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Multiobjective trajectory optimization of intelligent electro-hydraulic shovel

《机械工程前沿（英文）》 2022年第17卷第4期 doi: 10.1007/s11465-022-0706-2

摘要： Multiobjective trajectory planning is still face challenges due to certain practical requirements and multiple contradicting objectives optimized simultaneously. In this paper, a multiobjective trajectory optimization approach that sets energy consumption, execution time, and excavation volume as the objective functions is presented for the electro-hydraulic shovel (EHS). The proposed cubic polynomial S-curve is employed to plan the crowd and hoist speed of EHS. Then, a novel hybrid constrained multiobjective evolutionary algorithm based on decomposition is proposed to deal with this constrained multiobjective optimization problem. The normalization of objectives is introduced to minimize the unfavorable effect of orders of magnitude. A novel hybrid constraint handling approach based on -constraint and the adaptive penalty function method is utilized to discover infeasible solution information and improve population diversity. Finally, the entropy weight technique for order preference by similarity to an ideal solution method is used to select the most satisfied solution from the Pareto optimal set. The performance of the proposed strategy is validated and analyzed by a series of simulation and experimental studies. Results show that the proposed approach can provide the high-quality Pareto optimal solutions and outperforms other trajectory optimization schemes investigated in this article.

关键词： trajectory planning electro-hydraulic shovel cubic polynomial S-curve multiobjective optimization entropy weight technique

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鲁棒的极大熵聚类算法RMEC及其例外点标识

邓赵红,王士同,吴锡生,胡德文

《中国工程科学》 2004年第6卷第9期页码 38-45

摘要：

针对极大熵聚类算法MEC（maximum entropy clustering）对例外点（outliers）较敏感和不能标识例外点的缺陷，提出了一种改进的极大熵聚类算法RMEC（robust maximumentropy clustering）。

关键词：熵聚类鲁棒性例外点 ε-不敏感损失函数权重因子

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Principle of maximum entropy for reliability analysis in the design of machine components

Yimin ZHANG

《机械工程前沿（英文）》 2019年第14卷第1期页码 21-32 doi: 10.1007/s11465-018-0512-z

摘要： We studied the reliability of machine components with parameters that follow an arbitrary statistical distribution using the principle of maximum entropy (PME). We used PME to select the statistical distribution that best fits the available information. We also established a probability density function (PDF) and a failure probability model for the parameters of mechanical components using the concept of entropy and the PME. We obtained the first four moments of the state function for reliability analysis and design. Furthermore, we attained an estimate of the PDF with the fewest human bias factors using the PME. This function was used to calculate the reliability of the machine components, including a connecting rod, a vehicle half-shaft, a front axle, a rear axle housing, and a leaf spring, which have parameters that typically follow a non-normal distribution. Simulations were conducted for comparison. This study provides a design methodology for the reliability of mechanical components for practical engineering projects.

关键词： machine components reliability arbitrary distribution parameter principle of maximum entropy

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High-order phase-field model with the local and second-order max-entropy approximants

Fatemeh AMIRI

《结构与土木工程前沿（英文）》 2019年第13卷第2期页码 406-416 doi: 10.1007/s11709-018-0475-5

摘要： We approximate the fracture surface energy functional based on phase-field method with smooth local maximum entropy (LME) and second-order maximum entropy (SME) approximants. The higher-order continuity of the meshfree methods such as LME and SME approximants allows to directly solve the fourth-order phase-field equations without splitting the fourth-order differential equation into two second-order differential equations. We will first show that the crack surface functional can be captured more accurately in the fourth-order model with smooth approximants such as LME, SME and B-spline. Furthermore, smaller length scale parameter is needed for the fourth-order model to approximate the energy functional. We also study SME approximants and drive the formulations. The proposed meshfree fourth-order phase-field formulation show more stable results for SME compared to LME meshfree methods.

