Kefei Liu

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a r t i c l e i n f o a b s t r a c t Estimation of the number of signals impinging on an array of sensors, also known as source enumeration, is usually required prior to direction-of-arrival (DOA) estimation. In challenging scenarios such as the presence of closely-spaced sources and/or high level of noise, using the true source number for nonlinear(More)
A novel R-dimensional (R ≥ 3) model order selection (MOS) criterion is proposed for estimating the number of sources embedded in noise. By extending the classical r-mode matrix unfolding of a Rth-order measurement tensor to multi-mode matrix unfolding, (2 R−1 − 1) unfolded matrices are obtained. To maximize the iden-tifiability, the unfolded matrix whose(More)
Both theoretical and experimental studies suggest that response properties in the visual system are shaped by signals in the natural environment. Recent studies showed that, in the primary visual cortex (V1), neurons preferring light decrements (OFF stimuli) outnumber those preferring light increments (ON stimuli). However, it is not clear whether the(More)
R-dimensional (R-D) harmonic retrieval (HR) in colored noise, where R Z 2, is required in numerous applications including radar, sonar, mobile communications, multiple-input multiple-output channel estimation and nuclear magnetic resonance spectroscopy. Tensor-based subspace approaches to R-D HR such as R-D unitary ESPRIT and R-D MUSIC provide(More)
This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Abstract—Subspace-based high-resolution algorithms for direction-of-arrival estimation have been developed for large-scale adaptive antenna arrays. However, its prerequisite step, namely, source(More)
—Eigenvalue-based methods have been widely investigated for multiantenna blind spectrum sensing in cognitive radio (CR). However, most of them are formulated in the framework of maximum likelihood (ML) estimation, which is optimal only when the number of samples is much larger than the number of antennas. In relatively small-sample scenarios where the(More)
The responses of visual cortical neurons to natural stimuli are both reliable and sparse. These properties require inhibition, yet the contribution of specific types of inhibitory neurons is not well understood. Here we demonstrate that optogenetic suppression of parvalbumin (PV)- but not somatostatin (SOM)-expressing interneurons reduces response(More)