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Volume 9
Issue 23
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Appl. Sci., Volume 9, Issue 23 (December-1 2019) – 287 articles

Cover Story (view full-size image): The use of Virtual Reality (VR) as a resource in the teaching of courses that focus on the design of urban spaces helps users to improve their digital abilities in the area of complex representation and in the evaluation and decision-making processes. This image represents the work of two students (Lucas Escudero and Jordi Carbajo) in the Computer Tools II subject at the Architecture School in La Salle, Ramon Llull University that focused on the redesign of the Plaça (square) Baró, in Santa Coloma de Gramanet, Barcelona. They worked with different tools, including VR, in the design of this urban project. View this paper.
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15 pages, 2398 KiB  
Article
Analytical Model for Predicting the UCS from P-Wave Velocity, Density, and Porosity on Saturated Limestone
by Javier González, Manuel Saldaña and Javier Arzúa
Appl. Sci. 2019, 9(23), 5265; https://doi.org/10.3390/app9235265 - 3 Dec 2019
Cited by 26 | Viewed by 5618
Abstract
Rock mechanics and rock engineering projects require determining, among other parameters, the uniaxial compressive strength (UCS) of rock. For such a purpose, it is not uncommon to perform ultrasonic pulse laboratory tests. Many researchers have found experimental relationships between strength and P-wave velocity, [...] Read more.
Rock mechanics and rock engineering projects require determining, among other parameters, the uniaxial compressive strength (UCS) of rock. For such a purpose, it is not uncommon to perform ultrasonic pulse laboratory tests. Many researchers have found experimental relationships between strength and P-wave velocity, but these relationships are based mainly on dry conditions and without considering any other physical or chemical characteristics of the studied rock. Specifically, for limestone, there are 11 correlations reported in the literature, eight of which are simple and the remaining three are multiple, and, among the latter, only two of them consider the saturation. In order to evaluate the combined effect of P-wave velocity, density, and porosity on the UCS of saturated limestone, simple and multiple regression analyses were carried out on the test results of 13 saturated limestone specimens to determine the parameters of both previously mentioned predictive models. The results showed that density is not correlated with strength. Full article
(This article belongs to the Section Civil Engineering)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Predicted UCS Equations (1)–(11) vs. experimental UCS.</p> Full article ">Figure 2
<p>Left: correlation between experimental UCS and P-wave velocity. Right: predicted against experimental UCS values. (<b>a</b>,<b>b</b>) Linear fit, (<b>c</b>,<b>d</b>) exponential fit, (<b>e</b>,<b>f</b>) potential fit, and (<b>g</b>,<b>h</b>) quadratic fit.</p> Full article ">Figure 2 Cont.
<p>Left: correlation between experimental UCS and P-wave velocity. Right: predicted against experimental UCS values. (<b>a</b>,<b>b</b>) Linear fit, (<b>c</b>,<b>d</b>) exponential fit, (<b>e</b>,<b>f</b>) potential fit, and (<b>g</b>,<b>h</b>) quadratic fit.</p> Full article ">Figure 3
<p>Multiple regression analysis response surface of UCS: (<b>a</b>) Equation (21) and (<b>b</b>) Equation (22).</p> Full article ">Figure 4
<p>Predicted against experimental UCS results of the multiple regression analysis.</p> Full article ">Figure 5
<p>Comparison of theoretical and observed probabilities for standardized residuals of uniaxial compressive strength.</p> Full article ">
16 pages, 3244 KiB  
Article
Neural Computing Improvement Using Four Metaheuristic Optimizers in Bearing Capacity Analysis of Footings Settled on Two-Layer Soils
by Hossein Moayedi, Dieu Tien Bui and Phuong Thao Thi Ngo
Appl. Sci. 2019, 9(23), 5264; https://doi.org/10.3390/app9235264 - 3 Dec 2019
Cited by 22 | Viewed by 3613
Abstract
This study outlines the applicability of four metaheuristic algorithms, namely, whale optimization algorithm (WOA), league champion optimization (LCA), moth–flame optimization (MFO), and ant colony optimization (ACO), for performance improvement of an artificial neural network (ANN) in analyzing the bearing capacity of footings settled [...] Read more.
This study outlines the applicability of four metaheuristic algorithms, namely, whale optimization algorithm (WOA), league champion optimization (LCA), moth–flame optimization (MFO), and ant colony optimization (ACO), for performance improvement of an artificial neural network (ANN) in analyzing the bearing capacity of footings settled on two-layered soils. To this end, the models estimate the stability/failure of the system by taking into consideration soil key factors. The complexity of each network is optimized through a sensitivity analysis process. The performance of the ensembles is compared with a typical ANN to evaluate the efficiency of the applied optimizers. It was shown that the incorporation of the WOA, LCA, MFO, and ACO algorithms resulted in 14.49%, 13.41%, 18.30%, and 35.75% reductions in the prediction error of the ANN, respectively. Moreover, a ranking system is developed to compare the efficiency of the used models. The results revealed that the ACO–ANN performs most accurately, followed by the MFO–ANN, WOA–ANN, and LCA–ANN. Lastly, the outcomes demonstrated that the ACO–ANN can be a promising alternative to traditional methods used for analyzing the bearing capacity of two-layered soils. Full article
(This article belongs to the Special Issue Artificial Intelligence in Smart Buildings)
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Figure 1

Figure 1
<p>The structure of a multi-layer perceptron (MLP) neural network.</p> Full article ">Figure 2
<p>Distribution of bearing capacity influential factors: (<b>a</b>) unit weight, (<b>b</b>) friction angle, (<b>c</b>) elastic modulus, (<b>d</b>) dilation angle, (<b>e</b>) Poisson’s ratio, (<b>f</b>) applied stress, (<b>g</b>) setback distance, and (<b>h</b>) settlement.</p> Full article ">Figure 3
<p>Executed sensitivity analysis based on the population size: (<b>a</b>) obtained RMSE values, the convergence curves of (<b>b</b>) MFO-ANN, (<b>c</b>) WOA-ANN, (<b>d</b>) ACO-ANN, and (<b>e</b>) LCA-ANN.</p> Full article ">Figure 4
<p>The results obtained for (<b>a</b>) WOA-ANN, (<b>b</b>) LCA-ANN, (<b>c</b>) MFO-ANN, and (<b>d</b>) ACO-ANN predictions in the training phase.</p> Full article ">Figure 4 Cont.
<p>The results obtained for (<b>a</b>) WOA-ANN, (<b>b</b>) LCA-ANN, (<b>c</b>) MFO-ANN, and (<b>d</b>) ACO-ANN predictions in the training phase.</p> Full article ">Figure 5
<p>The results obtained for (<b>a</b>,<b>b</b>) whale optimization algorithm (WOA)–artificial neural network (ANN), (<b>c</b>,<b>d</b>) league champion optimization algorithm (LCA)–ANN, (<b>e</b>,<b>f</b>) moth–flame optimization (MFO)–ANN, and (<b>g</b>,<b>h</b>) ant colony optimization (ACO)–ANN predictions for the testing samples.</p> Full article ">Figure 6
<p>The receiver operating characteristic (ROC) curves of (<b>a</b>) WOA–ANN, (<b>b</b>) LCA–ANN, (<b>c</b>) MFO–ANN, and (<b>d</b>) ACO–ANN predictions in the testing phase.</p> Full article ">
11 pages, 2107 KiB  
Article
Receptance-Based Dominant Eigenvalues Computation of Controlled Vibrating Systems with Multiple Time-Delays Using a Contour Integral Method
by Jun-Shen Yang, Huajiang Ouyang, Jia-Fan Zhang, Ke-Wei Zhang, Zhi-Gang Hu and Hai-Min Liu
Appl. Sci. 2019, 9(23), 5263; https://doi.org/10.3390/app9235263 - 3 Dec 2019
Cited by 1 | Viewed by 2282
Abstract
The computation of dominant eigenvalues of second-order linear control systems with multiple time-delays is tackled by using a contour integral method. The proposed approach depends on a reduced characteristic function and the associated characteristic matrix comprised of measured open-loop receptances. This reduced characteristic [...] Read more.
The computation of dominant eigenvalues of second-order linear control systems with multiple time-delays is tackled by using a contour integral method. The proposed approach depends on a reduced characteristic function and the associated characteristic matrix comprised of measured open-loop receptances. This reduced characteristic function is derived from the original characteristic function of the second-order time delayed systems based on the reasonable assumption that eigenvalues of the closed-loop system are distinct from those of the open-loop system, and has the same eigenvalues as those of the original. Then, the eigenvalues computation is equivalent to solve a nonlinear eigenvalue problem of the associated characteristic matrix by using a contour integral method. The proposed approach also utilizes the spectrum distribution features of the retarded time-delay systems. Finally, numerical examples are given to illustrate the effectiveness of the proposed approach. Full article
(This article belongs to the Section Acoustics and Vibrations)
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Figure 1

Figure 1
<p>A five-degree of freedom closed-loop control system [<a href="#B27-applsci-09-05263" class="html-bibr">27</a>].</p> Full article ">Figure 2
<p>Dominant eigenvalues of the closed-loop system without/with time-delays (“+”/“o”).</p> Full article ">Figure 3
<p>Dominant eigenvalues of the closed-loop time delayed system, obtained by a spectral method [<a href="#B8-applsci-09-05263" class="html-bibr">8</a>] (“*”) and by the contour integral method (“o”) with radius <span class="html-italic">R</span> = 5.</p> Full article ">Figure 4
<p>All poles of the open-loop receptances <math display="inline"><semantics> <mrow> <msub> <mstyle mathvariant="bold" mathsize="normal"> <mi>H</mi> </mstyle> <mrow> <mn>0</mn> <mi mathvariant="normal">m</mi> </mrow> </msub> <mrow> <mo>(</mo> <mi>λ</mi> <mo>)</mo> </mrow> </mrow> </semantics></math> within two contours with radius <span class="html-italic">R</span> = 2 (<b>a</b>) and 5 (<b>b</b>) (denoted by “<b>+</b>”) and computed eigenvalues using the contour integral method (denoted by “o”).</p> Full article ">
15 pages, 3758 KiB  
Article
A Novel Design of Fractional PI/PID Controllers for Two-Input-Two-Output Processes
by Vo Lam Chuong, Truong Nguyen Luan Vu, Nguyen Tam Nguyen Truong and Jae Hak Jung
Appl. Sci. 2019, 9(23), 5262; https://doi.org/10.3390/app9235262 - 3 Dec 2019
Cited by 6 | Viewed by 2960
Abstract
In this paper, a new formulation of fractional order proportional integral (PI)/ proportional integral derivative (PID) controller is proposed. The proposed controller will be justified for some well-known two-input-two-output (TITO) processes. In order to deal with interactions between process variables in a multivariable [...] Read more.
In this paper, a new formulation of fractional order proportional integral (PI)/ proportional integral derivative (PID) controller is proposed. The proposed controller will be justified for some well-known two-input-two-output (TITO) processes. In order to deal with interactions between process variables in a multivariable system, as well as multiple delay times in process transfer functions, the simplified decoupling Smith predictor (SDSP) structure is also used. The issue of decoupling realizability is solved by the PSO algorithm and fractional order processes are also suggested for model reduction. The tuning rules of the controller are derived in analytical terms based on the internal model control (IMC) structure. The effectiveness and robust stability of the proposed approach are illustrated by comparing it with other methods. To have a fair comparison, the robustness criterion using the M-Δ structure with μ-synthesis is adopted and the μ value of the proposed method is always kept smaller than the value of the others. Full article
(This article belongs to the Section Mechanical Engineering)
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Figure 1

Figure 1
<p>The simplified decoupling Smith predictor (SDSP) structure with approximated fractional order processes (F-SDSP).</p> Full article ">Figure 2
<p>The one degree of freedom feedback control diagram. (<b>a</b>) Classical feedback control (<b>b</b>) Internal model control.</p> Full article ">Figure 3
<p><b>M-Δ</b> structure with multiplicative output uncertainties.</p> Full article ">Figure 4
<p>(<b>a</b>) Closed-loop responses to the unit step changes in the set-point of loop 1 in Example 1. (<b>b</b>) Closed-loop responses to the unit step changes in the set-point of loop 2 in Example 1.</p> Full article ">Figure 5
<p>(<b>a</b>) The control signal of loop 1 in Example 1. (<b>b</b>) The control signal of loop 1 in Example 1.</p> Full article ">Figure 6
<p>The structured singular value (SSV) plots of robust stability in Example 1.</p> Full article ">Figure 7
<p>(<b>a</b>) Closed-loop responses to the unit step changes in the set-point of loop 1 in Example 2*. (<b>b</b>) Closed-loop responses to the unit step changes in the set-point of loop 2 in Example 2*. (* Santos in all <a href="#applsci-09-05262-f007" class="html-fig">Figure 7</a>, <a href="#applsci-09-05262-f008" class="html-fig">Figure 8</a> and <a href="#applsci-09-05262-f009" class="html-fig">Figure 9</a> is used instead of “Simplified filter Smith predictor proposed by Santos et al. [<a href="#B22-applsci-09-05262" class="html-bibr">22</a>]”).</p> Full article ">Figure 8
<p>(<b>a</b>) The control signal in loop 1 in Example 2*. (<b>b</b>) The control signal in loop 2 in Example 2*.</p> Full article ">Figure 9
<p>The SSV plots of robust stability in Example 2*.</p> Full article ">Figure 10
<p>(<b>a</b>) Closed-loop responses to the unit step changes in the set-point of loop 1 in Example 3*. (<b>b</b>) Closed-loop responses to the unit step changes in the set-point of loop 2 in Example 3*. (<span class="html-italic">*</span> Garrido in all <a href="#applsci-09-05262-f010" class="html-fig">Figure 10</a>, <a href="#applsci-09-05262-f011" class="html-fig">Figure 11</a> and <a href="#applsci-09-05262-f012" class="html-fig">Figure 12</a> is used instead of “The centralized inverted decoupling method proposed by Garrido et al. [<a href="#B21-applsci-09-05262" class="html-bibr">21</a>]”).</p> Full article ">Figure 11
<p>(<b>a</b>) The control signal of loop 1 in Example 3*. (<b>b</b>) The control signal of loop 2 in Example 3*.</p> Full article ">Figure 12
<p>The SSV plots of robust stability in Example 3*.</p> Full article ">
4 pages, 174 KiB  
Editorial
Special Issue on Modelling, Simulation and Data Analysis in Acoustical Problems
by Claudio Guarnaccia, Lamberto Tronchin and Massimo Viscardi
Appl. Sci. 2019, 9(23), 5261; https://doi.org/10.3390/app9235261 - 3 Dec 2019
Cited by 3 | Viewed by 2203
Abstract
Modelling and simulation in acoustics is gathering more and more importance nowadays [...] Full article
(This article belongs to the Special Issue Modelling, Simulation and Data Analysis in Acoustical Problems)
14 pages, 8176 KiB  
Article
Research and Development of a Novel TIG Welding Torch for Joining Thin Sheets
by Ngo Huu Manh, Nguyen Van Anh, Nguyen Van Tuan, Bin Xu and Murata Akihisa
Appl. Sci. 2019, 9(23), 5260; https://doi.org/10.3390/app9235260 - 3 Dec 2019
Cited by 7 | Viewed by 5398
Abstract
This paper aims to develop a novel tungsten inner gas (TIG) welding torch in order to join thin sheets efficiently. Using a narrowing nozzle (constricted nozzle) inside a conventional TIG torch can critically improve the position accuracy of the tungsten electrode and also [...] Read more.
