有源电磁扩散场克希霍夫积分偏移

As active electromagnetic method, field data of CSAMT method follow the equation of diffusion. Propagting in solid earth media, diffusion EM signal has strong attenuation and dispersion, otherwise seismic wave shows weak attenuation and dispersion, therefore the resolution power of CSAMT method is not better than seismic reflection method. However, there is consistence and similarity between EM signal and seismic wave in wave equation, we can apply Kirchhoff integral migration technique, a proven one in seismic method in time domain, to carry out seduo-seismic processing for CSAMT signal in frequency domain so that the attenuation and dispersion could be made compensated in some extent, and the resolution power and interpretation precision of active EM wave could be improved. Satisfying passive homogeneous Helmholtz quation, we proceed with Green theorem and combine the active inhomogenous Helmholtz quation, the Kirchhoff integral formula could be derived. Given practical problems, if we only consider the surface integral value, and assume that the intergral value in other interface is zero, combined with Green theorem in uniform half space, the expression could be simplified, and we can obtain frequency-domain Kirchhoff integral formula in surface, which is also called downward continuation of EM field in frequency domain. With image conditions and energy compensation considered, in order to get image conditions in time domain Fourier inverse transformation in frequency domain can be performed, so we can formulate the active Kirchhoff integral migration expression. At first, we construct relative stratified model, with different frequency series taken into account, then we change the distances between transmitter and reciever, the EM response can be obtained. Analyzing the EM properties, we can clarify near and far zone that can instruct us to carry out transmitter layout in practical application. Combined with field data surveyed in far zone, We perform Kirchhoff integral migration and compare the results with model to interpret. Secondly, with far field EM data, we apply TM mode to get EM response of given 2D model, then apply Kirchhoff integral migration on modelling data and interpret the results.

边坡工程的极限分析上限法

Theory of limit analysis include upper bound theorem and lower bound theorem. To deal with slope stability analysis by limit analysis is to approximate the real solution from upper limit and lower limit. The most used method of limit analysis is upper bound theorem, therefore it is often applied to slope engineering in many cases. Although upper bound approach of limit analysis can keep away from vague constitutive relation and complex stress analyses, it also can obtain rigorous result. Assuming the critical surface is circular slip surface, two kinematically admissible velocity fields for perpendicular slice method and radial slice method can be established according to the limit analysis of upper bound theorem. By means of virtual work rate equation and strength reduction method, the upper-bound solution of limit analysis for homogeneous soil slope can be obtained. A log-spiral rotational failure mechanism for homogeneous slope is discussed from two different conditions which represent the position of shear crack passing the toe and below the toe. In the dissertition, the author also establishes a rotational failure mechanics with combination of different logarithmic spiral arcs. Furthermore, the calculation formula of upper bound solution for inhomogeneous soil slope stability problem can be deduced based on the upper bound approach of rigid elements. Through calculating the external work rate caused by soil nail, anti-slide pile, geotechnological grid and retaining wall, the upper bound solution of safety factor of soil nail structure slope, slip resistance of anti-slide pile, critical height of reinforced soil slope and active earth pressure of retaining wall can be obtained by upper bound limit analysis method. Taking accumulated body slope as subject investigated, with study on the limit analysis method to calculate slope safety factor, the kinematically admissible velocity fields of perpendicular slice method for slope with broken slip surface is proposed. Through calculating not only the energy dissipation rate produced in the broken slip surfaces and the vertical velocity discontinuity, but also the work rate produced by self-weight and external load, the upper bound solution of slope with broken slip surface is deduced. As a case study, the slope stability of the Sanmashan landslide in the area of the Three Gorges reservoir is analyzed. Based on the theory of limit analysis, the upper bound solution for rock slope with planar failure surface is obtained. By means of virtual work-rate equation, energy dissipation caused by dislocation of thin-layer and terrane can be calculated; furthermore, the formulas of safety factor for upper bound approach of limit analysis can be deduced. In the end, a new computational model of stability analysis for anchored rock slope is presented after taking into consideration the supporting effect of rock-bolts, the action of seismic force and fissure water pressure. By using the model, not only the external woke-rate done by self-weight, seismic force, fissure water pressure and anchorage force but also the internal energy dissipation produced in the slip surface and structural planes can be totally calculated. According to the condition of virtual work rate equation in limit state, the formula of safety factor for upper bound limit analysis can be deduced.

