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Novel method of constructing generalized Hoberman sphere mechanisms based on deployment axes

Xuemin SUN, Yan-An YAO, Ruiming LI

《机械工程前沿（英文）》 2020年 第15卷 第1期   页码 89-99 doi: 10.1007/s11465-019-0567-5

摘要： This study proposes a method of constructing type II generalized angulated elements (GAEs II) Hoberman sphere mechanisms on the basis of deployment axes that intersect at one point. First, the constraint conditions for inserting GAEs II into deployment axes to form a loop are given. The angle constraint conditions of the deployment axes are obtained through a series of linear equations. Second, the connection conditions of two GAEs II loops that share a common deployable center are discussed. Third, a flowchart of constructing the generalized Hoberman sphere mechanism on the basis of deployment axes is provided. Finally, four generalized Hoberman sphere mechanisms based on a fully enclosed regular hexahedron, arithmetic sequence axes, orthonormal arithmetic sequence axes, and spiral-like axes are constructed in accordance with the given arrangement of deployment axes that satisfy the constraint conditions to verify the feasibility of the proposed method.

关键词： deployable mechanism     type II generalized angulated elements     Hoberman sphere mechanism     deployment axes     constraint conditions    

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Technology and system of constraint programming for industry production scheduling

Yarong CHEN, Zailin GUAN, Yunfang PENG, Xinyu SHAO, Muhammad HASSEB

《机械工程前沿（英文）》 2010年 第5卷 第4期   页码 455-464 doi: 10.1007/s11465-010-0106-x

摘要： The use of techniques and system of constraint programming enables the implementation of precise, flexible, efficient, and extensible scheduling systems. It has been identified as a strategic direction and dominant form for the application into planning and scheduling of industrial production. This paper systematically introduces the constraint modeling and solving technology for production scheduling problems, including various real-world industrial applications based on the Chip system of Cosytec Company. We trend of some concrete technology, such as modeling, search, constraint propagation, consistency, and optimization of constraint programming for scheduling problems. As a result of the application analysis, a generic application framework for real-life scheduling based on commercial constraint propagation (CP) systems is proposed.

关键词： constraint programming     production scheduling     constraint propagation     search     consistency     optimization    

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Recent development in low-constraint fracture toughness testing for structural integrity assessment of

Jidong KANG, James A. GIANETTO, William R. TYSON

《机械工程前沿（英文）》 2018年 第13卷 第4期   页码 546-553 doi: 10.1007/s11465-018-0501-2

摘要：

Fracture toughness measurement is an integral part of structural integrity assessment of pipelines. Traditionally, a single-edge-notched bend (SE(B)) specimen with a deep crack is recommended in many existing pipeline structural integrity assessment procedures. Such a test provides high constraint and therefore conservative fracture toughness results. However, for girth welds in service, defects are usually subjected to primarily tensile loading where the constraint is usually much lower than in the three-point bend case. Moreover, there is increasing use of strain-based design of pipelines that allows applied strains above yield. Low-constraint toughness tests represent more realistic loading conditions for girth weld defects, and the corresponding increased toughness can minimize unnecessary conservatism in assessments. In this review, we present recent developments in low-constraint fracture toughness testing, specifically using single-edge-notched tension specimens, SENT or SE(T). We focus our review on the test procedure development and automation, round-robin test results and some common concerns such as the effect of crack tip, crack size monitoring techniques, and testing at low temperatures. Examples are also given of the integration of fracture toughness data from SE(T) tests into structural integrity assessment.

关键词： fracture toughness     constraint effect     single-edge-notched tension test     pipeline     structural integrity assessment    

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Development of rocking constraint device with vertical damping capacity for three-dimensional base-isolated

《结构与土木工程前沿（英文）》 2023年 第17卷 第3期   页码 350-367 doi: 10.1007/s11709-022-0923-0

摘要： A new rocking constraint device (RCD) is developed for three-dimensional (3D) base-isolated frame structures by connecting a custom-designed cylinder pair to provide vertical damping with replaceable damping components installed outside the cylinders when the superstructure undergoes translational motion, and rocking constraint capacity when the superstructure is susceptible to rocking. Theoretical formulas for calculating the damping and rocking constraint stiffness of the RCD are proposed. Two series of sinusoidal loading tests are conducted at different loading frequencies and amplitudes to verify the damping and rocking constraint performance of the RCD. The test results show that the cylinder without orifices on its piston can provide the desired damping with a replaceable damping component, and that the RCD can effectively suppress rocking. Although the vertical stiffness of an individual cylinder is affected by the location of the replaceable damping component and loading frequency, the average vertical stiffness of the two cylinders, which determines the rocking constraint stiffness of the RCD, is independent of the two factors. Comparisons of the test and theoretical results indicate that the errors of the proposed formulas for calculating the damping and rocking constraint stiffness of the RCD do not exceed 12.9% and 11.0%, respectively.

