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Volume 10
Issue 13
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Appl. Sci., Volume 10, Issue 13 (July-1 2020) – 272 articles

Cover Story (view full-size image): The stiffness properties of industrial robots are very important for many industrial applications, such as automatic robotic assembly and material removal processes (e.g., machining and deburring). On the one hand, in robotic assembly, joint compliance can be useful for compensating dimensional errors in the parts to be assembled; on the other hand, in material removal processes, a high Cartesian stiffness of the end-effector is required. In this paper, a compliant joint dynamic model of an industrial robot has been developed, in which joint stiffness has been experimentally identified using a modal approach. View this paper
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32 pages, 2821 KiB  
Article
Forensic Exchange Analysis of Contact Artifacts on Data Hiding Timestamps
by Da-Yu Kao
Appl. Sci. 2020, 10(13), 4686; https://doi.org/10.3390/app10134686 - 07 Jul 2020
Cited by 1 | Viewed by 3834
Abstract
When computer systems are increasingly important for our daily activities, cybercrime has created challenges for the criminal justice system. Data can be hidden in ADS (Alternate Data Stream) without hindering performance. This feature has been exploited by malware authors, criminals, terrorists, and intelligence [...] Read more.
When computer systems are increasingly important for our daily activities, cybercrime has created challenges for the criminal justice system. Data can be hidden in ADS (Alternate Data Stream) without hindering performance. This feature has been exploited by malware authors, criminals, terrorists, and intelligence agents to erase, tamper, or conceal secrets. However, ADS problems are much ignored in digital forensics. Rare researches illustrated the contact artifacts of ADS timestamps. This paper performs a sequence of experiments from an inherited variety and provides an in-depth overview of timestamp transfer on data hiding operations. It utilizes files or folders as original media and uses the timestamp rules as an investigative approach for the forensic exchange analysis of file sets. This paper also explores timestamp rules using case examples, which allow practical applications of crime scene reconstruction to real-world contexts. The experiment results demonstrate the effectiveness of temporal attributes, help digital forensic practitioners to uncover hidden relations, and trace the contact artifacts among crime scenes, victims, and suspects/criminals. Full article
(This article belongs to the Special Issue Human-Centered Computing and Information Security: Recent Advances & Intelligent Applications)
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19 pages, 15254 KiB  
Article
Influence of Body Weight Support Systems on the Abnormal Gait Kinematic
by Van-Thuc Tran, Kota Sasaki and Shin-ichiroh Yamamoto
Appl. Sci. 2020, 10(13), 4685; https://doi.org/10.3390/app10134685 - 07 Jul 2020
Cited by 6 | Viewed by 2940
Abstract
In recent years, the Body Weight Support system has been considered to be an indispensable component in gait training systems, which be used to improve the ability to walk of hemiplegic, stroke, and spinal cord injury patients. Previous studies investigated the influence of [...] Read more.
In recent years, the Body Weight Support system has been considered to be an indispensable component in gait training systems, which be used to improve the ability to walk of hemiplegic, stroke, and spinal cord injury patients. Previous studies investigated the influence of the Body Weight Support system on gait parameters were based on the implementation with healthy subjects or patients with high assistance. Consequently, the influences of the Body Weight Support systems on gait rehabilitation in clinical practice are still unclear and need further investigation. In this study, we investigated the effects of the two Body Weight Support systems, the active body weight support system and the Counter Weight system, on an abnormal gait, which was generated by restriction of the right knee joint and 3 kg-weight on the right ankle joint. Both Body Weight Support systems improve the gait parameters of the abnormal gait such as the center of mass, the center of pressure, margin of stability, and step parameters. The active Body Weight Support system with the unloading force modulation showed more advanced and better behavior in comparison with the Counter Weight system. The results suggested the applicability of two Body Weight Support systems in clinical practice as a recovered gait intervention. Full article
(This article belongs to the Section Applied Biosciences and Bioengineering)
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13 pages, 4492 KiB  
Article
Seismic Behavior of RC Beam Column Joints with 600 MPa High Strength Steel Bars
by Jian Feng, Shuo Wang, Marco Meloni, Qian Zhang, Jingwen Yang and Jianguo Cai
Appl. Sci. 2020, 10(13), 4684; https://doi.org/10.3390/app10134684 - 07 Jul 2020
Cited by 14 | Viewed by 3453
Abstract
This paper presents an experimental investigation of the seismic performance of interior beam–column joints with beams reinforced with Grade 600MPa longitudinal steel bars. Six full-scale reinforcement concrete (RC) interior joints are designed with different axial compression ratios and longitudinal reinforcement ratios, which are [...] Read more.
This paper presents an experimental investigation of the seismic performance of interior beam–column joints with beams reinforced with Grade 600MPa longitudinal steel bars. Six full-scale reinforcement concrete (RC) interior joints are designed with different axial compression ratios and longitudinal reinforcement ratios, which are tested under reversed cyclic loading. Failure modes, hysteretic curves, skeleton curves, energy dissipation capacity, and the ductility of joints are investigated systematically. Moreover, the effect of the different axial compression ratios and longitudinal reinforcement ratios on the seismic behavior of the joints are deeply studied. Comparisons performed between specimens demonstrate that among the beam–column joints with 600 MPa high strength steel bars, specimens with high reinforcement ratios have better energy dissipation capacity, slower stiffness degradation, and lower ductility. Moreover, with the increase of the axial compression ratios, the energy dissipation capacity and ductility become weaker. The test results show the favorable seismic properties of beam–column joints equipped with 600 MPa high strength steel bars, which can be regarded as the research basis of the popularization and application of 600 MPa high strength steel bars in reinforcement concrete frame structures. Full article
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15 pages, 3081 KiB  
Article
A Study on the Evaluation Method of Autonomous Emergency Vehicle Braking for Pedestrians Test Using Monocular Cameras
by Bong-Ju Kim and Seon-Bong Lee
Appl. Sci. 2020, 10(13), 4683; https://doi.org/10.3390/app10134683 - 07 Jul 2020
Cited by 4 | Viewed by 2991
Abstract
Traffic accidents continue to increase in Korea as traffic increases, and the resulting loss of life is also on the rise. According to data surveyed by the South Korean National Police Agency, 45,921 pedestrian traffic accidents were reported in 2019, resulting in 1487 [...] Read more.
