Applied Sciences

16 pages, 52593 KiB

Open AccessArticle

Investigation of Size Effects Due to Different Cooling Rates of As-Quenched Martensite Microstructures in a Low-Alloy Steel

by Marius Graf, Matthias Kuntz, Hermann Autenrieth and Ralf Müller

Appl. Sci. 2020, 10(15), 5395; https://doi.org/10.3390/app10155395 - 04 Aug 2020

Cited by 8 | Viewed by 3931

Abstract

Martensite transformation is a complex mechanism in materials that is classically initiated by a suitable heat treatment. This heat treatment process can be optimized based on a better understanding of the physical mechanisms on the length scale of several prior austenite grains. It [...] Read more.

Martensite transformation is a complex mechanism in materials that is classically initiated by a suitable heat treatment. This heat treatment process can be optimized based on a better understanding of the physical mechanisms on the length scale of several prior austenite grains. It is therefore appropriate to consider individual process steps of heat treatment in isolation. The aim of this study is to characterize the microstructural size changes caused by a variation of the cooling rate applied during the quenching process. For this purpose, individual martensitic microstructures from different heat treatments are analyzed using the electron backscatter diffraction (EBSD) method. With special orientation relationships between the parent austenite and martensite, the structure of the prior austenite grains and the close packet plane packets can then be reconstructed. The influence of the heat treatments on these characteristics as well as on the martensite blocks is thus quantified. No significant influence of the quenching rate on the sizes of martensite blocks and packets could be found. Full article

(This article belongs to the Special Issue Microstructural Characterization of Metals, from Nano to Macro Scale)

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11 pages, 2945 KiB

Open AccessArticle

Microstructure and Nanohardness of Ti-48Al-2Cr Alloy Solidified under High Pressure

by Duo Dong, Li Liu, Dongdong Zhu, Yang Liu, Ye Wang, Xiaohong Wang and Zunjie Wei

Appl. Sci. 2020, 10(15), 5394; https://doi.org/10.3390/app10155394 - 04 Aug 2020

Cited by 1 | Viewed by 1987

Abstract

In this work, the Ti-48Al-2Cr alloy, solidified under different pressures and temperatures, was investigated in detail. The effect of high pressure on the microstructure and nanohardness of the Ti-48Al-2Cr alloy was investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and a [...] Read more.

In this work, the Ti-48Al-2Cr alloy, solidified under different pressures and temperatures, was investigated in detail. The effect of high pressure on the microstructure and nanohardness of the Ti-48Al-2Cr alloy was investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and a nanoindenter XP testing machine. The results showed that the B2 phase disappeared after high-pressure solidification. Compared with ambient pressure solidification, high pressure led to the increase of (α₂ + γ) lamellar structure and the decrease of γ phase. The nanohardness of the lamellar structure was discussed based on the microstructure observation. When solidified at 5 GPa/1873 K, the hardness rose to 5.54 GPa, an increase of 60.5% compared with that solidified at ambient pressure. However, the increased holding temperature of 1973 K made the dislocation density in the lamellar structures greatly decrease, and reduced the structure’s hardness to 4.48 GPa. Full article

(This article belongs to the Section Nanotechnology and Applied Nanosciences)

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16 pages, 5062 KiB

Open AccessArticle

Numerical 3D Modeling: Microwave Plasma Torch at Intermediate Pressure

by Qinghao Shen, Run Huang, Zili Xu and Wei Hua

Appl. Sci. 2020, 10(15), 5393; https://doi.org/10.3390/app10155393 - 04 Aug 2020

Cited by 7 | Viewed by 4795

Abstract

This study represents a self-consistent three-dimensional (3D) fluid plasma model coupled with Maxwell equations at an intermediate pressure between 1000 and 5000 Pa. The model was established using the finite element method to analyze the effects of time–space characteristics, which is the variation [...] Read more.

This study represents a self-consistent three-dimensional (3D) fluid plasma model coupled with Maxwell equations at an intermediate pressure between 1000 and 5000 Pa. The model was established using the finite element method to analyze the effects of time–space characteristics, which is the variation of plasma parameters with time and the 3D spatial distribution of plasma parameters in the plasma torch at various times. The numerical modeling was demonstrated in three different stages, where the growth of electron density is associated with time. From the distribution characteristics of molecular ions, it can be concluded that they are distributed mainly at the port of the quartz tube of the torch, which is larger than the center of the tube. The density ratio of molecular ion to electron is decreased because of the reduction of pressure and distance, which has been calculated from the port to the center of the quartz tube. The analysis of microwave plasma parameters indicated that intermediate pressure is useful for modeling and plasma source designing, especially for carbon dioxide conversion. Full article

(This article belongs to the Special Issue The Applications of Plasma Techniques)

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10 pages, 674 KiB

Open AccessArticle

Ferrite-Loaded Spidron Fractal Loop VHF Antenna for UAV Applications

by Won Bin Park, Young-Mi Park and Keum Cheol Hwang

Appl. Sci. 2020, 10(15), 5392; https://doi.org/10.3390/app10155392 - 04 Aug 2020

Cited by 2 | Viewed by 4198

Abstract

In this letter, an electrically small Spidron fractal loop antenna operating in the VHF band is proposed. The ferrite material, which consists of a nickel-zinc combination, is loaded into inside of the loop antenna to increase the gain of the antenna in the [...] Read more.

In this letter, an electrically small Spidron fractal loop antenna operating in the VHF band is proposed. The ferrite material, which consists of a nickel-zinc combination, is loaded into inside of the loop antenna to increase the gain of the antenna in the low frequency band. To minimize the magnetic loss of the ferrite in the high frequency band, the amount and configuration of the ferrite are optimized using a genetic algorithm. Through this optimization step, the amount of the ferrite is decreased to 37.5% and the gain of the antenna in the high frequency band is improved. The size of the proposed antenna is 0.0242

\times

0.0242

\times

0.0051

λ_{L}^{3}

at the lowest operating frequency. The proposed antenna was fabricated to verify the performance, and the simulated and measured results are in good agreement. The measured peak gains varied from −31.6 to −1.9 dBi within the measured frequency band. To examine the performance of the proposed antenna mounted on an unmanned aerial vehicle model (UAV), the antenna on a UAV was also simulated and the results were discussed. The simulated realized peak gains of the antenna on the UAV and on flat ground are similar. Full article

(This article belongs to the Section Electrical, Electronics and Communications Engineering)

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24 pages, 5289 KiB

Open AccessArticle

Optimization and Economic Analysis for Small-Scale Movable LNG Liquefaction Process with Leakage Considerations

by Sang Hyun Lee, Dong-Ha Lim and Kyungtae Park

Appl. Sci. 2020, 10(15), 5391; https://doi.org/10.3390/app10155391 - 04 Aug 2020

Cited by 10 | Viewed by 3926

Abstract

In this study, exergy and economic analysis were conducted to gain insight on small-scale movable LNG liquefaction considering leakage. Optimization and comparison were performed to demonstrate the quantitative results of single mixed refrigerant, dual nitrogen expansion, and the propane pre-cooling self-refrigeration processes. For [...] Read more.

