A model for gas pressure in layered landfills with horizontal gas collection systems     

《Computers and Geotechnics》2015

The recovery and emission of landfill gas (LFG) is an important topic in landfill management. To produce an effective engineering design for an LFG collection system, designers must understand the migration of gas from the waste body to horizontal extraction wells. This paper develops a two-dimensional analytical solution to enable the study of the gas pressure distribution, well pressure and recovery efficiency in layered landfills with horizontal wells. A horizontal layered structure is used to accommodate the non-homogeneity of various municipal solid waste (MSW) aspects with respect to depth, including gas generation, permeability and temperature. The governing equations, subject to boundary and continuity conditions, are solved by using separation of variables and double finite integral transforms. The solution was verified against another analytical solution and a numerical simulation. Subsequently, a sensitivity analysis of single-well model parameters is performed to optimize a double-well system. The results show that a landfill with horizontal collection systems cannot be assumed to be one dimensional with increasing well spacing. Additionally, both the operational vacuum and maximum gas pressure can be reduced through the design of a double- or multiple-well system. Therefore, the proposed solution can be used for the verification of more complex models and the preliminary design of a horizontal well system.  相似文献   

利用有限正弦和有限余弦变换模拟地震波场:声波方程   总被引：4，自引：1，他引：3  

孙建国  王雪秋 《吉林大学学报(地球科学版)》2006,36(1):108-112

研究了一种利用有限正弦和有限余弦变换解变密度声波方程的方法,它的基本思想有下列4点：(1)对声波方程两端进行关于一个或多个变量的有限正弦或有限余弦变换;（2）将待求波场的Fourier正弦或余弦级数表达式代入到经过变换后的波动方程之中,进而得到级数表达系数所满足的微分方程式;（3）分别对时间和未作变换的空间导数进行有限差分或其它形式的近似,得到变换系数所满足的离散（矩阵）方程;（4）将通过解离散（矩阵）方程而得到的变换系数代入到相应的反演公式中去,用求和的方式得到待求波场的数值解。与其它方法相比,利用有限正弦和有限余弦的优点在于可以无限制地扩展变换方向的计算区间和可以处理任意变化的速度和密度结构而不明显地增加计算量。  相似文献   

Modelling evapotranspiration using discrete wavelet transform and neural networks   总被引：2，自引：0，他引：2  

Turgay Partal 《水文研究》2009,23(25):3545-3555

This study combines wavelet transforms and feed‐forward neural network methods for reference evapotranspiration estimation. The climatic data (air temperature, solar radiation, wind speed, relative humidity) from two stations in the United States was evaluated for estimating models. For wavelet and neural network (WNN) model, the input data was decomposed into wavelet sub‐time series by wavelet transformation. Later, the new series (reconstructed series) are produced by adding the available wavelet components and these reconstructed series are used as the input of the WNN model. This phase is pre‐processing of raw data and the main different of the WNN model. The performance of the WNN model was compared with classical neural networks approach [artificial neural network (ANN)], multi‐linear regression and Hargreaves empirical method. This study shows that the wavelet transforms and neural network methods could be applied successfully for evapotranspiration modelling from climatic data. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

结合空间辅助面特征的区域自动配准     

王瑞瑞  王晋年  尤红建  马建文 《遥感学报》2010,14(3):454-463

提出了一种新的基于空间辅助面特征的主被动遥感影像区域自动配准方法,该方法借鉴了全局区域配准高精度与局部区域配准低复杂度的算法特征,采用正、反函数变换法提取具有相同角度和尺度的空间特征,并采用归一化互相关系数法定义灰度相似性,通过构建空间辅助面,将空间特征和灰度相似性有效地结合起来,共同用于影像的自动配准。文中选取了SPOT与ASTER影像、ASAR和ASTER影像两组数据进行实验,并提取基准影像和配准后待配准影像的不同部位相间拼接形成结果图,从中可以看出各种地物在拼接处表现自然平滑。实验结果证明,该方法简单易行,且配准精度较高。  相似文献   

Seismic performance of buildings with structural and foundation rocking in centrifuge testing          下载免费PDF全文

Iason Pelekis  Gopal S. P. Madabhushi  Matthew J. DeJong 《地震工程与结构动力学》2018,47(12):2390-2409

Rocking motion, established in either the superstructure in the form of a 2‐point stepping mechanism (structural rocking) or resulting from rotational motion of the foundation on the soil (foundation rocking), is considered an effective, low‐cost base isolation technique. This paper unifies for the first time the 2 types of rocking motion under a common experimental campaign, so that on the one hand, structural rocking can be examined under the influence of soil and on the other, foundation rocking can be examined under the influence of a linear elastic superstructure. Two building models, designed to rock above or below their foundation level so that they can reproduce structural and foundation rocking respectively, were tested side by side in a centrifuge. The models were placed on a dry sandbed and subjected to a sequence of earthquake motions. The range of rocking amplitude that is required for base isolation was quantified. Overall, it is shown that the relative density of sand does not influence structural rocking, while for foundation rocking, the change from dense to loose sand can affect the time‐frequency response significantly and lead to a more predictable behaviour.  相似文献   

