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EXISTENCE OF GLOBAL SMOOTH SOLUTION FOR SCALAR CONSERVATION LAWS WITH DEGENERATE VISCOSITY IN 2-DIMENSIONAL SPACE

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Acta Mathematica Scientia 2007年第2期27卷 430-436页

作者：陈静徐学文 Laboratory of Nonlinear Analysis Department of Mathematics Central China Normal University

This article concerns the existence of global smooth solution for scalar conservation laws with degenerate viscosity in 2-dimensional space. The analysis is based on successive approximation and maximum principle.

关键词： Fourier transform successive approximation maximum principle

ASYMPTOTIC STABILITY OF RAREFACTION WAVE FOR HYPERBOLIC-ELLIPTIC COUPLED SYSTEM IN RADIATING GAS

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Acta Mathematica Scientia 2007年第2期27卷 347-360页

作者：阮立志张晶 Laboratory of Nonlinear Analysis Department of Mathematics Central China Normal University

In this article, authors study the Cauch problem for a model of hyperbolic-elliptic coupled system derived from the one-dimensional system of the rudiating gas. By considering the initial data as a small disturbances of rarefaction wave of inviscid Burgers equation, the global existence of the solution to the corresponding Cauchy problem and asymptotic stability of rarefaction wave is proved. The analysis is based on a priori estimates and L^2-energy method.

关键词： Hyperbolic-elliptic coupled system rarefaction wave asymptotic stability L^2-energy method

Migration of Infiltrated NH_4 and NO_3 in a Soil and Groundwater System Simulated by a Soil Tank

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Pedosphere 2008年第5期18卷 628-637页

作者： WANG Chao WANG Pei-Fang State key Laboratory of Hydrology- Water Resources and Hydraulic Engineering Key Laboratory of Integrated Regulationand Resource Department on Shallow Lakes Ministry of Education Environmental Science and Engineering CollegeHohai University Nanjing 210098 （China）.

The infiltration of water contaminants into soil and groundwater systems can greatly affect the quality of groundwater. A laboratory-designed large soil tank with periodic and continuous infiltration models, respectively, was used to simulate the migration of the contaminants NH4 and NO3 in a soil and groundwater system, including unsaturated and saturated zones. The unsaturated soil zone had a significant effect on removing NH4 and NO3 infiltrated from the surface water. The patterns of breakthrough curves of NH4 and NO3 in the unsaturated zone were related to the infiltration time. A short infiltration time resulted in a single sharp peak in the breakthrough curve, while a long infiltration time led to a plateau curve. When NH4 and NO3 migrated from the unsaturated zone to the saturated zone, an interracial retardation was formed, resulting in an increased contaminant concentration on the interface. Under the influence of horizontal groundwater movement, the infiltrated contaminants formed a contamination-prone area downstream. As the contaminants migrated downstream, their concentrations were significantly reduced. Under the same infiltration concentration, the concentration of NO3 was greater than that of NH4 at every corresponding cross-section in the soil and groundwater tank, suggesting that the removal efficiency of NH4 was greater than that of NO3 in the soil and groundwater system.

关键词： breakthrough curve migration NH4 NO3 soil tank experiment

Synthesis of TiC Powder by Mechanical Alloying of Titanium and Asphalt

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chinese Journal of Chemical Engineering 2007年第1期15卷 138-140页

作者：李渤崔立山郑雁军徐春明 State key Laboratory of Heavy Oil Processing China University of Petroleum Beijing 102249 China Department of Materials Science and Engineering China University of Petroleum Beijing 102249 China

Abstract TiC powder was synthesized by mechanical alloying of titanium and asphalt in this paper. Deoiled asphalt as a carbon source not only provided element C in the fabrication of TiC but also cracked itself by the mechanical alloying process. The results of X-ray diffraction demonstrated the synthesis of cubic TiC. Gas phase chromatography showed that the discharged gas was composed of low molecular weight hydrocarbons, including H2, CH4 and C2H6. The formation mechanism of titanium carbide by mechanical alloying, and the thermodynamic and kinetics were discussed. These results showed that mechanical alloying is a promising method to prepare TiC and to crack asphalt with some light fraction byproducts.

关键词： asphalt titanium carbide mechanical alloying

Monitoring bioaccumulation and toxic effects of hexachlorobenzene using the polyurethane foam unit method in the microbial communities of the Fuhe River,Wuhan

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Journal of Environmental Sciences 2007年第6期19卷 738-744页

作者： LIU Ting CHEN Zhu-lei SHEN Yun-fen GAN Lu CAO Li LV Zi-zhong Environmental Science Research Institute Huazhong University of Science and Technology Wuhan 430074 China The Laboratory of Protozoan Taxonomy and Ecology Institute of Hydrobiology Chinese Academy of Sciences Wuhan 430072 China

