Mixing of A Non-Circular Jet into A Counterflow

An elliptic jet and a square jet flowing into a counterflow with different jet-to-current velocity ratios are investigated by using realizable k–ε model. Some computed mean velocity and scalar features agree reasonably well with experimental measurements, and more features are obtained by analyzing the computed results. After fluid issues from a nozzle, it entrains ambient fluid, and its velocity and concentration on the centerline decay with the distance downstream from the potential core (l0). The decay ratio increases with the decreasing jet-to-current velocity ratio α. For an elliptic jet, the evolution of the excess velocity half-width b and the concentration half-width bc merely remains constant near the jet exit on major-axis plane while they increase linearly on the minor-axis plane. However, the half-widths on the major-axis and minor-axis plane become proportional to the axial distance downstream after equaling each other. For a square jet, b and bc increase linearly with the distance downstream from the jet exit, but the spread ratio is larger on the middle plane than that on the diagonal plane before they equal each other. The radial extent of the dividing streamline rs or the mixing boundary rsc increases linearly downstream, and decreases exponentially after reaching a peak at xb. The ratio on the minor-axis plane is larger than that on the major-axis plane for an elliptic jet. The characteristics are the same for the square jet. b, bc, rs, and rsc on two corresponding planes become equal to each other more rapidly for the square jet than for the elliptic jet, because the sharp corner of the square nozzle induces secondary structures that are more intense. The distributions of the excess axial velocity and scalar concentration exhibit self-similarity for either the elliptic jet or square jet in the region of l0 < x < xb. On the cross section, four counter-rotating pairs of vortices, which enhance the entrainment between the jet and counterflow, form at the four corners of the square jet or at the two ends of the major-axis plane of the elliptic jet. The recirculation pattern formed by these axial vortices is more complex for the square jet than that for the elliptic jet. The turbulent kinetic energy k have large value in the region near the jet exit and stagnation point. The maximum value of k for the square jet is larger than that of the elliptic jet near the jet exit. This results in the square jet mixing more strongly than the elliptic jet.     

Initial Dilution of A Vertical Round Non-Buoyant Jet in Wavy Cross-Flow Environment

The phenomenon of wastewater discharged into coastal waters can be simplified as a turbulent jet under the effect of waves and currents. Previous studies have been carried out to investigate the jet behaviors under the current only or the wave only environment. To gain obtain better understanding of the jet behaviors in a realistic situation, a series of physical experiments on the initial dilution of a vertical round jet in the wavy cross-flow environment are conducted. The diluted processes of the jet are recorded by a high-resolution camcorder and the concentration fields of the jet are measured with a peristaltic suction pumping system. When the jet is discharged into the wavy cross-flow environment, a distinctive phenomenon, namely “effluent clouds”, is observed. According to the quantitative measurements, the jet width in the wavy cross-flow environment increases more significantly than that does in the cross-flow only environment, indicating that the waves impose a positive effect on the enhancement of jet initial dilution. In order to generalize the experimental findings, a comprehensive velocity scale ua and a characteristic length scale l are introduced. Through dimensional analysis, it is found that the dimensionless centerline concentration trajectories is in proportional to 1/3 power of the dimensionless downstream distance , and the dimensionless centerline dilution is proportional to the square of the dimensionless centerline trajectory . Several empirical equations are then derived by using the Froude number of cross-flow Frc as a reference coefficient. This paper provides a better understanding and new estimations of the jet initial dilution under the combined effect of waves and cross-flow current.     

金沙江-红河成矿带斑岩铜钼矿的成矿集中期: Re-Os同位素定年

利用Re-Os同位素定年方法对云南境内金沙江-红河成矿带中的斑岩铜矿进行了年代学研究, 获得了马厂箐(33.9±1.1)Ma和铜厂(34.4±0.5)Ma的新数据. 表明马厂箐和铜厂两个矿区的斑岩型铜钼矿是基本同时形成的. 结合前人获得的西藏玉龙铜矿(与马厂箐和铜厂位于同一成矿带)的辉钼矿Re-Os模式年龄(35.4, 35.9, 36.2 Ma), 可以认为, 金沙江-红河成矿带中近于等间距分布的3个新生代斑岩铜矿是基本同时形成的, 均属始新世后期同一成矿集中期的产物.     

云南元江地区中元古代昆阳群下亚群的沉积地质及控矿作用

滇中地区昆阳群下亚群的沉积层序和沉积构型对原生铜矿形成、富集和就位均有重要的控制作用．从时间上讲,昆阳群下亚群分为４个层序．第一层序海侵体系域的因民组中上部火山岩和深水沉积及下伏大红山群为原生铜矿的生矿层,第一层序高水位体系域的落雪组及其上下过渡段为原生铜矿的储矿层,第二层序海侵体系域鹅头厂组的泥质沉积为铜矿的盖层．在空间上,滇中地区中元古代裂谷盆地的结构和沉积构型对铜矿的空间分布也具明显的控制作用．铜矿的就位场所主要位于断隆－断陷区之间的同沉积断裂附近,尤其是靠近断隆区边缘落雪组的高水位体系域进积序列及其相变带．元江地区中元古代的铜矿找矿方向应着重考虑同沉积断裂带与落雪组及上下过渡段相变的复合部位．     