Traffic accidents continue to increase in Korea as traffic increases, and the resulting loss of life is also on the rise. According to data surveyed by the South Korean National Police Agency, 45,921 pedestrian traffic accidents were reported in 2019, resulting in 1487 deaths and 46,400 injuries. Due to the increased interest in traffic accident safety, the Advanced Driver Assistance System (ADAS) concept is rapidly developing and playing a significant role in coping with activities that are not recognized by the driver. Autonomous Emergency Braking (AEB), a representative ADAS system, is a system that is useful for preventing and mitigating accidents by braking vehicles in emergencies. For the study of AEBs’ safety evaluation methods for pedestrians, a distance measurement method using a monocular camera with excellent accessibility, and measurement equipment required to validate data on the movement of vehicles, and a dummy to replace pedestrians are used. Based on the evaluation scenario considering the proposed Korea road environment, the relative distance obtained from equipment like DGPS and the relative distance using a monocular camera is compared and analyzed to verify safety. Comparative analysis shows that the minimum deviation is 2.3 cm, the third test result of 30 km/h of Car-to-Pedestrian Nearside Child (CPNC), and the maximum deviation is 25 cm, the first test result of 25 km/h of Car-to-Pedestrian Nearside Adult (CPNA). The main factor in error generation is that the lane recognition in the camera image is not accurate, and the perception of small children is slow, which is why emergency braking is considered to have been slow. It is deemed that a safety assessment in weather conditions of adverse conditions will be required in the future. Full article
(This article belongs to the Special Issue Advanced Engine Technologies and Innovative Vehicle Driving Systems)
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14 pages, 3388 KiB  
Article
Discrete Optimization of a Gear Pump after Tooth Root Undercutting by Means of Multi-Dimensional Logic Functions
by Marian A. Partyka and Maria Natorska
Appl. Sci. 2020, 10(13), 4682; https://doi.org/10.3390/app10134682 - 07 Jul 2020
Cited by 2 | Viewed by 1921
Abstract
In this paper, the optimization of a gear pump after tooth root undercutting has been investigated; this requires the volumetric, mechanical and total efficiencies of the pump to be calculated. Due to conflict in the existing model, the total efficiency is often calculated [...] Read more.
In this paper, the optimization of a gear pump after tooth root undercutting has been investigated; this requires the volumetric, mechanical and total efficiencies of the pump to be calculated. Due to conflict in the existing model, the total efficiency is often calculated with the assumption that the other efficiencies have acceptable values. Multiple-dimensional logical functions are an additional independent method that can be used for the optimization of a pump. Full article
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15 pages, 4799 KiB  
Article
Study on Cold Resistance Performance of Composite Subgrade Structure in Seasonal Frozen Regions
by Leilei Han, Haibin Wei, Yong Zhang, Ji Zhang and Fuyu Wang
Appl. Sci. 2020, 10(13), 4681; https://doi.org/10.3390/app10134681 - 07 Jul 2020
Cited by 3 | Viewed by 1750
Abstract
In order to achieve the purpose of subgrade frost damage control and waste utilization, this paper proposes a specific kind of composite subgrade structure which is suitable for subgrade in seasonal frozen regions, especially wet subgrade. The composite subgrade structure is composed of [...] Read more.
In order to achieve the purpose of subgrade frost damage control and waste utilization, this paper proposes a specific kind of composite subgrade structure which is suitable for subgrade in seasonal frozen regions, especially wet subgrade. The composite subgrade structure is composed of extruded polystyrene (XPS) plates as a cold resistance layer and modified subgrade soil with excellent frost resistance which can consume a lot of oil shale residue and fly ash. To provide valuable reference for engineering applications, an outdoor model test is designed and carried out based on indoor test results and actual engineering data. The cold resistance performance of this new type subgrade structure is evaluated by comparing the temperature distribution, energy transfer, and freezing index of the composite subgrade and the common subgrade during the freezing process. The results show that, firstly, the cold resistance layer can effectively preserve temperature inside the subgrade and form a positive temperature zone beneath XPS plates, which can ensure that the subgrade soil in a certain range will not freeze during the freezing period. Secondly, the position with the best cold resistance effect of the cold resistance layer is directly under the XPS plate. In actual application, the key position should be covered as completely as possible by XPS plates to ensure the cold resistance effect. Thirdly, the cold resistance layer can not only protect subgrade soil under XPS plates from frost damage, but also raise and keep the service temperature of the structure above XPS plates in a certain range, which is beneficial to the cold resistance durability of the entire road. This means that the composite subgrade can greatly reduce the occurrence of subgrade frost damage, thereby even improving the service capability of roads in seasonal frozen regions. Full article
(This article belongs to the Section Civil Engineering)
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20 pages, 6220 KiB  
Article
Research and Implementation of Axial 3D Printing Method for PLA Pipes
by Haiguang Zhang, Wenguang Zhong, Qingxi Hu, Mohamed Aburaia, Joamin Gonzalez-Gutierrez and Herfried Lammer
Appl. Sci. 2020, 10(13), 4680; https://doi.org/10.3390/app10134680 - 07 Jul 2020
Cited by 10 | Viewed by 2875
Abstract
Additive manufacturing has been applied in many fields, but its layer-by-layer fabrication process leads to a weak inter-layer bond strength of printed parts, so it cannot meet the higher requirements for mechanical properties of the industry. At present, many researchers are studying the [...] Read more.
Additive manufacturing has been applied in many fields, but its layer-by-layer fabrication process leads to a weak inter-layer bond strength of printed parts, so it cannot meet the higher requirements for mechanical properties of the industry. At present, many researchers are studying the printing path planning method to improve the mechanical properties of printed parts. This paper proposes a method to plan the printing path according to the actual stress of pipe parts, and introduces the realization process of an algorithm in detail, and obtains the printing control G-code. Additionally, a 5-axis material extrusion platform was built to realize the printing of polylactic acid pipes with plane and space skeleton curves, respectively, which verified the feasibility and applicability of the method and the correctness of the planning path with standard material extrusion filaments. Finally, the tensile and bending experiments prove that axial printing enhances the mechanical properties of pipe parts. Full article
(This article belongs to the Special Issue Material Development for Additive Manufacturing and Injection Moulding)
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19 pages, 4493 KiB  
Article
Evaluation of Polyethylene Glycol Crosslinked β-CD Polymers for the Removal of Methylene Blue
by Isabelle Mallard, David Landy and Sophie Fourmentin
Appl. Sci. 2020, 10(13), 4679; https://doi.org/10.3390/app10134679 - 07 Jul 2020
Cited by 13 | Viewed by 4208
Abstract
The environment is at the heart of global worldwide discussion. This study describes the synthesis of ecofriendly polymers by a crosslinking reaction between β-cyclodextrin as the monomer and polyethylene glycol diglycidyl ether (PEDGE) as well as ethylene diglycidyl ether (EDGE) as the crosslinking [...] Read more.
