给水管道费用函数中a、b、a的确定

本文采用数理统计及工程优化手段,对给水管造价公式中系数a、b、α的确定,提出了较为准确合理的计算方法,经与其它方法比较,具有明显的优越性,为下一步给水系统的技术、经济计算提供了改进建议.     

印度NHPC25a回顾

回顾了印度NHPC25a来的发展历程和所取得的成就。     

Cleuson-Dixence水电站将运1a

ＥＯＳ公司宣布Ｃｌｅｕｓｏｎ -Ｄｉｘｅｎｃｅ水电站将至少停止运行 1ａ时间 ,在此期间对去年 12月份遭受破坏的压力井道进行修复。据ＥＯＳ公司的生产负责人Ｐ .Ｄｅｓｐｏｎｄｓ称 ,调查事故出现的困难意味着该水电站不能像预期的那样于 2 0 0 1年重新投入运行。他解释道 ,ＥＯＳ公司首先将修建一个安全设施通往压力井道受破坏处 ,以便对压力井道的金属进行取样检查。由于焊接缺陷引起主压力管道渗漏 ,装机 12 0 0ＭＷ的这座水电站已于 2 0 0 0年 2～ 8月停止运行 ,预计损失几百万法郎。大迪克桑斯坝的水库向三座电站供水 ,总发电量为 1…     

水库水中叶绿素a测定方法比较

叶绿素a是表征浮游植物生物量的最常用指标之一。本文以潍坊峡山水库的库中水体为对象,通过实验对水利部检测叶绿素a的新老标准从滤膜选择、抽滤操作、细胞破碎方式和提取时间4个方面进行比较和分析。     

浮游植物体内叶绿素a含量测定方法

文中通过系列实验,主要研究并验证了浮游植物叶绿素a含量测定提取过程中过滤藻类的滤膜最佳浸泡时间,以及对校正脱镁叶绿素a的最佳酸化时间,以便得到更为准确的结果。     

大沙河水库叶绿素a影响因子分析

运用回归统计法,研究了大沙河水库叶绿素a与环境因子间的相关性,同时分析了水库的富营养化状况以及叶绿素a的时间分布特征。结果表明:大沙河水库处于富营养化状态,且叶绿素a的季节性差异不显著;叶绿素a与pH值、TP含量呈显著正相关,与透明度呈显著负相关,而与水温、TN、NH4+-N、NO3--N、DO、CODMn和BOD5呈弱相关;大沙河水库为磷限制性水体,TP是浮游植物的生长限制因子。     

大兴安岭地区30a降水变化趋势分析

利用大兴安岭地区1971～2000年地面气象资料分析了全区年和各季的降水变化趋势。     

五华县近31 a雷暴气候特征分析

利用五华国家基本气象站1983—2013年雷暴资料,采用统计分析方法,对近31 a来五华县雷暴日数的年、季、月变化和初终日等特征进行统计,并进行分析,结果表明:五华近31 a的年平均雷暴日数为68.7 d,最多为1983年的103 d,最少为2003年的40 d,年际变化整体呈缓慢减少的趋势。雷暴主要集中在春、夏季,夏季雷暴日数近31 a占比55.57%,春季次之,占比28.89%。五华每个月均有可能出现雷暴,雷暴日数呈单峰型,峰值出现在7—8月,其中汛期4—9月的雷暴日数占比90.18%。初雷日一般出现在3月,终雷日出现在9—10月较多。初雷日对应的侯平均气温是13℃,终雷日则为23℃。     

未来10a黄河流域水资源承载能力评价

通过梳理《黄河流域综合规划(2012—2030年)》和《黄河流域水文设计成果修订报告》中黄河流域水资源总量成果,综合设定12种供需情景,结合黄河流域经济社会发展规划、节水规划等开展2030年流域经济社会需水量预测,并对流域水资源承载能力进行分析。根据水资源承载能力现状与经济社会发展之间的矛盾,有针对性地提出立法、节水、调水、监管等适应性对策,以期为黄河流域生态保护和高质量发展决策提供参考。     

黑龙江省八五三农场近50a降水特征分析

为揭示黑龙江省八五三农场降雨量的变化规律,利用农场近50a(1959-2010年)的月降水量,通过线性趋势分析法、滑动平均法、累积距平法、年际极值比、Mann-Kendall(M-K)突变检验法,分析了农场年降水量和季节降水量的变化趋势及其突变点。研究结果表明:(1)八五三农场的年降水量在研究时段内,总体上呈减少的趋势,且年际变化较显著;对于各季节降水量,夏季下降趋势比较明显,冬季上升趋势显著,春季和秋季基本无趋势变化;(2)M-K突变分析显示,年降水量突变趋势明显,存在1986年和1999年2个突变点;而该区域四季降水突变点较多,其中春季和冬季上升趋势明显,夏季和秋季的下降趋势较明显。     

近50a黄淮海地区降水演变规律

基于ArcGIS平台分析了黄淮海地区1961—2011年生长季降水量和暴雨的时空变化特征,研究指标包括面生长季降水量、生长季降水质心空间位置以及暴雨中心笼罩面积。结果表明:1961—2011年,黄淮海地区生长季降水整体上呈减小趋势,生长季降水量的倾向率为-8.4 mm/10 a;近50 a来,黄淮海地区雨带整体上呈较明显的南移态势,但近10 a雨带呈北抬的特点;强降水事件特性在20世纪80年代发生转变,尤其是近10 a连续暴雨事件影响范围增大。     

大古力大坝建设70a经验总结

世界大坝委员会对大古力大坝建坝70a的情况进行了调查研究，总结出了一些经验和教训，这对许多大型综合利用水资源工程的开发有很好的启示作用。     

株洲市近59 a降水变化规律分析

为了解株洲市年降水变化规律,运用滑动平均值法、距平分析法、Mann-Kendall突变检验、t检验及小波分析等方法,研究株洲市1954—2012年的年降水量变化特征.研究表明:①株洲市在59 a时段内降水量总体呈增加趋势,每10 a增加27.3 mm,降水量在2002年达到最高,在1954年达到最低;②株洲市干旱年为2...     

