Zhang Y.,Chongqing University of Science and Technology
Research Journal of Applied Sciences, Engineering and Technology | Year: 2013
This study proposed a novel robust sliding mode control strategy for the stabilized platform of rotary steering drilling system. Firstly, a Nonlinear Disturbance Observer (NDO) which can converge exponentially with suitable design parameters is used to observe the uncertain disturbance of stabilized platform under work condition. Subsequently, sliding mode controller is designed to guarantee the robustness of the closed-loop system. The adaptive rate of switching gain is designed and sign function is replaced by bipolar sigmoid function to weaken chattering. Finally, Genetic Algorithm (GA) is applied to search the optimal controller parameters, including switching function coefficient, switching gain adaptive coefficient, sigmoid function coefficient and observer coefficient. Simulation results show that NDO can observe the uncertain disturbance effectively, controller output is decreased and stabilized platform can get optimal control performance and robustness. © Maxwell Scientific Organization, 2013.
Peng X.,Chongqing University of Science and Technology
2011 2nd International Conference on Mechanic Automation and Control Engineering, MACE 2011 - Proceedings | Year: 2011
Three sub-models of heat transfer across wall in network model of fire are analyzed. The software predictions with the three methods are compared with data of Japan one another by illustration. It shows that for three-node simple building, Both of half-infinite heat transfer sub-model and finite heat transfer sub-model agree well with the data of Japan, half-infinite heat transfer sub-model has a temperature deviation of less than 5% with finite heat transfer sub-model, While the method of heat insulation more than 40%. © 2011 IEEE.
Tang X.,Chongqing University of Science and Technology
Surface and Coatings Technology | Year: 2013
A simple strategy of combining in-situ reaction with microemulsion is used to prepare a crack-free TiO2 thin film with the nano-particles self-assembling into a mesoporous network. The particle shape and size are controlled by the reverse micelles in the microemulsion. In-situ growth of the TiO2 nano-particles prevents the film from cracking by reducing the build-up of capillary stress during the drying process. SEM images indicate that the in-situ TiO2 film is composed of interconnected nano-particles with a size of several tens of nanometers and does not crack macroscopically even when the film thickness is beyond 50μm. © 2013 Elsevier B.V.
Gu X.-H.,Chongqing University of Science and Technology
Tien Tzu Hsueh Pao/Acta Electronica Sinica | Year: 2013
This paper proposed a visual perception and edge preserving illumination invariant face recognition method, which on one hand employs a visual perception based image gradient to replace the image special gradient to make the method be more consistent with the human visual system, and on the other hand, proposes a novel diffusion equation to overcome the edge sharpening problem. The novel method can preserve the image edge and meanwhile can eliminate the halo effect and spot effect to some extent. Experimental results on EYaleB and CMU PIE databases show that the proposed method outperforms other compared methods, which illustrates the effectiveness of the proposed method.
Ren Z.,Chongqing University of Science and Technology
Mathematical Problems in Engineering | Year: 2014
We use variational level set method and transition region extraction techniques to achieve image segmentation task. The proposed scheme is done by two steps. We first develop a novel algorithm to extract transition region based on the morphological gradient. After this, we integrate the transition region into a variational level set framework and develop a novel geometric active contour model, which include an external energy based on transition region and fractional order edge indicator function. The external energy is used to drive the zero level set toward the desired image features, such as object boundaries. Due to this external energy, the proposed model allows for more flexible initialization. The fractional order edge indicator function is incorporated into the length regularization term to diminish the influence of noise. Moreover, internal energy is added into the proposed model to penalize the deviation of the level set function from a signed distance function. The results evolution of the level set function is the gradient flow that minimizes the overall energy functional. The proposed model has been applied to both synthetic and real images with promising results. © 2014 Zemin Ren.