针对往复压缩机振动信号的强非平稳特性,提出了一种基于有理Hermite插值的局部均值分解(Local mean decomposition,LMD)方法。结合有理Hermite插值法的保形特性和曲线形状随参数可调特性,以其构建极值点间局部包络曲线。提出以极值对称...针对往复压缩机振动信号的强非平稳特性,提出了一种基于有理Hermite插值的局部均值分解(Local mean decomposition,LMD)方法。结合有理Hermite插值法的保形特性和曲线形状随参数可调特性,以其构建极值点间局部包络曲线。提出以极值对称点为依据的局部包络线优选方法,进而提高局部均值与包络估计的拟合逼近精度。给出了有理Hermite插值LMD方法的算法与流程。利用仿真数据,通过与不同插值方法比较,验证了有理Hermite插值LMD方法拟合逼近性能的优越性。以往复压缩机轴承故障振动信号为研究对象,应用有理Hermite插值LMD方法实现了轴承间隙大故障的准确诊断,验证了该方法对强非平稳信号的适用性。展开更多
The original unified hardening(UH) model, in which a straight Hvorslev envelope was employed to determine the potential peak stress ratio of overconsolidated soils, is revised using a smoothed Hvorslev envelope(Hermit...The original unified hardening(UH) model, in which a straight Hvorslev envelope was employed to determine the potential peak stress ratio of overconsolidated soils, is revised using a smoothed Hvorslev envelope(Hermite-Hvorslev envelope). The strength at the intersection between the straight Hvorslev envelope and the critical state surface(i.e. Mohr-Coulomb envelope) can be undefined due to the discontinuous change in the slope of the two linear strength envelopes mentioned above. A smoothed Hvorslev envelope is derived through Hermite interpolation to ensure a smooth change between the proposed Hvorslev envelope and the zero-tension surface as well as a smoothed transition between the proposed Hvorslev envelope and the critical state surface. The Hermite-Hvorslev envelope is then integrated into the original UH model, and then the UH models with four different functions of the Hvorslev envelope are compared with each other. The UH model revised by the Hermite-Hvorslev envelope can well predict the mechanical behaviors of normally consolidated and overconsolidated soils in drained and undrained conditions with the same parameters in the modified Cam-Clay model.展开更多
建立了超声测距时延估计模型,由于窄带超声回波参考信号与接收信号的相关函数在极值点附近具有慢衰减高频振荡特性,所以有必要将搜索直接相关函数的极值点转化为搜索相关函数包络的极值点.针对相关峰常规插值方法在多倍插值的情况下存...建立了超声测距时延估计模型,由于窄带超声回波参考信号与接收信号的相关函数在极值点附近具有慢衰减高频振荡特性,所以有必要将搜索直接相关函数的极值点转化为搜索相关函数包络的极值点.针对相关峰常规插值方法在多倍插值的情况下存在计算复杂、时延估计精度不高等缺点,结合超声回波信号的窄带带通特性和相关峰细化(F ine In terpo lation of Corre lation Peak)原理,提出了直接提取相关函数包络及包络峰细化方法,并分析了其计算复杂度.仿真与实验研究表明,该方法能大大提高相关函数包络峰值分辨率,适用于类超声回波信号的带通信号精细时延估计问题.展开更多
Meshed surfaces are ubiquitous in digital geometry processing and computer graphics. The set of attributes associated with each vertex such as the vertex locations, curvature, temperature, pressure or saliency, can be...Meshed surfaces are ubiquitous in digital geometry processing and computer graphics. The set of attributes associated with each vertex such as the vertex locations, curvature, temperature, pressure or saliency, can be recognized as data living on mani- fold surfaces. So interpolation and approximation for these data are of general interest. This paper presents two approaches for mani- fold data interpolation and approximation through the properties of Laplace-Beltrami operator (Laplace operator defined on a mani- fold surface). The first one is to use Laplace operator minimizing the membrane energy of a scalar function defined on a manifold. The second one is to use bi-Laplace operator minimizing the thin plate energy of a scalar function defined on a manifold. These two approaches can process data living on high genus meshed surfaces. The approach based on Laplace operator is more suitable for manifold data approximation and can be applied manifold data smoothing, while the one based on bi-Laplace operator is more suit- able for manifold data interpolation and can be applied image extremal envelope computation. All the application examples demon- strate that our procedures are robust and efficient.展开更多
在基于三次样条插值的局部均值分解方法(local mean decomposition based on cubic spline interpolation,CSI-LMD)中,三次样条插值在获取被测信号的包络线时缺乏灵活性,是影响该方法分解信号准确性的一个重要因素。有理样条插值作为三...在基于三次样条插值的局部均值分解方法(local mean decomposition based on cubic spline interpolation,CSI-LMD)中,三次样条插值在获取被测信号的包络线时缺乏灵活性,是影响该方法分解信号准确性的一个重要因素。有理样条插值作为三次样条插值的一般形式,可以通过其极点参数调节插值曲线的松紧度,灵活适应不同类型的被测信号。为提高LMD分解信号的准确性,采用有理样条插值代替三次样条插值,并结合二分法原理确定有理样条插值函数的最优极点参数值。通过对单一电能质量扰动信号和复合电压暂降扰动信号的时频分析,验证了基于有理样条插值的LMD方法(LMD based on rational spline interpolation,RSI-LMD)在检测和分析电压暂降扰动信号方面的有效性。展开更多
