Semi-active noise suppression based on SSD technique using piezoelectric elements

ABSTRACT Noise suppression using piezoelectric elements has received extensive attention in recent years. Traditional active noise control methods usually require the use of microphones as sensors to directly measure the sound pressure in either feed-forward or feedback control schemes. This makes the traditional active noise isolation more difficult to implement in some practical applications. Nonlinear semi-active Synchronized Switch Damping (SSD) approaches are typical switched-voltage control methods, which have recently been a topic of active research in the field of vibration control. In this paper, SSD method is proposed for the suppression of noise transmission through an aluminum panel. In a typical SSD setting, microphones are not required for feedback control, but are used merely as sensors to evaluate the control performance. The layout of the piezoelectric elements on the panel has been optimized based on the mode shape dominating the noise radiation. SSDV (SSD based on voltage sources) was used to improve the control performance. Experimental results show that the proposed control approach exhibits good performance in suppressing noise transmission

Real-Time Stereo Matching Network Based on 3D Channel and Disparity Attention for Edge Devices Toward Autonomous Driving

Stereo matching is an important component technology that constitutes the 3D perception capability of autonomous vehicles. On resource-constrained edge devices, it is very important to compute in real-time with very low time. However, most stereo matching networks focus on generating disparity maps on high-end GPUs, which do not meet the real-time requirements on edge devices. To solve this problem, a new stereo matching network is proposed in this paper to achieve real-time stereo matching on edge devices. The proposed network greatly improves the inference speed by constructing a low-resolution feature extractor, and by using multi-stage residual methods for stereo matching. In particular, we propose a method that combines the group-wise L1 distance & the group-wise correlation cost volume and an effective attention-based 3D cost aggregation method. Our network achieves a good balance between speed and accuracy on the KITTI 2012 and KITTI 2015 datasets. The proposed network achieves 2.77% and 3.44% accuracy (D1-all) on KITTI 2012 and KITTI 2015, respectively. With TensorRT, the proposed network achieves 31.8 FPS and outperforms the real-time results of most state-of-the-art networks on NVIDIA Jetson Nano edge devices

Detecting Rock Glacier Displacement in the Central Himalayas Using Multi-Temporal InSAR

Rock glaciers represent typical periglacial landscapes and are distributed widely in alpine mountain environments. Rock glacier activity represents a critical indicator of water reserves state, permafrost distribution, and landslide disaster susceptibility. The dynamics of rock glacier activity in alpine periglacial environments are poorly quantified, especially in the central Himalayas. Multi-temporal Interferometric Synthetic Aperture Radar (MT-InSAR) has been shown to be a useful technique for rock glacier deformation detection. In this study, we developed a multi-baseline persistent scatterer (PS) and distributed scatterer (DS) combined MT-InSAR method to monitor the activity of rock glaciers in the central Himalayas. In periglacial landforms, the application of the PS interferometry (PSI) method is restricted by insufficient PS due to large temporal baseline intervals and temporal decorrelation, which hinder comprehensive measurements of rock glaciers. Thus, we first evaluated the rock glacier interferometric coherence of all possible interferometric combinations and determined a multi-baseline network based on rock glacier coherence; then, we constructed a Delaunay triangulation network (DTN) by exploiting both PS and DS points. To improve the robustness of deformation parameters estimation in the DTN, we combined the Nelder–Mead algorithm with the M-estimator method to estimate the deformation rate variation at the arcs of the DTN and introduced a ridge-estimator-based weighted least square (WLR) method for the inversion of the deformation rate from the deformation rate variation. We applied our method to Sentinel-1A ascending and descending geometry data (May 2018 to January 2019) and obtained measurements of rock glacier deformation for 4327 rock glaciers over the central Himalayas, at least more than 15% detecting with single geometry data. The line-of-sight (LOS) deformation of rock glaciers in the central Himalayas ranged from −150 mm to 150 mm. We classified the active deformation area (ADA) of all individual rock glaciers with the threshold determined by the standard deviation of the deformation map. The results show that 49% of the detected rock glaciers (monitoring rate greater than 30%) are highly active, with an ADA ratio greater than 10%. After projecting the LOS deformation to the steep slope direction and classifying the rock glacier activity following the IPA Action Group guideline, 12% of the identified rock glaciers were classified as active and 86% were classified as transitional. This research is the first multi-baseline, PS, and DS network-based MT-InSAR method applied to detecting large-scale rock glaciers activity

Sedimentary architecture and distribution of intra-platform shoal in sequence framework of Permian Changxing Formation in central Sichuan Basin, SW China

Based on the comprehensive analysis of core, thin section, logging and seismic data, this study carried out the identification and comparison of Permian Changxing Formation sequences, clarified the typical sedimentary architectures of intra-platform shoal, investigated the vertical and horizontal development and distribution of intra-platform shoal in each sequence, and thus established the sedimentary evolution model of shoal body. The study results are reflected in four aspects. First, there are two complete third-order sequences (SQ1 and SQ2) in Changxing Formation in central Sichuan Basin. SQ1 is generally thick in the north and thin in the south, and SQ2 shows a thickness differentiation trend of “two thicknesses and three thinnesses”. Second, the Changxing Formation in central Sichuan Basin mainly develops intra-platform shoal, inter-shoal sea and intra-platform depression subfacies. In the vertical direction, the intra-platform shoal mainly presents two typical sedimentary sequences: stable superposed and high-frequency interbedded. Third, the stable superimposed sedimentary sequence is developed in the shoal belt at the edge of intra-platform depression, which is composed of two shoal-forming periods and located in the highstand systems tracts (HSTs) of SQ1 and SQ2. The high-frequency interbedded sedimentary sequence is developed in the southern shoal belt of intra-platform depression, which is composed of four shoal-forming periods and mainly located in the HST of SQ2. Fourth, during the SQ1 deposition, the intra-platform shoal was mainly developed at the edge of the intra-platform depression on the north side of the study area, and the inter-shoal sea subfacies was mainly developed on the south side. During the SQ2 deposition, the intra-platform shoal was widely developed in the area, forming two nearly parallel intra-platform shoal belts. The study results provide direction and ideas for exploration of Changxing Formation intra-platform shoal reservoirs in central Sichuan Basin

Damage evaluation based on a wave energy flow map using multiple PZT sensors

A new wave energy flow (WEF) map concept was proposed in this work. Based on it, an improved technique incorporating the laser scanning method and Betti’s reciprocal theorem was developed to evaluate the shape and size of damage as well as to realize visualization of wave propagation. In this technique, a simple signal processing algorithm was proposed to construct the WEF map when waves propagate through an inspection region, and multiple lead zirconate titanate (PZT) sensors were employed to improve inspection reliability. Various damages in aluminum and carbon fiber reinforced plastic laminated plates were experimentally and numerically evaluated to validate this technique. The results show that it can effectively evaluate the shape and size of damage from wave field variations around the damage in the WEF map