Time reversal (T) invariant topological insulator is widely recognized as one of the fundamental discoveries in condensed matter physics, for which most fascinating hallmark perhaps a spin based protection, total cancellation scattering conduction electrons with certain spins on surface. Recently, it has created paradigm shift insulators, from electronics to photonics, phononics well mechanics, bringing about not only involved new physics but also potential applications robust wave...

The problem of direction-of-arrival (DOA) estimation for sparse array is addressed. perspective that DOA in virtual response model can be cast as the recovery introduced. Two methods are proposed, based on different optimization problems, which solvable using second-order cone (SOC) programming. Without knowledge number sources, proposed yield superior performances, verified by numerical simulations.

Despite a long history of studies, acoustic waves are generally regarded as spinless scalar waves, until recent research revealed their rich structures. Here, we report the experimental observation skyrmion configurations in waves. We find that surface trapped by designed hexagonal metasurface give rise to lattice patterns dynamic velocity fields (i.e., oscillating air flows). Using an sensing technique, directly visualize Néel-type configuration fields. further demonstrate, respectively,...

Based on vibration signals detected by a phase-sensitive optical time-domain reflectometer distributed fiber sensing system, this paper presents an implement of time-frequency analysis and convolutional neural network (CNN), used to classify different types vibrational events. First, spectral subtraction the short-time Fourier transform are enhance features into spectrograms, which input CNN for automatic feature extraction classification. Finally, replacing soft-max layer in with multiclass...

Abstract A new multifeature recognition method for optical fiber vibration signals is proposed to solve the difficulty with present long‐distance distributed sensing systems based on phase‐sensitive time‐domain reflectometer (φ‐OTDR) in effectively distinguishing vibrational intrusions. Firstly, wide‐band background noise reduced by spectral subtraction enhance time‐frequency characteristics of signals. Then, parameters including short‐time energy ratio, level crossing rate, duration, and...

A one-bit joint sparse representation direction of arrival (OBJSR-DOA) estimation approach is proposed in this letter. By exploiting the spatial and spectral correlations inherent acoustic sensor array data, OBJSR-DOA provides reliable DOA from only sign bit randomly subsampled data. The random subsampling single-bit quantization allow significant reduction data to be transmitted fusion center without additional energy consumption requirement source coding/compression operation. Compared...

Understanding unidirectional and topological wave phenomena requires the unveiling of intrinsic geometry symmetry for dynamics. This is essential yet challenging flexible control near-field evanescent waves, highly desirable in broad practical scenarios ranging from information communication to energy radiation. However, exploitations waves are limited by a lack fundamental understanding about inherent directional coupling at sub-wavelengths, especially longitudinal waves. Here, based on...

In this paper, we present a generalized iterated Kalman filter (GIKF) algorithm for state estimation of nonlinear stochastic discrete-time system with state-dependent multiplicative observation noise. The GIKF adopts the Newton-Raphson iterative optimization steps to yield an approximate maximum posteriori estimate states. mean-square error (MSE) and Cramér-Rao lower bound (CRLB) estimates are also derived. particular, local convergence MSE is rigorously established. It proved that yields...

In this paper, a rigid surface decorated with an array of grooves graded widths is proposed to get spatial separation the spoof acoustic waves. Because intermodal coupling between forward and backward modes on structure, waves different frequencies stop propagating ahead reflect back at positions groove grating. The intensity field effectively enhanced near propagation-stop position due slow group velocity. We believe that such system capability energy concentration wave arrangement by has...

We demonstrate that acoustic subwavelength imaging can be realized through the spoof surface waves on phononic crystal which is composed of borehole arrays with square lattice in a rigid plate. The dispersion property two-dimensional textured plate analyzed theoretically. By utilizing broad flat equifrequency contour waves, image full width at half maximum 0.14 λ has been obtained both numerically and experimentally. believe such work bring potential applications design focusing devices.

