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1.
基于非均匀周期采样的随机共振研究   总被引:2,自引:1,他引:1       下载免费PDF全文
随机共振的参数调节过程比较复杂,而且一般要求采样频率不低于信号频率的50倍以上才能实现随机共振。该文借鉴非均匀采样的思想,提出基于非均匀周期采样的随机共振实现方法,对不同采样频率下的采样数据进行随机共振,并利用非均匀采样傅里叶变换进行频谱叠加分析,可以实现只需简单确定随机共振参数即可得到特征信号成分。此种方法还可以在采样频率小于50倍信号频率时,依然能够得到特征信号频率成分。数值仿真和故障模拟实验研究验证了该方法有效的应用性。  相似文献   

2.
针对信号特征频率和采样频率所要求的匹配关系对Duffing振子变尺度随机共振的限制,研究一种频谱重构的信号预处理方法,并进一步提出基于Duffing振子的信号频谱重构随机共振方法。该方法通过引入频谱重构参数实现信号特征频率的灵活转化,与变尺度方法和阻尼比参数调节方法相结合,可以实现任意信号特征频率和采样频率下的Duffing系统的大参数随机共振,从而扩展其在微弱信号处理中的应用。数值仿真和故障诊断实例分析均验证了该方法的有效性。  相似文献   

3.
欠采样噪声分析与光电一体化设计   总被引:2,自引:0,他引:2  
欠采样噪声产生分布于整个画面的附加像,给目标识别等应用带来困难。基于信息理论,建立了欠采样噪声的应用分析模型,提出了采样成像系统光电一体化设计方法。通过仿真试验,得出欠采样噪声与光学成像系统参数的关系。理论分析和仿真证明,根据系统互信息量选择光、电系统参数,可以减小欠采样噪声,提高图像质量。  相似文献   

4.
分析了二次采样随机共振中涉及到的重要参数采样频率和二次采样频率,结合理论推导与仿真,得出了这两个参数对系统输出效果的具体影响,同时分析了造成这些影响的原因,提出了这两个参数选取的方法,为更好地应用二次采样随机共振检测微弱周期信号提供了依据。  相似文献   

5.
针对非均匀采样序列提出了一种四参数正弦波形曲线拟合方法.它借助于频率已知的三参数正弦曲线拟合算法实现,既可以在非均匀采样条件下获得正弦波采样序列的4个参数拟合值,也可用于均匀采样条件下正弦波形采样序列的曲线参数拟合.其特点是将幅度、频率、相位和直流分量4个参数的四维非线性最优化问题转化成频率参数的一维线性搜索和最优化问题.其优点是无需先验初值估计,具有良好的收敛性、鲁棒性,以及明确的收敛区间.仿真及实验均证明了该方法的有效性和可行性.该方法可用于解决非均匀采样和均匀采样下正弦波测量序列的参数拟合问题.  相似文献   

6.
李芦钰  牛芸 《振动与冲击》2014,33(18):190-197
首先介绍利用复Morlet小波变换进行结构非线性振动模型参数识别的原理,进而分析了因小波变换过程中的边端效应以及在采样点较少情况下复Morlet小波变换对非线性模型参数识别准确性的影响。然后提出了利用BP神经网络对非线性模型参数识别的信号进行预测延拓,并基于预测后的信号进行参数识别。最后通过对两种非线性振动模型进行数值仿真,验证了该方法能很好的提高非线性模型参数识别的准确性,并且具有一定的抗噪能力。  相似文献   

7.
马杰  姚郁 《高技术通讯》2002,12(6):34-37,42
从频域设计角度出发,应用离散信号分析方法,提出了仿真转台周期时变系统-采样控制系统QFT设计参数的选取方法,并应用采样控制系统直接设计方法,在不丢失采样时刻之间系统信息的条件下,通过对系统进行提升化处理,求解等效离散系统,使仿真转台伺服控制系统的QFT设计问题转化为采样控制系统混合灵敏度设计问题,为仿真转台数字控制器的设计提供了一种新方法。在此基础上同时给出了某电仿真转台控制系统QFT设计实例。  相似文献   

8.
刘营  李鸿光  李韵  杜环宇 《振动与冲击》2020,39(16):148-154
针对参数化模型降阶方法在多维参数维度的情况下面临采样点过多、离线构建降阶模型数据库时间长等问题,提出了一种基于子结构的参数化模型降阶方法。在固定界面模态综合法的基础上,设置标准模态矩阵,利用不同参数主模态矩阵之间的Frobenius范数最小准则确定了转换矩阵,推导了子结构降阶矩阵各元素的变换公式,对其进行坐标转换;对参数空间上的采样点重复整个计算过程生成了坐标兼容的离线数据库。并以电磁振动台动圈为例,采用该方法对均布采样样本点展开了仿真研究。结果表明,此方法能大幅减少采样点的个数及模型生成与计算时间,提高降阶模型离线训练效率;所构建的参数化降阶模型具备很高的在线计算效率及计算准确度。  相似文献   