基于信息重建技术的地震信号处理方法研究

The dissertation addressed the problems of signals reconstruction and data restoration in seismic data processing, which takes the representation methods of signal as the main clue, and take the seismic information reconstruction (signals separation and trace interpolation) as the core. On the natural bases signal representation, I present the ICA fundamentals, algorithms and its original applications to nature earth quake signals separation and survey seismic signals separation. On determinative bases signal representation, the paper proposed seismic dada reconstruction least square inversion regularization methods, sparseness constraints, pre-conditioned conjugate gradient methods, and their applications to seismic de-convolution, Radon transformation, et. al. The core contents are about de-alias uneven seismic data reconstruction algorithm and its application to seismic interpolation. Although the dissertation discussed two cases of signal representation, they can be integrated into one frame, because they both deal with the signals or information restoration, the former reconstructing original signals from mixed signals, the later reconstructing whole data from sparse or irregular data. The goal of them is same to provide pre-processing methods and post-processing method for seismic pre-stack depth migration. ICA can separate the original signals from mixed signals by them, or abstract the basic structure from analyzed data. I surveyed the fundamental, algorithms and applications of ICA. Compared with KL transformation, I proposed the independent components transformation concept (ICT). On basis of the ne-entropy measurement of independence, I implemented the FastICA and improved it by covariance matrix. By analyzing the characteristics of the seismic signals, I introduced ICA into seismic signal processing firstly in Geophysical community, and implemented the noise separation from seismic signal. Synthetic and real data examples show the usability of ICA to seismic signal processing and initial effects are achieved. The application of ICA to separation quake conversion wave from multiple in sedimentary area is made, which demonstrates good effects, so more reasonable interpretation of underground un-continuity is got. The results show the perspective of application of ICA to Geophysical signal processing. By virtue of the relationship between ICA and Blind Deconvolution , I surveyed the seismic blind deconvolution, and discussed the perspective of applying ICA to seismic blind deconvolution with two possible solutions. The relationship of PC A, ICA and wavelet transform is claimed. It is proved that reconstruction of wavelet prototype functions is Lie group representation. By the way, over-sampled wavelet transform is proposed to enhance the seismic data resolution, which is validated by numerical examples. The key of pre-stack depth migration is the regularization of pre-stack seismic data. As a main procedure, seismic interpolation and missing data reconstruction are necessary. Firstly, I review the seismic imaging methods in order to argue the critical effect of regularization. By review of the seismic interpolation algorithms, I acclaim that de-alias uneven data reconstruction is still a challenge. The fundamental of seismic reconstruction is discussed firstly. Then sparseness constraint on least square inversion and preconditioned conjugate gradient solver are studied and implemented. Choosing constraint item with Cauchy distribution, I programmed PCG algorithm and implement sparse seismic deconvolution, high resolution Radon Transformation by PCG, which is prepared for seismic data reconstruction. About seismic interpolation, dealias even data interpolation and uneven data reconstruction are very good respectively, however they can not be combined each other. In this paper, a novel Fourier transform based method and a algorithm have been proposed, which could reconstruct both uneven and alias seismic data. I formulated band-limited data reconstruction as minimum norm least squares inversion problem where an adaptive DFT-weighted norm regularization term is used. The inverse problem is solved by pre-conditional conjugate gradient method, which makes the solutions stable and convergent quickly. Based on the assumption that seismic data are consisted of finite linear events, from sampling theorem, alias events can be attenuated via LS weight predicted linearly from low frequency. Three application issues are discussed on even gap trace interpolation, uneven gap filling, high frequency trace reconstruction from low frequency data trace constrained by few high frequency traces. Both synthetic and real data numerical examples show the proposed method is valid, efficient and applicable. The research is valuable to seismic data regularization and cross well seismic. To meet 3D shot profile depth migration request for data, schemes must be taken to make the data even and fitting the velocity dataset. The methods of this paper are used to interpolate and extrapolate the shot gathers instead of simply embedding zero traces. So, the aperture of migration is enlarged and the migration effect is improved. The results show the effectiveness and the practicability.

