蒙城地震台地磁核旋观测数据b值初步分析     

曹志磊  周琼  张有林  成业明  汪继林  薛志明  郎孝龄 《地震地磁观测与研究》2009,30(1):64-69

利用蒙城地震台地磁核旋观测资料,进行b值统计分析,得出了其短期、长期以及周期性变化基本规律。与华东地区中强震做震例对应分析,结果表明,该台b值异常可能具有孕震效应,对中强震具有一定的预测意义。  相似文献   

NDVI spatial pattern and its differentiation on the Mongolian Plateau     

ZHANG Xue-Yan  HU Yun-Feng  PENG Da-Fang  JI Yong-Qing  MA Xin 《地理学报》2009,30(4):403-415

GIMMS NDVI database and geo-statistics were used to depict the spatial distribution and temporal stability of NDVI on the Mongolian Plateau.The results demonstrated that:(1) Regions of interest with high NDVI indices were distributed primarily in forested mountainous regions of the east and the north,areas with low NDVI indices were primarily distributed in the Gobi desert regions of the west and the southwest,and areas with moderate NDVI values were mainly distributed in a middle steppe strap from northwest to southeast.(2) The maximum NDVI values maintained for the past 22 years showed little variation.The average NDVI variance coefficient for the 22-year period was 15.2%.(3) NDVI distribution and vegetation cover showed spatial autocorrelations on a global scale.NDVI patterns from the vegetation cover also demonstrated anisotropy;a higher positive spatial correlation was indicated in a NW-SE direction,which suggested that vegetation cover in a NW-SE direction maintained increased integrity,and vegetation assemblage was mainly distributed in the same specific direction.(4) The NDVI spatial distribution was mainly controlled by structural factors,88.7% of the total spatial variation was influenced by structural and 11.3% by random factors.And the global autocorrelation distance was 1178 km,and the average vegetation patch length(NW-SE) to width(NE-SW) ratio was approximately 2.4:1.0.  相似文献   

蒙古高原NDVI的空间格局及分异   总被引：5，自引：2，他引：3  

张雪艳  胡云锋  庄大方  齐永清  马欣 《地理学报(英文版)》2009,19(4):403-415

GIMMS NDVI database and geo-statistics were used to depict the spatial distribu-tion and temporal stability of NDVI on the Mongolian Plateau. The results demonstrated that: (1) Regions of interest with high NDVI indices were distributed primarily in forested moun-tainous regions of the east and the north, areas with low NDVI indices were primarily distrib-uted in the Gobi desert regions of the west and the southwest, and areas with moderate NDVI values were mainly distributed in a middle steppe strap from northwest to southeast. (2) The maximum NDVI values maintained for the past 22 years showed little variation. The average NDVI variance coefficient for the 22-year period was 15.2%. (3) NDVI distribution and vege-tation cover showed spatial autocorrelations on a global scale. NDVI patterns from the vegetation cover also demonstrated anisotropy; a higher positive spatial correlation was in-dicated in a NW-SE direction, which suggested that vegetation cover in a NW-SE direction maintained increased integrity, and vegetation assemblage was mainly distributed in the same specific direction. (4) The NDVl spatial distribution was mainly controlled by structural factors, 88.7% of the total spatial variation was influenced by structural and 11.3% by random factors. And the global autocorrelation distance was 1178 km, and the average vegetation patch length (NW-SE) to width (NE-SW) ratio was approximately 2.4:1.0.  相似文献   

泉州湾及邻近海湾潮间带底质若干项数据的计算机分析     

陈世希  王渊源 《台湾海峡》1998,17(1):29-33

本文将１９８４－１９８５年进行的全国海岸带综合调查中“福建省潮间带生物调查”中有关泉州湾与邻近海湾的底质温、盐和粒径组成等调查数据利用计算机的数据库软件进行统计、绘图和分析,以便于今后的检索、查询和利用。统计结果表明,该海域潮间带具有暖水性为主的亚热带海岸特点。底盐受区域的淡水径流影响,变质中砾石滩为有机物的贫脊区,红树林滩为有机物的富含区。  相似文献   

基于双谱幅值和相位重构的地震子波提取          下载免费PDF全文

李亚峻  李月  高颖 《地球物理学进展》2007,22(3):947-952

利用地震记录双谱中包含子波的幅值和相位信息，以及其超强的抗噪声干扰能力，采用一种基于双谱幅值和相位重构的地震子波提取方法，首先提取出子波幅值及相位信息，进而通过傅立叶反变换，使子波得以完全恢复.本文针对双谱相位重构递推公式，提出一种新的初值选取方法，使地震子波估计的稳定性得到了提高.仿真实验证实了该方法的可行性.  相似文献   

高阶统计量在探地雷达数据处理中的应用     

谢尚平  张阔 《物探与化探》2012,(1):122-125,132

用高阶统计量方法对探地雷达数据进行处理,基本思路是采用信号识别与检测中的高阶统计量参数,对不同模型的探地雷达数据记录进行处理与重构,结果表明不同模型具有不同阶数的高阶统计量特征。模型实验与实际应用都表明,高阶统计量对压制背景噪声和多次反射波有较好的效果。  相似文献   

Alteration Mechanisms of Chromian-Spinel during Serpentinization at Wadi Sifein Area, Eastern Desert, Egypt   总被引：1，自引：0，他引：1  

