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Pose-free assembly retrieval based on spatial-contact skeleton

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Chinese Journal of Aeronautics 2022年第4期35卷 497-507页

作者： jianfeng yu Jiazhen PANG Jie ZHANG yuan LI School of Mechanical Engineering Northwestern Polytechnical UniversityXi'an 710072China

In complicated product industry such as aircraft manufacturing, an assembly model contains abundant engineering information for use in design, manufacture, and maintenance. Assembly retrieval can be used to find relevant models for knowledge reuse. However, an assembly with rotatable joints may have many poses, which brings difficulty to assembly retrieval, since there is no pose principle for assembly design. Therefore, focused on rotatable joints in assembly, a skeleton-based descriptor for pose-free assembly retrieval is proposed. The centroid points of part surfaces and contact faces in an assembly are extracted to construct a spatial-contact skeleton. The skeletonbased distance is proposed to measure the distance between two surface points, which is invariant to the rotatable joints. The distribution of skeleton distances between two parts is used to describe the pair. Considering a part paired with all other parts in the assembly, the set of part pairs is used to represent a part, and the modified Hausdorff distance is used to measure the dissimilarity between parts for assembly retrieval. Experiments are conducted to compare the accuracy of the proposed descriptor to holistic and structureless descriptors. The proposed method is shown to retrieve assemblies with similar parts and structures regardless of their rotatable joints.

关键词： Assembly retrieval Computer-aided design(CAD) Rotation connection Similarity measure Spatial-contact skeleton

CAD mesh model simplification with assembly features preservation

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Science China(Information Sciences) 2014年第3期57卷 119-129页

作者： XIAO Hong LI yuan yu jianfeng ZHANG Jie The Key Laboratory of Contemporary Design and Integrated Manufacturing Technology Ministry of EducationNorthwestern Polytechnical University

This paper aims to investigate a CAD mesh model simplification method with assembly features preservation,in order to satisfy the requirement of assembly field for the information of 3D *** proposed method simplifies a CAD mesh model as ***,the notion of"conjugation"is incorporated into the definition of assembly features,with the purpose of benefitting the downstream applications such as assembly features recognition and ***,the attributed adjacency graphs(AAGs)of the regionlevel-represented parts are *** assembly features are automatically recognized by searching for conjugated subgraphs of every two AAGs based on subgraph isomorphism *** order to improve the efciency of assembly features recognition,the characteristics of conjugated subgraphs are adopted to initialize the mapping matrix,and the"verifying while matching strategy"is used to verify the validity of every two newly founded vertices which are correspondingly ***,simplified CAD mesh model with assembly features preserved is constructed after suppressing the common form *** method is applied successfully to simplify the CAD mesh model with assembly features well ***,the tradeof between the cost of time for conjugated subgraphs matching and the complexity of the to-be-matched parts is proven to be almost linear.

关键词： CAD mesh model model simplification assembly features feature recognition subgraph isomorphism

Mtuli-objective Optimization Method for Automatic Drilling and Riveting Sequence Planning

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Chinese Journal of Aeronautics 2010年第6期23卷 734-742页

作者： Xiao Hong Li yuan Zhang Kaifu yu jianfeng Liu Zhenxing Su Jianbin The Key Laboratory of Contemporary Design and Integrated Manufacturing Technology Ministry of Education School of Mechatronics Northwestern Polytechnical Universitry Xi 'an 710072 China Xi 'an Aircaft Industry (Group) Co. Ltd. Xi 'an 710089 China

There are numerous riveting points on the large-sized aircraft panel, irregular row of riveting points on delta wing. It is essential to plan the riveting sequence reasonably to improve the efficiency and accuracy of automatic drilling and riveting. Therefore, this article presents a new multi-objective optimization method based on ant colony optimization （ACO）. Multi-objective optimization model of automatic drilling and riveting sequence planning is built by expressing the efficiency and accuracy of riveting as functions of the points＇ coordinates. In order to search the sequences efficiently and improve the quality of the sequences, a new local pheromone updating rule is applied when the ants search sequences. Pareto dominance is incorporated into the proposed ACO to find out the non-dominated sequences. This method is tested on a hyperbolicity panel model of ARJ21 and the result shows its feasibility and superiority compared with particle swarm optimization （PSO） and genetic algorithm （GA）.