9.
彭成  王平波  刘旺锁 《声学技术》2014,33(5):473-476
Alpha稳定分布是对水声混响数据进行非高斯概率密度拟合的最优模型之一,而仿真产生服从标准参数系下的Alpha稳定分布序列是展开相应研究的基础。论述了三种参数系下服从Alpha稳定分布随机变量的变换关系及各种参数系表述的优缺点,实现了标准参数系下任意参数组合Alpha稳定分布序列的数值仿真;同时还利用直接数值积分法完成了无显性概率密度表达式的Alpha稳定分布序列概率密度值计算,以之作为理论值与统计值进行了分析比较,验证了数值仿真方法的正确性。  相似文献   

10.
利用数值仿真方法,分析了单自由度含对称弹性约束碰撞振动系统在(ω,b)参数平面内周期运动的分布及转迁规律。根据周期运动的边界条件和衔接条件理论推导得到了系统n-1-1_S周期运动存在的条件。数值仿真得到了系统在(ω,b)参数平面内的周期运动分布图,并根据各周期运动转迁的特点将参数平面划分为两个参数域,进而结合胞映射方法对各参数域内周期运动的转迁规律、周期吸引子及其吸引域的分布进行了分析;总结了各参数域内周期运动之间的相互转迁规律。  相似文献   

11.
李建华  毛文贵  周舟 《振动与冲击》2020,39(10):121-126
风机不对中故障是多载荷参数耦合而成,工程师难以凭经验了解载荷参数的大致范围。针对因转子结构参数和测试条件等不确定性参数的存在及载荷参数先验信息未知,最大似然法识别转子不对中故障的载荷参数时采用的搜索计算面临计算量大,且迭代过程中灵敏度会带来一些数值问题。引入搜索区间进退法到敏感矩阵法与最大似然法中,对最大似然法进行改进。改进后的最大似然法中的迭代适于处理复杂工程优化问题,避免传统迭代数值法对搜索空间的苛刻要求。以输入尺寸和输出测试响应具有随机性测量误差的风力发电机转子系统为例,在三种测量误差下的识别结果表明,改进的最大似然法提高了最大似然法的辨识效果,可以减少不确定性因素对识别结果的影响,鲁棒性好。  相似文献   

12.
 A new method named as Statistical Average Algorithm is developed for solving the structural dynamic compound inverse problem, which means to identify structural parameters with unknown input or to inverse input time history with unknown structural parameters. By taking the mechanical characteristic of the ground motion as an additional condition, an iterative algorithm based on the least-squares technique is developed so that the input process and structural parameters can be correctly determined using only output measurements. The procedure of the proposed method is discussed in detail, and a mathematical proof is presented as well in the appendix. A practical input situation such as earthquake, ambient vibration is considered in the numerical examples to verify the accuracy, reliability and robustness of the proposed algorithm. Considering the background of the practical application, both of the noise-free and noise-included output responses are considered in the numerical examples. In all cases, the proposed method identifies the structural parameters and reconstructs the input process rationally. Received: 12 March 2001 / Accepted: 16 September 2002  相似文献   

13.
一种分段平稳随机信号的参数识别方法   总被引:1,自引:1,他引:1  
基于振动的结构健康监测的前提是从振动测试信号中提取结构模态参数。随机子空间方法是近年来发展起来的一种线性系统辨识方法,可以有效地从环境激励的结构响应信号中提取结构模态参数。随机子空间识别方法的应用前提是输人满足白噪声的假定,输出信号应当是平稳信号。论文对随机子空间方法的使用前提进行了拓展。将非平稳信号划分为分段平稳随机信号进行处理,为非平稳信号的研究提供一种新的分析方法。基本思想是将在现场采集的结构输出信号进行分段,各段信号应满足稳定的条件,即分段平稳。将各段信号用随机子空间结合稳定图进行识别,然后将所有各段所识别的模态参数再一次用稳定图方法进行分析,得出结构的模态参数。最后用-3跨连续梁的数值模型进行验证,结果表明用随机子空间方法结合两次稳定图可以有效地识别分段平稳的随机信号。  相似文献   

14.
基于AUTODYN软件建立了水下爆炸一维楔形模型,对空气不耦合装药结构下爆炸能量的输出进行研究。首先获得炸药冲击波压力以及气泡脉动随时间的变化曲线,进一步获知径向不耦合状态下水下爆炸的冲击波峰值压力、气泡最大半径以及脉动周期等数据,并最终得到了不耦合系数下冲击波能以及气泡能的变化情况。将计算结果与已有的水下爆炸实验结果进行了比较分析。结果表明,该计算结果与实验数据吻合较好,证明了利用数值计算手段可以实现定量化表征炸药输出能量随不耦合装药结构的变化规律。  相似文献   