This paper aims to develop a novel tungsten inner gas (TIG) welding torch in order to join thin sheets efficiently. Using a narrowing nozzle (constricted nozzle) inside a conventional TIG torch can critically improve the position accuracy of the tungsten electrode and also the arc plasma characteristics and heat input density. In order to evaluate the efficiency of this new torch, weld bead appearance and cross-section images were examined by an optical microscope, scanning electron microscope (SEM), and electron back scatter diffraction patterns (EBSD). The results showed that in all cases, the weld bead profile was stable without undercut and burn-through. Full penetration weld was seen. The width of weld bead on the bottom surface was increased much in comparison to conventional TIG welding. However, the results from SEM and EBSD images indicated that in the case of low welding current, the blowholes were found out on the side of the thinner material (SS400). The penetration of SUS430 material to SS400 material was not good. It seems that no fusion of SUS430 material to SS400 at the bottom surface can be seen. Meanwhile, no blowholes were seen in the case of high welding current. The penetration was better, and the fusion was reached on the bottom surface. Full article
(This article belongs to the Section Mechanical Engineering)
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Figure 1

Figure 1
<p>Constricted nozzle and welding torch.</p> Full article ">Figure 2
<p>A Schematic illustration of constricted nozzle tungsten inner gas (TIG) welding process.</p> Full article ">Figure 3
<p>Experimental equipment.</p> Full article ">Figure 4
<p>Experimental process.</p> Full article ">Figure 5
<p>Weld bead appearance.</p> Full article ">Figure 6
<p>Electron back scatter diffraction (EBSD) images of welding SS400 materials (No.1).</p> Full article ">Figure 7
<p>SEM (scanning electron microscope) images of welding between SS400 materials (No.1).</p> Full article ">Figure 8
<p>EBSD images of welding between SUS430 materials (No.2).</p> Full article ">Figure 9
<p>EBSD images of welding SS400 and SUS430 materials (No.3).</p> Full article ">Figure 10
<p>EBSD images of welding SS400 and SUS430 materials (No.4).</p> Full article ">Figure 11
<p>Elemental analysis images of welding SS400 and SUS430 materials (No.3).</p> Full article ">Figure 12
<p>Elemental analysis images of welding SS400 and SUS430 materials (No.4).</p> Full article ">Figure 13
<p>Magnified images of blowhole inside the weldment in the case of No.3. (<b>a</b>): SEM-X15000 and (<b>b</b>): SEM-X10000).</p> Full article ">Figure 14
<p>Ratio of width on top surface to width on bottom surface.</p> Full article ">Figure 15
<p>Prediction of the blowhole formation process.</p> Full article ">
14 pages, 2145 KiB  
Article
Thermo-Optical and Particle Number Size Distribution Characteristics of Smoldering Smoke from Biomass Burning
by Feng Wang, Qixing Zhang, Xuezhe Xu, Weixiong Zhao, Yongming Zhang and Weijun Zhang
Appl. Sci. 2019, 9(23), 5259; https://doi.org/10.3390/app9235259 - 3 Dec 2019
Cited by 3 | Viewed by 2793
Abstract
Controlled laboratory combustion experiments were conducted in the fire test room to mimic freshly emitted smoldering smoke of biomass burning in China. The biomass components were determined by ultimate analysis and proximate analysis before experiments. The particle number size distribution (PNSD) between 5 [...] Read more.
Controlled laboratory combustion experiments were conducted in the fire test room to mimic freshly emitted smoldering smoke of biomass burning in China. The biomass components were determined by ultimate analysis and proximate analysis before experiments. The particle number size distribution (PNSD) between 5 and 1000 nm of smoke was measured by a high sampling frequency size spectrometer. A cavity-enhanced aerosol albedometer with wavelength of 532 nm was used to measure scattering coefficients, extinction coefficients, and single scattering albedo (SSA) of smoldering smoke. The PNSDs of smoldering smoke from the burning of agricultural straw could be fitted with a bimodal lognormal distribution as modes around 10 nm (nucleation mode) and 60 nm (Aitken mode). The PNSDs of wood sawdust could be fitted with a trimodal lognormal distribution, while the two modes were in nucleation mode, and one was in Aitken mode. The bulk optical properties (scattering and extinction coefficients) of smoldering smoke had strong correlations with particle number concentrations of sizes bigger than 100 nm. The correlation between SSA and fixed carbon (FC) was strong (the correlation coefficient is 0.89), while the correlation between SSA and volatile matter (VM) or ash was weak. The relationship between SSA and N (or S) showed a positive correlation, while that of SSA and C showed a negative correlation. The relationship between SSA and VM/FC (or N) showed a strong linear relationship (r2 > 0.8). This paper could improve understanding of the relationship between the optical and particle size distribution properties of smoke from biomass burning and the components of biomass materials under similar combustion conditions. Full article
(This article belongs to the Special Issue Combustion Aerosol)
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Figure 1

Figure 1
<p>Schematic diagram of the fire test room and the experimental setup.</p> Full article ">Figure 2
<p>Van Krevelen diagram of biomass samples with the atom ratios of H/C and O/C from the ultimate analysis results.</p> Full article ">Figure 3
<p>Correlation between the contents of volatile matter (VM) and ash from the proximate analysis results of biomass samples on dry basis.</p> Full article ">Figure 4
<p>Two kinds of particle size distributions and their fitted curves in the well-mixed stage after burning out. (<b>a</b>) Particle size distribution of soya which has two modes; (<b>b</b>) particle size distribution of P2 which has three modes.</p> Full article ">Figure 5
<p>The correlation coefficients between extinction coefficients (<b>a</b>) scattering coefficients (<b>b</b>) and particle number concentrations of different sizes for smoke of biomass samples.</p> Full article ">Figure 6
<p>Correlation between SSA and the biomass components: (<b>a</b>) VM/FC; (<b>b</b>) N.</p> Full article ">
15 pages, 6848 KiB  
Article
Failure Analysis on a Collapsed Flat Cover of an Adjustable Ballast Tank Used in Deep-Sea Submersibles
by Fang Wang, Mian Wu, Genqi Tian, Zhe Jiang, Shun Zhang, Jian Zhang and Weicheng Cui
Appl. Sci. 2019, 9(23), 5258; https://doi.org/10.3390/app9235258 - 3 Dec 2019
Cited by 1 | Viewed by 3294
Abstract
A flat cover of an adjustable ballast tank made of high-strength maraging steel used in deep-sea submersibles collapsed during the loading process of external pressure in the high-pressure chamber. The pressure was high, which was the trigger of the collapse, but still considerably [...] Read more.
A flat cover of an adjustable ballast tank made of high-strength maraging steel used in deep-sea submersibles collapsed during the loading process of external pressure in the high-pressure chamber. The pressure was high, which was the trigger of the collapse, but still considerably below the design limit of the adjustable ballast tank. The failure may have been caused by material properties that may be defective, the possible stress concentration resulting from design/processing, or inappropriate installation method. The present paper focuses on the visual inspections of the material inhomogeneity, ultimate cause of the collapse of the flat cover in pressure testing, and finite element analysis. Special attention is paid to the toughness characteristics of the material. The present study demonstrates the importance of material selection for engineering components based on the comprehensive properties of the materials. Full article
(This article belongs to the Special Issue Recent Trends in Advanced High-Strength Steels)
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Figure 1

Figure 1
<p>Sketch of the adjustable ballast tank and its sealing cover: (<b>a</b>) front view of the adjustable ballast tank; (<b>b</b>) description of the sealing cover.</p> Full article ">Figure 2
<p>Stress–strain curve of 18Ni(350) (solution heat treatment: 820 °C for 1 h; aging treatment: 510 °C for 4 h).</p> Full article ">Figure 3
<p>Dimension of the flat cover (unit: mm).</p> Full article ">Figure 4
<p>Loading scheme of pressure test.</p> Full article ">Figure 5
<p>Photography of the cracked flat cover: (<b>a</b>) upper surface of the cover; (<b>b</b>) fracture surface in the outer edge of the cover.</p> Full article ">Figure 6
<p>Recorded strains in the three positions outside the shell with variations of pressure.</p> Full article ">Figure 7
<p>Inclusion morphology of the sample.</p> Full article ">Figure 8
<p>Metallographic structure of the cover sample: (<b>a</b>) low magnification; (<b>b</b>) high magnification.</p> Full article ">Figure 9
<p>SEM microstructure of the cover sample: (<b>a</b>) low magnification; (<b>b</b>) high magnification.</p> Full article ">Figure 10
<p>TEM microstructure of sealed top cover sample: (<b>a</b>) low magnification; (<b>b</b>) high magnification; (<b>c</b>) precipitated phase Fe<sub>2</sub>Mo morphology.</p> Full article ">Figure 11
<p>SEM morphology of crack source at the fracture surface of the flat cover: (<b>a</b>) low magnification morphology; (<b>b</b>) low magnification morphology at the crack source; (<b>c</b>) high magnification morphology at the crack source; (<b>d</b>) partially magnified morphology at the crack source.</p> Full article ">Figure 12
<p>Topography of cracking area of the flat cover: (<b>a</b>) low magnification morphology; (<b>b</b>) high magnification morphology.</p> Full article ">Figure 13
<p>Crack position at the right-angle transition root.</p> Full article ">Figure 14
<p>Δ<span class="html-italic">K</span> and Δ<span class="html-italic">K</span>(1 − <span class="html-italic">R</span>) values of 18Ni(350) determined by unstable crack growth properties.</p> Full article ">Figure 15
<p>Finite element model for stress analysis.</p> Full article ">Figure 16
<p>The position relationship between the sub-model and the global model.</p> Full article ">Figure 17
<p>Stress intensity factor along crack front with increasing external pressure.</p> Full article ">Figure 18
<p>Stress intensity factor at the surface points and the deepest point.</p> Full article ">
17 pages, 4601 KiB  
Article
A Study on a Mechanism of Lateral Pedestrian-Footbridge Interaction
by Zhou Chen, Siyuan Chen, Xijun Ye and Yunlai Zhou
Appl. Sci. 2019, 9(23), 5257; https://doi.org/10.3390/app9235257 - 3 Dec 2019
Cited by 6 | Viewed by 2390
Abstract
Based on the pedestrian lateral force hybrid Van der Pol/Rayleigh model, this study investigates the interaction dynamic model of a pedestrian-flexible footbridge lateral coupling system. A multi scale method is adopted to decouple the equation. The paper also studies the nonlinear dynamic response [...] Read more.
Based on the pedestrian lateral force hybrid Van der Pol/Rayleigh model, this study investigates the interaction dynamic model of a pedestrian-flexible footbridge lateral coupling system. A multi scale method is adopted to decouple the equation. The paper also studies the nonlinear dynamic response of the pedestrian-footbridge coupling system as well as the relationship between the lateral displacement of pedestrians and flexible footbridges, and the lateral interaction of the two variables. The results show that with the same frequency tuning parameters, when the mass ratio of pedestrians and footbridges is very small, the larger the mass ratio is, the larger the lateral response amplitude of pedestrians becomes. Conversely, when the mass ratio of pedestrians and footbridges is much larger, the larger the mass ratio is, the smaller the response amplitude becomes. When the natural frequency of a footbridge is larger, its Phase Angle becomes larger. As the lateral amplitude of pedestrians increases, the Phase Angle approaches zero. Moreover, regarding the variation of the Phase Angle between the interaction force and footbridge lateral vibration speed based on the lateral relative displacement of pedestrians, of which the variation range is (0, π ), as the pedestrians’ lateral amplitude increases, the Phase Angle approaches − π / 2 . The dynamic load coefficient varies linearly with the lateral amplitude of pedestrian vibrations. Full article
(This article belongs to the Special Issue Bridge Dynamics)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Lateral coupling of an individual pedestrian and a footbridge.</p> Full article ">Figure 2
<p>Effect of frequency tuning parameters on the Phase Angle between pedestrians and footbridges under different amplitude ratios.</p> Full article ">Figure 3
<p>Amplitude frequency curve of pedestrians’ lateral vibration.</p> Full article ">Figure 4
<p>Amplitude frequency curve of lateral vibration of the footbridge.</p> Full article ">Figure 5
<p>Phase frequency curve between pedestrians’ absolute displacement and footbridge displacement.</p> Full article ">Figure 6
<p>Phase Angle between interaction force and excitation speed.</p> Full article ">Figure 7
<p>Variation of the Phase Angle between pedestrians’ lateral absolute displacement and footbridge lateral vibration displacement according to the lateral relative displacement of pedestrians.</p> Full article ">Figure 8
<p>Variation of the Phase Angle between the interaction force and footbridge lateral vibration speed according to the lateral relative displacement of pedestrians.</p> Full article ">Figure 9
<p>Variation of pedestrian-footbridge interaction dynamic load factor <math display="inline"><semantics> <mi>α</mi> </semantics></math> according to pedestrians’ lateral relative displacement.</p> Full article ">Figure 10
<p>The impact of pedestrians’ lateral relative displacement on the ratio of pedestrians’ lateral absolute displacement to pedestrians’ lateral relative displacement.</p> Full article ">
12 pages, 1882 KiB  
Article
Architecture and Viability of the Biofilms Formed by Nine Listeria Strains on Various Hydrophobic and Hydrophilic Materials
by Cristina Rodríguez-Melcón, Carlos Alonso-Calleja and Rosa Capita
Appl. Sci. 2019, 9(23), 5256; https://doi.org/10.3390/app9235256 - 3 Dec 2019
Cited by 12 | Viewed by 4436
Abstract
Biofilms are a key factor in the persistence of Listeria in food processing plants, representing a potential source of foodstuff contamination. Nine Listeria strains (eight Listeria monocytogenes and one Listeria ivanovii) were studied by confocal laser scanning microscopy (CLSM) for their ability [...] Read more.