电阻率测井反演方法应用研究

Formation resistivity is one of the most important parameters to be evaluated in the evaluation of reservoir. In order to acquire the true value of virginal formation, various types of resistivity logging tools have been developed. However, with the increment of the proved reserves, the thickness of interest pay zone is becoming thinner and thinner, especially in the terrestrial deposit oilfield, so that electrical logging tools, limited by the contradictory requirements of resolution and investigation depth of this kinds of tools, can not provide the true value of the formation resistivity. Therefore, resitivity inversion techniques have been popular in the determination of true formation resistivity based on the improving logging data from new tools. In geophysical inverse problems, non-unique solution is inevitable due to the noisy data and deficient measurement information. I address this problem in my dissertation from three aspects, data acquisition, data processing/inversion and applications of the results/ uncertainty evaluation of the non-unique solution. Some other problems in the traditional inversion methods such as slowness speed of the convergence and the initial-correlation results. Firstly, I deal with the uncertainties in the data to be processed. The combination of micro-spherically focused log (MSFL) and dual laterolog(DLL) is the standard program to determine formation resistivity. During the inversion, the readings of MSFL are regarded as the resistivity of invasion zone of the formation after being corrected. However, the errors can be as large as 30 percent due to mud cake influence even if the rugose borehole effects on the readings of MSFL can be ignored. Furthermore, there still are argues about whether the two logs can be quantitatively used to determine formation resisitivities due to the different measurement principles. Thus, anew type of laterolog tool is designed theoretically. The new tool can provide three curves with different investigation depths and the nearly same resolution. The resolution is about 0.4meter. Secondly, because the popular iterative inversion method based on the least-square estimation can not solve problems more than two parameters simultaneously and the new laterolog logging tool is not applied to practice, my work is focused on two parameters inversion (radius of the invasion and the resistivty of virgin information ) of traditional dual laterolog logging data. An unequal weighted damp factors- revised method is developed to instead of the parameter-revised techniques used in the traditional inversion method. In this new method, the parameter is revised not only dependency on the damp its self but also dependency on the difference between the measurement data and the fitting data in different layers. At least 2 iterative numbers are reduced than the older method, the computation cost of inversion is reduced. The damp least-squares inversion method is the realization of Tikhonov's tradeoff theory on the smooth solution and stability of inversion process. This method is realized through linearity of non-linear inversion problem which must lead to the dependency of solution on the initial value of parameters. Thus, severe debates on efficiency of this kinds of methods are getting popular with the developments of non-linear processing methods. The artificial neural net method is proposed in this dissertation. The database of tool's response to formation parameters is built through the modeling of the laterolog tool and then is used to training the neural nets. A unit model is put forward to simplify the dada space and an additional physical limitation is applied to optimize the net after the cross-validation method is done. Results show that the neural net inversion method could replace the traditional inversion method in a single formation and can be used a method to determine the initial value of the traditional method. No matter what method is developed, the non-uniqueness and uncertainties of the solution could be inevitable. Thus, it is wise to evaluate the non-uniqueness and uncertainties of the solution in the application of inversion results. Bayes theorem provides a way to solve such problems. This method is illustrately discussed in a single formation and achieve plausible results. In the end, the traditional least squares inversion method is used to process raw logging data, the calculated oil saturation increased 20 percent than that not be proceed compared to core analysis.

