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Effect of blade tip geometry on tip leakage vortex dynamics and cavitation pattern in axial-flow pump

Science China(Technological Sciences) 2017年第10期60卷 1480-1493页

作者： shi lei ZHANG DeSheng ZHAO RuiJie shi WeiDong JIN YongXin Research Center of Fluid Machinery Engineering and Technology Jiangsu University Zhenjiang 212013 China

A series of blade tip geometries, including original plain tip, rounded tip on the pressure side and diverging tip towards the suction side, were adopted to investigate the effect of blade geometry on tip leakage vortex dynamics and cavitation pattern in an axial-flow pump. On the basis of the computation, it clearly shows the flow structure in the clearance for different tip configurations by the detailed data of axial velocity and turbulent kinetic energy. The in-plain trajectory, in aspects of the angle between the blade suction side and vortex core and the initial point of tip leakage vortex, was presented using the maximum swirling strength method. The most striking feature is that the inception location of tip leakage vortex is delayed for chamfered tip due to the change of blade loading on suction side. Some significant non-dimensional parameters, such as pressure, swirling strength and turbulent kinetic energy, were used to depict the characteristics of tip vortex core. By the distribution of circumferential vorticity which dominates the vortical flows near the tip region, it is observed that the endwall detachment as the leakage flow meets the mainstream varies considerably for tested cases. The present study also indicates that the shear layer feeds the turbulence into tip leakage vortex core, but the way is different. For the chamfered tip, high turbulence level in vortex core is mainly from the tip clearance where large turbulent kinetic energy emerges, while it is almost from a layer extending from the suction side corner for rounded tip. At last, the visualized observations show that tip clearance cavitation is eliminated dramatically for rounded tip but more intensive for chamfered tip, which can be associated with the vortex structure in the clearance.

关键词： blade tip geometry tip leakage vortex cavitation numerical simulation high-speed photography

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A review of linear carbon chains

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Chinese Chemical Letters 2020年第7期31卷 1746-1756页

作者： Kan Zhang Yifan Zhang lei shi Check for updates State Key Laboratory of Optoelectronic Materials and Technologies Nanotechnology Research CenterSchool of Materials Science and EngineeringSun Yat-sen UniversityGuangzhou 510275China

Linear carbon chains(LCCs)are a one-dimensional sp1-hybridized allo trope of ca *** are extre mely unstable:The longer the LCCs,the less stable the ***,it is a big challenge to synthesize long *** the research on the short LCCs,e.g.,polyynes,can be traced back to the 18th,LCCs are still not well-known compared to other allotropes of carbon,e.g.,fullerenes,carbon nanotubes and ***,introducing recent progress on LCCs is of great significance to draw more attention in the community of nanocarbons as well as nanomaterials in ***,various excellent properties have been ***,LCCs with different length in many kinds of forms have been successfully *** this review,we summarized recent studies of polyynic LCCs from both theoretical and experimental ***,perspectives are highlighted to point out the further investigations of the materials.

关键词： Linear carbon chains Polyyne Carbyne Carbon nanotubes Electronic property

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Bounded Tiles in ■_p are Compact Open Sets

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Acta Mathematica Sinica,English Series 2020年第2期36卷 189-195页

作者： Ai Hua FAN shi lei FAN LA MFA UMR 7352 CNRSUniversity of Picardie33 rue Saint Leu80039 AmiensFrance School of Mathematics and Statistics&Hubei Key Laboratory of Mathematical Sciences Central China Normal UniversityWuhan430079P.R.China

Any bounded tile of the field Qp of p-adic numbers is a compact open set up to a set of zero Haar *** this note,we present two simple and direct proofs of this fact.

关键词： p-adic field tile bounded compact open

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A user-based taxonomy for deep learning visualization

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Visual Informatics 2018年第3期2卷 147-154页

作者： Rulei Yu lei shi SKLCS Institute of SoftwareChinese Academy of Sciencesand UCAS

Deep learning has achieved impressive success in a variety of tasks and is developing rapidly in recent *** problem of understanding the deep learning models has become an issue for the development of deep learning,for example,in domains like medicine and finance which require interpretable *** it is challenging to analyze and interpret complicated deep neural networks,visualization is good at bridging between abstract data and intuitive *** analytics for deep learning is a rapidly growing research *** help users better understand this field,we present a mini-survey including a user-based taxonomy that covers state-of-the-art works of the *** the requirements of different types of users(beginners,practitioners,developers,and experts),we categorize the methods and tools by four visualization goals respectively focusing on teaching deep learning concepts,architecture assessment,tools for debugging and improving models,and visual ***,we present a table consisting of the name of the method or tool,the year,the visualization goal,and the types of networks to which the method or tool can be applied,to assist users in finding available tools and methods *** emphasize the importance of visual explanation for deep learning,we introduce the studies in this research field in detail.

