二滩水电站调速器的交叉冗余双微机调节器

介绍了二滩水电站调速器的总体结构,微机调节器的工作原理和应用效果。微机调节器由两套相互独立相互通讯的Quantum系列PLC控制,具有独立的供电电源系统、独立的信号采样(机组频率、导叶开度、有功功率等)通道和独立的输入输出通道。调速器实现双微机调节器及其输入输出通道的交叉冗余,并进行适应式变参数的转速调节和功率调节。着重描述了交叉冗余双微机调节器的容错控制和功率控制方法。     

二滩水电站调速器的交叉冗余双微机调节器

介绍了二滩水电站调速器的总体结构、微机调节器的工作原理和应用效果。微机调节器由2套相互独立、相互通信的Quantum系列可编程逻辑控制器（PLC）控制，每一套PLC具有独立的供电电源系统、独立的信号采样（机组频率、导叶开度、有功功率等）通道和独立的输入输出通道。调速器实现双微机调节器及其输入输出通道的交叉冗余，并进行适应式变参数的转速调节和功率调节。着重描述了交叉冗余双微机调节器的容错控制和功率控制方法。     

洪江水电厂6^#机组国产双微机调速器特点介绍

文章介绍了湖南洪江水力发电厂调速器的总体结构,微机调节器的工作原理和应用效果。微机调节器由两套相互独立相互通讯的Quantum系列PLC控制,具有独立的供电电源系统、独立的信号采样（机组频率、导叶开度、有功功率等）通道和独立的输入输出通道。调速器实现双微机调节器及其输入输出通道的交叉冗余,并进行适应式变参数的转速调节和功率调节。     

水轮机数字调速器系统在乌溪江水电厂的应用

介绍了水轮机数字调速器系统在乌溪江水电厂的应用，主要阐述了PSWT比例数字式冗余可编程微机调速器及BWT步进式可编程微机调速器的改造设计、系统配置、系统性能特点及现场运行情况。     

我国水轮机调速技术创新回顾与学科前景展望

对我国水轮机调速器的技术与产品发展情况进行了全方位介绍,回顾了我国水轮机调速器技术创新历程,从调速器的系统结构模式、微机调节器的构成、电液转换元件的多元化、系统冗余问题、计算机仿真测试功能、友善且内容丰实的人机界面,以及调速器工作油压等级提高等方面进行了总结.结果表明:我国水轮机微机调速器产品的主要技术性能指标一般都已...     

我国水轮机调速技术最新进展与展望

通过分析国内水轮机调速器研制生产厂家的最新调速器技术水平,从调速器的系统结构模式、以工业控制计算机构成的微机调节器、计算机双机冗余问题、友善且内容丰实的人机界面、调速器的计算机仿真测试功能、采用工业标准液压件如比例伺服阀或伺服电机构成的电液转换部件、机械反馈和机械开度限制机构的设置、普遍提高的调速器油压等级等方面进行了总结。结果表明：我国水轮机微机调速器产品的主要技术指标都达到了国家技术标准的要求,部分厂商的的产品技术指标达到了国际先进水平。同时,从“努力贯彻有关水轮机调速器各类标准”等5个方面提出了我国水轮机调速技术的努力目标。     

公伯峡水电站调速器的交叉冗余实现方案

介绍了公伯峡水电站（5×300MW）微机调速器的交叉冗余实现方案、双机切换原则和切换方法，同时指出了双可编程逻辑控制器（PLC）微机调速器在国内大型、巨型水轮发电机组上运行的可行性。     

水轮机微机调速器测频方式与方法的探讨

就微机调速器的测频方式、测频的冗余、数字测频硬件选择、测频分辨率与测频采样周期、PLC调速器测频方法、PCC调速器测频、齿盘测速回路等方面展开分析,希望能对微机调速器的研发、设计、验收、标准制定等相关部门提供参考性的意见和建议.     

CC-Link开放式现场网络在调速器双机通信中的应用

三菱公司CC-Link总线技术具有很高的性价比和可靠性。文中介绍了CC-Link在双微机调速器系统交叉冗余结构中实现交换数据的结果，指出大型（或巨型）机组采用中国自行研制的双可编程微机调速器是可行的。     

龙滩水电站水轮机调速器的特点和问题分析

结合水轮机调速器的发展过程,着重介绍了龙滩水电站水轮机调速器采用T.SLG型功能组合式数字调节器组成的双冗余微机数字控制器+全液控电液随动系统,分析了该调速器的特点和设计及运行中存在的问题。     

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.