关键词： second-order maximum entropy local maximum entropy second- and fourth-order phase-field models B-spline

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Maximum entropy based finite element analysis of porous media

Emad NOROUZI, Hesam MOSLEMZADEH, Soheil MOHAMMADI

《结构与土木工程前沿（英文）》 2019年第13卷第2期页码 364-379 doi: 10.1007/s11709-018-0470-x

摘要： The maximum entropy theory has been used in a wide variety of physical, mathematical and engineering applications in the past few years. However, its application in numerical methods, especially in developing new shape functions, has attracted much interest in recent years. These shape functions possess the potential for performing better than the conventional basis functions in problems with randomly generated coarse meshes. In this paper, the maximum entropy theory is adopted to spatially discretize the deformation variable of the governing coupled equations of porous media. This is in line with the well-known fact that higher-order shape functions can provide more stable solutions in porous problems. Some of the benchmark problems in deformable porous media are solved with the developed approach and the results are compared with available references.

关键词： maximum entropy FEM fully coupled multi-phase system porous media

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Solving topology optimization problems by the Guide-Weight method

Xinjun LIU, Zhidong LI, Liping WANG, Jinsong WANG

《机械工程前沿（英文）》 2011年第6卷第1期页码 136-150 doi: 10.1007/s11465-010-0126-6

摘要：

Finding a good solution method for topology optimization problems is always paid attention to by the research field because they are subject to the large number of the design variables and to the complexity that occurs because the objective and constraint functions are usually implicit with respect to design variables. Guide-Weight method, proposed first by Chen in 1980s, was effectively and successfully used in antenna structures’ optimization. This paper makes some improvement to it so that it possesses the characteristics of both the optimality criteria methods and the mathematical programming methods. When the Guide-Weight method is applied into topology optimization, it works very well with unified and simple form, wide availability and fast convergence. The algorithm of the Guide-Weight method and the improvement on it are described; two formulations of topology optimization solved by the Guide-Weight method combining with SIMP method are presented; subsequently, three numerical examples are provided, and comparison of the Guide-Weight method with other methods is made.

关键词： Guide-Weight method topology optimization SIMP method

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High-entropy catalysts for electrochemical water-electrolysis of hydrogen evolution and oxygen evolution

《能源前沿（英文）》 doi: 10.1007/s11708-023-0892-6

摘要： High entropy materials (HEMs) have developed rapidly in the field of electrocatalytic water-electrolysis for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) due to their unique properties. In particular, HEM catalysts are composed of many elements. Therefore, they have rich active sites and enhanced entropy stability relative to single atoms. In this paper, the preparation strategies and applications of HEM catalysts in electrochemical water-electrolysis are reviewed to explore the stabilization of HEMs and their catalytic mechanisms as well as their application in support green hydrogen production. First, the concept and four characteristics of HEMs are introduced based on entropy and composition. Then, synthetic strategies of HEM catalysts are systematically reviewed in terms of the categories of bottom-up and top-down. The application of HEMs as catalysts for electrochemical water-electrolysis in recent years is emphatically discussed, and the mechanisms of improving the performance of electrocatalysis is expounded by combining theoretical calculation technology and ex-situ/in situ characterization experiments. Finally, the application prospect of HEMs is proposed to conquer the challenges in HEM catalyst fabrications and applications.

关键词： high-entropy electrocatalysis synthetic methods water-electrolysis hydrogen and oxygen evolutions

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Application of entropy-based fuzzy matter-element analysis in seepage monitoring of RCC dam

Chongshi GU, Zhijun ZHANG, Xin CAI, Yue HOU

《结构与土木工程前沿（英文）》 2011年第5卷第1期页码 105-111 doi: 10.1007/s11709-010-0015-4

摘要： Taking account of the fuzzy results of the seepage monitoring analysis of roller compacted concrete (RCC) dam and uncertainties of the individual indicator evaluation, the fuzzy matter-element model of seepage monitoring of RCC dam analysis has been established with the use of the fuzzy matter-element analysis theory and the concept of euclid approach degree. The use of entropy theory can calculate the weighting factor through the disorder utility values of the information reflected by the data itself, which can effectively avoid the problems of weight distribution and uncertainties of subjective judgments of the seepage monitoring analysis of roller compacted concrete dam. And further the example shows that the analysis of entropy-based fuzzy matter-element analysis model of the seepage monitoring of roller compacted concrete dam is in accordance with the actual situation, which verifies the effectiveness of the method.

