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28 pages, 18674 KiB  
Article
OBTPN: A Vision-Based Network for UAV Geo-Localization in Multi-Altitude Environments
by Nanxing Chen, Jiqi Fan, Jiayu Yuan and Enhui Zheng
Drones 2025, 9(1), 33; https://doi.org/10.3390/drones9010033 - 6 Jan 2025
Abstract
UAVs typically rely on satellite navigation for positioning, yet this method proves ineffective in instances where the signal is inadequate or communication is disrupted. Visually based positioning technology has emerged as a reliable alternative. In this paper, we propose a novel end-to-end network, [...] Read more.
UAVs typically rely on satellite navigation for positioning, yet this method proves ineffective in instances where the signal is inadequate or communication is disrupted. Visually based positioning technology has emerged as a reliable alternative. In this paper, we propose a novel end-to-end network, OBTPN. In the initial phase of the model, we optimized the distribution of attention within the primary network, aiming to achieve a balance between self-attention and cross-attention. Subsequently, we devised a feature fusion head, which enhanced the model’s capacity to process multi-scale information. OBTPN was successfully deployed on an NVIDIA Jetson TX2 onboard computer. This paper also proposes a high-altitude complex environment dataset, Crossview9, which addresses a research gap in the field of high-altitude visual navigation. The performance of the model on this dataset is also evaluated. Additionally, the dataset was processed to simulate a low-quality image environment to assess the model’s resilience in challenging weather conditions. The experimental results demonstrate that OBTPN_256 attains an accuracy of 84.55% on the RDS metric, thereby reaching the state-of-the-art (SOTA) level of the UL14 dataset. On the Crossview9 dataset, OBTPN_256 achieves an RDS score of 79.76%, also reaching the SOTA level. Most notably, the model’s high accuracy in low-quality image environments further substantiates its robustness in complex environments. Full article
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21 pages, 3337 KiB  
Article
Combining UAS LiDAR, Sonar, and Radar Altimetry for River Hydraulic Characterization
by Monica Coppo Frias, Alexander Rietz Vesterhauge, Daniel Haugård Olesen, Filippo Bandini, Henrik Grosen, Sune Yde Nielsen and Peter Bauer-Gottwein
Drones 2025, 9(1), 31; https://doi.org/10.3390/drones9010031 - 6 Jan 2025
Abstract
Accurate river hydraulic characterization is fundamental to assess flood risk, parametrize flood forecasting models, and develop river maintenance workflows. River hydraulic roughness and riverbed/floodplain geometry are the main factors controlling inundation extent and water levels. However, gauging stations providing hydrometric observations are declining [...] Read more.
Accurate river hydraulic characterization is fundamental to assess flood risk, parametrize flood forecasting models, and develop river maintenance workflows. River hydraulic roughness and riverbed/floodplain geometry are the main factors controlling inundation extent and water levels. However, gauging stations providing hydrometric observations are declining worldwide, and they provide point measurements only. To describe hydraulic processes, spatially distributed data are required. In situ surveys are costly and time-consuming, and they are sometimes limited by local accessibility conditions. Satellite earth observation (EO) techniques can be used to measure spatially distributed hydrometric variables, reducing the time and cost of traditional surveys. Satellite EO provides high temporal and spatial frequency, but it can only measure large rivers (wider than ca. 50 m) and only provides water surface elevation (WSE), water surface slope (WSS), and surface water width data. UAS hydrometry can provide WSE, WSS, water surface velocity and riverbed geometry at a high spatial resolution, making it suitable for rivers of all sizes. The use of UAS hydrometry can enhance river management, with cost-effective surveys offering large coverage and high-resolution data, which are fundamental in flood risk assessment, especially in areas that difficult to access. In this study, we proposed a combination of UAS hydrometry techniques to fully characterize the hydraulic parameters of a river. The land elevation adjacent to the river channel was measured with LiDAR, the riverbed elevation was measured with a sonar payload, and the WSE was measured with a UAS radar altimetry payload. The survey provided 57 river cross-sections with riverbed elevation, and 8 km of WSE and land elevation and took around 2 days of survey work in the field. Simulated WSE values were compared to radar altimetry observations to fit hydraulic roughness, which cannot be directly observed. The riverbed elevation cross-sections have an average error of 32 cm relative to RTK GNSS ground-truth measurements. This error was a consequence of the dense vegetation on land that prevents the LiDAR signal from reaching the ground and underwater vegetation, which has an impact on the quality of the sonar measurements and could be mitigated by performing surveys during winter, when submerged vegetation is less prevalent. Despite the error of the riverbed elevation cross-sections, the hydraulic model gave good estimates of the WSE, with an RMSE below 3 cm. The estimated roughness is also in good agreement with the values measured at a gauging station, with a Gauckler–Manning–Strickler coefficient of M = 16–17 m1/3/s. Hydraulic modeling results demonstrate that both bathymetry and roughness measurements are necessary to obtain a unique and robust hydraulic characterization of the river. Full article
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27 pages, 12396 KiB  
Article
Research on Bearing Capacity Characteristics of Cave Piles
by Lixin Ou, Yufeng Huang, Xu Chen, Yang Xue, Qingfu Li and Biao Guo
Buildings 2025, 15(1), 143; https://doi.org/10.3390/buildings15010143 - 6 Jan 2025
Viewed by 70
Abstract
To investigate the load-bearing characteristics of a pile foundation with multiple piles passing through karst caves and the extent of the caves’ influence, this study takes the Qihe Bridge, a key project of the second section of the Anhe Expressway, as a case [...] Read more.
