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141.
142.
《工程测量学》双语教学的实践与评估 总被引:2,自引:0,他引:2
介绍工程测量学双语教学的具体实践过程,对工程测量学双语教学模式及教学效果进行了问卷调查、评估与分析,提出工程测量学双语教学存在的问题和应采取的改进措施。 相似文献
143.
提高斜拉索索力估算精度的方法 总被引:11,自引:1,他引:10
振动法是测量实际索力的首选方法,但其测试精度会受到外界环境因素如温度、风和桥面对拉索作用等的影响。本文围绕如何将外界环境因素的影响降至最小,从测量时机的选取、数据处理方法的选择等方面,综合运用随机振动、风工程、非线性和误差分析理论,提出了提高拉索索力估算精度的实用改进方法,得出了一些有意义的结论。并通过哈尔滨松花江斜拉桥实例进行验证对比,结果表明,该方法具有较高的精度。 相似文献
144.
145.
Yuling Zhang Hong Qian Jiali Wang Chaoqun Si Zhiyu Chen Jiangyan Dang Zhenyi Zhang 《Environmental Earth Sciences》2017,76(2):90
The objective of this paper was to investigate a petroleum-contaminated groundwater site in northeast China. Based on the monitoring and analysis of environmental characteristics of groundwater slightly contaminated with petroleum, microbes were added into the petroleum-contaminated groundwater via single-well and multiple-well models to enhance bioremediation. The effect of enhanced bioremediation was monitored and analyzed, and variations in the environmental characteristics of groundwater containing total petroleum hydrocarbons (TPH) were identified to provide a scientific basis for controlling and remediating petroleum-contaminated groundwater. Findings confirmed that this site was slightly contaminated and TPH levels exhibited a slight decreasing trend. After enhanced remediation, the microbial degradation effect was large, and the TPH concentration significantly reduced. In particular, near the wells treated by bioremediation, the amounts of electron acceptors, such as NO3 ?, Fe3+, and SO4 2?, markedly decreased. The product of the microbial degradation process, HCO3 ?, gradually increased in the treated wells. Activities of the enzyme catechol 1, 2-dioxygenase decreased, while those of catalase increased. Reductions in pH, from 7.4 to 6.1, were recorded, and the groundwater environment became further deoxidized. 相似文献
146.
利用试验资料,对蒸散面积2 m2和4 m2两种尺寸蒸渗计测量蒸散量的差异及原因进行了研究。结果表明:2 m2蒸渗计与4 m2蒸渗计所测蒸散量具有很好的一致性,但2 m2蒸渗计所测蒸散量总体要略偏大,日蒸散量平均偏大4%,月蒸散量平均偏大10%,年蒸散量相对偏大5%;典型天气条件下,2 m2蒸渗计和4 m2蒸渗计所测蒸散量的日变化过程基本相同,小时蒸散量的差异表现为晴天时白天显著偏大、夜晚略有偏小,阴天时白天略偏大、夜晚较接近,雨天时白天、夜晚均非常接近的特征。晴天和阴天时,2 m2蒸渗计比4 m2蒸渗计测量日蒸散量分别偏大1.78 mm和0.12 mm,雨天时偏小0.11 mm;2 m2蒸渗计比4 m2蒸渗计测量蒸散量总体偏大的原因,主要是2 m2蒸渗计土壤温度显著高于4 m2蒸渗计和建造时间不同导致土体内部土壤湿度产生差异。 相似文献
147.
????XPL????Ч?????????HPL??VPL??????????????????м?????????????????????HPL??VPL??????????????HPL??VPL?????????С??9 m??12 m?????????12 m??20 m????????????????????????????????????? 相似文献
148.
基于增量动力分析(IDA)的倒塌易损性分析方法是评估建筑结构抗地震倒塌能力的精细方法,但分析过程比较繁杂且非常费时。为了较快地评估建筑结构的抗地震倒塌能力,首先利用静力非线性(pushover)分析,获得结构倒塌能力的初步估计值aS*,然后将每个地面运动记录调整到aS*,对结构进行动力时程分析,记录结构的动力时程反应,利用IDA的思想得到结构的中值数倒塌谱强度?CTS。该方法与传统的增量动力分析方法相比较,可提高计算效率,计算精度也满足要求。 相似文献
149.
H. Zhang Z. Dang Ph.D. L. C. Zheng X. Y. Yi Ph.D. 《International Journal of Environmental Science and Technology》2009,6(2):249-258
Sites co-contaminated with organic and metal pollutants are common and considered to be a more complex problem as the two components often causes a synergistic effect on cytotoxicity. Phytoremediation has been proposed as a cost-effective technology for treating heavy metal or organic contamination and may be suitable for remediation of co-contaminated soil. This study investigated the concurrent removal of pyrene and cadmium in co-contaminated soil by growing maize in a pot experiment. At the end of 60 day culture, pyrene in spiked soil diminished significantly, accounting for 21–31 % of the initial extractable concentration in unplanted soil and 12–27 % in planted soil. With the increment of cadmium level, the residual pyrene both in unplanted and planted soil tended to increase. Although the presence of cadmium increased the accumulation of pyrene in maize, plant accumulation only account for less than 0.30 % of the total amount of the dissipated pyrene in vegetated soils. It implied that plant-promoted microbial biodegradation was the predominant contribution to the plant-enhanced dissipation of pyrene in co-contaminated soil. Unlike pyrene, heavy metal cadmium cannot be degraded. It was observed that maize can concurrently removed about on the average 0.70 % of the total cadmium amount in soil by plant uptake, but cadmium phytoextraction would be inhibited under contamination of pyrene. Maize CT38 can normally grow in the co-contaminated soil with high level cadmium and pyrene and can effectively remedy the sites co-contaminated with these two types of contamination, which suggest the possibility of simultaneous phytoremediation of two different contaminant types. 相似文献
150.
区域持续农业的景观生态研究 总被引:9,自引:1,他引:8
从提出背景,概念内涵,本质特性以及实践内容来看,持续农业具有鲜明的生态内涵,研究离不开生态学的指导;从系统主体,出发点、尺度、动态来看,区域持续农业在更大程度上属于景观生态学的研究范畴,因此 生态学可作为区域持续珠理论基础,而主观生态学应用方向的景观生态规划便可实现区域持续农业的空间途径,最后,文章以中国北方农牧过渡北山地的景观利用方向进行案例实践。 相似文献