数字抽取滤波器的DSP优化设计     

谭耀银  廖成旺  邓涛  赵凤花  丁炜  陈卫明 《大地测量与地球动力学》2007,27(Z1):87-90

为了降低地震数据采集系统的成本和功耗，采用数字信号处理器（DSP）实现∑-△模数转换器中的数字抽取滤波器算法。通过采取查表法、倒序循环遍历法以及模拟循环寻址法等优化方法，以较低工作频率实现了四通道四级抽取滤波运算，达到了系统设计的要求。  相似文献   

Large-eddy simulation of the turbulent near wake behind a circular cylinder: Reynolds number effect     

《Applied Ocean Research》2015

The purpose of the present work is <!–<query>The highlights are in an incorrect format. Hence they have been deleted. Please refer the online instructions: http://www.elsevier.com/highlights and provide 3-5 bullet points.</query>–>to study the effect of the Reynolds number on the near-wake structure and separating shear layers behind a circular cylinder. Three-dimensional unsteady large-eddy simulation is carried out and two different subgrid scale models are applied in order to evaluate the turbulent wake reasonably. The Reynolds number based on the free-stream velocity and the cylinder diameter is ranging from Re = 5500–41,300, corresponding to the full development of the shear-layer instability in the intermediate subcritical flow regime. For a complete validation of this numerical study, hydrodynamic bulk coefficients are computed and compared to experimental measurements and numerical studies in the literature. Special focus is made on the variations of both the large-scale near-wake structure and the small-scale shear-layer instability with increasing Reynolds numbers. The present numerical study clearly shows the broadband nature of the shear-layer instability as well as the dependence of the shear-layer frequency especially on the high Reynolds numbers.  相似文献   

弧形防波堤波浪力试验研究     

赵利平  朱亚州  谢奥运  邹俊飞 《海洋工程》2015,33(5):35-42

在圆筒形防波堤和V形防波堤的基础上,结合离岸堤后形成V形和半圆形连续出现的韵律海岸的地貌平面形态特点,提出一种前墙为连续的半圆筒形防波堤形式。通过在波浪水槽内进行规则波物理模型试验,探究这一新型防波堤的波压力分布规律及波高、周期、水深等因素对波压力的影响。将试验结果与海港水文公式和合田良实公式计算的理论值对比分析,给出了以合田良实公式的折减系数来拟合新型弧形防波堤波浪总水平力的计算公式。结果表明:新型弧形防波堤上的波压力随波高、周期的增大而增大,其水平波浪总力比同等尺度直墙少10%左右。  相似文献   

平面四参数法坐标转换在圆形基坑变形监测中的应用     

刘永辉  黄立 《测绘与空间地理信息》2021,44(1):217-221

由于基坑工程的监测工作往往会受到开挖深度、设计形状等各方面因素的影响和制约,导致监测方法和手段也不能一成不变。基于虚拟断面法仅适用于比较规则的多边形基坑,本文结合珠海市横琴新区基坑工程实例,提出使用平面四参数坐标转换法在圆形基坑中对基坑立柱水平位移计算的应用。结果表明:使用平面四参数坐标转换法计算基坑水平位移时,既不受基坑形状的影响,也能更直观地反映出基坑水平位移的变形量。  相似文献   

河南熊耳山北部上观环形构造及其找矿意义     

赵留升  常云真  徐文超 《世界地质(英文版)》2014,(3)

河南省西部的熊耳山地区是重要的金成矿集中区,区内环形-线性构造与成矿存在耦合关系。本研究中对最新高分SPOT-5图像和Aster的遥感地质解译发现,熊耳山北部上观周围区域存在多个环形构造,主要发育于太华群古老变质岩和熊耳群火山岩中,南部附近为中生代花山岩体。环形构造集中分布,大环套小环、线性和环形构造交切。影像蚀变信息提取研究发现,环形构造周围及其内部发育较好的铁染异常和羟基异常,具有良好的找矿前景。附近和周围已知的金矿床和金矿点零星分布,但其遥感图像与熊耳山其他类似环形构造发育地区相比,影像特征更为典型,且成矿条件似更为优越,有可能成为熊耳山地区又一个金银成矿集中区。  相似文献   

