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Volume 12
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Appl. Sci., Volume 12, Issue 4 (February-2 2022) – 497 articles

Cover Story (view full-size image): Smart industrial workstations for the training and evaluation of workers are an innovative approach to face the problems of manufacturing quality assessment and fast training. In this study, four different vision-based methods based, respectively, on ArUco markers, OpenPose, Azure Kinect Body Tracking and the YOLO network have been proposed in order to estimate the position of a specific point of interest of the tool that has to be tracked in real-time during an assembly or maintenance procedure. The proposed approaches have been tested on a real scenario with four users handling a power drill simulating three different conditions during an assembly procedure. The performance of the methods has been evaluated and compared with the HTC Vive tracking system as a benchmark. Then, the advantages and drawbacks in terms of the accuracy and invasiveness of the method have been discussed. View this paper
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12 pages, 51164 KiB  
Article
Laboratory Test Campaign Aimed at the Analysis of an Uncommon Wear Phenomenon in a Marble Quarry
by Alfio Di Giovanni, Carmine Todaro, Marilena Cardu, Stefano Bianchini and Brunello Forfori
Appl. Sci. 2022, 12(4), 2264; https://doi.org/10.3390/app12042264 - 21 Feb 2022
Cited by 4 | Viewed by 2730
Abstract
The use of ornamental stones has a historical value that makes them strategically precious in Italy; marble can offer high performance in architectural applications, even though the variability of the rock mass requires detailed studies to optimize the exploitation techniques and reduce waste. [...] Read more.
The use of ornamental stones has a historical value that makes them strategically precious in Italy; marble can offer high performance in architectural applications, even though the variability of the rock mass requires detailed studies to optimize the exploitation techniques and reduce waste. Italy is world famous for its marble, which is extracted mainly through chainsaw cutting machines, which are currently used intensively due to their high-safety working conditions compared to alternative techniques and for their great versatility, especially in underground applications. Although this cutting technique is well-rooted, an uncommon problem of tool wear was found in the quarry under study, which strongly affected productivity. A series of laboratory test were carried out to estimate the wear potential of the rock and the suitability of the tools. The Cerchar abrasivity test highlighted a mean wear potential for the marble of 2.77, while microhardness outcomes pointed out the presence of quartz veins in the tested material (values over 10,000 MPa). Finally, additives typically used in the conditioning process of EPB machines in tunneling were tested with the purpose of reducing the extent of wear. A reduction of about 50% in the wear (in terms of weight lost) was obtained for a moisture content of 9%. Full article
(This article belongs to the Topic Sustainable Environmental Technologies)
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<p>The chain cutting machine adopted in the quarry. The machine is engaged in a series of horizontal cuts to widen the underground opening (link <a href="https://www.fantinispa.it/en/gu70rxc-tunnel-chain-saw-machine/" target="_blank">https://www.fantinispa.it/en/gu70rxc-tunnel-chain-saw-machine/</a>, accessed on 2 October 2021).</p> Full article ">Figure 2
<p>Detail of the tools and their tool holder: (<b>a</b>) front view of the arrangement of the tools in the execution of the cut with a thickness of 40.82 mm, (<b>b</b>) cutting chain front view.</p> Full article ">Figure 3
<p>Typical tool used in the chainsaw cutting machine. The front and side views are shown on the left and right of the image, respectively. A new tool is shown above: the color difference between polycrystalline diamond (shorter area) and tungsten carbide (longer area) is clearly recognizable from the top right image. Below is shown a tool after 0.24 h/m<sup>2</sup> of work: the almost complete absence of the polycrystalline diamond layer is evident.</p> Full article ">Figure 4
<p>Intensity vs. incidence angle chart (<b>a</b>) and mineralogical abundance (<b>b</b>).</p> Full article ">Figure 5
<p>Indentation scheme [<a href="#B23-applsci-12-02264" class="html-bibr">23</a>]. F is the applied force, while d is the diagonal of the left footprint.</p> Full article ">Figure 6
<p>Samples analyzed. The grey veins are marginally present in sample 3 (<b>c</b>), while in samples 1 and 2 (<b>a</b>,<b>b</b>), the presence of impurities is greater. Sample 4 (<b>d</b>) is almost entirely composed of grey material.</p> Full article ">Figure 7
<p>Cumulative frequency curves of microhardness (microhardness characteristic curves).</p> Full article ">Figure 8
<p>Sample before the test (<b>a</b>) and after the test (<b>b</b>).</p> Full article ">Figure 9
<p>Soil abrasion testing apparatus. Image modified from [<a href="#B45-applsci-12-02264" class="html-bibr">45</a>].</p> Full article ">Figure 10
<p>Particle size distribution of the crushed marble used in the wear test performed with the SATA.</p> Full article ">Figure 11
<p>Wear bells related to marble and quartzite.</p> Full article ">Figure 12
<p>Marble wear bell and wear conditioning tests (4% and 9% moisture content).</p> Full article ">
15 pages, 3459 KiB  
Article
Participatory Ergonomic Interventions for Improving Agricultural Work Environment: A Case Study in a Farming Organization of Korea
by Dohyung Kee
Appl. Sci. 2022, 12(4), 2263; https://doi.org/10.3390/app12042263 - 21 Feb 2022
Cited by 4 | Viewed by 2930
Abstract
Farmers are often exposed to risk factors for musculoskeletal disorders through lifting, carrying heavy loads, and sustained or repeated full-body bending. Several relevant studies on ergonomic interventions have been conducted for specific agricultural tasks, such as harvesting and pruning, by experts without involving [...] Read more.
