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Appl. Sci., Volume 9, Issue 17 (September-1 2019)

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Cover Story (view full-size image) This paper describes an experimental test campaign while using an unmanned aerial vehicle (UAV) and [...] Read more.
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Open AccessArticle
Investigating Different Grounds Effects on Shock Wave Propagation Resulting from Near-Ground Explosion
Appl. Sci. 2019, 9(17), 3639; https://doi.org/10.3390/app9173639 - 03 Sep 2019
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Abstract
A massive explosion of a liquid-propellant rocket in the course of an accident can lead to a truly catastrophic event, which would threaten the safety of personnel and facilities around the launch site. In order to study the propagation of near-ground shock wave [...] Read more.
A massive explosion of a liquid-propellant rocket in the course of an accident can lead to a truly catastrophic event, which would threaten the safety of personnel and facilities around the launch site. In order to study the propagation of near-ground shock wave and quantify the enhancement effect on the overpressure, models with different grounds have been established based on an explicit nonlinear dynamic ANSYS/LS-DYNA 970 program. Results show that the existence of the ground will change the propagation law and conform to the reflection law of the shock wave. Rigid ground absorbs no energy and reflects all of it, while concrete ground absorbs and reflects some of the energy, respectively. Ground may influence the pressure-time curve of the shock wave. When the gauge is close to the explosive, the pressure-time curve presents a bimodal feature, while when the gauge reaches a certain distance to the explosive, it presents a single-peak feature. For gauges at different heights, different grounds may have different effects on the peak overpressure. For gauges of height not greater than 4 m, the impact on the shock wave is obvious when the radial to the explosive is small. On the contrary, as for the gauges of height greater than 4 m, the impact on the shock wave is obvious when the radial to the explosive is big. Ground has the enhancement effect on peak overpressure, but different grounds have different ways. For rigid ground, the peak overpressure factor is about 2. However, for the concrete and soil ground, peak overpressure factor is from 1.43 to 2.1. Full article
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Open AccessArticle
Virtual Mechanical Product Disassembly Sequences Based on Disassembly Order Graphs and Time Measurement Units
Appl. Sci. 2019, 9(17), 3638; https://doi.org/10.3390/app9173638 - 03 Sep 2019
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Abstract
Recently, the approach that defines the total life cycle assessment (LCA) and the end of life (EoL) in the early design phases is becoming even more promising. Literature evidences many advantages in terms of the saving of costs and time and in the [...] Read more.
Recently, the approach that defines the total life cycle assessment (LCA) and the end of life (EoL) in the early design phases is becoming even more promising. Literature evidences many advantages in terms of the saving of costs and time and in the fluent organization of the whole design process. Design for disassembly (DfD) offers the possibility of reducing the time and cost of disassembling a product and accounts for the reusing of parts and of the dismantling of parts, joints, and materials. The sequence of disassembly is the ordered way to extract parts from an assembly and is a focal item in DfD because it can deeply influence times and operations. In this paper, some disassembly sequences are evaluated, and among them, two methods for defining an optimal sequence are provided and tested on a case study of a mechanical assembly. A further sequence of disassembly is provided by the authors based on experience and personal knowledge. All three are analyzed by the disassembly order graph (DOG) approach and compared. The operations evaluated have been converted in time using time measurement units (TMUs). As result, the best sequence has been highlighted in order to define a structured and efficient disassembly. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle
Study on an Optimal Strut-And-Tie Model for Concrete Deep Beams
Appl. Sci. 2019, 9(17), 3637; https://doi.org/10.3390/app9173637 - 03 Sep 2019
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Abstract
The optimal strut-and-tie models (STMs) of two typical irregular concrete deep beams were constructed using evolutionary structural optimization and compared with those of previous studies. The reinforced concrete deep beam specimens were cast according to the reinforcement designs guided by different STMs. Eight [...] Read more.
The optimal strut-and-tie models (STMs) of two typical irregular concrete deep beams were constructed using evolutionary structural optimization and compared with those of previous studies. The reinforced concrete deep beam specimens were cast according to the reinforcement designs guided by different STMs. Eight irregular concrete deep beam specimens were experimentally investigated under stepped loading, and the differences in the amount of steel used, the load-carrying capacity, and the failure pattern of the different specimens were analyzed. The results show that the optimal STMs proposed in this study have significant advantages in terms of cost-effectiveness and can simultaneously ensure the load-carrying capacity, delay the crack propagation of irregular concrete deep beams, and reduce the amount of steel used in structural members. Therefore, they have an important engineering application value for the reinforcement design of irregular concrete deep beams. Full article
(This article belongs to the Section Civil Engineering)
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Open AccessArticle
Monitoring of Evolving Laser Induced Periodic Surface Structures
Appl. Sci. 2019, 9(17), 3636; https://doi.org/10.3390/app9173636 - 03 Sep 2019
Viewed by 215
Abstract
Laser induced periodic surface structures (LIPSS) are generated on titanium and silicon nitride surfaces by multiple femtosecond laser pulses. An optical imaging system is used to observe the backscattered light during the patterning process. A characteristic fringe pattern in the backscattered light is [...] Read more.
Laser induced periodic surface structures (LIPSS) are generated on titanium and silicon nitride surfaces by multiple femtosecond laser pulses. An optical imaging system is used to observe the backscattered light during the patterning process. A characteristic fringe pattern in the backscattered light is observed and evidences the surface modification. Experiments are complemented by finite difference time domain numerical simulations which clearly show that the periodic surface modulation leads to characteristic modulations in the coherently scattered light field. It is proposed that these characteristic fringe pattern can be used as a very fast and low-cost monitor of LIPSS formation formation during the manufacturing process. Full article
(This article belongs to the Section Nanotechnology and Applied Nanosciences)
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Open AccessArticle
Using Earthworms Eisenia fetida (Sav.) for Utilization of Expansive Littoral Plants Biomass
Appl. Sci. 2019, 9(17), 3635; https://doi.org/10.3390/app9173635 - 03 Sep 2019
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Abstract
This paper presents the results of the process of vermicomposting waste biomass of littoral plants Typha latifolia, Iris pseudacorus, Ceratophyllum demersum in vermireactors, with the use of earthworms Eisenia fetida. It was observed that E. fetida may be used for [...] Read more.
