n—D Radon变换与波动方程偏移

本文把Ｒａｄｏｎ变换公式推广到任意ｎ维的情况。同时结合ｎ维Ｒａｄｏｎ变换和摄动理论提出了一种既能用于地面资料又能用于ＶＳＰ资料的偏移方法。     

一类广义Radon变换及反投影

本文提出了一类广义Ｒａｄｏｎ变换及反投影公式。这种变换形式比常规Ｒａｄｏｎ变换形式具有更广泛的意义及应用。数值计算结果表明，反投影恢复性较好。     

广义Radon变换的正交展开和反演

本文具体给出了广义Ｒａｄｏｎ变换在函数空间Ｌ＾２（Ｒ＾ｎ,Ｗｎ）上的正交函数展开形式,由此得到了广义Ｒａｄｏｎ变换的反演公式,从而推广了Ｌｏｕｉｓ和Ｄａｖｉｓｏｎ的工作。     

平面Radon变换的反演公式

本文借助球面平均法和Ｈｉｌｂｅｒｔ空间算子理论,给出了平面上Ｒａｄｏｎ变换的反演公式,此公式是具体的、构造性的,便于数值计算,或者进一步探讨重建图象的性质。     

Influence of Atmospheric Radon Transport on a Radon Flux from the Surface

Radon-222 is inert radioactive gas with a half-life period of 3.8 days, it is a decay product of radium-226. Being escaped from minerals and underground waters into pore space of rocks and soil, it is transported to the surface by diffusion and advection and gone to the atmosphere. When modeling processes of atmosphere radon transport one sets value of radon flux from the surface, depending on contents of radium-226 in rocks and conditions of radon transport in soil, especially on soil porosity and humidity. The impact of radon turbulent transport in the atmospheric boundary layer (ABL) on radon flux density from the surface is estimated in this paper. It is shown that both for stationary state and for typical diurnal variations of the radon volumetric activity (VA) in the ABL, the correction to the radon flux density caused by its turbulent transport in the ABL is negligible (less than 1%) and doesn’t exceed measurement errors. Thus, when calculating radon VA in the ABL it is really possible to set an average value of the radon flux density on the surface as a boundary condition.     

Vibration Effect of Near Earthquakes at Different Depths in a Shallow Medieval Mine

The shallow medieval Jeroným Mine is located at a distance of about 25 km southeast of the Nový Kostel focal zone where the most intensive seismic activity in West Bohemia (Czech Republic) has been documented. Permanent seismological monitoring has been carried out since 2004 in this mine. During the 2011 and 2014 seismic swarms, more than 1000 triggered records comprising almost 1500 earthquakes were recorded at the permanent station in the mine. Three short-term seismological experiments were accomplished during these swarms. Several temporary seismic stations were simultaneously placed in different parts of underground spaces which enabled comparison of vibration effect caused by near earthquakes in different parts of the mine. Although the depth of the lowest parts of mine is only about 60 m, a vibration effect generated by earthquakes from the Nový Kostel focal zone is not the same for the whole underground complex.     

Radon Transform Methods and Their Applications in Mapping Mantle Reflectivity Structure

This paper reviews the fundamentals of Radon-based methods using examples from global seismic applications. By exploiting the move-out or curvature of signal of interest, Least-squares and High-resolution Radon transform methods can effectively eliminate random or correlated noise, enhance signal clarity, and simultaneously constrain travel time and ray angles. The inverse formulation of the Radon transform has the added benefits of phase isolation and spatial interpolation during data reconstruction. This study presents a ‘cookbook’ for Radon-based methods in analyzing shear wave bottom-side reflections from mantle interfaces, also know as SS precursors. We demonstrate that accurate and flexible joint Radon- and frequency-domain approaches are particularly effective in resolving the presence and depth of known and postulated mantle reflectors.     

三维Radon变换的一种快速解析方法

3D Radon变换及其反变换是X-CT三维图像重建理论的核心,它在其他许多学科领域也有广泛应用。3D Radon变换的表达式是一个三重积分,按照定义直接计算相当费时。为此,研究一种新的快速的方法实现3D Radon变换,对X-CT图像重建理论及相关领域的发展有重要意义。本文以算法仿真常用椭球模型为基础,通过求解椭球模型与空间任意平面的面积,实现了用解析的方法快速得到模型的Radon变换,进一步比较了它与传统方法的优缺点,最后根据Radon反变换重建出原物体模型;计算机仿真结果验证了这种方法的正确。     

求解Radon变换改进Fourer算法的误差分析

本文将对求解Ｒａｄｏｎ变换的改进Ｆｏｕｒｉｅｒ算法进行误差分析,证明了在Ｌ２范数下改进Ｆｏｕｒｉｅｒ算法是收敛的且具有Ｏ（１／ｑ）敛阶,其中２ｑ为像素点矩陈阶数。     

沿圆曲线的Radon变换数值解

研究具有紧支集且在支集内连续的二元函数沿上半圆曲线的Radon变换反演问题。基于对投影函数的Fourier变换,反演问题可以归结为具有弱奇性及震荡核的Abel积分方程的求解。我们证明了当圆曲线中心及半径在一定范围内变化时,在已知沿上半圆曲线的Radon变换情况下,这个积分方程的解具有唯一性,并给出了消除Abel积分方程弱奇性的数值方法。在考虑投影数据噪声的情况下,给出了多次加权改善系数矩阵条件数稳定的数值方法,并通过数值模拟验证所提出方法的有效性。     

一类曲线图象重建卷积反投影算法

本文给出了一类平面曲线 s=4(x,y)·coxθ+B(x,y)·sinθ上的 Radon 变换卷积反投影算法,并进行了数值模拟,其重建结果与真实数据相吻合,其中 A(x,y)和 B(x,y)满足一定条件.     

