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Search Results (17,810)

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22 pages, 1079 KiB  
Article
Experimental Study of the Influence of Even Harmonics on Flame Extinguishing by Low-Frequency Acoustic Waves with the Use of High-Power Extinguisher
by Jacek Lukasz Wilk-Jakubowski
Appl. Sci. 2024, 14(24), 11809; https://doi.org/10.3390/app142411809 (registering DOI) - 17 Dec 2024
Abstract
The acoustic technique appears to be a novel and innovative way to extinguish flames, in which properly generated waves emitted by a high-power sound source are used for extinguishing purposes. The highest extinguishing efficiency is demonstrated by low-frequency waves. In practice, changing the [...] Read more.
The acoustic technique appears to be a novel and innovative way to extinguish flames, in which properly generated waves emitted by a high-power sound source are used for extinguishing purposes. The highest extinguishing efficiency is demonstrated by low-frequency waves. In practice, changing the parameters of the acoustic signal results in the possibility of universal and reusable use of the extinguisher, which is limited only by access to the power supply, unlike the currently known traditional methods of fighting fire (such as gases, foams, and extinguishing powders). The purpose of this paper is to analyze whether flame extinguishing by low-frequency acoustic waves is possible using signals containing higher harmonics with the use of large and very large powers delivered to the sound source, which is a scientific novelty. Analyzing the extinguishing capabilities of low-frequency acoustic waves allows one to fill the gap in the literature. This paper presents the results of research in the range of the influence of even sinusoidal harmonics on the extinguishing of flames originating from organic substances. For this purpose, in the experimental part, a high-power acoustic extinguisher and a point source of flames, i.e., a candle containing paraffin wax, were applied. The capabilities of the acoustic method in flame extinguishing have been experimentally demonstrated. The results address both the power that had to be delivered to the sound source of a high-power acoustic extinguisher to extinguish flames and the sound pressure level at which this phenomenon was observed. The added value is also to analyze how the order of even harmonics affects the process of acoustic extinguishment of flames (the order of harmonics for each fundamental frequency was varied from two to ten). Furthermore, the potential benefits and limitations of this method are explained, and future research directions are presented. Full article
(This article belongs to the Section Acoustics and Vibrations)
24 pages, 3460 KiB  
Article
Development of a Low-Cost Automated Injection Molding Device for Sustainable Plastic Recycling and Circular Economy Applications
by Ananta Sinchai, Kunthorn Boonyang and Thanakorn Simmala
Inventions 2024, 9(6), 124; https://doi.org/10.3390/inventions9060124 (registering DOI) - 17 Dec 2024
Abstract
In response to the critical demand for innovative solutions to tackle plastic pollution, this research presents a low-cost, fully automated plastic injection molding system designed to convert waste into sustainable products. Constructed entirely from repurposed materials, the apparatus focuses on processing high-density polyethylene [...] Read more.
In response to the critical demand for innovative solutions to tackle plastic pollution, this research presents a low-cost, fully automated plastic injection molding system designed to convert waste into sustainable products. Constructed entirely from repurposed materials, the apparatus focuses on processing high-density polyethylene (HDPE) efficiently without hydraulic components, thereby enhancing eco-friendliness and accessibility. Performance evaluations identified an optimal molding temperature of 200 °C, yielding consistent products with a minimal weight deviation of 4.17%. The key operational parameters included a motor speed of 525 RPM, a gear ratio of 1:30, and an inverter frequency of 105 Hz. Further tests showed that processing temperatures of 210 °C and 220 °C, with injection times of 15 to 35 s, yielded optimal surface finish and complete filling. The surface finish, assessed through image intensity variation, had a low coefficient of variation (≤ 5%), while computer vision evaluation confirmed the full filling of all specimens in this range. A laser-based overflow detection system has minimized material waste, proving effective in small-scale, community recycling. This study underscores the potential of low-cost automated systems to advance the practices of circular economies and enhance localized plastic waste management. Future research will focus on automation, temperature precision, material adaptability, and emissions management. Full article
(This article belongs to the Section Inventions and Innovation in Advanced Manufacturing)
26 pages, 4990 KiB  
Article
Analysis of Time–Frequency Characteristics and Influencing Factors of Air Quality Based on Functional Data in Fujian
by Huirou Shen, Yanglan Xiao, Linyi You, Yijing Zheng, Houzhan Xie, Yihan Xu, Zhongzhu Chen, Aidi Wu, Yuning Huang and Tiange You
Atmosphere 2024, 15(12), 1510; https://doi.org/10.3390/atmos15121510 (registering DOI) - 17 Dec 2024
Abstract
Increased air pollution is driven by anthropogenic pollution emissions and climate change, which pose great challenges to environmental governance. Strengthening the monitoring of regional air quality levels and analyzing the causes of regional pollution is conducive to the management and sustainable development of [...] Read more.
Increased air pollution is driven by anthropogenic pollution emissions and climate change, which pose great challenges to environmental governance. Strengthening the monitoring of regional air quality levels and analyzing the causes of regional pollution is conducive to the management and sustainable development of the regional atmosphere. Functional data obtained on a wavelet basis were used in the fitting of air quality data of Fujian Province, and wavelet decomposition was performed to obtain low-frequency and high-frequency information. While the Fourier basis cannot adaptively adjust the time–frequency window, resulting in the loss of location information of special frequencies, the wavelet basis solves this problem. Functional analysis of variance was utilized for analyzing spatial differences in air pollution characteristics. Furthermore, the study established a multivariate functional linear regression model to explore the impact of meteorological factors and ozone precursor factors. The results indicated that the overall air quality was gradually improving in Fujian Province, but the concentration of ozone was progressively increasing. Air pollution in coastal areas was higher than that in inland areas. The p-values of the functional analysis of variance for energy values and crest values were less than 0.05. Moreover, the energy entropy and kurtosis values were greater than 0.05. There were significant differences of AQI in the fluctuation amplitude and variation characteristics of different cities. The total squared multiple correlation of regression model was above 50% on average. Ozone is currently the most serious pollution factor, mainly affected by wind speed, temperature, NO2, and CO. In summer, it was principally influenced by VOCs. The findings of this study could act as a reference in exploring the time–frequency characteristics of air quality data and support of air pollution control. Full article
(This article belongs to the Section Air Quality)
13 pages, 813 KiB  
Article
Development of a Wearable Electromyographic Sensor with Aerosol Jet Printing Technology
by Stefano Perilli, Massimo Di Pietro, Emanuele Mantini, Martina Regazzetti, Pawel Kiper, Francesco Galliani, Massimo Panella and Dante Mantini
Bioengineering 2024, 11(12), 1283; https://doi.org/10.3390/bioengineering11121283 - 17 Dec 2024
Abstract
Electromyographic (EMG) sensors are essential tools for analyzing muscle activity, but traditional designs often face challenges such as motion artifacts, signal variability, and limited wearability. This study introduces a novel EMG sensor fabricated using Aerosol Jet Printing (AJP) technology that addresses these limitations [...] Read more.
