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Skeleton-Based Human Action Recognition via Screw Matrices

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Chinese Journal of Electronics 2017年第4期26卷 790-796页

作者： DING Wenwen LIU Kai XU Biao cheng fei School of Computer Science and Technology Xidian University School of Mathematical Sciences Huaibei Normal University

With the recent advent of low-cost acquisition depth cameras, extracting 3D body skeleton has become relatively easier, which significantly lighten many difficulties in 2D videos including occlusions, shadows and background extraction, etc. Directly perceived features,for example points, lines and planes, can be easily extracted from 3D videos such that we can employ rigid motions to represent skeletal motions in a geometric *** apply screw matrices, acquired by using rotations and translations in 3D space, to model single and multi-body rigid motion. Since screw matrices are members of the special Euclidean group SE(3), an action can be represented as a point on a Lie group, which is a differentiable manifold. Using Lie-algebraic properties of screw algebra, isomorphic to se(3), the classical algorithms of machine learning in vector space can be expanded to manifold space. We evaluate our approached on three public3 D action datasets: MSR Action3 D dataset, UCF Kinect dataset and Florence3D-Action Dataset. The experimental results show that our approaches either match or exceed state-of-the-art skeleton-based human action recognition approaches.

关键词： Skeleton joints Human activity recogni tion Screw algebra Lie group Lie algebra

Controllable synthesis of high loading LiFePO_4/C nanocomposites using bimodal mesoporous carbon as support for high power Li-ion battery cathodes

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Journal of Energy Chemistry 2013年第6期22卷 907-913页

作者： fei cheng Duo Li Anhui Lu Wencui Li State Key Laboratory of Fine Chemicals School of Chemical Engineering Faculty of Chemical Environmental and Biological Science and Technology Dalian University of Technology

Mesoporous LiFePO4/C composites containing 80 wt% of highly dispersed LiFePO4 nanoparticles(4-6 nm) were fabricated using bimodal mesoporous carbon(BMC) as continuous conductive networks. The unique pore structure of BMC not only promises good particle connectivity for LiFePO4, but also acts as a rigid nano-confinement support that controls the particle size. Furthermore, the capacities were investigated respectively based on the weight of LiFePO4 and the whole composite. When calculated based on the weight of the whole composite, it is 120 mAh·g-1at 0.1 C of the high loading electrode and 42 mAh·g-1at 10 C of the low loading electrode. The electrochemical performance shows that high LiFePO4 loading benefits large tap density and contributes to the energy storage at low rates, while the electrode with low content of LiFePO4 displays superior high rate performance, which can mainly be due to the small particle size, good dispersion and high utilization of the active material, thus leading to a fast ion and electron diffusion.

关键词： LiFePO4 high loading fast ion diffusion high rate performance lithium-ion batteries

Loop Subgraph-Level Greedy Mapping Algorithm for Grid Coarse-Grained Reconfigurable Array

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Tsinghua Science and Technology 2023年第2期28卷 330-343页

作者： Naijin Chen fei cheng chenghao Han Jianhui Jiang Xiaoqing Wen School of Computer and Information Science Anhui Polytechnic UniversityWuhu 241000China School of Software Engineering Tongji UniversityShanghai 201804China Department of Computer Science and Networks Kyushu Institute of TechnologyFukuoka 820-8502Japan

To solve the problem of grid coarse-grained reconfigurable array task mapping under multiple constraints,we propose a Loop Subgraph-Level Greedy Mapping(LSLGM)algorithm using parallelism and processing element *** the constraint of a reconfigurable array,the LSLGM algorithm schedules node from a ready queue to the current reconfigurable cell array *** mapping a node,its successor’s indegree value will be dynamically *** its successor’s indegree is zero,it will be directly scheduled to the ready queue;otherwise,the predecessor must be dynamically *** the predecessor cannot be mapped,it will be scheduled to a blocking *** dynamically adjust the ready node scheduling order,the scheduling function is constructed by exploiting factors,such as node number,node level,and node *** with the loop subgraph-level mapping algorithm,experimental results show that the total cycles of the LSLGM algorithm decreases by an average of 33.0%(PEA44)and 33.9%(PEA_(7×7)).Compared with the epimorphism map algorithm,the total cycles of the LSLGM algorithm decrease by an average of 38.1%(PEA_(4×4))and 39.0%(PEA_(7×7)).The feasibility of LSLGM is verified.

