基于噪声谱比法的内蒙古西部地区台站场地响应研究     

张珂  王鑫  王树波  张红才  宋晓燕 《大地测量与地球动力学》2020,40(6):646-651

利用内蒙古西部12个台站的地脉动噪声数据，采用噪声谱比法研究台站的场地响应情况。分析表明，台站场地响应按曲线形态可分为3类，且可能受地形地貌、局部构造和台基状况等条件影响。对比分析噪声谱比法与Moya方法的场地响应结果发现，场地响应曲线形态基本一致，只有极少数台站存在明显差异。结果表明，内蒙古西部区域大部分台站的台基状况总体较好，场地响应曲线较为平坦，无明显频率放大点。  相似文献   

AR（P）参数估计协方差方法与其改进型方法的对比研究     

楚岩  祝轩 《地球科学与环境学报》1997,(Z1)

定性分析协方差方法及其改进型在ＡＲ（Ｐ）参数估计中的应用，提供了一种估计参数的计算机上机流程图，比较了协方差方法及其改进型谱估计结果。  相似文献   

A note on turbulent perturbations of salinity in a partially mixed estuary     

J.R. West  K. Shiono 《Estuarine, Coastal and Shelf Science》1985,20(1):55-78

Measurements of salinity perturbations in a partially mixed estuary have been used to evaluate the usefulness of an inductive salinometer and to determine some of the characteristics of the salinity perturbations. The salinometer performed satisfactorily under most conditions. Although internal wave like effects were present, the turbulence fluctuations were dominant. The salinity fluctuations and the turbulent fluxes $\text{sw}$ and $\text{su}$ were found to behave in a manner similar to the density fluctuations in a thermally stratified atmospheric boundary layer and a laboratory open channel flow. A quadrant analysis suggested that the contribution of each quadrant to the turbulent flux changed with Ri. The turbulence parameters ν and c_γ were found to decrease and increase respectively as Ri increases.  相似文献   

LAMOST/GALAXY计划:利用LAMOST研究银河系     

胡景耀 《天文研究与技术》2004,1(3):234-240

本文讨论了利用LAMOST作银河系研究的科学意义及可能性；并提出具体实施LAMOST/GAIAXY计划的初步方案。  相似文献   

The influence of macrophyte growth,typical of eutrophic conditions,on river flow velocities and turbulence production     

Pamela Naden  Ponnambalam Rameshwaran  Owen Mountford  Coralie Robertson 《水文研究》2006,20(18):3915-3938

The influence of emergent and submerged macrophytes on flow velocity and turbulence production is demonstrated in a 140 m reach of the River Blackwater in Farnborough, Hampshire, UK. Macrophyte growth occurs in patches and is dominated by Sparganium erectum and Sparganium emersum. In May 2001, patches of S. erectum were already established and occupied 18% of the channel area. The flow adjusted to these (predominantly lateral) patches by being channelled through a narrower cross‐section. The measured velocity profiles showed a logarithmic form, with deviations attributable to topographic control. The channel bed was the main source of turbulence. In September 2001, in‐stream macrophytes occupied 27% of the channel, and overhanging bank vegetation affected 32% of the area. Overall flow resistance, described by Manning's n, showed a threefold increase that could be attributed to the growth of S. emersum in the middle of the channel. Velocity profiles showed different characteristic forms depending on their position relative to plant stems and leaves. The overall velocity field had a three‐dimensional structure. Turbulence intensities were generally higher and turbulence profiles tended to mirror the velocity profiles. Evidence for the generation of coherent eddies was provided by ratios of the root mean square velocities. Spectral analysis identified deviations from the Kolmogorov ?5/3 power law and provided statistical evidence for a spectral short‐cut, indicative of additional turbulence production. This was most marked for the submerged vegetation and, in some instances, the overhanging bank vegetation. The long strap‐like leaves of S. emersum being aligned approximately parallel to the flow and the highly variable velocity field created by the patch arrangement of macrophytes suggest that the dominant mechanism for turbulence production is vortex shedding along shear zones. Wake production around individual stems of S. emersum close to the bed may also be important locally. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