Electromyographic (EMG) sensors are essential tools for analyzing muscle activity, but traditional designs often face challenges such as motion artifacts, signal variability, and limited wearability. This study introduces a novel EMG sensor fabricated using Aerosol Jet Printing (AJP) technology that addresses these limitations with a focus on precision, flexibility, and stability. The innovative sensor design minimizes air interposition at the skin–electrode interface, thereby reducing variability and improving signal quality. AJP enables the precise deposition of conductive materials onto flexible substrates, achieving a thinner and more conformable sensor that enhances user comfort and wearability. Performance testing compared the novel sensor to commercially available alternatives, highlighting its superior impedance stability across frequencies, even under mechanical stress. Physiological validation on a human participant confirmed the sensor’s ability to accurately capture muscle activity during rest and voluntary contractions, with clear differentiation between low and high activity states. The findings highlight the sensor’s potential for diverse applications, such as clinical diagnostics, rehabilitation, and sports performance monitoring. This work establishes AJP technology as a novel approach for designing wearable EMG sensors, providing a pathway for further advancements in miniaturization, strain-insensitive designs, and real-world deployment. Future research will explore optimization for broader applications and larger populations. Full article
20 pages, 7862 KiB  
Article
Numerical and Experimental Study on the Hydrodynamic Performance of a Sloping OWC Wave Energy Converter Device Integrated into Breakwater
by Taotao Tao, Zhengzhi Deng, Mengyao Li, Pengda Cheng and Wenbo Luo
J. Mar. Sci. Eng. 2024, 12(12), 2318; https://doi.org/10.3390/jmse12122318 - 17 Dec 2024
Abstract
This study presents numerical and experimental investigations on an oscillating water column (OWC) wave energy device integrated into a sloping breakwater. Regular waves were generated in a physical wave tank to investigate the hydrodynamic performance and extraction efficiency of the small-scale nested OWC [...] Read more.
This study presents numerical and experimental investigations on an oscillating water column (OWC) wave energy device integrated into a sloping breakwater. Regular waves were generated in a physical wave tank to investigate the hydrodynamic performance and extraction efficiency of the small-scale nested OWC device. Simultaneously, to complement various scenarios, numerical simulations were conducted using the open-source computational fluid dynamics platform OpenFOAM. The volume of fluid (VOF) method was employed to capture the complex evolution of the air–water interface, and an artificial source term (Forchheimer flow region) was introduced into the Navier–Stokes equations to replace the power take-off (PTO) system. By analyzing wave reflection properties, energy absorption efficiency, and wave run-up, the hydrodynamic characteristics of the inclined OWC device were explored. The comparison between the numerical and experimental results indicate a good consistence. A smaller front wall draft broadens the high-efficiency frequency bandwidth. For relatively long waves, increasing the air chamber width enhances energy conversion efficiency and reduces wave run-up. The optimal configuration was achieved with the following dimensionless parameters: front wall draft a/h=1/3, air chamber width d1/h=2/9, and slope i=2. Due to the sloped structure, when compared with a vertical OWC, long waves can more easily enter the chamber. This causes the efficient frequency bandwidth to shift towards the low frequency range, allowing more wave energy to be converted into pneumatic energy. As a result, wave run-up is reduced, enhancing the protective function of the breakwater. Full article
(This article belongs to the Topic Marine Renewable Energy, 2nd Edition)
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Figure 1

Figure 1
<p>A sketch of the OWC device.</p>
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<p>Physical model of the OWC device.</p>
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<p>The OWC device in the wave flume.</p>
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<p>Detail view of the orifice.</p>
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<p>Experimental setup.</p>
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<p>The grid discretization scheme around the structure. (<b>a</b>) Coarse, (<b>b</b>) medium, and (<b>c</b>) fine.</p>
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<p>The variation of the free surface (<b>a</b>) and the corresponding pressure values (<b>b</b>) in the air chamber under different grids.</p>
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<p>The comparison of numerical values of the free surface at the front wall of the OWC device and the relative pressure in the air chamber with experimental results. (<b>a</b>) Surface elevation, (<b>b</b>) pressure drop (<span class="html-italic">H<sub>i</sub></span> = 0.03 m, <span class="html-italic">T</span> = 1.0 s), (<b>c</b>) surface elevation, and (<b>d</b>) pressure drop (<span class="html-italic">H<sub>i</sub></span> = 0.03 m, <span class="html-italic">T</span> = 2.4 s).</p>
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<p>Comparison between experimental and numerical results for the OWC device. (<b>a</b>) Wave energy absorption efficiency, (<b>b</b>) reflection coefficient, (<b>c</b>) peak and trough values of the free surface oscillations at the front wall, and (<b>d</b>) peak and trough values of the free surface oscillations at the back wall (h = 0.40 m).</p>
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<p>Comparison between experimental and numerical results for the OWC device. (<b>a</b>) Wave energy absorption efficiency, (<b>b</b>) reflection coefficient, (<b>c</b>) peak and trough values of the free surface oscillations at the front wall, and (<b>d</b>) peak and trough values of the free surface oscillations at the back wall (h = 0.45 m).</p>
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<p>The impact of the front wall draft depth on the hydrodynamic characteristics of the sloped OWC device. (<b>a</b>) Wave energy absorption efficiency, (<b>b</b>) reflection coefficient, (<b>c</b>) energy dissipation coefficient, (<b>d</b>) maximum pressure difference on both sides of the front wall, (<b>e</b>) relative amplitude of the water column in the air chamber, and (<b>f</b>) relative wave run-up at the front wall.</p>
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<p>The impact of chamber width on the hydrodynamic characteristics of the sloped OWC device. (<b>a</b>) Wave energy absorption efficiency, (<b>b</b>) reflection coefficient, (<b>c</b>) energy dissipation coefficient, (<b>d</b>) maximum pressure difference on both sides of the front wall, (<b>e</b>) relative amplitude of the water column in the air chamber, and (<b>f</b>) relative wave run-up at the front wall.</p>
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<p>Schematic diagram of slope variation for sloped OWC device.</p>
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<p>The impact of slope on the hydrodynamic characteristics of the sloped OWC device. (<b>a</b>) Wave energy absorption efficiency, (<b>b</b>) reflection coefficient, (<b>c</b>) energy dissipation coefficient, (<b>d</b>) maximum pressure difference on both sides of the front wall, (<b>e</b>) relative amplitude of the water column in the air chamber, and (<b>f</b>) relative wave run-up at the front wall.</p>
Full article ">Figure 14 Cont.