Farmers are often exposed to risk factors for musculoskeletal disorders through lifting, carrying heavy loads, and sustained or repeated full-body bending. Several relevant studies on ergonomic interventions have been conducted for specific agricultural tasks, such as harvesting and pruning, by experts without involving farmers. This study introduces ergonomic interventions to mitigate risk factors in a farming organization that cultivates peaches as the main crop based on ergonomic analysis of the entire peach farming cycle; subjective and objective evaluations of the proposed interventions are also performed. The ergonomic analysis and interventions were established based on consultations provided by an ergonomist, the government, and the organization members. Engineering controls were introduced for powered carts, sorters, and stools to reduce load carrying and awkward postures; moreover, thermal or cooling vests, winter shoes and gloves, and farmer hats were provided to alleviate cold or heat stresses. Administrative controls such as education/training and adjusting work–rest cycles were also recommended after considering the characteristics of the risk factors identified. The scores of the questionnaire survey from the organization members were high (>4.1 out of 5 for five questions), and postural loads for unstable postures by RULA were significantly reduced so as to avoid fast or immediate changes for the postures or working methods assessed. The study results are expected to help promote farmers’ health and enhance farming efficiency. Full article
(This article belongs to the Special Issue Worker Safety in Agricultural Systems)
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<p>Two types of carts: (<b>a</b>) one-wheel manual cart; (<b>b</b>) powered cart with tracked wheels.</p> Full article ">Figure 2
<p>Work postures involved in pruning, flower and fruit thinning, and wrapping fruits in paper bags: (<b>a</b>) posture on traditional footrest; (<b>b</b>) posture on height-adjustable cargo box.</p> Full article ">Figure 3
<p>Sorting harvested peaches: (<b>a</b>) manual sorting; (<b>b</b>) automatic sorting.</p> Full article ">Figure 4
<p>Pesticide-related interventions: (<b>a</b>) old storage; (<b>b</b>) new storage; (<b>c</b>) protective clothing.</p> Full article ">Figure 5
<p>Interventions against cold and heat: (<b>a</b>) thermal vest; (<b>b</b>) agricultural shoes; (<b>c</b>) cooling vest; (<b>d</b>) farmer hat.</p> Full article ">Figure 6
<p>Different types of work gloves: (<b>a</b>) woven glove; (<b>b</b>) cut-resistant winter glove.</p> Full article ">Figure 7
<p>Height-adjustable agricultural stool.</p> Full article ">Figure 8
<p>Results of questionnaire survey.</p> Full article ">
14 pages, 2354 KiB  
Article
Data-Driven Robust Control Using Reinforcement Learning
by Phuong D. Ngo, Miguel Tejedor and Fred Godtliebsen
Appl. Sci. 2022, 12(4), 2262; https://doi.org/10.3390/app12042262 - 21 Feb 2022
Cited by 1 | Viewed by 2693
Abstract
This paper proposes a robust control design method using reinforcement learning for controlling partially-unknown dynamical systems under uncertain conditions. The method extends the optimal reinforcement learning algorithm with a new learning technique based on the robust control theory. By learning from the data, [...] Read more.
This paper proposes a robust control design method using reinforcement learning for controlling partially-unknown dynamical systems under uncertain conditions. The method extends the optimal reinforcement learning algorithm with a new learning technique based on the robust control theory. By learning from the data, the algorithm proposes actions that guarantee the stability of the closed-loop system within the uncertainties estimated also from the data. Control policies are calculated by solving a set of linear matrix inequalities. The controller was evaluated using simulations on a blood glucose model for patients with Type 1 diabetes. Simulation results show that the proposed methodology is capable of safely regulating the blood glucose within a healthy level under the influence of measurement and process noises. The controller has also significantly reduced the post-meal fluctuation of the blood glucose. A comparison between the proposed algorithm and the existing optimal reinforcement learning algorithm shows the improved robustness of the closed-loop system using our method. Full article
(This article belongs to the Special Issue Advances in Intelligent Control and Image Processing)
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<p>Data-driven robust reinforcement learning diagram.</p> Full article ">Figure 2
<p>Comparison of blood glucose responses in nominal case without meal intake.</p> Full article ">Figure 3
<p>Comparison of insulin concentration in nominal case without meal intake.</p> Full article ">Figure 4
<p>Comparison of blood glucose responses in uncertain cases without meal intake.</p> Full article ">Figure 5
<p>Insulin concentration in uncertain cases without meal intake.</p> Full article ">Figure 6
<p>Update of controller gains during the learning process (<math display="inline"><semantics> <mrow> <mi>K</mi> <mn>1</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>K</mi> <mn>2</mn> </mrow> </semantics></math> represent the first and second element of the controller gain vector <span class="html-italic">K</span>).</p> Full article ">Figure 7
<p>Carbohydrate intake per meal.</p> Full article ">Figure 8
<p>Blood glucose responses in simulation with meals.</p> Full article ">Figure 9
<p>Insulin concentration in simulation with meals.</p> Full article ">
10 pages, 2509 KiB  
Article
Competitive Detection of Volatile Compounds from Food Degradation by a Zinc Oxide Sensor
by Lucio Bonaccorsi, Andrea Donato, Antonio Fotia, Patrizia Frontera and Andrea Gnisci
Appl. Sci. 2022, 12(4), 2261; https://doi.org/10.3390/app12042261 - 21 Feb 2022
Cited by 5 | Viewed by 2201
Abstract
During the phenomenon of food degradation, several volatile organic compounds are generally released. In particular, due to lipid oxidation in stored and packed meat, hexanal is formed as a typical decomposition product. Therefore, its detection can provide an important indication of the quality [...] Read more.
