微波炉在重量法测定硫中的应用     

姜锋  江荣燕 《岩矿测试》1993,12(2):135-136

采用玻璃砂芯坩埚过滤BaSO_4沉淀,微波炉代替马弗炉恒重坩埚、沉淀,重量法测定了矿石中的硫。方法准确,精密度好。微波炉不需预先升温,加热6min可达恒重,省时、省电。  相似文献   

Single GPS receiver time-relative positioning with loop misclosure corrections     

Nicolas Balard  Rock Santerre  Marc Cocard  Stéphanie Bourgon 《GPS Solutions》2006,10(1):56-62

Time-relative positioning makes use of observations taken at two different epochs and stations with a single global positioning system (GPS) receiver to determine the position of the unknown station with respect to the known station. The limitation of this method is the degradation over time of the positioning accuracy due to the temporal variation of GPS errors (ionospheric delay, satellite clock corrections, satellite ephemerides, and tropospheric delay). The impact of these errors is significantly reduced by adding to the one-way move from the known to the unknown station, a back move to the known station. A loop misclosure is computed from the coordinates obtained at the known station at the beginning and at the end of the loop, and is used to correct the coordinates of the unknown station. The field tests, presented in this paper, show that using the loop misclosure corrections, time-relative positioning accuracy can be improved by about 60% when using single frequency data, and by about 40% with dual frequency data. For a 4-min processing interval (an 8-min loop) and a 95% probability level, errors remain under 20 cm for the horizontal components and 36 cm for the vertical component with single frequency data; and under 11 cm for the horizontal components and 29 cm for the vertical component with dual frequency data.  相似文献   

A Reanalysis and Reinterpretation of Geodetic and Geological Evidence of Glacial-Isostatic Adjustment in the Churchill Region, Hudson Bay     

Detlef Wolf  Volker Klemann  Johann Wünsch  Fei-peng Zhang 《Surveys in Geophysics》2006,27(1):19-61

We review the historical, geological, tide-gauge, GPS and gravimetric evidence advanced in favour of, or against, continuing land uplift around Hudson Bay, Canada. We also reanalyse the tide-gauge and GPS data for Churchill using longer time series than those available to previous investigators. The dependence of the mean rate of relative sea-level change obtained from the tide-gauge record on the length and mid-epoch of the observation interval considered is investigated by means of a newly developed linear-trend analysis diagram. For studying the shorter-period variability of the tide-gauge record, the wavelet transform is used. The mean rate of land uplift obtained from GPS is based on a new analysis using IGS solutions of GFZ. To include the post-glacial land uplift, sea-level indicators from the Churchill region representing the relative sea-level history during the past 8000 years are also used. Finally, the values of the four observables are jointly inverted in terms of mantle viscosity. The optimum values are ~3.2 × 10²⁰ Pa s and ~1.6 × 10²² Pa s for the upper- and lower-mantle viscosities, respectively.  相似文献   

Turbulence Scale Dependence of the Richardson Constant in Lagrangian Stochastic Models     

A. Maurizi  G. Pagnini  F. Tampieri 《Boundary-Layer Meteorology》2006,118(1):55-68

We investigate the relative dispersion properties of the well-mixed class of Lagrangian stochastic models. Dimensional analysis shows that, given a model in the class, its properties depend solely on a non-dimensional parameter, which measures the relative weight of Lagrangian-to-Eulerian scales. This parameter is formulated in terms of Kolmogorov constants, and model properties are then studied by modifying its value in a range that contains the experimental variability. Large variations are found for the quantity, g* = 2gC₀^{− 1}, where g is the Richardson constant.  相似文献   

LaCoste&Romberg航空重力仪K因子的动态标定及其特性研究   总被引：1，自引：1，他引：1       下载免费PDF全文

孙中苗  夏哲仁  王兴涛  李迎春 《地球物理学报》2007,50(3):724-729

摆杆尺度因子（K因子）是反映LaCoste&Romberg航空重力仪线性响应特性的最重要参数. 利用基于地面参考数据的外部标定法和基于交叉点不符值的内部标定法分别对其进行了标定，实测数据分析表明，K因子的内、外部标定结果非常一致，且利用新K因子计算的空中重力扰动，其精度较采用出厂值提高了02～04 mGal. 内部标定法具有较好的实际应用价值. 研究了K因子与滤波尺度的相关性，表明重力仪可能为一非线性响应系统，即K因子的大小与摆杆速度的变化有关.  相似文献   

