基于Seislet-TV双正则化约束的地震随机噪声压制方法          下载免费PDF全文

张鹏  刘洋  刘鑫明  刘财  张亮 《地球物理学报》2020,63(5):2056-2068

人工地震数据总是受到随机噪声的干扰,地震数据时-空变的特性使得常规去噪方法处理效果并不理想,容易导致有效信号的损失.目前广泛应用的预测滤波类方法存在处理时变数据能力不足的问题.随着压缩感知理论的不断完善,稀疏变换阈值算法能够解决时变地震数据噪声压制问题,但是常规的稀疏变换方法,如傅里叶变换,小波变换等,并不是特殊针对地震数据设计的,很难提供地震数据最佳的压缩特征,同时,常规阈值算法容易导致去噪结果过于平滑.因此开发更加有效的时-空变地震数据信噪分离方法具有重要的工业价值.本文将地震数据信噪分离问题归纳为数学基追踪问题,在压缩感知理论框架下,利用特殊针对地震数据设计的VD-seislet稀疏变换方法,结合全变差(TV)算法,构建seislet-TV双正则化条件,并利用分裂Bregman迭代算法求解约束最优化问题,实现地震数据的有效信噪分离.通过理论模型和实际数据测试本文方法,并且与工业标准FXdecon方法进行比较,结果表明基于seislet-TV双正则化约束条件的迭代方法能够更加有效地保护时-空变地震信号,压制地震数据中的强随机噪声.  相似文献   

长距离曲线顶管技术在电力管道工程中的应用     

陈勇  陈永光  黄以华 《岩土钻凿工程》2011,(2):63-68

非开挖技术在市政管道铺设中的应用越来越广泛,从直径50mm通讯光缆-直径3000mm混凝土管道,采用非开挖安装各种管道都变得很普遍。同时,鉴于非开挖技术综合效益优越性、环境友好型施工特点,也逐渐被工程建设方、社会所接受和认可。泥水平衡顶管技术是非开挖最为成熟的技术之一,在城市市政设施建设中也起着举足轻重的作用。采用泥水平衡顶管技术进行城市雨污分流改造已经在国内大量城市取得应用,但是,采用泥水平衡顶管在岩层中铺设直径达2000mm埋深在5m电力管道,在国内为数不多,在福建厦门地区也是尚属首次。通过在工程施工中对设备、施工工艺的摸索和改进,最后采用泥水平衡顶管施工技术成功铺设建设方所要求的电力管道。本工程将为在福建地区采用预管技术铺设大口径长距离、曲线管道提供了指导和借鉴。  相似文献   

内膜揭除——排水管道非开挖内衬修复的要素     

何渊 《岩土钻凿工程》2011,(3):45-48

本文概要论述了排水管道内衬修复技术应满足的一般特征;同时从天津开发区现有排水管道运行中面临的实际问题出发,分析了非开挖内衬修复工艺选择时的关注点;特别强调了内膜揭除在排水管道内衬修复技术应用中的必要性。  相似文献   

Pipe Service Age Effect on Chlorine Decay in Drinking‐Water Transmission and Distribution Systems     

A. O. Al‐Jasser 《洁净——土壤、空气、水》2011,39(9):827-832

Maintaining acceptable quality of water transported in the transmission and distribution system requires the chlorination of water beyond the treatment plant. While flowing through pipes, the chlorine concentration decreases for different reasons. Reaction with the pipe material itself and the reaction with both the biofilm and tubercles formed on the pipe wall are known as pipe wall demand. This varies with pipe parameters. The aim of this paper was to assess the impact of the service age of pipes on the chlorine wall decay constant. One hundred and fifty three pipe sections of different sizes and four different pipe materials were collected and tested for their chlorine first‐order wall decay constants. The results showed that pipe service age was an important factor that must not be ignored. For the range of the 55 years of pipe service age used in this study, the change in the wall decay ranged from 8 to 531% of the corresponding values in the recently installed pipes. The effect of service age on the wall decay constants was most evident in steel pipes. Other important findings were reached.  相似文献   

Nonplanar multi-modal vibrations of fluid-conveying risers under shear cross flows     

