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PSD analyzing for complicated shock signal 被引量:1
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作者 郭旻 钞红晓 +1 位作者 张鹏飞 曹馨 《Journal of Measurement Science and Instrumentation》 CAS 2013年第2期155-157,共3页
This paper presents a new idea for an a lyzing the complicated shock signal.Based on this kind of analysis,an equivale nt power spectral density(PSD) chart is drawn for vibration environmental test,which is carried to... This paper presents a new idea for an a lyzing the complicated shock signal.Based on this kind of analysis,an equivale nt power spectral density(PSD) chart is drawn for vibration environmental test,which is carried to test the vehicle loading instrument's vibration behavior.T he environment test is equivalent to the condition under which the vehicle and t he instrument is experiencing a firing period.Exactly speaking,the short time vibration during the firing period is a complicated shock event.The paper point s out the deficiency of the commonly used half sine equivalence for the shock an d vibration environment test and gives the procedure of how to draw the PSD char t through the actual acceleration data. 展开更多
关键词 environment test waveform equivalence complicated shock power spectral densitypsd
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Simulation of pavement roughness based on time domain model 被引量:2
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作者 钮凯健 李昶 《Journal of Southeast University(English Edition)》 EI CAS 2010年第3期475-479,共5页
In order to describe pavement roughness more intuitively and effectively, a method of pavement roughness simulation, i.e., the stochastic sinusoidal wave, is introduced. The method is based on the primary idea that pa... In order to describe pavement roughness more intuitively and effectively, a method of pavement roughness simulation, i.e., the stochastic sinusoidal wave, is introduced. The method is based on the primary idea that pavement roughness is denoted as the sum of numerous sines or cosines with stochastic phases, and uses the discrete spectrum to approach the target stochastic process. It is a discrete numerical method used to simulate pavement roughness. According to a given pavement power spectral density (PSD) coefficient, under the condition that the character of displacement frequency based on the time domain model is in accordance with the given pavement surface spectrum, the pavement roughness is optimized to stochastic equivalent vibrations by computer simulation, and the curves that describe pavement roughness under each grade are obtained. The results show that the stochastic sinusoidal wave is suitable for simulation of measured pavement surface spectra based on the time domain model. The method of the stochastic sinusoidal wave is important to the research on vehicle ride comfort due to its rigorous mathematical derivation, extensive application range and intuitive simulation curve. Finally, a roughness index defined as the nominal roughness index (NRI) is introduced, and it has correlation with the PSD coefficient. 展开更多
关键词 pavement roughness stochastic sinusoidal wave stochastic process power spectral density psd coefficient time domain nominal roughness index (NRI)
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Inhibitory effects of jujuboside A on EEG and hippocampal glutamate in hyperactive rat 被引量:10
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作者 卢英俊 周竣 +2 位作者 张韶岷 张恒义 郑筱祥 《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 SCIE CAS CSCD 2005年第4期265-271,共7页
In this study, the inhibitory effect of jujuboside A (JuA) on a penicillin sodium (Na-PCN) induced hyperactivity model was investigated. Cortical EEG (electroencephalogram) and the concentration of hippocampal Glutama... In this study, the inhibitory effect of jujuboside A (JuA) on a penicillin sodium (Na-PCN) induced hyperactivity model was investigated. Cortical EEG (electroencephalogram) and the concentration of hippocampal Glutamate (Glu) were monitored simultaneously in vivo as indicators of rat’s excitatory state. Power spectral density (PSD) and gravity frequency of PSD were calculated. JuA (0.05 g/L and 0.1 g/L) inhibited the EEG excitation effect caused by Na-PCN by increasing the power of δ1 and δ2 bands (P<0.01 vs model) and lowering the gravity frequency of PSD (P<0.01 vs model). JuA also remarkably reduced the Glu elevation induced by Na-PCN (P<0.05 vs model). Diazepam also depressed Glu concentration and lowered the gravity frequency, but it showed a different EEG pattern in increased β2-activity (P<0.01 vs model). EEG excitation caused by Na-PCN correlated with Glu elevation during the first hour. Neurophysiological inhibitory effects of JuA and diazepam were more persistent than their Glu inhibitoty effects. 展开更多
