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.     

基于数码图像的掌子面岩体结构量化表征方法及工程应用

 以隧道掌子面立体数码摄像为基础,针对隧道开挖、支护两道工序,构建隧道掌子面岩体结构量化表征体系,实现隧道轴向岩体结构及径向岩体结构表征的有效整合。针对具体工程,基于控制点测量、掌子面图像对采集、结构面提取、CAD模型再现四道工序,提出了基于数码摄像的二维掌子面裂隙模型构建方法。以测线法为手段,考虑多条测线的全断面布设方法,以单测线RBI指标为基础,以玫瑰花方位角表征测线位置、玫瑰花半径表征对应方位岩体结构RBI量化值,建立了隧道掌子面岩体结构玫瑰花表征体系,实现了隧道径向岩体结构差异性可视化分析。同时,提出了掌子面结岩体结构综合量化指标(Z-RBI),建立了岩体结构六色分类方法,实现了掌子面岩体结构量化及结构类型划分的可视化集成。最后,采用数理方法,以序列掌子面Z-RBI值为基础,初步构建了隧道轴向岩体完整性预测方法,并进行了工程验证。     

钢筋砼实体结构构件静力荷载试验评定方法的建议

现行相关国家标准对钢筋砼实体结构构件荷载试验的适用对象、试验目标、评定方法等规定存在缺陷,导致检测机构在对荷载试验进行方案设计和试验成果评定时出现混乱。本文通过对国家标准体系的溯源,并借鉴桥梁类标准和国外标准,提出关于现浇钢筋砼实体结构静力荷载试验的适用对象、试验目标和评定方法的建议,供同行业人员参考。     

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.     

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.     

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 effect of industrial activities on the periphyton community at the upper reaches of New Calabar river,Niger delta,Nigeria

Periphyton diversity and biomass were studied for wet and dry seasons (between 1994 and 1995), selected stations at the upper New Calabar river. The periphyton species assemblage were dominated by diatoms species (45 species) except for areas with crude oil tainting on the substrates. The periphyton standing crop and biomass were higher in concentrations for the crude oil impacted environment (Stations 4 and 5). Also the values for the upper limits area (stations 1, 2 and 3) of the river were lower than that obtained for the lower limit area (station 7, 8, 9 and 10). In comparison using student t-test, there were no significant differences in values between seasons for the periphyton standing crop and biomass (P>0.05).The assemblage structure for all the stations, showed that diatoms dominated the population and constituted over 70% of the entire periphyton community except for stations 4 and 5 where the Cyanophyta (blue greens) predominated the periphyton population. The species diversity for the stations were above 2.50 except for Stations 4 and 5 (impacted by crude oil), that had diversity values <2.0.Some of the physicochemical parameters such as pH and the nutrient parameters (NH4+ -N, NO₃ -N, and PO₄⁺³) showed strong co-linearity with periphyton standing crop and biomass.It is concluded that the activities of industries in the upper New Calabar river had impacted on the periphyton community, but such impact was localised and not on the entire stretch of the study area.     

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。     

Fluoridated ground water and its toxic effects on domesticated animals residing in rural tribal areas of Rajasthan,India

Ground water sources (wells and handpumps) for drinking water in 12 villages of tribal areas of Rajasthan (India) were analysed for evidence of fluoride (F) content. These sources revealed mean F concentration in the range of 1.0 to 5.2 ppm. The toxic effects of fluoride (fluoride toxicity) in the form of osteo‐dental fluorosis were observed in the domesticated immature and mature animals, viz., cattle, buffaloes, goats and sheep. The prevalence of dental fluorosis in calves (< 1 year age) was found to be relatively higher than for adult cattle and buffaloes. Cent percent calves (7/7) were revealed with enamel mottling with varying grades at 3.0 ppm F concentration in ground water, whereas cattle (40/40) and buffaloes (14/14) were at 3.2 ppm. The older buffaloes showed brownish black teeth, not creamy yellow as found in calves and cattle. Out of 516 goats and 468 sheep and their 236 lambs, none showed evidence of osteo‐dental fluorosis. The overall prevalence of skeletal fluorosis was 36.2%, with the highest prevalence of 56.0% in cattle and 59.6% in buffaloes at a mean F concentration of 5.2 ppm. At or more 4.0 ppm F concentration only 28 (7.16%) buffalo calves were found to be affected with skeletal fluorosis. Intermittent lameness occurred in most of the higher age group of animals (>7 years age) at 1.8 ppm F or more in the water. None of the fluorotic animals was found to be affected with hypothyroidism. The prevalence and severity of osteo‐dental fluorosis in these animals was progressive with age. Different effects of fluoride toxicity in cattle and buffaloes are also discussed.     

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.     

基于广义逆矩阵理论的杆系结构形态创构方法#br#

广义逆矩阵理论被广泛应用于不稳定结构的形态分析。不稳定结构在荷载作用下,其形状会发生变化直至其势能达到最低,此时的结构处于无弯矩的平衡状态。根据该原理并结合广义逆矩阵理论提出一种适用于杆系结构的形态创构方法。该方法将杆系模型中杆单元进行分组,在每一组中杆单元总长度不变的条件下,建立控制结构形状变化的移形方程。利用广义逆矩阵理论和势能梯度确定使模型势能下降最快的方向,并逐步调整节点位置直至势能达到最低。临时单元和单元组的引入使得该方法可以应用于多种形式结构的形态创构,合理地设置单元组和临时单元可以实现单元长度与单元内力的重新分配进而实现诸多功能。算例分析说明该方法的特性并验证其有效性。     

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.     

A simplified method for the detection of Gallionella in water

This paper discusses a simplified technique for the detection of Gallionella in water. The method uses a smear slide technique and does not require staining or chemical treatment of the sample.     

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。     

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。     

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.