Realization of the Linear Tree that Corresponds to a Fundamental Loop Matrix

Graph realization from a matrix is an important topic in network topology. This paper presents an algorithm for the realization of a linear tree based on the study of the properties of the number of the single-link loops that are incident to each tree branch in the fundamental loop matrix Bf. The proposed method judges the pendent properties of the tree branches, determines their order one by one and then achieves the realization of the linear tree. The graph that corresponds to Bf is eventually constructed by adding links to the obtained linear tree. The proposed method can be extended for the realization of a general tree.

New Matrix Loop Algebra and Its Application

A new matrix Lie algebra and its corresponding Loop algebra are constructed firstly,as its application,the multi-component TC equation hierarchy is obtained,then by use of trace identity the Hamiltonian structure of the above system is presented.Finally,the integrable couplings of the obtained system is worked out by the expanding matrix Loop algebra.

A Rework Reduction Mechanism in Complex Projects Using Design Structure Matrix Clustering Methods

To reduce the uncertainty and reworks in complex projects,a novel mechanism is systematically developed in this paper based on two classical design structure matrix(DSM)clustering methods:Loop searching method(LSM)and function searching method(FSM).Specifically,the optimal working areas for the two clustering methods are first obtained quantitatively in terms of non-zero fraction(NZF)and singular value modularity index(SMI),in which the whole working area is divided into six sub-zones.Then,a judgement procedure is proposed for conveniently choosing the optimal DSM clustering method,which makes it easy to determine which DSM clustering method performs better for a given case.Subsequently,a conceptual model is constructed to assist project managers in effectively analyzing the network of projects and greatly reducing reworks in complex projects by defining preventive actions.Finally,the aircraft design process is presented to show how the proposed judgement mechanism can be utilized to reduce the reworks in actual projects.

THE ANALYSIS METHOD OF THE SETS OF BRANCHES BASED ON INDEPENDENT LOOPS IN THE ELECTRIC NETWORK

The matrix D describing relations of the loops to the nodes in the graph and also the setsof branches based on the independent loops and their matrix Q are defined.The theorem in whichthe product of the loop-node matrix D multiplied by the incidence matrix Aa is equal to matrix Qis put forward and proved.The admittance matrix Ylc of the sets of the branches is defined and it isassumed that the vector Vlc of voltage of the sets of branches to be a calculative quantity.The equa-tion of the sets of branches is derived and the analysis method of the sets of branches based on theindependent loops in the electric network is presented.

蛋白质loop区域闭合数值方法分析与比较

针对蛋白质loop区域的闭合问题,比较分析了两种来源于机器人学的数值方法——循环坐标下降法(CCD)和雅可比矩阵方法,进行了实现并设计实验。在计算时间和闭合效率方面循环坐标下降法要明显优于雅可比矩阵方法,而雅可比矩阵方法则可以较平均地改变每一个二面角值。

弱电网下并网变流器相位裕度的分频段补偿方法

在弱电网条件下,针对并网变流器各控制环节与电网阻抗之间交互作用,容易引发系统振荡而造成失稳问题,文中提出一种分频段相位补偿控制策略。首先,建立dq坐标下的并网变流器输出导纳矩阵模型,针对在低频段由锁相环引起的变流器输出导纳的负阻尼特性,不改变锁相环动态特性而通过分析锁相环对控制系统的影响路径,加入含积分元素的补偿矩阵抵消锁相环的负阻尼影响,同时简化导纳模型;进而,引入仅含常数元素的补偿矩阵实现超前校正,对电流环带宽外的负阻尼进行相位补偿,使导纳矩阵元素在全频段为正实部,为并网控制系统提供正阻尼,从而增强并网变流器的稳定性。最后,通过仿真和实验在不同短路比条件下对文中提出的补偿方案进行验证,证明所提方案的有效性。

An Upper Bound on the Higgs Self-Coupling and Higgs Boson Mass from the Positivity Condition of the Mass Matrix

The actual value of Higgs boson mass is difficult to determine theoretically due to lack of knowledge on the exact value of Higgs self coupling constant l. The purpose of this paper is to obtain an upper bound on the Higgs mass in the Standard Model on the basis of one-loop effective potential in the ’t Hooft-Landau gauge and MS scheme. The condition of positivity of mass matrix at ф?= ф0 (where ф0 is the absolute minimum of the effective potential) of the scalar field gives an upper bound on the Higgs self coupling as l ≤ 0.881. This condition yields an upper bound on the Higgs mass as mH ≤ 229.48 GeV.

