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利用Visual Basic 6.0编程和mtimer定时进程控制技术，建立了《气象报文自动处理分发系统》。县（区）局测报员应用该系统的县局部分，能够实现报文编辑、转换、发送；市台预报员应用该系统的市局部分，可以实现报文收集、整理、打包传输。系统在一年多的实际业务应用中，简化了工作程序，实用性强，初步实现了气象信息传输的自动化。 相似文献
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近年来,探地雷达(GPR)凭借其快速、高效、无破损等特点,已经广泛应用于浅地层目标探测中.数值模拟是研究探地雷达电磁波在地下结构中传播规律的有效手段.辛算法是一种保持Hamilton系统总能量不变的时域数值计算方法.本文提出了基于一阶显式辛分块龙格库塔方法的探地雷达数值模拟方法.通过对比本文算法与时域有限差分方法计算结果可知,在同等计算精度下,本文算法可以节省25%的计算时间.并基于本文算法对两个复杂GPR模型进行正演模拟,得到模拟GPR探测wiggle图,这有助于更好的理解和分析实测雷达数据. 相似文献
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本文介绍了用高性能集成电路研制的高稳定性的微功耗遥测地震发讯设备,提供了该设备的设计要求,主要单元电路的设计方法,整机的主要技术指标及其主要参数的设计计算。 相似文献
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高阶双渐近时域透射边界能够同时模拟行波和快衰波的传播,并且能够在全频范围内迅速逼近准确解,具有优良的收敛性能和计算效率.本文将动水压力波高阶双渐近透射边界直接嵌入到近场有限元方程中,建立了大坝-库水动力相互作用的直接耦合分析模型.该模型的整体控制方程保留了近场有限元方程系数矩阵对称稀疏的优势,可以方便地利用现有的通用有限元求解器求解.基于有限元开源软件框架体系OpenSees（Open System for Earthquake Engineering Simulation）,编程实现了直接耦合分析模型,并将其应用于二维重力坝、三维拱坝与库水动力相互作用分析.数值算例表明,该直接耦合分析模型具有很高的精度和计算效率. 相似文献
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On the basis of previous study of the 1679 Sanhe-Pinggu(M8.0) earthquake,the biggest event in history ever recorded in Beijing and its adjacent area,we made a 3-D strong ground motion simulation utilizing the staggered-grid finite differences method to study the distributions of peak ground velocity with different earthquake source models in the Beijing region.In the paper,earthquake source models and a transmission medium velocity model are established and the corresponding parameters are given in accordance to the results from a related previous study.Then,using a three-dimensional finite difference computing program of near-fault strong ground motion developed by Graves,the peak ground velocity caused by a destructive earthquake in the Beijing area is simulated.In our computation model,the earthquake source is 3km in depth,and a total number of 21,679 observation points on the ground surface are figured out.The transmission medium velocity model is composed of four stratums which are the Quaternary deposit,the upper crust,the upper part of the middle crust and the lower part of the middle crust.With the minimum grid spacing of 0.15km,a total of 2.28×106 grids are generated.Using a time step of 0.02 seconds we calculated the peak ground velocity for a duration of 8 seconds.After the analysis of the simulation results,we observed some basic characteristics of near-fault strong ground motion such as the concentration effect of near-fault peak ground velocity,rupture directivity effect,hanging wall effect,and basin effect.The results from our simulation and analysis suggest that the source and transmitting medium parameters in our model are suitable and the finite difference method is applicable to estimate the distribution of strong ground motion in the study region. 相似文献
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Local transmitting boundaries for transient elastic analysis 总被引：1，自引：0，他引：1
The aim of this paper is to investigate and develop alternative methods of analyzing problems in dynamic soil–structure-interaction (SSI). The interaction means that the amplitude of structural response is effected by additional energy dissipation through radiation and material damping in the soil. The surrounding soft soil behaves as a natural damper for a massive and stiff structure supported or embedded in it. The main focus is the major difficulty posed by such an analysis — the phenomena of waves that radiate outward from the excited structures towards infinity. In numerical calculations only a finite region of the foundation medium is analyzed and something is done to prevent the outgoing radiation waves from reflecting at the boundary region.Development of a simple and efficient finite element (FE) procedure for the solution directly in the time domain of transient SSI problems is the main concern. The central feature of the procedure is local absorbing boundaries used to render the computational domain finite. These boundaries are local in both time and space and are completely defined by a pair of symmetric stiffness and damping matrices. As the effort for implementing them is the same as for the impedance boundary condition (BC) considering the angle of incidence, standard assembly procedure can be used. Due to the local nature they also preserve the overall structure of the global equations of motion. Even though the focus is in the time domain the same equations of motions can be used to determine the solution under time-harmonic excitation directly in the frequency domain. Explicit formulae for the element matrices are included in the paper and numerical examples for transient radiation model problems to illustrate the validity and accuracy of the new procedures, are given. 相似文献
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A quasi-3D method for the analysis of single piles and pile groups is presented. The method includes an equivalent linear constitutive model for nonlinear analysis, an 8-node pile element that simulates the effects of pile volume and energy transmitting boundaries which are especially important for the analysis of high frequency loading of machine foundations. The quasi-3D formulation and equivalent linear model result in orders of magnitude decreases in computational time. The accuracy and reliability of the approximate approach was validated by comparing results with 3D analytical results from MIT and by data from field tests on single piles and pile groups from Taiwan. The computed results compared very favorably with the analytical and field test data. 相似文献
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Transmitting boundary for water-saturated transversely isotropic strata based on the u–U formulation
A new transmitting boundary in a cylindrical coordinate system has been developed for modeling the elastic waves radiating out to an infinite boundary in water-saturated transversely isotropic soil strata over a rigid bedrock. The saturated soil strata are assumed to consist of a porous material and modeled as a transversely isotropic two-phase medium, based on the u−U formulation. The newly developed transmitting boundary is combined with the finite-elements model of the near-field region, using the same u−U formulation, and applied to the study of the dynamics of a rigid circular foundation in porous isotropic or transversely isotropic layered strata, either fully or partly saturated with water. The verification and application examples give valuable insights into new and interesting aspects of the dynamic behavior of rigid circular foundations in fully or partly saturated two-phase ground in terms of permeability, transverse anisotropy, and ground-water table level. 相似文献
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The energy transmitting boundary used in programs such as FLUSH and ALUSH is a very accurate and useful technique for the earthquake response analysis of soil–structure interaction systems. However, it is applicable only to linear analyses or equivalent linear analyses, because it can be calculated only in the frequency domain. The author has proposed methods for transforming frequency-dependent impedance into the time domain. In this paper, an earthquake response analysis method for a soil–structure interaction system, using the energy transmitting boundary in the time domain, is proposed. First, the transform of the transmitting boundary matrices to the time domain using the methods proposed by the author is studied. Then, linear and nonlinear time history earthquake response analyses using the boundary are performed. Through these studies, the validity and efficiency of the proposed methods are confirmed. 相似文献