To investigate the load-bearing characteristics of a pile foundation with multiple piles passing through karst caves and the extent of the caves’ influence, this study takes the Qihe Bridge, a key project of the second section of the Anhe Expressway, as a case study. Field tests on the bearing capacity of the pile foundation, passing through underlying karst caves, were conducted. Piles passing through the caves were selected as test piles, and a finite element analysis of the Qihe Bridge pile foundation structure was performed using Midas GTS NX 2022 software. After verifying the accuracy of the software’s calculation results, this study further explored the distribution patterns of factors such as axial force, side friction resistance, settlement, and relative displacement between the pile and soil with respect to the position of the pile. Special attention was given to monitoring locations at the interface between rock and soil layers, as well as within the depth range of the karst caves. The horizontal axial force on the piles was found to increase with the depth of the caves. By analyzing the distribution patterns of axial force, side friction resistance, settlement, and pile–soil relative displacement, the study clarifies the mechanism by which karst caves affect the load-bearing behavior of pile foundations. Full article
(This article belongs to the Section Building Structures)
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30 pages, 2461 KiB  
Article
Research on the Thermal Comfort Experience of Metro Passengers Under Sustainable Transportation: Theory of Stimulus-Organism-Response Integration with a Technology Acceptance Model
by Tao Zou, Jiawei Guan, Yuhui Wang, Fangyuan Zheng, Yuwen Lin and Yifan Zhao
Sustainability 2025, 17(1), 362; https://doi.org/10.3390/su17010362 - 6 Jan 2025
Viewed by 90
Abstract
(1) Background: Metro is an important part of urban transportation, carrying huge passenger volume every day. With improvements in people’s living standards, passengers’ demand for a comfortable Metro experience is increasing. In the context of urban development, maintaining a good thermal comfort level [...] Read more.
(1) Background: Metro is an important part of urban transportation, carrying huge passenger volume every day. With improvements in people’s living standards, passengers’ demand for a comfortable Metro experience is increasing. In the context of urban development, maintaining a good thermal comfort level of Metro cars is not only conducive to providing a comfortable and healthy environment for passengers, but also has great significance for reducing energy consumption and sustainable urban transportation development. This study provides empirical evidence for Metro design and operation strategies, aiming at creating a safer and more comfortable passenger experience. (2) Methods: By combining passengers’ comfort perception (cognitive value of thermal environment) and rideability perception (confidence in thermal comfort control), this study established a correlation model between thermal comfort and passenger unsafe behavior, namely the integration of SOR (Stimulus-Organism-Response) and TAM (Technology Acceptance Model). This study used methods such as field surveys, structural equation modeling, and reliability and validity analyses to investigate the impact of Metro thermal comfort on passenger behavior safety. (3) Results: This study found that the Metro thermal environment, including temperature, humidity, and airflow velocity, significantly affects passengers’ comfort perception and behavior choices. (4) Conclusions: Passengers may exhibit avoidance behavior in uncomfortable thermal environments, leading to uneven distribution of people in the train car and increasing safety risks. Improving Metro thermal environments can effectively enhance passengers’ perceived comfort and reduce unsafe behavior motivation, which is of great significance for safe Metro operations. Full article
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18 pages, 6296 KiB  
Article
Vehicle-Mounted SRM DITC Strategy Based on Optimal Switching Angle TSF
by Hongyao Wang, Jingbo Wu, Chengwei Xie and Zhijun Guo
World Electr. Veh. J. 2025, 16(1), 26; https://doi.org/10.3390/wevj16010026 - 6 Jan 2025
Viewed by 81
Abstract
Switched reluctance motors (SRMs) offer several advantages, including a magnet- and winding-free rotor, high mechanical strength, and exceptional output efficiency. However, the doubly salient pole structure and high-frequency switching power supply result in significant torque ripple and electromagnetic noise, which limit the application [...] Read more.