Hexachlorobenzene （HCB） is a chlorinated aromatic hydrocarbon that was widely used for seed dressing in prevention of fungal growth on crops, and also as a component of fireworks, ammunition, and synthetic rubbers. Because of its resistance to degradation and mobility, HCB is widely distributed throughout the environment and is accumulated through food chains in different ecosystems. In this study, a preliminary investigation was carried out on the bioaccumulation and the toxic effects of HCB in the microbial （protozoan in particular） communities in the Fuhe River, Wuhan, a water body receiving industrial wastewaters containing HCB and other pollutants, using the standardized polyurethane foam units （PFU） method. Field samples were taken from eight stations established along the Fuhe River in January and August 2006. The concentration ratios of HCB in microbial communities and in water were 9.66-18.64, and the microbial communities accumulated 13.29-56.88 μg/L of HCB in January and 0.82-10.25 μg/L HCB in August. Correlation analysis showed a negative correlation between the HCB contents in the microbial assemblage, and the number of species and the diversity index of the protozoan communities. This study demonstrated the applicability of the PFU method in monitoring the effects of HCB on the level of microbial communities.

关键词： bioaccumulation toxicity effect hexachlorobenzene PFU method microbial community protozoan communities

An Experimental Study on Flow Patterns and Width Adjustment in Self-formed Channels

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四川大学学报(工程科学版) 2005年第S1期37卷 106-111页

作者： LFU Xingnian YANG Kejun CAO Shuyou SHI Bing State key Lab.of Hydraulics and Mountain River Eng. Sichuan Univ.Chengdu 610065China School of Civil Eng. Ocean Univ.of ChinaQingdao 266071China

The distribution of velocity is one of the basic issues in river *** on the experimental data measured by ADV in the flume of State key Hydraulics Laboratory (SKHL),this paper analyzed the ver- tical distribution of point velocity and the varying law of turbulence intensity in straight mobile compound chan- nel with an asymmetric *** certain relative height,the streamwise point velocity follows the loga- rithmic *** the location,the velocity varies linearly approxim...

关键词： compound channels velocity turbulence intensity width adjustment mobile bed

AN EQUIVALENT CONTINUUM METHOD OF LATTICE STRUCTURES

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Acta Mechanica Solida Sinica 2006年第2期19卷 103-113页

作者： Fan Hualin Yang Wei Department of Engineering Mechanics Tsinghua University Beijing 100084 China

An equivalent continuum method is developed to analyze the effective stiffness of three-dimensional stretching dominated lattice materials. The strength and three-dimensional plastic yield surfaces are calculated for the equivalent continuum. A yielding model is formulated and compared with the results of other models. The bedding-in effect is considered to include the compliance of the lattice joints. The predicted stiffness and strength are in good agreement with the experimental data, validating the present model in the prediction of the mechanical properties of stretching dominated lattice structures.

关键词： stretching dominated lattice materials equivalent continuum method effective stiffness yield surface bedding-in effect

Application of Stereology on Neodymium-Doped Yttrium Aluminum Garnet (Nd∶YAG) Transparent Ceramics

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Journal of Rare Earths 2006年第5期24卷 538-542页

作者：张华山荆敏苏春辉张洪波候朝霞邵晶宋琼 School of Materials and Chemical Engineering Changchun University of Science and Technology chinese Special Vehicle Institute

Nd ： YAG precursor powders were synthesized by homogeneous precipitation, and Nd ： YAG transparent ceramics were prepared by vacuum sintering at 1700 ℃ for 5 h. The ceramic materials were characterized by light transmittance and field emission gun-environment scanning microscope. Using statistics and stereology theory, study was carried out on the quantitative relationships between light transmittance and stereological parameters in three-dimensional Euclidean space. It is found that the transmittance of Nd：YAG with 1 mm in thickness is about 45% and 58% in visible and near-infrared wavelength, respectively. The transmittance linearly increases with increasing equivalent sphere diameter and reaches the theoretical value of single crystal when the equivalent sphere diameter is 20μm. The transmittance decreases with the increasing of mean specific area per unit volume of grain and discrete grains, and the transmittance decreases with increasing mean free distance of grains in Nd：YAG ceramics.

关键词： neodymium doped yttrium aluminum garnet transparent ceramics stereology microstructure rare earths

The energy release rate for hygrothermal coupling elastic materials

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Acta Mechanica Sinica 2006年第1期22卷 28-33页

作者： Fan Yang Jun Wang Dapeng Chen Institute of Computational Engineering and Science Southwest Jiaotong UniversityChengdu 610031 China Department of Material Science Fudan UniversityShanjzhai 200433. China

In the fracture problems of hydrophilic elastic materials under coupling effects of heat conduction, moisture diffusion and mechanical deformation, the conventional J-integral is no longer path independent. The value of J is unequal to the energy release rate in hygrothermal coupling cases. In the present paper, we derived a general form of the energy release rate for hygrothermal fracture problems of the hydrophilic elastic materials on the basis of energy balance equation in cracked areas. By introducing the constitutive relations and the essential equations of irreversible thermodynamics, a specific expression of the energy release rate was obtained, and the expression can be reformmulated as path independent integrals, which is equivalent to the energy release rate of the fracture body. The path independence of the integrals is then verified numerically.

关键词： Fracture Energy release rate J-integral Hygrothermal coupling problems