山东郯城和江苏东海早白垩世晚期恐龙足迹化石新发现及古环境^*   总被引：2，自引：0，他引：2       下载免费PDF全文

汪明伟  旷红伟  柳永清  彭楠  刘海  吴清资  徐加林  陈军  许欢 《古地理学报》2013,15(4):489-504

首次在山东郯城早白垩世晚期地层中发现恐龙足迹化石,分属蜥脚类和兽脚类恐龙足迹,足迹大小差异较大。通过对山东省郯城县新发现的2处恐龙足迹化石点和江苏省东海县南古寨恐龙足迹化石点的对比研究,探讨了足迹类型、大小、速度与足迹深度的关系,发现同等条件下,蜥脚类恐龙足迹通常较兽脚类足迹深,而蜥脚类恐龙足迹深度随着足迹大小的增加有变深的趋势;波痕、雨痕和泥裂等沉积构造以及足迹回填和叠覆现象对足迹化石保存形态和细节有较大影响,而构造变形对足迹形态和行迹并无明显影响,但高角度的构造变形会加速差异风化,使足迹化石更易暴露而被破坏。对研究区古环境与古生态的研究表明,早白垩世晚期研究区经历了水体逐渐变浅、气候由湿到干并伴随短暂间歇性干旱的过程,沉积环境由河湖演变为三角洲前缘、并逐渐过渡到三角洲平原,生态环境逐渐恶化,动植物由兴而衰、逐渐减少。  相似文献   

2017年7月23日吉林松原MS4.9地震热红外异常研究     

李梦莹  张志宏  黄明威  杨牧萍 《地震地磁观测与研究》2021,42(z1):148-150

1 研究背景 地震与热辐射的相关研究始于20世纪80年代,诸多研究有:强祖基等(1992)认为,热红外异常是,地震时构造板块间的摩擦使得岩体内的温室气体沿着断裂缝隙逸出,也称作"地球放气",惰性气体被低空电场电离后形成各种波段的红外光;马瑾等(2000)提出利用遥感技术探测活动断层的构想,并证实了1997年玛尼MS7.9地震前20 d阿尔金断裂带条带状增温异常的存在;张元生等(2011)应用中国静止气象卫星热红外遥感亮温资料,分析了2011年日本MW 9.0地震和2011年缅甸MS 7.2地震前相对功率谱存在的显著亮温变化.中国东部地区关于热红外异常的研究较少.2011年日本MW 9.0地震后,中国东北地区地震活动呈增强趋势.2017年7月,吉林松原地区发生MS 4.9地震,对此次地震前热红外异常特征进行分析,以便为地震预测相关研究提供参考.  相似文献   

Camera calibration from profile of revolution     

Zheng Shunyi  Yang Ling  Sun Mingwei 《地球空间信息科学学报》2013,16(1):38-44

This paper focuses on the problem of calibrating a pinhole camera from images of profile of a revolution. In this paper, the symmetry of images of profiles of revolution has been extensively exploited and a practical and accurate technique of camera calibration from profiles alone has been developed. Compared with traditional techniques for camera calibration, for instance, it may involve taking images of some precisely machined calibration pattern (such as a calibration grid), or edge detection for determining vanish points which are often far from images center or even do not physically exist or calculation of fundamental matrix and Kruppa equations which can be numerically unstable, the method presented here uses just profiles of revolution, which are commonly found in daily life (e. g. bowls and vases), to make the process easier as a result of the reduced cost and increased accessibility of the calibration objects. This paper firstly analyzes the relationship between the symmetry property of profile of revolution and the intrinsic parameters of a camera, and then shows how to use images of profile of revolution to provide enough information for determining intrinsic parameters. During the process, high-accurate profile extraction algorithm has also been used. Finally, results from real data are presented, demonstrating the efficiency and accuracy of the proposed methods.  相似文献   

地磁Z分量日变形态畸变与周边低点位移异常关系初探     

李西京  陈俊  刘红飞  徐苏红  曾宪军  薛志明  汪继林  李雪华  李明威 《地震地磁观测与研究》2012,33(Z1)

通过对2010年1月1日至2011年12月31日期间中国大陆地磁低点位移异常数据及蒙城地震台地磁垂直分量日变形态畸变统计,按低点位移分界线到蒙城地震台的距离,分段探讨该台地磁垂直分量日变形态畸变与其周边低点位移异常的关系.  相似文献   

爆破地震效应及其对附近建筑物影响因素的探讨     

李庆武  李明威  袁国旭  孙彭涛  任峻峰  鞠永  于艳红  李万里 《高原地震》2012,(4):70-72

根据工作实践,围绕爆破地震效应及其对附近建筑物的影响因素进行了探讨和分析,阐明了爆破地震效应影响附近建筑物的因素,有助于减少爆破危害,对生产过程中的爆破工作具有一定的参考意义。  相似文献   

Uncertainty and variability in bivariate modeling of hydrological droughts   总被引：2，自引：1，他引：1  

Xinjun Tu  Xiaohong Chen  Mingwei Ma  Qiang Zhang  Yong Zhao 《Stochastic Environmental Research and Risk Assessment (SERRA)》2016,30(5):1317-1334

