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Volume 11
Issue 7
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Appl. Sci., Volume 11, Issue 7 (April-1 2021) – 409 articles

Cover Story (view full-size image): Wireless body area networks (WBANs) are a subset of wireless sensor networks (WSNs) with unique challenges due to mobility and over-the-body radio propagation. This work presents an empirical performance analysis of several WBAN channels that is based on the receiver signal strength indicator (RSSI) and packet reception rate (PRR) metrics. Using real hardware nodes, this article characterizes four different physical activities—standing, sitting, cycling and walking—evaluating the effect of the frequency band, transmit power and node placement for several human subjects. This analysis confirms the theoretical notions of path attenuation and serves as a benchmark for the design of future algorithms. View this paper.
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18 pages, 2587 KiB  
Article
Mathematical Modeling of the Manufacturing Sector’s Dominant Part as a Base for Automation
by Elena Grešová and Jozef Svetlík
Appl. Sci. 2021, 11(7), 3295; https://doi.org/10.3390/app11073295 - 6 Apr 2021
Cited by 6 | Viewed by 2770
Abstract
The current great expansion of automation and robotics affects a multiplicity of various fields. A prominent example is industry, where the different manufacturing processes and technologies embrace a certain level of automation and robotics. Thus, the use of robotics and automation implementation is [...] Read more.
The current great expansion of automation and robotics affects a multiplicity of various fields. A prominent example is industry, where the different manufacturing processes and technologies embrace a certain level of automation and robotics. Thus, the use of robotics and automation implementation is part of a rapidly rising trend in industry. The presented paper deals with the manufacturing segment in the context of automation. The main subject is data analysis, with our own subsequent model building and final realization of the prediction corresponding to the machinery and electrical machinery sector as a highly relevant automation driver through the use of mathematical modeling. The design of the model is accompanied by optimization of the particular weights. Determination of the most suitable model is preceded by creating and testing a number of models to decide upon the final one. The construction of the mathematical model pursues the aim of making predictions relating to the machinery and electrical machinery sector for the specific national economy as the concluding investigation step. We apply a polynomial approximation as the research method. The software selected for our purposes is Matlab. Full article
(This article belongs to the Special Issue Trends in Modeling and Simulation of Production Processes and Systems)
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14 pages, 6883 KiB  
Article
Statistical Evaluation of Quantities Measured in the Detection of Soil Air Pollution of the Environmental Burden
by Erika Skvarekova, Marcela Tausova, Andrea Senova, Gabriel Wittenberger and Jana Novakova
Appl. Sci. 2021, 11(7), 3294; https://doi.org/10.3390/app11073294 - 6 Apr 2021
Cited by 10 | Viewed by 2443
Abstract
The article highlights the investigation of the relationships between measured quantities during the atmospheric geochemical survey of contaminated soil and the environmental burden of the industrial establishment in eastern Slovakia. Statistical data processing was undertaken from the measured values of pollutants. The basic [...] Read more.
The article highlights the investigation of the relationships between measured quantities during the atmospheric geochemical survey of contaminated soil and the environmental burden of the industrial establishment in eastern Slovakia. Statistical data processing was undertaken from the measured values of pollutants. The basic statistical characteristics of the monitored indicators were defined here. With the help of regressive and correlative analysis, dependency was confirmed between examined values, further expressed by a mathematical relationship. We analysed variability of the measured variables due to the influence of changed input quantities by the non-parametric Wilcox test. The statistical data processing helps us to identify the dependency between the measured values and improves valorization of the pollution of a given environmental burden. This was due to the handling of organic pollutants and the production of basic organic and inorganic chemicals stated for other industries. Chemical analysis of soil air helps us to determine the extent and amount of soil contamination by pollutants. Individual pollutants have their own characteristic properties and their negative effects on biota, the environment and humans are different. Full article
(This article belongs to the Special Issue Environmental Chemical: Pollution, Analysis and Restoration)
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20 pages, 1347 KiB  
Review
L-Citrulline: A Non-Essential Amino Acid with Important Roles in Human Health
by Encarna Aguayo, Ascensión Martínez-Sánchez, Bárbara Fernández-Lobato and Fernando Alacid
Appl. Sci. 2021, 11(7), 3293; https://doi.org/10.3390/app11073293 - 6 Apr 2021
Cited by 42 | Viewed by 27045
Abstract
L-Arginine (Arg) has been widely used due to its functional properties as a substrate for nitric oxide (NO) generation. However, L-citrulline (CIT), whose main natural source is watermelon, is a non-essential amino acid but which has important health potential. This review provides a [...] Read more.
L-Arginine (Arg) has been widely used due to its functional properties as a substrate for nitric oxide (NO) generation. However, L-citrulline (CIT), whose main natural source is watermelon, is a non-essential amino acid but which has important health potential. This review provides a comprehensive approach to different studies of the endogenous synthesis of CIT, metabolism, pharmacokinetics, and pharmacodynamics as well as its ergogenic effect in exercise performance. The novel aspect of this paper focuses on the different effects of CIT, citrulline malate and CIT from natural sources such as watermelon on several topics, including cardiovascular diseases, diabetes, erectile dysfunction, cancer, and exercise performance. CIT from watermelon could be a natural food-sourced substitute for pharmacological products and therefore the consumption of this fruit is promoted. Full article
(This article belongs to the Special Issue Functional Foods and Human Health)
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16 pages, 2986 KiB  
Article
Performance Evaluation of Buried Concrete Pipe Considering Soil Pressure and Crack Propagation Using 3D Finite Element Analysis
by Hoki Ban, Seungjun Roh and Won-Jun Park
Appl. Sci. 2021, 11(7), 3292; https://doi.org/10.3390/app11073292 - 6 Apr 2021
Cited by 6 | Viewed by 3029
Abstract
Numerous factors affect the soil pressure distributions around buried pipes, including the shape, size, and stiffness of the pipe, burial depth, and the stiffness of the surrounding soil. Additionally, to some extent, a pipe can benefit from the soil arching effect, where the [...] Read more.
