Precise integration method without inverse matrix calculation for structural dynamic equations

The precise integration method proposed for linear time-invariant homogeneous dynamic systems can provide accurate numerical results that approach an exact solution at integration points. However, difficulties arise when the algorithm is used for non-homogeneous dynamic systems due to the inverse matrix calculation required. In this paper, the structural dynamic equalibrium equations are converted into a special form, the inverse matrix calculation is replaced by the Crout decomposition method to solve the dynamic equilibrium equations, and the precise integration method without the inverse matrix calculation is obtained. The new algorithm enhances the present precise integration method by improving both the computational accuracy and efficiency. Two numerical examples are given to demonstrate the validity and efficiency of the proposed algorithm.

General calculation formulas and recurrence relations of radial matrix elements for relativistic n-dimensional hydrogen atom of spin S=0

In this paper, the general calculation formulas of radial matrix elements for relativistic n-dimensional hydrogen atom of spin S=0 are obtained, and the recurrence relation of different power order radial matrix elements are also derived.

Research and application of a power-flow-calculation method in multiterminal VSC-HVDC power grid

For demonstrating a multiterminal voltage-source converter(VSC)-based high-voltage DC(HVDC)(VSCHVDC) project, this study puts forward a technical route for calculating the power flow in a 500-kV VSC-HVDC power grid in comparison with that of an AC power grid. The Jacobian matrix used in the power-flow calculation was deduced through methods such as Newton–Laphson iteration and Taylor series expansion. Further, the operation effect of powerflow calculation on a true bipolar VSC-HVDC power grid was analyzed briefly. The elements of the Jacobian matrix corresponding to VSC were studied under the mode of droop control and the control strategy of VSC-HVDC power grid was analyzed in detail. The power-flow calculation model for VSC-HVDC power grid of the master–slave control mode was simplified using the PQ decomposition method of the power-flow calculation of an AC power grid. Moreover, a four-terminal model of the Zhangbei VSC-HVDC demonstration project was established and tested on MATLAB. The simulation results under two kinds of operating conditions were analyzed and compared to the results of BPA; the deviation between the power-flow results was studied. The results show that the proposed calculation method can provide a feasible support for calculating the power flow in VSC-HVDC grids.

Automatic Calculation of Dimension Chains in AutoCAD

In the course of mechanical part designing, process p lanning and assembling designing, we often have to calculate and analyse a dimen sion chain. Traditionally, a dimension chain is established and calculated m anually. With wide computer application in the field of mechanical design and ma nufacture, people began to use a computer to acquire and calculate a dimension c hain automatically. In reported work, a dimension chain can be established and c alculated automatically. However, dimension text values of dimensions composing a dimension chain and these dimensions’ tolerance’s upper values and lower valu es are put into a computer manually, which is inefficient and easy to make mis takes. In order to overcome above difficulties. it is very important to acquir e noted dimensions automatically, furthermore analyse and calculate a dimens ion chain, then show results. At present AutoCAD softwares of Autodesk company h ave been used popularly in mechanical designing. For automatically acquiring noted dimensions, analyzing and calculating a dimension chain in a design draw in AutoCAD, this paper introduces the solvable scheme of automatic dimension acq uisition and dimension chain calculation in AutoCAD by ObjectARX. ObjectARX is a developing tool for AutoCAD. In this paper a dimension chain is expressed b y three matrixes, which respectively stand for dimension text value matrix, tole rance’s upper value matrix and tolerance’s lower value matrix. The developed p rogram can be used to both calculate a assembling dimension chain, and a process dimension chain. When the program running in AutoCAD, noted dimensions comp osing a dimension chain in AutoCAD are selected in turn with a mouse, then the c omputer begin to calculate the dimension chain and results are shown in a dialog box. A running example is given in this paper.

Unified method for typical gear failure modeling and stiffness calculation based on the matrix equation

The failure types in gear systems vary,with typical ones mainly including pitting,cracking,wear,and broken teeth.Different modeling and stiffness calculation methods have been developed for various gear failure types.A unified method for typical gear failure modeling and stiffness calculation is introduced in this study by considering the deviations in the time-varying meshing stiffness(TVMS)of faulty gears resulting from the use of different methods.Specifically,a gear tooth is discretized into a large number of microelements expressed with a matrix,and unified models of typical gear failures are built by adjusting the values of the matrix microelements.The values and positions of the microelements in the tooth failure model matrix have the same physical meaning as the parameter variables in the potential energy method(PEM),so the matrix-based failure model can be perfectly matched with PEM.Afterward,a unified method for TVMS is established.Modeling of healthy and faulty gears with pitting,wear,crack,and broken tooth is performed with the matrix equation,and the corresponding TVMS values are calculated by incorporating the matrix models with PEM.On the basis of the results,the mechanism of typical fault types that affect TVMS is analyzed,and the conclusions are verified through the finite element method.The developed unified method is a promising technique for studying the dynamic response characteristics of gear systems with different failure types because of its superiority in eliminating stiffness deviations.

