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Appl. Sci., Volume 14, Issue 16 (August-2 2024) – 581 articles

Cover Story (view full-size image): The vehicle–road collaborative intelligence approach has become an industry consensus. It can efficiently tackle the technical hurdles and reduce the performance requirements and costs of on-board perception and computing devices. In this paper, we present a model for distributing perception and computing capabilities between vehicle-side and roadside, ensuring that the needs of various autonomous driving levels are met. Meanwhile, the collaborative intelligence approach will also introduce the costs of intelligent infrastructure deployment, energy, and maintenance. Different roads have varying scene characteristics and usage intensities. It is necessary to conduct a cost-effectiveness analysis of the intelligent deployment of different road types. View this paper
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16 pages, 6376 KiB  
Article
Strength and Vibration Analysis of Axial Flow Compressor Blades Based on the CFD-CSD Coupling Method
by Haiwei Lin, Hong Bao, Huaihuai Zhang, Feifei Zhao and Junli Wang
Appl. Sci. 2024, 14(16), 7432; https://doi.org/10.3390/app14167432 - 22 Aug 2024
Viewed by 1132
Abstract
During the operational process of an axial-flow compressor, the blade structure is simultaneously subjected to both aerodynamic loads and centrifugal loads, posing significant challenges to the safe and reliable operation of the blades. Considering both centrifugal loads and aerodynamic loads comprehensively, a bidirectional [...] Read more.
During the operational process of an axial-flow compressor, the blade structure is simultaneously subjected to both aerodynamic loads and centrifugal loads, posing significant challenges to the safe and reliable operation of the blades. Considering both centrifugal loads and aerodynamic loads comprehensively, a bidirectional CFD-CSD coupling analysis method for blade structure was established. The Navier–Stokes governing equations were utilized to solve the internal flow field of the axial-flow compressor. The conservative interpolation method was utilized to couple and solve the blade’s static equilibrium equation, and the deformation, stress distribution, and prestress modal behavior of compressor blades were mainly analyzed. The research results indicate that the maximum deformation of the blades occurred at the lead edge tip, while stress predominantly concentrated approximately 33% upward from the blade root, exhibiting a radial distribution that gradually decreased. As the rotational speed increased, the maximum deformation of the blades continuously increased. Furthermore, at a constant rotational speed, the maximum deformation of the blade exhibited a trend of first increasing and then decreasing with the increase in mass flow. In contrast, the maximum stress showed a trend of first increasing, then decreasing, and finally increasing again as the rotational speed continuously increased. Centrifugal loads are the primary factor influencing blade stress and natural frequency. During operation, the blades exhibited two resonance points, approximately occurring at 62% and 98% of the design rotational speed. Full article
(This article belongs to the Topic Fluid Mechanics, 2nd Edition)
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<p>Process diagram of the bidirectional CFD-CSD coupled method.</p>
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<p>Computation results with different turbulence models.</p>
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<p>Test positions and computational domain of the NASA Rotor37 transonic rotor flow field.</p>
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<p>The blade flow field model and boundary condition schematic diagram.</p>
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<p>The blade structural field model and boundary condition schematic diagram.</p>
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<p>Schematic of blade single passage meshing.</p>
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<p>Mesh diagrams near the blade for different numbers of nodes.</p>
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<p>Mesh independence study.</p>
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<p>Comparison of calculated and experimental compressor characteristics.</p>
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<p>Deformation and equivalent stress of blades under aerodynamic load.</p>
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<p>Deformation and equivalent stress of blades under centrifugal load.</p>
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<p>Deformation and equivalent stress of blades under centrifugal and aerodynamic loads.</p>
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<p>Deformation and stress of blades at different rotational speeds under load.</p>
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<p>Variation of maximum deformation and maximum equivalent stress of blades at different rotational speeds with mass flow.</p>
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<p>The Campbell diagram of an axial flow compressor blade.</p>
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12 pages, 2366 KiB  
Article
Study of the Improvement of Disintegration Efficiency and Antibacterial Properties of Disposable Toilet Seat Cover Sheet Made of Cellulose Fibers
by Ju-Hyun Park, Chul-Hwan Kim, Hyeong-Hun Park, Tae-Gyeong Lee, Min-Sik Park and Jae-Sang Lee
Appl. Sci. 2024, 14(16), 7431; https://doi.org/10.3390/app14167431 - 22 Aug 2024
Viewed by 752
Abstract
The growing prevalence of disposable toilet seat covers in public restrooms stems from concerns about personal hygiene, given the direct contact between the seat and various users’ skin. To enable these disposable cover sheets to be flushed down the toilet instead of being [...] Read more.
The growing prevalence of disposable toilet seat covers in public restrooms stems from concerns about personal hygiene, given the direct contact between the seat and various users’ skin. To enable these disposable cover sheets to be flushed down the toilet instead of being discarded in the trash, they must possess specific properties. These include rapid water absorption for quick disintegration, strength to endure user movement or moisture on the toilet seat surface, and a comfortable texture. To address these challenges, the study investigated the disintegration characteristics of flushable cover sheets prepared under different refining conditions. Alkyl ketene dimer (AKD) was also employed to enhance water resistance, while an organic antibacterial agent was used to impart antimicrobial properties. The findings revealed that adding 0.2% AKD and 1% organic antibacterial agent to pulp stock with a freeness of about 650 mL CSF was suitable for manufacturing disposable cover sheets with disintegration characteristics like toilet tissue paper. Full article
(This article belongs to the Section Applied Industrial Technologies)
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<p>Simultaneous measurement device for the Stöckigt sizing degree and contact angle: (<b>a</b>) automatic sizing tester; (<b>b</b>) contact angle on the cover sheet.</p>
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<p>Comparison of disintegration rate of the disposable toilet cover sheets according to varying freeness and AKD addition levels.</p>
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<p>The SEM image of the surface structure of the cover sheet made from refined pulp fibers.</p>
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<p>Comparison of sizing degrees and contact angles of the disposable toilet seat cover sheets according to varying freeness and AKD addition levels: (<b>a</b>) sizing degree; (<b>b</b>) contact angle.</p>
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<p>Comparison of surface roughness of toilet cover sheets made from pulp stocks with different freeness.</p>
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<p>Tensile strength and surface roughness of toilet seat cover sheets made from pulp stocks with different freeness.</p>
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<p>Comparison of the antibacterial effect of the toilet seat cover sheets.</p>
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16 pages, 5319 KiB  
Article
Experimental Investigation of Heat Dissipation of Lithium–Ion Cells and Its Correlation with Internal Resistance
by Stefan Michael Peringer, Yash Kotak and Hans-Georg Schweiger
Appl. Sci. 2024, 14(16), 7430; https://doi.org/10.3390/app14167430 - 22 Aug 2024
Viewed by 774
Abstract
Power loss is a limiting factor for batteries and individual cells. The resulting heat generation due to the power loss leads to reduced battery performance and, thus, lower efficiency. These losses are largely due to the internal resistance of the cells. Therefore, it [...] Read more.
Power loss is a limiting factor for batteries and individual cells. The resulting heat generation due to the power loss leads to reduced battery performance and, thus, lower efficiency. These losses are largely due to the internal resistance of the cells. Therefore, it is important to accurately determine the value of the internal resistance of lithium–ion cells. From the literature, it was found that there are three widely used internal resistance-measurement methods (current step method, direct-energy-loss method, and calorimeter measurement), with negligible research on their comparison demonstrating the most efficient method. Henceforth, to find the most optimal method, this research adopts all three methods on a variety of cell chemistries, including Lithium-ion Manganese Oxide (LMO), Lithium Iron Phosphate (LFP), Nickel Manganese Cobalt (NMC), and Lithium Titanium-Oxide (LTO) for different c-rates (1 C, 2 C, and 3 C), with a wide temperature range (from 0 °C to 40 °C). Full article
(This article belongs to the Special Issue Electric Vehicle Battery: Materials and Safety)
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<p>Research plan of the presented work.</p>
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<p>The structure of a calorimeter is formed by a vacuum flask containing the lithium–ion cell inside a liquid with a thermometer and a calorifier [<a href="#B7-applsci-14-07430" class="html-bibr">7</a>].</p>
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<p>Structure of the measurement setup.</p>
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<p>Circuit diagram of a measurement setup.</p>
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<p>Flowchart of the measurement cycle.</p>
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<p>Example of area-compensation method from the measurements. The black curve represents the measured temperature inside the calorimeter. The red lines are the extrapolated resting phases necessary for the determination of the temperature differences. The blue lines are the determined temperature differences from the area-compensation method.</p>
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<p>Measurement results for the internal resistance of the LMO cells at 1 C, 2 C, and 3 C from temperature 0 °C to 40 °C.</p>
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<p>Measurement results for the internal resistance of the LFP cell at 1 C, 2 C, and 3 C from temperature 0 °C to 40 °C.</p>
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<p>Measurement results for the internal resistance of the NMC cell at 1 C, 2 C, and 3 C from temperature 0 °C to 40 °C.</p>
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<p>Measurement results for the internal resistance of the LTO cell at 1 C, 2 C, and 3 C from temperature 0 °C to 40 °C.</p>
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20 pages, 3607 KiB  
Review
Microbial Diversity of Biodeteriorated Limestone Cultural Heritage Assets Identified Using Molecular Approaches—A Literature Review
by Hana Suchy, Polona Zalar and Maria Filomena Macedo
Appl. Sci. 2024, 14(16), 7429; https://doi.org/10.3390/app14167429 - 22 Aug 2024
Viewed by 1144
Abstract
A significant part of our stone heritage is made of limestone. Researchers are increasingly concerned about the risk of biodeterioration of these important objects. In this article, we present an up-to-date review of the microbial diversity of biodeteriorated limestone cultural heritage (CHL). This [...] Read more.
A significant part of our stone heritage is made of limestone. Researchers are increasingly concerned about the risk of biodeterioration of these important objects. In this article, we present an up-to-date review of the microbial diversity of biodeteriorated limestone cultural heritage (CHL). This is based on an extensive bibliographic search of the literature investigating biodiversity using culture-dependent (CD) and culture-independent (CI) techniques. In the case of the former, only articles in which microorganisms were identified using molecular tools that generate DNA sequences were selected, with the aim of providing traceable identification based on the sequences submitted to public databases. The literature search resulted in the selection of 50 articles published between 2004 and 2023. The biodiversity data obtained from the CHL were organized into the following groups: fungi (626 records), bacteria and cyanobacteria (786 and 103 records, respectively), algae (51 records), and archaea (27 records). Within each group, the microbial diversity studied was compared according to results obtained using CD and CI techniques. Of all the articles selected, 12 used both approaches, demonstrating the growing effort to discover the total microbiome of biodeteriorated cultural heritage assets. Full article
(This article belongs to the Special Issue Application of Biology to Cultural Heritage III)
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<p>Biodeteriorated limestone outdoor monument of Aristotle, located at Dornava mansion (Slovenia) from the middle of 18th century. The statue shows discoloration phenomena and superficial disintegration of limestone. This photo was taken by Maja Gutman Levstek.</p>
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<p>The number of studies on biodeteriorated limestone using molecular identification approaches by country marked up on the world map in different colors according to the number of articles.</p>
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<p>Biodiversity of microbial groups on damaged CHL with molecular identification (1403 records).</p>
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<p>Fungi on damaged limestone cultural heritage. (<b>A</b>) Fungal genera identified using CD approaches (397 records obtained from 24 cultural heritage sites); (<b>B</b>) Fungal genera identified using CI approaches (229 records obtained from 13 cultural heritage sites).</p>
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<p>Bacteria on damaged limestone cultural heritage. (<b>A</b>) Bacterial genera identified using CD approaches (256 records obtained from 19 cultural heritage sites); (<b>B</b>) Bacterial genera identified using CI approaches (530 records obtained from 21 cultural heritage sites).</p>
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<p>Cyanobacteria on damaged limestone cultural heritage. (<b>A</b>) Cyanobacterial genera identified using CD approaches (53 records obtained from 12 cultural heritage sites); (<b>B</b>) Cyanobacterial genera identified using CI approaches (50 records obtained from 14 cultural heritage sites).</p>
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<p>Algae identified on damaged limestone cultural heritage. (<b>A</b>) Algal genera identified using CD approaches (39 records obtained from 3 cultural heritage sites); (<b>B</b>) Genera of algae identified using CI approaches (12 records obtained from 5 cultural heritage sites).</p>
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<p>Archaea on damaged limestone cultural heritage identified using CI approaches (26 records obtained from 4 cultural heritage sites).</p>
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<p>The number of molecular biology studies on CHL conducted using CD approaches, CI approaches, and both CD and CI approaches together through the years in ascending order.</p>
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12 pages, 1836 KiB  
Article
Adaptability of Swiss Stone Pine (Pinus cembra) in Two Different Environmental Conditions of Romanian Carpathians
by Marius Budeanu, Flaviu Popescu, Emanuel Besliu and Ecaterina Nicoleta Apostol
Appl. Sci. 2024, 14(16), 7428; https://doi.org/10.3390/app14167428 - 22 Aug 2024
Viewed by 738
Abstract
Swiss stone pine (Pinus cembra) is a feasible solution for increasing the resistance of future mixed spruce–pine stands to windfall at the upper altitudinal limit of Romanian forests. This study aims to analyze the adaptability of ten full-sib families in two [...] Read more.
