基于最小二乘法的正弦波谐波失真度测试

本文介绍了直接数字合成正弦波的基本原理,在此基础上对合成正弦波的频谱进行了分析,论述了产生谐波失真的原因,重点讨论了利用最小二乘法测量合成正弦波的谐波失真度(THD)的方法,给出了测量的基本原理.并使用数字存储示波器和微型计算机组成一个测试系统,对给出的测试方法进行验证.     

基于加强的部分最小二乘回归方法的电网谐波发射水平评估

本文提出了一种基于改进的部分最小二乘回归的供电系统谐波阻抗和谐波发射水平估计方法。该方法解决了偏最小二乘回归方法不能高效率地依次提取对因变量解释能力强的成分,可能漏选有用成分的缺陷。仿真计算结果验证了该方法的有效性。     

最小二乘法在压缩机选型中的应用

在制冷工程设计过程中,传统的压缩机选型计算过程复杂,涉及到大量数据资料的查询,耗时较长,误差较大,影响选型的准确性及微机的应用。因此,可利用最小二乘法原理,将各种型号压缩机的性能曲线拟合成公式,从而提供一种更简捷、更高效的压缩机选型新方法。     

基于约束总体最小二乘法的高分辨正弦信号频率估计方法

分析了噪声背景下实谐波过程ARMA模型系数之间的对称性,并以此为约束条件加入ARMA谱估计方法的求解过程中,从而提出了一种改进的正弦信号频率估计方法.理论分析与计算机仿真表明,对于低信噪比条件下的正弦信号参量估计,这一算法的精度与稳定性都优于仅使用总体最小二乘法(SVD-TLS)的ARMA谱估计方法.     

基于最小二乘法改进的随机圆检测算法

提出了一种利用最小二乘法迭代修正随机圆检测的改进算法.解决了由于随机圆检测算法中阈值选取不当,造成同一个圆被分割为多个圆的问题.首先根据随机选取四个点求解出的圆参数,得到属于假设圆的点集;然后由当前点集,利用最小二乘法重新计算得到新的圆参数;接着根据新参数,检测集合中属于当前假设圆的新点,加入到当前点集中,重新计算圆参...     

最小二乘法在压缩机选型中的应用

制冷工程设计过程中，传统的压缩机选型计算过程复杂，涉及到大量数据资料的查询，耗时较长．误差较大．影响选型的准确性及微机的应用．因此，可利用最小二乘法原理，将各种型号压缩机的性能曲线拟合成公式，从而提供一种更简捷，更高效的压缩机选型新方法．     

基于改进型偏最小二乘法的谐波源识别

准确识别配电网中各个谐波源是电能质量管理的难点。当采用谐波阻抗识别谐波源时,很难得到谐波阻抗。首先,该文采用改进型偏最小二乘法,通过计算对谐波阻抗进行估计,用估计值代替实际测量得到的数值。其次,利用阻抗法,根据谐波电流的大小来判断主要谐波源,从而识别谐波源的位置。该方法不需要进行数据选择,能够避免偏最小二乘法提取和响应无关成分的缺陷,尤其是在整个系统谐波源数量较多的情况下,该方法可以得到更好的效果。最后,进行系统试验仿真,以证明该方法的可行性。     

最小二乘法原理及其处理方法的探讨

本文通过对最小二乘法测量方程与残余误差方程进行描述,说明了最小二乘法的原理,明确了其在数据处理和误差计算方面的适用范围,在工程实际和实验技术中具有重要作用。     

基于最小二乘法的长期趋势变动研究

长期趋势是时间数列分析中一种重要的变动模式,研究长期趋势的变动模型对揭示社会经济现象的规律具有重要意义。本文利用最小二乘法来确定长期趋势的变动方程,由此方程外推长期趋势在下一时期的状态值,从而实现对社会经济现象的跟踪预测,最终为决策分析提供数据支持。     

基于最小二乘法的Lagrange分析方法研究

Lagrange分析方法是通过测量各个拉格朗日位置处的物理量历程来分析材料内部该位置处的其他物理量的变化,进而认识材料的动态力学性能。但现有的Lagrange分析方法在已知应变情况下,求解方法仍有不足。本文针对这一情况,将反解法和自洽检验法相结合,提出了基于最小二乘法的Lagrange反解法。该方法的理论精度能够实现沿径线的 阶导数 （ 为迹线数）,并且该方法满足自洽检验法,算法本身不会造成数据处理结果的失真,其精度完全取决于试验精度和数据量。利用该方法对一组混凝土在冲击作用下的实验数据进行了处理,计算得到了相应的粒子速度波形、应力波形以及加、卸载全过程的应力-应变曲线,从而揭示出混凝土材料与应变率相关的弹-塑性本构关系的特征。     

改进EMD端点效应电力系统HHT谐波检测研究

为对电力系统谐波进行有效的检测,提出一种改进的基于镜像延拓的方法对信号数据边界进行端点处理。通过对端点和极值点的判断比较来选取镜面进行延拓,按照包络原则对延拓之后的信号进行经验模态分解(EMD),并得到IMF分量。仿真实验结果表明:改进后的方法幅值及频率检测准确度明显优于改进前,能够有效改善EMD端点效应,准确快速地分解出各种模态的谐波,适用于电力系统谐波的检测。     

Adaptive resonator-based method for power system harmonic analysis

A simple algorithm for the harmonic estimation, in a wide range of frequency changes, with benefits in a reduced complexity and computational efforts is prescribed. This implementation is based on a recently introduced common structure for recursive discrete transforms and contemplated as an implementation of finite-impulse-response (FIR) and infinite-impulse-response (MR) filter transfer functions to reduce computational efforts. This structure consists of digital resonators in a common negative feedback loop. The structure of the estimation algorithm consists of two decoupled modules: the first one for an adaptive filter of input signal with harmonic amplitude and phase calculation, the second one for an external frequency estimation. A very suitable algorithm for frequency and harmonic phasor estimations is obtained. To demonstrate the performance of the developed algorithm, computer-simulated data records are processed. Simulation results show that this algorithm is applicable to detect the harmonic amplitudes of steady-state, varying and decaying sinusoidal signals. It has been found that the proposed method really meets the needs of online applications. This technique provides accurate amplitude estimates in about one period.     