大气垂直折射与时序垂直角值的谱分析     

王泽民  张学廉 《大地测量与地球动力学》1995,(2)

本文介绍了对时序垂直角观测值进行谱分析的方法和所得到的结论。使以往对于大气折射影响及其变化规律的定性认识得以定量化。  相似文献   

长江中下游金属矿找矿前景与找矿方法   总被引：14，自引：3，他引：11       下载免费PDF全文

赵文津 《中国地质》2008,35(5):771-802

本文论述了长江中下游地区金属矿床的地质、地球物理和地球化学特点,提出今后深部找矿的主要对象是：找隐伏含矿岩体及有关的各类矿体,找岩体中的大型斑岩型矿床,找受岩体和五通砂岩联合控制的层状矿;讨论了地球物理和地球化学方法应用中要注意解决的几个主要问题,强调应发挥包括重力、磁法、激发极化法、电磁法、岩性探测仪及多种天然地震法和化探方法等综合方法的作用,并与地质矿床成矿规律研究密切结合;讨论了方法应用试验中要注意的几个问题。文章最后一部分是从本区大地构造的演化探讨了区域构造岩浆活动与成矿前景,认为这一地区是扬子板块与华北板块陆-陆碰撞挤压造山带及其前陆区,在岩石圈强烈挤压下形成地壳增厚和深部物质的挤出折返,使深部的高压和超高压变质岩层推到地壳浅部;深部生成的柯石英等高压超高压矿物及地幔熔融岩浆同时上侵;生成大量钙碱性岩浆并存储在中地壳部位,通过长期与中下地壳金属物质进行交换,形成矿液的集中优势,通过后期出现的张性断裂构造而进入地壳表层,再经过与围岩发生物理化学成矿作用后沉淀成矿。归纳出扬子板块与华北板块陆-陆碰撞造山带一种新的构造模式。  相似文献   

Spectral Analysis of Nonlinear Drag Forces     

马汝建  李桂喜赵东 《中国海洋工程》2005,19(2):325-332

The spectral properties of nonlinear drag forces of random waves on vertical circular cylinders are analyzed in this paper by means of nonlinear spectral analysis. The analysis provides basic parameters for estimation of the characteristic drag forces. Numerical computation is also performed for the investigation of the effects of nonlinearity of the drag forces.The results indicate that the wave drag forces calculated by linear wave theory are larger than those calculated by the third order Stokes wave theory for given waves. The difference between them increases with wave height. The wave drag forces calculated by use of hnear approximation are about 5% smaller than their actual values when measured in the peak values of spectral densities. This will result in a safety problem for the design of offshore structures. Therefore, the nonlinear effect of wave drag forces should be taken into comidemtion in design and application of important offshore structures.  相似文献   

Cod migration patterns in relation to temperature: analysis of storage tag data   总被引：1，自引：0，他引：1  

Stensholt  Boonchai K. 《ICES Journal of Marine Science》2001,58(4):770-793

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海水分光反射率与叶绿素浓度的相关分析     

傅克忖  曾宪模 《海洋科学进展》1995,(1)

通过对东京湾两年度不同季节海水分光反射率与叶绿素浓度进行统计分析，结果表明，叶绿素浓度Ｃ与两谱段分光反射率之比Ｒｗ（λｊ）／Ｒｗ（λｊ）具有幂函关系Ｃ＝Ａ［Ｒｗ（λｊ）／Ｒｗ（λｊ）Ｂ。两者的对数显示出较好的线性关系，即ｌｏｇＣ＝ｌｏｇＡ＋Ｂｌｏｇ［Ｒｗ（λｊ）／Ｒｗ（λｊ）］。负相关系数达０．９９。相关方程之一为Ｃ＝３．３２９［Ｒｗ（５２０）／Ｒｗ（５５０）］－１．３８４（１９８７年６月初）．在梅雨季节之后，相关方程为Ｃ＝１２．６８［Ｒｗ（５２０）／Ｒｗ（５５０）］－２．０１０（１９８８年８月）。这表明了海湾或混浊的沿岸水质，在叶绿素浓度算法中，统计参数Ａ和Ｂ的确立，要基于不同季节不同水质的现场观测资料。  相似文献