Swiss stone pine (Pinus cembra) is a feasible solution for increasing the resistance of future mixed spruce–pine stands to windfall at the upper altitudinal limit of Romanian forests. This study aims to analyze the adaptability of ten full-sib families in two different environmental conditions and their evolution in time for predicting forward selection. At a seedling age of 33, evaluations were carried out for survival rate (Sr), growth (diameter at breast height—Dbh, and trees’ height), and branch traits, as well as for stem straightness. The high level of genetic variability, inheritance rate, and trait–trait correlations, registered in both trials, ensure the success of the breeding program. The Swiss stone pine shows a very good adaptation on high-sloping lands from the upper altitudinal limit of Romania’s forests, with the cross-pollinated (CP) families registering a 28.5% better survival in the Rodna trial (34° slope) compared to the Păltiniș experiment (7° slope). The consanguineous families registered only an 11% Sr in Păltiniș, while in the Rodna trial, the Sr was four times higher (in both trials, consanguineous trees were dominated). The juvenile–adult correlations of growth traits were significant, indicating that early selection could be efficient. The forward selection of the best 10% of CP families for Dbh could be applied, ensuring a 9% to 15% genetic gain. Full article
(This article belongs to the Special Issue Ecosystems and Landscape Ecology)
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<p>Location of the Păltiniş and Rodna field trials (red triangles) and provenance origins (red circle) on the <span class="html-italic">Pinus cembra</span> distribution map [<a href="#B36-applsci-14-07428" class="html-bibr">36</a>]. Natural species distribution is hatched (<b>A</b>). Regional climate trends (<b>B</b>) in the mean annual temperature (lines) and total precipitation (columns) for the trials during the last 28 years were computed using the climate downscaling tool [<a href="#B34-applsci-14-07428" class="html-bibr">34</a>].</p>
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<p>Survival of the CP common mothers in replications in the Rodna (<b>A</b>) and Păltiniș (<b>B</b>) trials (mean ± SD).</p>
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<p>Dbh and Th of the CP mothers in the Rodna (<b>A</b>,<b>C</b>) and Păltiniș (<b>B</b>,<b>D</b>) trials (significant differences expressed by different letters resulted by applying Tukey’s HSD post hoc test).</p>
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27 pages, 5458 KiB  
Article
Numerical Modeling and Analysis of Pendant Installation Method Dynamics Using Absolute Nodal Coordinate Formulation
by Yongkang Chen, Shiping He and Xinhao Luo
Appl. Sci. 2024, 14(16), 7427; https://doi.org/10.3390/app14167427 - 22 Aug 2024
Viewed by 715
Abstract
Accurately simulating the deployment process of coupled systems in deep-sea environments remains a significant challenge. This study employs the Absolute Nodal Coordinate Formulation (ANCF) to dynamically model and analyze multi-body systems based on the Pendant Installation Method (PIM). Utilizing the principle of energy [...] Read more.
Accurately simulating the deployment process of coupled systems in deep-sea environments remains a significant challenge. This study employs the Absolute Nodal Coordinate Formulation (ANCF) to dynamically model and analyze multi-body systems based on the Pendant Installation Method (PIM). Utilizing the principle of energy conversion, this study calculates the stiffness, generalized elastic forces, mass matrices, and Morison equation, formulating a motion equation for the dynamic coupling of nonlinear time-domain forces in cables during pendulum deployment, which is numerically solved using the implicit generalized-α method. By comparing the simulation results of this model with those from the catenary theory model, the advanced modeling capabilities of this model are validated. Lastly, the sensitivity of the multi-body system under various boundary conditions is analyzed. The results indicate that deployment operations are more effective in environments with strong ocean currents. Furthermore, upon comparing the impacts of structural mass and deployment depth on the system, it was found that deployment depth has a more significant effect. Consequently, the findings of this study provide a scientific basis for formulating subsequent optimization strategies. Full article
(This article belongs to the Special Issue The Applications of Nonlinear Dynamics in Materials and Structures)
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<p>Flowchart of cantilever deployment.</p>
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<p>ANCF framework and coordinate system.</p>
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<p>Tangent and normal directions denoted by <math display="inline"><semantics> <mstyle mathvariant="bold" mathsize="normal"> <msup> <mi>r</mi> <mo>′</mo> </msup> </mstyle> </semantics></math> and <math display="inline"><semantics> <mstyle mathvariant="bold" mathsize="normal"> <msup> <mi>r</mi> <mo>″</mo> </msup> </mstyle> </semantics></math>.</p>
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<p>Diagram of vector direction decomposition.</p>
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<p>Concentrated load acting on the cantilever beam.</p>
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<p>Deformation diagram of cantilever beam under end concentrated load.</p>
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<p>Flexible free oscillation beam model.</p>
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<p>Time history diagram of vertical displacement of the free end.</p>
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<p>Falling flexible pendulum at different time steps.</p>
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<p>Model coordinate system.</p>
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<p>(<b>a</b>) Time history diagram of axial force at the structural connection and horizontal displacement at the center of mass. (<b>b</b>) Vertical displacement at the structure’s center of mass.</p>
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<p>(<b>a</b>) Time history diagram of horizontal velocity at the structure’s center of mass. (<b>b</b>) Vertical velocity at the center of mass.</p>
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<p>(<b>a</b>) Time history diagram of axial force at the cable–structure connection under different flow velocities. (<b>b</b>) Horizontal displacement at the center of mass. (<b>c</b>) Vertical displacement at the center of mass. (<b>d</b>) Vertical velocity at the center of mass. (<b>e</b>) Horizontal velocity at the center of mass. (<b>f</b>) Enlarged time history diagram of horizontal velocity at the center of mass.</p>
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<p>(<b>a</b>) Time history of axial force at the structural connection and horizontal displacement at the center of mass under different structural masses. (<b>b</b>) Vertical displacement at the center of mass. (<b>c</b>) Horizontal velocity at the center of mass. (<b>d</b>) Enlarged time history of horizontal velocity at the center of mass. (<b>e</b>) Vertical velocity at the center of mass.</p>
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<p>(<b>a</b>) Time history of axial force at the connection between cable and structure under different total cable lengths. (<b>b</b>) Horizontal displacement at the center of mass. (<b>c</b>) Vertical displacement at the center of mass. (<b>d</b>) Horizontal velocity at the center of mass. (<b>e</b>) Vertical velocity at the center of mass.</p>
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23 pages, 4001 KiB  
Article
Enhancing Firewall Packet Classification through Artificial Neural Networks and Synthetic Minority Over-Sampling Technique: An Innovative Approach with Evaluative Comparison
by Adem Korkmaz, Selma Bulut, Tarık Talan, Selahattin Kosunalp and Teodor Iliev
Appl. Sci. 2024, 14(16), 7426; https://doi.org/10.3390/app14167426 - 22 Aug 2024
Viewed by 1236
Abstract
Firewall packet classification is a critical component of network security, demanding precise and reliable methods to ensure optimal functionality. This study introduces an advanced approach that combines Artificial Neural Networks (ANNs) with various data balancing techniques, including the Synthetic Minority Over-sampling Technique (SMOTE), [...] Read more.
Firewall packet classification is a critical component of network security, demanding precise and reliable methods to ensure optimal functionality. This study introduces an advanced approach that combines Artificial Neural Networks (ANNs) with various data balancing techniques, including the Synthetic Minority Over-sampling Technique (SMOTE), ADASYN, and BorderlineSMOTE, to enhance the classification of firewall packets into four distinct classes: ‘allow’, ‘deny’, ‘drop’, and ‘reset-both’. Initial experiments without data balancing revealed that while the ANN model achieved perfect precision, recall, and F1-Scores for the ‘allow’, ‘deny’, and ‘drop’ classes, it struggled to accurately classify the ‘reset-both’ class. To address this, we applied SMOTE, ADASYN, and BorderlineSMOTE to mitigate class imbalance, which led to significant improvements in overall classification performance. Among the techniques, the ANN combined with BorderlineSMOTE demonstrated superior efficacy, achieving a 97% overall accuracy and consistently high performance across all classes, particularly in the accurate classification of minority classes. In contrast, while SMOTE and ADASYN also improved the model’s performance, the results with BorderlineSMOTE were notably more balanced and reliable. This study provides a comparative analysis with existing machine learning models, highlighting the effectiveness of the proposed approach in firewall packet classification. The synthesized results validate the potential of integrating ANNs with advanced data balancing techniques to enhance the robustness and reliability of network security systems. The findings underscore the importance of addressing class imbalance in machine learning models, particularly in security-critical applications, and offer valuable insights for the design and improvement of future network security infrastructures. Full article
(This article belongs to the Special Issue Progress and Research in Cybersecurity and Data Privacy)
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<p>Firewall dataset classification attribute data distribution.</p>
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<p>Research methodology steps.</p>
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<p>Artificial neural network structure.</p>
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<p>Minority class member generation diagram based on SMOTE algorithm [<a href="#B44-applsci-14-07426" class="html-bibr">44</a>].</p>
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<p>Confusion matrix output of the study.</p>
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<p>Accuracy and loss graphs of training and validation metrics of ANN’s analysis.</p>
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<p>Confusion matrix output of study with ANNs + SMOTE function.</p>
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<p>Accuracy and loss graphs of training and validation metrics of ANNs + SMOTE analysis.</p>
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<p>Confusion matrix output of study with ANNs + ADASYN function.</p>
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<p>Accuracy and loss graphs of training and validation metrics of ANNs + ADASYN analysis.</p>
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<p>Confusion matrix output of study with ANNs + BorderlineSMOTE function.</p>
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<p>Accuracy and loss graphs of training and validation metrics of ANNs + BorderlineSMOTE analysis.</p>
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12 pages, 4607 KiB  
Communication
Simulation Study of Dynamic Rotation and Deformation for Plasmonic Electric Field-Skyrmions
by Gao Tang, Chunyan Bai, Saima Kanwal, Zhening Zhao and Dawei Zhang
Appl. Sci. 2024, 14(16), 7425; https://doi.org/10.3390/app14167425 - 22 Aug 2024
Viewed by 838
Abstract
The topological properties of optical skyrmions in confined electromagnetic fields are perfectly presented through spin vectors and electric-field vectors. However, currently, electric-field optical skyrmions in surface plasmon polaritons are mostly presented in the form of a Néel type. Most control strategies involve linear [...] Read more.
The topological properties of optical skyrmions in confined electromagnetic fields are perfectly presented through spin vectors and electric-field vectors. However, currently, electric-field optical skyrmions in surface plasmon polaritons are mostly presented in the form of a Néel type. Most control strategies involve linear directional movement, and topological manipulation methods are monotonous. We specifically propose a multi-arc symmetric slit array, which generates skyrmions from the surface plasmon polariton (SPP) field under excitation of a linearly polarized Gaussian light-source array and exhibits strong dependence processes on the rotation, deformation, and phase distribution of the incident light source. We also discuss the independence and synthesis of deformation and rotation related to phase difference and positions of regulation, respectively, which provide the possibility for rich deformations under different rotation states. Our work extends new ideas for the dynamic control of plasmonic skyrmions, which is of great significance to fields such as spin photonics and nano-positioning. Full article
(This article belongs to the Section Optics and Lasers)
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<p>The schematic diagram of SPP waves generated by quadrilateral, triangle, and hexagonal linear slits is shown in the top view in (<b>a</b>–<b>c</b>). The schematic diagram using six and multiple red linear slits to equivalently replace the grey arc-shaped slits in the black dashed lines is shown, respectively, in (<b>d</b>,<b>e</b>).</p>
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<p>Multi-arc symmetric slit array excited by 12 incident beams with varying phases, as shown in the three-dimensional view in (<b>a</b>). The slit array is indicated by red shading distributed on the Ag surface, the distance from the outer side to the center of the structure <b><span class="html-italic">D</span></b> by yellow dashed arrows, and the distance from the inner side of each arc-shaped slit to the center of the structure <b><span class="html-italic">D</span></b> by green dashed arrows, as shown in the top view in (<b>b</b>). The distributed phase of the SPP waves is indicated by yellow, standard Néel-type optical skyrmions before phase modulation in (<b>c</b>). The polarization direction of sources is indicated by blue arrows in (<b>a</b>,<b>c</b>), and the incident direction of sources is indicated by purple.</p>
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<p>The value of the squared electric field in the X–Y plane. Based on the morphology mentioned above, the rotational characteristics of the skyrmions are labeled specifically in (<b>a</b>–<b>d</b>). The blue dashed lines in (<b>a</b>–<b>d</b>) contain the generated skyrmions and their topological domain walls. The yellow dashed arrow indicates the long axis direction of the skyrmion under the deformation, and the green dashed arrow indicates the direction of the positive X-axis. The corresponding positions of regulated slits are shown in (<b>e</b>–<b>h</b>). Specifically, the blue dashed arrow indicates the direction of the position vector of the regulated slits, which pass through the center of the arc-shaped slit structure. Therefore, we clearly indicate in <a href="#applsci-14-07425-t001" class="html-table">Table 1</a> the different conditions of the phase value that need to be set to obtain the results.</p>
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<p>The value of the squared electric field in the X–Y plane. Based on the morphology mentioned above, the rotational characteristics of the skyrmions are labeled specifically in (<b>a</b>–<b>d</b>). The blue dashed lines in (<b>a</b>–<b>d</b>) contain the generated skyrmions and their topological domain walls. The yellow dashed arrow indicates the long axis direction of the skyrmion under the deformation, and the green dashed arrow indicates the direction of the positive X-axis. The corresponding positions of regulated slits are shown in (<b>e</b>–<b>h</b>). Specifically, the blue dashed arrow indicates the direction of the position vector of the regulated slits, which pass through the center of the arc-shaped slit structure. Therefore, we clearly indicate in <a href="#applsci-14-07425-t001" class="html-table">Table 1</a> the different conditions of the phase value that need to be set to obtain the results.</p>
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<p>The different patterns of electric field skyrmions under the regulations for a combination of different positions of slits or different phase differences: (<b>a</b>) The skyrmions deform to the right in the horizontal direction: the skyrmion shape gradually flattens from circular to broken to the right, and the number of skyrmions is no longer equal to 1; however, the topological type is still Néel–type; (<b>b</b>) Under an acute–angle rotation state, different degrees of deformation are applied to the skyrmion: the shape of the skyrmion gradually changes from circular to irregular–circular until it breaks; (<b>c</b>) The skyrmion deforms in the vertical direction: the deformation process is equivalent to (<b>a</b>), but here the deformation direction is upward, which is equivalent to the result of the process in (<b>a</b>) in a right–angle rotation state.</p>
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<p>The different patterns of electric field skyrmions under the regulations for a combination of different positions of slits or different phase differences: (<b>a</b>) The skyrmions deform to the right in the horizontal direction: the skyrmion shape gradually flattens from circular to broken to the right, and the number of skyrmions is no longer equal to 1; however, the topological type is still Néel–type; (<b>b</b>) Under an acute–angle rotation state, different degrees of deformation are applied to the skyrmion: the shape of the skyrmion gradually changes from circular to irregular–circular until it breaks; (<b>c</b>) The skyrmion deforms in the vertical direction: the deformation process is equivalent to (<b>a</b>), but here the deformation direction is upward, which is equivalent to the result of the process in (<b>a</b>) in a right–angle rotation state.</p>
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<p>The top view of the three-dimensional SPP electric field vector.</p>
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<p>The top view of the corresponding positions of regulated slits in <a href="#applsci-14-07425-f004" class="html-fig">Figure 4</a>b.</p>
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<p>The top view of the SPP electric field under the regulations for a process involving the dynamic deformations of skyrmions.</p>
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14 pages, 6402 KiB  
Article
Anatomical-Based Customized Cervical Orthosis Design in Automation
by Yu-Ching Hsiao, Chung-De Chen, Yi-Hsiu Wu and Jing-Jing Fang
Appl. Sci. 2024, 14(16), 7424; https://doi.org/10.3390/app14167424 - 22 Aug 2024
Viewed by 764
Abstract
Cervical orthoses, vital for neck immobilization in medical care and sports, often struggle to provide adequate support due to individual neck shape and size variations. This study addresses this issue by developing a specific computer-aided orthosis design software tailored for creating customized 3D-printed [...] Read more.
