一类R~n空间上旋转椭球面簇的广义Radon变换     

吴一刚  邱佩璋 《CT理论与应用研究》1993,(1)

本文基于二维雷达成像的原理研究了其数学问题,对R~n 空间中的图像函数f(x),已知其旋转椭球面簇上的积分值,应用广义Radon 变换来重建图像函数f(x)。利用球谐函数展开和Funk-Heck 定理证明了这种重建图像问题的存在、唯一性,并在一定的函数类中给出了它的反演解的数学表达式和推广了V.G.Romanov的工作。  相似文献   

甘06井水位潮汐参数的震前中期异常     

唐九安  白亚平 《地震》1993,(6):21-28

本文介绍了甘０６井１９８６－１９９１年期间潮汐参数的计算结果，分析了该井水位和潮汐参数在共和、景泰地震前的中期异常显示。结果表明，该井下水位月均值及其差分值于１９８９年２月至１９９０年２月期间明显异常，自１９８９年起，该井的潮汐因子有明显增大趋势，测井所在区域的构造应力场也明显增强。  相似文献   

Secular variation in the geographic location of the dip equator     

G. K. Rangarajan 《Pure and Applied Geophysics》1994,143(4):697-711

The geographic location of the dip equator on the globe has been determined for several epochs between 1550 and 1990 A.D. It is shown that two regions near 165°E and 285°E are devoid of migratory changes whereas between 300 and 0°E there is a large northward movement. The period between 1945 and 1990 is marked by a nearly linear change in the latitude of the dip equator while earlier epochs show more complex trends. Consistent with the earlier observations of the movement of the magnetic center towards or away from the centre of the earth, before and after 1800 A.D., the secular curves in certain longitude zones indicate a clear change in pattern. The observed secular variations in the vertical cornponent at several low latitude stations are generally in agreement with the direction of the movement of the dip equator. Examples of unexpected behaviour are highlighted. The eccentric dipole model appears to be adequate to delineate the dip equator for any epoch.  相似文献   

Decline curve analyses revisited     

Walter Rose 《Mathematical Geology》1990,22(8):1051-1061

Empiricaldecline curve forecasts of future production rates and cumulative production to be expected from certain classes of petroleum reservoirs has been a methodology practiced and relied on by petroleum geologists for many years. New ways to consider the subject are described in this paper. Thereby it is seen that these forecasts sometimes can be made even when some of the record of the past performance history is sparse (say, because it has been lost, or never recorded).SI Units D, D _i initial reference production rate,s ^–1 - n dimensionless constant [cf. Eq. (1)] - N cumulative production, m³ - Q, Q _i production rate att and initially, m³/s - R dimensionless time variable [cf. Eq. (9)] - t time, s  相似文献   

Localized spectral analysis of global satellite gravity fields for recovering time-variable mass redistributions     

Shin-Chan Han  Pavel Ditmar 《Journal of Geodesy》2008,82(7):423-430

A spatiospectral localization method is discussed for processing the global geopotential coefficients from satellite mission data to investigate time-variable gravity. The time-variable mass variation signal usually appears associated with a particular geographical area yielding inherently regional structure, while the dependence of the satellite gravity errors on a geographical region is not so evident. The proposed localization amplifies the signal-to-noise ratio of the (non-stationary) time-variable signals in the geopotential coefficient estimates by localizing the global coefficients to the area where the signal is expected to be largest. The results based on localization of the global satellite gravity coefficients such as Gravity Recovery And Climate Experiment (GRACE) and Gravity and Ocean Circulation Explorer (GOCE) indicate that the coseismic deformation caused by great earthquakes such as the 2004 Sumatra–Andaman earthquake can be detected by the low-low tracking and the gradiometer data within the bandwidths of spherical degrees 15–30 and 25–100, respectively. However, the detection of terrestrial water storage variation by GOCE gradiometer is equivocal even after localization.  相似文献   

基于不同潮汐类型的不同时间尺度分潮结果精度分析     

宋艳朋  付延光  周兴华  杨磊 《测绘与空间地理信息》2017,(1)

选取4种不同潮汐类型的验潮站实测潮位资料,对验潮零点在一定范围内变动对调和分析结果的影响进行分析,结果表明,一年的潮位数据中若后续6个月的数据发生10 cm、20 cm、30 cm零点漂移,各分潮振幅最大变化量为0.47 cm,迟角为0.16°。采用1~12个月不同中期尺度的实测数据,对调和结果的精度进行分析,结果表明,当潮位观测数据时间尺度小于6个月时,其4个主要分潮O_1、K_1、M_2、S_2振幅综合中误差在2 cm以上,迟角中误差在2°以上,具有显著的不稳定性;相同时间尺度的不同潮汐类型的潮位站潮位资料调和分析得到的主要分潮的振幅精度差异较大,迟角分布相似。当潮位观测数据时间尺度达到或多于6个月时,澳门站、汕尾站的分潮综合中误差分别为1.16 cm、0.61 cm,厦门站、北海站分别为2.90 cm和2.51 cm;各分潮迟角中误差均在2°内。当时间尺度超过9个月后,4个验潮站分潮振幅综合中误差均在2 cm以内,各分潮迟角中误差均在1°左右。  相似文献   

