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2005年05月17日

【期刊论文】中西环境哲学的源流与发展

陈国谦, 赵锋, 涂又光, 叶文虎

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-1年11月30日

摘要

本文界定环境哲学的基本范畴框架,以“天人合一”和“主客恶性二分”分别概括中国和西方的传统环境形上学特征,分析环境哲学的源流及其在当代可持续发展要求下的学科建构。

环境哲学, 环境伦理学, 环境美学, 可持续发展

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2005年05月17日

【期刊论文】A NUMERICAL STUDY OF TURBULENT LINE PUFFS VIA THE RENORMALIZATION GROUP (RNG) K-∈MODEL

陈国谦, J.H.W.LEE a, *, AND G.Q. CHEN b

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-1年11月30日

摘要

The time evolution of a line puff, a turbulent non-buoyant element with significant momentum, is studied using the renormalization group (RNG) K-∈ model. The numerical results show that the puff motion is characterized by a vortex pair flow; the computed flow details and scalar mixing characteristies can be described by self-similar relations beyond a dimensionless time of around 30. The added mass coefficient of the puff motion is found to be approximately unity, The predicted puff flow and mixing rate are substantially similar to those obtained from the standard K-∈ model and are well supported by experimental data. The computed scalar field reveals significant significant secondary concentration peaks trailing behind in the wake fo the puff. The present results suggestthat the overall mixing rate of a puff is primarily detenmined by the large-scale motion and that stremline curvature probably plays a minor role.

Puffs and thermals, turbulence modelling, jets and plumes, environmental fluid mechanics, vortex flow added mass.,

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2005年05月17日

【期刊论文】A Perturbational h4 Exponential Finite Difference Scheme for the Convective Diffusion Equation

陈国谦, G.Q. CHEN AND Z.GAO, AND, Z.F. YANG

,-0001,():

-1年11月30日

摘要

A perturbational h4 compact exponential finite difference scheme with diagonally dominant coefficient matrix and upwind effect is developed for the convective diffusion equation. Perturbations of second order arerted on the convective coefficients and source term of an h2 exponential finite difference scheme proposed in this paper based on a transtormation to eliminate the upwind effect of the convective diffusion equation. Four numerical examples including one to three-dimensional model equations of fluid flow and a problem of natural convective heat transfer are given to illustrate the excellent behavior of the present exponential schemes. Besides, the h4 accuracy of the perturbational scheme is vernfied using double precision arithmetic.

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2005年05月17日

【期刊论文】Coupled Heat and Mass Transfer With One Discrete Sublimation Moving Interface and One Desorption Mushy Zone

陈国谦, Shi-Wen peng, Guo-Qian Chen

,-0001,():

-1年11月30日

摘要

Thepresent work discusses coupled heat and mass transfer during freeze-drying of a rigid product, as well as accelerated freeze-drying where sublimation and desorption occur concurrently. A desorption mushy zone model was developed to describe the desorption drying. An exaxt solution was obtained for coupled heat and mass transfer with one discrete sublimation moving interface and one desorption mushy zone where mass transfer is controlled by both Fick and Darcy laws. The effects of several parameters on the sublimation and desorption are analyzed and discussed.

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2005年05月17日

【期刊论文】Viewpoint Exergy analysis of energy utilization in the transportation sector in China

陈国谦, Xi Ji, G.Q. Chen*

,-0001,():

-1年11月30日

摘要

As an emerging approach for unified resource accounting and energy-utilization assessment for the transportation sector, the exergy method to embody the second law fo thermodynamics is investigated and applied to the energy-utilization assessment of the Chinese transport sector from 1978 to 2002. The exergy consumed by the sector in 2000 was 3.3 times that in 1978. The exergy of the oil consumed by transportation accounted for 30.5% of the total oil consumption in the whole country up to 2000, almost equal to the exergy of the net oil import. In terms of the exergy consumption intersity, taken as the exergy consumption per Converted Tumover, proposed to assess the overall effectiveness of the system, and conventional exergy efficiency to reflect the technical performance of involved transport vehicles, both the energy-utilization effectiveness and efficiency of the sector have been declining generally. Waterways transport was proved the most effective one, and railways, highways and clvil aviation were the second, third and fourth, respectively.The historical evolution and structural variation of energy use in terms of the total exergy consumption, exergy effciency and exergy consumption intensity are revealed and explored against drastic backgrud transitions in related policies and socioeconomies.

Energy, Transportation

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    北京大学,北京

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