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神经网络 4

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A regularization scheme for explicit level-set XFEM topology optimization

Markus J. GEISS, Jorge L. BARRERA, Narasimha BODDETI, Kurt MAUTE

《机械工程前沿（英文）》 2019年第14卷第2期页码 153-170 doi: 10.1007/s11465-019-0533-2

摘要： Regularization of the level-set (LS) field is a critical part of LS-based topology optimization (TO) approaches. Traditionally this is achieved by advancing the LS field through the solution of a Hamilton-Jacobi equation combined with a reinitialization scheme. This approach, however, may limit the maximum step size and introduces discontinuities in the design process. Alternatively, energy functionals and intermediate LS value penalizations have been proposed. This paper introduces a novel LS regularization approach based on a signed distance field (SDF) which is applicable to explicit LS-based TO. The SDF is obtained using the heat method (HM) and is reconstructed for every design in the optimization process. The governing equations of the HM, as well as the ones describing the physical response of the system of interest, are discretized by the extended finite element method (XFEM). Numerical examples for problems modeled by linear elasticity, nonlinear hyperelasticity and the incompressible Navier-Stokes equations in two and three dimensions are presented to show the applicability of the proposed scheme to a broad range of design optimization problems.

关键词： level-set regularization explicit level-sets XFEM CutFEM topology optimization heat method signed distance field nonlinear structural mechanics fluid mechanics

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Simulation of heterogeneous two-phase media using random fields and level sets

George STEFANOU

《结构与土木工程前沿（英文）》 2015年第9卷第2期页码 114-120 doi: 10.1007/s11709-014-0267-5

摘要： The accurate and efficient simulation of random heterogeneous media is important in the framework of modeling and design of complex materials across multiple length scales. It is usually assumed that the morphology of a random microstructure can be described as a non-Gaussian random field that is completely defined by its multivariate distribution. A particular kind of non-Gaussian random fields with great practical importance is that of translation fields resulting from a simple memory-less transformation of an underlying Gaussian field with known second-order statistics. This paper provides a critical examination of existing random field models of heterogeneous two-phase media with emphasis on level-cut random fields which are a special case of translation fields. The case of random level sets, often used to represent the geometry of physical systems, is also examined. Two numerical examples are provided to illustrate the basic features of the different approaches.

关键词： microstructure random fields level sets shape recovery two-phase media

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A refined risk explicit interval linear programming approach for optimal watershed load reduction with

Pingjian YANG,Feifei DONG,Yong LIU,Rui ZOU,Xing CHEN,Huaicheng GUO

《环境科学与工程前沿（英文）》 2016年第10卷第1期页码 129-140 doi: 10.1007/s11783-014-0683-8

摘要： To enhance the effectiveness of watershed load reduction decision making, the Risk Explicit Interval Linear Programming (REILP) approach was developed in previous studies to address decision risks and system returns. However, REILP lacks the capability to analyze the tradeoff between risks in the objective function and constraints. Therefore, a refined REILP model is proposed in this study to further enhance the decision support capability of the REILP approach for optimal watershed load reduction. By introducing a tradeoff factor ( ) into the total risk function, the refined REILP can lead to different compromises between risks associated with the objective functions and the constraints. The proposed model was illustrated using a case study that deals with uncertainty-based optimal load reduction decision making for Lake Qionghai Watershed, China. A risk tradeoff curve with different values of was presented to decision makers as a more flexible platform to support decision formulation. The results of the standard and refined REILP model were compared under 11 aspiration levels. The results demonstrate that, by applying the refined REILP, it is possible to obtain solutions that preserve the same constraint risk as that in the standard REILP but with lower objective risk, which can provide more effective guidance for decision makers.

关键词： refined risk explicit interval linear programming decision making objective-constraint uncertainty tradeoff aspiration level Lake Qionghai Watershed

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一种模糊Rough决策方法

罗党

《中国工程科学》 2004年第6卷第12期页码 32-36

摘要：

利用模糊集理论和粗糙集理论在处理不确定性和不精确性问题方面侧重点的差异性，构造一种组合决策模型。该模型从问题领域内的部分不精确信息出发利用模糊聚类方法构造一个决策信息系统，利用粗糙集理论关于决策规则的约简方法从决策信息系统中提取（挖掘）决策规则，使之适用于问题的整个领域。

关键词：模糊聚类粗糙集决策表决策规则

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Improved approach to quality function deployment based on Pythagorean fuzzy sets and application to assembly

Huchang LIAO, Yinghan CHANG, Di WU, Xunjie GOU

《工程管理前沿（英文）》 2020年第7卷第2期页码 196-203 doi: 10.1007/s42524-019-0038-z

摘要： Quality function deployment (QFD) is an effective method that helps companies analyze customer requirements (CRs). These CRs are then turned into product or service characteristics, which are translated to other attributes. With the QFD method, companies could design or improve the quality of products or services close to CRs. To increase the effectiveness of QFD, we propose an improved method based on Pythagorean fuzzy sets (PFSs). We apply an extended method to obtain the group consensus evaluation matrix. We then use a combined weight determining method to integrate former weights to objective weights derived from the evaluation matrix. To determine the exact score of each PFS in the evaluation matrix, we develop an improved score function. Lastly, we apply the proposed method to a case study on assembly robot design evaluation.

