随机取向小冰晶多色粒子在红外谱区光散射的线偏振特征

用有限长圆柱状模拟小冰晶的非球形性，用T－矩阵理论研究了随机取向小圆柱状冰晶多色粒子光散射的线偏振特征，强调了在红外谱区波长从大气红外短波窗区（λ=3.979μm)到远红外λ=30μm的光散射，考虑了31种粒子的谱分布和10种圆柱状纵横比。广泛的计算结果表明，圆柱状小冰粒在红外谱区的线偏振强烈地依赖于波长和折射指数、粒子的纵横比和谱分布。与文献中类似的工作比较，获得了一些新的和有意义的结果。     

On the transverse vibrations of a revolving tether

We analyse the transverse vibrations of a tether, modelled as an inextensible cable, and revolving at an average rate equal to the orbital rate. The reference motion is a revolving rigid tether. During this motion the force in the tether (time and location dependent) remains, in a first approximation, aligned with the tether axis. Separation of variables for the vibrations about this motion gives a Legendre equation for the spatial dependency of the deformations and Hill's equations for time dependency of the in- and out-of-plane deformations. The boundary conditions on the Legendre equation generate a series of admissible values of the separation constant that become equidistant. The two Hill's equations generate a series of intervals, contracting to equidistant critical values, where the solutions are unbounded. The admissible values of the separation constant must avoid these intervals. Asymptotic expressions for the separation constant and the critical values are given. The first and second in-plane deformation mode arc unstable for zero end masses. By increasing the ratio of the concentrated over the distributed mass the deformation modes can be stabilised and the values of the separation constant can be made a multiple of the distribution of the critical points. Introducing unequal tip masses does not affect this result.     

解流体动力弥散问题的等参数溶质质量均衡有限元法与其它方法的比较

本文将解流体动力弥散问题的等参数溶质质量均衡有限元法与采用同样非线性基函数的等参数里茨(Ritz)有限元法或伽辽金有限元法做以比较发现,前者具有物理意义明确,能准确反映局部质量均衡关系,计算公式简单,易于接受应用等优点,克服了线性有限元法的插值函数不能体现单元内部溶质质量守恒一般规律的缺点。     

Seismic history and consistent seismicity: Evidence from southern Italy

In this paper a method is proposed to evaluate the seismicity level of an area in a given historical period, based on records of seismic events, source characteristics and intensity attenuation with distance. Also considered is the seismic activity recorded in southern Italy during the 10th and 11th centuries, seismic records being obtained from all available sources. To determine the level of seismicity, a key role is played by source characteristics, i.e. recording modalities and activity periods of recording centers. In addition, models of intensity attenuation with distance allow the assessment of the size of the area under investigation. This paper identifies the areas, in the 10th and 11th centuries, where major earthquakes (M 6.5) did not occur during periods of silence of sources, as well as those where such events cannot be excluded. For each area, different levels of probability were determined by applying the Cox linear logistic model to historical seismic data. The completeness analysis, in terms of area and time-span coverage, is a valuable tool to assess seismicity in seismogenetic areas. The reproducibility of the model for lower magnitude earthquakes (M < 6.5) is reliable.     

Application of Correspondence Analysis in the Assessment of Groundwater Chemistry

Correspondence Analysis (CA) was used to determine the sources and processes that may explain the variation observed in datasets of groundwater analyses. The following method was adopted: (1) based on the observation of sympathies and antipathies between loadings signs, correspondence factors were represented by parameters with some pertinent geochemical meaning: (2) the relation between factors and parameters then was checked by Multiple Linear Regression (MLR) where factors acted as independent variables and parameters as dependent variables. Sample scores of the selected parameters gave the ability to separate polluted from nonpolluted waters, identify areas where pollution is dominated by agriculture and areas where contamination is controlled by domestic effluents, and describe weathering and agricultural activities in the sampled area. The practical example presented here anticipates the impact of agriculture and urban pollution on the chemistry of 160 water samples collected in a granitoid area at central Portugal (Fundão).     

线性-动态规划改进模型及其应用

Becker和Yeh于1974年提出的线性(LP-DP)模型是一种功能很强的优化模型。然而该模型是针对梯级发电库群实时调度提出的,对并联系统并不适用。且该模型在理论上还不够严密,需进一步完善。本文所提出的LP-DP改进模型不但在理论上比较完整,而且扩展了应用范围,提高了优化效益。该模型现已成功地应用于江西省水火电力系统实时优化调度之中。