Application of synchrosqueezed wavelet transforms to estimate the reservoir fluid mobility          下载免费PDF全文

Ya‐Juan Xue  Jun‐Xing Cao  Gu‐Lan Zhang  Guang‐Hui Cheng  Hui Chen 《Geophysical Prospecting》2018,66(7):1358-1371

This paper presents a new methodology for estimating reservoir fluid mobility using synchrosqueezed wavelet transforms. Synchrosqueezed wavelet transforms, which adopts a reassignment method, can improve the temporal and spatial resolutions of conventional time‐frequency transforms. The synchrosqueezed wavelet transforms‐based fluid mobility estimation requires the favourable selection of sensitive low‐frequency segment and more accurate estimation of the change rate of the low frequency segment in the spectrum. The least‐squares fitting method is employed in the synchrosqueezed wavelet transforms‐based fluid mobility estimation for improving the precision of the estimation of change rate of the low‐frequency segment in the spectrum. We validate our approach with a model test. Two field examples are used to illustrate that the fluid mobility estimation using the synchrosqueezed wavelet transforms‐based method gives a better reflection of fluid storage space and monitors hydrocarbon‐saturated reservoirs well.  相似文献   

强夯时地基土的应力场分布特征及应用   总被引：19，自引：6，他引：13  

孔令伟  袁建新 《岩土力学》1999,20(3):13-19,23

在前期研究工作的基础上,利用积分变换技术和传递矩阵法对强夯时地基土的应力场分布特征进行了数值模拟,并和前人的数值分析与室内外试验结果进行了对比分析,结果表明：所得的动应力衰减规律与实测结果较为吻合。在动荷载作用下,地基土动应力衰减率比强夯冲击荷载作用下的衰减率快,强夯冲击荷载作用下的最大动应力等值线图可作为估算强夯的有效加固深度和加固范围时参考。  相似文献   

Reflection–transmission matrix method for the consolidation of a multilayered saturated soil          下载免费PDF全文

Jian‐Fei Lu  Rong‐Feng Shen  Meng‐Qin Shi 《国际地质力学数值与分析法杂志》2016,40(11):1594-1622

The consolidation of the layered saturated soil is an important issue in civil engineering and has been investigated extensively during the past decades. In this study, based on the Biot's theory, the reflection–transmission matrix (RTM) method for treating the layered saturated soil under axisymmetric consolidation is developed. To decouple the governing equations of the Biot's theory, the McNamee displacement functions are introduced, and the general solution for the saturated soil is obtained using the Laplace and Hankel transforms. In order to develop the RTM method for the layered saturated soil, based on the obtained general solution, the static wave vector corresponding to the state vector of the saturated soil and the transform matrix relating the aforementioned two vectors are defined. Also, the transfer matrices corresponding to the two vectors are introduced, and the representations of the RTMs for the static wave vector of the saturated soil are presented. As the state vector, static wave vector, and the transform matrix relating the two vectors are all defined in the global coordinate system, the RTMs obtained in this study thus have a reasonable physical meaning. By using the RTMs for the layered saturated soil, the solutions for the layered saturated soil subjected to external sources are derived. Comparison of results due to the proposed RTM method with some existing results and results due to the transfer matrix method validates the developed RTM method. Some numerical results are obtained based on the proposed RTM method for the layered saturated soil. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

频率-波数域频散曲线提取方法及程序设计     

李杰  陈宣华  张交东  周琦  刘刚  刘志强  徐燕  李冰  杨婧 《物探与化探》2011,35(5):684-688

主要研究了地震瞬态瑞利波频率一波数域频散曲线的提取,以二维傅氏变换,半波长理论等作为理论基础.使用Delphi7.0将其程序化,通过工程应用验证了本方法及程序.结论证明f-k方法克服了-维数字处理技术存在的不足,充分利用了多道瑞利波数据记录信息.  相似文献   

The logratio approach to the classification of modern sediments and sedimentary environments in northern South China Sea     

Di Zhou  Hanzong Chen  Youlang Lou 《Mathematical Geology》1991,23(2):157-165

Grain-size measurements are a type of compositional data and thus subject to closure effects and nonnormality. The logratio transform of Aitchison successfully resolves these problems in compositional data analysis. An application to modern sediment data from the northern part of the South China Sea demonstrates that logratio principal components analysis provides a clear separation of data which cannot be obtained by ordinary principal components analysis, and that cluster analysis using logratio principal components gives a much better classification of sediments than does cluster analysis using raw data. The delineation of sedimentary environments on the basis of a logratio classification of sediment samples provides a better understanding of hydrodynamic conditions on the shelf.  相似文献