关键词： three-dimensional isolation     rocking behavior     rocking constraint device     replaceable damping component     sinusoidal test    

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Research on constraint-based virtual assembly technologies

YANG Rundang, WU Dianliang, FAN Xiumin, YAN Juanqi

《机械工程前沿（英文）》 2007年 第2卷 第2期   页码 243-249 doi: 10.1007/s11465-007-0043-5

摘要： To realize a constraint-based virtual assembly operation, the unified representations of the assembly constraint, the equivalent relation between the constraint and the degree of freedom (DOF), and the movement DOF reduction in a virtual environment are proposed. Several algorithms about the constraint treatment are submitted. First, the automatic recognition algorithm based on the assembly relation is used to determine the position and orientation relation between two geometry elements of constraint whether they meet the given errors. Second, to satisfy the new constraint, according to the positing solving algorithm, the position and orientation of an active part are modified with minimal adjustment after the part has satisfied the affirmed constraints. Finally, the algorithm of movement navigation based on the generalized coordinate system is put forward, and the part movement is guided. These algorithms have been applied to the integrated virtual assembly environment (IVAE) system. Experiments have indicated that these algorithms have well supported constraint treatments in the IVAE and realized the closer combination of the virtual and the real assembly processes.

关键词： movement DOF     recognition algorithm     assembly     orientation     combination    

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Topology optimization of transient problem with maximum dynamic response constraint using SOAR scheme

《机械工程前沿（英文）》 2021年 第16卷 第3期   页码 593-606 doi: 10.1007/s11465-021-0636-4

摘要： This paper proposes a novel method for the continuum topology optimization of transient vibration problem with maximum dynamic response constraint. An aggregated index in the form of an integral function is presented to cope with the maximum response constraint in the time domain. The density filter solid isotropic material with penalization method combined with threshold projection is developed. The sensitivities of the proposed index with respect to design variables are conducted. To reduce computational cost, the second-order Arnoldi reduction (SOAR) scheme is employed in transient analysis. Influences of aggregate parameter, duration of loading period, interval time, and number of basis vectors in the SOAR scheme on the final designs are discussed through typical examples while unambiguous configuration can be achieved. Through comparison with the corresponding static response from the final designs, the optimized results clearly demonstrate that the transient effects cannot be ignored in structural topology optimization.

关键词： topology optimization     solid isotropic material with penalization     transient response     aggregation function     second-order Arnoldi reduction    

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Fast removal of ocular artifacts from electroencephalogram signals using spatial constraint independent

Bang-hua YANG,Liang-fei HE,Lin LIN,Qian WANG

《信息与电子工程前沿（英文）》 2015年 第16卷 第6期   页码 486-496 doi: 10.1631/FITEE.1400299

摘要： Ocular artifacts cause the main interfering signals within electroencephalogram (EEG) signal measurements. An adaptive filter based on reference signals from an electrooculogram (EOG) can reduce ocular interference, but collecting EOG signals during a long-term EEG recording is inconvenient and uncomfortable for the subject. To remove ocular artifacts from EEG in brain-computer interfaces (BCIs), a method named spatial constraint independent component analysis based recursive least squares (SCICA-RLS) is proposed. The method consists of two stages. In the first stage, independent component analysis (ICA) is used to decompose multiple EEG channels into an equal number of independent components (ICs). Ocular ICs are identified by an automatic artifact detection method based on kurtosis. Then empirical mode decomposition (EMD) is employed to remove any cerebral activity from the identified ocular ICs to obtain exact artifact ICs. In the second stage, first, SCICA applies exact artifact ICs obtained in the first stage as a constraint to extract artifact ICs from the given EEG signal. These extracted ICs are called spatial constraint ICs (SC-ICs). Then the RLS based adaptive filter uses SC-ICs as reference signals to reduce interference, which avoids the need for parallel EOG recordings. In addition, the proposed method has the ability of fast computation as it is not necessary for SCICA to identify all ICs like ICA. Based on the EEG data recorded from seven subjects, the new approach can lead to average classification accuracies of 3.3% and 12.6% higher than those of the standard ICA and raw EEG, respectively. In addition, the proposed method has 83.5% and 83.8% reduction in time-consumption compared with the standard ICA and ICA-RLS, respectively, which demonstrates a better and faster OA reduction.

