DDOS(分布式拒绝服务)研究与探讨

由于目前网络安全问题的日趋严重, ＤＤＯＳ（ Ｄｉｓｔｒｉｂｕｔｅｄ Ｄｅｎｉａｌ ｏｆ Ｓｅｒｖｉｃｅ,分布式拒绝服务攻击）的攻击手段严重威胁 Ｉｎｔｅｒｎｅｔ的安全。文章详细地介绍了什么是 ＤＤＯＳ及其造成的危害,Ｗ理论上分析了其体系结构和运作情况,并实际列举了一些著名的ＤＤＯＳ 工具及其特点,尝试提出有关ＤＤＯＳ的攻击检测规则和相关的检测工具。     

规则格网DTM快速构建算法研究*

规则格网(Grid)是数字地形模型(DTM)最常用的表示方法,有着广泛的应用。研究了基于离散点、三角网两种空间数据的规则格网快速构建算法。实验表明,分块索引方法及扫描线填充方法的引入实现了规则格网的快速生成,在大数据量条件下,效果也非常明显。     

液压卧倒闸坝在拦河坝工程中的应用

简述液压卧倒闸坝在江西省宜春市袁州区温汤镇防洪工程拦河坝中的应用。设计通过对多方案技术经济比选,推荐采用液压卧倒闸坝。可供类似工程参考。     

Flood Management in Japan—From Rivers to Basins

Abstract

The River Commission of the Ministry of Construction in Japan recommended a basin response to floods in its December 2000 Interim Report to Minister of Construction. This is practically an official declaration of the policy accepting inundation in habited areas. By this policy shift, it is anticipated that more basin response measures and non-structural measures against floods will be promoted to complement structural measures such as continuous levees and dams. Such a policy is not new in the world but is a significant governmental move in Japan, a densely populated, highly developed, and highly flood hazardous country. Although living with floods is a universal coping strategy, the implementation of measures should be different from region to region reflecting region's nature and socio-economic conditions. This paper reviews the flood fighting history of Japan and her statutory evolution against floods and shows the process by which the ever-increasing flood damage potential and the recent increase of flood damages necessitated the official move in flood control management from rivers to basins.     

Predicting dam failure risk for sustainable flood retention basins: A generic case study for the wider Greater Manchester area

This study aims to provide a rapid screening tool for assessment of sustainable flood retention basins (SFRBs) to predict corresponding dam failure risks. A rapid expert-based assessment method for dam failure of SFRB supported by an artificial neural network (ANN) model has been presented. Flood storage was assessed for 110 SFRB and the corresponding Dam Failure Risk was evaluated for all dams across the wider Greater Manchester study area. The results show that Dam Failure Risk can be estimated by using the variables Dam Height, Dam Length, Maximum Flood Water Volume, Flood Water Surface Area, Mean Annual Rainfall (based on Met Office data), Altitude, Catchment Size, Urban Catchment Proportion, Forest Catchment Proportion and Managed Maximum Flood Water Volume. A cross-validation R² value of 0.70 for the ANN model signifies that the tool is likely to predict variables well for new data sets. Traditionally, dams are considered safe because they have been built according to high technical standards. However, many dams that were constructed decades ago do not meet the current state-of-the-art dam design guidelines. Spatial distribution maps show that dam failure risks of SFRB located near cities are higher than those situated in rural locations. The proposed tool could be used as an early warning system in times of heavy rainfall.     

基于考虑外生变量的SWARCH模型对中国股市波动性的实证研究

货币供应量是货币政策的主要调控指标,在很大程度上影响着股市的波动情况,作者将货币供应量作为外生变量加入到SWARCH模型中,建立了上证指数的考虑外生变量的SWARCH模型,实证研究结果表明该模型具有较好的拟合和预测效果．     

南四湖水体富营养化时空比较分析与评价

南四湖是南水北调东线工程重要的输水通道和调蓄湖泊之一,随着通水时间的临近,其水质安全和水体富营养化状况备受关注．根据2006、2007、2010和2011年4次32个采样点的南四湖水质空间分布监测数据,采用综合营养状态指数法进行评价．结果表明,4个监测年枯水期南四湖水体总体平均处于富营养轻度水平,在南四湖水质得到大幅度改善的情况下,各年营养水平变化不大;南阳湖和独山湖水体的综合营养状态指数出现下降趋势,而昭阳湖（下）和微山湖岛北水体的综合营养状态指数出现上升趋势,这与全湖总磷出现均一化趋势有关．2010-2011年除微山湖岛南水体处于中营养水平外,其他湖区水体均处于富营养轻度水平．对南四湖水质空间分布监测数据的分析表明,南四湖藻类水华的繁殖生长主要受水体中TP的制约．     

医师科技创新能力评价指标构建

本文运用文献分析法、Delphi法和层次分析法筛选和确定了医师科技创新能力指标体系。该评价体系包括专业教育背景、知识创新能力、技术创新能力和学术交流能力4项一级指标,11项二级指标,部分二级指标又细分为三级指标,对每一指标给出相应权重系数和内涵,并对各项指标提出量化方法。     

AMPHIBIAN OCCUPANCY IN FLOOD‐CREATED AND EXISTING WETLANDS OF THE LOWER MISSOURI RIVER ALLUVIAL VALLEY

During the previous century, the wetland area in the lower Missouri River alluvial valley was reduced by 39% because of river channelization and bank stabilization projects. The Great Flood of 1993 reversed the trend of wetland loss by creating 466 new wetlands in the alluvial valley between Kansas City and St. Louis, Missouri. We estimated amphibian occupancy, detection probability and number of species exhibiting evidence of reproduction in eight flood‐created and 16 pre‐flood existing wetlands from 1996 through 1998. We also evaluated whether hydroperiod (the number of days any water was present in a wetland from 20 February through 31 August) and distance to river predicted those values. Detection probabilities for adult amphibian species were relatively constant across years and ranged from 0.013 [Great Plains toad (Anaxyrus cognatus)] to 0.280 [Woodhouse's toad (Anaxyrus woodhousii woodhousii)]. Occupancy of adult amphibians differed across years and was not correlated with habitat features. Estimated occupancy probabilities for amphibian species ranged from 0.126 [Plains spadefoot (Spea bombifrons)] to 0.896 [boreal chorus frog (Pseudacris maculata)]. Almost double the number of amphibian species showed evidence of reproduction in existing wetlands (wetlands created before the Great Flood of 1993) when compared with that in flood‐created wetlands. Similarly, temporary wetlands had nearly double the number of amphibian species showing evidence of reproduction when compared with permanent wetlands. Finally, the highest number of species showed evidence of reproduction in wetlands with spring–summer hydroperiods between 135 and 140 days. All these relationships suggest that the invasion and persistence of predators in wetlands negatively influence amphibian reproduction. If the Missouri River is allowed to reconnect with the alluvial valley, more predators may be introduced into wetlands, leading to reduced amphibian occupancy and reproduction. However, this connection will not likely occur over the entire alluvial valley and, therefore, should not adversely impact amphibians that find refuge in higher‐elevation, non‐connected regions of the alluvial valley. Copyright © 2011 John Wiley & Sons, Ltd.     

水贫困指数在河西走廊三大内陆河流域的应用

水贫困指数提供了一种简单、易行的水资源评价方法,它通过资源、途径、能力、利用和环境5个方面来定量评价区域水资源的相对水平。运用主客观组合赋权法确定各分指标的权重,对河西走廊三大内陆河流域的水贫困指数进行了研究。结果表明:黑河流域、疏勒河流域、石羊河流域的水贫困指数分别为39.4、66.0、36.6,评价结果与客观情况基本相符。