共查询到20条相似文献，搜索用时 25 毫秒
1.
System identification is a method for using measured data to create or improve a mathematical model of the object being tested. From the measured data however, noise is noticed at the beginning of the response. One solution to avoid this noise problem is to skip the noisy data and then use the initial conditions as active parameters, to be found by using the system identification process. This paper describes the development of the equations for setting up the initial conditions as active parameters. The simulated data and response data from actual shear buildings were used to prove the accuracy of both the algorithm and the computer program, which include the initial conditions as active parameters. The numerical and experimental model analysis showed that the value of mass, stiffness and frequency were very reasonable and that the computed acceleration and measured acceleration matched very well. 相似文献
2.
以1978年至2008年的某省职工年平均工资作为样本数据、2009年至2010年的数据作为模型检验数据,建立了基于时间序列分析的ARMA模型,使用Eviews软件对时间序列进行分析,根据Box-Jenkins模型识别方法,得出模型的参数,进而得到模型,误差分析表明模型的预测结果非常理想。 相似文献
3.
This paper presents the explosion cratering effects and their propagation laws of blast waves in dry standard sands using
a 450 g-t geotechnical centrifuge apparatus. Ten centrifuge model tests were completed with various ranges of explosive mass, burial
depth and centrifuge accelerations. Eleven accelerometers were installed to record the acceleration response in sand. The
dimensions of the explosion craters were measured after the tests. The results demonstrated that the relationship between
the dimensionless parameters of cratering efficiency and gravity scaled yield is a power regression function. Three specific
function equations were obtained. The results are in general agreement with those obtained by other studies. A scaling law
based on the combination of the π terms was used to fit the results of the ten model tests with a correlation coefficient of 0.931. The relationship can be
conveniently used to predict the cratering effects in sand. The results also showed that the peak acceleration is a power
increasing function of the acceleration level. An empirical exponent relation between the proportional peak acceleration and
distance is proposed. The propagation velocity of blast waves is found to be ranged between 200 and 714 m/s. 相似文献
4.
The cohort growth model (CGM) is a method for estimating the parameters of a latent growth model (LGM) based on cross-sectional data. The CGM models the interindividual differences in the growth rate, and it models how subjects’ growth rate is related to their initial status. We derive model identification for the CGM and illustrate, in a simulation study, that the CGM provides unbiased parameter estimates in most simulation conditions. Based on empirical data we compare the estimates of the CGM with the estimates of the LGM. The results were comparable for both models. Although the estimates of the (co)-variances were different, the estimates of both models led to similar conclusions on the developmental change. Finally, we discuss the advantages and limitations of the CGM, and we provide recommendations for its use in empirical research. 相似文献
5.
将系统抽样方法应用于随机减量法中随机振动信号的提取,对当测量得到的结构响应信号数量很大时如何能较准确地识别结构系统的周期和阻尼比问题进行了研究,给出了结构系统周期和阻尼比估计量的表达式．数值算例结果表明,当结构系统响应信号长度很大时,该方法可较好地解决信号长度与识别精度的矛盾． 相似文献
6.
The least means squares (LMS) adaptive filter algorithm was used in active suspension system. By adjusting the weight of adaptive filter, the minimum quadratic performance index was obtained. For two-degree-of-freedom vehicle suspension model, LMS adaptive controller was designed. The acceleration of the sprung mass,the dynamic tyre load between wheels and road,and the dynamic deflection between sprung mass and unsprung mass were determined as the evaluation targets of suspension performance. For LMS adaptive control suspension, compared with passive suspension, acceleration power spectral density of sprung mass acceleration under the road input model decreased 8-10 times in high frequency resonance band or low frequency resonance band. The simulation results show that LMS adaptive control is simple and remarkably effective. It further proves that the active control suspension system can improve both the riding comfort and handling safety in various operation conditions, and the method is fit for the active control of the suspension system. 相似文献
7.
In structural equation models, outliers could result in inaccurate parameter estimates and misleading fit statistics when using traditional methods. To robustly estimate structural equation models, iteratively reweighted least squares (IRLS; Yuan & Bentler, 2000) has been proposed, but not thoroughly examined. We explore the large-sample properties of IRLS and its effect on parameter recovery, model fit, and aberrant data identification. A parametric bootstrap technique is proposed to determine the tuning parameters of IRLS, which results in improved Type I error rates in aberrant data identification, for data sets generated from homogenous populations. Scenarios concerning (a) simulated data, (b) contaminated data, and (c) a real data set are studied. Results indicate good parameter recovery, model fit, and aberrant data identification when noisy observations are drawn from a real data set, but lackluster parameter recovery and identification of aberrant data when the noise is parametrically structured. Practical implications and further research are discussed. 相似文献
8.
The soil-pile-bridge interaction of super-large pile groups is a very complex issue for the design of deep pile group foundations. In this paper, the load distribution on the pile top of a super large bridge foundation and its influential factors are analyzed comprehensively using a three-dimensional elasto-plastic finite element method. The adopted model and its input parameters are firstly verified by comparing the numerical results with the measured data of static loading tests of a single pile. Numerical analysis is then performed to investigate the load distribution and the load-settlement characteristics of super-large pile groups, and the models are verified using centrifuge laboratory model testing data. The mechanism of the interaction between pile groups and soil under different conditions is explored. 相似文献
9.
10.
1 Introduction Identification of an unknown systemfrom availabledata is i mportant in many fields . There are severalmodels representing systems that are dominated bynonlinear characteristics . NARMAX model provides aunified and si mple representation for a wide class ofdiscrete-ti me nonlinear stochastic systems , proposedby Leontaritis ,et al.[1]System identification usingNARMAX model consists of two stages : model struc-ture determination and parameter esti mation proce-dure . The ide… 相似文献
11.
