Introduction to Mesh Based Generated Lumped Parameter Models for Electromagnetic Problems using Triangular Elements

This paper is an introduction to mesh based generated reluctance network modeling using triangular elements.Many contributions on mesh based generated reluctance networks using rectangular shaped elements have been published,but very few on those generated from a mesh using triangular elements.The use of triangular elements is aimed at extending the application of the approach to any shape of modeled devices.Basic concepts of the approach are presented in the case of electromagnetic devices.The procedure for coding the approach in the case of a flat linear permanent magnet machine is presented.Codes developed under MATLAB environment are also included.

A Finite Volume Method with Unstructured Triangular Grids for Numerical Modeling of Tidal Current

The finite volume method （FVM） has many advantages in 2-D shallow water numerical simulation. In this study, the finite volume method is used with unstructured triangular grids to simulate the tidal currents. The Roe scheme is applied in the calculation of the intercell numerical flux, and the MUSCL method is introduced to improve its accuracy. The time integral is a two-step scheme of forecast and revision. For the verification of the present method, the Stoker＇s problem is calculated and the result is compared with the mathematically analytic solutions. The comparison indicates that the method is feasible. A sea area of a port is used as an example to test the method established here. The result shows that the present computational method is satisfactory, and it could be applied to the engineering fields.

Critical behaviour of the ferromagnetic Ising model on a triangular lattice

We use a new updated algorithm scheme to investigate the critical behaviour of the two-dimensional ferromagnetic Ising model on a triangular lattice with the nearest neighbour interactions. The transition is examined by generating accurate data for lattices with L=8, 10, 12, 15, 20, 25, 30, 40 and 50. The updated spin algorithm we employ has the advantages of both a Metropolis algorithm and a single-update method. Our study indicates that the transition is continuous at Тc=3.6403（2）. A convincing finite-size scaling analysis of the model yields ν=0.9995（21）, β/ν=0.12400（17）, γ/v=1.75223（22）, γ^1/ν=1.7555（22）, α/ν=0.00077（420） （scaling） and α/ν=0.0010（42） （hyperscaling）. The present scheme yields more accurate estimates for all the critical exponents than the Monte Carlo method, and our estimates are shown to be in excellent agreement with their predicted values.

An improved model of damage depth of shock-melted metal in microspall under triangular wave loading

Damage depth is an important dynamic parameter for describing the degree of material damage and is also a key fundamental issue in the field of impact compression technology.The present work is dedicated to the damage depth of shock-melted metal in microspall under triangular wave loading,and an improved model of damage depth considering the material's compressibility and relative movement is proposed.The damage depth obtained from the proposed model is in good agreement with the laser-driven shock loading experiment.Compared with the previous model,the proposed model can predict the damage depth of shock-melted metal in microspall more accurately.Furthermore,two-groups of the smoothed particle hydrodynamics(SPH)simulations are carried out to investigate the effects of peak stress and decay length of the incident triangular wave on the damage depth,respectively.As the decay length increases,the damage depth increases linearly.As the peak stress increases,the damage depth increases nonlinearly,and the increase in damage depth gradually slows down.The results of the SPH simulations adequately reproduce the results of the proposed model in terms of the damage depth.Finally,it is found that the threshold stress criterion can reflect the macroscopic characteristics of microspall of melted metal.

Method of triangular mesh modeling in numerical control machining simulation

In the process of numerical control machining simulation,the workpiece surface is usually described with the uniform triangular mesh model.To alleviate the contradiction between the simulation speed and accuracy in this model,two improved methods,i.e.,the local refinement triangular mesh modeling method and the adaptive triangular mesh modeling method were presented.The simulation results show that when the final shape of the workpiece is known and its mathematic representation is simple,the local refinement triangular mesh modeling method is preferred;when the final shape of the workpiece is unknown and its mathematic description is complicated,the adaptive triangular mesh modeling method is more suitable.The experimental results show that both methods are more targeted and practical and can meet the requirements of real-time and precision in simulation.