In this study, exergy and economic analysis were conducted to gain insight on small-scale movable LNG liquefaction considering leakage. Optimization and comparison were performed to demonstrate the quantitative results of single mixed refrigerant, dual nitrogen expansion, and the propane pre-cooling self-refrigeration processes. For the optimization, exergy efficiency was used as the objective function; the results showed that exergy efficiencies are 38.85%, 19.96%, and 13.65%, for single mixed refrigerant, dual nitrogen expansion, and propane pre-cooling self-refrigeration, respectively. Further, the cost analysis showed that the product cost of each process is 4002.3 USD/tpa, 5490.2 USD/tpa, and 9608.5 USD/tpa. A sensitivity analysis was conducted to determine parameters that affect exergy and cost. The SMR process is the most competitive in terms of exergy efficiency, product cost, and operability, without considering makeup facilities. Full article

(This article belongs to the Special Issue Recent Advances in Sustainable Process Design and Optimization)

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18 pages, 7837 KiB

Open AccessArticle

Local Phase-Amplitude Joint Correction for Free Surface Velocity of Hopkinson Pressure Bar

by Jun Yang, Junhua He, Dezhi Zhang, Haibin Xu, Guokai Shi, Min Zhang, Wenxiang Liu and Yang Zhang

Appl. Sci. 2020, 10(15), 5390; https://doi.org/10.3390/app10155390 - 04 Aug 2020

Cited by 5 | Viewed by 2046

Abstract

The Hopkinson pressure bar is widely used to measure the reflected pressure of blast waves over a short distance. However, dispersion effects will occur when the elastic stress waves propagate in the pressure bar due to lateral inertia, and there will be errors [...] Read more.

The Hopkinson pressure bar is widely used to measure the reflected pressure of blast waves over a short distance. However, dispersion effects will occur when the elastic stress waves propagate in the pressure bar due to lateral inertia, and there will be errors between the signals obtained from the sensors and the actual loading. For the free surface velocity measured in our system, we developed a local phase-amplitude joint correction method to convert the measured velocity into the average reflected pressure of a shock wave at the impact end of the bar, considering factors such as propagation modes of the elastic wave, the frequency components’ time of arrival, velocity variation over the bar axis, and the stress–velocity relationship. Firstly, the Pochhammer–Chree frequency equation is calculated numerically, and the first to fourth orders of phase velocity, group velocity, normalized frequency, and propagation time curves of elastic wave propagation in 35CrMnSiA steel are obtained. Secondly, the phase and amplitude correction formulas for calculating average reflected pressure from center velocity are derived based on the propagation mode of the axial elastic wave in the pressure bar by analyzing the time-frequency combined spectrum obtained by short-time Fourier transform. Thirdly, a local phase-amplitude joint correction algorithm based on propagation mode is proposed in detail. The experimental tests and data analyses are carried out for eight sets of pressure bar. The results show that this method can identify the propagation mode of elastic waves in the bar intuitively and clearly. The first three orders of propagation modes are stimulated in the bar 04, while only the first order of propagation is stimulated in the other eight bars. The local phase-amplitude joint correction algorithm can avoid correcting the component of the non-axial elastic wave. The rising edge of the average stress curve on the impact surface of bar 01 and bar 04 is corrected from 4.13 μs and 4.09 μs to 2.70 μs, respectively. Full article

(This article belongs to the Section Mechanical Engineering)

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17 pages, 5861 KiB

Open AccessArticle

Parametric and Statistical Study of the Wing Geometry of 75 Species of Odonata

by Nasim Chitsaz, Romeo Marian, Amirmasoud Chitsaz and Javaan S. Chahl

Appl. Sci. 2020, 10(15), 5389; https://doi.org/10.3390/app10155389 - 04 Aug 2020

Cited by 5 | Viewed by 3888

Abstract

The flight performance and maneuverability of Odonata depends on wing shape and aero-structural characteristics, including airfoil shape, wingspan, and chord. Despite the superficial similarity between Odonata planforms, the frequency with which they are portrayed artistically, and the research interest in their aerodynamics, those [...] Read more.

The flight performance and maneuverability of Odonata depends on wing shape and aero-structural characteristics, including airfoil shape, wingspan, and chord. Despite the superficial similarity between Odonata planforms, the frequency with which they are portrayed artistically, and the research interest in their aerodynamics, those features that are stable and those that are labile between species have not been identified. Studies have been done on 2D aerodynamics over corrugated wings; however, there is limited comparative quantified data on the planforms of Odonata wings. This study was undertaken to explore the scale relationships between the geometrical parameters of photogrammetrically reconstructed wings of 75 Odonata species, 66 from Epiprocta, and 9 from Zygoptera. The wing semi-spans captured in the database range from 24 to 85 mm. By carrying out an extensive statistical analysis of data, we show that the geometrical parameters for the suborder Epiprocta (dragonflies) can be classified into scale-dependent and independent parameters using regression analysis. A number of close correlations were found between the wingspan and the size of other structures. We found that amongst the variables considered, the largest independent variations against the forewing span were found in the chord of the hindwing, and that hindwing properties were not reliably predicted by the Odonata family. We suggest that this indicates continuous evolutionary pressure on this structure. Full article

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17 pages, 301 KiB

Open AccessArticle

Semi-Steady-State Jaya Algorithm for Optimization

by Uday K. Chakraborty

Appl. Sci. 2020, 10(15), 5388; https://doi.org/10.3390/app10155388 - 04 Aug 2020

Cited by 9 | Viewed by 2084

Abstract

The Jaya algorithm is arguably one of the fastest-emerging metaheuristics amongst the newest members of the evolutionary computation family. The present paper proposes a new, improved Jaya algorithm by modifying the update strategies of the best and the worst members in the population. [...] Read more.

