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111.
纯水、超纯水与饮用纯净水 总被引:3,自引:0,他引:3
饮用纯净水按水的纯度概念划分已属各纯水( 含初级纯水、纯水、高纯水) 范围。制取的水为去离子水、软水、酸性( 偏) 水,其中尚有无氧的死水。饮用纯净水取自天然,由于制作的过度纯化已不具天然性。因此,饮用纯净水有诸多值得忧虑的问题。天然矿泉水仍有无可比拟的可靠性和珍贵性。 相似文献
112.
针对某些地质条件导出了离散双重介质二维二相流耦合微分方程,对方程中的渗透率和裂隙宽度进行了Karhunen-Loeve级数展开,对其他参数进行了多项式随机函数的级数展开,同时对截取级数前有限项所产生的误差作了分析.在求解基本未知量的同时也能求解随机变量的特征数。 相似文献
113.
焦家断裂带是我国著名的金矿聚集带,分布有新城金矿、焦家金矿、朱郭李家金矿、寺庄金矿等多个深部大型矿山,多年来围绕该带提交的详查报告很多,矿床水文地质条件研究程度较高。为了能更加确切、清晰地反映焦家断裂带下盘地下水水文地质特征,围绕抽水试验技术方法稍作改进,应用过程中效果明显。 相似文献
114.
CHEN Jingsheng TIAN Dexin YANG Hao LI Weiwei LIU Miao LI Bin YANG Fan LI Wei WU Zhen 《《地质学报》英文版》2019,93(5):1325-1353
The early Mesozoic marked an important transition from collisional orogeny to post-orogenic extension at the northern margin of the North China Craton(NCC). In this study, we undertook zircon U-Pb dating and whole-rock majorand trace-element geochemical analyses of early Mesozoic granitic rocks in the Chifeng area to establish their geochronological framework, petrogenesis, and implications for the tectonic evolution of the eastern Central Asia Orogenic Belt(CAOB). Zircon U-Pb dating results show that these rocks were emplaced in three stages during the Triassic:(1) syenogranites during 250–248 Ma,(2) granodiorites during 244–243 Ma, and(3) monzogranites and granodiorites during 232–230 Ma. These Triassic granitoids belong to the high-K calc-alkaline series and are evolved I-type granites. They have high SiO_2 and low Mg O contents with enrichments in light rare-earth elements, Zr, Hf, Rb, Th, and U, and depletions in Ba, Nb, Ta, Sr, and Eu. These geochemical data indicate that the granitoids were derived from partial melting of a lower-crustal source under relatively low-pressure conditions and subsequently underwent extensive fractional crystallization. Considering both the geochemical data and regional geological information, we propose that the 250–248 Ma syenogranites were emplaced in an extensional environment linked to slab break-off after closure of the Paleo-Asian Ocean(PAO) along the Solonker-Xra Moron-Changchun suture zone. The 244–243 Ma granodiorites were formed in a compressional orogenic setting during collision between the Erguna-Xing'an-Songliao composite block and the NCC. The 232–230 Ma granodiorites and monzogranites were emplaced during the transition from compressional orogeny to post-orogenic extension. Overall, the early Mesozoic tectonic evolution of the Chifeng area can be divided into three main stages:(1) closure of the Paleo-Asian Ocean and extension related to slab break-off during the Early Triassic;(2) continuous collisional compression during the Middle Triassic after closure of the PAO; and(3) post-orogenic extension during the Late Triassic, most probably due to lithospheric delamination after amalgamation of the Erguna-Xing'an-Songliao composite block and the NCC. 相似文献
115.
正Objective Western Liaoning has a large area of Mesozoic continental strata,which is unique for the study of Mesozoic continental strata in China and even all over the world.The Jurassic-Cretaceous boundary of Mesozoic continental strata in Western Liaoning has been controversial since 2013 when the Jurassic-Cretaceous boundary at 145 Ma was established in the international stratigraphic table.The Tuchengzi Formation is a key Mesozoic stratum in Western Liaoning,which is widely distributed and has a clear top and bottom.The 相似文献
116.
117.
内蒙古赤峰敖汉旗地区属于宁城-捣格朗营子火山喷发带北段。通过实测剖面和大比例尺地质调查,确定敖汉旗地区中生界以火山岩为主的地层为义县组,并将其进一步划分为4个岩性段:一段由复成分砾岩和含砾粗砂组成,二段由酸性流纹质火山岩组成,三段由一套安山质的火山岩及沉积相的凝灰质砂砾岩等组成,四段由中性偏碱性的粗面英安质火山岩组成。本区各段火山岩LA-ICP-MS锆石U-Pb测年结果表明,敖汉旗地区义县组火山活动时限为127.7~121.6Ma。该结果与北部阜新-义县盆地义县组标准剖面年龄可对比。依据岩石组合特征、同位素测年结果,敖汉地区义县组可以与标准剖面的中部对比,缺失可与标准剖面上部对比的层位。 相似文献
118.
119.
杨境生 《成都信息工程学院学报》1993,(1)
本文介绍了在定向生班和委培生班进行有关高等数学教学方面的教学经验;因材施材,教书育人和培养学生分析问题和解决问题的能力等。 相似文献
120.
Piyang Liu Gary Douglas Couples Jun Yao Zhaoqin Huang Wenhui Song Jingsheng Ma 《Computational Geosciences》2018,22(5):1187-1201
The two-scale continuum model is widely used in simulating the reactive dissolution process and predicting the optimum injection rate for carbonate reservoir acidizing treatment. The numerical methods of this model are currently based on structured grids, which are not applicable for complicated geometries. In this study, a general numerical scheme for simulating a reactive flow problem on both structured and unstructured grids is presented based on the finite volume method (FVM). The convection and diffusion terms involved in the reactive flow model are discretized by using the upwind scheme and two-point flux approximation (TPFA), respectively. The location of the centroid node inside each control volume is moved by using an optimization algorithm to make the connections with the surrounding elements as orthogonal as possible, which systematically improves the accuracy of the TPFA scheme. Additionally, in order to avoid the computational complexity resulting from the discretization of the non-linear term, the mass balance equation is only discretized in the spatial domain to get a set of ordinary differential equations (ODEs). These ODEs are coupled with the reaction equations and then solved using the numerical algorithm on ODEs. The accuracy and efficiency of the proposed method are studied by comparing the results obtained from the proposed numerical method with previous experimental and numerical results. This comparison indicates that, compared with the previous methods, the proposed method predicts the wormhole structure more accurately. Finally, the presented method is used to check the effect of the domain geometry, and it is found that the geometry of the flow domain has no effect on the optimum injection velocity, but the radial domain requires a larger breakthrough volume than the linear domain when other parameters are fixed. 相似文献