关键词： quality function deployment Pythagorean fuzzy sets group consensus combined weights assembly robot design

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Explicit optimization method for cutting-screw-thread on the basis of dual-RSM

Zhengbao LEI, Shubin WEI, Qingyun DU

《机械工程前沿（英文）》 2010年第5卷第4期页码 423-430 doi: 10.1007/s11465-010-0109-7

摘要： To obtain the explicit function for optimizing the cutting-screw-thread (CST) in crash, the simulations of frontal crash at the speed of 56 km/h have been carried out in VPG. The peak acceleration in crash has been taken as the evaluation index of energy absorption characteristics. First, the single factor experiment was taken based on six parameters affecting on the absorption characteristics of CST. Second, the peak acceleration function of each parameter by using response surface method (RSM) is obtained. Third, the explicit resultant peak acceleration function of six parameters by using RSM again is obtained. A dual RSM-based explicit method is proposed. According to this function, the best size dimensions of CST in different crash conditions could be easily obtained. Finally, an example shows that the values of the calculation errors for simulation value and target value (40 g) are 3.6% and 1.3%, respectively. This method can satisfy the demand for engineering accuracy.

关键词： vehicle engineering crash safety explicit method response surface method

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Noise control technology for generator sets in enclosures

ZHANG Nailong, YANG Wentong, FEI Renyuan

《机械工程前沿（英文）》 2008年第3卷第4期页码 377-384 doi: 10.1007/s11465-008-0051-0

摘要： Currently, noise pollution is an environmental problem all over the world. The health and life of human beings are affected by loud noise from high power generator sets. To reduce such noise, a sound-attenuated enclosure is widely used for its high performance and convenient usage. By installing equipment in an enclosure, noise is controlled and prevented from radiating. In this paper, noise control techniques for enclosures are presented. Enclosure development trends are predicted.

关键词： equipment generator sound-attenuated enclosure convenient Enclosure development

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一种基于粗糙集的模糊信息融合方法及应用

陈双叶,张微敬

《中国工程科学》 2006年第8卷第12期页码 75-79

摘要：

将粗糙集理论和模糊逻辑技术结合起来，提出了一种基于粗糙集数据处理的模糊信息融合方法。运用粗糙集的基本理论和简约计算方法，从大量原始数据中发现精简的、概略化的规则，结合模糊逻辑推理建立一致粗糙模糊模型，并提出了对模型进行扩充与完备化的概念。脉动真空灭菌温度控制过程的仿真试验研究结果表明了所提方法的有效性和可行性。

关键词：信息融合粗糙集模糊逻辑粗糙模糊模型

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基于粗集方法的智能专家系统

曾黄麟

《中国工程科学》 2001年第3卷第2期页码 47-51

摘要：

文章主要介绍基于粗集方法的智能专家系统的基本构成、知识表达方式及学习推理方法。提出了利用不可分辨性或根据算法相容性进行知识简化，导出决策规则的方法，通过研究导师的知识与学习者的知识之间的依赖程度，找出每一概念的有用特征，进行知识简化和系统简化，导出决策规则的学习推理方法。

关键词：粗集方法智能专家系统不可分辨性知识简化决策规则

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一种粗模糊神经分类器

曾黄麟,王晓

《中国工程科学》 2003年第5卷第12期页码 60-65

摘要：

介绍一种新的粗集编码模糊神经分类器。基于粗集理论的概念，讨论了知识编码、属性简化、分类系统简化的方法；并利用模糊隶属度函数将输入精确信息映射为模糊变量信息，解决分类中病态定义的数据问题和提高系统非线性映射的分类能力；提出了结合系统参数的重要性因子的网络的模糊推理方法和粗模糊神经分类器的网络结构以及有导师的最小平方误差学习训练算法。实现的粗集编码模糊神经分类器具有网络结构空间维数低、学习算法简单、网络训练时间短、非线性特性丰富等优点。