Cervical orthoses, vital for neck immobilization in medical care and sports, often struggle to provide adequate support due to individual neck shape and size variations. This study addresses this issue by developing a specific computer-aided orthosis design software tailored for creating customized 3D-printed cervical orthoses. The self-developed software embedded anatomical and rehabilitation knowledge into the orthosis design process, ensuring consistency and reducing manual modification. Finite element analysis of cervical orthoses determined that a minimum thickness of 5 mm PLA (polylactic acid) material is necessary to meet safety requirements. This study highlights the automation potential of customized computer-aided orthosis design and underscores the potential to revolutionize orthopedic care. We also applied easy-to-access 3D printing technology to fabricate well-fitting and immobilized cervical orthoses. These customized cervical orthoses offer a promising future with the advantages of being cost-effective, lightweight, immobility, comfortable, easy to wear, and minimal accessories to meet clinical needs, enhancing patient comfort and compliance and providing reassurance about the economic benefits of the technology. Full article
(This article belongs to the Section Applied Biosciences and Bioengineering)
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<p>(<b>a</b>) The designed cervical orthosis. (<b>b</b>) The anatomical features below the cervical orthosis.</p>
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<p>The design workflow for cervical orthoses.</p>
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<p>Bipartite graph of 12 features.</p>
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<p>The neck coordinate system.</p>
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<p>(<b>a</b>) Relationship between neck Cartesian coordinates (<span class="html-italic">x</span>, <span class="html-italic">y</span>, <span class="html-italic">z</span>) and cylindrical coordinates (<span class="html-italic">r</span>, <span class="html-italic">θ</span>, <span class="html-italic">h</span>). (<b>b</b>) Unfolded graph of the front piece of the cervical orthosis. (<b>c</b>) Centerline of the two-piece cervical orthosis.</p>
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<p>The centerline template (<b>a</b>) before and (<b>b</b>) after being symmetrized.</p>
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<p>The customization procedure from template to individual.</p>
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<p>Normalization and de-normalization processes in the central line.</p>
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<p>Fixed points and loading points for the finite element analysis: (<b>a</b>) the front piece, (<b>b</b>) the back piece.</p>
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<p>Stress analysis of different thicknesses of orthosis (<b>a</b>) the front piece, (<b>b</b>) the back piece.</p>
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<p>Stress contours for cervical orthosis with thickness of 3 mm (<b>a</b>) the front piece under flexion, (<b>b</b>) the back piece under extension.</p>
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27 pages, 6449 KiB  
Article
Design of a Digital Platform for Carbon Generalized System of Preferences Communities Based on the TAO Model of Three-Way Decisions
by Huilan Wei, Chendan Yang, Chuanye Wen and Yanlong Wang
Appl. Sci. 2024, 14(16), 7423; https://doi.org/10.3390/app14167423 - 22 Aug 2024
Cited by 1 | Viewed by 985
Abstract
The increasing carbon dioxide emissions from human activities present a significant global concern, with approximately two-thirds of greenhouse gas emissions attributed to household activities. The Carbon Generalized System of Preferences (CGSP) has emerged as a pivotal mechanism to incentivize voluntary carbon reduction in [...] Read more.
The increasing carbon dioxide emissions from human activities present a significant global concern, with approximately two-thirds of greenhouse gas emissions attributed to household activities. The Carbon Generalized System of Preferences (CGSP) has emerged as a pivotal mechanism to incentivize voluntary carbon reduction in community households. This paper examines the development of a community digital management platform designed to incentivize voluntary carbon reduction at the community level, highlighting the critical role of reducing emissions in urban community life to meet carbon peak and neutrality targets. This study employs the TAO model of Three-Way Decision to establish a closed-loop operational framework for the CGSP digital platform. The platform features a Trisection mechanism to record and quantify low-carbon behaviors, an Action mechanism to classify and reward community members, and an Outcome mechanism to assess overall community carbon reduction achievements. Additionally, a user interface tailored for community users is developed to enhance platform accessibility. The proposed platform presents a practical and innovative solution for exploring emission reduction potential in urban communities. By systematically recording low-carbon behaviors, providing targeted rewards, and conducting comprehensive assessments, the platform aims to guide community residents in adopting sustainable practices. This study offers a valuable reference for the digital transformation, intelligent system construction, and development of new urban functional units within communities. Full article
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<p>Rough Set Three-Way decision-making model. Source: Yao, Y. The Superiority of Three-Way Decisions in Probabilistic Rough Set Models. Information Sciences 2011, 181, 1080–1096, doi:10.1016/j.ins.2010.11.019 [<a href="#B27-applsci-14-07423" class="html-bibr">27</a>].</p>
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<p>Basic Theoretical Framework of the TAO Model. Source: Jiang, C.; Guo, D.; Sun, L. Effectiveness Measure for TAO Model of Three-Way Decisions with Interval Set. IFS 2021, 40, 11071–11084, doi:10.3233/JIFS-202207 [<a href="#B28-applsci-14-07423" class="html-bibr">28</a>].</p>
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<p>Subject layer of the community Carbon Generalized System of Preferences digital platform. Source: own processing.</p>
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<p>Means layer of the community Carbon Generalized System of Preferences digital platform. Source: own processing.</p>
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<p>Carbon-inclusive community digital platform scenario layer. Source: own processing.</p>
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<p>Mechanisms for the operation of community digital platforms. Source: own processing.</p>
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<p>Types of incentive strategies. Source: own processing.</p>
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<p>Community Carbon Generalized System of Preferences Digital management platform workflow diagram. Source: own processing.</p>
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<p>Overall architecture diagram of the Community Carbon Generalized System of Preferences digital platform. Source: own processing.</p>
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<p>Data flow diagram design. Source: own processing.</p>
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<p>Functional architecture diagram. Source: own processing.</p>
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<p>Public platform and application user interface design. Source: own processing.</p>
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<p>Experimental program. Source: own processing.</p>
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11 pages, 1305 KiB  
Systematic Review
Accuracy of Implant Placement Using Digital Prosthetically-Derived Surgical Guides: A Systematic Review
by Cristian Abad-Coronel, Stefan Vandeweghe, María Dolores Vela Cervantes, María José Tobar Lara, Nancy Mena Córdova and Paulina Aliaga
Appl. Sci. 2024, 14(16), 7422; https://doi.org/10.3390/app14167422 - 22 Aug 2024
Viewed by 1580
Abstract
Dental implant placement is crucial in oral rehabilitation, requiring precision for successful outcomes. Digital technologies, including surgical guides, enhance predictability and efficiency in implant procedures. However, their impact on implant positioning accuracy is still under investigation. This systematic review aimed to evaluate the [...] Read more.
Dental implant placement is crucial in oral rehabilitation, requiring precision for successful outcomes. Digital technologies, including surgical guides, enhance predictability and efficiency in implant procedures. However, their impact on implant positioning accuracy is still under investigation. This systematic review aimed to evaluate the literature on implant accuracy using digital prosthetically-derived surgical guides. Registered in PROSPERO (CRD 42023483194), the review employed a PICO strategy and searched PubMed for English-language, in vivo studies from 2013 to 2023 on restrictive digital prosthetically-derived surgical guides. Two reviewers independently assessed records, with a third verifying the decisions. PRISMA guidelines were followed, yielding 24 results after excluding nine duplicates. Ten studies met the criteria after title, abstract, and keyword review, with three included after verification. These studies showed coronal deviations of 0.44 mm to 0.56 mm, apical deviations of 0.64 mm to 1.03 mm, angular deviations of 2.03° to 2.42°, and vertical deviations of 0.19 mm to 0.45 mm. Superior accuracy was noted with static guided techniques, while bilateral guides offered stability and printed guides were cost-effective. A surgical guide that comes from a planning with a primary wax-up of the prosthesis leads to the placement of a dental implant that can be functionally and esthetically rehabilitated. Further research is needed to standardize outcomes and improve implant protocols and patient outcomes. Full article
(This article belongs to the Special Issue Advances in Dental Implants)
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<p>Workflow chart of implant placement using digital prosthetically-derived surgical guides.</p>
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<p>Search flowchart according to PRISMA guidelines (n = number of records).</p>
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31 pages, 2364 KiB  
Review
Biochar Amendment in Green Roof Substrate: A Comprehensive Review of the Benefits, Performance, and Challenges
by Cuong Ngoc Nguyen, Hing-Wah Chau, Apurv Kumar, Ayon Chakraborty and Nitin Muttil
Appl. Sci. 2024, 14(16), 7421; https://doi.org/10.3390/app14167421 - 22 Aug 2024
Viewed by 1067
Abstract
Green roofs (GRs) are a well-established green infrastructure (GI) strategy that have been extensively studied for decades to address a growing array of social and environmental challenges. Research efforts have been continuously made to contribute to the awareness of benefits of GRs and [...] Read more.
Green roofs (GRs) are a well-established green infrastructure (GI) strategy that have been extensively studied for decades to address a growing array of social and environmental challenges. Research efforts have been continuously made to contribute to the awareness of benefits of GRs and towards their widespread application. The substrate, which is one of the crucial layers of a GR system, plays a major role in the serviceability of GRs. Thus, several studies have been undertaken to alter the substrate characteristics by applying innovative substrate additives. Biochar, a carbon-rich material with a highly porous structure and large specific surface area, has been found advantageous in several areas such as agriculture, water filtration, environmental remediation, construction, and so on. However, the application of biochar in GRs has been insufficiently studied, partially because biochar amendment in GRs is a relatively recent innovation. Furthermore, a comprehensive review of the performance of biochar-amended GR substrates is lacking. This review paper aims to summarize the past performance of GRs enhanced with biochar by considering the various benefits that biochar offers. The results indicate that most of the reviewed studies observed increased retention of runoff and nutrients when utilizing biochar. Additionally, the capabilities of biochar in improving thermal insulation, plant performance, and microbial diversity, as well as its effectiveness in sequestrating carbon and controlling soil erosion, were mostly agreed upon. Notwithstanding, a definitive conclusion cannot yet be confidently made due to the limited research information from biochar–GR systems and the uneven research focus observed in the studies reviewed. The influence of biochar-related variables (including amendment rates, application methods, processed forms, and particle size) on the effectiveness of biochar was also discussed. Opportunities for future research were suggested to fill the research gaps and address challenges restricting the application of biochar in GRs. Detailed information from past research findings could serve as a foundation for further investigations into the large-scale implementation of biochar in GRs. Full article
(This article belongs to the Section Green Sustainable Science and Technology)
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<p>The number of studies on biochar-amended green roofs and biochar recorded in the Scopus database by year of publication from 2011 to 2023.</p>
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<p>The number of studies on green roofs and biochar using different search keywords in the Scopus database.</p>
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<p>A flow chart depicting the reviewing methodology used in this research.</p>
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<p>A flow chart illustrating the benefits of biochar in green roofs.</p>
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<p>Mechanisms by which biochar increases soil porosity and improves water-holding capacity: (<b>a</b>) low-porosity soil structure without biochar, (<b>b</b>) high-porosity soil structure due to inter-pores between soil and biochar and intra-pores within biochar particles [<a href="#B56-applsci-14-07421" class="html-bibr">56</a>].</p>
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<p>Commonly used biochar application methods in green roofs: (<b>a</b>) biochar at the bottom of the substrate, (<b>b</b>) biochar in the middle of the substrate, (<b>c</b>) biochar at the top of the substrate, and (<b>d</b>) biochar thoroughly mixed with the substrate.</p>
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<p>The number of studies examining the benefits of biochar in green roofs.</p>
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<p>The number of studies on biochar-amended green roofs by country.</p>
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22 pages, 38189 KiB  
Article
Visual Odometry in GPS-Denied Zones for Fixed-Wing Unmanned Aerial Vehicle with Reduced Accumulative Error Based on Satellite Imagery
by Pablo Mateos-Ramirez, Javier Gomez-Avila, Carlos Villaseñor and Nancy Arana-Daniel
Appl. Sci. 2024, 14(16), 7420; https://doi.org/10.3390/app14167420 - 22 Aug 2024
Cited by 1 | Viewed by 1270
Abstract
In this paper, we present a method for estimating GPS coordinates from visual information captured by a monocular camera mounted on a fixed-wing tactical Unmanned Aerial Vehicle at high altitudes (up to 3000 m) in GPS-denied zones. The main challenge in visual odometry [...] Read more.