Switched reluctance motors (SRMs) offer several advantages, including a magnet- and winding-free rotor, high mechanical strength, and exceptional output efficiency. However, the doubly salient pole structure and high-frequency switching power supply result in significant torque ripple and electromagnetic noise, which limit the application in the field of new energy vehicles. To address these issues, this paper proposes a direct instantaneous torque control (DITC) strategy based on an optimal switching angle torque sharing function (TSF). Firstly, an improved cosine TSF is designed to reasonably distribute the total reference torque among the phases, stabilizing the synthesized torque of SRM during the commutation interval. Subsequently, an improved artificial bee colony (ABC) algorithm is used to obtain the optimal switching angle data at various speeds, integrating these data into the torque distribution module to derive the optimal switching angle model. Finally, the effectiveness of the proposed control strategy is validated through simulations of an 8/6-pole SRM. Simulation results demonstrate that the proposed control strategy effectively suppresses torque ripple during commutation and reduces the peak current at the beginning of phase commutation. Full article
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18 pages, 6766 KiB  
Article
Study on Deformation Mechanism and Surrounding Rock Strata Control in End-Mining Retracement Roadway in Closely Spaced Coal Seams
by Bin Wang, Hui Liu, Dong Liu, Jie Zhang and Haifei Lin
Appl. Sci. 2025, 15(1), 436; https://doi.org/10.3390/app15010436 - 5 Jan 2025
Viewed by 396
Abstract
This paper aims to address the issue of hydraulic support crushing accidents or support failures in the retracement roadway (RR) that frequently occurs when a fully mechanized mining face is retraced during the end-mining stage. The deformation and instability mechanism of surrounding rock [...] Read more.
This paper aims to address the issue of hydraulic support crushing accidents or support failures in the retracement roadway (RR) that frequently occurs when a fully mechanized mining face is retraced during the end-mining stage. The deformation and instability mechanism of surrounding rock in the RR during the end mining of a fully mechanized mining face at the Hanjiawan Coal Mine located in the northern Shaanxi mining area is explored through field measurement, theoretical analysis, similar simulation, and numerical simulation. The results reveal that the stability of the remaining coal pillar (RCP) and the fracture position of the main roof are the main factors contributing to large-scale dynamic load pressure in the RR during the end-mining stage. The plastic zone width limit of the RCP is identified to be 5.5 m. Furthermore, the stress distribution within the RCP during the end-mining stage is determined, and the linear relationship between the load borne by the RCP and the strength of the coal pillar is quantified. A similar simulation experiment is conducted to examine the collapse and instability characteristics of the overlying rock structure during the end-mining stage. UDEC (v.5.0) software is utilized to optimize the roof support parameters of the RR. A surrounding rock control technology that integrates the anchor net cable and hydraulic chock is proposed to ensure RR stability. Meanwhile, a method involving ceasing mining operations and waiting pressure is adopted to ensure a safe and smooth connection between the working face and the RR. This study provides a reference for the surrounding rock control of the RR during end mining in shallow, closely-spaced coal seams under similar conditions. Full article
(This article belongs to the Special Issue Advances in Green Coal Mining Technologies)
24 pages, 8540 KiB  
Article
Numerical Simulation of Free Surface Deformation and Melt Stirring in Induction Melting Using ALE and Level Set Methods
by Pablo Garcia-Michelena, Emilio Ruiz-Reina, Olaia Gordo-Burgoa, Nuria Herrero-Dorca and Xabier Chamorro
Materials 2025, 18(1), 199; https://doi.org/10.3390/ma18010199 - 5 Jan 2025
Viewed by 338
Abstract
This study investigates fixed and moving mesh methodologies for modeling liquid metal–free surface deformation during the induction melting process. The numerical method employs robust coupling of magnetic fields with the hydrodynamics of the turbulent stirring of liquid metal. Free surface tracking is implemented [...] Read more.
