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Build orientation determination of multi-feature mechanical parts in selective laser melting via multi-objective

《机械工程前沿（英文）》 2023年 第18卷 第2期 doi: 10.1007/s11465-022-0737-8

摘要： Selective laser melting (SLM) is a unique additive manufacturing (AM) category that can be used to manufacture mechanical parts. It has been widely used in aerospace and automotive using metal or alloy powder. The build orientation is crucial in AM because it affects the as-built part, including its part accuracy, surface roughness, support structure, and build time and cost. A mechanical part is usually composed of multiple surface features. The surface features carry the production and design knowledge, which can be utilized in SLM fabrication. This study proposes a method to determine the build orientation of multi-feature mechanical parts (MFMPs) in SLM. First, the surface features of an MFMP are recognized and grouped for formulating the particular optimization objectives. Second, the estimation models of involved optimization objectives are established, and a set of alternative build orientations (ABOs) is further obtained by many-objective optimization. Lastly, a multi-objective decision making method integrated by the technique for order of preference by similarity to the ideal solution and cosine similarity measure is presented to select an optimal build orientation from those ABOs. The weights of the feature groups and considered objectives are achieved by a fuzzy analytical hierarchy process. Two case studies are reported to validate the proposed method with numerical results, and the effectiveness comparison is presented. Physical manufacturing is conducted to prove the performance of the proposed method. The measured average sampling surface roughness of the most crucial feature of the bracket in the original orientation and the orientations obtained by the weighted sum model and the proposed method are 15.82, 10.84, and 10.62 μm, respectively. The numerical and physical validation results demonstrate that the proposed method is desirable to determine the build orientations of MFMPs with competitive results in SLM.

关键词： selective laser melting (SLM)     build orientation determination     multi-feature mechanical part (MFMP)     fuzzy analytical hierarchy process     multi-objective decision making (MODM)    

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Residual stresses in coating-based systems, part I: Mechanisms and analytical modeling

ZHANG Xiancheng, WU Yixiong, XU Binshi, WANG Haidou

《机械工程前沿（英文）》 2007年 第2卷 第1期   页码 1-12 doi: 10.1007/s11465-007-0001-2

摘要： Thin films and multi-layered coatings comprised of different classes of materials are often used for various functional devices. The thermo-mechanical integrity of these systems is becoming a major concern and is strongly related to the residual stresses because of the fabrication processes. In this paper, the sources of the residual stresses in the coating-based systems and the concept of misfit strain were briefly reviewed. Analytical models were developed to predict the residual stresses in multi-layered film structures or coating-based systems using the force and moment balances. In addition, the residual stress distributions in the func tionally and compositionally graded coatings were also analyzed.

关键词： briefly     different     thermo-mechanical integrity     addition     residual    

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Unknown fault detection for EGT multi-temperature signals based on self-supervised feature learning and

《能源前沿（英文）》 2023年 第17卷 第4期   页码 527-544 doi: 10.1007/s11708-023-0880-x

摘要： Intelligent power systems can improve operational efficiency by installing a large number of sensors. Data-based methods of supervised learning have gained popularity because of available Big Data and computing resources. However, the common paradigm of the loss function in supervised learning requires large amounts of labeled data and cannot process unlabeled data. The scarcity of fault data and a large amount of normal data in practical use pose great challenges to fault detection algorithms. Moreover, sensor data faults in power systems are dynamically changing and pose another challenge. Therefore, a fault detection method based on self-supervised feature learning was proposed to address the above two challenges. First, self-supervised learning was employed to extract features under various working conditions only using large amounts of normal data. The self-supervised representation learning uses a sequence-based Triplet Loss. The extracted features of large amounts of normal data are then fed into a unary classifier. The proposed method is validated on exhaust gas temperatures (EGTs) of a real-world 9F gas turbine with sudden, progressive, and hybrid faults. A comprehensive comparison study was also conducted with various feature extractors and unary classifiers. The results show that the proposed method can achieve a relatively high recall for all kinds of typical faults. The model can detect progressive faults very quickly and achieve improved results for comparison without feature extractors in terms of F1 score.

