Scale Transitions in Fracture and Active Fault Networks     

Thomas H. Wilson 《Mathematical Geology》2001,33(5):591-613

Detailed box counting analysis was conducted of (1) fractures observed in exposures of the Devonian Shale in the central Appalachians Valley and Ridge Province of West Virginia, (2) several fracture patterns presented in the literature, and (3) active faults mapped throughout the main island (Honshu) of Japan. Box curves reveal, with few exceptions, that most naturally occurring fracture patterns are characterized by nonfractal behavior. In many cases, two linear regions separated by an abrupt transition are observed in the logN/logr box curves. The small-scale (larger r) features generally have higher fractal dimension than do the larger scale features in the pattern. Transitions from one region to another are usually abrupt. These transitions are not associated with sampling problems or other data limitations. In some cases three or more linear regions may appear. Box counting analysis of model fracture patterns indicate that transitions are related to the dominant spacing of individual sets or to the dominant fragment size in the network. This study provides detailed documentation of scale invariant features in natural fracture and active fault patterns. Although the relationship of the geometrical properties of a pattern to the location of transitions is understood in terms of the models, to understand the physical mechanisms responsible for these transitions deserves further study.  相似文献   

Discrimination of reworked pyroclastics from primary tephra-fall tuffs: a case study using kimberlites of Fort a la Corne, Saskatchewan, Canada     

Kevin Leahy 《Bulletin of Volcanology》1997,59(1):65-71

 Reworked volcaniclastics are traditionally discriminated from primary tephra-fall pyroclastics by an absence of features such as blanketing, juvenile lapilli, grain welding and poor sorting. Frequently, these features are difficult to identify, especially in small outcrops, ancient or altered successions, debris flows and surge deposits. Crystal-rich volcaniclastics, such as kimberlites, have a large proportion of coarse euhedral crystals, and abrasion leading to rounding can be recognised and classified with relative ease. A petrographic method of discriminating reworked material has been devised, based on the degree of grain roundness, and is illustrated using volcaniclastic kimberlite from Fort a la Corne, Saskatchewan, Canada. Petrographic thin sections of samples at regular intervals throughout the borehole core, and from a nearby crater-facies kimberlite, show that the percentages of rounded, subrounded and euhedral grains define two distinct groupings. The first group contains a higher percentage of euhedral grains and includes all the samples from the basal 4.8 m of the 14.1-m-thick kimberlite section in borehole 004, and all of the crater facies tephra-fall tuffs. A second group contains more rounded, subrounded and fragmental grains and includes all the data from the upper 6.3 m, which are interpreted as reworked strata. Thus, point counting concurs with hand-sample interpretation and may be used as a verification tool in discriminating reworked pyroclastic sands from primary tephra-fall tuffs. Received: 27 August 1996 / Accepted: 31 May 1997  相似文献   

由主厂房建立建筑坐标系统方法的研究     

奚毓敏 《现代测绘》2003,26(4):18-21

本文对由主厂房建立建筑坐标系统方法进行归纳总结，对应用中应引起重视的技术问题进行了深入研究，并给出了解决方案，这对提高精度和防止出错是非常重要的。同时指出极坐标方法二中的计算错误所在及其本质，应停止使用。  相似文献   

云南天文台新型斑点象探测系统   总被引：1，自引：0，他引：1  

卢汝为  王锋  楼柯  邱耀辉  刘忠 《天文研究与技术》1998,(1)

斑点成象技术能有效地消除地球大气湍流的不良影响,实现地基大型天文望远镜的衍射受限分辨率成象,其所需的原始数据是天文目标及参考星的一系列的短曝光斑点象,它们取自望远镜的终端设备：斑点象探测系统。文中对比该技术对原始数据的要求：介绍了云南天文台研制的新型斑点象探测系统的结构和性能。实际观测结果表明,该系统基本能满足要求。  相似文献   

地下水^32硅年龄的测定方法—液体闪烁计数法   总被引：1，自引：0，他引：1  

周炼  刘存富  王佩仪 《岩矿测试》2000,19(2):97-100

用Fe(OH) 3共沉淀从天然水中提取纯化SiO2 ,回收率在 30 %～ 98% ,然后提取32 P ,将H3PO4溶液和PicoflourLLT混合制备计数溶液 ,用液体闪烁计数法测量32 P的放射性 ,计算32 Si的放射性浓度 ,最后确定地下水的年龄。通过对河北平原浅层地下水的32 Si年龄进行测定 ,所得的32 Si年龄为 92 9 89a± 1 7 87a,与1 4 C的校正年龄一致  相似文献   

基于浓缩法的浮游植物定量数据稳定性与可靠性分析   总被引：1，自引：1，他引：0  

牛海玉  陈纯  韩博平 《湖泊科学》2015,27(5):776-782

浮游植物是水生生态系统中重要的初级生产者,相对准确地定量它们的数量是进一步进行水质评价和生态功能分析的基础.通过采集处于不同营养状态的水库和不同处理的围隔中的浮游植物,研究影响浓缩法定量浮游植物的因素,了解如何通过浓缩法来合理地定量浮游植物.分析浓缩倍数、样品的显微镜计数量、水体营养状态对浮游植物丰度、生物量及群落多样性等定量参数稳定性的影响,同时比较单个不同水体中重复(或平行)样品之间浮游植物丰度的差别.结果表明,基于浮游植物的显微镜计数效率与定量数据稳定性的综合考虑,选择计数4片×10格/片即可基本保证定量数据的稳定性;在保证正常镜检的基础上,考虑水体营养状态适当增加浓缩倍数能够提高定量数据的可靠性;在特别依赖生物量或稀有种进行水质评价时,处于不同营养水平的水体均需要增加样品的平行数来提高定量数据的可靠性.  相似文献   

一维游标位敏阳极光子计数探测器          下载免费PDF全文

鄢秋荣  赵宝升  杨颢  刘永安  朱香平  李梅 《海洋学报》2010,32(9):6164-6171

报道了一维游标位敏阳极光子计数探测器,详细介绍了一维游标位敏阳极的解码原理和设计结果. 搭建了基于一维游标位敏阳极探测器的紫外光子计数探测系统. 该系统工作于光子计数模式,可同时测量单光子事件的一维坐标. 获得了对应入射光空间强度一维分布的脉冲计数分布图. 通过测试,系统的分辨率优于100 μm. 该探测器可以实现极微弱的高能光子、电子和离子等粒子流强度分布的一维探测,因此可以用于深空探测、光谱测量、高能物理以及生物发光探测.  相似文献   

感应读出方式紫外光子计数成像技术的研究          下载免费PDF全文

赵菲菲  赵宝升  刘永安  胡慧君  曹希斌 《海洋学报》2010,32(9):6306-6311

搭建了感应读出方式紫外光子计数成像系统,详细介绍了该系统的组成、工作原理和分辨率性能测试.紫外光经过减光和滤光后入射微通道板,产生的光电子在微通道板内倍增后形成电子云,由呈高阻特性的半导体Ge薄膜收集后,通过电荷耦合感应到Ge膜衬底背面的位敏阳极.阳极输出的信号经过电荷灵敏前置放大器、整形放大器后由计算机进行数据采集和处理,最后得到不同位置的光子计数图像.通过分辨率板,测得了该系统分辨率为150 μm,并通过对比试验和分布式RC网络理论模型分析了Ge膜电阻及其衬底厚度对系统性能的影响.该系统在生物超微  相似文献