期刊文献+
共找到17篇文章
< 1 >
每页显示 20 50 100
基于连续小波变换的时变结构瞬时模态参数识别 被引量:6
1
作者 赵丽洁 刘瑾 +1 位作者 杜永峰 李万润 《地震工程学报》 CSCD 北大核心 2019年第3期601-606,共6页
为体现时变结构动力特性,定义随机冲击荷载作为时变结构输入激励,提出了基于连续小波变换的时变结构瞬时模态参数识别方法。在短时时变假定条件下,建立基于模局部极大值的连续小波变换时变参数识别原理,利用结构的输出响应进行瞬时模态... 为体现时变结构动力特性,定义随机冲击荷载作为时变结构输入激励,提出了基于连续小波变换的时变结构瞬时模态参数识别方法。在短时时变假定条件下,建立基于模局部极大值的连续小波变换时变参数识别原理,利用结构的输出响应进行瞬时模态参数识别,采用三自由度的时变结构体系进行数值模拟,该方法能够准确识别时变结构的瞬时模态参数值。通过设计具有质量参数可变的两层钢框架模型进行测试,验证了方法的有效性与可行性。 展开更多
关键词 连续小波变换 时变结构 参数识别 瞬时模态参数 随机冲击激励
下载PDF
基于线调频自适应分解的时变系统瞬时模态参数识别 被引量:3
2
作者 张杰 史治宇 赵宗爽 《振动与冲击》 EI CSCD 北大核心 2020年第22期103-109,118,共8页
提出了基于线调频小波时频分解的时变系统瞬时模态参数识别方法。该方法应用线调频小波对时变系统加速度响应信号进行时频分析,通过小波脊方法提取瞬时频率,再应用卡尔曼滤波进行自适应分解获得各阶响应的幅值信息;为了更精确地识别时... 提出了基于线调频小波时频分解的时变系统瞬时模态参数识别方法。该方法应用线调频小波对时变系统加速度响应信号进行时频分析,通过小波脊方法提取瞬时频率,再应用卡尔曼滤波进行自适应分解获得各阶响应的幅值信息;为了更精确地识别时变结构的阻尼比,该研究推导了基于幅值能量法的时变阻尼比识别方法;线调频小波相比传统小波对具有更高的能量聚集性,因此该方法具有更高的瞬时频率提取精度,此外传统的基于幅值的阻尼识别方法易受噪声干扰,能量法在短区间内基于幅值进行整体积分具有较强的抗噪性和更高的识别精度。仿真算例中,构造了一个三自由度时变结构来验证识别方法,通过与传统小波和时域峰值法作对比,验证了方法识别瞬时模态参数的精确性和抗噪性。 展开更多
关键词 线调频小波变换(CT) 时频脊提取 自适应滤波 时变系统 瞬时模态参数识别 能量法
下载PDF
瞬时模态法计算圆板受水下爆炸时的变形 被引量:1
3
作者 谌勇 张军 +1 位作者 华宏星 沈荣瀛 《振动工程学报》 EI CSCD 北大核心 2004年第z2期898-902,共5页
应用瞬时模态法分析了刚塑性圆板受水下爆炸时的变形,用Taylor平板理论计算湿表面的压力,同时用压力标准考虑了空泡的影响.将圆板变形过程分为移动铰环模式和膜变形模式,并通过变形模态的演化,求得最终变形.在移动铰环模式时,根据Lee极... 应用瞬时模态法分析了刚塑性圆板受水下爆炸时的变形,用Taylor平板理论计算湿表面的压力,同时用压力标准考虑了空泡的影响.将圆板变形过程分为移动铰环模式和膜变形模式,并通过变形模态的演化,求得最终变形.在移动铰环模式时,根据Lee极值原理求得任意时刻移动铰的位置,从而得到该时刻的瞬时模态.在膜变形模式时,结构变形退化为定常的余弦变形模式.计算结果同有限元分析结果进行比较表明该方法具有相当高的精度,较好地解决了流固耦合及空泡因素的影响. 展开更多
关键词 圆板 水下爆炸 瞬时模态
下载PDF
基于瞬时频率估计的旋转机械故障信号阶比分析
4
作者 刘颖源 《电子制作》 2014年第5X期59-59,共1页
提出了自相关函数降噪与基于瞬时频率估计的阶比分析相结合的方法。首先应用自相关分析消除信号中的随机噪声成分,再对去噪后信号进行经验模态分解得到信号的固有模态函数,对各个固有模态函数作Hilbert变换,得到信号的瞬时频率,然后根... 提出了自相关函数降噪与基于瞬时频率估计的阶比分析相结合的方法。首先应用自相关分析消除信号中的随机噪声成分,再对去噪后信号进行经验模态分解得到信号的固有模态函数,对各个固有模态函数作Hilbert变换,得到信号的瞬时频率,然后根据参考轴的转速信号对时域振动信号进行等角度重采样,最后对重采样信号进行阶比分析。 展开更多
关键词 故障诊断 旋转机械 经验模态分解瞬时频率估计 阶比分析
下载PDF
玉米收获机调节架动态特性分析 被引量:2
5
作者 吴林峰 吴金妹 +2 位作者 朱汉涛 李国强 张涛 《农机化研究》 北大核心 2009年第5期83-85,88,共4页
利用有限元软件分析软件abaqus对玉米收获机调节架进行了建模,同时对调节架的前4阶固有频率和瞬态模态进行了计算,得到了调节架前4阶频率和相应的振型、结构瞬态时的应力应变规律,指出调节架工作时应避开的频率,为该类玉米收获机结构的... 利用有限元软件分析软件abaqus对玉米收获机调节架进行了建模,同时对调节架的前4阶固有频率和瞬态模态进行了计算,得到了调节架前4阶频率和相应的振型、结构瞬态时的应力应变规律,指出调节架工作时应避开的频率,为该类玉米收获机结构的安全可靠性分析提供了可借鉴的理论依据和有益指导。 展开更多
关键词 玉米收获机调节架 有限元 固有频率 瞬时模态
下载PDF
桥梁高墩地震反应中高阶振型贡献程度的分析 被引量:4
6
作者 卢皓 李建中 《石家庄铁道大学学报(自然科学版)》 2012年第4期7-12,共6页
针对山区典型不同高度桥墩,通过增量动力分析(Incremental Dynamic Analysis-IDA)研究高墩在地震作用下从弹性状态到极限状态的整个反应过程,得到不同塑性程度下墩身的位移分布,并通过对各级地震动输入下墩底曲率达到最大时刻的结构刚... 针对山区典型不同高度桥墩,通过增量动力分析(Incremental Dynamic Analysis-IDA)研究高墩在地震作用下从弹性状态到极限状态的整个反应过程,得到不同塑性程度下墩身的位移分布,并通过对各级地震动输入下墩底曲率达到最大时刻的结构刚度进行瞬时模态分析,探讨了整个非线性过程中瞬时振型、瞬时振型参与系数、瞬时质量参与系数以及各阶瞬时周期对应的延性位移谱值随着墩底曲率增加的变化,揭示了整个非线性过程中高阶振型参与程度的变化,进而对在各级地震动作用下墩底达到曲率最大值时刻的墩身位移分布中的高阶振型贡献程度进行评估。 展开更多
关键词 高墩 IDA 瞬时模态分析 瞬时周期 延性位移谱
下载PDF
硬目标侵彻高冲击加速度下微小电子元的动态响应
7