<p>The impact of slope on the hydrodynamic characteristics of the sloped OWC device. (<b>a</b>) Wave energy absorption efficiency, (<b>b</b>) reflection coefficient, (<b>c</b>) energy dissipation coefficient, (<b>d</b>) maximum pressure difference on both sides of the front wall, (<b>e</b>) relative amplitude of the water column in the air chamber, and (<b>f</b>) relative wave run-up at the front wall.</p>
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26 pages, 4377 KiB  
Article
Characteristics and Comparative Assessment of Flash Flood Hazard Evaluation Techniques: Insights from Wadi Haily Basin, Eastern Red Sea Coast, Saudi Arabia
by Bashar Bashir and Abdullah Alsalman
Water 2024, 16(24), 3634; https://doi.org/10.3390/w16243634 - 17 Dec 2024
Abstract
The Wadi Haily basin in southwest Saudi Arabia, which runs along the Red Sea coast, serves as an ideal natural laboratory for understanding flash flood dynamics in this region. However, limited morphometric and hydrological data are currently available in this area. This study [...] Read more.
The Wadi Haily basin in southwest Saudi Arabia, which runs along the Red Sea coast, serves as an ideal natural laboratory for understanding flash flood dynamics in this region. However, limited morphometric and hydrological data are currently available in this area. This study aims to analyze key morphometric effective parameters to examine and assess flash flood risk potential within the basin. Using remote sensing, GIS, geological, and topographical datasets, this research combines advanced modeling and GIS tools to produce detailed flood hazard maps and risk assessments. This study examines 15 sub-basins of varying sizes, characterized by primary stream orders ranging from 4th to 8th. Based on morphometric analysis, the basins are categorized by flood susceptibility: four basins have a low flood risk, five exhibit moderate risk, and six are highly susceptible to flooding. Key findings indicate that the study area features a vast drainage area, high grid cell values of the drainage frequency, moderate drainage density, elongated basin shapes, low infiltration rates, and long overland flow distances, all suggesting a heightened flood hazard. Additional indicators include high values in gradient ratios, slopes, ruggedness numbers, relief ratios, and basin relief, reinforcing the basin’s flash flood vulnerability. This study provides a comprehensive morphological framework that can support strategic flood management and hazard mitigation planning for the Wadi Haily region. Full article
19 pages, 6153 KiB  
Article
Multi-Objective Topology Optimization of Thin-Plate Structures Based on the Stiffener Size and Layout
by Qin Yin, Junsong Guo, Yingzhe Kan, Jinghua Ma and Congying Deng
Electronics 2024, 13(24), 4968; https://doi.org/10.3390/electronics13244968 - 17 Dec 2024
Abstract
To address the limitations of existing optimization methods that focus on single objectives or neglect stiffener features, a multi-objective topology optimization (MOTO) method is proposed based on the stiffener size and layout. By constraining the initial structural performance parameters, the optimal stiffener height [...] Read more.
To address the limitations of existing optimization methods that focus on single objectives or neglect stiffener features, a multi-objective topology optimization (MOTO) method is proposed based on the stiffener size and layout. By constraining the initial structural performance parameters, the optimal stiffener height is determined through size optimization. Based on the stiffener height, single-objective topology optimization is used to achieve the best material distribution. The stiffener width is treated as a design variable, while MOTO is performed on the load point displacement, first natural frequency, and mass, thereby yielding an optimal stiffener width and performance. Finally, a multi-dimensional analysis of the stiffener height, width, and dynamic and static characteristics of the stiffened thin-plate structure is conducted. The results indicate that the optimized stiffener layout is considerably improved. Compared to the initial structure, the maximum and average displacements of the load point are reduced by 23.26% and 8.62%, respectively. The first natural frequency increases by 3.81%, while the maximum resonance amplitude and overall structural mass decrease by 39.97% and 1.99%, respectively. The results indicate that the optimized structure achieves a lightweight design while maintaining better stiffness and low-frequency vibration resistance. The feasibility and effectiveness of the proposed method are validated. Full article
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Figure 1

Figure 1
<p>(<b>a</b>) Schematic of a large WSS; (<b>b</b>) milling process; (<b>c</b>) cruciform stiffeners.</p>
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<p>Schematic of the initial STPS: (<b>a</b>) upper surface; (<b>b</b>) lower surface.</p>
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<p>Finite element model of the initial STPS: (<b>a</b>) upper surface; (<b>b</b>) lower surface.</p>
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<p>Technical roadmap of the MOTO method.</p>
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<p>(<b>a</b>) Iteration curve; (<b>b</b>) optimization results of the IP thickness.</p>
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<p>Topology optimization results: (<b>a</b>) Scheme 1; (<b>b</b>) Scheme 2.</p>
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<p>Optimization results with different load point displacement constraints.</p>
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<p>(<b>a</b>) Reconstructed model of the STPS; (<b>b</b>) optimized stiffener layout.</p>
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<p>Response levels of the design variables to the optimization objectives: (<b>a</b>) mass; (<b>b</b>) feature point displacement; (<b>c</b>) first natural frequency.</p>
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<p>MOTO results: (<b>a</b>) all the objectives; (<b>b</b>) feature point displacement and first natural frequency; (<b>c</b>) feature point displacement and mass; (<b>d</b>) first natural frequency and mass.</p>
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<p>Topology optimization results of the three schemes: (<b>a</b>) H1; (<b>b</b>) H2; (<b>c</b>) H3.</p>
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<p>Comparison of the frequency response function curves between the two schemes: (<b>a</b>) X-axis; (<b>b</b>) Y-axis; (<b>c</b>) Z-axis.</p>
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18 pages, 5537 KiB  
Article
Relaxation Phenomena in Low-Density and High-Density Polyethylene
by Viktor A. Lomovskoy and Svetlana A. Shatokhina
Polymers 2024, 16(24), 3510; https://doi.org/10.3390/polym16243510 - 17 Dec 2024
Viewed by 79
Abstract
A study was conducted on the internal friction spectra and temperature dependencies of the frequency of free damped oscillatory processes excited in the investigated samples of low-density polyethylene (LDPE) and high-density polyethylene (HDPE) over a temperature range from −150 °C to +150 °C. [...] Read more.