《Applied Ocean Research》2019

Risers/pipes conveying fluid are a typical kind of slender structures commonly used in marine engineering. It is of great academic significance and application value for us to evaluate and understand the vibration characteristics and nonlinear responses of these risers under the combined action of internal and external fluid flows. In this paper, the nonplanar vibrations and multi-modal responses of pinned-pinned risers in shear cross flow are numerically studied. With this objective in mind, the van der Pol wake oscillators are used to simulate the dynamical behavior of the vortex shedding in the wake. Two nonlinear equations of motion of the riser are proposed to govern the lateral responses of the riser structure. The nonplanar nonlinear equations for the riser and wake are then discretized by employing Galerkin's method and solved by using a fourth-order Runge–Kutta integration algorithm. Theoretical results show that the coupled frequencies for cross-flow (CF) and in-line (IL) motions and the corresponding coupled damping ratio could be influenced by the external and/or internal fluid velocities. Based on extensive calculations, the dynamical behavior of the riser with various internal and external flow velocities are presented in the form of bifurcation diagrams, time traces, phase portraits, oscillation trajectories and response spectrum curves. It is shown that some interesting dynamical phenomena, such as ‘lock-in’ state, ‘figure-of-eight’ trajectory and quasi-periodic oscillation, could occur in such a fluid-structure interaction system. Our results also demonstrate that the shear parameter can significantly affect the dynamic responses of the riser. When the shear parameter of the cross flow is large, multi-modal quasi-periodic responses of the riser can be excited, showing some new features undetected in the system of fluid-conveying risers in uniform cross flow.  相似文献   

Seepage simulation using pipe network flow model in a discrete element system     

《Computers and Geotechnics》2017

The pipe network flow model can simulate the seepage process with DEM conveniently because of its simple algorithm. However, whether it can recover the correct seepage process has not been verified. In this paper, the equation to update the fluid pressure is rebuilt according to the flow conservation. Through the steady seepage simulation, this algorithm is verified to be able to recover Darcy’s law, and the equation to calibrate the aperture according to macro permeability is derived. Furthermore, the modified algorithm is used to simulate the unsteady seepage process, and the results show good agreement with the analytical solutions.  相似文献   

超浅层顶管施工诱发地表沉降规律分析     

张海生 《岩土钻凿工程》2014,(2):61-66

随着社会化进程的推进,顶管法在各类城市地下管线的施工中得到广泛应用。超浅层顶管施工。绝大多数是在已建道路下进行的,施工时,易发生地表沉降,且沉降量很大,易破坏路面。为此,超浅层顶管施工对周围环境的影响已引起人们足够的重视,其施工及控制技术是目前迫切需要掌握的。利用有限差分软件FLAC3D对顶管施工过程中地表沉降进行模拟,旨在了解超浅层顶管施工引起的力学效应。对超浅层顶管施工引起的地表沉降作出预测,为采取措施减小地表沉降提供依据。  相似文献   

爆管法在北美地区的应用现状     

赵士鹤  陈亚洲  周俊  关蕾蕾  孙平贺 《岩土钻凿工程》2014,(4):46-52

随着市政部门不断寻求节约成本的创新技术来解决地下基础设施问题,非开挖管线更换技术诸如爆管法成为可行的选择。爆管法是一种用相等或更大口径的新管更换现有地下供水给水、污水排水和燃气输送管线的施工方法。它是唯一一种完全沿旧管线线路铺设的施工方法。这使得安装新管线施工时无须征求额外通行权。爆管法兴起于20纪80年代,现在已遍布北美地区。本文通过对来自2007—2010年加拿大和美国的886个项目的调查问卷结果的总结,讨论了目前非开挖更管技术的趋势,分析了爆管法施工中的因素：包括设备的使用、采购与支付的形式、管线扩径的限制和施工的风险。  相似文献   

长输管道局部腐蚀体积型缺陷逐次评价     

陈婷  赵民  乌效鸣  王俊波  李列平 《岩土钻凿工程》2014,(2):145-147

局部腐蚀包括缝隙腐蚀、应力腐蚀、腐蚀磨损、氢腐蚀,H2S应力腐蚀和氢腐蚀是长输管道最容易发生的一种局部腐蚀方式。针对长输管道易发生局部腐蚀的特点,参考其他管道评价方法,根据现场管道的安全状况,提出了适用于现场的含局部腐蚀体积型缺陷管道的三步评价法。该方法不需要考虑管道的腐蚀裕量,简化公式,便于现场计算。  相似文献   

Estimation of parameters in a split functional model of geodetic observations (<Emphasis Type="Italic">M</Emphasis><Subscript>split</Subscript> estimation)     

Z. Wiśniewski 《Journal of Geodesy》2009,83(2):105-120

The paper presents a method of estimating parameters in two competitive functional models. The models considered here are concerned with the same observation set and are based on the assumption that an observation may result from a realization of either of two different random variables. These variables differ from one another at least in the main characteristic (for example, outliers can be realizations of one variable). A quantity that describes the opportunity of identifying a single observation with one random variable is assumed to be known. That quantity, called the elementary split potential, is strictly referred to the amount of information that an observation can provide about two competitive assumptions concerning the observation distribution. Parameter assessments that maximize the global elementary split potential (concerning all observations), are called M _split estimators. A generalization of M _split estimation presented in the paper refers to the theoretical foundation of M-estimation. An erratum to this article can be found at  相似文献