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Effect of combined electromagnetic fields on surface quality and structure of a HDC casting 5182 Al alloy ingot

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Acta Metallurgica Sinica(English Letters) 2012年第6期25卷 453-460页

作者： Qingfeng ZHU Zhihao ZHAO yubo ZUO Xiangjie WANG Jianzhong CUI Key Laboratory of Electromagnetic Processing of Materials Ministry of Education Northeastern University Shenyang 110819 China

5182 Al alloy ingots with the diameters of 100 mm are produced by conventional and combined electromagnetic fields （CEMF） horizontal direction chill （HDC） cast- ing process. The effect of CEMF on the ingot surface quality and floating grains is investigated. The results show that the CEMF is effective in reducing the segregation layer in both top and bottom sub-surfaces. Big floating grains with coarse dendrite arms mainly distribute in the crescent-shaped area near the bottom in the conven- tional HDC casting ingot. With the application of the CEMF, they disappear in the whole cross section of the HDC casting ingot and the equiaxed grains are significantly refined.

关键词： Aluminum alloy Combined electromagnetic field Horizontaldirect chill casting Structure Surface quality

Effect of microporosity on scaffolds for bone tissue engineering

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Regenerative Biomaterials 2018年第2期5卷 115-124页

作者： Ke Zhang yubo Fan Nicholas Dunne Xiaoming Li Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education School of Biological Science and Medical EngineeringBeihang UniversityBeijing 100083China Beijing Advanced Innovation Center for Biomedical Engineering Beihang UniversityBeijing 102402China Centre for Medical Engineering Research School of Mechanical and Manufacturing EngineeringDublin City UniversityStokes BuildingCollins AvenueDublin 9Ireland State Key Laboratory of New Ceramic and Fine Processing Tsinghua UniversityBeijing 100084China

Microporosity has a critical role in improving the osteogenesis of scaffolds for bone tissue *** the exact mechanism,by which it promotes new bone formation,is not well recognized yet,the related hypothesis can be found in many previous *** review presents those possible mechanisms about how the microporosity enhances the osteogenic-related functions of cells in vitro and the osteogenic activity of scaffolds in *** summary,the increased specific surface areas by microporosity can offer more protein adsorption sites and accelerate the release of degradation products,which facilitate the interactions between scaffolds and ***,the unique surface properties of microporous scaffolds have a considerable effect on the protein ***,capillary force generated by the microporosity can improve the attachment of bone-related cells on the scaffolds surface,and even make the cells achieve penetration into the micropores smaller than *** review also pays attention to the relationship between the biological and mechanical properties of microporous *** lots of achievements have been obtained,there is still a lot of work to do,some of which has been proposed in the conclusions and perspectives part.

关键词： bone tissue engineering mechanism microporosity

A Sub-pixel Disparity Refinement Algorithm Based on Lagrange Interpolation

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Chinese Journal of Electronics 2017年第4期26卷 784-789页

作者： MEN yubo ZHANG Guoyin MEN Chaoguang LI Xiang MA Ning College of Computer Science and Technology Harbin Engineering University Harbin Normal University

A sub-pixel disparity refinement algorithm based on Lagrange interpolation is proposed to calculate the sub-pixel disparity and the elevation of the target construction on the remote sensing image. The accurate integer matching feature points are obtained by improved affine scale invariant feature transform. A series of interpolation samples can be estimated through the three times magnification results of each feature matching point and its close neighbor pixels. The final sub-pixel deviation can be calculated by the interpolation samples. Experiment results show that a more accurate elevation information can be obtained on the remote sensing image with corrective epipolar line, and an accurate sub-pixel disparity result can be estimated without the epipolar line constraint as well.

关键词： Computer vision Remote sensing image processing Sub-pixel disparity Interpolation

A Stereo Matching Algorithm Based on Four-Moded Census and Relative Confidence Plane Fitting

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Chinese Journal of Electronics 2015年第4期24卷 807-812页

作者： MEN yubo ZHANG Guoyin MEN Chaoguang LI Xiang MA Ning Collage of Computer Science and Technology Harbin Engineering University Harbin Commercial University

A four-moded Census transform stereo matching algorithm using bidirectional constraint dynamic programming and relative confidence plane fitting is proposed to solve the problems of matching quality. Using the four-moded Census transform which adds a restrictive condition replaces traditional Census transform to improve matching accuracy and mean value of all pixels intensity replaces the center pixel intensity in the Census window to solve the problem of the center pixel distortion effectively,a refined initial local matching cost can be obtained. During the disparity optimization, the difficulty of disparity computation in textureless areas is overcome by the estimated condition and defined relative confident pixels. Experiment results show that a better dense matching map can be obtained by the proposed algorithm.

