Ground roll attenuation using a time-frequency dependent polarization filter based on the S transform

The ground roll and body wave usually show significant differences in arrival time, frequency content, and polarization characteristics, and conventional polarization filters that operate in either the time or frequency domain cannot consider all these elements. Therefore, we have developed a time-frequency dependent polarization filter based on the S transform to attenuate the ground roll in seismic records. Our approach adopts the complex coefficients of the S transform of the multi-component seismic data to estimate the local polarization attributes and utilizes the estimated attributes to construct the filter function. In this study, we select the S transform to design this polarization filter because its scalable window length can ensure the same number of cycles of a Fourier sinusoid, thereby rendering more precise estimation of local polarization attributes. The results of applying our approach in synthetic and real data examples demonstrate that the proposed polarization filter can effectively attenuate the ground roll and successfully preserve the body wave.

Robust adaptive polarization analysis method for eliminating ground roll in 3C land seismics

To improve the data quality of converted waves, and better identify and suppress the strong ground-roll interference in three-component （3C） seismic recordings on land, we present an adaptive polarization filtering method, which can effectively separate the ground- roll interference by combining complex polarization and instantaneous polarization analysis. The ground roll noise is characterized by elliptical plane polarization, strong energy, low apparent velocity, and low frequency. After low-pass filtering of the 3C data input within a given time-window of the ground roll, the complex covariance matrix is decomposed using the sliding time window with overlapping data and length that depends on the dominant ground-roll frequency. The ground-roll model is established using the main eigenvectors, and the ground roll is detected and identified using the instantaneous polarization area attributes and average energy constraints of the ground-roll zone. Finally, the ground roll is subtracted. The threshold of the method is stable and easy to select, and offers good ground- roll detection. The method is a robust polarization filtering method. Model calculations and actual data indicate that the method can effectively identify and attenuate ground roll while preserving the effective signals.

Ground roll wave suppression based on wavelet frequency division and radial trace transform

Ground roll waves interfere with seismic data. The suppression of ground roll waves based on the division of wavelet frequencies considers the low-frequency characteristics of ground roll waves. However, this method will not be effective when the ground roll wave and the effective signal have the same frequency bands because of overlapping. The radial trace transform （RTT） considers the apparent velocity difference between the effective signal and the ground roll wave to suppress the latter, but affects the low-frequency components of the former. This study proposes a ground roll wave suppression method by combining the wavelet frequency division and the RTT based on the difference between the ground roll wave velocity and the effective signal and their energy difference in the wavelet domain, thus making full use of the advantages of both methods. First, we decompose the seismic data into different frequency bands through wavelet transform. Second, the RTT and low-cut filtering are applied to the low-frequency band, where the ground roll waves are appearing. Third, we reconstruct the seismic record without ground roll waves by using the inverse RTT and the remaining frequency bands. The proposed method not only improves the ground roll wave suppression, but also protects the signal integrity. The numerical simulation and real seismic data processing results suggest that the proposed method has a strong ability to denoise while preserving the amplitude.

Ground roll attenuation based on an empirical curvelet transform

In the field of seismic exploration, ground roll seriously affects the deep effective reflections from subsurface deep structures. Traditional curvelet transform cannot provide an adaptive basis function to achieve a suboptimal denoised result. In this paper, we propose a method based on empirical curvelet transform （ECT） for ground roll attenuation. Unlike the traditional curvelet transform, this method not only decomposes seismic data into multiscale and multi-directional components, but also provides an adaptive filter bank according to frequency content of seismic data itself. So, ground roll can be separated by using this method. However, as the frequency of reflection and ground roll components are close, we apply singular value decomposition （SVD） in the curvelet domain to differentiate the ground roll and reflection better. Examples of synthetic and field seismic data reveal that the proposed method based ECT performs better than the traditional curvelet method in terms of the suppression of ground roll.