作者 任宪仁 高修柱 《安徽工业大学学报(自然科学版)》 CAS 2008年第3期294-299,共6页
利用有限元方法对硬目标侵彻高冲击加速度条件下某微小加速度存储测试系统进行了瞬时模态动态分析,分别从固有频率、动态响应及部件强度3个方面对整个结构设计的合理性进行了判断。分析表明,该加速度存储测试系统的固有频率满足使用条件... 利用有限元方法对硬目标侵彻高冲击加速度条件下某微小加速度存储测试系统进行了瞬时模态动态分析,分别从固有频率、动态响应及部件强度3个方面对整个结构设计的合理性进行了判断。分析表明,该加速度存储测试系统的固有频率满足使用条件,动态应力在极限应力范围内满足强度要求,为结构的初步设计提供了理论依据,同时也为类似的工程提供了参考。 展开更多
关键词 瞬时模态 动态响应 有限元分析
下载PDF
浮筏系统隔振优化设计 被引量:4
8
作者 张乐 《中国水运(下半月)》 2014年第2期150-151,共2页
文中基于Abaqus瞬时模态动态分析获得浮筏系统动力响应,对多激励源浮筏建立了隔振性能优化设计数学模型。选取筏架板厚、隔振器刚度、设备布局坐标作为设计变量,考虑设备布局、筏架应力、质量以及工艺性要求等约束,以浮筏基座处的力振... 文中基于Abaqus瞬时模态动态分析获得浮筏系统动力响应,对多激励源浮筏建立了隔振性能优化设计数学模型。选取筏架板厚、隔振器刚度、设备布局坐标作为设计变量,考虑设备布局、筏架应力、质量以及工艺性要求等约束,以浮筏基座处的力振级落差为目标函数,采用Python建立浮筏有限元分析参数化模型,通过Isight平台集成Abaqus,运用遗传算法,给出了浮筏设备隔振性能优化设计最优解。 展开更多
关键词 浮筏 瞬时模态动态分析 遗传算法
下载PDF
Seismic attribute extraction based on HHT and its application in a marine carbonate area 被引量:5
9
作者 黄亚平 耿建华 +4 位作者 钟广法 郭彤楼 蒲勇 丁孔芸 麻纪强 《Applied Geophysics》 SCIE CSCD 2011年第2期125-133,177,共10页
The Hilbert-Huang transform(HHT) is a new analysis method suitable for nonlinear and non-stationary signals.It is very appropriate to seismic signals because they show both non-stationary and nonlinear characteristi... The Hilbert-Huang transform(HHT) is a new analysis method suitable for nonlinear and non-stationary signals.It is very appropriate to seismic signals because they show both non-stationary and nonlinear characteristics.We first introduce the realization of HHT empirical mode decomposition(EMD) and then comparatively analyze three instantaneous frequency algorithms based on intrinsic mode functions(IMF) resulting from EMD,of which one uses the average instantaneous frequency of two sample intervals having higher resolution which can determine that the signal frequency components change with time.The method is used with 3-D poststack migrated seismic data of marine carbonate strata in southern China to effectively extract the three instantaneous attributes.The instantaneous phase attributes of the second intrinsic mode functions(IMF2) better describe the reef facies of the platform margin and the IMF2 instantaneous frequency attribute has better zoning.Combining analysis of the three IMF2 instantaneous seismic attributes and drilling data can identify the distribution of sedimentary facies well. 展开更多
关键词 Hilbert-Huang transform empirical mode decomposition instantaneous frequency seismic attributes
下载PDF
希尔伯特—黄变换时频分析在沉积旋回划分中的应用 被引量:2
10
作者 孙兴刚 赵晓 +1 位作者 刘浩杰 赵翠霞 《油气地质与采收率》 CAS CSCD 北大核心 2012年第6期58-60,65,共4页
希尔伯特—黄变换是基于地震数据对信号进行经验模态分解的新的时频分析方法,其克服了原有时频分析方法因受到分辨率和信号平稳性的限制导致沉积旋回划分精度降低的影响,通过对非平稳信号进行处理得到地震信号不同固有模态分量的瞬时时... 希尔伯特—黄变换是基于地震数据对信号进行经验模态分解的新的时频分析方法,其克服了原有时频分析方法因受到分辨率和信号平稳性的限制导致沉积旋回划分精度降低的影响,通过对非平稳信号进行处理得到地震信号不同固有模态分量的瞬时时频特征,以此为基础,精细刻画地震资料中的时间、频率和能量之间的关系,进而依据不同模态分量的瞬时时频特征划分出不同级次的地层沉积旋回。模型数据与实际地震资料的处理结果表明,地震数据通过希尔伯特—黄变换时频分析能够准确地进行地层沉积旋回划分,实现的过程简单实用且精确度较高,从而为地层的沉积旋回划分和精细对比提供了有效方法和参考依据。 展开更多
