Detection and variation of microcystin contents of Microcystis blooms in eutrophic Lalla Takerkoust Lake, Morocco

Hepatotoxic microcystins produced by cyanobacteria represent a significant health hazard. In Morocco, although blooms of cyanobacteria are known to occur frequently in some water‐bodies, studies on toxicology and toxinology of these potentially harmful algae have been scarcely developed. This paper presents results of the detection of Microcystin‐LR (Mcyst‐LR) and other microcystin variants and their content variations from Microcystis natural blooms and from the isolated strain culture. During the cyanobacteria dynamic study, 11 bloom samples were collected between 1994 and 2000 and were assessed for toxicity and quantification of microcystins, respectively, by mice bioassay and the enzyme‐linked immunosorbent assay. The bloom samples exhibit a high toxicity with mice intraperitoneal injection (i.p.) LD₅₀ < 100 mg/kg and the total microcystin contents were 496–8800 μg/g dry weight with a coefficient of variation of less than 11%. However, the Microcystis isolated strain cultured on Z8 medium under controlled laboratory conditions produced an amount of 707 μg/g dry weight, its toxicity level corresponds to a LD₅₀ i.p mice of 31 mg/kg. The detection of microcystin variants and the identification of Mcyst‐LR from some natural bloom samples collected in 1994, 1996 and 1999 have been carried out by high performance liquid chromatography with a photodiode array detector, which confirmed the identification from each bloom sample of at least four microcystin variants, among which the Mcyst‐LR one represents a relative proportion of 30% to 62% of total microcystin contents. Only one variant of microcystin that was not a Mcyst‐LR has been detected from a Microcystis isolated strain. The toxicity level of the material depended either on the amount of microcystins or the number of these variants and their proportion. According to these results, the survey of cyanobacteria and cyanotoxins monitoring in water used for human consumption is needed to avoid any sanitary risk.     

Ultrasonic flaw detection of joints of precast-monolithic penstocks of the Zagorsk pumped-storage station

Conclusion The investigations permit recommending the ultrasonic method for inspection and flaw detection of joints of precast-monolithic penstocks of PSS. This nondestructive inspection method has a sufficient reliability for field conditions. Ultrasonic flaw detection of the joints of precast-monolithic penstocks was adopted as the main and most large-scale type of field inspection at the construction site of the Zagorsk PSS.Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 5, pp. 24–27, May, 1988.     

Dynamics of the formation of an ice prism on reservoir slopes of a pumped-storage station

Conclusion It is recommended to use the given relationships when designing dikes of reservoirs operated under conditions similar to the conditions of the Kiev PSS reservoir [3–5].To refine a number of the foregoing assumptions and proposed relationships, it is expedient to continue hydrophysical investigations of the dynamics of formation of the structure and mechanical strength of the layered ice prism on the slopes of the dike of the Kiev PSS reservoir.The materials presented and also the data of on-site observations can serve as grounds for developing as a first approximation a method of designing revetments of dike slopes of PSS reservoirs for the effect of ice.Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 3, pp. 14–16, March, 1982.     

The occurrence of microcystin-LR in Lake Chivero, Zimbabwe

Lake Chivero is a eutrophic reservoir, initially constructed to supply drinking water to the City of Harare, Zimbabwe. Blooms of blue‐green algae have been a problem in the lake for many years and concern has been expressed about the toxins produced by Microcystis spp. The concentrations of the toxin, microcystin‐LR, produced in cultures of Microcystis aeruginosa from Lake Chivero, were investigated from March–April 2003. Microcystin‐LR was found in algal cells cultured from the lake water in concentrations ranging between 18.02 and 22.48 µg L^?1, with a mean concentration of 19.86 µg L^?1. These concentrations are the highest recorded to date for the lake, raising concerns about the possible effects of the toxin on the health of people who are drinking the water. Based on these study results, there is a need to control eutrophication, reducing algal blooms in order to prevent their potentially detrimental effects from blue‐green algal toxins produced under such conditions.     

Use of pumped-storage electric power stations with underground downstream basins

Conclusions An essential virtue of a PSS with an underground downstram basin consists in the possibility of constructing it in practically any region, since its location is not related with topographic conditions. The deep founding of the basins and power house of the PSS permit locating it under favorable geologic conditions in the greater part of the territory of our country. The construction of such PSS can be based on a standard design if the same capacities, heads, and daily energy production of a series of PSS of the given type are used. The combined construction of SPS, APS, and PSS permits creating a power system with an optimal structure of the generating capacities with a substantial decrease of expenditures for industrial facilities, housing, etc. It is possible to locate PSS near maximum load centers which increases the stability of the power system and reliability of the electrical supply and quality of electric energy delivered to consumers with a decrease in expenditures for the construction of transmission lines. The location of PSS on seacoasts and near lakes opens prospects for the effective use of these bodies of water as the upstream basins of PSS. Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 2, pp. 29–33, February, 1973.     