Nonlinear instability suppression of closed-loop pilot-vehicle system with rate-limiting actuator based on anti-windup compensation

To solve the flight safety problem caused by nonlinear instabilities（category II pilot induced oscillations, PIOs） of the closed-loop pilot-vehicle system with rate-limiting actuator, the antiwindup（AW） compensation method to avoid category II PIOs is investigated. Firstly, the AW compensation method originally used for controlling input magnitude limited system is introduced, then this method is extended for controlling input rate-limiting system through a circle criterion theorem. Secondly, the establishment of the AW compensator is transformed into the solving of linear matrix inequalities. Finally, an AW compensator establishment algorithm for the closed-loop pilot-vehicle system with the rate-limiting actuator is obtained. The effectiveness of the AW compensation method to avoid category II PIOs is validated by time-domain simulations,and compared with rate-limited feedback（RLF） command rate compensation method. The results show that the AW compensation method can effectively suppress category II PIOs and maintain the nominal performance when the closed-loop pilot-vehicle system is normal. Unlike the command rate compensator which works upon system uninterruptedly, the AW compensation method affects the closed-loop pilot-vehicle system only when the rate-limiting of actuator is activated, so it is a novel PIO avoidance method.

Subsystem model-based close-loop grey-box identification method for hydraulic stewart platform

In order to solve the problem of difficult modeling and identification caused by time-variable parameters,multiple inputs and outputs and unstable open loop,a subsystem model-based close-loop grey-box identification method was put forward when consider the main coupling effects of hydraulic Stewart platform.Firstly,the whole system is divided into three TITO(Two Input Two Output) subsystems according to the characteristics of the pseudo-mass matrix,hence transfer function matrix model of the subsystem can also be found.Secondly,since the Stewart platform is unstable,the close-loop transfer model of the subsystem is derived under the proportional controllers.The inverse M serial is adopted as the identification signal to get the experimental data.All parameters of the subsystem are determined in close-loop indirect identification by PEM(Prediction Error Method).Finally,a case study validates the correctness and effectiveness of the subsystem model-based close-loop grey-box identification method for hydraulic Stewart platform.

有源电力滤波器补偿的PI解耦控制技术研究

电网中电压和电流波形的失真会产生谐波,导致电网功率因数降低,并影响电力系统的稳定性和可靠性。为了确保电力系统的正常工作,研究了基于有源电力滤波器补偿的比例积分(PI)解耦控制技术。设计了基于二极管钳位式的有源电力滤波器模型。结合基尔霍博电压法,降低控制谐波和解除部分变量耦合。针对设备非线性产生的谐波,分析有源电力滤波器的可逆性,获得输入雅可比矩阵,以实现滤波器旋转坐标的线性化。利用变换矩阵转换转动角速向量,输入谐波的幅度,输出电流取样延迟,完成无差PI解耦控制。试验结果表明,所提技术能够有效解耦滤波器的谐波电流成分,从而补偿电网中的失真电流。该技术可以减少谐波对电力系统的整体影响,保证设备的正常运行。

基于电压矩阵的跟网变流器无锁相环控制的本质特征与提升策略

弱电网下跟网变流器由于锁相环引起的负阻特性容易造成振荡现象。针对锁相环的提升策略已有较多研究,其中,基于电压矩阵的同步控制策略因其不存在锁相环受到广泛关注,但关于其稳定性缺乏严格的理论证明。文中分析表明,基于电压矩阵的无锁相环控制策略本质上是基于并网点电压反正切计算的开环定向方式,虽然去除锁相环但不能提高稳定性。因为该策略并没有降低电压扰动给电流控制带来的负阻特性,所以如何降低并网点电压扰动对于电流控制的影响是提升弱电网下跟网变流器稳定性的关键。因此,提出自适应带通滤波器来降低同步环节的带宽,从而提升跟网变流器在弱电网下的稳定性。最后,通过阻抗模型和实验结果验证了理论分析的正确性和所提策略的有效性。

回差矩阵奇异值方法改进和MIMO系统稳定性分析

高速防空导弹大攻角飞行时,耦合现象严重,弹体的高动态响应特征进一步加剧通道耦合,因此研究通道耦合下的系统稳定性至关重要。本文提出一种双通道控制模式下,单通道断开、耦合通道视为内回路的传递函数矩阵,并引入回差阵奇异值法计算系统稳定裕度。通过仿真将传统奇异值法和基于传递函数矩阵的奇异值改进法计算出的稳定裕度、单通道稳定裕度、双通道断开的稳定裕度和基于通道耦合下的稳定裕度,结合系统的时域响应进行对比分析。结果表明,改进回差阵奇异值法计算结果更精确,通道耦合下的开环传递函数对系统稳定性描述更合理。

