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排序方式: 共有1715条查询结果,搜索用时 31 毫秒
61.
不同围压下混凝土受压弹塑性损伤本构模型的研究 总被引:17,自引:0,他引:17
在MTS公司81502型电液伺服系统上,完成了围压由0~40MPa范围内混凝土受压试验,发现随着围压的增大,应力应变全曲线的峰值应力与峰值应变均有所提高,但弹性模量基本不变在此基础上,根据等效应变假定和内变量理论,建立了考虑不可逆应变影响的弹塑性损伤本构模型只要计及峰值应力和峰值应变的变化,该模型可以统一地描述不同围压下混凝土的力学性能 相似文献
62.
考虑到潜水含水层普遍存在入渗补给这一客观事实,本文应用迭加原理推导、建立有均匀入渗条件下潜水稳定井流公式. 相似文献
63.
准确识别和把控矿山地质环境问题是矿山安全生产和矿区生态文明建设的重要内容,矿山地质环境问题的解码对于矿产资源开发和矿区环境保护具有十分重要的意义。本文通过常见矿山地质灾害、含水层破坏及其危害、水土污染和地形地貌景观破坏等四个方面对矿山地质环境问题进行阐述,通过图文并茂的形式解码矿山开采引发的环境问题,更直观地展现矿业开发对地质环境和生态空间的影响,以期增强人们对矿业开发引发环境问题的重视,引导更多人参与到保护矿山地质环境的行列中,也为科学规划矿业开发,匹配矿区环境承载能力等矿业综合监管提供了方向性支撑。 相似文献
64.
Ying-Jiao Li Ting-Ting Qi Kun Dong Guang-Wen Chu Hai-Kui Zou Bao-Chang Sun 《American Institute of Chemical Engineers》2022,68(3):e17509
Catalytic hydrogenation of maleic anhydride (MA) into succinic anhydride (SA) is one of the most important transformations in synthetic organic chemistry. Herein, we firstly synthesized well-dispersed nickel particles confined by mixed metal oxides (Ni/MMO) derived from in situ transformation of Ni-Al hydrotalcite in a rotating packed bed (RPB) to catalyze this process. A series of Ni/MMO catalysts (63 wt%–89 wt% Ni) were effectively fabricated and the structure–activity relationship was established. Results showed that a Ni/MMO catalyst (82 wt% Ni) with substantial surface defect sites and the highest Ni surface area among the prepared Ni/MMO catalysts, demonstrates the highest activity with ~100% MA conversion and ~100% selectivity to SA under 25°C within 77 min. This is, to our knowledge, the highest conversion and selectivity under room temperature to date. Moreover, the Ni/MMO catalyst prepared by RPB has higher specific surface area and Ni surface area, therefore possessing a higher hydrogenation rate compared to that by stirred tank reactor (1.69 vs. 1.36, 10−3·molMA/gcat/min). These results will provide an attractive option of the catalysts for MA hydrogenation, and a novel strategy for synthesizing nickel catalyst derived from Ni-Al hydrotalcite. 相似文献
65.
66.
针对第⑥硬土隔水层有缺失的上海地铁M8线黄兴路车站深基坑,分析了车站深基坑工程特点,提出了基坑承压水处理方案,从技术、经济、对环境影响等角度对方案进行了比选,并将比选后方案应用于工程实际,结果显示该方案切实可行。最后,对基坑承压水的处理提出了一些建议。 相似文献
67.
分析采矿活动对地表损坏的原因.得出了以含水层失水与岩溶塌陷为主、开采直接影响为辅的采动损害结论.研究结论为南方岩溶发育地区开采损害预计和责任认定提供了依据. 相似文献
68.
69.
Zhiqiang Liu Jian Zhou Xiaomin Tang Fujian Liu Jiamin Yuan Guangchao Li Ling Huang Rajamani Krishna Kuan Huang Anmin Zheng 《American Institute of Chemical Engineers》2020,66(8):e16269
Zeolites have been widely used for the processes of adsorption, separation, and catalysis, which are strongly correlated with molecular diffusion. However, the correlation between pore dimension and diffusion properties has not been systematically investigated so far. In this work, the diffusion properties of alkanes in six zeolites with similar pore sizes but different pore dimension have been examined. It is found that the diffusion coefficients of alkanes in zeolites are 2–5 orders of magnitude smaller than that in gas phase. Moreover, the diffusion of alkanes inside zeolites is sensitive to the pore dimension, and can be differentiated by 1-D straight, 1-D tortuous, and 3-D intersecting channels, based on the derived quantitative correlation between the diffusion behavior and pore dimension. Our work may not only provide deep insights into the effects of pore dimension on diffusion, but also benefits for the future design and practical applications of zeolite catalysts. 相似文献
70.
Jiqi Wang Fei Wu Yuhong Cui Junjie Chen Aibo Zhang Qiuyu Zhang Baoliang Zhang 《Journal of the American Ceramic Society》2020,103(10):5706-5720
In this study, a simple and efficient method for fabrication of tubular magnetic carbon nanofibers (TMCF) has been developed. Firstly, tubular polymer nanofiber precursors are synthesized by confined self-condensation method. After carbonization of polymer and in situ transformation of FeCl3 at high temperature, TMCF loaded with Fe nanoparticles is obtained. It has been found that carbonization temperature has significant effects on conductivity, specific surface area, pore volume, defects number in carbon component, and magnetic content of TMCF. The influence of composition, structure, and filler content on microwave absorption properties is revealed. Meanwhile, the microwave absorption mechanism has been analyzed in depth, which benefits from the designed unique structure. The TMCF obtained at 700°C exhibited best performance with the filler content of 15%. The minimum reflection loss is −47.33 dB@2.2 mm, the effective absorption bandwidth is 6.5 GHz (RL < 10 dB), and the matching frequency is 14.1 GHz. The obtained TMCF is lightweight and possess excellent microwave absorption ability, which can be widely used as highly efficient microwave absorber. 相似文献