波动方程反问题与广义RADON变换反演的一种关系

本文把波动方程反问题与广义Radon 变换的反演相联系。在假定弱散射条件下,把波动方程反问题转化成广义Radon 变换的反演问题,即如何从一系列关于目标函数在某类子流形上的积分值,去求出目标函数.这种转化提供了一种研究波动方程反问题的途径。     

局域双曲线Radon变换压制散射波研究与应用

一般而言,由于地下非均质体的存在所产生的二次波源,由它再生成新的波场,叫散射波场。目前,将散射波作为有效波来成像,已开始在溶洞和裂缝等特殊地质体的识别中得到应用。但对于野外资料采集来说,地表复杂地区,如戈壁、砾石区和山前带,大量存在的散射波却是干扰波,它们的存在会严重影响资料的品质,而其研究与实际应用国内外还很少。因此,通过正演模拟,分析散射波的基本特征,在此基础上研究散射波的去噪方法显得十分必要。本文从地震波运动学时距关系出发,研究了反射波和散射波的几何特征;然后用有限差分正演,模拟了散射波场,用理论模型研究并测试了局域双曲线Radon变换散射波去噪新方法。对于实际炮集资料,分析了F-K滤波方法压制散射噪声的局限,采用局域双曲Radon变换有效地去除了炮集中存在的散射噪声,取得了较好的应用效果。     

Response of Surface Soft Soil and Fine-Grained Sand Layers to Seismic Waves

INTRODUCTIONManyChineseandforeignseismologistsandengineeringseismologistshavestudiedthelargecasualtiesandpropertydamagescausedbytheMexicanMS8 1earthquakeonSeptember1 9,1 985andtheHanshinMS7 4earthquakeinJapan ,onJanuary 1 7,1 995andfoundthatsurfacesoftsoilcovercansignificantlyamplifyseismicgroundmotion .Thisphenomenoncanresultinlargerfailureofbuildingswithvibrationfrequencysimilartotheamplifiedgroundmotionfrequencythanthatcausedbyearthquakesthatoccuratbedrocksiteswheretherearenoamplifi…     

一类广义Radon变换的反演:迭代重建再投影的外插算法

本文对不完全数据下的一类广义Radon变换的反演问题,建议用迭代重建再投影的外插算法重建图像。数值模拟结果表明,迭代重建再投影的外插算法对重建图像是有效的。     

利用sPL震相测定福建顺昌地区地震震源深度

选用福建数字地震台网宽频带记录,利用sPL震相测定顺昌地区2007年至2017年间ML≥3.5地震的震源深度。基于地震的震源机制解,结合本地区的速度模型,利用频率-波数法(F-K方法),先计算出相应震中距上不同深度的格林函数,再进一步得到sPL震相在不同深度上的理论波形;根据sPL震相的特点,选用震中距30~50km范围的宽频带台站记录,经过去仪器响应、滤波、旋转至传播路径后,将其和理论波形进行比对,找出波形最为相似的对应深度。结果显示顺昌地区地震深度为7km左右。     

利用成都台网速度量记录测定尾波震级的初步研究

利用成都遥测地震台记录和实量处理系统记录，初步建立了１４个子台速度量记录持续时间测定近层波震级的经验公式ＭＤ＋Ｄ０＋Ｃ１ｌｏｇτ＋Ｃ２ｌｏｇ＾２τ并求得其中的系数Ｃ０，Ｃ１和Ｃ２，使得ＭＤ与全川分析目录结果的地震震级ＭＬ相一致，由于持续时间测定的震级的大小与信号持续时间直接相关，并反映台站附近价质性质，与路径基本无关，不受记录限幅与否的影响，可提高震级测定精度。     

Assimilation and High Resolution Forecasts of Surface and Near Surface Conditions for the 2010 Vancouver Winter Olympic and Paralympic Games

A dynamical model was experimentally implemented to provide high resolution forecasts at points of interests in the 2010 Vancouver Olympics and Paralympics Region. In a first experiment, GEM-Surf, the near surface and land surface modeling system, is driven by operational atmospheric forecasts and used to refine the surface forecasts according to local surface conditions such as elevation and vegetation type. In this simple form, temperature and snow depth forecasts are improved mainly as a result of the better representation of real elevation. In a second experiment, screen level observations and operational atmospheric forecasts are blended to drive a continuous cycle of near surface and land surface hindcasts. Hindcasts of the previous day conditions are then regarded as today’s optimized initial conditions. Hence, in this experiment, given observations are available, observation driven hindcasts continuously ensure that daily forecasts are issued from improved initial conditions. GEM-Surf forecasts obtained from improved short-range hindcasts produced using these better conditions result in improved snow depth forecasts. In a third experiment, assimilation of snow depth data is applied to further optimize GEM-Surf’s initial conditions, in addition to the use of blended observations and forecasts for forcing. Results show that snow depth and summer temperature forecasts are further improved by the addition of snow depth data assimilation.