A hybrid finite difference and moving least square method for elasticity problems

In this paper, a novel hybrid finite difference and moving least square (MLS) technique is presented for the two-dimensional elasticity problems. A new approach for an indirect evaluation of second order and higher order derivatives of the MLS shape functions at field points is developed. As derivatives are obtained from a local approximation, the proposed method is computationally economical and efficient. The classical central finite difference formulas are used at domain collocation points with finite difference grids for regular boundaries and boundary conditions are represented using a moving least square approximation. For irregular shape problems, a point collocation method (PCM) is applied at points that are close to irregular boundaries. Neither the connectivity of mesh in the domain/boundary or integrations with fundamental/particular solutions is required in this approach. The application of the hybrid method to two-dimensional elastostatic and elastodynamic problems is presented and comparisons are made with the boundary element method and analytical solutions.     

A convected particle least square interpolation material point method

Applying the convected particle domain interpolation (CPDI) to the material point method has many advantages over the original material point method, including significantly improved accuracy. However, in the large deformation regime, the CPDI still may not retain the expected convergence rate. The paper proposes an enhanced CPDI formulation based on least square reconstruction technique. The convected particle least square interpolation (CPLS) material point method assumes the velocity field inside the material point domain as nonconstant. This velocity field in the material point domain is mapped to the background grid nodes with a moving least squares reconstruction. In this paper, we apply the improved moving least squares method to avoid the instability of the conventional moving least squares method due to a singular matrix. The proposed algorithm can improve convergence rate, as illustrated by numerical examples using the method of manufactured solutions.     

基于谐波平衡法的双稳态压电发电系统非线性振动特性研究

研究双稳态压电发电系统非线性振动特性。通过谐波平衡法计算获得系统幅频响应方程,分析不同非线性系数、阻抗参数与激励对系统幅值解影响,随激励频率、幅值的变化,双稳态压电发电系统幅值解存在跳跃、多解现象,调节非线性系数及阻抗参数可使不稳定区域范围最小;研究外加激励对功率影响,随非线性系数及阻抗参数的增加,输出功率先增加后减小,通过调节磁化强度与负载阻抗可使系统输出功率最大;通过实验所得频率电压响应曲线及电阻功率响应曲线,验证系统非线性分析结果。可为双稳态压电发电系统工程应用提供理论依据。     

几何功能约束最小二乘法双短圆弧检测

针对双短圆弧的准确检测难题,首先从工件的几何功能使用要求出发,详细分析使用三坐标测量机检测双短圆弧时误差产生的原因与影响;然后根据误差产生的原因,提出基于几何功能约束最小二乘拟合的双短圆弧检测方法。该方法将双短圆弧的设计半径、相对位置关系以及圆弧整体轮廓与工作基准的位置作为最小二乘圆拟合的约束条件,以降低拟合的误差。将该检测方法与经典最小二乘圆弧分段拟合检测方法进行对比实验,结果表明:提出的方法能够很好地改善最小二乘法对双短圆弧的拟合质量,有效降低检测结果的"误判"风险,可为双短圆弧的精确检测提供一种可靠方法。     

改进最小二乘法双目视觉位姿测量技术研究与测试

由于工件表面油污、光照等因素干扰导致工件图像提取的特征点偏离实际位置,对工业机器人的抓取定位带来较大误差。该文以视觉引导工业机器人抓取气缸盖为应用对象,对双目视觉高准确度位姿测量技术进行分析。首先探讨特定条件下的双目视觉定位引导机器人技术以及粗差点产生原因与解决方法情况;其次介绍视觉系统视觉坐标系和目标坐标系,然后在位姿测量数学模型的基础上提出改进最小二乘法的准确计算方法,并搭建双目视觉引导的工业机器人抓取气缸盖系统进行测试分析。测试表明:改进最小二乘法的位姿计算方法可实现双目视觉对目标物的全自由度位姿测量,满足工业机器人高准确度抓取操作。     

基于加权最小二乘法的弹体转速测量方法研究

针对常规弹药在高旋状态下的转速测量值不准确这一难题,搭建基于无刷直流电机控制的稳定平台,并在此基础上提出一种基于加权最小二乘法的弹体转速测量方法。对测量原理进行简要阐述,然后引入相关的融合算法,通过3个不同量程的陀螺仪的测量值计算弹体转速的无偏估计量,以达到复现弹体转速的目的,从理论上证明加权最小二乘法这一融合算法的优越性。设计车床试验,试验结果表明该方法的测试结果与理论基本相符,最终使弹体转速测量精度提高一个数量级。该方法为常规弹药的导航、制导提供相关支持,具有一定工程应用价值。     

A power system digital harmonic analyzer

The authors describe the design of a harmonic analyzer for use in studying the harmonic content of commercial electric power. This MC 68000-based instrument samples the waveform and calculates the first 63 harmonics of the 60-Hz fundamental for both a voltage and current waveform. The 64-kbyte memory is adequate for one week of hourly samples for a power-quality survey by an electrical utility. The analyzer is quickly attached to the outputs of potential and current transformers by alligator clips and a current plug. The harmonic data are retrieved from the instrument by a portable computer. A separate personal computer (PC) program is then used for data analysis. Accuracy is shown to be about 0.1%, more than adequate for power quality surveys