基于DSP旋翼飞行机器人增稳操纵杆设计

本文首先介绍了旋翼飞行机器人控制系统的功能与应用,着重介绍了其中基于tmx320f28335数字信号处理器的无线增稳操控系统工作原理、硬件构架以及软件流程,并对AD转换过程中的关键FIR滤波算法进行说明,详尽比较了不同滤波参数对滤波效果的影响,最后得到该方法可以应用于旋翼飞行机器人增稳控制系统的结论,并将应用该方法滤波后的控制信号应用于实际增稳飞行,以实际数飞行据验证上述结论。

基于多种群遗传算法的波能装置的优化设计及分析

作为可再生能源,波浪能的吸收和利用一直是国内外热点研究内容之一。本文提出一种新的基于惯性摆结构的波浪能吸收转换方法,对这种结构在波浪力作用下的频域响应进行了分析,建立了其最优化能量获取模型,提出采用多种群遗传算法对其结构进行优化设计,并针对系统所受波浪力(矩)随载体半径改变而改变,且求取困难的问题,采用最小二乘法对波浪力(矩)与载体半径变化的关系进行了拟和。通过优化结果找出影响结构获取波浪能量的因素,仿真结果表明了方法的先进性,为进一步的应用研究和频域波能获取研究奠定了基础。

基于惯性摆的波能系统研究

提出了一种基于惯性摆结构的波浪能吸收转换方法,并对采用此结构构成的水中载体所受到的波浪力及水动力进行了理论分析,建立了实验模型,对其进行了运动学、动力学仿真实验,仿真结果证明了方案的可行性。

面向旋翼飞行机器人的控制方法研究

旋翼飞行机器人是目前国防、民用两大领域都迫切需要的一种无人平台，它在受限空间内的机动能力，如在狭小的空间起降、空中悬停、超低空飞行、悬停转向等，使得其可以承担固定翼无人机所难以完成的使命，如城市空中信息获取、灾难搜救、反恐防暴、输电线路油气管线巡检、边防反走私反偷渡、森林防火、航拍航测等等。但是，要摆脱遥控的限制，实现旋翼飞行机器人远距离、超视距自主飞行，高性能的机载控制器是必要的前提。但是，由于旋翼飞行机器人的动力学模型复杂，除了飞行器所共有的空气动力学不确定性外，还包括主、尾旋翼之间的强耦合，低空飞行时由旋翼气流引起的地效扰动，低速飞行时的风扰等。上述这些因素导致难以建立起旋翼飞行机器人的动力学模型。 旋翼飞行机器人的动力学复杂性是制约其高性能控制实现的核心问题，如何解决这个问题也就成为目前自动控制领域的重要研究方向之一，其研究内容包括可以归纳为：1) 如何合理简化动力学模型使其适合控制策略设计，2) 如何处理未建模不确定因素和空气动力学扰动，3) 如何提高算法的实时性以便在线实现。 本论文针对上述内容开展深入研究，以在线可实现性为核心目标，旨在建立具有结构简单、实时性好、针对不确定因素及扰动具有强鲁棒性的旋翼飞行机器人控制方法。论文的具体内容安排如下： 第1章，在综述现有控制方法的基础上，深入分析并归纳出旋翼飞行机器人控制策略设计中的难点；同时，鉴于本论文将重点研究在线估计方法与旋翼飞行机器人控制策略相集成的可行性，本章也分析了现有非线性估计方法的特点。 第2章，在简单介绍旋翼飞行机器人飞行机理的基础上，将其视为理想刚体，根据理论力学及叶素理论建立了旋翼飞行机器人六自由度动力学模型。这个模型是一个本质上强非线性、不稳定、高度耦合、非最小相位，带有时变不确定因素的多输入多输出系统。本章对该模型进行了相应地简化，使其可以作为后续控制方法设计与分析的基础。 第3章，重点研究旋翼飞行机器人的独立通道控制方法，提出了两种方案提高基于单输入单输出简化模型的独立通道控制对未建模因素的鲁棒性。首先分析了动态反馈线性化方法在旋翼飞行机器人独立通道控制方面应用的可行性，虽然在理论上可以证明其稳定性，但其对模型的依赖以及计算量大、实时性差等缺点将制约其在实际系统上的应用。以此为基础，又创新地提出基于自调整神经元的控制方法克服未建模扰动和未知时变参数扰动，该方法保留了独立通道控制结构简单、算法易于实现的特点。 第4章，深入研究了UKF算法。在介绍了U变换和标准UKF算法的基础上，提出了具有噪声统计特性自适应能力的UKF算法。该方法以新息方差的实际值与估计值的差为指标函数，用MIT规则作为自适应机制，在线调整UKF中的噪声方差参数，从而提高UKF估计方法在先验信息不足时的估计性能。该方法为基于在线主动估计的旋翼飞行机器人控制奠定了基础。 第5章，提出基于在线主动建模的旋翼飞行机器人控制结构。在该结构中，利用非线性估计方法在线估计旋翼飞行机器人动力学模型中的不确定因素及扰动；同时，将在线估计的结果融入控制策略，实现对模型不确定因素及扰动的抑制。 最后对全文作出总结。

