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电子科学技术评论 2005年第2期 55-55页

edge Computing Based Applications in Vehicular Environments:Comparative Study and Main Issues

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Journal of Computer Science & Technology 2019年第4期34卷 869-886页

作者： Leo Mendiboure Mohamed-Aymen Chalouf Francine Krief LaBRI Laboratory University of BordeauxTalence 33400France IRISA Laboratory University of Rennes 1Lannion 22300France LaBRI Laboratory Bordeaux INPTalence 33400France

Despite the expanded efforts,the vehicular ad-hoc networks(VANETs)are still facing many challenges such as network performances,network scalability and *** solutions have been proposed to overcome these obstacles,and the edge computing,an extension of the cloud computing,is one of *** edge computing,communication,storage and computational capabilities are brought closer to end *** could offer many benefits to the global vehicular network including,for example,lower latency,network off-loading and context-awareness(location,environment factors,etc.).Different approaches of edge computing have been developed:mobile edge computing(MEC),fog computing(FC)and cloudlet are the main *** introducing the vehicular environment background,this paper aims to study and compare these different *** that purpose their main features are compared and the state-of-the-art applications in VANETs are *** addition,MEC,FC,and cloudlet are classified and their suitability level is debated for different types of vehicular ***,some challenges and future research directions in the fields of edge computing and VANETs are discussed.

关键词： cloud computing edge computing fog computing cloudlet vehicular network

Dynamically reconfigurable topological edge state in phase change photonic crystals

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Science Bulletin 2019年第12期64卷 814-822页

作者： Tun Cao Linhan Fang Ying Cao Nan Li Zhiyou Fan Zhiguo Tao School of Optoelectronic Engineering and Instrumentation Science Dalian University of TechnologyDalian 116024China China North Vehicle Research Institute Beijing 100072China

The observation of topological edge states(TESs) revolutionized our understanding of scattering and propagation of electromagnetic(EM) waves. Supported by topological robustness, the TES at the interface between trivial and non-trivial insulators was not reflected from the structural disorders and imperfections. Recently topological photonic crystals(PhCs) were demonstrated to obtain remarkable one-way propagation of the TES, having the advantages of lossless propagation, dense integration, and high fabrication tolerance over conventional PhCs. Nevertheless, the lack of reversible switching of TES possesses significant limitations in helicity/spin filtering and tunable photonic devices. We proposed a topological PhC based on a prototypical phase-change material, Ge2 Sb2 Te5(GST225) to solve the problem. We find that at a particular frequency, the TES within the structure can be reversibly switched between "on"and "off" by transiting the GST225 structural state between amorphous and crystalline. Moreover, the topology of the PhC was maintained since the tuning of TES was achieved by varying the refractive index of GST225 instead of the structural geometry. This provides a continuous change of the spectral position of the photonic bandgap and TES by gradually crystallising the GST225. We show that the phase change of GST225 from amorphous to crystalline and vice versa can be engineered in nanoseconds. Our proof of concept may offer a platform for dynamically tuning the TESs that might otherwise be challenging to attain in photonic systems. We expect it to have potential applications for photonic devices in topological optical circuits and scatter-free one-way light propagation.

关键词： Phase change materials Photonic crystals Topological edge states Tunability Reconfigurability

edge and lithium concentration effects on intercalation kinetics for graphite anodes

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Journal of Energy Chemistry 2024年第3期90卷 337-347,I0009页

作者： Keming Zhu Denis Kramer Chao Peng School of Mechanical and Precision Instrument Engineering Xi'an University of TechnologyXi'an 710048ShanxiChina Faculty of Mechanical Engineering Helmut-Schmidt UniversityHamburg 22043Germany School of Engineering University of SouthamptonSouthampton SO171BJUK Multiscale Crystal Materials Research Center Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen 518055GuangdongChina

Graphite interfaces are an important part of the anode in lithium-ion batteries(LIBs),significantly influencing Li intercalation *** anodes adopt different stacking sequences depending on the concentration of the intercalated Li *** this work,we performed first-principles calculations to comprehensively address the energetics and dynamics of Li intercalation and Li vacancy diffusion near the no n-basal edges of graphite,namely the armchair and zigzag-edges,at high Li *** find that surface effects persist in stage-Ⅱ that bind Li strongly at the edge ***,the pronounced effect previously identified at the zigzag edge of pristine graphite is reduced in LiC_(12),penetrating only to the subsurface site,and eventually disappearing in LiC_(6).Consequently,the distinctive surface state at the zigzag edge significantly impacts and restrains the charging rate at the initial lithiation of graphite anodes,whilst diminishes with an increasing degree of *** diffusion time for Li hopping to the bulk site from either the zigzag edge or the armchair edge in LiC_(6) was observed during high state of charge due to charge *** controlling Li occupation and diffusion kinetics at this stage is also crucial for enhancing the charge rate.

