Papers by Keyword: Physical Model

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Authors: Jie Tao Diao, Xiao Bo Tian
Abstract: Memristor is a kind of circuit element with nano scale, its appearance may radically change the traditional circuit. Recently, dopant drift model is a hot issue in research works connected to memristor. However, because of lack of transparency in the process of simulation, simulation method on dopant drift model of memristor needs to be strengthened. Dopant drift model was analyzed, circuit characteristics and relations between different circuit variables were studied. Based on those works above, a kind of numerical simulation method was designed to simulate and validate the memristor model. Simulation results show that the method designed accurately expresses conducting behaviour of memristor physical model, which provides a new feasible way for simulations of memristor model.
Authors: Jian Yi Yuan, Jian Hua Cheng, Chun Feng Wang, Ding Bang Zhang, Zhen Hua Wu
Abstract: In order to reveal the heat conduction direction on roadbed, a series of theoretical analysis and mathematical derivations are used. Through simplifying the frozen soil layer as an equivalent homogeneous frozen body, the physical model of heat conduction was founded. Also, applying the entropy change of the thermodynamics second law, the direction of the actual heat transfer was analyzed. Further more, the three-dimensional and two-dimensional differential equation of unsteady heat transfer in Cartesian model were obtained by using Fourier's Law and importing the micro unit. It has significant senses for deep research of roadbed tympanites.
Authors: Nai Chuan Guo, Shang Xu Wang, Hong Wei Guo
Abstract: In order to study the wavefield response of heterogeneous structure in seismic section, firstly, we have got the 2-D P-wave data for two kinds of heterogeneous structure in the physical model of a 3-D heterogeneous sand layer. Then, we choose several typical single shot seismic records and minimum offset gathers for wavefield analysis. Finally, we show two images generated by using reverse time migration (RTM) on the recording data. Experimental results indicate that, heterogeneous structure’s information is included in every single shot record; each heterogeneity forms a diffractor whose diffraction response, which affects the imaging of the interface between the heterogeneous region and the homogeneous region, is especially obvious in the minimum offset gathers; diffraction wave could be eliminated by RTM imaging, which could reflect the position of heterogeneous structure in reality; the differences of the wavefield response of the two kinds of heterogeneous structures are mainly reflected in the divergences of the events’ scale and power of the heterogeneities.
Authors: Xiao Ping Fan, Zhi Feng Meng, Jia Hua Zhou, Hong Xiang
Abstract: Major factors that influenced the breakage of starch bubbles during extrusion expansion such as the initial bubble radium, the initial cell wall thickness, the initial cell wall temperature, the initial cell wall moisture content, the stress strength constant of starch and the changes of failure stress of bubble wall, stress of bubble wall, bubble radium, cell wall thickness, pressure different with time were investigated and the critical breaking points for each operation parameters under certain conditions were determined. The results showed that the smaller the initial bubble radium, the higher the initial cell wall thickness, and within certain range, the lower the initial temperature, the lower the initial moisture content, and the higher the stress strength constant of starch, the lower the tendency the bubble broke.
Authors: Behzad Mohammadzadeh, Mahmoud Bina, Hooshang Hasounizadeh
Abstract: To protect downstream of hydraulic structures against erosion and degradation, must dipress water energy. one of the most comon methods to achive this purpose is constructing the stilling basin at the downstream of such structures. In stilling basin, the water energy dissipated by taking place of hydraulic jump. When a hydraulic jump occurs, the hydrodynamic and hydrostatic forces effect on the stilling basin floor slab. These forces include the force due to water weight and the up lift force affected the slab below which these forces are classified in hydrostatic. also the other force is hydrodynamic force due to pressure fluctions below the hydraulic jump. To keep the stilling basin stabillity from liffting up and destruction must the resistant forces be equal to destroyer forces. In this study after discution about the hydraulic jump and its resultant forces, a equation has been offerd to determine the thickness of stilling basin floor slab using buckingham theory andsoftware DATAFIT. Finaly the slab which evaluated by physical model, simulated using mathematical model(software ANSYS 10) and studied. The stress and strain diagrams were extracted. Results showed that physical and mathematical models were matched very good.
Authors: Kiyomoto Tsushima, Hideki Aoyama
Abstract: Reverse engineering systems are used to construct mathematical models of physical models such as clay model based on measurement data. In this study, we proposed a reverse engineering method which can construct high quality surface data automatically. This method consists of the following steps; The first globally and regionally smooths measured data based on the target shape by fitting quadric surface to measurement data. The second defines quadric surfaces and converts measurement points into 3D lattice points to obtain uniform measurement data density. As the positions of measurement data are converted from coordinate values into 3D lattice points, it is easier to find neighboring points and clarify neighboring relations between surfaces. The third acquires segment measurement data based on maximum curvatures and normals at each point. The last defines NURBS surfaces for each segment using the least square method to average positional errors. In order to validate the effectiveness of the proposed method, we developed a reverse engineering system and constructed mathematical models through basic experiments using clay car model measurement data.
Authors: Zhong Tang Wang, Guang Xia Qi, Fang Wang, Shi Hong Zhang
Abstract: ] Theoretical calculation formula of punch force during tube extrusion has been proposed by means of slab method. On the basis of theoretical and experimental study, it is found that theoretical results of extrusion force given by the calculating formula approached to that of the experiment, and the relative errors are less than 20%. It is also found that the extrusion force is closely related to deformation temperature, lubricant and the ratio of extrusion. The calculating formula of extrusion force is given by considering the factors which are the conical angle of die, and the friction coefficient between the deformation zone and the extrusion container, and the friction coefficient between the undeformed zone and the mandrel. Key Words: Tube, Extrusion, Force, Physical model
Authors: Jia Dong Tang, Yi Ping Lu, Xue Mei Sun, Wan Quan Zhang
Abstract: To analyze the effect of the installation angle on the performance of axial flow fan, single blade model and whole model was established, steady flow in the axial flow fan of the 7500KW air-cooled motor was simulated by software FLUENT. Volume flow rate and hydraulic efficiency of the fan with different installation angle under specific outlet pressures were analyzed, the effect of different turbulence model on the numerical simulation results was discussed, and the effect of the single blade model, the whole model and lengthened flow passage model on the numerical calculation results was compared. The results show that the fan volume flow rate and hydraulic efficiency is higher with the installation angle of 30°, the results simulated by standard k-ε model are close to the results simulated by k-ω-SST model, calculation results of these three methods have a good agreement with each other, and the result coincides well with experimental measured values.
Authors: Jian Yun He, Zhao Pen He
Abstract: The intensity distribution of a UV linear light source and a UV linear light with a parabolic cylinder reflector on work piece surface were simulated using OpenGL program based on VC++6.0. Physical models were established and relevant fundamental assumptions were given. The results of the simulation fitted the real situation quite well. It is feasible to adjust the parameters of UV-curing radiation system using the results of computer simulation.
Authors: Qiang Gao, Li Jun Ji, Run Min Hou, Ji Lin Chen
Abstract: Electro-hydraulic servo systems (EHSS) are widely used in many industrial applications, and to determine the control strategies to exhibit high robustness and high precision remains the focus of attention. In order to improve the control performance of EHSS, a novel control method, based on fractional PID (FPID) controller, is proposed and designed for the EHSS. The transfer function of EHSS is constructed using first-principle method. The feasibility and availability of the proposed controller are examined by numerical simulation. The control performances of fractional FPID are well assessed based on performance indexes, including response time, tracking accuracy and robustness. The results of the simulation verify that FPID controller is of excellent control performance, and is suitable for the control of EHSS.
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