Numerous factors affect the soil pressure distributions around buried pipes, including the shape, size, and stiffness of the pipe, burial depth, and the stiffness of the surrounding soil. Additionally, to some extent, a pipe can benefit from the soil arching effect, where the overburden and surcharge pressure at the crown can be supported by the adjacent soil. As a result, a buried pipe only needs to support the portion of the load that is not transferred to the adjacent soil. This paper presents numerical investigations of the soil pressure distributions around buried concrete pipes and crack propagation under different environmental conditions, such as loading, saturation level, and the presence of voids. To this end, a nonlinear elastoplastic model for backfill materials was implemented using finite element software and a user-defined subroutine. Three different backfill materials and two different native soils were selected to examine the material-specific behaviors of concrete pipes, including soil pressure distributions and crack propagation. For each backfill material, the effects of the loading type, groundwater, and voids were investigated. These simulation results provide helpful information regarding pressure redistribution and buried concrete pipe behavior under various environmental conditions. Full article
(This article belongs to the Special Issue Toward Sustainable Engineering Structures for Better Safety in Built-Environment)
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15 pages, 1559 KiB  
Article
Bioactive Properties of Breads Made with Sourdough of Hull-Less Barley or Conventional and Pigmented Wheat Flours
by Simone Luti, Viola Galli, Manuel Venturi, Lisa Granchi, Paolo Paoli and Luigia Pazzagli
Appl. Sci. 2021, 11(7), 3291; https://doi.org/10.3390/app11073291 - 6 Apr 2021
Cited by 10 | Viewed by 2688
Abstract
Functional and nutritional properties of baked goods can be enhanced by the use of sourdough fermentation, which is defined as a mixture of water and flour fermented by lactobacilli (LAB) and yeasts. Previous data highlighted the ability of sourdoughs obtained with selected LAB [...] Read more.
Functional and nutritional properties of baked goods can be enhanced by the use of sourdough fermentation, which is defined as a mixture of water and flour fermented by lactobacilli (LAB) and yeasts. Previous data highlighted the ability of sourdoughs obtained with selected LAB strains and commercial flour to produce bioactive peptides equipped with antioxidant and anti-inflammatory properties. More recently, it has been proven that choosing the most suitable combination of selected LAB and high-functional-value flours greatly increase the amount of low-molecular-weight antioxidant compounds responsible for improving the nutritional value of the products. This work aimed to isolate bioactive peptides both from sourdoughs and baked breads obtained with pigmented wheat and barley and a selected combination of LABs. Soluble water extracts were obtained, and low-molecular-weight peptides were isolated. Antioxidant activity was detected by assaying the intracellular ROS production in stressed cultured macrophages, treated with peptides. Moreover, anti-inflammatory activity, highlighted by NFkB pathway inhibition and by COX2 reduction in stressed cells, was demonstrated for peptides obtained from breads. The results allowed the conclusion that the combination of flours and LAB used in the present manuscript led to the production of bakery products with beneficial effects on oxidative and inflammatory status. Full article
(This article belongs to the Special Issue Bioactive Peptides from Foods)
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16 pages, 45148 KiB  
Article
The Cognition of Audience to Artistic Style Transfer
by Yanru Lyu, Chih-Long Lin, Po-Hsien Lin and Rungtai Lin
Appl. Sci. 2021, 11(7), 3290; https://doi.org/10.3390/app11073290 - 6 Apr 2021
Cited by 11 | Viewed by 5029
Abstract
Artificial Intelligence (AI) is becoming more popular in various fields, including the area of art creation. Advances in AI technology bring new opportunities and challenges in the creation, experience, and appreciation of art. The neural style transfer (NST) realizes the intelligent conversion of [...] Read more.
Artificial Intelligence (AI) is becoming more popular in various fields, including the area of art creation. Advances in AI technology bring new opportunities and challenges in the creation, experience, and appreciation of art. The neural style transfer (NST) realizes the intelligent conversion of any artistic style using neural networks. However, the artistic style is the product of cognition that involving from visual to feel. The purpose of this paper is to study factors affecting audience cognitive difference and preference on artistic style transfer. Those factors are discussed to investigate the application of the AI generator model in art creation. Therefore, based on the artist’s encoding attributes (color, stroke, texture) and the audience’s decoding cognitive levels (technical, semantic, effectiveness), this study proposed a framework to evaluate artistic style transfer in the perspective of cognition. Thirty-one subjects with a background in art, aesthetics, and design were recruited to participate in the experiment. The experimental process consists of four style groups, including Fauvism, Expressionism, Cubism, and Renaissance. According to the finding in this study, participants can still recognize different artistic styles after transferred by neural networks. Besides, the features of texture and stroke are more impact on the perception of fitness than color. The audience may prefer the samples with high cognition in the semantic and effectiveness levels. The above indicates that through AI automated routine work, the cognition of the audience to artistic style still can be kept and transferred. Full article
(This article belongs to the Special Issue User Experience for Advanced Human–Computer Interaction)
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15 pages, 54614 KiB  
Article
Bearing Fault Diagnosis Approach under Data Quality Issues
by Ashraf AlShalalfeh and Laith Shalalfeh
Appl. Sci. 2021, 11(7), 3289; https://doi.org/10.3390/app11073289 - 6 Apr 2021
Cited by 9 | Viewed by 3764
Abstract
In rotary machinery, bearings are susceptible to different types of mechanical faults, including ball, inner race, and outer race faults. In condition-based monitoring (CBM), several techniques have been proposed in fault diagnostics based on the vibration measurements. For this paper, we studied the [...] Read more.
In rotary machinery, bearings are susceptible to different types of mechanical faults, including ball, inner race, and outer race faults. In condition-based monitoring (CBM), several techniques have been proposed in fault diagnostics based on the vibration measurements. For this paper, we studied the fractal characteristics of non-stationary vibration signals collected from bearings under different health conditions. Using the detrended fluctuation analysis (DFA), we proposed a novel method to diagnose the bearing faults based on the scaling exponent (α1) of vibration signal at the short-time scale. In vibration data with high sampling rate, our results showed that the proposed measure, scaling exponent, provides an accurate identification of the health state of the bearing. At the end, we evaluated the performance of the proposed method under different data quality issues, data loss and induced noise. Full article
(This article belongs to the Special Issue Diagnostics of Rotating Machinery through Vibration Monitoring: Signal Processing and Pattern Analysis)
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14 pages, 3518 KiB  
Article
Performance Evaluation of Stewart-Gough Flight Simulator Based on L1 Adaptive Control
by Jiangwei Zhao, Dongsu Wu and Hongbin Gu
Appl. Sci. 2021, 11(7), 3288; https://doi.org/10.3390/app11073288 - 6 Apr 2021
Cited by 2 | Viewed by 2271
Abstract
In the design of the six degrees of freedom (6-DOF) flight simulation system, the unmodeled dynamic, transient performance and steady-state performance of the system are generally concerned. Considering that the model of flight simulation system is highly nonlinear and requires high response speed [...] Read more.