A study was conducted on the internal friction spectra and temperature dependencies of the frequency of free damped oscillatory processes excited in the investigated samples of low-density polyethylene (LDPE) and high-density polyethylene (HDPE) over a temperature range from −150 °C to +150 °C. It was found that the internal friction spectra exhibit several local dissipative processes of varying intensity, which manifest in different temperature intervals. The structure of the internal friction spectra and the peaks of dissipative losses are complex, as evidenced by the occurrence of sharp, locally temperature-dependent jumps in the intensity of dissipative losses observed throughout the entire temperature range. A theoretical analysis was performed to explore the relationship between the anomalous change in the frequency of the oscillatory process and the defect in the shear modulus, as well as the mechanisms of internal friction for the most intense dissipative loss processes identified in the internal friction spectra. A significant difference was revealed in the structure of the internal friction spectra of LDPE and HDPE in the temperature range of −50 °C to +50 °C. A comparison of the LDPE and HDPE samples was conducted based on changes in their strength characteristics, taking into account the locally temperature-dependent changes in the shear modulus caused by local dissipative losses observed in the internal friction spectra. Full article
(This article belongs to the Section Polymer Analysis and Characterization)
Show Figures

Graphical abstract

Graphical abstract
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<p>Internal friction spectrum <math display="inline"><semantics> <mrow> <mi>λ</mi> <mo>=</mo> <mi>f</mi> <mfenced> <mi>T</mi> </mfenced> </mrow> </semantics></math> of HDPE.</p>
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<p>Schematic representation of a horizontal torsional pendulum. 1—Furnace housing; 2—collet; 3—sample; 4—substrates used in the high-temperature range; 5—horizontal rod; 6—core; 7–9—photoelectric transducer; 10—inertial weights; 11—shell; 12—counterweight; 13—tension string; 14—pendulum beam; 15—weight for tension; 16—vacuum cover; 17—electromagnets; 18—base plate.</p>
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<p>Diagrams outlining the freely damped oscillatory process induced in the studied material; (<b>a</b>) in isothermal mode <math display="inline"><semantics> <mrow> <mi>T</mi> <mo>=</mo> <mi>c</mi> <mi>o</mi> <mi>n</mi> <mi>s</mi> <mi>t</mi> </mrow> </semantics></math>; (<b>b</b>) by pulse action. Sweep of the time dependence of the twist angle <math display="inline"><semantics> <mrow> <mi>φ</mi> <mfenced> <mi>t</mi> </mfenced> </mrow> </semantics></math> relative to the longitudinal axis <math display="inline"><semantics> <mi>Z</mi> </semantics></math> of the specimen—(<b>c</b>). The deformation of the sample—<math display="inline"><semantics> <mrow> <mi>γ</mi> <mfenced> <mi>t</mi> </mfenced> </mrow> </semantics></math>—(<b>d</b>) and the corresponding shear stresses <math display="inline"><semantics> <mrow> <msub> <mi>σ</mi> <mrow> <mi>i</mi> <mi>j</mi> </mrow> </msub> </mrow> </semantics></math> occurring in the sample—(<b>e</b>). <math display="inline"><semantics> <mi>β</mi> </semantics></math>—damping coefficient of the oscillatory process; <math display="inline"><semantics> <mi>θ</mi> </semantics></math>—period of the vibration process. All other designations are defined below in the text of the article [<a href="#B21-polymers-16-03510" class="html-bibr">21</a>,<a href="#B47-polymers-16-03510" class="html-bibr">47</a>].</p>
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<p>DSC thermograms for LDPE and HDPE.</p>
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<p>Internal friction spectrum <math display="inline"><semantics> <mrow> <mi>λ</mi> <mo>=</mo> <mi>f</mi> <mfenced> <mi>T</mi> </mfenced> </mrow> </semantics></math> (<b>a</b>); temperature dependence of frequency <math display="inline"><semantics> <mrow> <mi>ν</mi> <mo>=</mo> <mi>f</mi> <mfenced> <mi>T</mi> </mfenced> </mrow> </semantics></math> (<b>b</b>) for LDPE (red line) and HDPE (blue line).</p>
Full article ">Figure 5 Cont.
<p>Internal friction spectrum <math display="inline"><semantics> <mrow> <mi>λ</mi> <mo>=</mo> <mi>f</mi> <mfenced> <mi>T</mi> </mfenced> </mrow> </semantics></math> (<b>a</b>); temperature dependence of frequency <math display="inline"><semantics> <mrow> <mi>ν</mi> <mo>=</mo> <mi>f</mi> <mfenced> <mi>T</mi> </mfenced> </mrow> </semantics></math> (<b>b</b>) for LDPE (red line) and HDPE (blue line).</p>
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<p>Temperature–frequency dependencies and a graphical example of determining the modulus defect <math display="inline"><semantics> <mrow> <mo>Δ</mo> <mi>G</mi> </mrow> </semantics></math> for LDPE (<b>a</b>) and HDPE (<b>b</b>).</p>
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<p>The internal friction spectrum of LDPE and HDPE in the temperature range from −70 °C to +130 °C.</p>
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<p>Decomposition of the <math display="inline"><semantics> <mi>α</mi> </semantics></math> peaks and the <math display="inline"><semantics> <mrow> <msub> <mi>β</mi> <mi>k</mi> </msub> </mrow> </semantics></math> peak of dissipative losses using a mathematical method based on Gaussian distribution.</p>
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<p>The dependence of the relaxation time and activation energy of <math display="inline"><semantics> <mi>α</mi> </semantics></math> processes on temperature for LDPE is shown, with the activation energy values indicated by a red dashed line on the additional axis on the right.</p>
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<p>The dependence of relaxation time and activation energy of the <math display="inline"><semantics> <mrow> <msub> <mi>β</mi> <mi>k</mi> </msub> </mrow> </semantics></math> processes on temperature for LDPE and HDPE is illustrated, with the activation energy values indicated by the red dashed line on the additional axis on the right.</p>
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<p>Schematic representation of the separation of <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>+</mo> <msub> <mi>β</mi> <mi>k</mi> </msub> </mrow> </semantics></math> peaks of LDPE and HDPE.</p>
Full article ">Figure 11 Cont.
<p>Schematic representation of the separation of <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>+</mo> <msub> <mi>β</mi> <mi>k</mi> </msub> </mrow> </semantics></math> peaks of LDPE and HDPE.</p>
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20 pages, 98934 KiB  
Article
Automated Snow Avalanche Monitoring and Alert System Using Distributed Acoustic Sensing in Norway
by Antoine Turquet, Andreas Wuestefeld, Guro K. Svendsen, Finn Kåre Nyhammer, Espen Lauvlund Nilsen, Andreas Per-Ola Persson and Vetle Refsum
GeoHazards 2024, 5(4), 1326-1345; https://doi.org/10.3390/geohazards5040063 - 17 Dec 2024
Viewed by 77
Abstract
Avalanches present substantial hazard risk in mountainous regions, particularly when avalanches obstruct roads, either hitting vehicles directly or leaving traffic exposed to subsequent avalanches during cycles. Traditional detection methods often are designed to cover only a limited section of a road stretch, hampering [...] Read more.
