Simulation of leachate migration in leaky aquifers

A two-dimensional cross-section finite difference model is presented to simulate density dependent leachate migration in leaky aquifers. Unlike existing models, a new approach is adopted to couple the groundwater-flow equation and the hydrodynamic dispersion equation with the elimination of the intermediate step of calculating velocities. The concept of the reference density is employed, permitting increased accuracy (over pressure-based models) in the representation of the transport process. The model is then used to study the effect of several hydraulic and transport parameters on the flow pattern and plume migration which are found to be very sensitive to most of these parameters. Equiconcentration and equipotential lines are overlapped to provide a better understanding of the coupling effect.     

NUMERICAL SIMULATION OF STREAMBED HEAT TRANSFER

１．　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｓｉｍｕｌａｔｉｏｎｏｆｓｔｒｅａｍｗａｔｅｒｔｅｍｐｅｒａｔｕｒｅｉｓｓｉｇｎｉｆｉｃａｎｔｌｙｉｍｐｏｒｔａｎｔｆｏｒｔｈｅｓｔｕｄｙｏｆｎｕｍｅｒｉｃａｌｍｏｄｅｌｉｎｇｏｆｒｉｖｅｒｉｃｅｐｒｏｃｅｓｓｅｓ［１］　．Ｈｉｓｔｏｒｉｃａｌｌｙ，ｔｈｅｍａｔｈｅｍａｔｉｃａｌｍｏｄｅｌｉｎｇｏｆｔｈｅｔｒａｎｓｐｏｒｔａｎｄｆａｔｅｏｆｈｅａｔｉｎａｗａｔｅｒｂｏｄｙｈａｓｂｅｅｎｔｈｅｓｕｂｊｅｃｔｏｆｅｘｔｅｎｓｉｖｅｓｔｕｄｙｆｏｒｖａｒｉｏｕｓｒｅ…     

利用短周期地脉动推断深层地基S波速度

从二维随机波场的相关理论出发，提出了如何从短周期地脉动（频率＞０．５Ｈｚ）时域信号中计算Ｒａｙｌｅｉｇｈ波弥散曲线，进而反演深层地基剪切波（Ｓ波）速度的理论方法和分析技术，并结合实测信号的分析结果，探讨了该方法的可行性和实用性。     

偏振模色散统计特性的研究

利用动态方程研究了偏振模色散矢量的统计特性 ,分别用统计系综和频率系综两种方法进行数值模拟。数值结果表明 ,统计系综和频率系综两种方法的结果一致。在大归一化距离条件下 ,均方根时延的平方随归一化距离线性变化 ;偏振模色散矢量的各个分量服从高斯分布 ,差分群时延服从麦克斯韦分布 ;偏振模色散矢量弥散于整个邦加球     

Theoretical Discussion of Couple-Mode Using Chirped Fiber Grating for Dispersion Compensation

１ＩｎｔｒｏｄｕｃｔｉｏｎＡｔｐｒｅｓｅｎｔ，ａｓｔｈｅｅｒｂｉｕｍｄｏｐｅｄａｍｐｌｉｆｉｅｒｓｈａｖｅｓｕｃｅｓｆｕｌｙｂｅｅｎａｐｐｌｉｅｄｔｏｏｐｔｉｃａｌｆｉｂｅｒｌｉｎｋｓ，ｔｈｅｌｏｎｇｈａｕｌｈｉｇｈｂｉｔｒａｔｅｏｆｏｐｔｉｃ...     

Kerr型介质界面上弱非线性TM表面波的传播特性

本文研究Ｋｅｒｒ型介质界面上弱非线性ＴＭ表面波的性质。数值计算表明了沿线性与非线性介质界面传播的ＴＭ表面波的自散焦特性。     

一种新的高次边缘元方法

讨论了一种新的高次边缘元方法，它不仅消除了伪解，并具有简单高效的特点．着重研究了二次边缘元的空间构造；给出了有关计算公式．对具有精确解的条形介质填充波导主模和高次模本征值的计算表明：二次边缘元方法的计算精度比一次边缘元提高约一个数量级．块状介质填充和衬底各向异性的微带线主模色散曲线的计算证实了该方法的精确性和广泛的适用性．     

Dynamic properties of carbon black filled chlorinated polyethylene/hindered phenol blends

Aggregates of carbon black (CB) in a polymer matrix have a tendency to form a CB network. The dynamic mechanical properties of binary systems of chlorinated polyethylene (CPE) and CB or 3,9‐bis{1,1‐dimethyl‐2[β‐(3‐tert‐butyl‐4‐hydroxy‐5‐methylphenyl)propionyloxy]ethyl}‐2,4,8,10‐tetraoxaspiro[5,5]‐undecane (AO‐80) and their ternary systems were investigated. It was found that the dynamic mechanical properties of those systems depend on the colloidal properties, surface oxides, and surface modification of CB. For binary systems of CPE and CB, oxidized CB gives a high modulus at low strain amplitude and a large Payne effect compared with untreated CB. In contrast, the reverse effect was observed for their ternary systems. Consequently, a good micro‐dispersion is obtainable by surface modification due to physical adsorption of AO‐80 on oxidized CB particles via hydrogen bonds. © 2003 Society of Chemical Industry     

Mathematical analysis of viscometric (polymer) flow fields in capillaries: Taylor dispersion revisited

A general formulation for capillary flow of two miscible fluids – one a dilute plug of polymer fluid inserted into a fully developed Poiseuille flow of the other, a Newtonian stream – is examined for its long time behavior. Phenomenologically, the system evolves from an initial state, that of a plug within the boundaries of sharp, well defined fronts inside a Newtonian stream, to a more homogenized state in the very long time scale. This problem was addressed by G.I. Taylor but with regard to a system of two Newtonian fluids, leading to the well-known results commonly described as `Taylor axial dispersion'. In this paper, a general and systematic perturbation analysis is presented from which Taylor's result is recovered as a special case of a more general solution which applies to fluids incorporating elastic properties. In particular, the influence of viscoelasticity and (polymer) diffusivity on the observed pressure profile in the capillary conduit is examined. This effect is clearly separated out for small Peclet number flows using asymptotic and numerical analysis. The results identify the influence of fluid viscosity, elasticity, and diffusivity on the observed pressure profile and form the basis for the improved characterization of polymeric elasticity using capillaries – a finding that is of significant scientific and commercial interest. These results were obtained by the authors as a class of observations resulting from the perturbation analysis of forced-flow capillary devices in viscoelastic fluid property investigation.     

一种基于小波变换的OTDR事件分析算法的研究

简单分析了用 OTDR卡进行光纤检测的原理 ,根据小波分析检测信号突变点的理论 ,提出了运用小波分析对光纤断点及反射事件准确定位的方法。理论分析和实例计算表明 ,这种方法对 OTDR曲线中反射事件尤其是断点的定位非常准确 ,是一种行之有效的方法