中国第四纪孢粉数据库(CPD)和生物群区(Biome 6000)   总被引：21，自引：0，他引：21  

孙湘君  陈旭东  宋长青 《地球科学进展》1999,14(4):407-411

介绍了中国第四纪花粉数据库的建立、组织及数据收集、大型成果共享等原则及章程,并着重介绍了当前由ＩＧＢＰ所支持的用孢子花粉资料重建６ｋａＢＰ及１８ｋａＢＰ生物群区（植被）的全球合作项目。到目前为止,利用中国第四纪花粉数据的原始数据及生物群区化方法已经完成中国现代表土花粉、６ｋａＢＰ（中全新世）及１８ｋａＢＰ（２０ｋａＢＰ）（末次盛冰期）的生物群区模拟及重建,在文中展示了制图结果,并讨论了当时植被与现  相似文献   

营口潍坊断裂带新生代活动的特征   总被引：38，自引：4，他引：34       下载免费PDF全文

徐杰  宋长青  高战武 《地震地质》1999,21(4):289-300

营潍断裂带以北西向北京 蓬莱断裂带与之交汇的部位为界分南北两段,北段由辫状交织的两条断裂组成;南段为并列的东西两支断裂,但被黄北、莱北和潍北等北东东向断裂横切成4节。断裂带北段早第三纪水平拉张和垂直差异活动强烈,控制了断陷盆地的发育,晚第三纪—第四纪右旋走滑活动显著。南段本身活动甚弱,但黄北等横向断裂早第三纪水平拉张和垂直差异活动强烈,相应形成了黄北等几个断陷盆地;晚第三纪—第四纪横向断裂仍有活动。断裂带活动具明显的分段性,南段是受横向断裂强烈分割、改造而被“废弃”的一段。断裂带新生代活动具由南部和北部统一向中部迁移的特点,北段还有向东侧迁移的趋势。断裂带地震活动微弱,渤海中部斜穿断裂带分布的北东向地震带,可能是黄河口聊城新生地震构造带向海区延伸的部分  相似文献   

周期基数插值对偶尺度函数和对偶小波     

朱长青 《测绘学院学报》1999,(3)

在对二维周期基数插值小波的尺度函数和小波函数研究的基础上,对二维周期基数插值小波的对偶尺度函数和对偶小波进行了研究,得到了一系列重要的结论。  相似文献   

高职工程测量技术专业"工程实践不断线"人才培养模式的创新与实践     

薄志毅  李长青  赵小平  崔有祯  高绍伟  姜晶 《测绘通报》2010,(3)

通过专业人才需求和生源调研,结合多年来教学改革实践,构建了"工程实践不断线"人才培养模式。实践表明,该模式能够与测绘专业和北京市测绘行业特点很好地结合起来,大大调动了学生学习和企业参与人才培养的积极性,促进了人才培养和就业质量的提高。  相似文献   

Spatio-temporal differentiation of spring phenology in China driven by temperatures and photoperiod from 1979 to 2018     

Wu  Xiaojing  Cheng  Changxiu  Qiao  Cancan  Song  Changqing 《中国科学:地球科学(英文版)》2020,63(10):1485-1498

Large amounts of data accumulated in ecology and related environmental sciences arouses urgent need to explore useful patterns and information in it. Here we propose coclustering-based methods and a temperatures-photoperiod driven phenological model to explore spatio-temporal differentiation in long-term spring phenology in China. First, we created the first bloom date(FBD) dataset in China from 1979 to 2018 using the extended spring indices and China Meteorological Forcing Dataset. Then we analyzed the dataset using Bregman block average co-clustering algorithm with I-divergence(BBAC_I) and kmeans algorithm. Such analysis delineated the spatially-continuous phenoregions in China for the first time. Results showed three spatial patterns of FBD in China and their temporal dynamics for 40 years(1979–2018). More specifically, overall late spring onsets occur in 1979–1996, in which areas located in Jiangxi, northern Xinjiang and middle Inner Mongolia experienced constant changing spring onsets. Overall increasingly earlier spring onsets occur in 1997–2012, in which areas located in Fujian,Hunan and eastern Heilongjiang experienced the most variable spring onsets. Stable early spring onsets over China occur after 2012. Results also showed 15 temporal patterns of spring phenology over the study period and their spatial delineation in China.More specifically, most areas in China have the same FBD category for 40 years while northern Guizhou, Hunan and southern Hubei have the same category in 1979–1997 and then fluctuate between different categories. Finally, our results have certain directive significance on the design of existing observational sites in Chinese Phenological Network.  相似文献   

An improved optical flow method to estimate Arctic sea ice velocity (winter 2014?2016)     

Haili Li  Changqing Ke  Qinghui Zhu  Xiaoyi Shen  Mengmeng Li 《海洋学报(英文版)》2021,40(12):148-160