Biofilms are a key factor in the persistence of Listeria in food processing plants, representing a potential source of foodstuff contamination. Nine Listeria strains (eight Listeria monocytogenes and one Listeria ivanovii) were studied by confocal laser scanning microscopy (CLSM) for their ability to form biofilm on glass, polystyrene, graphene and resin after 120 h of incubation at 12 °C. The relationship between cell surface hydrophobicity and biofilm formation was also investigated. On comparing the data for all the strains, similar (P > 0.05) biovolume values were obtained on glass (average 3.39 ± 1.69 µm3/µm2) and graphene (2.93 ± 1.14 µm3/µm2), while higher (P < 0.05) values were observed for polystyrene (4.39 ± 4.14 µm3/µm2). The highest (P < 0.01) biovolume levels were found in the biofilms formed on resin (7.35 ± 1.45 µm3/µm2), which also had the smallest biomass of inactivated cells (0.38 ± 0.37 µm3/µm2 vs. 1.20 ± 1.12 µm3/µm2 on the remaining surfaces; P < 0.001). No relationship was noted between cell surface hydrophobicity and biofilm-forming ability. Full article
(This article belongs to the Special Issue Biofilms in Focus: A Threat to Foods)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Three-dimensional projections of the biofilm structures of nine <span class="html-italic">Listeria</span> spp. isolates on four materials (glass, polystyrene, graphene monolayer coating and epoxy resin coating). The biofilms were studied after 120 h of incubation at 12 °C. The images (126.8 µm × 126.8 µm) were reconstructed from confocal z-stacks using IMARIS software, with shadow projections to the right.</p> Full article ">Figure 2
<p>Box and whisker diagrams showing the distribution of the biovolume values observed for eight <span class="html-italic">L. monocytogenes</span> (LM) strains and one <span class="html-italic">L. ivanovii</span> (LI) strain. The boxes run from the 25th to the 75th percentile and are intersected by the median line. Whiskers extend below the box range, from the lowest to the highest values, respectively. Average values are indicated with (×). Outliers are indicated as individual data points (○). Average values in the same graph for the same physiological state (total, live or dead cells) with no letter in common are significantly different (<span class="html-italic">P</span> &lt; 0.05). In total, nine determinations were performed for each strain, contact material and physiological state.</p> Full article ">Figure 3
<p>Cell surface hydrophobicity values observed for cultures of eight <span class="html-italic">Listeria monocytogenes</span> (LM) strains and one <span class="html-italic">Listeria ivanovii</span> (LI) strain. Data are means ± standard deviations (SD) for eight determinations. Mean values with no letters in common are significantly different (<span class="html-italic">P &lt;</span> 0.05). LM26 (ATCC-American Type Culture Collection- 19112; serotype 1/2c), LM28 (ATCC 19111; serotype 1/2a), LM29 (ATCC 19114; serotype 4a), LM30 (ATCC 13932; serotype 4b), LM31 (STCC-Spanish Type Culture Collection- 936; serotype 1/2b), LM32 (STCC 937; serotype 3b), LM33 (STCC 938; serotype 3c), LM34 (ATCC 19117; serotype 4d), LI (ATCC 19119).</p> Full article ">
15 pages, 7262 KiB  
Article
Seismic Behavior of Steel Plate-Concrete Shear Walls with Holes
by Zhihua Chen, Jingshu Wu and Hongbo Liu
Appl. Sci. 2019, 9(23), 5255; https://doi.org/10.3390/app9235255 - 3 Dec 2019
Cited by 4 | Viewed by 3387
Abstract
Steel plate-concrete shear walls (SPSW) are used as the containment in nuclear power stations. However, the influence of holes and axial loading on the behavior of steel plate-concrete shear walls is neglected in most studies. Thus, it is necessary to understand the seismic [...] Read more.
Steel plate-concrete shear walls (SPSW) are used as the containment in nuclear power stations. However, the influence of holes and axial loading on the behavior of steel plate-concrete shear walls is neglected in most studies. Thus, it is necessary to understand the seismic behavior of SPSW members with holes in order to avoid the potential risks for nuclear power stations. In this study, a series of specimens were tested by low-cycle reciprocal loading. The specimens were designed with different holes to simulate real members in nuclear power stations. A hysteretic curve of specimens was obtained from a low-cycle reciprocal test to discuss the seismic behavior of steel plate-concrete shear walls (SPSW). Moreover, effects of axial compression ratio, hole size, thickness of the steel plate, and hole position on the hysteretic performance of SPSW were analyzed. The horizontal ultimate bearing capacity of SPSW specimens was estimated using the norms of the Architecture Institute of Japan and the calculation method of Ono reduction rate. Results provide theoretical references for the design and application of SPSW with holes. Full article
(This article belongs to the Special Issue Advanced Methods for Seismic Performance Evaluation of Building Structures)
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<p>Loading device (<b>a</b>) and measurement arrangement (<b>b</b>).</p> Full article ">Figure 2
<p>Typical flat specimens.</p> Full article ">Figure 3
<p>Typical I-shaped specimens.</p> Full article ">Figure 4
<p>Loading system.</p> Full article ">Figure 5
<p>Bucklingof side plates, pulling failure of weld joints, and concrete crushing of flat steel plate-concrete shear wall (SPSW) specimens with small holes.</p> Full article ">Figure 6
<p>Failuremodes of I-shaped SPSW specimens with large holes.</p> Full article ">Figure 6 Cont.
<p>Failuremodes of I-shaped SPSW specimens with large holes.</p> Full article ">Figure 7
<p>Hysteretic curve of specimens under different stress ratios. (<b>a</b>) SCW-3, (<b>b</b>) SCW-4, and (<b>c</b>) SCW-5.</p> Full article ">Figure 8
<p>Comparison of the skeleton curves of specimens of the same size under different axial compression ratios.</p> Full article ">Figure 9
<p>displacement curves of SPSW specimens with different hole sizes. (<b>a</b>) SCW-1, (<b>b</b>) SCW-3, (<b>c</b>) SCW-7, and (<b>d</b>) SCW-8.</p> Full article ">Figure 10
<p>Skeleton curves of SPSW specimens with different hole sizes.</p> Full article ">Figure 11
<p>Load displacement curve of specimens reinforced by different thicknesses of plates. (<b>a</b>) SCW-4 and (<b>b</b>) SCW-6.</p> Full article ">Figure 12
<p>Skeleton curves of specimens reinforced by different thicknesses of plates.</p> Full article ">Figure 13
<p>Hysteretic curves of specimens with holes at different positions. (<b>a</b>) SCW-8 and (<b>b</b>) SCW-9.</p> Full article ">Figure 14
<p>Skeleton curves of specimens with holes at different positions.</p> Full article ">Figure 15
<p>Effective supporting area in the Ono reduction rate calculation method.</p> Full article ">
17 pages, 3282 KiB  
Article
Modeling and Solution of the Routing Problem in Vehicular Delay-Tolerant Networks: A Dual, Deep Learning Perspective
by Roberto Hernández-Jiménez, Cesar Cardenas and David Muñoz Rodríguez
Appl. Sci. 2019, 9(23), 5254; https://doi.org/10.3390/app9235254 - 3 Dec 2019
Cited by 9 | Viewed by 2918
Abstract
The exponential growth of cities has brought important challenges such as waste management, pollution and overpopulation, and the administration of transportation. To mitigate these problems, the idea of the smart city was born, seeking to provide robust solutions integrating sensors and electronics, information [...] Read more.
The exponential growth of cities has brought important challenges such as waste management, pollution and overpopulation, and the administration of transportation. To mitigate these problems, the idea of the smart city was born, seeking to provide robust solutions integrating sensors and electronics, information technologies, and communication networks. More particularly, to face transportation challenges, intelligent transportation systems are a vital component in this quest, helped by vehicular communication networks, which offer a communication framework for vehicles, road infrastructure, and pedestrians. The extreme conditions of vehicular environments, nonetheless, make communication between nodes that may be moving at very high speeds very difficult to achieve, so non-deterministic approaches are necessary to maximize the chances of packet delivery. In this paper, we address this problem using artificial intelligence from a hybrid perspective, focusing on both the best next message to replicate and the best next hop in its path. Furthermore, we propose a deep learning–based router (DLR+), a router with a prioritized type of message scheduler and a routing algorithm based on deep learning. Simulations done to assess the router performance show important gains in terms of network overhead and hop count, while maintaining an acceptable packet delivery ratio and delivery delays, with respect to other popular routing protocols in vehicular networks. Full article
(This article belongs to the Special Issue Artificial Intelligence Applications to Smart City and Smart Enterprise)
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<p>Opportunistic encounters for routing in vehicular delay tolerant networks (VDTN) and the message queue in a host.</p> Full article ">Figure 2
<p>The fundamental routing architecture of a deep learning–based router (DLR+).</p> Full article ">Figure 3
<p>Architecture of the neural networks used in the host’s fitness center: (<b>a</b>) Neural network used to calculate the host’s fitness; (<b>b</b>) neural network used to compute the messages’ fitness.</p> Full article ">Figure 4
<p>The roads and streets used in the simulation.</p> Full article ">Figure 5
<p>Effect of the fitness thresholds in packet delivery ratio (<b>a</b>) and average delivery delay (<b>b</b>).</p> Full article ">Figure 6
<p>Effect of the fitness threshold in network overhead (<b>a</b>) and hop count (<b>b</b>).</p> Full article ">Figure 7
<p>Performance of DLR+ in packet delivery ratio (<b>a</b>) and average delivery delay (<b>b</b>).</p> Full article ">Figure 8
<p>Performance of DLR+ in network overhead (<b>a</b>) and hop count (<b>b</b>).</p> Full article ">
18 pages, 2549 KiB  
Article
Supplier Selection and Performance Evaluation for High-Voltage Power Film Capacitors in a Fuzzy Environment
by Chun-Ming Yang, Kuen-Suan Chen, Ting-Hsin Hsu and Chang-Hsien Hsu
Appl. Sci. 2019, 9(23), 5253; https://doi.org/10.3390/app9235253 - 3 Dec 2019
Cited by 8 | Viewed by 3358
Abstract
Rapid advances in technology have shortened the upgrade and replacement cycles in industries such as electronics, household appliances, and communication technologies. Within these industries, high-voltage power film capacitors have become indispensable electrical components due to their good electrical performance and high reliability. The [...] Read more.
Rapid advances in technology have shortened the upgrade and replacement cycles in industries such as electronics, household appliances, and communication technologies. Within these industries, high-voltage power film capacitors have become indispensable electrical components due to their good electrical performance and high reliability. The selection and evaluation of suppliers of these capacitors is therefore increasingly important. Suppliers play a crucial role in the electronics industry; the quality of their products determines the degree to which the quality of the final product can be guaranteed. Supplier quality also affects the ability of all the members in a supply chain to control costs. Evaluation by decision-makers is highly significant in the supplier selection process. However, when the opinions of multiple decision-makers are combined, issues such as cognitive differences, fuzzy linguistics, and uncertainty are common. This study presents a supplier performance index SPL and derives the estimates of the index SPL and its statistical properties. The proposed index is not only helpful for the accurate measurement of supplier performance; it can also reduce cognitive differences among evaluators in the decision-making process (that is, the sample variability associated with the Likert scale). Evaluation scores for each criterion for the linguistic labels are converted to triangular fuzzy numbers in order to reduce ambiguity. Subsequently, integrated crisp values are obtained by defuzzification in a fuzzy inference system. A real-world case study of the supplier selection of high-voltage power film capacitors is provided to illustrate the efficacy of the proposed method. Full article
(This article belongs to the Special Issue Industrial Engineering and Management: Current Issues and Trends)
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<p>Triangular number fuzzy (TNF).</p> Full article ">Figure 2
<p>Fuzzy inference process.</p> Full article ">Figure 3
<p>Input linguistic labels.</p> Full article ">Figure 4
<p>Output crisp numerical values.</p> Full article ">Figure 5
<p>Fuzzy rule.</p> Full article ">Figure 6
<p>High-voltage power film capacitor.</p> Full article ">
12 pages, 864 KiB  
Article
Potential of Advanced Consolidants for the Application on Sandstone
by Monika Remzova, Radek Zouzelka, Jaroslav Lukes and Jiri Rathousky
Appl. Sci. 2019, 9(23), 5252; https://doi.org/10.3390/app9235252 - 3 Dec 2019
Cited by 13 | Viewed by 2385
Abstract
Alkoxy-based consolidants are widely used for conservation of cultural heritage objects made from sandstones. Even if such consolidants were introduced into practice already in the 19th century, their performance has been enhanced by several modifications to their composition only recently. To obtain a [...] Read more.
Alkoxy-based consolidants are widely used for conservation of cultural heritage objects made from sandstones. Even if such consolidants were introduced into practice already in the 19th century, their performance has been enhanced by several modifications to their composition only recently. To obtain a relevant comparison of their application potential, both commercial (Remmers KSE OH and SurfaPore FX SB) and a self-developed particle-modified ethyl silicate consolidant supplemented with two phosphate-based ones, were assessed. Importantly, the potential toxicity of our novel consolidants was considered. Since the stone substrate should mimic the properties of naturally weathered stone, sandstone from the Msene quarry in Central Bohemia, characterized by a high porosity and relatively low mechanical strength, is selected. From practical point of view, the long-term durability of the consolidation effect is crucial compared to the initial level of consolidation. Regarding the determination of durability of the sandstone consolidation according to an American Society for Testing and Materials (ASTM) accelerated weathering test, we performed mechanical tests in micro- (nanoindentation) and macroscale (drilling resistance measurements). The cohesion of the consolidant xerogels in the pores were determined by sorption experiments in gas phase. The durability of our TiO2 and ZnO particle-modified consolidants is superior to that of the commercial products. The aqueous diammonium hydrogen phosphate-based consolidant, which also shows exceptional durability, reveals itself to be a promising product for not only carbonate but also sandstone materials. Full article
(This article belongs to the Section Civil Engineering)
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<p>Mechanical properties of the xerogel on a microscale level. (<b>a</b>) Variation of the storage modulus with the sweep frequency; (<b>b</b>) load-displacement curves; (<b>c</b>) Dependence of Young’s modulus (<b>c</b>) and hardness (<b>d</b>) on indent displacement.</p> Full article ">Figure 2
<p>Effect of weathering on the consistency of the xerogels. (<b>a</b>) fresh; (<b>b</b>) after one WAT cycle; (<b>c</b>) after two WAT cycles.</p> Full article ">
15 pages, 8959 KiB  
Article
Multiscale Damage Evolution Analysis of Aluminum Alloy Based on Defect Visualization
by Yuquan Bao, Yali Yang, Hao Chen, Yongfang Li, Jie Shen and Shuwei Yang
Appl. Sci. 2019, 9(23), 5251; https://doi.org/10.3390/app9235251 - 3 Dec 2019
Cited by 7 | Viewed by 2598
Abstract
The evaluation of fatigue life through the mechanism of fatigue damage accumulation is still a challenging task in engineering structure failure analysis. A multiscale fatigue damage evolution model was proposed for describing both the mesoscopic voids propagation in the mesoscopic-scale and fatigue damage [...] Read more.