An Evaluation Model of Graduation Thesis Results Based on Triangular Fuzzy Number

The evaluation of thesis by undergraduate has the characteristics of multi-factor, multi-layer and easy to be affected by subjective factors. To reduce the subjectivity, triangular fuzzy number is used as index set to give weight, and on this basis, fuzzy comprehensive evaluation is used to evaluate the quality of graduation thesis. The empirical analysis shows that the combination of triangular fuzzy number and fuzzy comprehensive evaluation has certain practical value in the quality evaluation of graduation thesis.

砖木结构古建筑火灾风险影响因子评估研究

提出模糊DEMATEL-ISM的方法,在建立古建筑火灾评价指标体系的基础上,对归属于4大类风险因素的25个潜在风险因子进行关联性分析,得出因子的因果属性及因子间的逻辑层次结构关系,从而对古建筑火灾风险进行评估。利用模糊DEMATEL-ISM法对华阴市西岳庙灏灵殿进行实例分析,结果表明:疏散与扑救条件、电器设备隐患的原因度较大,需要对其予以控制;耐火等级、火灾荷载的结果度大,为事故发生的主要原因;疏散与扑救条件、易燃易爆危险品、电器设备隐患、安全责任制、灭火应急预案和演练为古建筑火灾事故的关键风险因子,可为古建筑火灾风险管控工作提供相应参考。

基于组合赋权云模型的塔台管制系统运行安全评估

随着我国民航业的迅猛发展,空中交通流量不断攀升,机场塔台管制系统的运行安全面临严峻考验,因此,正确识别和评估风险成为有效提高塔台管制系统运行安全水平的重要前提。为精准且有效地完成对塔台管制系统运行的安全评估,构建了基于模糊决策实验室分析法(Decision-Making Trial and Evaluation Laboratory,DEMATEL)网络层次分析法(Analytic Network Process,ANP)熵权法云模型的塔台管制系统运行安全评估模型。首先,通过流程图法并结合人机环管的思想建立塔台管制系统运行安全评估指标体系,并采用模糊DEMATEL法确定评估指标间的相互影响关系,绘制评估指标之间的网络结构图;然后,通过ANP法确定各评估指标的主观权重,采用熵权法确定各评估指标的客观权重,并通过博弈论方法计算评估指标的综合权重;最后,将权重结果与评语层云模型结合使用对各级安全评估指标进行安全评估,通过MATLAB软件完成算例的仿真分析。结果表明:该塔台管制系统运行安全等级在一般和良好之间,仍需采取有效措施对某些风险因素进行控制;同时验证了该模型在塔台管制系统运行安全评估中具有可行性和准确性,对塔台管制系统安全评估具有指导意义。

基于TFN-AHP和云模型的母舰对气垫船保障能力评价

母舰对气垫船的保障能力是气垫船任务执行能力的重要组成部分,对母舰的保障能力进行综合评价是提升气垫船与母舰保障适配能力的重要环节。母舰对气垫船的保障活动具有高度的随机性、复杂性和动态性,导致其保障能力的评价也存在不确定性和模糊性。为此,基于三角模糊数(triangular fuzzy number,TFN)-层次分析法(analytic hierarchy process,AHP)与云模型提出了一种新的母舰对气垫船保障能力评价方法,并对某型母舰对气垫船的保障能力进行了评价。该方法通过特定的结构算法完成定性概念与定量表示的相互结合,降低了保障能力评价中权重计算的主观性和随机性,为母舰对气垫船保障能力评价提供了借鉴。

基于改进AHP及云模型的水轮机调节系统状态评价

针对水轮机调节系统综合评价不够全面,无法综合反映系统多指标、多层次的复杂性问题,提出了基于模糊层次分析法(AHP)-决策与实验室评估法(DEMATEL)-云模型的水轮机调节系统综合评价模型。首先建立基于主要设备和相关工况的多层次指标体系,采用模糊AHP计算评价指标的初始权重;通过DEMATEL法计算评价指标的相互影响与参照关系,绘制出指标因果关系图,并结合初始权重计算评价指标的综合权重;引入云模型得到评价指标各等级的隶属度矩阵。最后将权重结果与隶属度结合,得到系统综合评价等级。算例分析表明,该方法可高效快捷地对水轮机调节系统运行状态进行客观评价,为状态检修提供参考依据。