关键词： Deep learning Visualization Interpretation

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Development and test of an automatic height-adjusting cotton topper

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International Journal of Agricultural and Biological Engineering 2017年第2期10卷 44-55页

作者： Chen Zhaoyang shi lei Graduate School of Chinese Academy of Agricultural Sciences Beijing 100081China Nanjing Research Institute for Agricultural Mechanization Ministry of AgricultureNanjing 210014China

A fine-tuned height-adjustable cotton topper was developed and evaluated in this *** is topped at the late flowering stage because spindling reduces cotton production and complicates *** main disadvantage of traditional cotton toppers is that their topping height cannot be adjusted according to the heights of individual cotton plants,resulting in a high percentage of missed tops and overcutting that damages fruit *** solve this problem,a mechanical-electronic topping prototype was developed that could be adjusted according to the height of *** prototype includes a shearing machine system that can be tuned vertically and an automatic height control system that can detect cotton heights and actuate the mechanical *** cotton topper was attached to a tractor by a three-point hitch and tested in the *** the trial,the prototype was tested at ground speeds of 1.1 km/h,1.5 km/h and 2.2 km/h and excision lengths(from the peak to the cutting point)of 9 cm and 11 *** all tested conditions,the pass rate(the percentage of buds accurately cut without hurting the fruit branch),which reached 74%,was significantly higher than the ideal pass rates of traditional toppers,which were much lower than 50%or even 40%.The dominate factors affecting topping quality were *** pass rate was significantly influenced by the forward speed;the missing rate(rate of missed topping)was significantly influenced by the forward speed and excision length;and the overcut rate was significantly influenced by the excision *** optimized topping speed and excision length were 1.1 km/h and 11 cm respectively,and the other parameters varied according to different user preferences.A replicate trial was conducted and showed that topping at 1.1 km/h and 9 cm prevented further spindling of 90%of the plants,and topping at 1.5 km/h and 11 cm prevented further spindling of 83%of the plants.

关键词： cotton topper height-adjusting topping quality field test automatic control

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A Confined Laminar Slot Impinging Jet at Low Reynolds Numbers:Unsteady Flow and Heat Transfer Characteristics

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Journal of Thermal Science 2023年第2期32卷 753-769页

作者： shi lei SUN Chong ZHU Xiaocheng DU Zhaohui School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China

In this study,the unsteady flow and heat transfer characteristics of a laminar slot jet at low Reynolds numbers impinging on an isothermal plate surface in a two-dimensional confined space are numerically *** investigations are performed at Reynolds numbers of 120,150 and 200 based on the nozzle width and mean inlet velocity of the *** show that the Reynolds numbers of 120,150 and 200 correspond to different flow features,namely,a steady flow,an intermittent flapping motion of jet column and a continuous sinusoidal flapping state,*** on some time snapshots of the flow field,the dynamic characteristics and driving mechanism of the intermittent flapping motion of the jet column and the continuous sinusoidal flapping state are *** the jet flaps at the Reynolds number 150 and 200,there are other Nusselt number peaks outside the stagnation zone,which are related to the interference between the vortices shedding on both sides of the jet and the boundary layers of the plate ***,the dynamic mode decomposition is implemented to accurately extract flow modes with characteristic *** a Reynolds number of 150,there is a flapping mode,which describes the lateral flapping motion of the jet *** the Reynolds number is 200,there are multiple modes related to the flapping motion of the jet,as well as a low-frequency mode,which reflects the periodic changes of the boundary contour and position of the recirculation zone.

关键词： laminar slot impinging jet unsteady flow heat transfer Nusselt number dynamic mode decomposition

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Evolution of microstructures and intermetallic compounds at bonding interface in friction stir welding of dissimilar Al/Mg alloys with/without ultrasonic assistance

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Journal of Materials Science & Technology 2023年第8期139卷 31-46页

作者： Junjie Zhao ChuanSong Wu lei shi Hao Su MOE Key Lab for Liquid-Solid Structure Evolution and Materials Processing Institute of Materials JoiningShandong UniversityJinan 250061China

Complete understanding of the evolution behaviors of the microstructures and intermetallic compounds(IMCs)along the interface materials flow path in friction stir welding(FSW)of dissimilar Al to Mg alloys is of great *** this study,conventional FSW and ultrasonic vibration enhanced FSW(UVeFSW)experiments of Al/Mg alloys were performed,and the instantaneous evolution features of the interface materials around the tool were"frozen"by using the"sudden stop"and simultaneous cooling *** microstructures and IMCs formation at different locations around the exit hole were observed and characterized by scanning electron microscope,energy dispersive spectrometer and transmission elec-tron *** was found that before the materials started to deposit near the back of the tool,“IMC+Mg+IMC+Al”multilayer microstructure and simple IMC layer with(β+γ)sequentially emerged on the Al/Mg *** the application of ultrasonic vibration,the multi-layered interface structure only appeared at the middle stage of materials flow around the pin,and ultrasonic vibration just began to play a suppression role on the growth of two sub-layers IMC at a position where the materials *** assistance of ultrasonic vibration in UVeFSW,the tool drove a larger volume of Mg alloy to move toward the retreating side,and the final IMCs thickness was thinner than that in FSW.