Avalanches present substantial hazard risk in mountainous regions, particularly when avalanches obstruct roads, either hitting vehicles directly or leaving traffic exposed to subsequent avalanches during cycles. Traditional detection methods often are designed to cover only a limited section of a road stretch, hampering effective risk management. This research introduces a novel approach using Distributed Acoustic Sensing (DAS) for avalanche detection. The monitoring site in Northern Norway is known to be frequently impacted by avalanches. Between 2022–2024, we continuously monitored the road for avalanches blocking the traffic. The automated alert system identifies avalanches affecting the road and estimates accumulated snow. The system provides continuous, real-time monitoring with competitive sensitivity and accuracy over large areas (up to 170 km) and for multiple sites on parallel. DAS powered alert system can work unaffected by visual barriers or adverse weather conditions. The system successfully identified 10 road-impacting avalanches (100% detection rate). Our results via DAS align with the previous works and indicate that low frequency part of the signal (<20 Hz) is crucial for detection and size estimation of avalanche events. Alternative fiber installation methods are evaluated for optimal sensitivity to avalanches. Consequently, this study demonstrates its durability and lower maintenance requirements, especially when compared to the high setup costs and coverage limitations of radar systems, or the weather and lighting vulnerabilities of cameras. Furthermore the system can detect vehicles on the road as important supplemental information for search and rescue operations, and thus the authorities can be alerted, thereby playing a vital role in urgent rescue efforts. Full article
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<p>(<b>a</b>) Map showing Existing Cable (blue) and New Cable extension (orange). Photos taken during the installation are attached from (i) the cabinet at the northern end of the monitoring system, (ii) the vehicle warning system end of the north section, (iii) the vehicle warning system beginning of the south section (iv) an example photo of microtrenching. (<b>b</b>) Map of Norway and the region surrounding the avalanche monitoring zone. Important places are marked, including Holmbuktura, the location of the installation. (<b>c</b>) A cross section sketch showing the details of microtrench cable installation (iv). Direct buried new cable is installed at 15 cm depth and plastic tube covered installation is done at 20 cm depth from the surface.</p>
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<p>Aerial overview of the Holmbuktura region detailing characteristic avalanche paths and the avalanche monitoring setup. The image on the left (<b>a</b>) shows a comprehensive view of the valley with shaded areas for avalanche zones in north and south. The paths (1–5) along the slope show 5 characteristic avalanche paths, delineating the primary areas of avalanche activity. The cyan line represents the trajectory of the sensor cable installation, placed to capture both the dynamics of avalanches and the road traffic activity. The plot on the right (<b>b</b>) shows the altitude evolution along 5 selected paths, giving the impression of the topography of the region. Image © 2024 Google Earth, Image Landsat/Copernicus, Image © 2024 Maxar Technologies, Image © 2024 CNES/Airbus.</p>
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<p>Simplified flowchart of the automated avalanche detection and monitoring system. Data is continuously collected and processed through edge computing in two separate modules: (1) vehicle detection and (2) avalanche detection, which operate independently to avoid interference. Detected avalanches and vehicles are then transferred to a central repository and messaging module. This module evaluates risk levels, checks for stranded or at-risk vehicles, and prepares necessary visualizations and alerts. If the risk level exceeds a predefined threshold, the system sends alerts, including plots and messages, via SCADA message system and email using 4G communication.</p>
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<p>Examples of signals recorded during monitoring with the DAS system in Holmbuktura are shown. The strain rate waterfall plot (Z) highlights features of different events: (<b>a</b>) avalanche activity in the north, (<b>b</b>) avalanche activity in the south, (<b>c</b>) a passenger car, and (<b>d</b>) a snowplow.</p>
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<p>The power spectral density (PSD) was computed from signals recorded during monitoring with the DAS system in Holmbuktura. The signals represent distinct events, specifically: (<b>a</b>) avalanche activity in the north, (<b>b</b>) avalanche activity in the south, (<b>c</b>) a passenger car, and (<b>d</b>) a snowplow.</p>
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<p>Most energetic traces from all avalanches are presented as raw signals. In (<b>a</b>) avalanche signals are presented and marked with “Zone N” and “Zone S” showing where the avalanches happened. Event 0 is an avalanche which stopped right before the road it is presented for comparison. Corresponding mean frequency of the 200 s trace is computed and marked on the end of trace. In (<b>b</b>) we present the spectrogram of all avalanches. (<b>c</b>,<b>d</b>) we compare the power spectra of north avalanches and south avalanches respectively. The associated log-averaged power spectra are also plotted.</p>
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<p>Co-located direct buried “D” (red) and piped loopback cable “P” (blue) traces from avalanches only hitting the southern section are presented (<b>a</b>). Corresponding mean frequency of the entire trace is computed and marked on the trace as well. On right we compare the power spectra from direct buried cable (<b>b</b>) and piped buried (<b>c</b>). The associated log-average power spectra are also plotted.</p>
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<p>Detailed analysis of the most energetic trace from Event 5. The avalanche signal is analyzed using 20 s sliding time window to investigate avalanche dynamics. In (<b>a</b>), the normalized signal is shown in the time domain; (<b>b</b>) presents the mean frequency of the 20 s time window sliding every 1 s; and (<b>c</b>) displays the power spectra of selected time windows. The colored boxes in (<b>a</b>) indicate time windows, which are highlighted with markers in the mean frequency plot (<b>b</b>) and in the power spectra plot (<b>c</b>) in corresponding colors.</p>
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<p>Comparison of avalanche dates with historical data of environmental variables. Temperature, snow depth, rain and wind speed from the region covering October 2022 to May 2024 is obtained from OpenMeteo [<a href="#B69-geohazards-05-00063" class="html-bibr">69</a>] is presented. We have plotted the 200 h moving averaged data to visualize long term trends.</p>
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17 pages, 5082 KiB  
Article
Data-Driven-Based Full Recovery Technology and System for Transformer Insulating Oil
by Feng Chen, Li Wang, Zhiyao Zheng, Bin Pan, Yujia Hu and Kexin Zhang
Energies 2024, 17(24), 6345; https://doi.org/10.3390/en17246345 - 17 Dec 2024
Viewed by 136
Abstract
This study aims to develop an efficient recovery solution for waste transformer insulating oil, addressing the challenge of incomplete separation of residual oil in existing recovery technologies. A multi-module integrated system is constructed, comprising a waste oil extraction module, a residual oil vaporization [...] Read more.
This study aims to develop an efficient recovery solution for waste transformer insulating oil, addressing the challenge of incomplete separation of residual oil in existing recovery technologies. A multi-module integrated system is constructed, comprising a waste oil extraction module, a residual oil vaporization module, an exhaust gas treatment module, and an online monitoring module. By combining steps such as oil extraction, residual oil absorption, hot air circulation heating, and negative-pressure low-frequency induction heating, the complete recovery of waste oil is achieved. The recovery process incorporates oil–gas saturation monitoring and an oil–gas precipitation assessment algorithm based on neural networks to enable intelligent control, ensuring thorough recovery of residual oil from transformers. The proposed system and methods demonstrate excellent recovery efficiency and environmental protection effects during the pre-treatment of waste transformer oil. Experiments conducted on 50 discarded transformers showed an average recovery efficiency exceeding 99%, with 49 transformers exhibiting no damage to core components after the recovery process. From a theoretical perspective, this research introduces monitoring and control methods for transformer insulating oil recovery, providing significant support for the green processing and reutilization of discarded transformer insulating oil. From an application value perspective, the recovery process helps reduce environmental pollution and facilitates the disassembly of transformers. This enables better analysis of transformer operating characteristics, thereby enhancing the reliability and safety of power systems. Full article
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<p>Flowchart of the full recovery process for insulating oil.</p>
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<p>Schematic diagram of the full recovery system for waste transformer insulating oil.</p>
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<p>Full recovery system for waste transformer insulating oil and low-frequency induction heating device. (<b>a</b>) Full recovery system. (<b>b</b>) Low-frequency induction heating device.</p>
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<p>(<b>a</b>) Diagram of the pressure and temperature sensor installation and (<b>b</b>) structural diagram of the oil–gas analyzer.</p>
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<p>The waste transformer and the full oil recovery test. (<b>a</b>) The waste transformation. (<b>b</b>) The full oil recovery test.</p>
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<p>Current, voltage, power, and equivalent resistance waveforms of the low-frequency induction heating device during the recovery process.</p>
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<p>Full oil recovery effect of the waste transformer.</p>
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<p>Full oil recovery failure case.</p>
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11 pages, 1757 KiB  
Article
High-Altitude Discharges and Whistlers of Volcanic Thunderstorms
by Evgeniy I. Malkin, Boris M. Shevtsov, Nina V. Cherneva, Evgeniy A. Kazakov and János Lichtenberger
Atmosphere 2024, 15(12), 1503; https://doi.org/10.3390/atmos15121503 - 17 Dec 2024
Viewed by 132
Abstract
The results of the observations of atmospherics and whistlers initiated by high-altitude electrical discharges that occurred during the eruption of the Kamchatka volcanoes (Bezymianny and Shiveluch (Russia)) on 7 and 10 April 2023 are presented. Recording of atmospherics and associated whistlers was carried [...] Read more.