The Jaya algorithm is arguably one of the fastest-emerging metaheuristics amongst the newest members of the evolutionary computation family. The present paper proposes a new, improved Jaya algorithm by modifying the update strategies of the best and the worst members in the population. Simulation results on a twelve-function benchmark test-suite and a real-world problem show that the proposed strategy produces results that are better and faster in the majority of cases. Statistical tests of significance are used to validate the performance improvement. Full article

17 pages, 8061 KiB

Open AccessArticle

A Design for a Manufacturing-Constrained Off-Axis Four-Mirror Reflective System

by Ruoxin Liu, Zexiao Li, Yiting Duan and Fengzhou Fang

Appl. Sci. 2020, 10(15), 5387; https://doi.org/10.3390/app10155387 - 04 Aug 2020

Cited by 4 | Viewed by 3256

Abstract

Off-axis reflective optical systems find wide applications in various industries, but the related manufacturing issues have not been well considered in the design process. This paper proposed a design method for cylindrical reflective systems considering manufacturing constraints to facilitate ultra-precision raster milling. An [...] Read more.

Off-axis reflective optical systems find wide applications in various industries, but the related manufacturing issues have not been well considered in the design process. This paper proposed a design method for cylindrical reflective systems considering manufacturing constraints to facilitate ultra-precision raster milling. An appropriate index to evaluate manufacturing constraints is established. The optimization solution is implemented for the objective function composed of primary aberration coefficients with weights and constraint conditions of the structural configuration by introducing the genetic algorithm. The four-mirror initial structure with a good imaging quality and a special structural configuration is then obtained. The method’s feasibility is validated by designing an off-axis four-mirror afocal system with an entrance pupil diameter of 170 mm, a field of view of 3° × 3° and a compression ratio of five times. All mirrors in the system are designed to be distributed along a cylinder. Full article

(This article belongs to the Collection Optical Design and Engineering)

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17 pages, 4066 KiB

Open AccessArticle

Variable-Diameter Drum with Concentric Threshing Gap and Performance Comparison Experiment

by Yaoming Li, Zhan Su, Zhenwei Liang and Yu Li

Appl. Sci. 2020, 10(15), 5386; https://doi.org/10.3390/app10155386 - 04 Aug 2020

Cited by 15 | Viewed by 3495

Abstract

The threshing gap of the thresher device for rice combine harvester has to be adjusted in real time based on different feed rates to ensure the operation efficiency in the harvesting process. However, adjusting the threshing gap by changing the position of concave [...] Read more.

The threshing gap of the thresher device for rice combine harvester has to be adjusted in real time based on different feed rates to ensure the operation efficiency in the harvesting process. However, adjusting the threshing gap by changing the position of concave grid may result in unevenness of threshing gap of the thresher device and further impact on the fluidity of material in the thresher device; in addition, it is also unavailable to adjust the threshing gap by changing the drum diameter when the rice combine harvester is in operation. In view of the above and based on axial flow threshing drum, the design of a variable-diameter threshing drum available for overall and rapid drum diameter adjustment and the research on diameter adjustment device as well as electronic control self-locking device were introduced in this study. Besides, stress analysis was implemented to the diameter adjustment device to ensure the stability of the variable-diameter threshing drum. Field experiment was implemented to identify the difference between the impacts brought to the threshing performance (grain-entrainment loss rate, damage rate, threshing efficiency, and threshing power consumption) by both methods for threshing gap adjustment. The experiment result shows that the drum adjustment method with variable-diameter drum features higher grain-entrainment loss rate, threshing efficiency, and threshing power consumption, yet stable in terms of consumption fluctuation, but a lower damage rate than their counterparts with concave adjustment method. Full article

(This article belongs to the Section Environmental Sciences)

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14 pages, 2529 KiB

Open AccessArticle

Non-Local Spatial and Temporal Attention Network for Video-Based Person Re-Identification

by Zheng Liu, Feixiang Du, Wang Li, Xu Liu and Qiang Zou

Appl. Sci. 2020, 10(15), 5385; https://doi.org/10.3390/app10155385 - 04 Aug 2020

Cited by 3 | Viewed by 2569

Abstract

Given a video containing a person, the video-based person re-identification (Re-ID) task aims to identify the same person from videos captured under different cameras. How to embed spatial-temporal information of a video into its feature representation is a crucial challenge. Most existing methods [...] Read more.

Given a video containing a person, the video-based person re-identification (Re-ID) task aims to identify the same person from videos captured under different cameras. How to embed spatial-temporal information of a video into its feature representation is a crucial challenge. Most existing methods have failed to make full use of the relationship between frames during feature extraction. In this work, we propose a plug-and-play non-local attention module (NLAM) for frame-level feature extraction. NLAM, based on global spatial attention and channel attention, helps the network to determine the location of the person in each frame. Besides, we propose a non-local temporal pooling (NLTP) method used for temporal features’ aggregation, which can effectively capture long-range and global dependencies among the frames of the video. Our model obtained impressive results on different datasets compared to the state-of-the-art methods. In particular, it achieved the rank-1 accuracy of 86.3% on the MARS (Motion Analysis and Re-identification Set) dataset without re-ranking, which is 1.4% higher than the state-of-the-art way. On the DukeMTMC-VideoReID (Duke Multi-Target Multi-Camera Video Reidentification) dataset, our method also had an excellent performance of 95% rank-1 accuracy and 94.5% mAP (mean Average Precision). Full article

(This article belongs to the Section Computing and Artificial Intelligence)

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17 pages, 3388 KiB

Open AccessArticle

Using Committee Neural Network for Prediction of Pressure Drop in Two-Phase Microchannels

by Arman Haghighi, Mostafa Safdari Shadloo, Akbar Maleki and Mohammad Yaghoub Abdollahzadeh Jamalabadi

Appl. Sci. 2020, 10(15), 5384; https://doi.org/10.3390/app10155384 - 04 Aug 2020

Cited by 14 | Viewed by 2832

Abstract

Numerous studies have proposed to correlate experimental results, however there are still significant errors in those predictions. In this study, an artificial neural network (ANN) is considered for a two-phase flow pressure drop in microchannels incorporating four neural network structures: multilayer perceptron (MLP), [...] Read more.