基于惯性摆的波浪能获取机理与方法研究

随着陆地战略资源日益短缺以及经济的全球化进展，海洋资源的开发利用已成为沿海各国的重要发展战略之一，也成为地球资源保护与开发的关注热点。 海洋资源开发和利用能力对于一个国家的科研、经济实力具有重大的影响及意义。由于海洋资源开发利用和地球环境监测的迫切需求，促进了水下机器人、水下潜器等无人水中移动载体技术的发展。能源供给技术是水中移动载体系统的关键技术，能源技术对海洋人工系统的生存、作业、自主能力提升具有重要意义。目前海洋移动人工系统主要依赖自携带能源形式，针对水中移动载体的能量自补给技术研究还处于探索阶段。 地球表面有70%的面积被海水所覆盖，海水中蕴藏巨大的波浪能。具有环保、再生特色的波浪能开发利用技术长期以来一直受到国内外科研人员的关注。随着海洋战略地位的提升，海洋自主人工系统已成为海洋科学技术的重点发展内容。利用波浪能为海洋人工移动载体进行能量补给，是对于海洋波浪能利用的一种新的方法和思路。这对于提高海洋人工系统的自主生存、续航能力，提高人类在海洋资源与环境的探测、开发利用等方面的技术能力无疑具有重大意义。因而研究面向海洋人工系统的波浪能利用机理和系统实现技术无疑具有广泛的应用前景。 本文针对海洋人工移动载体自主能量获取利用这一重大科学技术需求，依托中国科学院基地创新基金项目“基于惯性摆原理的无源系统研究”，探索基于惯性摆机理的移动载体波浪能自主获取的机理，研究相关设计理论和技术方法。 由于目前尚无基于惯性摆机理的海洋移动载体能量自补给技术的相关研究成果。因而本论文的研究主要从理论分析和实验方法两个方面开展。重点分析了惯性摆的外激励能量获取机理，基于惯性摆的波浪机械能获取理论的可行性；开展了惯性摆载体的水动力学建模，原理样机的仿真，频域下的能量建模和优化，非线性波浪条件模拟，惯性摆载体的能量获取结构优化等研究工作。主要研究工作如下： 1.针对基于惯性摆机理的移动载体随机波能获取研究方案，分析了相关单摆及惯性摆机械能量转换机理，采用动量及动量矩定理，构建了惯性摆载体的六自由度运动学和动力学方程。 2．进行了相关水动力系数获取方法研究，获得了水动力系数数学描述。同时，采用虚拟样机方法进行惯性摆载体能量获取的研究，证明了基于惯性摆的波能自主获取方法的可行性及有效性。 3.针对虚拟样机方法建模的复杂性及容易产生错误等问题，进行了基于BP神经网络方法的惯性摆能量吸收效率的建模研究。并研究了基于该模型的不同波向角及波浪频率、载体外形尺寸、质量等的虚拟样机的波浪能吸收效率问题，为载体机构的改进及设计提供了较好的理论模型和基础。 4.开展了频域下惯性摆能量吸收效率研究。研究了基于频域的单惯性摆载体的动力学建模方法以及载体结构优化方法，提出采用多种群遗传算法进行载体结构的优化设计方法。通过仿真实验证明了相关算法的有效性，为系统的优化设计研究提供了理论基础。 5.以能量吸收效率最大为目标，进行了多种惯性摆形式的能量获取最大化分析研究，提出了包括单摆在内的多种可行的形式，给出了对比研究结果，可根据不同的提取形式而确定采用的惯性摆的形式。 6.采用PM谱对非线性波浪进行了模拟，研究了单惯性摆结构在非线性波浪力下的能量获取情况，仿真结果表明，在非线性条件下获取的惯性摆能量要更多，而其他波向角、频率等优化条件均与线性条件下的研究结果相同。

