Knowledge-Aided Covariance Matrix Estimation via Kronecker Product Expansions for Airborne STAP
This letter proposes a new approach for knowledge-aided estimation of structured clutter covariance matrices (CCMs) in airborne radar systems with limited training data. First, we model the CCM in space–time adaptive processing (STAP) as a sum of low-rank Kronecker products. We then apply a permutation operation to convert the Kronecker factors into linear structures and propose a novel CCM estimation method under the maximum-likelihood framework. Employing a proximal gradient algorithm, the proposed method simultaneously exploits the knowledge about the clutter and the Kronecker structure of the CCM. We finally evaluate the performance of the proposed method using real data from airborne STAP.
Channel Covariance Matrix Estimation via Dimension Reduction for Hybrid MIMO MmWave Communication Systems
Hybrid massive MIMO structures with lower hardware complexity and power consumption have been considered as potential candidates for millimeter wave (mmWave) communications. Channel covariance information can be used for designing transmitter precoders, receiver combiners, channel estimators, etc. However, hybrid structures allow only a lower-dimensional signal to be observed, which adds difficulties for channel covariance matrix estimation. In this paper, we formulate the channel covariance estimation as a structured low-rank matrix sensing problem via Kronecker product expansion and use a low-complexity algorithm to solve this problem. Numerical results with uniform linear arrays (ULA) and uniform squared planar arrays (USPA) are provided to demonstrate the effectiveness of our proposed method.
The alcohol-aggression stereotype: a cross-cultural comparison of beliefs.
University students (N = 1,008) in eight countries participated in a survey aimed at mapping cross-cultural alcohol expectancies. Multisample structured means analysis was applied to compare changes in aggressive behaviors believed to occur in connection with drinking after "many" alcoholic drinks. Most subjects expressed the belief that intoxication was associated with greater aggressiveness, but there were significant national differences unrelated to self-reported alcoholic beverage preference, frequency of drinking to intoxication, or rates of personal involvement in episodes of alcohol-related aggression. Thus, the expectation that drinking leads to aggression may be determined to a significant extent by contextual factors and cultural traditions related to alcohol use.