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REGULARITY OF sOLUTIONs TO THE DIRICHLET PROBLEM FOR DEGENERATE ELLIPTIC EQUATION

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Chinese Annals of Mathematics,series B 2003年第4期24卷 529-540页

作者： CHEN YEMIN school of Mathematics, peking university, beijing 100871, china. school of Mathematics Peking University Beijing 100871 China

In this paper, the author studies the regularity of solutions to the Dirichlet problem forequation Lu = f, where L is a second order degenerate elliptic operator in divergence form inΩ, a bounded open subset of Rn (n... 详细信息

关键词： Regularity Dirichlet problem Degenerate Weighted spaces

Hausdorff dimension of Julia set of a polynomial with a siegel disk

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science china Mathematics 2006年第9期49卷 1284-1296页

作者： sHEN Liang LMAM, school of Mathematical sciences, peking university, beijing 100871, china LMAM School of Mathematical Sciences Peking University Beijing China

Let f(z) = e2πiθz(1+z/d)d,θ∈R\Q be a polynomial. Ifθis an irrational number of bounded type, it is easy to see that f(z) has a siegel disk centered at 0. In this paper, we will show that the Hausdorff dimension o... 详细信息

关键词： Hausdorff dimension siegel disk porous set

china's energy, environment and policy perspective

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Journal of environmental sciences 2000年第3期12卷 270-274页

作者： ZHANG shi\|qiu (Center for environmental sciences, peking university, beijing 100871, china) Center for environmental sciences Peking University Beijing 100871 China

This paper discusses the specific features of the energy in china, and addresses those key challenges in china is that the co\|exist of (1) higher total energy production and lower per capita level; (2) lower per capita energy resources level with unrational energy consumption structure; (3) lower energy utilization efficiency and higher energy conservation potential; and (4) unequal distribution of energy resources. It reviews the key environmental problems related to the feature of energy production and consumption. Based on the analysis, the author furthers addresses the policy and actions needed.

关键词： energy energy production energy consumption environment policy

A new Early Cretaceous lizard with well-preserved scale impressions from western Liaoning, china

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Progress in Natural science:Materials International 2005年第2期15卷 67-73页

作者： JI shu’an*(school of Earth and space sciences, peking university, beijing 100871, china) sch. of Earth and space sci. Peking Univ. Beijing 100871 China

A new small lizard, Liaoningolacerta brevirostra gen. et sp. nov., from the Early Cretaceous Yixian Formation of western Liaoning is described in detail. The new specimen was preserved not only by the skeleton, but also by the exceptionally clear scale impressions. This lizard can be included within the taxon scleroglossa based on its 26 or more presacrals, cruciform interclavicle with a large anterior process, moderately elongated pubis, and slightly notched distal end of tibia. The scales vary evidently in size and shape at different parts of body: small and rhomboid ventral scales, tiny and round limb scales, and large and longitudinally rectangular caudal scales that constitute the caudal whorls. This new finding provides us with more information on the lepidosis of the Mesozoic lizards.

关键词： new genus squamata skeleton lepidosis Early Cretaceous western Liaoning

On Riemann-Finsler geometry

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Chinese science Bulletin 1998年第6期43卷 447-450页

作者： MO Xiaohuan school of Mathematical sciences, peking university, beijing 100871, china school of Mathematical sciences Peking University Beijing China

The history of Finsler geometry is reviewed and briefly recent development in Finsler geometry and its application is completed systematically. Furthermore, an interesting open problem has been proposed in this field.

关键词： Finsler space Chern connection Hilbert form Minkowski potential projective sphere bundle.

Kinetic characteristics of continuous flow polymerase chain reaction chip: A numerical investigation

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science china(Technological sciences) 2010年第7期53卷 1967-1972页

作者： WANG shiYing1 & WANG Wei2,3 1 school of Physics, peking university, beijing 100871, china 2 Institute of Microelectronics, peking university, beijing 100871, china 3 National Key Laboratory of science and Technology on Micro/Nano Fabrication, beijing 100871, china school of Physics Peking University Beijing China Institute of Microelectronics Peking University Beijing China National Key Laboratory of science and Technology on Micro/Nano Fabrication Beijing China

Continuous flow PCR (polymerase chain reaction) chip holds impressive advantages compared to micro chamber PCR chip. In order to have better understanding of kinetic characteristics of continuous flow PCR chip, a comprehensive mathematical model is presented in this paper, including melting, annealing and extension phases of a typical PCR process which has the essence of a convection-diffusion-reaction system. Using this model, we can simulate the PCR process in series of reaction cycles. Numerical results show that the average sample velocity plays a significant role in affecting the amplification efficiency. Also, appropriate combination of the PCR mixture is important for high-quality DNA amplification. Giving a large initial DNA concentration range, the continuous flow PCR scheme holds excellent real-time detection ability theoretically. The present numerical model bridges the temperature distribution to the real DNA amplification, and thereby is able to successfully predict continuous flow PCR properties which are important for the chip design.

