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Multi-UAVs Collaborative Path Planning in the Cramped Environment

IEEE/CAA Journal of Automatica Sinica 2024年第2期11卷 529-538页

作者： Siyuan Feng Linzhi zeng Jining liu Yi Yang Wenjie Song School of Automation Beijing Institute of TechnologyNanjing 210039China Nanjing Research Institute of Electronics Technology Nanjing 210039China Yichang Testing Technique Research Institute Yichang 443003China IEEE

Due to its flexibility and complementarity, the multiUAVs system is well adapted to complex and cramped workspaces, with great application potential in the search and rescue(SAR) and indoor goods delivery fields. However, safe and effective path planning of multiple unmanned aerial vehicles(UAVs)in the cramped environment is always challenging: conflicts with each other are frequent because of high-density flight paths, collision probability increases because of space constraints, and the search space increases significantly, including time scale, 3D scale and model scale. Thus, this paper proposes a hierarchical collaborative planning framework with a conflict avoidance module at the high level and a path generation module at the low level. The enhanced conflict-base search(ECBS) in our framework is improved to handle the conflicts in the global path planning and avoid the occurrence of local deadlock. And both the collision and kinematic models of UAVs are considered to improve path smoothness and flight safety. Moreover, we specifically designed and published the cramped environment test set containing various unique obstacles to evaluating our framework performance thoroughly. Experiments are carried out relying on Rviz, with multiple flight missions: random, opposite, and staggered, which showed that the proposed method can generate smooth cooperative paths without conflict for at least 60 UAVs in a few *** benchmark and source code are released in https://***/inin-xingtian/multi-UAVs-path-planner.

关键词： Collision avoidance conflict resolution multi-unmanned aerial vehicles(UAVs)system path planning

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Multiple advanced surgical techniques to treat acquired seminal duct obstruction

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Asian Journal of Andrology 2014年第6期16卷 912-916页

作者： Hong-Tao Jiang Qian Yuan Yu liu zeng-Qin liu Zhen-Yu Zhou Ke-Feng Xiao Jiang-Gen Yang Department of Urology Shenzhen People's Hospital Shenzhen 518020 China Department of Laboratory Medicine Shenzhen People's Hospital Shenzhen 518020 China

The aim of this study was to evaluate the outcomes of multiple advanced surgical treatments （i.e. microsurgery, laparoscopic surgery and endoscopic surgery）for acquired obstructive azoospermia. We analyzed the surgical outcomes of 51 patients with suspected acquired obstructive azoospermia consecutively who enrolled at our center between January 2009 and May 2013. Modified vasoepididymostomy, laparoscopically assisted vasovasostomy and transurethral incision of the ejaculatory duct with holmium laser were chosen and performed based on the different obstruction sites. The mean postoperative follow-up time was 22 months （range： 9 months to 52 months）. Semen analyses were initiated at four postoperative weeks, followed by trimonthly （months 3, 6, 9 and 12） semen analyses, until no sperm was found at 12 months or until pregnancy was achieved. Patency was defined as 〉10,000 sperm m1-1 of semen. The obstruction sites, postoperative patency and natural pregnancy rate were recorded. Of 51 patients, 47 underwent bilateral or unilateral surgical reconstruction; the other four patients were unable to be treated with surgical reconstruction because of pelvic vas or intratesticular tubules obstruction. The reconstruction rate was 92.2% （47/51）, and the patency rate and natural pregnancy rate were 89.4% （42/47） and 38.1% （16/42）, respectively. No severe complications were observed. Using multiple advanced surgical techniques, more extensive range of seminal duct obstruction was accessible and correctable; thus, a favorable patency and pregnancy rate can be achieved.

关键词： azoospermia endoscopy laparoscopy male infertility microsurgery

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Unsupervised Multi-Expert Learning Model for Underwater Image Enhancement

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IEEE/CAA Journal of Automatica Sinica 2024年第3期11卷 708-722页

作者： Hongmin liu Qi Zhang Yufan Hu Hui zeng Bin Fan the School of Intelligence Science and Technology and the Institute of Artificial Intelligence University of Science and Technology BeijingBeijing 100083China the School of Automation and Electrical Engineering University of Science and Technology BeijingBeijing 100083China IEEE

Underwater image enhancement aims to restore a clean appearance and thus improves the quality of underwater degraded *** methods feed the whole image directly into the model for ***,they ignored that the R,G and B channels of underwater degraded images present varied degrees of degradation,due to the selective absorption for the *** address this issue,we propose an unsupervised multi-expert learning model by considering the enhancement of each color ***,an unsupervised architecture based on generative adversarial network is employed to alleviate the need for paired underwater *** on this,we design a generator,including a multi-expert encoder,a feature fusion module and a feature fusion-guided decoder,to generate the clear underwater ***,a multi-expert discriminator is proposed to verify the authenticity of the R,G and B channels,*** addition,content perceptual loss and edge loss are introduced into the loss function to further improve the content and details of the enhanced *** experiments on public datasets demonstrate that our method achieves more pleasing results in vision *** metrics(PSNR,SSIM,UIQM and UCIQE) evaluated on our enhanced images have been improved obviously.

