Search Results (169)

Due to its fast processing time and robustness against harsh environmental conditions, the frequency modulated continuous waveform (FMCW) multiple-input multiple-output (MIMO) radar is widely used for target localization. For high-accuracy localization, the two-dimensional multiple signal classification (2D MUSIC) algorithm can be applied to signals received by a single FMCW MIMO radar, achieving high-resolution positioning performance. To further enhance estimation accuracy, received signals or MUSIC spectra from multiple FMCW MIMO radars are often collected at a data fusion center and processed coherently. However, this approach increases data communication overhead and implementation complexity. To address these challenges, we propose an efficient high-resolution target localization algorithm. In the proposed method, the target position estimates from multiple FMCW MIMO radars are collected and combined using a weighted averaging approach to determine the target’s position within a unified coordinate system at the data fusion center. We first analyze the achievable resolution in the unified coordinate system, considering the impact of local parameter estimation errors. Based on this analysis, weights are assigned according to the achievable resolution within the unified coordinate framework. Notably, due to the typically limited number of antennas in FMCW MIMO radars, the azimuth angle resolution tends to be relatively lower than the range resolution. As a result, the achievable resolution in the unified coordinate system depends on the placement of each FMCW MIMO radar. The performance of the proposed scheme is validated using both synthetic simulation data and experimentally measured data, demonstrating its effectiveness in real-world scenarios. Full article

This article presents a Synthetic-Aperture Distributed Phased Array (SADPA) framework to address emitter localization challenges in dynamic environments. Building on Distributed Synthetic-Aperture Radar (DSAR) principles, SADPA integrates distributed phased arrays with motion-induced phase compensation, enabling coherent aperture synthesis beyond physical array limits. By analytically modeling and compensating nonlinear phase variations caused by platform motion, we resolve critical barriers to signal integration while extending synthetic apertures. An improved MUSIC algorithm jointly estimates emitter positions and phase distortions, overcoming parameter coupling inherent in moving systems. To quantify fundamental performance limits, the Cramer–Rao bound (CRB) is derived as a theoretical benchmark. Numerical simulations demonstrate the SADPA framework’s superior performance in multi-source resolution and positioning accuracy; it achieves 0.012 m resolution at 10 GHz for emitters spaced 0.01 m apart. The system maintains consistent coherent gain exceeding 30 dB across both the 1.5 GHz communication and 10 GHz radar bands. Monte Carlo simulations further reveal that the MUSIC-DPD algorithm within the SADPA framework attains minimum positioning error (RMSE), with experimental results closely approaching the theoretical CRB. Full article

The percentage of historical heritage buildings in Italy is substantial. Many of these buildings are abandoned or not adequately restored for public access due to safety concerns. However, some are managed by city councils and made available to local communities. These heritage buildings, valued for their historical significance, are now frequently used for live events, including musical performances by ensembles and small groups. This paper deals with the acoustics of two rooms provided with barrel-vaulted ceilings: Sisto V Hall in Naples and Aula Magna at the University of Parma. These spaces are structurally very similar, differing mainly in length. Acoustic measurements conducted in both halls reveal reverberation times of approximately 4.5 s at mid frequencies, resulting in poor speech clarity. This is primarily due to the presence of reflective surfaces, as the walls and ceilings are plastered, and the floors are tiled. To optimize their acoustic properties for functions such as celebrations, gatherings, and conferences, an acoustic design intervention was proposed. Digital models of the halls were calibrated and used to correct the acoustics by incorporating absorbing panels on the walls and carpeting on the floors of the central walk path. This treatment successfully balanced the reverberation time to approximately 1.3–1.4 s at mid frequencies, making speech more intelligible. Additionally, an amplified audio system was analyzed to enhance sound distribution, ensuring uniform coverage, even in the last rows of seating. Under amplified conditions, sound pressure levels (SPLs) range between 90 dB and 93 dB, with appropriate gain control applied to the column array speakers. Full article