关键词： continuous flow PCR chip numerical simulation convection-diffusion-reaction system

study on urban water environmental support capacity

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Journal of environmental sciences 1995年第4期7卷 430-434页

作者： Guo Huaicheng Ye Wenhu(Center of environmental sciences , peking university , beijing 100871 , china) Ctr of Envmtl sciences Peking Univ Beijing China China

ＳｔｕｄｙｏｎｕｒｂａｎｗａｔｅｒｅｎｖｉｒｏｎｍｅｎｔａｌｓｕｐｐｏｒｔｃａｐａｃｉｔｙＧｕｏＨｕａｉｃｈｅｎｇ；ＹｅＷｅｎｈｕ（ＣｅｎｔｅｒｏｆＥｎｖｉｒｏｎｍｅｎｔａｌＳｃｉｅｎｃｅｓ，ＰｅｋｉｎｇＵｎｉｖｅｒ... 详细信息

ＳｔｕｄｙｏｎｕｒｂａｎｗａｔｅｒｅｎｖｉｒｏｎｍｅｎｔａｌｓｕｐｐｏｒｔｃａｐａｃｉｔｙＧｕｏＨｕａｉｃｈｅｎｇ；ＹｅＷｅｎｈｕ（ＣｅｎｔｅｒｏｆＥｎｖｉｒｏｎｍｅｎｔａｌＳｃｉｅｎｃｅｓ，ＰｅｋｉｎｇＵｎｉｖｅｒｓｉｔｙ，Ｂｅｉｊｉｎｇ１００８７...

关键词： water environmental support capacity urban water environment development variablesi supportvariables.

Abrupt climate change and collapse of ancient civilizations at 2200BC-2000BC

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Progress in Natural science:Materials International 2005年第10期15卷 46-52页

作者： WANG shaowu (Department of Atmospheric science, school of Physics, peking university, beijing 100871, china) Department of Atmospheric science School of Physics Peking University Beijing 100871 China

Plentiful evidence of historical, archaeological and palaeoclimatic studies proved that an abrupt change from wetter to drier climate occurred over the Nile Valley,the Mesopotamia, the Indus Valley and Huanghe River Valley at 2200BC-2000BC. The abrupt change was developed based on the general lowering of temperature in the middle latitudes, and was a strong cold event since the beginning of the Megathermal (8.5-3.0 kaBP). Collapse of Nile civilization appeared at the First Intermediate Period (2181BC-2040BC). Civilization of Mesopotamia began collapse following the disintegration of Akkadian Empire. This process lasted to the foundation of Babylon Kingdom from 2200BC to 1900BC. Indus civilization abruptly fell off at 1800BC. A widespread alternation of archaeological cultures happened in china at ca. 2000BC except only in its central part. Longsheng culture was replaced by the Erlitou culture, which is now acknowledged in china as Xia Culture. Foundation of Xia Dynasty at 2070BC opened a new chapter in the development of Chinese civilization. studies indicated that abrupt climate change may be caused by the weakening of the Thermohaline Circulation (THC).

关键词： 2200BC-2000BC abrupt climate change collapse of ancient civilization.

Marginal cost pricing for coal fired electricity in coastal cities of china:The case of Mawan Electricity Plant in shenzhen City, china

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Journal of environmental sciences 2003年第3期15卷 401-412页

作者： ZHANG shi-qiu, DUAN Yan-xin (Center for environmental sciences, peking university, beijing 100871, china.) Center for environmental sciences Peking University 北京 100871

By developing a GDMOD model to estimate the environmental externalities associated with electricity generation, this project provides a detailed analysis of the damages and costs caused by different pollutants at varying distances from the Mawan Electricity Plant in shenzhen, china. The major findings of this study can be summarized that (1) environmental damages caused by electricity production are large and are mainly imposed on regions far away from the electricity plant; (2) air pollution is the most significant contributor to the total damages, and sO_2, NOx, and particulate matter are the three major pollutants with highest damages; (3) the damages caused per unit of particulate, NOx, and sO_2 emissions are much higher than pollution treatment and prevention costs. The research results of this project showed that china needs to have a more effective levy system on sO_2, and a more manageable electricity tariff mechanism to internalize the environmental externalities. The results have also implications for pollution control strategies, compensation schemes as well as emission trading arrangements.

关键词： marginal cost pricing environmental damages environmental policy