关键词： Graphite anode edge Interface Lithium-ion batteries Density functional theory

First principle study of edge topological defect-modulated electronic and magnetic properties in zigzag graphene nanoribbons

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Chinese Physics B 2017年第10期26卷 169-174页

作者：黄露婷陈铮王永欣卢艳丽 State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical University

Zigzag graphene nanoribbon （ZGNR） is a promising candidate for next-generation spintronic devices. Development of the field requires potential systems with variable and adjustable electromagnetic properties. Here we show a detailed investigation of ZGNR decorated with edge topological defects （ED-ZGNR） synthesized in laboratory by Ruffieux in 2015 [Pascal Ruffieux, Shiyong Wang, Bo Yang, et al. 2015 Nature 531 489]. The pristine ED-ZGNR in the ground state is an antiferromagnetic semiconductor, and the acquired band structure is significantly changed compared with that of perfect ZGNR. After doping heteroatoms on the edge, the breaking of degeneration of band structure makes the doped ribbon a half-semi-metal, and nonzero magnetic moments are induced. Our results indicate the tunable electronic and magnetic properties of ZGNR by deriving unique edge state from topological defect, which opens a new route to practical nano devices based on ZGNR.

关键词： graphene nanoribbons topological defect spin edge

Numerical Analysis and PIV Measurements of Tip Vortex in an Axial Rotor with Skewed-Swept Blade at Its Leading edge

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Journal of Thermal Science 2004年第1期13卷 16-23页

作者： Guanghui Wu Lijie Zheng Keqi Wu Huazhong Univ Sci & Technol Sch Energy & Power Engn Wuhan 430074 Peoples R China

Based on the characteristics of axial fans of outdoor units of centralized air-conditioners, using the finite-volume method, applying three-dimensional steady Reynolds-averaged Navier-Stokes equations coupled with Spalart-Allmaras turbulence model equation, and adopting SIMPLE algorithm, numerical analysis is made and applied to analyze the internal flow field of axial rotors with skewed-swept blade at its leading edge. This numerical simulation mainly investigates the formation and development of the tip vortex. Based on the tip vortex characteristics that have been captured, the internal flow numerical results are compared with those obtained by the PIV experiments. This comparison indicates a good agreement between numerical results and PIV results, thus proving the validity of the numerical simulation. In addition, based on the internal flow analyses of the axial rotor with skewed-swept blade at its leading edge, different flow phenomena features are presented. These flow features can be used for further improvements of the present rotor performance characteristics.

关键词： axial rotor with skewed-swept blade at its leading edge numerical simulation tip vortex PIV experiment

edgence: A Blockchain-Enabled edge-Computing Platform for Intelligent IoT-Based dApps

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China Communications 2020年第4期17卷 78-87页

作者： Jinliang Xu Shangguang Wang Ao Zhou Fangchun Yang State Key Laboratory of Networking and Switching Technology Beijing University of Posts and TelecommunicationsBeijing 100876China

Nowadays scalable Io T management is a bottleneck of Io T development due to the geographically dispersed distribution, fragmented ownerships, and ever-growing population of Io T devices. To intelligently manage massive decentralized applications(d Apps) in Io T usecases, edgence(edge + intellig ENCE) is proposed to use edge clouds to access Io T devices and users, and then use its in-built blockchain to realize self-governing and self-supervision of the edge clouds. edgence proposes to use masternode technology to introduce Io T devices and users into a closed blockchain system, which can extend the range of blockchain to Io T-based d Apps. Further, masternodes do good to scalability by raising the TPS(transactions per second) of the blockchain network. To support various d Apps, a three-tier validation is proposed, namely script validation, smartcontract validation, and masternode validation. To avoid energy consumption resulted by blockchain consensus, edgence proposes a random but verifiable way to elect a masternode to generate each new block. The potential of the tailored edgence is shown by examples of decentralized crowdsourcing and AI training.