关键词： Friction stir welding Aluminium alloy Magnesium alloy Microstructure evolution Intermetallic compounds(IMCs) Bonding interface Ultrasonic vibration

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Sexual size dimorphism in lizards:Rensch’s rule,reproductive mode,clutch size,and line fitting method effects

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Integrative Zoology 2022年第5期17卷 787-803页

作者： Tao LIANG Shai MEIRI lei shi College of Animal Science Xinjiang Agricultural UniversityUrumqiXinjiangChina College of Forestry Nanjing Forestry UniversityNanjingJiangsuChina School of Zoology&the Steinhardt Museum of Natural History Tel Aviv UniversityTel AvivIsrael

Rensch’s rule relates to a pattern whereby sexual size dimorphism is more female-biased in small-sized species and more male-biased in large-sized *** collected literature and museum data on the body size of males and females belonging to 4032 lizard species,as well as data on their reproductive modes and clutch *** used phylogenetic comparative analyses,and general linear mixed models,to test Rensch’s rule and examined how re-productive mode and clutch size affect sexual size *** size dimorphism was independent of clutch size in lizard species with variable clutch sizes and in oviparous *** litters were associated with female-biased sexual dimorphism in viviparous and in scincomorph *** regarding Rensch’s rule depended on the analytical method used to identify *** widely used,but less conservative,reduced major axis regression usually support Rensch’s rule while ordinary least squares regressions mostly show isometric *** rule tended to apply more to oviparous than to viviparous *** infer that Rensch’s rule is,at best,a weak pattern in *** is especially true in viviparous lineages where females reproduce infrequently and therefore evolve large sizes to maximise fecundity,resulting in female-biased dimorphism.

关键词： fecundity selection reduced major axis regression sexual selection sexual size dimorphism viviparity

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Dynamics of Commuting Rational Maps on Berkovich Projective Space over C_p

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Acta Mathematica Sinica,English Series 2013年第8期29卷 1459-1478页

作者： shi lei FAN Yue Fei WANG Institute of Applied Mathematics AMSSChinese Academy of Sciences Institute of Mathematics AMSSChinese Academy of Sciences

We study the dynamics of commuting rational maps with coefficients in Cp. By lifting the dynamics from P1（Cp） to Berkovich projective space P1 Berk, we prove that two nonlinear commuting maps have the same Berkovich Julia set and the same canonical measure. As a consequence, two nonlinear commuting maps with coefficient in Cp have the same classical Julia set. We also prove that they have the same pre-periodic Berkovich Fatou components.

关键词： Non-Archimedean field Berkovich projective line Fatou set Julia set

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Diffusion of municipal wastewater treatment technologies in China： a collaboration network perspective

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Frontiers of Environmental Science & Engineering 2017年第1期11卷 111-121页

作者： Yang Li lei shi Yi Qian Jie Tang State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University Beijing 100084 China Department of Computer Science and Technology Tsinghua University Beijing 100084 China

The diffusion of municipal wastewater treatment technology is vital for urban environment in developing countries. China has built more than 3000 municipal wastewater treatment plants in the past three decades, which is a good chance to understand how technologies diffused in reality. We used a data-driven approach to explore the relationship between the diffusion of wastewater treatment technologies and collaborations between organizations. A database of 3136 municipal wastewater treatment plants and 4634 collaborating organizations was built and transformed into networks for analysis. We have found that： 1）.the diffusion. networks are assortative, arid the .pattems of diffusion vary across technologies; while the collaboration networks are fragmented, and have an assortativity around zero since the 2000s. 2） Important projects in technology diffusion usually involve central organizations in collaboration networks, but organizations become more central in collaboration by doing circumstantial projects in diffusion. 3）The importance of projects in diffusion can be predicted with a Random Forest-model at a good accuracy and precision level. Our findings provide a quantitative understanding of the technology diffusion processes, which could be used for waterrelevant policy-making and business decisions.

关键词： Innovation diffusion Collaboration network Wastewater treatment plant Complex network Data driven

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