Matlab.NET混合编程在潮汐调和分析与预报中的应用     

宋艳朋  周兴华  付延光  杨磊  孙维康 《测绘与空间地理信息》2017,40(5)

利用.NET中C#强大的界面开发能力和经典的Matlab潮汐调和分析程序包T_TIDE,采用Matlab.NET混合编程技术,创建潮汐调和常数计算THCCalculate.dll和潮汐预报Tide Forecast.dll,在主程序中调用对应的函数,实现了操作简单且具有良好用户界面的潮汐调和分析与潮位预报系统,具有潮位数据读取、调和分析和预报、数据绘制等功能。结果表明:使用混合编程技术能充分发挥C#与Matlab各自的特点,较好地提高程序开发和运行效率,具有较广泛的应用范围。  相似文献   

GGOS对流层延迟产品精度分析及在PPP中的应用     

姚宜斌  徐星宇  胡羽丰 《测绘学报》2017,46(3):278-287

对流层延迟是卫星导航定位的主要误差源,GNSS广域增强需要高精度的对流层延迟产品进行误差修正。对流层延迟可通过GNSS进行实时估计,也可通过融合多源数据的数值气象预报模型获取。IGS发布的全球对流层天顶延迟产品由GNSS解算,其精度可达4mm,时间分辨率为5min,但其分布不均匀,在广袤的海洋区域无数据覆盖。GGOS Atmosphere基于ECMWF 40年再分析资料,可提供1979年以来时间分辨率为6h、空间分辨率为2.5°×2°的全球天顶对流层总延迟格网数据。本文通过2015年全球IGS测站的ZTD资料对GGOS的ZTD产品进行了评估,研究了GGOS Atmosphere对流层延迟产品与IGS发布ZTD资料之间的系统差,通过线性拟合估计出每个测站GGOS-ZTD与IGSZTD系统差系数(包括比例误差a和固定误差b),然后对比例误差a、固定误差b进行球谐展开,建立了两种ZTD数据源之间的系统差模型。选取IGS测站和陆态网测站,对附加系统偏差改正后的GGOSZTD产品对PPP的收敛速度的影响进行研究。本文研究结果表明:GGOS-ZTD与IGS-ZTD间存在系统偏差,其bias平均为-0.54cm;两者之间较差的RMS平均为1.31cm,说明GGOS-ZTD产品足以满足广大GNSS导航定位用户对对流层延迟改正的需要。将改正了系统差后的GGOS-ZTD产品用于ALBH、DEAR、ISPA测站、PALM测站、ADIS测站、YNMH测站、WUHN测站进行PPP试验,发现可明显提高定位收敛速度,尤其是在U方向上,收敛速度分别提高10.58%、31.68%、15.96%、43.89%、51.46%、14.69%、18.40%。  相似文献   

庐江台自流井流量固体潮观测资料调和分析的初步结果     

刘长海  张朝明  梁久亮 《大地测量与地球动力学》1993,(2)

本文给出了积分采样数据的维尼迪柯夫调和分析方法。使用该方法,以相应的固体潮体应变为理论值,对庐江台自流井流量1987年7月～1988年1月的观测数据(脉冲数)进行了调和分析计算,主要潮波结果为:振幅因子(脉冲数/10~(-9))O_1波:49.6±0.6;M_2波:50.8±0.3;其相位滞后分别为-4°.6±0°.7、6°.9±0°.3。说明以该井流量做为体应变仪具有很高的灵敏度。  相似文献   

Lateral stress caused by horizontal and vertical surcharge strip loads on a cross‐anisotropic backfill     

Cheng‐Der Wang 《国际地质力学数值与分析法杂志》2005,29(14):1341-1361

This study derives analytical solutions for estimating the lateral stress caused by horizontal and vertical surcharge strip loads resting on a cross‐anisotropic backfill. The following loading types are employed in this work: point load, line load, uniform strip load, upward linear‐varying strip load, upward nonlinear‐varying strip load, downward linear‐varying strip load and downward nonlinear‐varying strip load. The cross‐anisotropic planes are assumed to be parallel to the horizontal surface of the backfill. The solutions proposed herein have never been mentioned in previous literature, but can be derived by integrating the point load solution in a Cartesian co‐ordinate system for a cross‐anisotropic medium. The calculations by the presented solutions are quick and accurate since they are concise and systematized. Additionally, the proposed calculations demonstrate that the type and degree of material anisotropy and the horizontal/vertical loading types decisively influence the lateral stress. This investigation presents examples of the proposed horizontal and vertical strip loads acting on the surface of the isotropic and cross‐anisotropic backfills to elucidate their effects on the stress. The analytical results reveal that the stress distributions accounting for soil anisotropy and loading types are quite different from those computed from the available isotropic solutions. Restated, the derived solutions, as well as realistically simulating the actual surcharge loading circumstances, provide a good reference for the design of retaining structures for the backfill materials are cross‐anisotropic. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献