江西省灌区工程老化损坏现状及其改造对策

本文叙述了江西省灌区工程老化损坏的现状,指出采用坚决措施维修或改造工程以及增加改造资金的投入是减少灌区工程老化损坏的重要途径。     

盘锦灌区工程老化损坏问题及其改造

经30a大规模开发建设,盘锦灌区已具相当规模.但灌区工程老化损坏严重,已影响了农业生产和辽河三角洲农业二期开发建设.经调查分析工程老化损失原因有:工程超期"服役",自然老化或损坏;地震破坏;机泵受海水浸蚀、变压器器材陈旧;工程标准低、施工质量差;工程不配套;管理不善,维修养护不及时;人为损坏等.提出改造对策是:①进行灌区更新改造,采取国家、地方、集体进行集资建设;②农业用水按成本收费;③健全管理制度,深化灌区体制改革;④兴办经济实体,开展多种经营;⑤加强法制建设     

水闸工程现状存在病险问题及规划建设研究

绥中县共有水闸71座,其中有4座水闸存在不同的病险问题。目前,病险水闸工程存在着在渗流破坏,消能设施损坏,闸门启闭机损坏等不同程度的损坏。针对这些问题,提出了对现有病险水闸进行除险加固和加强工程运行管理等措施,解决灌区排灌设施老化,使之不影响灌区的正常灌溉和用水效率,确保水闸充分发挥应有作用。     

灌区骨干工程水情监测系统的方案比选

针对辛庄引黄灌区运行现状,进行科学分析,介绍了该灌区骨干工程中存在的主要问题,如工程老化严重、标准较低、节水防渗措施不到位、建筑物老化、损坏严重等等,并提出了合理的解决措施与灌区骨干工程水情监测系统技术方案。     

浅析宁夏引黄灌区工程老损改造

宁夏引黄灌区位于黄河上游,是全国古老的大型灌区之一。有效灌溉面积为550万亩,约占全区总灌溉面积的90％;年产粮食15.5亿公斤,占全区总产量的75％;灌区工农业产值分别占全区的97％和87％,灌区是宁夏经济和社会发展的重要基础,也是全国20个商品粮基地之一。 但是,由于整个灌区工程老化损坏严重,供水能力下降,效益难以保持,制约了我区工农业生产的发展。 工程老化损坏现状 工程老化失修,致使功能降低。     

汾河灌区工程老化损坏分析与对策

水利工程老化损坏是汾河灌区效益衰减的主要原因之一。为充分发挥汾河灌区水利工程的效益．适应灌区国民经济发展对工农业生产的要求，当务之急应对水利工程老化损坏的现状、成因及后果进行分析，并在此基础上针对汾河灌区水利工程老化损坏情况提出应采取的对策。1概述1．1灌区     

淠史杭灌区存在问题与节水改造

文章对淠史杭灌区目前存在的工程不配套，老化损坏严重，输水损失大，管理设施陈旧，水费标准低，效益衰减等情况作了叙述，指出要抓住机遇进行灌区节水改造。     

密云县灌区配套改造工程中着重解决的几个问题

密增县灌区工程大都建于50－60年代，工程运行几十年来老化失修，渗漏水严重，至今已不能发挥其设计效益。目前按水利部规定的划分标准测定，损坏程度已达到了二级，部分地区达到了一级。因而密云县灌区改造任务十分繁重。针对灌区存在的问题，在配套改造工程建设中急需解决以下几个问题。     

漳河水库灌区农业水资源利用综合评价分析

应用层次分析法对湖北省漳河水库灌区2005年农业灌溉实际用水资料进行综合评价分析。其结论为:灌区农业水资源利用综合评价总体情况较好,16项主要指标中的大多数达到了较高的水平,但水资源短缺和灌区工程老化损坏较严重等问题将是制约和影响灌区可持续发展的重要因素,应引起有关部门的高度重视。所建立的评价模型分析结果与实际情况相比,基本吻合。     

灌区工程群体年龄结构预测与控制

本文在全国大型灌区工程老化调查和老化机理评估分析的基础上，提出了一种动态机理模型（ＤＹＭ），对工程老化的群体年龄结果进行模拟识别，确定了映射矩阵的元素值；分析了我国灌区工程老化的特点；并在数学模型及控制特性分析、论证的基础上，对工程老化趋势和后果进行了预测，提出了按稳定年龄结构进行控制的遏制工程过速老化的对策方案。     

地下厂房施工过程的三维非线性数值模拟分析

根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。     

Evaluation of freshwater mussel relocation as a conservation and management strategy

The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects.     