This study investigates fixed and moving mesh methodologies for modeling liquid metal–free surface deformation during the induction melting process. The numerical method employs robust coupling of magnetic fields with the hydrodynamics of the turbulent stirring of liquid metal. Free surface tracking is implemented using the fixed mesh level set (LS) and the moving mesh arbitrary Lagrangian–Eulerian (ALE) formulation. The model’s geometry and operating parameters are designed to replicate a semi-industrial induction melting furnace. Six case studies are analyzed under varying melt masses and coil power levels, with validation performed by comparing experimentally measured free surface profiles and magnetic field distributions. The melt’s stirring velocity and recirculation patterns are also examined. The comparative analysis determines an improved performance of the ALE method, convergence, and computational efficiency. Experimental validation confirms that the ALE method reproduces the free surface shape more precisely, avoiding unrealistic topological changes observed in LS simulations. The ALE method faces numerical convergence difficulties for high-power and low-mass filling cases due to mesh element distortion. The proposed ALE-based simulation procedure is a potential numerical optimization tool for enhancing induction melting processes, offering scalable and robust solutions for industrial applications. Full article
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34 pages, 2874 KiB  
Article
Annotated Checklist of Poroid Hymenochaetoid Fungi in Central Asia: Taxonomic Diversity, Ecological Roles, and Potential Distribution Patterns
by Yusufjon Gafforov, Manzura Yarasheva, Xue-Wei Wang, Milena Rašeta, Yelena Rakhimova, Lyazzat Kyzmetova, Kanaim Bavlankulova, Sylvie Rapior, Jia-Jian Chen, Ewald Langer, Burkhon Munnavarov, Zafar Aslonov, Bobozoda Bakokhoja and Li-Wei Zhou
J. Fungi 2025, 11(1), 37; https://doi.org/10.3390/jof11010037 - 5 Jan 2025
Viewed by 215
Abstract
Central Asia, located at the heart of Eurasia, is renowned for its varied climate and vertical vegetative distribution, which support diverse biomes and position it as a global biodiversity hotspot. Despite this ecological richness, Central Asia’s fungal diversity, particularly wood-inhabiting macrofungi, remains largely [...] Read more.
Central Asia, located at the heart of Eurasia, is renowned for its varied climate and vertical vegetative distribution, which support diverse biomes and position it as a global biodiversity hotspot. Despite this ecological richness, Central Asia’s fungal diversity, particularly wood-inhabiting macrofungi, remains largely unexplored. This study investigates the diversity, ecological roles, and potential distribution of poroid Hymenochaetoid fungi in the region. By conducting field surveys, collecting basidiomes, and reviewing the literature and herbarium records from five Central Asian countries, we compiled a comprehensive checklist of these fungi. In total, 43 Hymenochaetoid species belonging to 18 genera were identified, with Inonotus, Phellinus, and Phylloporia being the most species-rich. Notably, Inonotus hispidus and Phellinus igniarius were found to be the most widespread species. These macrofungi play essential ecological roles as saprotrophs and pathogens of various identified host plant families, aiding in lignin degradation and exhibiting diverse enzymatic activities. For the first time, we modelled the potential distribution patterns of Hymenochaetoid fungi in Central Asia, revealing that their distribution is strongly influenced by host plant availability and temperature-related factors. The three most critical variables were host plant density, annual temperature range (Bio7), and mean temperature of the warmest quarter (Bio10). The distribution of suitable habitats is uneven, with highly suitable areas (4.52%) concentrated in the mountainous border regions between Kazakhstan, Kyrgyzstan, Tajikistan, and Uzbekistan. These results underscore the significance of specific environmental conditions for the growth and survival of Hymenochaetoid fungi in this region. Our findings highlight the urgent need for continued mycological and host plant research and expanded conservation initiatives to document and preserve macrofungal and botanical biodiversity in this under-explored area. In light of climate change, the collected mycological and botanical data provide a valuable reference for promoting forest health management globally. Full article
(This article belongs to the Special Issue Diversity, Phylogeny and Ecology of Forest Fungi)
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20 pages, 3757 KiB  
Article
Analytical Solutions for Electroosmotic Flow and Heat Transfer Characteristics of Nanofluids in Circular Cylindrical Microchannels with Slip-Dependent Zeta Potential Considering Thermal Radiative Effects
by Zouqing Tan and Xiangcheng Ren
Micromachines 2025, 16(1), 63; https://doi.org/10.3390/mi16010063 - 5 Jan 2025
Viewed by 231
Abstract
This study analyzes the impact of slip-dependent zeta potential on the heat transfer characteristics of nanofluids in cylindrical microchannels with consideration of thermal radiation effects. An analytical model is developed, accounting for the coupling between surface potential and interfacial slip. The linearized Poisson–Boltzmann [...] Read more.