关键词 Jujuboside A (JuA) DIAZEPAM Glutamate (Glu) Electroencephalogram (EEG) HYPERACTIVITY Penicillin sodium (Na-PCN) power spectral density (psd) Gravity frequency
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Life Prediction Based on Transient Dynamics Analysis of Van Semi-trailer with Air Suspension System 被引量:3
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作者 LI Liang SONG Jian HE Lin ZHANG Mengjun LI Hongzhi 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2011年第3期372-379,共8页
The early fatigue damage in the van-body of the semi-trailer is often caused by the unique mechanical characteristics and the dynamic impact of the loads.The traditional finite element method with static strength anal... The early fatigue damage in the van-body of the semi-trailer is often caused by the unique mechanical characteristics and the dynamic impact of the loads.The traditional finite element method with static strength analysis cannot support the fatigue design of van-body;thus,the dynamics analysis should be adopted for the endurance performance.The accurate dynamics model to describe the transient impacts of all kinds of uneven road and the proper system transfer functions to calculate the load transfer effects from tire to van-body are two critical factors for transient dynamics analysis.In order to evaluate the dynamic performance,the dynamics model of the trailer with the air suspension is brought forward.Then the analysis method of the power spectral density (PSD) is set up to study the transient responses of the road dynamic impacts.The transient responses transferred from axles to van-body are calculated,such as dynamic stress,dynamic RMS acceleration,and dynamic load factors.Based on the above dynamic responses,the fatigue life of van-body is predicted with the finite element analysis (FEA) method.Applying the test parameters of the trailer with air suspension,the simulation system with Matlab/Simulink is constructed to describe the dynamic responses of the impacts of the tested PSD of the vehicle axles,and then the fatigue life is predicted with FEA method.The simulated results show that the vibration level of the van-body with air suspension is reduced and the fatigue life is improved.The real vehicle tests on different roads are carried out,and the test results validate the accuracy of the simulation system.The proposed fatigue life prediction method is effective for the virtual design of auto-body. 展开更多
关键词 van-body air suspension system transient dynamics power spectral density psd life prediction
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民用飞机焊接管路建模及高周疲劳分析 被引量:1
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作者 吴剑飞 张鹏飞 栾涛 《民用飞机设计与研究》 2021年第2期84-88,共5页
焊接结构具有连接性良好、重量轻、易于加工等特点,被广泛应用于民用飞机系统管路的连接。但是焊接结构的不连续性容易引起应力集中效应,从而导致焊接部位产生疲劳破坏。以某型飞机焊接管路接头为研究对象,首先介绍了一般管路焊接结构... 焊接结构具有连接性良好、重量轻、易于加工等特点,被广泛应用于民用飞机系统管路的连接。但是焊接结构的不连续性容易引起应力集中效应,从而导致焊接部位产生疲劳破坏。以某型飞机焊接管路接头为研究对象,首先介绍了一般管路焊接结构的疲劳破坏区域、破坏模式及焊接焊缝要求,之后采用实体网格单元对焊接接头进行了细节有限元建模,并详细说明了为消除应力集中效应需注意的焊缝、焊趾等的有限元建模要求和网格收敛性要求。本文中振动激励载荷环境选用RTCA/DO160中规定的振动环境曲线,利用Abaqus软件中的PSD分析模块对焊接管路进行了应力响应功率谱密度(PSD)分析,最后选取三区间法疲劳损伤模型和Miner线性疲劳累积损伤理论,给出了焊接结构的疲劳寿命分析结果。 展开更多
关键词 焊接 有限元(finite element method 简称FEM) 疲劳 三区间法 功率谱密度(power spectral density 简称psd) MINER
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Contrastive Analysis of General and Special Forced Oscillations of Power Systems 被引量:4
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作者 Yongfei Liu Ping Ju +2 位作者 Jun Chen Yiming Zhang Yiping Yu 《CSEE Journal of Power and Energy Systems》 SCIE 2015年第1期61-68,共8页
With the continuous incorporation of renewable energy and new loads into the electric power grid,random factors that induce general forced oscillations(GFOs)gradually become risks that affect the power system's se... With the continuous incorporation of renewable energy and new loads into the electric power grid,random factors that induce general forced oscillations(GFOs)gradually become risks that affect the power system's security and stability.T his research conducts a comparative analysis of the generation mechanisms of GFOs versus the traditional special forced oscillations(SFOs),specifically,from the perspective of frequency domain.Similarities and differences in en-oscillating conditions,occurrence probabilities,and the influencing factors of GFO and SFO are compared to better understand and recognize the GFO theory and the response characteristics of the power system under random excitations.A series of simulations in the lO-generator,39-bus New England Test System is carried out to verify the analysis. 展开更多