The environment is at the heart of global worldwide discussion. This study describes the synthesis of ecofriendly polymers by a crosslinking reaction between β-cyclodextrin as the monomer and polyethylene glycol diglycidyl ether (PEDGE) as well as ethylene diglycidyl ether (EDGE) as the crosslinking agents. The studied polymers were characterized by several techniques, such as SEM, FTIR, TGA-TDA and XRD. Their adsorption properties for methylene blue under various conditions of pH, contact time and initial concentration of dye were assessed in order to find the optimal conditions. The results indicate that the polymers are good nominates for methylene blue adsorption with adsorption capacities up to 15 mg/g. The adsorption mechanism was demonstrated to follow the Langmuir model. Finally, the regeneration of the polymers was investigated using Soxhlet extraction with ethanol. The absorption capacities of the adsorbent were stable after three cycles. Full article
(This article belongs to the Special Issue Cyclodextrin-Based Materials and Applications)
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31 pages, 31523 KiB  
Article
Digital Twin and Web-Based Virtual Gaming Technologies for Online Education: A Case of Construction Management and Engineering
by Samad M.E. Sepasgozar
Appl. Sci. 2020, 10(13), 4678; https://doi.org/10.3390/app10134678 - 07 Jul 2020
Cited by 117 | Viewed by 14571
Abstract
Mixed reality is advancing exponentially in some innovative industries, including manufacturing and aerospace. However, advanced applications of these technologies in architecture, engineering, and construction (AEC) businesses remain nascent. While it is in demand, the use of these technologies in developing the AEC digital [...] Read more.
Mixed reality is advancing exponentially in some innovative industries, including manufacturing and aerospace. However, advanced applications of these technologies in architecture, engineering, and construction (AEC) businesses remain nascent. While it is in demand, the use of these technologies in developing the AEC digital pedagogy and for improving professional competence have received little attention. This paper presents a set of five novel digital technologies utilising virtual and augmented reality and digital twin, which adds value to the literature by showing their usefulness in the delivery of construction courses. The project involved designing, developing, and implementing a construction augmented reality (AR), including Piling AR (PAR) and a virtual tunnel boring machine (VTBM) module. The PAR is a smartphone module that presents different elements of a building structure, the footing system, and required equipment for footing construction. VTBM is developed as a multiplayer and avatar-included module for experiencing mechanisms of a tunnel boring machine. The novelty of this project is that it developed innovative immersive construction modules, practices of implementing digital pedagogy, and presenting the capacity of virtual technologies for education. This paper is also highly valuable to educators since it shows how a set of simple to complex technologies can be used for teaching various courses from a distance, either in emergencies such as corona virus disease (COVID-19) or as a part of regular teaching. This paper is a step forward to designing future practices full of virtual education appropriate to the new generation of digitally savvy students. Full article
(This article belongs to the Special Issue Digital Twins in Industry)
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14 pages, 1525 KiB  
Review
Cryobiotechnology of Plants: A Hot Topic Not Only for Gene Banks
by Petra Jiroutová and Jiří Sedlák
Appl. Sci. 2020, 10(13), 4677; https://doi.org/10.3390/app10134677 - 07 Jul 2020
Cited by 9 | Viewed by 4075
Abstract
Agriculture has always been an important part of human evolution. Traditionally, farming is changing and developing with regard to challenges it faces. The major challenges of modern agriculture are food and nutrition safety for the growing world population. Promoting species and genetic diversity [...] Read more.
Agriculture has always been an important part of human evolution. Traditionally, farming is changing and developing with regard to challenges it faces. The major challenges of modern agriculture are food and nutrition safety for the growing world population. Promoting species and genetic diversity in agriculture appears to be an important approach to dealing with those challenges. Gene banks all around the world play a crucial role in preserving plant genetic resources for future crop improvements. The plant germplasm can be preserved in different ways, depending on the species or form of stored plant tissue. This review focuses on a special preservation method—cryopreservation. Cryopreservation is an effective technique for storing living systems at ultra-low temperatures, usually in liquid nitrogen or its vapor phase. This conservation method is crucial for plants that do not produce seeds or that produce non germinating seeds, as well as for plants that propagate vegetatively. Moreover, based on the cryopreservation method, a novel plant biotechnology tool for pathogen eradication called cryotherapy has been developed. The use of liquid nitrogen eliminates plant pathogens such as viruses, phytoplasmas, and bacteria. Our article reviews recent advances in cryo-biotechnologies such as cryopreservation and cryotherapy, with special focus on studies concerning fruit plants. Full article
(This article belongs to the Special Issue New Trends in Environmental Engineering, Agriculture, Food Production, and Analysis)
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16 pages, 4937 KiB  
Article
Cutting Force Prediction and Experiment Verification of Paper Honeycomb Materials by Ultrasonic Vibration-Assisted Machining
by Wenjun Cao, Jun Zha and Yaolong Chen
Appl. Sci. 2020, 10(13), 4676; https://doi.org/10.3390/app10134676 - 07 Jul 2020
Cited by 16 | Viewed by 3018
Abstract
The disc-cutter is a finishing tool for the ultrasonic-cutting of paper honeycomb-core material. The cutting state directly affects the machining accuracy and surface quality of the workpiece. The cutting force is an important physical quantity and the cause of ultrasonic cutting defects of [...] Read more.
The disc-cutter is a finishing tool for the ultrasonic-cutting of paper honeycomb-core material. The cutting state directly affects the machining accuracy and surface quality of the workpiece. The cutting force is an important physical quantity and the cause of ultrasonic cutting defects of the honeycomb-core material. Due to differences in the mechanical properties and cutting performance of honeycomb-core materials and commonly used metal materials, existing metal-cutting-force models cannot be applied to the calculation of ultrasonic cutting forces in the processing of honeycomb-core materials. In response to this problem—combined with actual working conditions using the ABAQUS finite element analysis software—a finite element simulation model of the ultrasonic vibration-assisted cutting force of the disc-cutter on the honeycomb-core material was established, and the cutting curves and values were obtained. The experiment of ultrasonic vibration cutting of the disc-cutter proves that from the surface morphology of the honeycomb core, the milling-width has the greatest influence on the cutting force, and the cutting-depth has the smallest influence on the cutting force. The maximum error between the cutting force experimental results and the finite element simulation results under the same cutting conditions was 13.2%, which means that the established cutting-force finite element model is more accurate and can be used to predict the cutting in honeycomb ultrasonic vibration-assisted cutting-force value. Finally, based on the response surface method, a three-dimensional cutting force prediction model of the ultrasonic cutting honeycomb core of the disc-cutter was established by using the simulation model data. The results of this study can provide a useful basis for the improvement of cutting performance and processing efficiency in the processing of paper honeycomb-core materials. Full article
(This article belongs to the Section Mechanical Engineering)
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17 pages, 5908 KiB  
Article
Bearing Capacity of Ring Foundations on Sand Overlying Clay
by Chaowei Yang, Zhiren Zhu and Yao Xiao
Appl. Sci. 2020, 10(13), 4675; https://doi.org/10.3390/app10134675 - 07 Jul 2020
Cited by 12 | Viewed by 4097
Abstract
The vertical bearing capacity of rough ring foundations resting on a sand layer overlying clay soil is computed in this study by using finite element limit analysis (FELA). The sands and clays are assumed as elastoplastic models, obeying Mohr–Coulomb and Tresca failure criteria, [...] Read more.
