Primary analysis of upper-air temperature change in china

Xue DeQiang,Tan ZheMin,Gong Dianli,Wang xingtang 한국기상학회 2006 한국기상학회 학술대회 논문집 Vol.2006 No.-

Effect of the scanning speed of laser cladding on microstructure and mechanical properties of WC/Ni composite coatings

Wenqiang Sun,Deqiang Zhang,Xiang Chen,Keyan Wang,Jiqing Zhang,Yunjie Jia 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.2

Cold work dies (of Cr12MoV) surface of the WC/Ni composite coating prepared by laser cladding can be used to quickly repair worn areas of dies. The composition, hardness, fracture morphology, microstructure, and shear strength of the coating were characterized by microhardness tester, universal tensile testing machine, XRD, EDS, and SEM. The results show that the main phase of the coating is composed are M 23 C 6 , FeNi 3 , Cr 7 C 3 , WC, W 2 C, Cr 2 B, Fe 2 B, and W 2 B. The change of scanning speed only changes the diffraction peak, but has little effect on the internal structure and strengthening mechanism of the coating. With the decrease of scanning speed, the powder deposition density per unit time increases, and a large number of pores and unmelted particles are mixed in the coating, which weakens the bonding strength between the coating and the substrate, and the fracture mechanism of the coating changes from quasi-cleavage fracture to brittle fracture.

Experimental study on the wake characteristics of the circular cylinder with the V-groove surface

Liu Ping,Wang Deqiang,Yan Fei 대한조선학회 2022 International Journal of Naval Architecture and Oc Vol.14 No.1

In order to understand the wake characteristics for the circular cylinder with the V-groove surface, the Particle Image Velocimetry (PIV) and Proper Orthogonal Decomposition (POD) technology are used to measure and analyze the flow field velocity and the flow characteristic of the wake flow of the circular cylinder with the V-groove surface. This study focuses on the length of the velocity gradient, the Reynolds stress, the turbulent kinetic energy, the vortex shedding process, and the velocity fluctuating characteristics of flow field with POD technology. Compared with the smooth cylinder, the velocity gradient of the circular cylinder with the V-groove surface are larger. The peak values of Reynolds stress of the circular cylinders with the V-groove surface (the peak values are 0.33, 0.28 and 0.24) is lower than that of the smooth cylinder (0.39), and the peak values of turbulent kinetic energy are also lower. The recirculation region of the circular cylinders with the V-groove surface is larger, the length of the recirculation region are increased by 5.9%, 13.0% and 16.1% respectively, and it implies the suppression of vortex by the V-groove structure. Otherwise, the correlation of POD mode coefficients is disturbed for the circular cylinders with the V-groove surface, further proving that the effect of V-groove structure on vortex shedding.

Filtration and regeneration behavior of polytetrafluoroethylene membrane for dusty gas treatment

Weidong Zhang,Deqiang Jiang,Junteng Liu,Zhongqi Ren,Wang Geng 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.4

With micron talcum particles and nano-CaCO3 powder as test dust, a series of experiments have been carried out to systematically study the gas filtration and regeneration behavior of polytetrafluoroethylene membrane, and some comparisons were made with common filter media. The experimental results showed that the PTFE membrane had a filtration efficiency of above 99.99% for micron particles, and excellent regeneration behavior was obtained, though a much higher initial pressure drop existed. Based on the results, it was concluded that the PTFE membrane is an excellent surface-filtration media for micron particles. Effects of operation parameters, including airflow velocity, particle concentration and particle characteristics were also investigated. To better understand the evolution of pressure drop during the filtration process, a mathematical model with operation parameters and characteristics of particles was derived from the gas-solid two-phase flow theories. A novel method on the determination of regeneration period of the filter media was put forward based on the analysis of the pressure drop according to this model

Transient Simulation Studies of Squirrel-Cage Induction Motor Directly Supplied with Aircraft Variable Frequency Power

Du, Xiaofei,Wang, Deqiang,Zhou, Yuanjun Journal of International Conference on Electrical 2014 Journal of international Conference on Electrical Vol.3 No.1

Aircraft variable frequency power and a new application of induction motor under the aero-power are introduced. The transient models and simulation of induction motor are reviewed. A new transient model and simulation method is presented that includes deep-bar effect and magnetic saturation. Dynamic magnetizing inductance, rotor resistance and leakage reactance are considered as varying parameters in state-space model. Base on known rotor structure and speed, these parameters can be calculated.

Collaborative Sub-channel Allocation with Power Control in Small Cell Networks

( Guang Yang ),( Yewen Cao ),( Deqiang Wang ),( Jian Xu ),( Changlei Wu ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.2

For enhancing the coverage of wireless networks and increasing the spectrum efficiency, small cell networks (SCNs) are considered to be one of the most prospective schemes. Most of the existing literature on resource allocation among non-cooperative small cell base stations (SBSs) has widely drawn close attention and there are only a small number of the cooperative ideas in SCNs. Based on the motivation, we further investigate the cooperative approach, which is formulated as a coalition formation game with power control algorithm (CFG-PC). First, we formulate the downlink sub-channel resource allocation problem in an SCN as a coalition formation game. Pareto order and utilitarian order are applied to form coalitions respectively. Second, to achieve more availability and efficiency power assignment, we expand and solve the power control using particle swarm optimization (PSO). Finally, with our proposed algorithm, each SBS can cooperatively work and eventually converge to a stable SBS partition. As far as the transmit rate of per SBS and the system rate are concerned respectively, simulation results indicate that our proposed CFG-PC has a significant advantage, relative to a classical coalition formation algorithm and the non-cooperative case.