In this paper, we present a method for estimating GPS coordinates from visual information captured by a monocular camera mounted on a fixed-wing tactical Unmanned Aerial Vehicle at high altitudes (up to 3000 m) in GPS-denied zones. The main challenge in visual odometry using aerial images is the computation of the scale due to irregularities in the elevation of the terrain. That is, it is not possible to accurately convert from pixels in the image to meters in space, and the error accumulates. The contribution of this work is a reduction in the accumulated error by comparing the images from the camera with satellite images without requiring the dynamic model of the vehicle. The algorithm has been tested in real-world flight experiments at altitudes above 1000 m and in missions over 17 km. It has been proven that the algorithm prevents an increase in the accumulated error. Full article
(This article belongs to the Special Issue Advances in Unmanned Aerial Vehicle (UAV) System)
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<p>The blue path represents the Ground Truth measured by the GPS sensor. The path starts at the green marker and ends at the red marker, measuring approximately 18 km. We used Google Earth to visualize the data (Google Earth is a trademark of Google LLC).</p>
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<p>First and final photo. It is assumed that GPS signal is lost when the first photo is taken and it is not restored along the entire trajectory.</p>
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<p>Flowchart of the visual odometry phase. The algorithm starts when the GPS signal is lost. The first step is to take two consecutive images and find correspondences between keypoints (represented with the red lines). Then, we calculate the displacement between the centroids of the point clouds (represented with the red dots) <math display="inline"><semantics> <msup> <mi>d</mi> <mrow> <mo>(</mo> <mi>p</mi> <mi>x</mi> <mo>)</mo> </mrow> </msup> </semantics></math> in pixel units; these point clouds are the keypoints corresponding to the good matches. This displacement is converted to meters and added to the previous coordinate (in UTM). Finally, the result is transformed into latitude/longitude coordinates, and the process is repeated with the next image.</p>
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<p>Matches between consecutive images. The red lines connect the pixels from the first image with their corresponding ones in the second image. The figure shows the best 200 matches.</p>
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<p>Matches between consecutive images. The figure shows, with red lines, the matches between keypoints with <math display="inline"><semantics> <mrow> <mi>ρ</mi> <mo>&lt;</mo> <mn>300</mn> </mrow> </semantics></math>.</p>
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<p>Elevation map used for this study (<a href="#applsci-14-07420-f001" class="html-fig">Figure 1</a>). Geodetic reference data: the datum corresponds to ITRF92 epoch 1988.0, GRS80 ellipsoid, geographic coordinates.</p>
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<p>Comparison of GPS coordinate estimation against the flight path (ground truth), represented with the blue markers, using different values (<math display="inline"><semantics> <mrow> <mi>δ</mi> <mo>=</mo> <mn>0.0005</mn> <mi>p</mi> <msup> <mi>x</mi> <mrow> <mo>−</mo> <mn>1</mn> </mrow> </msup> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>δ</mi> <mo>=</mo> <mn>0.001</mn> <mi>p</mi> <msup> <mi>x</mi> <mrow> <mo>−</mo> <mn>1</mn> </mrow> </msup> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>δ</mi> <mo>=</mo> <mn>0.0015</mn> <mi>p</mi> <msup> <mi>x</mi> <mrow> <mo>−</mo> <mn>1</mn> </mrow> </msup> </mrow> </semantics></math>) and its error accumulation.</p>
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<p>Preprocessing flowchart (offline preprocessing). This process ensures the best keypoints are maintained to compare the real-time application. We included images of every subprocess for a better understanding, but they are shown better in <a href="#sec3dot2dot1-applsci-14-07420" class="html-sec">Section 3.2.1</a>, <a href="#sec3dot2dot2-applsci-14-07420" class="html-sec">Section 3.2.2</a> and <a href="#sec3dot2dot3-applsci-14-07420" class="html-sec">Section 3.2.3</a>.</p>
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<p>Example (3D) of RRT* path planning over a section of Hidalgo State in Mexico. We show the final path. Geodetic reference data: the datum corresponds to ITRF92 epoch 1988.0, GRS80 ellipsoid, geographic coordinates. In (<b>b</b>), we use a colormap to represent elevation and the ∗ symbol represent the calculated flight plan.</p>
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<p>Demonstration of the number of keypoints present in the satellite image. In the flight plan area, 68,061 keypoints have been identified, which are shown in (<b>b</b>).</p>
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<p>Satellite image keypoints filtered based on their proximity to the flight plan defined by the user and represented with the red line in (<b>a</b>).</p>
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<p>Distance histogram and its fitted exponential decay probability distribution.</p>
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<p>Map of filtered keypoints based on the flight plan.</p>
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<p>Quad-tree scheme. It divides a space into four quadrants or regions, recursively breaking down each quadrant into smaller sub-quadrants. This process continues until a specified level of detail is reached or the region contains no more than a certain number of data points [<a href="#B67-applsci-14-07420" class="html-bibr">67</a>].</p>
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<p>Offset from the keypoint to the image center. The red dots represent the matched keypoint, and the yellow dotted arrow is the offset to the the center of the image, which is marked with the red cross.</p>
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<p>Flowchart of our algorithm: The keypoints of the satellite image are computed offline. Then, during the flight, we compute the visual odometry phase and apply a correction if we find a keypoint from the satellite image.</p>
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<p>Output of the correction algorithm.</p>
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<p>Filtered output of the correction algorithm using the Kalman Filter.</p>
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<p>Filtered output of the correction algorithm.</p>
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11 pages, 5201 KiB  
Article
An Innovative Heating Solution for Sustainable Agriculture: A Feasibility Study on the Integration of Phase Change Materials as Passive Heating Elements
by Stephan M. Thaler, Josef Zwatz, Pascal Nicolay, Robert Hauser and Roman Lackner
Appl. Sci. 2024, 14(16), 7419; https://doi.org/10.3390/app14167419 - 22 Aug 2024
Cited by 1 | Viewed by 891
Abstract
In this study, we investigate an innovative option for the ecological management of agricultural land. The focus is on the use of phase change materials (PCMs) for passive temperature regulation in greenhouses and fruit crop fields in order to reduce yield losses due [...] Read more.
In this study, we investigate an innovative option for the ecological management of agricultural land. The focus is on the use of phase change materials (PCMs) for passive temperature regulation in greenhouses and fruit crop fields in order to reduce yield losses due to unforeseen late frost events. The use of PCMs represents a novel approach to enhancing crop growth and extending growing seasons without relying on conventional energy-intensive methods, providing a stable microclimate that can protect plants from cold stress. This passive regulation of temperature helps to reduce the need for fossil fuel-based heating systems, thereby lowering greenhouse gas emissions and operational costs. The application of PCMs in agricultural settings is particularly innovative as it leverages naturally occurring temperature variations to create a self-sustaining, low-maintenance solution that aligns with the principles of sustainable farming. This approach not only improves energy efficiency but also contributes to the resilience of agricultural practices in the face of climate variability. This study focuses on the possible use of PCMs in passive heating modules for the protection of potted plants in greenhouses. Various PCMs such as paraffin, beeswax, and shea butter were tested. Experiments were then conducted, using one kind of paraffin-based PCM, in a specially designed module. In addition, an FEM simulation model (CFD) was built and tested. The model was used to perform detailed analyses of the heat transfer efficiency, fluid dynamics, and overall performance of the modules. The model can also be used for optimization purposes (e.g., efficiency improvements). Full article
(This article belongs to the Special Issue New Insights on Environmentally Friendly Materials)
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<p>Specific stored heat vs. temperature behavior. PCM is compared to sensitive materials, where ∆Q PCM is significantly higher than ∆Q sensitive in the melting range [<a href="#B21-applsci-14-07419" class="html-bibr">21</a>].</p>
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<p>Experimentally determined cooling curves of RT5HC, beeswax, and shea butter.</p>
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<p>PCM-based concept for the protection of free-standing fruit trees (<b>left</b>) and potted plants in greenhouses (<b>right</b>).</p>
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<p>Three-dimensional model of the module for the protection of free-standing fruit trees.</p>
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<p>Fully 3D-printed module (PLA).</p>
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<p>Module with galvanized steel sheet to improve thermal conduction.</p>
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<p>CFD simulation model. (<b>Left</b>): cross-section of the 3D model, including the “fluid body” (PCM) in red. (<b>Right</b>): position of the temperature sensor (red disc) used for the experimental measurement of temperature over time in the fabricated modules (dimensions in mm).</p>
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<p>Paraffin RT5HC—partial enthalpy distribution [<a href="#B22-applsci-14-07419" class="html-bibr">22</a>].</p>
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<p>Measurement setup for the characterization of the potted plant protection modules.</p>
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<p>Experimentally determined cooling curve of fully 3D-printed PLA and PLA–metal module.</p>
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<p>Temperature distribution after 30 min (<b>left</b>) and 60 min (<b>right</b>).</p>
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<p>Temperature distribution after 360 min (<b>left</b>) and 540 min (<b>right</b>).</p>
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<p>Simulated temperature behavior of PLA and PLA–metal modules.</p>
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16 pages, 11725 KiB  
Article
Simulation Analysis and Experiment of Piezoelectric Pump with Tapered Cross-Section Vibrator
by Caiqi Hu, Wei Jiang, Xiaoqi Hu, Jing Ji, Shengduo Li and Qingbo Zhang
Appl. Sci. 2024, 14(16), 7418; https://doi.org/10.3390/app14167418 - 22 Aug 2024
Viewed by 821
Abstract
In order to meet the requirements of microfluidic transport in the fields of medical, health, and microelectromechanical integration, a valve-less piezoelectric pump with a tapered cross-sectional vibrator was designed according to the bionic principles of fish swimming. Through theoretical analysis, the pattern of [...] Read more.