关键词： Stereo matching Disparity estimation Census transform Plane fitting

Characterization of Passive Films Formed on As-received and Sensitized AISI 304 Stainless Steel

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Chinese Journal of Mechanical Engineering 2019年第2期32卷 61-72页

作者： yubo Zhang Hongyun Luo Qunpeng Zhong Honghui Yu Jinlong Lv Key Laboratory of Aerospace Materials and Performance (Ministry of Education) School of Materials Science and Engineering Beijing University of Aeronautics and Astronautics The Collaborative Innovation Center for Advanced Aero-Engine (CICAAE) Beijing University of Aeronautics and Astronautics Beijing Key Laboratory of Advanced Nuclear Materials and Physics Beijing University of Aeronautics and Astronautics China Waterborne Transport Research Institute Beijing Key Laboratory of Fine Ceramics Institute of Nuclear and New Energy Technology Tsinghua University

The current research of corrosion resistance of stainless steels mainly focuses on characterization of the passive films by point defect mode and mixed-conduction model. The corrosion resistance of the passive films formed on asreceived and sensitized AISI304 stainless steel in borate bu er solution were evaluated in this paper. The degree of sensitization and corrosion resistance of AISI304 stainless steels was evaluated by double loop electrochemical potentiodynamic reactivation and electrochemical impedance spectroscopy. The passive films formed on the stainless steels were studied by XPS technique. It was found that as-received specimen had higher pitting corrosion potential and corrosion resistance than sensitized one. The Mott-Schottky results showed that sensitized stainless steel had more defects in the passive film than as-received one. The compositions of the passive films were mainly Cr and Fe oxides according to XPS results.

关键词： 304 stainless steel Sensitization Passive films XPS Impedance

Physical-barrier detection based collective motion analysis

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Frontiers of Computer Science 2019年第2期13卷 426-436页

作者： Gaoqi HE Qi CHEN Dongxu JIANG yubo YUAN Xingjian LU Department of Computer Science and Engineering East China University of Science and Technology Shanghai 200237 China State Key Laboratory of Virtual Reality Technology and Systems Beihang University Beijing 100191 China Smart City Collaborative Innovation Center Shanghai Jiao Tong University Shanghai 200240 China

Collective motion is one of the most fascinating phenomena and mainly caused by the interactions between individuals. Physical-barriers, as the particular facilities which divide the crowd into different lanes, greatly affect the measurement of such interactions. In this paper we propose the physical-barrier detection based collective motion analysis (PDCMA) approach. The main idea is that the interaction between spatially adjacent pedestrians actually does not exist if they are separated by the physical-barrier. Firstly, the physical-barriers are extracted by two-stage clustering. The scene is automatically divided into several motion regions. Secondly, local region collectiveness is calculated to represent the interactions between pedestrians in each region. Finally, extensive evaluations use the three typical methods, i.e., the PDCMA, the Collectiveness, and the average normalized Velocity, to show the efficiency and efficacy of our approach in the scenes with and without physical barriers. Moreover, several escalator scenes are selected as the typical physical-barrier test scenes to demonstrate the performance of our approach. Compared with the current collective motion analysis methods, our approach better adapts to the scenes with physical barriers.

关键词： crowd behavior analysis collective motion physical-barrier detection two-stage clustering local region collectiveness

WSN Node Coverage Optimization Algorithm Based on Global and Neighborhood Difference DE

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China Communications 2022年第3期19卷 215-229页

作者： Yi Wang yubo Peng Li Chen Yanzhong Duan Jing Li School of Information Science and Technology Northwestern UniversityXi’anShaanxi 710127China

Wireless sensor networks are widely used in today's fields,such as scientific research,industry and ***,due to the influence of its geographical location and the problems of low coverage and waste of resources caused by random placement,it is very important to adopt appropriate strategies to improve its *** this end,an improved GND-DE(Global and Neighborhood Difference Guided DE)algorithm is *** algorithm uses both the global topology structure and the neighborhood topology structure,combined with the evaluation of contemporary optimization results,and selects the results from the two topology *** value-dominant individual,the individual to be evolved and the two dominant individuals calculate the difference operator corresponding to the two topological structures;a diversity neighborhood topology is proposed for the creation of the neighborhood topology;at the same time,the algorithm step size factor F is adaptively adjusted and the JADE external archive mutation strategy is introduced to eliminate the possibility of algorithm search *** order to verify the effectiveness of its improved algorithm,compared with other mainstream improved algorithms on the CEC2017 test set,it shows that its optimization efficiency and convergence are better than other comparison algorithms;finally,GND-DE is applied to WSN node coverage optimization,which proves the feasibility of its optimization strategy.

