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Cooling Performance for Cylindrical Film-Cooling Hole with Divided Downstream Crescent-Shaped Block

IOP Conference Series: Earth and Environmental science 2020年第1期461卷

作者： Pengfei Zhang Zhiting Tong Fei Wang Linchao Bai Chao Zhang Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control Tianjin University of Technology Tianjin 300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin 300384 China

The cooling performances for the cylindrical film-cooling hole with divided downstream crescent-shaped blocks were numerically investigated in present study. Four configurations with divided crescent-shaped block, i.e. linear, 30° convergence, 30° expansion, and 30° curved expansion, were studied at typical flow conditions. The successive crescent-shaped block case and the no block case were also solved in comparison. The temperature profiles, the local and lateral averaged cooling effectiveness at blowing ratios of 0.5 to 1.5 were obtained. As compared with the successive block case, the lateral coolant coverage were widened by using the divided block, and thus the lateral averaged cooling effectiveness were improved, especially at higher blowing ratios. Comparatively, the cylindrical hole with 30° expansion crescent-shaped block exhibited highest cooling performance.

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Pickup Manipulator design and Its Kinematics Simulation

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IOP Conference Series: Earth and Environmental science 2018年第4期170卷

作者： Zhongdang Zhang Zhaoqiang Zhang Shitai Ma Haibo Zhou Tianjin University of Technology Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control Tianjin 300384 China National Demonstration Center for Experimental Mechanical and electrical Engineering Education (Tianjin University of Technology) Tianjin 300384 China

In order to improve the flexibility of the pickup manipulator and solve the problem of picking up small sports balls in training ground such as golfing, tennis, and table tennis, a 5-DOF pickup manipulator structure is designed. According to the pickup task requirements of the manipulator, through theoretical calculations, the 86HS series stepping motor is selected as the driving motors of the front end joints. Based on this, the stepping motor control system is designed to realize the closed-loop control of the manipulator. Then the manipulator model is built using D-H method, the inverse kinematics solution is calculated, and the analysis of kinematic theory is conducted. Finally, the targeted pickup point is selected to carry out case simulation analysis of the manipulator, the motion law of the manipulator is verified to be reasonable and the task of picking up small sports balls is completed.

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Port Reconfigurable Phase-Change Optical Resonator

arXiv

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arXiv 2022年

作者： Meng, Haiyu Wang, Lingling Liu, Ziran Chen, Jianghua Lee, Ching Hua Ang, Yee Sin Department of Physics National University of Singapore 117542 Singapore Singapore University of Technology and Design 497372 Singapore Center for High-Resolution Electron Microscopy College of Materials Science and Engineering Hunan University Changsha410082 China School of Physics and Electronics Hunan University Changsha410082 China Department of Physics Key Laboratory for Low-Dimensional Structures and Quantum Manipulation Ministry of Education Hunan Normal University Changsha410081 China

Active control and manipulation of electromagnetic waves are highly desirable for advanced photonic device technology, such as optical cloaking, active camouflage and information processing. designing optical resonators with high ease-of-control and reconfigurability remains a open challenge thus far. Here we propose a novel mechanism to continuously reconfigure an optical resonator between one-port and two-port configurations via phase-change material for efficient optical modulation. By incorporating a phase-change material VO2 substrate into a photonic crystal optical resonator, we computationally show that the system behaves as a one-port device with near-perfect absorption and two-port device with high transmission up to 92% when VO2 is in the metallic rutile phase and insulating monoclinic phase, respectively. The optical response can be continuously and reversibly modulated between various intermediate states. More importantly, the proposed device is compatible with wide-angle operation and is robust against structural distortion. Our findings reveal a novel device architecture of port reconfigurable optical resonator uniquely enabled by switchable optical properties of phase change material. Copyright © 2022, The Authors. All rights reserved.