There are two kinds of uncertainty factors in modeling the bivariate distribution of hydrological droughts: the alteration of predefined critical ratios for pooling droughts and excluding minor droughts and the temporal variability of univariate and/or bivariate characteristics of droughts due to the impact of human activities. Daily flow data covering a period of 56 hydrological years from two gauging stations from a humid region in South China are used. The influences of alterations of threshold values of flow and critical ratios of pooling droughts and excluding minor droughts on drought properties are analyzed. Six conventional univariate models and three Archimedean copulas are employed to fit the marginal and joint distributions of drought properties, the Kolmogorov–Smirnov and Anderson–Darling methods are used for testing the goodness-of-fit of the univariate model, and the Cramer-von Mises method based on Rosenblatt’s transform is applied for the test of the bivariate model. The change point analysis of the copula parameter of bivariate distribution of droughts is first made. Results demonstrate that both the statistical characteristics of each drought property and their bivariate joint distributions are sensitive to the critical ratio of excluding minor droughts. A model can be selected to fit the marginal distribution for drought deficit volume or maximum deficit, but it is not determined for drought duration with the lower ratios of the pooling and excluding droughts. The statistical uncertainty of drought duration makes the modeling of bivariate joint distribution of drought duration and deficit volume or of drought duration and maximum deficit undermined. Change points significantly occurred in the period from the late 1970s to the middle 1980s for a single drought property and the copula parameter of their joint distribution due to the impact of human activities. The difference between two subseries separated by the change point is remarkable in the magnitudes of drought properties and the joint return periods. A copula function can be selected to optimally fit the bivariate distribution, provided that the critical ratios of pooling and excluding droughts are great enough such as the optimal value of 0.4 in the case study. It is valuable that the modeling and designing of the bivariate joint correlation and distribution of drought properties can be performed on the subseries separated by the change point of the copula parameter.  相似文献   

An insight into the Palmer drought mechanism based indices: comprehensive comparison of their strengths and limitations   总被引：2，自引：2，他引：0  

Yi Liu  Liliang Ren  Mingwei Ma  Xiaoli Yang  Fei Yuan  Shanhu Jiang 《Stochastic Environmental Research and Risk Assessment (SERRA)》2016,30(1):119-136

Considering the drawbacks of the original Palmer drought severity index (PDSI) in terms of its simplified hydrologic algorithm and spatio-temporal inconsistency, we compare six variants of PDSI derived from different combinations of two hydrologic algorithms and three standard processes so as to provide deep insights into the individual impacts of hydrological processing and standardization on final PDSI values as well as their combined effects. Investigations are conducted in whole Yellow River basin. On basis of 52 years’ (1961–2012) hydro-meteorological data, comprehensive analysis on multiple drought characteristics are carried out for each PDSI variant, combined with comparison of three crucial intermediate variables of PDSI. Results show that variable infiltration capacity (VIC) model based modification in the hydrologic accounting section significantly improve drought trends with more reasonable spatial distributions presented. For the statistical characteristics of drought areas and frequency, comparable performance is found between VIC-based modification and self-calibrating standard procedure-based modification, though they are derived from different mechanisms. However, in case of the coupling of these two modifications, indices derived from combined modifications perform poorly than single modification-based indices with unexpected high frequency of extreme events detected in certain regions. This reflects the complicated mechanism of PDSI and it is essential to propose an appropriate standardization to match the hydrological algorithm and further improve the performance of relevant drought index. With the crucial findings mentioned above, this study is promising to provide some theoretical supports and serve as a competent reference for future PDSI based researches.  相似文献   

基于SCIAMACHY反演数据的全球CO2浓度时空变化特征研究     

赵明伟  李晨晨  张兴赢  王春  江岭  孙京禄 《气候变化研究进展》2017,13(2):95-102

通过卫星观测光谱反演计算是当前观测全球CO₂浓度水平,分析其变化趋势的重要手段,但是由于观测条件及反演方法的限制,基于卫星观测光谱反演计算只能得到离散的CO₂浓度数据,需要借助空间插值方法才能获得空间连续的CO₂浓度数据。本文以SCIAMACHY研究团队发布的XCO₂浓度数据为基础数据,首先对比分析了空间分析中常用的3种经典插值方法（反距离加权法,克里格法,样条函数法）在XCO₂空间内插中的精度,综合分析平均绝对值误差、绝对值误差最大值和均方根误差3个指标,结果表明反距离加权插值法为最优内插方法。基于该方法生成2003年1月-2012年4月共计112个月的全球大陆XCO₂浓度分布数据集,并对全球大陆范围内XCO₂浓度的时空变化特征进行分析,发现在此时段内全球各个大陆XCO₂均表现出增加的趋势;在全球大陆平均水平上,XCO₂浓度增加幅度为17.43×10^-6,XCO₂年平均值增加速率约为2×10^-6,总体上呈现北半球增加速率高于南半球的特点。  相似文献   

Grain size characteristics of surface sediment and its response to the dynamic sedimentary environment in Qiantang Estuary,China   总被引：2，自引：0，他引：2  

Shanshan Wang  Cunhong Pan  Dongfeng Xie  Mingwei Xu  Yuhan Yan  Xinwen Li 《国际泥沙研究》2022,37(4):457-468

The composition and grain size characteristics of sediment in estuarine and coastal environments provide important information on the material source, hydrodynamic environment, environmental events,etc. However, few studies have focused on the sediment characteristics of the entire Qiantang Estuary,particularly, on the correlation between hydrodynamics and sediment properties. Through systematic sampling of the surface sediment in a large area of the Qiantang Estuary, the spatial distribution ch...  相似文献   

基于街景影像的城市道路空间舒适度研究     

杨灿灿  许芳年  江岭  王瑞璠  尹力  赵明伟  张鲜鲜 《地球信息科学学报》2021,23(5):785-801

城市道路空间舒适度是综合刻画城市道路环境的量化指标之一,可为城市道路规划建设、城市交通优化、城市环境评估等提供参考.本文以街景影像为基础数据,从空间视角阐述了城市道路空间舒适度内涵,构建了城市道路空间舒适度量化指标,建立了以语义分割和等距采样为基础的城市道路空间舒适度测度方法和空间插值方法,最后以南京市局部城区为样区进...  相似文献