The results of the observations of atmospherics and whistlers initiated by high-altitude electrical discharges that occurred during the eruption of the Kamchatka volcanoes (Bezymianny and Shiveluch (Russia)) on 7 and 10 April 2023 are presented. Recording of atmospherics and associated whistlers was carried out by a VLF (very low frequencies) radio direction finder. Two-hop whistlers were identified by dispersion coefficient, which corresponded to the double passage of the signal from Kamchatka to Australia and back. The heights of the electric discharges were determined by means of interferograms of direct and reflected from the ionosphere radiofrequency atmospherics. The high-altitude distribution of an electric discharge is obtained, the penetration of which into the ionosphere is responsible for the generation of whistlers. The characteristics of volcanic electrical discharges and whistlers can be used to estimate the height of an explosive eruption. Full article
(This article belongs to the Special Issue Atmospheric Electricity (2nd Edition))
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<p>Proposed phenomenological schemes of volumetric charge separation during eruptive column formation and eruptive cloud propagation. (<b>a</b>) Adapted from Rulenko: I—charge separation under gravity force at the initial section in case of weak wind; II—formation of a cloud at the automodel section under wind effect; III—plume in the floating zone; IV—region of coarse fraction fall; V—region of tephra fall [<a href="#B9-atmosphere-15-01503" class="html-bibr">9</a>]. (<b>b</b>) Adapted from Lane [<a href="#B16-atmosphere-15-01503" class="html-bibr">16</a>]. (<b>c</b>) Adapted from Miura [<a href="#B10-atmosphere-15-01503" class="html-bibr">10</a>].</p>
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<p>(<b>a</b>,<b>e</b>) The number of lightning discharges over 15-min time intervals in the area of Australia. (<b>b</b>,<b>f</b>) Azimuthal distribution of bearings of pulsed electromagnetic radiation in the range of 350°–70°. The count rate of pulsed electromagnetic radiation during eruptions, coming azimuthally from the side of the Bezymianny (<b>c</b>) and Shiveluch (<b>g</b>) volcanoes. Record of explosive earthquakes at the BZM seismic station during the eruption of the Bezymianny volcano on 7 April 2023 (<b>d</b>) and at the BDR seismic station during the eruption of the Shiveluch volcano on 10 April 2023 (<b>h</b>).</p>
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<p>Total daily thunderstorm activity during the eruption of Bezymianny and Shiveluch volcanoes and around their magnetically conjugated regions, x-marker of the lightning stroke.</p>
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<p>Peak frequencies of the vertical electric component signal of the VLF direction finder during the eruption of Bezymianny volcano on 7 April 2023: (<b>a</b>) whistlers initiated by lightning discharges from the Australian thunderstorm center and the eruptive cloud in coordinates (<math display="inline"><semantics> <mrow> <mi>t</mi> <mo>,</mo> <mi>f</mi> </mrow> </semantics></math>) and (<b>b</b>) in coordinates (<math display="inline"><semantics> <mrow> <mi>t</mi> <mo>,</mo> <msup> <mi>f</mi> <mrow> <mo>−</mo> <mn>1</mn> <mo>/</mo> <mn>2</mn> </mrow> </msup> </mrow> </semantics></math>); (<b>c</b>) atmospherics of the initiating thunderstorm discharge of volcanic origin. Slope coefficients <math display="inline"><semantics> <mrow> <msub> <mi>K</mi> <mn>1</mn> </msub> <mo>=</mo> <mrow> <mo>(</mo> <mn>12.5</mn> <mo>±</mo> <mn>1.5</mn> <mo>)</mo> </mrow> <mo>×</mo> <msup> <mn>10</mn> <mrow> <mo>−</mo> <mn>3</mn> </mrow> </msup> <msup> <mi mathvariant="normal">s</mi> <mrow> <mo>−</mo> <mn>1</mn> <mo>/</mo> <mn>2</mn> </mrow> </msup> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <msub> <mi>K</mi> <mn>2</mn> </msub> <mo>=</mo> <mrow> <mo>(</mo> <mn>6.2</mn> <mo>±</mo> <mn>1.5</mn> <mo>)</mo> </mrow> <mo>×</mo> <msup> <mn>10</mn> <mrow> <mo>−</mo> <mn>3</mn> </mrow> </msup> <msup> <mi mathvariant="normal">s</mi> <mrow> <mo>−</mo> <mn>1</mn> <mo>/</mo> <mn>2</mn> </mrow> </msup> </mrow> </semantics></math>. The inset shows the model of electromagnetic wave propagation along a waveguide according to [<a href="#B29-atmosphere-15-01503" class="html-bibr">29</a>]. Time in seconds from the start of the recording is indicated in the figure.</p>
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<p>Peak frequencies of the signal of the vertical electrical component of the VLF direction finder during the eruption of the Shiveluch volcano on 10 April 2023: (<b>a</b>) whistler initiated by a thunderstorm discharge of an eruptive cloud in coordinates (<math display="inline"><semantics> <mrow> <mi>t</mi> <mo>,</mo> <mi>f</mi> </mrow> </semantics></math>) and (<b>b</b>) in coordinates (<math display="inline"><semantics> <mrow> <mi>t</mi> <mo>,</mo> <msup> <mi>f</mi> <mrow> <mo>−</mo> <mn>1</mn> <mo>/</mo> <mn>2</mn> </mrow> </msup> </mrow> </semantics></math>); (<b>c</b>) atmospherics of the initiating thunderstorm discharge of volcanic origin. The slope coefficient <math display="inline"><semantics> <mrow> <msub> <mi>K</mi> <mn>2</mn> </msub> <mo>=</mo> <mrow> <mo>(</mo> <mn>7.62</mn> <mo>±</mo> <mn>1.5</mn> <mo>)</mo> </mrow> <mo>×</mo> <msup> <mn>10</mn> <mrow> <mo>−</mo> <mn>3</mn> </mrow> </msup> <msup> <mi mathvariant="normal">s</mi> <mrow> <mo>−</mo> <mn>1</mn> <mo>/</mo> <mn>2</mn> </mrow> </msup> </mrow> </semantics></math>.</p>
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<p>(<b>a</b>) An interferometry scheme for determining the height of the discharge. (<b>b</b>) The geometry of the difference in the paths of the atmospheric rays during the eruption of the Shiveluch volcano. The symbols 0 and OP indicate the observation point “Karymshina”.</p>
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<p>(<b>a</b>) Interferogram of the model power spectrum for determining the discharge height, (<b>b</b>) Power spectrum of the real atmospheric signal recorded at the reception point at 10:51:43.1857 UTC during the eruption of the Shiveluch volcano on 10 April 2023. (<b>c</b>) Correlation function (convolution) of the model and real signal spectra.</p>
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13 pages, 11990 KiB  
Article
Racing in Kart Dromes: Laboratory and Site Assessment of Noise Levels from Competition and Rental Karts
by Antonella Bevilacqua, Gino Iannace, Luis Gomez-Agustina and Amelia Trematerra
Acoustics 2024, 6(4), 1180-1192; https://doi.org/10.3390/acoustics6040064 - 17 Dec 2024
Viewed by 115
Abstract
Kart racing is one of the hobbies that people get passionate about from a young age. Kart dromes are commonly built in suburban or rural areas, generally surrounded by industrial zones and sporadic residential buildings. The circuits are primarily active during summer, hosting [...] Read more.
