水库深孔挑射出流对复氧的试验研究   总被引：2，自引：0，他引：2       下载免费PDF全文

范丽丽  沙海飞  吴时强  周辉  陈惠玲 《水科学进展》2006,17(2):176-180

在水工泄水建筑物复氧能力的研究中,前人对自由溢流复氧能力和闸下出流复氧能力的研究较多,但对泄流水库下层水的中孔和深孔的复氧能力研究较少.为了消除低溶解氧的水库下层水对下游生态环境的不利影响,保证水生生物的多样性,在滩坑水电站泄洪洞模型中进行了系统的试验,发现复氧率与弗汝德数和下游相对水深相关性较好,同时增设掺气槽能够显著的提高复氧率.经研究提出的在一定条件下的经验公式,为水工深孔设计提供了参考.  相似文献   

Limestone assimilation and the origin of CO₂ emissions at the Alban Hills (Central Italy): Constraints from experimental petrology     

Giada Iacono Marziano  Fabrice Gaillard  Michel Pichavant 《Journal of Volcanology and Geothermal Research》2007

The Alban Hills volcanic region (20 km south of Rome, in the Roman Province) emitted a large volume of potassic magmas (> 280 km³) during the Quaternary. Chemical interactions between ascending magmas and the ∼ 7000–8000-m-thick sedimentary carbonate basement are documented by abundant high temperature skarn xenoliths in the eruptive products and have been frequently corroborated by geochemical surveys. In this paper we characterize the effect of carbonate assimilation on phase relationships at 200 MPa and 1150–1050 °C by experimental petrology. Calcite and dolomite addition promotes the crystallization of Ca-rich pyroxene and Mg-rich olivine respectively, and addition of both carbonates results in the desilication of the melt. Furthermore, carbonate assimilation liberates a large quantity of CO₂-rich fluid. A comparison of experimental versus natural mineral, glass and bulk rock compositions suggests large variations in the degree of carbonate assimilation for the different Alban Hills eruptions. A maximum of 15 wt.% assimilation is suggested by some melt inclusion and clinopyroxene compositions; however, most of the natural data indicate assimilation of between 3 and 12 wt.% carbonate. Current high CO₂ emissions in this area most likely indicate that such an assimilation process still occurs at depth. We calculate that a magma intruding into the carbonate basement with a rate of ∼ 1 – 2 · 10⁶ m³/year, estimated by geophysical studies, and assimilating 3–12 wt.% of host rocks would release an amount of CO₂ matching the current yearly emissions at the Alban Hills. Our results strongly suggest that current CO₂ emissions in this region are the shallow manifestation of hot mafic magma intrusion in the carbonate-hosted reservoir at 5–6 km depth, with important consequences for the present-day volcanic hazard evaluation in this densely populated and historical area.  相似文献   

蒸馏法富集纯化Os实验条件研究及其在负离子热电离质谱测量中的应用   总被引：1，自引：1，他引：0  

李欣尉  杨显德  李超  周利敏  赵鸿 《岩矿测试》2018,37(4):439-447

微蒸馏是富集纯化Os的一项重要化学前处理技术,提高Os回收率对提高Os的负离子热电离质谱(NTIMS)测量精度尤为重要。在微蒸馏过程中,蒸馏温度、吸收液体积、蒸馏时间等对Os回收率具有重要影响,但目前微蒸馏的实验条件不够明确,导致Os回收率不稳定,影响NTIMS测量精度,易增加所得Re-Os年龄误差。本文以自制的含Os溶液为对象,以ICP-MS为测量手段,对微蒸馏过程中多种实验条件对Os回收率的影响进行深入研究,以期获得最佳微蒸馏实验条件,满足后续NTIMS对Os信号强度的测量要求。结果表明:在溶液蒸干温度为120℃并保持15 min,微蒸馏温度为80℃,氢溴酸吸收液体积为15μL,微蒸馏时间为2 h的条件下,获得Os回收率为80%~90%,能够满足多种地质样品尤其是中酸性岩浆岩、热液硫化物等pg级地质样品的NTIMS测量要求,在保证Os信号强度的情况下提高了分析效率。  相似文献   

Basin analysis palaeo-landscape modelling: Testing the critical controls using experimental design constrained by a real 3D geological model,Gippsland Basin,Australia     

Xuemei Yang  Gregory Smith  Ritu Gupta 《Basin Research》2023,35(1):214-243

The main controlling variables for palaeo-landscape evolution are investigated to assess their relative importance using the Gippsland Basin geological history. Palaeo-landscape reconstruction is a complicated process controlled and affected by multiple variables, including tectonic, palaeo-environment, sea-level change, rainfall, sediment erosion, transportation, deposition, etc. The Basin and Landscape Dynamics software (Badlands) software was used with an efficient experimental design (ED) to guide the selected scenarios, process the results, and generate the multi-variate equations that define and identify the important controlling variables. The ED was used to test and identify the main uncertainties and their possible ranges, based on actual field data, while at the same time ensuring that the full multi-dimensional space for those variables was covered to enable the computation of multivariate equations from the minimum number of scenario runs. A full suite of 3D forward palaeo-landscape models of the Gippsland Basin was built to reconstruct the basin history from its formation to the present (Early Cretaceous to Holocene, 137-0 Ma). The models are compared to the corresponding full 3D realistic structural and stratigraphic model of the basin that has been built in Petrel (Schlumberger software). This constrains the sedimentary, stratigraphic, burial and thermal histories to the relative subsidence rates and basin-fill for each geological sequence by using the model isopachs input to the Badlands modelling. The ED required only 22 scenarios to fit 12 identified variables and test for possible interactions with each other. The most significant variables are those that control sediment supply including non-marine erodibility, rainfall, (Rainfall × Area) exponent m, Slope and critical slope while maximum % Marine Deposition and marine dispersal are also required to fill the marine accommodation space. Sea Level and subsidence only become significant when rapid enough to outpace sediment supply. The controlling factors change over time with basin development from rift to post-rift phases and interactions are highly significant.  相似文献   