This paper presents the results of the process of vermicomposting waste biomass of littoral plants Typha latifolia, Iris pseudacorus, Ceratophyllum demersum in vermireactors, with the use of earthworms Eisenia fetida. It was observed that E. fetida may be used for rapid utilization of pure I. pseudacorus and C. demersum waste, but using the technology presented in this paper and the assumed observation time, it was not possible to recycle T. latifolia waste. Vermicomposts obtained were characterized by higher N, P, K, Ca, and Mg content compared to the initial plant biomass. The content of Cu, Mn, Zn, Cd, and Pb in vermicomposts did not exclude their application as a fertilizer. During vermicomposting of all littoral plants, the earthworm population was maintained up to day 70 of the experiment, with a slight decrease in their number (on average by 6%, p > 0.05), and since day 35, a significant loss in earthworm biomass was observed. The greatest loss of mean sum of biomass (49%, p < 0.05) was noted in a group of earthworms utilizing T. latifolia. The earthworms reproduced, with the greatest mean number (and the sum of biomass) of cocoons observed in a group of earthworms processing C. demersum. These values were greater by 32% and 38% respectively (p < 0.05), for the aforementioned characteristics of cocoons produced in the remaining experimental groups. Full article
(This article belongs to the Section Environmental and Sustainable Science and Technology)
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Open AccessArticle
The Design and Optimization of an Interior, Permanent Magnet Synchronous Machine Applied in an Electric Traction Vehicle Requiring a Low Torque Ripple
Appl. Sci. 2019, 9(17), 3634; https://doi.org/10.3390/app9173634 - 03 Sep 2019
Viewed by 191
Abstract
An internal permanent magnet synchronous machine (IPMSM) was designed for heavy-load traction vehicles applied in port transportation. Based on finite element analysis (FEA), the rotor iron core topology was optimized with the most attention paid to cogging torque and torque ripple. The influences [...] Read more.
An internal permanent magnet synchronous machine (IPMSM) was designed for heavy-load traction vehicles applied in port transportation. Based on finite element analysis (FEA), the rotor iron core topology was optimized with the most attention paid to cogging torque and torque ripple. The influences of the iron core on the air-gap magnetic flux density, the back electro-motive-force harmonic, the cogging torque and the torque ripple were investigated. The design scheme of minimizing cogging torque and output torque ripple was obtained. Focused on the relationship between the rotor parameters and the torque ripple, the relative sensitivity factor was proposed and analyzed. Finally, the torque ripple was reduced from 14.4% to 3.84%, after further optimization of the rotor design parameters. The reliability and stability of the IPMSM were also covered. Additionally, the experimental study of the prototype was carried out to verify the FEA results. Full article
(This article belongs to the Section Electrical, Electronics and Communications Engineering)
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Open AccessArticle
A 3D Simulation of Single-Channel High-Temperature Polymer Exchange Membrane Fuel Cell Performances
Appl. Sci. 2019, 9(17), 3633; https://doi.org/10.3390/app9173633 - 03 Sep 2019
Viewed by 221
Abstract
The fuel cell is an electrochemical energy converter that directly converts the chemical energy of the fuel into electrical current and heat. The fuel cell has been able to identify itself as a source of clean energy over the past few decades. In [...] Read more.
The fuel cell is an electrochemical energy converter that directly converts the chemical energy of the fuel into electrical current and heat. The fuel cell has been able to identify itself as a source of clean energy over the past few decades. In order to achieve the durability and stability of fuel cells, many parameters should be considered and evaluated Therefore, in this study, a single-channel high-temperature polymer exchange membrane fuel cell (HT-PEMFC) has been numerically simulated in three-dimensional, isothermal and single-phase approach. The distribution of the hydrogen and oxygen concentrations, as well as water in the anode and cathode, are shown; then the effect of different parameters of the operating pressure, the gas diffusion layer porosity, the electrical conductivity of the gas diffusion layer, the ionic conductivity of the membrane and the membrane thickness are investigated and evaluated on the fuel cell performance. The results showed that the pressure drop in the cathode channel was higher than the anode channel, so that the pressure drop in the cathode channel was higher than 9 bars but, in the anode channel was equal to 2 bars. By examining the species concentration, it was observed that their concentration at the entrance was higher and at the output was reduced due to participation in the reaction and consumption. Also, with increasing the operating pressure, the electrical conductivity of the gas diffusion layer and ionic conduction of the membrane, the performance of the fuel cell is improved. Full article
(This article belongs to the Section Materials)
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Open AccessArticle
Simultaneous Verification of Multi-Ultrasonic-Flowmeters in Tandem Arrangement for Natural Gas
Appl. Sci. 2019, 9(17), 3632; https://doi.org/10.3390/app9173632 - 03 Sep 2019
Viewed by 173
Abstract
A combined experiment and numerical analysis was performed to determine whether the flow field has a significant impact on the simultaneous verification of multi-ultrasonic flowmeters (UFMs) in tandem arrangement (SVUFMST) and whether the SVUFMST is practical for flowrate measurement of pressurized natural gas. [...] Read more.
