五元系数法-改进熵权法在水质评价中的应用

为了使水质监测值和水体划类标准值之间关系更紧密,利用五元联系数方法建立了各水质评价指标与评价标准的五元联系数;同时在传统熵权计算的基础上,采用秩比法设定偏好校正系数,得到改进的熵权重;最后将五元联系数ui和改进的熵权重WRi相结合获得五元综合联系度,据此对水质进行评价,这是一种主客观结合的、符合实际情况的水质评价新方法。以贵州贵阳市河流断面监测数据为例,评定样本点所在河段水质等级,分析了该河流水质变化趋势,验证了五元系数法-改进熵权法水质评价方法的实用性。     

八五九灌区水生态环境分析与评价

针对灌区的特殊性及在生态环境中的重要作用,对其水生态环境进行分析与评价,建立了地表水和地下水的水质安全模糊综合评价模型,对八五九灌区的水质安全进行评价。结果表明:1该研究区地表水质为Ⅱ类,地表水的主要污染因子是五日生化需氧量和氨氮;22号水样地下水主要水质为Ⅱ类,其主要超标因子是氟化物和氯化物。采用模糊综合评价方法进行灌区水质安全评价是合理有效的。     

广州市沿海地区浅层地下水质量评价

基于研究区18个地下水采样点近2 a的监测结果,采用单指标综合评价法和主成分分析法对研究区地下水质量进行了评价,并探讨了水质变化的影响因素.结果表明:研究区浅层地下水质量总体较差,但近两年有变好的趋势.研究区超标指标主要有氨氮、锰、耗氧量、氯化物、总硬度、溶解性总固体、铁、pH值和硫酸盐等9项,超标率在23.6％～77...     

北京西南部山前平原区地下水水质评价及其影响因素

为研究北京西南部山前平原区地下水水质状况和主要影响因素,本文以北京市丰台区为例,分别采用单因子指数评价法和模糊综合评价法对17口监测井的水质状况进行评价,并分析了空间分布规律。结果表明:丰台区地下水水质Ⅲ级以上占比为53%,未达标水质占比为47%。污染指标以总硬度、溶解性总固体、硝酸盐氮等为主,其中总硬度为水质超标最严重的指标。在空间分布上,西北山区地下水水质优于东南平原区。从自然和人为因素分析对地下水水质的影响,西北山区主要受地质条件及农业污染等影响,东南平原区主要受区域降水蒸发、工业和生活污染、地下水开采等影响。     

三门峡市地下水水质特征及机理初探

采用模糊数学综合评判法对三门峡地下水水质进行了评价,结果表明：主要超标因子为Fe^2＋、总硬度、NO3ˉ。通过对水文地质条件的分析认为,Fe^2＋超标主要是自然因素引起的,而总硬度、NO3ˉ超标主要是人类活动引起的,并提出了相应的改善措施。     

聊城市地下水水质特征及评价方法选择研究

为准确反映聊城市地下水现状,本文以聊城市典型监测点监测数据为依据,运用综合评价法和模糊综合评价法对监测点水质进行评价,并探讨2种水质评价方法的评价效果。结果表明:聊城市浅层地下水和深层地下水水质以Ⅲ类和Ⅳ类水为主,主要超标指标为总硬度和溶解性总固体;各超标指标之间具有一定相关关系;综合评价法评价结果数值偏大,并且缺失Ⅲ类水;模糊综合评价法更适合聊城市地下水水质评价。     

北京市朝阳区地下水水质调查和评价

采用单项组分评价法和综合评价法对北京市朝阳区100个地下水监测井水质现状进行了调查评价。结果表明:地下水单项组分评价中超标较严重的有铁、锰、氨氮、总硬度。综合评价中水质良好、优良的占56%,水质较差的占42.7%,水质总体状况不容乐观。     

沙溪河水质评价与趋势分析

选取闽江支流沙溪河的3个断面1993—2000年主要水质监测资料,采用单因子污染指数法、综合污染指数法、秩相关系数法对沙溪河水质状况进行评价,并分析了其变化趋势。结果表明:沙溪河污染程度较轻,水质状况一般,主要污染物为NH3-N,枯水期各污染因子浓度变化较大,虽然基本能满足Ⅲ类水质要求,但是水质无明显改善趋势。     

某水源地地下水中石油类有机污染特征

利用GIS空间分析平台的反距离权重法插值获取中国北方某典型岩溶水源地2008—2010年地下水中石油类有机污染物浓度空间分布,基于SPSS软件的Spearman秩相关系数法获取地下水中石油类有机污染物的变化趋势,在此基础上叠加地下水水动力因素,并结合2016年地下水典型有机污染物空间分布状况获取地下水有机污染风险特征,结果表明:研究区59.04%的区域地下水水质趋于好转,29.55%的区域水质呈恶化趋势,水质恶化区集中在石化公司新区和旧区的下游;地下水中总挥发性有机物浓度与石化公司新旧区、排污渠、排污渗坑及导水系数的空间分布密切相关;石化公司新区污染源及其下游(Ⅰ-Ⅰ')典型石油有机污染物检出率高且浓度大,需加强防漏及采取污染防治措施;石化公司旧区下游(Ⅱ-Ⅱ')有机污染风险高且呈恶化趋势,需要采取污染防治措施。     

改进权重集对分析法在准东水质评价中的应用

根据准东水源地2011年9月地下水水质监测资料,以对地下水水质影响较大的总硬度、溶解性总固体、硫酸盐和氯化物为评价项目,采用基于熵权与超标倍数赋权的改进权重集对分析法对准东水源地进行了水质评价。结果表明:改进权重集对分析法在计算时考虑了各评价项目的重要性,使计算结果更接近客观实际;准东水源地大部分水质为Ⅰ级和Ⅱ级,水质总体情况较好,基本未受到污染。     

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.