This study analyzes the impact of slip-dependent zeta potential on the heat transfer characteristics of nanofluids in cylindrical microchannels with consideration of thermal radiation effects. An analytical model is developed, accounting for the coupling between surface potential and interfacial slip. The linearized Poisson–Boltzmann equation, along with the momentum and energy conservation equations, is solved analytically to obtain the electrical potential field, velocity field, temperature distribution, and Nusselt number for both slip-dependent (SD) and slip-independent (SI) zeta potentials. Subsequently, the effects of key parameters, including electric double-layer (EDL) thickness, slip length, nanoparticle volume fraction, thermal radiation parameters, and Brinkman number, on the velocity field, temperature field, and Nusselt number are discussed. The results show that the velocity is consistently higher for the SD zeta potential compared to the SI zeta potential. Meanwhile, the temperature for the SD case is higher than that for the SI case at lower Brinkman numbers, particularly for a thinner EDL. However, an inverse trend is observed at higher Brinkman numbers. Similar trends are observed for the Nusselt number under both SD and SI zeta potential conditions at different Brinkman numbers. Furthermore, for a thinner EDL, the differences in flow velocity, temperature, and Nusselt number between the SD and SI conditions are more pronounced. Full article
(This article belongs to the Section C1: Micro/Nanoscale Electrokinetics)
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30 pages, 9935 KiB  
Article
A Versatile Workflow for Building 3D Hydrogeological Models Combining Subsurface and Groundwater Flow Modelling: A Case Study from Southern Sardinia (Italy)
by Simone Zana, Gabriele Macchi Ceccarani, Fabio Canova, Vera Federica Rizzi, Simone Simone, Matteo Maino, Daniele D’Emilio, Antonello Micaglio and Guido Bonfedi
Water 2025, 17(1), 126; https://doi.org/10.3390/w17010126 - 5 Jan 2025
Viewed by 443
Abstract
This research project aims to develop a basin-scaled 3D hydrogeological model by using Petrel E&P (Petrel 2021©) as the basis for a numerical groundwater flow model developed with “ModelMuse”. A relevant aspect of the project is the use of Petrel 2021© geologic modelling [...] Read more.
This research project aims to develop a basin-scaled 3D hydrogeological model by using Petrel E&P (Petrel 2021©) as the basis for a numerical groundwater flow model developed with “ModelMuse”. A relevant aspect of the project is the use of Petrel 2021© geologic modelling tools in the field of applied hydrogeology to improve the details of both hydrogeological and numerical groundwater flow models, and their predictive capabilities. The study area is located in South Sardinia (Campidano Plain), where previous hydrogeological and modelling studies were available. The hydrogeological model was developed by digitising and interpreting the facies in the available borehole logs; a grid was subsequently created, including the main hydrogeological surfaces and performing geostatistical modelling of the facies based on grain size percentages. Afterwards, an empiric formula, achieved from flow tests and laboratory analyses, was applied to the grain size distribution to obtain preliminary hydraulic conductivity values, calibrated during simulations. These simulations, under various groundwater head scenarios, established the boundary conditions and conductivity values needed to determine the hydrogeological balance of the study area. The probabilistic approach has produced a highly detailed model able to adequately represent the natural hydrogeological phenomena and the anthropic stresses in places underground. Full article
(This article belongs to the Section Hydrogeology)
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19 pages, 11895 KiB  
Article
Mapping Spatial Variability of Sugarcane Foliar Nitrogen, Phosphorus, Potassium and Chlorophyll Concentrations Using Remote Sensing
by Ericka F. Picado, Kerin F. Romero and Muditha K. Heenkenda
Geomatics 2025, 5(1), 3; https://doi.org/10.3390/geomatics5010003 - 5 Jan 2025
Viewed by 202
Abstract
Various nutrients are needed during the sugarcane growing season for plant development and productivity. However, traditional methods for assessing nutritional status are often costly and time consuming. This study aimed to determine the level of nitrogen (N), phosphorus (P), potassium (K) and chlorophyll [...] Read more.