Numerous studies have proposed to correlate experimental results, however there are still significant errors in those predictions. In this study, an artificial neural network (ANN) is considered for a two-phase flow pressure drop in microchannels incorporating four neural network structures: multilayer perceptron (MLP), radial basis function (RBF), general regression (GR), and cascade feedforward (CF). The pressure drop predication by ANN uses six inputs (hydraulic diameter of channel, critical temperature of fluid, critical pressure of fluid, acentric factor of fluid, mass flux, and quality of vapor). According to the experimental data, for each network an optimal number of neurons in the hidden layer is considered in the range 10–11. A committee neural network (CNN) is fabricated through the genetic algorithm to improve the accuracy of the predictions. Ultimately, the genetic algorithm designates a weight to each ANN model, which represents the relative contribution of each ANN in the pressure drop predicting process for a two-phase flow within a microchannel. The assessment based on the statistical indexes reveals that the results are not similar for all models; the absolute average relative deviation percent for MLP, CF, GR, and CNN were obtained to be equal to 10.89, 10.65, 7.63, and 5.79, respectively. The CNN approach is demonstrated to be superior to many ANN techniques, even with simple linearity in the model. Full article

(This article belongs to the Special Issue Advancement in Phase Change Material Technologies)

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21 pages, 5392 KiB

Open AccessArticle

Induction Motor Fault Classification Based on FCBF-PSO Feature Selection Method

by Chun-Yao Lee and Wen-Cheng Lin

Appl. Sci. 2020, 10(15), 5383; https://doi.org/10.3390/app10155383 - 04 Aug 2020

Cited by 4 | Viewed by 2355

Abstract

This study proposes a fast correlation-based filter with particle-swarm optimization method. In FCBF–PSO, the weights of the features selected by the fast correlation-based filter are optimized and combined with backpropagation neural network as a classifier to identify the faults of induction motors. Three [...] Read more.

This study proposes a fast correlation-based filter with particle-swarm optimization method. In FCBF–PSO, the weights of the features selected by the fast correlation-based filter are optimized and combined with backpropagation neural network as a classifier to identify the faults of induction motors. Three significant parts were applied to support the FCBF–PSO. First, Hilbert–Huang transforms were used to analyze the current signals of motor normal, bearing damage, broken rotor bars and short circuits in stator windings. Second, ReliefF, symmetrical uncertainty and FCBF three feature-selection methods were applied to select the important features after the feature was captured. Moreover, the accuracy comparison was performed. Third, particle-swarm optimization (PSO) was combined to optimize the selected feature weights which were used to obtain the best solution. The results showed excellent performance of the FCBF–PSO for the induction motor fault classification such as had fewer feature numbers and better identification ability. In addition, the analyzed of the induction motor fault in this study was applied with the different operating environments, namely, SNR = 40 dB, SNR = 30 dB and SNR = 20 dB. The FCBF–PSO proposed by this research could also get the higher accuracy than typical feature-selection methods of ReliefF, SU and FCBF. Full article

(This article belongs to the Special Issue Advances in Pattern Analysis for Identity Recognition and Verification)

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21 pages, 26497 KiB

Open AccessArticle

A Three-Tier Architecture of Large-Scale Wireless Sensor Networks for Big Data Collection

by Ado Adamou Abba Ari, Asside Christian Djedouboum, Abdelhak Mourad Gueroui, Ousmane Thiare, Alidou Mohamadou and Zibouda Aliouat

Appl. Sci. 2020, 10(15), 5382; https://doi.org/10.3390/app10155382 - 04 Aug 2020

Cited by 11 | Viewed by 3351

Abstract

In recent years, technological advances and the ever-increasing power of embedded systems have seen the emergence of so-called smart cities. In these cities, application needs are increasingly calling for Large-Scale Wireless Sensor Networks (LS-WSN). However, the design and implementation of such networks pose [...] Read more.

In recent years, technological advances and the ever-increasing power of embedded systems have seen the emergence of so-called smart cities. In these cities, application needs are increasingly calling for Large-Scale Wireless Sensor Networks (LS-WSN). However, the design and implementation of such networks pose several important and interesting challenges. These low-cost, low-power devices are characterized by limited computing, memory storage, communication, and battery power capabilities. Moreover, sensors are often required to cooperate in order to route the collected data to a single central node (or sink). The many-to-one communication model that governs dense and widely deployed Wireless Sensor Networks (WSNs) most often leads to problems of network overload and congestion. Indeed, it is easy to show that the closer a node is geographical to the sink, the more data sources it has to relay. This leads to several problems including overloading of nodes close to the sink, high loss rate in the area close to the sink, and poor distribution of power consumption that directly affects the lives of these networks. In this context, we propose a contribution to the problem of LS-WSN energy consumption. We designed a hierarchical 3-tier architecture of LS-WSNs coupled with a modeling of the activities of the different sensors in the network. This architecture that is based on clustering also includes a redeployment function to maintain the topology in case of coverage gaps. The results of the performed simulations show that our architecture maximizes the lifetime than compared solutions. Full article

(This article belongs to the Section Electrical, Electronics and Communications Engineering)

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13 pages, 2208 KiB

Open AccessArticle

Research on Lifespan Prediction of Cross-Linked Polyethylene Material for XLPE Cables

by Yi Zhang, Zaijun Wu, Cheng Qian, Xiao Tan, Jinggang Yang and Linlin Zhong

Appl. Sci. 2020, 10(15), 5381; https://doi.org/10.3390/app10155381 - 04 Aug 2020

Cited by 11 | Viewed by 2946

Abstract

In this paper, cross-linked polyethylene (XLPE) cables of the same batch from Factory A, which ran from 1 to 8 years in Jiangsu Province, are sampled. Some widely accepted aging characterization methods of XLPE cables such as the gel content test, differential scanning [...] Read more.

In this paper, cross-linked polyethylene (XLPE) cables of the same batch from Factory A, which ran from 1 to 8 years in Jiangsu Province, are sampled. Some widely accepted aging characterization methods of XLPE cables such as the gel content test, differential scanning calorimetry (DSC) test, tensile test and hardness test are employed to obtain the physicochemical, mechanical and electrical properties of the samples. Then, some lifespan prediction parameters significantly correlated with operating time are obtained through correlation calculations. Finally, a prediction method is proposed to predict the operating time of XLPE cables from Factory A. The test results indicate that parameters including the gel content C_ge, the crystallinity X_C, tensile strength σ, ultimate elongation δ, the dielectric permittivity ε, and the dielectric loss J_tan are significantly correlated with operating time, which can be used in evaluating the aging degree of XLPE cables. Moreover, due to the high accuracy of the experimental verification, it turns out that the lifespan prediction method proposed in this paper can be used to determine the operating time of XLPE cables from Factory A in future research. Full article

(This article belongs to the Section Electrical, Electronics and Communications Engineering)

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21 pages, 25727 KiB

Open AccessArticle

The Influence of Tilt Angle on the Aerodynamic Performance of a Wind Turbine

by Qiang Wang, Kangping Liao and Qingwei Ma

Appl. Sci. 2020, 10(15), 5380; https://doi.org/10.3390/app10155380 - 04 Aug 2020

Cited by 11 | Viewed by 11886

Abstract

Aerodynamic performance of a wind turbine at different tilt angles was studied based on the commercial CFD software STAR-CCM+. Tilt angles of 0, 4, 8 and 12° were investigated based on uniform wind speed and wind shear. In CFD simulation, the rotating motion [...] Read more.