In order to meet the requirements of microfluidic transport in the fields of medical, health, and microelectromechanical integration, a valve-less piezoelectric pump with a tapered cross-sectional vibrator was designed according to the bionic principles of fish swimming. Through theoretical analysis, the pattern of fluid flow in the pump chamber caused by the vibration of the piezoelectric vibrator was derived. The flow field of the piezoelectric pump was analyzed through simulation based on multiple physical fields coupling using the software of COMSOL Multiphysics (version 6.1). The velocity field distribution and its change law were obtained, and the fluid disturbance and instantaneous motion suppression phenomena were acquired as well. Based on the analysis of flow field streamline, the rule of generating vortexes was found. Thus, the driving mechanism of the vibrator with the tapered cross-section, which was consistent with the swimming principle of a fish tail, was verified. A prototype pump was made, and the pump performance was tested. The experimental data showed that the tested flow rate changed in the same trend as the simulated flow rate. When the driving voltage was 150 V and the driving frequency was 588 Hz, the pump achieved a maximum output flow rate of 367.7 mL/min. These results indicated that the piezoelectric pump with the tapered cross-sectional vibrator has great potential of fluid transportation. Full article
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<p>Structure of the piezoelectric pump.</p>
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<p>Bionic contrast diagram of the tapered cross-section vibrator. (<b>a</b>) Schematic diagram of the correspondence relationship between the piezoelectric vibrator and the fish-shaped body. (<b>b</b>) Vibration mode of the vibrator.</p>
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<p>Schematic diagram of the tapered cross-section vibrator substrate.</p>
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<p>Structure of the tapered cross-section vibrator.</p>
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<p>Simplified model of the pump vibrator.</p>
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<p>Centrifugal force on a fluid particle.</p>
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<p>Mesh model of the piezoelectric pump.</p>
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<p>Fluid streamline diagram in the pump chamber (the vortices are marked by red circles).</p>
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<p>Fluid velocity field in the pump chamber.</p>
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<p>Schematic diagram of the vibrator node.</p>
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<p>Fluid velocity distribution at the vibrator tail region during period T. (<b>a-1</b>) Amplitude curve of point P. (<b>a-2</b>) Vibrator tail position at the beginning. (<b>a-3</b>) Fluid velocity distribution at the beginning. (<b>b-1</b>) Amplitude curve of point P. (<b>b-2</b>) Vibrator tail position at T/8. (<b>b-3</b>) Fluid velocity distribution at T/8. (<b>c-1</b>) Amplitude curve of point P. (<b>c-2</b>) Vibrator tail position at T/4. (<b>c-3</b>) Fluid velocity distribution at T/4. (<b>d-1</b>) Amplitude curve of point P. (<b>d-2</b>) Vibrator tail position at 3T/8. (<b>d-3)</b> Fluid velocity distribution at 3T/8. (<b>e-1</b>) Amplitude curve of point P. (<b>e-2</b>) Vibrator tail position at T/2. (<b>e-3</b>) Fluid velocity distribution at T/2. (<b>f-1</b>) Amplitude curve of point P. (<b>f-2</b>) Vibrator tail position at 5T/8. (<b>f-3</b>) Fluid velocity distribution at 5T/8. (<b>g-1</b>) Amplitude curve of point P (<b>g-2</b>) Vibrator tail position at 3T/4 (<b>g-3</b>) Fluid velocity distribution at 3T/4. (<b>h-1</b>) Amplitude curve of point P. (<b>h-2</b>) Vibrator tail position at 7T/8. (<b>h-3</b>) Fluid velocity distribution at 7T/8. (<b>i-1</b>) Amplitude curve of point P. (<b>i-2</b>) Vibrator tail position at T. (<b>i-3</b>) Fluid velocity distribution at T.</p>
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<p>Fluid velocity distribution at the vibrator tail region during period T. (<b>a-1</b>) Amplitude curve of point P. (<b>a-2</b>) Vibrator tail position at the beginning. (<b>a-3</b>) Fluid velocity distribution at the beginning. (<b>b-1</b>) Amplitude curve of point P. (<b>b-2</b>) Vibrator tail position at T/8. (<b>b-3</b>) Fluid velocity distribution at T/8. (<b>c-1</b>) Amplitude curve of point P. (<b>c-2</b>) Vibrator tail position at T/4. (<b>c-3</b>) Fluid velocity distribution at T/4. (<b>d-1</b>) Amplitude curve of point P. (<b>d-2</b>) Vibrator tail position at 3T/8. (<b>d-3)</b> Fluid velocity distribution at 3T/8. (<b>e-1</b>) Amplitude curve of point P. (<b>e-2</b>) Vibrator tail position at T/2. (<b>e-3</b>) Fluid velocity distribution at T/2. (<b>f-1</b>) Amplitude curve of point P. (<b>f-2</b>) Vibrator tail position at 5T/8. (<b>f-3</b>) Fluid velocity distribution at 5T/8. (<b>g-1</b>) Amplitude curve of point P (<b>g-2</b>) Vibrator tail position at 3T/4 (<b>g-3</b>) Fluid velocity distribution at 3T/4. (<b>h-1</b>) Amplitude curve of point P. (<b>h-2</b>) Vibrator tail position at 7T/8. (<b>h-3</b>) Fluid velocity distribution at 7T/8. (<b>i-1</b>) Amplitude curve of point P. (<b>i-2</b>) Vibrator tail position at T. (<b>i-3</b>) Fluid velocity distribution at T.</p>
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<p>Fluid velocity distribution at the vibrator tail region during period T. (<b>a-1</b>) Amplitude curve of point P. (<b>a-2</b>) Vibrator tail position at the beginning. (<b>a-3</b>) Fluid velocity distribution at the beginning. (<b>b-1</b>) Amplitude curve of point P. (<b>b-2</b>) Vibrator tail position at T/8. (<b>b-3</b>) Fluid velocity distribution at T/8. (<b>c-1</b>) Amplitude curve of point P. (<b>c-2</b>) Vibrator tail position at T/4. (<b>c-3</b>) Fluid velocity distribution at T/4. (<b>d-1</b>) Amplitude curve of point P. (<b>d-2</b>) Vibrator tail position at 3T/8. (<b>d-3)</b> Fluid velocity distribution at 3T/8. (<b>e-1</b>) Amplitude curve of point P. (<b>e-2</b>) Vibrator tail position at T/2. (<b>e-3</b>) Fluid velocity distribution at T/2. (<b>f-1</b>) Amplitude curve of point P. (<b>f-2</b>) Vibrator tail position at 5T/8. (<b>f-3</b>) Fluid velocity distribution at 5T/8. (<b>g-1</b>) Amplitude curve of point P (<b>g-2</b>) Vibrator tail position at 3T/4 (<b>g-3</b>) Fluid velocity distribution at 3T/4. (<b>h-1</b>) Amplitude curve of point P. (<b>h-2</b>) Vibrator tail position at 7T/8. (<b>h-3</b>) Fluid velocity distribution at 7T/8. (<b>i-1</b>) Amplitude curve of point P. (<b>i-2</b>) Vibrator tail position at T. (<b>i-3</b>) Fluid velocity distribution at T.</p>
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<p>Flow rate of simulation.</p>
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<p>Prototype of the piezoelectric pump.</p>
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<p>Schematic diagram of flow test.</p>
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<p>Pump flow test.</p>
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<p>Test–simulation flow rate contrast.</p>
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<p>Flow rate comparison result between simulation and test.</p>
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17 pages, 4852 KiB  
Article
Mechanism of Rejuvenation in Aged SBS-Modified Asphalt by Density Functional Theory
by Ping Li, Zhanghui Li and Shenyang Cao
Appl. Sci. 2024, 14(16), 7417; https://doi.org/10.3390/app14167417 - 22 Aug 2024
Viewed by 641
Abstract
As a large area of SBS-modified asphalt pavement entered the maintenance period, the aging and rejuvenation of SBS-modified asphalt have attracted attention in recent years. In order to further study the rejuvenation of aged SBS-modified asphalt, both rheological experiments and quantum mechanical simulations [...] Read more.
As a large area of SBS-modified asphalt pavement entered the maintenance period, the aging and rejuvenation of SBS-modified asphalt have attracted attention in recent years. In order to further study the rejuvenation of aged SBS-modified asphalt, both rheological experiments and quantum mechanical simulations were used. Complex shear modulus (G*) and phase angle (δ) were used to analyze the rejuvenation effect of aged SBS-modified asphalt. Electron density, binding energy (Ebinding), and charge transfer number (Qtransfer) were used to observe the process of rejuvenation in aged SBS-modified asphalt. The results show that compared to asphalt components, SBS polymer was the least stable and most susceptible to breaking. After oxidative aging, SBS polymer with its aging products could impair the rejuvenation in aged asphalt. The interaction between aromatic components in rejuvenator and asphaltenes in aged asphalt was unstable and could be influenced by asphalt aging level. The interaction between heavy component molecules in aged asphalt with saturate component molecules in rejuvenator are closer than those with aromatic components molecules. The binding energies between saturate components in rejuvenator and asphaltenes in aged asphalt could be served as an evaluation indicator of rejuvenation. Full article
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<p>Li and Greenfield twelve-component model (carbon atoms are gray, hydrogen atoms are white, oxygen atoms are red, sulfur atoms are yellow, and nitrogen atoms are blue).</p>
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<p>Four-component model of rejuvenator. (Carbon atoms are gray, hydrogen atoms are white, oxygen atoms are red, sulfur atoms are yellow, and nitrogen atoms are blue).</p>
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<p>SBS molecular model (styrene molecules are yellow; butadiene molecules are green).</p>
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<p>(<b>a</b>) SBS molecular aging product 1; (<b>b</b>) SBS molecular aging product 2.</p>
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<p>Layer models of aromatic components molecules in rejuvenator (stick model) with asphalt (ball and stick model) and SBS molecules (ball and stick model)” Usually, different colors represent different atoms. SBS molecules are only colored to distinguish them from the asphalt molecules.</p>
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<p>Electron density of SBS-modified asphalt components.</p>
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<p>(<b>a</b>) Effect of temperature on <span class="html-italic">G</span>*; (<b>b</b>) effect of temperature on <span class="html-italic">δ</span>.</p>
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<p>(<b>a</b>) Effect of temperature on rutting factor; (<b>b</b>) effect of temperature on fatigue factor.</p>
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<p><span class="html-italic">E</span><sub>binding</sub> between light components in rejuvenator and heavy components in aged SBS-modified asphalt.</p>
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<p>Elastic transformation rate of SBS-modified asphalt in different aging levels.</p>
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<p><span class="html-italic">Q</span><sub>transfer</sub> between light components in rejuvenator and heavy components in aged SBS-modified asphalt.</p>
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10 pages, 1807 KiB  
Article
Indoor Visible Light Fingerprint Location Method Based on Marine Predator Algorithm-Optimized Least Squares Support Vector Machine
by Yuanjia Mei and Yong Deng
Appl. Sci. 2024, 14(16), 7416; https://doi.org/10.3390/app14167416 - 22 Aug 2024
Viewed by 554
Abstract
To increase the accuracy of indoor visible light positioning, a novel indoor visible light localization technique based on the marine predator algorithm-optimized least squares support vector machine (MPA-LSSVM) is suggested. The light signals of each reference point are recorded in the first place [...] Read more.
To increase the accuracy of indoor visible light positioning, a novel indoor visible light localization technique based on the marine predator algorithm-optimized least squares support vector machine (MPA-LSSVM) is suggested. The light signals of each reference point are recorded in the first place and a fingerprint database is created. Introduced thereafter is the marine predator algorithm, which, through iterative optimization of the hyperparameters of the least squares support vector machine, aims to establish an optimal localization model using finely-tuned hyperparameters. This culminated in the development of a positioning model, successfully attaining the objective of enhancing accuracy in positioning while minimizing time expenditure. In an indoor-positioning scene (size: 1 m × 1 m × 1 m), the average positioning error of the proposed positioning method is 0.041 m, and the proportion of test points with positioning errors less than 0.1 m is 96.7%. Full article
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<p>The model of indoor visible light positioning system.</p>
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<p>The flowchart of MPA-LSSVM fingerprint locating model.</p>
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<p>The experimental platform.</p>
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<p>The histogram of positioning error.</p>
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<p>The cumulative distribution of positioning errors.</p>
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26 pages, 26499 KiB  
Article
Numerical Modeling for Tunnel Lining Optimization
by Jose Francisco Suárez-Fino and Juan M. Mayoral
Appl. Sci. 2024, 14(16), 7415; https://doi.org/10.3390/app14167415 - 22 Aug 2024
Viewed by 916
Abstract
The construction of tunnels excavated by the conventional method in densely populated urban environments requires an adequate characterization of the loads acting on the primary lining during the excavation process, to ensure that the ground is deformed and stresses around the tunnel are [...] Read more.
The construction of tunnels excavated by the conventional method in densely populated urban environments requires an adequate characterization of the loads acting on the primary lining during the excavation process, to ensure that the ground is deformed and stresses around the tunnel are relieved, simultaneously complying with the failure and serviceability limits of international standards while minimizing damage to nearby structures. In this paper, common lining design criteria are revisited, through the numerical simulation of an instrumented tunnel section which is part of a 4.5 km long metro line currently under construction in Mexico City. Key needs for improvement in current design approaches are identified. The tunnel was instrumented with load cells, extensometers, and topographical references for convergences and divergences. A three-dimensional finite difference model of the instrumented section was developed, and the load transfer mechanisms between the excavated soil and the primary lining were analyzed. Then, the numerical simulation of the contribution of the secondary lining in the overall stability for sustained load was established, along with the expected ground settlements, which can significantly affect nearby structures. Results gathered from this research are key for updating lining design criteria for urban tunnels built in stiff brittle soils. Full article
(This article belongs to the Special Issue High-Reliability Structures and Materials in Civil Engineering)
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<p>Project trace and geotechnical zoning of Mexico City.</p>
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<p>Soil profile and tunnel at the studied site.</p>
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<p>Tunnel cross-section and primary lining configuration used.</p>
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<p>Schematic tunneling process [<a href="#B29-applsci-14-07415" class="html-bibr">29</a>]. (I) Stage 1, (II) Stage 2, (III) Stage 3, and (IV) Stage 4.</p>
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<p>Excavation of the complete upper half section with a central core. It shows the poor quality of the soil and the presence of water seepage.</p>
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<p>Schematic representation of the tunnel instrumentation: (<b>a</b>) inside the tunnel and (<b>b</b>) topographical elevation survey references, modified from [<a href="#B29-applsci-14-07415" class="html-bibr">29</a>].</p>
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<p>Drilling for the installation of the extensometer and measurement of the instrument. Photographs taken by the author, 2021.</p>
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<p>Measurement of convergences during the excavation of the upper half section. Photographs taken by the author, 2021.</p>
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<p>Maneuvers during the instrumentation of radial cells. Photographs taken by the author, 2021.</p>
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<p>Finally, the pressure transducers are protected with steel ducts and are channeled to the Datalogger where they are connected. Photographs taken by the author, 2021.</p>
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<p>Placement of the first layer of shotcrete with 10 cm thick fibers, covering the periphery of the tunnel vault and the instrumented radial pressure cells. Photographs taken by the author, 2021.</p>
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<p>Photograph showing the connection of the instruments to the Datalogger. Once connected, the first readings are taken on a laptop using the Logger Net software version 4.5.</p>
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<p>Measured vertical ground movements at the tunnel crown in the control section (the arrow indicates the tunnelling direction).</p>
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<p>Convergences and divergences, EM-7, located 20 m before the control section.</p>
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<p>Convergences and divergences, EM-6, located 10 m before the control section.</p>
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<p>Convergences and divergences, EM-5, located 5 m before the control section.</p>
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<p>Convergences and divergences, EM-4, located at the control section.</p>
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<p>Convergences and divergences, EM-3, placed 5 m after the control section.</p>
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<p>Convergences and divergences, EM-2, placed 10 m after the control section.</p>
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<p>Convergences and divergences, EM-1, placed 20 m after the control section.</p>
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<p>Surface points to monitor settlements in the control section.</p>
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<p>Extensometer measurements.</p>
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<p>Recorded radial pressures.</p>
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<p>Recorded axial pressures.</p>
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<p>Three-dimensional mesh of finite differences: (<b>a</b>) global domain of the model; (<b>b</b>) discretization of construction stages.</p>
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<p>Evolution of SFRC stress–strength relationship over time.</p>
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<p>Settlements recorded and predicted on the surface above the tunnel axis and on the tunnel crown.</p>
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<p>Unconfined compression test stress–strain relationship of the tuff soils.</p>
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<p>Measured and predicted ground movements at (<b>a</b>) tunnel crown and (<b>b</b>) sidewalls, respectively.</p>
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<p>Pressures measured and predicted on the primary lining: (<b>a</b>) radial; (<b>b</b>) axial.</p>
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<p>Measured and predicted convergences at the monitoring section in the secondary lining.</p>
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<p>(<b>a</b>) Ground reaction and support reaction curves, calculated with analytical methods and with the calibrated numerical model, and (<b>b</b>) longitudinal displacement profiles, LDPs, calculated with analytical methods and with the calibrated numerical model [<a href="#B25-applsci-14-07415" class="html-bibr">25</a>,<a href="#B44-applsci-14-07415" class="html-bibr">44</a>,<a href="#B47-applsci-14-07415" class="html-bibr">47</a>,<a href="#B48-applsci-14-07415" class="html-bibr">48</a>,<a href="#B49-applsci-14-07415" class="html-bibr">49</a>].</p>
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<p>Displacement contours around the tunnel calculated with (<b>a</b>) the idealized conditions of the analytical methods, and (<b>b</b>) real conditions of the calibrated numerical model.</p>
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<p>Constitutive laws used in the definition of interaction diagrams: (<b>a</b>) concrete, (<b>b</b>) steel bars, and (<b>c</b>) steel fiber-reinforced shotcrete (SFRS).</p>
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<p>Interaction diagrams and acting loads at (<b>a</b>) the primary lining and (<b>b</b>) secondary lining.</p>
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<p>Interaction diagrams and acting loads at (<b>a</b>) the primary lining and (<b>b</b>) secondary lining.</p>
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<p>Interaction diagram and acting loads at primary lining.</p>
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<p>Surface vertical displacements perpendicular to the tunnel axis for each case analyzed.</p>
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22 pages, 5745 KiB  
Article
GenAI-Assisted Database Deployment for Heterogeneous Indigenous–Native Ethnographic Research Data
by Reen-Cheng Wang, David Yang, Ming-Che Hsieh, Yi-Cheng Chen and Weihsuan Lin
Appl. Sci. 2024, 14(16), 7414; https://doi.org/10.3390/app14167414 - 22 Aug 2024
Viewed by 954
Abstract
In ethnographic research, data collected through surveys, interviews, or questionnaires in the fields of sociology and anthropology often appear in diverse forms and languages. Building a powerful database system to store and process such data, as well as making good and efficient queries, [...] Read more.
