Simultaneous waveform inversion for three-dimensional Earth structure and earthquake source parameters considering a wide range of modal coupling     

Tatsuhiko Hara  & Robert J. Geller 《Geophysical Journal International》2000,142(2):539-550

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关于勒让德多项式的算法问题   总被引：2，自引：0，他引：2  

张强  刘林 《紫金山天文台台刊》1996,15(4):259-283

本文讨论勒让德多项式P_1(x)和缔合勒让德多项式P_(1m)(x)的两种算法,即直接计算和递推算法,并给出相应的计算公式,当1取值较大时,也可以保证达到较高的精度。  相似文献   

数字近景摄影测量系统PV-1的几何精度     

徐青 《测绘学院学报》1991,(2)

本文系统地介绍了所建立的一个数字近景摄影测量系统PV—1的检校方法,并得出了该系统的点定位精度。初步实验表明。运用直接线性变换法进行点定位精度评定,物方坐标的中误差为:M_x=0.247mm,M_y=0.158mm,M_z=0.272mm,象方坐标的中误差为0.2像元,相对精度为1/6000。  相似文献   

交流电弧直读发射光谱法测定地球化学样品中银、硼、锡、钼、铅的方法研究   总被引：5，自引：0，他引：5  

郝志红  姚建贞  唐瑞玲  杨帆  李文阁  白金峰  张勤 《地质学报》2016,90(8):2070-2082

本文建立了交流电弧直读原子发射光谱法测定地球化学样品中银、硼、锡、钼、铅的分析方法。以K2S2O7、NaF、Al2O3、碳粉为缓冲剂,Ge为内标,优选了分析线对,曝光时间为25s,同时扣除分析线和内标线背景。选取国家一级地球化学标准物质（GBW07103、GBW07104、GBW07107、GBW07312、GBW07302a、GBW07304a、GBW07305a、GBW07307a、GBW07406、GBW07446、GBW07454、GBW07456）作为标准系列,以对数坐标二次曲线拟合标准曲线,并采取两次平行分析取平均值的计算方法。方法检出限为:Ag:0011×10-6、B:054×10-6、Sn:019×10-6、Mo:0034×10-6、Pb:066×10-6,精密度为:Ag:401%～833%、B:377%～786%、Sn:294%～817%、Mo:303%～1094%、Pb:201%～1111%。经岩石、水系沉积物、土壤国家一级标准物质验证,测定值与认定值符合。本方法操作简便、工作效率高,是一种新的测定地球化学样品中银、硼、锡、钼、铅的分析方法,可推广应用于大批量地球化学样品的分析测试。  相似文献   

基于WRF模式对华北一次飑线过程中雷电活动的间接和直接模拟研究   总被引：1，自引：1，他引：0  

赵鹏国  银燕  周筠珺  肖辉  康汉青  邓美玲 《气象科学》2017,37(3):293-303

将非感应起电机制和放电参数化方案耦合到WRF模式的Morrison双参数微物理方案中,并在模式中引入了闪电潜势指数LPI,在此基础上模拟了2009年6月16日华北一次飑线过程,讨论模式对闪电活动再现能力。模拟结果显示,模式能够较好地再现雷达回波和降水分布特征,说明模式对此次飑线过程的宏观和微观特征具有一定的模拟能力。利用计算闪电潜势指数LPI的间接模拟,能够指示出大致的闪电分布特征,但闪电潜势指数LPI分布范围明显大于实际闪电落区;而通过耦合电过程的WRF模式直接输出闪电密度的直接模拟,模拟结果与实际闪电密度分布的对应关系较好,但由于模式中输出的闪电密度为总闪电密度,与观测地闪密度资料相比,模拟的闪电密度偏大。  相似文献   

Marine seismics with a pulsed combustion source and Pseudo Noise codes     

Bjørn Askeland  Halvor Hobæk  Rolf Mjelde 《Marine Geophysical Researches》2007,28(2):109-117

There has been a long-standing debate concerning how dangerous seismic surveys are with respect to marine life. Marine seismic work today is dominated by airgun technology, where high energy is generated by a release of compressed air into the water. The objective of the “Time coded impulse seismic technique” project is to examine whether a new low energy acoustic source can be used for seismic purposes. If the method turns out to be successful, the low output energy and continuous operation will make the source suitable in environmental sensitive areas. The Low level Acoustic Combustion Source (LACS) is a petrol driven pulsed underwater acoustic source. It operates at a few meters depth, and each shot can be digitally controlled from the surface by a computer located in the mother vessel. A presentation of the recorded LACS signal characteristics, the modulation, the Pseudo Noise coding/decoding principles and field test results, is given. The importance of using an optimized code with fine resolution and of using the near field recording as a correlator sequence is demonstrated. Clear correlation peaks could then be seen from the bottom and sub bottom reflectors.  相似文献   

利用Direct3D的地形三维快速重建方法     

张钧  吴云东  张强  王慧 《海洋测绘》2005,25(3):60-62,66

在视口数据检索之后，视口重建效率成为了影响地形数据三维重建和显示速度的主要因素，视口重建与可利用的开发平台资源密切相关。在剖析Direct3D硬件访问方式的基础上，提出了一套完整的DEM快速重建方法。实验结果表明在相同的条件下，基于Direct3D的视口重建具有明显的速度优势。  相似文献   

Carbon dioxide flux techniques performed during GasEx-98   总被引：2，自引：0，他引：2  

Wade R. McGillis  James B. Edson  Jonathan D. Ware  John W. H. Dacey  Jeffrey E. Hare  Christopher W. Fairall  Rik Wanninkhof 《Marine Chemistry》2001,75(4):851

A comprehensive study of air–sea interactions focused on improving the quantification of CO₂ fluxes and gas transfer velocities was performed within a large open ocean CO₂ sink region in the North Atlantic. This study, GasEx-98, included shipboard measurements of direct covariance CO₂ fluxes, atmospheric CO₂ profiles, atmospheric DMS profiles, water column mass balances of CO₂, and measurements of deliberate SF₆–³He tracers, along with air–sea momentum, heat, and water vapor fluxes. The large air–sea differences in partial pressure of CO₂ caused by a springtime algal bloom provided high signals for accurate CO₂ flux measurements. Measurements were performed over a wind speed range of 1–16 m s⁻¹ during the three-week process study. This first comparison between the novel air-side and more conventional water column measurements of air–sea gas transfer show a general agreement between independent air–sea gas flux techniques. These new advances in open ocean air–sea gas flux measurements demonstrate the progress in the ability to quantify air–sea CO₂ fluxes on short time scales. This capability will help improve the understanding of processes controlling the air–sea fluxes, which in turn will improve our ability to make regional and global CO₂ flux estimates.  相似文献   

确定震源位置,发震时刻及区域平均波速的最优化方法     

聂永安  冯德益 《地震研究》1992,15(4):373-380

本文详细讨论了利用井下和地面观测直达波到时资料联合确定震源位置,发震时刻及区域平均波速的最优化方法,该方法对震源深度及波速的确定给予特别的重视与处理。理论检验和实际算例表明,用该方法编制的程序定位精度高,计算速度快,可以在地层差异小的地区推广应用。  相似文献   

Impact of coherent neutrino nucleus scattering on direct dark matter searches based on CaWO4 crystals     

《Astroparticle Physics》2015

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