Lightning Very-High-Frequency (VHF) radiation source mapping technology represents a pivotal advancement in the study of lightning discharge processes and their underlying physical mechanisms. This paper introduces a novel methodology for reconstructing lightning discharge channels by employing the Multiple Signal Classification (MUSIC) algorithm to estimate the Direction of Arrival (DOA) of lightning VHF radiation sources, specifically tailored for both non-uniform and uniform L-shaped arrays (2D-MUSIC). The proposed approach integrates the Random Sample Consensus (RANSAC) algorithm with 2D-MUSIC, thereby enhancing the precision and robustness of the reconstruction process. Initially, the array data are subjected to denoising via the Ensemble Empirical Mode Decomposition (EEMD) algorithm. Following this, the covariance matrix of the processed array data is decomposed to isolate the signal subspace, which corresponds to the signal components, and the noise subspace, which is orthogonal to the signal components. By exploiting the orthogonality between these subspaces, the method achieves an accurate estimation of the signal incidence direction, thereby facilitating the precise reconstruction of the lightning channel. To validate the feasibility of this method, comprehensive numerical simulations were conducted, revealing remarkable accuracy with elevation and azimuth angle errors both maintained below 1 degree. Furthermore, VHF non-uniform and uniform L-shaped lightning observation systems were established and deployed to analyze real lightning events occurring in 2021 and 2023. The empirical results demonstrate that the proposed method effectively reconstructs lightning channel structures across diverse L-shaped array configurations. This innovative approach significantly augments the capabilities of various broadband VHF arrays in radiation source imaging and makes a substantial contribution to the study of lightning development processes. The findings of this study underscore the potential of the proposed methodology to advance our understanding of lightning dynamics and enhance the accuracy of lightning channel reconstruction. Full article

This study investigates the vibrational and acoustic properties of Sitka spruce (Picea sitchensis (Bong.) Carr.) and Indian rosewood (Dalbergia latifolia Roxb.), two common musical instrument woods, at moisture contents of 2%, 7%, and 12%. The specimens with dimensions of 400mm (longitudinal) × 25 mm (radial) × 10 mm (tangential) were tested under cantilever beam conditions using non-contact magnetic field excitation to generate sinusoidal and pulse signals. Vibration data were collected via acceleration sensors and FFT analyzers. The test method was based on ASTM D6874-12 standard. Results indicate that increasing moisture content reduces acoustic vibration characteristics, with hardwoods exhibiting higher declines than softwoods. From 2% to 12% moisture content, the first-order sound radiation quality factor of Sitka spruce and Indian rosewood decreased by 15.41% and 15.57%, respectively, while the sound conversion rate declined by 41.91% and 43.21%. Increased moisture content lowers first-order and second-order resonance frequencies, amplitude ratios, dynamic elastic modulus, vibration propagation velocity, acoustic radiation quality factor, and acoustic conversion efficiency, while increasing acoustic impedance and the loss factor. With excitation frequency increases from 100 Hz to 1500 Hz, vibration propagation velocity rises slightly, while the loss factor declines. Full article

Acoustic temperature measurement (ATM) and sound source localization (SSL) are two important applications of acoustic sensors. The development of novel acoustic sensors capable of both ATM and SSL is an innovative research topic with great interest. In this work, an acoustic Fabry-Perot resonance detector (AFPRD) and its cross-shaped array were designed and fabricated, and the passive ATM function of the AFPRD and the SSL capability of the AFPRD array were simulated and experimentally verified. The AFPRD consists of an acoustic waveguide and a microphone with its head inserted into the waveguide, which can significantly enhance the microphone’s sensitivity via the FP resonance effect. As a result, the frequency response curve of AFPRD can be easily measured using weak ambient white noise. Based on the measured frequency response curve, the linear relationship between the resonant frequency and the resonant mode order of the AFPRD can be determined, the slope of which can be used to calculate the ambient sound velocity and air temperature. The AFPRD array was prepared by using four bent acoustic waveguides to expand the array aperture, which combined with the multiple signal classification (MUSIC) algorithm can be used for distant multi-target localization. The SSL accuracy can be improved by substituting the sound speed measured in real time into the MUSIC algorithm. The AFPRD’s passive ATM function was verified in an anechoic room with white noise as low as 17 dB, and the ATM accuracy reached 0.4 °C. The SSL function of the AFPRD array was demonstrated in the outdoor environment, and the SSL error of the acoustic target with a sound pressure of 35 mPa was less than 1.2°. The findings open up a new avenue for the development of multifunctional acoustic detection devices and systems. Full article

