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Properties of Phase Transition of Traffic Flow on Urban Expressway Systems with Ramps and Accessory Roads

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Communications in Theoretical Physics 2011年第11期56卷 945-951页

作者：梅超群刘业进 School of Statistics Capital University of Economics and Business School of Urban economics and Public Affair Capital University of Economics and Business

In this paper, we develop a cellular automaton model to describe the phase transition of traffic flow on urban expressway systems with on-off-ramps and accessory roads. The lane changing rules are given in detailed, the numerical results show that the main road and the accessory road both produce phase transitions. These phase transitions will omen be influenced by the number of lanes, lane changing, the ramp flow, the input flow rate, and the geometry structure.

关键词： traffic flow ramp phase transition

Finite Element Method Formulation in Polar Coordinates for Transient Heat Conduction Problems

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Journal of Thermal Science 2016年第2期25卷 188-194页

作者： Piotr Duda Institute of Thermal Power Engineering Faculty of Mechanical Engineering Cracow University of Technology Al.

The aim of this paper is the formulation of the finite element method in polar coordinates to solve transient heat conduction problems. It is hard to find in the literature a formulation of the finite element method(FEM) in polar or cylindrical coordinates for the solution of heat transfer problems. This document shows how to apply the most often used boundary conditions. The global equation system is solved by the Crank-Nicolson method. The proposed algorithm is verified in three numerical tests. In the first example, the obtained transient temperature distribution is compared with the temperature obtained from the presented analytical solution. In the second numerical example, the variable boundary condition is assumed. In the last numerical example the component with the shape different than cylindrical is used. All examples show that the introduction of the polar coordinate system gives better results than in the Cartesian coordinate system. The finite element method formulation in polar coordinates is valuable since it provides a higher accuracy of the calculations without compacting the mesh in cylindrical or similar to tubular components. The proposed method can be applied for circular elements such as boiler drums, outlet headers, flux tubes. This algorithm can be useful during the solution of inverse problems, which do not allow for high density grid. This method can calculate the temperature distribution in the bodies of different properties in the circumferential and the radial direction. The presented algorithm can be developed for other coordinate systems. The examples demonstrate a good accuracy and stability of the proposed method.

关键词： FEM polar coordinate system numerical methods transient heat conduction power boilers

Characteristic fractional step finite difference method for nonlinear section coupled system

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Applied Mathematics and Mechanics(English Edition) 2014年第10期35卷 1311-1330页

作者：袁益让李长峰孙同军刘允欣 Institute of Mathematics Shandong University School of economics Shandong University

For the section coupled system of multilayer dynamics of fluids in porous media, a parallel scheme modified by the characteristic finite difference fractional steps is proposed for a complete point set consisting of coarse and fine partitions. Some tech- niques, such as calculus of variations, energy method, twofold-quadratic interpolation of product type, multiplicative commutation law of difference operators, decomposition of high order difference operators, and prior estimates, are used in theoretical analysis. Optimal order estimates in 12 norm are derived to show accuracy of the second order approximation solutions. These methods have been used to simulate the problems of migration-accumulation of oil resources.

关键词： three-dimensional section coupled system complete nonlinear equation,characteristic fractional step convergence numerical simulation

Two Efficient Parameterized Boundaries for Vee's Asian Option Pricing PDE

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Acta Mathematicae Applicatae Sinica 2012年第4期28卷 643-652页

作者： Bai-min YU School of International Trade and economics University of International Business and Economics

In this paper, we derive two general parameterized boundaries of finite difference scheme for VeSe~＇s PDE which is used to price both fixed and floating strike Asian options. Using these two boundaries, we can deal with all kinds of situations, especially, some extreme cases, like overhigh volatility, very small volatility, etc, under which the Asian option is usually mispriced in many existing numerical methods. Numerical results show that our boundaries are pretty efficient.

关键词： Asian option Vecer's PDE finite difference parameterized boundaries sensitivity

Improve access to the EU market by identifying French consumer preference for fresh fruit from China

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Journal of Integrative Agriculture 2018年第6期17卷 1463-1474页

作者： WANG Er-peng Zhifeng Gao Yan Heng School of economics and Management Nanjing Tech University College of economics and Management Jilin Agricultural University Food and Resource economics Department University of Florida

Most previous studies have investigated country-of-origin effect for agricultural products from the economically developed country, but few have focused on the impact of country-of-origin on agricultural products from economically developing countries. Using a national online survey in France, we determine French consumers＇ perceptions and preferences for fresh fruit from China. Results of ordered logit models show that fresh fruit from China was perceived as low quality and unsafe. Respondents who care about country-of-origin were less likely to purchase fresh fruit from China, while those who care about brand were more likely to buy Chinese fresh fruit. Risk perception and quality perception both had a significant impact on the purchase of Chinese fresh fruit. Results of latent class models obtained with key consumer demographics show that heterogeneous preferences exist among different consumer groups. The results provide critical information to both China and other economically developing countries in their efforts to improve market penetration in economically developed countries.