The evaluation of fatigue life through the mechanism of fatigue damage accumulation is still a challenging task in engineering structure failure analysis. A multiscale fatigue damage evolution model was proposed for describing both the mesoscopic voids propagation in the mesoscopic-scale and fatigue damage evolution process, reflecting the progressive degradation of metal components in the macro-scale. An effective method of defect classification was used to implement 3D reconstruction technology based on the MCT (micro-computed tomography) scanning damage data with ABAQUS subroutine. The effectiveness was validated through the comparison with the experimental data of fatigue damage accumulation. Our results indicated that the multiscale fatigue damage evolution model built a bridge between mesoscopic damage and macroscopic fracture, which not only used the damage variable in the macro-scale to characterize the mesoscopic damage evolution indirectly but also understood macroscopic material degradation behavior from mesoscale with sufficient precision. Furthermore, the multiscale fatigue damage evolution model could offer a new reasonable explanation of the effect of load sequence on fatigue life, and also could predict the fatigue life based on damage data by nondestructive testing techniques. Full article
(This article belongs to the Special Issue Fracture and Fatigue Assessments of Structural Components)
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<p>Specimens (<b>a</b>) Two-dimensions size of the specimens. (<b>b</b>) Three-dimensional view of the specimens.</p> Full article ">Figure 2
<p>MTS (Systems Corporation) fatigue tensile testing machine.</p> Full article ">Figure 3
<p>Test specimens.</p> Full article ">Figure 4
<p>X-ray micro-computed tomography system.</p> Full article ">Figure 5
<p>TIF slice diagram with different volume defects.</p> Full article ">Figure 6
<p>The flow chart of modular processing.</p> Full article ">Figure 7
<p>TIF diagram display. (<b>a</b>) TIF diagram after positioning display processing, (<b>b</b>) TIF diagram after noise filtering, (<b>c</b>) TIF diagram after threshold segmentation processing.</p> Full article ">Figure 8
<p>The 3D visualization of internal void defects for specimen labeled 8-3 from different perspectives.</p> Full article ">Figure 9
<p>Variation of the voids damage characterization with the number of cycles N. (<b>a</b>) Variation of the total number of voids with the number of cycles N. (<b>b</b>) Variation of the volume of maximum void with the number of cycles N. (<b>c</b>) Variation of the maximum damage surface area with the number of cycles N. (<b>d</b>) Variation of the Porosity with the number of cycles N.</p> Full article ">Figure 9 Cont.
<p>Variation of the voids damage characterization with the number of cycles N. (<b>a</b>) Variation of the total number of voids with the number of cycles N. (<b>b</b>) Variation of the volume of maximum void with the number of cycles N. (<b>c</b>) Variation of the maximum damage surface area with the number of cycles N. (<b>d</b>) Variation of the Porosity with the number of cycles N.</p> Full article ">Figure 10
<p>Schematic diagram of the distance between the base point voids and the reference point voids.</p> Full article ">Figure 11
<p>Schematic diagram of the equivalent damage model created by ABAQUS subroutine for specimen labeled 8-3.</p> Full article ">Figure 12
<p>The tensile simulation results of damage model of specimens labeled 8-3. (<b>a</b>) Stress cloud map, (<b>b</b>) strain cloud map.</p> Full article ">Figure 13
<p>The verification of the fatigue damage evolution model.</p> Full article ">Figure 14
<p>(<b>a</b>) Variation of Young’s damage modulus E<sub>d</sub> with the number of cycles N. (<b>b</b>) Variation of the damage variable D with the number of cycles N.</p> Full article ">
15 pages, 4308 KiB  
Article
Calculation Model of High-Pressure Water Jet Slotting Depth for Coalbed Methane Development in Underground Coal Mine
by Jianguo Zhang, Yingwei Wang, Zhaolong Ge, Songqiang Xiao, Hanyun Zhao and Xiaobo Huang
Appl. Sci. 2019, 9(23), 5250; https://doi.org/10.3390/app9235250 - 3 Dec 2019
Cited by 7 | Viewed by 2598
Abstract
In underground coal mines, high-pressure water jet slotting is effective at improving coal seams’ permeability. The slotting depth determines the effect of pressure relief and permeability enhancement in coal seams. However, there is no effective and feasible way of determining the slotting depth; [...] Read more.
In underground coal mines, high-pressure water jet slotting is effective at improving coal seams’ permeability. The slotting depth determines the effect of pressure relief and permeability enhancement in coal seams. However, there is no effective and feasible way of determining the slotting depth; thus, the operational parameters and borehole layout are unknown. This study determined the effects of key parameters, including the nozzle diameter, jet pressure, rotation speed, and slotting time, on the slotting depth. A water jet slotting depth calculation model was established and verified according to the slotting experiments under different operational conditions. The slotting depths were investigated based on the results of field slotting experiments. The results revealed that there exists an optimal nozzle diameter for a higher jet impact velocity. The slotting depth linearly increased with the jet pressure and decreased as a power function with the increase of the jet translation speed. The slotting depth increased with the slotting time, but the growth rate gradually decreased and tended to be stable. As the rotation speed increased, the slotting depth became greater at the initial period and the limit depth was reached faster. Laboratory and field slotting experiments were conducted to verify the model, and the experimental results are approximately in agreement with the theoretical predictions. The results of this study can be useful as guidelines for the hydraulic parameter selection of water jet slotting and for optimizing the layout of coal gas drainage boreholes. Full article
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<p>Technical sketch of coal seam permeability improvement by water jet slotting. (<b>a</b>) is the process of high-pressure water jet slotting in coal seams; (<b>b</b>) is the crack condition surrounding the slots.</p> Full article ">Figure 2
<p>(<b>a</b>) Axial velocity and (<b>b</b>) axial dynamic pressure of a water jet with different nozzle diameters [<a href="#B28-applsci-09-05250" class="html-bibr">28</a>].</p> Full article ">Figure 3
<p>System used in cutting experiment.</p> Full article ">Figure 4
<p>Comparison of cutting depth subjected to high-pressure water jet with different jet pressures.</p> Full article ">Figure 5
<p>The effect of jet pressure on cutting depth.</p> Full article ">Figure 6
<p>The effect of translation speed on cutting depth.</p> Full article ">Figure 7
<p>Cutting depths from a high-pressure water jet with different translation speeds.</p> Full article ">Figure 8
<p>The effect of cutting times on cutting depth [<a href="#B31-applsci-09-05250" class="html-bibr">31</a>].</p> Full article ">Figure 9
<p>System used in experiment of rotary slotting by water jet.</p> Full article ">Figure 10
<p>Slotting depth at different rotation speeds.</p> Full article ">Figure 11
<p>Fitting curves between slotting depth and slotting time at different rotation speeds under jet pressure of 10 MPa.</p> Full article ">Figure 12
<p>Prediction curves of slotting depth versus slotting time at different rotation speeds under jet pressure of 25 MPa.</p> Full article ">Figure 13
<p>Site of water jet slotting field test: Shoushan Number 1 coal mine affiliated with Pingdingshan Coal Group Co. Ltd.</p> Full article ">Figure 14
<p>Layout of slotting borehole and inspection holes.</p> Full article ">
16 pages, 4559 KiB  
Article
Adsorption of Ammonium Nitrogen from Aqueous Solution on Chemically Activated Biochar Prepared from Sorghum Distillers Grain
by Derlin Hsu, Changyi Lu, Tairan Pang, Yuanpeng Wang and Guanhua Wang
Appl. Sci. 2019, 9(23), 5249; https://doi.org/10.3390/app9235249 - 3 Dec 2019
Cited by 43 | Viewed by 4650
Abstract
Chemically activated biochars prepared from sorghum distillers grain using two base activators (NaOH and KOH) were investigated for their adsorption properties with respect to ammonium nitrogen from aqueous solution. Detailed characterizations, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction [...] Read more.
Chemically activated biochars prepared from sorghum distillers grain using two base activators (NaOH and KOH) were investigated for their adsorption properties with respect to ammonium nitrogen from aqueous solution. Detailed characterizations, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetry (TG), and specific surface area analyses, were carried out to offer a broad evaluation of the prepared biochars. The results showed that the NaOH- and KOH-activated biochars exhibited significantly enhanced adsorption capacity, by 2.93 and 4.74 times, respectively, in comparison with the pristine biochar. Although the NaOH-activated biochar possessed larger specific surface area (132.8 and 117.7 m2/g for the NaOH- and KOH-activated biochars, respectively), the KOH-activated biochar had higher adsorption capacity owing to its much higher content of functional groups. The adsorption kinetics and isotherms of the KOH-activated biochar at different temperatures were further studied. The biochar had a maximum adsorption capacity of 14.34 mg/g at 45 °C, which was satisfactory compared with other biochars prepared using different feedstocks. The adsorption process followed pseudo-second-order kinetics, and chemical adsorption was the rate-controlling step. The equilibrium data were consistent with the Freundlich isotherm, and the thermodynamic parameters suggested that the adsorption process was endothermic and spontaneous. Consequently, this work demonstrates that chemically activated biochar from sorghum distillers grain is effective for ammonium nitrogen removal. Full article
(This article belongs to the Special Issue Advanced or Conventional Materials as Sorbent)
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<p>Effect of activators on the yield and NH<sub>4</sub><sup>+</sup>-N adsorption of biochar from sorghum distillers grain (<b>a</b>); Effect of pyrolysis temperature on the yield and NH<sub>4</sub><sup>+</sup>-N adsorption of KOH-activated biochar from sorghum distillers grain (<b>b</b>).</p> Full article ">Figure 2
<p>Effect of solution pH on NH<sub>4</sub><sup>+</sup>-N adsorption and the zeta potential of biochar (adsorption conditions: NH<sub>4</sub><sup>+</sup>-N, 100 mg/L; biochar dosage, 4 g/L; temperature, 25 °C).</p> Full article ">Figure 3
<p>(<b>a</b>) Adsorption kinetics of NH<sub>4</sub><sup>+</sup>-N onto biochar (NH<sub>4</sub><sup>+</sup>-N: 100 mg/L, biochar dosage: 4 g/L, temperature: 25–45 °C), as well as the fitting curves using pseudo-first-order and pseudo-second-order models. (<b>b</b>) Langmuir and Freundlich equilibrium adsorption isotherms for the adsorption of NH<sub>4</sub><sup>+</sup>-N onto biochar (adsorbent dose: 4 g/L, temperature: 25–45 °C).</p> Full article ">Figure 4
<p>SEM images of NaOH-activated biochar (<b>a</b>,<b>b</b>) and KOH-activated biochar (<b>d</b>,<b>e</b>), (<b>c</b>,<b>f</b>) represent the NOH-activated biochar and KOH-activated biochar, respectively, after ammonium nitrogen adsorption.</p> Full article ">Figure 5
<p>Nitrogen adsorption–desorption isotherms of NaOH-activated biochar and KOH-activated biochar.</p> Full article ">Figure 6
<p>XRD patterns of NaOH-activated biochar before (<b>a</b>) and after (<b>b</b>) ammonium nitrogen adsorption and KOH-activated biochar before (<b>c</b>) and after (<b>d</b>) ammonium nitrogen adsorption.</p> Full article ">Figure 7
<p>Thermogravimetric curves of sorghum distillers grain (SDG), NaOH-activated biochar, and KOH-activated biochar.</p> Full article ">Figure 8
<p>FTIR spectra of NaOH-activated biochar and KOH-activated biochar.</p> Full article ">
13 pages, 5032 KiB  
Article
Diesel Spray Macroscopic Parameter Estimation Using a Synthetic Shapes Database
by Andrea Bottega and Claudio Dongiovanni
Appl. Sci. 2019, 9(23), 5248; https://doi.org/10.3390/app9235248 - 2 Dec 2019
Cited by 1 | Viewed by 2042
Abstract
The paper presents a method for the macroscopic characterization of diesel sprays starting from digital images. Macroscopic spray characterization mainly consists in the definition of two parameters, namely penetration and cone angle. The latter can be evaluated according to many possible definitions, all [...] Read more.
The paper presents a method for the macroscopic characterization of diesel sprays starting from digital images. Macroscopic spray characterization mainly consists in the definition of two parameters, namely penetration and cone angle. The latter can be evaluated according to many possible definitions, all based on the spray contour that is obtained by means of image thresholding. Therefore, the obtained cone angle value depends on the adopted angle definition and on the used thresholding algorithm. In order to avoid this double dependence, an alternative method has hence been proposed. The algorithm does not require the image thresholding and has an intrinsic cone angle definition. The algorithm takes advantage of principal component analysis technique and allows for a direct estimation of spray penetration and cone angle by comparing the original image with a database made of artificial spray images. In the present work, images coming from two different experiments are analyzed with the proposed method and results are compared with those obtained with a traditional procedure based on the Otsu’s image thresholding and four cone angle definitions. Full article
(This article belongs to the Section Energy Science and Technology)
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<p>Generic definition of macroscopic spray parameters.</p> Full article ">Figure 2
<p>Transverse (<b>a</b>–<b>c</b>) and longitudinal (<b>d</b>) intensity profile of a typical diesel spray image.</p> Full article ">Figure 3
<p>Artificial spray parametrization.</p> Full article ">Figure 4
<p>(<b>a</b>) Original Image. (<b>b</b>) Reconstructed version using database.</p> Full article ">Figure 5
<p>Cumulative normalized sum of the eigenvalues.</p> Full article ">Figure 6
<p>(<b>a</b>) Original image. In red pixels columns for background estimation. (<b>b</b>) Estimated background (intensity adjusted for visualization purposes).</p> Full article ">Figure 7
<p>Penetration estimation for scaling.</p> Full article ">Figure 8
<p>(<b>a</b>) Original image. (<b>b</b>) Scaled Image.</p> Full article ">Figure 9
<p>Spay contour evaluated by using the proposed method at different time step.</p> Full article ">Figure 10
<p>Experimental layout.</p> Full article ">Figure 11
<p>Test A: Penetration and cone angle temporal evolution.</p> Full article ">Figure 12
<p>Test B: Penetration and cone angle temporal evolution.</p> Full article ">Figure 13
<p>Intensity level effect.</p> Full article ">Figure 14
<p>Test A: Comparison of the cone angle trends for the different methods.</p> Full article ">Figure 15
<p>Test B: Comparison of the cone angle trends for the different methods.</p> Full article ">Figure 16
<p>Test A: Effect of the thresholding algorithm.</p> Full article ">
11 pages, 2088 KiB  
Article
A High Peak Power and High Beam Quality Sub-Nanosecond Nd:YVO4 Laser System at 1 kHz Repetition Rate without SRS Process
by Yutao Huang, Hongbo Zhang, Xiaochao Yan, Zhijun Kang, Fuqiang Lian and Zhongwei Fan
Appl. Sci. 2019, 9(23), 5247; https://doi.org/10.3390/app9235247 - 2 Dec 2019
Cited by 6 | Viewed by 3857
Abstract
We present a compact sub-nanosecond diode-end-pumped Nd:YVO4 laser system running at 1 kHz. A maximum output energy of 65.4 mJ without significant stimulated Raman scattering (SRS) process was obtained with a pulse duration of 600 ps, corresponding to a pulse peak power [...] Read more.