15.
本文提出一种用于多维线性模型(AR,ARMA)参数估计的神经网络方法和相应的递归预测误差算法。本文在分析多输入、单输出,含一个隐含和多层神经网络的输入输出关系的基础上,提出了首先将理想输出Xi进行预畸变(F(Xt))作为神经网络的训练目标。当神经网络训练完毕后,网络的连接权就是待估计的线性模型参数。本文提出方法的优点是网络结构简单,估计结果准确。仿真模拟结果表明,本文所提出的神经网络方法估计多维线性模型参数是有效的。  相似文献   

16.
In this study, a synthesis method for a non-integer periodic function generator of a four-bar mechanism using a Haar wavelet is presented. Using wavelet theory, the mathematical model for the output of a four-bar mechanism is established. Next, the characteristics of the four-bar mechanism output variable are described by the wavelet feature parameters; the relationship of the wavelet feature parameters between the output and its translation or dilation is also investigated. Based on this finding, three numerical atlas databases comprising of 203,500 groups of basic dimensional types of planar four-bar mechanisms, 148,995 groups of basic dimensional types of spherical four-bar mechanism and 11,175 groups of basic dimensional types of planar slider–crank mechanism are compiled. According to the internal relationship between the wavelet feature parameters, the sizes of the objective mechanism can be obtained using fuzzy recognition. Based on a genetic algorithm, optimization of the link parameters can be realized. Three examples are presented to demonstrate the efficacy and practicality of the proposed theory.  相似文献   

17.
The association mechanism between the main operation parameters and multi-physical fields of the large-scale vertical mill system is unclear, which leads to the difficulty in optimizing operation parameters to improve the performance of large vertical mill systems. To investigate the mechanism of multi-physical field coupling in the operation of the large vertical mill, the numerical simulation method is constructed by coupled CFD-DPM model to calculate the finished product quality, the simulation results were in good agreement with the actual operation results. Based on the Kriging surrogate model, a multi-objective optimization framework for large vertical mills is proposed. Finally, the multi-objective optimization design of LGM large vertical mills is carried out. Combined with CFD-DPM coupling method is developed, design variables and output responses are determined. The Kriging method is used for correlation analysis. The multi-objective optimization function was established. The NSGA-II. optimization algorithm was used to update the surrogate model and obtain the optimal solution, and the optimized operating parameters increased the vertical mill yield by 5.34% and the specific surface area by 9.07%. The maximum relative error between the simulated value and the optimized value is 2.02% through numerical calculation, which verifies the superiority of the optimization method of large vertical mill for performance improvement.  相似文献   

18.
This paper introduces a method for the synthesis of the multiple tasks of a planar six-bar mechanism by wavelet series. Based on the theory of wavelet series, a mathematical model for assessing the output of multiple tasks of planar linkage mechanisms was generated. The multiple tasks that combine a function generation and a rigid body guidance will be presented throughout this paper. For function generation, a numerical atlas database, including 31,775 groups of basic dimensional types of a planar slider-crank mechanism was created based on the relationships of the wavelet feature parameters. For rigid body guidance synthesis, an output feature parameters database of a planar four-bar motion generation, including 178,810 groups of the basic dimensional types was created by analysing the relationships of the wavelet coefficients between the rigid body rotation angle and the coupler rotation angle of its corresponding basic dimensional types. The actual sizes and installation position parameters of the planar six-bar mechanism were calculated using the fuzzy identification method and theoretical formulas. Finally, an application is presented to illustrate the validity and practicality of the proposed theory.  相似文献   

19.
基于周期统计平均的结构动力复合反演研究   总被引:3,自引:0,他引:3  
研究了输入未确知条件下的参数识别、荷载反演问题。根据激励的周期特性,运用统计平均的思想,构造出一类时域识别反演算法。数值算例表明,该算法的参数识别精度高,且具有很强的噪声适应能力和初参数选择鲁捧性。将本算法与全量补偿算法有机会结合,可更好地解决在旋转动力设备周期激振力作用下的结构参数识别及荷载反演问题。  相似文献   

20.
This paper explores the possibilities of numerical methods for uncertainty analysis of personal dosimetry systems. Using a numerical method based on Monte Carlo sampling the probability density function (PDF) of the dose measured using a personal dosemeter can be calculated using type-test measurements. From this PDF the combined standard uncertainty in the measurements with the dosemeter and the confidence interval can be calculated. The method calculates the output PDF directly from the PDFs of the inputs of the system such as the spectral distribution of the radiation and distributions of detector parameters like sensitivity and zero signal. The method can be used not only in its own right but also for validating other methods because it is not limited by restrictions that apply to using the Law of Propagation of Uncertainty and the Central Limit Theorem. The use of the method is demonstrated using the type-test data of the NRG-TLD.  相似文献   

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