Simple analytical Green's functions for ray perturbations in layered media

The total Green's function for two-point boundary-value problems can be related to the propagator for initial-value problems. A very simple expression for the Green's function is obtained when the unperturbed medium may be described by material with a constant gradient in quadratic slowness. The derivation requires a correct understanding of assumptions made in the propagator solution. Expressions are also obtained for Green's function in multilayered media.     

方差分量估计的MINQE理论及其在摄影测量中的应用

本文深入研究了异方差分量模型的MINQE(U,I)准则的算法实现的可能性,所导出的约化算法具有压缩内存,提高运算速度等明显优点,因而具有实用意义。文中介绍了实现约化算法的计算机程序框图,并提供了数据例子。作者将方差分量估计的MINQE理论引入解析摄影测量平差实践,分别采用模拟数据和新滩滑坡监测数据研究了自检校光束法平差中随机模型的确定,结果表明,MINQE理论用于自检校的验后权估计是可行的。最后,作者就平差随机模型的扩展,以及MINQE理论的应用提出了进一步研究的几点设想。     

一种测求水井含水层导水系数的新方法

本文给出了一种测求水井含水层导水系数的新方法。利用Cooper理论和振动理论,通过简单的试验,可以测求出水井含水层的导水系数。用这种方法计算出珍珠泉井含水层的导水系数为2439m~2/d,用抽水试验法测得该系数为2618m~2/d,两者符合得较好。     

垂直地震力作用下弹性半空间上扁壳基础的解析解

用布希涅斯克定义的弹性半空间内的垂直位移包括两项积分,除了积分号前面系数的差别之外,第一项积分是单层位势而第二项积分为双层位势。若扁壳基础是正高斯曲率的几何曲面,则壳底与半空间表面间的挤压强度就是半空间表面作用的分布垂直荷载。当越过边界时,双层势位的函数值和单层势位的法向导数值发生跳跃。利用这些性质,本文得出布希涅斯克积分的反演公式,从而避开要求解偏微分—积分方程组的巨大数学困难而易于得出解析解。以椭园抛物面扁壳为例说明本文方法的应用。     

Hydrophobic and electrostatic parameters in bacterial adhesion

Recently it has been shown that the initial stages of bacterial adhesion to a model-surface of sulphated polystyrene can best be described using hydrophobic and electrostatic parameters. In the present study it is tested whether these parameters can generally be applied to predict bacterial adhesion by using (i) glass, as a model for hydrophilic and natural surfaces of silicates and oxides, (ii) polystyrene coated with proteins, as a model for a surface coated with an organic layer, and (iii) river Rhine sediment, as an example of a natural surface. Adhesion to glass was dominated by electrostatic interaction, whereas adhesion to polystyrene coated with various types of proteins depended on the surface characteristics of the bacteria and the type of protein. By relating Van der Waals interactions to hydrophobicity of the interacting species, the adhesion of bacteria to the various surfaces including the river Rhine sediments could be interpreted in terms of the DLVO-theory. It is therefore concluded that the conceptual principles of the DLVO-theory (interplay of Van der Waals and electrostatic interactions) are suitable to describe, at least qualitatively, the initial processes of bacterial adhesion to a wide range of surfaces.     

Some elements of mathematical information theory and total inversion algorithm applied to travel time inversion

The total inversion algorithm and some elements of Mathematical Information Theory are used in the treatment of travel-time data belonging to a seismic refraction experiment from the southern segment (Sardinia Channel) of the European Geotraverse Project. The inversion algorithm allows us to improve a preliminary propagating model obtained by means of usual trial and error procedure and to quantify the resolution degree of parameters defining the crust and upper mantle of such a model. Concepts related to Mathematical Information Theory detect some seismic profiles of the refraction experiment which give the most homogeneous coverage of the model in terms of number of trajectories crossing it. Finally, the efficiency of the inversion procedure is quantified and the uncertainties regarding knowledge of different parts of the model are also evaluated.