关键词： mobile edge computing IoT crowd-intelligence blockchain dApp

A new method for deburring of servo valve core edge based on ultraprecision cutting with the designed monocrystalline diamond tool

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Science China(Technological Sciences) 2019年第10期62卷 1805-1815页

作者： AN QingLong DANG JiaQiang LIU GongYu Dong DaPeng MING WeiWei CHEN Ming State Key Laboratory of Mechanical System and Vibration School of Mechanical Engineering Shanghai Jiao Tong University

Deburring of high-precision components to their micrometer features without any damage is very important but of great difficulty as the burr-to-functionality size ratio increases. To this end, this paper proposes a new deburring method in which the micro burr should be directly removed based on ultraprecision cutting with the designed monocrystalline diamond tool. To determine the feasibility of the proposed method, this paper applies it for deburring of the precision working edge of the servo valve core. Firstly, the monocrystalline diamond tool is carefully designed by covering a variety of topics like rake angle,clearance angle, edge radius. Then, the finite element(FE) simulation was conducted to characterize the deburring performance during the removal of the micro burr produced by the single abrasive grinding. Finally, an innovative self-designed deburring system was introduced and the deburring process was evaluated in terms of cutting forces, temperatures, tool wear mechanisms and deburring quality of the working edges by experiments. The FE simulation results indicate the suitability of the proposed deburring method. Meanwhile, the experimental findings agree well with simulation results and show that ultraprecision cutting with the specialized monocrystalline diamond tool could be successfully used for deburring of servo valve core edge without any damage. This work can provide technical guidance for similar engineering applications, and thus brings an increase to the machining efficiency for the manufacture of precision components.

关键词： monocrystalline diamond tool FE simulation deburring method servo valve core edge ultraprecision cutting

Numerical studies of reverse flows controlled by undulating leading edge

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Science China(Physics,Mechanics & Astronomy) 2019年第7期62卷 95-107页

作者： Biao Wang Jian Liu QiBing Li YunJun Yang ZhiXiang Xiao School of Aerospace Tsinghua University China Academy of Aerospace Aerodynamics

The improved delayed detached-eddy simulation(IDDES) method is used to simulate the reverse flows past an NACA0012 airfoil at medium(10°) and large(30°) angles of attack. The numerical results of the baseline configuration are compared with the available measurements. The effects of the undulating leading edge with four different amplitudes are compared and analyzed at angle of attack of 10°. Based on these analyses, the amplitude of A/C=0.04 yields the best performance. Compared with the uncontrolled case, the performances of the undulating leading edge are greatly improved with reducing of the aerodynamic fluctuations. Furthermore, the mechanisms of performance are explored by comparing the local flow structures near the undulations.

关键词： IDDES method reverse flow flow control undulating leading edge

edge detection on terahertz pulse imaging of dehydrated cutaneous malignant melanoma embedded in paraffin

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Frontiers of Optoelectronics 2019年第3期12卷 317-323页

作者： Jiayu LI Yijun XIE Ping SUN Beijing Key Laboratory of Applied Optics Department of PhysicsBeijing Normal UniversityBeijing 100875China

Terahertz pulse imaging of cutaneous malignant melanoma dehydrated by ethanol and embedded in paraffin was carried out across a frequency range of 0.2- 1.4 THz. First, the tissue images based on the time-domain electric-field amplitude information were acquired. Then the areas of normal and cancerous tissues were determined using multi-scale, multi-azimuth and multi-structural element mathematical morphology. The physical meaning of the image was analyzed by calculation of the refractive index and absorption coefficient of cutaneous malignant melanoma in different areas. The refractive index of both normal and cancerous tissues showed anomalous dispersion. The refractive index of cancerous tissues tended to vary between 0.2 and 0.7 THz, while that of normal and fat tissues remain almost unchanged. The absorption of cancerous tissues was higher, with a maximum at 0.37 THz. We concluded that both the refractive index and absorption coefficient differ considerably between normal and cancerous tissues, and the areas of normal and abnormal tissues can be identified using THz pulse imaging combined with mathematical morphology. The method for edge detection of terahertz pulse imaging of cutaneous malignant melanoma provides a reference for the safe surgical removal of malignant tumors.

关键词： terahertz pulse imaging edge detection mathematical morphology cutaneous malignant melanoma refractive index absorption coefficient