A combined experiment and numerical analysis was performed to determine whether the flow field has a significant impact on the simultaneous verification of multi-ultrasonic flowmeters (UFMs) in tandem arrangement (SVUFMST) and whether the SVUFMST is practical for flowrate measurement of pressurized natural gas. In practical testing, SVUFMST can highly improve the efficiency of UFMs’ calibration. Two types of UFMs of different nominal diameter were studied: DN250 and DN150. When it comes to DN250, data obtained from the actual-flow experiments were first used to verify the simulated results for n ≤ 3 (number of tested UFMs) and then the verified numerical method was extended to simulate the internal flow of four and five tested UFMs. Comparison analysis shows that all the numerical results agree remarkably well with the available experimental data and more than two tested UFMs can induce an overall shift in the EQ curve (relative measurement error E plotted as a function of flowrate Q). For the slight difference among the tested UFMs, the practicability of the SVUFMST at n ≤ 4 (DN250) and n ≤ 3 (DN150) are thereby proved, whereas the striking difference in E (~1.0%) between the most downstream UFM and the other UFMs for n = 5 (DN250), associated with the outstanding collapse onto the velocity profile along the acoustic paths, results in the invalidation of the SVUFMST. Full article
(This article belongs to the Section Applied Industrial Technologies)
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Open AccessArticle
Major Depressive Disorder and Oxidative Stress: In Silico Investigation of Fluoxetine Activity against ROS
Appl. Sci. 2019, 9(17), 3631; https://doi.org/10.3390/app9173631 - 03 Sep 2019
Viewed by 220
Abstract
Major depressive disorder is a psychiatric disease having approximately a 20% lifetime prevalence in adults in the United States (U.S.), as reported by Hasin et al. in JAMA Psichiatry 2018 75, 336–346. Symptoms include low mood, anhedonia, decreased energy, alteration in appetite [...] Read more.
Major depressive disorder is a psychiatric disease having approximately a 20% lifetime prevalence in adults in the United States (U.S.), as reported by Hasin et al. in JAMA Psichiatry 2018 75, 336–346. Symptoms include low mood, anhedonia, decreased energy, alteration in appetite and weight, irritability, sleep disturbances, and cognitive deficits. Comorbidity is frequent, and patients show decreased social functioning and a high mortality rate. Environmental and genetic factors favor the development of depression, but the mechanisms by which stress negatively impacts on the brain are still not fully understood. Several recent works, mainly published during the last five years, aim at investigating the correlation between treatment with fluoxetine, a non-tricyclic antidepressant drug, and the amelioration of oxidative stress. In this work, the antioxidant activity of fluoxetine was investigated using a computational protocol based on the density functional theory approach. Particularly, the scavenging of five radicals (HO, HOO, CH3OO, CH2=CHOO, and CH3O) was considered, focusing on hydrogen atom transfer (HAT) and radical adduct formation (RAF) mechanisms. Thermodynamic as well as kinetic aspects are discussed, and, for completeness, two metabolites of fluoxetine and serotonin, whose extracellular concentration is enhanced by fluoxetine, are included in our analysis. Indeed, fluoxetine may act as a radical scavenger, and exhibits selectivity for HO and CH3O, but is inefficient toward peroxyl radicals. In contrast, the radical scavenging efficiency of serotonin, which has been demonstrated in vitro, is significant, and this supports the idea of an indirect antioxidant efficiency of fluoxetine. Full article
(This article belongs to the Special Issue The Application of Quantum Mechanics in Reactivity of Molecules)
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Open AccessArticle
Thermal Analysis and Stability of Boron/Potassium Nitrate Pyrotechnic Composition at 180 °C
Appl. Sci. 2019, 9(17), 3630; https://doi.org/10.3390/app9173630 - 03 Sep 2019
Viewed by 189
Abstract
Aerospace missions require that pyrotechnic compositions are able to withstand 180 °C. Therefore, this paper studies the thermal stability and output performance of boron/potassium nitrate (abbreviated BPN) used in pyrotechnic devices. Firstly, differential scanning calorimetry (DSC) and thermogravimetric (TG) tests are used to [...] Read more.
Aerospace missions require that pyrotechnic compositions are able to withstand 180 °C. Therefore, this paper studies the thermal stability and output performance of boron/potassium nitrate (abbreviated BPN) used in pyrotechnic devices. Firstly, differential scanning calorimetry (DSC) and thermogravimetric (TG) tests are used to analyze the thermal reaction process of KNO3, boron, and BPN to qualitatively judge their thermal stability. Then, apparent morphology analysis, component analysis, and the p-t curve test, which is the closed bomb test to measure the output power of the pyrotechnic composition, are carried out with BPN samples before and after the high-temperature test to verify BPN stability at 180 °C. The weight change of boron powder caused by chemical reactions occurs above 500 °C. When the temperature is lower than the peak exothermic temperature of decomposition, no obvious chemical reaction occurs with KNO3, and only physical changes (crystal transformation and melting) occur. Combined with a verification test at 180 °C for two days, it is concluded that boron and KNO3 components are stable at 180 °C. With an increase in boron content, the thermal stability of BPN is improved, with the best performance achieved when the ratio is 25:75 (B:KNO3). BPN samples without binder have the best thermal stability. In a test at 180 °C for five days, the binder affects the weight loss and p-t curve of BPN, and BPN with fluororubber binder is better than BPN with unsaturated polyester binder. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle
The Prevention and Control Mechanism of Rockburst Hazards and Its Application in the Construction of a Deeply Buried Tunnel
Appl. Sci. 2019, 9(17), 3629; https://doi.org/10.3390/app9173629 - 03 Sep 2019
Viewed by 224
Abstract
Rockburst hazards induced by high geostress are particularly prominent during the construction of underground engineering. Prevention and control of rockburst is still a global challenge in the field of geotechnical engineering, which is of great significance. Based on the tunnel group of the [...] Read more.
Rockburst hazards induced by high geostress are particularly prominent during the construction of underground engineering. Prevention and control of rockburst is still a global challenge in the field of geotechnical engineering, which is of great significance. Based on the tunnel group of the Jinping II hydropower station of China, this paper analyzed the mechanical principle of support in the process of construction, and discussed in detail the active release and passive support by numerical simulation and field application. The results show that as two active measures, stress relieve holes and advanced stress relief blasting can release the energy of the microseismic source and transfer the high stress to the deeper surrounding rock, make the surface rock wall with a relatively low stress act as a protective barrier. Their stress release rate is about 12% and 33% in this project, respectively. In term of passive measure, the combined rapid support, which is mainly composed of water swelling anchor and nano-admixture shotcrete, is also an effective way to prevent and control the rockburst under high geostress. Full article
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Open AccessArticle
The Dynamic Characteristic of a Faulted Rotor System with Multi-Objective Optimization Designed SFD
Appl. Sci. 2019, 9(17), 3628; https://doi.org/10.3390/app9173628 - 03 Sep 2019
Viewed by 228
Abstract
As an important part of the turbomachinery, the rotor–bearing system has been upgraded to provide a high rotating speed in order to meet the demand of high power production. With increasing demand for stability, the squeeze film damper (SFD) has been widely used [...] Read more.
