Papers by Keyword: Nonlinear

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Authors: Ting Wu, Wen He Liao, Ning Dai
Abstract: In this paper biomechanical behavior of dental implant and surrounding bone system are investigated under static occlusal loads through 3D nonlinear finite element analysis (FEA), taking into account the interaction of implant-bone and implant-abutment contact interfaces. Stress-based performances of four commercially-available dental implant systems are evaluated in detail, demonstrating that implant and bone stability is strongly affected by implant-abutment connection structure as well as by a number of geometrical parameters. The results also indicate that platform-switching configuration can significantly reduce the crestal bone stress peaks, which contributes to the bone preservation for long-term success.
Authors: Shuang Xi Zhang, Wen Gai, Wei Hua Chu, Nian Liu
Abstract: In wind tunnel experiments, in order to adjust the attack angle continuously, the support mechanism movement should be steady and smooth. However, the electro-hydraulic servo system is a typical nonlinear, time-varying and uncertainty system, and the wind tunnel environment is very complicated. To address these problems, an on-line identification and generalized predictive control (GPC) strategy is proposed in this study. Firstly, the Labview and AMESim are integrated to build an electro-hydraulic system simulation model. Secondly, the controlled auto-regressive moving average (CARIMA) model of the electro-hydraulic system is developed. Thirdly, the influence on the system performance owing to the control parameters, model parameters, and external disturbance are widely discussed and deeply analyzed. At last, a test platform is constructed with the National Instruments (NI) embedded real time technology. The proposed control strategy is tested and verified on this test platform. The experimental results show that the angular velocity control precision reaches 0.01°/s. It implies that this control strategy has a good performance for nonlinear velocity control. Thus it satisfies the requirement of the continuously adjusting attack angle in wind tunnel experiments.
Authors: Chong Wen Cao, Gui Sheng Fan
Abstract: Based on test data of field soil water infiltration, Back-propagation (BP) model of predicting Kostiakov infiltration model parameters was established after analyzing the primary influence factors of water infiltration model parameters. The results indicate that BP model can reflect the non-linear relationship between the model parameters and the physical parameters of the soil; BP model is high accuracy for prediction soil infiltration model parameters. It can be referred as a new method to predict soil infiltration process using soil physical parameters.
Authors: Huai Ning Ruan, Man Lu Luo, Di Wang, J. W. Ju
Abstract: A failure criterion is proposed for complex rocks and soils. Their anisotropic and nonlinear behavior is analyzed theoretically and experimentally. The influence of the intermediate principal stress is taken into account. The nonhomogeneous strength and the effect of geological temperature are also discussed. Many classical failure criteria are special cases of the proposed condition. The criterion is applied in the analysis of the bedrock of Ankang Dam in China. The case study illustrates the potential of the proposed general model in engineering application.
Authors: Ming Xia Feng, Ren Chen, Qiang Li
Abstract: A Homotopic BI neural network model is developed by combining the homotopy theory and the BI neural network model, to improve the defects of the steepest gradient descent algorithm itself, such as low speed converging and liable to be trapped in local minimum. The end-point carbon content and temperature of molten steel in BOF smelting process is predicted by the proposed model and the original. Result shows that the precision of new model is improved significantly. The hit rates are increased by about 5% and 10%, and the forecasting residuals have decreased 16.31% and 8.67% than the conventional ones, respectively. Also, the calculation time of the new model is 10% shorter than BI model.
Authors: Feng Chi, Yu Zhu, Li Wei Wu
Abstract: This paper discusses the air spring of the lithography mechanic gravity compensation device and the working principle of pneumatic control structure, and introduces the related technical parameter design. Focus on the structure of vibration damping device design and classical control theory.
Authors: Fa Jia Li, Ru Peng Zhu, He Yun Bao, Xiao Zhen Li
Abstract: The (4+N) DOFs (degrees of freedom) nonlinear dynamic model of the planetary gear transmission system has been established which include the horizontal displacement, vertical displacement of sun gear, eccentricity error excitation of the sun gear and planetary gear, and gear backlash. The nonlinear dynamic equations was dealt with non-dimensional. Non-dimensional relative displacement of sun gear with planet gears and planet gears with internal gear were solved by using the method of numerical integration. Load sharing coefficients of every planet gear was got by dealt with the result of dynamic equations. The differences of non-dimensional relative displacement and load sharing coefficient were contrasted.
Authors: Xi Wang Wang, Xiao Yang Li, Xiao Guang Wang, Lin Lin Zhang
Abstract: Bolt load in a bolted connection directly influence the safety of a design in regard to both static and fatigue loading as well as in the prevention of separation in the connection. When the separating force is applied off the bolt center, although the materials for the bolted joint remain in the linear elastic range, the interface contact area between the clamped plates is sensitive to both the magnitude and the location of the separating force. This often causes nonlinear variation of the bolt load, the deformation etc. An analytical model is proposed to obtain the expression for the nonlinear bolt load under a separating service load. Finite element modeling is used for evaluating the accuracy of the proposed model.
Authors: Ying Hui Lu, Shui Lin Wang, Hao Jiang, Xiu Run Ge
Abstract: In geotechnical engineering, based on the theory of inverse analysis of displacement, the problem for identification of material parameters can be transformed into an optimization problem. Commonly, because of the non-linear relationship between the identified parameters and the displacement, the objective function bears the multimodal characteristic in the variable space. So to solve better the multimodal characteristic in the non-linear inverse analysis, a new global optimization algorithm, which integrates the dynamic descent algorithm and the modified BFGS (Brogden-Fletcher-Goldfrab-Shanno) algorithm, is proposed. Five typical multimodal functions in the variable space are tested to prove that the new proposed algorithm can quickly converge to the best point with few function evaluations. In the practical application, the new algorithm is employed to identify the Young’s modulus of four different materials. The results of the identification further show that the new proposed algorithm is a very highly efficient and robust one.
Authors: Ying Hui Lv, Xia Ting Feng, Jun Yan Liu
Abstract: It has gained some popularity that optimization methods are used for identification of material parameters, furthermore because of non-linear relationship between identified parameters and foregone information, mostly parameter identification problem must be expressed in terms of a global optimization problem. In order to solve successfully non-linear parameter identification problem, a new global optimization algorithm, which is based on the general dynamic canonical descent method, is proposed. The results in numerical experiments and engineering application both show that the proposed method will be robust one in the field of non-linear parameter identification.
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