关键词： 压差传感技术   红谷隧道   沉降位移   自动化监测  

摘要： 对压差传感技术应用到沉降位移监测进行了误差理论研究,发现误差影响因素主要有压强传递介质密度的温度变化率、测点与基点的高差和温度,结合上述3个变量建立了误差公式;然后,通过户外试验证明了基于压差传感技术的沉降位移自动化监测系统的可行性以及误差公式的正确性,同时以红谷隧道管段间相对沉降位移监测数据系统误差控制在±0.5mm内为例,反演出自动化监测系统中需要把测点间的竖向相对位置控制在18 mm;通过对红谷隧道管段间相对位移沉降的实时连续监测数据进行分析,与人工数据基本吻合。

关键词： 蒸发岩   石盐   包裹体   古环境  

摘要： 蒸发岩是保存古环境信息的宝库,而石盐是蒸发岩盆地完全干涸后最主要的矿物。石盐矿物具有很好的封闭性,在浅埋深状态就会固结成岩,没有孔隙并且不可压缩。石盐、石膏、钙芒硝、芒硝中的包裹体,是潟湖或陆地盐湖环境下,通过蒸发而结晶析出过程中所捕获的流体（液体和/或气体）。因此,在石盐矿物的内部可以保存下来良好的原生石盐流体包裹体,它们记录了原始海洋/盐湖的温度、化学组分和大气成分的信息,为古环境研究提供了绝妙的直接记录。其中石盐原生流体包裹体的均一温度,可记录卤水沉积时的温度;浅水环境石盐流体包裹体记录的卤水温度近似等于气温。石盐原生流体包裹体中的卤水成分代表了海水/盐湖蒸发浓缩过程中的卤水,可通过其来推断当时的海水/盐湖水体的成分。石盐漏斗晶形成时是漂浮在卤水表面的,其原生流体包裹体可捕获当时的大气,而石盐是一种稳定的无机矿物,其原生流体包裹体可保存原始的大气信息。石盐原生流体包裹体可以提供其他传统地球化学手段无法提供的直接、精确、定量的地质记录,因此在未来的古环境研究中将成为焦点。

关键词： 超临界   大涡模拟   喷雾   状态方程  

摘要： 基于大涡模拟方法对超临界喷射进行数值分析,使用真实气体状态方程SRK计算流体的热物性和输运特性.研究对象是定容弹内低温液氮超临界喷射,假定初始入口条件不变,重点考察了不同环境压力对超临界喷雾特性的影响.结果表明:由于射流流体与周围流体之间存在较大密度比,射流表面形成显著的密度分层,并起到限制射流流体向径向扩展的作用.随着环境压力的提高,由于射流和周围环境的密度比降低,射流表面不稳定增加,比较容易形成不稳定涡,从而更有利于射流与周围气体的混合,因而液核长度也比较短,表明随着压力的增大,射流与周围气体的混合效果更好.进一步分析发现,环境压力对热物性和输运特性的影响较大,而对湍动能和速度场的影响不大.

关键词： Frequency response  

摘要： V-shaped beams have been widely used in atomic force microscope (AFM) and micro-nano mechanical sensing applications. The structure is usually used for sophisticated detection, sensing and performance characterization in viscous fluids, thus making it complex to study the vibration characteristics of the structure by considering the fluid-structure interaction between the complicated geometry and viscous fluids. It is of fundamental importance to investigate the vibration characteristics of V-shaped beams submerged in viscous fluids owing to the fact that the vibration characteristics will directly affect the dynamic properties of the applications. In this paper, an underwater vibration model is developed to depict the dynamic characteristics of V-shaped beams immersed in viscous fluids by taking into account the fact that the cross-section and bending stiffness of the V-shaped beam are variable along the beam axis. A complex hydrodynamic function in terms of the gap to width ratio and the frequency parameter is developed to describe the hydrodynamic loading where the complex hydrodynamic function is derived from the modified hydrodynamic function based on the gap to width ratio in beam's cross-section. Besides, the frequency response of V-shaped beams vibrating in viscous fluids is obtained theoretically. Moreover, the experimental verifications on flexural vibrations of several V-shaped beams with different geometrical sizes are carried out. It demonstrates that the experimental data is in good agreement with the theoretical results, thus validating the modified expression of hydrodynamic function and the underwater dynamic model. Besides, the effect of different fluid viscosities, angles of V-shaped beams and the scale of the geometry on the vibration characteristics of the coupling system is analyzed based on the proposed fluid-structure interaction model. © 2018, Editorial Office of Chinese Journal of Theoretical and Applied Mechanics. All right reserved.