关键词： fault detection     unary classification     self-supervised representation learning     multivariate nonlinear time series    

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Aseismic smart building isolation systems under multi-level earthquake excitations: Part I, conceptual

Min-Ho CHEY,J. Geoffrey CHASE,John B. MANDER,Athol J. CARR

《结构与土木工程前沿（英文）》 2015年 第9卷 第3期   页码 286-296 doi: 10.1007/s11709-015-0307-9

摘要： As a novel structural control strategy, tuned mass damper (TMD) inspired passive and semi-active smart building isolation systems are suggested to reduce structural response and thus mitigate structural damage due to earthquake excitations. The isolated structure’s upper stories can be utilized as a large scaled TMD, and the isolation layer, as a core design point, between the separated upper and lower stories entails the insertion of rubber bearings and (i) viscous dampers (passive) or (ii) resettable devices (semi-active). The seismic performance of the suggested isolation systems are investigated for 12-story reinforced concrete moment resisting frames modeled as “10+ 2” stories and “8+ 4” stories. Passive viscous damper or semi-active resettable devices are parametrically evaluated through the optimal design principle of a large mass ratio TMD. Statistical performance metrics are presented for 30 earthquake records from the three suites of the SAC project. Based on nonlinear structural models, including P-delta effects and modified Takeda hysteresis, the inelastic time history analyses are conducted to compute the seismic performances across a wide range of seismic hazard intensities. Results show that semi-active smart building isolation systems can effectively manage seismic response for multi-degree-of freedom (MDOF) systems across a broader range of ground motions in comparison to uncontrolled case and passive solution.

关键词： tuned mass damper     smart building isolation     resettable device     non-linear     statistical assessment    

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Reliability-based robust design optimization of vehicle components, Part I: Theory

Yimin ZHANG

《机械工程前沿（英文）》 2015年 第10卷 第2期   页码 138-144 doi: 10.1007/s11465-015-0333-2

摘要：

The reliability-based design optimization, the reliability sensitivity analysis and robust design method are employed to present a practical and effective approach for reliability-based robust design optimization of vehicle components. A procedure for reliability-based robust design optimization of vehicle components is proposed. Application of the method is illustrated by reliability-based robust design optimization of axle and spring. Numerical results have shown that the proposed method can be trusted to perform reliability-based robust design optimization of vehicle components.

关键词： vehicle components     reliability-based design optimization     reliability-based sensitivity analysis     multi-objective optimization     robust design    

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Mechanical responses of multi-layered ground due to shallow tunneling with arbitrary ground surface load

《结构与土木工程前沿（英文）》 2023年 第17卷 第5期   页码 745-762 doi: 10.1007/s11709-023-0935-4

摘要： An analytical model based on complex variable theory is proposed to investigate ground responses due to shallow tunneling in multi-layered ground with an arbitrary ground surface load. The ground layers are assumed to be linear-elastic with full-stick contact between them. To solve the proposed multi-boundary problem, a series of analytic functions is introduced to accurately express the stresses and displacements contributed by different boundaries. Based on the principle of linear-elastic superposition, the multi-boundary problem is converted into a superposition of multiple single-boundary problems. The conformal mappings of different boundaries are independent of each other, which allows the stress and displacement fields to be obtained by the sum of components from each boundary. The analytical results are validated based on numerical and in situ monitoring results. The present model is superior to the classical model for analyzing ground responses of shallow tunneling in multi-layered ground; thus, it can be used with assurance to estimate the ground movement and surface building safety of shallow tunnel constructions beneath surface buildings. Moreover, the solution for the ground stress distribution can be used to estimate the safety of a single-layer composite ground.