关键词： Vanadium dioxide

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The grassland carbon cycle:Mechanisms,responses to global changes,and potential contribution to carbon neutrality

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Fundamental Research 2023年第2期3卷 209-218页

作者： Lingli Liu Emma J.Sayer Meifeng Deng Ping Li Weixing Liu Xin Wang Sen Yang Junsheng Huang Jie Luo Yanjun Su JoséM.Grünzweig Lin Jiang Shuijin Hu Shilong Piao State Key Laboratory of Vegetation and Environmental Change Institute of BotanyChinese Academy of SciencesBeijing 100093China University of Chinese Academy of Sciences Beijing 100049China Lancaster Environment Centre Lancaster UniversityLancaster LA14YQUnited Kingdom Department of Evolutionary Biology and Environmental Studies University of ZurichZurich 8057Switzerland Institute of Plant Sciences and Genetics in Agriculture The Robert H.Smith Faculty of AgricultureFood and EnvironmentThe Hebrew University of JerusalemRehovot 7610001Israel School of Biological Sciences Georgia Institute of Technology310 Ferst DriveAtlantaGA 30332United States Department of Plant Pathology North Carolina State UniversityRaleighNC 27607United States Sino-French Institute for Earth System Science College of Urban and Environmental SciencePeking UniversityBeijing 100871China National Hulunber Grassland Ecosystem Observation and Research Station Institute of Agricultural Resources and Regional PlanningChinese Academy of Agricultural SciencesBeijing 100081China

Grassland is one of the largest terrestrial biomes,providing critical ecosystem services such as food production,biodiversity conservation,and climate change *** climate change and land-use intensification have been causing grassland degradation and desertification *** one of the primary medium for ecosystem energy flow and biogeochemical cycling,grassland carbon(C)cycling is the most fundamental process for maintaining ecosystem *** this review,we first summarize recent advances in our understanding of the mechanisms underpinning spatial and temporal patterns of the grassland C cycle,discuss the importance of grasslands in regulating inter-and intra-annual variations in global C fluxes,and explore the previously unappreciated complexity in abiotic processes controlling the grassland C balance,including soil inorganic C accumulation,photochemical and thermal degradation,and wind *** also discuss how climate and land-use changes could alter the grassland C balance by modifying the water budget,nutrient cycling and additional plant and soil ***,we examine why and how increasing aridity and improper land use may induce significant losses in grassland C ***,we identify several priorities for future grassland C research,including improving understanding of abiotic processes in the grassland C cycle,strengthening monitoring of grassland C dynamics by integrating ground inventory,flux monitoring,and modern remote sensing techniques,and selecting appropriate plant species combinations with suitable traits and strong resistance to climate fluctuations,which would help design sustainable grassland restoration strategies in a changing climate.

关键词： Climate changes Land-use change Soil Biotic and abiotic interactions Grassland degradation Grassland restoration Carbon accounting Carbon storage and sequestration mechanisms

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Research on WebAssembly Runtimes: A Survey

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ACM Transactions on Software Engineering and Methodology 1000年

作者： Yixuan Zhang Mugeng Liu Haoyu Wang Yun Ma Gang Huang Xuanzhe Liu Key Laboratory of High Confidence Software Technologies (Peking University) Ministry of Education School of Computer Science Peking University China Huazhong University of Science and Technology China Institute for Artificial Intelligence Peking University China School of Computer Science Peking University National Key Laboratory of Data Space Technology and System China

WebAssembly (abbreviated as Wasm) was initially introduced for the Web and quickly extended its reach into various domains beyond the Web. To create Wasm applications, developers can compile high-level programming languages into Wasm binaries or manually write the textual format of Wasm and translate it into Wasm binaries by the toolchain. Regardless of whether it is utilized within or outside the Web, the execution of Wasm binaries is supported by the Wasm runtime. Such a runtime provides a secure, memory-efficient, and sandboxed execution environment to execute Wasm binaries. This paper provides a comprehensive survey of research on Wasm runtimes with 103 collected research papers related to Wasm runtimes following the traditional systematic literature review process. It characterizes existing studies from two different angles, including the internal research of Wasm runtimes (Wasm runtime design, testing, and analysis) and the external research (applying Wasm runtimes to various domains). This paper also proposes future research directions about Wasm runtimes.