Various nutrients are needed during the sugarcane growing season for plant development and productivity. However, traditional methods for assessing nutritional status are often costly and time consuming. This study aimed to determine the level of nitrogen (N), phosphorus (P), potassium (K) and chlorophyll of sugarcane plants using remote sensing. Remotely sensed images were obtained using a MicaSense RedEdge-P camera attached to a drone. Leaf chlorophyll content was measured in the field using an N-Tester chlorophyll meter, and leaf samples were collected and analyzed in the laboratory for N, P and K. The highest correlation between field samples and predictor variables (spectral bands, selected vegetation indices, and plant height from Light Detection and Ranging (LiDAR)), were noted.The spatial distribution of chlorophyll, N, P, and K maps achieved 60%, 75%, 96% and 50% accuracies, respectively. The spectral profiles helped to identify areas with visual differences. Spatial variability of nutrient maps confirmed that moisture presence leads to nitrogen and potassium deficiencies, excess phosphorus, and a reduction in vegetation density (93.82%) and height (2.09 m), compared to green, healthy vegetation (97.64% density and 3.11 m in height). This robust method of assessing foliar nutrients is repeatable for the same sugarcane variety at certain conditions and leads to sustainable agricultural practices in Costa Rica. Full article
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12 pages, 9337 KiB  
Article
Fourier Ptychographic Microscopy with Optical Aberration Correction and Phase Unwrapping Based on Semi-Supervised Learning
by Xuhui Zhou, Haiping Tong, Er Ouyang, Lin Zhao and Hui Fang
Appl. Sci. 2025, 15(1), 423; https://doi.org/10.3390/app15010423 - 5 Jan 2025
Viewed by 239
Abstract
Fourier ptychographic microscopy (FPM) has recently emerged as an important non-invasive imaging technique which is capable of simultaneously achieving high resolution, wide field of view, and quantitative phase imaging. However, FPM still faces challenges in the image reconstruction due to factors such as [...] Read more.
Fourier ptychographic microscopy (FPM) has recently emerged as an important non-invasive imaging technique which is capable of simultaneously achieving high resolution, wide field of view, and quantitative phase imaging. However, FPM still faces challenges in the image reconstruction due to factors such as noise, optical aberration, and phase wrapping. In this work, we propose a semi-supervised Fourier ptychographic transformer network (SFPT) for improved image reconstruction, which employs a two-stage training approach to enhance the image quality. First, self-supervised learning guided by low-resolution amplitudes and Zernike modes is utilized to recover pupil function. Second, a supervised learning framework with augmented training datasets is applied to further refine reconstruction quality. Moreover, the unwrapped phase is recovered by adjusting the phase distribution range in the augmented training datasets. The effectiveness of the proposed method is validated by using both the simulation and experimental data. This deep-learning-based method has potential applications for imaging thicker biology samples. Full article
(This article belongs to the Special Issue Advances in Optical Imaging and Deep Learning)
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27 pages, 4210 KiB  
Article
Magnetic Field Distribution and Energy Losses in a Permanent Magnet Linear Synchronous Motor Under Stick-Slip Friction
by Paweł Olejnik, Yared D. Desta and Marcin Mydłowski
Energies 2025, 18(1), 191; https://doi.org/10.3390/en18010191 - 4 Jan 2025
Viewed by 458
Abstract
This study investigates the modeling and dynamic analysis of three coupled electromechanical systems, emphasizing interactions between a magnetic linear drive and frictional contact with flat springs. The experimental setup includes a table driven by a three-phase permanent magnet linear synchronous motor (PMLSM) using [...] Read more.
