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Wang J.,Nanjing University of Science and Technology | Li F.,Lanzhou Polytechnical College
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

In this paper, we address the problem of supporting applications with high bandwidth requirements in Wireless Mesh Networks (WMN) and develop a Markov analytic framework to study the important performance measures experienced by SUs in a cognitive radio (CR) based wireless mesh network. Specifically, we study the blocking and forced termination probabilities and throughput of secondary users under systems with/without spectrum handoff and channel reservation. Based on this framework, a novel dynamic cognitive channel access control algorithm for wireless mesh networks is proposed in order to maintain given quality of service (QoS) requirements. Simulation and analysis results show that our proposed dynamic cognitive channel access control algorithm can maximize the throughput while keeping forced termination and blocking probabilities of SUs' requests under the desired constraints, which providing a solution to improve load balance among multipath in wireless mesh networks. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE). Source


Ai W.-H.,Northwest University for Nationalities | Liu D.-W.,Lanzhou Polytechnical College | Wang S.-W.,Northwest University for Nationalities
Proceedings - International Conference on Artificial Intelligence and Computational Intelligence, AICI 2010 | Year: 2010

Digital image matting is to extract the foreground objects with arbitrary shapes from an image. This paper proposes optimal and developed algorithms for image matting in the efficiency and user interaction,without solving an optimization problem, but transforms the optimization problem into the minimum weighted distance issues based on dynamic programming. This method begins from segmenting regions by a user with two different colors to identify the foreground and background,and then the algorithm will be automatically propagated according to sampling points.Thus we can calculate the alpha channel of the overall image. This method is much faster than the existing approaches of comparable quality. © 2010 IEEE. Source


Tang L.,Lanzhou University of Technology | Tang L.,Lanzhou Polytechnical College | Huang J.,Lanzhou University of Technology | Xie L.,Lanzhou University of Technology
International Journal of Advanced Manufacturing Technology | Year: 2011

The influences of cutting parameters on temperature, stress, and shear angle during dry hard orthogonal cutting (DHOC) of D2 tool steel (62 ± 1 HRC) are investigated in this paper. Temperature and stress are considered the most important aspects to be taken into account in dry hard machining; however, dry hard machining is a complex process, and the temperature fields and residual stress are the most difficult to be measured. Up to now, only very few studies have been reported on influences of cutting parameters on shear angle, temperature, and stress of AISI D2 tool steel (62 ± 1 HRC). In this paper, the Johnson-Cook model is utilized to propose a finite element (FE) model. The FE model is properly calibrated by means of an iterative procedure based on the comparison between experimental resultant forces obtained from literatures and simulated resultant forces. At last, this FE model is utilized to predict the influences of cutting speed and depth of cut on temperature fields and residual stress within a workpiece, cutting tool edge temperature, and shear angle during DHOC hardened AISI D2 tool steel (62 ± 1 HRC) and validated by experimental results. As shown in this investigation, it is also possible to properly analyze the influences of cutting parameters on the cutting mechanism for industrial application. © 2010 Springer-Verlag London Limited. Source


Zhang L.,Lanzhou Polytechnical College | Luo D.,Lanzhou University of Technology | Kou S.,Lanzhou University of Technology
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2012

In order to research the plasticity of the Cu-based bulk amorphous and the influence of rare earth element on the mechanical properties of the amorphous, the Cu50-xZr42Al8Gdx (x=0, 2, 4) alloy rods with 3.0 mm in diameter were prepared by the suspend melting-copper mold suction casting. The structure and glass forming ability of the alloys were analyzed by X-ray diffraction (XRD) and differential scanning calorimetry (DSC), respectively. Subsequently, through the compression performance testing and the fracture morphology observation, the effect of rare earth element Gd on the mechanical performance and the fracture behavior of the samples were investigated. The results show that the structure of the rods is composed of amorphous phase. The samples possess larger thermal stability and good glass formation ability. With the increase of Gd content, the brittleness of the samples is enhanced gradually. Fracture mode presents brittle fracture. Source


Li B.,Lanzhou Polytechnical College
Advanced Materials Research | Year: 2011

A technique of cutting parameters optimization based on radial basis function neural networks and partical swarm optimization is presented in the paper. Taking experimental data as samples, the model between processing parameter and processing function was established based on radial basis function neural networks. Then, the cutting parameters is optimized by particle swarm optimization. With the combination of radial basis function neural network and particle swarm optimization, and making good use of the respective virtues, the model was solved. The experiment shows that the actual output as same as the predictive output and the mixes algorithm can realize optimization of cutting parameter real time in workplace. © (2011) Trans Tech Publications. Source

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