关键词： Ocular artifacts     Electroencephalogram (EEG)     Electrooculogram (EOG)     Brain-computer interface (BCI)     Spatial constraint independent component analysis based recursive least squares (SCICA-RLS)    

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工程监理委托代理关系中激励约束与参与约束的研究

秦旋

《中国工程科学》 2007年 第9卷 第4期   页码 45-49

摘要：

基于委托－代理理论对工程监理委托－代理关系中的激励约束与参与约束进行若干拓展研究，与参 与约束（IR）相比，激励相容约束（IC）更为重要，一个机制不满足激励约束，那将是一个无效机制。业主想要 提高工程监理制度的运作效率，就必须通过相应的激励措施诱使工程师努力工作，使“道德风险”得以抑制， 为我国工程监理制度的健康发展提供了有益的启示。

关键词： 工程监理     业主     工程师     委托代理     激励相容约束     参与约束    

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Changes of ecological conditions induced by rock tunneling in Laoshan Mountain area

LI Xiaozhao, ZHAO Xiaobao, WANG Zhongsheng

《结构与土木工程前沿（英文）》 2008年 第2卷 第4期   页码 366-370 doi: 10.1007/s11709-008-0056-0

摘要： Through field investigation, this paper examined the changes of ecological conditions induced by tunnel construction in Laoshan Mountain area, Nanjing, Jiangsu Province, P. R. China. The effects of habitat fragmentation and edge effect are examined and discussed. It is found that the environmental factors and vegetation situation have been influenced by the tunneling activity, and the disturbed area is approaching the sampling patch centre. The changed ecological conditions are beneficial for the settlement and growth of some herb and shrub species, and are unfavorable for the existence and growth of saplings, especially for the predominant species (e.g., robur) in this area. If the time of habitat fragmentation is long enough and there is no supplement from external areas, some vegetation species in the engineering influencing area will deteriorate, or even diminish in the future. The results can be used as a reference for the long-term ecological study in this area.

关键词： supplement     fragmentation     reference     tunneling activity     vegetation situation    

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Research on the influence of contact surface constraint on mechanical properties of rock-concrete composite

Baoyun ZHAO, Yang LIU, Dongyan LIU, Wei HUANG, Xiaoping WANG, Guibao YU, Shu LIU

《结构与土木工程前沿（英文）》 2020年 第14卷 第2期   页码 322-330 doi: 10.1007/s11709-019-0594-7

摘要： The contact form of rock-concrete has a crucial influence on the failure characteristics of the stability of rock-concrete engineering. To study the influence of contact surface on the mechanical properties of rock-concrete composite specimens under compressive loads, the two different contact forms of rock-concrete composite specimens are designed, the mechanical properties of these two different specimens are analyzed under triaxial compressive condition, and analysis comparison on the stress-strain curves and failure forms of the two specimens is carried out. The influence of contact surface constraint on the mechanical properties of rock-concrete composite specimens is obtained. Results show that the stress and strain of rock-concrete composite specimens with contact surface constraint are obviously higher than those without. Averagely, compared with composite specimens without the contact surface, the existence of contact surface constraint can increase the axial peak stress of composite specimens by 24% and the axial peak strain by 16%. According to the characteristics of the fracture surface, the theory of microcrack development is used to explain the contact surface constraint of rock-concrete composite specimens, which explains the difference of mechanical properties between the two rock-concrete composite specimens in the experiment. Research results cannot only enrich the research content of the mechanics of rock contact, but also can serve as a valuable reference for the understanding of the corresponding mechanics mechanism of other similar composite specimens.