关键词： WebAssembly WebAssembly runtime WebAssembly system Interface

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α [email protected] carrier modulated platinum single atoms for high-efficient solar cells

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Applied Surface science 2023年 611卷

作者： Jixin Yao Jie Wang Wen Wang Ying Meng Haibo Wang Shibin Lu Feng Du Li Yang Xueqin Zuo Guang Li Anhui Province Key Laboratory of simulation and design for Electronic information system Universities Joint Key Laboratory of photoelectric detection Science and Technology in Anhui Province Hefei Normal University Hefei 230601 China School of Materials Science and Engineering Anhui Key Laboratory of Information Materials and Devices Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education Institute of Physical Science and Information Technology Anhui University Hefei 230601 China Institute of Materials Science and Devices School of Materials Science and Engineering Suzhou University of Science and Technology Suzhou 215011 China

Single-atom electrocatalysts have been proven to be the great promising catalysts for energy-related fields yet their active site structure remains elusive, especially in dye-sensitized solar cell (DSSC). Herein, atomically dispersed Pt is anchored into α [email protected] carrier (Pt/α [email protected] ), which vigorously stimulates the activity of Pt single atoms under the strong metal interaction. As expected, the Pt/α [email protected] as the cathode in DSSC exhibits high power conversion efficiency (PCE) of 9.67%, exceeding Pt electrode (7.61%). X-ray photoelectron spectroscopy combined with density functional theory calculations reveals that the high activity is mainly derived from charge re-distribution of Pt/α [email protected] caused by the interaction between Pt atoms and α-MoC. This interaction not only achieves the optimized adsorption/desorption energy of reactants but also brings synergic advantages to expedite the reaction kinetics of the overall system. This work paves further research prospects for charge re-distribution, stimulating electrocatalysts to effectively enhance their catalytic properties by an atomic-level engineering strategy.

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Wave Interaction with a Concentric Bottom-Mounted Cylinder system with Dual Porous Ring Plates

SSRN

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SSRN 2022年

作者： Zhang, MoHan Wang, GuangYuan Wang, Jin Zhao, PengYuan Key Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of Mechanics Chinese Academy of Sciences Beijing100190 China National Engineering Research Center of Port Hydraulic Construction Technology Tianjin Research Institute for Water Transport Engineering M.O.T. Tianjin300000 China School of Engineering Science University of Chinese Academy of Sciences Beijing100049 China China Ship Development and Design Center Wuhan430000 China

The interaction between linear surface waves and a concentric bottom-mounted cylinder system has been investigated using the eigenfunction expansion approach. This system contains an outer porous cylinder and an inner impermeable cylinder, which are connected by dual porous ring plates. Both cylinders are surface-piercing and rigidly installed on the flat bottom of the ocean, while the porous ring plates are fixed below the free water surface. Analytical solutions were obtained using matching boundary conditions. According to the velocity potential, the hydrodynamic forces of the system and the free surface elevation are calculated. The numerical results obtained for limiting cases agreed well with the published results. The results of the study show that reducing the draft, spacing, and permeability of the dual plates all contribute to reduce the surge force of the inner cylinder. However, the significance of the lower plate is mainly to cope with the condition where the water surface is lower than the upper plate. © 2022, The Authors. All rights reserved.

关键词： Surface waves

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Approaching the Fundamental Limit of Orbital Angular Momentum Multiplexing Through a Hologram Metasurface

arXiv

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arXiv 2021年

作者： Yuan, Shuai S.A. Wu, Jie Chen, Menglin L.N. Lan, Zhihao Zhang, Liang Sun, Sheng Huang, Zhixiang Chen, Xiaoming Zheng, Shilie Jiang, Li Jun Zhang, Xianmin Sha, Wei E.I. College of Information Science and Electronic Engineering Zhejiang University Hangzhou310027 China Ministry of Education The Key Laboratory of Electromagnetic Environmental Sensing Department of Education of Anhui Province Anhui University Hefei230039 China Department of Electrical and Electronic Engineering The University of Hong Kong Hong Kong Department of Electronic and Electrical Engineering University College London Torrington Place LondonWC1E 7JE United Kingdom Anhui Province Key Laboratory of Simulation and Design for Electronic Information System Hefei Normal University Hefei230601 China School of Electronic Science and Engineering University of Electronic Science and Technology of China Chengdu611731 China School of Information and Communications Engineering Xi’an Jiaotong University Xi’an710049 China

Establishing and approaching the fundamental limit of orbital angular momentum (OAM) multiplexing are necessary and increasingly urgent for current multiple-input multiple-output research. In this work, we elaborate the fundamental limit in terms of independent scattering channels (or the degrees of freedom of scattered fields) through angular-spectral analysis, in conjunction with a rigorous Green’s function method. The scattering-channel limit is universal for arbitrary spatial-mode multiplexing, which is launched by a planar electromagnetic device, such as antenna, metasurface, etc., with a predefined physical size. As a proof of concept, we demonstrate both theoretically and experimentally the limit by a phase-only metasurface hologram that transforms orthogonal OAM modes to plane-wave modes scattered at critically separated angular-spectral regions. Particularly, a minimax optimization algorithm is applied to suppress angular-spectrum aliasing, achieving good performances in both full-wave simulation and experimental measurement at microwave frequencies. This work offers a theoretical upper bound and corresponding approach route for engineering designs of OAM multiplexing. Copyright © 2021, The Authors. All rights reserved.