During the phenomenon of food degradation, several volatile organic compounds are generally released. In particular, due to lipid oxidation in stored and packed meat, hexanal is formed as a typical decomposition product. Therefore, its detection can provide an important indication of the quality and conservation of meat. Unfortunately, the simultaneous release of other compounds, such as 1-pentanol and 1-octen-3-ol, during the first phase of the degradation process can have an undesirable effect on the detection of hexanal. In this work, a metal oxide (MOX) sensor based on zinc oxide (ZnO) was prepared and tested for possible use in the monitoring of low concentrations of hexanal. The sensor was expected to detect the target volatile with minimum interference from all the others, when released all at the same time. For this purpose, the ZnO sensor was exposed to both pure and different mixtures of vapors of the main competing organic compounds. Comparing the results of the mixtures to the response relating to pure hexanal, it was highlighted that the presence of 1-pentanol and 1-octen-3-ol decreases the response of the sensor to hexanal in terms of the eR/R0 ratio, especially at low concentrations (5–10 ppm), while at 50 ppm, the sensor response was comparable with the hexanal quantity, proving that its detection was less affected at higher concentrations. Full article
(This article belongs to the Special Issue Advanced Materials and Nanotechnology for Sustainable Energy and Environmental Applications)
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<p>Electron microscopy (SEM) image of the ZnO powder as prepared at 298 K and after the annealing treatment at 673 K (<b>a</b>), X-ray patterns of ZnO from 298 K to 673 K and (inset) the temperature shift at 2θ = 31.7° (<b>b</b>).</p> Full article ">Figure 2
<p>(<b>a</b>) Comparison of the sensor’s response to pure compounds according to data from <a href="#applsci-12-02261-t002" class="html-table">Table 2</a> and (<b>b</b>) the transient response of the ZnO sensor to pure volatiles at 5 (<b>top</b>) and 50 ppm (<b>bottom</b>).</p> Full article ">Figure 3
<p>(<b>a</b>) Sensor’s response to hexanal/1-pentanol mixtures (data from <a href="#applsci-12-02261-t004" class="html-table">Table 4</a>) and (<b>b</b>) transient response to mixture 98/2 (hexanal/1-pentanol) at 5 (<b>top</b>) and 50 ppm (<b>bottom</b>).</p> Full article ">Figure 4
<p>(<b>a</b>) Sensor’s response to hexanal/1-octen-3-ol mixtures (data from <a href="#applsci-12-02261-t004" class="html-table">Table 4</a>) and (<b>b</b>) transient response to mixture 98/2 (hexanal/1-octen-3-ol mixtures) at 50 (<b>top</b>) and 50 ppm (<b>bottom</b>).</p> Full article ">Figure 5
<p>(<b>a</b>) Sensor’s response to the ternary mixture 96/2/2 (data from <a href="#applsci-12-02261-t004" class="html-table">Table 4</a>) and (<b>b</b>) the transient response of the ZnO sensor to the ternary mixture 96/2/2 for 5 (<b>top</b>) and 50 ppm (<b>bottom</b>).</p> Full article ">
16 pages, 27741 KiB  
Article
oneM2M-Enabled Prediction of High Particulate Matter Data Based on Multi-Dense Layer BiLSTM Model
by Aji Teguh Prihatno, Ida Bagus Krishna Yoga Utama and Yeong Min Jang
Appl. Sci. 2022, 12(4), 2260; https://doi.org/10.3390/app12042260 - 21 Feb 2022
Cited by 4 | Viewed by 2261
Abstract
High particulate matter (PM) concentrations in the cleanroom semiconductor factory have become a significant concern as they can damage electronic devices during the manufacturing process. PM can be predicted before becoming more concentrated based on its historical data to support factory management in [...] Read more.
High particulate matter (PM) concentrations in the cleanroom semiconductor factory have become a significant concern as they can damage electronic devices during the manufacturing process. PM can be predicted before becoming more concentrated based on its historical data to support factory management in regulating the air quality in the cleanroom. In this paper, a Multi-Dense Layer BiLSTM model is proposed to predict PM2.5 concentrations in the indoor environment of the cleanroom. To obtain reliability, validity, and interoperability data, the datasets containing temperature, humidity, PM0.3, PM0.5, PM1, PM2.5, PM5, and PM10 were retrieved in a standardized manner via oneM2M-defined representational state transfer application programmable interfaces by employing software platforms compliant with the Internet of Things (IoT) standard. Based on the proposed model, an algorithm was built providing short-term PM2.5 concentration predictions (one hour ahead, two hours ahead, and three hours ahead). The proposed model outperformed the RNN, LSTM, CNN-LSTM, and Single-Dense Layer BiLSTM models in terms of MSE, MAE, and MAPE values. The model created in this study could predict high PM2.5 concentration levels more accurately, thus providing vital support for operation and maintenance for the semiconductor industry. Full article
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<p>General architecture of this study.</p> Full article ">Figure 2
<p>IoT platform design and architecture with MQTT.</p> Full article ">Figure 3
<p>The oneM2M architecture model.</p> Full article ">Figure 4
<p>Real-time sensor data acquisition visualization using oneM2M browser application.</p> Full article ">Figure 5
<p>Proposed architecture of Multi-Dense Layer BiLSTM model.</p> Full article ">Figure 6
<p>Result of loss function using the proposed model for 1 h ahead prediction (<b>a</b>,<b>b</b>) 20 epochs. (<b>c</b>,<b>d</b>) 35 epochs. (<b>e</b>,<b>f</b>) 50 epochs.</p> Full article ">Figure 6 Cont.