关键词： rock-concrete     composite specimen     contact surface     mechanical properties     failure mechanism    

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risk explicit interval linear programming approach for optimal watershed load reduction with objective-constraint

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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Chord error constraint based integrated control strategy for contour error compensation

Tie ZHANG, Caicheng WU, Yanbiao ZOU

《机械工程前沿（英文）》 2020年 第15卷 第4期   页码 645-658 doi: 10.1007/s11465-020-0601-7

摘要： As the traditional cross-coupling control method cannot meet the requirements for tracking accuracy and contour control accuracy in large curvature positions, an integrated control strategy of cross-coupling contour error compensation based on chord error constraint, which consists of a cross-coupling controller and an improved position error compensator, is proposed. To reduce the contour error, a PI-type cross-coupling controller is designed, with its stability being analyzed by using the contour error transfer function. Moreover, a feed rate regulator based on the chord error constraint is proposed, which performs speed planning with the maximum feed rate allowed by the large curvature position as the constraint condition, so as to meet the requirements of large curvature positions for the chord error. Besides, an improved position error compensation method is further presented by combining the feed rate regulator with the position error compensator, which improves the tracking accuracy via the advance compensation of tracking error. The biaxial experimental results of non-uniform rational B-splines curves indicate that the proposed integrated control strategy can significantly improve the tracking and contour control accuracy in biaxial contour following tasks.

关键词： cross-coupling controller     contour error     tracking error     position error compensator     feed rate regulator    

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Multi-scale UDCT dictionary learning based highly undersampled MR image reconstruction using patch-based constraint

Min YUAN,Bing-xin YANG,Yi-de MA,Jiu-wen ZHANG,Fu-xiang LU,Tong-feng ZHANG

《信息与电子工程前沿（英文）》 2015年 第16卷 第12期   页码 1069-1087 doi: 10.1631/FITEE.1400423

摘要： Recently, dictionary learning (DL) based methods have been introduced to compressed sensing magnetic resonance imaging (CS-MRI), which outperforms pre-defined analytic sparse priors. However, single-scale trained dictionary directly from image patches is incapable of representing image features from multi-scale, multi-directional perspective, which influences the reconstruction performance. In this paper, incorporating the superior multi-scale properties of uniform discrete curvelet transform (UDCT) with the data matching adaptability of trained dictionaries, we propose a flexible sparsity framework to allow sparser representation and prominent hierarchical essential features capture for magnetic resonance (MR) images. Multi-scale decomposition is implemented by using UDCT due to its prominent properties of lower redundancy ratio, hierarchical data structure, and ease of implementation. Each sub-dictionary of different sub-bands is trained independently to form the multi-scale dictionaries. Corresponding to this brand-new sparsity model, we modify the constraint splitting augmented Lagrangian shrinkage algorithm (C-SALSA) as patch-based C-SALSA (PB C-SALSA) to solve the constraint optimization problem of regularized image reconstruction. Experimental results demonstrate that the trained sub-dictionaries at different scales, enforcing sparsity at multiple scales, can then be efficiently used for MRI reconstruction to obtain satisfactory results with further reduced undersampling rate. Multi-scale UDCT dictionaries potentially outperform both single-scale trained dictionaries and multi-scale analytic transforms. Our proposed sparsity model achieves sparser representation for reconstructed data, which results in fast convergence of reconstruction exploiting PB C-SALSA. Simulation results demonstrate that the proposed method outperforms conventional CS-MRI methods in maintaining intrinsic properties, eliminating aliasing, reducing unexpected artifacts, and removing noise. It can achieve comparable performance of reconstruction with the state-of-the-art methods even under substantially high undersampling factors.

关键词： Compressed sensing (CS)     Magnetic resonance imaging (MRI)     Uniform discrete curvelet transform (UDCT)     Multi-scale dictionary learning (MSDL)     Patch-based constraint splitting augmented Lagrangian shrinkage algorithm (PB C-SALSA)    

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Assessing artificial neural network performance for predicting interlayer conditions and layer modulus

