四种重金属离子对河川沙塘鳢早期发育的毒性影响

以早期发育阶段河川沙塘鳢(包括胚胎和初孵仔鱼)为研究材料,研究Hg2+、Cr6+、Zn2+和Cu2+4种重金属离子对其的毒性影响.结果表明,4种重金属离子对河川沙塘鳢早期发育死亡率和孵化率影响大小依次为Hg2+ ＞Cu2+＞Zn2+ ＞Cr6+,沙塘鳢在神经胚期和出膜仔鱼期的死亡率较高,且在重金属离子处理初期,大多数低...     

基于RF-ELM模型的边坡稳定性预测研究

为实现对边坡稳定性的有效预测,将极限学习机算法与旋转森林算法相结合,并依据影响边坡稳定性的六项重要因素,建立了边坡稳定性预测的RF-ELM预测模型。该模型是以极限学习机算法为基分类器,以旋转森林算法为框架的集成学习模型,利用UCI数据库中三组数据集验证了该集成模型确实提高了ELM的预测性能。将RF-ELM模型应用于边坡稳定性的预测问题中,结合39组工程实例数据进行预测实验,结果表明该模型具有较高的预测精度,可有效的对边坡稳定性进行预测。     

地表夯击载荷作用下埋地管道力学分析

为研究地基强夯作业中夯击载荷对埋地管道力学性能的影响,基于有限元原理建立了夯锤-管道-围土耦合三维模型,分析了夯击过程中管道截面变形及所受冲击力变化规律,研究了管道壁厚、夯击速度、夯锤体积对管道应力、应变及变形的影响规律。结果表明:夯击载荷下的管道所受冲击力为脉冲型,且随时间推移逐渐降低为0,最大冲击力随管道壁厚、夯击速度、夯锤体积增大而增大;管道最大等效应力、高应力范围及最大等效塑性应变随壁厚增加而减小,但随夯击速度或夯锤体积增大而增大;随着夯击速度、夯锤体积增大,管道截面变形率（椭圆度或凹陷率）逐渐增大,但其随壁厚增加而减小。     

武汉市与西安市颗粒物PM_(10)、PM_(2.5)的污染水平分析

利用武汉、西安两市2013年PM10与PM2.5的监测数据,统计分析了武汉市和西安市PM10与PM2.5的污染水平,并比较了两城市的污染水平。根据GB 3095—2012《中华人民共和国环境空气质量标准》规定的二级浓度限值,可知武汉市和西安市PM2.5的污染都非常严重,PM10的污染相对较轻。从整体上说,西安市的污染水平要比武汉市严重,其中西安市PM10中PM2.5约占79%。武汉市和西安市的相关部门都应重视PM10和PM2.5的污染问题。     

Photoacoustic infrared spectroscopy for conducting gas tracer tests and measuring water saturations in landfills

Gas tracer tests can be used to determine gas flow patterns within landfills, quantify volatile contaminant residence time, and measure water within refuse. While gas chromatography (GC) has been traditionally used to analyze gas tracers in refuse, photoacoustic spectroscopy (PAS) might allow real-time measurements with reduced personnel costs and greater mobility and ease of use. Laboratory and field experiments were conducted to evaluate the efficacy of PAS for conducting gas tracer tests in landfills. Two tracer gases, difluoromethane (DFM) and sulfur hexafluoride (SF₆), were measured with a commercial PAS instrument. Relative measurement errors were invariant with tracer concentration but influenced by background gas: errors were 1-3% in landfill gas but 4-5% in air. Two partitioning gas tracer tests were conducted in an aerobic landfill, and limits of detection (LODs) were 3-4 times larger for DFM with PAS versus GC due to temporal changes in background signals. While higher LODs can be compensated by injecting larger tracer mass, changes in background signals increased the uncertainty in measured water saturations by up to 25% over comparable GC methods. PAS has distinct advantages over GC with respect to personnel costs and ease of use, although for field applications GC analyses of select samples are recommended to quantify instrument interferences.     

水解酸化-外循环(EC)厌氧-接触氧化工艺处理啤酒废水

内蒙古自治区某啤酒厂采用水解酸化-外循环(EC)厌氧-接触氧化工艺处理啤酒废水。经过4个月的调试达到满负荷运行,系统稳定可靠,出水水质远优于GB19821-2005《啤酒工业污染物排放标准》。COD、BOD5、NH3-N、TN和TOC的去除率分别达97.5%、98.5%、85%、75%和98.5%。     

Analytical solution for katabatic flow induced by an isolated cold strip

An analytical model for katabatic flow induced by cold strip of finite width in the cross-slope direction but of infinite extent in the downslope direction is presented. The fluid is assumed to have a constant (eddy) viscosity, and the Coriolis force is neglected. A numerical simulation has been used to verify the model, which is shown to revert to the classical Prandtl model if the strip width goes to infinity. The effects of the strip width and slope angle on the katabatic flow are studied. The buoyancy and downslope velocity reach maximum values at the centre of the strip, and spread outwards in the cross-slope direction. The downslope wind maximum weakens for narrow strips and shallow slopes. In contrast to the Prandtl solution, which shows a counter flow above the wind maximum, our model predicts the counter flow to occur outside the strip. The cross-slope variation in the surface forcing induces cross-slope and slope-normal velocities, which are manifested in vortices at the strip edges. Below the wind maximum, the fluid above the cooling surface descends and moves toward the strip edge where it is detrained from the strip region. Replenishment of fluid into the strip region takes place above the wind maximum.     

零价铁还原降解活性染料

在分别通氮气,不通氮气和曝气的情况下,在水溶液中用零价铁还原降解活性染料。实验发现：在不同的氛围中,活性染料的降解程度不同,其降解程度为：暴气〉不通氮气〉通氮气。在不同通氮 和曝气的条件下,活性染料的降解过程中有黄色絮状沉淀生成,经红外光谱鉴定为三聚氯氰的取代产物。     

合理开发坡地资源--以江西省吉水县为例

本文通过对江西省吉水县坡地资源现状、特点的分析,从未利用坡地、利用不充分坡地、利用不合理坡地３方面对吉水县坡地资源进行了潜力分析,并提出了开发利用坡地资源的途径     

LABORATORY TESTS OF EROSION DEPENDENCE ON PROPERTIES OF SOILS AND RAINFALL1

ABSTRACT: One hundred and sixty-two rainfall-induced soil erosion tests were conducted to assist in predicting soil loss and subsequent increase in total suspended solids leaving a highway construction site during a rainfall event. A rainfall simulator and a water flume were constructed for the tests. Soil shear strength, compressive strength, rainfall intensity, and soil bed slope were treated as variables during the experiments. The soil with a higher shear strength resisted soil erosion better than lower strength soils. Soil loss was nearly independent of shear strength at low rainfall intensity but at high intensities, the shear strength was more important in resisting soil loss. Lower soil loss can be expected for cohesive soils if the compressive strength is high.