This study focuses on calculating multiple scattering by infinitely long circular cylinders using the multipole method. The multipole method requires truncating an infinite-dimensional linear system to a finite system, but selecting inappropriate truncation numbers may lead to inaccuracy or instability. Interestingly, the system's stability depends crucially on its formulation. Here, to demonstrate this, four (algebraically equivalent) formulations of the linear system are considered and compared through numerical experiments. The experimental results indicate that commonly used formulations become unstable with high truncation numbers, whereas less common formulations remain stable because of their well-conditioned system matrices, suggesting their computational advantage.
This study introduces a convolutional neural network based method for rapid prediction of underwater acoustic propagation fields, addressing the high computational cost of traditional methods. By analyzing regional terrain features and constructing a training dataset, the model learns acoustic transmission loss patterns across various terrain conditions. Tests in the Western Pacific demonstrate a root mean square error of 3.48 dB for non-smoothed fields, with an average prediction time of 1.95 ms per batch (10 samples). This method highlights the potential for fast acoustic propagation predictions using simplified inputs, offering a promising direction for real-time applications.
Gaussian processes (GPs) can densify and denoise sparsely sampled signals and have been applied in matched-field processing (MFP) localization to improve localization accuracy and robustness. Given a known true field, the minimum mean squared error criterion is proposed to evaluate the performance of GP interpolation and its application in MFP localization. This approach allows for the performance comparison of different kernel functions and likelihood functions, assisting in identifying the optimal hyperparameters, interpolation results, and localization outcomes. It also highlights possible challenges faced by existing GP methods under limited data conditions while establishing a performance upper bound for GPs-MFP.
A liquid irradiated with high-power ultrasound generates harmonics and broad-band noise. The effect of ultrasound-containing harmonics on the bubble shape stability was numerically investigated in this study by solving the Keller-Miksis equation and the dynamic equation of distortion amplitude to identify the effect of harmonics on the equilibrium bubble size of acoustic cavitation. Numerical results indicated that the tendency of bubble stability changed for low- and high-pressure amplitudes, which could be attributed to decrease in the bubble expansion because of harmonic waves at high-pressure amplitude. The cavitation bubble became more unstable under low-pressure amplitude conditions, and more stable at high-pressure amplitude conditions because of harmonics; however, the discrepancy in the stable zones was small. The bubble wall velocity contributed to bubble stability under both amplitude conditions. The magnitude of the maximum bubble wall velocity increased with harmonic waves for the small pressure-amplitude conditions, resulting in an unstable bubble shape. The time that the bubble wall spent moving at high velocity was shortened with increasing harmonic waves under the high-pressure amplitude conditions, causing a stable bubble shape. Further, the phase shift of the harmonic wave affected bubble stability; bubble expansion was largely suppressed, and the bubble became more stable with an increase in the minimum pressure of the composite wave.
Owing to the long duration of cooking legumes, which limits their consumption and utilization, soaking has been used to reduce cooking time, save energy consumption, and diminish their hardness. However, limited studies have reported the influence of cooking and soaking treatment along with ultrasonication on hydration, hardness, and cooking time reduction of legumes. Therefore, this study investigated the impact of cooking and soaking treatments on Dr. Saunder cowpea’s water absorption, hardness, and cooking time reduction with and without ultrasonication. Samples of Dr. Saunder’s cowpea were first soaked at 30 °C and 50 °C for 15 – 90 min (with and without ultrasonication), after which they were cooked at 100 °C and 121 °C for 15 – 120 min. The absorbed water and hardness of the tested samples under these treatments were measured. Hydration and softening behaviors were modeled from the obtained data using Ibarz-Augusto and first-order equations, respectively. Arrhenius equation was used to describe the kinetics of the hydration and softening process. Results showed that ultrasonic treatments accelerated water absorption and reduced the hardness of the samples; consequently, in a shorter time, using less energy will receive the desired hardness as the final product. The Ibartz-Augusto and first-order equations perfectively fit the sigmoidal and decaying exponential behavior of the absorbed water and hardness data with high prediction performance (R2 ≈ 1) marked by minimal error values. The deployment of ultrasonication and increased cooking temperature were observed to reduce the kinetic parameter (water absorption) and elevate the softening rates and activation energy (for hydration and softening). A synergy of the trio treatments reduced the total cooking duration from 120 min to 90 min (25 %), thus promoting the benefit of deploying ultrasonication to soften cowpeas and other seeds rapidly.
