The use of laboratory experiments for the study of conservative solute transport in heterogeneous porous media

 Laboratory experiments on heterogeneous porous media (otherwise known as intermediate scale experiments, or ISEs) have been increasingly relied upon by hydrogeologists for the study of saturated and unsaturated groundwater systems. Among the many ongoing applications of ISEs is the study of fluid flow and the transport of conservative solutes in correlated permeability fields. Recent advances in ISE design have provided the capability of creating correlated permeability fields in the laboratory. This capability is important in the application of ISEs for the assessment of recent stochastic theories. In addition, pressure-transducer technology and visualization methods have provided the potential for ISEs to be used in characterizing the spatial distributions of both hydraulic head and local water velocity within correlated permeability fields. Finally, various methods are available for characterizing temporal variations in the spatial distribution (and, thereby, the spatial moments) of solute concentrations within ISEs. It is concluded, therefore, that recent developments in experimental techniques have provided an opportunity to use ISEs as important tools in the continuing study of fluid flow and the transport of conservative solutes in heterogeneous, saturated porous media. Received, December 1996 · Revised, July 1997 · Accepted, August 1997     

Population distribution and its change in Guangzhou city

Ｉ．ＰＯＰＵＬＡＴＩＯＮＤＩＳＴＲＩＢＵＴＩＯＮＣＨＡＲＡＣＴＥＲＩＳＴＩＣＳＢｙｔｈｅｅｎｄｏｆ１９９４,ｔｈｅｐｏｐｕｌａｔｉｏｎｏｆＧｕａｎｇｚｈｏｕＣｉｔｙｈａｄｉｎｃｒｅａｓｅｄｔｏ３．８０３ｍｉｌｉｏｎ,ａｐｏｐｕｌａｔｉｏｎｓｉｚｅｒａ...     

我国境外旅游本底趋势线的建立及科学意义

提出了旅游本底趋势线的概念,依据１９７８￣１９９６年共计１９境外客流量统计数据,经过“滤波”订正,建立了外国人,港澳台胞,华侨及境外客流总量４条本底趋势线;利用旅游本底趋势表“晴雨表”功能说明‘８９风波地我国境外旅游业的影响,利用预测功能预估了未来４年我国境外旅游业的发展趋势。     

大口径硬岩钻凿技术现状与研究方向

大口径硬岩钻凿是一个技术难题,尽管国内外科学家和工程技术人员研究思路及方法较多,并取得了一定效果,但是,仍然存在着各种问题和不足。笔者对目前国内外研究现状作了简要综述,并结合国情对其研究方向和思路提出了自己的观点。     

New seismological constraints on differential rotation of the inner core from Novaya Zemlya events recorded at DRV, Antarctica

Novaya Zemlya nuclear test records at the seismic station DRV, Antarctica, are analysed in order to obtain further constraints on a possible differential rotation of the inner core with respect to the mantle. These data allow the sampling of the inner core along a nearly polar path in very stable conditions over more than two decades, from 1966 to 1990. The PKP (BC)– PKP (DF) traveltime residuals, which reflect the inner-core anisotropy and/or heterogeneities sampled along the path, exhibit a great stability through time. A computation of the residuals that are expected for various differential rotation rates and the same rotation axis as the mantle has been performed using the worldwide residual catalogue of Engdahl et al . (1997) for summary rays that include the time as an additional parameter in data stacking. Comparison of data and predictions shows that an eastward differential rotation with a rate as large as 3°  yr⁻¹, as suggested by some authors, is not possible, but an eastward rotation at 1°  yr⁻¹ or lower cannot be rejected.     

荆山群的地层结构及野头组含金性研究

在荆山群建组剖面实地研究的基础上,补测了野头组的禄格庄剖面,考察了荆山区至平度区荆山群的相变规律,采用数学地质方法研究荆山群地层结构及生成环境,得知：荆山群无论在原岩建造、岩性组合、生成的古地理环境均不同于胶东岩群。荆山群形成于不稳定的冒地槽环境,相变剧烈,由荆山区至平度区厚度锐减,火山活动减弱。荆山群在总体上表现为三大周期,对应三个组,各组内部具有不同的沉积韵律和拟周期,野头组火山沉积和禄格庄组的砂泥质沉积是荆山群金的高丰度部位。野头组的火山建造形成于海底裂陷环境,金主要赋存在正常沉积与火山沉积的交变带中。产于进入火山活动和由火山活动转出的历史阶段,属火山喷气—溢流阶段的产物。     

从地震地质学角度对震后的地震活动趋势进行预测

本文从地震地质学的角度，通过综合分析、数理统计和实际计算获得了判定地震序列类型的定量和定性指标，提出了中小地震（群）后地震活动趋势和大震后强余震预报的地震地质学方法，通过一些地震实例的实践与检验，证明本文提出的方法是行之有效的，可用于震后地震活动趋势的预测和预报。     

长江下游感潮河段大洪水和特大洪水的形成及趋势

分析了长江下游感潮河段大洪水和特大洪水高水位形成的水文因素,揭示了年最高水位今后一段时期内可能的变化趋势。主要结论是:该河段大洪水和特大洪水高水位的形成原因十分复杂,本世纪以来每次大洪水和特大洪水高水位的形成几乎都有其主要原因;该河段大洪水特大洪水高水位出现的频次有增加趋势;自1975年以来,年最高水位的均值呈明显的升高趋势,其主要原因是人类活动对防洪产生的负面影响,海平面上升也有一定的影响。     

农业气候年景预测和决策服务系统的研究

农业气候年景预测和决策服务系统（ACHPDS）由三部分组成。介绍了农业气象灾害预测（AMDP）、农作物产量年景预测（COHP）及农作物种植面积合理配置决策系统（CAAD）的研究方法和应用情况。