辽宁省区域性大雾预报研究   总被引：11，自引：0，他引：11  

蒋大凯  闵锦忠  陈传雷  孙欣  陈艳秋 《气象科学》2007,27(5):578-583

通过对1994—2002年9年辽宁区域地面图的普查,得到了辽宁区域性大雾天气(大于等于5个地市,能见度小于0.5 km)共有73次。分析近10年区域性大雾天气过程得到了区域性大雾的时空分布特征。普查区域性大雾过程发生时的常规气象资料,进行区域性大雾天气分型。分析辽宁省各种区域性大雾的成因及要素演变特征,从中提取预报指标,建立预报流程,用PP法建立区域性大雾的客观预报方法。  相似文献   

Airborne gravimetry used in precise geoid computations by ring integration   总被引：1，自引：1，他引：0  

A. H. W. Kearsley  R. Forsberg  A. Olesen  L. Bastos  K. Hehl  U. Meyer  A. Gidskehaug 《Journal of Geodesy》1998,72(10):600-605

Two detailed geoids have been computed in the region of North Jutland. The first computation used marine data in the offshore areas. For the second computation the marine data set was replaced by the sparser airborne gravity data resulting from the AGMASCO campaign of September 1996. The results of comparisons of the geoid heights at on-shore geometric control showed that the geoid heights computed from the airborne gravity data matched in precision those computed using the marine data, supporting the view that airborne techniques have enormous potential for mapping those unsurveyed areas between the land-based data and the off-shore marine or altimetrically derived data. Received: 7 July 1997 / Accepted: 22 April 1998  相似文献   

用于便携式γ射线康普顿背散射扫描仪的多道分析器研制     

杜洪  丁厚本 《CT理论与应用研究》1998,7(2):44-48

本文简介了康普顿背散射扫描仪（ＣＢＳ）的基本原理,优点,阐述了便携式ＣＢＳ的特点和对ＣＢＳ多道分析器的要求,介绍了一种多道分析器的指标,电路原理,工作过程和稳峰技术。  相似文献   

中国近45年来气候变化的研究   总被引：344，自引：7，他引：337  

陈隆勋  朱文琴  王文  周秀骥  李维亮 《气象学报》1998,56(3):257-271

利用１９５１～１９９５年约４００站的月平均气温、降水和１９６１～１９９５年２００余站的最高和最低气温、相对湿度、总云量和低云量、日照时数、蒸发、风速和积雪日数和深度以及０～３．２ｍ共８层土壤温度等资料,对近４５ａ来中国气候变化特征作了一个较全面的分析研究。本文作为第一部分,分析了平均气温、最高最低气温、降水、相对湿度和日照的气候变化规律。其余要素的变化规律以及中国气候变化的可能机制将在第二部分中加以讨论。  相似文献   

地震CT及其在采空区探测中的应用   总被引：7，自引：0，他引：7       下载免费PDF全文

王超凡  赵永贵  靳洪晓  郭鸿  李勤 《地球物理学报》1998,41(Z1):367-375

应用地震波速CT和吸收CT相结合的方法对山东省招远市界河金矿隐伏采空区进行了联合探测研究．波速CT是利用地震波走时资料反演地质体内部波速结构;吸收CT是通过能量变化观测反演吸收系数分布．地震波速对岩性敏感,吸收系数与岩石的完整性关系更密切在界河金矿采空区探测中利用地震波速和吸收系数为层析物理量,在巷道和地表间进行透射观测,以优于2m的分辨率清楚地揭示了测区内采空区和断裂破碎带的分布,探测结果已被后期的采掘所证实．探测的成功为解决同类问题提供了一种可行的方案,对促进工程地球物理探测技术的发展也有重要意义．  相似文献