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1.
电子器件中的功率放大器常常伴随着非线性失真效应.为解决此类非线性失真问题,通过研究无记忆和有记忆功放的失真特性,运用最小二乘法来构建多种形式的特性拟合函数,在选择了效果较好的特性拟合函数基础上,根据实际约束条件进行预失真模型的建立,使失真处理后的输出信号趋于线性,最后从信号的功率谱密度的角度出发检验预失真模型的补偿效果,证明模型具有较好的可行性和准确性.  相似文献   

2.
信号的功率放大器是电子通信系统的关键器件之一,功放的输出信号相对于输入信号可能产生非线性变形,这将带来无益的干扰信号,研究其机理并采取措施改善,具有重要意义.通过利用无记忆非线性功放和记忆非线性功放的实测数据用数学方法对其分别进行建模,而后使用前置预失真器的方法改善功放的非线性特性,并对其中预失真器的建模做了研究,采用间接学习型结构构建预失真器模型.仿真结果显示功放非线性模型结合预失真器模型能够很好地逼近实际情况,并且能很好地抑制带外频谱扩展.  相似文献   

3.
功率放大器的非线性化导致信号的失真,是电子信息行业普遍存在的问题之一.在功率放大器的前端引入预失真模块能对失真有很好的改善,也是目前研究较多的一种方法.从这一点出发,研究了非记忆性功放和记忆性功放的输入输出特征曲线,分别利用分段线性模型以及记忆多项式模型进行了拟合与数学表示,并构建了预失真模型以及预失真函数,对引入预失真模块的整个系统进行了仿真实验和评价指标的计算.最后对有记忆功放进行了Burg法功率谱密度分析,计算出了ACPR值并进行分析.  相似文献   

4.
预失真技术是克服功率放大器非线性失真的一种非常有效的方法.许多研究者从数学建模的思想角度出发,建立了关于功放与预失真的各类级数模型,以实现线性增益输出.但是在应用通信系统中,这些模型不能有效地动态实现功放效率尽可能高的要求.在和记忆多项式模型的基础上,创新地运用多目标规划的方法优化功放的预失真模型.在满足一定的线性化输出的同时,尽可能地得到更高的功放效率,而且能同时计算出增益系数与模型参数.对于数据量为1000的无记忆功放得到增益倍数为1.82649,预失真模型的NMSE值为-41.5633.数据量为73920的有记忆功放得到增益倍数为9.5969,预失真模型的NMSE值为-24.3682.  相似文献   

5.
宽带移动通信传输正在改变着人们的生活.作为信息传输的重要环节,信号的功率放大在无线通信中起着关键作用.第十届全国研究生数模竞赛B题:功率放大器非线性特性及预失真建模,利用数学建模的思路辨识功率放大器非线性失真行为模型并通过预畸变来减少失真.通信系统的发展需要有技术弥补功率器件的固有非线性特性,保证功率放大器的能量转换效率和线性度.随着器件的更新和信息传输速率的增加,解决此问题的数学模型—预失真算法一直在更新和发展.在研究生数模竞赛中引入此类赛题,可以开阔思维,激发研究生使用数学的兴趣,提高利用数学模型解决实际工程问题的能力,同时利用学生思维活跃的优势,提出有价值的创新点,丰富现有的算法类型,为国内相关企业研究解决此类问题提供新的思路方法,具有重要的意义.  相似文献   

6.
球面径向基函数(SBF)和多项式样条函数均为处理球面散乱数据的有效工具. 本文考虑由球面径向基函数与球面多项式函数组成的混合插值模型, 并利用最小二乘法求解该模型. 对于该插值模型, 首先, 给出带Bessel势的Sobolev空间中的Bernstein不等式, 然后利用该不等式建立逼近正定理,并进一步给出该插值工具的误差估计. 最后, 研究该插值方式(即利用最小二乘法求解混合插值模型)的稳定性.  相似文献   

7.
基于LS-SVM的管道腐蚀速率灰色组合预测模型   总被引:1,自引:0,他引:1  
为提高管道腐蚀速率预测精度,建立了一种基于最小二乘支持向量机的灰色组合预测模型.以各种灰色模型对管道腐蚀速率的预测结果作为支持向量机的输入,以管道腐蚀速率的实测值作为支持向量机的输出,采用最小二乘支持向量机回归算法和高斯核函数对支持向量机进行训练,利用训练好的支持向量机进行组合预测.预测模型兼具灰色模型所需原始数据少、建模简单、运算方便的优势和最小二乘支持向量机具有泛化能力强、非线性拟合性好、小样本等特性,弥补了单一预测模型的不足,避免了神经网络组合预测易于陷入局部最优的弱点.模型结构简单、实用,仿真结果验证了其有效性.  相似文献   

8.
本文首先给出了二维圆盘传递装置在极坐标下的药物非线性扩散最优控制模型.然后,用基于迭代法的最小二乘方法求解模型的非线性扩散方程,并估计相应的扩散系数.最后,通过一个数值算例,验证该控制模型和算法在二维圆盘传递装置中是有效的.  相似文献   

9.
偏最小二乘回归分析在均匀设计试验建模分析中的应用   总被引:14,自引:0,他引:14  
本文分析了目前应用一般的最小二乘法建立均匀试验数据的二次多项式回归模型时存在的局限性,提出了应用偏最小二乘法(Partial least-square,PLS)建立二次多项式回归模型的技术,并且进一步介绍了偏最小二乘回归(PLS回归)在均匀设计中的应用。作者认为,PLS回归分析建模技术将为均匀设计的更广泛应用提供有力的技术支持。  相似文献   