Aerodynamic performance of a wind turbine at different tilt angles was studied based on the commercial CFD software STAR-CCM+. Tilt angles of 0, 4, 8 and 12° were investigated based on uniform wind speed and wind shear. In CFD simulation, the rotating motion of blade was based on a sliding mesh. The thrust, power, lift and drag of the blade section airfoil at different tilt angles have been widely investigated herein. Meanwhile, the tip vortices and velocity profiles at different tilt angles were physically observed. In addition, the influence of the wind shear exponents and the expected value of turbulence intensity on the aerodynamic performance of the wind turbine is also further discussed. The results indicate that the change in tilt angle changes the angle of attack of the airfoil section of the wind turbine blade, which affects the thrust and power of the wind turbine. The aerodynamic performance of the wind turbine is better when the tilt angle is about 4°. Wind shear will cause the thrust and power of the wind turbine to decrease, and the effect of the wind shear exponents on the aerodynamic performance of the wind turbine is significantly greater than the expected effect of the turbulence intensity. The main purpose of the paper was to study the effect of tilt angle on the aerodynamic performance of a fixed wind turbine. Full article

(This article belongs to the Special Issue Wind Turbine Aerodynamics II)

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29 pages, 12197 KiB

Open AccessArticle

An Advanced Vehicle Body Part Inspection Scheme Based on Scattered Point Cloud Data

by Yang Yang, Ming Li and Xie Ma

Appl. Sci. 2020, 10(15), 5379; https://doi.org/10.3390/app10155379 - 04 Aug 2020

Cited by 2 | Viewed by 2660

Abstract

To further improve the efficiency and accuracy of the vehicle part inspection process, this paper designs an accurate and efficient vehicle body part inspection framework based on scattered point cloud data (PCD). Firstly, a hybrid filtering algorithm for point cloud denoising is designed [...] Read more.

To further improve the efficiency and accuracy of the vehicle part inspection process, this paper designs an accurate and efficient vehicle body part inspection framework based on scattered point cloud data (PCD). Firstly, a hybrid filtering algorithm for point cloud denoising is designed to solve the problem of multiple noise points in the original point cloud measurement data. Secondly, a point cloud simplification algorithm based on Fuzzy C-Means (FCM) is designed to solve the problems of a large amount of data and many redundant points in the PCD. Thirdly, a point cloud fine registration algorithm based on the Teaching-Learning-based Optimization (TLBO) algorithm is designed to solve the problem where the initial point cloud measurement data cannot be located properly. Finally, the deviation distance between the PCD and Computer-Aided-Design (CAD) model is calculated by the K-Nearest Neighbor (KNN) algorithm to inspect and analyze the point cloud after preprocessing. On the basis of the design algorithm, four groups that contain measurement data for eight vehicle body parts are analyzed and the results prove the effectiveness of the algorithm, which is very suitable for the inspection process of vehicle body parts. Full article

(This article belongs to the Special Issue Advanced Intelligent Imaging Technology Ⅱ)

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10 pages, 2081 KiB

Open AccessFeature PaperArticle

Analysis of Work-Function Variation Effects in a Tunnel Field-Effect Transistor Depending on the Device Structure

by Garam Kim, Jang Hyun Kim, Jaemin Kim and Sangwan Kim

Appl. Sci. 2020, 10(15), 5378; https://doi.org/10.3390/app10155378 - 04 Aug 2020

Cited by 7 | Viewed by 3308

Abstract

Metal gate technology is one of the most important methods used to increase the low on-current of tunnel field-effect transistors (TFETs). However, metal gates have different work-functions for each grain during the deposition process, resulting in work-function variation (WFV) effects, which means that [...] Read more.

Metal gate technology is one of the most important methods used to increase the low on-current of tunnel field-effect transistors (TFETs). However, metal gates have different work-functions for each grain during the deposition process, resulting in work-function variation (WFV) effects, which means that the electrical characteristics vary from device to device. The WFV of a planar TFET, double-gate (DG) TFET, and electron-hole bilayer TFET (EHBTFET) were examined by technology computer-aided design (TCAD) simulations to analyze the influences of device structure and to find strategies for suppressing the WFV effects in TFET. Comparing the WFV effects through the turn-on voltage (V_turn-on) distribution, the planar TFET showed the largest standard deviation (σV_turn-on) of 20.1 mV, and it was reduced by −26.4% for the DG TFET and −80.1% for the EHBTFET. Based on the analyses regarding metal grain distribution and energy band diagrams, the WFV of TFETs was determined by the number of metal grains involved in the tunneling current. Therefore, the EHBTFET, which can determine the tunneling current by all of the metal grains where the main gate and the sub gate overlap, is considered to be a promising structure that can reduce the WFV effect of TFETs. Full article

(This article belongs to the Special Issue New Aspects of Si-Based Material and Device)

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21 pages, 4649 KiB

Open AccessArticle

3D Documentation with TLS of Caliphal Gate (Ceuta, Spain)

by Rubén Pérez-Álvarez, Julio Manuel de Luis-Ruiz, Raúl Pereda-García, Gema Fernández-Maroto and Beatriz Malagón-Picón

Appl. Sci. 2020, 10(15), 5377; https://doi.org/10.3390/app10155377 - 04 Aug 2020

Cited by 4 | Viewed by 2594

Abstract

Three-dimensional surveying with a terrestrial laser scanner (TLS) has implied a revolution in the field of 3D modeling, as this methodology provides detailed point-clouds with simplified processes of capture. In addition to the point-clouds, other outputs can be obtained, such as ortho-images, virtual [...] Read more.

Three-dimensional surveying with a terrestrial laser scanner (TLS) has implied a revolution in the field of 3D modeling, as this methodology provides detailed point-clouds with simplified processes of capture. In addition to the point-clouds, other outputs can be obtained, such as ortho-images, virtual itineraries, 2D cartography, and meshes, which implies a second avenue of multimedia products, such as 3D Portable Document Format (PDF) files and interactive applications. All these options are interesting for the management and broadcast of cultural heritage. The works that have been developed in this research are aimed at setting a workflow for the TLS surveying works and subsequent data management for the generation of a 3D model of the Caliphal Gate of Ceuta, which is considered as one of the most important medieval findings in Spain in recent years, and its immediate surroundings. This model and the different outputs that have been obtained from it allow for the continuation of the historiographic analysis of the complex, while documenting a partial stage in the development of the works of enhancement. In addition to this, these products are not only useful in terms of conservation studies or enhancement, as they are also suitable for the dissemination of the site. Special attention has been set on the paid suitable software for data management while generating the outputs, and for its application by the final users. Full article

(This article belongs to the Special Issue 3D Virtual Reconstruction for Archaeological Sites)

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11 pages, 3276 KiB

Open AccessArticle

Bioactive Healing Abutment as a Potential Tool for the Treatment of Peri-Implant Disease—In Vitro Study

by Bartłomiej Iwańczyk, Piotr Wychowański, Anna Minkiewicz-Zochniak, Kamila Strom, Sylwia Jarzynka and Gabriela Olędzka

Appl. Sci. 2020, 10(15), 5376; https://doi.org/10.3390/app10155376 - 04 Aug 2020

Cited by 7 | Viewed by 4317

Abstract

The common use of dental implants for dental reconstruction poses new treatment challenges for physicians, peri-implantitis being a particularly difficult one. Micro-organisms, including drug-resistant Staphylococcus spp. strains, play a crucial role in the etiology of peri-implantitis. In this paper, the authors assess the [...] Read more.