关键词： differential evolution the global topology the neighborhood topology diversity wireless sensor network

Exploring differentiated improvement strategies of cultivated land quality in China

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Frontiers of Agricultural Science and Engineering 2024年第2期11卷 282-291页

作者： Wenguang CHEN Xiangbin KONG yubo LIAO College of Land Science and Technology China Agricultural UniversityBeijing 100193China

Quality is the core feature of cultivated land. In the face of deteriorating cultivated land quality and growing food demand, improving cultivated land quality is a top priority for guaranteeing the sustainable use of resources and national food security. Cultivated land quality in the new era can be considered in four dimensions: suitability, contiguity, resistance and ecological stress. Cultivated land suitability in China shows a decreasing trend from east to west, cultivated land contiguity is high in the north-east and low in the south-west. In terms of cultivated land resistance, the number of strongly and weakly resistant cropping fields is small and spatially clustered. Cultivated land with ecological stress is mainly located in the northern region. Based on the current situation of cultivated land quality and the strategic needs of national high-quality development, China's future goals for improving cultivated land quality include four aspects: promoting the sustainable use of resources,improving the economic benefits of farming, coping with extreme meteorological disasters and meeting the transition of the food *** the backdrop of a volatile international environment and high domestic demand for food, China should guarantee a safe supply of staples, a stable supply of animal feed and a moderate supply of high-nutrient food. In the future, China should create three major food production spaces: highstandard, low-to medium-yield, and marginal cultivated land. China urgently needs to construct three paths to implement the goal of improving cultivated land quality, namely the development of high-standard cultivated land with the core of spatial optimization, resilience enhancement and scale coupling,the transformation of low-to medium-yield cultivated land with the core of obstacle elimination, tenure adjustment, ecological sustainable, and the conservation development of marginal cultivated land with a focus on sustainable use.

关键词： China cultivated land quality differentiated improvement food security

Response of grain yield to plant density and nitrogen rate in spring maize hybrids released from 1970 to 2010 in Northeast China

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The Crop Journal 2016年第6期4卷 459-467页

作者： Chunrong Qian Yang Yu Xiujie Gong yubo Jiang Yang Zhao Zhongliang Yang yubo Hao Liang Li Zhenwei Song Weijian Zhang Institute of Crop Cultivation and Farming Heilongjiang Academy of Agricultural Sciences/Scientific Observing and Experimental Station of Crop Cultivation in Northeast ChinaMinistry of Agriculture Institute of Crop Science Chinese Academy of Agricultural Sciences/Key Laboratory of Crop Physiology and EcologyMinistry of Agriculture

The objective of this study was to identify the response of grain yield to plant density and nitrogen rate in spring maize hybrids released from 1970 to 2010 and grown extensively in Northeast ***-one hybrids were grown for 2 years in Northeast China at densities of 30,000,52,500,75,000,and 97,500 plants ha^(-1)and N application levels of 0,150,300,and 450 kg N ha^(-1).Irrespective of density or nitrogen application rate,grain yields both per plant and per unit area were significantly higher for newer than older *** plant density increased from 30,000 to 97,500 plant ha^(-1),yield per plant of 1970 s,1980 s,1990 s,and 2000 s hybrids decreased by 50%,45%,46%,and 52%,*** response of grain yield per unit area to plant density was *** estimated optimum plant densities were about 58,000,49,000,65,000,and 65,000 plants ha^(-1)for hybrids released in the 1970 s,1980s,1990 s,and 2000 s,*** theoretical optimum densities for the hybrids released from the 1970 s to the 2000 s increased by 1750 plants ha^(-1)decade^(-1).Nitrogen fertilization significantly increased grain yields per plant and per unit area for all *** theoretical optimum N application rates for high yield for hybrids released in the 1970 s and 1980 s were about 280 and 360 kg ha^(-1),and the hybrids from the 1990 s and 2000 s showed highest yield at 330 kg ha^(-1)*** significant difference in the grain yields of 2000 s hybrids between the N levels of 150 to 450 kg ha^(-1)was *** yield gains per plant and per unit area were found,with average increases of 17.9 g plant^(-1)decade^(-1)and936 kg ha^(-1)decade^(-1)over the period 1970–2010,*** gains were attributed mainly to increased yield per plant,contributed by increases in kernel number per ear and1000-kernel *** rates of lodging and barren plants of newer hybrids were significantly lower than those of older ones,especially at high plant density.

关键词： Zea mays L. Grain yield Plant density Nitrogen application rate Northeast China