大规模降雨监测数据异常识别方法

为实现大规模降雨监测数据的异常识别和快速处理,基于Hampel法、格拉布斯准则、周边测站分析法和雷达辅助校验等方法,建立了递进式异常站点筛查体系,通过K-d tree(K-dimension tree)高级数据结构和并行计算方法提高计算效率,并以福建省5234个具有雨量监测功能的地面站2015—2021年雨量数据进行了验证,结果表明福建省地面站雨量监测数据质量逐年提升;各类测站中,雨量站异常站点占全部异常站点的比例最高,各类异常站点在全省相应类型站点中,雨量站异常站点的占比也最高;雷达辅助校验能够有效解决在雨区与非雨区边界、雨强差异较大的雨区边界的正常站点易被误判为异常值的问题,校验前异常识别准确率为90%左右,校验后准确率提高为95%左右。通过K-d tree和并行计算,全省测站完成一次异常识别需约5~8 min,为大规模降雨监测数据异常识别、充分利用雨量监测站有效信息提供可靠的方法。     

龙滩水电站PSS试验与应用

通过对龙滩水电站7号机组的PSS现场试验和参数选择,确定了PSS的运行参数,检验了PSS性能,为实际应用提供了理论依据.为了消除安全臆患,根据7号机组运行情况,对7号机组PSS进行技改,提高了机组运行可靠性.     

Efficiency of using the upper reservoir of the Zagorsk pumped-storage station

Conclusions  

Role and significance of pumped-storage stations in the power industry

Conclusions  

机组PSS参数整定及其抑制系统低频振荡的效果

在对云南大朝山水电厂机组的ABB公司UNITROL 5000数字式励磁调节器的电力系统稳定器(PSS)、漫湾电厂机组的南瑞集团SJ-800型励磁调节器的电力系统稳定器(PSS)进行初步理论计算研究的基础上,通过对其励磁系统进行在线无补偿频率特性的测量,分别提出了一组PSS参数,并详细进行了PSS电压阶跃响应试验、原动机功率突然改变时的反调试验、系统扰动试验,结果表明,这两组参数可以有效地阻尼系统低频振荡,具有良好的鲁棒性。大朝山电厂、漫湾电厂发电机组PSS投入运行后,对保证云南电网乃至南方电网安全稳定运行起到了重要作用。     

电力系统稳定器在喜河水电站的应用研究

针对喜河水电站水轮发电机励磁控制系统中的励磁调节器产生负阻尼转矩可能导致电力系统低频振荡的问题,采用电力系统稳定器(PSS)以抑制低频振荡。建立了喜河水电站3号水轮机组的PSS模型,通过模型参数测试结果与仿真结果的比较,验证了参数的准确性,并进行了现场试验研究。结果表明,该机组PSS能够有效地抑制系统低频振荡,对本机振荡有良好的正阻尼作用。     

二滩水电站PSS对抑制系统低频振荡的作用

二滩电站首台机组发电时通过长６２２ｋｍ的一回５００ＫＶ的输电线路送电，此时等值于１同组与无穷大电力系统相连，呈弱联系，根据电力系统稳定性的要求，其励在系统联合会了ＰＳＳ系统。设ＰＳＳ的目的是当系统出现扰动时为发电机转子转速摇摆提供正阻尼，以增强与电力系统的联系，ＰＳＳ能在系统突然施加一个干扰，如线路退出运行或系统联系较弱和稳定裕度不够时，起到重要作用。二滩机组ＰＳＳ增益设定是根据现场试验进行调整，     

基于年径流序列的五种趋势检测方法性能对比

趋势变化是水循环过程的重要变化特性之一,准确识别水文要素变化趋势是认识变化环境下水循环演变规律的基本内容。由于当前趋势检测方法众多,且受多种因素影响,趋势检测结果存在较大的不确定性,很难判断结果的准确性。为提高对水文要素趋势分析方法的认识,研究基于3组变化特征不同且已知成分的人工生成序列,综合对比分析了5种常用趋势检测方法(累积距平法、线性回归法、MK法、EMD法和DWT法)的准确性和可靠性,并以3组不同实测年径流序列为例,进一步评价了不同方法在水文时间序列趋势检测中的性能差异。实例分析表明,累积距平法可用于水文时间序列趋势的初步分析,不宜作为判断依据。MK法与线性回归法所得结果差异不大,对趋势单调且无明显季节或周期变化的水文时间序列具有较高识别精度,适用于演变特征相对简单且趋势变化明显的年径流序列的趋势检测。EMD和DWT法可以准确地识别并分离出序列自身含有的不同尺度波动成分,从而避免序列周期、非线性变化等特征对趋势检测结果的影响,性能相对更优,对于演变机理及变化特征复杂的年径流序列的趋势分析,应优先考虑DWT法,其次为EMD法。研究成果可为水文要素的趋势分析及其方法选择提供参考。     