研究了利用分布式点力源作为次级力源对封闭空腔内的结构辐射噪声进行控制的问题,并对封闭空腔中结构辐射噪声的控制机制进行了分析.建立了包含2块简支弹性板的矩形封闭空腔,并将其作为研究对象.通过对初、次级声场以及结构-声耦合的特性分析,以减小腔内声场的声压级为最优控制目标,分析比较了在不同位置及参数的次级点力激励下腔内声场的声压级响应.仿真结果表明,在2块弹性板上施加联合激振力控制腔内噪声的效果要明显好于激振力只作用在受激弹性板上. 相似文献
12.
Shear probe works under a tough environment where the turbulence signals to be measured are very weak.The measured turbulence signals often contain a large amount of noise.Due to wide frequency band,no... 相似文献
13.
WU Xiao-juan ZHU Xin-jian CAO Guang-yi TU Heng-yong 《浙江大学学报(A卷英文版)》2007,8(9):1505-1509
The solid oxide fuel cell (SOFC) is a nonlinear system that is hard to model by conventional methods. So far,most existing models are based on conversion laws,which are too complicated to be applied to design a control system. To facilitate a valid control strategy design,this paper tries to avoid the internal complexities and presents a modelling study of SOFC per-formance by using a radial basis function (RBF) neural network based on a genetic algorithm (GA). During the process of mod-elling,the GA aims to optimize the parameters of RBF neural networks and the optimum values are regarded as the initial values of the RBF neural network parameters. The validity and accuracy of modelling are tested by simulations,whose results reveal that it is feasible to establish the model of SOFC stack by using RBF neural networks identification based on the GA. Furthermore,it is possible to design an online controller of a SOFC stack based on this GA-RBF neural network identification model. 相似文献
14.
A Note on the Invariance of the DINA Model Parameters 总被引：1，自引：0，他引：1
Cognitive diagnosis models (CDMs), as alternative approaches to unidimensional item response models, have received increasing attention in recent years. CDMs are developed for the purpose of identifying the mastery or nonmastery of multiple fine-grained attributes or skills required for solving problems in a domain. For CDMs to receive wider use, researchers and practitioners need to understand the basic properties of these models. The article focuses on one CDM, the deterministic inputs, noisy "and" gate (DINA) model, and the invariance property of its parameters. Using simulated data involving different attribute distributions, the article demonstrates that the DINA model parameters are absolutely invariant when the model perfectly fits the data. An additional example involving different ability groups illustrates how noise in real data can contribute to the lack of invariance in these parameters. Some practical implications of these findings are discussed . 相似文献
15.
张平安 《深圳信息职业技术学院学报》2005,3(4):6-10
本文提出了模糊建模技术实现电力市场价格（market clearing price，MCP）短期预测的方法。该方法运用具有散射划分结构的Takagi—Sugeno-Kang（TSK）模糊模型，详细地介绍了辨识这种TSK模型结构的改进算法。特别地，由于这种结构辨识算法计算简单，划分准确，我们可设置良好的初始参数，加快建立MCP预测模糊模型的速度。用过去的MCP实际数据建模并测试TSK模型，所得到的结果是正确有效的。 相似文献
16.
A motion information analysis system based on the acceleration data is proposed in this paper,consisting of filtering,feature extraction and classification.The Kalman filter is adopted to eliminate the noise.With the time-domain and frequency-domain analysis,acceleration features like the amplitude,the period and the acceleration region values are obtained.Furthermore,the accuracy of the motion classification is improved by using the k-nearest neighbor （KNN） algorithm. 相似文献
17.
Wang Wenqi Wang Rongguang Chen Baolin Wang Tong 《上海大学学报(英文版)》1998,2(3):213-217
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18.
降噪处理是分析结构振动信号、提取特征参数、研究损伤识别方法的基础,核独立分量分析(KICA)采用的核方法为结构振动信号的降噪处理提供了新的方法;通过对比KICA与其他算法降噪后信号的HHT边际谱,验证了KICA对低阻尼钢框架结构标准损伤模型降噪的优良性能,特别是提高了对结构安全至关重要的低频振动部分的能量估计的准确度。 相似文献
19.
机构间隙转动副冲击碰撞模型的混沌研究 总被引：1，自引：0，他引：1
以钢球与钢套组成的体系为例,建立起钢球在钢套中运动的数学模型,编制了计算程序,得出了钢球与钢套之间的碰撞特性,说明了系统在一定条件下对初值极其敏感及存在混沌状态,为机构间隙转动副冲击碰撞模型的混沌研究奠定了基础. 相似文献
20.
An online experiment to acquire the interior noise of a China Railways High-speed (CRH) train showed that it was mainly composed of middle-low frequency components and could not be described properly by linear or A-weighted sound pressure level (SPL). Thus, the appropriate way to evaluate the high-speed train interior noise is to use sound quality parameters, and the most important is loudness. To overcome the disadvantages of the existing loudness algorithms, a novel signal-adaptive Moore loudness algorithm (AMLA) based on the equivalent rectangular bandwidth (ERB) spectrum was introduced. The validation reveals that AMLA can obtain higher accuracy and efficiency, and the simulated dark red noise conforms best to the high-speed train interior noise by loudness and auditory assessment. The main loudness component of the interior noise is below 27.6 ERB rate (erbr), and the sound quality of the interior noise is relatively stable between 300–350 km/h. The specific loudness components among 12–15 erbr stay invariable throughout the acceleration or deceleration process while components among 20–27 erbr are evidently speed related. The unusual random noise is effectively identified, which indicates that AMLA is an appropriate method for sound quality assessment of the high-speed train under both steady and transient conditions. 相似文献