万家寨水电站厂用电系统运行分析

本文介绍了万家寨电站厂用电系统的接线构成,分析了厂用电系统的运行方式及运行可靠性,提出了厂用电系统的危险因素。     

万家寨水电站厂用电系统运行分析

本文介绍了万家寨电站厂用电系统的接线构成，分析了厂用电系统的运行方式及运行可靠性，提出了厂用电系统的危险因素。     

紫坪铺电厂10kV厂用电系统可靠性分析

在紫坪铺电厂500kV系统中采用GIS设备,三角形接线并且只有一回出线,给全厂厂用电10kV系统提出了更高的要求。阐述了紫坪铺电厂厂用电10kV系统接线方式、运行方式及设备特点,重点分析了10kV系统运行的可靠性并指出了其存在的不足之处。     

浅析长洲水电站厂用电系统

针对长洲水电站外江厂用电接线方式分析其优缺点,并结合实际工作中运行人员在倒厂用电时,对运行方式的安排是否合理进行分析,提出如何根据实际情况灵活安排更加科学的运行方式。     

蒲石河抽水蓄能电站厂用电系统接线方式的优化调整

蒲石河抽水蓄能电站厂用电系统分为10 kV系统和400 V系统,分别介绍了其接线构成和运行方式。根据厂用电系统接线特点,提出改进机组机旁动力盘接线方法,同时取消自用电400 V四段母线。对厂用电系统接线的优化调整及改进可以提高特殊情况下机组运行可靠性,减少了检修维护工作量。     

龙滩水电站10kV系统优化改造及运行可靠性分析

简要介绍了龙滩水电站10 kV厂用电系统结构及运行方式,提出10 kV系统一次接线及备自投装置设计上的不足,简述了10 kV系统改造的必要性和具体改造思路,并分析了改造前后厂用电系统运行可靠性。     

老挝会兰庞雅水电站厂用电备自投及闭锁逻辑设计

介绍了老挝会兰庞雅水电站厂用电接线形式和运行方式,分析了本工程厂用电的特殊性和复杂性,通过对备自投配置难点和进线备自投接线难点的分析,提出了具体的解决方案及备自投配置的优化方案,解决了复杂厂用电系统的电气二次设计问题。     

长洲水利枢纽工程厂用电接线设计

介绍了广西长洲水利枢纽工程厂用电设计的一些特点,并结合电站的装机规模、运行方式及枢纽布置等具体情况,对厂用电源的引接、电压等级的选择、厂用电系统接线、厂用电运行方式及厂用电设备选择等作了系统论述.     

下福水利枢纽工程厂用电设计

介绍了桂江下福水利枢纽工程厂用电设计的一些特点,并结合电站的装机规模、运行方式及枢纽布置等具体情况,系统论述了厂用电源的引接、电压等级的选择、厂用电系统接线、运行方式及设备选择。     

小浪底水电站厂用电控制系统设计

厂用电系统是重要组成部分，它的可靠与否直接影响着整个电站的安全运行。本文介绍了小浪底水电站厂用电系统的设计思想和设计方法，并根据厂用电系统的接线方式和运行方式，论述了厂用电系统的控制方式以及备用电源自投自复功能及其特点。     

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。     

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.     

浅谈天湖水电站水轮机运行故障及处理措施

简述天湖水电站投运以来各种故障的表现形式，分析其原因，提出了相应的处理方法及措施，并对合理利用国内外设备提出建议。