Spatiotemporal non-uniformly correlated beams

We present a new partially coherent source with spatiotemporal coupling. The stochastic light, which we call a spatiotemporal (ST) non-uniformly correlated (NUC) beam, combines space and time in an inhomogeneous (shift- or space-variant) correlation function. This results in a source that self-focuses at a controllable location in space-time, making these beams potentially useful in applications such as optical trapping, optical tweezing, and particle manipulation. We begin by developing the mutual coherence function for an ST NUC beam. We then examine its free-space propagation characteristics by deriving an expression for the mean intensity at any plane $$z \ge 0$$ z ≥ 0 . To validate the theoretical work, we perform Monte Carlo simulations, in which we generate statistically independent ST NUC beam realizations and compare the sample statistical moments to the corresponding theory. We observe excellent agreement amongst the results.

Two-Dimensional DOA Estimation of MIMO Radar Coherent Source Based on Toeplitz Matrix Set Reconstruction

In order to realize the high-precision direction of arrival (DOA) estimation of the coherent source of two-dimensional multiple-input and multiple-output (MIMO) radar, a solution is given by combining Toeplitz matrix set reconstruction. MIMO radar obtains a larger aperture with fewer arrays. Traditional two-dimensional reconstruction Toeplitz-like algorithms use part of the information in the construction of two correlation matrices or covariance matrices to construct the Toeplitz matrix when performing two-dimensional coherent source DOA estimation, which makes the information utilization incomplete and requires additional denoising processing. To solve the above problems, this paper proposes an improved Toeplitz matrix set reconstruction algorithm based on the two-dimensional reconstruction Toeplitz class algorithm. The complete array element receiving signal vector is used to construct two Toeplitz matrix sets containing complete information, and then their conjugate transposes. Multiply and sum to correct the matrix to obtain a full-rank matrix, so as to achieve the purpose of decoherence and combine the traditional ESPRIT algorithm to perform two one-dimensional reconstruction processing through rotation invariance and then perform angle matching to achieve two-dimensional coherent signal angle estimation, while avoiding additional denoising processing. Finally, the simulation results of the cross array and the L-shaped array verify the effectiveness of the algorithm in this paper and further extend it to the two-dimensional MIMO radar array model and compare it with the traditional ESPRIT-like algorithm and the REC-FBSS-ESPRIT algorithm. In comparison, the algorithm in this paper has better performance under the conditions of successful resolution, DOA estimation accuracy, and low signal-to-noise ratio.

Sculptures and Accessories: Domestic Piety in the Norwegian Parish around 1300

Eagerly venerated and able to perform miracles, medieval relics and religious artefacts in the Latin West would occasionally also be subject to sensorial and tactile devotional practices. Evidenced by various reports, artefacts were grasped and stroked, kissed and tasted, carried and pulled. For medieval Norway, however, there is very little documentary and/or physical evidence of such sensorial engagements with religious artefacts. Nevertheless, two church inventories for the parish churches in Hålandsdalen (1306) and Ylmheim (1321/1323) offer a small glimpse of what may have been a semi-domestic devotional practice related to sculpture, namely the embellishing of wooden sculptures in parish churches with silver bracelets and silver brooches. According to wills from England and the continent, jewellery was a common material gift donated to parishes by women. Such a practice is likely to have been taking place in Norway, too, yet the lack of coherent source material complicate the matter. Nonetheless, using a few preserved objects and archaeological finds as well as medieval sermons, homiletic texts and events recorded in Old Norse sagas, this article teases out more of the significances of the silver items mentioned in the two inventories by exploring the interfaces between devotional acts, decorative needs, and possibly gendered experiences, as well as object itineraries between the domestic and the religious space.

A Sparse Representation Method for Coherent Sources Angle Estimation with Uniform Circular Array

Coherent source localization is a common problem in signal processing. In this paper, a sparse representation method is considered to deal with two-dimensional (2D) direction of arrival (DOA) estimation for coherent sources with a uniform circular array (UCA). Considering that objective function requires sparsity in the spatial dimension but does not require sparsity in time, singular value decomposition (SVD) is employed to reduce computational complexity and ℓ2 norm is utilized to renew objective function. After the new objective function is constructed to evaluate residual and sparsity, a second-order cone (SOC) programming is employed to solve convex optimization problem and obtain 2D spatial spectrum. Simulations show that the proposed method can deal with the case of coherent source localization, which has higher resolution than 2D MUSIC method and does not need to estimate the number of coherent sources in advance.