Optimal Heterogeneous Distributed Storage Regenerating Code at Minimum Remote-Repair Bandwidth Regenerating Point

Jian Xu,Yewen Cao,Deqiang Wang,Changlei Wu,Guang Yang 한국전자통신연구원 2016 ETRI Journal Vol.38 No.3

Recently, a product-matrix (PM) framework was proposed to construct optimal regenerating codes for homogeneous distributed storage systems (DSSs). In this paper, we propose an extended PM (EPM) framework for coding of heterogeneous DSSs having different repair bandwidths but identical storage capacities. Based on the EPM framework, an explicit construction of minimum remote-repair bandwidth regenerating (MRBR) codes is presented for a specific heterogeneous DSS, where two geographically different datacenters with associated storage nodes are deployed. The data reconstruction and regeneration properties of the MRBR code are proved strictly. For the purpose of demonstration, an example implementation of MRBR code is provided. The presented MRBR code is the first optimal strict-regenerating code for heterogeneous DSSs. In addition, our proposed EPM framework can be applied to homogeneous systems also.

Different Tribological Behaviors of SiCp/AZ91 Composites Induced by Tailoring the Distribution of SiC Particles

Huan Liu,Nannan Lu,Xiaojun Wang,Xiaoshi Hu,Deqiang Chen 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.3

In this study, the wear behaviors of the solution-treated and as-extruded SiCp/AZ91D metal matrix composites with differentsizes and volume fractions of SiC particles were systematically investigated under different wear test parameters. The SiCparticles exhibited a typical necklace-type distribution in the solution-treated composites and a homogeneous distributionin the as-extruded composites. Wear tests results showed that the wear rates of the as-extruded composites were lower thanthat of the solution-treated composites almost under all testing conditions and with the same SiC size and volume fraction. However, the dominant wear mechanisms for these two types of composites were different. The typical necklace-type distributionof SiCpin the solution-treated composites could effectively promote the occurrence of delamination owing to theweak bonding between SiCpand matrix in the particle aggregated regions. By contrast, as the bond between disperse SiCpand matrix was enhanced, the homogeneous distribution of SiCpin the as-extruded composites could promote the occurrenceof adhesion and prevent the occurrence of delamination. Moreover, a higher applied load and higher volume fraction of SiCpobviously promoted the progress of delamination for the solution-treated composites, while the extent of the adhesive wear forthe as-extruded composites was mainly associated with the increase of the applied load, sliding velocity and SiC particle size.

SDN‐Based Hierarchical Agglomerative Clustering Algorithm for Interference Mitigation in Ultra‐Dense Small Cell Networks

Guang Yang,Yewen Cao,Amir Esmailpour,Deqiang Wang 한국전자통신연구원 2018 ETRI Journal Vol.40 No.2

Ultra‐dense small cell networks (UD‐SCNs) have been identified as a promising scheme for next‐generation wireless networks capable of meeting the ever‐increasing demand for higher transmission rates and better quality of service. However, UD‐SCNs will inevitably suffer from severe interference among the small cell base stations, which will lower their spectral efficiency. In this paper, we propose a software‐defined networking (SDN)‐based hierarchical agglomerative clustering (SDN‐HAC) framework, which leverages SDN to centrally control all sub‐channels in the network, and decides on cluster merging using a similarity criterion based on a suitability function. We evaluate the proposed algorithm through simulation. The obtained results show that the proposed algorithm performs well and improves system payoff by 18.19% and 436.34% when compared with the traditional network architecture algorithms and non‐cooperative scenarios, respectively.

Solution processable small molecules for organic light-emitting diodes

Duan, Lian,Hou, Liudong,Lee, Tae-Woo,Qiao, Juan,Zhang, Deqiang,Dong, Guifang,Wang, Liduo,Qiu, Yong Royal Society of Chemistry 2010 Journal of materials chemistry Vol.20 No.31

<P>Organic light-emitting diodes (OLEDs) based on vacuum deposited small molecules have undergone significant progress since the first efficient double-layered OLEDs were reported in 1987 by Tang and Van Slyke. Recently, solution processed small molecular OLEDs are also drawing more and more research attention, as such a technology combines advantages of the facile synthesis of small molecules and the low-cost solution process like polymers. The performance of OLEDs made by solution process is gradually catching up with their vacuum deposited counterparts. This feature article will review the device structures adopted to achieve high performance solution processed OLEDs, the development of solution processable small molecules, and the comparisons of the different nature of the films and devices fabricated by solution-process or by vacuum deposition. Finally, the prospects and remaining problems will be discussed.</P> <P>Graphic Abstract</P><P>Recent developments, prospects and remaining problems of organic light-emitting diodes based on solution processable small molecules are reviewed, with comparisons of the films and devices by solution-process or vacuum deposition. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b926348a'> </P>