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991.
2013年4月20日四川芦山7.0级地震后,四川省宝兴县冷木沟沟道内新增大量崩塌、滑坡物源,在强降雨的诱发下,极易发生泥石流灾害,且沟口直面县城,直接威胁着整个县城的生命、财产安全。利用SCS水文模型,根据冷木沟流域的地貌特征将其划分成17个子流域,在子流域不同的土地利用数据及水文土壤条件下进行产流、汇流计算,最后通过叠加得到冷木沟流域出口断面的汇流过程;对2012年8月18日发生的泥石流汇流过程进行探讨预测,结果显示,本次泥石流的洪峰流量为278m3/s,泥石流总量为20.2×104m3,计算得到的泥石流总量与实际调查结果的相对误差为7.8%;用同一方法预测2013年5月23日冷木沟支沟黑沟的泥石流汇流过程,计算的洪峰流量为38.2 m3/s,与实际监测值的相对误差为4.2%。说明此模型对于冷木沟流域具有适用性,且效果较好,可用于宝兴县冷木沟泥石流的流量预测及泥石流灾害规模预测,将对宝兴县的泥石流防灾减灾工作提供科学指导。 相似文献
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蚯蚓土壤填料生态滤池处理生活污水 总被引:1,自引:0,他引:1
采用二级蚯蚓土壤填料生态滤池对生活污水进行处理,考察其对污水中各类污染物的去除效果。连续运行90d,试验结果表明:滤池运行稳定,对COD、TP、NH3-N、TN和SS的去除效果良好,平均去除率分别为78.7%、93.4%、74.9%、60.4%和87.5%,出水满足GB 1898—2002《城镇污水处理厂污染物排放标准》二级标准。滤池二级串联结构设计系统稳定,改善了出水水质。蚯蚓在试验初期对滤池环境可较好较快的适应,维持了滤池的稳定运行。土壤生态处理技术工艺简单,兼具经济实用和规模灵活的优点,适合推广。 相似文献
995.
Yanlai HAN Michael D. Y. YANG Weixian ZHANG Weile YAN 《Frontiers of Environmental Science & Engineering》2015,9(5):813
Nanoscale iron particles (nZVI) is one of the most important engineered nanomaterials applied to environmental pollution control and abatement. Although a multitude of synthesis approaches have been proposed, a facile method to screen the reactivity of candidate nZVI materials produced using different methods or under varying synthesis conditions has yet been established. In this study, four reaction parameters were adjusted in the preparation of borohydride-reduced nZVI. The reductive properties of the resultant nanoparticles were assayed independently using two model aqueous contaminants, Cu(II) and nitrate. The results confirm that the reductive reactivity of nZVI is most sensitive to the initial concentration of iron precursor, borohydride feed rate, and the loading ratio of borohydride to ferric ion during particle synthesis. Solution mixing speed, in contrast, carries a relative small weight on the reactivity of nZVI. The two probing reactions (i.e., Cu(II) and nitrate reduction) are able to generate consistent and quantitative inference about the mass-normalized surface activity of nZVI. However, the nitrate assay is valid in dilute aqueous solutions only (50 mg·L−1 or lower) due to accelerated deactivation of iron surface at elevated nitrate concentrations. Additional insights including the structural and chemical makeup of nZVI can be garnered from Cu(II) reduction assessments. The reactivity assays investigated in this study can facilitate screening of candidate materials or optimization of nZVI production parameters, which complement some of the more sophisticated but less chemically specific material characterization methods used in the nZVI research. 相似文献
996.
对 JWF150-1500 型和 JWF150-0.0015GHW 型断路器并联电容器进行高压介质损耗试验,发现部分断路器并联电容器随电压升高介损值变化明显,存在离子性缺陷。通过数据和理论分析,解释了断路器并联电容器介质损耗随电压变化的原因及离子性缺陷对断路器并联电容器影响,并提出有效解决措施。结果表明:例行试验与投运前试验时 10 kV 下 tanδ 测量值偏差较大,且高压介损随电压变化下降明显的断路器并联电容器,可认定存在离子性缺陷。 相似文献
997.