关键词 希尔伯特-黄变换时频分析非平稳信号固有模态分量沉积旋回瞬时时频
下载PDF
A Novel Statistical Delay Model Based on the Birnbaum-Saunders Distribution for RLC Interconnects in 90nm Technologies
11
作者 周磊 孙玲玲 蒋立飞 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2008年第7期1313-1317,共5页
For performance optimization such as placement,interconnect synthesis,and routing, an efficient and accurate interconnect delay metric is critical,even in design tools development like design for yield (DFY) and des... For performance optimization such as placement,interconnect synthesis,and routing, an efficient and accurate interconnect delay metric is critical,even in design tools development like design for yield (DFY) and design for manufacture (DFM). In the nanometer regime, the recently proposed delay models for RLC interconnects based on statistical probability density function (PDF)interpretation such as PRIMO,H-gamma,WED and RLD bridge the gap between accuracy and efficiency. However, these models always require table look-up when operating. In this paper, a novel delay model based on the Birnbaum-Saunders distribution (BSD) is presented. BSD can accomplish interconnect delay estimation fast and accurately without table look-up operations. Furthermore, it only needs the first two moments to match. Experimental results in 90nm technology show that BSD is robust, easy to implement,efficient,and accurate. 展开更多
关键词 delay model INTERCONNECT MOMENT probability distribution function
下载PDF
玉米脱粒试验台清选风机线性动力学分析
12
作者 邸志峰 崔中凯 +3 位作者 刘虎 张华 卜令昕 周进 《农机化研究》 北大核心 2017年第5期37-41,共5页
由于设计的玉米脱粒试验台清选风机,在样件试验过程中风机叶片出现严重扭曲变形故障。为实现有效改进,借助有限元分析软件对风机结构开展线性动力学分析。分析结果表明:原风机结构在800~900r/min长时间运行时,自身固有频率与激励频率耦... 由于设计的玉米脱粒试验台清选风机,在样件试验过程中风机叶片出现严重扭曲变形故障。为实现有效改进,借助有限元分析软件对风机结构开展线性动力学分析。分析结果表明:原风机结构在800~900r/min长时间运行时,自身固有频率与激励频率耦合,共振后导致破坏,分析结果与故障现象具有一致性。通过在叶片薄弱位置增设中间支撑,改进后风机轴装配1阶固有频率由62.3Hz提升到116.3Hz,改进后样件在后续试验过程中运行可靠,未出现破坏现象,证明改进措施切实可行,为后续开发高性能样机提供了参考。 展开更多
关键词 清选风机 线性动力学分析 瞬时模态
下载PDF
Three-dimensional transient numerical simulation for intake process in the engine intake port-valve-cylinder system 被引量:4
13
作者 罗马吉 陈国华 马元镐 《Journal of Zhejiang University Science》 EI CSCD 2003年第3期309-316,共8页
This paper presents a KIVA-3 code based numerical model for three-dimensional transient intake flow in the intake port-valve-cylinder system of internal combustion engine using body-fitted technique, which can be used... This paper presents a KIVA-3 code based numerical model for three-dimensional transient intake flow in the intake port-valve-cylinder system of internal combustion engine using body-fitted technique, which can be used in numerical study on internal combustion engine with vertical and inclined valves, and has higher calculation precision. A numerical simulation (on the intake process of a two-valve engine with a semi-sphere combustion chamber and a radial intake port) is provided for analysis of the velocity field and pressure field of different plane at different crank angles. The results revealed the formation of the tumble motion, the evolution of flow field parameters and the variation of tumble ratios as important information for the design of engine in-take system. 展开更多