<p>Result of loss function using the proposed model for 1 h ahead prediction (<b>a</b>,<b>b</b>) 20 epochs. (<b>c</b>,<b>d</b>) 35 epochs. (<b>e</b>,<b>f</b>) 50 epochs.</p> Full article ">Figure 7
<p>Comparison of all models to predict PM2.5 concentrations for one hour ahead.</p> Full article ">Figure A1
<p>Result of loss function using the proposed model for 2 h ahead prediction (<b>a</b>,<b>b</b>) 20 epochs. (<b>c</b>,<b>d</b>) 35 epochs. (<b>e</b>,<b>f</b>) 50 epochs.</p> Full article ">Figure A2
<p>The accuracy of prediction using the proposed model for 3 h ahead prediction (<b>a</b>,<b>b</b>) 20 epochs. (<b>c</b>,<b>d</b>) 35 epochs. (<b>e</b>,<b>f</b>) 50 epochs.</p> Full article ">
13 pages, 999 KiB  
Article
Securing Remote State Estimation against Sequential Logic Attack of Sensor Data
by Jing Wang and Tao Feng
Appl. Sci. 2022, 12(4), 2259; https://doi.org/10.3390/app12042259 - 21 Feb 2022
Viewed by 1765
Abstract
The SCADA system, which is widely used in the continuous monitoring and control of the physical process of modern critical infrastructure, relies on the feedback control loop. The remote state estimation system triggers the control algorithm or control condition of the controller according [...] Read more.
The SCADA system, which is widely used in the continuous monitoring and control of the physical process of modern critical infrastructure, relies on the feedback control loop. The remote state estimation system triggers the control algorithm or control condition of the controller according to the monitoring data returned by the sensor. The controller sends the control command to the actuator, and the actuator executes the command to control the physical process. Since SCADA system monitoring and control data are usually transmitted through unprotected wireless communication networks, attackers can use false sensor data to trigger control algorithms to make wrong decisions, disrupt the physical processing of the SCADA system, and cause huge economic losses, even casualties. We found an attack strategy based on the sequential logic of sensor data. This kind of attack changes the time logic or sequence logic of the response data, so that the false data detector can be successfully deceived. This would cause the remote state estimation system to trigger wrong control algorithms or control conditions, and eventually disrupt or destroy the physical process. This paper proposes a sequential signature scheme based on the one-time signature to secure the sequential logic and transmission of sensor data. The security analysis proves that the proposed scheme can effectively resist counterfeiting, forgery, denial, replay attacks, and selective forwarding attacks. Full article
(This article belongs to the Special Issue Selected Papers from FCPAE2021 and 3rd International Conference on Artificial Intelligence and Advanced Manufacturing (AIAM2021))
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<p>Model of SCADA control system.</p> Full article ">Figure 2
<p>Network attack model.</p> Full article ">
21 pages, 6604 KiB  
Article
Glass Beads for Road Markings: Surface Damage and Retroreflection Decay Study
by Kevin M. Wenzel, Tomasz E. Burghardt, Anton Pashkevich and Wilhelm A. Buckermann
Appl. Sci. 2022, 12(4), 2258; https://doi.org/10.3390/app12042258 - 21 Feb 2022
Cited by 16 | Viewed by 4706
Abstract
Road markings must be reflectorised with glass beads to be visible to drivers at night, retro-reflecting light from vehicle’s headlights, which is critical for road safety. Four commonly used types of glass beads were evaluated in a laboratory setting for retroreflectivity and their [...] Read more.
Road markings must be reflectorised with glass beads to be visible to drivers at night, retro-reflecting light from vehicle’s headlights, which is critical for road safety. Four commonly used types of glass beads were evaluated in a laboratory setting for retroreflectivity and their surfaces were analysed using optical and scanning electron microscopy. The glass beads were subjected to abrasion and a visual correlation was sought between the measured retroreflectivity and the surface damage. Scratching the glass bead surface with corundum in a rotary drum resulted in major differences in the rates of damage development, depending on the type of the glass beads, and it could be correlated with the rate of retroreflectivity decay. The relative results from abrasion testing were confirmed under tyre action during a turntable evaluation. Based on the outcomes of these tests, service lives, defined as maintaining appropriately high retroreflectivity, were predicted and used to calculate the consumption of raw materials—the basic sustainability parameter. It was shown that the use of ‘premium’ glass beads, enhanced with TiO2 and made in a proprietary process, provided the road marking system characterised by the lowest long-term consumption of resources. Full article
(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)
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<p>Schematic drawing of the abrasive test setup.</p> Full article ">Figure 2
<p>Loss of R<sub>L</sub> under abrasive testing.</p> Full article ">Figure 3
<p>Loss of R<sub>L</sub> (dry conditions) under turntable testing.</p> Full article ">Figure 4
<p>Microscope images (magnification 4×) of freshly applied GB: (<b>a</b>) <span class="html-italic">standard</span> (sample <span class="html-italic">SF</span>), (<b>b</b>) <span class="html-italic">large</span> (sample <span class="html-italic">ML</span>), (<b>c</b>) <span class="html-italic">premium</span> (sample <span class="html-italic">SP</span>), (<b>d</b>) <span class="html-italic">high index</span> (sample <span class="html-italic">HI</span>).</p> Full article ">Figure 5
<p>Microscope images (magnification 32×) of GB after exposure to 168 drum rotations with corundum: (<b>a</b>) <span class="html-italic">standard</span> (sample <span class="html-italic">SF</span>), (<b>b</b>) <span class="html-italic">large</span> (sample <span class="html-italic">ML</span>), (<b>c</b>) <span class="html-italic">premium</span> (sample <span class="html-italic">SP</span>), (<b>d</b>) <span class="html-italic">high index</span> (sample <span class="html-italic">HI</span>).</p> Full article ">Figure 5 Cont.