关键词： Spectrum analysis

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Intelligent Identification of Building Patches and Assessment of Roof Greening Suitability in High-density Urban Areas:A Case Study of Chengdu

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Journal of Resources and Ecology 2022年第2期13卷 247-256页

作者： LUO Luhua CHEN Mingjie DONG Lulu SU Wei LI Xin HU Xiaodong ZHANG Xin LI Chen CHENG Weiming SHI Hanning LUO Jiancheng Faculty of Geomatics Lanzhou Jiaotong UniversityLanzhou 730070China National-Local Joint Engineering Research Center of Technological and Application for National Geographic State Monitoring Lanzhou 730070China Gansu Provincial Engineering Laboratory for National Geographic State Monitoring Lanzhou 730070China College of Geoscience and Surveying Engineering China University of Mining&Technology(Bejing)Beijing 100083China School of Earth Science and Engineering Hebei University of EngineeringHebei 056000China Tianjin University Urban Planning and Design Institute Co.Ltd Tianjin 300072China State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China The ImageSky International Co.Ltd SuzhouJiangsu 215000China Aerospace Information Research Institute Chinese Academy of SciencesBeijing 100101China School of Architecture Tianjin UniversityTianjin 300072China

With the expansion of a city,the urban green space is occupied and the urban heat island effect is *** the roof surfaces of urban buildings is an effective way to increase the area of urban green space and improve the urban ecological *** provide effective data support for urban green space planning,this paper used high-resolution images to(1)obtain accurate building spots on the map of the study area through deep learning assisted manual correction;and(2)establish an evaluation index system of roof greening including the characteristics of the roof itself,the natural environment and the human society *** weight values of attributes not related to the roof itself were calculated by Analytic Hierarchy Process(AHP).The suitable green roof locations were evaluated by spatial join,weighted superposition and other spatial analysis *** the areas within the Chengdu city’s third ring road as the study area,the results show that an accurate building pattern obtained by deep learning greatly improves the efficiency of the *** roof surfaces unsuitable for greening can be effectively classified by the method of feature extraction,with an accuracy of 86.58%.The roofs suitable for greening account for 48.08%,among which,the high-suitability roofs,medium-suitability roofs and low-suitability roofs represent 45.32%,38.95%and 15.73%.The high-suitability green buildings are mainly distributed in the first ring district and the western area outside the first ring district in *** paper is useful for solving the current problem of the more saturated high-density urban area and allowing the expansion of the urban ecological environment.

关键词： deep learning roof greening suitability assessment spatial join weighted overlay

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Numerical Comparison of Transpiration Cooling designs Using Real Gas Effects and Approximate Gas Model

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Journal of Physics: Conference Series 2021年第1期2097卷

作者： Meng Wang Jianhua Wang Fei He Kang Qian Yadong Wu Guangsheng Zhu CAS Key Laboratory of Mechanical Behaviour and Design of Materials Department of Thermal Science and Energy Engineering University of Science and Technology of China Hefei 230027 Anhui China Beijing Institute of Astronautical System Engineering Beijing 100076 China

In the severe high-temperature environment caused by aerodynamic heating, the vibrational excitation, dissociation and ionization of gas may successively occur, which are known as real gas effects. Under the real gas effects, the thermodynamic properties of gas vary drastically and significantly influence the performances of the active thermal protection system of hypersonic vehicles, especially in the case with coolant outflow, for example transpiration cooling. This paper numerically investigates the transpiration cooling performance with the consideration of the interaction between coolant outflow and hypersonic flow under the real gas effects. The mathematical models and coupled numerical strategy are firstly validated by experimental data, then the influences of real gas effects on the transpiration cooling of a wedged leading edge (WLE) are studied under a flight Mach number range from 8 to 12 and a flight height of 40 km. The analysis and discussions of the numerical results reveal some important phenomena and demonstrate the need to consider real gas effects.

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