The vertical bearing capacity of rough ring foundations resting on a sand layer overlying clay soil is computed in this study by using finite element limit analysis (FELA). The sands and clays are assumed as elastoplastic models, obeying Mohr–Coulomb and Tresca failure criteria, respectively. Based on the FELA results, design charts are provided for evaluating the ultimate bearing capacity of ring foundations, which is related to the undrained shear strength of the clay, the thickness, the internal friction angle, the unit weight of the sand layer, and the ratio of the internal radius to the external radius of the footing. A certain thickness, beyond which the clay layer has a negligible effect on the bearing capacity, is determined. The collapse mechanisms are also examined and discussed. Full article
(This article belongs to the Section Civil Engineering)
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23 pages, 8166 KiB  
Article
A Smart Parking Solution Architecture Based on LoRaWAN and Kubernetes
by Jhonattan J. Barriga, Juan Sulca, José León, Alejandro Ulloa, Diego Portero, José García and Sang Guun Yoo
Appl. Sci. 2020, 10(13), 4674; https://doi.org/10.3390/app10134674 - 07 Jul 2020
Cited by 13 | Viewed by 5244
Abstract
Finding a parking space in a city is one of the most common activities of a driver. This becomes more difficult when the city is unknown or has huge vehicular congestion. A solution to address this issue is called smart parking. Smart parking [...] Read more.
Finding a parking space in a city is one of the most common activities of a driver. This becomes more difficult when the city is unknown or has huge vehicular congestion. A solution to address this issue is called smart parking. Smart parking solutions rely on Internet of Things (IoT) and several technologies to achieve their purpose. This paper proposes an architecture for deploying a smart parking solution based on Long-Range Wide Area Network (LoRaWAN) sensors, LoRaWAN and a cluster of Kubernetes. This approach provides an open architecture able to share information with other parties through a REST API interface. Likewise, it contains a mobile and a web application for user interaction. This solution provides an administration interface for managing parking lots. The user interface lets a user to find, view information, display available spaces and rate a parking lot in real time. This solution could be used as an application as service parking system. The proposed architecture is fully portable and scalable due to the use of Kubernetes. Full article
(This article belongs to the Special Issue Internet of Things (IoT))
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8 pages, 1651 KiB  
Article
Subpopulations of Organoid-Forming Cells Have Different Motility
by David Gomez Jimenez, Sofia Carreira Santos, Lennart Greiff, Kersti Alm and Malin Lindstedt
Appl. Sci. 2020, 10(13), 4673; https://doi.org/10.3390/app10134673 - 07 Jul 2020
Cited by 1 | Viewed by 3602
Abstract
Cancer stem cells from oropharyngeal squamous cell carcinoma (OPSCC) have the ability to self-renew and differentiate into heterogeneous three-dimensional structures carrying features of tumor cells. Here, we describe a simple and label-free method for generating tumor organoids, and imaging them using live digital [...] Read more.
Cancer stem cells from oropharyngeal squamous cell carcinoma (OPSCC) have the ability to self-renew and differentiate into heterogeneous three-dimensional structures carrying features of tumor cells. Here, we describe a simple and label-free method for generating tumor organoids, and imaging them using live digital holographic microscopy (DHM) on the basis of the phase shift caused by light passing through the cells. We show early events of cell aggregation during tumor-organoid formation, and display their heterogeneity in terms of optical parameters up to an optical volume of 105 µm3. Lastly, by sorting OPSCC epithelial cells, we demonstrate that CD44+ cells displayed greater motility and tumor-forming capacity than those of CD44− cells. These results were in line with previous reports highlighting increased invasive and tumorigenic potential in tumor cells expressing high levels of CD44. Our method provides insight into the formation of tumor organoids, and could be used to assess stemness-associated biomarkers and drug screenings on the basis of tumor organoids. Full article
(This article belongs to the Special Issue Applications of Digital Holography in Biomedical Engineering)
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16 pages, 5997 KiB  
Article
DC Converter with Wide Soft Switching Operation, Wide Input Voltage and Low Current Ripple
by Bor-Ren Lin and Guan-Hong Lin
Appl. Sci. 2020, 10(13), 4672; https://doi.org/10.3390/app10134672 - 07 Jul 2020
Cited by 3 | Viewed by 2342
Abstract
A soft switching current-source resonant converter is presented and implemented for wide voltage applications such as fuel cells and solar power. An LLC (inductor–inductor–capacitor) converter is adopted to accomplish zero voltage (current) operation on active switches (diodes). Thus, the circuit efficiency is increased. [...] Read more.
A soft switching current-source resonant converter is presented and implemented for wide voltage applications such as fuel cells and solar power. An LLC (inductor–inductor–capacitor) converter is adopted to accomplish zero voltage (current) operation on active switches (diodes). Thus, the circuit efficiency is increased. The interleaved pulse-width modulation (PWM) converter is employed on the input side to accomplish low input ripple current. A hybrid LLC converter is adopted to achieve wide voltage operation from Vin, min to 4Vin, min and to improve the weakness of a conventional LLC converter. Half-bridge diode rectification is employed on the output side to decrease power loss on the rectifier diode. To confirm the theoretical analysis and feasibility, experimental verifications with a 500-W prototype are demonstrated in this paper. Full article
(This article belongs to the Special Issue Resonant Converter in Power Electronics Technology)
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18 pages, 5749 KiB  
Article
Assessing the Performance of the Multi-Beam Echo-Sounder Bathymetric Uncertainty Prediction Model
by Tannaz H. Mohammadloo, Mirjam Snellen and Dick G. Simons
Appl. Sci. 2020, 10(13), 4671; https://doi.org/10.3390/app10134671 - 07 Jul 2020
Cited by 12 | Viewed by 4208
Abstract
Realistic predictions of the contribution of the various sources affecting the quality of the bathymetric measurements prior to a survey are of importance to ensure sufficient accuracy of the soundings. To this end, models predicting these contributions have been developed. The objective of [...] Read more.