旋翼飞行机器人故障诊断及容错控制方法研究

无人直升机（Unmanned Helicopter）具有固定翼无人机所不具备的很多优势，它具有垂直起降、空中悬停、协调转弯、前飞、侧飞等多种飞行模态。这种独特的飞行性能决定了它的使用价值：在军用方面，无人直升机既能执行各种非杀伤性任务，又能执行各种软硬杀伤性任务，包括侦察、监视、目标截获、诱饵、攻击、通信中继等；在民用方面，无人直升机在航拍、大气监测、交通监控、资源勘探、电力巡检、森林防火、农业等方面具有广泛的应用前景。但是，直升机自身动力学所固有的高度复杂性和不确定性，导致难以对其实现高性能控制，目前视距范围内遥控仍然是其主要的行为方式，这极大地制约着无人直升机的实际应用。近五年来，将机器人学中的自主行为技术与无人直升机平台相结合，构造全自主型无人直升机系统，即所谓的旋翼飞行机器人（Rotary Wing Flying Robot, RWFR），被认为是一种可行的技术路线；同时，与之相关的自主控制方法也成为移动机器人领域的重要研究方向之一。 自主行为能力包括三个层面的内涵：一是自主、在线的环境理解能力，这里的环境不仅是机器人所处的外部环境，也包括其自身的动力学以及健康状态；二是以环境理解为基础的优化行为自主产生能力；三是控制自身本体实现期望行为的能力。对于旋翼飞行机器人而言，其自身健康状态的自主理解以及与之相关的控制行为产生是至关重要的环节，因为它决定着可靠性。旋翼飞行机器人具有多变量、非线性耦合、柔性结构等多种动力学特性[1]，在飞行过程中会遇到风、发动机振动等多种扰动，其机械部件和控制系统极易出现故障，如果故障不能被有效检测或在有限控制周期内没有被及时处理，旋翼飞行机器人就会因其静不稳定的特点而失去控制，导致机体严重损毁甚至地面人员伤亡。 本论文针对旋翼飞行机器人的自主健康诊断与管理能力开展深入研究，重点研究传感器、执行器、飞机本体故障解耦，各子系统故障的检测、辨识与容错控制，面向在线应用的算法实时性等核心问题，旨在建立具有结构简单、实时性好、针对典型故障可实时进行故障诊断及容错控制的方法体系。论文的具体内容如下： 第1章，对故障诊断及容错控制方法的研究现状进行综述，深入分析并归纳旋翼飞行机器人故障诊断与容错控制中存在的问题和发展方向，引出本文的研究内容和重点。同时，在简要介绍国内外各种旋翼飞行机器人实验平台的基础上，选择一种具有典型性的实验平台进行深入分析，总结了其特点和不足，为研制自己的实验平台系统奠定基础。 第2章，作为论文后续方法研究、仿真及实验验证的基础，首先介绍旋翼飞行机器人的动力学模型，接下来介绍本人参与研制的开放式仿真系统，并着重介绍以作者为主要负责人所设计、研发的40公斤起飞重量级旋翼飞行机器人开放式飞行实验平台—ServoHeli-40。 第3章，以阐述ServoHeli-40旋翼飞行机器人自主飞行控制结构及独立通道控制方法为基础，创新性地提出旋翼飞行机器人容错控制体系结构，并分析该结构中各模块任务及作用。针对传感器和执行器故障之间的耦合问题，提出基于贝叶斯推理的异类故障解耦方法，为独立研究传感器、执行器故障扫清障碍。 第4章，重点研究旋翼飞行机器人传感器故障诊断及容错控制。针对不同故障检测类型和阶段，提出了三种方法。首先针对突变类型的传感器故障采用基于db2的小波变换方法进行检测，对传感器数据进行时频域同时变换，实现实时准确分析；其次应用自适应神经网络方法对故障信号及正常飞行中飞行模态变化进行区分，提高了故障检测的可信性与可靠性；最后以多源传感器信息融合为基础，探索在部分传感器出现故障的情况下提供次优的传感器数据。 第5章，重点研究执行器软性故障的在线估计及控制策略在线重构问题。首先提出旋翼飞行机器人执行器定量软性故障的数学表达方法，深入研究两种自适应UKF方法在执行器软性故障在线估计方面的有效性和可行性；最后，提出一种基于故障参数在线估计的控制策略重构方法。 论文针对所提出的方法，以ServoHeli-40旋翼飞行机器人的实际拟合动力学模型为对象开展了仿真研究，部分内容在ServoHeli-40上进行了实际飞行实验验证。