Ground roll separation method via threshold fi ltering and constraint of seismic wavelet support in curvelet domain

Most traditional ground roll separation methods utilize only the difference in geometric characteristics between the ground roll and the refl ection wave to separate them.When the geometric characteristics of data are complex,these methods often lead to damage of the reflection wave or incompletely suppress the ground roll.To solve this problem,we proposed a novel ground roll separation method via threshold filtering and constraint of seismic wavelet support in the curvelet domain;this method is called the TFWS method.First,curvelet threshold fi ltering(CTF)is performed by using the diff erence of the curvelet coeffi cient of the refl ection wave and the ground roll in the location,scale,and slope of their events to eliminate most of the ground roll.Second,the degree of the local damaged signal or the local residual noise is estimated as the local weighting coeffi cient.Under the constraints of seismic wavelet and local weighting coeffi cient,the L1 norm of the refl ection coeffi cient is minimized in the curvelet domain to recover the damaged refl ection wave and attenuate the residual noise.The local weighting coeffi cient in this paper is obtained by calculating the local correlation coeffi cient between the high-pass fi ltering result and the CFT result.We applied the TFWS method to simulate and fi eld data and compared its performance with that of frequency and wavenumber filtering and the CFT method.Results show that the TFWS method can attenuate not only linear ground roll,aliased ground roll,and nonlinear noise but also strong noise with a slope close to the refl ection events.

机场地面服务资源滚动时域调度方法

为了应对航班随机到达对机场地面服务资源调度的影响,针对问题的特点设计了一种滚动时域调度方法(rolling horizon scheduling method,RHSM)。先按时间轴将原问题分解为一系列子问题,再以最小化航班延误总成本和同类资源负荷均衡为目标,构建项目-资源分级调度的数学模型,对每轮滚动时域内的子问题进行调度,最后由各个子问题的解构成原问题的近似解。这样就把复杂问题分解为若干小问题逐个求解,保证了资源调度的实时性。以广州白云国际机场某天3个不同规模的数据:01:00-02:00、15:00-16:00及13:00-21:00,验证该方法的性能。实验结果表明,RHSM能够应对航班到达时间的随机性,并且相较于时间窗解耦调度方法,在01:00-02:00小规模数据中,当求解总时长相同时,选择合适参数的RHSM可降低36.79%航班延误总成本;在15:00-16:00和13:00-21:00的中、大规模数据中,RHSM具有较快的求解速度和较小的计算机内存空间。因此所提方法是具有可行性的,有助于机场地面服务提质增效。

基于模糊PID的球形两栖机器人的设计及控制

为了解决移动机器人对工作环境要求严格的问题,设计了一种适用于多变、狭窄环境的轻小型球形陆空两栖机器人,具有地面滚动和空中飞行两种运动模式,可以自主完成运动模式的切换。首先,设计了机器人的结构,包括滚动部分、飞行部分和模式切换部分。基于拉格朗日方法,建立了不同运动模式下的动力学模型,建立了基于欧拉方程的运动学模型。最后,根据机器人的运动模型,设计了飞行模式和地面滚动模式下的姿态控制器,并对控制器进行了仿真对比实验。在实机上进行了测试,实验结果表明,该机器人能够实现自主模式切换,在不同运动模式下运动稳定、姿态可控,在纯地面模式下具有一定的越障能力。在结构、控制方法及控制策略切换方法上对陆空两栖可变形机器人具有一定借鉴作用。

新老区块滚动开发地面系统简化优化技术研究

为实现地面集输系统的简化优化及新老区块产能的有效利用,以老区块改造投资、新区块建设投资和地面系统运行成本为目标函数,以运行成本、扩建费用、改建费用、管道隶属关系、流量、热力和水力等为约束条件,将站场降级方案、站场减并方案、站场扩建方案等为决策变量,采用改进粒子群算法进行迭代计算和优化,并进行了实例分析。结果表明,旧区块改造后可实现部分站点“关、停、并、转”,新区块可充分利用老区块的剩余产能实现开发;老区块的电力费用和燃料费用有所降低,年运行费用从1.1561亿元降至0.7562亿元,降幅34.59%,新区块新建联合站数量由3个降至1个,投资费用大幅降低,经济效益显著。

Genetic programming for predictions of effectiveness of rolling dynamic compaction with dynamic cone penetrometer test results

Rolling dynamic compaction (RDC),which employs non-circular module towed behind a tractor,is an innovative soil compaction method that has proven to be successful in many ground improvement applications.RDC involves repeatedly delivering high-energy impact blows onto the ground surface,which improves soil density and thus soil strength and stiffness.However,there exists a lack of methods to predict the effectiveness of RDC in different ground conditions,which has become a major obstacle to its adoption.For this,in this context,a prediction model is developed based on linear genetic programming (LGP),which is one of the common approaches in application of artificial intelligence for nonlinear forecasting.The model is based on in situ density-related data in terms of dynamic cone penetrometer (DCP) results obtained from several projects that have employed the 4-sided,8-t impact roller (BH-1300).It is shown that the model is accurate and reliable over a range of soil types.Furthermore,a series of parametric studies confirms its robustness in generalizing data.In addition,the results of the comparative study indicate that the optimal LGP model has a better predictive performance than the existing artificial neural network (ANN) model developed earlier by the authors.

