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Tomographic PIV investigation on coherent vortex structures over shark-skin-inspired drag-reducing riblets

Acta Mechanica Sinica 2016年第2期32卷 284-294页

作者： Shao-Qiong Yang Shan Li Hai-ping tian Qing-Yi wang Nan Jiang Department of Mechanics Tianjin UniversityTianjin 300072 China tianjin Key Laboratory of Modern Engineering Mechanics Tianjin 300072 China School of Mechanical and Aerospace Engineering Nanyang Technological University Singapore 639805 Singapore

Nature has shown us that the microstructure of the skin of fast-swimming sharks in the ocean can reduce the skin friction drag due to the well-known shark-skin *** the present study,the effect of shark-skin-inspired riblets on coherent vortex structures in a turbulent boundary layer（TBL） is *** is done by means of tomographic particle image velocimetry（TPIV） measurements in channel fl ws over an acrylic plate of drag-reducing riblets at a friction Reynolds number of *** turbulent fl ws over drag-reducing riblets are verifie by a planar time-resolved particle image velocimetry（TRPIV） system initially,and then the TPIV measurements are ***-dimensional（2D） experimental results with a dragreduction rate of around 4.81% are clearly visible over triangle riblets with a peak-to-peak spacing s＋of 14,indicating from the drag-reducing performance that the buffer layer within the TBL has thickened;the logarithmic law region has shifted upward and the Reynolds shear stress decreased.A comparison of the spatial topological distributions of the spanwise vorticity of coherent vortex structures extracted at different wall-normal heights through the improved quadrant splitting method shows that riblets weaken the amplitudesof the spanwise vorticity when ejection（Q2） and sweep（Q4） events occur at the near wall,having the greatest effect on Q4 events in *** so-called quadrupole statistical model for coherent structures in the whole TBL is verified Meanwhile,their spatial conditional-averaged topological shapes and the spatial scales of quadrupole coherent vortex structures as a whole in the overlying turbulent fl w over riblets are changed,suggesting that the riblets dampen the momentum and energy exchange between the regions of near-wall and outer portion of the TBL by depressing the bursting events（Q2 and Q4）,thereby reducing the skin friction drag.

关键词： Turbulent boundary layer(TBL) Coherent vortex structure Flow control Drag reduction Shark-skininspired riblet Tomographic particle image velocimetry(TPIV)

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Control of group velocity in an annular chain of microring coupled-resonator optical waveguides

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Chinese Science Bulletin 2007年第22期52卷 3047-3050页

作者： tian He ZHANG YunDong wang Nan YUAN ping Institute of Opto-electronics Harbin Institute of Technology Harbin 150080 China

In order to control group velocity,an annular chain of microring coupled-resonator optical waveguides was analyzed,and its transmission spectra were obtained using the transfer matrix method. The result showed that the curvature of the chain caused the dispersion curves to shift and the resonance fre-quency got fixed. It is therefore concluded that the group velocity of light in the annular chain of mi-croring coupled-resonator optical waveguides can be controlled by adjusting the curvature of the chain. We believe that such an annular chain can be used as an optical buffer or signal retarder for optical communication.

关键词：群速度共鸣器光波波导传输模式

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Divergent synthesis of aryl amines and dihydroquinazolinones via electrochemistry-enabled rhodium-catalyzed C–H functionalization

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Science China Chemistry 2023年第10期66卷 2863-2870页

作者： Yi-Kang Xing Zhen-Hua wang ping Fang Cong Ma tian-Sheng Mei State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryUniversity of Chinese Academy of SciencesShanghai 200032China

Electrochemistry-enabled rhodium-catalyzed C–H amination and amination cyclization of arene assisted by a weakly coordinating amide have been reported. Additionally, aryl amines and dihydroquinazolinones could be obtained selectively by controlling the electric current. Mechanistic studies suggested that the amination reaction likely involves an electrochemical oxidation-induced reductive elimination of a high valent rhodium intermediate, which led to the amination reaction even proceeding smoothly at room temperature.