<p>Microscope images (magnification 32×) of GB after exposure to 168 drum rotations with corundum: (<b>a</b>) <span class="html-italic">standard</span> (sample <span class="html-italic">SF</span>), (<b>b</b>) <span class="html-italic">large</span> (sample <span class="html-italic">ML</span>), (<b>c</b>) <span class="html-italic">premium</span> (sample <span class="html-italic">SP</span>), (<b>d</b>) <span class="html-italic">high index</span> (sample <span class="html-italic">HI</span>).</p> Full article ">Figure 6
<p>Microscope images (magnification 32×) of GB after exposure to 840 drum rotations with corundum: (<b>a</b>) <span class="html-italic">standard</span> (sample <span class="html-italic">SF</span>), (<b>b</b>) <span class="html-italic">large</span> (sample <span class="html-italic">ML</span>), (<b>c</b>) <span class="html-italic">premium</span> (sample <span class="html-italic">SP</span>), (<b>d</b>) <span class="html-italic">high index</span> (sample <span class="html-italic">HI</span>).</p> Full article ">Figure 6 Cont.
<p>Microscope images (magnification 32×) of GB after exposure to 840 drum rotations with corundum: (<b>a</b>) <span class="html-italic">standard</span> (sample <span class="html-italic">SF</span>), (<b>b</b>) <span class="html-italic">large</span> (sample <span class="html-italic">ML</span>), (<b>c</b>) <span class="html-italic">premium</span> (sample <span class="html-italic">SP</span>), (<b>d</b>) <span class="html-italic">high index</span> (sample <span class="html-italic">HI</span>).</p> Full article ">Figure 7
<p>Exemplary severely damaged GB (<span class="html-italic">high index</span>, sample <span class="html-italic">HI</span>) after exposure to 6720 drum rotations. Microscope image (magnification 32×).</p> Full article ">Figure 8
<p>SEM images (magnification 150×) of GB after exposure to 168 drum rotations with corundum: (<b>a</b>) <span class="html-italic">standard</span> (sample <span class="html-italic">SF</span>), (<b>b</b>) <span class="html-italic">large</span> (sample <span class="html-italic">ML</span>), (<b>c</b>) <span class="html-italic">premium</span> (sample <span class="html-italic">SP</span>), (<b>d</b>) <span class="html-italic">high index</span> (sample <span class="html-italic">HI</span>).</p> Full article ">Figure 9
<p>Example of severely damaged GB (<span class="html-italic">high index</span>, sample <span class="html-italic">HI</span>) after 6720 drum rotations. SEM image (magnification 90×).</p> Full article ">Figure 10
<p>Relative long-term material consumption to maintain R<sub>L</sub> &gt; 150 mcd/m<sup>2</sup>/lx for 100,000 drum rotations (abrasive testing). The <span class="html-italic">premium</span> GB (sample <span class="html-italic">SP</span>) was assumed as 1.0 (arbitrary unitless scale).</p> Full article ">Figure 11
<p>Relative long-term material consumption to maintain R<sub>L</sub> &gt; 500 mcd/m<sup>2</sup>/lx for 1 × 10<sup>8</sup> tyre passes (turntable testing). The sample <span class="html-italic">SH<sup>t</sup></span> (70% <span class="html-italic">premium</span> GB mixed with 30% <span class="html-italic">high index</span> GB) was defined as 1.0 (arbitrary unitless scale).</p> Full article ">
17 pages, 3617 KiB  
Article
The Influence of Fly Ash on the Mechanical Performance of Cementitious Materials Produced with Recycled Cement
by Blas Cantero, Miguel Bravo, Jorge de Brito, Isabel Fuencisla Sáez del Bosque and César Medina
Appl. Sci. 2022, 12(4), 2257; https://doi.org/10.3390/app12042257 - 21 Feb 2022
Cited by 15 | Viewed by 2561
Abstract
Concrete is the most widely used construction material in the world; as such, the best way to promote a more sustainable construction industry is to improve the environmental performance of this material. Since cement production is the main source of the high environmental [...] Read more.
Concrete is the most widely used construction material in the world; as such, the best way to promote a more sustainable construction industry is to improve the environmental performance of this material. Since cement production is the main source of the high environmental impact of concrete, due to the high calcination temperature that clinker requires, replacing this binder with recycled cement would allow for the establishment of a new concrete design with a much lower ecological footprint. This research intends to analyse the mechanical performance of mortars with recycled cement and fly ash. Mixes with two replacement ratios of recycled cement (5% and 10%) were studied separately or in combination with fly ash (10% and 20%). An exhaustive experimental programme was designed to assess the variation in air content, density, compressive and flexural strengths, modulus of elasticity, and ultrasonic pulse velocity. The results suggest that the simultaneous use of recycled cement and fly ash improves the mechanical performance of mortars relative to those with recycled cement only or fly ash only. Full article
(This article belongs to the Special Issue Nanotechnology in Cement-Based Construction: Trends and Challenges)
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<p>SEM image for FA.</p> Full article ">Figure 2
<p>SEM image for RC.</p> Full article ">Figure 3
<p>(<b>a</b>) Air content as a function of consistency (<b>b</b>) and variation in density with OPC replacement in the mixes.</p> Full article ">Figure 4
<p>Results of (<b>a</b>) compressive strength and (<b>b</b>) strength activity index between 7 and 365 days of curing.</p> Full article ">Figure 5
<p>Results of flexural strength between 7 and 365 days of curing (<b>a</b>,<b>b</b>) and flexural strength as function of the square root of the compressive strength (at the same age).</p> Full article ">Figure 6
<p>Dynamic modulus of elasticity at 91 and 365 days as a function of the square root of the compressive strength (at the same age).</p> Full article ">Figure 7
<p>Results of ultrasonic pulse velocity at 91 and 365 days of curing (<b>a</b>,<b>b</b>) on the compressive strength, <span class="html-italic">f<sub>cm</sub></span>, of the mortar as a function of the ultrasonic pulse velocity, UPV.</p> Full article ">Figure 8
<p>Energy performance at (<b>a</b>) 7 days and ((<b>b)</b> 365 days of mortars.</p> Full article ">Figure 9
<p>Quantification of synergistic effects on the 7-day and 365-day energy performance of the mortars.</p> Full article ">
15 pages, 2765 KiB  
Article
Chronic Effects of Fluoxetine on Danio rerio: A Biochemical and Behavioral Perspective
by Daniela Correia, Inês Domingues, Melissa Faria and Miguel Oliveira
Appl. Sci. 2022, 12(4), 2256; https://doi.org/10.3390/app12042256 - 21 Feb 2022
Cited by 14 | Viewed by 3163
Abstract
Fluoxetine is an antidepressant widely used to treat depressive and anxiety states. Due to its mode of action in the central nervous system (selective serotonin reuptake inhibitor (SSRI)), it becomes toxic to non-target organisms, leading to changes that are harmful to their survival. [...] Read more.