Wojciech BATKO, Leszek RADZISZEWSKI, Andrzej BĄKOWSKI
The article addresses the problem of assessing the impact of road modernization on improving the acoustic environment. It formulates a hypothesis about the advisability of adopting the scalar dimension of the decibel space to describe acoustic hazards. It is proposed to reduce the analysis of changes in sound levels to the analysis of changes in the coefficient of exceedance of the recommended noise levels. Its value is determined by the decibel relation of dividing sound levels. The basis for the assessment of the effectiveness of the adopted solution was the analysis of the statistical characteristics of monitored exceedances of recommended noise levels, considered through the prism of the current and proposed measure. They showed greater sensitivity of the proposed coefficient in the assessment of the improvement of the acoustic climate caused by road modernization. For example, the median noise level for nights before the road modernization was 66.9 dB(A), and after the modernization 65.6 dB(A). However, the coefficient of exceedances decreased by approximately 25 %. Numerical simulations, in accordance with the Cnossos noise model, showed that reducing the speed by 10 km/h will reduce the coefficient of exceedances by approximately 20 %.
The translation behaviors of oscillating bubbles are closely related to the polymerizations and dispersions between them, which are crucial for the ultrasonic cavitation effect. In this study, six types of translational motion of bubbles with a wide range of sizes (2–100 μm) in the R01-R02 plane are investigated. Our results demonstrate that in addition (to the 2nd order harmonic), the 1/2 order subharmonic can change the bubble pairs from the three states of the attraction, stable after attraction, and repulsion to that of the repulsion, coalescence, and attraction, respectively. Furthermore, within the range of the main resonance radius and the 1/2 order subharmonic resonance radius, the chaotic bubble pairs with alternating attractive and repulsive forces appear in the region between the coalescence pairs and stable pairs after attraction. Finally, the corresponding physical mechanisms of the chaotic translational motions are also revealed.
Motonobu Tomoda, Akihisa Kubota, Osamu Matsuda
et al.
We present a picosecond optoacoustic technique for mapping both the longitudinal sound velocity v and the refractive index n in solids by automated measurement at multiple probe incidence angles in time-domain Brillouin scattering. Using a fused silica sample with a deposited titanium film as an optoacoustic transducer, we map v and n in the depth direction. Applications include the imaging of sound velocity and refractive index distributions in three dimensions in inhomogeneous samples such as biological cells.
We present measurements of laser-induced shockwave pressure rise time in liquids on a sub-nanosecond scale, using custom-designed single-mode fiber optic hydrophone. The measurements are aimed at the study of the shockwave generation process, helping to improve the effectiveness of various applications and decrease possible accidental damage from shockwaves. The developed method allows measurement of the fast shockwave rise time as close as 10 µm from an 8 µm sized laser-induced plasma shockwave source, significantly improving the spatial and temporal resolution of the pressure measurement over other types of hydrophones. The spatial and temporal limitations of the presented hydrophone measurements are investigated theoretically, with actual experimental results agreeing well with the predictions. To demonstrate the capabilities of the fast sensor, we were able to show that the shockwave rise time is linked to liquid viscosity exhibiting logarithmic dependency in the low viscosity regime (from 0.4 cSt to 50 cSt). Additionally, the shockwave rise time dependency on propagation distance close to the source in water was investigated, with shock wave rise times measured down to only 150 ps. It was found that at short propagation distances in water halving the shock wave peak pressure results in the rise time increase by approximately factor of 1.6. These results extend the understanding of shockwave behavior in low viscosity liquids.
Abstract Traffic congestion can lead to negative driving emotions, significantly increasing the likelihood of traffic accidents. Reducing negative driving emotions as a means to mitigate speeding, reckless overtaking, and aggressive driving behaviors is a viable approach. Among the potential methods, affective speech has been considered one of the most promising. However, research on humor-based affective speech interventions in the context of driving negative emotions is scarce, and the utilization of electroencephalogram (EEG) signals for emotion detection in humorous audio studies remains largely unexplored. Therefore, our study first designed a highly realistic experiment scenario to induce negative emotions experienced by drivers in congested traffic conditions. Subsequently, we collected drivers’ EEG signals and subjective questionnaire ratings during the driving process. By employing one-way analysis of variance (ANOVA) and t tests, we analyzed the data to validate the success of our experiment in inducing negative emotions in drivers during congested road conditions and to assess the effectiveness of humorous audio in regulating drivers’ negative emotions. The results indicated that humorous audio effectively alleviated drivers’ negative emotions in congested road conditions, with a 145.84% increase in arousal and a 93.55% increase in valence ratings compared to control conditions. However, it should be noted that humorous audio only restored drivers’ emotions to the level experienced during normal driving. Our findings offer novel insights into regulating drivers’ negative emotions during congested road conditions.
Aarón Terán, Miguel Cortijo, Ángel Gutiérrez
et al.