关键词： Grid Coarse-Grained Reconfigurable Array(GCGRA) mapping loop subgraph scheduling

Improvement of interleaving Aramid pulp microfibers on compressive strengths of carbon fiber reinforced polymers with and without impact

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Chinese Journal of Aeronautics 2023年第10期36卷 459-470页

作者： fei cheng Guangming YANG Yunsen HU Bingyan YUAN Xiaozhi HU School of Materials Science and Engineering Southwest University of Science and TechnologyMianyang 621010China Engineering Research Center of Biomass Materials Ministry of EducationSouthwest University of Science and TechnologyMianyang 621010China Department of Mechanical Engineering University of Western AustraliaPerth WA6009Australia

Compressive strengths and elastic moduli of Carbon Fiber Reinforced Polymer(CFRP)composites can be noticeably improved by multiple ultra-thin interlays with non-woven Aramid Pulp(AP)micro/nano-fibers.10-ply CFRP specimens with 0,2,4,6,8 g/m^(2)AP were tested under uniaxial *** flexible AP fibers,filling the resin-rich regions and further constructing the fiber bridging at the ply interfaces,can effectively suppress delamination growth and lead to very good improvements both in the compressive strength and the elastic *** CFRP specimen with an optimum interlay thickness has a distinct shear failure mode instead of the typical delamination cracking along the direction of continuous carbon *** Strengths After Impacts(CAI)of 12.35 J were also measured,up to 90%improvement in CAI has been *** is concluded those ultra-thin interlays of non-woven AP micro/nano-fibers are beneficial to design and manufacture“high strength”CFRP composites.

关键词： Compressive strength Carbon Fiber Reinforced Polymer(CFRP) Aramid pulp Interleaving Interfacial reinforcing

Enhancing adhesive bond strength of CFRP/titanium joints through NaOH anodising and resin pre-coating treatments with optimised anodising conditions

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Chinese Journal of Aeronautics 2024年第2期37卷 511-523页

作者： Yunsen HU Jingheng ZHANG Lin WANG fei cheng Xiaozhi HU School of Materials and Chemistry Southwest University of Science and TechnologyMianyang 621000China School of Mechanical Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China Engineering Research Center of Biomass Materials Ministry of EducationSouthwest University of Science and TechnologyMianyang 621010China Department of Mechanical Engineering University of Western AustraliaPerthWA 6009Australia

Adhesively Bonded Carbon Fibre Reinforced Plastic(CFRP)and titanium alloy have been extensively used as a hybrid structure in modern aircrafts due to their excellent combination of mechanical properties and chemical *** study utilised NaOH anodising method to create micro-rough titanium surfaces for enhancing adhesive bonding between titanium alloy and CFRP laminates.A special and simple technique named Resin Pre-Coating(RPC)was also employed to improve the surface wetting of anodised titanium and grinded CFRP *** influences of anodising temperature and duration on the surface morphology,wettability and adhesive bond strength were *** single lap shear test results showed that the bond strength of specimens anodised at 20℃for 15 min improved by 135.9%and 95.4%,respectively,in comparison with that of acid pickled and grinded specimens(without RPC treatment).Although increasing the anodising temperature and duration produced rougher titanium surfaces,the adhesively bonded joints were not strong enough due to relatively friable titanium oxide layers.

关键词： Carbon Fibre Reinforced Polymer(CFRP) Titanium alloy Anodising Resin pre-coating Adhesive joints

Crack detection for wading-concrete structures using water irrigation and electric heating

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Frontiers of Structural and Civil Engineering 2023年第3期17卷 368-377页

作者： Jiang CHEN Zizhen ZENG Ying LUO Feng XIONG fei cheng Failure Mechanics and Engineering Disaster Prevention Key Laboratory of Sichuan Province Sichuan UniversityChengdu 610065China MOE Key Laboratory of Deep Earth Science and Engineering Sichuan UniversityChengdu 610065China College of Architecture and Environment Sichuan UniversityChengdu 610065China College of Biomass Science and Engineering Sichuan UniversityChengdu 610065China