Realistic predictions of the contribution of the various sources affecting the quality of the bathymetric measurements prior to a survey are of importance to ensure sufficient accuracy of the soundings. To this end, models predicting these contributions have been developed. The objective of the present paper is to assess the performance of the bathymetric uncertainty prediction model for modern Multi-Beam Echo-Sounder (MBES) systems. Two datasets were acquired at water depths of 10 m and 30 m with three pulse lengths equaling 27 s , 54 s , and 134 s in the Oosterschelde estuary (The Netherlands). The comparison between the bathymetric uncertainties derived from the measurements and those predicted using the current model indicated a relatively good agreement except for the most outer beams. The performance of the uncertainty prediction model improved by accounting for the most recent insights into the contributors to the MBES depth uncertainties, i.e., the Doppler effect, baseline decorrelation (accounting for the pulse shape), and the signal-to-noise ratio. Full article
(This article belongs to the Special Issue Modelling, Simulation and Data Analysis in Acoustical Problems Ⅱ)
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28 pages, 6475 KiB  
Article
Valorization of Slags Produced by Smelting of Metallurgical Dusts and Lateritic Ore Fines in Manufacturing of Slag Cements
by Theofani Tzevelekou, Paraskevi Lampropoulou, Panagiota P. Giannakopoulou, Aikaterini Rogkala, Petros Koutsovitis, Nikolaos Koukouzas and Petros Petrounias
Appl. Sci. 2020, 10(13), 4670; https://doi.org/10.3390/app10134670 - 07 Jul 2020
Cited by 12 | Viewed by 3502
Abstract
A pyrometallurgical process was developed for the recycling of Ni bearing dusts and laterite ore fines by direct reduction smelting in DC (direct current) arc furnace. In the course of the performed industrial trials, besides the Ni-recovery in the liquid bath, slag composition [...] Read more.
A pyrometallurgical process was developed for the recycling of Ni bearing dusts and laterite ore fines by direct reduction smelting in DC (direct current) arc furnace. In the course of the performed industrial trials, besides the Ni-recovery in the liquid bath, slag composition was deliberately adjusted in order to produce a series of metallurgical slags with different chemical and mineralogical composition. The aim of this study was to investigate their suitability as clinker substitute in cement manufacturing. Examined parameters were slag FeOx content, basicity and applied cooling media (air, water cooling). A series of composite Portland and slag cements were manufactured in laboratory scale incorporating 20% and 40% of each slag, respectively; the rest being clinker of OPC (ordinary Portland cement) and 5% gypsum. The extended mineralogical analysis and microstructural properties of the produced slags were examined and correlated with the properties of the produced cements. The physical and mechanical characteristics of all examined cement products were found to meet the requirements of the regulation set for cements. The present research revealed that the most critical parameter in the compressive strength development of the slag cements is the mineralogical composition of the slag. Even in cases where rapid cooling to obtain glassy matrix is not feasible, adjustment of slag analysis to obtain mineralogical phases similar to those met in clinker of OPC, even at higher FeO contents (up to ~21wt.%), can result in production of slag with considerable latent hydraulic properties. These results indicate that there is potentially space for adjustments in conventional EAF (electric arc furnace) steel slags composition to allow for their wider use in cement manufacturing with significant environmental and economic benefits resulting from the reduction of energy requirements, CO2 emissions and natural raw materials consumption. Full article
(This article belongs to the Special Issue Climate Change, Carbon Capture, Storage and CO2 Mineralisation Technologies)
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17 pages, 7190 KiB  
Article
Multi-Pose Face Recognition Based on Deep Learning in Unconstrained Scene
by Shuai Ruan, Chaowei Tang, Xu Zhou, Zhuoyi Jin, Shiyu Chen, Haotian Wen, Hongbin Liu and Dong Tang
Appl. Sci. 2020, 10(13), 4669; https://doi.org/10.3390/app10134669 - 07 Jul 2020
Cited by 11 | Viewed by 5171
Abstract
At present, deep learning drives the rapid development of face recognition. However, in the unconstrained scenario, the change of facial posture has a great impact on face recognition. Moreover, the current model still has some shortcomings in accuracy and robustness. The existing research [...] Read more.
At present, deep learning drives the rapid development of face recognition. However, in the unconstrained scenario, the change of facial posture has a great impact on face recognition. Moreover, the current model still has some shortcomings in accuracy and robustness. The existing research has formulated two methods to solve the above problems. One method is to model and train each pose separately. Then, a fusion decision will be made. The other method is to make “frontal” faces on the image or feature level and transform them into “frontal” face recognition. Based on the second idea, we propose a profile to the frontal revise mapping (PTFRM) module. This module realizes the revision of arbitrary poses on the feature level and transforms the multi-pose features into an approximate frontal representation to enhance the recognition ability of the existing recognition models. Finally, we evaluate the PTFRM on unconstrained face validation benchmark datasets such as Labeled Faces in the Wild (LFW), Celebrities in Frontal Profile (CFP), and IARPA Janus Benchmark A(IJB-A). Results show that the chosen method for this study achieves good performance. Full article
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23 pages, 2979 KiB  
Article
A Study on Aeroengine Conceptual Design Considering Multi-Mission Performance Reliability
by Dalu Cao and Guangchen Bai
Appl. Sci. 2020, 10(13), 4668; https://doi.org/10.3390/app10134668 - 07 Jul 2020
Cited by 13 | Viewed by 2571
Abstract
Owing to the realization of multi-mission adaptability requires more complex mechanical structure, the candidates of future aviation propulsion are confronted with more overall reliability problems than that of the conventional gas turbine engine. This situation is challenging to a traditional aeroengine deterministic design [...] Read more.