The common use of dental implants for dental reconstruction poses new treatment challenges for physicians, peri-implantitis being a particularly difficult one. Micro-organisms, including drug-resistant Staphylococcus spp. strains, play a crucial role in the etiology of peri-implantitis. In this paper, the authors assess the efficacy of a bioactive healing abutment (BHA) of their own design for the local release of antibiotics as a potential tool for the treatment of peri-implant disease. BHA filled with a collagen material, combined with the antibiotics clindamycin and tetracycline, was tested in vitro by disk diffusion assay. Antibacterial activity was observed for the chosen Staphylococcus aureus and Staphylococcus epidermidis bacterial strains. In addition, the impact of titanium discs (which were used to make the BHA) was monitored. The results show that the zone diameter breakpoints for BHA are higher than those of standard absorbent paper discs in both tested strains for both tested antibiotics. This work demonstrates that the proposed BHA can serve as an effective and precise drug carrier. The release of antibiotics from the described implant device is easy to control and allows for an effective local antibacterial in vitro treatment. The procedure is inexpensive, easy to perform, and repeatable. Full article

(This article belongs to the Section Applied Dentistry and Oral Sciences)

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13 pages, 4235 KiB

Open AccessArticle

Experimental Evaluation on the Effect of Electrode Configuration in Electrostatic Actuators for Increasing Vibrotactile Feedback Intensity

by Taylor Mason, Jeong-Hoi Koo, Young-Min Kim and Tae-Heon Yang

Appl. Sci. 2020, 10(15), 5375; https://doi.org/10.3390/app10155375 - 04 Aug 2020

Cited by 5 | Viewed by 2296

Abstract

Vibrotactile feedback is a key feature of many modern touch displays, which greatly enhances user experiences when interacting with an onscreen interface. Despite its popularity in small touch screen devices, this haptic feature is absent in most large displays due to a lack [...] Read more.

Vibrotactile feedback is a key feature of many modern touch displays, which greatly enhances user experiences when interacting with an onscreen interface. Despite its popularity in small touch screen devices, this haptic feature is absent in most large displays due to a lack of suitable actuators for such applications. Thus, a growing need exists for haptic actuators capable of producing sufficient vibrations in large touch displays. This study proposes and evaluates a novel electrostatic resonant actuator (ERA) with a moving mass and dual electrodes for increased vibration feedback intensity. The dual-electrode ERA was fabricated along with a comparable single-electrode ERA to investigate the effect of the electrode configuration on the maximum vibration intensity. When measured directly on the mass, the maximum vibration intensity of the dual-electrode actuator increased by 73% compared to the single-electrode actuator. When mounted and measured on a mock panel, the maximum vibration intensity of the dual-electrode actuator increased by nearly 65% compared to a similarly mounted single-electrode actuator. These results show that the dual-electrode configuration can significantly increase the vibration intensity when compared to the conventional ERA. This demonstrates a promising potential for the use of the proposed actuator for generating vibrotactile feedback in large touch displays. Full article

(This article belongs to the Special Issue Haptics: Technology and Applications)

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14 pages, 5834 KiB

Open AccessArticle

Selection of Tanned-Leather Waste in Recovering Novel Raw Material for Manufacturing Rubber Artifacts: Towards a Zero-Waste Condition

by Gennaro Bufalo, Bruno Molino and Luigi Ambrosone

Appl. Sci. 2020, 10(15), 5374; https://doi.org/10.3390/app10155374 - 04 Aug 2020

Cited by 6 | Viewed by 2726

Abstract

Zero-waste is an ambitious goal to encourage sustainable production, consumption optimum recycling and resource recovery. The recycling and resource recovery of chrome-tanned leather waste is a difficult proposition because of the three-dimensional chemical network of collagen, which renders leather waste incompatible to polymer [...] Read more.

Zero-waste is an ambitious goal to encourage sustainable production, consumption optimum recycling and resource recovery. The recycling and resource recovery of chrome-tanned leather waste is a difficult proposition because of the three-dimensional chemical network of collagen, which renders leather waste incompatible to polymer matrices. Many attempts have been undertaken to reuse leather waste, most of them require technological processes and challenging chemical pretreatments, which make the reuse an economically disadvantageous industrial operation. The paper aims to show how a very fine separation of leather solid waste leads to raw materials suitable for mixtures with natural rubber, without any chemical pretreatment. In other words, the paper intends to be a stimulus to manage leather solid waste carefully to start a cleaner and more profitable production. In particular, various industrial compounds containing different concentrations of post-tanning dyeing, or chrome shaving or oil-tanning and natural rubber were vulcanized through a standard preparation. Some compounds were also reinforced with carbon black and the vulcanization kinetics were monitored through rheometer. Experimental results indicate that there exists an optimal concentration of waste such that post-tanning dyeing post-tanning and chrome shaving are suitable for manufacture floor mats, soles and heels while oil-tanning waste can be used for making hose or conveyor belts. The mechanical performances of the articles prepared by direct mixing with leather waste are the same as those of commercially distributed rubber products. Full article

(This article belongs to the Section Environmental Sciences)

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20 pages, 2241 KiB

Open AccessArticle

Spectroscopic Characterization of Iron Slags from the Archaeological Sites of Brâncoveneşti, Călugăreni and Vătava Located on the Mureş County (Romania) Sector of the Roman Limes

by Enikő Bitay, Irina Kacsó, Claudiu Tănăselia, Dana Toloman, Gheorghe Borodi, Szilamér-Péter Pánczél, Zsombor Kisfaludi-Bak and Erzsébet Veress

Appl. Sci. 2020, 10(15), 5373; https://doi.org/10.3390/app10155373 - 04 Aug 2020

Cited by 6 | Viewed by 2237

Abstract

Iron slag samples unearthed from archaeological sites lying on the Eastern limes sector of Roman Dacia (the Brâncoveneşti and Călugăreni auxiliary forts and the Vătava watchtower) were studied in order to assess the probability of local iron working (smelting and smithing) during the [...] Read more.