As an important part of the turbomachinery, the rotor–bearing system has been upgraded to provide a high rotating speed in order to meet the demand of high power production. With increasing demand for stability, the squeeze film damper (SFD) has been widely used in industrial machinery because it can reduce the vibration amplitude and suppress the external force. Usually, it shows inadaptability under the different working conditions where the SFD parameters didn’t change appropriately. Therefore, the reasonable choice of operational parameters of SFD is the key solution that can provide viscous damping effectively and restrain the nonlinear vibration generated by faults. In this paper, the mathematical model of a rotor-ball bearing-SFD system considering the misalignment fault and misalignment-rubbing coupling fault is built first. Then the dynamic characteristics under typical working conditions (ω = 1000 rad/s) of the faulted rotor are discussed. The vibration attenuation effects of the SFD parameters selected by using the multi-objective optimization method on the dynamic responses are analyzed. The results show that when the rotor system operates under different states, the value and the sensitivity of optimization parameters are altered. With no fault, the amplitude of fundamental frequency decrease 23%. With the misalignment fault, the amplitude of the fundamental frequency decreases by 43.4%, the amplitude of 2× fundamental frequency decreases by 27.5%, and the amplitude of 3× fundamental frequency decreases by 66.7%. With the misalignment-rubbing coupling fault, the amplitude of fundamental frequency reduces by 7.4%, the amplitude of 2× fundamental frequency drops by 51.5%, and the amplitude of 3× fundamental frequency drops by 16.8%. Overall, the feasibility of the optimization method of the variable-structured SFD operational parameters for the faulted rotor system is verified. These parametric analyses are very helpful in the development of a high-speed rotor system and provide a theoretical reference for the vibration control and optimal design of rotating machinery. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessReview
Accumulative Roll Bonding—A Review
Appl. Sci. 2019, 9(17), 3627; https://doi.org/10.3390/app9173627 - 03 Sep 2019
Viewed by 269
Abstract
Different manufacturing processes can be utilized to fabricate light-weight high-strength materials for their applications in a wide spectrum of industries such as aerospace, automotive and biomedical sectors among which accumulative roll bonding (ARB) is a promising severe plastic deformation (SPD) method capable of [...] Read more.
Different manufacturing processes can be utilized to fabricate light-weight high-strength materials for their applications in a wide spectrum of industries such as aerospace, automotive and biomedical sectors among which accumulative roll bonding (ARB) is a promising severe plastic deformation (SPD) method capable of creating ultrafine grains (UFG) in the final microstructure. The present review discusses recent advancements in the ARB process starting with the ARB basics, intricacies of the underlying mechanisms and physics, different materials, surface and rolling parameters, and finally its key effects on different properties such as strength, ductility, fatigue, toughness, superplasticity, tribology and thermal characteristics. Moreover, results of recent computational investigations have also been briefed towards the end. It is believed that ARB processing is an emerging area with tremendous opportunities in the industrial sector and ample potential in tailoring microstructures for high-performance materials. Full article
(This article belongs to the Section Materials)
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Open AccessCommunication
Selected Scattering on Quasi-Ordered Hexagonal Close-Packed Al Nanodents for Tunable Output of White LEDs
Appl. Sci. 2019, 9(17), 3626; https://doi.org/10.3390/app9173626 - 03 Sep 2019
Viewed by 198
Abstract
Quasi-ordered hexagonal close-packed Al nanodents, with depths of 30 nm and top-diameters of 300 nm prepared by electrochemical anodizing, are used to manage the output spectrum of white Light Emitting Diodes (LEDs). Significant short wavelength light, with a peak of 450 nm, displays [...] Read more.
Quasi-ordered hexagonal close-packed Al nanodents, with depths of 30 nm and top-diameters of 300 nm prepared by electrochemical anodizing, are used to manage the output spectrum of white Light Emitting Diodes (LEDs). Significant short wavelength light, with a peak of 450 nm, displays significant scattering enhancements on these Al nanodents with the increment of the angle of the incidence, while long wavelength light, with a peak of 550 nm, shows weaker scattering on Al nanodents with the increment of theincidence angle. Near-field and far-field simulations reveal the effect of light coupling in the holes of Al nanodents on the selected scattering. This work could provide a striking new way to make use of cheap white LEDs. Full article
(This article belongs to the Section Nanotechnology and Applied Nanosciences)
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Open AccessArticle
Investigation of the Fatigue Behaviour of a Ballastless Slab Track–Bridge Structural System under Train Load
Appl. Sci. 2019, 9(17), 3625; https://doi.org/10.3390/app9173625 - 03 Sep 2019
Viewed by 202
Abstract
To probe into the time-dependent behaviour of the ballastless track–bridge structural system under train load, based on the import of the static and fatigue damage constitutive model of materials to simulate damage deterioration of the structural system and interface cohesive zone model to [...] Read more.