关键词： 晚白垩世   碳同位素   稀土元素   流体来源   沉积环境   岗巴   西藏  

摘要： 冷泉碳酸盐岩是海底冷泉流体活动的重要标志,其地球化学特征记录了过去流体活动的信息。西藏岗巴地区晚白垩世沉积地层中发育有冷泉碳酸盐岩,为了探究其形成的流体来源及沉积环境,开展了野外观察、岩石学、矿物学、地球化学研究。该区岗巴剖面冷泉碳酸盐岩以结核状产于灰黑色页岩中,碳酸盐矿物主要为泥微晶方解石,含少量草莓状黄铁矿,δ13CV-PDB为-17.0‰^-7.2‰,表明碳源可能与甲烷渗漏冷泉活动有关。稀土元素分布模式呈中稀土富集特征,经La校正后显示无Ce异常,指示了冷泉碳酸盐岩形成于弱缺氧的沉积环境中。西藏岗巴地区碳酸盐岩结核的发现及其地质地球化学特征是该地区晚白垩世冷泉甲烷渗漏活动发育的有力证据,对古冷泉流体来源及沉积环境特征的探讨将为恢复古冷泉活动提供重要线索。

关键词： Particle aggregation   Volcanic ash   Meteorite impact   Granulation  

摘要： Aggregation is a common process occurring in many diverse particulate gas mixtures (e.g. those derived from explosive volcanic eruptions, meteorite impact events, and fluid bed processing). It results from the collision and sticking of particles suspended in turbulent gas/air. To date, there is no generalized model of the underlying physical processes. Here, we investigate aggregates from 18 natural deposits (16 volcanic deposits and two meteorite impact deposits) as well as aggregates produced experimentally via fluidized bed techniques. All aggregates were analyzed for their size, internal structuring, and constituent particle size distribution. Commonalities and differences between the aggregate types are then used to infer salient features of the aggregation process. Average core to rim ratios of internally structured aggregates (accretionary lapilli) is found to be similar for artificial and volcanic aggregates but up to an order of magnitude different than impact-related aggregates. Rim structures of artificial and volcanic aggregates appear to be physically similar (single, sub-spherical, regularly-shaped rims) whereas impact-related aggregates more often show multiple or irregularly shaped rims. The particle size distributions (PSDs) of all three aggregate types are similar (< 200 mu m). This proves that in all three environments, aggregation occurs under broadly similar conditions despite the significant differences in source conditions (particle volume fraction, particle size distribution, particle composition, temperature), residence times, plume conditions (e.g., humidity and temperature), and dynamics of fallout and deposition. Impact-generated and volcanic aggregates share many similarities, and in some cases may be indistinguishable without their stratigraphic context.

关键词： 流体力学   创新思维   教学方法改革   问卷调查  

摘要： 本文通过对建环专业在校生进行匿名问卷调查,统计和分析了建环专业流体力学与流体机械课程教学中存在的主要问题,征求了改善教学效果的具体建议,同时比较研究了各高校针对本课程的教学改革方法。通过将问题导向式教学、虚拟实验教学、课堂实验、专业工程实践类型大作业的多种教学改革手段引入课堂,激发了学生的学习热情,全面提高了学生的分析、表达、逻辑推导和应用基本理论解决工程实践问题的能力,有助于培养学生的创新思维。

关键词： 超临界流体萃取技术   环境工程   污染治理  

摘要： 在我国现阶段的环境工程中,超临界流体萃取技术是非常重要的一项技术。本文首先简要介绍了超临界流体萃取技术的基本原理和应用状况,随后重点分析了超临界流体萃取技术在废水治理、大气污染物治理以及固体废弃物治理中的应用。希望这些观点能够有效提升环境保护工程的长远发展,促进我国的生态文明建设。

关键词： 微流体系统   微加热系统   装置设计   细胞培养  

摘要： 设计开发一种新型功能化的二维微流体加热器系统,用于哺乳动物细胞(Hela)的灌注培养及生长过程中的实时监控.该装置在无培养箱的条件下,可以为细胞提供生长所需的温度环境.采用聚二甲硅氧烷(PDMS)及多层控制阀门制作微流体通道,与采用镀有金和铬的玻璃片制作的加热片高度集成,构成一个加热片上具备9个加热单元的装置.通过阀门控制,装置各单元独立工作,控制各腔室细胞接种及排出.该系统可以为各腔室培养的细胞提供稳定及均匀的温度(37℃),培养结果显示所培养细胞生长状况良好,表明该装置具有较好工作性能.

关键词： 心血管疾病   胞外囊泡   微型核糖核酸   微流体  

摘要： 摘要隐藏中