关键词： Multi-expert learning underwater image enhancement unsupervised learning

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Comparison of antimony and arsenic behaviour at the river-lake junction in the middle of the Yangtze River Basin

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Journal of Environmental Sciences 2024年第2期136卷 189-200页

作者： Huiji liu Wei zeng Ziyang Lai Mengchang He Chunye Lin Wei Ouyang Xitao liu State Key Laboratory of Water Environment Simulation School of EnvironmentBeijing Normal UniversityBeijing 100875China Advanced Interdisciplinary Institute of Environment and Ecology Beijing Normal UniversityZhuhai 519087China

As typical metalloid toxic elements widely distributed in environmental media,the geochemical behaviour of antimony(Sb)and arsenic(As)affects environmental *** selected the surface waters and sediments at the river-lake junction of Dongting Lake as the research objects,analysed the concentration and chemical partitioning of Sb and As,assessed its contamination and ecological risk levels,and discussed its sources and potential influencing *** concentrations of dissolved Sb and As in surface waters were low(<5.46μg/L),and the concentrations of Sb and As in surface sediments were 2.49-22.65mg/kg and 11.10-136.34 mg/kg,*** and As in sediments were mainly enriched in the fraction of residues,but the proportion of As in bioavailability was significantly higher than that of *** the contamination level of Sb was higher than that of As,the risk assessment code(RAC)showed that the ecological risk level of As was higher than that of *** erosion and mining activities(in the midstream of Zijiang River)were the main contaminated sources of Sb,while As was affect mainly by rainwater *** contamination and ecological risk of Sb in the inlet of the Zijiang River should receive considerable attention,while those of As in the inlet of the Xiangjiang River should also be seriously *** study highlights the need for multi-index-based assessments of contamination and ecological risk and the importance of further studies on the environmental behaviour of metalloids in specific hydrological conditions,such as river-lake junctions.

关键词： Contamination Ecological risks Antimony(Sb) Arsenic(As) River-lake junction Dongting Lake

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Switched-capacitor Based Seven-level Boost Inverter with a Reduced Number of Devices

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 381-391页

作者： Weijie Lin Jun zeng Bo Fu Zhixing Yan Junfeng liu School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China WISDRI Engineering&Research Incorporation Limited Wuhan 430074China Department of Energy Aalborg UniversityAalborg 9220Denmark School of Automation Science and Engineering South China University of TechnologyGuangzhou 510641China

The conventional multilevel inverters(MLIs)have the disadvantages of numerous devices,incapacity of boost,unbalance for capacitor’s voltage,high complexity for control,and *** by this issue,a seven-level boost inverter(7LBI)based on a switched capacitor is presented for singlephase applications in this *** proposed 7LBI using only seven transistors can achieve seven output levels,1.5 voltage gain,and natural balance of capacitors’voltages without sensors or other auxiliary methods,which illustrates its suitability for the applications of renewable energy *** configuration of topology and operating principles are illustrated in *** natural balance of capacitors and capacitance calculations are deduced as ***,the comparative study is conducted for different types of *** results illustrate the merits of the proposed 7LBI with respect to reduced devices,lower voltage stress,and less power ***,a simulation for the proposed 7LBI with PWM modulation is realized based on the theoretical analysis;an experimental prototype is also implemented,verifying multilevel output,boost ability,natural balance for switched capacitors,and performance of transient response.

关键词： Multilevel inverters voltage gain natural balance renewable energy generation reduced number of elements

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Comparison of transcriptomes undergoing waterlogging at the seedling stage between tolerant and sensitive varieties of Brassica napus L.

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Journal of Integrative Agriculture 2015年第9期14卷 1723-1734页

作者： ZOU Xi-ling zeng liu LU Guang-yuan CHENG Yong XU Jin-song ZHANG Xue-kun Key Laboratory of Biology and Genetic Improvement of Oil Crops Ministry of Agriculture/Oil Crops Research InstituteChinese Academy of Agricultural Sciences

RNA sequencing of the sensitive GH01 variety of Brassica napus L. seedling roots under 12 h of waterlogging was compared with previously published data of the ZS9 tolerant variety to unravel genetic mechanisms of waterlogging tolerance beyond natural variation. A total of 2 977 genes with similar expression patterns and 17 genes with opposite expression patterns were identiifed in the transcription proifles of ZS9 and GH01. An additional 1 438 genes in ZS9 and 1 861 genes in GH01 showed strain speciifc regulation. Analysis of the overlapped genes between ZS9 and GH01 revealed that waterlogging tolerance is determined by ability to regulate genes with similar expression patterns. Moreover, differences in both gene expression proifles and abscisic acid (ABA) contents between the two varieties suggest that ABA may play some role in waterlogging tolerance. This study identiifes a subset of candidate genes for further functional analysis.