We present a compact sub-nanosecond diode-end-pumped Nd:YVO4 laser system running at 1 kHz. A maximum output energy of 65.4 mJ without significant stimulated Raman scattering (SRS) process was obtained with a pulse duration of 600 ps, corresponding to a pulse peak power of 109 MW. Laser pulses from this system had good beam quality, where M2 < 1.6, and the excellent signal to noise ratio was more than 42 dB. By frequency doubling with an LBO crystal, 532 nm green light with an average power of 40.5 W and a power stability of 0.28% was achieved. The diode-end-pumped pump power limitation on a high peak power amplifier caused by the SRS process and thermal fracture in bulk Nd:YVO4 crystal is also analyzed. Full article
(This article belongs to the Special Issue Modern Applications in Optics and Photonics: From Sensing and Analytics to Communication)
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<p>Schematic of the laser system. PBS: polarization beam splitter; FR: Faraday rotator; HWP: half-wave plate; BE: beam expander; TFP: thin-film plate; LD: laser diode.</p> Full article ">Figure 2
<p>Signal to noise ratio and pre-pulse energy at different amplifiers when a regenerative amplifier was used as the pre-amplifier.</p> Full article ">Figure 3
<p>Time signal to noise ratio of maximum output energy: (<b>a</b>) Pre-pulse amplitude when the photodetector was overexposed; (<b>b</b>) main pulse amplitude when the photodetector was operated in the linear range.</p> Full article ">Figure 4
<p>Obtained spectrum of first Stokes wave of Raman light as high intensity laser passing through the Nd:YVO<sub>4</sub> crystal.</p> Full article ">Figure 5
<p>The relationship between the maximum pump power and the maximum laser intensity in an end-pumped Nd:YVO<sub>4</sub> amplifier at a QCW pump duty cycle of 10%.</p> Full article ">Figure 6
<p>Obtained spectrum of the maximum laser output.</p> Full article ">Figure 7
<p>Pulse spectrum of: (<b>a</b>) the oscillator (<b>b</b>) via the amplifying system.</p> Full article ">Figure 8
<p>Pulse temporal width of: (<b>a</b>) the oscillator (<b>b</b>) via the amplifying system.</p> Full article ">Figure 9
<p>Beam images of each stage. (<b>a</b>) pre-amplifier; (<b>b</b>) stage 1 in main amplifier; (<b>c</b>) stage 2 in main amplifier; (<b>d</b>) stage 3 in main amplifier.</p> Full article ">Figure 10
<p>Beam quality factor M<sup>2</sup> of (<b>a</b>) the oscillator (<b>b</b>) via the amplifying system.</p> Full article ">Figure 11
<p>Energy stability of amplified pulses from the whole amplifier.</p> Full article ">Figure 12
<p>Beam quality factor M<sup>2</sup> of green light. The insets show the beam distribution of green light.</p> Full article ">
11 pages, 1331 KiB  
Article
Respiration Monitoring for Premature Neonates in NICU
by Yue Sun, Wenjin Wang, Xi Long, Mohammed Meftah, Tao Tan, Caifeng Shan, Ronald M. Aarts and Peter H. N. de With
Appl. Sci. 2019, 9(23), 5246; https://doi.org/10.3390/app9235246 - 2 Dec 2019
Cited by 13 | Viewed by 4527
Abstract
In this paper, we investigate an automated pipeline to estimate respiration signals from videos for premature infants in neonatal intensive care units (NICUs). Two flow estimation methods, namely the conventional optical flow- and deep learning-based flow estimation methods, were employed and compared to [...] Read more.
In this paper, we investigate an automated pipeline to estimate respiration signals from videos for premature infants in neonatal intensive care units (NICUs). Two flow estimation methods, namely the conventional optical flow- and deep learning-based flow estimation methods, were employed and compared to estimate pixel motion vectors between adjacent video frames. The respiratory signal is further extracted via motion factorization. The proposed methods were evaluated by comparing our automated extracted respiration signals to that extracted from chest impedance on videos of five premature infants. The overall average cross-correlation coefficients are 0.70 for the optical flow-based method and 0.74 for the deep flow-based method. The average root mean-squared errors are 6.10 and 4.55 for the optical flow- and the deep flow-based methods, respectively. The experimental results are promising for further investigation and clinical application of the video-based respiration monitoring method for infants in NICUs. Full article
(This article belongs to the Section Applied Physics General)
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<p>Example of an acquired video frame.</p> Full article ">Figure 2
<p>Flowchart of the proposed video-based respiration monitoring system.</p> Full article ">Figure 3
<p>Framework of deep flow.</p> Full article ">Figure 4
<p>Monitored respiration from the CI, and corresponding extracted respiration signals from a segment, based on optical flow and deep flow.</p> Full article ">Figure 5
<p>Data patterns for chest impedance and video-based observation: (<b>a</b>) re-scaled 1D signals; and (<b>b</b>) zoom in of each interval indicated in (<b>a</b>).</p> Full article ">Figure 6
<p>Correlation and Bland–Altman plots comparing respiration rate measurements derived from: (<b>a</b>) the CI and optical flow-based method; and (<b>b</b>) the CI and deep flow-based method. The correlation plots contain the linear regression equation, correlation coefficient (<math display="inline"><semantics> <msup> <mi>r</mi> <mn>2</mn> </msup> </semantics></math>), sum of squared error (SSE), and number of points. The Bland–Altman plots contain the reproducibility coefficient (RPC = <math display="inline"><semantics> <mrow> <mn>1.96</mn> <mo>∗</mo> <mi>σ</mi> </mrow> </semantics></math>), and also show the coefficient of variation (CV = the standard deviation (<math display="inline"><semantics> <mi>σ</mi> </semantics></math>) as a percentage of the mean), limits of agreement (LOA = <math display="inline"><semantics> <mrow> <mo>±</mo> <mn>1.96</mn> <mo>∗</mo> <mi>σ</mi> </mrow> </semantics></math>), and the bias offset of the measures.</p> Full article ">
22 pages, 8774 KiB  
Article
Effects of Toe-Out and Toe-In Gaits on Lower-Extremity Kinematics, Dynamics, and Electromyography
by Weiling Cui, Changjiang Wang, Weiyi Chen, Yuan Guo, Yi Jia, Weijin Du and Chenyan Wang
Appl. Sci. 2019, 9(23), 5245; https://doi.org/10.3390/app9235245 - 2 Dec 2019
Cited by 15 | Viewed by 9056
Abstract
Toe-in and toe-out gait modifications have received increasing attention as an effective, conservative treatment for individuals without severe osteoarthritis because of its potential for improving knee adduction moment (KAM) and knee flexion moment (KFM). Although toe-in and toe-out gaits have positive effects on [...] Read more.
Toe-in and toe-out gait modifications have received increasing attention as an effective, conservative treatment for individuals without severe osteoarthritis because of its potential for improving knee adduction moment (KAM) and knee flexion moment (KFM). Although toe-in and toe-out gaits have positive effects on tibiofemoral (TF) joint pain in the short term, negative impacts on other joints of the lower extremity may arise. The main purpose of this study was to quantitatively compare the effects of foot progression angle (FPA) gait modification with normal walking speeds in healthy individuals on lower-extremity joint, ground reaction force (GRF), muscle electromyography, joint moment, and TF contact force. Experimental measurements using the Vicon system and multi-body dynamics musculoskeletal modelling using OpenSim were conducted in this study. Gait analysis of 12 subjects (n = 12) was conducted with natural gait, toe-in gait, and toe-out gait. One-way repeated measures of ANOVA (p < 0.05) with Tukey’s test was used for statistical analysis. Results showed that the toe-in and toe-out gait modifications decreased the max angle of knee flexion by 8.8 and 12.18 degrees respectively (p < 0.05) and the max angle of hip adduction by 1.28 and 0.99 degrees respectively (p < 0.05) compared to the natural gait. Changes of TF contact forces caused by FPA gait modifications were not statistically significant; however, the effect on KAM and KFM were significant (p < 0.05). KAM or combination of KAM and KFM can be used as surrogate measures for TF medial contact force. Toe-in and toe-out gait modifications could relieve knee joint pain probably due to redistribution of TF contact forces on medial and lateral condylar through changing lateral contact centers and shifting bilateral contact locations. Full article
(This article belongs to the Section Applied Biosciences and Bioengineering)
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<p>(<b>a</b>) Surface markers (blue circle) and electromyography (EMG) electrodes (red circle) used for trials and (<b>b</b>) musculoskeletal model of the lower extremity.</p> Full article ">Figure 2
<p>Schematic diagram for foot progression angle in the toe-out and toe-in gait patterns: L represents the left foot position, R the right foot position, and the arrow represents the forward direction while walking.</p> Full article ">Figure 3
<p>Measured joint angles (mean and standard deviation) of a gait cycle for the natural, toe-in, and toe-out gait patterns (12 participants and 5 trials for each gait pattern).</p> Full article ">Figure 4
<p>Measured ground reaction forces (GRFs; mean and standard deviation) of the stance phase for the natural, toe-in, and toe-out gait patterns (12 participants and 5 trials for each gait patterns).</p> Full article ">Figure 5
<p>Joint moments (mean and standard deviation) calculated from the musculoskeletal model for the natural, toe-in, and toe-out gait patterns (12 participants and 5 trials for each gait patterns).</p> Full article ">Figure 6
<p>Knee joint reaction forces (JRFs; mean and standard deviation) calculated from the musculoskeletal model for the natural, toe-in, and toe-out gait patterns (12 participants and 5 trials for each gait patterns).</p> Full article ">Figure A1
<p>Peak EMGs/activations of nine muscles for subject 1.</p> Full article ">Figure A2
<p>Peak EMGs/activations of nine muscles for subject 2.</p> Full article ">Figure A3
<p>Peak EMGs/activations of nine muscles for subject 3.</p> Full article ">Figure A4
<p>Peak EMGs/activations of nine muscles for subject 4.</p> Full article ">Figure A5
<p>Peak EMGs/activations of nine muscles for subject 5.</p> Full article ">Figure A6
<p>Peak EMGs/activations of nine muscles for subject 6.</p> Full article ">Figure A7
<p>Peak EMGs/activations of nine muscles for subject 7.</p> Full article ">Figure A8
<p>Peak EMGs/activations of nine muscles for subject 8.</p> Full article ">Figure A9
<p>Peak EMGs/activations of nine muscles for subject 9.</p> Full article ">Figure A10
<p>Peak EMGs/activations of nine muscles for subject 10.</p> Full article ">Figure A11
<p>Peak EMGs/activations of nine muscles for subject 11.</p> Full article ">Figure A12
<p>Peak EMGs/activations of nine muscles for subject 12.</p> Full article ">
15 pages, 6582 KiB  
Article
Numerical Simulation of the Tip Leakage Vortex Characteristics in a Semi-Open Centrifugal Pump
by Like Wang, Jinling Lu, Weili Liao, Yaping Zhao and Wei Wang
Appl. Sci. 2019, 9(23), 5244; https://doi.org/10.3390/app9235244 - 2 Dec 2019
Cited by 33 | Viewed by 3166
Abstract
Tip leakage vortex has an important influence on the performance of semi-open centrifugal pumps. Simulations based on the three-dimensional Reynolds-Averaged Navier–Stokes were conducted to study the structural characteristics of tip leakage vortex and its effects on the internal flow field, and the Shear [...] Read more.
Tip leakage vortex has an important influence on the performance of semi-open centrifugal pumps. Simulations based on the three-dimensional Reynolds-Averaged Navier–Stokes were conducted to study the structural characteristics of tip leakage vortex and its effects on the internal flow field, and the Shear Stress Transport k-ω turbulence model was used to simulate the whole flow passage of centrifugal pumps with tip clearances of 0 mm and 1 mm. Then, the tip leakage vortex was analyzed using the relative vorticity transport equation. The numerical data and experimental results agreed well. The leakage vortex formed in the tip clearance led to 18.7% and 14.4% decrease in head and efficiency under design condition, respectively, and the bigger the flow rate, the fast the performance decreased. Tip leakage vortex formed at the leading edge of the blade moved along the suction surface. Whereas the tip leakage vortex formed near the middle of the blade extended to the pressure surface of the adjacent blade. This phenomenon deteriorated the flow field and induced passage vortex, thereby reducing the static pressure and blade load and changing the static pressure distribution law. The formation and development of leakage vortex could be attributed to the relative vortex stretching the term. The Coriolis force term could reflect the change of vorticity caused by leakage flow, and the viscous diffusion term served as the vorticity source. Full article
(This article belongs to the Section Energy Science and Technology)
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<p>Computational domain of the pump.</p> Full article ">Figure 2
<p>Impeller meridional shape.</p> Full article ">Figure 3
<p>Closed test loop.</p> Full article ">Figure 4
<p>Mesh analysis for NTC (without tip clearance) and TC (tip clearance). (<b>a</b>) NTC, (<b>b</b>) TC.</p> Full article ">Figure 5
<p>Computational domain grids of a centrifugal pump. (<b>a</b>) Impeller, (<b>b</b>) Leading edge of the blade, (<b>c</b>) Trailing edge of the blade.</p> Full article ">Figure 6
<p>Comparison of the head between experimental and numerical results.</p> Full article ">Figure 7
<p>External characteristics of TC and NTC.</p> Full article ">Figure 8
<p>Streamline distribution of NTC on different span planes. (<b>a</b>) Span = 0.05, (<b>b</b>) Span = 0.5, (<b>c</b>) Span = 0.95.</p> Full article ">Figure 9
<p>Streamline distribution of TC on different span planes. (<b>a</b>) Span = 0.05, (<b>b</b>) Span = 0.5, (<b>c</b>) Span = 0.95.</p> Full article ">Figure 10
<p>Relative flow angle distribution of the blade leading edge on different span planes. (<b>a</b>) Span = 0.05, (<b>b</b>) Span = 0.5, (<b>c</b>) Span = 0.95.</p> Full article ">Figure 11
<p>Static pressure coefficient distribution on the blade surface on different span planes. (<b>a</b>) Span = 0.05, (<b>b</b>) Span = 0.5, (<b>c</b>) Span = 0.95.</p> Full article ">Figure 12
<p>Vortex structure defined by the Q criterion (Q = 1.0 × 10<sup>5</sup> s<sup>−2</sup>).</p> Full article ">Figure 13
<p>Tip streamline’s distribution of tip clearance vortex.</p> Full article ">Figure 14
<p>Distribution of relative vortex stretching term on different span planes.</p> Full article ">Figure 15
<p>Distribution of Coriolis force term on different span planes.</p> Full article ">Figure 16
<p>Distribution of viscous diffusion term on different span planes.</p> Full article ">
16 pages, 3257 KiB  
Article
Integrated Design of Aerodynamic Performance and Structural Characteristics for Medium Thickness Wind Turbine Airfoil
by Quan Wang, Pan Huang, Di Gan and Jun Wang
Appl. Sci. 2019, 9(23), 5243; https://doi.org/10.3390/app9235243 - 2 Dec 2019
Cited by 6 | Viewed by 3241
Abstract
The currently geometric and aerodynamic characteristics for wind turbine airfoils with the medium thickness are studied to pursue maximum aerodynamic performance, while the interaction between blade stiffness and aerodynamic performance is neglected. Combining the airfoil functional integration theory and the mathematical model of [...] Read more.