Owing to the realization of multi-mission adaptability requires more complex mechanical structure, the candidates of future aviation propulsion are confronted with more overall reliability problems than that of the conventional gas turbine engine. This situation is challenging to a traditional aeroengine deterministic design method. To overcome this challenge, the Reliability-based Multi-Design Point Methodology is proposed for aeroengine conceptual design. The presented methodology adopted an unconventional approach of engaging the reliability prediction by artificial neural network (ANN) surrogate models rather than the time-consuming Monte Carlo (MC) simulation. Based on the Adaptive Particle swarm optimization, the utilization of the pre-training technique optimizes the initial network parameters to acquire better-conditioned initial network, which is sited closer to designated optimum so that contributes to the convergence property. Moreover, a new hybrid algorithm is presented to integrate the pre-training technique into neural network training procedure in order to enhance the ANN performance. The proposed methodology is applied to the cycle design of a turbofan engine with uncertainty component performance. The testing results certify that the prediction accuracy of pre-trained ANN is improved with negligible computational cost, which only spent nearly one-millionth as much time as the MC-based probabilistic analysis (0.1267 s vs. 95,262 s, for 20 testing samples). The MC simulation results substantiate that optimal cycle parameters precisely improve the engine overall performance to simultaneously reach expected reliability (≥98.9%) in multiple operating conditions without unnecessary performance redundancy, which verifies the efficiency of the presented methodology. The presented efforts provide a novel approach for aeroengine cycle design, and enrich reliability design theory as well. Full article
(This article belongs to the Section Aerospace Science and Engineering)
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13 pages, 1916 KiB  
Article
Allogeneic Demineralized Dentin Matrix Graft for Guided Bone Regeneration in Dental Implants
by In-Woong Um, Jeong-Kui Ku, Yu-Mi Kim, Pil-Young Yun, Na-Hee Chang, Young-Kyun Kim and Yonghoon Choi
Appl. Sci. 2020, 10(13), 4661; https://doi.org/10.3390/app10134661 - 07 Jul 2020
Cited by 16 | Viewed by 4394
Abstract
Autogenous and allogeneic demineralized dentin matrices (Auto-DDM and Allo-DDM, respectively) are currently used for guided bone regeneration (GBR). Buccal marginal bone (BMB) resorption is critical for successful implant integration. This study analyzed BMB resorption around dental implants for GBR between the control group [...] Read more.
Autogenous and allogeneic demineralized dentin matrices (Auto-DDM and Allo-DDM, respectively) are currently used for guided bone regeneration (GBR). Buccal marginal bone (BMB) resorption is critical for successful implant integration. This study analyzed BMB resorption around dental implants for GBR between the control group (Auto-DDM graft) and experimental group (Allo-DDM graft). From 2014 to 2019, we enrolled 96 patients (59 males, 37 females, average 57.13 years) who received GBR (52 and 44 using Allo-DDM and Auto-DDM, respectively,) without a barrier membrane and a simultaneous single dental implantation (54 in the maxilla and 42 in the mandible). BMB height was measured immediately after GBR, at prosthetic loading, and 12 months after loading. BMB resorption was classified as initial resorption (between GBR and prosthetic loading) and functional resorption (during 12 months after prosthetic loading). The differences in the BMB levels of Auto-DDM and Allo-DDM were analyzed between the initial and functional resorption stages by independent sample t-test. Auto-DDM and Allo-DDM showed similar BMB changes in initial resorption (0.73 ± 0.97 and 0.72 ± 0.77 mm, respectively) and functional resorption (0.69 ± 0.81 and 0.48 ± 0.58 mm, respectively) without a significant difference between the maxilla and mandible. For GBR, Allo-DDM is comparable to Auto-DDM in terms of BMB resorption. Full article
(This article belongs to the Special Issue Implant Dentistry)
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13 pages, 2686 KiB  
Article
Performance Evaluation of Autonomous Driving Control Algorithm for a Crawler-Type Agricultural Vehicle Based on Low-Cost Multi-Sensor Fusion Positioning
by Joong-hee Han, Chi-ho Park, Jay Hyoun Kwon, Jisun Lee, Tae Soo Kim and Young Yoon Jang
Appl. Sci. 2020, 10(13), 4667; https://doi.org/10.3390/app10134667 - 06 Jul 2020
Cited by 27 | Viewed by 4358
Abstract
The agriculture sector is currently facing the problems of aging and decreasing skilled labor, meaning that the future direction of agriculture will be a transition to automation and mechanization that can maximize efficiency and decrease costs. Moreover, interest in the development of autonomous [...] Read more.
The agriculture sector is currently facing the problems of aging and decreasing skilled labor, meaning that the future direction of agriculture will be a transition to automation and mechanization that can maximize efficiency and decrease costs. Moreover, interest in the development of autonomous agricultural vehicles is increasing due to advances in sensor technology and information and communication technology (ICT). Therefore, an autonomous driving control algorithm using a low-cost global navigation satellite system (GNSS)-real-time kinematic (RTK) module and a low-cost motion sensor module was developed to commercialize an autonomous driving system for a crawler-type agricultural vehicle. Moreover, an autonomous driving control algorithm, including the GNSS-RTK/motion sensor integration algorithm and the path-tracking control algorithm, was proposed. Then, the performance of the proposed algorithm was evaluated based on three trajectories. The Root Mean Square Errors (RMSEs) of the path-following of each trajectory are calculated to be 9, 7, and 7 cm, respectively, and the maximum error is smaller than 30 cm. Thus, it is expected that the proposed algorithm could be used to conduct autonomous driving with about a 10 cm-level of accuracy. Full article
(This article belongs to the Special Issue Remote Sensing and Geoscience Information Systems in Applied Sciences)
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15 pages, 4812 KiB  
Article
Low-Speed Bearing Fault Diagnosis Based on Permutation and Spectral Entropy Measures
by Diego Sandoval, Urko Leturiondo, Francesc Pozo and Yolanda Vidal
Appl. Sci. 2020, 10(13), 4666; https://doi.org/10.3390/app10134666 - 06 Jul 2020
Cited by 12 | Viewed by 3613
Abstract
Despite its influence on wind energy service life, condition-based maintenance is still challenging to perform. For offshore wind farms, which are placed in harsh and remote environments, damage detection is critically important to schedule maintenance tasks and reduce operation and maintenance costs. One [...] Read more.
Despite its influence on wind energy service life, condition-based maintenance is still challenging to perform. For offshore wind farms, which are placed in harsh and remote environments, damage detection is critically important to schedule maintenance tasks and reduce operation and maintenance costs. One critical component to be monitored on a wind turbine is the pitch bearing, which can operate at low speed and high loads. Classical methods and features for general purpose bearings cannot be applied effectively to wind turbine pitch bearings owing to their specific operating conditions (high loads and non-constant very low speed with changing direction). Thus, damage detection of wind turbine pitch bearings is currently a challenge. In this study, entropy indicators are proposed as an alternative to classical bearing analysis. For this purpose, spectral and permutation entropy are combined to analyze a raw vibration signal from a low-speed bearing in several scenarios. The results indicate that entropy values change according to different types of damage on bearings, and the sensitivity of the entropy types differs among them. The study offers some important insights into the use of entropy indicators for feature extraction and it lays the foundation for future bearing prognosis methods. Full article
(This article belongs to the Special Issue Bearing Fault Detection and Diagnosis)
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18 pages, 7305 KiB  
Article
Application of Hyperspectral Imaging for Assessment of Tomato Leaf Water Status in Plant Factories
by Tiejun Zhao, Akimasa Nakano, Yasunaga Iwaski and Hiroki Umeda
Appl. Sci. 2020, 10(13), 4665; https://doi.org/10.3390/app10134665 - 06 Jul 2020
Cited by 15 | Viewed by 3019
Abstract
Irrigation management continues to be an important issue for tomato cultivation, especially in plant factories. Accurate and timely assessment of tomato leaf water status is a key factor in enabling appropriate irrigation, which can save nutrition solution and labor. In recent decades, hyperspectral [...] Read more.