Ranking Method for Complementary Judgment Matrixes with Fuzzy Numbers Based on Hausdorff Metric Distance

A method for ranking complementary judgment matrixes with traspezoidal fuzzy numbers based on Hausdorff metric distance and fuzzy compromise decision approach is proposed. With regard to fuzzy number complementary judgment matrixes given by a decider group whose members have various weights, the expert＇s information was aggregated first by means of simple weight average（SWA） method and Bonissone calculational method. Hence a matrix including all the experts＇ preference information was got. Then the matrix＇ column members were added up and the fuzzy evaluation values of the alternatives were got. Lastly, the Hausdorff metric distance and fuzzy compromise decision approach were used to rank the fuzzy evaluation values and then the ranking values of all the alternatives were got. Because exact numbers and triangular fuzzy numbers could all be transformed into trapezoidal fuzzy numbers, the method developed can rank complementary judgment matrixes with trapezoidal fuzzy numbers, triangular fuzzy numbers and exact numbers as well. An illustrative example is also given to verify the developed method and to demonstrate its feasibility and practicality.

建筑智能化系统顶层设计方法探讨

通过自上而下地展开,吸收质量功能配置的思想,对建设过程中影响智能化系统的因素进行统筹考量。通过逐层迭代的方式,直观展示不同技术方案对业主满意度的影响,为建筑设计提供可比较的方案效益评价,也为设计明确后续技术路径。

基于损失特征矩阵的CHB-BESS模块间接地故障诊断

模块间接地故障是H桥级联型电池储能系统(cascaded H bridge based battery energy storage system,CHB-BESS)的易发故障,快速诊断故障位置对减少故障损失至关重要。模块间接地故障的故障特征主要体现在零序电流上,会受到接地过渡电阻的影响。为实现接地过渡电阻不确定情况下,故障模块位置的快速准确鲁棒定位,本工作提出了一种基于损失特征矩阵的快速故障诊断方法。首先,本工作建立了零序等效电路模型;然后,将零序电流模型离散化;接着,提出基于损失特征矩阵的定位方法,该方法使用拓扑矩阵描述故障位置和过渡电阻的遍历信息,基于离散化模型来遍历计算零序电流,将计算结果与测量结果的偏差记录在损失特征矩阵中,通过偏差最优解确定故障位置;其次,本工作证实了故障定位问题作为最优化问题具有最优解唯一性,偏差最优解在接地过渡电阻不确定的情况下可获得准确的故障发生位置;最终,基于最优解唯一性提出了最优化计算的加速方法。实测表明,所提方法的平均定位误差仅为0.2个子模块,在接地过渡电阻较大范围不确定的情况下实现了准确定位,并且所提加速方法显著提高诊断速度。

不同饱和度下膨胀土原位孔内剪切试验及强度响应特征

膨胀土强度随饱和度变化显著,非饱和膨胀土的抗剪强度一直是研究膨胀土工程问题的关键。选取南阳市某高速路沿线边坡膨胀土为研究对象,进行了天然条件下处于不同饱和度状态的膨胀土原位孔内剪切试验,获得了自然条件下膨胀土的抗剪强度随饱和度的变化特征。膨胀土的抗剪强度、黏聚力、内摩擦角随着膨胀土饱和度的增大而逐渐减小。结合现场试验数据和土-水特征曲线,提出了以法向应力、饱和度为变量和以法向应力、基质吸力为变量的两种非饱和膨胀土的抗剪强度计算模型,并结合试验数据对计算模型的适用性进行了验证。与之前常用的非饱和土抗剪强度计算模型相比较,提出的两种计算模型所需的拟合参数少,适用于更宽吸力范围、不同法向应力条件下非饱和膨胀土抗剪强度的计算,且结果更为准确。