关键词： analytical model     mechanical response     multi-layered ground     shallow tunneling     ground surface load     complex variable solution    

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Reliability-based robust design optimization of vehicle components, Part II: Case studies

Yimin ZHANG

《机械工程前沿（英文）》 2015年 第10卷 第2期   页码 145-153 doi: 10.1007/s11465-015-0334-1

摘要：

The reliability-based optimization, the reliability-based sensitivity analysis and robust design method are employed to propose an effective approach for reliability-based robust design optimization of vehicle components in Part I. Applications of the method are further discussed for reliability-based robust optimization of vehicle components in this paper. Examples of axles,torsion bar, coil and composite springs are illustrated for numerical investigations. Results have shown the proposed method is an efficient method for reliability-based robust design optimization of vehicle components.

关键词： vehicle axles and springs     reliability-based design optimization     reliability-based sensitivity analysis     multi-objective optimization     robust design    

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Wavelet design for extracting weak fault feature based on lifting scheme

JIANG Hong-kai, WANG Zhong-sheng, HE Zheng-jia

《机械工程前沿（英文）》 2006年 第1卷 第2期   页码 199-203 doi: 10.1007/s11465-006-0009-z

摘要： Weak fault features of mechanical signals are usually immersed in noisy signals. A new wavelet method based on lifting scheme to match weak fault characteristics is proposed. In this method, an initial set of finite biorthogonal filters is modified by a lifting and dual lifting procedure alternately, and different lifting operators and dual lifting operators are obtained. The properties of the initial wavelet is improved, and the new wavelet with particular properties is designed. Simulation and engineering results confirm that the proposed method is better than other wavelet methods for extracting weak fault feature. Modulus maxima of the detail signal in every operation cycle are extracted, the position and time that weak signal singularity occurs are clearly found, and slight rub-impact fault caused by axis misalignment and rotor imbalance of a heavy oil catalytic cracking set are desirably extracted. extracted.

关键词： misalignment     imbalance     particular     position     mechanical    

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机械产品的信息化——面向机械装备的信息技术

屈梁生,胡兆勇

《中国工程科学》 2004年 第6卷 第11期   页码 20-28

摘要：

机械工业是我国的传统工业，机械装备技术直接影响和制约国民经济诸多领域的发展。信息科学是一门迅速发展的前沿学科，已经渗透到国民经济的各个领域。文章从机械产品的角度出发，讨论了如何用信息技术来提升和发展传统的机械产品，提出了机械产品信息化的内涵、特点与实现的步骤；结合作者过去的一些科研实践，重点分析了机械产品信息化过程的信息融合和特征提取两个技术关键；文章最后强调了理论开拓是产品拥有自主知识产权和核心技术的前提。

关键词： 信息化     机械工业     信息融合     特征提取    

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Aseismic smart building isolation systems under multi-level earthquake excitations: Part II, energy-dissipation

Min-Ho CHEY,J. Geoffrey CHASE,John B. MANDER,Athol J. CARR

《结构与土木工程前沿（英文）》 2015年 第9卷 第3期   页码 297-306 doi: 10.1007/s11709-015-0308-8

摘要： Based on the performance results of the previously suggested smart building isolation systems (1st companion paper), this following study verifies the control effects of the systems from the view point of energy dissipation and damage level metrics. Several different model cases of the strategically isolated multi-story building structures utilizing passive dampers and semi-active resettable devices are analyzed and the energy-based target indices are compared. Performance comparisons are conducted on statistically calculated story/structural hysteretic energy and story/structural damage demands over realistic suites of earthquake ground motion records, representing seismic excitations of specific return period probability. Again, the semi-active solutions show significant promise for applications of resettable device, offering advantages over passive systems in the consistent damage reductions. The specific results of this study include the identification of differences in the mechanisms by which smart building isolation systems remove energy, based on the differences in the devices used. Less variability is also seen for the semi-active isolation systems, indicating an increased robustness.