关键词：模糊粗集神经网络分类

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计算管内湍动流体摩擦因数的显式新方程

王勇,阮奇

《中国工程科学》 2006年第8卷第6期页码 83-88

摘要：

管内湍动流体摩擦因数是雷诺数和相对粗糙度的二元非线性函数，由Colebrook隐式方程计算摩擦因数要用迭代的方法求解，很不方便。为了得到形式简单、精度高的计算摩擦因数的显式方程，提出了二元非线性多项式智能拟合法。该法将二元非线性多项式转化成多元线性多项式并建立线性最小二乘法标准矩阵，用遗传算法结合矩阵法对多项式的项数、项型式项指数及项系数进行搜索得到最优的拟合函数式。用该法拟合了Colebrook方程解的数据，得到一个计算管内湍动流体摩擦因数的显式新方程。在雷诺数3.000≤Re≤10⁸、相对粗糙度0≤e/d≤0.05的范围内，该方程计算结果与Colebrook方程的平均偏差为0.5%，最大偏差不超过1.8%，与实验数据偏差为2.3%。新方程具有形式简单、精度高、适用范围广的优点，且便于简化成光滑管或阻力平方区等情况下的计算摩擦因数的方程。

关键词：湍动流动摩擦因数 Colebrook隐式方程遗传算法智能拟合法显式方程

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An overview on the applications of the hesitant fuzzy sets in group decision-making: Theory, support

Zeshui XU, Shen ZHANG

《工程管理前沿（英文）》 2019年第6卷第2期页码 163-182 doi: 10.1007/s42524-019-0017-4

摘要： Due to the characteristics of hesitant fuzzy sets (HFSs), one hesitant fuzzy element (HFE), which is the basic component of HFSs, can express the evaluation values of multiple decision makers (DMs) on the same alternative under a certain attribute. Thus, the HFS has its unique advantages in group decision making (GDM). Based on which, many scholars have conducted in-depth research on the applications of HFSs in GDM. We have viewed lots of relevant literature and divided the existing studies into three categories: theory, support and methods. In this paper, we elaborate on hesitant fuzzy GDM from these three aspects. The first aspect is mainly about the introduction of HFSs, HFPRs and some hesitant fuzzy aggregation operators. The second aspect describes the consensus process under hesitant fuzzy environment, which is an important support for a complete decision-making process. In the third aspect, we introduce seven hesitant fuzzy GDM approaches, which can be applied in GDM under different decision-making conditions. Finally, we summarize the research status of hesitant fuzzy GDM and put forward some directions of future research.

关键词： hesitant fuzzy set hesitant fuzzy preference relation group decision-making

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大型火电机组的振动故障诊断

于文虎,宋斌

《中国工程科学》 2001年第3卷第1期页码 44-50

摘要：

文章回顾总结了国内外火电机组振动故障诊断的发展状况，指出了目前振动故障诊断研究存在的问题及确定故障诊断知识范围、进行机组轴系传递特性研究的重要性，对大型火电机组振动及性能远程诊断系统进行了介绍，最后指出了振动故障诊断的发展方向。

关键词：汽轮机组故障诊断振动性能诊断

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基于Vague集的系统安全综合评价

刘爱华,施式亮,吴　超

《中国工程科学》 2007年第9卷第3期页码 58-61

摘要：

系统安全中存在含糊性和不可分辨性，Fuzzy综合评价只能从正面解决含糊性问题，而Vague集具有对不确定数据更强、更灵活的直觉表达能力，由此提出把Vague集运用到综合评价当中，并使用改进层次分析法确定各评价指标的权重，建立了基于Vague集的系统安全综合评价模型。通过对陕西某高层建筑火灾危险评价实例证明，该模型能使系统安全评价结果更准确、合理。

关键词：系统安全 Vague集综合评价权重

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任一路面上基于显式和隐式联合仿真技术的某轿车动态响应 Article

胡红舟, 钟志华

《工程（英文）》 2019年第5卷第6期页码 1171-1178 doi: 10.1016/j.eng.2019.09.003

摘要：

本文开展了将数值仿真技术用于某轿车耐久分析的研究。运用了基于显式和隐式的联合仿真，同时通过子模型技术来缩短仿真时间，使整车动态仿真时间达到基于传统有限元分析方法难以达到的低水平。联合仿真模型包含所有必要的非线性因素来保障仿真精度，所有关键件都基于变形体的定义。轮胎与路面的关系通过任一路面与轮胎的接触摩擦仿真实现。通过试验样车在6种不同路面上的仿真与测量值的对比，证明了基于显式和隐式分析的联合仿真技术具有足够的精度与仿真效率。本文同时也讨论了所采用的方法的局限性及将来可能的改进。

关键词：耐久分析动态响应显式隐式联合仿真接触分析子模型