Review of the Field Measurements and Parameterization for Dust Emission During Sand-Dust Events          下载免费PDF全文

ZHANG Hongsheng  LI Xiaolan 《Acta Meteorologica Sinica》2014,28(5):903-922

Dust emission generated by wind erosion is a basic process before the transport and deposition of dust particles. Parameterization of dust emission flux is important for accurate simulation and prediction of dust events. Field observation and numerical simulation are two approaches to understand the complex process of dust emission. Great progress has been made on the characteristics and mechanism of dust emission during dust storm events. This review introduces the major factors influencing dust emission and summarizes the calculation methods of several key parameters of dust emission, including the threshold friction velocity u.t, threshold wind speed Ut, streamwise saltation flux Q, and （vertical） dust emission flux F, from perspectives of both observation and parameterization. The paper also discusses the improvement, application, and validation of different dust emission schemes in dust models. Existing problems and future research directions are elaborated as well.  相似文献   

致密储层孔隙结构研究综述     

陈秀娟  刘之的  刘宇曦  柴慧强  王勇 《物探与化探》2022,(1):22-31

国家对油气资源需求日益剧增的背景下,油气田勘探开发的主战场由常规转向非常规领域,致密油气成为当今及未来非常规油气勘探开发的热点和重点.我国致密储层多为陆相沉积,横向连续性差、纵向非均质性强、岩性复杂、物性变化大,致使致密储层的孔隙结构难以有效表征.储层孔隙结构不仅影响油气赋存,还严重制约着油气渗流和高效开采.为有针对性...  相似文献   

5400阶次勒让德函数的递推计算方法          下载免费PDF全文

刘缵武  刘世晗  张敬伟 《海洋测绘》2014,(4):1-4

超高阶球谐重力场模型由超高阶次勒让德函数构成。即使采用压缩因子递推计算超高阶(如大于3600阶)勒让德函数,在两极附近仍然会出现溢出(上溢或下溢)而导致计算失败。基于对递推公式的分析,利用改进的压缩因子修正递推算法,可以得到直到5400阶次高精度"压缩勒让德函数",且仍可用Horner技术求和。  相似文献   

卓越海洋人才培养模式创新实验区建设的探索与实践     

林年冬  安立龙 《广东海洋大学学报》2014,(5):96-100

介绍了广东海洋大学卓越海洋人才培养模式创新实验区的建设情况,分析了实验区建设背景、建设宗旨、建设措施和建设成效,从教育理念、培养途径、机制创新等方面提出进一步加强实验区建设的建议。  相似文献   

块石路基对流特性实验研究   总被引：4，自引：3，他引：1  

俞祁浩  钱进  游艳辉  胡俊  郭磊 《冰川冻土》2012,34(2):411-417

利用块石层调控冻土路基地温是冻土工程主动冷却路基的一种重要措施,并在青藏铁路重大工程建设中得到广泛应用.通过块石层中空气流动特性的深入研究,对其结构优化和效能提升具有重要意义,而不同温差条件下块石层中空气的流动特性,以及微风速的实际测定一直是其中亟待解决的问题.通过高精度微风速探测,首次获得封闭条件下块石层的空气流动特征.结果表明:在边界温度波动条件下,块石层内的降温过程与其内部自然对流过程密切相关,在对流作用下快速完成降温过程;升温过程则在相对较长时段内主要由内部的热传导换热完成,由此导致温度变化曲线非对称这一特殊现象的出现,并随深度增加而愈加明显.块石层上下端面的温差是对流发生及强度的关键控制因素,当温差达到一定量值时流速随温差的增加而加大,同时空气温度的变化也会对空气流动过程产生影响;块石层内整个空气流动过程是一个传递过程,也是热量传递的过程.该实验研究结果将对该种工程措施机理的进一步认识和改进、相关模拟计算参数的选取,以及在冻土区高等级公路等重大工程建设中的进一步有效应用均具有重要意义.  相似文献   

宽尾墩消力池透水底板脉动压力试验研究          下载免费PDF全文

刘安富  杨敏  李会平  董天松 《水科学进展》2012,23(2):243-248

与不透水底板相比,透水底板能够降低作用在其上的动水荷载,达到防护结构安全稳定的目的。为了更好地认识透水底板这种新型防护结构形式,基于阿海水电站宽尾墩底流消力池水工模型试验,系统地研究了消力池平底透水底板表、底面脉动压力特性在板块开孔前后的变化规律。试验结果包括脉动压力沿程分布规律、概率密度分布的正态性、板块表、底面时空相关性、积分尺度以及脉动压力功率谱密度,并初步探讨了透水底板减压降载机理。试验成果可为消力池透水底板设计提供参考。  相似文献