In the design of the six degrees of freedom (6-DOF) flight simulation system, the unmodeled dynamic, transient performance and steady-state performance of the system are generally concerned. Considering that the model of flight simulation system is highly nonlinear and requires high response speed and high stability, this paper applies L1 adaptive controller to the control of flight simulation platform. The controller has a low-pass filter in feedback loop to avoid high frequencies in the control signals, and the required transient performance can be enhanced by increasing the adaptive gain, which can improve the transient, stability, and smoothness of the flight simulator platform. The performance of the L1 adaptive controller is obtained by comparison with the traditional model reference adaptive controller (MRAC). In addition to maintaining the good transient response of MRAC, the L1 adaptive controller improves the stability of the system. The output amplitude of the actuator is reduced by 39.95%, which effectively reduces the performance requirements of the actuator. Some additional experimental evaluations are carried out to show the performance of the controller. Full article
(This article belongs to the Section Aerospace Science and Engineering)
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10 pages, 566 KiB  
Article
Biology of Drug-Induced Gingival Hyperplasia: In Vitro Study of the Effect of Nifedipine on Human Fibroblasts
by Dorina Lauritano, Giulia Moreo, Fedora Della Vella, Annalisa Palmieri, Francesco Carinci and Massimo Petruzzi
Appl. Sci. 2021, 11(7), 3287; https://doi.org/10.3390/app11073287 - 6 Apr 2021
Cited by 31 | Viewed by 2951
Abstract
Background: It has been proven that the antihypertensive agent nifedipine can cause gingival overgrowth as a side effect. The aim of this study was to analyze the effects of pharmacological treatment with nifedipine on human gingival fibroblasts activity, investigating the possible pathogenetic mechanisms [...] Read more.
Background: It has been proven that the antihypertensive agent nifedipine can cause gingival overgrowth as a side effect. The aim of this study was to analyze the effects of pharmacological treatment with nifedipine on human gingival fibroblasts activity, investigating the possible pathogenetic mechanisms that lead to the onset of gingival enlargement. Methods: The expression profile of 57 genes belonging to the “Extracellular Matrix and Adhesion Molecules” pathway, fibroblasts’ viability at different drug concentrations, and E-cadherin levels in treated fibroblasts were assessed using real-time Polymerase Chain Reaction, PrestoBlue™ cell viability test, and an enzyme-linked immunoassay (ELISA), respectively. Results: Metalloproteinase 24 and 8 (MMP24, MMP8) showed significant upregulation in treated cells with respect to the control group, and cell adhesion gene CDH1 (E-cadherin) levels were recorded as increased in treated fibroblasts using both real-time PCR and ELISA. Downregulation was observed for transmembrane receptors ITGA6 and ITGB4, the basement membrane constituent LAMA1 and LAMB1, and the extracellular matrix protease MMP11, MMP16, and MMP26. Conclusions: The obtained data suggested that the pathogenesis of nifedipine-induced gingival overgrowth is characterized by an excessive accumulation of collagen due to the inhibition of collagen intracellular and extracellular degradation pathways. Full article
(This article belongs to the Special Issue Applied Sciences of Pharmacology in Dentistry)
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20 pages, 26354 KiB  
Article
Thermal Effects on the Drilling Performance of a Limestone: Relationships with Physical and Mechanical Properties
by Víctor Martínez-Ibáñez, María Elvira Garrido, Carlos Hidalgo Signes, Aniello Basco, Tiago Miranda and Roberto Tomás
Appl. Sci. 2021, 11(7), 3286; https://doi.org/10.3390/app11073286 - 6 Apr 2021
Cited by 9 | Viewed by 2974
Abstract
This work evaluates the effect of high temperatures and cooling methods on the drillability of Prada limestone. Samples from boreholes drilled during the design stage of the Tres Ponts Tunnel in the Catalan south Pyrenean zone (Spain) were subjected to temperatures of 105, [...] Read more.
This work evaluates the effect of high temperatures and cooling methods on the drillability of Prada limestone. Samples from boreholes drilled during the design stage of the Tres Ponts Tunnel in the Catalan south Pyrenean zone (Spain) were subjected to temperatures of 105, 200, 300, 400, and 600 °C, and then cooled at a slow rate or by quenching. Sievers’ J-value (SJ) and brittleness (S20) were determined on thermally treated samples, and the drilling rate index (DRI) was calculated for each temperature. The results show that thermal treatment implied a sustained increase in the drillability of the rock of up to 40% at 600 °C and a change in the drillability category (from medium to high). At 600 °C, SJ and S20 tripled and doubled, respectively, the initial values obtained for the intact rock. The results were inconclusive about the influence of the cooling method on the drilling performance of Prada limestone for the tested range of temperatures. The substantial improvement observed in the drillability of Prada limestone when heated, measured in terms of DRI, could help in the development of novel thermally-assisted mechanical excavation methods. Additionally, strong correlations between drillability variables (i.e., SJ and S20) and physical and mechanical variables of Prada limestone (i.e., P- and S-wave velocities, uniaxial compression strength, elastic modulus, and Poisson’s ratio) are proposed. Correlations will help make preliminary predictions of drillability based on properties such as uniaxial compression strength and ultrasound wave velocities. Full article
(This article belongs to the Special Issue Effects of Temperature on Rock and Rock Masses)
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11 pages, 2736 KiB  
Article
A Deep Multi-Frame Super-Resolution Network for Dynamic Scenes
by Ze Pan, Zheng Tan and Qunbo Lv
Appl. Sci. 2021, 11(7), 3285; https://doi.org/10.3390/app11073285 - 6 Apr 2021
Cited by 2 | Viewed by 2932
Abstract
The multi-frame super-resolution techniques have been prosperous over the past two decades. However, little attention has been paid to the combination of deep learning and multi-frame super-resolution. One reason is that most deep learning-based super-resolution methods cannot handle variant numbers of input frames. [...] Read more.
The multi-frame super-resolution techniques have been prosperous over the past two decades. However, little attention has been paid to the combination of deep learning and multi-frame super-resolution. One reason is that most deep learning-based super-resolution methods cannot handle variant numbers of input frames. Another reason is that it is hard to capture accurate temporal and spatial information because of the misalignment of input images. To solve these problems, we propose an optical-flow-based multi-frame super-resolution framework, which is capable of dealing with various numbers of input frames. This framework enables to make full use of the input frames, allowing it to obtain better performance. In addition, we use a spatial subpixel alignment module for more accurate subpixel-wise spatial alignment and introduce a dual weighting module to generate weights for temporal fusion. Both two modules lead to more effective and accurate temporal fusion. We compare our method with other state-of-the-art methods and conduct ablation studies on our method. The results of qualitative and quantitative analyses show that our method achieves state-of-the-art performances, demonstrating the advantage of the designed framework and the necessity of proposed modules. Full article
(This article belongs to the Special Issue Signal, Image and Video Processing)
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16 pages, 18735 KiB  
Article
Selective Use of Corn Crop Residues: Energy Viability
by M. T. Miranda, R. García-Mateos, J. I. Arranz, F. J. Sepúlveda, P. Romero and A. Botet-Jiménez
Appl. Sci. 2021, 11(7), 3284; https://doi.org/10.3390/app11073284 - 6 Apr 2021
Cited by 5 | Viewed by 4000
Abstract
The corn crop is one of the most important crops worldwide. However, the management of the residues generated is not efficient enough, which diminishes the competitiveness of this crop. An interesting option for the valorization of these wastes is their thermal use. In [...] Read more.