Under wideband interference conditions, traditional neural networks often suffer from low accuracy in single-frequency direction-of-arrival (DOA) estimation and face challenges in detecting single-frequency sound sources. To address this limitation, we propose a novel model called Parallel Net. The architecture adopts a frequency-parallel design: it first employs a recurrent neural network, the generalized feedback gated recurrent unit (GFGRU), to independently extract features from each frequency component, and then it fuses these features through an attention mechanism. This design significantly enhances the network’s capability in estimating the DOA of single-frequency signals. The simulation results demonstrate that when the signal-to-noise ratio (SNR) exceeds −10 dB, Parallel Net achieves a mean absolute error (MAE) below 2°, outperforming traditional frequency-coherent neural networks and the MUSIC algorithm, and reduces the error to half that of classical beamforming (CBF). Further validation on the SWellEx-96 experiment confirms the model’s effectiveness in detecting single-frequency sources under wideband interference. Parallel Net exhibits superior sidelobe suppression and fewer spurious peaks compared to CBF, achieves higher accuracy than MUSIC, and produces smoother and more continuous DOA trajectories than conventional neural network models. Full article

The Direction-of-Arrival (DOA) estimation method using traditional array antennas cannot dynamically adjust the observation angle range based on the Region of Interest (ROI), which leads to limited estimation accuracy and high computational complexity. To address the above issue, this paper proposes a Beamspace Spatial Smoothing MUltiple SIgnal Classification (BSS-MUSIC) DOA estimation method using a Dynamic Metasurface Antenna (DMA). Specifically, we propose a new DMA model with a single RF chain and exploit its flexibility to design a time-division data reception scheme. Based on this scheme, we dynamically select the ROI and increase the beam density in the ROI with an appropriate number of beam patterns. Next, a BSS algorithm is proposed to decohere the multipath signals in beamspace without reverting to the element space. Subsequently, we convert the 2D DOA estimation into two 1D beamspace MUSIC DOA estimations. After pairing the elevation and azimuth angles, the complex gains of each path are derived. Simulation results show that the proposed method can achieve higher estimation accuracy with lower computational complexity. Full article

The attenuation of resonant frequencies across the entire spectrum of an audio signal is important because it helps to eliminate the harshness, sibilance, clear muddiness, boominess, and proximity effect of any sound source. This paper presents a method for the attenuation of resonant frequencies across the entire spectrum of an audio signal. A spectrum obtained by the Fast Fourier Transform is segmented into bands—one-third octave bands and Equivalent Rectangular Bandwidth-scale bands—in order to obtain the maximum value per band. Additionally, a curve representing the general shape of the spectrum is generated using the standard deviation to create a threshold curve for detecting resonant frequencies. The array with maximum values per bands and the array with the threshold curve are used to detect the resonant frequencies and calculate the attenuation for each filter. Subsequently, the coefficients of a second-order section of IIR-Peak filters are calculated for processing the input signal. Twenty audio files from different sources are utilized to test the algorithm. The output produced is then compared to that produced by the commercially available Soothe2 and RESO plug-ins. The Root Mean Square Level and the Loudness Units Full Scale integrated metrics are reported. The proposed plug-in output is more attenuated than the output from commercial plug-ins under factory conditions. The average RMS attenuation is −2.32 dBFS, while Soothe2 and RESO exhibit −1.27 dBFS and −1.10 dBFS, respectively. The attenuation per octave band over time is calculated using the Wavelet Transform. Finally, an annotator agreement used as a subjective result is made with 40 people related to audio and music in order to verify if the attenuation generated by the present work at resonant frequencies agrees with subjective opinion. The octave band analysis and annotator agreement show that the proposed plug-in performs better on audio from vocal, percussion, and guitar ensembles. Full article