关键词： smart building isolation     story and structural     energy-dissipation     damage assessment    

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基于本体论的工艺信息描述方法研究

李莉,郝永平,舒启林,张建富

《中国工程科学》 2003年 第5卷 第11期   页码 75-78

摘要：

依据本体论的概念论述了零件信息和制造资源信息的描述方法，给出了它们本体的定义方式。描述了零件本体和特征本体的属性，分析了各本体间和本体属性间的关系。以开发的CAPP系统为例，阐述了此描述方法在实际应用中体现出的特点。

关键词： CAPP     本体论     零件本体     特征本体     制造资源本体     工艺资源本体    

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Surface accuracy optimization of mechanical parts with multiple circular holes for additive manufacturing

Jinghua XU, Hongsheng SHENG, Shuyou ZHANG, Jianrong TAN, Jinlian DENG

《机械工程前沿（英文）》 2021年 第16卷 第1期   页码 133-150 doi: 10.1007/s11465-020-0610-6

摘要： Surface accuracy directly affects the surface quality and performance of mechanical parts. Circular hole, especially spatial non-planar hole set is the typical feature and working surface of mechanical parts. Compared with traditional machining methods, additive manufacturing (AM) technology can decrease the surface accuracy errors of circular holes during fabrication. However, an accuracy error may still exist on the surface of circular holes fabricated by AM due to the influence of staircase effect. This study proposes a surface accuracy optimization approach for mechanical parts with multiple circular holes for AM based on triangular fuzzy number (TFN). First, the feature lines on the manifold mesh are extracted using the dihedral angle method and normal tensor voting to detect the circular holes. Second, the optimal AM part build orientation is determined using the genetic algorithm to optimize the surface accuracy of the circular holes by minimizing the weighted volumetric error of the part. Third, the corresponding weights of the circular holes are calculated with the TFN analytic hierarchy process in accordance with the surface accuracy requirements. Lastly, an improved adaptive slicing algorithm is utilized to reduce the entire build time while maintaining the forming surface accuracy of the circular holes using digital twins via virtual printing. The effectiveness of the proposed approach is experimentally validated using two mechanical models.

关键词： surface accuracy optimization     multiple circular holes     additive manufacturing (AM)     part build orientation     triangular fuzzy number (TFN)     digital twins    

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Exploring the mechanical properties of steel- and polypropylene-reinforced ultra-high-performance concretethrough numerical analyses and experimental multi-target digital image correlation

《结构与土木工程前沿（英文）》   页码 1228-1248 doi: 10.1007/s11709-023-0931-8

摘要： This study presents experimental and numerical investigations on the mechanical properties of ultra-high-performance concrete (UHPC) reinforced with single and hybrid micro- and macro-steel and polypropylene fibers. For this purpose, a series of cubic, cylindrical, dog-bone, and prismatic beam specimens (total fiber by volume = 1%, and 2%) were tested under compressive, tensile, and flexural loadings. A method, namely multi-target digital image correlation (MT-DIC) was used to monitor the displacement and deflection values. The obtained experimental data were subsequently used to discuss influential parameters, i.e., flexural strength, tensile strength, size effect, etc. Numerical analyses were also carried out using finite element software to account for the sensitivity of different parameters. Furthermore, nonlinear regression analyses were conducted to obtain the flexural load-deflection curves. The results showed that the MT-DIC method was capable of estimating the tensile and flexural responses as well as the location of the crack with high accuracy. In addition, the regression analyses showed excellent consistency with the experimental results, with correlation coefficients close to unity. Furthermore, size-effect modeling revealed that modified Bazant theory yielded the best estimation of the size-effect phenomenon compared to other models.