The currently geometric and aerodynamic characteristics for wind turbine airfoils with the medium thickness are studied to pursue maximum aerodynamic performance, while the interaction between blade stiffness and aerodynamic performance is neglected. Combining the airfoil functional integration theory and the mathematical model of the blade cross-section stiffness matrix, an integrated design method of aerodynamic performance and structural stiffness characteristics for the medium thickness airfoils is presented. The aerodynamic and structural comparison of the optimized WQ-A300 airfoil, WQ-B300 airfoil, and the classic DU97-W-300 airfoil were analyzed. The results show that the aerodynamic performance of the WQ-A300 and WQ-B300 airfoils are better than that of the DU97-W-300 airfoil. Though the aerodynamic performance of the WQ-B300 airfoil is slightly reduced compared to the WQ-A300 airfoil, its blade cross-sectional stiffness properties are improved as the flapwise and edgewise stiffness are increased by 6.2% and 8.4%, respectively. This study verifies the feasibility for the novel design method. Moreover, it also provides a good design idea for the wind turbine airfoils and blade structural properties with medium or large thickness. Full article
(This article belongs to the Special Issue Wind Power Technologies)
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<p>Conformal transformation.</p> Full article ">Figure 2
<p>Schematic diagrams of the blade cross-sectional parameters.</p> Full article ">Figure 3
<p>Flow chart of the mathematical model.</p> Full article ">Figure 4
<p>Equivalent representation of each segment.</p> Full article ">Figure 5
<p>Flow chart of the optimal design method for the airfoil and its structure.</p> Full article ">Figure 6
<p>Profiles of the new airfoils and the DU97-W-300 airfoil.</p> Full article ">Figure 7
<p>(<b>a</b>) Lift coefficients of the new airfoils and the DU97-W-300 airfoil (smooth condition); (<b>b</b>) Lift coefficients of the new airfoils and the DU97-W-300 airfoil (rough condition).</p> Full article ">Figure 8
<p>(<b>a</b>) Lift-drag ratio of the new airfoils and the DU97-W-300 airfoil (smooth condition); (<b>b</b>) Lift-drag ratio of the new airfoils and the DU97-W-300 airfoil (rough condition).</p> Full article ">Figure 9
<p>Profiles of the airfoil in literature [<a href="#B32-applsci-09-05243" class="html-bibr">32</a>] and the new airfoil.</p> Full article ">Figure 10
<p>Lift coefficients of the airfoil in literature [<a href="#B32-applsci-09-05243" class="html-bibr">32</a>] and the WQ-B300 airfoil.</p> Full article ">Figure 11
<p>Lift-drag ratio of the airfoil in literature [<a href="#B32-applsci-09-05243" class="html-bibr">32</a>] and the WQ-B300 airfoil.</p> Full article ">Figure 12
<p>Comparisons of layer parameters for the WQ-A300 and WQ-B300 blade sections.</p> Full article ">Figure 13
<p>Variation of the main beam position for the WQ-B300 blade cross-section.</p> Full article ">
16 pages, 6759 KiB  
Article
Forecasting Landslides via Three-Dimensional Discrete Element Modeling: Helong Landslide Case Study
by Wei Peng, Shengyuan Song, Chongjia Yu, Yiding Bao, Jiaxuan Sui and Ying Hu
Appl. Sci. 2019, 9(23), 5242; https://doi.org/10.3390/app9235242 - 2 Dec 2019
Cited by 7 | Viewed by 3399
Abstract
Forecasting the occurrence potential of landslides is important but challenging. We aimed to forecast the failure potential of the Helong landslide, which is temporarily stable but has clearly deformed in recent years. To achieve the goal, we used reconnaissance, remote sensing, drilling, laboratory [...] Read more.
Forecasting the occurrence potential of landslides is important but challenging. We aimed to forecast the failure potential of the Helong landslide, which is temporarily stable but has clearly deformed in recent years. To achieve the goal, we used reconnaissance, remote sensing, drilling, laboratory tests, topographical analysis, and electrical resistivity tomography (ERT). The factor of safety (FOS) of the slope was first calculated using a limit equilibrium method. The results show the FOS of the slope was 1.856 under natural conditions, 1.506 under the earthquake conditions, 1.318 under light rainfall, 0.986 under heavy rainfall, 1.075 under light rainfall and earthquake, and 0.832 under simultaneous heavy rainfall and earthquake. When the FOS is less than 1.35, the slope is considered metastable according to the Technical Code for Building Slope Engineering (GB50330-2013) published by the Chinese Ministry of Housing and Urban-Rural Development. Based on the drilling data and digital elevation data, a three-dimensional discrete element method (DEM) model was used to simulate potential landslides. The simulation was used to examine catastrophic slope failure under heavy rainfall conditions within a range of friction coefficients and the corresponding affected areas were determined. Then, we analyzed a typical run-out process. The dynamic information of the run-out behavior, including velocity, run-out distance, and depth, were obtained, which is useful for decision support and future landslide hazard assessment. Full article
(This article belongs to the Section Earth Sciences)
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<p>The study area: (<b>a</b>) location, (<b>b</b>) topographic, and (<b>c</b>) geological maps.</p> Full article ">Figure 2
<p>Visual interpretation of historical deformation of the rockslide from Google Earth images (the date is shown using the YYYY.MM.DD format). (<b>a</b>) 2008.12.26, (b) 2011.09.02, (c) 2011.09.25, (d) 2013.09.22, (e) 2015.10.16, (f) 2018.05.31.</p> Full article ">Figure 3
<p>Overview of Helong landslide: (<b>a</b>) three-dimensional (3D) scene model and (<b>b</b>) AA’ profile of Helong landslide in <a href="#applsci-09-05242-f003" class="html-fig">Figure 3</a>a (ERT in the <a href="#applsci-09-05242-f003" class="html-fig">Figure 3</a>a denotes electrical resistivity tomography).</p> Full article ">Figure 4
<p>Photographs of the Helong landslide in April 2018: (<b>a</b>) collapsed area of the landslide, (<b>b</b>) composition of the sources, (<b>c</b>) consolidation pressure test of the material, (<b>d</b>) terrain bulged phenomenon at the front part of potential failure mass, (<b>e</b>) cracks and trop head at the trilling edge, and (<b>f</b>) infiltration at the bottom of the source area.</p> Full article ">Figure 5
<p>ERT inverse models for the investigated (<b>a</b>) longitudinal and (<b>b</b>) transverse profiles. The positioning of ERT profiles is shown in <a href="#applsci-09-05242-f003" class="html-fig">Figure 3</a>a.</p> Full article ">Figure 6
<p>Slice discretization and slice force in a sliding mass.</p> Full article ">Figure 7
<p>Principle of a digital elevation model (DEM): (<b>a</b>) schematic of the force–displacement model between two particles and a (<b>b</b>) calculation flow chart.</p> Full article ">Figure 8
<p>Factor of safety (FOS) results of stability analysis.</p> Full article ">Figure 9
<p>Parameter calibration of the DEM: (<b>a</b>) flow chart, (<b>b</b>) numerical direct shear test, and (<b>c</b>) comparison of the shear test between the numerical model and the laboratory experiment.</p> Full article ">Figure 10
<p>Three-dimensional DEM.</p> Full article ">Figure 11
<p>Simulation results with friction coefficients of (<b>a</b>) 0.35, (<b>b</b>) 0.3, (<b>c</b>) 0.25, and (<b>d</b>) 0.2 to illustrate the final deposition areas.</p> Full article ">Figure 12
<p>Dynamic process of the Helong landslide (friction coefficient = 0.25) with snapshots at different times: (<b>a</b>) T = 2 s, (<b>b</b>) T = 10 s, (<b>c</b>) T = 18 s, and (<b>d</b>) T = 25 s.</p> Full article ">Figure 13
<p>Run-out behavior in different parts of the sliding mass: (<b>a</b>) position of the monitoring balls and corresponding traces, and (<b>b</b>) velocity of the monitoring balls in the whole sliding process.</p> Full article ">
15 pages, 2347 KiB  
Article
Mixed Convective Flow of Micropolar Nanofluid across a Horizontal Cylinder in Saturated Porous Medium
by Ahmed M. Rashad, Waqar A. Khan, Saber M. M. EL-Kabeir and Amal M. A. EL-Hakiem
Appl. Sci. 2019, 9(23), 5241; https://doi.org/10.3390/app9235241 - 2 Dec 2019
Cited by 39 | Viewed by 2781
Abstract
The micropolar nanofluids are the potential liquids that enhance the thermophysical features and ability of heat transportation instead of base liquids. Alumina and Titania nanoparticles are mixed in a micropolar fluid. The impact of convective boundary condition is also examined with assisting and [...] Read more.
The micropolar nanofluids are the potential liquids that enhance the thermophysical features and ability of heat transportation instead of base liquids. Alumina and Titania nanoparticles are mixed in a micropolar fluid. The impact of convective boundary condition is also examined with assisting and opposing flows of both nanofluids. The main objective of this study is to investigate mixed convective flow and heat transfer of micropolar nanofluids across a cylinder in a saturated porous medium. Non-similar variables are used to make the governing equations dimensionless. The local similar and non-similar solutions are obtained by using the Runge-Kutta-Fehlberg method of seventh order. The impacts of various embedded variables on the flow and heat transfer of micropolar nanofluids are investigated and interpreted graphically. It is demonstrated that the skin friction and heat transfer rates depend on solid volume fraction of nanoparticles, Biot number, mixed convection, and material parameters. Full article
(This article belongs to the Section Mechanical Engineering)
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<p>Geometry of the flow process.</p> Full article ">Figure 2
<p>Variation of dimensionless velocity with <span class="html-italic">∆</span> and <span class="html-italic">λ</span> for assisting flow of micropolar fluid with (<b>a</b>) Al<sub>2</sub>O<sub>3</sub> and (<b>b</b>) TiO<sub>2</sub> nanoparticles.</p> Full article ">Figure 3
<p>Variation of dimensionless velocity with <span class="html-italic">∆</span> and <span class="html-italic">λ</span> for opposing flow of micropolar fluid with (<b>a</b>) Al<sub>2</sub>O<sub>3</sub> and (<b>b</b>) TiO<sub>2</sub> nanoparticles.</p> Full article ">Figure 4
<p>Variation of dimensionless rotational velocity with <span class="html-italic">∆</span> and <span class="html-italic">λ</span> for assisting flow of micropolar fluid with (<b>a</b>) Al<sub>2</sub>O<sub>3</sub> and (<b>b</b>) TiO<sub>2</sub> nanoparticles.</p> Full article ">Figure 5
<p>Variation of dimensionless rotational velocity with <span class="html-italic">∆</span> and <span class="html-italic">λ</span> for opposing flow of micropolar fluid with (<b>a</b>) Al<sub>2</sub>O<sub>3</sub> and (<b>b</b>) TiO<sub>2</sub> nanoparticles.</p> Full article ">Figure 6
<p>Variation of dimensionless temperature with <span class="html-italic">∆</span> and <span class="html-italic">λ</span> for assisting flow of micropolar fluid with (<b>a</b>) Al<sub>2</sub>O<sub>3</sub> and (<b>b</b>) TiO<sub>2</sub> nanoparticles.</p> Full article ">Figure 7
<p>Variation of dimensionless temperature with <span class="html-italic">∆</span> and <span class="html-italic">λ</span> for opposing flow of micropolar fluid with (<b>a</b>) Al<sub>2</sub>O<sub>3</sub> and (<b>b</b>) TiO<sub>2</sub> nanoparticles.</p> Full article ">Figure 8
<p>Variation of skin friction along the surface with <span class="html-italic">∆</span> and <span class="html-italic">λ</span> for (<b>a</b>) assisting flow and (<b>b</b>) opposing flow of micropolar-Al<sub>2</sub>O<sub>3</sub> nanofluids.</p> Full article ">Figure 9
<p>Variation of skin friction along the surface with solid volume fraction of nanoparticles and Biot number for (<b>a</b>) assisting flow and (<b>b</b>) opposing flow of micropolar-TiO<sub>2</sub> nanofluids.</p> Full article ">Figure 10
<p>Variation of skin friction along the surface with solid volume fraction of nanoparticles and Biot number for (<b>a</b>) assisting flow and (<b>b</b>) opposing flow of micropolar-TiO<sub>2</sub> nanofluids.</p> Full article ">Figure 11
<p>Variation of local Nusselt number along the surface with <span class="html-italic">∆</span> and <span class="html-italic">λ</span> for (<b>a</b>) assisting flow and (<b>b</b>) opposing flow of micropolar-Al<sub>2</sub>O<sub>3</sub> nanofluids.</p> Full article ">Figure 12
<p>Variation of local Nusselt number along the surface with solid volume fraction of nanoparticles and Biot number for (<b>a</b>) assisting flow and (<b>b</b>) opposing flow of micropolar-TiO<sub>2</sub> nanofluids.</p> Full article ">
22 pages, 8738 KiB  
Article
Availability and Fade Margin Calculations for 5G Microwave and Millimeter-Wave Anyhaul Links
by Attila Hilt
Appl. Sci. 2019, 9(23), 5240; https://doi.org/10.3390/app9235240 - 2 Dec 2019
Cited by 33 | Viewed by 16389
Abstract
The deployment of new radio access technologies always provides a good opportunity and timing to optimize the existing mobile front- and backhaul (commonly called “anyhaul”). The legacy systems (Long-Term Evolution (LTE), High-Speed Packet Access (HSPA), third-generation mobile (3G), second-generation mobile (2G)) already extensively [...] Read more.
