北京大学AMS ¹⁴ C 国际比对样品测量^*   总被引：1，自引：0，他引：1       下载免费PDF全文

刘克新  丁杏芳  傅东坡  潘岩  吴小红  周力平  郭之虞 《第四纪研究》2007,27(3):469-473

介绍了北京大学加速器质谱(AMS)实验室参加国际原子能机构 (IAEA) 组织的第五届¹⁴ C国际比对样品测量的过程和结果,包括样品制备、小型¹⁴ C测量加速器质谱计装置和比对测量结果的统计分析等。北京大学的测量结果与IAEA加权统计平均值的偏差在1σ之内, 这一结果较客观地体现了我国¹⁴ C AMS年代测定在国际同类实验室中所处的地位。  相似文献   

Cosmogenic Be inferred lake-level changes in Sumxi Co basin, Western Tibet     

Ping Kong  Chunguang Na  David Fink  Feixin Huang  Lin Ding 《Journal of Asian Earth Sciences》2007,29(5-6):698-703

Most Tibetan lakes are surrounded by conspicuous regressive shorelines attesting to high-water levels in the past. Concentrations of the in situ produced cosmogenic radionuclide ¹⁰Be in bedrock from the three highest terraces surrounding Sumxi Co, situated in Western Kunlun, indicate that the highest lake-level appeared before 10,000–11,500 yr, and most likely between 11,000 and 12,800 yr. Younger ages for the two lower terraces imply regression of Sumxi Co during the early-mid Holocene. The concurrency of the highest lake-level with orbitally induced maximum northern hemisphere summer insolation suggests that the increase in water supply to Sumxi Co was most likely associated with increased recharge from melting glaciers. We conclude that the enhanced Indian monsoon during the early Holocene did not penetrate the Tibetan plateau and affect the northwestern part of Tibet significantly.  相似文献   

北京市地震台网"速度震级"与仿真震级的关系     

丁晗  马士振  张伟  王占英  白永福  乔永军 《地震地磁观测与研究》2007,28(3):43-47

速度型记录设备的地震速报,一般直接使用记录到的波形数据计算震级(速度震级).编写台网观测报告,需要把速度波形仿真成位移后再计算震级(仿真震级).本文利用北京市地震台网2003年以来1 000多条记录,以全网、单台两种方式研究了上述两种震级的关系,结果表明.它们之间存在很好的线性关系,且与震中距、台基、设备等因素有关.建议在速报阶段,可用震级差和线性关系两种方法对仿真震级进行估计.  相似文献   

Single epoch ambiguity resolution for Galileo with the CAR and LAMBDA methods   总被引：3，自引：3，他引：3  

Shengyue Ji  Wu Chen  Chunmei Zhao  Xiaoli Ding  Yongqi Chen 《GPS Solutions》2007,11(4):259-268

This paper investigates single epoch ambiguity resolution performance using Galileo four frequency data. Two commonly used ambiguity resolution methods are used in the tests, including the Cascade Ambiguity Resolution (CAR) and the Least-Squares Ambiguity Decorrelation Adjustment (LAMBDA) methods. For CAR method, four optimal combinations are carefully selected according to their wavelength to noise ratios and success rate for ambiguity fixing. The test results show, in general, the LAMBDA method performs better than the CAR method. The speed of ambiguity resolution is closely related to the carrier phase measurement precision. With carrier phase measurement precision of 3 mm, single epoch ambiguity resolution can be achieved at every epoch with simulated 1-s interval 24-h Galileo data (total epochs 86,400). With the increase of carrier phase noise, ambiguity resolution performances become worse. When the noise level is increased to 12 mm, single epoch ambiguity resolution can only be achieved about 50% of epochs.  相似文献   

India-Eurasian collision vs. ocean-continent collision＊     

曾融生吴庆举  丁志峰朱露培 《地震学报(英文版)》2007,20(1):1-10

Introduction Major tectonic activities occur in collisions zones between plates or intra-plate continental blocks. Therefore, it is significant to investigate collision processes. We know that orogenic and seismic belts in plate margins are closely relate…  相似文献   

文件系统监视及其在大震速报台的应用   总被引：1，自引：1，他引：1  

杨世英  丁小牛  孟彩菊  靳玉贞  赵春华 《地震地磁观测与研究》2007,28(6):91-95

针对太原基准地震台大震速报事件触发报警存在的问题,编写了《FTP扫描及文件监视程序》.该程序采用Visual Basic 2005开发环境,实现了FTP扫描、文件监视、语音报警、电话告知等功能,使速报台报警功能得到改善,减轻了值班人员的工作强度.本文对程序功能原理及实现方法做了简要的介绍.  相似文献   

河北邢台余震窗地震活动对华北地区6级以上地震的预测反应   总被引：1，自引：0，他引：1  

薛丁  曹刚  纪建国 《山西地震》2007,(2):13-15

文中简要介绍了1966年河北邢台地震发震的构造背景。在选取合理的地震参数确立余震窗后,分析了余震窗地震月频次的变化特征对研究华北地区6级以上地震的反应。发现,余震活动出现月频次过程异常对应华北地区6级地震成组活动或震群活动;单点高值频次异常则对应单发6级地震。  相似文献   

Plant Response to Metal Contamination at an Oil Shale Tailing Site in Maoming, South China     

Aizhong Ding  Lirong Cheng  Puxin Liu  Philip J. Carpenter  Yanguo Teng 《Ground Water Monitoring & Remediation》2007,27(3):111-117

  相似文献   

湿润气候区无资料站点土壤湿度插补及预报试验   总被引：1，自引：1，他引：1  

彭小燕  刘晶淼  丁裕国 《气象科学》2007,27(4):400-406

利用前期降水指数法(API)并结合水量平衡方程提出一种土壤湿度的初始化方案,将所建模型用于湿润气候区无资料站点的土壤湿度插补与预报试验,证明其应用的可行性。  相似文献   

Erosion in northwest Tibet from in‐situ‐produced cosmogenic 10Be and 26Al in bedrock     

Ping Kong  Chunguang Na  David Fink  Lin Ding  Feixin Huang 《地球表面变化过程与地形》2007,32(1):116-125

Concentrations of in‐situ‐produced cosmogenic nuclides ¹⁰Be and ²⁶Al in quartz were measured by accelerator mass spectrometry for bedrock basalts and sandstones located in northwest Tibet. The effective exposure ages range between 23 and 134 ka (¹⁰Be) and erosion rates between 4·0 and 24 mm ka^?1. The erosion rates are significantly higher than those in similarly arid Antarctica and Australia, ranging between 0·1 and 1 mm ka^?1, suggesting that precipitation is not the major control of erosion of landforms. Comparison of erosion rates in arid regions with contrasting tectonic activities suggests that tectonic activity plays a more important role in controlling long‐term erosion rates. The obtained erosion rates are, however, significantly lower than the denudation rate of 3000–6000 mm ka^?1 beginning at c. 5‐3 Ma in the nearby Godwin Austen (K2) determined by apatite fission‐track thermochronology. It appears that the difference in erosion rates within different time intervals is indicative of increased tectonic activity at c. 5–3 Ma in northwest Tibet. We explain the low erosion rates determined in this study as reflecting reduced tectonic activity in the last million years. A model of localized thinning of the mantle beneath northwest Tibet may account for the sudden increased tectonic activity at c. 5–3 Ma and the later decrease. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献