气相色谱法、频响法及短路阻抗法是测试变压器绕组是否变形的重要手段,但单一的试验方法和试验数据对判断绕组变形存在一定的局限性。结合现场实际,提出应用色谱法进行检测后,再结合频响法和短路阻抗法进行分析的综合方法。应用结果表明:变压器绕组变形的综合分析方法能够有效、准确判断绕组的状态。 相似文献
998.
Sediment-laden turbulent flows are commonly encountered in natural and engineered environments. It is well known that turbulence generates fluctuations to the particle motion, resulting in modulation of the particle settling velocity. A novel stochastic particle tracking model is developed to predict the particle settling out and deposition from a sediment-laden jet. Particle velocity fluctuations in the jet flow are modelled from a Lagrangian velocity autocorrelation function that incorporates the physical mechanism leading to a reduction of settling velocity. The model is first applied to study the settling velocity modulation in a homogeneous turbulence field. Consistent with basic experiments using grid-generated turbulence and computational fluid dynamics (CFD) calculations, the model predicts that the apparent settling velocity can be reduced by as much as 30 % of the stillwater settling velocity. Using analytical solution for the jet mean flow and semi-empirical RMS turbulent velocity fluctuation and dissipation rate profiles derived from CFD predictions, model predictions of the sediment deposition and cross-sectional concentration profiles of horizontal sediment-laden jets are in excellent agreement with data. Unlike CFD calculations of sediment fall out and deposition from a jet flow, the present method does not require any a priori adjustment of particle settling velocity. 相似文献
999.
Precipitation is of great importance to agriculture, environment and ecosystem as a regular precipitation pattern is usually vital to healthy plants; excessive or insufficient rainfall can be harmful. Periodic patterns of precipitation can be studied based on regularly observed data over time. Since regularly observed precipitation data are generally skewed with many zeros, two common analysis approaches have been proposed recently. One approach investigates precipitation using a two-part model where the occurrence and positive amount of precipitation are analyzed separately (Piantadosi et al. in Environ Model Assess 14:431–438, 2009), whereas the other approach handles occurrence and amount simultaneously using a Tweedie’s compound Poisson model for independent observations (Hasan and Dunn in Int J Climatol 32:1006–1017, 2012). The former approach fails to maintain the regular temporal structure of serially observed precipitation, whereas the latter approach ignores serial dependence. As there is generally substantial serial correlation in the observed sequence of precipitation data over time, we introduce a compound Poisson state-space model with serially correlated random effects for daily precipitation data. This approach characterizes both occurrence and amount of precipitation simultaneously while accounting for the corresponding serial correlation. Our main results depend only on the first- and second-moment assumptions of unobserved random effects. We illustrate our method with the analysis of the daily precipitation data recorded at Mount Washington, NH, USA. 相似文献
1000.
敌百虫对中国林蛙蝌蚪生长发育的毒性效应 总被引:1,自引:0,他引:1
为评价水域环境中敌百虫(trichlorfon)污染对两栖类幼体的急性毒性,将中国林蛙(Rana chensinensis)28~29期(Gos-ner)蝌蚪分别暴露于10~30 mg· L-1敌百虫5个不同浓度的水体中,分别在24、48、72和96 h统计蝌蚪的死亡率,计算半致死浓度(LC50).结果显示,暴露24、48、72和96 h,敌百虫对蝌蚪的LC50分别为14250±3.23、49.19±128、25.68±2.04、1555±1.93 mg·L-1,安全浓度(SC)为156±0.19 mg· L-1.蝌蚪中毒后尾部多呈弯曲状,仰翻,外观浮肿.对死亡蝌蚪的解剖表明,其鳃腔内充水,内鳃萎缩,肝脏、肠管和肾脏呈灰白色.另外,将28~29期蝌蚪分别暴露于0.2 ~ 2.0 mg·L-1敌百虫4个不同浓度的水体中进行慢性暴露实验,检测蝌蚪暴露28和42 d时的体重和体长以及75%个体变态所需的时间.结果表明,蝌蚪在低剂量敌百虫水体中持续暴露,其生长发育受到明显抑制,并可导致蝌蚪身体扭曲、尾部强直性弯曲等畸型发生,蝌蚪的死亡率显著增高,作用强度呈现剂量和时间的累积效应.慢性暴露实验证明SC以下的敌百虫水体仍威胁着蝌蚪的生存. 相似文献