摆动液压缸组合密封的建模与计算

七功能水下机械手采用至少1个摆动液压缸作为关节驱动。为进行水下作业要求摆动液压缸工作压力为21MPa。为实现其作业压力,对摆动液压缸采用聚四氟乙烯(PTFE)-橡胶组合密封。设定密封件压缩量,对其进行力学分析和弹性流体动力学(EHL)建模,计算出密封压力、油膜厚度等参数。计算结果表明组合密封能够完成21MPa下摆动液压缸的密封。

水下七功能机械手摆动液压缸的研究

强作业型七功能水下机械手是水下机器人不可或缺的通用水下作业工具。随着对海洋的探索加快，对其需求量将越来越大。我国在强作业型七功能水下机械手的研究上与世界先进水平相差很大。对强作业型七功能水下机械手展开研发工作势在必行。 本论文对七功能机械手的重要关节驱动－摆动液压缸进行研究。首先确定摆动缸的结构选型。然后针对摆动液压缸的组合密封展开研究，以明确组合密封各部分的功能，优化密封件的密封性能。最后对摆动缸进行详细设计，并对其工作性能的参数进行估算。 首先，对组合密封模型进行简化后，用弹性流体润滑（EHL）理论进行分析计算，以得到密封件压缩量与密封油膜厚度、泄漏量、摩擦力的关系。 然后将用有限元(FEM)工具分别建立简化模型、叶片模型和组合密封模型，按接近实际的状态对模型进行约束和加载，以分析其变形和应力分布，并根据最终结果对EHL计算结果进行相应修正，以辅助摆动液压缸的设计。完成以上工作后，根据分析结果确定密封件适当的压缩量。同时，对轴端密封建立模型，用FEM工具对其进行受力变形分析，以改善其密封情况。 对密封件的分析表明，采用论文给出的组合密封结构，其中起支撑作用的Ｏ形圈受液压压力变形产生“自封”效应，强化了密封效果。组合密封的在给定压缩量时的，其O形圈的硬度对密封压力影响很大，应选择更高硬度的Ｏ形圈，以完成对摆动液压缸叶片的密封。端密封受装配后轴沿轴向的游动影响明显，应提高此处Ｏ形圈的直径并适当增加其预压缩量。

整合多尺度地球物理数据建立高分辨率储层模型的方法及应用

Most of the fields in China are in the middle-late development phase or are mature fields. It becomes more and more difficult to develop the remaining oil/gas. Therefore, it is import to enhance oil/gas recovery in order to maintain the production. Fine scale modeling is a key to improve the recovery. Incorporation of geological, seismic and well log data to 3D earth modeling is essential to build such models. In Ken71 field, well log, cross-well seismic and 3D seismic data are available. A key issue is to build 3D earth model with these multi-scales data for oil field development.In this dissertation, studies on sequential Gaussian-Bayesian simulation have been conducted. Its comparison with cokriging and sequential Gaussian simulation has been performed. The realizations generated by sequential Gaussian-Bayesian simulation have higher vertical resolution than those generated by other methods. Less differences between these realization and true case are observed. With field data, it is proved that incorporating well log, cross-well seismic and 3D seismic into 3D fine scale model is reliable. In addition, the advantages of sequential Gaussian-Bayesian simulation and conditions for input data are demonstrated. In Ken71 field, the impedance difference between sandstone and shale is small. It would be difficult to identify sandstone in the reservoir with traditional impedance inversion. After comparisons of different inversion techniques, stochastic hillclimbing inversion was applied. With this method, shale content inversion is performed using 3D seismic data. Then, the inverted results of shale content and well log data are incorporated into 3D models. This demonstrates a procedure to build fine scale models using multi scale seismic data, especially 3D seismic amplitude volume.The models generated through sequential Gaussian-Bayesian simulation have several advantages including: (1) higher vertical resolution compared with 3D inverted acoustic impedance (AI); (2) consistency of lateral variation as 3D inverted AI; (3) more reliability due to integration cross-well seismic data. It is observed that the precision of the model depends on the 3D inversion.