In ethnographic research, data collected through surveys, interviews, or questionnaires in the fields of sociology and anthropology often appear in diverse forms and languages. Building a powerful database system to store and process such data, as well as making good and efficient queries, is very challenging. This paper extensively investigates modern database technology to find out what the best technologies to store these varied and heterogeneous datasets are. The study examines several database categories: traditional relational databases, the NoSQL family of key-value databases, graph databases, document databases, object-oriented databases and vector databases, crucial for the latest artificial intelligence solutions. The research proves that when it comes to field data, the NoSQL lineup is the most appropriate, especially document and graph databases. Simplicity and flexibility found in document databases and advanced ability to deal with complex queries and rich data relationships attainable with graph databases make these two types of NoSQL databases the ideal choice if a large amount of data has to be processed. Advancements in vector databases that embed custom metadata offer new possibilities for detailed analysis and retrieval. However, converting contents into vector data remains challenging, especially in regions with unique oral traditions and languages. Constructing such databases is labor-intensive and requires domain experts to define metadata and relationships, posing a significant burden for research teams with extensive data collections. To this end, this paper proposes using Generative AI (GenAI) to help in the data-transformation process, a recommendation that is supported by testing where GenAI has proven itself a strong supplement to document and graph databases. It also discusses two methods of vector database support that are currently viable, although each has drawbacks and benefits. Full article
(This article belongs to the Topic Innovation, Communication and Engineering)
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<p>ERD store in key-value NoSQL database.</p>
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<p>ERD store in document database.</p>
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<p>ERD store in graph database.</p>
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<p>3-nearest query in a vector database.</p>
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<p>Prompt to fetch the metadata from a record.</p>
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<p>An experience report for example.</p>
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<p>Response from GenAI.</p>
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<p>Convert to JSON format for DocumentDB importing.</p>
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<p>A record insert with Cypher commands.</p>
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<p>A simple ERD database established.</p>
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<p>Prompt for finding out Node, Relation and Property of a record.</p>
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<p>The response from OpenAI.</p>
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<p>Generate Cypher commands automatically.</p>
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<p>Pseudocode of vector embedding.</p>
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<p>Get the vector from OpenAI.</p>
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<p>The response OpenAI API.</p>
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<p>A sample of South-Paiwan oral conversation record in Romanized script.</p>
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<p>The result of analyzing <a href="#applsci-14-07414-f017" class="html-fig">Figure 17</a> by ChatGPT4o.</p>
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17 pages, 1529 KiB  
Article
Perceived Usefulness of a Mandatory Information System
by Shimon Fridkin, Gil Greenstein, Avner Cohen and Aviran Damari
Appl. Sci. 2024, 14(16), 7413; https://doi.org/10.3390/app14167413 - 22 Aug 2024
Viewed by 745
Abstract
This study examines the adoption and implementation of an information system in a mandatory context focusing on an Israeli governmental organization. The system referred to as “Slot” is an online platform for managing educational activities within this organization. The research investigates the impact [...] Read more.
This study examines the adoption and implementation of an information system in a mandatory context focusing on an Israeli governmental organization. The system referred to as “Slot” is an online platform for managing educational activities within this organization. The research investigates the impact of the system on its functionality users and the results of its usage. Additionally, the study explores factors that influence the acceptance and utilization of information systems, including whether the willingness to use the system under instruction depends on other variables. The key findings of this study are: perceived ease of use significantly and positively influences perceived usefulness; perceived usefulness significantly and positively affects symbolic adoption; and supervisor influence significantly and positively impacts perceived usefulness. Moreover, the relationship between perceived ease of use and symbolic adoption is entirely mediated by perceived usefulness as is the relationship between supervisor influence and symbolic adoption. The study’s limitations include the relatively small sample size and the specific context of the research, which may limit the generalizability of the findings. Future research could explore similar models in different organizational settings to validate and extend the applicability of the results. The findings suggest that enhancing the perceived ease of use and usefulness of mandatory systems can significantly impact their symbolic adoption, with supervisory influence playing a crucial role in shaping user perceptions. These insights can inform strategies for more effective implementation and management of information systems in mandatory settings. Full article
(This article belongs to the Special Issue Recent Advances in Information Retrieval and Recommendation Systems)
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<p>Structural hypothesized equation model.</p>
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<p>Latent structures derived from standardized questionnaire statements.</p>
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<p>Comprehensive overview of the final structural equation model (N = 72; * <span class="html-italic">p</span> &lt; 0.05; ** <span class="html-italic">p</span> &lt; 0.01; *** <span class="html-italic">p</span> &lt; 0.001).</p>
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20 pages, 29604 KiB  
Article
Stability Analysis of Surrounding Rock and Initial Support of Tunnel Undercrossing Multi-Situational Goafs: A Reference of Construction Guidance
by Meng Zhao, Jiaqi Guo, Shaohua Li, Shifan Liang and Fengwei Sun
Appl. Sci. 2024, 14(16), 7412; https://doi.org/10.3390/app14167412 - 22 Aug 2024
Viewed by 640
Abstract
To ensure the construction and operational safety of tunnel undercrossing multi-situational goafs, the Huaying Mountain High-Speed Rail Tunnel, a critical section of the Xi’an-Chongqing High-Speed Railway, was taken as a case study. Based on a three-dimensional finite difference numerical simulation platform, twelve situations [...] Read more.
To ensure the construction and operational safety of tunnel undercrossing multi-situational goafs, the Huaying Mountain High-Speed Rail Tunnel, a critical section of the Xi’an-Chongqing High-Speed Railway, was taken as a case study. Based on a three-dimensional finite difference numerical simulation platform, twelve situations were established to analyze the effects of three factors: distance, scale, and angle. The stability analysis was conducted by examining the displacement and deformation characteristics of the surrounding rock, stress changes, and axial forces of the initial support for each situation. The results show that in tunnel undercrossing multi-situational goafs, the vertical deformation, horizontal convergence of the surrounding rock, and the maximum axial force of initial support are all affected. Within a certain range, changes in distance significantly impact subsidence and settlement deformation of the surrounding rock. However, as the distance increases, the horizontal and vertical displacements of the tunnel and the axial force of the initial support tend to decrease. Conversely, the scale and angle of the goaf have an opposite effect on the surrounding rock: as the scale and angle increase, the stability of the surrounding rock deteriorates. In this case study, when the distance exceeds 1.13 times the tunnel span, the influence of the goaf on the stability of the surrounding rock gradually decreases. When the angle exceeds 45°, vertical displacement decreases, and the increasing trend of horizontal displacement gradually diminishes. The conclusions of this paper can provide guidance for designing reinforcement schemes for tunnels crossing through multi-situational goafs. The findings provide valuable insights and guidance for similar engineering projects. Full article
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<p>Overview of tunnel and goaf.</p>
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<p>Position relationship between tunnel and goaf.</p>
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<p>Horizontal displacement of surrounding rock of tunnel under different distances of goafs (Units: m).</p>
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<p>Vertical displacement of surrounding rock of tunnel under different distances of goafs (Units: m).</p>
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<p>Displacement of tunnel hance and vault under different distances of goafs.</p>
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<p>Surrounding rock stress of tunnel under different distances of goafs.</p>
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<p>The maximum axial force of initial support of tunnel under different distances of goafs (Units: m).</p>
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<p>Horizontal displacement of surrounding rock of tunnel under different scales of goafs (Units: m).</p>
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<p>Horizontal displacement of surrounding rock of tunnel under different scales of goafs (Units: m).</p>
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<p>Vertical displacement of surrounding rock of tunnel under different scales of goafs (Units: m).</p>
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<p>Displacement of tunnel hance and vault under different scales of goafs.</p>
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<p>Surrounding rock stress of tunnel under different scales of goafs.</p>
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<p>The maximum axial force of initial support of tunnel under different scales of goafs (Units: m).</p>
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<p>Horizontal displacement of surrounding rock of tunnel under different angles of goafs (Units: m).</p>
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<p>Horizontal displacement of surrounding rock of tunnel under different angles of goafs (Units: m).</p>
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<p>Vertical displacement of tunnel surrounding rock under different angles of go afs (Units: m).</p>
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<p>Displacement of tunnel hance and vault under different angles of goafs.</p>
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<p>Surrounding rock stress of tunnel under different angles of goafs.</p>
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<p>The maximum axial force of initial support of tunnel under different angles of goafs (Units: m).</p>
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<p>Guidance for engineering: (<b>a</b>) The resistivity profile image of the Huaying Mountain High-Speed Railway Tunnel site; (<b>b</b>) The drilling process of the CASAGRADNE-C6xp-2; (<b>c</b>) Changes in vertical displacement; (<b>d</b>) Changes in horizontal displacement; (<b>e</b>) Changes in maximum axial force of initial support; (<b>f</b>) Design of corresponding support schemes for different working conditions; (<b>g</b>) Design the best solution based on the above content.</p>
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16 pages, 5430 KiB  
Article
Novel Gas Supply System for Multi-Chamber Tri-Gas Cell Culture: Low Gas Consumption and Wide Concentration Range
by Donggen Xiao, Weijun Zeng, Ruitao Chen, Wei Li and Haixuan Sun
Appl. Sci. 2024, 14(16), 7411; https://doi.org/10.3390/app14167411 - 22 Aug 2024
Viewed by 880
Abstract
Gas plays a crucial role in cell culture as cells require a specific gas environment to maintain their growth, reproduction, and function. Here, we propose a gas supply system for tri-gas multi-channel cell incubators to meet the specific needs of various cells. The [...] Read more.
Gas plays a crucial role in cell culture as cells require a specific gas environment to maintain their growth, reproduction, and function. Here, we propose a gas supply system for tri-gas multi-channel cell incubators to meet the specific needs of various cells. The system utilizes a circulating gas supply method powered by air pumps for each chamber. Gas inflow from the cylinder is independently controlled by Mass Flow Controllers (MFCs), and a quantitative step-by-step adjustment control strategy is employed to calculate the volume of different gases being introduced. Through mixing simulations and experiments, we identified the SV static mixer with an L/D ratio of 2.5 as the optimal choice. To evaluate the concentration accuracy and gas consumption of the gas system, we conduct gas mixing and distribution experiments under different conditions. The results show that the system could achieve a concentration range of 0–100% for O2 with an accuracy of ±0.5%, and a concentration range of 0–10% for CO2 with an accuracy of ±0.1%. The daily gas consumption during cultivation is 3570 mL of N2, 330 mL of CO2, and 115 mL of O2, significantly lower than conventional incubators. Overall, our system can effectively manage dynamic gas concentration changes, particularly in high O2 concentration environments. It offers advantages such as low gas consumption, a wide concentration range, and high accuracy compared to existing incubators. Full article
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<p>Schematic of the gas mixing and distribution system for a multi-chamber cell incubator. The system requires compressed gases of pure N<sub>2</sub>, O<sub>2</sub>, and CO<sub>2</sub>. The red arrows indicate the gas flow direction.</p>
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<p>Mixers with different length–diameter ratios (L/D).</p>
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<p>Gas supply and distribution process.</p>
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<p>A system-based multi-chamber cell incubator.</p>
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<p>The concentration distribution at the center section (molar fraction).</p>
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<p>The concentration distribution at the outlet section (molar fraction).</p>
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<p>Concentration changes of CO<sub>2</sub> (<b>a</b>) and O<sub>2</sub> (<b>b</b>) in an open system with mixers with different L/D ratios.</p>
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<p>Concentration changes of CO<sub>2</sub> (<b>a</b>) and O<sub>2</sub> (<b>b</b>) in circulatory system experiment with mixers with different L/D ratios.</p>
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<p>(<b>a</b>) Concentration changes of CO<sub>2</sub> and O<sub>2</sub> when initializing (<b>b</b>) gas consumption during each adjustment.</p>
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<p>Concentration changes of CO<sub>2</sub> under different set concentrations of O<sub>2</sub>.</p>
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<p>Concentration changes of O<sub>2</sub> under different set concentrations of O<sub>2</sub>.</p>
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<p>Gas consumption during each adjustment.</p>
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<p>(<b>a</b>) Concentration changes of CO<sub>2</sub> and O<sub>2</sub> after lids open (<b>b</b>) gas consumption during each adjustment.</p>
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23 pages, 7464 KiB  
Article
Algorithms to Reduce the Data File Size and Improve the Write Rate for Storing Sensor Reading Values in Hard Disk Drives for Measurements with Exceptionally High Sampling Rates
by Quang Dao Vuong, Kanghyun Seo, Hyejin Choi, Youngmin Kim, Ji-woong Lee and Jae-ung Lee
Appl. Sci. 2024, 14(16), 7410; https://doi.org/10.3390/app14167410 - 22 Aug 2024
Viewed by 825
Abstract
This study aimed to enhance the data write performance in measurements with exceptionally high sampling rates, such as acoustic emission measurements. This is particularly crucial when employing conventional hard disk drives to store data. This study introduced algorithms for handling binary formats, thereby [...] Read more.