The corn crop is one of the most important crops worldwide. However, the management of the residues generated is not efficient enough, which diminishes the competitiveness of this crop. An interesting option for the valorization of these wastes is their thermal use. In order to make the management of this residue as much efficient as possible, it is vital to know the different processes related to a corn harvest, and try to adapt the use of this waste depending on its characteristics. Thus, in this work, and on the basis of a conventional corn harvest, a differentiated analysis of the residue generated was carried out, including its characterization and assessing its behavior during pyrolysis and combustion. The results pointed out the importance of collecting residue immediately after its generation and avoiding its contact with the soil as this factor tends to worsen its thermal properties and ash content. Concerning the selective collection, it is highly advisable if the subsequent thermal use is going to be a pyrolytic process. In the case of combustion, even though the samples that contain corn stalk showed better combustion properties, this improvement did not outweigh the adverse effects related to the increase in ash content, especially for its pelletizing. Full article
(This article belongs to the Special Issue Biofuels from Waste Biomass)
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13 pages, 8079 KiB  
Article
Finite Element Analysis on Block Shear Mechanism of Lean Duplex Stainless Steel Welded Connections
by YongHyun Cho, Dong-Keon Kim, JunSu Kim and TaeSoo Kim
Appl. Sci. 2021, 11(7), 3283; https://doi.org/10.3390/app11073283 - 6 Apr 2021
Cited by 4 | Viewed by 2287
Abstract
The block shear equations specified in the current AISC specification for structural steel buildings and North American cold-formed steel design specifications are based on research results of carbon steel bolted connections. These equations were found to be inapplicable for the welded connections in [...] Read more.
The block shear equations specified in the current AISC specification for structural steel buildings and North American cold-formed steel design specifications are based on research results of carbon steel bolted connections. These equations were found to be inapplicable for the welded connections in the literature. This issue is primarily associated with the use of the incorrect assumption on block shear failure mechanism. The present paper examines the accuracy of various block shear equations available in the design specifications and in the literature. The paper also examines the shear hardening capacity and the level of tensile stress over the critical net area with the results of finite element analysis, in which the fracture simulation is considered. It shows that the block shear capacities of lean duplex stainless steel welded connections can be predicted accurately using tensile stress equal to 1.25Fu, as proposed in the literature. Full article
(This article belongs to the Section Civil Engineering)
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21 pages, 5366 KiB  
Article
Dynamic Response Analysis of a Thin Plate with Partially Constrained Layer Damping Optimization under Moving Loads for Various Boundary Conditions
by Yun Qin, Qinghua Song, Zhanqiang Liu and Jiahao Shi
Appl. Sci. 2021, 11(7), 3282; https://doi.org/10.3390/app11073282 - 6 Apr 2021
Cited by 1 | Viewed by 2289
Abstract
In this paper, the vibration analysis of a partially constrained layer damping plate subjected to moving loads is investigated. In addition, the first four order damping loss factor of the system is optimized with the location of partially constrained layer damping as a [...] Read more.
In this paper, the vibration analysis of a partially constrained layer damping plate subjected to moving loads is investigated. In addition, the first four order damping loss factor of the system is optimized with the location of partially constrained layer damping as a design variable. The equations of motion of a partially constrained layer damping plate are derived through the Lagrange equation based on first order shear deformation theory (FSDT). Next, using an extended Rayleigh–Ritz solution together with the penalty method expresses the unknown displacement terms, and the differential quadrature method is proposed to obtain the dynamic response of the system in the time domain. A multi-population genetic algorithm (MPGA) is employed to deal with the optimization of the damping loss factor of a partially constrained layer damping plate. To ensure the accuracy of the method presented in this study, the numerical results are comprehensively verified by experiments and open literature. The optimization results show that the damping loss factor increases when the position of the patch is close to the constraint boundary, and the best strategy is to optimize the low order damping loss factor of the system under moving loads. It is believed that the research results are of interest to engineering science. Full article
(This article belongs to the Section Mechanical Engineering)
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49 pages, 4342 KiB  
Article
Primary and Secondary Environmental Effects Triggered by the 30 October 2020, Mw = 7.0, Samos (Eastern Aegean Sea, Greece) Earthquake Based on Post-Event Field Surveys and InSAR Analysis
by Spyridon Mavroulis, Ioanna Triantafyllou, Andreas Karavias, Marilia Gogou, Katerina-Navsika Katsetsiadou, Efthymios Lekkas, Gerassimos A. Papadopoulos and Issaak Parcharidis
Appl. Sci. 2021, 11(7), 3281; https://doi.org/10.3390/app11073281 - 6 Apr 2021
Cited by 17 | Viewed by 5999
Abstract
On 30 October 2020, an Mw = 7.0 earthquake struck the eastern Aegean Sea. It triggered earthquake environmental effects (EEEs) on Samos Island detected by field surveys, relevant questionnaires, and Interferometric Synthetic Aperture Radar (InSAR) analysis. The primary EEEs detected in the field [...] Read more.
On 30 October 2020, an Mw = 7.0 earthquake struck the eastern Aegean Sea. It triggered earthquake environmental effects (EEEs) on Samos Island detected by field surveys, relevant questionnaires, and Interferometric Synthetic Aperture Radar (InSAR) analysis. The primary EEEs detected in the field comprise coseismic uplift imprinted on rocky coasts and port facilities around Samos and coseismic surface ruptures in northern Samos. The secondary EEEs were mainly observed in northern Samos and include slope failures, liquefaction, hydrological anomalies, and ground cracks. With the contribution of the InSAR, subsidence was detected and slope movements were also identified in inaccessible areas. Moreover, the type of the surface deformation detected by InSAR is qualitatively identical to field observations. As regards the EEE distribution, effects were generated in all fault blocks. By applying the Environmental Seismic Intensity (ESI-07) scale, the maximum intensities were observed in northern Samos. Based on the results from the applied methods, it is suggested that the northern and northwestern parts of Samos constitute an almost 30-km-long coseismic deformation zone characterized by extensive primary and secondary EEEs. The surface projection of the causative offshore northern Samos fault points to this zone, indicating a depth–surface connection and revealing a significant role in the rupture propagation. Full article
(This article belongs to the Special Issue The Contribution of Geology and Geomatics to Seismic Hazard and Earthquake Engineering)
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10 pages, 1296 KiB  
Article
Stability of Bituminous Emulsion Induced by Waste Based Bio-Surfactant
by Michele Porto, Paolino Caputo, Abraham A. Abe, Valeria Loise and Cesare Oliviero Rossi
Appl. Sci. 2021, 11(7), 3280; https://doi.org/10.3390/app11073280 - 6 Apr 2021
Cited by 2 | Viewed by 3061
Abstract
In the asphalt industry, bituminous emulsions are widely used in road pavement operations and in building/construction processes such as cold mix asphalt and waterproofing processes, respectively. A very important fact to keep in mind is that not all types of bitumen are suitable [...] Read more.
