定规划中可达关系的快速求解算法

在不确定规划领域中,通常需要在同一个不确定状态转移系统中解决多个规划问题,如果能得到不确定规划中状态之间的可达关系即可方便求解该规划问题,然而现有矩阵乘法求解可达关系时存在算法复杂度高的问题。为此,设计一种快速求解不确定规划中状态之间可达关系的算法,将确定动作和不确定动作区分处理,先求解所有确定动作的可达关系,再采用链表和队列求解不确定动作的可达关系。实验结果表明,与矩阵乘法相比,该算法能得到更全面的可达关系,且求解效率更高。

A new coordination method for multi-robot system

This paper proposes a new coordination method for multi-robot system.The state space for a multi-robot system is constructed according to the task requirements and system characteristics.Reachable statefor the system is constrained by the system s internal and external constraints,under which the task isexecutable if there exists a state transition trajectory from the initial to the goal state in its state space.Ifthe task is realizable,the feasible or the optimal strategy for task execution could then be investigated inthe state space.Otherwise,the task could be modified to be realizable via adjusting system s configura-tions and/or task constraints,which provides critical guidance for system reconstructions.This con-tributes to the designing and planning of the robotic tasks.Experiments of multi-robot formation movementare conducted to show the validity of the proposed method.

Analysis of Unbalances Forces Using Methods of Identification and Finite Elements

The study of damage in rotating machineries is of fundamental interest in the fields of machine and structure design. A rotating system, supported by bearings and under some dynamic conditions, can generate a variety of problems that are encountered in many different types of rotating machines. One of these problems is the unbalance due to non-homogeneous mass distribution along the shaft. One of the techniques which are widespread today is the identification of parameters and excitation forces that may well followed by monitoring the evolution and change of possible variations of these parameters. Although several methods for the identification of unbalance excitation force are available in the literature, none of them can be considered unrestricted to be applied for all rotating systems. In this study, two methodologies to identify unknown excitations, such as unbalance, have been proposed. This project refers to the analysis of unbalanced forces from displacement parameters and speed by using methods of identification by Fourier series and Legendre polynomials together with the finite element method, state observers in reasons of the problem of absence of signs of rotational displacement, bandpass filter were used to noise suppression of the data collected from the experimental part, Quasi-Newton method to minimize a function in which the bearing stiffness and its damping are unknowns, and also the experimental verification of the methodology, using for this system owned by a rotary mechanical vibrations of the Department of Mechanical Engineering of Faculty of Engineering, campus of llha Solteira.

Generating wind power time series based on its persistence and variation characteristics

Generation of wind power time series is an important foundational task for assisting electric power system planning and mak- ing decision. By analyzing the characteristics of wind power persistence and variation, th!.s paper proposes an improved Mar- kov chain Monte Carlo （MCMC） method, identified as the PV-MC method, for the direct generation of a synthetic series of wind power output. On the basis of the MCMC method, duration time and variation features are concluded in PV-MC method, gaining a more comprehensive reflection of wind power characteristics in the generated wind power time series. First, the wind power state series is generated to meet the state transition matrix based on the definition of the wind power state. Then, the time duration of each state in the series is determined by its respective duration character. Finally, the variation characteristic is used to convert the state series to a wind power time series. A significant amount of simulations are performed based on the PV-MC and MCMC methods and are then compared for 25 wind farms at 6 different locations throughout the world. The sim- ulation results show that the PV-MC method offers an excellent fit for the time domain features （persistence and variation characteristic） while holding other statistic features （mean value, variance, autocorrelation coefficient （ACC） and probability density function （PDF）） close to the MCMC method.

A novel method of periodic orbit computation in circular restricted three-body problem

Periodic orbits are fundamental keys to understand the dynamical system of circular restricted three-body problem, and they play important roles in practical deep-space exploration. Current methods of periodic orbit computation need a high-order analytical approximate solution to start the iteration process, thus making the computation complicated and limiting the types of periodic orbits that can be obtained. By utilizing the symmetry of the restricted three-body problem, a special kind of flow function is constructed, so as to map a state on the plane of symmetry to another state that also lies in this plane. Based on this flow function, a new method of periodic orbit computation is derived. This method needs neither a starting analytic approximation nor the state transition matrix to be computed, so it can be conveniently implemented on a computer. Besides, this method is unaffected by the nonlinearity of the dynamical system, allowing a large set of periodic orbits which have x-z plane symmetry to be computed numerically. As examples, some planar periodic orbits (e.g. Lyapunov orbit) and spatial periodic orbits (e.g. Halo orbit) are computed. By further combining with a differential correction process, the method introduced here can be used to design resonant orbits that can jump between different resonant frequencies. One such resonant orbit is given in this paper, verifying the efficiency of this method.

STATE TRANSFER CONTROL OF QUANTUM SYSTEMS ON THE BLOCH SPHERE

The state transfer under control fields is analyzed based on the Bloch sphere representation of a single qubit. In order to achieve the target from an arbitrary initial state to a target state, the conditions that parameters should satisfy are deduced separately in two different requirements： One is in the case of the rotation angle around the x-axis being fixed and another is in the situation with a given evolution time. Several typical states trajectories are demonstrated by numerical simulations on the Bloch sphere. The relations between parameters and the trajectories are analyzed.