污水管网模拟模型节点平均流量的估算方法

建立排水管网模拟模型是城市排水实现科学化管理的一个重要手段。作为污水管网建模的基础部分,研究了污水管网节点平均流量估算的间接求解方法,即根据用水量推求污水量。该法包括污水排放系数的确定和节点服务区域属性值的计算两部分。污水排放系数根据生活用水量结构确定;在城市排水管网GIS平台上可以估算节点服务区域属性,如人口、面积(平面面积和建筑面积)等。     

截流式合流制排水管网设计新思路

提出了一种以溢流井为分界线,将截流式合流制排水管网分解为一系列小型完全合流制排水管网的设计新思路,并以管网关联矩阵和节点连接特性矩阵为基础,以节点平衡原理和节点递归算法为核心,实现完全合流制排水管网的流量计算和水力计算.该方法能有效减小管网计算模型的规模,降低程序设计难度,提高程序的实用性.     

基于隶属度的污水管网设计流量矩阵计算模型研究

运用图论的树形结构理论分析污水管网的拓扑结构,提出用隶属度表示街区或集中用水点与管段的对应关系,并给出隶属度矩阵的概念和求解方法。基于隶属度建立矩阵计算模型,用Matlab编程实现设计流量的自动求解。结合实例,验证了模型求解大型污水管网设计流量的可行性和快捷性。     

基于拓扑关系构建的城市污水管网优化设计

在城市污水管网优化设计过程中,提出利用数组记录关联管段及其编号的方法来构建污水管网的拓扑关系;根据各关联管段及其节点的参数比较确定下游管段的初始控制参数,并以各管段的平均坡度作为控制依据进行污水管网的优化设计.采用VB语言编制了污水管网优化设计程序,并用广东某城镇的污水管网对程序进行了验证.     

供水管网中节点流量随机性的影响分析

供水管网中节点流量是一个随机变量。首先利用网络矩阵的理论求出了节点压力和管段流量对节点流量的偏导数矩阵。基于正态分布研究了由于节点流量的随机性所导致的节点压力和管段流量的随机性问题,利用概率论的理论求出了节点压力和管段流量的概率密度分布、均值、方差及置信区间。最后以实例说明了节点流量的随机性对管段流量和节点压力的影响。结果表明,节点流量的随机性变化对管网中的节点压力和管段流量有显著影响。     

北京市小城镇排水管网规划设计探讨

排水管网是小城镇基础设施的一个重要组成部分，在促进经济建设的发展、保护城镇环境免受污染、保障人民健康与正常生活方面起着至关重要的作用。根据北京市小城镇的实际情况，从小城镇排水规划原则、排水体制选择、污水管道设计流量计算、管线布置及水力计算等方面归纳了小城镇排水管网规划设计的特点及应注意的问题，提出了北京市小城镇排水管网合理规划设计的建议。     

Excel规划求解的环状给水管网平差

Excel规划求解环状给水管网平差,以管段流量为变量,各环闭合差的绝对值之和取得最小值为目标函数进行规划求解,通过设置节点连续性方程为约束条件,节点流量无需手工计算而自动平衡.采用Excel的公式与函数成批运算,便于选择管径取得经济流速,是一种环状给水管网优化设计和水力计算的新方法.同等环状给水管网的算例计算表明,与Hardy.Cross法相比,规划求解法过程简单快捷,求解精度高,4个环闭合差的绝对值之和为2.64×10-5(kPa)     

三峡库区小城镇污水管网设计和实施中的问题探讨

就三峡库区污水管网设计及配合施工工作,总结了三峡库区小城镇污水管网设计的特殊性、施工建设难点以及充分利用特殊的地形地貌采取的技术措施,对快速发展的新城镇管网建设、老城区管网改造进行探讨.     

一般流出型环状管网的水力计算

目前所有的管网计算方法只限于求解节点流出型管网的问题，而不能用于管路流出型管网。本文提出节点水头法计算管路流出型环状管网的方法，并编制了计算程序，经计算实例证明方法正确合理，管路流出型比节点流出型更加接近实际地管网流出状态，因此，在运行管网的控制管理模拟计算时要比节点流出型管网优越。     

浅述沿海老城区污水管网系统的规划与设计

结合编制某市市区污水管网系统专业规划 ,分析和研究了东南沿海地区类似老城区排水管网系统规划与设计需要注意的几个问题。主要包括排水体制的选择 ,污水水量预测 ,系统管网布置与已建排水管道的利用 ,泵站规模计算 ,并对今后进行类似规划需要改进的方面提出了建议     

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.