月表热参数模型与月壤厚度的被动微波遥感理论分析

利用被动微波遥感亮度温度数据反演月壤厚度是“嫦娥”探月工程的科学目标之一，也是人类探测月壤厚度的一种新的尝试。深入研究月表太阳辐射、月球内部热流以及月表温度的分布和变化规律，是解译遥感数据，反演月壤厚度的前提条件，也为进一步开展月球探测、开发利用月球资源乃至建立月球基地相关研究工作提供必要的参考。 本文根据月表有效太阳辐照度与太阳常数、日月距离和太阳辐射入射角的关系，建立了月表有效太阳辐照度的实时模型如下： (1) 其中， (2) (3) 通过对月表有效太阳辐照度实时模型的各个参数分析发现，影响月表有效太阳辐照度变化的主要因素是日地距离和太阳辐射入射角的变化。对模型的误差分析表明，从1950年到2050年的100年内，月表有效太阳辐照度计算结果的误差百分比小于0.28％，能更准确地反映月表有效太阳辐照度的变化情况。从2007年月表有效太阳辐照度的计算结果发现，该年内的月表有效太阳辐照度变化在1321.5～1416.6 W•m-2之间，平均为1368.0 W•m-2，一个月内的变化最小幅度为6.0 W•m-2，最大幅度为23.6 W•m-2。 在月表有效太阳辐照度的实时模型基础上，根据能量守恒和Stefan-Boltzmann定律，本文还得出了月表温度分布模型如下： (4) 其中，初始条件由下式决定， (5) 通过与月表温度实际观测结果的比较发现，当月表反射率、热发射率和热惯量分别取0.127、0.94和125 J•m-2•s-1/2•K-1时，模型的计算结果与实际观测值比较符合，能较好地预测理想条件下的月表温度。 月表热参数研究的一个重要应用就是解译对月被动微波遥感的亮度温度数据。在对月被动微波遥感探测中，辐射计获得的亮度温度反映了月球表层的热辐射特性。月球表层的热辐射与其自身的热状况紧密相关，结合文中建立的月表热参数模型，根据辐射传播理论进一步分析了对月微波遥感探测中，月球表层在不同情况下对亮度温度的贡献，确定了亮度温度随月表温度和月壤厚度的变化关系，对被动微波遥感探测月壤厚度的可能性和可能达到的精度进行了估算。 对月球表层的热辐射传播的分析发现，对月被动微波遥感探测获得的亮度温度受月球表层热辐射的控制，与月壤厚度具有指数相关性，并受到月表温度的影响。当月壤和月岩的复介电常数分别为2 + 0.005 j和9 + 1 j、相对磁导率均为1时，对应3.0GHz、7.8GHz、19.35GHz和37.0GHz四个频率的亮度温度与月壤厚度及月表温度的关系可分别近似表示为， 3.0GHz亮度温度： (6) 7.8GHz亮度温度： (7) 19.35GHz亮度温度： (8) 37.0GHz亮度温度： (9) 当月壤厚度和月表温度分别在0.5m~30m和100K~400K之间变化时，上述四个频率的亮度温度变化范围分别在212.5K～252.8K、207.4 K～266.7K、193.8 K～288.6K和174.0 K～310.9K之间。对于较低频率的被动微波遥感，亮度温度随月壤厚度的增大逐渐增大并趋于稳定；对较高频率的被动微波遥感，亮度温度随月壤厚度的增大会产生起伏波动，不利于用单波段反演月壤厚度。亮度温度梯度在频率较高时梯度较大，在很小的月壤厚度范围内很快就趋于0，不利于厚度较大时的月壤厚度反演，但对于厚度较小时的月壤厚度反演精度较高；同时，除3.0GHz外，7.8GHz、19.35GHz和37.0GHz三个频率的亮度温度梯度随月表温度的升高降幅较大，尤其是19.35GHz，适合在夜间对月壤厚度较小的地区进行更精确的探测。对于3.0GHz，其亮度温度梯度受月表温度变化的影响很小，能反映出较深层月壤厚度的信息，可以对月球进行全球全天时探测。若辐射计的分辨率为0.02K，3.0GHz频率对10m厚月壤的判别精度达到0.07m；对于20m厚月壤的精度为1.4m。当月壤厚度小于0.5m时，随着月壤厚度从0到0.5m增加，月球表层的亮度温度贡献呈先减小后增大的趋势，从而使某一亮度温度值可能对应存在两种不同的月壤厚度。因此，对于月壤厚度小于0.5m的区域，利用单波段被动微波遥感亮度温度反演月壤厚度是比较困难的。 在对月被动微波遥感探测中，可以利用月球夜晚时段的亮度温度数据判别月壤厚度是否小于0.5m。当月表温度为100K时，3.0GHz、7.8GHz、19.35GHz和37.0GHz四个频率的亮度温度判别参考值分别为212.9K、207.4K、193.5K和174.1K；月表温度为240K时，上述四个频率的亮度温度判别参考值分别为220.8K、226.8K、234.1K和237.2K。当亮度温度小于参考值时表示月壤厚度小于0.5m，反之，表示月壤厚度大于0.5m。更进一步地，可以根据月表温度的影响系数对月岩是否裸露于月表进行判断。当3.0GHz、7.8GHz、19.35GHz和37.0GHz四个频率的月表温度影响系数接近0.77、0.82、0.84和0.85时，可以认为月岩直接暴露于月表。

Time-dependent wavepacket approach to the influence of intense fields on the population of molecular excited states

The influence of laser-field parameters, such as intensity and pulse width, on the population of molecular excited state is investigated by using the time-dependent wavepacket method. For a two-state system in intense laser fields, the populations in the upper and lower states are given by the wavefunctions obtained by solving the Schrodinger equation through split-operator scheme. The calculation shows that both the laser intensity and the pulse width have a strong effect on the population in molecular excited state, and that as the common feature of light-matter interaction (LMI), the periodic changing of the population with the evolution time in each state can be interpreted by Rabi oscillation and area-theorem. The results illustrate that by controlling these two parameters, the needed population in excited state of interest can be obtained, which provides the foundation of light manipulation of molecular processes. (C) 2005 Elsevier B.V. All rights reserved.