易门七步郎铜矿床控矿因素及富集规律研究

本文通过对七步郎铜矿床含矿层位、容矿岩石类型、构造及地球化学和成矿特征等综合分析、研究，从铜矿化的时、空结构特征两方面框定了控矿的主导因素，探讨了成矿富集规律，提出只有经历初始预富集→预富集→构造改造富集完整序列阶段的区段方能形成富矿体的认识。对成矿预测有重要实际意义。     

ERS卫星雷达干涉测量:1999年台湾集集大地震震前和同震地表位移

1999年集集大地震(Mw=7.6)是20世纪以来台湾岛内最大的地震.在本研究中,5个不同时间获取的ERS-1/2卫星合成孔径雷达图像被组合,并被处理成多个差分干涉图,以此来考查与该地震相关的地表位移场.这些差分干涉图(空间分辨率为50m×50m)详细地揭示了沿台湾西海岸震中附近150km2陆地范围内的震前和同震地表形变.几个具有较长时间(2-3a)跨度的震前干涉图呈现出高度的相关性和一致性,并均显示出约1个干涉条纹,相当于沿kd 雷达视线方向的地表位移在空间尺度上呈相对总量为28.3mm的分布;而具有短时间跨度(0.5-la)的同震干涉图呈现出显著的反映地震形变的干涉条纹(9-10个条纹),相当于沿雷达视线方向的地表位移在空间尺度上呈相对总量为25.5-28.3cm的分布,这些由干涉处理所得到的形变观测结果与GPS测量结果吻合程度很高(相关系数达0.95),证实了干涉形变精度可达1cm.特别地,这些高分辨率的同震形变干涉结果可以为该地震的物理机制解释提供极好的观测数据,同时也展示了使用短波段InSAR监测长时间累积的微小震前地表位移是可能的.     

滇中昆阳群刺穿构造形成机制研究

从昆阳群内刺穿构造时、究分布特征出发，详细研究刺穿体边界特征及其性质，体内物质组成与结构、构造和变质变形特点。分析地质高孔隙流体作用在刺穿构造发生和成长中的地位和作用，提出地层高孔隙流体压力的波动和局部作用是导致刺穿的重要因素，逆冲推覆断裂作用应是继因民组地层岩石水力破裂、破裂作用之后所发生。昆阳群刺穿构造经历了本区地壳岩石圈由拉张体制下的张性破裂、断裂（刺穿）过程向挤压体制下的缩短、增厚过程的转化演化。最后，建立了刺穿构造形成的构造物理过程演化模型。     

腾冲火山区的地震层析成像及其构造意义

利用滇西南临时台网和固定台站的地震数据反演了腾冲及邻近地区的P波速度结构,着重分析了腾冲火山区和龙陵7级地震震源区的地壳结构特点.研究结果表明,腾冲火山区下方10～20 km深度范围存在明显的低速区,其横向尺度大约在20～30 km之间;推测这一低速区代表了仍处于活动状态的壳内岩浆源,热流通道有可能通过腾冲断裂延伸至地...     

基于改进LAMBDA方法的PSInSAR相位解缠

相位解缠是PSInSAR技术的一个重要环节,本文提出了一种基于谱修正迭代法改进的LAMBDA方法,用于PSInSAR的相位解缠.新算法使得LAMBDA方法在不需要确定伪观测值的情况下,也可成功进行相位解缠,从而避免了伪观测值选取时的不确定性及由此引入的误差.本文先从理论上分别介绍了LAMBDA方法和基于谱修正迭代法改进...     

岩石受力红外与微波辐射变化机理及地应力遥感关键问题

地应力遥感是遥感科学的新范式,是打开地震遥感预测大门的金钥匙;岩石受力附加电磁辐射的产生机理、感知模型及定量分离是地应力遥感的理论基础。本文简要回顾了地震红外及微波遥感异常研究的历程,系统梳理了固体力学中电磁辐射实验观测的研究成果,包括材料应力与损伤的热像分析、岩石受力破裂过程的红外成像观测、红外波谱辐射观测及微波辐射观测。系统总结了岩石受力电磁辐射变化机理研究的代表性成果,包括矿物晶体压电效应、裂纹尖端放电效应、自由电子逃逸效应、孤立系统能量平衡等岩石物理机制;分析了岩石受力附加电磁辐射变化的量子力学机理,包括晶体原子振动能级跃迁及矿物分子转动能级跃迁;讨论了岩石介电常数变化效应、地表发射率变化效应等遥感物理机制。结合地应力变化驱动下的地球系统耦合现象,分析了地壳岩体电流激发效应、地下氡气逸出效应的原理与不足,总结提出了地球系统地震响应的多尺度性。最后,面向中国地球物理卫星重大计划,提出了地应力遥感亟待突破的三大关键问题,即地应力遥感卫星的波段优选与组合配置、构造活动及地震前兆的遥感识别与复合诊断、地应力响应现象的协同观测与智能分析。