To probe into the time-dependent behaviour of the ballastless track–bridge structural system under train load, based on the import of the static and fatigue damage constitutive model of materials to simulate damage deterioration of the structural system and interface cohesive zone model to the interface layer, a three-dimensional nonlinear finite element model of the China Railway Track System Type II (CRTS II) ballastless track–bridge structural system was established using the equivalent static method. Then, using this model, we developed the numerical simulation analysis of the influence law of material damage deterioration on structural system performance under train load and revealed the fatigue evolution of the structural system. The results show that the beam remains in compressed status for the whole process, the track is in compression in the midspan and in tension at the beam end, and the tensile stress is larger near the shear groove under the double-track static load. Under the fatigue load, stiffness degradation of the structural system is not obvious, and integral rigidity of the structural system is dependent on the rigidity of the beam. Strength reduction of the materials caused stress redistribution of the structural system and had a larger effect on the stress of each layer of track structure than on the stress on the beam. The fatigue degradation of the cement-emulsified asphalt (CA) mortar layer material has a significant impact on the structural system, which directly affects structural layer stress variation with the fatigue loading cycle. Full article
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Open AccessArticle
Congestion Evaluation of Pedestrians in Metro Stations Based on Normal-Cloud Theory
Appl. Sci. 2019, 9(17), 3624; https://doi.org/10.3390/app9173624 - 03 Sep 2019
Viewed by 232
Abstract
This study aims at evaluating the congestion level of pedestrians in metro stations. Twelve hours (4 h × three facilities) of video data were collected in the channel, stairway, and platform in a metro station in the city of Ningbo, China. The indicator [...] Read more.
This study aims at evaluating the congestion level of pedestrians in metro stations. Twelve hours (4 h × three facilities) of video data were collected in the channel, stairway, and platform in a metro station in the city of Ningbo, China. The indicator of GPC (grade of pedestrian crowd) was proposed to quantify the congestion level of pedestrians. Four levels of congestion (level I, level II, level III, and level IV) were determined based on the GPC. A normal-cloud (NC) model was proposed and calibrated for the evaluation of three facilities including channel, stairway, and platform. The evaluation results showed that the GPC of L1-L2 and L2-L1 in channel are level II and level I, respectively. The GPC of upward and downward of stairway are level III and level I. The GPC of platform is level IV. Crowd management countermeasures were proposed for the management of pedestrians in metro station. Full article
(This article belongs to the Section Civil Engineering)
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Open AccessFeature PaperArticle
Effect of the Pillar Size on the Electrochemical Performance of Laser-Induced Silicon Micropillars as Anodes for Lithium-Ion Batteries
Appl. Sci. 2019, 9(17), 3623; https://doi.org/10.3390/app9173623 - 03 Sep 2019
Viewed by 234
Abstract
Silicon micropillars with tunable sizes are successfully fabricated on copper foils by using nanosecond-pulsed laser irradiation and then used as anodes for lithium-ion batteries. The size of the silicon micropillars is manipulated by using different slurry layer thicknesses ranging from a few microns [...] Read more.
Silicon micropillars with tunable sizes are successfully fabricated on copper foils by using nanosecond-pulsed laser irradiation and then used as anodes for lithium-ion batteries. The size of the silicon micropillars is manipulated by using different slurry layer thicknesses ranging from a few microns to tens of microns. The effects of the pillar size on electrochemical properties are thoroughly investigated. The smaller the pillars, the better the electrochemical performance. A capacity of 1647 mAh g−1 at 0.1 C current rate is achieved in the anode with the smallest pillars, with 1215, 892, and 582 mAh g−1 at 0.2, 0.5, and 1.0 C, respectively. Although a significant difference in discharge capacity is observed in the early period of cycling among micropillars of different sizes, this discrepancy becomes smaller as a function of the cycle number. Morphological studies reveal that the expansion of micropillars occurred during long-term cycling, which finally led to the formation of island-like structures. Also, the formation of a solid electrolyte interphase film obstructs Li+ diffusion into Si for lithiation, resulting in capacity decay. This study demonstrates the importance of minimizing the pillar size and optimizing the pillar density during anode fabrication. Full article
(This article belongs to the Special Issue Advanced Materials for Rechargeable Lithium Batteries II)
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Open AccessArticle
Matching Quality Detection System of Synchronizer Ring and Cone
Appl. Sci. 2019, 9(17), 3622; https://doi.org/10.3390/app9173622 - 03 Sep 2019
Viewed by 202
Abstract
A synchronizer is a key component in automotive transmission. It is necessary to detect the matching quality between a synchronizer ring and cone. For this purpose, a friction torque based detection system of matching quality between a synchronizer ring and cone is designed [...] Read more.
A synchronizer is a key component in automotive transmission. It is necessary to detect the matching quality between a synchronizer ring and cone. For this purpose, a friction torque based detection system of matching quality between a synchronizer ring and cone is designed in this paper. In the system, the acceptance criteria are established by the residual sum of squares (RSS), and the quality of the synchronizer is determined by measuring the friction torque and backup gap. This synchronizer ring and cone matching quality detection system has been implemented. The system is mainly used for quality detection of the synchronizer ring and cone in the automobile gearbox before packing. It improves the consistency of the synchronizer ring and synchronizer cone, which makes the synchronizer lighter and more reliable during shifting of the gearbox. According to market research, the system designed and implemented in this paper is advanced and original. Full article
(This article belongs to the Special Issue Machine Fault Diagnostics and Prognostics)
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Open AccessArticle
Pressure Observer Based Adaptive Dynamic Surface Control of Pneumatic Actuator with Long Transmission Lines
Appl. Sci. 2019, 9(17), 3621; https://doi.org/10.3390/app9173621 - 03 Sep 2019
Viewed by 197
Abstract
In this paper, the needle insertion motion control of a magnetic resonance imaging (MRI) compatible robot, which is actuated by a pneumatic cylinder with long transmission lines, is considered and a pressure observer based adaptive dynamic surface controller is proposed. The long transmission [...] Read more.
