L&R航空重力仪摆杆尺度因子的确定与分析   总被引：2，自引：0，他引：2  

孙中苗  夏哲仁  李迎春 《武汉大学学报(信息科学版)》2002,27(4):367-371

讨论了K因子的实验确定方法，基于重力仪检测平台的检测数据和航空重力测量实测数据，分析了K因子对计算结果的影响。  相似文献   

成像光谱仪分光技术概览   总被引：28，自引：0，他引：28  

郑玉权  禹秉熙 《遥感学报》2002,6(1):75-80

论文介绍了多种成像光谱仪的分光技术。棱镜或光栅色散型成像光谱仪技术成熟，应用广泛；在发散光束中使用光栅的方法，克服了准直光束用法中的一些缺陷；傅里叶变换光谱仪是遥感探测可见和红外弱辐射的有力工具；光楔成橡光谱仪结构简单，随着渐变滤光片工艺技术的成熟，已走向实用化；采用可调谐滤光片的成像光谱仪由于滤光片水平的限制，投入应用还有待时日；采用二元光学元件的成像光谱仪结构紧凑，体积小，扫描速度快，已研制出地面实用型产品；层析成像光谱仪原理新，目前还处在实验阶段；三维成像光谱仪可以同时获取二维影像和一维光谱信息，可实现对迅变目标的观测。  相似文献   

攀枝花数字地震台网建设的技术难点及其应对措施     

杨晓源 《四川地震》2004,(3):6-9,5

攀枝花数字地震台网是一个采用全无线传输方式的地方台网。唯一可资利用的大黑山中继站电磁干扰强烈和部分子台传输路径条件差是该台网设计建设中最大的技术难点。避、滤、纠是在攀枝花台网设计建设中采取的三大应对措施，要点是避开密集而强烈的干扰、在接收机中用多种方法滤除干扰、应用具有高编码增益的前向差错控制技术纠正已出现的误码。通过避、滤、纠使地震波形数据的高质量无线传输在攀枝花特有的恶劣环境中得以实现。  相似文献   

Assimilation de données dans un modèle d'écosystème marin de la mer Ligure     

Stéphanie Magri  Pierre Brasseur  Geneviève Lacroix 《Comptes Rendus Geoscience》2005,337(12):1065-1074

The objective is to explore the potentialities of sequential statistical estimation methods to assimilate observations in a primary production biological model coupled to a vertical 1D hydrodynamical model characterised by a k–l turbulent closure. The assimilation method is derived from the SEEK filter (Singular Evolutive Extended Kalman filter), which uses an error subspace represented by multivariate empirical orthogonal functions (EOFs). Real data assimilation experiments collected at sea have been realised to reconstruct the variability of the Ligurian Sea ecosystem during the FRONTAL field experiment. To cite this article: S. Magri et al., C. R. Geoscience 337 (2005).  相似文献   

Modelling the variability of heat flow due to the random thermal conductivity of the crust     

Kirti Srivastava 《Geophysical Journal International》2005,160(2):776-782

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地震数据采集系统延迟时研究与分析   总被引：2，自引：0，他引：2  

罗兰兵  董世学 《吉林大学学报(地球科学版)》2005,(Z1)

详细介绍了地震采集系统延迟时的因素,并根据系统的理论对产生的原因进行了论证。同时对实际生产中的测试方法进行了研究和分析;最后提出了新的测试方法,并对实际生产提出了合理的建议,取得了预期的效果。  相似文献   

Experimental investigation of runoff reduction and sediment removal by vegetated filter strips   总被引：2，自引：0，他引：2  

Majed Abu‐Zreig  Ramesh P. Rudra  Manon N. Lalonde  Hugh R. Whiteley  Narinder K. Kaushik 《水文研究》2004,18(11):2029-2037