Lingyun YOU, Kezhen YAN, Nengyuan LIU

《结构与土木工程前沿（英文）》 2020年 第14卷 第2期   页码 487-500 doi: 10.1007/s11709-020-0609-4

摘要： The objective of this study is to evaluate the performance of the artificial neural network (ANN) approach for predicting interlayer conditions and layer modulus of a multi-layered flexible pavement structure. To achieve this goal, two ANN based back-calculation models were proposed to predict the interlayer conditions and layer modulus of the pavement structure. The corresponding database built with ANSYS based finite element method computations for four types of a structure subjected to falling weight deflectometer load. In addition, two proposed ANN models were verified by comparing the results of ANN models with the results of PADAL and double multiple regression models. The measured pavement deflection basin data was used for the verifications. The comparing results concluded that there are no significant differences between the results estimated by ANN and double multiple regression models. PADAL modeling results were not accurate due to the inability to reflect the real pavement structure because pavement structure was not completely continuous. The prediction and verification results concluded that the proposed back-calculation model developed with ANN could be used to accurately predict layer modulus and interlayer conditions. In addition, the back-calculation model avoided the back-calculation errors by considering the interlayer condition, which was barely considered by former models reported in the published studies.

关键词： asphalt pavement     interlayer conditions     finite element method     artificial neural network     back-calculation    

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Influence of initial curing conditions and exposure environments on chloride migration in concrete using

Wen XUE, Weiliang JIN, Hiroshi YOKOTA,

《结构与土木工程前沿（英文）》 2010年 第4卷 第3期   页码 348-353 doi: 10.1007/s11709-010-0077-3

摘要： To investigate the influence of initial curing conditions and exposure environments on chloride ions’ migration in concrete, the specimens that were cured in different conditions and placed in several marine environments were studied. The amount of chloride ions passing through the specimen’s section was monitored in the accelerated chloride migration test. The effective chloride diffusion coefficients () were calculated from the steady-state on the basis of Nernst-Planck’s equation. The results indicated that the initial curing conditions and the wet-dry interval of external environments have coupling influence on effective diffusion coefficient of chloride ion significantly. reflected the density and pore connectivity of concrete. The co-effects of the initial curing condition and following exposure environment should be taken into account in durability design for concrete structure located in marine environment.

关键词： durability     effective diffusion coefficient     steady-state     migration test    

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标题 作者 时间 类型 操作

Novel method of constructing generalized Hoberman sphere mechanisms based on deployment axes

Xuemin SUN, Yan-An YAO, Ruiming LI

期刊论文

Technology and system of constraint programming for industry production scheduling

Yarong CHEN, Zailin GUAN, Yunfang PENG, Xinyu SHAO, Muhammad HASSEB

期刊论文

Recent development in low-constraint fracture toughness testing for structural integrity assessment of

Jidong KANG, James A. GIANETTO, William R. TYSON

期刊论文

Development of rocking constraint device with vertical damping capacity for three-dimensional base-isolated

期刊论文

Research on constraint-based virtual assembly technologies

YANG Rundang, WU Dianliang, FAN Xiumin, YAN Juanqi

期刊论文

Topology optimization of transient problem with maximum dynamic response constraint using SOAR scheme

期刊论文

Fast removal of ocular artifacts from electroencephalogram signals using spatial constraint independent

Bang-hua YANG,Liang-fei HE,Lin LIN,Qian WANG

期刊论文

工程监理委托代理关系中激励约束与参与约束的研究

秦旋

期刊论文

Changes of ecological conditions induced by rock tunneling in Laoshan Mountain area

LI Xiaozhao, ZHAO Xiaobao, WANG Zhongsheng

期刊论文

Research on the influence of contact surface constraint on mechanical properties of rock-concrete composite

Baoyun ZHAO, Yang LIU, Dongyan LIU, Wei HUANG, Xiaoping WANG, Guibao YU, Shu LIU

期刊论文

risk explicit interval linear programming approach for optimal watershed load reduction with objective-constraint

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

期刊论文

Chord error constraint based integrated control strategy for contour error compensation

Tie ZHANG, Caicheng WU, Yanbiao ZOU

期刊论文

Multi-scale UDCT dictionary learning based highly undersampled MR image reconstruction using patch-based constraint

Min YUAN,Bing-xin YANG,Yi-de MA,Jiu-wen ZHANG,Fu-xiang LU,Tong-feng ZHANG

期刊论文

Assessing artificial neural network performance for predicting interlayer conditions and layer modulus

Lingyun YOU, Kezhen YAN, Nengyuan LIU

期刊论文

Influence of initial curing conditions and exposure environments on chloride migration in concrete using

Wen XUE, Weiliang JIN, Hiroshi YOKOTA,

期刊论文