In this paper, the needle insertion motion control of a magnetic resonance imaging (MRI) compatible robot, which is actuated by a pneumatic cylinder with long transmission lines, is considered and a pressure observer based adaptive dynamic surface controller is proposed. The long transmission line is assumed to be an intermediate chamber connected between the control valve and the actuator in series, and a nonlinear first order system model is constructed to characterize the pressure losses and time delay brought by it. Due to the fact that MRI-compatible pressure sensors are not commercially available, a globally stable pressure observer is employed to estimate the chamber pressure. Based on the model of the long transmission line and the pressure observer, an adaptive dynamic surface controller is further designed by using the dynamic surface control technique. Compared to the traditional backstepping design method, the proposed controller can avoid the problem of “explosion of complexity” since the repeated differentiation of virtual controls is no longer required. The stability of the closed-loop system is analytically proven by employing the Lyapunov theory. Extensive experimental results are presented to demonstrate the effectiveness and the performance robustness of the proposed controller. Full article
(This article belongs to the Special Issue Engineering for Surgery)
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Open AccessArticle
Life-Cycle Assessment of the Substitution of Sand with Coal Bottom Ash in Concrete: Two Concrete Design Methods
Appl. Sci. 2019, 9(17), 3620; https://doi.org/10.3390/app9173620 - 03 Sep 2019
Viewed by 256
Abstract
Life-cycle assessments (LCAs) were conducted to evaluate the replacement of sand with coal bottom ash (CBA) in concrete. CBA is a byproduct of coal-fueled electricity production. Sand was replaced with CBA at proportions of 0, 25, 50, 75, and 100 wt.%, and the [...] Read more.
Life-cycle assessments (LCAs) were conducted to evaluate the replacement of sand with coal bottom ash (CBA) in concrete. CBA is a byproduct of coal-fueled electricity production. Sand was replaced with CBA at proportions of 0, 25, 50, 75, and 100 wt.%, and the resultant concretes were denoted as CBA0, CBA25, CBA50, CBA75, and CBA100, respectively. Two concrete mixture design methods (that resulted in different component qualities of concrete mixtures) were used: (i) Mixture with a fixed slump (MIX-fixed-SLUMP) and (ii) mixture with a fixed water/cement ratio (MIX-fixed-W/C). The ReCiPe2016 midpoint and single score (six methodological options) methods were followed to compare the environmental damage caused by the CBA-based concretes. The ReCiPe2016 results showed that replacing sand with CBA was environmentally (i) beneficial with the MIX-fixed-SLUMP design and (ii) harmful with the MIX-fixed-W/C design. Therefore, using CBA as a partial sand replacement in concrete production is a controversial issue as it highly depends on the concrete mixture design method. Full article
(This article belongs to the Section Civil Engineering)
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Open AccessArticle
Investigation of a Promoted You Only Look Once Algorithm and Its Application in Traffic Flow Monitoring
Appl. Sci. 2019, 9(17), 3619; https://doi.org/10.3390/app9173619 - 03 Sep 2019
Viewed by 214
Abstract
We propose a high-performance algorithm while using a promoted and modified form of the You Only Look Once (YOLO) model, which is based on the TensorFlow framework, to enhance the real-time monitoring of traffic-flow problems by an intelligent transportation system. Real-time detection and [...] Read more.
We propose a high-performance algorithm while using a promoted and modified form of the You Only Look Once (YOLO) model, which is based on the TensorFlow framework, to enhance the real-time monitoring of traffic-flow problems by an intelligent transportation system. Real-time detection and traffic-flow statistics were realized by adjusting the network structure, optimizing the loss function, and introducing weight regularization. This model, which we call YOLO-UA, was initialized based on the weight of a YOLO model pre-trained while using the VOC2007 data set. The UA-CAR data set with complex weather conditions was used for training, and better model parameters were selected through tests and subsequent adjustments. The experimental results showed that, for different weather scenarios, the accuracy of the YOLO-UA was ~22% greater than that of the YOLO model before optimization, and the recall rate increased by about 21%. On both cloudy and sunny days, the accuracy, precision, and recall rate of the YOLO-UA model were more than 94% above the floating rate, which suggested that the precision and recall rate achieved a good balance. When used for video testing, the YOLO-UA model yielded traffic statistics with an accuracy of up to 100%; the time to count the vehicles in each frame was less than 30 ms and it was highly robust in response to changes in scenario and weather. Full article
(This article belongs to the Special Issue Intelligent System Innovation)
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Open AccessArticle
Quantitative Characterization of the Aqua-Dispersing Nano-Binder Effects on the Slip Resistance of Borrowed Soil of a Rock Slope
Appl. Sci. 2019, 9(17), 3618; https://doi.org/10.3390/app9173618 - 03 Sep 2019
Viewed by 188
Abstract
Soil loss can be reduced by enhancing the slip resistance of soil. Therefore, the slip resistance of borrowed soil of rock slopes is key to ecological restoration. An effective way to enhance the soil slip resistance is to improve the permeability and shear [...] Read more.
Soil loss can be reduced by enhancing the slip resistance of soil. Therefore, the slip resistance of borrowed soil of rock slopes is key to ecological restoration. An effective way to enhance the soil slip resistance is to improve the permeability and shear strength of the soil by using polymeric materials. Most current projects have confirmed the amount and effect of additions via repeated tests because of the lack of a quantitative characterization model. This leads to high implementation costs and inhibition of the method’s popularization and application. Therefore, based on different dosages and application processes of aqua-dispersing nano-binder (ADNB), the present study aims to examine the change rules of the particles, permeability, and shear strength after soil improvement through particle analysis, permeability, and direct shear experiments. It was found that ADNB could increase the average particle diameter, permeability coefficient, and shear strength of soil, and significantly enhanced the slip resistance of rock slope soil. On this basis, this paper establishes quantitative characterization models of the slip resistance of rock slopes, reveals the clay improvement mechanism, and proposes the optimal addition range. The study also verified the reliability of the models through an engineering application. It is proved that the appropriate amount of ADNB based on the model can enhance the slip resistance of borrowed soil as well as the ecological restoration effect of rock slopes. The model in question solves the problem of repeated tests during implementation due to the lack of a quantitative characterization model and provides theoretical guidance for the ecological restoration of rock slopes. Full article
(This article belongs to the Special Issue New Trends of Sustainability in Civil Engineering and Architecture)
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Open AccessArticle
Semi-Supervised Convolutional Neural Network for Law Advice Online
Appl. Sci. 2019, 9(17), 3617; https://doi.org/10.3390/app9173617 - 03 Sep 2019
Viewed by 191
Abstract
With the rapid developments of Internet technology, a mass of law cases is constantly occurring and needs to be dealt with in time. Automatic classification of law text is the most basic and critical process in the online law advice platform. Deep neural [...] Read more.