Application of artificial neural networks for predicting the impact of rolling dynamic compaction using dynamic cone penetrometer test results

Rolling dynamic compaction(RDC),which involves the towing of a noncircular module,is now widespread and accepted among many other soil compaction methods.However,to date,there is no accurate method for reliable prediction of the densification of soil and the extent of ground improvement by means of RDC.This study presents the application of artificial neural networks(ANNs) for a priori prediction of the effectiveness of RDC.The models are trained with in situ dynamic cone penetration(DCP) test data obtained from previous civil projects associated with the 4-sided impact roller.The predictions from the ANN models are in good agreement with the measured field data,as indicated by the model correlation coefficient of approximately 0.8.It is concluded that the ANN models developed in this study can be successfully employed to provide more accurate prediction of the performance of the RDC on a range of soil types.

高水位软土公路路基土石方填筑施工技术研究

由于土石方填筑施工缺乏与实际工况的结合,导致存在高水位软土公路填筑路基沉降值超标的情况,为此,文中对高水位软土公路路基土石方填筑施工技术进行研究。收集高水位软土公路路基各土层的厚度、力学参数(压缩模量、抗剪强度等)等基本地质信息,结合水位分布以及高度,确定其对地基沉降情况的影响,计算高水位软土公路路基沉降状态。在土石方填筑施工阶段,结合计算结果,针对不同土层的具体情况,从填筑松铺厚度、填料粒径、碾压速度、碾压次数,以及特殊工况的施工基础进行针对性设计。应用路基填筑技术后,60 d的最大沉降值仅为0.66 mm,在沉降值允许范围(≤1.0 mm)内,且在50 d后,沉降逐渐收敛,10 d内,沉降值变化幅度仅为0.03 mm。

侧倾工况下子午线轮胎接地区域非对称特性影响因素研究

车辆侧倾时轮胎接地特性呈现的非对称性对车辆燃油经济性、轮胎磨损以及轮胎动力学特性都有重要影响。考虑到接地特性高度依赖轮胎接地时印迹的形状和印迹上压力的准确分布,而目前计算轮胎侧倾时接地印迹上压力值的计算模型尚欠精确,以205/55 R16型半钢子午线轮胎为研究对象建立三维有限元模型,对影响准确获取轮胎接地非对称特性即压力分布的因素进行研究,构建侧倾工况下轮胎的二维接地压力模型,对压力分布影响因素及影响规律进行研究,为准确获取侧倾工况下轮胎路面间峰值附着系数的轮胎智能化研究提供参考。

轮胎配套的注意要点及关键技术探讨

介绍轮胎配套的注意要点及关键技术。轮胎配套的注意要点包括前端分析、车辆信息分析及产品质量先期策划。90%以上的设计变更应在开发初期完成,以大幅降低费用。在轮胎配套的关键技术方面,重点介绍接地印痕对轮胎的转向、操控性、舒适性、噪声和水漂等性能的影响、低滚动阻力轮胎设计以及实车评价中舒适性的技术要点和解决方案。

基于可逆叠加变换的地滚波压制技术

地滚波是一种常见规则干扰,具有低频、低速、强能量、频散的特征,由于地滚波和有效波在频带、传播方向、速度等方面存在重叠,导致变换域滤波方法很难取得理想的效果。目前,工业界主流的地滚波压制技术是预测+匹配相减,由于近地表复杂的波场传播过程,直接对地滚波进行预测建模通常很困难并且精度有限。本文提出了一种基于可逆叠加变换的地滚波压制新技术,通过叠加算子对CMP域反射波进行建模,构建一个反射波估计的反问题,使用最优化方法求解此反问题,相当于把地震数据向反射波空间投影。由于地滚波和反射波处在不同的空间,通过投影能够得到干净的反射波数据。为了降低地滚波对反演结果的影响,本文进一步引入数据预条件算子减少地滚波的泄露,能够得到更好的噪声压制效果。