Kart racing is one of the hobbies that people get passionate about from a young age. Kart dromes are commonly built in suburban or rural areas, generally surrounded by industrial zones and sporadic residential buildings. The circuits are primarily active during summer, hosting races that often extend into the evening and night hours, where each race has a duration of 20 min. This study examines the noise generated by kart dromes through acoustic measurements conducted at a kart drome located in southern Italy, where a microphone was placed at the side of the circuit for short periods in addition to a survey conducted at the nearest sensitive receptor. Another survey was conducted within the kart drome for a long-term period to record all of the variations in noise levels of a typical summer day when the races are organized during the nighttime; for this type of data, the hourly average values were taken for one week in June, July, and August, highlighting the increasing trend in the noise levels due to the kart races. However, a detailed analysis of noise emissions during different phases of kart operation revealed two significant acoustic events, such as the acceleration of pass-by peaks centered on high frequencies and strong breaking noise at curves that are centered at low-medium frequencies, causing a whistling noise of the wheels while turning the kart. This paper highlights the increasing trend in noise levels during summer nighttime races, compares on-site measurements with laboratory data, and discusses the implications for local communities and noise regulations. Full article
(This article belongs to the Special Issue Vibration and Noise (2nd Edition))
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<p>Aerial view of the kart drome.</p>
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<p>Types of karts: hiring/rental (<b>a</b>) and competition/racing (<b>b</b>).</p>
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<p>Equipment installed at the border of the racing circuit during the evening (<b>a</b>) and nighttime (<b>b</b>).</p>
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<p>Sound pressure level spectra comparison related to hiring/rental and competition/racing karts.</p>
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<p>Noise levels from the competition karts recorded at the side of the circuit for almost 5 min.</p>
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<p>Sound pressure level spectra related to a competition kart running for 2 laps in the circuit: the blue color represents lap No. 1, and the red color represents lap No. 2.</p>
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<p>Noise levels from the rental karts recorded at the side of the circuit for almost 5 min.</p>
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<p>Sound pressure level spectra related to a rental kart running for 2 laps in the circuit: the blue color represents lap No. 1, and the red color represents lap No. 2.</p>
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<p>Frequency spectrum emitted by 5 rental karts measured at the side of the circuit over a 15 min survey.</p>
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<p>Frequency spectrum emitted by 5 rental karts measured in the sensitive receptor over a 15 min survey.</p>
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<p>Microphone installation within the kart drome (<b>a</b>). Weekly averaged results of LAeq (<b>b</b>).</p>
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<p>Frequency spectrograms emitted by a competition kart (<b>a</b>) and a rental kart (<b>b</b>).</p>
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<p>Grid values of 10 karts singularly plotted: laboratory values related to competition karts (<b>a</b>), site values related to competition karts (<b>b</b>), laboratory values related to rental karts (<b>c</b>), and site values related to rental karts (<b>d</b>).</p>
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<p>View of a typical kart racing where multiple vehicles are competing.</p>
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16 pages, 1353 KiB  
Article
Clinical and Radiological Features of an Adenovirus Type 7 Outbreak in Split-Dalmatia County, Croatia, 2022–2023
by Antea Trogrlic, Dina Mrcela, Danijela Budimir Mrsic, Ivana Jukic, Sanda Sardelic, Irena Tabain, Željka Hruskar, Diana Nonkovic, Josko Markic and Mirela Pavicic Ivelja
Pathogens 2024, 13(12), 1114; https://doi.org/10.3390/pathogens13121114 - 17 Dec 2024
Viewed by 215
Abstract
Human adenoviruses (HAdVs) are known to be highly contagious pathogens. They are commonly associated with mild respiratory infections in young children but can also cause severe life-threatening infections. Human adenovirus types 4 and 7 have frequently been reported to cause pneumonia in immunocompetent [...] Read more.
Human adenoviruses (HAdVs) are known to be highly contagious pathogens. They are commonly associated with mild respiratory infections in young children but can also cause severe life-threatening infections. Human adenovirus types 4 and 7 have frequently been reported to cause pneumonia in immunocompetent youths and adults. In this retrospective study, we analyzed the clinical, laboratory, radiological, and microbiological features, as well as the treatment and outcomes of an adenovirus outbreak in 185 patients who were admitted to the Emergency Unit of the Departments of Infectious Diseases and Pediatrics, University Hospital of Split, Croatia, between October 2022 and April 2023. An unusual increase in the frequency of adenovirus pneumonia was observed, especially in adults, followed by respiratory failure and complications such as pulmonary embolism. The most common chest X-ray findings were unilateral patchy opacity and unilateral reticulations (11.6%), followed by unilateral lobar pneumonia (7.1%). The predominant CT presentation was unilateral lobar pneumonia with multiple patchy ground glass opacities (23.5%) or lobar pneumonia with mixed opacities (17.6%). We found a low correlation between Brixia score and C-reactive protein in adults and no correlation in children. Adenovirus type 7 was almost exclusively isolated from patients with pneumonia. Most of our patients with severe or critical adenovirus pneumonia were immunocompetent adults without any medical history. So far, only a few studies have presented the radiological features of HAdV pneumonia, which generally did not reveal lobar pneumonia in a substantial percentage. Our research also demonstrated an unusual presentation of adenovirus infection complicated with pulmonary embolism, which has rarely been reported in previous studies. The aforementioned HAdV outbreak indicates the necessity for further research, especially in the context of effective antiviral therapy and infection prevention. Full article
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<p>Month-by-month distribution of human-adenovirus-positive infections. Blue bar: number of HAdV-infected patients. Red line: number of HAdV-hospitalized patients.</p>
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<p>Correlation between Brixia score and C-reactive protein (mg/L) in patients’ samples.</p>
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<p>Correlation between Brixia score and C-reactive protein (mg/L) in children and adults.</p>
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13 pages, 2004 KiB  
Article
Neutropenia and Felty Syndrome in the Twenty-First Century: Redefining Ancient Concepts in Rheumatoid Arthritis Patients
by Jorge Luis Rodas Flores, Blanca Hernández-Cruz, Víctor Sánchez-Margalet, Ana Fernández-Reboul Fernández, Esther Fernández Panadero, Gracia Moral García and José Javier Pérez Venegas
J. Clin. Med. 2024, 13(24), 7677; https://doi.org/10.3390/jcm13247677 - 17 Dec 2024
Viewed by 196
Abstract
Objectives: To describe the frequency of neutropenia and Felty syndrome in patients with rheumatoid arthritis (RA) attended in routine clinical practice. Methods: We selected by randomization a sample of 270 RA patients attended from January 2014 to November 2022. Demographic, clinical, and neutropenia-related [...] Read more.