基于VPP碳流计算的多目标多时间尺度优化调度

为研究虚拟电厂低碳经济运行策略,以虚拟电厂能流和碳流模型为基础,执行了多目标多时间尺度优化调度。首先,基于碳流走向建立虚拟电厂低碳经济运行的非线性多目标规划模型,并采用归一化法向约束法进行求解。然后,建立了基于动态矩阵控制算法的有限时域优化模型,对日前结果进行跟踪优化和反馈校正,以降低不确定性因素的影响。最后,仿真对比实验验证了所提调度策略能在保证碳流计算精度超过95%的前提下实现虚拟电厂低碳经济运行。

适用于含新能源交流电网继电保护整定计算的故障计算方法研究

基于阻抗矩阵的故障计算方法以其计算量小、适用于局部求解等特性,在交流电网继电保护整定计算中得到了广泛应用。新能源的大范围接入改变了整定计算中故障计算的局部性特征,增加了故障计算所需内存、降低了故障计算效率。针对这一问题,该文基于含新能源的故障计算公式,根据新能源对故障节点的影响因素,提出了适用于含新能源交流电网继电保护整定计算的故障计算方法。首先,从网络结构方面,筛选对故障电气量具有强影响的新能源,构建初始计算域;其次,从新能源输出方面对初始计算域进一步增补和修正;最后,经过逐层外扩,形成最终计算域。在保证工程所需计算精度的同时,降低了矩阵元素使用率,减少了故障计算的计算量,提高了计算效率。在IEEE39节点、IEEE118节点系统中验证了该方法的准确度和计算效率。

基于瞬态拼接裂变矩阵的耦合型中子动力学算法研发

在核反应系统的瞬态计算中,通常使用的确定论方法和蒙特卡罗方法不能同时兼备计算精度与计算效率,其中点堆动力学方法无法得到空间上的分布,扩散方法计算速度快但误差较大,输运方法和蒙特卡罗方法虽然精度高但计算效率低。本文在瞬态裂变矩阵和拼接裂变矩阵理论的基础上,提出了瞬态拼接裂变矩阵方法,该方法可精确快速地进行瞬态分析。其中,瞬态裂变矩阵方法是一种可进行输运计算的混合方法,但需大量的计算时间用于生成瞬态裂变矩阵。拼接裂变矩阵方法是一种可高效处理裂变矩阵数据库以及快速计算全堆芯稳态的方法,但未运用于瞬态分析中。本文通过单棒模型以及组件模型的瞬态工况对瞬态拼接裂变矩阵方法进行验证。结果表明,瞬态拼接裂变矩阵方法在稳态和瞬态计算过程与参考解吻合良好,能在61 cup·h时间完成真实时间0.5 s的插棒-提棒的瞬态三维精确解,均方根误差在整个插棒-提棒的瞬态过程中均保持在0.2%以下。

基于改进矩量法的风电机无源干扰快速计算

准确快速计算风电机的散射电场,是解决风电机无源干扰的基本前提。采用传统矩量法求解电大尺寸风电机散射电场时,需要极为庞大的计算资源导致难以求解。为此,考虑风电机工作时叶片的周期对称性以及风电机叶片大曲率、复杂的异形曲面,改进了传统矩量法中求解风电机无源干扰的面元剖分方法,引入基于曲面三角面元的矩量法基函数,并且利用叶片结构的对称性简化阻抗矩阵填充过程,准确快速计算出了风电机表面感应电流产生的散射电场,实现了风电机无源干扰的快速计算。为验证所提方法的正确性及有效性,开展了基于电波暗室风电机缩比模型实验,结果表明,该方法计算的结果与实验测量结果较为一致。以实际金风GW82/1500型风电机为例,将所提方法计算的不同方位角下风电机叶片无源干扰水平与传统矩量法相比,表明该方法与其吻合良好,所提方法矩阵元素计算内存减少了34.64倍,矩阵元素求解效率提高了37.95倍。为后续广域空间下风电场中大规模风电机阵列动态电磁散射理论研究奠定了理论与技术基础。

Analytical Calculation Method of Reliability Sensitivity Indexes for Distribution Systems Based on Fault Incidence Matrix

An analytical calculation method for the reliability sensitivity indexes of distribution systems is proposed to explicitly quantify the impact of various influence factors on system reliability.Firstly,the analytical calculation formulas for the reliability indexes of distribution systems are derived based on the fault incidence matrix(FIM).Secondly,the factors that affect system reliability are divided into two categories:quantifiable parameter factors and non-quantifiable network structure factors.The sensitivity indexes for the quantifiable parameter factors are derived using the direct partial derivation of the reliability calculation formulas.The sensitivity indexes for the nonquantifiable network structure factors are derived using the transformation of FIMs.Finally,the accuracy and efficiency of the proposed sensitivity calculation method are verified by applying them to an IEEE 6-bus RBTS system.This paper sums up the factors that influence system reliability in detail and gives the explicit analytical calculation method for the sensitivity of each factor.Repetitive calculation of the reliability index can be avoided during the sensitivity analysis.The bottleneck that affects the reliability level of distribution systems can be identified efficiently,and valuable information and guidance can be provided to enhance the reliability of distribution systems.