基于量子蒙特卡罗的地震波反演方法

The primary approaches for people to understand the inner properties of the earth and the distribution of the mineral resources are mainly coming from surface geology survey and geophysical/geochemical data inversion and interpretation. The purpose of seismic inversion is to extract information of the subsurface stratum geometrical structures and the distribution of material properties from seismic wave which is used for resource prospecting, exploitation and the study for inner structure of the earth and its dynamic process. Although the study of seismic parameter inversion has achieved a lot since 1950s, some problems are still persisting when applying in real data due to their nonlinearity and ill-posedness. Most inversion methods we use to invert geophysical parameters are based on iterative inversion which depends largely on the initial model and constraint conditions. It would be difficult to obtain a believable result when taking into consideration different factors such as environmental and equipment noise that exist in seismic wave excitation, propagation and acquisition. The seismic inversion based on real data is a typical nonlinear problem, which means most of their objective functions are multi-minimum. It makes them formidable to be solved using commonly used methods such as general-linearization and quasi-linearization inversion because of local convergence. Global nonlinear search methods which do not rely heavily on the initial model seem more promising, but the amount of computation required for real data process is unacceptable. In order to solve those problems mentioned above, this paper addresses a kind of global nonlinear inversion method which brings Quantum Monte Carlo (QMC) method into geophysical inverse problems. QMC has been used as an effective numerical method to study quantum many-body system which is often governed by Schrödinger equation. This method can be categorized into zero temperature method and finite temperature method. This paper is subdivided into four parts. In the first one, we briefly review the theory of QMC method and find out the connections with geophysical nonlinear inversion, and then give the flow chart of the algorithm. In the second part, we apply four QMC inverse methods in 1D wave equation impedance inversion and generally compare their results with convergence rate and accuracy. The feasibility, stability, and anti-noise capacity of the algorithms are also discussed within this chapter. Numerical results demonstrate that it is possible to solve geophysical nonlinear inversion and other nonlinear optimization problems by means of QMC method. They are also showing that Green’s function Monte Carlo (GFMC) and diffusion Monte Carlo (DMC) are more applicable than Path Integral Monte Carlo (PIMC) and Variational Monte Carlo (VMC) in real data. The third part provides the parallel version of serial QMC algorithms which are applied in a 2D acoustic velocity inversion and real seismic data processing and further discusses these algorithms’ globality and anti-noise capacity. The inverted results show the robustness of these algorithms which make them feasible to be used in 2D inversion and real data processing. The parallel inversion algorithms in this chapter are also applicable in other optimization. Finally, some useful conclusions are obtained in the last section. The analysis and comparison of the results indicate that it is successful to bring QMC into geophysical inversion. QMC is a kind of nonlinear inversion method which guarantees stability, efficiency and anti-noise. The most appealing property is that it does not rely heavily on the initial model and can be suited to nonlinear and multi-minimum geophysical inverse problems. This method can also be used in other filed regarding nonlinear optimization.

