短周期密集台阵被动源地震探测技术研究进展

近十年来,短周期密集台阵被动源探测技术日益成长为国内外深部结构探测领域的一项重要手段.该技术相较于传统宽频带地震探测具有高分辨、省时省钱、绿色环保等优点.尽管低频信号不足,对岩石圈地幔以深结构探测能力有限,但密集的台站间距使得地壳精细结构成像成为可能;台阵下方不同方位射线形成密集的交叉覆盖,从而可通过反演和叠加偏移等手段获取稳定的壳幔结构图像.因此,短周期密集台阵探测技术已广泛应用于深部速度和界面结构成像,以及矿产资源勘查、火山活动监测、微震精定位、发震断层的几何学和运动学特征研究等多种不同领域.本文系统的总结了短周期密集台阵在地壳结构研究和微震定位检测等方面的研究进展.展望未来,以科学问题为导向,利用天然地震及背景噪声观测、重力测量、InSAR数据、GPS测量等多种地球物理数据,开展联合反演和成像,并提取研究对象的多属性特征正日益成为减少解的非唯一性、揭示地质体真实赋存状态的有效途径;该领域方法技术的迅速提升有望大大促进地震学及地球动力学研究,在深部结构成像、矿产资源勘查等领域具有广阔应用前景.     

多通道置信传播算法的核线影像密集匹配

针对航空核线影像的稠密匹配问题,该文提出了一种基于控制点与RGB三色置信传播模型的多通道置信传播算法。该算法利用点特征匹配算子提取影像的部分同名点作为区域控制点,随后将RGB 3个颜色分量都作为置信传播模型的独立基础变量,同时增加邻域像素点对的颜色差异的贡献。两组核线影像匹配实验结果表明,所提算法在使用较少参数的情况下,降低了同名点存在颜色差异造成的干扰,利用置信传播原理提高了同名点的匹配正确率,能有效进行航空核线影像的逐像素密集匹配。     

栉孔扇贝血细胞的显微和超微结构

通过光镜、扫描电镜和透射电镜观察栉孔扇贝Chlamys farreri血细胞的形态、结构特征,对其分类进行了初步研究。根据细胞的大小、形态和结构特征可将血细胞分成5种类型:Ⅰ型小透明细胞,大小约2.44±0.11μm,约占45%—50%;Ⅱ型大透明细胞,大小约4.83±0.28μm,约占15%—20%;Ⅲ型小颗粒细胞,大小约4.07±0.15μm,约占15%—20%;Ⅳ型中颗粒细胞,大小约7.20±0.26μm,约占20%—25%和Ⅴ型大颗粒细胞,大小约13.87±0.73μm,约占3%—5%。血细胞在血淋巴中的平均密度为(3.03±0.11)×107cell.ml—1,其中颗粒细胞占42.6%,透明细胞占57.4%。透射电镜观察结果表明,颗粒细胞的细胞质颗粒可区分成3种类型:Ⅰ型高电子密度颗粒,Ⅱ型低电子密度颗粒和Ⅲ型中等电子密度颗粒。     

CBERS02B卫星CCD传感器数据反演陆地气溶胶

研究利用CBERS02B卫星的CCD传感器数据反演陆地气溶胶的方法。采用的方法是暗像元法。具体步骤为: 根据地面采集的植被光谱数据, 结合CCD传感器特点, 建立浓密植被(暗像元)红蓝波段(CCD传感器的第三和第一波段)反射率与地表反射率之间的关系, 确定了暗像元识别的阈值, 讨论气溶胶光学厚度对暗像元识别的影响以及消除这种影响的方法; 利用6S进行辐射传输运算, 构建查找表; 根据CBERS02B卫星的CCD传感器数据, 从查找表插值得到气溶胶光学厚度, 并进行了算法的误差分析。用广西南宁市及北京地区附近的两景数据进行了实际的反演试验, 使用MODIS的气溶胶产品与反演结果进行比对。结果显示, CBERS02B卫星的CCD传感器数据能够较好的反演陆地气溶胶。     

Pycnonuclear burning of 34Ne in accreting neutron stars

We study the pycnonuclear burning of ³⁴Ne in the inner crust of an accreting neutron star. We show that the associated energy production rate can be calculated analytically for any arbitrary temporal variability of the mass accretion rate. We argue that the theoretical time-scale for ³⁴Ne burning is currently very uncertain and ranges from a fraction of a millisecond to a few years. The fastest allowable burning may change the composition of the accreted crust while the slowest burning leads to a time-independent nuclear energy generation rate for a variable accretion. The results are important for constructing self-consistent models of the accreted crust and deep crustal heating in neutron stars which enter soft X-ray transients.     

Cross‐sectional profiles of sand ripples,megaripples, and dunes: a method for discriminating between formational mechanisms

Cross‐sectional profiles of sand ripples, megaripples, and sand dunes provide a useful tool for discriminating between formation by ripple and dune processes. Feature width, defined as the basal break in slope along the profile to either side of the crest, represents a good standard for comparison of profile attributes across more than three orders of magnitude. Aspect ratio (height/width) as a function of log width separates measurements into clusters representing differing mechanisms of formation. Scaling both height and distance for individual profiles by feature width facilitates comparison of profile shapes across three orders of magnitude in width. The data presented here should prove useful for evaluating possible mechanisms of origin for aeolian features observed remotely, including on planetary bodies. Copyright © 2012 John Wiley & Sons, Ltd.     

Two-fluid models of superfluid neutron star cores

Both relativistic and non-relativistic two-fluid models of neutron star cores are constructed, using the constrained variational formalism developed by Brandon Carter and co-workers. We consider a mixture of superfluid neutrons and superconducting protons at zero temperature, taking into account mutual entrainment effects. Leptons, which affect the interior composition of the neutron star and contribute to the pressure, are also included. We provide the analytic expression of the Lagrangian density of the system, the so-called master function, from which the dynamical equations can be obtained. All the microscopic parameters of the models are calculated consistently using the non-relativistic nuclear energy density functional theory. For comparison, we have also considered relativistic mean field models. The correspondence between relativistic and non-relativistic hydrodynamical models is discussed in the framework of the recently developed 4D covariant formalism of Newtonian multifluid hydrodynamics. We have shown that entrainment effects can be interpreted in terms of dynamical effective masses that are larger in the relativistic case than in the Newtonian case. With the nuclear models considered in this work, we have found that the neutron relativistic effective mass is even greater than the bare neutron mass in the liquid core of neutron stars.