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431.
槽上卸料车及矿槽口尘源点具有移动性特征,有效的矿槽槽口密闭以及可靠的随卸料车移动的风管连接装置,是保证除尘良好效果的要点.常用的除尘方法各有其特点和适用条件,应根据作业方式及矿槽结构状况有针对性的采用. 相似文献
432.
公路沿线弃渣场的失稳破坏,不仅容易造成其下方道路和河流的堵塞,而且严重威胁人民的生命和财产安全.快速、准确和批量地评价公路沿线弃渣场危险性就显得十分必要.通过对公路沿线弃渣场进行遥感图像识别、无人机拍摄、现场调查及试验,确定了6个弃渣场危险性影响因子,运用物质点法对实体弃渣场进行了多因素多水平的数值模拟,得出各因子对弃... 相似文献
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Phosphorus (P) pollution in the sediments of seven artificial landscape lakes was studied via fractionation and phosphorus-31 nuclear magnetic resonance ((31)P NMR) spectroscopy. The lake sediments accumulated significant amounts of P from supplementation with reclaimed water and from runoff from the golf course lawns. The differences in total sediment P among lakes were correlated to the varied pollution extent from the lawns. One striking feature of the artificial lake sediments was the insufficiency of NaOH-extracted Al, which plays an important role in avoiding internal P release during anoxia. Another characteristic was the dominance of orthophosphate in the NaOH-EDTA extractants of the sediments, due to the heavy external P pollution. Phytate, considered prevalent in many soils and lake sediments, as well as polyphosphates and phosphonates which have appeared in some natural lake sediments, was not detected. The rank order of present biogenic P species was monoester-P>DNA-P>pyrophosphate>lipid-P. 相似文献
436.
动荷载作用下边坡锚固系统合理设计探讨 总被引:1,自引:0,他引:1
爆破、地震或列车振动等动荷载作用下,边坡锚固系统易产生锚筋松弛、夹具损伤、注浆体拉裂及界面粘结失效等情况,影响其预应力赋存状态、加固效果和耐久性。基于动荷载作用类型和锚固系统动力响应特征分析,提出了动载下不同地层内的锚固段合理结构设计方案和锚筋抗拉安全系数及锁定荷载的建议。动载下自由段(外锚固段)宜设计为全粘结型或增设多级反锚装置,形成岩土自锁锚固,以控制预应力损失和防止锚头或自由段破断造成突发性灾害;在水泥基灌浆体中掺入钢纤维或树脂纤维,可改善锚固体抗裂性能,提高其抗疲劳和抗冲击能力;建议优先采用防腐性能卓越的填充型环氧涂层钢绞线,以提高锚固体在动载破裂时的耐久性。 相似文献
437.
An estimation of the indoor background radiation dose distribution was carried out in dwellings of eleven villages located within and around the uranium mineralization area of Kylleng-Pyndensohiong, Mawthabah in West Khasi Hills District of Meghalaya, India. The ambient indoor gamma radiation level was monitored using Thermo Luminescence Dosimeters (TLDs) while the indoor radon and thoron concentration was measured using twin-cup dosimeters employing Solid State Nuclear Track Detectors (SSNTDs). Results obtained from the study reveals that the local inhabitants of villages located close to the mining site receive higher doses than those inhabitants of villages located at a much farther distance from the mining site. The average total annual effective dose was found to be varying from 1.2 mSv y−1 in the village of Langpa to 3.4 mSv y−1 in the village of Nongbah Jynrin. The data obtained will serve as a reference in documenting changes to environmental radioactivity if mining is to be carried out in the future. 相似文献
438.
基于物质流分析的江苏省区域生态效率评价 总被引:2,自引:0,他引:2
物质流分析被认为是适用于生态效率评价的重要工具和方法之一,但应用于区域生态效率评价的研究尚较少。根据生态效率理论、物质流分析理论与方法,建立了基于物质流账户的3个层面的区域生态效率评价指标:区域直接生态效率、区域总生态效率、整体生态效率。以江苏省为例,全面评价了 1995~2005年江苏省不同层面的生态效率,结果表明:(1)江苏省区域直接生态效率远高于我国同期水平。区域总生态效率和整体生态效率相对较低,分别仅为区域直接生态效率 15%~22%和 7%~8%左右;(2)1995~2005年,区域直接生态效率呈先上升后下降趋势,原因在于物质生产率未有显著提高以及近年来重工业在产业结构中比重的增加;(3)整体生态效率的变化趋势与区域直接生态效率类似,原因主要是近年江苏省对区外物质和资源的进口量显著增加;(4)区域总生态效率则表现为先快速上升后缓慢上升的趋势。在对研究结果及成因进行分析和讨论的基础上,提出了提高区域生态效率的建议. 相似文献
439.
Zhenzi Jing Fangming Jin Nakamichi Yamasaki Hirotaka Maeda Emile H. Ishida 《Journal of environmental management》2009
Hydrothermal solidification of riverbed sediments (silt) has been carried out in a Teflon (PTFE) lined stainless steel hydrothermal apparatus, under saturated steam pressure at 343–473 K for 2–24 h by calcium hydrate introduction. Tobermorite was shown to be the most important strength-producing constituent of the solidified silt. A longer curing time or a higher curing temperature was shown to be favorable to the tobermorite formation, thus promoting strength development; however, overlong curing time (24 h) seemed to affect the strength development negatively. The hardening mechanism consisted of the crystal growth/morphology evolution during the hydrothermal process. The species dissolved from the silt were precipitated first as fine particles, and then some of the particles seemed to build up the rudimental morphology of calcium silicate hydrate (CSH) gel. The CSH gel, with precipitated particles, appeared to cause some reorganization within the matrix, which made the matrix denser and thus gave an initial strength development. Tobermorite, transformed inevitably from the CSH gel, reinforced the matrix with its interlocked structure, and thus further promoted the strength development. 相似文献
440.
R. J. Johnson M. J. Scicchitano 《Journal of Environmental Planning and Management》2009,52(6):833-846
Research on attitudes toward environmental policy making has often overlooked the important role that risks play in forming individual attitudes towards the environment. Similarly, this research often assumes that the factors that affect attitudes are similar across different environmental domains. The purpose of this research is to examine how the factors that affect an individual's willingness to get involved in environmental policy making differ on two environmental issues – nuclear power and drinking water. The study utilises multivariate statistical techniques to explore the relationship that uncertainty, risk, and trust play in an individual's willingness to take action in environmental policy making. The data consist of responses to a national random telephone survey of 403 adults in the United States. The individuals surveyed are more likely to take action on the less avoidable potential threat of nuclear power than they are on drinking water. The respondents believe that the potential harm from nuclear power is greater than that from drinking water. The individuals most likely to take action are those who indicate that they are interested in environmental issues. 相似文献