关键词： country of origin perception consumer preference fresh fruit China

What determines irrigation efficiency when farmers face extreme weather events? A field survey of the major wheat producing regions in China

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Journal of Integrative Agriculture 2018年第8期17卷 1888-1899页

作者： SONG Chun-xiao Les Oxley MA Heng-yun College of economics and Management Henan Agricultural University Department of economics and Finance University of Waikato

Water availability is a major constraint on grain production in China, therefore, improving irrigation efficiency is particularly important when agriculture faces extreme weather events. This paper first calculates irrigation efficiency with a translog stochastic frontier production function and then investigates what happens when extreme weather events occur via a Tobit model. The estimated results reveal several important features of irrigation practices: i) irrigation efficiency is lower when extreme weather events occur; ii) large variations in irrigation efficiency occur across irrigation facilities; iii) the farm plots exhibit an extreme distribution across efficiency levels; and iv) water-saving techniques, technology adoption, and the maintenance of farmers’ economic resilience are major determinants of irrigation efficiency. Based on these results we propose the following recommendations: i) farmers should balance crop yield and water use; undertake relevant training programs and adopt water-saving techniques; ii) local governments and researchers should help farmers to find the optimal level of irrigation water use based on their own circumstances and provide better water-saving techniques and training programs rather than simply encouraging farmers to invest in irrigation facilities in the most extreme weather years; and iii) the income level of farm households should be increased so as to improve their resilience to natural disasters.

关键词： irrigation efficiency determinants irrigation facilities water-saving techniques extreme weather events

Development of quadrilateral spline thin plate elements using the B-net method

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Acta Mechanica Sinica 2013年第4期29卷 567-574页

作者： Juan Chen Chong-Jun Li School of Mathematics and Quantitative economics Dongbei University of Finance and Economics School of Mathematical Sciences Dalian University of Technology

The quadrilateral discrete Kirchhoff thin plate bending element DKQ is based on the isoparametric element Q8, however, the accuracy of the isoparametric quadrilateral elements will drop significantly due to mesh distortions. In a previous work, we constructed an 8-node quadrilateral spline element L8 using the triangular area coordinates and the B- net method, which can be insensitive to mesh distortions and possess the second order completeness in the Cartesian co- ordinates. In this paper, a thin plate spline element is devel- oped based on the spline element L8 and the refined tech- nique. Numerical examples show that the present element indeed possesses higher accuracy than the DKQ element for distorted meshes.

关键词： Spline finite element ~ Refined quadrilateral el-ement ~ Discrete Kirchhoff plate element ~ Triangular areacoordinates ~ B-net method

Two 8-node quadrilateral spline elements by B-net method

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Acta Mechanica Sinica 2012年第6期28卷 1620-1629页

作者： Juan Chen Chong-Jun Li School of Mathematics and Quantitative economics Dongbei University of Finance and Economics School of Mathematical Sciences Dalian University of Technology

Isoparametric quadrilateral elements are widely used in the finite element method, but the accuracy of the isoparametric quadrilateral elements will drop obviously deteriorate due to mesh distortions. Spline functions have some properties of simplicity and conformality. Two 8-node quadrilateral elements have been developed using the trian- gular area coordinates and the B-net method, which can ex- actly model the quadratic field for both convex and concave quadrangles. Some appropriate examples are employed to evaluate the performance of the proposed elements. The nu- merical results show that the two spline elements can obtain solutions which are highly accurate and insensitive to mesh distortions.

关键词： Spline finite element B-net method Quadri-lateral element - Bivariate spline interpolation The secondorder completeness

COOPERATIVE ADVERTISING AND PRICING MODELS IN A DYNAMIC MARKETING CHANNEL

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Journal of Systems Science and Systems Engineering 2014年第1期23卷 94-110页

作者： Mingyang ZHOU Jie LIN School of economics and Management Tongji University

This paper studies dynamic pricing and cooperative advertising strategies in a two-member channel of distribution. We propose differential game models that incorporate the carryover effects of advertising over time for both manufacturer and retailer. Two different models are studied. Firstly, we discussed a non-cooperative differential game which the manufacturer supports partially the cost of the promotion activities. Secondly, both channel members cooperatively determine their respective strategies. In these two cases, dynamic cooperative advertising and pricing strategies are characterized. Then numerical simulation method is applied to analyze the sensitivity of main model parameters and compare the main results of the two models. The simulation results show that the cooperative model achieves better coordination than the non-cooperative model with the following features： all channel members achieve higher advertising efforts and profit level in the cooperative case rather than in the non-cooperative case.

关键词： Supply chain differential games cooperative advertising pricing