Iron slag samples unearthed from archaeological sites lying on the Eastern limes sector of Roman Dacia (the Brâncoveneşti and Călugăreni auxiliary forts and the Vătava watchtower) were studied in order to assess the probability of local iron working (smelting and smithing) during the 2nd–3rd centuries CE. Structural-mineralogic aspects revealed by PXRD analysis and FTIR spectroscopy indicate different slag types corresponding to different iron production and processing stages allowing the supposition that refining of the bloom and processing of the refined iron took place on the sites. The FTIR absorption bands obtained in the spectral domain 2000–400 cm⁻¹ show that mineralogically the samples are constituted mainly of silicates associated with minor quantities of aluminates and carbonates. The fayalite, haematite, and magnetite phases appearing on both the X-ray diffractograms and the FTIR spectra agree with the redox conditions of the slag formation process which result from the Fe³⁺/Fe²⁺ ratio determined using the EPR-method. The bulk macro-elemental PXRF and ICP-MS spectroscopy data support the slag typization proposed on the basis of the probable working conditions; trace-elemental bulk composition suggests that the provenance of the raw materials may be different. Full article

(This article belongs to the Section Chemical and Molecular Sciences)

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17 pages, 401 KiB

Open AccessArticle

Can Defect Prediction Be Useful for Coarse-Level Tasks of Software Testing?

by Can Cui, Bin Liu, Peng Xiao and Shihai Wang

Appl. Sci. 2020, 10(15), 5372; https://doi.org/10.3390/app10155372 - 04 Aug 2020

Cited by 2 | Viewed by 2041

Abstract

It is popular to use software defect prediction (SDP) techniques to predict bugs in software in the past 20 years. Before conducting software testing (ST), the result of SDP assists on resource allocation for ST. However, DP usually works on fine-level tasks (or [...] Read more.

It is popular to use software defect prediction (SDP) techniques to predict bugs in software in the past 20 years. Before conducting software testing (ST), the result of SDP assists on resource allocation for ST. However, DP usually works on fine-level tasks (or white-box testing) instead of coarse-level tasks (or black-box testing). Before ST or without historical execution information, it is difficult to get resource allocated properly. Therefore, a SDP-based approach, named DPAHM, is proposed to assist on arranging resource for coarse-level tasks. The method combines analytic hierarchy process (AHP) and variant incidence matrix. Besides, we apply the proposed DPAHM into a proprietary software, named MC. Besides, we conduct an up-to-down structure, including three layers for MC. Additionally, the performance measure of each layer is calculated based on the SDP result. Therefore, the resource allocation strategy for coarse-level tasks is gained according to the prediction result. The experiment indicates our proposed method is effective for resource allocation of coarse-level tasks before executing ST. Full article

(This article belongs to the Section Computing and Artificial Intelligence)

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18 pages, 1606 KiB

Open AccessArticle

Improvement of an Online Education Model with the Integration of Machine Learning and Data Analysis in an LMS

by William Villegas-Ch, Milton Román-Cañizares and Xavier Palacios-Pacheco

Appl. Sci. 2020, 10(15), 5371; https://doi.org/10.3390/app10155371 - 04 Aug 2020

Cited by 76 | Viewed by 11045

Abstract

The events that took place in the year 2020 have shown us that society is still fragile and that it is exposed to events that rapidly change the paradigms that govern it. This has been shown by a pandemic like Coronavirus disease 2019; [...] Read more.

The events that took place in the year 2020 have shown us that society is still fragile and that it is exposed to events that rapidly change the paradigms that govern it. This has been shown by a pandemic like Coronavirus disease 2019; this global emergency has changed the way people interact, communicate, study, or work. In short, the way in which society carries out all activities has changed. This includes education, which has bet on the use of information and communication technologies to reach students. An example of the aforementioned is the use of learning management systems, which have become ideal environments for resource management and the development of activities. This work proposes the integration of technologies, such as artificial intelligence and data analysis, with learning management systems in order to improve learning. This objective is outlined in a new normality that seeks robust educational models, where certain activities are carried out in an online mode, surrounded by technologies that allow students to have virtual assistants to guide them in their learning. Full article

(This article belongs to the Special Issue Emerging Artificial Intelligence (AI) Technologies for Learning)

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10 pages, 846 KiB

Open AccessArticle

Application of Artificial Neural Network for Modeling and Studying In Vitro Genotype-Independent Shoot Regeneration in Wheat

by Mohsen Hesami, Jorge A. Condori-Apfata, Maria Valderrama Valencia and Mohsen Mohammadi

Appl. Sci. 2020, 10(15), 5370; https://doi.org/10.3390/app10155370 - 04 Aug 2020

Cited by 40 | Viewed by 4122

Abstract

Optimizing in vitro shoot regeneration conditions in wheat is one of the important steps in successful micropropagation and gene transformation. Various factors such as genotypes, explants, and phytohormones affect in vitro regeneration of wheat, hindering the ability to tailor genotype-independent protocols. Novel computational [...] Read more.

Optimizing in vitro shoot regeneration conditions in wheat is one of the important steps in successful micropropagation and gene transformation. Various factors such as genotypes, explants, and phytohormones affect in vitro regeneration of wheat, hindering the ability to tailor genotype-independent protocols. Novel computational approaches such as artificial neural networks (ANNs) can facilitate modeling and predicting outcomes of tissue culture experiments and thereby reduce large experimental treatments and combinations. In this study, generalized regression neural network (GRNN) were used to model and forecast in vitro shoot regeneration outcomes of wheat on the basis of 10 factors including genotypes, explants, and different concentrations of 6-benzylaminopurine (BAP), kinetin (Kin), 2,4-dichlorophenoxyacetic acid (2,4-D), indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), 1-naphthaleneacetic acid (NAA), zeatin, and CuSO₄. In addition, GRNN was linked to a genetic algorithm (GA) to identify an optimized solution for maximum shoot regeneration. Results indicated that GRNN could accurately predict the shoot regeneration frequency in the validation set with a coefficient determination of 0.78. Sensitivity analysis demonstrated that shoot regeneration frequency was more sensitive to variables in the order of 2,4-D > explant > genotype < zeatin < NAA. Results of this study suggest that GRNN-GA can be used as a tool, besides experimental approaches, to develop and optimize in vitro genotype-independent regeneration protocols. Full article

(This article belongs to the Section Computing and Artificial Intelligence)

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9 pages, 1982 KiB

Open AccessArticle

Evaluation of the Effect of Freezing and Gamma Irradiation on Different Types of Tendon Allografts by DIC Assisted Tensile Testing

by Dénes Faragó, Gábor Szebényi, Tamás Temesi, Rita Mária Kiss and Károly Pap

Appl. Sci. 2020, 10(15), 5369; https://doi.org/10.3390/app10155369 - 04 Aug 2020

Cited by 2 | Viewed by 2182

Abstract

This study aimed to evaluate the changes in the endurance properties of four types of tendons caused by freezing and gamma irradiation. Four types of grafts were harvested: quadriceps, semitendinosus + gracilis, tibialis anterior, and peroneus longus. These were put into three groups: [...] Read more.

