River adjustment to changes in sediment load: The effects of tin mining on the Ringarooma River,Tasmania, 1875–1984

The mining of alluvial tin in the Ringarooma basin began in 1875, reached a peak in 1900–20, and had virtually ceased by 1982. During that time 40 million m³ of mining waste were supplied to the main river, quickly replacing the natural bed material and requiring major adjustments to the channel. Based on estimates of sediment supply from more than 50 widely scattered mines and the frequency of flows capable of transporting the introduced load, the river's transport history is reconstructed using a mass-conservation model. Because of the lengthy time period (110 years) and river distance (75 km) involved, the model cannot predict detailed change but it does reproduce the main pattern of sediment movement in which successive phases of aggradation and degradation progress downstream. Peak storage is predicted in that part of the river where braiding and anastomosis are best developed. Aggradation was most rapid in the upper reaches close to major supply points, becoming slower and later with distance downstream. Channel width increased by up to 300 per cent where the valley floor was broad and braiding became relatively common. Bridges had frequently to be replaced. While bed levels were still rising in lower reaches, degradation began in upper ones, notably after 1950, and by 1984 had progressed downriver over 30 km. Rates of incision reached 0·5 m yr^?1, especially in the early 1970s when record high flows occurred. As a result of degradation the bed material became gravelly through either reexposure of the original bed or lag concentration of coarser fractions. Also a narrower unbraided channel has developed. The river is beginning to heal itself and upper reaches now have reasonably stable beds but at least another 50 years will be required for the river to cleanse its channel of mining debris.     

在地面三角网中布设卫星观测站的最低精度要求

本文从地面三角网和卫星同联合平差的原理出发,讨论了对卫星网的最低精度要求。指出,为改善地面三角网而布设卫星网时,卫星观测站的最低精度主要决定于以下因素: ——地面三角网的精度; ——对地面三角网精度改善程度的要求; 一卫星观测站之间的距离。这里通过模拟计算对卫星网的最低精度要求与上列因素之间的关系作了数字分析,并建立了估算卫星网最低精度的数学模型。预期,在一般情况下,该模型的估算误差将不会超过10％。     

Quantitative chemical characterization of vitrinite concentrates using pyrolysis-gas chromatography. Rank variation of pyrolysis products

A series of hand-picked vitrinite samples from the Lower Kittanning Seam, Pennsylvania have been examined using quantitative pyrolysis-gas chromatography. These vitrinites ranged in rank from 0.59 to 1.71% reflectance, a rank range from high volatile C bituminous to low volatile bituminous. High molecular weight pyrolysis products included alkyl aromatic and phenolic compounds. Attempts have been made to correlate the pyrolysis product composition to rank parameters including vitrinite reflectance, volatile matter yield, carbon content, atomic H/C ratio and Rock-Eval determined T_max. Total yield of phenols was found to be strongly and inversely rank related. A clear relationship between C₈ alkyl-benzene yield and rank was not found for the sample set.     

地幔对流与岩石层板块的相互耦合及影响──（Ⅰ）球腔中的自由热对流

板块运动是地幔对流的主要证据之一．同时，作为地球动力系统中一个相对独立部分，板块自身的存在和运动对地幔内部物质的流动形态有巨大影响．地幔内部的流动由两部分组成：一是由内部非绝热温度差异造成的自由对流解；另一部分是由在地表运动的板块所激发．作为系列工作的第一部分，本文研究球腔中的自由热对流问题．得到了对地幔对流研究有实际意义的下边界为自由、上边界为刚性情况下的临界瑞利数值，不同的瑞利数时球腔内流场和温度场的分布形态等．     

典型构造背景应变场特征及其演化趋势

在外力作用下，一定的构造形式周围会产生特定的应变图象。其形态特征在失稳过程中会发生变化。研究应变图象的特征及其变化有助于鉴别失稳前兆，预测变形发展趋势。受构造形式控制，应变场在空间分布上可以划分为若干区域。在变形与失稳过程中，各个区域既有不同的变形行为，也相互影响、相互制约，构成一个紧密联系的动态体系。因此，应当全面观测应变场图象的时间与空间动态演化过程，从中获取失稳前兆，分析失稳机制     

山地边界层中场变量的动力学研究

采用与实测较接近的二次函数来表达Ｅｋｍａｎ层中的湍流粘性系数Ｋ，在圆形气压场条件下，求得了山地上空边界层中的风速，进而求得散度、涡度和垂直速度等场变量随高度的分布。并作图分析了这些场变量的一些动力学特征。改进了以往在求解析解时，略去运动方程中湍流粘性力项中的关于高度的一阶导数项，以及取山坡面上风速为零作下边界条件等欠合理欠精确的做法。所求得的风速、散度、涡度和垂直速度均用简单的初等函数表示出来，有助于边界层参数化和深化对边界层动力学的认识。     

论板块运动的驱动力

本文从动力学的角度讨论了板块运动的驱动机理,并提出了计算板块扩张速度的公式,然后求出了不同类型板块的扩张速度。用此公式所计算出的板块扩张速度与实际观测速度很符合。     

动态聚类-模糊模式识别及其应用

本文以模糊子集论为指导,在迪戴的DCM法的基础上提出了动态聚类-模糊模式识别方法。实际上,它是一种新的模糊聚类的方法。该方法以DCM法的动态聚类部分做为原始数据变换的手段,而将迪戴的强模式概念推广为模糊模式,将强模式识别推广为模糊模式识别。此外,还提出了模糊模式间联系度的概念,从而解决了类间联系、类内典型个体、类间过渡个体、个体对各类的隶属程度以及内部有某种演化趋势的类别的划分等问题。文章还给出了该方法的数学模型和算法概要。最后,通过一个在地质学中的应用实例,说明了该方法的应用效果。     

江苏水文站网优化调整有关问题的思考

在概述全省站网现状基础上，分析了站网优化调整的主要原因，提出了如何优化调整的总体思路和基本构想，进一步明确强调在水文站网优化调整中需要坚持和把握的原则和方法。     

新时期农村产业结构优化调整研究

通过在农村长期的工作实践和对农村经济发展的考察,依据当前国内外发展对农村产业经济发展的要求,分析研究我国和河南省农村产业结构的发展现状和动态变化,提出农村产业结构调整的指导思想、原则及目标,据此,从农村产业结构调整、农业产业结构调整和种植业结构调整3个层次,研究提出农村产业结构调整的基本思路和方向,为有关部门决策农村经济发展提供科学依据.