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频响函数二次正交法在Davenport风速谱下结构系列响应简明封闭解的应用研究 被引量:8
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作者 葛新广 张梦丹 +1 位作者 龚景海 李创第 《振动与冲击》 EI CSCD 北大核心 2021年第21期207-214,共8页
针对Davenport风速谱激励下结构响应表达式复杂的问题,提出了结构频响函数二次正交法,并首次给出随机风振系列响应(绝对位移和层间位移)的方差和谱矩的简明封闭解。综合运用复模态法和虚拟激励法将结构的系列响应的频响函数二次正交化,... 针对Davenport风速谱激励下结构响应表达式复杂的问题,提出了结构频响函数二次正交法,并首次给出随机风振系列响应(绝对位移和层间位移)的方差和谱矩的简明封闭解。综合运用复模态法和虚拟激励法将结构的系列响应的频响函数二次正交化,并基于随机振动理论获得了结构系列响应方差、0-2阶谱矩和风振绝对加速度方差的简明封闭解。运用该方法分析一10层建筑结构的风振响应并与虚拟激励法进行对比,研究表明该方法为封闭解法且表达式简洁,并可用于验证虚拟激励法的精度。由于频响函数的二次正交化必须采用复模态法对结构体系进行解耦,故该方法也适用非经典阻尼结构基于Davenport谱的响应分析。 展开更多
关键词 频响函数二次正交法 DAVENPORT谱 系列响应 谱矩 舒适度 简明封闭解
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基于迭代序列响应面的桥梁体系承载力可靠度评估 被引量:9
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作者 李星新 汪正兴 任伟新 《中国铁道科学》 EI CAS CSCD 北大核心 2009年第3期40-44,共5页
运用迭代序列响应面法和非线性有限元法,对桥梁结构承载能力体系进行可靠度评估。对大桥结构进行概率灵敏度分析,获得影响桥梁结构极限承载力的主要结构参数。应用实验设计方法得到输入参数值(桥梁荷载和体系状态),将桥梁极限承载力作... 运用迭代序列响应面法和非线性有限元法,对桥梁结构承载能力体系进行可靠度评估。对大桥结构进行概率灵敏度分析,获得影响桥梁结构极限承载力的主要结构参数。应用实验设计方法得到输入参数值(桥梁荷载和体系状态),将桥梁极限承载力作为响应面的输出参数,按照迭代序列响应面法得到桥梁体系极限承载力的回归方程,再与荷载共同组成桥梁体系承载力的极限状态方程;使用该极限状态方程和改进的一次二阶矩法,计算桥梁体系的失效概率与验算点,利用验算点求得新的展开点进行迭代计算,最终得到桥梁体系承载力的可靠度。应用该方法对九江长江大桥进行体系承载力可靠度评估的结果表明:经2次响应面迭代计算得到的响应面拟合精度达0.61%;九江长江大桥3大拱在中跨满载和边跨满载时的体系承载能力可靠度分别为5.75与5.90,均在正常范围内。 展开更多
关键词 公铁两用桥 可靠度评估 迭代系列响应面法 非线性有限元 极限承载力
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Influence of Random Track Irregularities on Dynamic Response of Bridge/Track Structure/High-Speed Train Systems
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作者 Marian Klasztomy Monika Podwoma 《Journal of Civil Engineering and Architecture》 2014年第10期1335-1352,共18页
Random vertical track irregularities are one of essential vibration sources in bridge, track structure and high-speed train systems. The common model of such irregularities is a stationary and ergodic Gaussian process... Random vertical track irregularities are one of essential vibration sources in bridge, track structure and high-speed train systems. The common model of such irregularities is a stationary and ergodic Gaussian process. The study presents the results of numerical dynamic analysis of advanced virtual models of composite BTT (bridge/ballasted track structure/high-speed train) systems. The analysis has been conducted for a series of types of single-span simply-supported railway composite (steel-concrete) bridges, with a symmetric platform, located on lines with ballasted track structure adapted for high-speed trains. The bridges are designed according to Polish bridge standards. A new methodology of numerical modeling and simulation of dynamic processes in BTT systems has been applied. The methodology takes into consideration viscoelastic suspensions of rail-vehicles, nonlinear Hertz wheel-rail contact stiffness and one-side wheel-rail contact, physically nonlinear elastic-damping properties of the track structure, random vertical track irregularities, approach slabs and other features. Computer algorithms of FE (finite element) modeling and simulation were programmed in Delphi. Both static and dynamic numerical investigations of the bridges forming the series of types have been carried out. It has been proved that in the case of common structural solutions of bridges and ballasted track structures, it is necessary to put certain limitations on operating speeds, macadam ballast and vertical track roughness. 展开更多
关键词 Steel-concrete composite bridge ballasted track structure high-speed passenger train random vertical track irregularities numerical analysis.
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Smoothing Non-Stationary Time Series Using the Discrete Cosine Transform
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作者 THOMAKOS Dimitrios 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2016年第2期382-404,共23页
This paper considers the problem of smoothing a non-stationary time series(having either deterministic and/or stochastic trends) using the discrete cosine transform(DCT).The DCT is a powerful tool which has found frui... This paper considers the problem of smoothing a non-stationary time series(having either deterministic and/or stochastic trends) using the discrete cosine transform(DCT).The DCT is a powerful tool which has found fruitful applications in filtering and smoothing as it can closely approximate the optimal Karhunen-Loeve transform(KLT).In fact,it is known that it almost corresponds to the KLT for first-order autoregressive processes with a root close to unity:This is the case with most economic and financial time series.A number of new results are derived in the paper:(a) The explicit form of the linear smoother based on the DCT,which is found to have time-varying weights and that uses all observations;(b) the extrapolation of the DCT-smoothed series;(c) the form of the average frequency response function,which is shown to approximate the frequency response of the ideal low pass filter;(d) the asymptotic distribution of the DCT coefficients under the assumptions of deterministic or stochastic trends;(e) two news method for selecting an appropriate degree of smoothing,in general and under the assumptions in(d).These findings are applied and illustrated using several real world economic and financial time series.The results indicate that the DCT-based smoother that is proposed can find many useful applications in economic and financial time series. 展开更多
关键词 Discrete cosine transform non-stationary time series order selection singular spectrumanalysis SMOOTHING trend extraction unit root.
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