This study investigates the modeling and dynamic analysis of three coupled electromechanical systems, emphasizing interactions between a magnetic linear drive and frictional contact with flat springs. The experimental setup includes a table driven by a three-phase permanent magnet linear synchronous motor (PMLSM) using an LMCA4 inductor, LMCAS3 magnetic track, and Xenus XTL controller. Mechanical phenomena such as stick-slip friction and impulsive loads are observed, particularly due to the rapid buckling of flat springs. These springs transition between sliding friction and fixation, impacting the motor’s operation during reciprocating velocity trajectories and generating acoustic emissions. Numerical simulations using COMSOL Multiphysics evaluate the magnetic field and system geometry in two- and three-dimensional spaces. Key findings include mechanical stick-slip vibrations, numerical modeling of the linear drive, and comparative analysis of experimental and simulated inductor current variations. Additionally, energy loss mechanisms under irregular loading conditions are assessed. The results highlight the coupling between friction-induced current changes and magnetic field variations, elucidating their impact on motor efficiency, vibration propagation, and acoustic emissions. The study provides insights into optimizing the design and reliability of coreless linear motors for precision applications under discontinuous loading. Full article
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25 pages, 7632 KiB  
Review
Solubility Characteristics and Microstructure of Bitumen: A Review
by Han Liu, Haibo Ding, Yanjun Qiu and Hinrich Grothe
Buildings 2025, 15(1), 135; https://doi.org/10.3390/buildings15010135 - 4 Jan 2025
Viewed by 379
Abstract
This is a comprehensive review of the significance of solubility theories, internal stability, and external compatibility within petroleum science and pavement engineering. The historical development and future trends of solubility methods in bitumen are discussed, emphasizing the importance of separating bitumen components based [...] Read more.
This is a comprehensive review of the significance of solubility theories, internal stability, and external compatibility within petroleum science and pavement engineering. The historical development and future trends of solubility methods in bitumen are discussed, emphasizing the importance of separating bitumen components based on solubility to establish a link with chemistry. The paper also highlights the development of solubility theories and various characterization tests for bitumen, as well as the distribution of functional groups of solvents and their parameters. Additionally, it explores the generation of solubility profiles for different types and aging states of bitumen based on solubility data and statistical correlation, and the use of stability diagrams to assess the internal stability of bitumen in different states. The potential for continued research in this field is emphasized to bridge the gap between fundamental chemistry and practical application, leading to improved formulations and enhanced performance of bitumen in various applications, ultimately resulting in more durable and stable pavement structures. Full article
(This article belongs to the Special Issue New Technologies for Asphalt Pavement Materials and Structures)
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21 pages, 10149 KiB  
Article
Minimizing Seam Lines in UAV Multispectral Image Mosaics Utilizing Irradiance, Vignette, and BRDF
by Hoyong Ahn, Chansol Kim, Seungchan Lim, Cheonggil Jin, Jinsu Kim and Chuluong Choi
Remote Sens. 2025, 17(1), 151; https://doi.org/10.3390/rs17010151 - 4 Jan 2025
Viewed by 263
Abstract
Unmanned aerial vehicle (UAV) imaging provides the ability to obtain high-resolution images at a lower cost than satellite imagery and aerial photography. However, multiple UAV images need to be mosaicked to obtain images of large areas, and the resulting UAV multispectral image mosaics [...] Read more.
Unmanned aerial vehicle (UAV) imaging provides the ability to obtain high-resolution images at a lower cost than satellite imagery and aerial photography. However, multiple UAV images need to be mosaicked to obtain images of large areas, and the resulting UAV multispectral image mosaics typically contain seam lines. To address this problem, we applied irradiance, vignette, and bidirectional reflectance distribution function (BRDF) filters and performed field work using a DJI Mavic 3 Multispectral (M3M) camera to collect data. We installed a calibrated reference tarp (CRT) in the center of the collection area and conducted three types of flights (BRDF, vignette, and validation) to measure the irradiance, radiance, and reflectance—which are essential for irradiance correction—using a custom reflectance box (ROX). A vignette filter was generated from the vignette parameter, and the anisotropy factor (ANIF) was calculated by measuring the radiance at the nadir, following which the BRDF model parameters were calculated. The calibration approaches were divided into the following categories: a vignette-only process, which solely applied vignette and irradiance corrections, and the full process, which included irradiance, vignette, and BRDF. The accuracy was verified through a validation flight. The radiance uncertainty at the seam line ranged from 3.00 to 5.26% in the 80% lap mode when using nine images around the CRT, and from 4.06 to 6.93% in the 50% lap mode when using all images with the CRT. The term ‘lap’ in ‘lap mode’ refers to both overlap and sidelap. The images that were subjected to the vignette-only process had a radiance difference of 4.48–6.98%, while that of the full process images was 1.44–2.40%, indicating that the seam lines were difficult to find with the naked eye and that the process was successful. Full article
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