关键词： information entropy fuzzy matter-element roller compacted concrete (RCC) dam seepage analysis

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Optimization of cold-end system of thermal power plants based on entropy generation minimization

《能源前沿（英文）》 2022年第16卷第6期页码 956-972 doi: 10.1007/s11708-021-0785-5

摘要： Cold-end systems are heat sinks of thermal power cycles, which have an essential effect on the overall performance of thermal power plants. To enhance the efficiency of thermal power plants, multi-pressure condensers have been applied in some large-capacity thermal power plants. However, little attention has been paid to the optimization of the cold-end system with multi-pressure condensers which have multiple parameters to be identified. Therefore, the design optimization methods of cold-end systems with single- and multi-pressure condensers are developed based on the entropy generation rate, and the genetic algorithm (GA) is used to optimize multiple parameters. Multiple parameters, including heat transfer area of multi-pressure condensers, steam distribution in condensers, and cooling water mass flow rate, are optimized while considering detailed entropy generation rate of the cold-end systems. The results show that the entropy generation rate of the multi-pressure cold-end system is less than that of the single-pressure cold-end system when the total condenser area is constant. Moreover, the economic performance can be improved with the adoption of the multi-pressure cold-end system. When compared with the single-pressure cold-end system, the excess revenues gained by using dual- and quadruple-pressure cold-end systems are 575 and 580 k$/a, respectively.

关键词： cold-end system entropy generation minimization optimization economic analysis genetic algorithm (GA)

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Instantaneous deflection of light-weight concrete slabs

Behnam VAKHSHOURI, Shami NEJADI

《结构与土木工程前沿（英文）》 2017年第11卷第4期页码 412-423 doi: 10.1007/s11709-017-0416-8

摘要： Construction loading before the age of 28 d can have the most significant effects on the slabs, especially for multi-story structures. The changing properties of the young concrete complicate the prediction of serviceability design requirements also. An experimental investigation is performed on four simply supported Light-Weight Concrete (LWC) one-way slabs subjected to immediate loading at 14 d. Effects of aggregate type, loading levels and cracking moment together with the influences of ultimate moment capacity and service moment on the instantaneous deflection of slabs are studied. Comparison of the obtained results with predictions of existing models in the literature shows considerable differences between the recorded and estimated instantaneous deflection of LWC slabs. Based on sensitivity analysis of the effective parameters, a new equation is proposed and verified to predict the instantaneous deflection of LWC slabs subjected to loading at the age of 14 d.

关键词： instantaneous deflection light-weight concrete expanded polystyrene effective moment of inertia cracking moment moment capacity service moment

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Entropy flow, entropy generation, exergy flux, and optimal absorbing temperature in radiative transfer

Zeshao CHEN, Songping MO, Peng HU, Shouli JIANG, Gang WANG, Xiaofang CHENG,

《能源前沿（英文）》 2010年第4卷第3期页码 301-305 doi: 10.1007/s11708-010-0006-0

摘要： Taking nonequilibrium radiative heat transfer between two surfaces as an example, the nonequilibrium thermodynamics of radiation is studied and discussed. The formulas of entropy flow, entropy generation, exergy flux, and optimal temperature of absorbing surface for maximum exergy output are derived. The result is a contribution to the thermodynamic analysis and optimization of solar energy utilization and can be applied in more complex radiative heat transfer cases.