In order to improve the angular resolution of direction-of-arrival (DOA) estimation based on portable microphone at low signal-noise-ratio (SNR), this paper proposes a new high-resolution DOA algorithm single acoustic vector sensor (AVS), namely Virtual-AVS algorithm. The innovative is mainly composed two parts: preprocessing method and with ambiguity elimination. implemented higher-order cumulants Gaussian noise suppression characteristic. This not only suppress effectively enhance SNR, but...

For direction-of-arrival (DOA) estimation of heterogeneous wideband sources, we propose a new adaptive space-frequency joint processing algorithm. The algorithm is implemented in the sparse Bayesian learning (SBL) DOA framework, which named as ASF-SBL this paper. traditional SBL-based methods suffer from problem erroneous due to structural mismatch between invariant prior and coefficients. To solve problem, employs correlation model that can be adaptively changed fit scenarios. Specifically,...

An acoustic-signature based method of estimating the flight trajectory low-altitude flying aircraft that only requires a stationary microphone array is proposed. This leverages Doppler shifts engine sound to estimate closest point approach distance, time, and speed. It also acoustic phase shift over direction arrival target. Combining these parameters, this algorithm provides total least square target under assumption constant height, direction, Analytical bounds potential performance...

A new CNN-based deep neural network, multi-scale one-dimensional convolutional network (MS 1-D CNN) was proposed to improve the efficiency and accuracy of vibration event recognition for a phase-sensitive optical time-domain reflectometry (Φ-OTDR) distributed fiber sensing system. The raw signals are pre-processed first remove noise as far possible. pre-processing operations include pre-emphasis filtering, normalization spectral subtraction. used inputs MS CNN directly. realizes end-to-end...

Moving target tracking in directional sensor networks has recently attracted attention by right of special sensing features. Unlike omnidirectional sensors, the senses only direction its orientation. It can provide quantized that indicates presence or absence field, rather than just analog measurement signal with respect to detected target. A Kalman filter (QKF) based on both directions and ranging measurements is derived minimum mean-square error (MMSE) sense. Its performances mean square...

The distributed fiber optic system based on phase-sensitive optical-time-domain reflectometry (Φ -OTDR) has attracted extensive interest in the field of perimeter security. However, noise caused by environmental factors signal processing is a great difficulty due to complexity and variability natural environment. In this paper, an improved wavelet de-noising method classification error training data proposed solve filtering thresholds selection. By maximizing true positive rates under...

This paper presents a new direction-of-arrival (DOA) estimation method using the concept of sparse representation an array cross-correlation vector (ACCV), in which DOA is achieved by finding parameter according to optimization criterion. Compared with other recovery algorithms proposed achieves higher resolution and has less computational complexity. The performance our demonstrated analyzed through numerical simulations.

An equivalent fluid model based finite-difference time-domain algorithm is proposed to simulate the frequency characteristic of porous material with rigid frame. The rigid-frame replaced by an characterized effective density and bulk modulus, which reflect viscous effects thermal in material, respectively. modulus are frequency-dependent complex values, designed form infinite impulse response filters domain. Z transform theory used discretize frequency-domain wave equations. accuracy...

An equivalent analog circuit is designed to mimic the coupled ears of fly Ormia ochracea for sound source localization. This receives two signals with tiny phase difference from a space closed two-microphone array, and produces obvious intensity difference. The response sensitivity can be adjusted through parameters. directional characteristics have been demonstrated in experiment. miniature microphone array localize low computational burden by using system has significant advantages various...

Whittaker-Shannon interpolation formula instead of narrowband filter (NF) is used to interpolate the signal more precisely in wideband direction-of-arrival (DOA) estimation problem when number samples highly limited. A novel algorithm named block FOCal Underdetermined System Solver (BFOCUSS) proposed solve this problem. The simulation results validate superior performance compared with other algorithms.

Acoustic signatures of aircraft engine and propeller noise are investigated in the context target tracking. Harmonics spectrograms light airplanes collected by a stationary microphone array on ground analyzed. Using model Doppler frequency shifts, speed height may be estimated from spectrogram recorded acoustic signal. These initial results highlight potential using for precision moving detection