基于模型试验的河床砂砾石层基本特性研究

为了经济可靠地确定深厚覆盖层的基本特性参数,以大渡河双江口水电站坝基河床砂砾石层基本特性研究为工程背景,进行大尺寸模型试验,研究河床砂砾石层的旁压模量和动探击数随密度、级配以及上覆压力的变化规律。根据室内模型试验结果,结合现场旁压试验及钻孔试验成果,推断出坝址区河床砂砾石相关层位的密度,并依此进行砂砾石室内力学试验,获得设计所需力学参数。研究成果可为深厚覆盖层基本特性测试提供新的方法。     

Serial discontinuities in a Rocky mountain river. I. Distribution and abundance of plecoptera

Samples were taken year-round at eleven sites along the altitudinal profile (2900-1400 m a.s.l.) of the Gunnison River, a 329 km tributary of the Colorado River, to document the distribution of the Plecoptera and to evaluate responses to hypolimnial-release dams in the headwaters and middle reaches. Twenty-two species were present, with the greatest species richness occurring in an unregulated segment upstream of the middle reach dams; average nymphal biomass over the study period (175 organisms, 395 mg dry mass m^?2) was also greatest in this segment. Only four species (58 organisms, 48 mg m^?2) were present in the tailwaters of the headwater dam and values were greatly reduced (nine species; 35 organisms, 180 mg m^?2) below the middle reach dams. The stonefly community recovered ca. 80 km downstream from the last dam (15 species; 244 organisms, 250 mg m^?2), apparently in response to natural resetting of environmental conditions corresponding to those above the middle reach dams. At the most downstream site (11) only four species (four organisms, 16 mg m^?2) were present. The observed distributional pattern is a classic serial discontinuity in response to hypolimnial stream regulation in a temperate latitude river.     

基于BP神经网络-马尔科夫链模型的隧道围岩位移预测

在隧道工程施工中,围岩位移预测起着很重要的作用。将BP神经网络-马尔科夫链模型引入到隧道围岩位移预测中来,通过对训练样本的学习,利用BP神经网络实现了对位移时间序列的滚动预测,同时得到了实测值与预测值的相对误差;在此基础上利用马尔科夫链对相对误差进行修正,有效地提高了预测结果的精度。并将该模型应用于某公路隧道拱顶下沉位移时序预测中,结果表明该模型具有精度高、科学可靠的特点,为隧道围岩变形的预测提供了新的途径。     

Short communication. Pipelines as a refuge for freshwater snails

In the lower River Murray, Australia, populations of gastropods have declined markedly over the past 40 years. Of the native fauna of about 18 species, only the ancylid Ferrissia petterdi remains common (but in patches), and another five species feature in sporadic local resurgences. Until recently the viviparid Notopala was thought to be extinct. The introduced physid Physa acuta is widespread, but in low numbers. The decline probably is associated with flow regulation, high turbidity and the introduction of common carp. Snail populations have persisted, however, in irrigation pipelines fed from the river, where they periodically cause blockages. This paper reports the discovery of the only known populaion of Notopala hanleyi in a pipeline where the inner wall accumulates microbial and other organic matter, providing high quality food for snails. In the Murray before regulation most of the periphytic biomass was probably microbial, as fluctuating water levels would have maintained littoral communities in a highly productive, early state of succession his postulated that, by stabilizing seasonal water levels, regulation has promoted the production of filamentous green algae, an inferior food source, and so displaced snail populations from the open aquatic environment.     

浙江省水域调查录入系统的设计和应用

浙江省水域调查录入系统将调查数据与电子地图相整合,对分类水域数据进行统计计算,并对输入数据进行合理性和完整性检查,得到调查范围内现有水域的详细数据,实现了水域调查数据输入、计算、统计和查询的数字化管理,提高了工作效率和工作质量,为各地下阶段水域保护规划编制和水域管理工作提供了数据支持。对该系统的设计原则、功能和技术设计等作了介绍。     

基于CT-连续加荷水泥乳化沥青混凝土细观损伤规律研究

利用CT技术对水泥乳化沥青混凝土的细观损伤过程进行实时扫描观测,获得了混凝土试件在连续加荷下的CT图像。通过采用直观分析法、CT数分析法、CT数与损伤变量关系3种方法分析表明,水泥乳化沥青混凝土的破坏过程可分为压密、扩容、裂纹扩展、破坏4个阶段,同时混凝土在受压过程中具有韧性,在极限荷载之前各断面处于压密和微扩容的强化阶段,极限荷载之后混凝土从损伤到破坏发展比较平稳。     

Automated system for removal and pneumatic transport of fly ash from electric precipitator hoppers

A system for removal and pneumatic transport of fly ash is examined, in which air pulses act on batches (pistons) of ash formed in a duct. Studies are made of the effect of several physical parameters on the force required to displace a piston of ash and these serve as a basis for choosing a system for removal and pneumatic transport of ash simultaneously from several hoppers of an electric precipitator. This makes it possible to separate the ash particles according to size without introducing additional components. Formulas are given for calculating the structural and dynamic parameters of this system and measurements of indirect dynamic parameters are used to calculate the input-output characteristics of the system. In order to optimize the system, configurations for summing several ducts into a single transport duct for pneumatic ash transport are proposed. Some variants of dry ash utilization and the advantages of producing of size-separated particles are considered. __________ Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008).     

The flood pulse advantage and the restoration of river-floodplain systems

The ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river-floodplain system, this restoration would provide a large, self-sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed.