A method for assessing the effect of water quality changes on plumbosolvency using random daytime sampling

The Mann-Whitney U-test is used to demonstrate the impact of phosphate on lead concentrations measured at customer properties. This test is statistically robust and particularly efficient for the type of distributions encountered in lead random daytime sampling. This non-parametric technique is developed to provide a best estimate of the lead reduction that results from a change in plumbosolvency conditions. The method is illustrated with compliance data collected before and after the introduction of phosphate at customer properties in the north west of England. Limitations due to operational factors are highlighted. Using a Monte Carlo simulation of the variability of lead random daytime samples it is shown that the method might be practical when assessing the impact of incremental changes in phosphate concentration on plumbosolvency.     

A strategy for assessing the effects of xenobiotics on fish reproduction

Environmental pollutants, such as industrial and agricultural chemicals, heavy metals, drugs and products with hormonal activity may disrupt reproduction of aquatic wildlife such as fish. Such xenobiotics may cause disruption of the reproductive endocrine system, or they may directly affect gamete development and viability as a result either of their cytotoxicity or by altering the hormonal environment during gamete development. The various possible sites of action are reviewed, and it is suggested that tests for toxicity should isolate the specific component of the reproductive system that is most sensitive to such disruption and that this may be at levels well below that which causes mortality or visible signs of stress. Fish are proposed as the most suitable aquatic organism for such tests.     

基于某水利工程堤防土方填筑施工方法的探讨

针对某水利工程堤防土方填筑施工方法进行了探讨,分别介绍了填筑前的施工准备工作及土料填筑过程中各工序施工方法,并阐述了土方开挖质量控制措施和土方填筑质量控制,对今后同类土方填筑施工具有指导意义。     

The community degradation index: a new method for assessing the deterioration of aquatic habitats

An index method is developed which condenses biological community data into a form which can be readily understood and used by the water resource planner. The concept and mathematical expression of this community degradation index (CDI), as proposed here, is new. A major advantage of the CDI methodology is that no subjective decisions have been made regarding the sensitivity of a particular species of biological assemblage to a pollutant or mix of pollutants. The CDI is applied to fisheries data collected from the Cuyahoga River, Ohio. The close agreement between community degradation as expressed by the index and field observations of the river, provides strong justification for the use of the CDI as a measure of habitat degradation.     

一种基于ANSYS的塔机结构应力检测方法的研究

针对目前传统的塔机结构应力检测指导方法的不足,结合有限元软件ANSYS和实际检测数据,提出一种新的指导布点的方法,经实际检验,证明该方法有很高的可行性.     

一种基于B-Rep的地质模型建立方法

本文以钻孔数据为地质数据来源,分析了地质模型的数据结构及表示方法,设计了一种基于B-Rep数据结构的地质模型建立方法。先以地表勘测点为原始数据点利用分治Delaunay剖分算法建立主TIN,再向下延伸构建多层TIN结构,最后把地层分界面和地质区域边界保存为B-Rep模型。运用该方法开发了基于B/S架构的原型系统并建立了某区域的地质模型。算法结构简单且占用存储空间小,能够在WebGIS上得到应用。     

基于虚拟激励法的框架结构抗震设计方法研究

运用随机振动的虚拟激励法的基本理论,研究了RC框架结构在地震作用下弹性阶段从完好到破坏的反应过程,提出了其各个衡量指标在概率条件下的均值和方差,推导了结构方差的一般计算公式并进行数值分析,从而确定结构在弹性阶段的失效概率,以一座三层框架结构为例进行了说明。     

Development of the phytoplankton community in a pit-lake in relation to water quality changes

An open pit-lake was formed at a Northern Saskatchewan mine site after flooding with lake water in early 1992. Since then, water and phytoplankton samples have been collected regularly from the artificial lake over seven years. The resulting data set provides a unique opportunity to examine the physical and chemical changes in water quality and phytoplankton community over time. Seventeen major variables were examined in a principal component analysis. Axes 1, 2 and 4 are significantly correlated to other three variables, the number of days (since the first sampling after flooding of the pit), water temperature and depth, respectively. Total suspended solid (TSS), dissolved oxygen, total phosphorus (Total-P), arsenic, and iron decreased over time while Mg, Ca, K, Na, total organic carbon and HCO3 increased. Canonical correspondence analysis was used to infer the relationship between water quality variables and phytoplankton community structure, which changed substantially over the survey period. TSS, Total-P and arsenic were considered to be the key factors driving the change in phytoplankton community composition.     

基于霍尔三维结构模型的城市水务业项目融资模式研究

首先,建立BOT、TOT和PPP项目融资模式霍尔三维结构模型,对我国城市水务业外商利用项目融资方式的投资行为进行三个维度的分析;其次,通过案例分析总结出项目融资的三个主要模式BOT、TOT和PPP在我国城市水务业的应用情况;最后,给出BOT、TOT和PPP项目融资模式投资城市水务业的一些建议与意见。     

A method for the measurement of nitrification rates in water

This paper describes a very sensitive method for the evaluation of nitrification rates requiring only short incubation times (3–6 h) and applicable to all aquatic media. It is based on the measurement of dark [¹⁴C]-bicarbonate incorporation inhibited by N-serve, an inhibitor of nitrification. Although this substance has been shown to have a high specificity towards nitrifying bacteria, it does cause an inhibition of bicarbonate incorporation by sulfate-reducing bacteria at the concentration used to inhibit nitrification. Because of this, physico-chemical conditions must be determined when performing measurements of nitrification rates to ensure that sulfate-reducing bacteria are not active. An illustration of this method is provided by measurements in the Scheldt estuary.     

基于分界排序法的流水施工工期优化研究

基于分界排序法的基本思路,将分界排序法与潘特考夫斯基法相结合,对流水施工的施工段排序进行优化后计算其总工期,通过工程实例分析结果表明,该算法能高效快速的对流水施工的施工段顺序进行优化,求出其优化后的工期,非常适合工程技术人员应用。     

A method for calculating effects, on aquatic organisms, of time varying concentrations

A method is presented for calculation of the effects, on aquatic organisms, of exposure to time variable concentrations of toxicants. The technique employs data from classical bioassay tests obtained using constant toxicant concentrations. Calculations of organism mortality as a result of exposure to time varying concentrations are compared to observed data providing a test of the proposed method. The calculation procedure employs available data to assess the duration and extent of carry over effects from individual exposures. Applications and limitations of the proposed method conclude the discussion.     

关于结构分析中能量法若干概念的商榷

对能量法中势能驻值原理的物理概念和数学方法进行整理、归纳和明析,进而推演出该原理的派生原理：势能不变值原理、最小势能原理和Timoshenko能量法,使各基本原理的物理和数学概念协调统一。     

基于FLAC的荷载结构法在衬砌验算中的应用

为了解决传统的荷载结构法在进行隧道衬砌结构验算时存在的不足,提出了将FLAC与其相结合的计算方法,达到了在传统荷载结构法基础上合理考虑锚喷支护、围岩弹性抗力对于结构的有利作用的目的。     

A method for estimating changes in the visibility of land cover

An inventory of resources that includes the contribution made by land cover to the visual landscape can be used in monitoring and assessing the impacts of change in land cover on the visual landscape of an area. A method is presented for assessing the visual resources of the landscape as applied to a case study area in the western part of the proposed Cairngorm National Park in Scotland. The method is based upon measuring the extent of the land from which different land cover types may be visible, on a cell-by-cell basis, using high resolution Digital Elevation Models combined with interpreted land cover data as inputs. The results show a reduction in the overall contribution of scattered, natural woodland to the visual landscape, and an increase in the visual contribution of plantation woodland at the expense of heather moorland. The geographical distribution of the changes in visibility of land cover types is shown and the potential of the method for providing a spatial context for expressing the results of landscape preference modelling is discussed.     

A rapid routine method for quantitative determination of benzo(a)pyrene in water by low-temperature spectrofluorimetry

Some limitations of the analytical method for the determination of polynuclear aromatic hydrocarbons (PAH) in water have led the authors to study the quantitative application of low-temperature spectrofluorimetry as a rapid routine method for the screening of benzo(a)pyrene (BaP) in the aquatic environment. Experiments on the technique of recovery of BaP from distilled water samples utilizing liquid-liquid extraction have given good results; trials concerned with evaluation of any quenching effects on BaP by other PAH and with the applicability to real water samples (river, rain and drinking waters) have shown the promise of this method for screening analysis of environmental waters. The reproducibility of the method is adequate and the required time of total analysis is very short, especially for drinking water samples.     

Detection and estimation of potentially toxic cyanobacteria in raw water at the drinking water treatment plant by in vivo fluorescence method

In vivo fluorescence methods have been accepted as a quick, simple, and useful tool for quantification of phytoplankton organisms. In this paper, we present a case study in which fluorescence methods were employed for the selective detection of potentially toxic cyanobacteria in raw water at the drinking water treatment plant. The occurrence of cyanobacteria in the drinking water reservoir and in raw water was monitored by phycocyanin fluorescence measurements and by standard methods for phytoplankton quantification (cell counts, chlorophyll a). A special attention was paid to the most critical parts of the season -- spring recruitment of cyanobacteria from sediment to water column and autumn bloom collapse. All methods showed similar patterns within the season. Phycocyanin fluorescence was found to be a simple and sensitive indicator of cyanobacteria in water and can serve as a tool that can provide an early warning about the presence of potentially toxic cyanobacterial metabolites in water.     

水下钢筋混凝土结构中钢筋锈蚀的原因及评测

针对水下混凝土中钢筋锈蚀的现状，就钢筋锈蚀原因进行了分析，评定与检测了水下混凝土构件中钢筋的锈蚀状态，对钢筋混凝土构件可做出使用寿命的推测和预见。