Music as an environmental factor can maintain intestinal health in animals, but it is unclear whether this effect is influenced by the tones of the music. In this study, 100 Kunming white mice were randomly divided into control group (C group) with no music, and three music groups were exposed to Mozart K.448 in D, A and G tone (D group, A group and G group), respectively. To study the effects of different tones of Mozart K.448 on intestinal barrier and intestinal microbiota, mice were given musical stimulation from 1 to 63 days of age. The results showed that no apparent abnormalities were observed in the structure of ileum among groups. The mRNA expression levels of genes related to intestinal physical barrier (Claudin-1, Claudin-12, ZO-2, Mucin2, ZO-1 and Claudin-5) were significantly higher in music groups than those in C group (p < 0.05), and the mRNA expression levels of intestinal barrier genes in D group were the highest (p < 0.05). The levels of intestinal mucosal permeability (DAO and D-lactate) in D group were significantly lower than those in other groups (p < 0.05). Ileum HSP60 mRNA level in D group were significantly lower than that in other groups (p < 0.05). The mRNA expression level of IgA was significantly higher in music groups than C group (p < 0.05). Additionally, the mRNA and protein expression levels of IgG were significantly higher in D group than other groups (p < 0.05). Music stimulation increased the abundance of beneficial microbiota, such as Lactobacillus and Sporosarcina (p < 0.05). Mozart K.448 can strengthen intestinal barrier function to reduce intestinal permeability and improve intestinal immunity, while also having a positive significance in promoting the colonization of beneficial intestinal microbiota. In addition, the effect of tone D was more significant. Full article

This paper proposes a novel sparse array design and an efficient algorithm for two-dimensional direction-of-arrival (2D-DOA) estimation. By analyzing the hole distribution in coprime arrays and introducing supplementary elements, we design a Complementary Coprime Planar Array (CCPA) that strategically fills key holes in the virtual array. This design enhances the array’s continuous Degrees Of Freedom (DOFs) and virtual aperture, achieving improved performance in 2D-DOA estimation with fewer physical elements. The virtualization of the array further increases the available DOFs, while the hole-filling strategy ensures better spatial coverage and continuity. On the algorithmic side, we introduce a dimensionality-reduction root MUSIC algorithm tailored for uniform planar arrays after virtualization. By decomposing the two-dimensional spectral peak search into two one-dimensional polynomial root-finding problems, the proposed method significantly reduces computational complexity while maintaining high estimation accuracy. This approach effectively mitigates the challenges of 2D peak search, making it computationally efficient without sacrificing precision. Extensive simulations demonstrate the advantages of the proposed array and algorithm, including higher DOFs, reduced complexity, and superior estimation performance compared to existing methods. These results validate the effectiveness of the proposed framework in advancing sparse array design and signal processing for 2D-DOA estimation. Full article