松辽盆地南部腰英台区块低渗透储层整体压裂改造技术研究

The Yaoyingtai Block is located within the northeastern Changling Depression of southern Songliao Basin, where the reservoir sandstones are petrophysically characterized by very low permeability, which results in the low success probability of artificial fracturing, and the low oil yield by water injection in the course of oil production. In order to improve the situations as stated above, this research aims to work out an integral fracturing technology and strategy applicable to the low permeable reservoirs in Yaoyingtai Block. Under the guidance of geological theory, reservoir engineering and technology, the subsurface occurrences of natural and hydraulic fractures in the reservoirs are expected to be delineated, and appropriate fracturing fluids and proppants are to be optimized, based on the data of drilling, well logging, laboratory and field experiments, and geological data. These approaches lay the basis of the integral fracturing technology suitable for the low permeable reservoir in the study area. Based on core sample test, in-situ stress analysis of well logging, and forward and inversion stress field modeling, as well as fluid dynamic analysis, the maximum in-situ stress field is unraveled to be extended nearly along the E-W direction (clustering along N85-135°E) as is demonstrated by the E-W trending tensional fractures. Hydraulic fractures are distributed approximately along the E-W direction as well. Faulting activities could have exerted obvious influences on the distribution of fractures, which were preferentially developed along fault zones. Based on reservoir sensitivity analysis, integrated with studies on rock mechanics, in-situ stress, natural fracture distribution and production in injection-production pilot area, the influences of primary fractures on fracturing operation are analyzed, and a diagnostic technology for primary fractures during depressurization is accordingly developed. An appropriate fracturing fluid (hydroxypropyl guar gum) and a proppant (Yixing ceramsite, with a moderate-density, 0.45-0.9mm in size) applicable to Qingshankou Formation reservoir are worked out through extensive optimization analysis. The fracturing fluid can decrease the damage to the oil reservoir, and the friction in fracturing operation, improving the effect of fracturing operation. Some problems, such as sand-out at early stage and low success rate of fracturing operations, have been effectively solved, through pre-fracturing formation evaluation, “suspension plug” fracturing, real-time monitoring and limited-flow fracturing. Through analysis of fracture-bearing tight reservoir with variable densities and dynamic analysis of influences of well patterns on fracturing by using numerical simulation, a fracturing operation scheme for the Qingshankou Formation reservoir is proposed here as being better to compress the short factures, rather than to compress the long fractures during hydraulic fracturing. It is suggested to adopt the 450m×150m inverted 9-spot well pattern in a diamond shape with wells placed parallel to fractures and a half fracture length of 60-75m.

非自喷层测试及评价解释技术研究与应用

Now low porosity and low permeability reservoir is one of the main targets of exploration for the onshore oilfields of China. Most of the reservoirs are none flowing because of bad formation percolation condition, poor gas oil ratio , low formation pressure coefficient and other factors. In the recent years, a number of domestic oilfields have carried out some research work and achieved some success on oil testing and production technology in such formation. But by now, there is still no systematic and mature technology, particularly testing technology in none flowing formation is still needed further study. Based on study the key problem of well testing and interpretation technology in none flowing formation, solve the important problems in well testing technology, continuously improve and innovate geological information acquisition technology for none flowing reservoir, accurately acquire boundary information and evaluate reservoir flow characteristics. Its wide application remarkable result has shown. The main results and cognitions obtained from research are as follows: 1. This new technology research results help solve the occurrent problems in well testing process for none flowing formations, such as small investigation radius, poor representative of interpretation results from the poor data, low level application of interpretation results. This new technology helps create favorable conditions for early precise reservoir evaluation and reduction of the risk of exploration. 2. The technological difficulties for none flowing well testing are successfully solved by using none flowing formation combined mechanical tool string .This method has been proved by its applications to be able to improve the efficiency of the testing and the quantity of the acquired test data ,and so as to enhance the application of the interpretation results of the test in development of oil fields. 3. The application of the rotary formation tester, selective test valve, well testing string and their allier tools help to resolve problems such as the operation of opening and shutting-in the well under different well conditions, to broaden the scope of well test technology for none flowing formations. 4. Refined Testing Technique for production Wells has greatly shortened the testing dwration and improved the efficiency and accuracy of operation, enriched test results, and at the same time created conditions for conducting multi-well interference well testing.

粘弹性介质中的地震波传播与波形反演研究

The real earth is far away from an ideal elastic ball. The movement of structures or fluid and scattering of thin-layer would inevitably affect seismic wave propagation, which is demonstrated mainly as energy nongeometrical attenuation. Today, most of theoretical researches and applications take the assumption that all media studied are fully elastic. Ignoring the viscoelastic property would, in some circumstances, lead to amplitude and phase distortion, which will indirectly affect extraction of traveltime and waveform we use in imaging and inversion. In order to investigate the response of seismic wave propagation and improve the imaging and inversion quality in complex media, we need not only consider into attenuation of the real media but also implement it by means of efficient numerical methods and imaging techniques. As for numerical modeling, most widely used methods, such as finite difference, finite element and pseudospectral algorithms, have difficulty in dealing with problem of simultaneously improving accuracy and efficiency in computation. To partially overcome this difficulty, this paper devises a matrix differentiator method and an optimal convolutional differentiator method based on staggered-grid Fourier pseudospectral differentiation, and a staggered-grid optimal Shannon singular kernel convolutional differentiator by function distribution theory, which then are used to study seismic wave propagation in viscoelastic media. Results through comparisons and accuracy analysis demonstrate that optimal convolutional differentiator methods can solve well the incompatibility between accuracy and efficiency, and are almost twice more accurate than the same-length finite difference. They can efficiently reduce dispersion and provide high-precision waveform data. On the basis of frequency-domain wavefield modeling, we discuss how to directly solve linear equations and point out that when compared to the time-domain methods, frequency-domain methods would be more convenient to handle the multi-source problem and be much easier to incorporate medium attenuation. We also prove the equivalence of the time- and frequency-domain methods by using numerical tests when assumptions with non-relaxation modulus and quality factor are made, and analyze the reason that causes waveform difference. In frequency-domain waveform inversion, experiments have been conducted with transmission, crosshole and reflection data. By using the relation between media scales and characteristic frequencies, we analyze the capacity of the frequency-domain sequential inversion method in anti-noising and dealing with non-uniqueness of nonlinear optimization. In crosshole experiments, we find the main sources of inversion error and figure out how incorrect quality factor would affect inverted results. When dealing with surface reflection data, several frequencies have been chosen with optimal frequency selection strategy, with which we use to carry out sequential and simultaneous inversions to verify how important low frequency data are to the inverted results and the functionality of simultaneous inversion in anti-noising. Finally, I come with some conclusions about the whole work I have done in this dissertation and discuss detailly the existing and would-be problems in it. I also point out the possible directions and theories we should go and deepen, which, to some extent, would provide a helpful reference to researchers who are interested in seismic wave propagation and imaging in complex media.

