Effects of light exposure on the TL dating of pottery     

LI Shenghua  MIAO Jianmin 《中国科学D辑(英文版)》2001,44(11):1038-1042

Bleaching experiments on Chinese pottery fine grains were conducted under sunlight and laboratory light conditions. It is found that the thermoluminescence (TL) at high temperatures can be bleached significantly, but no effects were observed on TL signals used for the pre-dose dating technique. It is concluded that the pre-dose dating technique can be applied to samples even after light exposures. Pottery samples of Tang Dynasty and New Stone Age were studied. Modifications to routine pre-dose dating technique are proposed with adding preheat procedures and using saturation exponential fitting for the sensitivity change data. The modified technique can extend the dating range to New Stone Age.  相似文献   

22°晕的光强度和颜色分布          下载免费PDF全文

胡波 《大气科学》1995,19(6):741-746

本文首次提出了22°晕的折射—衍射理论，计算了几种冰晶大小平均值ā和标准差σ情况下22°晕的径向光强度分布和色品坐标，给出了相对光强度曲线和色品曲线。探讨了冰晶大小及其分布对22°晕光强度和颜色分布的影响。理论计算的22°晕光强度分布与实测结果基本相符。事实上，22°晕是一种折射—衍射晕。  相似文献   

透水航空摄影曝光因子的确定     

戴勇书  汤晓涛 《测绘学院学报》1995,(1)

曝光因子的确定是航空摄影中的一个关键技术。本文根据透水航空摄影的特点，推导了海底景物的亮度模型，在分析曝光因素的基础上，提出了由海底景物亮度计算曝光时间的方法，实践证明，该方法是可行的。  相似文献   

采卤对接井钻井技术的研究          下载免费PDF全文

周铁芳  赵建亚  向军文  盛彦钧 《探矿工程》1995,(1):6-10,17

为了改变岩盐矿单井水溶采卤和其它采卤方法的缺点，采用螺杆钻受控定向钻控技术，使两口中曲率半径大斜度向井在盐层中交叉对接，实现对接井水溶采卤。本文，着重介绍对接井施工新技术及对接井试验研究结果。  相似文献   

影响粘土静止侧压力的一些问题   总被引：10，自引：0，他引：10  

李作勤 《岩土力学》1995,16(1):9-16

本文讨论了土的物理属性，应力历史，结构特性、土骨架的流变性质以及测量时采用的应力－应变路径等对静止侧压力的影响，最后，说明了对不同土实在实施Ｋ０值的测定时应注意的问题及对测试设备的要求。  相似文献   

评论硝板天日晒盐与“原地化学反应池”          下载免费PDF全文

宣之强 《盐湖研究》1995,(1)

开采３０００多年历史的世界级著名山西运城盐湖及其遗留下的人造矿层─硝板和硝板天日晒盐的奥秘已被中国著名学者蔡克勤、扬长辛及柴继光等人探明，瑞士籍卓有成就的国际地质学家许靖华教授提出的“原地化学反应池”专利其原理与硝板天日晒盐有惊人相似之处，值得人们探求“原地化学反应池”在开发盐湖资源中的应用前途．  相似文献   

Performance of the stereoscopic system of the HEGRA imaging air erenkov telescopes: Monte Carlo simulations and observations     

《Astroparticle Physics》1999,10(4):886

Based on the Monte Carlo simulations we have studied the performance of the HEGRA system of imaging air erenkov telescopes (IACTs) in its present configuration of 4 IACTs as well as in its future final configuration of 5 IACTs. Here we present the results on the basic characteristics of the IACT system which are used in the standard data analysis procedure, i.e., the collection areas, the detection rates, the angular resolution, the energy resolution, and the γ/hadron-separation efficiency. By comparing several key Monte Carlo predictions with experimental results it is possible to check the accuracy of the simulations. The Monte Carlo results concerning hadron-nuclear showers are tested with the recorded cosmic ray events and the results concerning photon-induced showers are tested with a large data sample of γ-rays observed from BL Lac object Mkn 501 during its high flaring activity in 1997. Summarizing the simulations and current observations we give the basic recommendations of using the instrument and the major values of its sensitivity.  相似文献   

Possible shallow crustal shear wave anisotropy off Lofoten, Norway, inferred from three-component ocean-bottom seismographs     

Rolf Mjelde  Markvard A. Sellevoll 《Geophysical Journal International》1993,115(1):159-167

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扶壁式及L式挡土墙的模型土压力试验   总被引：3，自引：0，他引：3  

魏元友 《岩土力学》1994,15(1):20-27

汇总分析了扶壁式墙和Ｌ型墙等多种结构模型，在填干砂、湿砂、砂中灌水、水中填砂等不同条件下进行试验，得到扶壁式墙立板和底板土压力减少的分布规律，提出了比较合理的土压力近似计算公式和简易的计算图式，并对有关算例进行了分析  相似文献   

黔中铝土矿及其赤泥中钪的某些特征   总被引：9，自引：3，他引：9  

肖金凯  雷剑泉 《矿物学报》1994,14(4):388-393

本文论述了黔中铝土矿和其紧密伴生硬质粘土岩及其炼铝残渣赤泥中的钪和稀土元素含量与分布特征，通过淋滤实验、酸处理实验、人工合成方钠石及电子探针分析等手段，探讨了钪在赤泥中的赋存特征。  相似文献