Use of high-resolution X-ray computed tomography and 3D image analysis to quantify mineral dissemination and pore space in oxide copper ore particles

Mineral dissemination and pore space distribution in ore particles are important features that influence heap leaching performance. To quantify the mineral dissemination and pore space distribution of an ore particle, a cylindrical copper oxide ore sample (φ4.6 mm×5.6 mm) was scanned using high-resolution X-ray computed tomography (HRXCT), a nondestructive imaging technology, at a spatial resolution of 4.85 μm. Combined with three-dimensional (3D) image analysis techniques, the main mineral phases and pore space were segmented and the volume fraction of each phase was calculated. In addition, the mass fraction of each mineral phase was estimated and the result was validated with that obtained using traditional techniques. Furthermore, the pore phase features, including the pore size distribution, pore surface area, pore fractal dimension, pore centerline, and the pore connectivity, were investigated quantitatively. The pore space analysis results indicate that the pore size distribution closely fits a log-normal distribution and that the pore space morphology is complicated, with a large surface area and low connectivity. This study demonstrates that the combination of HRXCT and 3D image analysis is an effective tool for acquiring 3D mineralogical and pore structural data.     

Rate of decay in admixture linkage disequilibrium and its implication in gene mapping

Modeling linkage disequilibria (LD) between genes usually observed in admixed natural populations has been shown an effective approach in high-resolution mapping of disease genes in humans. A prerequisite to obtain accurate estimation of recombination fraction between genes at a marker locus and the disease locus using the approach is a reliable prediction of the proportion of the admixture populations. The present study suggested the use of gene frequencies to predict the estimate of the admixture proportion based on the observation that the gene frequencies are much more stable quantities than the haplotype frequencies over evolution of the population. In this paper, we advanced the theory and methods by which the decay rate of nonlinear term of LD in admixed population may be used to estimate the recombination fraction between the genes. Theoretical analysis and simulation study indicate that, the larger the difference of gene frequencies between parental populations and the more closely the admixture proportion approaches 0.5, the more important the nonlinear term of the LD in the admixed population, and hence the more informative such admixed populations in the high-resolution gene mapping practice.     

资源一号02C星数据在土地利用分类中的应用

以资源一号02C星的2.36mHRC和10mMUX影像为数据源,根据试验区特点进行数据预处理,得到同时具有多光谱和高分辨率特征的影像,采用面向对象的分类方法进行土地利用分类,总结资源一号02C星的数据特点及应用潜力。结果显示:Pansharp融合法能有效保持02C影像的空间和光谱信息;面向对象的分类方法能充分利用02C高分辨率融合影像具有的丰富光谱、形状、纹理等特征信息,总体分类精度达到93.04%,Kappa系数达到0.89,结果优于传统基于像元的分类法。表明资源一号02C影像能较好地应用于土地利用宏观监测。     

A novel photoluminescent and photochromic europium complex

A ternary europium complex of 4-aminobutyric acid (ABA) with 1,10-phenanthroline (phen) [Eu₂(ABA)₄ (phen)₄](phen)₄(ClO₄)₆ was synthesized and characterized by X-ray single crystal diffraction. The result shows that 4-aminobutyric acid exists in zwitterion form in the binuclear complex and that the carboxylates coordinate with Eu³⁺ ion in bidentate bridging and tridentate chelating-bridging modes. There are two types of phen molecules, one is coordinated and the other is uncoordinated. When excited by YAG︰Nd laser with 355 nm light, the title complex can emit strong red fluorescence, and its high-resolution emission spectrum was recorded at 77 K. The Eu³⁺ ion site is in low symmetry, which is in agreement with the result of X-ray single crystal diffraction analysis. When irradiated with a mercury lamp, the aqueous solution of the title complex can perform photochromism with the color change from colorless to green and the green color can fade away in the dark. The photochromic response time is related to the concentration and pH of the solution, the temperature and the light intensity.     

城市居住单元建筑拥挤度环境遥感分析——以厦门市为例

居住单元的建筑拥挤度是居住单元环境评价的重要方面,而高分辨率卫星影像所提供的丰富的细节化的空间信息使得从居住单元的尺度研究建筑拥挤度成为可能。结合房地产估价理论和地统计学中的半变异函数方法,基于高分辨率遥感影像的特点创造性地构建了4个指标用来评价居住单元的建筑拥挤度,并选取了厦门市的5个典型居住单元对这些指标的可用性进行了检验。结果表明上述4个指标能很好地从不同角度刻画建筑拥挤度,为高分辨率遥感在环境评价中的应用提供了新的方向。     

基于改进波束域MUSIC算法的高分辨方位估计

波束域MUSIC算法在波束域高分辨目标方位估计算法中是最具代表性的方法。和阵元域处理相比,波束域处理具有计算量小、分辨信噪比门限低的优点。文中论及窄带信号的波达方向估计问题,提出了高分辨处理的一种改进的波束域MUSIC算法。仿真计算表明,这种改进算法改进了信号的分辨信噪比门限。     

黄骅坳陷港中地区沙二段高分辨率层序地层格架与沉积体系分布

应用T A.Cross高分辨率层序地层学理论,并综合运用地震、测井、岩心和分析化验资料,将港中地区古近系沙河街划分为5个长期基准面旋回、10个中期基准面旋回和41个短期基准面旋回。其中重点层位沙二段包括1个长期基准面旋回、3个中期基准面旋回和15个短期基准面旋回。长期旋回层序结构类型以向上变深再变浅的对称的C型结构为主,中短期旋回层序结构类型是以向上变深的A型或向上变浅的B型非对称型为主。识别出古近系沙二段主要发育3种沉积相类型:近岸水下扇、重力流水道和湖泊沉积,包括11种沉积微相;沙二段MSC3和MSC4时期,物源主要来自于西部的港西古凸起,至MSC5时期,物源方向由单一西部方向转为多方向物源供应。辫状重力流水道全都发育在近岸水下扇的前方,充足的物源供应是重力流水道发育的首要因素;辫状重力流水道的发育及分布与沉积期的古地貌有关,而断阶式断槽是港中地区古地貌的主要特征,因此,断阶式断槽是控制沙二段辫状重力流水道分布的主要因素。     

利用图象序列来重建高分辨率图象

在许多应用中,需要细节很丰富的图象.但是仅仅通过硬件设备(CCDs),通常得不到这样的高分辨率图象.所以要用图象处理的方法来重构一个高分辨率图象其中的一个做法就是通过一个低分辨率的图象序列来重构高分辨率图象.其中要解决的两个问题是图象序列中图象的配准及重建.本文给出了一种基于曲面拟合的图象配准重建算法来解决这个问题.试验结果验证了该方法的有效性.     

OFD-LFM信号体制MIMO雷达运动目标HRRP合成方法

针对OFD-LFM信号体制MIMO雷达运动目标的高分辨距离像(HRRP)合成问题展开了相关的研究工作,首先给出了OFD-LFM信号体制MIMO高分辨雷达成像的几何关系图,在此基础上,通过严格的理论推导和详细的原理论述,提出了基于相位补偿的OFD-LFM信号体制MIMO雷达运动目标的HRRP合成方法,该方法利用了OFD-LFM信号中各子载波信号之间的正交性,可有效地合成出运动目标的HRRP。此外,还进一步分析了HRRP不发生卷绕的条件。仿真结果证明了本文方法的有效性。