Chongqing Communication College

Chongqing, China

Chongqing Communication College

Chongqing, China

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Yang J.,Chongqing Communication College | Zhang D.,Chinese electronic system engineering company | Chen L.,Chongqing Communication College | Yuan Y.,Chongqing Communication College
Journal of Convergence Information Technology | Year: 2012

Wireless Sensor Networks(WSNs) can real-time monitor, collect and process all kinds of information. They have wide applications. The demands of spectrum in WSNs rose sharply, thereby how to deal with the spectrum allocation of WSNs is a difficult problem. A dynamical and real-time spectrum allocation system is proposed, which was based on the network architecture of Internet of things by the means of Cognitive Radio and cloud computing, it include Cloud resource scheduling configuration, Real-time data memory, Distributional policy-making support and so on. Dynamic spectrum allocation system of WSNs assigned the spectrum dynamically and real-timely that it can improve the spectrum utilization rate. This system is an efficient path to face the spectrum needs of WSNs.


Zhao X.,Chongqing University | Yang Y.,Chongqing University | Wu G.,Yingxiuwan Hydropower Plant | Yang J.,Chongqing Communication College | Xue X.,Chongqing University
Journal of Convergence Information Technology | Year: 2012

The project portfolio selection has great strategic value for R&D projects. However, the decision makers have to rely on qualitative, dynamic and uncertain information in the decision process which could cause adverse effects on the portfolio outcome. To counteract these soft factors, technical capability, satisfactory degree of project benefit and the crossing similarity were selected as indicators to comprehensively and systematically evaluate candidate projects, and three different fuzzy approaches were proposed to quantify these indicators respectively. A multi-objective trade-off model was then constructed, and a simulated annealing genetic algorithm was introduced to solve it. An illustrative example was presented to verify the effectiveness of the approach.


Zhang H.C.,Chongqing Communication College | Wen X.,Institute of China Electronic System Engineering Company | Mo D.H.,Institute of China Electronic System Engineering Company
WIT Transactions on Information and Communication Technologies | Year: 2014

Mainly due to lack of protected physical boundary and limited energy resources, security and lifetime optimization are becoming the two of the vital issues for multi-hop wireless sensor networks. This paper presents a novel secure routing protocol to provide the security through probabilistic random walking and extends the network lifetime by balancing the energy consumption. The routing protocol is designed with two configurable parameters, security level and energy balance control (EBC). The security level provides the source location privacy by determining the probabilistic distribution of the random walking. According to the network energy consumption, EBC is used to enforce the energy balance and extend the lifetime. Theoretical analysis and simulation results show that the proposed routing protocol can provide excellent balance between routing efficiency and energy consumption while preventing routing trace-back attacks. © 2014 WIT Press.


Chen L.,Chongqing University | Chai Y.,Chongqing University | Wu R.,Anhui University | Yang J.,Chongqing Communication College
IEEE Transactions on Circuits and Systems II: Express Briefs | Year: 2012

This brief discusses the stability and stabilization of a class of fractional-order nonlinear systems with Caputo derivative. On the basis of the stability theory of fractional-order linear differential equation, Mittag-Leffler function, Laplace transform, and the Gronwall inequality, two sufficient conditions are derived for the asymptotical stability of a class of fractional-order nonlinear systems with fractional-order α 0 < \alpha \leq 1 and 1 < \alpha < 2, respectively. Then, two sufficient conditions for asymptotical stabilization of such fractional-order systems are obtained, in which feedback gains could be ensured by the pole placement technique. Finally, some numerical examples are provided to show the validity and feasibility of the proposed method. © 2004-2012 IEEE.


Cao C.,Chongqing University | Cao C.,Chongqing Communication College | Hu C.,Chongqing University | Wang X.,Chongqing University | And 4 more authors.
Sensors and Actuators, B: Chemical | Year: 2011

Highly oriented TiO2 nanorod arrays were fabricated directly on fluorine-doped tin oxide-coated glass (FTO) substrate by the hydrothermal method. The diameter, length, and density of the nanorods could be varied by changing the growth parameters, such as time, temperature, and initial reactant concentration. The fabricated samples were characterized with X-ray diffraction, field-emission-scanning electron microscopy, transmission electron microscopy, high resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. The TiO2 nanorod array was applied to construct photoelectric devices, by which highly sensitive and steady photocurrent responses were obtained. © 2011 Elsevier B.V.


Cao C.,Chongqing University | Cao C.,Chongqing Communication College | Hu C.,Chongqing University | Shen W.,Chongqing Communication College | And 4 more authors.
Journal of Alloys and Compounds | Year: 2012

TiO 2/CdS core-shell nanorod arrays have been fabricated via a two-step method. Vertically aligned TiO 2 nanorod arrays (NRs) were synthesized by a facile hydrothermal method, and followed by depositing CdS nanoparticles on TiO 2 NRs by spin-coating successive ion layer adsorption and reaction (spin-SILAR) method. The surface morphology, structure, optical and photoelectrochemical behaviors of the core-shell NRs films are considered. The UV-vis absorption spectrum results suggested that the absorption peak of the TiO 2/CdS core-shell NRs shifts from the ultraviolet region to the visible region in comparison to that of the pure TiO 2 NRs. The obviously enhanced photoelectrochemical (PEC) performances of the heterojunction NRs were found under illumination of the simulated sunlight in comparison with that of the TiO 2 NRs. The enhanced PEC performance and formation mechanism of TiO 2/CdS core-shell NRs were discussed in detail. © 2012 Elsevier B.V.