Irrigation management continues to be an important issue for tomato cultivation, especially in plant factories. Accurate and timely assessment of tomato leaf water status is a key factor in enabling appropriate irrigation, which can save nutrition solution and labor. In recent decades, hyperspectral imaging has been widely used as a nondestructive measurement method in agriculture to obtain plant biological information. The objective of this research was to establish an approach to obtain the tomato leaf water status—specifically, the relative water content (WC) and equivalent water thickness (MC)—for five different tomato cultivars in real time by using hyperspectral imaging. The normalized difference vegetation index (NDVI) and two-band vegetation index (TBI) analyses were performed on the tomato leaf raw relative reflection (RAW), the inversion-logarithm relative reflection (LOG), and the first derivative of relative reflection (DIFF) from wavelengths of 900 nm to 1700 nm. The best regression model for WC assessment was obtained by TBI regression using DIFF at wavelengths of 1410 nm and 1520 nm, and the best regression model for MC assessment was obtained by NDVI regression using RAW at wavelengths of 1300 nm and 1310 nm. Higher model performance was obtained with MC assessment than with WC assessment. The results will help improve our understanding of the relationship between hyperspectral reflectance and leaf water status. Full article
(This article belongs to the Special Issue Application of Hyperspectral Imaging for Nondestructive Measurement)
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24 pages, 4764 KiB  
Article
Visual Workflow Process Modeling and Simulation Approach Based on Non-Functional Properties of Resources
by Kawtar Ougaabal, Gregory Zacharewicz, Yves Ducq and Said Tazi
Appl. Sci. 2020, 10(13), 4664; https://doi.org/10.3390/app10134664 - 06 Jul 2020
Cited by 10 | Viewed by 3315
Abstract
With the emergence of big data and cloud technologies, companies now evolve in complex IT environments. This situation requires good practices for data process automation to be adopted to ensure system interoperability. Visual computing helps companies to describe and organize the ways in [...] Read more.
With the emergence of big data and cloud technologies, companies now evolve in complex IT environments. This situation requires good practices for data process automation to be adopted to ensure system interoperability. Visual computing helps companies to describe and organize the ways in which information systems, devices, and people must interact. It incorporates a number of fields including modeling and simulation (M&S). This paper focused on M&S of data workflow processes that are key steps to bridging the gap between business views and goals on the one side, and operational implementations on the other side. Simulation adds a dynamic view to static modeling; it increases understanding of the behavior of process mechanisms and the identification of weak areas in data flow. Several research projects have been focused on control flow and data flow, but less attention has been paid to resource characteristics. This work is based on the MDSEA approach and the eBPMN language, and proposes an approach that aims to distinguish the types of resources carrying out process tasks. Furthermore, it introduces a new composite resource made from the relationship between a user (human resource) and a task form (IT resource). Moreover, it proposes a resource aggregation based on process performance combination in order to run and display a global performance measurement of a process path. Full article
(This article belongs to the Special Issue New Industry 4.0 Advances in Industrial IoT and Visual Computing for Manufacturing Processes: Volume II)
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5 pages, 464 KiB  
Editorial
Oral Health and Related Factors Associated with General Health and Quality of Life
by Gaetano Isola
Appl. Sci. 2020, 10(13), 4663; https://doi.org/10.3390/app10134663 - 06 Jul 2020
Cited by 3 | Viewed by 2254
Abstract
Oral well-being is an integral part of individual general health. The mouth and teeth are, in fact, part of our body, increasingly characterizing personal identity. Oral diseases are a public health problem that has a growing prevalence. Oral pathologies can occur in childhood, [...] Read more.
Oral well-being is an integral part of individual general health. The mouth and teeth are, in fact, part of our body, increasingly characterizing personal identity. Oral diseases are a public health problem that has a growing prevalence. Oral pathologies can occur in childhood, and as they have a chronic and progressive course, if not properly treated, they can affect the relational, psychological, and social skills of an individual. The population most affected are those with a low socio-economic level, so much so that the presence of diseases of the oral cavity is considered a marker of social disadvantage. In this regard, much effort is needed from scientists, and their applied sciences, in order to give the knowledge required for public health personal to take note of the seriousness of the situation and to start changing the way we deal with the problem. Full article
(This article belongs to the Special Issue Oral Health and Environmentally Related Factors Associated with General Health and Quality of Life)
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19 pages, 4239 KiB  
Article
Design of a Predictive RBF Compensation Fuzzy PID Controller for 3D Laser Scanning System
by Minghui Zhao, Xiaobin Xu, Hao Yang and Zhijie Pan
Appl. Sci. 2020, 10(13), 4662; https://doi.org/10.3390/app10134662 - 06 Jul 2020
Cited by 9 | Viewed by 2414
Abstract
A new proportional integral derivative (PID) control method is proposed for the 3D laser scanning system converted from 2D Lidar with a pitching motion device. It combines the advantages of a fuzzy algorithm, a radial basis function (RBF) neural network and a predictive [...] Read more.