The deployment of new radio access technologies always provides a good opportunity and timing to optimize the existing mobile front- and backhaul (commonly called “anyhaul”). The legacy systems (Long-Term Evolution (LTE), High-Speed Packet Access (HSPA), third-generation mobile (3G), second-generation mobile (2G)) already extensively utilize the transmission and transport capacities of the mobile anyhaul. With the current launch of 5G (fifth-generation mobile) and recent LTE-A (Advanced Long-Term Evolution), additional new transmission capacities are required again. Depending on the traffic and network topology, additional cell sites are built, and even more locations are connected with fiber optics. The existing microwave and millimeter-wave links are rotated toward those aggregation points that already have optical-fiber access. Due to the increased cell-site density, the average distance of the radio access links can be reduced by network and topology optimization. The reduced hop lengths combined with adaptive modulation and automatic power control bring an opportunity for capacity increase in shortened radio links. Links newly deployed for 5G find a wide spectrum in the millimetric V, E, W, and D frequency bands. This paper discusses the availability and hop-length targets of the anyhaul links that should be carefully kept by proper planning and monitoring. Full article
(This article belongs to the Special Issue Selected Papers from the 2019 42nd International Conference on Telecommunications and Signal Processing (TSP))
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<p>Fifth-generation mobile (5G): enabler for diverse use cases and services.</p> Full article ">Figure 2
<p>Different 5G interfaces: (<b>a</b>) in early 5G phase; (<b>b</b>) in mature 5G phase.</p> Full article ">Figure 3
<p>Example of topology re-planning for new and co-located sites.</p> Full article ">Figure 4
<p>Evolving core and radio access network (RAN) toward cloudification, 5G slicing, and edge sites.</p> Full article ">Figure 5
<p>Block diagram of the microwave and millimeter-wave (µ/mmW) transceiver (without feeder lines), according to European Telecommunication Standards Institute, ETSI EN 302 217. The reference points follow Reference [<a href="#B24-applsci-09-05240" class="html-bibr">24</a>].</p> Full article ">Figure 6
<p>System gain definitions—with and without antennas [<a href="#B1-applsci-09-05240" class="html-bibr">1</a>].</p> Full article ">Figure 7
<p>(<b>a</b>) Integrated antenna assembled as part of the outdoor unit (ODU). (<b>b</b>) Slip-mount antenna fitted without feeder lines to the ODU. (<b>c</b>) Example of combining polarization; photo reproduced with permission from RACOM [<a href="#B34-applsci-09-05240" class="html-bibr">34</a>]. (<b>d</b>) Separated antenna with two ODUs and two feeder waveguides.</p> Full article ">Figure 8
<p>Link budget and fading margin calculation.</p> Full article ">Figure 9
<p>Adaptive link modulation when ensuring guaranteed bit rate during intensive rain.</p> Full article ">Figure 10
<p>Specific attenuation due to oxygen (blue line), water vapor (orange line), and total attenuation (red line) according to International Telecommunication Union, ITU-R P.676-12. Reproduced with permission from ITU [<a href="#B39-applsci-09-05240" class="html-bibr">39</a>].</p> Full article ">Figure 11
<p>Atmospheric attenuation at 50–70 GHz (in dB/km, red line: sea level), according to ITU-R P.676-12. Reproduced with permission from ITU [<a href="#B39-applsci-09-05240" class="html-bibr">39</a>].</p> Full article ">Figure 12
<p>Combined atmospheric and rain attenuation in dB/km as a function of frequency [<a href="#B12-applsci-09-05240" class="html-bibr">12</a>]. The figure is re-printed with the permission of ETSI.</p> Full article ">Figure 13
<p>(<b>a</b>) Ice and snow on the radome of a parabolic dish; the photo is re-printed with permission from RACOM [<a href="#B34-applsci-09-05240" class="html-bibr">34</a>]. (<b>b</b>) Extra attenuation due to a tree in the near field. (<b>c</b>) ODU installed behind a church window (polycarbonate lamels). (<b>d</b>) Metal cables inside the first Fresnel zone of the µW link.</p> Full article ">Figure 14
<p>Recommended hop lengths as a function of rainfall intensity. (<b>a</b>) Hops with vertical polarization, 34 Mbit/s, 14 MHz, and ø 60 cm dishes. For the 58 GHz link, ø 30 cm dishes are used in the calculations. (<b>b</b>) Hops with horizontal polarization, 34 Mbit/s, 14 MHz, and ø 60 cm dishes.</p> Full article ">Figure 15
<p>Recommended hop lengths as a function of rainfall intensity. (<b>a</b>) Hops with vertical polarization, 34 Mbit/s, 14 MHz, and ø 30 cm dishes. In the 58 GHz band, <b><span class="html-italic">□</span></b> 20 cm rectangular antennas are used. (<b>b</b>) Hops with horizontal polarization, 34 Mbit/s, 14 MHz, and ø 30 cm dishes.</p> Full article ">Figure 16
<p>Recommended hop lengths as a function of rainfall intensity. (<b>a</b>) Hops with vertical polarization, 1 GHz channel and ø 12 cm dishes. (<b>b</b>) Hops with vertical polarization, 1 GHz channel and ø 39 cm dishes. (<b>c</b>) Hops with vertical polarization, 1 GHz channel and ø 69 cm dishes. (<b>d</b>) Comparison of vertical and horizontal links at the different modulation modes. (<b>e</b>) Comparison of hops with different dish sizes. Modulations are quadrature phase-shift keying (QPSK) and 128-QAM. (<b>f</b>) Example of monitoring the local and remote received signal level (RSL) and modulation modes.</p> Full article ">Figure 17
<p>Global map of rain-rate zones, reproduced with permission from RACOM [<a href="#B51-applsci-09-05240" class="html-bibr">51</a>].</p> Full article ">Figure 18
<p><span class="html-italic">R</span><sub>0.01%</sub> in mm/h, the rainfall intensities exceeded 0.01% of the time. (<b>a</b>) Rain-rate contour lines in Switzerland. (<b>b</b>) Rain-rate regions in Hungary as calculated in Reference [<a href="#B53-applsci-09-05240" class="html-bibr">53</a>]. The figure is reproduced with permission from László Csurgai-Horváth.</p> Full article ">Figure 19
<p>Rainfall maps of Norway measured over a long period. (<b>a</b>) Rainfall rates in mm/h, exceeded 0.001% of the time. (<b>b</b>) Rainfall rates in mm/h, exceeded 0.01% of the time. (<b>c</b>) Rainfall rates in mm/h, exceeded 0.1% of the time. Reproduced with permission from the Norwegian Meteorological Institute [<a href="#B54-applsci-09-05240" class="html-bibr">54</a>].</p> Full article ">
14 pages, 7666 KiB  
Article
Uncertainty Analysis of Two Methods in Hydrocarbon Prediction under Different Water Saturation and Noise Conditions
by Changcheng Liu, Deva Ghosh and Ahmed Mohamed Ahmed Salim
Appl. Sci. 2019, 9(23), 5239; https://doi.org/10.3390/app9235239 - 2 Dec 2019
Viewed by 2169
Abstract
The uncertainty of two recently proposed methods, “new fluid factor” and “delta K”, is analyzed under different water saturation and noise conditions through Monte Carlo modelling. The new fluid factor performs reliably (all metric parameters are above 0.9) when the water saturation is [...] Read more.
The uncertainty of two recently proposed methods, “new fluid factor” and “delta K”, is analyzed under different water saturation and noise conditions through Monte Carlo modelling. The new fluid factor performs reliably (all metric parameters are above 0.9) when the water saturation is up to 95%. The delta K has better performance (all metric parameters are close to 1) such that it is able to distinguish hydrocarbon from brine without the interference of high water saturation. The results prove the performances of the two methods are stable in a high water-saturation scenario. The analysis of noise indicates the methods are sensitive to noise in the input data in that the performance is excellent when the noise is relatively low (−20 dB) and decreases with increasing noise energy. The new fluid factor, which is in the interface domain, is more sensitive than delta K in the impedance domain. The metric parameters of the new fluid factor and delta K are in the range of 0.5 to 0.8 when the noise is high (−7 dB). High-quality input data and integration with other geophysical methods can effectively reduce these risks. In addition, two widely used traditional methods (fluid factor and Lambda-Rho) are analyzed as comparisons. It turns out the new fluid factor and delta K have better performance than traditional methods in both high water saturation and noise conditions. Full article
(This article belongs to the Section Earth Sciences)
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<p>(<b>a</b>) Receiver operating characteristic (ROC) of the new fluid factor (<math display="inline"><semantics> <mrow> <msub> <mrow> <mi>FF</mi> </mrow> <mrow> <mi>new</mi> </mrow> </msub> </mrow> </semantics></math>). (<b>b</b>) Evaluation metrics of the <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>FF</mi> </mrow> <mrow> <mi>new</mi> </mrow> </msub> </mrow> </semantics></math> vary with water saturation.</p> Full article ">Figure 2
<p>The area under the curve (AUC) of the <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>FF</mi> </mrow> <mrow> <mi>new</mi> </mrow> </msub> </mrow> </semantics></math> vary with water saturation.</p> Full article ">Figure 3
<p>(<b>a</b>) ROC of the <math display="inline"><semantics> <mrow> <mo>Δ</mo> <mi>K</mi> </mrow> </semantics></math>. (<b>b</b>) Evaluation metrics of the <math display="inline"><semantics> <mrow> <mo>Δ</mo> <mi>K</mi> </mrow> </semantics></math> vary with water saturation.</p> Full article ">Figure 4
<p>The AUC of the <math display="inline"><semantics> <mrow> <mo>Δ</mo> <mi>K</mi> </mrow> </semantics></math> varies with water saturation.</p> Full article ">Figure 5
<p>The performances of <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>FF</mi> </mrow> <mrow> <mi>Smith</mi> </mrow> </msub> </mrow> </semantics></math> in different water saturation scenarios: (<b>a</b>) ROC curves, (<b>b</b>) evaluation metrics.</p> Full article ">Figure 6
<p>AUC curve of traditional fluid factor (<math display="inline"><semantics> <mrow> <msub> <mrow> <mi>FF</mi> </mrow> <mrow> <mi>Smith</mi> </mrow> </msub> </mrow> </semantics></math>).</p> Full article ">Figure 7
<p>The performances of <math display="inline"><semantics> <mrow> <mi>λ</mi> <mi>ρ</mi> </mrow> </semantics></math> in different water saturation scenarios: (<b>a</b>) ROC curves. (<b>b</b>) metric parameters.</p> Full article ">Figure 8
<p>AUC curve of <math display="inline"><semantics> <mrow> <mi>λ</mi> <mi>ρ</mi> </mrow> </semantics></math>.</p> Full article ">Figure 9
<p>The ROCs of the <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>FF</mi> </mrow> <mrow> <mi>new</mi> </mrow> </msub> </mrow> </semantics></math> in the different noise scenarios: (<b>a</b>) −20 dB, (<b>b</b>) −10 dB, (<b>c</b>) −7 dB. The metrics of the <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>FF</mi> </mrow> <mrow> <mi>new</mi> </mrow> </msub> </mrow> </semantics></math> in the different noise scenarios: (<b>d</b>) −20 dB, (<b>e</b>) −10 dB, (<b>f</b>) −7 dB.</p> Full article ">Figure 10
<p>The AUC curves of the <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>FF</mi> </mrow> <mrow> <mi>new</mi> </mrow> </msub> </mrow> </semantics></math> in the different noise scenarios: −20 dB, −10 dB and −7 dB, respectively.</p> Full article ">Figure 11
<p>The ROCs of the <math display="inline"><semantics> <mrow> <mo>Δ</mo> <mi>K</mi> </mrow> </semantics></math> in the different noise scenarios: (<b>a</b>) −20 dB, (<b>b</b>) −10 dB, (<b>c</b>) −7 dB. The metrics of the <math display="inline"><semantics> <mrow> <mo>Δ</mo> <mi>K</mi> </mrow> </semantics></math> in the different noise scenarios: (<b>d</b>) −20 dB, (<b>e</b>) −10 dB, (<b>f</b>) −7 dB.</p> Full article ">Figure 12
<p>The AUC curves of the <math display="inline"><semantics> <mrow> <mo>Δ</mo> <mi>K</mi> </mrow> </semantics></math> in the different noise scenarios: −20 dB, −10 dB and −7 dB.</p> Full article ">Figure 13
<p>The ROCs of the <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>FF</mi> </mrow> <mrow> <mi>Smith</mi> </mrow> </msub> </mrow> </semantics></math> in the different noise scenarios: (<b>a</b>) −20 dB, (<b>b</b>) −10 dB, (<b>c</b>) −7 dB. The metrics of the <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>FF</mi> </mrow> <mrow> <mi>Smith</mi> </mrow> </msub> </mrow> </semantics></math> in the different noise scenarios: (<b>d</b>) −20 dB, (<b>e</b>) −10 dB, (<b>f</b>) −7 dB.</p> Full article ">Figure 14
<p>The AUC curves of the <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>FF</mi> </mrow> <mrow> <mi>Smith</mi> </mrow> </msub> </mrow> </semantics></math> in the different noise scenarios: −20dB, −10 dB and −7 dB.</p> Full article ">Figure 15
<p>The ROCs of the <math display="inline"><semantics> <mrow> <mrow> <mi mathvariant="sans-serif">λ</mi> <mi mathvariant="sans-serif">ρ</mi> </mrow> </mrow> </semantics></math> in the different noise scenarios: (<b>a</b>) −20 dB, (<b>b</b>) −10 dB, (<b>c</b>) −7 dB. The metrics of the <math display="inline"><semantics> <mrow> <mrow> <mi mathvariant="sans-serif">λ</mi> <mi mathvariant="sans-serif">ρ</mi> </mrow> </mrow> </semantics></math> in the different noise scenarios: (<b>d</b>) −20 dB, (<b>e</b>) −10 dB, (<b>f</b>) −7 dB.</p> Full article ">Figure 16
<p>The AUC curves of the <math display="inline"><semantics> <mrow> <mrow> <mi mathvariant="sans-serif">λ</mi> <mi mathvariant="sans-serif">ρ</mi> </mrow> </mrow> </semantics></math> in the different noise scenarios: −20dB, −10 dB and −7 dB.</p> Full article ">
20 pages, 5446 KiB  
Article
A Comparative Evaluation of Cement and By-Product Petrit T in Soil Stabilization
by Wathiq Al-Jabban, Jan Laue, Sven Knutsson and Nadhir Al-Ansari
Appl. Sci. 2019, 9(23), 5238; https://doi.org/10.3390/app9235238 - 2 Dec 2019
Cited by 13 | Viewed by 3769
Abstract
This study presents a comparison between the effectiveness of adding low binder amounts of industrial by-product Petrit T as well as cement to modify and improve fine-grained soil. Binder amount was added by soil dry weight; cement at 1%, 2%, 4% and 7% [...] Read more.
This study presents a comparison between the effectiveness of adding low binder amounts of industrial by-product Petrit T as well as cement to modify and improve fine-grained soil. Binder amount was added by soil dry weight; cement at 1%, 2%, 4% and 7% and Petrit T at 2%, 4% and 7%. The unconfined compressive strength (UCS) was used as an indicator of soil strength. In addition, the consistency limits, laser particle size analysis, and pH tests were also conducted on the treated soil. The samples were cured at 20 °C for different periods from 7 to 90 days before testing. Results indicate that cement is more effective at improving the physical and engineering properties of the treated soil. Soil plasticity index decreases after treatment and with time. Liquidity index and the water content to plastic limit ratio are introduced as new indices to define the improvement in the workability of treated soil. Soil particle size distribution is changed by reducing the clay size fraction and increasing the silt size fraction after treatment. The findings confirm that adding small binder contents improve soil properties, which subsequently reduce the environmental threats and costs that are associated with using a high amount of binder. Full article
(This article belongs to the Section Civil Engineering)
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<p>Consistency limits versus binder content of soil after one hour of treatment.</p> Full article ">Figure 2
<p>Plasticity index versus curing time.</p> Full article ">Figure 3
<p>Water content of soil versus binder amount after one hour of treatment.</p> Full article ">Figure 4
<p>Soil water content versus curing time and binder type and content.</p> Full article ">Figure 5
<p>Binder content versus liquidity index of soil after one hour of treatment.</p> Full article ">Figure 6
<p>Liquidity index versus soil water content for all curing times.</p> Full article ">Figure 7
<p>Specimen density versus binder content.</p> Full article ">Figure 8
<p>The pH value of soil after one hour of treatment versus binder content.</p> Full article ">Figure 9
<p>The pH value of treated soil versus curing time and binder amount.</p> Full article ">Figure 10
<p>Unconfined compressive strength (UCS) versus curing time for (<b>a</b>) Untreated soil; (<b>b</b>) Treated soil with 1 and 2% cement and 2% Petrit T; (<b>c</b>) Treated soil with 4% of cement and Petrit T; and (<b>d</b>) Treated soil with 7% of cement and Petrit T.</p> Full article ">Figure 11
<p>UCS versus liquidity index for all tests.</p> Full article ">Figure 12
<p>UCS versus water/plastic limit ratio for all tests.</p> Full article ">Figure 13
<p>Stress–strain curves for the untreated and treated soil with different binder content after (<b>a</b>) 14 days curing time; (<b>b</b>) 28 days curing time; (<b>c</b>) 60 days curing time; and (<b>d</b>) 90 days curing time.</p> Full article ">Figure 14
<p>Strain at failure versus curing time for (<b>a</b>) untreated soil; (<b>b</b>) treated soil with 1 and 2% cement and 2% Petrit T; (<b>c</b>) treated soil with 4% of cement and Petrit T and (<b>d</b>) treated soil with 7% of cement and Petrit T.</p> Full article ">Figure 15
<p>Axail failure strain versus UCS strength for all tests.</p> Full article ">Figure 16
<p>Modulus of elasticity versus curing time and binder content for (<b>a</b>) untreated soil; (<b>b</b>) treated soil with 1 and 2% cement and 2% Petrit T; (<b>c</b>) treated soil with 4% of cement and Petrit T and (<b>d</b>) treated soil with 7% of cement and Petrit T.</p> Full article ">Figure 17
<p>Modulus of elasticity versus UCS strength (q<sub>u</sub>) and binder content for (<b>a</b>) treated soil with 1 and 2% cement and 2% Petrit T; (<b>b</b>) treated soil with 4% of cement and Petrit T and (<b>c</b>) treated soil with 7% of cement and Petrit T.</p> Full article ">
12 pages, 4337 KiB  
Article
Facile Fabrication of Micro/Nano Hierarchical SERS Sensor via Anisotropic Etching and Electrochemical Treatment for Malachite Green Detection
by Chu-Yu Huang and Chih-Hung Chien
Appl. Sci. 2019, 9(23), 5237; https://doi.org/10.3390/app9235237 - 2 Dec 2019
Cited by 10 | Viewed by 4291
Abstract
We propose a facile method to produce micro/nano hierarchical surface-enhanced Raman scattering (SERS) active substrates using simple steps and inexpensive costs. The proposed SERS substrate is a silicon pyramid array covered by a nanostructured gold film (AuNS @ SiPA). Through finite element method [...] Read more.