The impact of vegetated filter strips (VFS) on sediment removal from runoff has been studied extensively in recent years. Vegetation is believed to increase water infiltration and decrease water turbulence thus enhancing sediment deposition within filter media. In the study reported here, field experiments have been conducted to examine the efficiency of vegetated filter strips for sediment removal from cropland runoff. Twenty filters with varying length, slope and vegetated cover were used under simulated runoff conditions with an average sediment concentration of 2700 mg/L. The filters were 2, 5, 10 and 15 m long with a slope of 2·3 and 5% and three types of vegetation. Three other strips with bare soil were used as a control. The experimental results showed that the average sediment trapping efficiency of all filters was 84% and ranging from 68% in a 2‐m filter to as high as 98% in a 15‐m long filter compared with only 25% for the control. The length of filter has been found to be the predominant factor affecting sediment deposition in VFS up to 10 m. Increasing filter length to 15 m did not improve sediment trapping efficiency under the present experimental conditions. The rate of incoming flow and vegetation cover percentage has a secondary effect on sediment deposition in VFS. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

用活性碳纤维滤布富集分离氢醌容量法测定金   总被引：3，自引：0，他引：3  

张汝生  邱宏喜  薛光 《黄金地质》2004,10(4):84-87

在封闭式水浴溶样器中,采取 HNO3-NH4HF2-KMnO4-NaCl体系溶矿.拟定用新型过滤材料C活性纤维滤布为吸附体制备吸附柱,抽滤吸附富集分离氢醌容量法测定Au.C活性纤维滤布以纤维做骨架,增加了C活性的表面积,使该吸附体对Au的吸附率达99.6%.C活性纤维滤布强度大,在转移及灰化过程中不易损失,能避免样品分析过程中因此带来的误差,方法的RSD≤1.68%.与C活性富集分离法相比,具有操作简单快速,成本低,准确度高等优点.  相似文献   

Diatom-based inference models and reconstructions revisited: methods and transformations   总被引：3，自引：7，他引：3  

Dörte Köster  Julien M. J. Racca  Reinhard Pienitz 《Journal of Paleolimnology》2004,32(3):233-246

Different calibration methods and data manipulations are being employed for quantitative paleoenvironmental reconstructions, but are rarely compared using the same data. Here, we compare several diatom-based models [weighted averaging (WA), weighted averaging with tolerance-downweighting (WAT), weighted averaging partial least squares, artificial neural networks (ANN) and Gaussian logit regression (GLR)] in different situations of data manipulation. We tested whether log-transformation of environmental gradients and square-root transformation of species data improved the predictive abilities and the reconstruction capabilities of the different calibration methods and discussed them in regard to species response models along environmental gradients. Using a calibration data set from New England, we showed that all methods adequately modelled the variables pH, alkalinity and total phosphorus (TP), as indicated by similar root mean square errors of prediction. However, WAT had lower performance statistics than simple WA and showed some unusual values in reconstruction, but setting a minimum tolerance for the modern species, such as available in the new computer program C² version 1.4, resolved these problems. Validation with the instrumental record from Walden Pond (Massachusetts, USA) showed that WA and WAT reconstructed most closely pH and that GLR reconstructions showed the best agreement with measured alkalinity, whereas ANN and GLR models were superior in reconstructing the secondary gradient variable TP. Log-transformation of environmental gradients improved model performance for alkalinity, but not much for TP. While square-root transformation of species data improved the performance of the ANN models, they did not affect the WA models. Untransformed species data resulted in better accordance of the TP inferences with the instrumental record using WA, indicating that, in some cases, ecological information encoded in the modern and fossil species data might be lost by square-root transformation. Thus it may be useful to consider different species data transformations for different environmental reconstructions. This study showed that the tested methods are equally suitable for the reconstruction of parameters that mainly control the diatom assemblages, but that ANN and GLR may be superior in modelling a secondary gradient variable. For example, ANN and GLR may be advantageous for modelling lake nutrient levels in North America, where TP gradients are relatively short.  相似文献   

Coherent-state analysis of the seismic head wave problem: an overcomplete representation and its relationship to rays and beams     

C. J. Thomson 《Geophysical Journal International》2004,157(3):1189-1205

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