A new proportional integral derivative (PID) control method is proposed for the 3D laser scanning system converted from 2D Lidar with a pitching motion device. It combines the advantages of a fuzzy algorithm, a radial basis function (RBF) neural network and a predictive algorithm to control the pitching motion of 2D Lidar quickly and accurately. The proposed method adopts the RBF neural network and feedback compensation to eliminate the unknown nonlinear part in the Lidar pitching motion, adaptively adjusting the PID parameter by a fuzzy algorithm. Then, the predictive control algorithm is adopted to optimize the overall controller output in real time. Finally, the simulation results show that the step response time of the Lidar pitching motion system using the control method is reduced from 15.298 s to 1.957 s with a steady-state error of 0.07°. Meanwhile, the system still has favorable response performance for the sinusoidal and step inputs under model mismatch and large disturbance. Therefore, the control method proposed above can improve the system performance and control the pitching motion of the 2D Lidar effectively. Full article
(This article belongs to the Section Mechanical Engineering)
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9 pages, 4733 KiB  
Article
Tunable Terahertz Metamaterial Using an Electric Split-Ring Resonator with Polarization-Sensitive Characteristic
by Tao Xu and Yu-Sheng Lin
Appl. Sci. 2020, 10(13), 4660; https://doi.org/10.3390/app10134660 - 06 Jul 2020
Cited by 16 | Viewed by 2983
Abstract
We present a tunable terahertz (THz) metamaterial using an electric split-ring resonator (eSRR), which exhibits polarization-sensitive characteristics. The proposed eSRR is composed of double symmetrical semicircles and two central metal bars. By changing the lengths of two metal bars, the electromagnetic responses can [...] Read more.
We present a tunable terahertz (THz) metamaterial using an electric split-ring resonator (eSRR), which exhibits polarization-sensitive characteristics. The proposed eSRR is composed of double symmetrical semicircles and two central metal bars. By changing the lengths of two metal bars, the electromagnetic responses can be tuned and switched between dual-band and triple-band resonances in transverse magnetic (TM) mode. Furthermore, by moving the bottom metal bar to change the gap between the two metal bars, the first resonance is stable at 0.39 THz, and the second resonance is gradually blue-shifted from 0.83 to 1.33 THz. The tuning range is 0.50 THz. This means that the free spectrum ranges (FSR) could be broadened by 0.50 THz. This proposed device exhibits a dual-/triple-band switch, tunable filter, tunable FSR and polarization-dependent characteristics. It provides an effective approach to perform tunable polarizer, sensor, switch, filter and other optoelectronics in THz-wave applications. Full article
(This article belongs to the Special Issue Advances of THz Spectroscopy)
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15 pages, 2664 KiB  
Article
Application of Multiple Unipolar Axial Eddy Current Brakes for Lightweight Electric Vehicle Braking
by Mufti Reza Aulia Putra, Muhammad Nizam, Dominicus Danardono Dwi Prija Tjahjana, Muhammad Aziz and Aditya Rio Prabowo
Appl. Sci. 2020, 10(13), 4659; https://doi.org/10.3390/app10134659 - 06 Jul 2020
Cited by 15 | Viewed by 12171
Abstract
The braking system in a vehicle has the main role of slowing down the speed or stopping the moving vehicle. Compared to mechanical braking, which utilizes friction, non-contact braking has several advantages, including longer lifetime and less maintenance. One form of non-contact braking [...] Read more.
The braking system in a vehicle has the main role of slowing down the speed or stopping the moving vehicle. Compared to mechanical braking, which utilizes friction, non-contact braking has several advantages, including longer lifetime and less maintenance. One form of non-contact braking systems is the eddy current brake (ECB), an electric braking system that employs eddy currents to operate. This research focuses on the impact of magnetic field sources used in the ECB. In addition, the number of magnetic field sources is also observed. In order to achieve an ECB design that can be easily applied in any types of vehicles, including motorcycles and compact cars, a compact ECB design with an excellent braking torque is required. In this study, a compact design of the ECB is obtained by distributing the required braking torque from the disc brake into multiple electromagnets. Finite element method-based modeling has been performed to study ECB parameters, including the number of coil winding, the number of electromagnets, and the electric current. The results of this study show that the developed compact ECB could produce 93.66% of the torque required for braking. Full article
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13 pages, 2122 KiB  
Article
Interferometric Study of the Heat Transfer Phenomena Induced by Rapid Heating of Nickel Sheet
by Hyeon-Seok Seo, In-Ju Hwang and Youn-Jea Kim
Appl. Sci. 2020, 10(13), 4658; https://doi.org/10.3390/app10134658 - 06 Jul 2020
Viewed by 1912
Abstract
Visualization of the heat transfer phenomena induced by the rapid heating of nickel sheets was carried out using a Mach–Zehnder interferometer (MZI) and a high-speed camera. This phenomenon may be an important factor in heat transfer phenomena when the working fluids reach the [...] Read more.
Visualization of the heat transfer phenomena induced by the rapid heating of nickel sheets was carried out using a Mach–Zehnder interferometer (MZI) and a high-speed camera. This phenomenon may be an important factor in heat transfer phenomena when the working fluids reach the thermodynamic critical point. The effect of heat transfer on the heating conditions of a nickel sheet was quantified by finite fringe analysis. The results show that isotherms near the heating surface with rapid heating are generated, and the induced isotherms are moved upward with similar patterns for different heating conditions. In addition, it is confirmed that the local Nusselt number decreases to the relationship of a secondary function if the thickness of the metal specimen is very thin and the time to reach the highest temperature is very short. Moreover, it decreased according to the increase of heating energy because the heat transfer mainly occurred by conduction and radiation rather than by convection, because the expansive force and compressive force between the fluid layers on the wall increased due to an increase in the heating energy in the beginning. Full article
(This article belongs to the Section Mechanical Engineering)
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13 pages, 8032 KiB  
Article
Nanosecond Laser Ablation of Ti–6Al–4V under Different Temperature
by Jiantao Zhao, Zhenge Zhu, Yacheng Xu, Xueyong Song, Yufan Wang, Hao Peng, Ying Wang, Jinrong Zuo, Xuedao Shu and Anmin Yin
Appl. Sci. 2020, 10(13), 4657; https://doi.org/10.3390/app10134657 - 06 Jul 2020
Cited by 7 | Viewed by 2280
Abstract
Multi-pulse nanosecond laser ablation of Ti–6Al–4V is a complex process. In this study, the effect of substrate temperature on the nanosecond laser ablation of Ti–6Al–4V was investigated. Morphology, diameter and depth of ablation craters were observed; ablation efficiency ω (μm3/mJ) was [...] Read more.
Multi-pulse nanosecond laser ablation of Ti–6Al–4V is a complex process. In this study, the effect of substrate temperature on the nanosecond laser ablation of Ti–6Al–4V was investigated. Morphology, diameter and depth of ablation craters were observed; ablation efficiency ω (μm3/mJ) was proposed to analyzes the ablation process. The results showed that, with the increasing of substrate temperature, the ablation craters’ diameter increased and depth decreased, while ω initially increased, but then decreased rapidly. Furthermore, with increasing pulse number, the depth of ablation crater increased linearly, while the growth of the diameter gradually slowed down and tended to be stable after the 16th irradiation. The above changes were different in details at different substrate temperatures. Full article
(This article belongs to the Special Issue Laser Material Manufacturing)
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