In the asphalt industry, bituminous emulsions are widely used in road pavement operations and in building/construction processes such as cold mix asphalt and waterproofing processes, respectively. A very important fact to keep in mind is that not all types of bitumen are suitable for the realization of bituminous emulsions. This is largely due to the variation in their chemical nature and the different cracking processes carried out on the bitumen during the fractional distillation process in the petroleum industry. The objective of this study is to identify the underlying causes of the non-emulsionability of bitumen using Nuclear Magnetic Resonance (NMR) and Dynamic Shear Rheology (DSR) analysis. NMR analysis aims at identifying the fundamental chemical components that are responsible for the emulsionability of the bitumen binder and how important their role is in this phenomenon. On the other hand, the DSR analysis is aimed at determining if the rheological (viscoelastic) behavior of bitumen is implicated in its emulsionability. The indications gotten from the data produced by these techniques, enable us as soon as the analyzed bitumen is deemed non-emulsionable to identify what type of additive can be used to modify the bitumen and alleviate its non-emulsionability until a point where its chemical components become ideal for the realization of bituminous emulsions. In this research work, a model bitumen (labelled as Cimar) which is known for its excellently high emulsionability in the production of anionic bituminous emulsions was used as the reference sample. Two bitumens (labelled as Adriatica and Alma) which from preliminary testing were deemed non-emulsionable were alongside the additives selected and subjected to the aforementioned techniques for analysis on their emulsionability. The NMR data obtained allowed the identification of the chemical nature of the components of the analyzed bitumens and the design of the right additive which improves the bitumen and makes it suitable for the preparation of emulsions. In addition to these, a largely uncommon however effective method of acid number determination of bitumen gave indications on an underlying factor which largely influences the emulsionability of bitumen. An aliphatic and an aromatic surfactant were identified thanks to the spectroscopic findings in this study. Full article
(This article belongs to the Special Issue Asphalt Materials II)
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19 pages, 1954 KiB  
Review
Antimicrobials in Dentistry
by Rana Alkattan, Luis Rojo and Sanjukta Deb
Appl. Sci. 2021, 11(7), 3279; https://doi.org/10.3390/app11073279 - 6 Apr 2021
Cited by 8 | Viewed by 4184
Abstract
Dental caries (decay) is caused by pathogenic bacterial species, which afflicts nearly a third of the world’s population from early childhood to old age. Treatment of tooth decay often involves the use of filling materials to restore the cavity; however, if untreated, it [...] Read more.
Dental caries (decay) is caused by pathogenic bacterial species, which afflicts nearly a third of the world’s population from early childhood to old age. Treatment of tooth decay often involves the use of filling materials to restore the cavity; however, if untreated, it can cause pain, infection and eventually lead to tooth loss. Since the oral environment is colonised by many different microorganisms, bacterial biofilms can form on these filling materials, contributing to secondary caries that can eventually lead to the failure of the dental restoration. Thus, preventing the formation of bacterial biofilms is an important strategy in the management of caries, which has led to research enabling antimicrobial capabilities in dental materials. Materials and pharmaceutical sciences are in a continuous race against microbial resistance but are trying to balance between beneficial biota associated with the oral cavity, and, of course, avoiding a harmful effect on tissues is challenging. This has, therefore, stemmed a substantial interest in both preventive and restorative measures that would enable limiting the formation of secondary caries, oral microbial biofilms, and the retention of tooth mineral. Thus, innovative strategies are being explored and here we present a review with a focus on strategies that can inhibit or limit the formation of bacterial biofilms. Full article
(This article belongs to the Special Issue Advances in Antimicrobial Sustainable Polymers)
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13 pages, 20923 KiB  
Article
An Empirical Evaluation of Prediction by Partial Matching in Assembly Assistance Systems
by Arpad Gellert, Stefan-Alexandru Precup, Bogdan-Constantin Pirvu, Ugo Fiore, Constantin-Bala Zamfirescu and Francesco Palmieri
Appl. Sci. 2021, 11(7), 3278; https://doi.org/10.3390/app11073278 - 6 Apr 2021
Cited by 10 | Viewed by 2673
Abstract
Industrial assistive systems result from a multidisciplinary effort that integrates IoT (and Industrial IoT), Cognetics, and Artificial Intelligence. This paper evaluates the Prediction by Partial Matching algorithm as a component of an assembly assistance system that supports factory workers, by providing choices for [...] Read more.
Industrial assistive systems result from a multidisciplinary effort that integrates IoT (and Industrial IoT), Cognetics, and Artificial Intelligence. This paper evaluates the Prediction by Partial Matching algorithm as a component of an assembly assistance system that supports factory workers, by providing choices for the next manufacturing step. The evaluation of the proposed method was performed on datasets collected within an experiment involving trainees and experienced workers. The goal is to find out which method best suits the datasets in order to be integrated afterwards into our context-aware assistance system. The obtained results show that the Prediction by Partial Matching method presents a significant improvement with respect to the existing Markov predictors. Full article
(This article belongs to the Special Issue Data Mining Applications in Industry 4.0)
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11 pages, 1134 KiB  
Article
Comparison of Postural Stability and Regulation among Female Athletes from Different Sports
by Andreas Lauenroth, Lars Reinhardt, Stephan Schulze, Kevin G. Laudner, Karl-Stefan Delank and René Schwesig
Appl. Sci. 2021, 11(7), 3277; https://doi.org/10.3390/app11073277 - 6 Apr 2021
Cited by 4 | Viewed by 2811
Abstract
The aim of this study was to evaluate the postural regulation of female athletes who participate in different sports under normal and high-demand conditions. Fifty-nine female athletes were classified into four specific groups based on their individual sport, which included basketball (n [...] Read more.