The elusive monosubstituted diruthenium complexes [Ru2Cl(DAniF)(O2CMe)3] (1), [Ru2Cl(DPhF)(O2CMe)3] (2), [Ru2Cl(D-p-CNPhF)(O2CMe)3] (3), [Ru2Cl(D-o-TolF)(O2CMe)3] (4), [Ru2Cl(D-m-TolF)(O2CMe)3] (5), [Ru2Cl(D-p-TolF)(O2CMe)3] (6) and [Ru2Cl(p-TolA)(O2CMe)3] (7) have been synthesized using for the first time ultrasound-assisted synthesis to carry out a substitution reaction in metal–metal bonded dinuclear compounds (DAniF− = N,N′-bis(4-anisyl)formamidinate; DPhF− = N,N′-diphenylformamidinate; D-p-CNPhF− = N,N′-bis(4-cyanophenyl)formamidinate; D-o/m/p-TolF− = N,N′-bis(2/3/4-tolyl)formamidinate; p-TolA− = N-4-tolylamidate). This is a simpler and greener method than the tedious procedures described in the literature, and it has permitted to obtain water-soluble complexes with good yields in a short period of time. A synthetic study has been implemented to find the best experimental conditions to prepare compounds 1–7. Two different types of ligands, formamidinate and amidate, have been used to check the generality of the method for the preparation of monosubstituted complexes. Five new compounds (2–6) have been obtained using a formamidinate ligand, the synthesis of the previously described compound 1 has been improved, and an unprecedented monoamidate complex has been achieved (7). The crystal structures of compounds 3 and 7 have been solved by single crystal X-ray diffraction. These compounds show the typical paddlewheel structure with three acetate ligands and one formamidinate (3) or amidate (7) bridging ligand at the equatorial positions. The axial positions are occupied by the chloride ligand giving rise to one-dimensional polymer structures that were previously unknown for monosubstituted compounds.
To a first-order approximation we can place most worship services on a continuum between clarity and mystery, depending on the setting and content of the service. This liturgical space can be thought of as a combination of the physical acoustics of the worship space and the qualities of the sound created during the worship service. A very clear acoustic channel emphasizes semantic content, especially speech intelligibility. An immersive, reverberant acoustic emphasizes mystery and music. One of the chief challenges in acoustical design is the fact that both clarity and immersion are subjectively preferred by audiences, yet these two goals are almost mutually exclusive of one another. The movement along this continuum in liturgical space can also be seen in the religious contexts for many of the worship spaces constructed in the West in the last two millennia. In the case of religious ceremony, a free field acoustic environment provides more clarity and precision in the spoken word received from God and given to the congregation. Yet a diffuse field environment provides an embodied, otherworldly sense of the supernatural: the mystery of the faith received which cannot merely be put into words. This tension is perceptible in many of the religious controversies in the West during this time period. This article examines the history of the spaces used by early Western Catholic Christians as well as those of the traditions—Lutheran and Calvinist—that left the Catholic faith during the 16th century Reformation. By considering the stated goals of these traditions alongside the architectural and liturgical innovations they created, it can be seen that emergent liturgical spaces mirror the assumptions of their respective traditions regarding the proper balance between semantic and aesthetic communication during the worship service. The Reformed faiths' emphasis on the power of the Word is reflected in the liturgical space of their services, while the Catholic faith gave greater priority to the role of Mystery, in their liturgical space as well as their explicit theology. Once constructed, these spaces also aid the cultural transmission of the sung or spoken liturgy of each tradition to future generations.
A survey of the literature related to theoretical and experimental studies on stick–slip vibration in oilwell drillstring is carried out in this study. It aims to explain key concepts and present the existing methods for studying this phenomenon. After briefly describing the stick–slip vibration related problems, theoretical models for such phenomenon are discussed including both coupled and uncoupled models. Discussion for experimental investigations including both laboratory and field tests are hereinafter addressed. This study aims to summarize the literature related to the stick–slip vibration, and help researchers in understanding and suppressing such phenomenon.
Control engineering systems. Automatic machinery (General), Acoustics. Sound
Abstract Dynamic time warping (DTW) can be used to compute the similarity between two sequences of generally differing length. We propose a modification to DTW that performs individual and independent pairwise alignment of feature trajectories. The modified technique, termed feature trajectory dynamic time warping (FTDTW), is applied as a similarity measure in the agglomerative hierarchical clustering of speech segments. Experiments using MFCC and PLP parametrisations extracted from TIMIT and from the Spoken Arabic Digit Dataset (SADD) show consistent and statistically significant improvements in the quality of the resulting clusters in terms of F-measure and normalised mutual information (NMI).
Rafał MŁYŃSKI, Emil KOZŁOWSKI, Jacek USOWSKI
et al.
The tests reported in this paper were carried out to evaluate the exposure of soldiers to noise at operator and control positions during military field exercises. The tests were conducted during firing from a T-72 tank, a BWP-1 Infantry Fighting Vehicle, antitank guided missiles, a ZU-23-2K anti-aircraft gun, and a 2S1 GOZDZIK howitzer. The evaluation of noise exposure showed that the limit values of sound pressure level, referred to by both Polish occupational noise protection standards and the Pfander and Dancer hearing damage risk criteria developed for military applications, were repeatedly exceeded at the tested positions. Despite of the use of tank crew headgear, the exposure limit values of sound pressure level were exceeded for the crew members of the T-72 tank, the BWP-1 infantry fighting vehicle, and the 2S1 GOZDZIK howitzer. The results show that exposure of soldiers to noise during military field exercises is a potentially high hearing risk factor.