一种新型免充气车轮的非线性有限元分析

文中介绍了一种新型免充气车轮的结构与原理,并基于车轮与材料的非线性特性建立了车轮的非线性有限元模型。建模时充分考虑了车轮聚氨酯材料与橡胶材料的超弹性,聚氨酯材料采用Yeoh本构模型,橡胶材料采用Mooney-Rivlin本构模型。分析了下沉量对车轮接地位置1、位置2处的接地性态的影响,具体包括接地印迹、法向应力分布与最大法向应力值。接地位置1、位置2的力学差异是车轮稳态滚动中产生振动的原因,并通过稳态滚动仿真得到了验证。

基于双树复小波域主成分分析的地震面波压制方法

面波是地震勘探中一种主要的规则干扰波,面波压制是地震处理中的重要问题之一.结合双树复小波变换和主成分分析提出了一种面波压制方法.首先,对含面波地震信号进行双树复小波变换,在变换域中分析面波信号与有效信号的分布情况.鉴于低频子带既含较多有效信号又有较强的面波成分,对其进行主成分分析处理.对分解得到的每一尺度高频小波系数中±45°方向作主成分分析处理,±75°方向进行基于分位数的阈值处理,±15°方向保持不变.最后,对处理后的小波系数进行逆变换得到压制面波后的地震信号.仿真实验及对实际资料的处理结果显示,该方法能够有效压制面波,去除随机噪声,较好地保留了有效信号.

三角胶高度对轿车子午线轮胎接地特性的影响

研究三角胶高度对轿车子午线轮胎接地特性、刚性和滚动阻力的影响。结果表明,三角胶高度减小,轮胎的接地面积呈增大趋势,纵向刚性和横向刚性呈降低趋势,变形向胎侧转移,滚动阻力系数有不同程度的减小。

不同摩擦因数胎面胶对轿车子午线轮胎性能的影响

研究不同摩擦因数胎面胶对轿车子午线轮胎的滚动阻力、静态刚性、接地印痕、六分力特性及整车性能的影响。结果表明:使用3种胎面胶的轮胎的滚动阻力接近;随着胎面胶摩擦因数的减小,轮胎的纵向刚性和扭转刚性变化较大,径向刚性和横向刚性变化不大,轮胎的包络刚性随胎面胶硬度的增大而增大;采用较大摩擦因数胎面胶的轮胎的接地面积及矩形比较大,3种方案轮胎其他接地特性参数差异较小;采用较小摩擦因数胎面胶的轮胎的侧偏刚度、回正刚度和纵滑刚度最大,成品轮胎的摩擦因数与胎面胶的摩擦因数呈正相关,但数值差异略大,轮胎的侧向力峰值、回正力矩峰值、纵向力峰值随胎面胶摩擦因数的增大而增大;轮胎干地刹车距离与胎面胶摩擦因数呈负相关,操控稳定性受轮胎侧偏刚度和回正刚度的影响较大,舒适性受胎面胶硬度的影响较大。

基于大数据理论的小电流接地故障推拉策略的研究

小电流接地系统广泛应用于我国35 kV及以下电压等级的配电网络,在中低压等级的配电网络中最常出现的故障为单相接地故障。通过整理小电流接地系统发生单相接地故障时的历史数据库,在大数据视野下发现发生单相接地故障的规律,并对多数据故障样本进行分析比对,得出各个因素对于接地故障的影响程度,从而在系统同一母线元件发生接地时根据数据信息分析出母线上各个出线的故障概率,提高故障推拉精度,缩小停电范围。

绿色建筑技术应用研究——以石家庄长安颐园项目为例

当前,环境问题日益凸显,居住环境也有待改善,发展绿色建筑成为一种必然趋势。本文简述了绿色建筑的含义及其设计理念,着重介绍了地源热泵系统、天棚辐射温控系统、全置换新风系统、外遮阳卷帘系统等绿色建筑技术在石家庄三星级绿色建筑设计项目——长安颐园中的实际应用,以期为相关项目设计提供借鉴参考。