关键词： radiative heat transfer entropy generation exergy thermodynamics

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知识创新随机过程最大熵模型

陈欣,和金生,董丽平

《中国工程科学》 2004年第6卷第12期页码 43-46

摘要：

根据创新知识的形成受已有相关知识影响的假设，综合运用概率统计、最优化、最大熵原理构建了知识创新随机过程最大熵模型，给出了以已有知识x∈X为约束的新知识y∈Y的条件概率p(y|x)。模型具有随机性与因果性对立统一的特点。

关键词：最大熵知识创新条件熵随机过程

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一类灰色模糊决策问题的熵权分析方法

罗党,刘思峰

《中国工程科学》 2004年第6卷第10期页码 48-51

摘要：

以灰色系统理论和模糊数学为基础，探讨了不确定型决策问题的特性，分析了一些相关成果中所给方法在直接处理灰色模糊数方面的优势与不足。运用优化理论和熵极大化准则，建立了基于灰色模糊关系的多属性群体决策方法，分别对属性权重向量已知和未知两种情况给出了简便实用的算法，通过算例说明了算法的合理性。

关键词：灰色模糊关系熵多属性决策

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Characterization of soil low-molecular-weight organic acids in the Karst rocky desertification region

Xiaoliang LI, Xiaomin CHEN, Xia LIU, Lianchuan ZHOU, Xinqiang YANG

《环境科学与工程前沿（英文）》 2012年第6卷第2期页码 195-203 doi: 10.1007/s11783-012-0391-1

摘要： Soil low-molecular-weight (LMW) organic acids play important roles in the soil-forming process and the cycling of nutrients in Karst regions. In this study, we quantified the contents of LMW organic acids (including lactate, acetate, formate, malate, and oxalate) in soil solution over the Karst region of Guizhou Province, China using ion chromatography. The concentration of total LMW organic acids in topsoil solution ranged from 0.358 to 1.823 μmol·g , with an average of 0.912 μmol·g . The mean concentrations of lactate, acetate, formate, malate, and oxalate were 0.212±0.089, 0.302±0.228, 0.301±0.214, 0.014±0.018 and 0.086±0.118 μmol·g , respectively. There were also significant difference in the contents of these acids among four phases of rocky desertification, and their concentrations decreased with the aggravation of rocky desertification. The concentrations of the LMW organic acids were significantly positive correlated each other. Significant positive correlations were also observed among individual LMW organic acids in soil solution, and between them and soil available P, available K, exchangeable Ca, respectively. Furthermore, the concentrations of LMW organic acids were significantly positively correlated with inorganic anions (chlorides, nitrates, and sulfates) in Karst topsoil solution. Therefore, the concentrations of soil LMW organic acids might be one of driving force in the Karst rock desertification process in Guizhou Province.

关键词： Karst rocky desertification low-molecular-weight (LMW) organic acids distribution characteristics soil

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多尺度作物种植结构优化及其伴生效应分析 Article

刘琦, 牛俊, 杜太生, 康绍忠

《工程（英文）》 2023年第28卷第9期页码 139-152 doi: 10.1016/j.eng.2023.03.012

摘要：

在农业可持续发展理念的推动下，作物种植结构优化已成为减少区域作物耗水、保障粮食安全和保护生态环境的有效措施。然而，传统的作物种植结构优化（CPSO）往往忽视了对区域粮食供需关系和省际间粮食贸易结构的影响。本研究运用系统分析的思想，以虚拟水贸易为衔接点，提出了一个基于多尺度、全方位评价指标体系的CPSO理论框架，并加以应用。构建了SWAT-WF的水足迹模拟模块，以模拟区域作物生产的水足迹（WF）数量与组分。建立了以最大化区域经济水生产力（EWP）、最小化蓝水依赖度（BWFrate）和最小化灰水足迹（GWFgray）为目标的多目标空间CPSO模型，以实现区域种植结构的最优种植布局。结合多层次效益指标，构建了基于地区、省份和国家尺度的全面评价指标体系。通过熵权-TOPSIS综合评价模型，实现多种CPSO方案的优选。以中国甘肃省内的黑河流域中上游地区为研究案例，验证本文提出的理论框架，结合虚拟水贸易与系统分析理论为黑河流域确定了最优作物种植结构。优化结果以牺牲一定程度经济效益为代价，显著提高了区域水资源效益和生态效益。

关键词：种植结构优化多尺度评价指标体系水足迹 SWAT-WF模块省际间粮食贸易熵权-TOPSIS法