Children with autism spectrum disorder (ASD) can have serious deficits in their social interactions, due to their limited social skills. There are many ways to use music as an intervention tool. One of them is by using musical instruments. Music emerges as a potential method of intervention, which can be used to address these deficits. The aims of this review are (a) to lay out internationally acclaimed and peer-reviewed studies, describing the elements of interventions with the use of musical instruments by children with autism, (b) to assess and analyze the effects of interventions with the use of musical instruments on the children’s social skills and (c) to provide recommendations to therapists, educators and researchers for future research and implementation. The process of article selection was carried out in strict adherence to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, ensuring methodological rigor and transparency in the systematic review process. A systematic search was conducted, using the following electronic databases: (a) PsycINFO, (b) Education Resources Information Center (ERIC), (c) Scopus and (d) Web of Science. Twelve studies were selected, with their results suggesting that the use of musical instruments, tangible or electronic ones, can have a positive effect on the social skills of children with autism. Inadequacies detected in the mentioned studies are also mentioned, as well as any important topics that should be gradually examined in future research. The present review is conducted within the framework of a doctoral thesis focusing on interventions that utilize music and technology as primary tools. Full article

In the current landscape of hearing rehabilitation, ear mold manufacturing typically involves the injection of silicone into the external ear canal (EEC) of each patient. This invasive procedure poses several risks, including the potential for silicone residue retention and tympanic membrane perforation, which may necessitate surgical intervention. To mitigate these risks, we present the design of a video otoscope that integrates a scanner capable of capturing high-precision, real-time images of the EEC’s geometry. The developed device allows (i) the generation of a 3D CAD model leading to the direct, quick, and low-cost production of customized hearing aids using 3D printing and (ii) the establishment of medical protocols for carrying out diagnoses and monitoring of hearing pathology evolution using methodologies based on Artificial Intelligence. Furthermore, the use of customized hearing aids that allow the application of Rhythmic Auditory Stimulation (RAS) and music therapy enhances audiology as an alternative and innovative way to treat cognitive and degenerative diseases, as well as pathological disorders. Full article

This paper presents the theoretical foundation, practical implementation, and empirical evaluation of a glove for interaction with 3-D virtual environments. At the dawn of the “Spatial Computing Era”, where users continuously interact with 3-D Virtual and Augmented Reality environments, the need for a practical and intuitive interaction system that can efficiently engage 3-D elements is becoming pressing. Over the last few decades, there have been attempts to provide such an interaction mechanism using a glove. However, glove systems are currently not in widespread use due to their high cost and, we propose, due to their inability to sustain high levels of performance under certain situations. Performance deterioration has been observed due to the distortion of the local magnetic field caused by ordinary ferromagnetic objects present near the glove’s operating space. There are several areas where reliable hand-tracking gloves could provide a next generation of improved solutions, such as American Sign Language training and automatic translation to text and training and evaluation for activities that require high motor skills in the hands (e.g., playing some musical instruments, training of surgeons, etc.). While the use of a hand-tracking glove toward these goals seems intuitive, some of the currently available glove systems may not meet the accuracy and reliability levels required for those use cases. This paper describes our concept of an interaction glove instrumented with miniature magnetic, angular rate, and gravity (MARG) sensors and aided by a single camera. The camera used is an off-the-shelf red, green, and blue–depth (RGB-D) camera. We describe a proof-of-concept implementation of the system using our custom “GMVDK” orientation estimation algorithm. This paper also describes the glove’s empirical evaluation with human-subject performance tests. The results show that the prototype glove, using the GMVDK algorithm, is able to operate without performance losses, even in magnetically distorted environments. Full article

This paper takes underwater hexapod robot target grasping in an extremely shallow water environment as the research goal and carries out the research on a high-precision and low-complexity method of target positioning. We address the above problem of estimating the two-dimensional (2D) directions of arrival (DOAs) of targets, using an L-shaped ultrasonic array. Based on the above considerations, low-complexity 2D multiple signal classification (MUSIC) based on sparse signal recovery (SSR) is proposed to enhance the super-resolution capability and DOA estimation accuracy. In the first step, subspace dimension is determined based on space distance. Then, a mixed-norm method is exploited to construct the projection subspace and new noise subspace. Finally, the orthogonality between the noise and signal subspaces is used to estimate DOAs. Via a numerical simulations analysis, we illustrate that the proposed technique can enhance the accuracy of DOA estimation while also being robust against coherent sources and limited snapshots. Full article