This study aimed to enhance the data write performance in measurements with exceptionally high sampling rates, such as acoustic emission measurements. This is particularly crucial when employing conventional hard disk drives to store data. This study introduced algorithms for handling binary formats, thereby reducing the data file size, increasing write rates, and ultimately shortening data write times during measurements. The suggested approaches included utilizing specialized binary formats and implementing self-created buffers. These approaches resulted in a remarkable write time reduction of up to 40×. Furthermore, employing multiple drives for writing significantly enhanced performance compared with that of using a single drive. Therefore, the proposed algorithms offer promising results for managing large amounts of data in real time. Full article
(This article belongs to the Section Acoustics and Vibrations)
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<p>Schematic diagram of the measurement system utilizing the algorithms developed in this study.</p>
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<p>Composition of an example scaled value of the 3-byte number format.</p>
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<p>Conversion algorithm of 2-byte and 3-byte number formats.</p>
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<p>Data write performance in the tests using the default buffer size. (<b>a</b>) File size = 128 MB and (<b>b</b>) file size = 256 MB.</p>
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<p>Data write performance in tests using the configured buffer size. (<b>a</b>) File size = 128 MB and (<b>b</b>) file size = 256 MB.</p>
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<p>Data write performance of tests using a self-created buffer. (<b>a</b>) Buffer size = 8 MB, (<b>b</b>) buffer size = 32 MB, (<b>c</b>) buffer size = 64 MB, (<b>d</b>) buffer size = 128 MB, (<b>e</b>) buffer size = 256 MB, and (<b>f</b>) buffer size = 512 MB.</p>
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<p>Data write performance of tests using a self-created buffer. (<b>a</b>) Buffer size = 8 MB, (<b>b</b>) buffer size = 32 MB, (<b>c</b>) buffer size = 64 MB, (<b>d</b>) buffer size = 128 MB, (<b>e</b>) buffer size = 256 MB, and (<b>f</b>) buffer size = 512 MB.</p>
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<p>Data write performance of the multi-threaded write. (<b>a</b>) Buffer size = 128 MB and (<b>b</b>) buffer size = 256 MB.</p>
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<p>Data distribution across the three drives, based on the principle of RAID 0.</p>
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<p>Configuration to store data on multiple drives.</p>
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<p>Operating window of the program in a high-performance measurement test.</p>
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<p>Configuration of the hydraulic accumulator.</p>
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<p>Installation of acoustic emission sensors.</p>
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<p>AE event wave measured by the Kistler sensors. (<b>a</b>) At position P1, (<b>b</b>) at position P2, and (<b>c</b>) at position P3. (<b>d</b>) Comparison of the arrival times of the AE event wave to positions P1, P2, and P3.</p>
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<p>AE event wave measured by the Kistler sensors. (<b>a</b>) At position P1, (<b>b</b>) at position P2, and (<b>c</b>) at position P3. (<b>d</b>) Comparison of the arrival times of the AE event wave to positions P1, P2, and P3.</p>
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<p>Failure of the hydraulic accumulator after 29 h of the load test.</p>
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16 pages, 12709 KiB  
Article
A Study on the Optimization of Water Jet Decontamination Performance Parameters Based on the Response Surface Method
by Xianyan Qiu, Mengkun Wang, Bingzheng Chen and Yang Ai
Appl. Sci. 2024, 14(16), 7409; https://doi.org/10.3390/app14167409 - 22 Aug 2024
Viewed by 612
Abstract
The substrate that adheres between the teeth of the traveling track plate during the operation of a deep-sea polymetallic nodule mining vehicle affects the driving performance, so this study aimed to investigate the effect of the water jet on the cleaning and decontamination [...] Read more.
The substrate that adheres between the teeth of the traveling track plate during the operation of a deep-sea polymetallic nodule mining vehicle affects the driving performance, so this study aimed to investigate the effect of the water jet on the cleaning and decontamination performance of the track under different conditions. An optimization design method based on response surface methodology (RSM) is proposed. Based on the Box–Behnken design, the optimization variables of jet pressure, jet target distance, and impact angle, and the target response of jet strike pressure on tracks, were selected, and the numerical simulation method was combined with the response surface method to establish the regression model of the response of each optimization variable to the jet strike pressure on tracks and to determine the optimal parameter combinations. The study findings indicate that the primary factor influencing the pressure of the jet striking the crawler is the jet pressure. The hierarchical order of influence on the pressure of the jet striking the crawler, under the interaction of the three factors, is as follows: jet pressure and impact angle, jet pressure and target distance of the jet, and target distance of the jet and impact angle. The maximum pressure of the jet striking the crawler occurs when the jet pressure is 0.983 MPa, the target distance is 0.14 m, and the impact angle is 89.5°. Overall, the proposed design serves as a systematic framework for parameter optimization in the cleaning and decontamination process, and the research method and results provide theoretical references for the optimal design of mining truck desorption efficiency, which is critical for increasing mining efficiency and lowering energy consumption. Full article
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<p>Computational domain.</p>
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<p>CFD solution process.</p>
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<p>Comparison of simulation-predicted and theoretically calculated jet velocities.</p>
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<p>Verification of grid independence.</p>
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<p>Actual versus predicted.</p>
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<p>The impact of the interaction between injection pressure and injection target distance on the dynamic pressure of the striking track tooth (<math display="inline"><semantics> <mrow> <msub> <mrow> <mi mathvariant="normal">X</mi> </mrow> <mrow> <mn>3</mn> </mrow> </msub> </mrow> </semantics></math> = 75°).</p>
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<p>The impact of the interaction between injection pressure and impact angle on the dynamic pressure of the striking track tooth (<math display="inline"><semantics> <mrow> <msub> <mrow> <mi mathvariant="normal">X</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> </mrow> </semantics></math> = 0.16).</p>
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<p>The impact of the interaction between impact angle and injection target distance on the dynamic pressure of the striking track tooth (<math display="inline"><semantics> <mrow> <msub> <mrow> <mi mathvariant="normal">X</mi> </mrow> <mrow> <mn>1</mn> </mrow> </msub> </mrow> </semantics></math> = 0.7).</p>
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<p>The correlation between jet strike track tooth pressure and jet pressure (<math display="inline"><semantics> <mrow> <msub> <mrow> <mi mathvariant="normal">X</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> </mrow> </semantics></math> = 0.16, <math display="inline"><semantics> <mrow> <msub> <mrow> <mi mathvariant="normal">X</mi> </mrow> <mrow> <mn>3</mn> </mrow> </msub> </mrow> </semantics></math> = 75°).</p>
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<p>The correlation between jet strike track tooth pressure and target distance (<math display="inline"><semantics> <mrow> <msub> <mrow> <mi mathvariant="normal">X</mi> </mrow> <mrow> <mn>1</mn> </mrow> </msub> </mrow> </semantics></math> = 0.7, <math display="inline"><semantics> <mrow> <msub> <mrow> <mi mathvariant="normal">X</mi> </mrow> <mrow> <mn>3</mn> </mrow> </msub> </mrow> </semantics></math> = 75°).</p>
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<p>The correlation between jet strike track tooth pressure and impact angle (<math display="inline"><semantics> <mrow> <msub> <mrow> <mi mathvariant="normal">X</mi> </mrow> <mrow> <mn>1</mn> </mrow> </msub> </mrow> </semantics></math> = 0.7, <math display="inline"><semantics> <mrow> <msub> <mrow> <mi mathvariant="normal">X</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> </mrow> </semantics></math> = 0.16).</p>
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15 pages, 1832 KiB  
Article
Application of Explosive Equivalency Approach in Blast-Induced Seismic Effect Prediction Using EXPLO5 Thermochemical Code
by Siniša Stanković, Josip Olivani, Ivana Dobrilović and Muhamed Sućeska
Appl. Sci. 2024, 14(16), 7408; https://doi.org/10.3390/app14167408 - 22 Aug 2024
Viewed by 696
Abstract
Blasting is a key process that plays a significant role in various industries, including mining and construction. To measure the effectiveness and potential impact of a blast generated by different explosives, industry professionals use a widely accepted parameter known as TNT (trinitrotoluene) equivalent. [...] Read more.
Blasting is a key process that plays a significant role in various industries, including mining and construction. To measure the effectiveness and potential impact of a blast generated by different explosives, industry professionals use a widely accepted parameter known as TNT (trinitrotoluene) equivalent. This manuscript provides an overview of the approach based on the application of the explosive equivalency principle in the prediction of the seismic effects caused by the detonation of different explosives. The explosive equivalents of studied explosives are derived from the results of thermochemical calculations using the EXPLO5 code and compared to field tests. The results have demonstrated that the equivalency approach can potentially be a useful tool in the assessment of blast-induced seismic effects. Full article
(This article belongs to the Section Applied Thermal Engineering)
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<p>Ground oscillation velocity measurement setup for Line 1 [<a href="#B30-applsci-14-07408" class="html-bibr">30</a>].</p>
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<p>The best-fit line and corresponding 95% confidence line for EME.</p>
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<p>Comparison of experimental and predicted values of PPV for EMM/EPS-40/60 mixture.</p>
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<p>Comparison of predicted and experimental PPV values for EMM/EPS mixtures. (Note: Red dashed curves represent the best-fit curve for EME calculated by Equation (15) using actual weight, solid blue curves represent the best-fit curve for EMM/EPS mixtures calculated by Equation (15) using EME equivalent weight, and solid green curves represent the best-fit of experimental data).</p>
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<p>Graphical presentation of determination of SD at which a specified PPV value is reached.</p>
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<p>Comparison of predicted and experimental W-R curves for fixed PPV value of 20 mm/s.</p>
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14 pages, 27392 KiB  
Article
Quantitative Determination of Partial Voxel Compositions with X-ray CT Image-Based Data-Constrained Modelling
by Haipeng Wang, Xinsheng Mu, Xinyue Zhou and Yu-Shuang Yang
Appl. Sci. 2024, 14(16), 7407; https://doi.org/10.3390/app14167407 - 22 Aug 2024
Viewed by 721
Abstract
X-ray CT imaging is an important three-dimensional non-destructive testing technique, which has been widely applied in various fields. However, segmenting image voxels as discrete material compositions may lose information below the voxel size. In this study, six samples with known volume fractions of [...] Read more.
X-ray CT imaging is an important three-dimensional non-destructive testing technique, which has been widely applied in various fields. However, segmenting image voxels as discrete material compositions may lose information below the voxel size. In this study, six samples with known volume fractions of compositions were imaged using laboratory micro-CT. Optical microscopic images of the samples reveal numerous small particles of compositions smaller than the CT voxel size within the samples. By employing the equivalent energy method to determine the X-ray beam energy for sample imaging experiments, data-constrained modelling (DCM) was used to obtain the volume fractions of different compositions in the samples for each voxel. The results demonstrated that DCM effectively captured information about compositions occupying CT voxels partially. The computed volume fractions of compositions using DCM closely matched the known values. The results of DCM and four automatic threshold segmentation algorithms were compared and analyzed. The results showed that DCM has obvious advantages in processing those samples containing a large number of particles smaller than the CT voxel size. This work is the first quantitative evaluation of DCM for laboratory CT image processing, which provides a new idea for multi-scale structure characterization of materials based on laboratory CT. Full article
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<p>The sample 1 configuration listed in <a href="#applsci-14-07407-t001" class="html-table">Table 1</a>. a: pure Al; b, c, d: compacted pure silica particles; e: vacuum putty.</p>
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<p>Typical X-ray CT slices of the samples. (<b>a</b>) Sample 1; (<b>b</b>) sample 2; (<b>c</b>) sample 3; (<b>d</b>) sample 4; (<b>e</b>) sample 5; (<b>f</b>) sample 6.</p>
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<p>Histograms of sub-regions of CT slices in <a href="#applsci-14-07407-f002" class="html-fig">Figure 2</a>.</p>
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<p>DCM-determined boundary of sample 1.</p>
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<p>Optical microscope images (<b>a</b>–<b>e</b>) and the threshold segmentation results (<b>a’</b>–<b>e’</b>) for samples 2–6. The pixel size of each image is 2560 × 1920 pixels, and each pixel represents a physical size of 0.206 × 0.206 μm<sup>2</sup>. (<b>a</b>,<b>a’</b>) Sample 2; (<b>b</b>,<b>b’</b>) sample 3; (<b>c</b>,<b>c’</b>) sample 4; (<b>d</b>,<b>d’</b>) sample 5; (<b>e</b>,<b>e’</b>) sample 6.</p>
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<p>Optical microscope images (<b>a</b>–<b>e</b>) and the threshold segmentation results (<b>a’</b>–<b>e’</b>) for samples 2–6. The pixel size of each image is 2560 × 1920 pixels, and each pixel represents a physical size of 0.206 × 0.206 μm<sup>2</sup>. (<b>a</b>,<b>a’</b>) Sample 2; (<b>b</b>,<b>b’</b>) sample 3; (<b>c</b>,<b>c’</b>) sample 4; (<b>d</b>,<b>d’</b>) sample 5; (<b>e</b>,<b>e’</b>) sample 6.</p>
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<p>The distribution of compositions computed by DCM in the X-ray CT slices, as shown <a href="#applsci-14-07407-f002" class="html-fig">Figure 2</a>. Different colors represent different compositions, and the color intensity of each composition is proportional to its volume fraction in the voxel. Compositions coexisting in one pixel are shown as mixed colors. (<b>a</b>) Sample 1; (<b>b</b>) sample 2; (<b>c</b>) sample 3; (<b>d</b>) sample 4; (<b>e</b>) sample 5; (<b>f</b>) sample 6.</p>
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<p>Original CT slice and composition distribution maps obtained by different methods. (<b>a</b>) The sub-region of the CT slice of sample 1; the pore distribution results obtained by (<b>b</b>) DCM; (<b>c</b>) Shanbhag; (<b>d</b>) Triangle; (<b>e</b>) Otsu; (<b>f</b>) Percentile. In the DCM results, the pixel gray value is proportional to the porosity, and black represents the pore in other image threshold segmentation results.</p>
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15 pages, 861 KiB  
Article
From Evaluation to Prediction: Analysis of Diabetic Autonomic Neuropathy Using Sudoscan and Artificial Intelligence
by Roxana Toderean, Maricela Cobuz, Mihai Dimian and Claudiu Cobuz
Appl. Sci. 2024, 14(16), 7406; https://doi.org/10.3390/app14167406 - 22 Aug 2024
Viewed by 833
Abstract
A dangerous side effect of diabetes that can significantly lower quality of life and raise the death rate of diabetic individuals is diabetic autonomic neuropathy. It is essential to identify and anticipate this disease early on for prompt intervention and care. This study [...] Read more.
