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An Approach to Assembly Sequence Plannning Based on hierarchical strategy and Genetic Algorithm

Computer Aided Drafting,Design and Manufacturing 2001年第2期11卷 8-14页

作者： Niu Xinwen ,Ding Han,Xiong Youlun School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China Manufacturing and Production School of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China

Using group and subassembly cluster methods, the hierarchical structure of a product is ?generated automatically, which largely reduces the complexity of planning. Based on genetic algorithm, the optimal of assembly sequence of each structure level can be obtained by sequence-by-sequence search. As a result, a better assembly sequence of the product can be generated by combining the assembly sequences of all hierarchical structures, which provides more parallelism and flexibility for assembly operations. An industrial example is solved by this new approach.

关键词： assembly sequence planning hierarchical strategy genetic algorithm

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Mapping impervious surfaces with a hierarchical spectral mixture analysis incorporating endmember spatial distribution

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Geo-Spatial Information Science 2022年第4期25卷 550-567页

作者： Zhenfeng Shao Yuan Zhang Cheng Zhang Xiao Huang Tao Cheng State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhanChina Department of Geosciences University of ArkansasFayettevilleARUSA

Impervious surface mapping is essential for urban environmental *** Mixture Analysis(SMA)and its extensions are widely employed in impervious surface estimation from medium-resolution *** SMA,inappropriate endmember combinations and inadequate endmember classes have been recognized as the primary reasons for estimation ***,the spectral-only SMA,without considering urban spatial distribution,fails to consider spectral variability in an adequate *** lack of endmember class diversity and their spatial variations lead to over/*** mitigate these issues,this study integrates a hierarchical strategy and spatially varied endmember spectra to map impervious surface abundance,taking Wuhan and Wuzhou as two study ***,the piecewise convex multiple-model endmember detection algorithm is applied to automatically hierarch-ize images into three regions,and distinct endmember combinations are independently developed in each ***,spatially varied endmember spectra are synthesized through neighboring spectra using the distance-based *** analysis indicates that the proposed method achieves better performance than hierarchical SMA and Fixed Four-endmembers SMA in terms of MAE,SE,and *** analysis suggests that the hierarch-ical strategy can expand endmember class types and considerably improve the performance for the study areas in general,specifically in less developed ***,we find that spatially varied endmember spectra facilitate the reduction of heterogeneous surface material variations and achieve the improved performance in developed areas.

关键词： Impervious surface Spectral Mixture Analysis(SMA) hierarchical strategy endmember class spatially varied endmember spectra

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hierarchical MPS-Based Three-Dimensional Geological Structure Reconstruction with Two-Dimensional Image(s)

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Journal of Earth Science 2021年第2期32卷 455-467页

作者： Weisheng Hou Hengguang Liu Tiancheng Zheng Wenjie Shen Fan Xiao School of Earth Sciences and Engineering Sun Yat-Sen UniversityGuangzhou 510275China Guangdong Provincial Key Lab of Geodynamics and Geohazards Guangzhou 510275China Southern Marine Science and Engineering Guangdong Laboratory Zhuhai 519000China

Multiple-point statistics(MPS)is a useful approach to reconstruct three-dimensional models in the macroscopic or microscopic *** spatial features for three-dimensional reconstruction from two-dimensional training images(TIs),and characterizing non-stationary features with directional ductility are two key issues in MPS *** study presents a step-wise MPS-based three-dimensional structures reconstruction algorithm with the sequential process and hierarchical strategy based on two-dimensional *** extension method is proposed to construct three-dimensional *** a sequential simulation process,an initial guess at the coarsest scale is simulated,in which hierarchical strategy is used according to the characteristics of *** obtain a more refined realization,an expectation-maximization like iterative process with global optimization is implemented.A concrete example of chondrite micro-structure simulation,in which one scanning electron microscopy(SEM)image of the Heyetang meteorite is used as TI,shows that the presented algorithm can simulate complex non-stationary structures.

关键词： multiple-point statistics hierarchical strategy chondrite two-dimensional image(s)

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