Fluoxetine is an antidepressant widely used to treat depressive and anxiety states. Due to its mode of action in the central nervous system (selective serotonin reuptake inhibitor (SSRI)), it becomes toxic to non-target organisms, leading to changes that are harmful to their survival. In this work, the effects of fluoxetine on juvenile zebrafish (Danio rerio) were evaluated, assessing biochemical (phase II biotransformation—glutathione S-transferase (GST), neurotransmission—acetylcholinesterase (ChE), energy metabolism—lactate dehydrogenase (LDH), and oxidative stress—glutathione peroxidase (GPx)) and behavior endpoints (swimming behavior, social behavior, and thigmotaxis) after 21 days exposure to 0 (control), 0.1, 1 and 10 µg/L. Biochemically, although chronic exposure did not induce significant effects on neurotransmission and energy metabolism, GPx activity was decreased after exposure to 10 µg/L of fluoxetine. At a behavioral level, exploratory and social behavior was not affected. However, changes in the swimming pattern of exposed fish were observed in light and dark periods (decreased locomotor activity). Overall, the data show that juvenile fish chronically exposed to fluoxetine may exhibit behavioral changes, affecting their ability to respond to environmental stressors and the interaction with other fish. Full article
(This article belongs to the Special Issue Emerging Effects of Pollutants in the Aquatic Environment)
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<p>Effects of fluoxetine concentrations on locomotor activity and thigmotactic behavior of juvenile zebrafish, in response to dark and light cycles, after 12 days exposure. (<b>A</b>)—Total swimming distance traveled by the juvenile zebrafish; (<b>B</b>)—Total time spent swimming; (<b>C</b>)—Total distance traveled in the outer zone; (<b>D</b>)—Total time spent swimming in the outer zone. Results are expressed as mean values ± standard error (<a href="#app1-applsci-12-02256" class="html-app">Supplementary Material, Table S1</a>). Yellow bars represent the light period and grey bars represent the dark period. Asterisks (*) indicate differences towards the control and the symbol “#” indicates differences between dark and light periods in their respective concentrations (Two-way ANOVA, Holm–Sidak method, <span class="html-italic">p</span> &lt; 0.05).</p> Full article ">Figure 2
<p>Effects of fluoxetine concentrations on locomotor activity and thigmotactic behavior of zebrafish, in response to dark and light cycles, after 21 days exposure. (<b>A</b>)—Total swimming distance traveled by the juvenile zebrafish; (<b>B</b>)—Total time spent swimming; (<b>C</b>)—Total swimming distance traveled in the outer zone; (<b>D</b>)—Total time spent swimming in the outer zone. Results are expressed as mean values ± standard error (<a href="#app1-applsci-12-02256" class="html-app">Supplementary Material, Table S2</a>). Yellow bars represent the light period and grey bars represent the dark period. Asterisks (*) indicate differences towards the control and the symbol “#” indicates that the dark and light periods are different from each other in their respective concentrations (Two-way ANOVA, Holm–Sidak method, <span class="html-italic">p</span> &lt; 0.05).</p> Full article ">Figure 3
<p>Percentage of frequency of class 1 and 4 angles (mean values ± standard error (<a href="#app1-applsci-12-02256" class="html-app">Supplementary Material, Table S3</a>)) after 12 (<b>A</b>,<b>B</b>) and 21 days (<b>C</b>,<b>D</b>). Yellow bars represent the light period and grey bars represent the dark period. Asterisks (*) indicate differences towards the control and the symbol “#” indicates that the dark and light stimuli are different from each other in their respective concentrations (Two-way ANOVA, Holm–Sidak method, <span class="html-italic">p</span> &lt; 0.05).</p> Full article ">Figure 4
<p>Effects of fluoxetine concentrations on zebrafish exploratory behavior (swimming behavior at bottom, middle, and top layers of the tank), after 21-days exposure. Results are expressed as a percentage of time spent in tank layers (<a href="#app1-applsci-12-02256" class="html-app">Supplementary Material, Table S4</a>).</p> Full article ">Figure 5
<p>Effects of fluoxetine concentrations on the social behavior of zebrafish, after 21-days exposure, discriminated between zone 1—Proximity Zone, zone 2—Neutral zone near the shoal, and zone 3—Neutral zone away from the shoal. Results are expressed as mean values ± standard error (<a href="#app1-applsci-12-02256" class="html-app">Supplementary Material, Table S5</a>).</p> Full article ">Figure 6
<p>Effects of fluoxetine concentrations on zebrafish enzymatic activities: (<b>A</b>)—Glutathione S-transferase (GST) activity; (<b>B</b>)—Glutathione peroxidase (GPx) activity; (<b>C</b>)—Cholinesterase (ChE) activity; (<b>D</b>)—Lactate Dehydrogenase (LDH) activity. Results are expressed as mean values ± standard error (<a href="#app1-applsci-12-02256" class="html-app">Supplementary Material, Table S6</a>). Asterisks (*) indicate differences towards the control (One Way ANOVA, Dunnett’s Method, <span class="html-italic">p</span> &lt; 0.05).</p> Full article ">
9 pages, 15985 KiB  
Article
Electrical Equalization Analysis of PAM-4 Transmission in Short-Reach Optical Systems
by Dana Arie and Gilad Katz
Appl. Sci. 2022, 12(4), 2255; https://doi.org/10.3390/app12042255 - 21 Feb 2022
Viewed by 2354
Abstract
Inclusive and intensive performance analysis of electrical equalizers in a short-reach optical system using four-level pulse amplitude modulation (PAM-4) is presented in this paper. Two equalizers are used—a feedforward equalizer and decision feedback equalizer using the least mean square algorithm. The sensitivity to [...] Read more.