Cracking in wading-concrete structures has a worse impact on structural safety compared with conventional concrete *** accurate and timely monitoring of crack development plays a significant role in the safety of wading-concrete *** heat-transfer rate near a crack is related to the flow velocity of the fluid in the *** on this,a novel crack-identification method for underwater concrete structures is *** method uses water irrigation to generate seepage at the interface of a crack;then,the heat-dissipation rate in the crack area will increase because of the convective heat-transfer effect near the *** information can be identified by monitoring the cooling law and leakage flow near *** proposed mobile crack-monitoring system consists of a heating system,temperature-measurement system,and irrigation system.A series of tests was conducted on a reinforcedconcrete beam using this *** crack-discrimination indexψwas defined,according to the subsection characteristics of the heat-source cooling *** effects of the crack width,leakage flow,and relative positions of the heat source and crack onψwere *** results showed that the distribution characteristics ofψalong the monitoring line could accurately locate the crack,but not quantify the crack ***,the leakage flow is sensitive to the crack width and can be used to identify it.

关键词： structural health monitoring underwater concrete structure fiber Bragg grating crack detection temperature tracer method

Some Bonnesen-style Inequalities for Higher Dimensions

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Acta Mathematica Sinica,English Series 2012年第12期28卷 2561-2568页

作者： Jia Zu ZHOU Yan Hua DU fei cheng School of Mathematics and Statistics Southwest University Southeast Guizhou Vocational College of Technology for Nationalities

We discuss the higher dimensional Bonnesen-style inequalities. Though there are many Bonnesen-style inequalities for domains in the Euclidean plane R2 few results for general domain in Rn （n ≥ 3） are known. The res... 详细信息

关键词： Convex domain the isoperimetric deficit the isoperimetric inequality the Bonnesen-style inequality

Comparative Case Study on Adhesion of Three Common Sizing Agents to Cotton and Polyester Yarns

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Journal of Wuhan University of Technology(Materials Science) 2021年第2期36卷 157-165页

作者： LI Ying HU Xiao cheng fei ZHOU Mi ZHU Puxin College of Biomass Science and Engineering Sichuan UniversityChengdu 610065China School of Textile Engineering Chengdu Textile CollegeChengdu 611731China Sichuan Zhukang New Material Co. Chengdu 611534China

The adhesion between warp sizing and fiber was systematically studied by using the roving *** roving and polyester roving were sized with various concentrations between 0.01%and 2.50%of acid-thinned starch,polyvinyl alcohol and water-soluble polyester sizing,respectively,and tensile property of the sized roving was tested *** break force of the sized roving was considered as the adhesion force of the sizing to the fiber in the roving *** experimental results show that the effects of sizing film strength and fiber strength on the adhesive force can be weakened when the concentration 0.5%of size paste is used,instead of 1%in the roving *** size morphology in the sized roving and on the surface was observed through scanning electron microscopy,in the form of penetration and coverage of the sizing in or on the *** the other hand,the Young-Dupréequation was used to calculate the adhesion *** advantages and disadvantages of roving method and the adhesion work method were *** adhesion obtained by both two methods reflects the rule of chemical similarity between warp sizing and fiber.

关键词： sizing agent adhesion analysis roving method adhesion work

Effect of Microfibrillated Cellulose Loading on Physical Properties of Starch/Polyvinyl Alcohol Composite Films

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Journal of Wuhan University of Technology(Materials Science) 2020年第4期35卷 825-831页

作者： TIAN Yu ZHU Puxin ZHOU Mi LIN Yi cheng fei College of Biomass Science and Engineering Sichuan UniversityChengdu 610065China

The starch/polyvinyl alcohol(PVA)/microfibrillated cellulose(MFC)composite films were prepared using solution casting method after adding MFC into starch/PVA blend *** effects of MFC content on the mechanical properties of starch/PVA composite films were *** MFC content increases,the elongation at break and tensile strength increase firstly and then *** the content of MFC is 2wt%,the tensile strength is 26.6 MPa and reaches the *** Fourier transform infrared(FTIR),scanning electron microscopy(SEM),X-ray diffraction(XRD)and thermogravimetric analysis(TGA),good dispersion of MFC in starch/PVA matrix at the loading of 2wt%,lower crystallinity of the starch/PVA/MFC films in comparison with starch/PVA blend and the effect of glass transition temperature increasing with MFC content from 0.5wt%to 4wt%can be found ***,incorporating MFC does not change the composition and crystal structure of the starch/PVA composite ***,the reinforcing mechanism for the improvement of mechanical properties is attributed to the homogeneous dispersion of MFC with large aspect ratio,good compatibility and interfacial interactions between starch/PVA blend matrix and MFC.

关键词： biopolymers fillers blends composites mechanical properties