关键词： automatic drilling and riveting riveting sequence multi-objective optimization ant colony optimization Paretooptimal solutions

Coordination control method to block cascading failure of a renewable generation power system under line dynamic security

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Protection and Control of Modern Power Systems 2023年第1期8卷 194-204页

作者： Jinxin Ouyang jianfeng yu Xiaoxuan Long Yanbo Diao Jian Wang State Key Laboratory of Power Transmission Equipment and System Security and New Technology School of Electrical EngineeringChongqing UniversityChongqingChina Information and Communication Branch of State Grid Chongqing Electric Power CompanyChongqingChina Chongqing City Management College ChongqingChina

The large application of renewable energy generation(REG)has increased the risk of cascading failures in the power *** the same time REG also provides the possibility of new approaches for the suppression of such ***,the capacity and position of the synchronous generator(SG)involved in regulation limit the power regu-lation speed(PRS)of REG to the overload line which is the main cause of cascading failures,while the PRS of SG is related to the position and shedding *** and SGs have difficulty in achieving effective cooperation under constraints of system power ***,the dynamic variation of line flow during power regulation causes new problems for the accurate evaluation of line thermal safety under ***,a new strategy for quan-titatively coordinating shedding power and power regulation to block cascading failures in the dynamic security domain is proposed in this *** control capability and dynamic security domain of the overload line are mod-eled,and the coordination control method based on power regulation is then proposed to minimize shedding *** algorithm for the optimal control scheme considers the constraints of load capacity,power source capacity and bus *** correctness of the proposed method is verified using case studies.

关键词： Cascading failures Overload Shedding power Power regulation Thermal stability

New method for the preparation of adsorbent with high adsorption capacity

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Chinese Science Bulletin 2005年第21期50卷 2432-2435页

作者： WANG Yongjian LIU jianfeng DUO Jia yu Yaoting Key Laboratory of Bioactive Materials Ministry of Education Nankai University Tianjin 300071 China

Polyamidoamine (PAMAM) is a type of macro- molecule having a definite chemical structure and a large number of terminal functional groups. The synthetic ap-proach of the adsorbent with high adsorption capacity in-volved arching of PAMAM onto cellulose beads by reaction with epichlorohydrin. The product thus prepared had a large number of amino groups of 2.94 mmol/g derived from 0.23 mmol/g epoxy groups on cellulose beads. This method pre-sents an effective method for the preparation of high-loading adsorbents.

关键词： PAMAM 高分子化合物化学结构吸附性纤维素

Association of Psb28 and Psb27 Proteins with PSII-PSI Supercomplexes upon Exposure of Synechocystis sp. PCC 6803 to High Light

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Molecular Plant 2017年第1期10卷 62-72页

作者： Martina Beckova Zdenko Gardian jianfeng yu Peter Konik Peter J. Nixon Josef Komenda Institute of Microbiology Center Algatech Opatovicky mlyn37981 Trebon Czech Republic Faculty of Science University of South Bohemia Branisovska 1760 37005 Ceske Budejovice Czech Republic Institute of Plant Molecular Biology Biology Centre Academy of Sciences Branisovska 3137005 Ceske Budejovice Czech Republic Sir Ernst Chain Building-Wolfson Laboratories Department of Life Sciences Imperial College London South Kensington Campus London SW7 2AZ UK

Formation of the multi-subunit oxygen-evolving photosystem II （PSII） complex involves a number of auxiliary protein factors. In this study we compared the localization and possible function of two homolo- gous PSU assembly factors, Psb28-1 and Psb28-2, from the cyanobacterium Synechocystis sp. PCC 6803. We demonstrate that FLAG-tagged Psb28-2 is present in both the monomeric PSII core complex and a PSII core complex lacking the inner antenna CP43 （RC47）, whereas Psb28-1 preferentially binds to RC47. When cells are exposed to increased irradiance, both tagged Psb28 proteins additionally associate with oligo- meric forms of PSII and with PSII-PSI supercomplexes composed of trimeric photosystem I （PSI） and two PSII monomers as deduced from electron microscopy. The presence of the Psb27 accessory protein in these complexes suggests the involvement of PSI in PSII biogenesis, possibly by photoprotecting PSII through energy spillover. Under standard culture conditions, the distribution of PSII complexes is similar in the wild type and in each of the single psb28 null mutants except for loss of RC47 in the absence of Psb28-1. In comparison with the wild type, growth of mutants lacking Psb28-1 and Psb27, but not Psb28-2, was retarded under high-light conditions and, especially, intermittent high-light/dark conditions, emphasizing the physiological importance of PSII assembly factors for light acclimation.

关键词： Psb28 proteins photosystem I and II Synechocystis

Microwave-assisted molybdenum-nickel alloy for efficient water electrolysis under large current density through spillover and Fe doping

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Nano Research 2022年第7期15卷 5873-5883页

作者： Ya-Nan Zhou Hai-Jun Liu Zhuo-Ning Shi Jian-Cheng Zhou Bin Dong Hui-Ying Zhao Feng-Ge Wang jianfeng yu Yong-Ming Chai State Key Laboratory of Heavy Oil Processing College of Chemistry and Chemical EngineeringChina University of Petroleum(East China)Qingdao 266580China

