Papers by Keyword: Numerical Method

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Authors: Ulrich Groh, Meinhard Kuna
Authors: Yiming Li
Abstract: Quantum correction model features the correction of the inversion layer charge on different classical transport models in semiconductor device simulation. This approach has successfully been of great interest in the recent years. Considering a metal-oxide-semiconductor (MOS) structure in this paper, the Hänsch, the modified local density approximation (MLDA), the density-gradient (DG), the effective potential (EP), and our models are investigated computationally and compared systematically with the result of the Schrödinger-Poisson (SP) model. In terms of the accuracy for (1) the position of the charge concentration peak, (2) the maximum of the charge concentration, (3)the total inversion charge sheet density, and (4) the average inversion charge depth, these well-established models are examined simultaneously. The DG model requires the solution of a boundary value problem, the EP model overestimates the position of the charge concentration peak and the maximum of the charge concentration, our explicit model demonstrates good accuracy among models.
Authors: Jian Xiao Zou, Cui Yun Zhou, Gang Zheng
Abstract: A new variable step-size numerical algorithm for implicit integration is discussed in this paper. The scheme for increase and decrease of step size is discussed according to the difference of output variable value. The next step size is calculated through the variable coefficient method and the limitation rules. The convergence and accuracy are testified by the simulation result. Compared with the common used ode45 algorithm, the algorithm has more computing efficiency with a certain calculation precision.
Authors: Jun Huang, Yong Jun Li, Fan Huang
Abstract: A numerical method is proposed for calculating the fractional order derivative and successfully resolving the integrand singularity problem based on Zhang-Shimizu algorithm. And then a method is developed to calculate the twice nonlinear fractional derivative, numerical examples demonstrate the numerical method with high precision and good stability.
Authors: Xin Zhu Zhou, Jian Jun Zheng
Abstract: Practical experience and observations suggest that corrosion affected reinforced concrete (RC) structures are more prone to cracking than other forms of structural deterioration. Concrete cracking incurs considerable costs of repairs and inconvenience to the public due to interruptions. This gives rise to the need for prediction of the time to surface cracking of concrete in order to achieve cost-effectiveness in maintaining the serviceability of RC structures. The intention of this paper is to develop a numerical method for predicting the time to surface cracking of corrosion affected RC structures. In this method, concrete with embedded reinforcing steel bars is modeled as a thick-wall cylinder. With an exponential curve modeling the energy dissipation process in concrete, the element transfer matrix is derived analytically. The time to surface cracking is then determined by solving the nonlinear problem numerically. Finally, the validity of this numerical method is verified by comparing with experimental results collected from the research literature.
Authors: Sen Lin Lu, Yu Feng Gu, Shian Chen, Sheng Wang
Abstract: The object is to propose an accurate and succinct numerical method to compute the electromagnetic force between the electromagnetic track brake and track. The model of the magnetic circuit with variable air-gap permeance is established and the electromagnetic force is obtained by using a method of magnetic flux tubes. The electromagnetic force is compared with that from the finite element method using Ansoft software. The comparison results show that the numerical method is capable of achieving precise and reliable electromagnetic force quickly.
Authors: Tian Jie Cao
Abstract: In this paper a general numerical method to analyze some simple planar frames subjected to concentrated loads with elastic large deflection is presented. In the method some reactions or displacements at the ends of the frames with three or below redundant constraints are considered as unknown, and a numerical method based on a more-fold method of bisection is presented to solve for the unknown reactions or displacments under known boundary conditions. In the examples in the paper,the flow graphs of solving for unknown reactions or displacements are demonstrated and some analysical results are given by the aid of some graphics.These examples show that some simple frame structures with three or below redundant constraints can all be analyzed easily and quickly with the numerical method presented in the paper.
Authors: Michele Buonsanti, Giovanni Leonardi, Francesco Scoppelliti
Abstract: The particles distinct element model has the consistency to model the mechanical behavior of the microscopic structures inside an asphalt mixture. The model assumes that the schematized granular constituents are in a contact point, considering the thin asphalt films as the binding elements. In this paper, we will model (at micro-scale) the damage to a surface in asphalt concrete under an impulsive load, considering binding, interface, viscosity and friction. Our aim is to reproduce the micro-damage due to detachment among the elementary components of the concrete in airports pavements.The proposed approach is mainly from a mechanical point of view, and a general model describing adhesive contact between rigid bodies is proposed. The intensity of adhesion is supposed to decrease under prescribed shear and normal displacement fields and comes by energy reduction, where the viscosity and friction contributes are taken in account.A numerical implementation by finite element procedures has been performed, and the outcome is presented.
Authors: Xiao Li Liu, Jun Jie Yang
Abstract: For numerical simulation, the shear strength reduction technique (SSRT) is often used to evaluate slope or landslide stability. According to numerical computation results of slopes or landslides analyzed by SSRT, it can be found that with increase of the shear strength reduction factor, some of the soil elements will yield gradually to form a connected plastic zone, which is the potential slip surface of the slope or landslide. In view of the plastic resistance of soils, formation of the connected plastic zone does not always indicate that the landslide is about to failure. Other auxiliary criterion is necessary to predict whether a slope or landslide is in a critical state or not. Here, difference of the incremental percent of horizontal displacement of the outcropping slip surface node is regarded as the auxiliary indicator to distinguish the critical state of slopes or landslides after formation of the potential slip surface. With the ideas mentioned above, stability of a fossil landslide, Xietan landslide has been analyzed for the natural and the long-term reservoir water level conditions. Factors of safety of Xietan landslide by the numerical method have been compared with that by the limit equilibrium method, which indicates that the method used here for evaluating stability of Xietan landslide is feasible. Because numerical method has more advantages over the limit equilibrium method, the approach for evaluating stability of landslide here can be applied to more complicated or three-dimensional landslides or slopes further.
Authors: Jin Shi Liu, De Jiang Shang, Hao Song
Abstract: To predict the sound radiation of structures, both a structural problem and an acoustic problem have to be solved. In case of thin structures and dense fluids, a strong coupling scheme between the two problems is essential, since the feedback of the acoustic pressure onto the structure is not negligible. A popular idea for solving this class of problems is to discretizing the structural domain with the finite element (FE) method and with boundary element (BE) method on the acoustic field. A wide range of researches has been carried on the coupling the FE and BE methods. For fast prediction of sound radiation characteristic of similar structures, a coupled solver in frequency domain is presented in this essay. Numerical experiments showed acceleration on noise optimization problems of underwater structures with different materials.
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