基于改进DEMATEL-ISM的钢桁梁桥施工风险影响因素研究

为提高钢桁梁桥施工过程中的安全管理,对钢桁梁桥施工中的风险因素进行分析,提出了一种基于改进DEMATEL-ISM的评价方法,首先引入三角模糊数对DEMATEL法中的直接影响矩阵进行改进,从而去模糊化以减少专家评价的主观性,再通过DEMATEL法分析各影响因素的影响度、被影响度、中心度与原因度并加以排序,对得到的主要影响因素进行初步分析,利用ISM法对筛选出的影响因素进行层次划分,得到直接层影响因素、过渡层影响因素与本质影响因素,并针对分析得到的5个本质影响因素提出深入的预防预警措施,可为钢桁梁桥施工方向的安全管理提供针对性措施,为事故预防提供一定的参考依据。

中国县域新型城镇化水平的空间分布特征与驱动因子分析

从经济、人口、社会3个维度构建县域新型城镇化发展水平的综合评价指标体系,基于2020年1593个县(市)的截面数据,运用熵值法测算县域新型城镇化水平,并通过探索性数据分析法和三角模型分析其空间分布特征和三维关系模式,最后运用地理探测器对新型城镇化的驱动因子进行分析,研究结果发现,我国县域新型城镇化呈现东高西低的分布特征,并且存在正的空间相关性;东部地区的县域经济城镇化、人口城镇化和社会城镇化处于较为协调的发展状态,中、西部地区县域经济城镇化水平滞后于人口城镇化和社会城镇化;居民储蓄余额、工业企业个数、固定电话用户数和普通中学学生数是县域新型城镇化发展的主要驱动因子,并且任意两个驱动因子交互作用的影响大于单个因子。基于此,提出应通过完善基础设施体系、增加教育资源供给、推动工业优化升级等措施带动县域新型城镇化发展。

西北农牧交错区土地可持续利用评价及障碍因子诊断——以吴忠市为例

为探究西北农牧交错区土地可持续利用水平,结合联合国可持续发展目标(SDGs)完善传统评价体系,从经济、社会和资源环境3个维度选取30个指标构建评价体系,采用综合指数法、三角模型、障碍度模型分析吴忠市土地可持续利用水平及障碍因子。结果表明,2006—2021年吴忠市土地利用可持续利用水平从不可持续提升到一般可持续;2006—2021年吴忠市土地利用稳定性较好,可持续利用变化趋势稳定,仅2020年稳定性较差;不同土地可持续利用水平下障碍因子不相同。吴忠市土地利用朝着健康的方向发展,现阶段草地覆盖率、农业从业人员比重等是影响吴忠市土地可持续利用主要障碍因子。

面向机械零件三角网格模型自动配准中增强特征的分割方法

三角网格模型配准是工业自动化检测软件中的重要一环,其配准精度对检测机械零件的形位公差有重要影响。针对三角网格模型的自动配准精度低、鲁棒性差的问题,本文提出一种面向机械零件三角网格模型自动配准中增强特征的分割方法。首先,确定三角网格模型特征分割的K值,通过拉普拉斯矩阵确定种子点进行迭代初始化。其次,本文采用合适的区域形状代理和代价函数以加速该过程,并通过多源迭代聚类得到特征分割结果。最终,在三角网格模型特征分割结果的基础上进行基于奇异值分解法的粗配准,之后再根据EM-ICP进行精配准。与传统的特征描述子粗配准结合ICP精配准的方法进行对比,结果表明,本文方法的配准误差下降了25.2%,自动配准时间缩短了62.6%,有效地提高了三角网格模型自动配准的精度和效率。

Flux phases in the extended Hubbard model on the triangular lattice

Using the unrestricted Hartree-Fock variational method,we study the extended Hubbard model in the triangular lattice at 3/4 filling.Due to the nesting instability of the Fermi surface,various density wave states compatible with the 2×2 supercell are found as the ground state by tuning the onsite and nearest neighbor repulsions U and V.Surprisingly,the flux phases with complex bond order parameters are realized in a wide range of the U-V phase diagram.They also acquire nontrivial topological properties due to the spontaneous breaking of the time-reversal symmetry.Our study suggests that the flux phases can be stabilized by the interplay between short-range repulsive interactions in correlated electron systems.