The aim of this study was to evaluate the postural regulation of female athletes who participate in different sports under normal and high-demand conditions. Fifty-nine female athletes were classified into four specific groups based on their individual sport, which included basketball (n = 16), gymnastics (n = 10), ski jumping (n = 13), diving (n = 8), and one group of recreational athletes (n = 12). These groups were then compared using several posturographic tests under four bipedal conditions: eyes open or closed and on a stable surface or foam pad. While there were some differences between groups standing in the less demanding positions (stable surface), the higher demanding positions (unstable surface-foam pads) showed significant differences between the technical sports (ski jumping, diving, and gymnastics) and basketball and recreational athletes. Most (50%, 6/12) of significant differences were provided by sports. In contrast, the predictors age, weight, and height played only a minor role within the covariance analysis. The largest effect by sports was detected for the anterior-posterior weight distribution standing on foam pads with closed eyes (p = 0.015, ηp2 = 0.211). Ski jumping and recreational athletes showed the largest (p = 0.011) partial difference by sports for this parameter and test position. According to the parameters, the weight distribution index (WDI) was the variable with the most significant effects (50%, 6/12). These results provide coaches and athletes with a more sport specific view on postural regulation and potentially assist in identifying deficits to improve sports performance and reduce the risk of injury. Full article
(This article belongs to the Special Issue Diagnostic and Interventions in Team Sports)
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10 pages, 1095 KiB  
Article
A Corner-Highlighting Method for Ambient Occlusion
by Sukjun Park and Nakhoon Baek
Appl. Sci. 2021, 11(7), 3276; https://doi.org/10.3390/app11073276 - 6 Apr 2021
Cited by 1 | Viewed by 2872
Abstract
Graphical user experiences are now ubiquitous features, and therefore widespread. Specifically, the computer graphics field and the game industry have been continually favoring the ambient occlusion post-processing method for its superb indirect light approximation and its effectiveness. Nonetheless of its canonical performance, its [...] Read more.
Graphical user experiences are now ubiquitous features, and therefore widespread. Specifically, the computer graphics field and the game industry have been continually favoring the ambient occlusion post-processing method for its superb indirect light approximation and its effectiveness. Nonetheless of its canonical performance, its operation on non-occluded surfaces is often seen redundant and unfavorable. In this paper, we propose a new perspective to handle such issues by highlighting the corners where ambient occlusion is likely to occur. Potential illumination occlusions are highlighted by checking the corners of the surfaces in the screen-space. Our algorithm showed feasibility for renderers to avoid unwanted computations by achieving performance improvements of 15% to 28% acceleration, in comparison to the previous works. Full article
(This article belongs to the Collection Big Data Analysis and Visualization Ⅱ)
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19 pages, 11596 KiB  
Article
Experimental/Numerical Evaluation of Steel Trapezoidal Corrugated Infill Panels with an Opening
by Majid Yaseri Gilvaee and Massood Mofid
Appl. Sci. 2021, 11(7), 3275; https://doi.org/10.3390/app11073275 - 6 Apr 2021
Cited by 5 | Viewed by 2537
Abstract
This paper investigates the influence of an opening in the infill steel plate on the behavior of steel trapezoidal corrugated infill panels. Two specimens of steel trapezoidal corrugated shear walls were constructed and tested under cyclic loading. One specimen had a single rectangular [...] Read more.
This paper investigates the influence of an opening in the infill steel plate on the behavior of steel trapezoidal corrugated infill panels. Two specimens of steel trapezoidal corrugated shear walls were constructed and tested under cyclic loading. One specimen had a single rectangular opening, while the other one had two rectangular openings. In addition, the percentage of opening in both specimens was 18%. The initial stiffness, ultimate strength, ductility ratio and energy dissipation capacity of the two tested specimens are compared to a specimen without opening. The experimental results indicate that the existence of an opening has the greatest effect on the initial stiffness of the corrugated steel infill panels. In addition, the experimental results reveal that the structural performance of the specimen with two openings is improved in some areas compared to the specimen with one opening. To that end, the energy dissipation capacity of the specimen with two openings is obtained larger than the specimen with one opening. Furthermore, a number of numerical analyses were performed. The numerical results show that with increasing the thickness of the infill plate or using stiffeners around the opening, the ultimate strength of a corrugated steel infill panel with an opening can be equal to or even more than the ultimate strength of that panel without an opening. Full article
(This article belongs to the Section Civil Engineering)
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18 pages, 2297 KiB  
Article
Daucus carota L. Seed Inoculation with a Consortium of Bacteria Improves Plant Growth, Soil Fertility Status and Microbial Community
by Marika Pellegrini, Giancarlo Pagnani, Massimiliano Rossi, Sara D’Egidio, Maddalena Del Gallo and Cinzia Forni
Appl. Sci. 2021, 11(7), 3274; https://doi.org/10.3390/app11073274 - 6 Apr 2021
Cited by 11 | Viewed by 3316
Abstract
The present work aimed to study suitability of a consortium of Azospirillum brasilense, Gluconacetobacter diazotrophicus, Herbaspirillum seropedicae, and Burkholderia ambifaria as biofertilizers. Strains were assayed for plant growth-promoting characteristics (i.e., auxins production, phosphate solubilizing capability, and 1-aminocyclopropane-1-carboxylate deaminase activity). The [...] Read more.
The present work aimed to study suitability of a consortium of Azospirillum brasilense, Gluconacetobacter diazotrophicus, Herbaspirillum seropedicae, and Burkholderia ambifaria as biofertilizers. Strains were assayed for plant growth-promoting characteristics (i.e., auxins production, phosphate solubilizing capability, and 1-aminocyclopropane-1-carboxylate deaminase activity). The consortium of four bacteria was then inoculated on carrot seeds and tested in an open field experiment. During the open field experiment, plant growth (morphological parameters, chlorophylls, and carotenoids), soil chemical analysis, and molecular and physiological profiles of soils were investigated. Each strain produced different amounts of indole-3acetic acid and several indole-derivates molecules. All strains showed phosphate solubilization capability, while 1-aminocyclopropane-1-carboxylate deaminase activity was only detected in H. seropedicae and B. ambifaria. The bacterial consortium of the four strains gave interesting results in the open field cultivation of carrot. Plant development was positively affected by the presence of the consortium, as was soil fertility and microbial community structure and diversity. The present work allowed for deepening our knowledge on four bacteria, already known for years for having several interesting characteristics, but whose interactions were almost unknown, particularly in view of their use as a consortium in a valid fertilization strategy, in substitution of agrochemicals for a sustainable agriculture. Full article
(This article belongs to the Special Issue Microbial Biofertilizers for Crop Improvement: From Molecular Biology to Biotechnology)
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12 pages, 1594 KiB  
Article
Machine Learning and Feature Selection Methods for EGFR Mutation Status Prediction in Lung Cancer
by Joana Morgado, Tania Pereira, Francisco Silva, Cláudia Freitas, Eduardo Negrão, Beatriz Flor de Lima, Miguel Correia da Silva, António J. Madureira, Isabel Ramos, Venceslau Hespanhol, José Luis Costa, António Cunha and Hélder P. Oliveira
Appl. Sci. 2021, 11(7), 3273; https://doi.org/10.3390/app11073273 - 6 Apr 2021
Cited by 23 | Viewed by 4900
Abstract
The evolution of personalized medicine has changed the therapeutic strategy from classical chemotherapy and radiotherapy to a genetic modification targeted therapy, and although biopsy is the traditional method to genetically characterize lung cancer tumor, it is an invasive and painful procedure for the [...] Read more.
