The design and implementation of a scheme for large ordered indices

Consider a very large ordered collection of indices for an index organization of a dynamically changing random access file. In this paper, we propose a technique for compressing keys from the collection of indices into the minimal set, and hence reducing tremendously the storage space requirement. A set of criteria is given for considering whether the application of this compression technique on keys can meet the minimal space requirement. We also propose the storage structure design for these compressed indices with a view to tackling the key redundancy problem, supporting a general algorithm for retrieving the keys and minimizing costs for updating and maintenance of indices. Finally, we give a comparison between the use of ON KEY interruption implemented in PL/1 and the use of the key compression technique and the hierarchical tree structure as our alternative in dealing with indexed sequential files.     

南潦闸防洪标准安全复核

利用最新的水文资料对南潦闸设计洪水重新进行复核计算.根据现有的洪水标准要求,指出了南潦闸现状的防洪能力.     

山西省汾河、漳泽水库管理标准化防洪决策支持系统研究

介绍了汾河水库及漳泽水库管理标准化防洪决策支持系统研究成果。研究中发挥了多学科综合优势，充分利用计算机技术的最新成就，把目前国内外常用的方法、最新研究成果和实际经验等融入项目研究中，推出了标准化的、具有不同特点的水库洪水调度系统开发模板。该系统软件技术上具有先进性、功能上具有外包性、使用范围上具有广泛的适应性，解决了水库防洪等实际生产中的许多复杂技术难题。     

龙山水库防汛抢险方案的实践与探讨

1994年8月14日，龙山水库上游突降暴雨，水库水位骤升，在肾急起闸时两孔闸门4个吊点的钢丝绳全部拉断，情况非常危急。文中记述了事件的处理过程，由于利用千斤顶一举托起大闸门，从而保住了水库，保住了下游人民生命财产的安全。同时文中也分析了钢丝绳拉断的四大原因，对今后水库的管理，防汛检查，抢险时制定切合实际方案的重要性也作出了阐述。     

Safety assessment in plant layout design using indexing approach: implementing inherent safety perspective. Part 2-Domino Hazard Index and case study

The design of layout plans requires adequate assessment tools for the quantification of safety performance. The general focus of the present work is to introduce an inherent safety perspective at different points of the layout design process. In particular, index approaches for safety assessment and decision-making in the early stages of layout design are developed and discussed in this two-part contribution. Part 1 (accompanying paper) of the current work presents an integrated index approach for safety assessment of early plant layout. In the present paper (Part 2), an index for evaluation of the hazard related to the potential of domino effects is developed. The index considers the actual consequences of possible escalation scenarios and scores or ranks the subsequent accident propagation potential. The effects of inherent and passive protection measures are also assessed. The result is a rapid quantification of domino hazard potential that can provide substantial support for choices in the early stages of layout design. Additionally, a case study concerning selection among various layout options is presented and analyzed. The case study demonstrates the use and applicability of the indices developed in both parts of the current work and highlights the value of introducing inherent safety features early in layout design.     

Large-Scale Flume Tests of Riprap-Apron Performance at a Bridge Abutment on a Floodplain

Laboratory tests using a large-scale model of a spill-through bridge abutment led to important findings about the performance of a riprap apron as an abutment scour countermeasure. Riprap stone is widely used for protecting side slopes of embankments against erosion, and several design guidelines are available in the literature. In contrast, only a few guidelines exist for the design of a riprap apron around an abutment. These guidelines focus only on the armoring effect of riprap, neglecting other effects. This study shows that apron performance involves several mechanisms: armoring the bed, dissipating large-scale turbulence shed from the abutment, reducing the peak unit discharge, reducing the average shear stress, and shifting the scour region away from the abutment. Together, these mechanisms substantially reduce the maximum scour depth. The test findings are compared with those from a much smaller model of riprap-apron performance.     

Case Study: Influence of Morphological Changes on Flooding in Jingjiang River

The middle reach of the Yangtze River, customarily called the Jingjiang River, together with its diversion channels and Dongting Lake, form a large complicated drainage system. In the last five decades, significant geomorphological changes have occurred in the drainage system, including the shrinkage of diversion channels, contraction of Dongting Lake, changes in the rating curve at the Luoshan station, and cutoffs of the lower Jingjiang River. These changes are believed to be the cause of the occurrence of abnormal floods in the Jingjiang River. Qualitative analyses suggest that the first three factors aggravate the flood situation in the lower Jingjiang River, while the last factor seems beneficial for flood prevention. To quantitatively evaluate these conclusions, a finite-volume numerical model was constructed. A series of numerical simulations were carried out to test the individual and combined effects of the aforementioned four factors, and these simulations showed that high flood stages in the Jingjiang River clearly are related to the geomorphological changes.     

Flood Inundation Modeling with an Adaptive Quadtree Grid Shallow Water Equation Solver

Flood risk studies require hydraulic modeling in order to estimate flow depths and other hydraulic variables in the floodplain for a wide range of input conditions. Currently there is a need to improve the computational efficiency of fully two-dimensional numerical models for large-scale flood simulation. This paper describes an adaptive quadtree grid-based shallow water equation solver and demonstrates its capability for flood inundation modeling. Due to the grid dynamically adapting to dominant flow features such as steep water surface gradients and wet-dry fronts, the approach is both efficient and accurate. The quadtree model is applied to a realistic scenario of flood inundation over an urban area of 36?km2, resulting from the flood defenses breaching at Thamesmead on the River Thames, United Kingdom. The results of the simulation are in close agreement with alternative predictions obtained using the commercially available software TUFLOW.     

关于高校专业实验室评估的若干思考

本文回顾了我国高校教学实验室评估工作的历程,分析了专业实验室评估面临的新形势,研究并提出了专业实验室评估应把握的基本原则,设计构建了专业实验室评估指标体系的基本架构,阐述了评估工作的组织实施办法。     

遵循自然过程的河流防洪规划——以浙江台州永宁江为例

随着当前世界性资源与环境危机的陡现,人们对洪水及防洪的认识也发生着根本性的变化。一些国家的防洪理念逐步从抵抗洪水向自然防洪转变。针对中国人多地少、社会经济活动密集的现实,应探讨既尊重洪水自然过程,又考虑土地有效利用的防洪途径。在对相关理论进行总结的基础上,分析了国内外相关案例,并以浙江台州永宁江为例,对基于自然防洪思想的河流防洪规划作了初步实证研究。