基于兴趣点的上海五个新城设施空间结构研究

本文基于高德地图兴趣点(POI)数据,将其分为生活、生产、公共3类设施,采用核密度估计法、Ripley’s K函数等空间分析方法,并设计了一个反映设施类型结构在空间中演化的三角轨迹模型,以上海主城区为参考,基于不同类型设施的数量、分布和聚集程度,分析了上海五个新城的设施空间结构特征和分布规律,探讨了五个新城进一步建设的方向。研究发现:与上海主城区相比,五个新城的设施空间分布特征差异明显,发展历史较长的新城已经出现明显的单中心空间结构,而发展历史较短的新城表现为微弱的多中心结构;从设施高密度圈层到低密度圈层,主城区的设施类型结构变化较小,表现出内部“城市功能趋同”的特征,而五个新城则均表现出生活设施的占比逐步降低而公共设施和生产设施的占比升高的趋势,新城之间呈现“扩张结构趋同”的特征;新城的高密度圈层中,生活设施占比均高于主城区水平,表现出一定的“卧城”特征;低密度圈层中,尽管生产设施占比均高于高密度圈层,但不同类型设施聚集中心高度重合表明生产设施的聚集中心同样在新城的中心区,其外围城市功能薄弱,并没有出现完善的“专业功能中心”。因此,新城的进一步建设需强调设施的均衡协调发展,完善城市功能,避免出现“卧城”“空城”等现象。

A triangular architectural relation model among sustainability,beauty,and power

Sustainability,beauty,and power are notions that hit our contemporary perception every day.However,they have been an integral part of architecture and urban planning in various forms since the ages.The paper presents their fundamental descriptions,followed by an assessment of their mutual relations and impact on architecture through a triangular architectural relation model developed by the authors of the article.Using the theoretical thought experiment,it highlights eight boundary models along with their main characteristics,in particular,the implosion,explosion,shared-control,utilitarian,no-control,supremacy,inside-forced,and outside-forced architectural related models.Such models can help predict future events,explain past events,make decisions,and plan strategies,or reveal problems and propose new solutions.Other applications include determination of the causes of certain results or finding out the responsibility and mechanisms that led to them.The authors are of the opinion that the mutual denominator of sustainability,beauty,and power represents ethics that should be forced in architectural education and practice.

基于TFAHP的电炉企业多维一体化财务模式评价模型

电炉企业的财务由于其参数指标众多,对相关模式评价过程不能运用单一阈值理论,评价过程一直是个难题。设计基于TFAHP的电炉企业多维一体化财务模式评价模型。通过微观模拟电炉企业财务工资过程,确定评价指标,由此构建模糊评价矩阵,依据模糊评价矩阵,构建二级评价矩阵,在单一准则下计算各评价指标的相对权重,采用三角模糊数层次分析法确定总权重,由此构建评价模型,获取评价结果,设定评价等级集合及区间值,给出具体评语等级。实验可知,所构建模型进行多维一体化财务模式评价在电炉企业应用效果较好,评价效率较高。

基于网格模型的自动铺丝路径规划方法

针对复合材料自动铺丝工艺,研究基于网格模型的自动铺丝路径规划方法。梳理了自动铺丝路径规划的业务流程,对三角网格拓扑关系进行重建,节省数据存储空间;提出了基于给定点与方向的定向延伸算法,用于精确计算网格模型的线型路径点;对路径等距后的点集进行优化,避免了等距后的线型自交以及凸边现象,保证了线型的准确;对所规划路径的压辊可铺放性分析方法进行研究,并基于分析结果提出了路径优化策略。结合CATIA二次开发工具CAA在VS平台对自动铺丝路径规划模块进行开发,并通过实例验证了本文所研究方法的可行性与可靠性。

基于模糊数学的工业区基坑支护施工风险评价

为研究工业区内复杂环境下深基坑支护结构风险状态,利用工作分解结构(WBS)分解工作项目,建立风险指标体系,制订安全预警等级,计算主客观权重并组合赋权,结合三角隶属函数进行多级模糊综合评价,建立深基坑桩锚支护结构风险评价模型。结果表明:模型能很好地反映出深基坑桩锚支护结构所处的风险状态,论证了该模型的可行性与科学性,可为现场管理人员提供借鉴。