大规模MIMO系统中基于模等式约束的降维去相干DOA估计

大规模MIMO系统中存在大量相干信号,简单的去相干处理导致二维波达方向(DOA, Direction of Arrival)估计的精度较低。为此,本文提出一种能够大幅度提高相干信号二维DOA估计性能的模等式约束降维MUSIC算法。该算法将二维DOA估计问题转化为优化问题,并采用模等式约束法定义附加条件,对方向矢量施加较强的约束,使优化方程求解更接近最优解。理论分析和仿真实验结果表明,本文提出的去相干DOA算法的可靠性与精度高,满足大规模MIMO系统的DOA估计性能需求,具有较强的可行性和实用性。

Economic Dispatch with Convex and Non-Convex Fuel Cost Functions Including Line Losses Using Pattern Search

This article presents an application of generalized pattern search （PS） algorithm to solve economic load dispatch （ELD） problems with convex and non-convex fuel cost objective functions. Main objective of ELI） is to determine the most economic generating dispatch required to satisfy the predicted load demands including line losses. Relaxing various equality and inequality constraints are considered. The unit operation minhnum/maximum constraints, effects of valve-point and line losses are considered for the practical applications. Several case studies were tested and verified, which indicate an improvement in total fuel cost savings. The robustness of the proposed PS method have been assessed and investigated through intensive comparisons with reported results in recent researches. The results are very encouraging and suggesting that PS may be very useful tool in solving power system ELD problems.

TESTING INEQUALITY CONSTRAINTS IN A LINEAR REGRESSION MODEL WITH SPHERICALLY SYMMETRIC DISTURBANCES

This paper develops a Wald statistic for testing the validity of multivariate inequality constraints in linear regression models with spherically symmetric disturbances,and derive the distributions of the test statistic under null and nonnull hypotheses.The power of the test is then discussed.Numerical evaluations are also carried out to examine the power performances of the test for the case in which errors follow a multivariate student-t(Mt) distribution.

GEOMETRIC ERROR CONTROL IN THE PARABOLA-BLENDING LINEAR INTERPOLATOR

This paper considers geometric error control in the parabola-blending linear interpolation method(Zhang,et al.,2011).Classical model of chord error by approximation with contact circle on the parabolas leads to incorrect result.By computing the geometric error directly without accumulating the approximation error and chord error,the authors realize correct geometric error control by establishing inequality constraints on the accelerations of the motion.

Model updating based on incomplete modal data

The objective of model updating is to improve the accuracy of a dynamic model based on the correlation between the measured data and the analytical (finite element) model. In this paper, we intend to update the mass and stiffness matrices of an analytical model when only modal frequencies or spatially incomplete modal data are available. While the proposed method is systematic in nature, it also preserves the initial configuration of the analytical model, and physical equality and/or inequality constraints can be easily incorporated into the solution procedure. Numerical examples associated with a simple 5-DoF (degree of freedom) mass-spring system are chosen to illustrate the detailed procedure and the effectiveness of the proposed method. Numerical scenarios ranging from the updating for stiffness terms only to that for all mass and stiffness terms based on various kinds of incomplete modal data are studied. The obtained model updating results are excellent when the measured modal data are noise-free. Uncertainty studies are also conducted based on simulations of corrupted modal data, but a thorough theoretical analysis of the noise effect on the proposed method is still needed.

A NOTE ON THE PROPERTIES OF STEIN-RULE AND INEQUALITY RESTRICTED ESTIMATORS WHEN THE REGRESSION MODEL IS OVER-FITTED

This paper considers the effect of an erroneous inclusion of regressors on the risk propertiesof the Stein-rule,positive-part Stein-rule and inequality restricted and pre-test estimators in a linearregression model.The two Stein-rule estimators are considered when extraneous information is availablein the form of a set of multiple equality constraints on the coefficients,while the inequality estimatorsare considered under the case of a single inequality constraint.It is shown that the inclusion ofwrong regressors has only minimal effect on the properties of the Stein-rule and positive-part Stein-ruleestimators,and no effect at all on the inequality restricted and pre-test estimators when there is asingle inequality constraint.