关键词 Internal combustion engine Intake flow Transient numerical simulation Dynamic grid generation
下载PDF
Stochastic Resonance of Instantaneous-State in Linear Regime of Single-Mode Lasers Driven by Colored Noises
14
作者 ZHANG Liang-Ying CAO Li WU Da-Jin 《Communications in Theoretical Physics》 SCIE CAS CSCD 2006年第1期109-112,共4页
According to a linear equation of the laser intensity of single-mode laser with input signal, we compute the generalized signal-to-noise ratio (GSNR) in the instantaneous-state of the single-mode laser, which is dri... According to a linear equation of the laser intensity of single-mode laser with input signal, we compute the generalized signal-to-noise ratio (GSNR) in the instantaneous-state of the single-mode laser, which is driven by two colored noises and correlated in the form of an e-exponential function. We detect that the stochastic resonance (SR) also occurs on instantaneous state at any time. Furthermore we discuss the GSNR trend to stable state in three different forms when taking different signal frequencies. 展开更多
关键词 colored noise Fourier transform generalized signal-to-noise ratio instantaneous-state stochastic resonance
下载PDF
Theoretical Study and Performance Analysis of an Adsorption Chiller
15
作者 Viorel Popa Liviu Costiuc Mihai Cuzic 《Journal of Energy and Power Engineering》 2012年第10期1570-1575,共6页
The thermodynamic cycle for an adsorption system is presented inp-T diagram. In order to investigate the performance of the adsorption system, a lumped parameter transient model of the chiller is developed, in order t... The thermodynamic cycle for an adsorption system is presented inp-T diagram. In order to investigate the performance of the adsorption system, a lumped parameter transient model of the chiller is developed, in order to predict the behaviors of the adsorption chiller system and find the influence of working conditions on its operation. For the working process of the main components of the system, including adsorber, condenser and evaporator, the coupled unsteady equations were set up for each stage. The model was then solved using stable numerical methods from EES (equation engineering solver), and the performance of the adsorber and condenser/evaporator of the system was analyzed. The condensation, evaporation and adsorber temperature values as well as the adsorption ratio and desorption ratio were obtained as function of operating time. Also, the coefficient of performance was analyzed in function of the heat source temperature and the cooling source temperature. 展开更多