关键词： UHPC     MT-DIC     flexural behavior     tensile behavior     steel fiber     polypropylene fiber    

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Multi-UAV collaborative system with a feature fast matching algorithm

Tian-miao Wang, Yi-cheng Zhang, Jian-hong Liang, Yang Chen, Chao-lei Wang,zycet@126.com

《信息与电子工程前沿（英文）》 2020年 第21卷 第12期   页码 1671-1814 doi: 10.1631/FITEE.2000047

摘要： We present a real-time monocular system with a new distributed structure for multi-UAV tasks. The system is different from other general SLAM systems in two aspects: First, it does not aim to build a global map, but to estimate the latest relative position between nearby vehicles; Second, there is no centralized structure in the proposed system, and each vehicle owns an individual metric map and an ego-motion estimator to obtain the relative position between its own map and the neighboring vehicles’. To realize the above characteristics in real time, we demonstrate an innovative algorithm to avoid catastrophic expansion of feature point matching workload due to the increased number of UAVs. Based on the hash and principal component analysis, the matching time complexity of this algorithm can be reduced from (log ) to (1). To evaluate the performance, the algorithm is verified on the acknowledged multi-view stereo benchmark dataset, and excellent results are obtained. Finally, through the simulation and real flight experiments, this improved SLAM system with the proposed algorithm is validated.
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自适应多小波基函数构造与机械故障诊断应用研究

何正嘉,孙海亮,訾艳阳

《中国工程科学》 2011年 第13卷 第10期   页码 83-92

摘要：

设备在运行中萌生的故障(即早期故障)，特征信息微弱且往往被机械设备运行过程的强噪声所淹没，给故障诊断与预示带来困难，已成为国内外此领域研究的热点和难点。文章深入研究了机械故障动态信号与基函数的内积变换原理；提出了若干自适应多小波基函数构造方法；改进了几种多小波邻域区间和局部阈值降噪方法。利用典型的工程案例分析和阐述了重油催化裂化装置、连铸连轧机组、空分机、电力机车和船载卫星通信地球站传动系统在运行状态下，微弱动态信号的特征增强和复合故障特征提取的工程应用实效。

关键词： 机械故障诊断     内积变换原理     自适应基函数     多小波降噪     故障特征提取    

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标题 作者 时间 类型 操作

Build orientation determination of multi-feature mechanical parts in selective laser melting via multi-objective

期刊论文

Residual stresses in coating-based systems, part I: Mechanisms and analytical modeling

ZHANG Xiancheng, WU Yixiong, XU Binshi, WANG Haidou

期刊论文

Unknown fault detection for EGT multi-temperature signals based on self-supervised feature learning and

期刊论文

Aseismic smart building isolation systems under multi-level earthquake excitations: Part I, conceptual

Min-Ho CHEY,J. Geoffrey CHASE,John B. MANDER,Athol J. CARR

期刊论文

Reliability-based robust design optimization of vehicle components, Part I: Theory

Yimin ZHANG

期刊论文

Mechanical responses of multi-layered ground due to shallow tunneling with arbitrary ground surface load

期刊论文

Reliability-based robust design optimization of vehicle components, Part II: Case studies

Yimin ZHANG

期刊论文

Wavelet design for extracting weak fault feature based on lifting scheme

JIANG Hong-kai, WANG Zhong-sheng, HE Zheng-jia

期刊论文

机械产品的信息化——面向机械装备的信息技术

屈梁生,胡兆勇

期刊论文

Aseismic smart building isolation systems under multi-level earthquake excitations: Part II, energy-dissipation

Min-Ho CHEY,J. Geoffrey CHASE,John B. MANDER,Athol J. CARR

期刊论文

基于本体论的工艺信息描述方法研究

李莉,郝永平,舒启林,张建富

期刊论文

Surface accuracy optimization of mechanical parts with multiple circular holes for additive manufacturing

Jinghua XU, Hongsheng SHENG, Shuyou ZHANG, Jianrong TAN, Jinlian DENG

期刊论文

Exploring the mechanical properties of steel- and polypropylene-reinforced ultra-high-performance concretethrough numerical analyses and experimental multi-target digital image correlation

期刊论文

Multi-UAV collaborative system with a feature fast matching algorithm

Tian-miao Wang, Yi-cheng Zhang, Jian-hong Liang, Yang Chen, Chao-lei Wang,zycet@126.com

期刊论文

自适应多小波基函数构造与机械故障诊断应用研究

何正嘉,孙海亮,訾艳阳

期刊论文