电流场通信技术在黄河小浪底水文作业的应用

小浪底水库无线遥控悬移质采样器的电流场通信系统主要由水面操作装置、水下控制装置、信号接收和发射天线(电极)以及电源模块等组成.采样器携带4个采样作业仓,水面操作装置采用4位二进制代码对操作按键编码,实现对作业仓的控制.对系统信息的编码方式、发射和接收电路组成结构、软件结构等进行了分析.实际应用表明,在小浪底库区坝前90m水深处,铅鱼携带采样器深入库底淤泥层中通信依然可靠.     

探地雷达在黄河枣树沟水下探测中的应用

在黄河枣树沟对探地雷达进行了水下探测试验,分析了探地雷达探测河道和水下抛石的图谱.结果表明:在均匀水体介质中,探地雷达波形稳定,振幅均匀,频谱范围集中,分辨率高,穿透能力逐渐减弱;在松散的水下抛石介质中,波形绕射明显,强振幅,频率偏高,相位连续,穿透能力好;在水下无抛石的淤泥区或抛石较少区,波形相位出现强吸收,顶部发生...     

河道工程根石智能化探测系统

技术简介：该系统由超声波探测仪、探测系统载体及液压控制系统、控制软件平台等组成，用于探测黄河水下的根石分布情况。主要性能指标：     

黄河下游河道整治工程根石探测技术分析

河道整治工程根石探测是黄河防洪工程管理的重要基础工作,探测技术手段是长期困扰黄河防洪安全的重大难题之一。为了探测坝垛根石状况,治黄工作者进行了长期不懈的努力,解决水下根石探测手段问题,以便及时掌握根石的分布情况与稳定状况,对减少河道整治工程出险、保证防洪安全至关重要。     

坝岸工程水下基础探测技术试验研究及其应用

河道整治工程水下根石探测技术是黄河下游防洪保安中急需解决的技术难题之一，解决根石探测技术问题，及时掌握根石的分布情况，对减少河道整治工程出险、保证防洪安全至关重要。为了解决这一重在难题，从美国引进了“X－STAR全谱扫频式数字水底剖面仪”。通过对大量的现场探测试验结果分析表明，该仪器对探测水下18m以内的根石分布情况十分有效，经过配套完善和二次开发，基本解决了长期以来一直未能解决的黄河下游高含沙洪水条件下穿透淤泥层的根石探测问题。     

水工建筑物隐患探测服务

依托日臻完善的水下探测服务平台。水工建筑物隐患探测方面配备了水下双频识别声呐、水下机器人、探地雷达和高密度电法仪等高精度探测设备。 利用水下双频识别声呐和水下机器人等可对水闸、泵站、船闸等水工建筑物经长期运营后,出现的如裂缝、冲坑、剥蚀等等种种病害进行水下探测。利用探地雷达和高密度电法仪等可进行堤防隐患探测、地下管线探测、地下截渗墙连续性检测、混凝土内钢筋和内部缺陷检测等。     

塔贝拉水电站扩建工程水库深水探测技术研究

在简述深水水下机器人探测和混合气潜水技术的基础上,针对塔贝拉水电站叠梁门安装工程水下探测中水下情况不明、水深大、能见度低等特点,探索了水下机器人初探结合潜水员进行复杂作业的库底深水探测技术,并在叠梁门门槽淤积情况探测、门槽水下锈蚀状况与上方淤积体勘测、百米深水下清障和除锈除垢作业等方面成功应用。研究成果对水库和浅海水下探测工程具有借鉴意义。     

“X—STAR剖面仪”在黄河下游河道整治工程根石探测中的初步应用

黄河下游根石探测技术一直是困扰堤防安全检测的重大难题之一，解决水下根石探测技术问题，及时掌握根石的分布情况，对减少险工出险、保证防洪安全至关重要。几十年来，水F根石状况完全靠人工探摸估计，人工探摸范围小、精度差，难以满足防洪保安全要求。1982年河务部门开始对黄河下游现代化根石探测技术进行研究，1992年曾列入国家科技攻关项［J．但未能彻底攻破这一难题。美国EG＆G公司研制的“X－STAR全谱扫频式数字水底剖面仅”（以下简称“X－STAR剖面仪”）具有良好的水下探测性能，是目前世界上最先进的水下工程基础探测仪器…     

库区水下泥沙探测信号处理技术应用研究

为了获取深水库区泥沙的沉积结构,研究了浅地层剖面仪的线性调频信号处理技术。浅地层剖面仪采用匹配滤波技术提高距离分辨率,通过分析回波的波形、振幅和频率等特性实现对水下地层结构的探测。对线性调频浅地层剖面仪的匹配滤波进行了理论分析和计算机仿真,通过试验获取了有效的地层信息。结果表明:采用的信号处理技术提高了库区水下泥沙探测的分辨率。     

黄河冰凌测报系统研究与设计

黄河冰凌测报系统采用了不同介质电阻特性存在差异的检测原理,以冰层厚度传感器作为信息采集装置,采集空气、冰与水的电阻值,实现对黄河河道冰凌的实时监测。冰层厚度传感器同时采集电压信号与温度信号,电压信号经过分析处理转化为冰层厚度,温度信号则用作辅助判断。通过选择合理的冰层厚度判断算法对采集数据进行分析计算,可得到冰层厚度、水位以及水温等数据信息,并通过GPRS数据通信模块将信息上传至监控中心。应用结果表明:该系统实现了对黄河河道断面冰层厚度的实时监测及冰下水位的在线测报,效果良好,为黄河的防凌汛工作提供了大量的基础数据,适用于黄河防凌抗灾工作。     

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.