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Enhanced tribological properties of aligned graphene-epoxy composites

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Friction 2022年第6期10卷 854-865页

作者： Yuefeng DU Zhenyu ZHANG Dong WANG Lezhen ZHANG Junfeng CUI Yapeng CHEN Mingliang WU Ruiyang KANG Yunxiang LU Jinhong YU Nan JIANG Key Laboratory for Precision and Non-Traditional Machining Technology of Ministry of Education Dalian University of TechnologyDalian 116024China Beijing spacecrafts Manufacturing Factory Co. Ltd.China Academy of Space TechnologyBeijing 100094China Weichai Power Co. Ltd.Weifang 261061China Key Laboratory of Marine Materials and Related Technologies Zhejiang Key Laboratory of Marine Materials and Protective TechnologiesNingbo Institute of Materials Technology and Engineering(NIMTE)Chinese Academy of SciencesNingbo 315201China

The random distribution of graphene in epoxy matrix hinders the further applications of grapheneepoxy composites in the field of ***,in order to fully utilize the anisotropic properties of graphene,highly aligned graphene-epoxy composites(AGEC)with horizontally oriented structure have been fabricated via an improved vacuum filtration freeze-drying *** frictional tests results indicated that the wear rate of AGEC slowly increased from 5.19x10^(-6)mm^(3)/(N-m)to 2.87x10^(-5)mm^(3)/(N-m)with the increasing of the normal load from 2 to 10 N,whereas the friction coefficient(COF)remained a constant of *** to the neat epoxy and random graphene-epoxy composites(RGEC),the COF of AGEC was reduced by 87.5%and 71.2%,and the reduction of wear rate was 86.6%and 85.4%at most,*** electron microscope(SEM)observations illustrated that a compact graphene self-lubricant film was formed on the worn surface of AGEC,which enables AGEC to possess excellent tribological ***,in light of the excellent tribological properties of AGEC,this study highlights a pathway to expand the tribological applications of graphene-epoxy composites.

关键词： graphene aligned epoxy composite tribological performance

Optimization of assembly line balancing using genetic algorithm

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Journal of Central South University 2015年第10期22卷 3957-3969页

作者： N.Barathwaj P.Raja S.Gokulraj School of Mechanical Engineering SASTRA University Rane (Madras) ltd. Deputy Manager (Manufacturing Engineering System Design Department)

In a manufacturing industry, mixed model assembly line(MMAL) is preferred in order to meet the variety in product demand. MMAL balancing helps in assembling products with similar characteristics in a random fashion. The objective of this work aims in reducing the number of workstations, work load index between stations and within each station. As manual contribution of workers in final assembly line is more, ergonomics is taken as an additional objective function. Ergonomic risk level of a workstation is evaluated using a parameter called accumulated risk posture(ARP), which is calculated using rapid upper limb assessment(RULA) check sheet. This work is based on the case study of an MMAL problem in Rane(Madras) ltd.(India), in which a problem based genetic algorithm(GA) has been proposed to minimize the mentioned objectives. The working of the genetic operators such as selection, crossover and mutation has been modified with respect to the addressed MMAL problem. The results show that there is a significant impact over productivity and the process time of the final assembled product, i.e., the rate of production is increased by 39.5% and the assembly time for one particular model is reduced to 13 min from existing 18 min. Also, the space required using the proposed assembly line is only 200 m2 against existing 350 m2. Further, the algorithm helps in reducing workers fatigue(i.e., ergonomic friendly).

关键词： optimization line balancing genetic algorithm product family assembly line

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A Constrained Local Neighborhood Approach for Efficient Markov Blanket Discovery in Undirected Independent Graphs

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Computers, Materials & Continua 2024年第8期80卷 2535-2555页

作者： Kun Liu Peiran Li Yu Zhang JiaRen Ming Li Xianyu Wang Cong Li School of Information and Communication Engineering Hainan UniversityHaikou570228China National Key Laboratory of Science and Technology on space Microwave China Academy of Space Technology Xi’anXi’an710100China Strategic Emerging Industries Department CRSC Communication&Information Group Co.Ltd.Beijing100070China Military Representative Bureau of the Army Equipment Department in Xi’an Xi’an710032China

When learning the structure of a Bayesian network,the search space expands significantly as the network size and the number of nodes increase,leading to a noticeable decrease in algorithm *** constraint-based methods typically rely on the results of conditional independence ***,excessive reliance on these test results can lead to a series of problems,including increased computational complexity and inaccurate results,especially when dealing with large-scale networks where performance bottlenecks are particularly *** overcome these challenges,we propose a Markov blanket discovery algorithm based on constrained local neighborhoods for constructing undirected independence *** method uses the Markov blanket discovery algorithm to refine the constraints in the initial search space,sets an appropriate constraint radius,thereby reducing the initial computational cost of the algorithm and effectively narrowing the initial solution ***,the method first determines the local neighborhood space to limit the search range,thereby reducing the number of possible graph structures that need to be *** process not only improves the accuracy of the search space constraints but also significantly reduces the number of conditional independence *** performing conditional independence tests within the local neighborhood of each node,the method avoids comprehensive tests across the entire network,greatly reducing computational *** the same time,the setting of the constraint radius further improves computational efficiency while ensuring *** to other algorithms,this method can quickly and efficiently construct undirected independence graphs while maintaining high *** simulation results show that,this method has significant advantages in obtaining the structure of undirected independence graphs,not only maintaining an accuracy of over 96%but also reducing the number of conditi