Inclusive and intensive performance analysis of electrical equalizers in a short-reach optical system using four-level pulse amplitude modulation (PAM-4) is presented in this paper. Two equalizers are used—a feedforward equalizer and decision feedback equalizer using the least mean square algorithm. The sensitivity to cut-off frequency for the transmitter and receiver filters, fiber length and number of equalizers taps in the means of the bit error rate vs. optical input power are shown. The analysis reveals the considerable impact of the filters’ bandwidth, particularly in the receiver, on the equalizer performance. These results and their reasons are analyzed and broadly discussed. Full article
(This article belongs to the Special Issue Optics in Information and Communication Technologies)
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<p>Block diagram of an optical communication system.</p> Full article ">Figure 2
<p>The organization of the code running.</p> Full article ">Figure 3
<p>(<b>a</b>) histograms of the received signal, before the equalizer with different fiber length = 0.5, 2.5, 3.5 km. <math display="inline"><semantics> <mrow> <msub> <mi>f</mi> <mi>c</mi> </msub> </mrow> </semantics></math> = 0.75 <span class="html-italic">R<sub>s</sub></span> Hz, OIP = −10 dBm. (<b>b</b>) BER curve for three different fiber length = 0.5, 1.5, 2.5, 3.5 km, and two equalizers FFE with <math display="inline"><semantics> <mrow> <msub> <mi>N</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>6</mn> </mrow> </semantics></math>, DFE with <math display="inline"><semantics> <mrow> <msub> <mi>N</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>6</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>N</mi> <mn>2</mn> </msub> <mo>=</mo> <mn>3</mn> </mrow> </semantics></math>. RX <math display="inline"><semantics> <mrow> <msub> <mi>f</mi> <mi>c</mi> </msub> <mo>=</mo> <mn>0.7</mn> <msub> <mi>R</mi> <mi>s</mi> </msub> </mrow> </semantics></math>, TX <math display="inline"><semantics> <mrow> <msub> <mi>f</mi> <mi>c</mi> </msub> <mo>=</mo> <mn>0.55</mn> <msub> <mi>R</mi> <mi>s</mi> </msub> </mrow> </semantics></math>.</p> Full article ">Figure 4
<p>Impact of number of taps on the penalty for desirable BER = 1 × 10<sup>−4</sup>, where 0 dB penalty corresponding to OIP of −14 dBm. (<b>a</b>) FFE with <math display="inline"><semantics> <mrow> <msub> <mi>N</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>2</mn> <mo>,</mo> <mn>6</mn> <mo>,</mo> <mn>10</mn> </mrow> </semantics></math> (<b>b</b>) DFE with <math display="inline"><semantics> <mrow> <msub> <mi>N</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>6</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <msub> <mi>N</mi> <mn>2</mn> </msub> <mo>=</mo> <mn>2</mn> <mo>,</mo> <mn>3</mn> <mo>,</mo> <mn>5</mn> </mrow> </semantics></math>. Fiber length 0.5, 2.5 km, variable combination of filter <math display="inline"><semantics> <mrow> <msub> <mi>f</mi> <mi>c</mi> </msub> </mrow> </semantics></math> as mentioned in the legend.</p> Full article ">Figure 5
<p>Penalty graph for desirable BER = 1 × 10<sup>−4</sup>, where 0 dBm OIP penalty corresponding to −14 dBm. (<b>a</b>) FFE with <math display="inline"><semantics> <mrow> <msub> <mi>N</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>6</mn> </mrow> </semantics></math> (<b>b</b>) DFE with <math display="inline"><semantics> <mrow> <msub> <mi>N</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>6</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <msub> <mi>N</mi> <mn>2</mn> </msub> <mo>=</mo> <mn>3</mn> </mrow> </semantics></math>.</p> Full article ">Figure 6
<p>Isolated noise model—penalty graph for desirable BER = 1 × 10<sup>−4</sup>, where 0 dBm OIP penalty corresponding to −14 dBm. (<b>a</b>) FFE with <math display="inline"><semantics> <mrow> <msub> <mi>N</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>6</mn> </mrow> </semantics></math> (<b>b</b>) DFE with 6 <math display="inline"><semantics> <mrow> <msub> <mi>N</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>6</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <msub> <mi>N</mi> <mn>2</mn> </msub> <mo>=</mo> <mn>3</mn> </mrow> </semantics></math>.</p> Full article ">
18 pages, 6659 KiB  
Article
Wind Forces and Flow Patterns of Three Tandem Prisms with a Small Height–Width Ratio
by Kun Du and Bo Chen
Appl. Sci. 2022, 12(4), 2254; https://doi.org/10.3390/app12042254 - 21 Feb 2022
Cited by 2 | Viewed by 1626
Abstract
Wind tunnel tests and large eddy simulations were conducted to investigate the dependency of wind forces and flow patterns on the spacing (S) for three tandem prisms with a small height–width ratio H/W = 0.4. At the spacing ratio S/W = [...] Read more.
