宁夏地区近震震级短周期量规函数的研究与修正

选取宁夏"十五"宽频带数字地震台网2009年1月—2016年12月的1 782个地震事件、7 345条地震记录资料,通过震级残差统计和多元回归分析计算各台站单台震级与台网平均震级的偏差、平均偏差和标准偏差,分析震级偏差的频次分布,修正M_L量规函数,得到宁夏地区的地方性均匀震级量规函数和台基改正量。且采用多元回归分析方法,得到最大地动位移的衰减关系及与之对应的量规函数。结果表明,修正后的震级均方差由原来的0.237 0降低为0.228 9,震级修正最大值为0.51。     

合肥地区超压密粉土-砂层的性状与地基评价

本文论述了合肥地区超压密粉土—砂层的分布及其物理力这性质。通过多种方法计算对比,综合确定了地基承载力与桩的端阻力。认为可以作为中高层建筑的桩基或箱（筏）基持力层。并对地层时代归属作了探讨。     

时-空局域化地震波传播方法:Dreamlet叠前深度偏移

提出了一种在时间和空间上完全局域化的波场分解和传播算法─dreamlet偏移方法.Dreamlet是一种脉冲-小波束形式的波场分解原子,它利用多维局部分解变换,把时空域波场映射到局部时间-频率-空间-波数相空间,并用局部相空间的传播算子(dreamlet算子)沿深度延拓.本文利用多维局部余弦变换实现dreamlet算法,分解后的波场系数和传播算子不仅有很好的稀疏性,且均为实数,也即波的传播和成像过程完全在实数域实现.文中推导了局部余弦基dreamlet波场分解和传播算子理论公式并将其应用于叠前深度偏移.在dreamlet相空间波的传播过程为稀疏矩阵相乘,而且延拓后的地表数据波场的有效时间长度随深度的增加不断减小,从而可以减少需要传播的波场系数.二维SEG/EAGE盐丘和SIGSBEE模型算例验证了理论推导的正确性,成像结果显示该方法在横向速度变化剧烈情况下有很好的精度.     

THE MOST PERFECT EXAMPLE OF AN ALIEN ECOLOGY EVER CONSTRUCTED

Much science-fiction literature is based upon the creation and exploration of alternative environments. Stanley G. Weinbaum's short story, “Parasite Planet,”introduces an unusual environment that may be wrong in the light of recent evidence on Venus but still stimulates the geographical imagination.     

2014年云南鲁甸6.5级、永善5.0级地震前岩石圈磁场局部异常特征分析

利用2012 ～2014年南北地震带3期流动地磁矢量测量的准确可靠资料,计算得到了2012 ～2013年和2013～ 2014年相邻期岩石圈磁场的分布.分析结果表明,2014年8月3日鲁甸6.5级地震、8月17日永善5.0级地震前,川滇交界东部均存在岩石圈磁场的异常变化.同时,异常持续时间、空间范围与震级大小有一定关系,鲁甸地震前岩石圈磁场异常持续时间长、空间范围广,而永善地震则反之.     

光学卫星摄影无控定位精度分析

"全球连续覆盖"和"局部区域覆盖"是卫星摄影测量常用的两种摄影模式,两种模式应用目标和无控定位实现途径也各有特点。本文简要介绍了两种模式典型的卫星无控定位精度情况,阐述了光束法平差的关键技术,重点对前方交会和光束法平差无控定位精度进行试验分析。试验结果表明,姿态误差是影响无控定位精度的重要因素,影像分辨率对其影响较小。当外方位角元素误差大于0.5″时,即使影像分辨率为5m,光束法平差后,其无控定位精度也优于0.5m分辨率影像前方交会精度。     

钻探工程在气化采煤压裂试验钻孔中的应用

通过内蒙古通辽地区气化采煤压裂试验钻孔施工实例,全面介绍了岩心钻探设备及技术在大口径钻探工程中的成功应用。并对保证钻孔垂直度、全孔下套管、造穴等特殊工艺和要求所采取的技术措施进行了重点总结。     

浙闽丘陵区土壤侵蚀影响因素与防治对策研究

通过对浙-闽丘陵区土壤侵蚀现状调查、分析研究,揭示了浙-闽丘陵区土壤侵蚀的严重性,提出了浙-闽丘陵区土壤侵蚀的主要影响因素:降雨条件;地形;地表松散的堆积物;植被的覆盖程度。降雨丰富且集中,山高坡陡,地表易流失的土壤,植被的严重破坏等,为该地区的土壤侵蚀提供了条件。最后,本文提出了浙-闽丘陵区土壤侵蚀防治对策应以生物措施为主,生物、工程、耕作密切结合。生物措施主要为植树种草;工程措施是改变小地形,以达到蓄水、保土的目的;耕作措施主要是改变乱开荒的做法,摒弃不合理的耕作方式,禁止陡坡开垦。不同地区应根据实地情况合理防治,采用小流域综合治理。不仅要根据影响因素来制定防治对策,也应该因地制宜。     

Towards realistic flow modelling. Creation and evaluation of two-dimensional simulated porous media: An image analysis approach

This work is part of an attempt to quantify the relationship between the permeability tensor (K) and the micro-structure of natural porous media. A brief account is first provided of popular theories used to relate the micro-structure toK. Reasons for the lack of predictive power and restricted generality of current models are discussed. An alternative is an empirically based implicit model whereinK is expressed as a consequence of a few pore-types arising from the dynamics of depositional processes. The analytical form of that implicit model arises from evidence of universal association between pore-type and throat size in sandstones and carbonates. An explicit model, relying on the local change of scale technique is then addressed. That explicit model allows, from knowledge of the three-dimensional micro-geometry to calculateK explicitly without having recourse to any constitutive assumptions. The predictive and general character of the explicit model is underlined. The relevance of the change of scale technique is recalled to be contingent on the availability of rock-like three-dimensional synthetic media. A random stationary ergodic process is developed, that allows us to generate three-dimensional synthetic media from a two-dimensional autocorrelation functionr( _x , _y ) and associated probability density function measured on a single binary image. The focus of this work is to ensure the rock-like character of those synthetic media. This is done first through a direct approach:n two-dimensional synthetic media, derived from single set ( ,r( _x , _y )) yieldn permeability tensorsK _i-1,n ⁱ (calculated by the local change of scale) of the same order. This is a necessary condition to ensure thatr( _x , _y ) and carry all structural information relevant toK. The limits of this direct approach, in terms of required Central Process Unit time and Memory is underlined, raising the need for an alternative. This is done by comparing the pore-type content of a sandstone sample andn synthetic media derived fromr( _x , _y ) and measured on that sandstone-sample. Achievement of a good match ensures that the synthetic media comprise the fundamental structural level of all natural sandstones, that is a domainal structure of well-packed clusters of grains bounded by loose-packed pores.     

一种大视场星图星点提取的阈值算法

确定区分星点与背景的阈值是星空图像处理的重要环节。介绍了根据背景灰度统计特征确定阈值的算法,根据星空图像灰度直方图的走势,提出一种基于灰度直方图的阈值算法;通过对实际拍摄大视场星图的处理,基于统计的阈值容易将亮背景中的亮噪声误认为星点提取,而基于直方图的阈值能够滤除这些噪点;针对星图中星点亮度不一的情况,提出在全局阈值的基础上应用Bernsen算法计算局部阈值提取暗星点,实验证明该算法能较充分地提取暗星图像。