Khalil I. Khalil    Ahmed M. El-Makky   《Resource Geology》2009,59(2):194-211

Wadi Sifein podiform chromite deposits, Central Eastern Desert of Egypt, are hosted by fully serpentinized peridotite that is a part of the dismembered Pan‐African ophiolite complexes. Relics of primary minerals and the chemical characters indicate that the ophiolitic rocks were derived from depleted mantle peridotite of harzburgite and subordinate dunite compositions. The mantle rocks were initially formed at a mid‐oceanic ridge and subsequently thrust at a supra‐subduction zone. The chromite mineralization at Wadi Sifein area displays either pod‐shaped bodies with massive and lumpy chromitite appearance or dissemination of chromian‐spinel in serpentinite matrix. The podiform chromitite exhibits a very limited compositional range in terms of Cr# [Cr/(Cr + Al) atomic ratio] and Mg# [Mg/(Mg + Fe) atomic ratio]. The chromian‐spinel, however, frequently displays optical and geochemical zoning. Four zones can be identified from core to edge: inner core representing the original composition of the chromian‐spinel; narrow Cr‐rich ferritchromit zone; wide ferritchromit zone; and outer Cr‐magnetite/magnetite zone. The zonation of chromian‐spinel is interpreted to be a result of serpentinization rather than magmatic or metamorphic processes. The geochemical data obtained from the chromitite and chromian‐spinel was statistically processed using discriminant and R‐mode factor analyses. Two trends, minor and major, were achieved considering the formation of ferritchromit. The minor trend is controlled by the redistribution of trivalent cations, where Cr₂O₃ increased on the expense mainly of Al₂O₃ and to less extent Fe₂O₃ to form zone II during the peak of serpentinization. The major trend of alteration, however, is explained by the exchange between Mg‐Fe²⁺ rather than Cr, Al, and Fe³⁺ to form zone III. Kammererite formation was accompanied the formation of zones III and IV at a 314°C temperature of formation.  相似文献   

气候概率分布理论及其应用新进展   总被引：6，自引：3，他引：3  

丁裕国  申红艳  江志红  张金铃 《气象科技》2009,37(3):257-262

随着全球变暖加剧,气候变化的研究不断深入,有关气候概率分布理论及其应用研究不但增加了许多新的内涵,而且有了长足的发展。文章从观测资料的分布拟合,气候概率分布的形成机制,气候变化的标志,即气候概率分布的变化、全球气候变化背景下的气候极值分布模式以及气候变量的空间域概率分布模式等方面简要综述了近年来气候概率分布理论及其应用领域的若干新进展。  相似文献   

Estimating the redshift distribution of photometric galaxy samples – II. Applications and tests of a new method     

Carlos E. Cunha  Marcos Lima  Hiroaki Oyaizu  Joshua Frieman  Huan Lin 《Monthly notices of the Royal Astronomical Society》2009,396(4):2379-2398

In Lima et al. we presented a new method for estimating the redshift distribution,   N ( z )  , of a photometric galaxy sample, using photometric observables and weighted sampling from a spectroscopic subsample of the data. In this paper, we extend this method and explore various applications of it, using both simulations and real data from the Sloan Digital Sky Survey (SDSS). In addition to estimating the redshift distribution for an entire sample, the weighting method enables accurate estimates of the redshift probability distribution,   p ( z )  , for each galaxy in a photometric sample. Use of   p ( z )  in cosmological analyses can substantially reduce biases associated with traditional photometric redshifts, in which a single redshift estimate is associated with each galaxy. The weighting procedure also naturally indicates which galaxies in the photometric sample are expected to have accurate redshift estimates, namely those that lie in regions of photometric-observable space that are well sampled by the spectroscopic subsample. In addition to providing a method that has some advantages over standard photo- z estimates, the weights method can also be used in conjunction with photo- z estimates e.g. by providing improved estimation of   N ( z )  via deconvolution of   N ( z _phot)  and improved estimates of photo- z scatter and bias. We present a publicly available   p ( z )  catalogue for ∼78 million SDSS DR7 galaxies.  相似文献   

Environmental effects on satellite galaxies: the link between concentration, size and colour profile   总被引：1，自引：0，他引：1  

Simone M. Weinmann  Guinevere Kauffmann  Frank C. van den Bosch  Anna Pasquali  Daniel H. McIntosh  Houjun Mo  Xiaohu Yang  Yicheng Guo 《Monthly notices of the Royal Astronomical Society》2009,394(3):1213-1228

Using the Sloan Digital Sky Survey Data Release 4 group catalogue of Yang et al., we investigate sizes, concentrations, colour gradients and surface brightness profiles of central and satellite galaxies. We compare central and satellite galaxies at fixed stellar mass, in order to disentangle environmental from stellar mass dependencies. Early- and late-type galaxies are defined according to concentration. We find that at fixed stellar mass, late-type satellite galaxies have smaller radii and larger concentrations than late-type central galaxies. No such differences are found for early-type galaxies. We have also constructed surface brightness and colour profiles for the central and satellite galaxies in our sample. We find that late-type satellite galaxies have a lower surface brightness and redder colours than late-type central galaxies. We show that all observed differences between satellite and central galaxies can be explained by a simple fading model, in which the star formation in the disc decreases over time-scales of 2–3 Gyr after a galaxy becomes a satellite. Processes that induce strong morphological changes (e.g. harassment) and processes that strip the galaxy of its entire interstellar medium need not to be invoked in order to explain the environmental dependencies we find.  相似文献