10.
对于线性系统中频响函数的估计问题,文章提出一种新的非参数辨识法-局部多项式法.与其它基于加窗策略的非参数辨识法相比较可知,在不使用周期输入激励信号下,局部多项式法在应用离散傅里叶变换时可有效地降低泄露误差的影响.将频响函数和泄露项围绕某中心频率处的窄窗展开成两个局部多项式模型,局部参数的估计可通过多个局部最小二乘问题来求解.当考虑相邻频率处多项式系数间的约束时,对局部多项式法做改进得到约束局部多项式法.改进后的约束局部多项式法通过多目标最小二乘准则来求解,并可降低频响函数估计的均方误差.最后用仿真算例验证文章辨识方法的有效性.  相似文献   

11.
In this paper we investigate penalized least squares methods in linear regression models with heteroscedastic error structure. It is demonstrated that the basic properties with respect to model selection and parameter estimation of bridge estimators, Lasso and adaptive Lasso do not change if the assumption of homoscedasticity is violated. However, these estimators do not have oracle properties in the sense of Fan and Li (2001) if the oracle is based on weighted least squares. In order to address this problem we introduce weighted penalized least squares methods and demonstrate their advantages by asymptotic theory and by means of a simulation study.  相似文献   

12.
The paper discusses recursive computation problems of the criterion functions of several least squares type parameter estimation methods for linear regression models, including the well-known recursive least squares (RLS) algorithm, the weighted RLS algorithm, the forgetting factor RLS algorithm and the finite-data-window RLS algorithm without or with a forgetting factor. The recursive computation formulas of the criterion functions are derived by using the recursive parameter estimation equations. The proposed recursive computation formulas can be extended to the estimation algorithms of the pseudo-linear regression models for equation error systems and output error systems. Finally, the simulation example is provided.  相似文献   

13.
This article is concerned with the estimating problem of semiparametric varyingcoefficient partially linear regression models. By combining the local polynomial and least squares procedures Fan and Huang (2005) proposed a profile least squares estimator for the parametric component and established its asymptotic normality. We further show that the profile least squares estimator can achieve the law of iterated logarithm. Moreover, we study the estimators of the functions characterizing the non-linear part as well as the error variance. The strong convergence rate and the law of iterated logarithm are derived for them, respectively.  相似文献   

14.
Minimum average variance estimation (MAVE, Xia et al. (2002) [29]) is an effective dimension reduction method. It requires no strong probabilistic assumptions on the predictors, and can consistently estimate the central mean subspace. It is applicable to a wide range of models, including time series. However, the least squares criterion used in MAVE will lose its efficiency when the error is not normally distributed. In this article, we propose an adaptive MAVE which can be adaptive to different error distributions. We show that the proposed estimate has the same convergence rate as the original MAVE. An EM algorithm is proposed to implement the new adaptive MAVE. Using both simulation studies and a real data analysis, we demonstrate the superior finite sample performance of the proposed approach over the existing least squares based MAVE when the error distribution is non-normal and the comparable performance when the error is normal.  相似文献   

15.
This paper proposes two permutation tests based on the least distance estimator in a multivariate regression model. One is a type of t test statistic using the bootstrap method, and the other is a type of F test statistic using the sum of distances between observed and predicted values under the full and reduced models. We conducted a simulation study to compare the power of the proposed permutation tests with that of the parametric tests based on the least squares estimator for three types of hypotheses in several error distributions. The results indicate that the power of the proposed permutation tests is greater than that of the parametric tests when the error distribution is skewed like the Wishart distribution, has a heavy tail like the Cauchy distribution, or has outliers.  相似文献   

16.
The scaled total least‐squares (STLS) method unifies the ordinary least‐squares (OLS), the total least‐squares (TLS), and the data least‐squares (DLS) methods. In this paper we perform a backward perturbation analysis of the STLS problem. This also unifies the backward perturbation analyses of the OLS, TLS and DLS problems. We derive an expression for an extended minimal backward error of the STLS problem. This is an asymptotically tight lower bound on the true minimal backward error. If the given approximate solution is close enough to the true STLS solution (as is the goal in practice), then the extended minimal backward error is in fact the minimal backward error. Since the extended minimal backward error is expensive to compute directly, we present a lower bound on it as well as an asymptotic estimate for it, both of which can be computed or estimated more efficiently. Our numerical examples suggest that the lower bound gives good order of magnitude approximations, while the asymptotic estimate is an excellent estimate. We show how to use our results to easily obtain the corresponding results for the OLS and DLS problems in the literature. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

17.
该文研究了响应变量缺失下半参数部分非线性变系数EV模型的统计推断问题,利用逆概率加权局部纠偏profile最小二乘法构造了模型中非参数分量和参数分量的估计,证明了估计量的渐近正态性.通过数值模拟和实际数据分析,验证了所提出的估计方法是有效的.  相似文献   

18.
In multiple linear regression model, we have presupposed assumptions (independence, normality, variance homogeneity and so on) on error term. When case weights are given because of variance heterogeneity, we can estimate efficiently regression parameter using weighted least squares estimator. Unfortunately, this estimator is sensitive to outliers like ordinary least squares estimator. Thus, in this paper, we proposed some statistics for detection of outliers in weighted least squares regression.  相似文献   

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