用宽频带远震体波波形研究中国及邻近地区地壳构造及地质意义初探

The theory and approach of the broadband teleseismic body waveform inversion are expatiated in this paper, and the defining the crust structure's methods are developed. Based on the teleseismic P-wave data, the theoretic image of the P-wave radical component is calculated via the convolution of the teleseismic P-wave vertical component and the transform function, and thereby a P-wavefrom inversion method is built. The applied results show the approach effective, stable and its resolution high. The exact and reliable teleseismic P waveforms recorded by CDSN and IRIS and its geodynamics are utilized to obtain China and its vicinage lithospheric transfer functions, this region ithospheric structure is inverted through the inversion of reliable transfer functions, the new knowledge about the deep structure of China and its vicinage is obtained, and the reliable seismological evidence is provided to reveal the geodynamic evolution processes and set up the continental collisional theory. The major studies are as follows: Two important methods to study crustal and upper mantle structure -- body wave travel-time inversion and waveform modeling are reviewed systematically. Based on ray theory, travel-time inversion is characterized by simplicity, crustal and upper mantle velocity model can be obtained by using 1-D travel-time inversion preliminary, which introduces the reference model for studying focal location, focal mechanism, and fine structure of crustal and upper mantle. The large-scale lateral inhomogeneity of crustal and upper mantle can be obtained by three-dimensional t ravel-time seismic tomography. Based on elastic dynamics, through the fitting between theoretical seismogram and observed seismogram, waveform modeling can interpret the detail waveform and further uncover one-dimensional fine structure and lateral variation of crustal and upper mantle, especially the media characteristics of singular zones of ray. Whatever travel-time inversion and waveform modeling is supposed under certain approximate conditions, with respective advantages and disadvantages, and provide convincing structure information for elucidating physical and chemical features and geodynamic processes of crustal and upper mantle. Because the direct wave, surface wave, and refraction wave have lower resolution in investigating seismic velocity transitional zone, which is inadequate to study seismic discontinuities. On the contrary, both the converse and reflected wave, which sample the discontinuities directly, must be carefully picked up from seismogram to constrain the velocity transitional zones. Not only can the converse wave and reflected wave study the crustal structure, but also investigate the upper mantle discontinuities. There are a number of global and regional seismic discontinuities in the crustal and upper mantle, which plays a significant role in understanding physical and chemical properties and geodynamic processes of crustal and upper mantle. The broadband teleseismic P waveform inversion is studied particularly. The teleseismic P waveforms contain a lot of information related to source time function, near-source structure, propagation effect through the mantle, receiver structure, and instrument response, receiver function is isolated form teleseismic P waveform through the vector rotation of horizontal components into ray direction and the deconvolution of vertical component from the radial and tangential components of ground motion, the resulting time series is dominated by local receiver structure effect, and is hardly irrelevant to source and deep mantle effects. Receiver function is horizontal response, which eliminate multiple P wave reflection and retain direct wave and P-S converted waves, and is sensitive to the vertical variation of S wave velocity. Velocity structure beneath a seismic station has different response to radial and vertical component of an accident teleseismic P wave. To avoid the limits caused by a simplified assumption on the vertical response, the receiver function method is mended. In the frequency domain, the transfer function is showed by the ratio of radical response and vertical response of the media to P wave. In the time domain, the radial synthetic waveform can be obtained by the convolution of the transfer function with the vertical wave. In order to overcome the numerical instability, generalized reflection and transmission coefficient matrix method is applied to calculate the synthetic waveform so that all multi-reflection and phase conversion response can be included. A new inversion method, VFSA-LM method, is used in this study, which successfully combines very fast simulated annealing method (VFSA) with damped least square inversion method (LM). Synthetic waveform inversion test confirms its effectiveness and efficiency. Broadband teleseismic P waveform inversion is applied in lithospheric velocity study of China and its vicinage. According to the data of high quality CDSN and IRIS, we obtained an outline map showing the distribution of Asian continental crustal thickness. Based on these results gained, the features of distribution of the crustal thickness and outline of crustal structure under the Asian continent have been analyzed and studied. Finally, this paper advances the principal characteristics of the Asian continental crust. There exist four vast areas of relatively minor variations in the crustal thickness, namely, northern, eastern southern and central areas of Asian crust. As a byproduct, the earthquake location is discussed, Which is a basic issue in seismology. Because of the strong trade-off between the assumed initial time and focal depth and the nonlinear of the inversion problems, this issue is not settled at all. Aimed at the problem, a new earthquake location method named SAMS method is presented, In which, the objective function is the absolute value of the remnants of travel times together with the arrival times and use the Fast Simulated Annealing method is used to inverse. Applied in the Chi-Chi event relocation of Taiwan occurred on Sep 21, 2000, the results show that the SAMS method not only can reduce the effects of the trade-off between the initial time and focal depth, but can get better stability and resolving power. At the end of the paper, the inverse Q filtering method for compensating attenuation and frequency dispersion used in the seismic section of depth domain is discussed. According to the forward and inverse results of synthesized seismic records, our Q filtrating operator of the depth domain is consistent with the seismic laws in the absorbing media, which not only considers the effect of the media absorbing of the waves, but also fits the deformation laws, namely the frequency dispersion of the body wave. Two post stacked profiles about 60KM, a neritic area of China processed, the result shows that after the forward Q filtering of the depth domain, the wide of the wavelet of the middle and deep layers is compressed, the resolution and signal noise ratio are enhanced, and the primary sharp and energy distribution of the profile are retained.