Tian Y.,Chongqing University | Tian Y.,Chongqing Communication College | Hu C.,Chongqing University | Wu X.,Chongqing University | And 3 more authors.
Solar Energy Materials and Solar Cells | Year: 2012

Time stability of dye-sensitized solar cells based on ZnO sphere aggregates sensitized by N719 was systematically investigated. Eight cells in two groups were involved in this study. Each group has four cells that were connected in series and were used to supply the power to a light emission diode. Group 1 was kept in a room and Group 2 was kept outside ambient condition. The duration was half a year. The cells of the two groups can maintain about 90% of their initial efficiency after half a year running. The decrease of efficiency mainly results from about 15% drop of current density in the first week. Then the current density remained unvaried in the following days no matter whether the cells were kept in the room or outside ambient condition. The open-circuit voltages of these cells increased from 0.670.72 to 0.710.76 V in the first week and then kept unvaried in the following operation. These results indicate an excellent time stability of DSCs based on aggregates of ZnO spheres sensitized by N719 and suggest a great potential for practice use. © 2011 Elsevier B.V. All rights reserved.


Shengchun W.,Chongqing University | Shengchun W.,Chongqing Communication College | Zhaoxiang D.,Chongqing University | Weidong S.,Chongqing Communication College
Composite Structures | Year: 2010

A theoretical study on the sound transmission loss (STL) characteristics of unbounded orthotropic sandwich panels considering the transverse shear deformation is presented. With the transverse shear deformation taken into account, the governing equation of bending vibration for unbounded orthotropic sandwich panels is derived and implemented to the sound transmission problem. The expressions for impedance and transmission coefficient are also derived. The accuracy of the theoretical predictions is checked against available experimental data. The influence of several key parameters on the sound insulation properties of the orthotropic sandwich panel is then systematically studied, including shear rigidity of the core, face sheet thickness, and core thickness. Numerical analysis shows that shear rigidity has evident effect on coincidence critical frequency and STL property, and should not be neglected when predicting STL. Increasing face sheet thickness can move coincidence critical frequency to lower frequency region and improve STL, which is much more effective than increasing the core thickness. © 2010 Elsevier Ltd.


Song S.-H.,Chongqing University | Song S.-H.,Chongqing Communication College | Liao Q.,Chongqing University | Shen W.-D.,Chongqing Communication College
Applied Thermal Engineering | Year: 2013

It is novel and better method that microencapsulated phase change material (MPCM) slurry and the tube with twisted tape inserts are adopted together to enhance convective heat transfer. In this paper, numerical analyses were carried out to study laminar heat transfer and friction characteristics of MPCM slurry in a circular tube with twisted tape inserts. It is found that the MPCM slurry in the tube with twisted tape insert leads to the best performance of convective heat transfer for the bigger apparent specific heat and the intensive swirl flow. Furthermore, the modified average Nusselt number increases with decreasing bulk Stefan number, twisted ratio and increasing Re, while the friction factor increases with increasing Re and decreasing twisted ratio. It is also found that the heat transfer enhanced efficiency increases with increasing Re and decreasing Steb, and the heat transfer enhancement effects of twisted tape for low Steb slurry are better than that for high Ste b slurry. Moreover, the thermal-hydraulic performance ratios increase to a peak, then decrease gradually with increasing Re for different twist ratio. The performance ratio increases with decreasing the twist ratio only in a definite Re range, and the Re range decreases with decreasing twist ratio. © 2012 Elsevier Ltd. All rights reserved.


Cao C.,Chongqing University | Cao C.,Chongqing Communication College | Hu C.,Chongqing University | Shen W.,Chongqing Communication College | And 3 more authors.
Journal of Alloys and Compounds | Year: 2013

A novel heterostructure of Co3O4-modified TiO 2 nanorod arrays (NRs) is fabricated by a facile two-step solution-based method. First, TiO2 NRs grow on fluorine-doped tin oxide (FTO) conductive glass substrates by hydrothermal method. Afterward, Co3O4 nanoparticles were coated on the TiO2 NRs using a photochemical coating method. The samples were characterized by X-ray diffraction, field emission electron-scanning microscopy, transmission electron microscopic, X-ray photoelectron spectroscopy and UV-visible spectroscopy. For the first time, the photoelectrochemical (PEC) properties of the electrode made by the Co3O4-modified TiO2 NRs were investigated under visible-light irradiation. The results showed remarkably enhanced visible light PEC response of the Co3O4-modified TiO2 NRs in comparison with the pure TiO2 NRs, offering attractive perspectives for applications of the Co3O 4-modified TiO2 NRs in solar cells or photocatalysts. © 2012 Elsevier B.V. All rights reserved.

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