关键词： rapeseed(Brassica napus L.) waterlogging digital gene expression(DGE) roots transcriptome comparative analysis

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Combined experimental and simulation study on corrosion behavior of B10 copper-nickel alloy welded joint under local turbulence

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Journal of Iron and Steel Research International 2023年第8期30卷 1598-1612页

作者： Da-lei Zhang Ran liul Ying-shuang liul Shao-hua Xing Zong-hao He Yao Qian Jin-zeng liu Xiao-hui Dou Xin-wei Zhang School of Materials Science and Engineering China University of Petroleum(East China)Qingdao 266580ShandongChina State Key Laboratory for Marine Corrosion and Protection Luoyang Ship Material Research InstituteQingdao 266237ShandongChina

The corrosion behavior of B10 copper-nickel alloy welded joints in seawater pipeline system was analyzed under local turbulence induced by weld residual *** corrosion behavior was evaluated by array electrode technology,mor-phology and elemental characterization,and COMSOL Multiphysics *** results provide a theoretical basis for the corrosion and leakage of B10 alloy in seawater pipeline under the action of *** results show that residual height-induced turbulence exhibits a significant effect on the corrosion behavior in different areas of welded joints in B10 *** can damage some surfaces,causing polarity deflection followed by acceleration of corrosion,or it is easier to form a protective film to slow down *** Multiphysics results show that the shear rate and turbulent kinetic energy increase linearly with the increase in residual height and *** corrosion behavior of alloy surface is influenced by controlling the mass transfer rate and surface state.

关键词： Array electrode technology Welded joint Corrosion COMSOL Multiphysics simulation Seawater

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How complex is the 2016 Mw 7.8 Kaikoura earthquake, South Island, New Zealand?

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Science Bulletin 2017年第5期62卷 309-311页

作者： Xuhua Shi Yu Wang Jing liu-zeng Ray Weldon Shengji Wei Teng Wang Kerry Sieh Earth Observatory of Singapore Nanyang Technological University State Key Laboratory of Earthquake Dynamics Institute of GeologyChina Earthquake Administration Department of Earth Sciences University of Oregon

A powerful earthquake of moment magnitude(Mw)7.8occurred in the Kaikoura region,South Island,New Zealand,at00:02:56 AM(local time),14 November *** to the Institute of Geological and Nuclear Sciences(GNS)in New Zealand,

关键词： New Zealand South Island How complex is the 2016 Mw 7.8 Kaikoura earthquake than http

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Activation of dislocations in Mg with solute Y

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Journal of Magnesium and Alloys 2024年第3期12卷 1045-1053页

作者： Alireza Maldar Leyun Wang Boyu liu Wenjun liu Zhaohui Jin Bijin Zhou Xiaoqin zeng National Engineering Research Center of Light Alloy Net Forming Shanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China Advanced Photon Source Argonne National LaboratoryIL 60439USA Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China School of Mechanical Engineering Suzhou University of Science and TechnologySuzhou 215009China

Mg-Y cast alloy shows excellent ductility(elongation to failure>15%)compared with pure Mg and commercial Mg cast *** monitoring the microstructure evolution during an in situ tensile test of a Mg-2.5 wt%Y alloy,we identify the activation of prismaticslip,which is rare in *** X-ray micro-beam Laue diffraction(μ-Laue)and transmission electron microscopy revealed the morphology of prismaticslip bands and individual*** functional theory and molecular dynamics calculations indicate that solute Y can significantly reduce the stacking fault energy(SFE)alongdirection on prismatic plane in Mg lattice and thus facilitate the nucleation ofdislocations during *** presence of freedislocations in the Mg lattice can also lead to nucleation of{10–12}twins even under unfavorable geometric conditions.

关键词： alloy microstructure ductility

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Direct TEM Observation of Phase Separation and Crystallization in Cu_(45)Zr_(45)Ag_(10)Metallic Glass

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Acta Metallurgica Sinica(English Letters) 2016年第6期29卷 538-545页

作者： Hui Wang Shang-Gang Xiao Tao Zhang Qiang Xu zeng-Qian liu Meng-Yue Wu Frans Tichelaar Henny Zandbergen Key Laboratory of Aerospace Materials and Performance (Ministry of Education) School of Materials Science and Engineering Beihang University Delft University of Technology Kavli Institute of Nanoscience Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences

The structural evolution of Cu_（45）Zr_（45）Ag_（10） metallic glass was investigated by in situ transmission electron microscopy heating experiments. The relationship between phase separation and crystallization was elucidated. Nucleation and growth-controlled nanoscale phase separation at early stage were seen to impede nanocrystallization, while a coarser phase separation via aggregation of Ag-rich nanospheres was found to promote the precipitation of Cu-rich *** of composition and dynamics heterogeneities was supposed to play a key role during phase separation preceding crystallization.

关键词： Bulk metallic glass Phase separation In situ TEM heating Crystallization Glass forming ability

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