Study on deformation law of circular foundation under combined loading     

ZHANG Qiyi  and SHI Hongda 《中国海洋大学学报(英文版)》2014,13(1):51-56

The foundations of some ocean engineering structures are built to withstand not only the vertical gravity load V, but also the horizontal load H induced by sea waves and current. The horizontal load includes the concentrated force load, the moment load M, and the torque load T termed also as combined loading. It is of academic and engineering significance to study the deformation law of submarine seabed due to combined loading. On the basis of the three-dimensional elastic mechanics solution of circular foundation, numerical methods are used to analyze the deformation law of submarine soil under circular foundation with six degrees of freedom. The finite element analysis results give the elastic deformation law of soil in three dimensional spaces, modify the theoretical elasticity solution, and presents nonlinear soil deformation mechanism under the circular foundation with six degrees of freedom.  相似文献   

CFD-based numerical analysis of a variable cross-section cylinder     

Jinlong Duan  Weiping Huang 《中国海洋大学学报(英文版)》2014,13(4):584-588

Using ANSYS-CFX, a general purpose fluid dynamics program, the vortex-induced vibration (VIV) of a variable cross-section cylinder is simulated under uniform current with high Reynolds numbers. Large eddy simulation (LES) is conducted for studying the fluid-structure interaction. The vortex shedding in the wake, the motion trajectories of a cylinder, the variation of drag and lift forces on the cylinder are analyzed. The results show that the vortices of variable cross-section cylinder are chaotic and are varying along the cylinder. In places where cross-sections are changing significantly, the vortices are more irregular. The motion trail of the cylinder is almost the same but irregular. The drag and lift coefficients of the cylinder are varying with the changes of diameters.  相似文献   

深部开采圆形巷道围岩破损区与支护压力的确定     

李铀  袁亮  刘冠学  金学玉  薛俊华  余国锋  彭意  张明 《岩土力学》2014,35(1):226-231

应用经典塑性力学理论确定的圆形巷道围岩弹塑性应力场存在一些问题,这影响深部圆形巷道的稳定性评价及支护设计的合理性。应用塑性力学求解新体系确定的圆形巷道围岩弹塑性应力场准确解,进行了各向同性均质地层中圆形巷道破损区、地层残余强度与支护压力关系方面的研究,取得了如下成果:(1)破损区随开采深度的增加而增大,它们基本呈线性关系。(2)建立了支护压力与巷道埋深、围岩强度、围岩破坏后残余强度、围岩泊松比和重度之间的关系。研究成果可为支护设计提供重要参考。  相似文献   

On the hydraulic intake shape factor for a circular opening located at an impervious boundary: Influence of inclined stratification     

A. P. S. Selvadurai 《国际地质力学数值与分析法杂志》2011,35(6):639-651

In this paper, we develop an exact closed form solution for a circular entry point located at the interface between an impermeable material and a stratified porous medium, where the principal plane of hydraulic isotropy is inclined to the interface. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Second-species solutions in the circular and elliptic restricted three-body problem     

Gerard Gomez  Merce Olle 《Celestial Mechanics and Dynamical Astronomy》1991,52(2):147-166

An analytical proof of the existence of some kinds of periodic orbits of second species of Poincaré, both in the Circular and Elliptic Restricted three-body problem, is given for small values of the mass parameter. The proof uses the asymptotic approximations for the solutions and the matching theory developed by Breakwell and Perko. In the paper their results are extended to the Elliptic problem and applied to prove the existence of second-species solutions generated by rectilinear ellipses in the Circular problem and nearly-rectilinear ones in the Elliptic case.  相似文献