Objectives: To describe the frequency of neutropenia and Felty syndrome in patients with rheumatoid arthritis (RA) attended in routine clinical practice. Methods: We selected by randomization a sample of 270 RA patients attended from January 2014 to November 2022. Demographic, clinical, and neutropenia-related variables were collected from the electronic medical records. Neutropenia was defined as having an absolute neutrophil count (ANC) of less than 1500/mm3 once, and acute if it persisted for <3 months. Felty syndrome was defined as RA-related neutropenia, rheumatoid factor (RF) and/or anti citrullinated protein antibody (ACPA) positivity. Results: We found 50 patients who had at least one neutropenia episode, with an incidence of 18.5% (14.0–25.6%). Most were women, with age (mean, p25–p75) at the time of neutropenia of 61.5 (57.4–69.3) years, 85% RF+ and 76% ACPA+. The demographic and RA characteristics of patients with and without neutropenia were very similar, except for sex: most patients with neutropenia were women. The 50 patients had 99 episodes of neutropenia; 59% were acute. The lower ANC was 1240 (1000–1395) mm3, and most of the episodes were mild (74%). In 32% of cases, there was other cytopenia. The RA activity measured by DAS28 in patients with neutropenia was low, at 2.18 (1.75–2.97). A total of 82 of 99 neutropenia episodes were related to DMARDs, 60% to Anti-IL6 drugs in monotherapy, 13% to RA activity, 3% to infectious diseases and 1% to hematologic malignancy. There were five (1.8%) cases with Felty syndrome, but only one woman with the classic combination of RA, positivity of autoantibodies (RF and ACPA), neutropenia and splenomegaly. Conclusions: In the 21st century, neutropenia in RA patients is most commonly related to biologics, mostly IL6 inhibitors and methotrexate. Episodes are mild, acute, with low RA activity, and associated with severe infections in few cases. Felty syndrome is rare. Full article
(This article belongs to the Special Issue Rheumatoid Arthritis: Current Status and Future Challenges)
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<p>Hands of patient with Felty syndrome. She has characteristics swan neck deformity, metacarpophalangeal subluxation and ulnar blunt.</p>
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<p>Anteroposterior hand X-ray with subluxation of the metacarpophalangeal and interphalangeal joints of first fingers, and erosions in metacarpal heads and proximal interphalangeal heads.</p>
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<p>Splenomegaly with spleen of 14 cm.</p>
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<p>Flow cytometry dot plots that show absence of clonal expansion of NK cells expressing or not CD8+.</p>
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20 pages, 3279 KiB  
Article
Slot Occupancy-Based Collision Avoidance Algorithm for Very-High-Frequency Data Exchange System Network in Maritime Internet of Things
by Sol-Bee Lee, Jung-Hyok Kwon, Bu-Young Kim, Woo-Seong Shim, Taeshik Shon and Eui-Jik Kim
Appl. Sci. 2024, 14(24), 11751; https://doi.org/10.3390/app142411751 - 16 Dec 2024
Viewed by 374
Abstract
The maritime industry is undergoing a paradigm shift driven by rapid advancements in wireless communication and an increase in maritime traffic data. However, the existing automatic identification system (AIS) struggles to accommodate the increasing maritime traffic data, leading to the introduction of the [...] Read more.
The maritime industry is undergoing a paradigm shift driven by rapid advancements in wireless communication and an increase in maritime traffic data. However, the existing automatic identification system (AIS) struggles to accommodate the increasing maritime traffic data, leading to the introduction of the very-high-frequency (VHF) data exchange system (VDES). While the VDES increases bandwidth and data rates, ensuring the stable transmission of maritime IoT (MIoT) application data in congested coastal areas remains a challenge due to frequent collisions of AIS messages. This paper presents a slot occupancy-based collision avoidance algorithm (SOCA) for a VDES network in the MIoT. SOCA is designed to mitigate the impact of interference caused by transmissions of AIS messages on transmissions of VDE-Terrestrial (VDE-TER) data in coastal areas. To this end, SOCA provides four steps: (1) construction of the neighbor information table (NIT) and VDES frame maps, (2) construction of the candidate slot list, (3) TDMA channel selection, and (4) slot selection for collision avoidance. SOCA operates by constructing the NIT based on AIS messages to estimate the transmission intervals of AIS messages and updating VDES frame maps upon receiving VDES messages to monitor slot usage dynamically. After that, it generates a candidate slot list for VDE-TER channels, classifying the slots into interference and non-interference categories. SOCA then selects a TDMA channel that minimizes AIS interference and allocates slots with low expected occupancy probabilities to avoid collisions. To evaluate the performance of SOCA, we conducted experimental simulations under static and dynamic ship scenarios. In the static ship scenario, SOCA outperforms the existing VDES, achieving improvements of 13.58% in aggregate throughput, 11.50% in average latency, 33.60% in collision ratio, and 22.64% in packet delivery ratio. Similarly, in the dynamic ship scenario, SOCA demonstrates improvements of 7.30%, 11.99%, 39.27%, and 11.82% in the same metrics, respectively. Full article
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<p>VDES functions and frequency usage.</p>
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<p>VDES frame structure.</p>
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<p>VDE-TER default slotmap.</p>
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<p>Example of ship scenarios: (<b>a</b>) static ship scenario and (<b>b</b>) dynamic ship scenario.</p>
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<p>Aggregate throughput: (<b>a</b>) static ship scenario and (<b>b</b>) dynamic ship scenario.</p>
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<p>Average latency: (<b>a</b>) static ship scenario and (<b>b</b>) dynamic ship scenario.</p>
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<p>Collision ratio: (<b>a</b>) static ship scenario and (<b>b</b>) dynamic ship scenario.</p>
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<p>Packet delivery ratio: (<b>a</b>) static ship scenario and (<b>b</b>) dynamic ship scenario.</p>
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