关键词 Forced oscillations modal analysis power spectral density(psd) power system random excitations
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Spectrum analysis of interval process model and its application in uncertain vibration analysis
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作者 LI JinWu JIANG Chao NI BingYu 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2024年第8期2549-2564,共16页
In recent years, the authors have extended the traditional interval method into the time dimension to develop a new mathematical tool called the “interval process model” for quantifying time-varying or dynamic uncer... In recent years, the authors have extended the traditional interval method into the time dimension to develop a new mathematical tool called the “interval process model” for quantifying time-varying or dynamic uncertainties. This model employs upper and lower bounds instead of precise probability distributions to quantify uncertainty in a parameter at any given time point. It is anticipated to complement the conventional stochastic process model in the coming years owing to its relatively low dependence on experimental samples and ease of understanding for engineers. Building on our previous work, this paper proposes a spectrum analysis method to describe the frequency domain characteristics of an interval process, further strengthening the theoretical foundation of the interval process model and enhancing its applicability for complex engineering problems. In this approach, we first define the zero midpoint function interval process and its auto/cross-power spectral density(PSD) functions. We also deduce the relationship between the auto-PSD function and the auto-covariance function of the stationary zero midpoint function interval process. Next, the auto/cross-PSD function matrices of a general interval process are defined, followed by the introduction of the concepts of PSD function matrix and cross-PSD function matrix for interval process vectors. The spectrum analysis method is then applied to random vibration problems, leading to the creation of a spectrum-analysis-based interval vibration analysis method that determines the PSD function for the system displacement response under stationary interval process excitations. Finally, the effectiveness of the formulated spectrum-analysis-based interval vibration analysis approach is verified through two numerical examples. 展开更多
关键词 interval process spectrum analysis power spectral density(psd) time-varying uncertainty uncertain vibration analysis
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Real-time reliability assessment based on acceleration monitoring for bridge 被引量:2
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作者 ZHANG LiYe SUN LiMin SHANG ZhiQiang 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2016年第8期1294-1304,共11页
Bridge health monitoring (BHM) has become increasingly significant in the life-cycle of the structure such as maintenance, repair and rehabilitation. It is necessary to use BHM information efficiently to assess the ... Bridge health monitoring (BHM) has become increasingly significant in the life-cycle of the structure such as maintenance, repair and rehabilitation. It is necessary to use BHM information efficiently to assess the working conditions of the bridge. The main objective of this study is to develop an effective method and establish a framework for the real-time reliability assessment based on BHM acceleration information. The first-passage probability and its further development have been proposed to as- sess the reliability probability. The first-passage probability shows the probability of that a scalar process exceeds a designated threshold during a given time interval. The advantage of the proposed method is the assessment of the real-time reliability probability based on the monitoring information during an assessment reference period. Furthermore, the velocity data and displacement data are calculated from the acceleration monitoring data using the relationships between their power spectral density (PSD) functions. The real-time reliability assessment of Donghai Bridge, which is the first large scale cross-sea bridge in China, demonstrates that the proposed method is efficient and effective. 展开更多
关键词 REAL-TIME reliability first passage monitoring information power spectral density psd Donghai Bridge
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