人工源频率域大地电磁法正反演研究

The CSAMT method is playing an important role in the exploration of geothermal and the pre-exploration in tunnel construction project recently. In order to instruct the interpretation technique for the field data, the forward method from ID to 3D and inversion method in ID and 2D are developed in this paper for the artificial source magnetotelluric in frequency domain. In general, the artificial source data are inverted only after the near field is corrected on the basis of the assumption of half-homogeneous space; however, this method is not suitable for the complex structure because the assumption is not valid any more. Recently the new idea about inversion scheme without near field correction is published in order to avoid the near field correction error. We try to discuss different inversion scheme in ID and 2D using the data without near field correction.The numerical integration method is used to do the forward modeling in ID CSAMT method o The infinite line source is used in the 2D finite-element forward modeling, where the near-field effect is occurred as in the CSAMT method because of using artificial source. The pseudo-delta function is used to modeling the source distribution, which reduces the singularity when solving the finite-element equations. The effect on the exploration area is discussed when anomalous body exists under the source or between the source and exploration area; A series of digital test show the 2D finite element method are correct, the results of modeling has important significant for CSAMT data interpretation. For 3D finite-element forward modeling, the finite-element equation is derived by Galerkin method and the divergence condition is add forcedly to the forward equation, the forward modeling result of the half homogeneous space model is correct.The new inversion idea without near field correction is followed to develop new inversion methods in ID and 2D in the paper. All of the inversion schemes use the data without near field correction, which avoid introducing errors caused by near field correction. The modified grid parameter method and the layer-by-layer inversion method are joined in the ID inversion scheme. The RRI method with artificial source are developed and finite-element inversion method are used in 2D inversion scheme. The inversion results using digital data and the field data are accordant to the model and the known geology data separately, which means the inversion without near field correction is accessible. The feasibility to invert the data only in exploration area is discussed when the anomalous body exists between the source and the exploration area.