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Meng C.,Xian University of Science and Technology | Zhu Y.,Polytechnic University of Mozambique | Ding S.,Xian University of Posts & Telecommunications
Chongqing Daxue Xuebao/Journal of Chongqing University | Year: 2015

Aiming at the problem that there are many switching delay and switching times in fuzzy control system, a fuzzy control based vertical handoff algorithm is proposed to solve the problem of handoff. The received signal strength is adopted to set up the threshold, and the ability of decision is improved. The network parameters and service type are set as decision factors, and analytic hierarchy process is combined with the parallel fuzzy control system to shorten decision time and select the best suitable network for users. The simulation result shows that the algorithm can reduce the time and frequency of handoff and enhance the performance of the system. Compared with the traditional handover algorithm, the algorithm considers comprehensive decision factors, and it not only takes the use of the environment and the cost of the user terminal into account, but effectively ensures the quality of service of the network. ©, 2015, Chongqing Medical University. All right reserved. Source

Xiao Y.-L.,Xian University of Posts & Telecommunications | Wang Y.-M.,Xidian University | Pang L.-J.,Xidian University | Tan S.-C.,Xidian University
Tongxin Xuebao/Journal on Communications | Year: 2014

To solve the existing problems caused by that the third version of WLAN authentication infrastructure (WAI) protocol was used to establish WLAN Mesh security association, a WLAN Mesh security association scheme based on an improved WAI protocol was proposed. The results of performance analysis of the scheme show that the scheme improves the performance of WLAN Mesh security association, especially decreases the overhead of the authentication server (AS). Then, on basis of this scheme, a WLAN Mesh security association scheme in trusted computing environment was put forward to meet the demand of trusted computing environment. Moreover, the two WLAN Mesh security association schemes were proved secure in the strand space model (SSM). Source

Qiao L.,Xian University of Posts and Telecommunications | Zhao D.,Xian University of Posts & Telecommunications | Li C.,Xian University of Posts and Telecommunications
Journal of Applied Optics | Year: 2016

In order to obtain the infrared/visible/low-level light images of targets, a multi-channel photoelectric system optical axis parallelism calibration device was proposed. This device could easily load multi-channel photoelectric detection system, it realized the adjustment for the optical axis parallism in the azimuth and pitch directions mainly through the waist-shaped hole of the backplane clearance and the pad under repair backplane, to meet the optical axis parallelism not more than 15″. The instrument is characterized by simply adjusting the optical system of optical axis parallelism for the first time, it is possible to achieve different detectors repeating interchangeable lenses, and the repeatable positioning accuracy is higher than 0.01 mm. In addtional, the instrument can be easily loaded on other light equipments, such as photoelectric rotary table, convenient for field experiments, which can satify the requirement for using. © 2016, Editorial Board, Journal of Applied Optics. All right reserved. Source

Wang Y.,Northwestern Polytechnical University | Wang Y.,Xian University of Posts & Telecommunications | Cai W.,Northwestern Polytechnical University
Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University | Year: 2016

Social networking is the most important medium for information spreading but incidents occur recently because of rumor spreading; so it is necessary to study how to reduce rumor spreading in social networking to a minimum. A rumor spreading model with forgetting mechanism considered is proposed in order to solve the problem of rumor spreading in social networking. In accordance with the forgetting rule of Ebbinghaus, we establish the model of exponential functional forgetting rate. The mean field equations of the model are established to describe the susceptible, the infected, know but not the infected, and the removed. The basic reproductive number is calculated and the spreading rules of the model are analyzed theoretically. We study the rules of four groups of throngs and analyze the influence of various parameters of forgetting function on rumor spreading. We compare the rumor spreading of exponential function forgetting rate and constant forgetting rate. The experiment results show that, the exponential forgetting rate can reflect the actual situation better: the forgetting rate has significant effect on the density of infected and removed, the greater the initial forgetting rate or forgetting speed, the weaker is the rumor spreading; compared with the case of constant forgetting rate, the exponential function forgetting rate is more in line with the actual situation of rumor spreading. The correctness of theoretical analysis is verified by simulation experiments and the control strategy of rumor is also proposed. The research results are helpful to understanding the behavior of rumor spreading and provide useful reference for the spreading process and the prediction of network public opinion. © 2016, Northwestern Polytechnical University. All right reserved. Source

Dong Q.,Xian University of Posts & Telecommunications | Hui Z.,Xian University of Posts & Telecommunications | Ruan C.,CAS Xian Institute of Optics and Precision Mechanic
Journal of Applied Optics | Year: 2016

An optical fiber displacement-vibration sensor using the incoherent light as a light source and the mirror as a reflective surface was analyzed. The analytic expressions of the optical fiber output power and the measurement distance were derived. The relationship between power ratio and measurement distance was detailedly investigated based on different optical fiber radii, different numerical apertures, different spacings and included angles between transmitting and receiving optical fibers. The results of numerical simulation show that the measurement precision and scope are affected by the optical fiber radius, the optical fiber numerical aperture, the distance and axis angle of both transmitting and receiving optical fibers. By analyzing the variation curves of distance and output power ratio, it is helpful to select the appropriate sensor according to the measurement target in practical engineering applications. Moreover, the measurement error was discussed. The results shows that the measuring range of distance is increased with the increasing of optic fiber included angle, while the error rate is reduced. The error rate is 1% for the included angle of 0.25°. © 2016, Editorial Board, Journal of Applied Optics. All right reserved. Source

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