With the rapid developments of Internet technology, a mass of law cases is constantly occurring and needs to be dealt with in time. Automatic classification of law text is the most basic and critical process in the online law advice platform. Deep neural network-based natural language processing (DNN-NLP) is one of the most promising approaches to implement text classification. Meanwhile, as the convolutional neural network-based (CNN-based) methods developed, CNN-based text classification has already achieved impressive results. However, previous work applied amounts of manually-annotated data, which increased the labor cost and reduced the adaptability of the approach. Hence, we present a new semi-supervised model to solve the problem of data annotation. Our method learns the embedding of small text regions from unlabeled data and then integrates the learned embedding into the supervised training. More specifically, the learned embedding regions with the two-view-embedding model are used as an additional input to the CNN’s convolution layer. In addition, to implement the multi-task learning task, we propose the multi-label classification algorithm to assign multiple labels to an instance. The proposed method is evaluated experimentally subject to a law case description dataset and English standard dataset RCV1 . On Chinese data, the simulation results demonstrate that, compared with the existing methods such as linear SVM, our scheme respectively improves by 7.76%, 7.86%, 9.19%, and 2.96% the precision, recall, F-1, and Hamming loss. Analogously, the results suggest that compared to CNN, our scheme respectively improves by 4.46%, 5.76%, 5.14% and 0.87% in terms of precision, recall, F-1, and Hamming loss. It is worth mentioning that the robustness of this method makes it suitable and effective for automatic classification of law text. Furthermore, the design concept proposed is promising, which can be utilized in other real-world applications such as news classification and public opinion monitoring. Full article
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Open AccessArticle
Spatial-Temporal Self-Focusing of Partially Coherent Pulsed Beams in Dispersive Medium
Appl. Sci. 2019, 9(17), 3616; https://doi.org/10.3390/app9173616 - 03 Sep 2019
Viewed by 218
Abstract
Partially coherent pulsed beams have many applications in pulse shaping, fiber optics, ghost imaging, etc. In this paper, a novel class of partially coherent pulsed (PCP) sources with circular spatial coherence distribution and sinc temporal coherence distribution is introduced. The analytic formula for [...] Read more.
Partially coherent pulsed beams have many applications in pulse shaping, fiber optics, ghost imaging, etc. In this paper, a novel class of partially coherent pulsed (PCP) sources with circular spatial coherence distribution and sinc temporal coherence distribution is introduced. The analytic formula for the spatial-temporal intensity of pulsed beams generated by this kind of source in dispersive media is derived. The evolution behavior of spatial-temporal intensity of the pulsed beams in water and air is investigated, respectively. It is found that the pulsed beams exhibit spatial-temporal self-focusing behavior upon propagation. Furthermore, a physical interpretation of the spatial-temporal self-focusing phenomenon is given. This is a phenomenon of optical nonlinearity, which may have potential application in laser micromachining and laser filamentation. Full article
(This article belongs to the Special Issue Recent Advances in Statistical Optics and Plasmonics)
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Open AccessArticle
Flow Analysis Based on Cathodic Current Using Different Designs of Channel Distribution In PEM Fuel Cells
Appl. Sci. 2019, 9(17), 3615; https://doi.org/10.3390/app9173615 - 03 Sep 2019
Viewed by 277
Abstract
In this work, a physical and numerical simulation of cathodic current for different designs of the channel distribution in PEM fuel cells was carried out. The first design consisted serpentine-type channels with abrupt changes in flow direction. On the other hand, Designs 2 [...] Read more.
In this work, a physical and numerical simulation of cathodic current for different designs of the channel distribution in PEM fuel cells was carried out. The first design consisted serpentine-type channels with abrupt changes in flow direction. On the other hand, Designs 2 and 3 were made of serpentine channels with a more gradual change in flow direction. The fourth design was a crisscross-type channel, which was based on continually redirecting the flow, while Design 5 was made with straight parallel channels. Designs 1–3 had one intake, while Designs 4 and 5 had three. The latter two produced more uniform electrical current distributions than Designs 1–3. It can be concluded that the intakes situated effectively within each design were as important as the shape of the channel configuration. Finally, the parallel channel flow field (Design 5) was the best alternative for current collectors due to its better performance. Full article
(This article belongs to the Section Energy)
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Open AccessArticle
Safety Effects of Freeway Hard Shoulder Running
Appl. Sci. 2019, 9(17), 3614; https://doi.org/10.3390/app9173614 - 02 Sep 2019
Viewed by 246
Abstract
Hard shoulder running (HSR) has been increasingly used as a sustainable and viable way to increase road capacity. This study investigated the safety effect of HSR on freeways in South Korea using the empirical Bayes method. This study found an increase in the [...] Read more.
Hard shoulder running (HSR) has been increasingly used as a sustainable and viable way to increase road capacity. This study investigated the safety effect of HSR on freeways in South Korea using the empirical Bayes method. This study found an increase in the total number of crashes. In terms of crash severity, a higher proportion of crashes (25.3%) on 2(3)-lane sections were found to be serious (involving injuries and/or fatalities) compared to those on 4(5)-lane sections (3.6%). Also, a positive relationship was found between the length of the hard shoulder running and changes in crash frequencies. Thus, hard shoulder running on lengthy 2(3)-lane freeways should be avoided. Full article
(This article belongs to the Special Issue Future-Ready Sustainable Infrastructure Systems)
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Open AccessArticle
Motion Capture Research: 3D Human Pose Recovery Based on RGB Video Sequences
Appl. Sci. 2019, 9(17), 3613; https://doi.org/10.3390/app9173613 - 02 Sep 2019
Viewed by 229
Abstract
Using video sequences to restore 3D human poses is of great significance in the field of motion capture. This paper proposes a novel approach to estimate 3D human action via end-to-end learning of deep convolutional neural network to calculate the parameters of the [...] Read more.