关键词： organic electrochemistry rhodium catalysis C-H functionalization divergent synthesis

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Fabrication of CuO_x thin-film photocathodes by magnetron reactive sputtering for photoelectrochemical water reduction

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Green Energy & Environment 2018年第3期3卷 239-246页

作者： tian Xie Tao Zheng Ruiling wang Yuyu Bu Jin-ping Ao Institute of Technology and Science Tokushima University National Institute of Technology Anan College Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices School of MicroelectronicsXidian University

The CuO_x thin film photocathodes were deposited on F-doped Sn O_2 (FTO)transparent conducting glasses by alternating current(AC)magnetron reactive sputtering under different Ar:O_2 *** advantage of this deposited method is that it can deposit a CuO_x thin film uniformly and rapidly with large *** the photoelectrochemical(PEC)properties of these CuO_x photocathodes,it can be found that the CuO_x photocathode with Ar/O_2 30:7 provide a photocurrent density ofà3.2 m A cm^(à2)under a bias potentialà0.5 V(***/Ag Cl),which was found to be twice higher than that of Ar/O_2 with 30:5.A detailed characterization on the structure,morphology and electrochemical properties of these CuO_x thin film photocathodes was carried out,and it is found that the improved PEC performance of CuO_x semiconductor photocathode with Ar/O_230:7 attributed to the less defects in it,indicating that this Ar/O_230:7 is an optimized condition for excellent CuO_x semiconductor photocathode fabrication.

关键词： CuOx thin film Magnetron sputtering Photocathode Defect controlling

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Objectness Region Enhancement Networks for Scene Parsing

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Journal of Computer Science & Technology 2017年第4期32卷 683-700页

作者： Xin-Yu Ou ping Li He-Fei Ling Si Liu tian-Jiang wang School of Computer Science and Technology Huazhong University of Science and Technology Wuhan 430074 China Institute of Information Engineering Chinese Academy of Sciences Beijing 100091 China Cadres Online Learning Institute of Yunnan Province Yunnan Open University Kunming 650223 China

Semantic segmentation has recently witnessed rapid progress, but existing methods only focus on identifying objects or instances. In this work, we aim to address the task of semantic understanding of scenes with deep learning. Different from many existing methods, our method focuses on putting forward some techniques to improve the existing algorithms, rather than to propose a whole new framework. Objectness enhancement is the first effective technique. It exploits the detection module to produce object region proposals with category probability, and these regions are used to weight the parsing feature map directly. 'Extra background' category, as a specific category, is often attached to the category space for improving parsing result in semantic and instance segmentation tasks. In scene parsing tasks, extra background category is still beneficial to improve the model in training. However, some pixels may be assigned into this nonexistent category in inference. Black-hole filling technique is proposed to avoid the incorrect classification. For verifying these two techniques, we integrate them into a parsing framework for generating parsing result. We call this unified framework as Objectness Enhancement Network (OENet). Compared with previous work, our proposed OENet system effectively improves the performance over the original model on SceneParse150 scene parsing dataset, reaching 38.4 mIoU (mean intersection-over-union) and 77.9% accuracy in the validation set without assembling multiple models. Its effectiveness is also verified on the Cityscapes dataset.

关键词： objectness region enhancement black-hole filling scene parsing instance enhancement objectness region proposal

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Molecular evolution of pancreatic ribonuclease gene(RNase1)in Rodentia

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Journal of Genetics and Genomics 2017年第4期44卷 219-222页

作者： Da-tian Lang Xiao-ping wang Lei wang Li Yu Chemistry and Life Science Department Zhaotong UniversityZhaotong 657000China state key laboratory for conservation and utilization of bio-resource in yunnan yunnan universitykunming 650091china key laboratory for animal genetic diversity and evolution of high education in yunnan province yunnan universitykunming 650091china

Pancreatic ribonuclease,which is encoded by RNase1,is a digestive enzyme secreted by the pancreas of vertebrates,and has been recognized to be a classic example for molecular evolutionary studies due to the frequent occurrence of gene duplication and functional divergence in organisms（Zhang et al.,2002,2006;Yu and Zhang,2006;Yu et al.,2010;Xu et al.,2013;Liu et al.,2014）.RNase1 has been extensively studied in many mammals,

关键词： RNase in Rodentia classic divergence digestive evolutionary duplication pancreas branch clade

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高速电磁能推进装置枢轨接触特性分析及实验研究

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西安交通大学学报 2025年第1期59卷 28-36页

作者：祝丽花刘平谷雨茜郝建英田子豪杨庆新天津理工大学新能源电力变换传输与智能控制天津市重点实验室天津300384

为准确分析高速增强型电磁能推进装置枢轨接触特性,提出了一种数值计算与实验测量相结合的方法,对推进装置枢轨接触特性进行动态分析。首先,建立接触电阻与膛口电压、轨道电流、磁场等物理量之间的数学模型,并设计实验对膛口电压、轨道... 详细信息

