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Quality of forwarding-based data disseminating strategy in urban VANET

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The Journal of China Universities of Posts and Telecommunications 2015年第6期22卷 1-9,50页

作者： Wang Wenjie luo tao School of Telecommunication Engineering Beijing University of Posts and Telecommunications

As for safety applications of vehicular Ad-hoc network （VANET）, many valuable broadcast protocols have been proposed nowadays, most of which are based on either senders or receivers. In fact, sender-based protocols would fall into invalidation due to high mobility of network, while receiver-based ones would generate extra delay. Combining both the advantages of the two schemes, this paper proposes an efficient and reliable broadcast protocol based on quality of forwarding （ERBPQF） of candidate nodes. In ERBPQF, a double-phase relay scheme is presented to reach fast message dissemination in the first phase and to ensure high packet delivery ratio （PDR） in the second phase. Then, considering signal fading, channel contention, queuing delay, broadcast interference and high mobility of vehicles, a new metric called quality of forwarding （QoF） for relay selection is further proposed. The simulation results show that the delay and dissemination efficiency （DE） of ERBPQF outperforms slotted-1 protocol, accompanying with the achievement of more than 95% PDR.

关键词： broadcast protocol quality of forwarding relay strategy VANET

An efficient 3D ordered mesoporous Cu sphere array electrocatalyst for carbon dioxide electrochemical reduction

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Journal of Materials Science & Technology 2020年第20期52卷 95-106页

作者： Jun-tao luo Guo-Long Zang Chuang Hu Tianjin Key Lab of Indoor Air Environmental Quality Control School of Environmental Science and EngineeringTianjin UniversityNo.92 Weijin RoadNankai DistrictTianjin 300072China

The electrochemical reduction of CO2 is a promising solution for sustainable energy research and carbon ***,this solution has been challenged by the lack of active and selective ***,we report a two-step synthesis of 3D ordered mesoporous Cu sphere arrays,which is fabricated by a dual template method using a poly methyl methacrylate(PMMA) inverse opal and the nonionic surfactant Brij 58 to template the mesostructure within the regular voids of a colloidal *** re,the well-ordered 3D interconnected bi-continuous mesopore s structure has advantages of abundant exposed catalytically active sites,efficient mass transport,and high electrical conductivity,which result in excellent electrocatalytic CO2 RR perfo *** prepared 3D ordered mesoporous Cu sphere array(3 D-OMCuSA) exhibits a low onset potential of-0.4 V at a 1 mA cm^-2 electrode current density,a low Tafel slope of 109.6 mV per decade and a long-term durability in 0.1 M potassium *** distinct features of 3 D-OMCuSA render it a promising method for the further develo p ment of advanced electrocatalytic materials for CO2 reduction.

关键词： 3D ordered mesoporous Cu sphere array electrocatalyst Copper nanoparticles Dual-template method CO2 electrochemical reduction reaction

Fog computing for vehicular Ad-hoc networks: paradigms, scenarios, and issues

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The Journal of China Universities of Posts and Telecommunications 2016年第2期23卷 56-65,96页

作者： Kang Kai Wang Cong luo tao School of Software Engineering Beijing University of Posts and Telecommunications Key Laboratory of Trustworthy Distributed Computing and Service Beijing University of Posts Telecommunications School of Information and Communication Engineering Beijing University of Posts and Telecommunications Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts Telecommunications

Vehicular Ad-hoc networks（VANETs） are kinds of mobile Ad-hoc networks（MANETs）, which consist of mobile vehicles with on-board units（OBUs） and roadside units（RSUs）. With the rapid development of computation and communication technologies, peripheral or incremental changes in VANETs evolve into a revolution in process. Cloud computing as a solution has been deployed to satisfy vehicles in VANETs which are expected to require resources（such as computing, storage and networking）. Recently, with special requirements of mobility, location awareness, and low latency, there has been growing interest in research into the role of fog computing in VANETs. The merging of fog computing with VANETs opens an area of possibilities for applications and services on the edge of the cloud computing. Fog computing deploys highly virtualized computing and communication facilities at the proximity of mobile vehicles in VANET. Mobile vehicles in VANET can also demand services of low-latency and short-distance local connections via fog computing. This paper presents the current state of the research and future perspectives of fog computing in VANETs. Moreover, we discuss the characteristics of fog computing and services based on fog computing platform provided for VANETs. In this paper, some opportunities for challenges and issues are mentioned, related techniques that need to be considered have been discussed in the context of fog computing in VANETs. Finally, we discuss about research directions of potential future work for fog computing in VANETs. Within this article, readers can have a more thorough understanding of fog computing for VANETs and the trends in this domain.

关键词： VANET fog computing cloud computing application vehicular cloud computing

Singular limits for the Navier-Stokes-Poisson equations of the viscous plasma with the strong density boundary layer

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Science China Mathematics 2023年第7期66卷 1495-1528页

作者： Qiangchang Ju tao luo Xin Xu Institute of Applied Physics and Computational Mathematics Beijing 100088China Department of Mathematics City University of Hong KongHong KongChina School of Mathematical Sciences and College of Oceanic and Atmospheric Sciences Ocean University of ChinaQingdao 266100China

The quasi-neutral limit of the Navier-Stokes-Poisson system modeling a viscous plasma with vanishing viscosity coefficients in the half-space■is rigorously proved under a Navier-slip boundary condition for velocity and the Dirichlet boundary condition for electric *** is achieved by establishing the nonlinear stability of the approximation solutions involving the strong boundary layer in density and electric potential,which comes from the breakdown of the quasi-neutrality near the boundary,and dealing with the difficulty of the interaction of this strong boundary layer with the weak boundary layer of the velocity field.