电力系统稳定器在喜河水电站的应用研究

针对喜河水电站水轮发电机励磁控制系统中的励磁调节器产生负阻尼转矩可能导致电力系统低频振荡的问题,采用电力系统稳定器（PSS）以抑制低频振荡。建立了喜河水电站3号水轮机组的PSS模型,通过模型参数测试结果与仿真结果的比较,验证了参数的准确性,并进行了现场试验研究。结果表明,该机组PSS能够有效地抑制系统低频振荡,对本机振荡有良好的正阻尼作用。     

Methodology for Estimating Streamflow by Water Balance and Rating Curve Methods Based on Logistic Regression

Both water balance (WB) and rating curve (RC) are methods for estimating streamflow. The first is mostly used to estimate reservoir outflows, while the second is usually adopted in hydrometeorological network streamflow gauges. While WB uses hourly collected data, the RC estimates streamflow using current water level and extrapolation techniques. The objective of this study was to analyze variations in the reservoir’s hourly outflow at Queimado Hydroelectric Power Plant (HPP Queimado) and to propose a method to evaluate whether the estimate of the daily outflows, obtained by the WB method, is similar to the flow values obtained at a conventional station. The logistic regression (LR) model was used because it is a method that adopts binary, categorically dependent variables to identify the event of interest. The results showed that the values of streamflow, obtained from an average of two daily readings, were a good representation of the flows in the region. The LR was able to identify atypical data, especially in the rainy season. This means that data consistency analysis can be faster and safer, when adequately employed and considering the proposed conditions, contributing to both management policies and the management of water resources.

     

基于单纯形-模拟退火算法的多阻尼控制器协调设计

提出一种基于单纯形-模拟退火算法的电力系统稳定器(PSS)参数优化方法。该方法以弱阻尼振荡模式构建目标函数,将单纯形法搜寻机理嵌入到模拟退火算法的基本步骤中,综合了模拟退火算法全局搜索能力强及单纯形算法局部收敛速度快的优点。四机典型系统上的特征根分析表明,该方法是一种有效的阻尼控制器优化方法,所得的参数对系统运行方式的变化具有良好的鲁棒性。     

Measurement of flow velocity profiles in tank structures using the prototype device OCM Pro LR

Generally, studies investigating the treatment efficiency of tank structures for storm water or waste water treatment observe pollutant flows in connection with conditions of hydraulic loading. Further investigations evaluate internal processes in tank structures using computational fluid dynamic (CFD) modelling or lab scale tests. As flow paths inside of tank structures have a considerable influence on the treatment efficiency, flow velocity profile (FVP) measurements can provide a possibility to calibrate CFD models and contribute to a better understanding of pollutant transport processes in these structures. This study focuses on tests carried out with the prototype FVP measurement device OCM Pro LR by NIVUS in a sedimentation tank with combined sewer overflow (CSO) situated in Petange, Luxembourg. The OCM Pro LR measurement system analyses the echo of ultrasonic signals of different flow depths to get a detailed FVP. A comparison of flow velocity measured by OCM Pro LR with a vane measurement showed good conformity. The FVPs measured by OCM Pro LR point out shortcut flows within the tank structure during CSO events, which could cause a reduction of the cleaning efficiency of the structure. The results prove the applicability of FVP measurements in large-scale structures.     

超声引发聚苯乙烯磺酸钠的降解

用低功率、高频率的超声波对水溶液中的聚苯乙烯磺酸钠进行降解,研究溶液浓度、pH值等对降解反应的影响,用凝胶色谱法测定降解产物的分子量及其分布,用红外光谱法以及紫外分光光度法表征了降解过程中的产物结构变化,用2,2-二苯基-1-苦肼基(DPPH)对降解过程中产生的自由基进行捕捉,证实降解反应经历了自由基历程。     

水体中溶解性微囊藻毒素与藻类细胞内微囊藻毒素的关系研究

应用高效液相色谱,对北方某水库水体中溶解性微囊藻毒素(extracellular microcystin,EMCs)和藻类细胞内微囊藻毒素(intracellular microcystin,IMCs)的3种异构体(LR、YR、RR)进行了为期1年的监测,研究了EMCs和IMCs随时间的变化规律及相互关系。结果表明：EMC-RR和IMC-RR的全年变化规律非常一致,在9月初之前其含量比较低,随后迅速上升并在10—11月份同时出现峰值;EMC-LR、IMC-LR、EMC-YR和IMC-YR全年出现多个起伏,且存在明显的差异,其峰值出现时间也不一样,EMC-LR和EMC-YR峰值出现在8—9月,而IMCLR与IMC-YR的峰值则出现在9月份中下旬。IMCLR和IMCRR是藻类细胞内主要毒素,但是2种异构体所占总的细胞内毒素的比值并不是固定的,5—12月份其比值不断下降。