关键词： Bayesian network structure learning Markov blanket conditional independence

Wind speed inversion and in-orbit assessment of the imaging altimeter on Tiangong-2 space station

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Acta Oceanologica Sinica 2020年第12期39卷 114-120页

作者： Youguang Zhang Qingliu Bao Mingsen Lin Shuyan Lang Key Laboratory of space Ocean Remote Sensing and Application National Satellite Ocean Application ServiceBeijing 100081China Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou) Guangzhou 511458China Beijing Piesat Information Technology Co. Ltd.Beijing 100195China

Imaging altimeter(IALT)is a new type of radar altimeter *** contrast to the conventional nadir-looking altimeters,such as HY-2 A altimeter,Jason-1/2,and TOPEX/Poseidon,IALT observes the earth surface at low incident angles(2.5°–8°),so its swath is much wider and its spatial resolution is much higher than the previous *** paper presents a wind speed inversion method for the recently launched IALT onboard Tiangong-2 space *** the current calibration results of IALT do not agree well with the well-known wind geophysical model function at low incidence angles,a neural network is used to retrieve the ocean surface wind speed in this *** wind speed inversion accuracy is evaluated by comparing with the ECMWF reanalysis wind speed,buoy wind speed,and in-situ ship *** results show that the retrieved wind speed bias is about–0.21 m/s,and the root-mean-square(RMS)error is about 1.85 m/*** wind speed accuracy of IALT meets the performance requirement.

关键词： imaging altimeter ocean surface wind speed inversion accuracy analysis in-orbit assessment

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A Bus Planning Algorithm for FPC Design in Complex Scenarios

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Chinese Journal of Electronics 2024年第2期33卷 346-352页

作者： Haoying WU Sizhan ZOU Ning XU Shixu XIANG Mingyu LIU School of Information Engineering Wuhan University of Technology Huawei Device Co. Ltd.

Flexible printed circuit(FPC) design in complex scenarios has a list of pin concentration areas, which lead to extremely congested intersection regions while connecting the pins. Currently, it is challenging to explore the routability and to find topologically non-crossing and routable paths manually for the nets timely. The existing bus planning methods cannot offer optimal solutions concerning the special resource distribution of the FPC design. To investigate an effective way to shorten the routing time of FPC and achieve enhanced performance, a bus planning algorithm is proposed to tackle complex area connection problems. On the basis of the pin location information, the routing space is partitioned and generally represented as an undirected graph, and the topological non-crossing relationship between different regions is obtained using the dynamic pin sequence. Considering the routability and electrical constraints, a heuristic algorithm is proposed to search the optimal location of the crossing point on the region boundary. Experimental results on industrial cases show that the proposed algorithm realize better performance in terms of count and routability in comparison with numerous selected state-of-the-art router and methods.

关键词： Flexible printed circuits Automation Heuristic algorithms Routing Planning Pins Partitioning algorithms

Design of communication relay mission for supporting lunar-farside soft landing

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Science China(Information Sciences) 2018年第4期61卷 73-86页

作者： Weiren WU Yuhua TANG Lihua ZHANG Dong QIAO Lunar Exploration Program and space Engineering Center School of aerospace Engineering Beijing Institute of Technology Dong Fang Hong Satellite Co.ltd. Key Laboratory of Autonomous Navigation and Control for Deep space Exploration Ministry of Industry and Information Technology

Chang’E-IV will be the first soft-landing and rover mission on the lunar farside. The relay satellite, which is located near the Earth-Moon L2 point for relay communication, is the key to the landing mission. Based on an analysis of the characteristics of the task and the technical difficulties associated with the relay satellite system, the overall design scheme of the relay communication mission is proposed in terms of trajectory design and communication system design among other aspects. First, according to the complex dynamic environment, a mission orbit that serves as an uninterrupted communication link is presented. A short-duration and low-energy transfer trajectory with lunar flyby is discussed. Orbital correction and a low-cost control strategy for orbit maintenance in the Earth-Moon L2 point region are provided. Second,considering the existing technical constraints, the requirement of relay communication in different stages and the design schemes of frequency division and redundant relay communication system are introduced. Finally,based on the trajectory design index and the performance of the communication system, the overall design scheme of the relay communication mission is proposed. This mission will provide the technical support and reference required for the Chang’E-IV mission.