关键词： Navier-Stokes-Poisson equations interaction of strong and weak boundary layers singular limit

A New Type of Absorbance Sensors Based on Long-Period Fiber Gratings

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Chinese Physics Letters 2011年第5期28卷 128-131页

作者： luo tao GU Zheng-Tian Laboratory of Photo-electric Functional Films College of ScienceUniversity of Shanghai for Science and TechnologyShanghai 200093

A new absorbance sensor based on long-period fiber gratings(LPFGs)is presented,The measurand is coated on the cladding of the *** is found that the depth of the stop band of the LPFG spectrum will be strongly affected by the absorbance of the measurand if an optimum coating thickness is *** analysis showsthat within the optimal thickness range,the cladding modes could transform into the overlay modes and interact with the measurand more *** absorbance sensitivity of 7×10^(3)is available when the sensor structure is optimized.

关键词： fiber cladding optimum

Dynamic subcarrier and power allocation based on cooperative game theory in symmetric cooperative OFDMA networks

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The Journal of China Universities of Posts and Telecommunications 2011年第2期18卷 9-16页

作者： LIU Wei luo tao YUE Guang-xin Key Laboratory of Universal Wireless Communication Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

In order to improve the efficiency and fairness of radio resource utilization,a scheme of dynamic cooperative subcarrier and power allocation based on Nash bargaining solution（NBS-DCSPA） is proposed in the uplink of a three-node symmetric cooperative orthogonal frequency division multiple access（OFDMA） *** the proposed NBS-DCSPA scheme,resource allocation problem is formulated as a two-person subcarrier and power allocation bargaining game（SPABG） to maximize the system utility,under the constraints of each user＇s maximal power and minimal rate,while considering the fairness between the two ***,the equivalent direct channel gain of the relay link is introduced to decide the transmission mode of each ***,all subcarriers can be dynamically allocated to the two users in terms of their selected transmission *** that,the adaptive power allocation scheme combined with dynamic subcarrier allocation is optimized according to ***,computer simulation is conducted to show the efficiency and fairness performance of the proposed NBS-DCSPA scheme.

关键词： cooperative relay OFDMA radio resource allocation NBS fairness

Cluster-Based Interference-Free MAC Protocol with Load Aware in Software Defined VANET

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China Communications 2020年第12期17卷 217-234页

作者： Yangshui Gao tao luo Xinxin He Zhilong Zhang Beijing Laboratory of Advanced Information Networks Beijing University of Posts and TelecommunicationsBeijing 100876China Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and TelecommunicationsBeijing 100876China School of Mathematics and Computer Dali UniversityDali 671003China

In order to reduce the interference,a novel,cluster-based medium access control(MAC)protocol with load aware for VANETs is proposed in this ***,all vehicles on roads are grouped into stable clusters in the light of their direction,number of neighbors,link reliability,and traffic *** utilizing the advantages of centralized control in software defined VANETs(SDVN),cluster stability can be maintained in ***,a contention-free MAC mechanism composed of inter-cluster multi-channel allocation and intra-cluster dynamic TDMA frame allocation is proposed to prevent co-channel interference and hidden terminal *** results show that the proposed protocol outperforms some existing protocols in cluster stability,delivery ratio,throughput and delay performance.

关键词： SDVN MAC co-channel interference non-safety services cluster

Existence of Periodic Solutions of Nonlinear Systems with Nonlinear Boundary Conditions

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Acta Mathematica Sinica,English Series 1995年第4期11卷 439-445页

作者： Xiaolin Xiang tao luo Guizhou University Academia Sinica

In this paper we consider the periodic solutions of nonlinear parabolic systems with nonlinear boundary *** constructing the Poincare operator,we obtain the existence of Wp2β-periodic weak solutions under some reason... 详细信息

关键词： Nonlinear parabolic systems Nonlinear boundary conditions Periodic solutions Semigroup

Tailoring sintering-resistant thermal barrier coatings by considering critical healing width of two-dimensional interlamellar pores

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Journal of Advanced Ceramics 2023年第7期12卷 1317-1330页

作者： Guang-Rong Li tao Liu Xiao-tao luo Guan-Jun Yang Chang-Jiu Li State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi'an Jiaotong UniversityXi'an 710049China

Large degradation in thermal insulation and strain tolerance is a main headache and a primary cause of the failure for plasma-sprayed thermal barrier coatings(TBCs)during *** mechanism behind such degradation is the healing of interlamellar pores formed by multiple connections between edges of a pore,which significantly speeds up healing during thermal *** objective of this study is to obtain sintering-resistant TBCs by tailoring the width of interlamellar pores to avoid multiple ***,the mechanism responsible for the multiple connections was *** splat surfaces before and after thermal treatments were characterized via an atomic force microscope(AFM).The roughening of the pore surface occurs during thermal exposure,along with the grain growth inside the ***,the local surface height increases,which causes multiple connections and healing of the interlamellar ***,critical widths of the interlamellar pores for avoiding the multiple connections during thermal exposure are established by correlating the extent of surface roughening with the growth of individual *** height increase of the splat surface and the growth of the grain size(D)were found to increase with the exposure temperature and duration.A relationship linking the height increase and the growth of the grain size induced by thermal exposure in plasma-sprayed ceramic splats was ***,composite TBCs were prepared to form wide interlamellar pores in the *** this design,the increases in the thermal conductivity(λ)and the elastic modulus(E)can be prevented to a large ***,sintering-resistant TBCs that maintain high thermal insulation and strain tolerance,even afer long thermal exposure,can be created.

关键词： thermal barrier coatings(TBCs) air plasma spraying(APS) multiple connections grain growth sintering-resistant structure