We propose a facile method to produce micro/nano hierarchical surface-enhanced Raman scattering (SERS) active substrates using simple steps and inexpensive costs. The proposed SERS substrate is a silicon pyramid array covered by a nanostructured gold film (AuNS @ SiPA). Through finite element method (FEM) simulation, we showed that many strong local electric field enhancements (hot spots) were formed between the nano-gap of gold nanostructures. In addition, the micron-scale pyramid structure not only increases the sensing surface area of the sensor, but also helps trap light. By combining these micro and nano structures, the proposed micro/nano hierarchical SERS sensor exhibited high sensitivity. Experimental results confirmed that the AuNS @ SiPA substrate has high sensitivity. The SERS signal enhancement factor obtained from the Rhodamine 6G (R6G) probe molecules was as high as 1 × 107 and the SERS substrates were found to be able to detect a very low concentration of 0.01 nM malachite green (MG) solution. Therefore, this study provides a novel and practical method for fabricating SERS substrates that can facilitate the use of SERS in medicine, food safety, and biotechnology. Full article
(This article belongs to the Special Issue Bottom-up Approach and Self-Assembled Nano-Structures for Plasmonics and Nano-Optics Applications)
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<p>The fabrication process of the described micro/nano hierarchical structure. (<b>a</b>) The silicon wafer was wet etched in a mixed solution of NaOH, water, and isopropyl alcohol. (<b>b</b>) Depositing a gold thin film on the micro-pyramid array using a sputtering system. (<b>c</b>) Attach the chip to a slide before electrochemical treatment. (<b>d</b>) The sample was treated with electrochemical oxidation and reduction cycles to create nanostructures on the surface of the gold thin film.</p> Full article ">Figure 2
<p>(<b>a</b>) The SEM image of pyramid microstructure formed by anisotropic wet etching. (<b>b</b>) The pyramid size measured by an atomic force microscope (AFM), the overall pyramid average height is 2 μm, and the average spacing is 2.8 μm.</p> Full article ">Figure 3
<p>(<b>a</b>) The gold film morphology on the surface of the micro-pyramid structure before electrochemical treatment, the surface is relatively smooth (compared with the electrochemically treated surface). (<b>b</b>) The gold film morphology after 5 redox cycles. (<b>c</b>) The gold film morphology after 10 redox cycles. (<b>d</b>) The gold film morphology after 15 redox cycles.</p> Full article ">Figure 4
<p>The gold film on the surface of the pyramid is oxidized and corroded. After too many oxidization-reduction cycles, the gold film became too thin and exposed the pyramid.</p> Full article ">Figure 5
<p>The cyclic voltammetry curves from the 1st scan to the 15th scan cycle at a sweeping rate of 50 mV s<sup>−1</sup> in the 0.2 M KCl solution. Each cycle curve was plotted in a different line style for clarity. The position of the blue arrow in the figure shows the position where the oxidation peak occurs, which is about 530 mV. We can see from the figure that the oxidation peak current increases with the number of scanning cycles. However, the increment gradually reduces, and its increment was quite limited after the number of scanning cycles exceeded 10.</p> Full article ">Figure 6
<p>The oxidation peak currents at 530 mV were plotted against the scanning cycles. It can be seen that the oxidation peak current increases with the number of scanning cycles. The increment gradually reduces, and when the voltammetry redox scan reaches a certain amount of cycles (in this case around 10 cycles), the oxidation peaks reach a plateau state.</p> Full article ">Figure 7
<p>It shows the surface-enhanced Raman scattering (SERS) experiments results of 1 μM Rhodamine 6 (R6G) solution measured by SERS chips with different oxidation-reduction cycles (0, 2, 4, 6, 8, 10, 12, and 14, respectively). It can be seen that in the first few cycles, the intensity of the SERS characteristic peak of R6G at 1510 cm<sup>−1</sup> increased rapidly and reached a plateau after 10 cycles.</p> Full article ">Figure 8
<p>A cross-sectional view of the electric field distribution between two micro-pyramids with an incident light wavelength of 633 nm. In this figure, the normalized electric field represents the ratio between the electric Field excited by the local surface plasmon resonance and the background electric field.</p> Full article ">Figure 9
<p>Shows the SERS spectra of R6G solutions with concentrations of 1 × 10<sup>−6</sup> M, 1 × 10<sup>−7</sup> M, 1 × 10<sup>−8</sup> M, and 1 × 10<sup>−9</sup> M, respectively, using our SERS substrate with 10 oxidation-reduction cycles.</p> Full article ">Figure 10
<p>The figure shows measured SERS spectra for malachite green concentrations ranging from 0.01 nM to 10 nM on SERS substrates.</p> Full article ">
16 pages, 5736 KiB  
Article
Directed Silica Co-Deposition by Highly Oxidized Silver: Enhanced Stability and Versatility of Silver Oxynitrate
by Carla J. Spina, Roohee Ladhani, Carlie Goodall, Michelle Hay and Rod Precht
Appl. Sci. 2019, 9(23), 5236; https://doi.org/10.3390/app9235236 - 2 Dec 2019
Cited by 5 | Viewed by 3429
Abstract
Novel silver compounds in higher oxidation states, Ag (II) and Ag (III), have emerged as desirable alternatives to existing forms of antimicrobial silver compounds. Offering enhanced efficacy without sacrificing biocompatibility. Unique physiochemical characteristics associated with higher oxidation state silver confer desirable therapeutic traits. [...] Read more.
Novel silver compounds in higher oxidation states, Ag (II) and Ag (III), have emerged as desirable alternatives to existing forms of antimicrobial silver compounds. Offering enhanced efficacy without sacrificing biocompatibility. Unique physiochemical characteristics associated with higher oxidation state silver confer desirable therapeutic traits. However, these same characteristics create challenges in terms of long-term stability and chemical compatibility with conventional biomedical materials. Core-shell methodologies, utilizing silica as a mesoporous or amorphous shell, have been adopted to enhance the stability of reactive active ingredients or cores. These methodologies commonly utilize controlled condensation of silicic acids in non-aqueous media by way of hydrolyzing alkyl silicates: the Stöber process or modified processes thereof. However, these strategies are not conducive to cores of higher oxidation state silver wherein hydroxyl organic precursors and by-products are incompatible with strong oxidizing agents. Addressing these challenges, we present a strategy herein for the preparation of a self-directed silver oxynitrate-silica, Ag7NO11:SiO2, framework. The method described utilizes pH gradients generated from the oxidation reaction of soluble silver, Ag (I), with a strong oxidizing agent/alkaline silicate media to facilitate spatial control over the protonation and subsequent condensation of silicic acid from aqueous solution. The resulting Ag7NO11:SiO2 framework confers enhanced long term and thermal stability to silver oxynitrate without impairing aqueous degradation profiles or subsequent antimicrobial and antibiofilm activities. Full article
(This article belongs to the Special Issue The Design, Synthesis, and Biological Evaluation of Compounds with Medicinal Value)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Powder X-ray diffraction of Ag<sub>7</sub>NO<sub>11</sub>:SiO<sub>2</sub> (0.0:1 to 0.5:1 molar equivalents SiO<sub>2</sub>:Ag). Solid-state silver compounds were identified as silver oxynitrate (Ag<sub>7</sub>NO<sub>11</sub>, inverted red triangles) and silver sulfate (Ag<sub>2</sub>SO<sub>4</sub>, green circles).</p> Full article ">Figure 2
<p>Scanning electron microscopy images of Ag<sub>7</sub>NO<sub>11</sub>:SiO<sub>2</sub> (0.0:1 to 0.5:1 molar equivalents SiO<sub>2</sub>:Ag). (<b>A</b>,<b>B</b>) Silver oxynitrate (Ag<sub>7</sub>NO<sub>11</sub>); (<b>C</b>,<b>D</b>) Ag<sub>7</sub>NO<sub>11</sub>:SiO<sub>2</sub> containing 0.10:1, SiO<sub>2</sub>:Ag; (<b>E</b>,<b>F</b>) Ag<sub>7</sub>NO<sub>11</sub>:SiO<sub>2</sub> containing 0.25:1, SiO<sub>2</sub>:Ag; (<b>G</b>,<b>H</b>) Ag<sub>7</sub>NO<sub>11</sub>:SiO<sub>2</sub>containing 0.50:1, SiO<sub>2</sub>:Ag.</p> Full article ">Figure 3
<p>Transmission electron microscopy images of Ag<sub>7</sub>NO<sub>11</sub>:SiO<sub>2</sub> (0.0:1 to 0.5:1 molar equivalents SiO<sub>2</sub>:Ag) prepared by the co-deposition synthetic process. (<b>A</b>–<b>C</b>) Ag<sub>7</sub>NO<sub>11</sub>:SiO<sub>2</sub> containing 0.10:1, SiO<sub>2</sub>:Ag; (<b>D</b>–<b>F</b>) Ag<sub>7</sub>NO<sub>11</sub>:SiO<sub>2</sub> containing 0.50:1, SiO<sub>2</sub>:Ag.</p> Full article ">Figure 4
<p>Powder X-ray diffraction patterns of (<b>A</b>) silver oxynitrate (Ag<sub>7</sub>NO<sub>11</sub>) and; (<b>B</b>) Ag<sub>7</sub>NO<sub>11</sub>:SiO<sub>2</sub> containing 0.10:1, SiO<sub>2</sub>:Ag, equivalents silica over a four month period under storage at ambient room temperature (RT) conditions. Solid-state silver compounds were identified as silver oxynitrate (Ag<sub>7</sub>NO<sub>11</sub>, inverted red triangles), silver sulfate (Ag<sub>2</sub>SO<sub>4</sub>, green circles), and argentic oxide (AgO, blue squares).</p> Full article ">Figure 5
<p>Powder X-ray diffraction patterns of (<b>A</b>) silver oxynitrate (Ag<sub>7</sub>NO<sub>11</sub>) and; (<b>B</b>) Ag<sub>7</sub>NO<sub>11</sub>:SiO<sub>2</sub> containing 0.10:1, SiO<sub>2</sub>:Ag, equivalents silica over a four month period under accelerated storage in an incubator at 40 °C. Solid-state silver compounds were identified as silver oxynitrate (Ag<sub>7</sub>NO<sub>11</sub>, inverted red triangles), silver sulfate (Ag<sub>2</sub>SO<sub>4</sub>, green circles), argentic oxide (AgO, blue squares), silver nitrate (AgNO3, orange diamonds), silver oxide (Ag<sub>2</sub>O, blue triangle), and metallic silver (Ag, grey arrows).</p> Full article ">Figure 6
<p>Powder X-ray diffraction patterns of (<b>A</b>) silver oxynitrate (Ag<sub>7</sub>NO<sub>11</sub>) and; (<b>B</b>) Ag<sub>7</sub>NO<sub>11</sub>:SiO<sub>2</sub> containing 0.10:1, SiO<sub>2</sub>:Ag, equivalents silica over a seven-day period in an aqueous solution at room temperature. Solid-state silver compounds were identified as silver oxynitrate (Ag<sub>7</sub>NO<sub>11</sub>, inverted red triangles), silver sulfate (Ag<sub>2</sub>SO<sub>4</sub>, green circles), and argentic oxide (AgO, blue squares).</p> Full article ">Figure 7
<p>Scanning electron microscopy images of silver oxynitrate and Ag<sub>7</sub>NO<sub>11</sub>:SiO<sub>2</sub> containing 0.1:1, SiO<sub>2</sub>:Ag, exposed to aqueous media for a period of seven days. Silver oxynitrate (Ag<sub>7</sub>NO<sub>11</sub>) (<b>A</b>) prior to aqueous exposure; (<b>B</b>) after 24 h of exposure to aqueous media; and (<b>C</b>) after 168 h of exposure to aqueous media. Ag<sub>7</sub>NO<sub>11</sub>:SiO<sub>2</sub> containing 0.1:1, SiO<sub>2</sub>:Ag (<b>D</b>) prior to aqueous exposure; (<b>E</b>) after 24 h of exposure to aqueous media; and (<b>F</b>) after 168 h of exposure to aqueous media.</p> Full article ">Figure 8
<p>Antimicrobial efficacy of silver oxynitrate (Ag<sub>7</sub>NO<sub>11</sub>) and Ag<sub>7</sub>NO<sub>11</sub>:SiO<sub>2</sub> containing 0.1:1, SiO<sub>2</sub>:Ag. (<b>A</b>) Single-time log reduction for 1-h treatment period against <span class="html-italic">P. aeruginosa</span> and 4-h treatment period against <span class="html-italic">S. aureus</span> challenged at 1 × 10<sup>6</sup> CFU/mL; (<b>B</b>) Biofilm log reduction values for 2-h treatment period against <span class="html-italic">P. aeruginosa</span> and 4-h treatment period against <span class="html-italic">S. aureus</span> established 3D biofilm. Results representing the average of triplicate data (<span class="html-italic">n</span> = 3), error bars indicated represent standard deviations of the triplicate measurements.</p> Full article ">
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