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991.
控制轨道交通噪声道间声屏障研究 总被引:1,自引:0,他引:1
应用环境噪声预测与分析软件SOUNDPLAN对将设置在上海轨道交通6#线上下行线之间的道间声屏障插入损失进行了模拟计算。计算结果表明,安装道间声屏障可使得距离线路20~30m远的较高层建筑获得2~4.7dB的降噪效果;随着两侧声屏障高度的增加,安装道间声屏障对待测表面的影响范围在缩小;离轨道线路越近,道间声屏障的插入损失越大。 相似文献
992.
用钢渣对含铬废水进行预处理,探讨了钢渣粒度、用量、废水pH值和添加硫酸亚铁还原剂的影响.结果表明,经硫酸亚铁还原处理后再用钢渣处理比单纯用钢渣处理的效果明显提高,采用钢渣/总铬质量比为40的100目钢渣处理经硫酸亚铁还原后的含铬废水,总铬和Cr6 去除率分别达79%和84%,采用钢渣柱进行的两级淋滤实验进一步表明该方法可作为工业上含铬废水处理的预处理段.处理后的废钢渣同工业铬渣一起进行水泥固化,标准养护20 d后固化体表面Cr6 浸出率、破碎至5 mm粒径以下和酸雨淋溶下的浸出液Cr6 浓度均符合安全标准,可作为普通建材或进行填埋处置. 相似文献
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995.
Chaojin Jiang Xiaoqian Jiang Lixun Zhang Yuntao Guan 《Frontiers of Environmental Science & Engineering》2020,14(3):47
996.
Etienne Bienvenu Akono 《Environmental Modeling and Assessment》2018,23(1):15-24
The purpose of this paper is to study the impacts of the vagueness about the transfer of the harvest right on the use of a natural resource. We develop one-period non-cooperative game frameworks to examine whether the choice of the resource owner to be hazy about the transmission of the harvest contract is optimal. In the perfect information situation, we show that it is optimal for the resource owner to forbid the transfer of the harvest right instead of being hazy about it when the transfer fees are lesser than the collected net punishment fines of the monitoring costs even though the resource would be inefficiently used. In particular, we find in this case that the government’s announcement to forbid the transfer of the right should be public. We further show that there are subgame Nash equilibria in the perfect information context and a unique Nash equilibrium in the imperfect information setting. Specifically, we show that, when the transfer fees are greater or equal to the (net) punishment fines, there is a Nash equilibrium both in perfect and imperfect information situations, precisely when the owner chooses to allow the transfer of harvest title and the resource harvester transfers it. 相似文献
997.
Na Wang You-Gan Wang Shuwen Hu Zhi-Hua Hu Jing Xu Hongwu Tang Guangqiu Jin 《Environmental Modeling and Assessment》2018,23(6):779-786
We introduce robust procedures for analyzing water quality data collected over time. One challenging task in analyzing such data is how to achieve robustness in presence of outliers while maintaining high estimation efficiency so that we can draw valid conclusions and provide useful advices in water management. The robust approach requires specification of a loss function such as the Huber, Tukey’s bisquare and the exponential loss function, and an associated tuning parameter determining the extent of robustness needed. High robustness is at the cost of efficiency loss in parameter loss. To this end, we propose a data-driven method which leads to more efficient parameter estimation. This data-dependent approach allows us to choose a regularization (tuning) parameter that depends on the proportion of “outliers” in the data so that estimation efficiency is maximized. We illustrate the proposed methods using a study on ammonium nitrogen concentrations from two sites in the Huaihe River in China, where the interest is in quantifying the trend in the most recent years while accounting for possible temporal correlations and “irregular” observations in earlier years. 相似文献
998.
Kinga Kostrakiewicz-Gierałt 《Russian Journal of Ecology》2018,49(1):47-52
The impact of succession stage on the share of clonal plants in the plant cover, seed rain and seedling pool has been studied in the years 2014 and 2015. The investigations were carried out in abandoned Molinion caeruleae meadows dominated by small-statured species (Patch I), tall growing large-tussock grasses (Patch II) and shrub-willows (Patch III). Although the clonal taxa dominated in the plant cover, seed rain and seedling pool, their share in subsequent study sites was quite different. The spectra of life-history traits relevant to clonality in the plant cover and seed rain were similar and did not vary significantly among subsequent locations, while they mostly differed as observed in the seedling pool. The various spectra observed in seedling pool in subsequent study sites might be due to fact that the seed germination and recruitment of offspring are strongly influenced by habitat conditions which varied remarkably in the successive Patches. 相似文献
999.
The annual relative mass of storage organs cycle of Bufo gargarizans in southwestern China was studied from December 2005 to November 2006. We described how those organs changed in response to extreme temperatures. Energy reservation dropped to the lowest levels after dormancy for both sexes, and then increased for period of 4.25 month. However, the mass of these organs dropped again rapidly until August (liver) and September (fat bodies) due to the constraint from extreme high temperature occurred during the summer, and then non-significantly increased before hibernation. For ovaries, varied with a different profile to those of liver and fat bodies have a resting period of four months. In addition, the toads’ ovaries kept growing when the mass of liver and fat bodies declining accordingly during hibernation. Therefore, ovarian mass increased during the hibernation and non-hibernation period. 相似文献
1000.
Azita Farashi 《Russian Journal of Ecology》2018,49(5):449-455
Many factors such as human activities threat brown bears (Ursus arctos) in Southern Asia, and limit it to small populations in remote and rocky mountainous regions. Brown bears are generally studied in North America and Europe, but there is little information about its conditions and requirements for survival in Asia. During the recent years, brown bear populations in Iran have decreased sharply. Therefore, they are now officially listed as a threatened species in local scale. Therefore, we tried to recognize brown bear habitat relationships in northern Iran using species distribution model (SDM). Maxent method was applied using multiscale approach to predict suitable habitats and habitat relationships of the species. Our results revealed that the predictive ability of environment variables and species distribution maps varied across scales strongly. Also, our findings showed that identifying a proper scale is important issue to improve habitat modeling accuracy. Only 17% of the protected areas was found suitable for brown bear and divided to 5.1% poor, 8.8% suitable, and 3.1% high-quality habitat. Consequently, it is suggested that the protected area of northern Iran reconsiders with interventions aimed at maintaining suitable habitats of brown bear. 相似文献