Using video sequences to restore 3D human poses is of great significance in the field of motion capture. This paper proposes a novel approach to estimate 3D human action via end-to-end learning of deep convolutional neural network to calculate the parameters of the parameterized skinned multi-person linear model. The method is divided into two main stages: (1) 3D human pose estimation based on a single frame image. We use 2D/3D skeleton point constraints, human height constraints, and generative adversarial network constraints to obtain a more accurate human-body model. The model is pre-trained using open-source human pose datasets; (2) Human-body pose generation based on video streams. Combined with the correlation of video sequences, a 3D human pose recovery method based on video streams is proposed, which uses the correlation between videos to generate a smoother 3D pose. In addition, we compared the proposed 3D human pose recovery method with the commercial motion capture platform to prove the effectiveness of the proposed method. To make a contrast, we first built a motion capture platform through two Kinect (V2) devices and iPi Soft series software to obtain depth-camera video sequences and monocular-camera video sequences respectively. Then we defined several different tasks, including the speed of the movements, the position of the subject, the orientation of the subject, and the complexity of the movements. Experimental results show that our low-cost method based on RGB video data can achieve similar results to commercial motion capture platform with RGB-D video data. Full article
(This article belongs to the Special Issue Computer Vision and Pattern Recognition in the Era of Deep Learning)
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Open AccessArticle
Multi-Focus Image Fusion Based on Decision Map and Sparse Representation
Appl. Sci. 2019, 9(17), 3612; https://doi.org/10.3390/app9173612 - 02 Sep 2019
Viewed by 219
Abstract
As the focal length of an optical lens in a conventional camera is limited, it is usually arduous to obtain an image in which each object is focused. This problem can be solved by multi-focus image fusion. In this paper, we propose an [...] Read more.
As the focal length of an optical lens in a conventional camera is limited, it is usually arduous to obtain an image in which each object is focused. This problem can be solved by multi-focus image fusion. In this paper, we propose an entirely new multi-focus image fusion method based on decision map and sparse representation (DMSR). First, we obtained a decision map by analyzing low-scale images with sparse representation, measuring the effective clarity level, and using spatial frequency methods to process uncertain areas. Subsequently, the transitional area around the focus boundary was determined by the decision map, and we implemented the transitional area fusion based on sparse representation. The experimental results show that the proposed method is superior to the other five fusion methods, both in terms of visual effect and quantitative evaluation. Full article
(This article belongs to the Special Issue Advanced Ultrafast Imaging)
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Open AccessArticle
Sex Differences in the Footprint Analysis During the Entire Gait Cycle in a Functional Equinus Condition: Novel Cross Sectional Research
Appl. Sci. 2019, 9(17), 3611; https://doi.org/10.3390/app9173611 - 02 Sep 2019
Viewed by 357
Abstract
Some studies suggest that gender is related to gait. Females show significantly higher ankle motion and vertical ground reaction forces. Males have significantly larger plantar contact surface areas in all regions of the foot than females in most, but not all, prior studies. [...] Read more.
Some studies suggest that gender is related to gait. Females show significantly higher ankle motion and vertical ground reaction forces. Males have significantly larger plantar contact surface areas in all regions of the foot than females in most, but not all, prior studies. However, there is no research on sex differences in a functional equinus condition. In this study, 119 individuals, including 59 females (29.7 ± 5.15 years, 58.74 ± 6.66 kg, 163.65 ± 5.58 cm) and 60 males (31.22 ± 6.06 years, 75.67 ± 9.81 kg, 177.10 ± 6.16 cm), with a functional equinus condition walked onto a pressure platform. In two separate testing sessions, five trials of each foot were conducted for the first, second, and third steps. We measured the contact surface areas for each of the three phases of the stance phase. We computed the intraclass correlation coefficient and standard error of the mean to assess the reliability. We found significantly greater contact surface areas in males than females in the first, second, and third steps in all phases of the stance phase: heel strike, mid-stance, and take-off. This is important information for the design of footwear and orthotics and gender knowledge. In a functional equinus condition, males have registered greater contact surface areas than females in all phases of the dynamic footprint of the stance phase. Full article
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Open AccessArticle
Analysis of DC Characteristics in GaN-Based Metal-Insulator-Semiconductor High Electron Mobility Transistor with Variation of Gate Dielectric Layer Composition by Considering Self-Heating Effect
Appl. Sci. 2019, 9(17), 3610; https://doi.org/10.3390/app9173610 - 02 Sep 2019
Viewed by 276
Abstract
This study investigates metal-insulator-semiconductor high electron mobility transistor DC characteristics with different gate dielectric layer compositions and thicknesses, and lattice temperature effects on gate leakage current by using a two-dimensional simulation. We first compared electrical properties, including threshold voltage, transconductance, and gate leakage [...] Read more.
This study investigates metal-insulator-semiconductor high electron mobility transistor DC characteristics with different gate dielectric layer compositions and thicknesses, and lattice temperature effects on gate leakage current by using a two-dimensional simulation. We first compared electrical properties, including threshold voltage, transconductance, and gate leakage current with the self-heating effect, by applying a single Si3N4 dielectric layer. We then employed different Al2O3 dielectric layer thicknesses on top of the Si3N4, and also investigated lattice temperature across a two-dimensional electron gas channel layer with various dielectric layer compositions to verify the thermal effect on gate leakage current. Gate leakage current was significantly reduced as the dielectric layer was added, and further decreased for a 15-nm thick Al2O3 on a 5-nm Si3N4 structure. Although the gate leakage current increased as Al2O3 thickness increased to 35 nm, the breakdown voltage was improved. Full article
(This article belongs to the Special Issue NANO KOREA 2019)
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