The development of high-efficiency electrocatalysts for overall water splitting under large current density is significant and ***,a high-performing Fe-doped MoNi alloy catalyst(M-H-MoNiFe-50)abundant with flower-like nanorods assemblies has been prepared by high-pressure microwave reaction and hydrogen ***,Fe doped NiMoO_(4) precursor(M-MoNiFe-50)was synthesized by microwave fast heating,ensuring the robustness of nanorods,which owns larger area and improved catalytic activity than that by conventional hydrothermal ***,M-MoNiFe-50 was reduced in H_(2)/Ar to fabricate Fe-incorporated MoNi_(4) alloys(M-H-MoNiFe-50),greatly enhancing the conductivity and facilitating hydrogen/oxygen *** final M-H-MoNiFe-50 exhibits remarkable activity for alkaline/acidic hydrogen evolution reaction and oxygen evolution reaction with low overpotential of 208(alkaline),254(acid)and 347 mV at 1,000 mA·cm^(−2).Moreover,an alkaline water electrolyzer is established using M-H-MoNiFe-50 as anode and cathode,generating a current density of 100 mA·cm^(−2) at 1.58 V with encouraging durability of 50 h at 1,000 mA·cm^(−2).The extraordinary water splitting performance can be chalked up to the large surface area,favorable charge transfer,modified electron distribution,intrinsic robustness as well as an efficient gas spillover of *** final electrocatalyst has great prospects for practical application and confirms the significance of Fe doping,microwave method and spillover effect for catalytic performance improvement.

关键词： high-pressure microwave Fe doping MoNi_(4) spillover overall water splitting

FtsH4 protease controls biogenesis of the PSII complex by dual regulation of high light-inducible proteins

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Plant Communications 2023年第1期4卷 272-286页

作者： Vendula Krynická Petra Skotnicová Philip J.Jackson Samuel Barnett jianfeng yu Anna Wysocka Radek Kaña Mark J.Dickman Peter J.Nixon C.Neil Hunter Josef Komenda The Czech Academy of Sciences Institute of MicrobiologyCentre AlgatechNovohradská 23737901 TreboñCzech Republic Plants Photosynthesis and SoilSchool of BiosciencesUniversity of SheffieldSheffield S102TNUK Department of Chemical and Biological Engineering University of SheffieldSheffield S13JDUK Sir Ernst Chain Building-Wolfson Laboratories Department of Life SciencesSouth Kensington CampusImperial College LondonLondon SW72AZUK Faculty of Science University of South Bohemia37005 Ceské BudějoviceCzech Republic

FtsH proteases are membrane-embedded proteolytic complexes important for protein quality control and regulation of various physiological processes in bacteria,mitochondria,and *** most cyanobacteria,the model species Synechocystis *** 6803 contains four FtsH homologs,FtsH1–***1–FtsH3 form two hetero-oligomeric complexes,FtsH1/3 and FtsH2/3,which play a pivotal role in acclimation to nutrient deficiency and photosystem Ⅱ quality control,***4 differs from the other three homologs by the formation of a homo-oligomeric complex,and together with Arabidopsis thaliana AtFtsH7/9 orthologs,it has been assigned to another phylogenetic group of unknown *** results exclude the possibility that Synechocystis FtsH4 structurally or functionally substitutes for the missing or non-functional FtsH2 subunit in the FtsH2/3 ***,we demonstrate that FtsH4 is involved in the biogenesis of photosystem Ⅱ by dual regulation of high light-inducible proteins(Hlips).FtsH4 positively regulates expression of Hlips shortly after high light exposure but is also responsible for Hlip removal under conditions when their elevated levels are no longer *** provide experimental support for Hlips as proteolytic substrates of *** labeling of FtsH4 enabled us to assess its localization using advanced microscopic *** show that FtsH4 complexes are concentrated in well-defined membrane regions at the inner and outer periphery of the thylakoid *** on the identification of proteins that co-purified with the tagged FtsH4,we speculate that FtsH4 concentrates in special compartments in which the biogenesis of photosynthetic complexes takes place.

关键词： thylakoid photosystemⅡbiogenesis FtsH4 high light-inducible protein proteolysis

公募基金管理是否有效?——多因素的基金能力评价

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系统工程理论与实践 2022年第4期42卷 906-922页

作者：林兟何为余剑峰天津大学管理与经济学部天津300072 西南财经大学中国金融研究院成都611130 清华大学五道口金融学院北京100084

本文通过构建多因素的基金管理能力评价体系研究了我国开放式主动管理股票型公募基金的管理有效性.结果表明:1)公募基金在承担较低风险情况下可获取高于股票市场组合的超额收益率;2)基于历史收益和持仓数据构建的指标能有效预测基金的... 详细信息

本文通过构建多因素的基金管理能力评价体系研究了我国开放式主动管理股票型公募基金的管理有效性.结果表明:1)公募基金在承担较低风险情况下可获取高于股票市场组合的超额收益率;2)基于历史收益和持仓数据构建的指标能有效预测基金的未来表现;3)通过组合这些指标构建的基金管理能力评价体系,其择优基金未来表现显著优于现有基金评奖体系.这些结果表明,公募基金作为散户投资“机构化”的重要渠道,可以显著提高投资人的收益表现,且基金的管理能力可以被合理的评价体系事前甄别.本文为证明机构投资者在市场中的作用提供了新的证据和视角,提出的评价体系为帮助监管机构提高公募基金市场资金流配置有效性具有重要启示作用.

关键词：中国公募基金基金评价市场质量个体投资者