This study aimed to evaluate the changes in the endurance properties of four types of tendons caused by freezing and gamma irradiation. Four types of grafts were harvested: quadriceps, semitendinosus + gracilis, tibialis anterior, and peroneus longus. These were put into three groups: Group A was the control group, tested without freezing or irradiation. Grafts in Group B were frozen and irradiated (target dose: 21 kGy), while grafts in Group C were again frozen and irradiated (target dose: 42 kGy). Maximum load, tensile modulus, tensile strength, strain at maximum force and fracture strain were calculated from the force-elongation graphs of cyclic load tests. The higher gamma irradiation dose (Group C) significantly decreased the strains at tensile strength of the quadriceps tendons (p = 0.0004–0.0237), compared to the other two groups. In the case of the quadricep tendons (p = 0.0151), there is a significant decrease in Young’s modulus after gamma irradiation with the dose of 42 kGy. According to the results of the study, the tibialis anterior and the peroneus longus are recommended in ACL reconstruction when gamma irradiation is required, while quadricep tendons, which are usually used for an autograph, are not suitable for allograft reconstruction after gamma irradiation from the viewpoint of mechanical properties. Full article

(This article belongs to the Section Applied Biosciences and Bioengineering)

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16 pages, 1259 KiB

Open AccessReview

Selenium Deficiency—From Soil to Thyroid Cancer

by Latifa Sarra Kazi Tani, Nouria Dennouni-Medjati, Benoit Toubhans and Laurent Charlet

Appl. Sci. 2020, 10(15), 5368; https://doi.org/10.3390/app10155368 - 04 Aug 2020

Cited by 10 | Viewed by 4331

Abstract

Selenium (Se) is an essential micronutrient present in human diet, entering in the composition of selenoproteins as selenocysteine (Se-Cys) amino acid. At the thyroid level, these proteins play an important role as antioxidant and in hormone metabolism. Selenoproteins are essential for the balance [...] Read more.

Selenium (Se) is an essential micronutrient present in human diet, entering in the composition of selenoproteins as selenocysteine (Se-Cys) amino acid. At the thyroid level, these proteins play an important role as antioxidant and in hormone metabolism. Selenoproteins are essential for the balance of redox homeostasis and antioxidant defense of mammalian organisms, while the corresponding imbalance is now recognized as the cause of many diseases including cancer. The food chain is the main source of Se in human body. Dietary intake is strongly correlated with Se content in soil and varies according to several factors such as geology and atmospheric input. Both Se deficiency and toxicity have been associated with adverse health effects. This review synthesizes recent data on the transfer of Se from soil to humans, Se U-shaped deficiency and toxicity uptake effects and particularly the impact of Se deficiency on thyroid cancer. Full article

(This article belongs to the Special Issue Selenium: Properties and Sources in the Food Industry)

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23 pages, 18839 KiB

Open AccessArticle

Dynamic Behavior of Steel and Composite Ferry Subjected to Transverse Eccentric Moving Load Using Finite Element Analysis

by Mohamed N. Lotfy, Yasser A. Khalifa, Abdelrahim K. Dessouki and Elsayed Fathallah

Appl. Sci. 2020, 10(15), 5367; https://doi.org/10.3390/app10155367 - 03 Aug 2020

Cited by 6 | Viewed by 3290

Abstract

The most important problems confronted by designers of floating structures are minimizing weight and increasing payload to get proper resistance to the applied loads. In the present study, the structural performance of a ferry is analyzed using both metallic and composite materials as [...] Read more.

The most important problems confronted by designers of floating structures are minimizing weight and increasing payload to get proper resistance to the applied loads. In the present study, the structural performance of a ferry is analyzed using both metallic and composite materials as a result of the dynamic load of the Military Load Capacity (MLC) 70 (tank load). The model is composed of sixteen floating pontoons. Finite element simulation and dynamic analysis were performed using ANSYS software (analysis system software), considering a moving MLC70 (tank load). Both concentric and eccentric cases of loading are considered. Draft, deformation, and stresses are obtained and investigated. For the steel ferry, the von-Mises stresses are investigated, while for the composite ferry, the maximum principal stresses are investigated. Furthermore, buckling analysis is performed on the composite ferry and the buckling load factor is determined. The results of the dynamic analysis illustrated that the transverse eccentricity of the moving tank MLC70 must not exceed 0.5 m for a steel ferry while it may reach up to 1.5 m for the composite ferry. This research can also be a useful tool in the design of floating composite and steel ferries. Full article

(This article belongs to the Section Marine Science and Engineering)

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15 pages, 785 KiB

Open AccessArticle

A Constant Round Write-Only ORAM

by Bo Zhao, Zhihong Chen, Hai Lin and XiangMin Ji

Appl. Sci. 2020, 10(15), 5366; https://doi.org/10.3390/app10155366 - 03 Aug 2020

Viewed by 1804

Abstract

The write-only oblivious RAM (ORAM) is proposed to efficiently protect the privacy of applications such as cloud storage synchronization and encrypted hidden volumes. For N blocks with size B = Ω(log²N), the most efficient write-only ORAM, DetWoORAM, achieves O [...] Read more.

The write-only oblivious RAM (ORAM) is proposed to efficiently protect the privacy of applications such as cloud storage synchronization and encrypted hidden volumes. For N blocks with size B = Ω(log²N), the most efficient write-only ORAM, DetWoORAM, achieves O(B) communication complexity with O(logN) rounds per logical write. We propose a two-level write-only ORAM and achieve O(B) communication complexity with O(1) rounds. Similar to the traditional bucket-based ORAM schemes, we set a rate for the write operation to further reduce the communication complexity. The top-level stores data blocks in a flat array and the write pattern is protected by writing blocks uniformly at random. The second level employs a binary tree to store the position map of data blocks. To avoid recursive storage, a static position map for blocks in the second level is used. Both the analysis and experiments show that, besides the achieved low communication complexity and rounds, the stash sizes in the top level and the second level are bounded to O(B) and ω(B), respectively. Full article

(This article belongs to the Section Electrical, Electronics and Communications Engineering)

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