The evolution of personalized medicine has changed the therapeutic strategy from classical chemotherapy and radiotherapy to a genetic modification targeted therapy, and although biopsy is the traditional method to genetically characterize lung cancer tumor, it is an invasive and painful procedure for the patient. Nodule image features extracted from computed tomography (CT) scans have been used to create machine learning models that predict gene mutation status in a noninvasive, fast, and easy-to-use manner. However, recent studies have shown that radiomic features extracted from an extended region of interest (ROI) beyond the tumor, might be more relevant to predict the mutation status in lung cancer, and consequently may be used to significantly decrease the mortality rate of patients battling this condition. In this work, we investigated the relation between image phenotypes and the mutation status of Epidermal Growth Factor Receptor (EGFR), the most frequently mutated gene in lung cancer with several approved targeted-therapies, using radiomic features extracted from the lung containing the nodule. A variety of linear, nonlinear, and ensemble predictive classification models, along with several feature selection methods, were used to classify the binary outcome of wild-type or mutant EGFR mutation status. The results show that a comprehensive approach using a ROI that included the lung with nodule can capture relevant information and successfully predict the EGFR mutation status with increased performance compared to local nodule analyses. Linear Support Vector Machine, Elastic Net, and Logistic Regression, combined with the Principal Component Analysis feature selection method implemented with 70% of variance in the feature set, were the best-performing classifiers, reaching Area Under the Curve (AUC) values ranging from 0.725 to 0.737. This approach that exploits a holistic analysis indicates that information from more extensive regions of the lung containing the nodule allows a more complete lung cancer characterization and should be considered in future radiogenomic studies. Full article
(This article belongs to the Special Issue Novel Applications of Artificial Intelligence in Medicine and Health)
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15 pages, 40767 KiB  
Article
The Deltah Lab, a New Multidisciplinary European Facility to Support the H2 Distribution & Storage Economy
by Sara Stelitano, Alberto Rullo, Luigi Piredda, Elisabetta Mecozzi, Luigi Di Vito, Raffaele Giuseppe Agostino, Raffaele Filosa, Vincenzo Formoso, Giuseppe Conte and Alfonso Policicchio
Appl. Sci. 2021, 11(7), 3272; https://doi.org/10.3390/app11073272 - 6 Apr 2021
Cited by 6 | Viewed by 2368
Abstract
The target for European decarburization encourages the use of renewable energy sources and H2 is considered the link in the global energy system transformation. So, research studies are numerous, but only few facilities can test materials and components for H2 storage. [...] Read more.
The target for European decarburization encourages the use of renewable energy sources and H2 is considered the link in the global energy system transformation. So, research studies are numerous, but only few facilities can test materials and components for H2 storage. This work offers a brief review of H2 storage methods and presents the preliminary results obtained in a new facility. Slow strain rate and fatigue life tests were performed in H2 at 80 MPa on specimens and a tank of AISI 4145, respectively. Besides, the storage capacity at 30 MPa of a solid-state system, they were evaluated on kg scale by adsorption test. The results have shown the H2 influence on mechanical properties of the steel. The adsorption test showed a gain of 26% at 12 MPa in H2 storage with respect to the empty condition. All samples have been characterized by complementary techniques in order to connect the H2 effect with material properties. Full article
(This article belongs to the Special Issue Advances in Porous Materials for Energy Storage)
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19 pages, 4751 KiB  
Article
Energy-Efficient Amplifiers Based on Quasi-Floating Gate Techniques
by Antonio Lopez-Martin, Maria Pilar Garde, Jose M. Algueta-Miguel, Javier Beloso-Legarra, Ramon G. Carvajal and Jaime Ramirez-Angulo
Appl. Sci. 2021, 11(7), 3271; https://doi.org/10.3390/app11073271 - 6 Apr 2021
Cited by 7 | Viewed by 4417
Abstract
Energy efficiency is a key requirement in the design of amplifiers for modern wireless applications. The use of quasi-floating gate (QFG) transistors is a very convenient approach to achieve such energy efficiency. We illustrate different QFG circuit design techniques aimed to implement low-voltage, [...] Read more.
Energy efficiency is a key requirement in the design of amplifiers for modern wireless applications. The use of quasi-floating gate (QFG) transistors is a very convenient approach to achieve such energy efficiency. We illustrate different QFG circuit design techniques aimed to implement low-voltage, energy-efficient class AB amplifiers. A new super class AB QFG amplifier is presented as a design example, including some of the techniques described. The amplifier has been fabricated in a 130 nm CMOS test chip prototype. Measurement results confirm that low-voltage, ultra-low-power amplifiers can be designed, preserving, at the same time, excellent small-signal and large-signal performance. Full article
(This article belongs to the Special Issue Advances in Low-Voltage Design Techniques for Scaled CMOS Technologies)
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34 pages, 3592 KiB  
Article
Large-Scale Truss-Sizing Optimization with Enhanced Hybrid HS Algorithm
by Sadik Ozgur Degertekin, Mohammad Minooei, Lorenzo Santoro, Bartolomeo Trentadue and Luciano Lamberti
Appl. Sci. 2021, 11(7), 3270; https://doi.org/10.3390/app11073270 - 6 Apr 2021
Cited by 15 | Viewed by 2863
Abstract
Metaheuristic algorithms currently represent the standard approach to engineering optimization. A very challenging field is large-scale structural optimization, entailing hundreds of design variables and thousands of nonlinear constraints on element stresses and nodal displacements. However, very few studies documented the use of metaheuristic [...] Read more.