A dangerous side effect of diabetes that can significantly lower quality of life and raise the death rate of diabetic individuals is diabetic autonomic neuropathy. It is essential to identify and anticipate this disease early on for prompt intervention and care. This study aims to predict this diabetic complication using Sudoscan and artificial intelligence. In this study, 172 individuals with type 1 or type 2 diabetes mellitus provided clinical and demographic information. Sudoscan was used to evaluate the subjects’ sudomotor dysfunction. Statistical methods were used to link various electrochemical skin conductance values with risk factors for neuropathy such as age, BMI, age of diabetes, or biochemical values such as cholesterol and triglycerides. Different machine-learning algorithms were used to predict the risk of diabetic autonomic neuropathy based on the collected data. The accuracy achieved with Logistic Regression is 92.6%, and with the Random Forest model is 96.3%. Lazzy Classifiers also show that six classifiers have a high performance of 97%. Thus, the use of machine learning algorithms in this field of metabolic diseases offers new perceptions for diagnosis, treatment, and prevention, and improves the quality of life of diabetic patients by reducing the incidence of complications related to this disease. Full article
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<p>Distribution of ESC values for hands and feet grouped by DAN.</p>
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<p>Distribution of ESC values according to age of diabetes diagnosis.</p>
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15 pages, 4972 KiB  
Article
Energy Evolution Characteristics and Hydraulic Fracturing Roof Cutting Technology for Hard Roof Working Face during Initial Mining: A Case Study
by Chungang Wang, Jianbiao Bai, Tianchen Wang and Wenda Wu
Appl. Sci. 2024, 14(16), 7405; https://doi.org/10.3390/app14167405 - 22 Aug 2024
Viewed by 759
Abstract
In the process of mining, a large area of hard roof will be exposed above a goaf and may suddenly break. This can easily induce rock burst and has a significant impact on production safety. In this study, based on the engineering background [...] Read more.
In the process of mining, a large area of hard roof will be exposed above a goaf and may suddenly break. This can easily induce rock burst and has a significant impact on production safety. In this study, based on the engineering background of the hard roof of the 2102 working face in the Balasu coal mine, the spatial and temporal characteristics of the strain energy of the roof during the initial mining process were explored in depth. Based on a theoretical calculation, it is proposed that hydraulic fracturing should be carried out in the medium-grained sandstone layer that is 4.8–22.43 m above the roof, and that the effective fracturing section in the horizontal direction should be within 30.8 m of the cutting hole of the working face. The elastic strain energy fish model was established in FLAC3D to analyze the strain energy accumulation of the roof during the initial mining process. The simulation and elastic strain energy results show that, as the working face advances to 70–80 m, the hard roof undergoes significant bending deformation. The energy gradient increases with the rapid accumulation of strain energy to a peak value of 140.54 kJ/m3. If the first weighting occurs at this moment in time, the sudden fracture of the roof will be accompanied by the release of elastic energy, which will induce rock burst. Therefore, it is necessary to implement roof cutting and pressure relief before reaching the critical step of 77 m. To this end, the comprehensive hydraulic fracturing technology of ‘conventional short drilling + directional long drilling’ is proposed. A field test shows that the hydraulic fracturing technology effectively weakens the integrity of the rock layer. The first weighting interval is 55 m, and it continues until the end of the pressure at the 70 m position. The roof collapses well, and the mining safety is improved. This study provides an important reference for hard roof control. Full article
(This article belongs to the Special Issue Underground Rock Support and Excavation)
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<p>Layout of longwall panel 2102. (<b>a</b>) Panel layout. (<b>b</b>) Generalized stratigraphy column.</p>
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<p>Asymmetric three-hinged arch structure of initial roof caving.</p>
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<p>Model overview.</p>
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<p>Temporal and spatial distribution characteristics of elastic strain energy density during mining to (<b>a</b>) 10, (<b>b</b>) 20, (<b>c</b>) 30, (<b>d</b>) 40, (<b>e</b>) 50, (<b>f</b>) 60, (<b>g</b>) 70, and (<b>h</b>) 80 m.</p>
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<p>Temporal and spatial distribution characteristics of elastic strain energy density during mining to (<b>a</b>) 10, (<b>b</b>) 20, (<b>c</b>) 30, (<b>d</b>) 40, (<b>e</b>) 50, (<b>f</b>) 60, (<b>g</b>) 70, and (<b>h</b>) 80 m.</p>
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<p>Principle of conventional straight-hole hydraulic fracturing technology. (<b>a</b>) The first section of construction. (<b>b</b>) Section n of construction.</p>
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<p>Principle of directional-hole hydraulic fracturing technology. (<b>a</b>) The first section of construction. (<b>b</b>) Section n of construction.</p>
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<p>Hydraulic fracturing roof cutting scheme. (<b>a</b>) Hydraulic fracturing drilling plane diagram. Drilling profile of hydraulic fracturing holes (<b>b</b>) S, L, B, and D, and (<b>c</b>) A, C, and D.</p>
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<p>Curve of hydraulic fracturing water pressure and flow rate vs. time. Boreholes (<b>a</b>) A3 and (<b>b</b>) L12.</p>
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<p>Drilling peep to detect crack propagation after hydraulic fracturing.</p>
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<p>The working resistance of the support during the mining of the 2102 working face.</p>
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<p>The roof collapse behind the support of the 2102 working face.</p>
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19 pages, 769 KiB  
Article
Promoting Environmental Sustainability: The Role of Renewable Energy Systems and Environmental Taxes
by Yugang He
Appl. Sci. 2024, 14(16), 7404; https://doi.org/10.3390/app14167404 - 22 Aug 2024
Viewed by 1920
Abstract
This study examines the effects of renewable energy consumption and environmental taxes on CO2 emissions in OECD countries from 1990 to 2022, employing the cross-sectional autoregressive distributed lag (CS-ARDL) approach. The findings reveal that both renewable energy consumption and environmental taxes significantly [...] Read more.
This study examines the effects of renewable energy consumption and environmental taxes on CO2 emissions in OECD countries from 1990 to 2022, employing the cross-sectional autoregressive distributed lag (CS-ARDL) approach. The findings reveal that both renewable energy consumption and environmental taxes significantly reduce CO2 emissions in both the short and the long term, emphasizing their crucial roles in climate change mitigation and sustainability promotion. Furthermore, this study identifies that industrialization and urbanization contribute to increased emissions, whereas foreign direct investment aids in emission reduction through the facilitation of green technology transfer. Economic growth is initially associated with higher emissions, but this trend reverses as economies mature and adopt sustainable practices. These results highlight the importance of continuous investment in renewable energy infrastructure and the implementation of robust environmental tax policies to achieve long-term sustainability goals. The integration of environmental considerations into economic and urban planning, along with leveraging foreign direct investment for technological advancements, is imperative for balancing economic growth with the necessity to reduce carbon emissions and effectively address climate change. This research provides a better understanding of the diverse factors influencing CO2 emissions and offers critical insights for policymakers. Full article
16 pages, 6578 KiB  
Article
Behaviour Analysis of Beam-Type Timber and Timber-Concrete Composite Panels
by Elza Briuka, Dmitrijs Serdjuks, Pavel Akishin, Genadijs Sahmenko, Andrejs Podkoritovs and Raimonds Ozolins
Appl. Sci. 2024, 14(16), 7403; https://doi.org/10.3390/app14167403 - 22 Aug 2024
Viewed by 699
Abstract
This study addresses the enhancement of material efficiency and reduction in brittleness in timber-to-concrete adhesive connections for beam-type timber and timber-concrete composite panels. The research explores the potential benefits of adding longitudinal timber ribs to cross-laminated timber (CLT) beam-type panels. Three groups of [...] Read more.
This study addresses the enhancement of material efficiency and reduction in brittleness in timber-to-concrete adhesive connections for beam-type timber and timber-concrete composite panels. The research explores the potential benefits of adding longitudinal timber ribs to cross-laminated timber (CLT) beam-type panels. Three groups of flexure-tested specimens were analysed as follows: (1) timber panels (1400 mm × 400 mm) with two 100 mm thick CLT panels and two 60 mm thick CLT panels reinforced with 150 × 80 mm timber ribs; (2) eight specimens (600 mm × 100 mm × 150 mm) with CLT members (600 mm × 100 mm × 100 mm) connected to a 50 mm concrete layer using granite chips and Sikadur-31 (AB) epoxy adhesive; (3) six CLT panels (1400 mm × 400 mm × 50 mm) bonded to a 50 mm concrete layer, with two panels containing polypropylene microfibres and two panels incorporating polyethene dowels for mechanical connection. Specimens were subjected to three-point bending tests and analysed using the transformed section method, γ-method, and finite element method with ANSYS 2023R2 software. Results indicated a 53% increase in load-carrying capacity for ribbed CLT panels with no additional material consumption, a 24.8–41.1% increase for CLT panels strengthened with a concrete layer, and improved ductility and prevention of disintegration in timber-concrete composites with polypropylene microfibres. Full article
(This article belongs to the Special Issue Latest Advances in Cement and Concrete Composites: 2nd Edition)
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<p>CLT beam-type panel with glued laminated timber longitudinal ribs.</p>
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<p>Transformed to the timber of CLT layers with the grains oriented parallel to the longitudinal axis of the member section of the TCC beam-type panel.</p>
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<p>The first sub-group of the laboratory specimens—CLT panels with dimensions 1400 mm × 400 mm × 100 mm: A—longitudinal section; B—cross-section.</p>
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<p>The second sub-group is presented by the two CLT panels with dimensions 1400 mm × 400 mm × 60 mm, strengthened by the two glued laminated timber ribs with dimensions 150 mm × 80 mm.</p>
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<p>The second group of laboratory specimens: (<b>a</b>) specimens of sub-group A, (<b>b</b>) specimens of sub-group B, and (<b>c</b>) specimens of sub-group C.</p>
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<p>The second group of laboratory specimens: (<b>a</b>) designations of specimens in the sub-groups and (<b>b</b>) specimens placed in the moulds in the process of concrete hardening.</p>
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<p>The third group of laboratory specimens: (<b>a</b>) the first sub-group signed as ASD, (<b>b</b>) the second sub-group, signed as AS, and (<b>c</b>) the third sub-group, signed as BS.</p>
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<p>Testing devices: (<b>a</b>) for the first and third groups of laboratory specimens and (<b>b</b>) for the second group of laboratory specimens.</p>
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<p>FEM models of the first group of laboratory specimens: (<b>a</b>) FEM of the first sub-group specimens under the action of concentrated force at 30 kN and (<b>b</b>) FEM of the first sub-group specimens under the action of concentrated force at 50 kN.</p>
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<p>FEM models of the second and third groups of laboratory specimens: (<b>a</b>) FEM of the second (sub-group B) group of specimens under the action of concentrated force at 10 kN and (<b>b</b>) FEM of the third (sub-group BS) group of laboratory specimens under the action of concentrated force at 60 kN.</p>
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<p>Design schemes of laboratory specimens: (<b>a</b>) the first and third groups, and (<b>b</b>) the second group.</p>
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<p>Dependence of the maximum vertical displacements on the vertical load, applied as a concentrated force in the middle of the span, for the first sub-group of the first group specimens, where 1st and 2nd specimen_exp—obtained by the laboratory experiment, FEM—by the FEM method, and SMD and SMD_shear—by the simplified design method without and with considering the shear force influence on the vertical displacements of the panels.</p>
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<p>Dependence of the maximum vertical displacements on the vertical load, applied as a concentrated force in the middle of the span, for the 2nd sub-group of the 1st group of the specimens, where 3rd and 4th specimen_exp—obtained by the laboratory experiment, FEM—by the FEM method, and SMD and SMD_shear—by the simplified design method without and with considering the shear force influence on the vertical displacements of the panels.</p>
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<p>Dependence of the effectiveness of structural materials use K<sub>1</sub> on the geometric parameters of the specimens: (<b>a</b>) on the depth of the glued laminated timber ribs and (<b>b</b>) on the depth of the CLT component.</p>
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<p>The failure modes of the specimens of all three sub-groups of the second group: (<b>a</b>) first sub-group (specimen A3), (<b>b</b>) second sub-group (specimen B1), and (<b>c</b>) third sub-group (specimen C2).</p>
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<p>The dependence of the maximum vertical displacements on the vertical load applied as a concentrated force in the middle of the span for the third group of laboratory specimens.</p>
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<p>The failure mode of the third group specimens: (<b>a</b>) sub-group BS and (<b>b</b>) sub-group AS.</p>
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<p>Maximum vertical displacements obtained for the third group of laboratory specimens at the concentrated force of 60 kN applied in the middle of the span.</p>
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