隔离型双向AC-DC矩阵变换器闭环控制方法研究

根据隔离型双向AC-DC矩阵变换器(Isolated AC-DC Matrix Converter,IAMC)没有中间电容缓冲环节,输入和输出变换器控制之间存在耦合,研究提出了IAMC两级功率变换器的控制方法。通过对全桥变换器进行闭环控制进而实现对直流侧输出电流和功率的直接控制;三相-单相矩阵变换器实现对有功和无功功率的独立控制,以满足网侧功率因数的高精度控制。所提控制策略有效降低了两级变换器的耦合强度,保证了系统的良好性能。在MATLAB中进行仿真,结果表明,所提出的控制方法在使系统电能质量得到提高的同时,可以实现单位功率因数可调,验证了所提控制策略的正确性和有效性。

基于关联矩阵标记法与回路矩阵的电网拓扑分析

针对电力系统对网络拓扑分析实时性与准确性的需求,提出一种基于关联矩阵标记法和回路矩阵的网络拓扑分析新方法。在系统正常运行情况下,利用关联矩阵标记法,判断图的连通性,同时标记网络的树支与连支,完成电网静态电气岛分析;当网络结构发生变化后,借助回路矩阵,判断变化支路的属性。在此基础上,利用破圈法和半径搜索法,修改局部网络拓扑及更新回路矩阵。IEEE 39节点和IEEE 118节点系统验证结果均表明该方法计算量小,更新速度快,可适用于多种网络变结构的情况。

钢丝绳传动机器人运动学的回路分析方法

研究分析了一类2N条钢丝绳驱动N个自由度机器人的运动学,其运动学分析可通过推导除去钢丝绳后的开环链机器人关节角位移与末端执行器之间的运动学模型和关节角位移与电机转子角位移之间的运动学模型两个步骤完成。在运动学分析的基础上,提出了用回路矩阵和等效半径矩阵描述钢丝绳传动机器人运动学的回路分析方法。根据钢丝绳传动原理,通过观察法可直接列写回路矩阵和电机驱动空间等效半径矩阵,从而得到电机转子角位移与关节角位移之间的映射关系模型,解耦了由于钢丝绳传动导致机器人关节之间的运动耦合。实现了电机驱动空间、关节空间和笛卡尔空间之间完整的运动学映射,加快和简化了钢丝绳传动机器人运动学的建模和分析过程。最后,以Utah/MIT手指为例进行了运动学分析,比较Matlab运算和Solidworks Motion仿真的末端运动轨迹,验证了回路分析方法的正确性。

基于化整为零策略和改进二进制差分进化算法的配电网重构

为缩减编码长度,提高计算效率,提出了基于化整为零策略和改进二进制差分进化算法的配电网重构方法。将开关根据其在环路中的位置进行分类,建立了环路–开关关联矩阵。应用化整为零策略将整个解空间划分成若干个子解空间,应用改进二进制差分进化算法直接对各子解空间进行并行搜索,比较所有子解空间的搜索结果即可找到重构问题的最优解。该方法缩短了开关方案的编码长度,改进二进制差分进化算法通过调整变异、交叉操作规则,避免了不可行解的产生。接入分布式电源的配电网仿真算例验证了该方法的有效性。

压水堆核电机组二回路热力系统矩阵分析法

基于各级加热器的热平衡方程,通过严密的数学推导,提出了基于矩阵的压水堆核电机组二回路热力系统的定功率方程式。对该矩阵的填写规则进行了详细阐述,指出了各矩阵的物理意义,该方程式全面考虑了二回路热力系统的结构特点以及辅助汽水系统,在定功率条件下,可以一次性求出汽耗量和各级抽汽量,通用性强,在应用时、具有简洁、准确和快速的特点。通过对某900MW机组进行算例分析,验证了该方程的准确性。

一个计算独立回路矩阵元素的新公式

本文从场论说给出了非线性网络中独立回路方程组形式，并将其改写成网孔方程组，求此方程组的解答，得到一个从非线性网络到线性网络的可按网孔行列式来计算独立回路矩阵元素的理论公式文中最后以实例验证了该公式的正确性.

搜索建筑平面图房间的算法及应用

首先介绍了利用边与边之间的邻接拓扑关系构造邻接矩阵的方法 ,并提出了一种搜索建筑平面图房间的算法 ,可以快速准确地确定平面图内的房间、墙线与顶点的拓扑关系 ,同时 。

基于环路矩阵分块重组策略的配电网重构

如何有效减少配电网重构中不可行解的产生是提高搜索速度的重要环节。为提高搜索效率,在对网络进行拓扑简化的基础上,提出一种基于环路矩阵分块重组策略的配电网重构预处理方法,实现了解空间压缩与分解。结合该策略,以布谷鸟搜索算法及其改进算法为例对IEEE33节点系统和119节点系统进行了算例仿真,结果表明结合环路矩阵分块重组策略后能够有效避免不可行解的产生,算法只在少数可行范围内进行搜索,搜索范围减少,计算速度与寻优成功率显著提高,验证了提出策略的有效性;最后将此策略运用于多种智能算法,对比结果表明该策略能使算法在性能上得到显著提升,验证了所提策略的适用性。