Intercalibration of international and domestic ~(40)Ar/~(39)Ar dating standards

40Ar/39Ar method is a high precision dating means, of which the age is obtained by contrasting the un- known sample with those of standards. Usually the age of standard is determined by K-Ar method in which the 38Ar spike should be added for measurement. However, the absolute concentration of 38Ar spike is measured through the calibrated standards in turn, al- though occasionally the concentration of 38Ar spike is determined by other dating methods, such as Rb-Sr, U-Pb methods, which is kn…     

Application of ensemble kalman filter to geophysical parameters retrieval in remote sensing:A case study of kernel-driven BRDF model inversion

Remote sensing can provide multi-spatial resolution, multi-temporal resolution multi-spectral band and multi-angular data for the observation of land surface. At present, one of research focuses is how to make the best of these data to retrieve geophysical parameters in conjunction with their a priori knowledge and simul-taneously consider the influence of data uncertainties on inversion results[1-5]. The essence of remote sensing lies in inversion. It is difficult to precisely retrieve parame…     

Intercalibration of international and domestic 40Ar/39Ar dating standards

Four international standards, Ga1550, MMhb-1, Lp-6, Bem 4M, and one domestic standard BT-1 have been intercalibrated. The repeated measurements on MMhb-1 with different mass demonstrate that MMhb-1 is inhomogeneous in age and its average age is 519.8 Ma. The results of Bern 4M and Lp-6 reflect that they have an invariable value of ⁴⁰Ar*/³⁹Ar_k (F) and the ages we obtained are consensus with their K-Ar age: Lp-6=127.7Ma; Bern 4M=18.2 Ma. Analyses of BT-1 age spectra, Ca/K and Cl/K spectra as well as inverse isochrons indicate that the sample is homogeneous and invariable and keeps close chemically, with its trapped argon isotope composition close to the atmosphere. The dating results show that age values are reproducible and steady, total fusion age, step-heating age, plateau age and isochron age are in accord with each other within the error range (2σ). Therefore, we recommend 28.7 Ma as the calibrated age of BT-1. We also discuss the variation in neutron flux gradients of Beijing 49-2 reactor. It was found that the neutron flux gradient varies considerably, and more monitors (standard samples) are needed to fix the trend of variation. The coefficient of the 49-2 reactor that transfers the ratio of production rate of ³⁷Ar_Ca/³⁹Ar_K into Ca/K ratio is 1.78. This is different from that reported earlier, 2.0, which may be caused by the reconstruction of the reactor.     

Variations of near-surface atmospheric CO2 and H2O concentrations during summer on Muztagata

Expeditions during the summers of 2002 and 2003 implemented continuous monitoring of near-surface (2 m height) atmospheric CO₂ and H₂O concentrations at the 4500 m elevation on Muztagata. The resultant data sets reveal a slight decrease of CO₂ concentrations (of about 5 μmol·mol^-1) and changes in the diurnal variations from the end of June to the middle August. The daily maximum CO₂ concentrations occur between 02:30-05:30 AM (local time) and the minimum levels occur between 12:00-15:30 PM. The atmospheric CO₂ concentrations in the summer of 2002 were around 5 μmol·mol^-1 lower than those during the same period of 2003, whereas the diurnal amplitude was higher. In contrast, we found that the daily mean atmospheric H₂O content in 2003 was much lower than that in 2002 and there exists a striking negative correlation between CO₂ and H₂O concentrations. We therefore suggest that the near-surface atmospheric CO₂ concentration is affected not only by photosynthesis and respiration, but also by the air H₂O content in the glaciated region around Muztagata.     

Inversion of coseismic stress-triggered fault slips using borehole strainmeter observations

Coseismic stress-triggering is becoming a new hot spot of research. Coseismic strain steps recorded by borehole strainmeters are particularly valuable in studying coseismic stress-triggered fault slips. Based on the theory of dis location, one can invert the triggered fault slips with such data if he/she has a well understanding about the local faults. Genetic algorithm can be applied to significantly raise the efficiency of searching a best solution among all possibilities in this kind of inversion. A testifying check of the program and analyses of each parameter＇s influence may further enhance the reliability of inversion results. Taking complexity of geological structure into account, the inversion results should be regarded as the predominant property or a comprehensive effect of triggered local faults＇ activities. As an attempt, we inverted the assumingly active faults＇ slips triggered by the Ms=8.1 Kunlun Mountain earthquake over Beijing area.     

天津市堆山造景工程地基稳定监测与防治

堆山造景工程是一项利用建筑渣土,在坑塘上进行堆载的市政工程。通过对堆山造景工程的工程地质条件分析,结合工程设计、施工工期等条件,提出了清理淤泥、设置反压平台、排水、控制堆填速率等促进地基稳定的防治措施。利用孔隙水压力监测、侧向位移监测及分层沉降监测等原位监测数据,以复合型法进行反演力学计算参数,并将反演结果用于该工程地基稳定性的模拟,以指导后期工程以及类似工程的建设。     

基于遗传算法的叠前地震波形反演构建虚拟井曲线

叠前地震波形反演能够提供详细的地下地层特征，但由于其计算量大、数据和模型之间的非线性、目标函数的多极值和反演结果的多解性使叠前地震反演的实施成为一大难点。本文通过叠前和叠后混合反演技术采用遗传算法实现了深海无井地震反演。遗传算法思想简单、易于实现和使用、具有隐含并行性和全局搜索能力等优点，基于遗传算法的叠前地震波形反演得到了与井中实际数据基本吻合的速度和密度数据。     

中国西北地区云的分布及其变化趋势

利用1983年7月—2001年9月ISCCP D2云的月平均资料,针对西北地区15种不同类型云的分布特征进行了分析,给出了中、低云量之和以及高云量在3个气候子区的多年变化趋势,初步探讨了其形成机制。结果表明:水层云、冰层云、水雨层云、冰雨层云和深对流云的光学厚度和云水路径值最大;水层云主要出现在天山山区、北疆地区和陕西南部,冰层云主要出现在北疆地区,水雨层云、冰雨层云和深对流云以及水高层云、冰高层云、卷层云的云量高值区在天山—昆仑山—祁连山一带以及陕南和/或陇南地区,因此上述地区也是有利于人工增水作业的地区。近20年中,高云量在3个气候区都呈明显下降趋势,中、低云量之和则呈上升趋势。西北地区云与地气系统之间可能存在这样一个过程:地面气温的升高,促使地面蒸发加剧,从而导致中、低云量增多而使降水增多,同时高云云量减少。     

大地测量反演模型准外部检验的进一步探讨

给出了大地测量反演模型准外部检验的基本理论,提出了观测数据的划分方法和反演模型准外部质量控制的标准,实现了在进行反演之前对反演模型的事先检验。     

河南某石膏矿立井工作面注浆设计与施工实践

通过对河南某石膏矿立井工作面预注浆的施工，概述了注浆堵水的设计计算，施工工艺和方法的应用，以及堵水效果的检查和检验方法。