1 Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology/Key Laboratory for Land Satellite Remote Sensing Applications of Ministry of Natural Resources, School of Geography and Ocean Science, Nanjing University, Nanjing 210023, China; 2 Collaborative Innovation Center of Novel Software Technology and Industrialization, Nanjing 210023, China; 3 Collaborative Innovation Center of South China Sea Studies, Nanjing 210023, China  相似文献   

一种基于伪随机序列和DCT的遥感影像水印算法   总被引：6，自引：0，他引：6  

朱长青  任娜 《武汉大学学报(信息科学版)》2011,36(12):1427-1429,1499

首先,对原始影像进行分块,通过伪随机序列选择要嵌入的影像块;然后,采用量化的方法在每一块的DCT低频系数中嵌入水印信息;最后,通过精度约束,对嵌入水印信息后的遥感影像进行误差控制。由于采用了量化的方法嵌入水印信息,其提取过程不需要原始影像的参与,实现了盲检测。实验结果表明,该算法在满足水印算法鲁棒性的同时,也能达到对遥感影像近乎零修改的目标。  相似文献   

Subsidence prediction method of solid backfilling mining with different filling ratios under thick unconsolidated layers     

Changqing Ma  Huaizhan Li  Peipeng Zhang 《Arabian Journal of Geosciences》2017,10(23):511

Solid backfill mining for coal pillar recovery in industrial squares has to ensure that the mine infrastructure, such as the shafts and substations, is not degraded or has its utility impaired by that mining. At the same time, it is important to recover as much coal as possible. As a result, it is necessary to predict mining subsidence during solid backfilling mining of coal pillars in industrial squares and to optimize the design of the working faces. At the Baishan coal mine in Anhiu province, China, there are thick layers of unconsolidated overburden above the coal seam so it is not appropriate to use the surface subsidence prediction method of equivalent mining height to predict subsidence during the mining of the coal pillars there. In order to find a reasonable coal pillar recovery scheme for the Baishan mine, a numerical simulation method is used to determine the relationships between the compression ratio of the backfilling material and the surface subsidence prediction parameters. Research was done to determine the appropriate parameters, and based on the final prediction parameters and taking the mandated protection standards for buildings and structures into account, surface subsidence is predicted and a backfill mining scheme for pillar recovery is proposed. The results show that of the six mining schemes considered, scheme 5 is the best scheme for coal pillar recovery in the industrial square at the Baishan mine. The research results are significant for similar mines with thick unconsolidated overburden anywhere in the world.  相似文献   

一种点约束分块的矢量地理数据精确认证算法     

任娜  吴维  朱长青 《地球信息科学学报》2015,17(2):166-171

脆弱水印可以实现对数据内容真实性的认证,并对发生变化的位置进行定位,鉴此,本文提出了一种点约束分块的矢量地理数据精确认证算法。在认证内容嵌入过程中,首先,按照点约束的方法对矢量地理数据进行分块,并将每块的数据点进行空间位置关系的“之字形”排序,建立数据点之间的位置关系;然后,将相邻点生成的脆弱水印信息嵌入到当前点。在内容精确认证时,比较原始的水印信息与提取的水印信息,判断二者是否相同来鉴别数据是否更新。将本文算法与均匀分块的方法进行了对比实验,结果表明,本文提出的认证算法能实现在数据更新时的精确认证,并可实现要素删除的精确认证,在检测数据变化时可对修改位置进行定位与标记。  相似文献   

一种面向遥感影像内容认证的多级权限管理方法     

丁凯孟  朱长青 《地球信息科学学报》2015,17(1):8-14

完整性认证是遥感影像获得有效利用的前提,完整性无法确定的遥感影像,其使用价值将大打折扣。传统认证技术没有顾及遥感影像认证过程中的特殊性,并不是所有用户都有权甄别遥感影像是否经过扰动。而且,传统认证技术对数据进行二进制级别的认证,已不能满足遥感影像的内容认证需求。本文从内容认证的角度研究遥感影像的多级权限管理,提出一种基于感知哈希技术与单向函数的遥感影像多级认证权限的管理方法。感知哈希技术能用很少的信息表征遥感影像的有效内容,并对不改变影像内容的操作保持鲁棒性,与密码学Hash函数有着显著的区别。多级权限的管理则通过建立与权限矢量对应的密钥矢量来实现,权限较高的用户可以通过自己的密钥计算出低权限用户的密钥,反之则不行。本方法首先以单向函数生成不同等级的权限密钥,然后,根据不同区域的地物影像进行敏感等级的划分,最后,计算不同区域影像的感知哈希序列,并通过不同级别的密钥加密生成的感知哈希序列。用户认证影像内容完整性时,根据权限的不同认证不同敏感度的影像。实验与分析表明,该算法能有效实现遥感影像的认证权限管理,并具有较高的实现效率和安全性。  相似文献