关键词： lunar farside soft landing relay communication Earth-Moon Lagrange point

Research on agile space emergency launching mission planning simulation and verification method

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Journal of Systems Engineering and Electronics 2023年第5期34卷 1267-1284页

作者： WU Feng LIU Xiuluo WANG Jia LI Chao LIU Ying SU Jianbin ZHANG Ailiang WANG Min Beijing Institute of Tracking and Telecommunications Technology Beijing 100094China CASIC space Engineering Development Co.ltd. Beijing 100854China

space emergency launching is to send a satellite into space by using a rapid responsive solid rocket in the bounded time to implement the emergency Earth observation *** key and difficult points mainly include the business process construction of launching mission planning,validation of the effectiveness of the launching scheme,*** paper pro-poses the agile space emergency launching mission planning simulation and verification method,which systematically con-structs the overall technical framework of space emergency launching mission planning with multi-field area,multi-platform and multi-task parallel under the constraint of resource schedul-ing for the first *** supports flexible reconstruction of mis-sion planning processes such as launching target planning,tra-jectory planning,path planning,action planning and launching time analysis,and can realize on-demand assembly of operation links under different mission scenarios and different plan condi-tions,so as to quickly modify and generate launching *** supports the fast solution of rocket trajectory data and the accurate analysis of multi-point salvo time window recheck and can realize the fast conflict resolution of launching missions in the dimensions of launching position and launching window *** supports lightweight scenario design,modular flexi-ble simulation,based on launching style,launching platform,launching rules,etc.,can realize the independent mapping of mission planning results to two-dimensional and three-dimen-sional visual simulation models,so as to achieve a smooth con-nection between mission planning and simulation.

关键词： emergency launching launching mission planning launching process simulation satellite orbit planning rocket tra-jectory planning

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Micropore structure characteristics and quantitative characterization methods of lacustrine shale-A case study from the member 2 of Kongdian Formation, Cangdong sag, Bohai Bay Basin

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Petroleum Research 2020年第2期5卷 93-102页

作者： Lihong Zhou Changwei Chen Fei Yang Wenzhong Han Quansheng Guan China National Petroleum Corporation ltd. Dagang Oilfield BranchTianjin300280China

To better understand the micropore characteristics of lacustrine shale and develop quantitative methodsfor characterizing lacustrine shale, the reservoir space types, structures and spatial distribution patternsof effective pores in the shale of Member 2 of Kongdian Formation in Cangdong sag are studied usingcores, thin sections, scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM),nuclear magnetic resonance (NMR), whole-rock X-ray diffraction (XRD) data, etc. Various shale porositycalculation methods are evaluated. The study results show that the reservoir spaces of the shale mainlyinclude three types, i.e., matrix pores, organic pores and fractures. Flaky pore throats formed bydissolution-induced pores and mould pores can improve the pore connectivity. NMR effective porosity ofthe shale varies from 0.59% to 4.42% with an average of 2.38%, accounting for 49.54% of the total NMRporosity and 34.53% of the gas porosity. The shale is divided into the unimodal-type felsic shale, bimodaltype felsic shale, carbonate shale and mixed shale. The different lithologies exhibit linear correlationsamong NMR, gas and effective porosities. The shale has effective porosity of 0.56%-4.53% with an averageof 2.12%. Furthermore, the shale reservoir is divided into four classes: Class I reservoir with effectiveporosities of more than 2.5%;Class II1 reservoir with effective porosity of 2.0%-2.5%;Class II2 reservoirwith effective porosity of 1.5%-2%;and Class III reservoir with effective porosity of less than 1.5%.

关键词： Lacustrine shale Rservoir space type Pore structure Effective porosity Sweet spot evaluation Member 2 of Kongdian Formation Cangdong sag Bohai Bay Basin

Cyber-physical-social-thinking space based science and technology framework for the Internet of Things

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Science China(Information Sciences) 2015年第3期58卷 17-35页

作者： NING HuanSheng LIU Hong School of Computer and Communication Engineering University of Science and Technology Beijing Engineering Laboratory RUN Technologies Co. Ltd. Beijing

The Internet of Things(Io T)as an emerging network paradigm is bringing the next scientific and technological revolution for ubiquitous things’interactions in cyber-physical-social *** Io T influences the current science and technology system by enabling its relatively stable interrelations for an inevitable architecture *** this paper,we aim to explore an updated science and technology framework for the Io ***,a novel cyber-physical-social-thinking(CPST)space is established by involving an attractive concept of the Internet of Thinking(Io Tk),and a science and technology framework is accordingly proposed referring to both scientific aspect(i.e.,cyber-physical,social,and noetic sciences)and technological aspect(i.e.,fundamental,physical,cyber,and social technologies).According to the perspective of the traditional Chinese culture,we explain the established science and technology framework,in which the"Five Elements"(i.e.,wood,fire,earth,metal,and water)have common properties with the restructured cyber-physical science in the Io ***,we introduce a scenario of smart city to identify the technological aspect in the Io T,and discuss the key enabling technologies,including resource management,energy management,data management,session management,security and privacy,loop control,space-time consistency,nanotechnology,and quantum *** turns out that the established science and technology framework will launch an innovation for academia and industry communities.

关键词： Internet of Things(Io T) cyber-physical-social-thinking science technology discipline