水文缆道测深测速信号装置及流速仪悬吊方法

根据水文缆道测深下限适用条件及测流信号在日常流量测验工作中存在的技术问题,提出了缆道测深、测速信号及流速仪悬吊方式的改进方法,对水文缆道流量测验工作及测洪应急措施起到一定作用.     

悬杆流场影响测速的误差分析

近年来随着缆道技术的发展,拉偏悬杆缆道在宽浅河流已急剧增加。由于测深测速范围的扩大,悬杆的长度和直径均在增加,导致水流扰动的加剧,增加了测速误差。ISO3455(国际标准)规定:流速仪检定时的悬杆悬吊方式,通常应和野外使用方式一致。这是较难做到的。但从研究悬杆流场对测速影响的分析入手,并改进悬杆结构,使误差减小到允许的范围,确是可能的。本文试就理论分析与水槽试验资料,论证二者之间的关系,并提出处理方法。供参考。     

拉力式河底信号装置研究

一、课题的提出在我国,水文缆道已成为水文站的一项重要的测流手段。但是,水文缆道测深仍是一个比较困难的问题。导致水文缆道测深困难的主要原因是河底信号常有失灵现象。目前,我国通常采用的是铅鱼附着托板的河底信号装置。它不仅改变了铅鱼原有的流体力学设计要求,而且经常发生河底信号的失灵情况。从而影响了水文缆道的发展和测验精度的提度。     

无线悬杆测验设备的研制

根据多年使用悬杆测验的经验,研制了一款无线悬杆测验设备,研制此设备的目的是使记录人员不必再随悬杆进行水上作业,在岸上即可完成记录工作。无线悬杆测验设备由无线悬杆、无线智能流速记录仪两部分组成,无线悬杆把流速仪接触信号转变为无线电信号发送至空中、无线智能流速记录仪接收到无线电信号后还原为流速仪接触信号,并记录信号数、测速历时,然后计算测点流速。实践证明,设备达到了研制目标。     

LS—250型半皮囊式悬移质泥沙采样器

一、前言 水文缆道在我国水文测验中得到广泛应用,但缆道测沙问题尚未得到完全解决。我们研制的LS—250型采样器,是缆道测深、测速、采水样三位一体的测具。仪器的主要特点如下所述。 1.采用机械型重力开关,利用测深的水面河底信号装置,兼作采样器开关的控制装置。在施测水深的同时,自动采取悬移质泥沙水样,无岸上控制系统。 2.取样舱采用半皮囊结构,利用厚度为     

无传感器测深技术研究

针对现有的悬杆测深技术存在水面信号获取准确性差,水底信号触发装置机械结构复杂或受测流环境干扰明显等问题,对通过模拟量电压识别水面信号和通过电机输出扭矩的变化得到水底信号的无传感器测深技术进行了研究,设计了基于Arduino平台的根据空气和水中电阻率不同获取水面信号的方案。利用ANSYS/LS-DYNA分析了碰撞过程并得出碰撞过程中悬杆加速度变化趋势和碰撞瞬间电机输出扭矩变化趋势,通过PLC监测伺服单元反馈模拟量变化值准确得到水底信号。实践证明,该技术能准确测深,已用于黄委中游水文水资源局各水文站的缆道吊箱测流系统。     

缆道直读测深在宽浅式动荡河流上的应用

缆道在我省已被广为应用,有的测速测深全部自动化,有的因某种原因只能测速而测深始终未解决。因此,为了使缆道既能测速也能测深。本文介绍两种种缆道直读测深的结构式在寛浅式动荡河流上的应用。     

超声波测深技术在溪洛渡枢纽水文监测中的应用

水深测验的精度直接影响到流量测验的准确性。基于超声波测深技术研制出HSH-IL型测深仪,它可采用缆道钢绳和水体作为测量信号传输通道,不需要专门导线;同时采用信号迭加概率分析技术,提高超声波测深精度和可靠性。在金沙江溪洛渡水电站截流施工中,根据水深流急、施工干扰突出的特点,在相应水文监测断面上布设HSH-IL型测深仪施测,满足了流量测验的可靠性和时效性要求,取得了较好的效果。     

水文缆道测深的不确定性

本文依据水文缆道测流实践过程中存在的测深问题进行论证，提出合理化建议。改进测验精度，具有一定的适用性。     

DW2004-8型水文缆道的工作原理及应用

水文缆道,是用来安装水文测验仪器使之到达断面指定位置的一种跨河测验设备。它是借助于横跨断面上方的缆索悬吊测验仪器,可在岸上操纵仪器进行水平和垂直运行的测验设备。由于缆道操作简便、作业安全等优点,近年来水文测验工作在使用缆道测深、测速、取样、测沙等方面得到快速发展。DW2004-8型水文缆道是近年来本省水文测验引用的最先进的自动测控测验装置,主要由水文绞车交流变频无级调速控制、PLC可编程控制系统、智能缆道测距和无线测流等部     

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.