文摘针对往复压缩机振动信号的强非平稳特性,提出了一种基于有理Hermite插值的局部均值分解(Local mean decomposition,LMD)方法。结合有理Hermite插值法的保形特性和曲线形状随参数可调特性,以其构建极值点间局部包络曲线。提出以极值对称点为依据的局部包络线优选方法,进而提高局部均值与包络估计的拟合逼近精度。给出了有理Hermite插值LMD方法的算法与流程。利用仿真数据,通过与不同插值方法比较,验证了有理Hermite插值LMD方法拟合逼近性能的优越性。以往复压缩机轴承故障振动信号为研究对象,应用有理Hermite插值LMD方法实现了轴承间隙大故障的准确诊断,验证了该方法对强非平稳信号的适用性。
基金financially supported by the Australian Research Council DECRA (Grant No. DE130101342)the National Program on Key Basic Research Project of China (Grant No. 2014CB047006)
文摘The original unified hardening(UH) model, in which a straight Hvorslev envelope was employed to determine the potential peak stress ratio of overconsolidated soils, is revised using a smoothed Hvorslev envelope(Hermite-Hvorslev envelope). The strength at the intersection between the straight Hvorslev envelope and the critical state surface(i.e. Mohr-Coulomb envelope) can be undefined due to the discontinuous change in the slope of the two linear strength envelopes mentioned above. A smoothed Hvorslev envelope is derived through Hermite interpolation to ensure a smooth change between the proposed Hvorslev envelope and the zero-tension surface as well as a smoothed transition between the proposed Hvorslev envelope and the critical state surface. The Hermite-Hvorslev envelope is then integrated into the original UH model, and then the UH models with four different functions of the Hvorslev envelope are compared with each other. The UH model revised by the Hermite-Hvorslev envelope can well predict the mechanical behaviors of normally consolidated and overconsolidated soils in drained and undrained conditions with the same parameters in the modified Cam-Clay model.
文摘建立了超声测距时延估计模型,由于窄带超声回波参考信号与接收信号的相关函数在极值点附近具有慢衰减高频振荡特性,所以有必要将搜索直接相关函数的极值点转化为搜索相关函数包络的极值点.针对相关峰常规插值方法在多倍插值的情况下存在计算复杂、时延估计精度不高等缺点,结合超声回波信号的窄带带通特性和相关峰细化(F ine In terpo lation of Corre lation Peak)原理,提出了直接提取相关函数包络及包络峰细化方法,并分析了其计算复杂度.仿真与实验研究表明,该方法能大大提高相关函数包络峰值分辨率,适用于类超声回波信号的带通信号精细时延估计问题.
基金Supported by National Natural Science Foundation of China (No.61202261,No.61173102)NSFC Guangdong Joint Fund(No.U0935004)Opening Foundation of Key Laboratory of Symbolic Computation and Knowledge Engineering of Ministry of Education of China(No.93K172012K02)
文摘Meshed surfaces are ubiquitous in digital geometry processing and computer graphics. The set of attributes associated with each vertex such as the vertex locations, curvature, temperature, pressure or saliency, can be recognized as data living on mani- fold surfaces. So interpolation and approximation for these data are of general interest. This paper presents two approaches for mani- fold data interpolation and approximation through the properties of Laplace-Beltrami operator (Laplace operator defined on a mani- fold surface). The first one is to use Laplace operator minimizing the membrane energy of a scalar function defined on a manifold. The second one is to use bi-Laplace operator minimizing the thin plate energy of a scalar function defined on a manifold. These two approaches can process data living on high genus meshed surfaces. The approach based on Laplace operator is more suitable for manifold data approximation and can be applied manifold data smoothing, while the one based on bi-Laplace operator is more suit- able for manifold data interpolation and can be applied image extremal envelope computation. All the application examples demon- strate that our procedures are robust and efficient.
文摘在基于三次样条插值的局部均值分解方法(local mean decomposition based on cubic spline interpolation,CSI-LMD)中,三次样条插值在获取被测信号的包络线时缺乏灵活性,是影响该方法分解信号准确性的一个重要因素。有理样条插值作为三次样条插值的一般形式,可以通过其极点参数调节插值曲线的松紧度,灵活适应不同类型的被测信号。为提高LMD分解信号的准确性,采用有理样条插值代替三次样条插值,并结合二分法原理确定有理样条插值函数的最优极点参数值。通过对单一电能质量扰动信号和复合电压暂降扰动信号的时频分析,验证了基于有理样条插值的LMD方法(LMD based on rational spline interpolation,RSI-LMD)在检测和分析电压暂降扰动信号方面的有效性。