Metaheuristic algorithms currently represent the standard approach to engineering optimization. A very challenging field is large-scale structural optimization, entailing hundreds of design variables and thousands of nonlinear constraints on element stresses and nodal displacements. However, very few studies documented the use of metaheuristic algorithms in large-scale structural optimization. In order to fill this gap, an enhanced hybrid harmony search (HS) algorithm for weight minimization of large-scale truss structures is presented in this study. The new algorithm, Large-Scale Structural Optimization–Hybrid Harmony Search JAYA (LSSO-HHSJA), developed here, combines a well-established method like HS with a very recent method like JAYA, which has the simplest and inherently most powerful search engine amongst metaheuristic optimizers. All stages of LSSO-HHSJA are aimed at reducing the number of structural analyses required in large-scale structural optimization. The basic idea is to move along descent directions to generate new trial designs, directly through the use of gradient information in the HS phase, indirectly by correcting trial designs with JA-based operators that push search towards the best design currently stored in the population or the best design included in a local neighborhood of the currently analyzed trial design. The proposed algorithm is tested in three large-scale weight minimization problems of truss structures. Optimization results obtained for the three benchmark examples, with up to 280 sizing variables and 37,374 nonlinear constraints, prove the efficiency of the proposed LSSO-HHSJA algorithm, which is very competitive with other HS and JAYA variants as well as with commercial gradient-based optimizers. Full article
(This article belongs to the Special Issue Harmony Search Algorithm - Theoretical Background and Practical Applications)
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30 pages, 38030 KiB  
Article
Numerical Analysis of the Beam-Column Resistance Compared to Methods by European Standards
by Jozef Prokop, Josef Vičan and Jozef Jošt
Appl. Sci. 2021, 11(7), 3269; https://doi.org/10.3390/app11073269 - 6 Apr 2021
Cited by 10 | Viewed by 3287
Abstract
The optimisation of the design method for verification of slender steel beam-columns is still a current issue not only from scientific point of view, but also for design practice. Therefore, the main objective of this paper is comparison of the suitability of established [...] Read more.
The optimisation of the design method for verification of slender steel beam-columns is still a current issue not only from scientific point of view, but also for design practice. Therefore, the main objective of this paper is comparison of the suitability of established design approaches, according to the European standards for steel and aluminium structures, on the basis of numerical simulations. Thus, a finite element model was validated on the basis of experimental analysis available in the scientific literature. To perform the comparison of accuracy of design approaches according to European standards, a commercial software program ANSYS was used for observation of the resistances of beam-columns. The resistance of european I beams with parallel flanges (IPE) and a rectangular hollow cross-section (RHS) were investigated for four load cases on a simply supported member and also on a pinned-fixed beam column with linear bending moment distribution, where the resistance of the cross-section governs. Finally, the conclusions for suitability of the respective design approaches are discussed, together with some findings that arose from this work. Full article
(This article belongs to the Special Issue Advances on Structural Engineering, Volume II)
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15 pages, 8124 KiB  
Article
Study on Design of Non-Circular Gears for Speed Control of the Squid Belly Opening and Gutting Machine (SBOGM)
by Hyo-Seong Jang, Chang-Hyun Lee, Gun-Young Park and Chul Kim
Appl. Sci. 2021, 11(7), 3268; https://doi.org/10.3390/app11073268 - 6 Apr 2021
Cited by 2 | Viewed by 3731
Abstract
Non-circular gears can maintain rotational motions of general gears and implement all varying rotational motions of the cam. They adjust the angular velocity of driven gear according to operating conditions and make precise changes in angular motion. The design of non-circular gears has [...] Read more.
Non-circular gears can maintain rotational motions of general gears and implement all varying rotational motions of the cam. They adjust the angular velocity of driven gear according to operating conditions and make precise changes in angular motion. The design of non-circular gears has not been sufficiently studied because of their particularity and complex design methods unlike spur gears. In the gutting section of the Squid Belly Opening and Gutting Machine (SBOGM), spur gears generate rotational impact due to constant angular velocities, causing noise and equipment damage; so, efficiency should be improved by varying sectional angular velocity. Therefore, we derived pitch curves by selecting angular velocity ratio considering operating environments, and the tooth profile was designed by calculating module for each section according to radius through theorical analysis for precise expression of angular velocity ratio. To confirm reliability of design, angular velocity ratio and structural safety of designed non-circular gears were verified using, commercial software, ‘DAFUL 2020 R1′. Full article
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11 pages, 4847 KiB  
Article
Passive Multi-Layer Composite Damper of Flat Belt Tensioner Idler
by Zuzana Murčinková, Jozef Živčák, Jozef Zajac and Pavel Adamčík
Appl. Sci. 2021, 11(7), 3267; https://doi.org/10.3390/app11073267 - 6 Apr 2021
Cited by 4 | Viewed by 2228
Abstract
In this study, the effect of multi-layer composite passive dampers on the dynamic properties of a mechanical system (a testing machine tool bench) was tested. Passive dampers are characterized by a layered structure, with each layer consisting of a specific structure of different [...] Read more.
In this study, the effect of multi-layer composite passive dampers on the dynamic properties of a mechanical system (a testing machine tool bench) was tested. Passive dampers are characterized by a layered structure, with each layer consisting of a specific structure of different materials, preferably foam polymers. The dynamic excitation is caused by a flat belt driving the rotor roller bearing by direct contact of the flat belt and bearing pin at a frequency of 1170–2170 Hz. The dynamic effects of the flat belt directly affect the complex dynamic effects inside rotor bearing, mainly torsional vibrations. A significant modification in the amplitude and frequency modulation and other evaluated dynamic parameters was obtained. By implementing passive dampers and modifying the mass and material damping, a decrease in amplitude at resonance of almost 30% was achieved. Full article
(This article belongs to the Section Mechanical Engineering)
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16 pages, 2983 KiB  
Article
Development of Optimal Design Method for Steel Double-Beam Floor System Considering Rotational Constraints
by Insub Choi, Dongwon Kim and Junhee Kim
Appl. Sci. 2021, 11(7), 3266; https://doi.org/10.3390/app11073266 - 6 Apr 2021
Cited by 1 | Viewed by 7272
Abstract
Under high gravity loads, steel double-beam floor systems need to be reinforced by beam-end concrete panels to reduce the material quantity since rotational constraints from the concrete panel can decrease the moment demand by inducing a negative moment at the ends of the [...] Read more.
Under high gravity loads, steel double-beam floor systems need to be reinforced by beam-end concrete panels to reduce the material quantity since rotational constraints from the concrete panel can decrease the moment demand by inducing a negative moment at the ends of the beams. However, the optimal design process for the material quantity of steel beams requires a time-consuming iterative analysis for the entire floor system while especially keeping in consideration the rotational constraints in composite connections between the concrete panel and steel beams. This study aimed to develop an optimal design method with the LM (Length-Moment) index for the steel double-beam floor system to minimize material quantity without the iterative design process. The LM index is an indicator that can select a minimum cross-section of the steel beams in consideration of the flexural strength by lateral-torsional buckling. To verify the proposed design method, the material quantities between the proposed and code-based design methods were compared at various gravity loads. The proposed design method successfully optimized the material quantity of the steel double-beam floor systems without the iterative analysis by simply choosing the LM index of the steel beams that can minimize objective function while satisfying the safety-related constraint conditions. In particular, under the high gravity loads, the proposed design method was superb at providing a quantity-optimized design option. Thus, the proposed optimal design method can be an alternative for designing the steel double-beam floor system. Full article
(This article belongs to the Special Issue Toward Sustainable Engineering Structures for Better Safety in Built-Environment)
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