关键词 Adsorbtion chiller coefficient of performance cooling systems numerical simulation.
下载PDF
A two-level method for sparse time-frequency representation of multiscale data Dedicated to Professor LI TaTsien on the Occasion of His 80th Birthday
16
作者 LIU ChunGuang SHI ZuoQiang HOU Thomas Yizhao 《Science China Mathematics》 SCIE CSCD 2017年第10期1733-1752,共20页
Based on the recently developed data-driven time-frequency analysis(Hou and Shi, 2013), we propose a two-level method to look for the sparse time-frequency decomposition of multiscale data. In the two-level method, we... Based on the recently developed data-driven time-frequency analysis(Hou and Shi, 2013), we propose a two-level method to look for the sparse time-frequency decomposition of multiscale data. In the two-level method, we first run a local algorithm to get a good approximation of the instantaneous frequency. We then pass this instantaneous frequency to the global algorithm to get an accurate global intrinsic mode function(IMF)and instantaneous frequency. The two-level method alleviates the difficulty of the mode mixing to some extent.We also present a method to reduce the end effects. 展开更多
关键词 sparse representation time-frequency analysis matching pursuit two-level method end effects
原文传递
Modeling to predict the time evolution of negative bias temperature instability(NBTI) induced single event transient pulse broadening
17
作者 CHEN ShuMing CHEN JianJun +2 位作者 CHI YaQing LIU FanYu HE YiBai 《Science China(Technological Sciences)》 SCIE EI CAS 2012年第4期1101-1106,共6页
An analytical model is proposed to calculate single event transient (SET) pulse width with bulk complementary metal oxide semiconductor (CMOS) technology based on the physics of semiconductor devices. Combining with t... An analytical model is proposed to calculate single event transient (SET) pulse width with bulk complementary metal oxide semiconductor (CMOS) technology based on the physics of semiconductor devices. Combining with the most prevalent negative bias temperature instability (NBTI) degradation model, a novel analytical model is developed to predict the time evolution of the NBTI induced SET broadening in the production, and NBTI experiments and three-dimensional numerical device simulations are used to verify the model. At the same time, an analytical model to predict the time evolution of the NBTI induced SET broadening in the propagation is also proposed, and NBTI experiments and the simulation program with integrated circuit emphasis (SPICE) are used to verify the proposed model. 展开更多
关键词 negative bias temperature instability (NBTI) single event transient (SET) pulse broadening analytical model
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部