基于人工边界条件的波面相位解析重建

At present,the measurement of the near wave field of ships mostly relies on shipborne radar.The commonly used shipborne radar is incoherent and cannot obtain information on wave surface velocity.Therefore,the mathematical model of wave reconstruction is remarkably complex.As a new type of radar,coherent radar can obtain the radial velocity of the wave surface.Most wave surface reconstruction methods that use wave velocity are currently based on velocity potential.The difficulty of these methods lies in determining the initial value of the velocity integral.This paper proposes a wave surface reconstruction method based on an artificial boundary matrix.Numerical simulation data of regular and short-crest waves are used to verify the accuracy of this method.Simultaneously,the reconstruction stability under different wave velocity measurement errors is analyzed.The calculation results show that the proposed method can effectively realize the reconstruction of wave field.

基于分布式监测的历史建筑结构整体变形计算方法研究

随着监测技术的发展,传统二维图表已难以满足日益增长的结构安全监测需求。互联网与计算机三维可视化技术,使监测数据呈现出以多维度、更加真实与实时的形式进行展现的发展趋势。在此过程中,利用分布式监测进行结构整体变形计算,成为监测数据多维展示的关键。在结构力学柔度矩阵的基础上,提出广义柔度矩阵,建立了基于广义柔度矩阵的结构整体变形计算方法,并在上海音乐厅观众厅穹顶木屋架监测中进行了应用。该方法可为后续结构安全监测数据的三维可视化提供技术支撑。

非线性干扰下雷电灾害易损性风险区划方法优化设计

雷电灾害易损性风险等级具有模糊性和非线性,现有方法未对其进行充分考虑,导致权重设置存在明显缺陷,影响精准区划。为此,提出非线性干扰下雷电灾害易损性风险区划方法优化设计。针对以往检测数据,计算年平均雷击大地密度,分析雷电活动分布特征,以克服雷电灾害易损性风险等级的模糊性。构建易损性风险指标,将各指标及年平均雷击大地密度为输入构建雷电灾害易损性风险预测函数。为确保区划的准确性,采用自适应粒子群优化算法对指标风险因子权重进行粒子寻优,克服非线性影响,确定等级划分权重,实现等级风险区划。结果表明,所提方法区划结果与实际结果一致,且权重自适应性效果较佳,等错误率整体平均约为0.768%,区划准确性较高,具有可行性。

基于WBS-RBS与AHP的W项目产品交付进度风险计算

“十四五”以来,国家陆续出台了系列政策文件,对抽水蓄能行业发展加强指导和支持,行业迎来前所未有的发展高潮。在工程建设期间,设备按期交付是业主与制造商关心的重要事宜,抽水蓄能项目集合了新技术、高投资、政治社会效应重大等多项特点,尤应重视项目执行过程中的风险管理。本文通过WBS-RBS风险识别与AHP层次分析法相结合,对A公司W抽水蓄能项目预埋产品交付进度风险度进行了量化评估,既有助于提高项目决策的合理化、科学化,提升管理效率和效益;同时,也是对抽水蓄能产品交付进度风险量化管理新途径的有益探索。

电厂热力系统矩阵分析法的改进

在分析电厂热力系统热平衡串联解法特点的基础上，给出了完整的矩阵表达的热平衡方程式，并指出其中各项与系统结构的对应关系。把电厂热力系统视为与辅助汽水系统的叠加，这种叠加在数学上表现为热平衡矩阵式中的各矩阵项之和。

继电保护整定计算中故障计算模型的选择与比较分析

计及运行方式变化的故障计算的快速实现是提高继电保护整定计算工作效率的关键。根据整定计算中故障计算的特点,基于节点阻抗矩阵,提出了计及运行方式变化的大批量故障快速计算的实现方法,通过涉及节点集的合理选取和阻抗矩阵的分级存贮,实现阻抗矩阵的最小修改,从而达到故障计算的快速及实用性要求。并从时间复杂度的角度分析和比较了基于节点导纳矩阵和节点阻抗矩阵的故障计算在整定计算中应用的差异。