为准确分析高速增强型电磁能推进装置枢轨接触特性,提出了一种数值计算与实验测量相结合的方法,对推进装置枢轨接触特性进行动态分析。首先,建立接触电阻与膛口电压、轨道电流、磁场等物理量之间的数学模型,并设计实验对膛口电压、轨道电流、电枢速度以及空间磁场等装置参数进行测量;其次,通过膛口电压与轨道电流等实验测量数据和有限元数值计算结果,对增强型电磁能推进装置枢轨接触电阻进行计算;进一步根据接触电阻计算结果与电枢速度特性曲线,对不同阶段下推进装置枢轨接触特性进行分析;最后,将服役后的导轨进行拆解和形貌扫描,通过样貌图侧面验证了不同阶段接触特性分析的可靠性。研究结果表明:初始阶段枢轨接触电阻最大可达8.5 mΩ,且轨道在此阶段损伤较为严重;在加速至中高速阶段,接触电阻基本平稳在0.78 mΩ左右,枢轨接触状态较为稳定;在高速运动至出口阶段,接触电阻波动幅度较大,电接触稳定性差。研究内容可为轨道磨损以及提高系统性能等提供基础数据和新的可靠参考。

关键词：电磁能推进装置高速状态接触电阻轨道形貌枢轨接触

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Knowledge Graph and Knowledge Reasoning:A Systematic Review

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Journal of Electronic Science and Technology 2022年第2期20卷 159-186页

作者： Ling tian Xue Zhou Yan-ping Wu wang-Tao Zhou Jin-Hao Zhang tian-Shu Zhang Kashi Institute of Electronics and Information Industry Kashi 844099 Shenzhen Institute of Information Technology Shenzhen 518172 the School of Computer Science and Engineering University of Electronic Science and Technology of ChinaChengdu 610054 the School of Information and Software Engineering University of Electronic Science and Technology of ChinaChengdu 610054

The knowledge graph(KG) that represents structural relations among entities has become an increasingly important research field for knowledge-driven artificial intelligence. In this survey, a comprehensive review of KG and KG reasoning is provided. It introduces an overview of KGs, including representation, storage, and essential technologies. Specifically, it summarizes several types of knowledge reasoning approaches, including logic rules-based, representation-based, and neural network-based methods. Moreover, this paper analyzes the representation methods of knowledge hypergraphs. To effectively model hyper-relational data and improve the performance of knowledge reasoning, a three-layer knowledge hypergraph model is proposed. Finally, it analyzes the advantages of three-layer knowledge hypergraphs through reasoning and update algorithms which could facilitate future research.

关键词： methods. representation reasoning

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Study on the Set-up and Set-down Induced by Breaking Waves Over A Reef

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China Ocean Engineering 2020年第6期34卷 853-862页

作者： LIU Qing-jun wang Deng-ting WEI Zhang-ping XU Hua SUN tian-ting Nanjing Hydraulic Research Institute Nanjing 210029China College of Harbour Coastal and Offshore Engineering Hohai UniversityNanjing 210098China Key Laboratory of Port Waterway&Sedimentation Engineering of MOTNanjing 210029China Department of Physics and Physical Oceanography University of North Carolina WilmingtonWilmingtonNC 28403USA

This paper proposes an equation to calculate breaking wave induced wave set-up and set-down along reef flat. The mathematical equation was derived based on the theory of radiation stress and the conservation of wave energy. The equation is primarily determined by several physical variables including the breaking wave index, the stable wave index, the attenuation coefficient of wave energy flux, and the flow velocity in the re-stabilization zone. A series of laboratory experiments were carried out to calibrate the theoretical equations. Specifically, the breaking wave index,the stable wave index, and the velocity over the reef flat were measured in the laboratory. The attenuation coefficient of wave energy flux in our theoretical equation was determined by calibration by comparing with the laboratory measured wave height. Furthermore, it has been put forward that the velocity based on cnoidal wave theory could be used to determine the velocity over the reef flat if there is no velocity measurement available. Overall, the proposed equation can provide satisfactory prediction of wave set-up and set-down along the reef flat.

关键词： wave set-up and set-down streamwise variation breaking waves reef flat reef terrain

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Tracking Control of Wheeled Mobile Robots with Communication Delay and Data Loss

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Journal of Systems Science & Complexity 2018年第4期31卷 927-945页

作者： ZHANG tian-Yong LIU Guo-ping Center For Control Theory and Guidance Technology Harbin Institute of Technology Harbin 150001 China School of Engineering University of South Wales Pontypridd CF37 1DL UK

This paper considers the tracking control problem of a wheeled mobile robot under situation of communication delay and consecutive data packet dropouts in the feedback channel. A tracking controller in discrete-time domain for the case of ideal network condition is first derived, and then the networked predictive controller as well as two algorithms for dealing with communication delay and consecutive data packet dropouts are proposed. Simulation and experimental results verify the realizability and effectiveness of the proposed algorithms.

关键词： Communication delay consecutive data loss networked predictive control trajectory tracking wheeled mobile robot

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