和田河上游62a径流演变特征分析

科学掌握径流演变特征,对干旱区水资源可持续开发利用及生态建设具有重要意义,本文基于和田河上游1957—2018年62 a长系列天然径流资料,采用累积距平、M ann-Kendall趋势检验和小波分析等方法分析了和田河上游径流年内分配、年际变化、径流趋势、突变性及周期变化等径流演变特征.结果表明:喀拉喀什河和玉龙喀什河年...     

白龙江流域近40a气候变化特征分析

根据甘肃南部白龙江流域气象资料,采用Mann-Kendall突变检测法和小波分析法对白龙江流域近40 a来气候变化特征进行分析,结果表明:①20世纪80年代之前气温变化趋势不明显,80—90年代波动显著,并呈下降趋势,至90年代中后期气温变化呈显著上升趋势;②降水量变化在90年代中期之前趋势不显著,之后呈下降趋势,流域趋于暖干化;③气温变化主要周期上游地区为7 a、27 a和4 a,中下游地区为17 a;④降水变化主要周期上游地区为7 a和4 a,中下游为25 a、9 a和4 a。     

Fouling cake layer in a submerged anaerobic membrane bioreactor treating saline wastewaters: curse or a blessing?

The treatment of inhibitory (saline) wastewaters is known to produce considerable amounts of soluble microbial products (SMPs), and this has been implicated in membrane fouling; the fate of these SMPs was of considerable interest in this work. This study also investigated the contribution of SMPs to membrane fouling of the; (a) cake layer/biofilm layer, (b) the compounds below the biofilm/cake layer and strongly attached to the surface of the membrane, (c) the compounds in the inner pores of the membrane, and (d) the membrane. It was found that the cake/biofilm layer was the main reason for fouling of the membrane. Interestingly, the bacteria attached to the cake/biofilm layer showed higher biodegradation rates compared with the bacteria in suspension. Moreover, the bacteria attached to the cake layer showed higher amounts of attached extracellular polysaccharides (EPS) compared with the bacteria in suspension, possibly due to accumulation of the released EPS from suspended biomass in the cake/biofilm layer. Molecular weight (MW) analysis of the effluent and reactor bulk showed that the cake layer can retain a large fraction of the SMPs in the reactor and prevent them from being released into the effluent. Hence, while cake layers lead to lower fluxes in submerged anaerobic membrane bioreactors (SAMBRS), and hence higher costs, they can improve the quality of the reactor effluent.     

Adsorption study of a commonly used antidepressant drug, fluoxetine hydrochloride, onto a crosslinked β-cyclodextrin-carboxymethylcellulose polymer

A study was carried out by ultraviolet-visible (UV-vis) and Fourier transform infrared (FTIR) spectroscopies to establish the efficiency of adsorption of fluoxetine hydrochloride (FLU), onto a crosslinked β-cyclodextrin-carboxymethylcellulose (β-CD-CMC) polymer. The adsorption was performed in mixtures containing aqueous FLU solution at 20 mg/L and 0.01-0.30 g of the β-CD-CMC polymer, at 25 °C, and atmospheric pressure under stirring. The results have revealed that the adsorption is a rapid process and the polymer possesses a high affinity for FLU with an adsorption capacity of 5.076 mg of FLU/g of polymer. This adsorption may involve the formation of a stable inclusion compound β-CD-CMC/FLU through the penetration of the FLU aromatic ring (A and/or B) into the β-CD cavity, and a physical adsorption with the polymer network. The inclusion compound can be stabilized by the formation of H-bonds between the -CF(3) group of FLU and the 6'-OH group of β-CD, and van der Waals interactions between the FLU aromatic ring and β-CD cavity. The data from a kinetic study have also indicated that the adsorption process was well described by the pseudo-second-order kinetic model, in which the initial adsorption rate and constant were estimated at 1.938 mg/g min and 0.075 g/mg min, respectively. Moreover, the results of adsorption equilibrium fitted the Freundlich isotherm, indicating a multilayer coverage and heterogeneous surface. Together, these results suggest that the adsorption of FLU onto the crosslinked β-CD-CMC polymer could constitute an advantageous technology for removing this commonly used antidepressant drug from wastewater due to the high adsorption capacity of the polymer and non-toxic character of β-CD to humans and environment.     

Capillary effect on the sloshing of a fluid in a rectangular tank submitted to sinusoidal vertical dynamical excitation

Surface tension effects on fluid sloshing in a tank subjected to external excitation has been less studied. This work aims at understanding this phenomenon in order to derive practical solutions to problems faced in several engineering. A tank containing a fluid with a free surface is submitted to gravity and capillary forces and subject to external dynamic excitation. Introduction of vertical sinusoidal dynamical excitation leads to a problem of paramtric oscillations governed by the Mathieu equation. Analysis of the Mathieu equation shows the existence of stable and unstable regions in the stability diagram. Some results induced by harmonic excitations on the fluid sloshing are presented. When the external dynamical excitation amplitude ~ is small, periodic solutions appear in stable regions and when e increases, the fluid behavior is not perfectly periodic and the amplitudes are not regular. Nonlinear effects make the behavior of the fluid complicated and render it almost unpredictable. In stable regions, the solution remains bounded at any time. When changing the perturbation parameter 6, the phase difference increases and also with the increase of the surface tension.