Wind tunnel tests and large eddy simulations were conducted to investigate the dependency of wind forces and flow patterns on the spacing (S) for three tandem prisms with a small height–width ratio H/W = 0.4. At the spacing ratio S/W = 0.7, mean and root-mean-square drag of downstream prisms have large local peaks, and their magnitudes are larger than those at adjacent spacing ratios; these should be noted to ensure the safety and economy of the wind-resistant design of prism-like low-rise buildings. These phenomena are different from that of a small group of tandem prisms with a large H/W and a large group of tandem prisms with a small H/W. At S/W = 0.7, tap pressure time histories of downstream prisms are non-stationary with abrupt changes, but wind force time histories of downstream prisms are stationary, unlike a small group of tandem prisms with a large H/W, where both tap pressure and win d force time histories are non-stationary. Above phenomena at S/W = 0.7 are attributed to a special asymmetric time-averaged wake regime, which has two modes with symmetric wake flow directions and they irregularly switch. The duration of each mode is ruleless. This special wake regime was not observed in previous studies on tandem prisms. Full article
(This article belongs to the Special Issue Structural Response in Transient Winds of Hurricane and Non-synoptic Events)
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<p>Information of incident flow: (<b>a</b>) Simulated atmosphere boundary layer; (<b>b</b>) Longitudinal power spectrum density.</p> Full article ">Figure 2
<p>Prism configuration and pressure tap arrangement: (<b>a</b>) Prisms arrangement and wind direction; (<b>b</b>) Prism pressure taps.</p> Full article ">Figure 3
<p>The schematic of computational domain and boundary conditions.</p> Full article ">Figure 4
<p>Computational meshes near the prisms model (Basic grids): (<b>a</b>) Horizontal section at <span class="html-italic">Z/H</span> = 0.5; (<b>b</b>) Vertical section at <span class="html-italic">Y/W</span> = 0.</p> Full article ">Figure 5
<p>Relative difference (<math display="inline"><semantics> <mi>ε</mi> </semantics></math>) of wind forces between the experimental and LES: (<b>a</b>) Mean <span class="html-italic">C<sub>D</sub></span> and Mean <span class="html-italic">C<sub>RL</sub></span>; (<b>b</b>) RMS <span class="html-italic">C<sub>D</sub></span> and RMS <span class="html-italic">C<sub>RL</sub></span>.</p> Full article ">Figure 6
<p>Pressure coefficients of the isolate prism: (<b>a</b>) Mean pressure coefficients; (<b>b</b>) RMS pressure coefficients.</p> Full article ">Figure 7
<p>Interfered wind forces of three tandem prisms: (<b>a</b>) Interference factors of drag coefficients; (<b>b</b>) Interference factors of roof uplift coefficients; (<b>c</b>) Lateral lift coefficients.</p> Full article ">Figure 8
<p>Pressure coefficient time histories in taps of prisms: (<b>a</b>) Pressure taps on windward wall and leeward wall; (<b>b</b>) Spacing ratio: 0.2; (<b>c</b>) Spacing ratio: 0.7; (<b>d</b>) Spacing ratio: 1.2.</p> Full article ">Figure 8 Cont.
<p>Pressure coefficient time histories in taps of prisms: (<b>a</b>) Pressure taps on windward wall and leeward wall; (<b>b</b>) Spacing ratio: 0.2; (<b>c</b>) Spacing ratio: 0.7; (<b>d</b>) Spacing ratio: 1.2.</p> Full article ">Figure 9
<p>Drag coefficient time histories of three prisms at the spacing ratio of 0.7.</p> Full article ">Figure 10
<p>Pressure coefficients on walls in period C-1 (Spacing ratio: 0.7): (<b>a</b>) Period C-1 (42 s–45 s); (<b>b</b>) Mean <math display="inline"><semantics> <mrow> <msub> <mi>C</mi> <mi>p</mi> </msub> </mrow> </semantics></math>; (<b>c</b>) RMS <math display="inline"><semantics> <mrow> <msub> <mi>C</mi> <mi>p</mi> </msub> </mrow> </semantics></math>.</p> Full article ">Figure 11
<p>Pressure coefficients on walls in period C-2 (Spacing ratio: 0.7): (<b>a</b>) Period C-2 (57 s–60 s); (<b>b</b>) Mean <math display="inline"><semantics> <mrow> <msub> <mi>C</mi> <mi>p</mi> </msub> </mrow> </semantics></math>; (<b>c</b>) RMS <math display="inline"><semantics> <mrow> <msub> <mi>C</mi> <mi>p</mi> </msub> </mrow> </semantics></math>.</p> Full article ">Figure 12
<p>Simulated pressure coefficient time histories in taps of prisms (Spacing ratio: 0.7).</p> Full article ">Figure 13
<p>Mean pressure coefficient on walls (Spacing ratio: 0.7): (<b>a</b>) Sampled period (9 s to 12 s); (<b>b</b>) Sampled period (25 s to 28 s).</p> Full article ">Figure 14
<p>RMS pressure coefficient on walls (Spacing ratio: 0.7): (<b>a</b>) Sampled period (9 s to 12 s); (<b>b</b>) Sampled period (25 s to 28 s).</p> Full article ">Figure 15
<p>Velocity magnitude and streamlines of horizontal section (<span class="html-italic">Z =</span> 0.5 <span class="html-italic">H</span>): (<b>a</b>) Isolated prism; (<b>b</b>) Spacing ratio: 0.2; (<b>c-1</b>) Spacing ratio: 0.7 (Period 0 s–12 s); (<b>c-2</b>) Spacing ratio: 0.7 (Period 24 s–30 s); (<b>d</b>) Spacing ratio: 1.2.</p> Full article ">Figure 16
<p>Velocity magnitude and streamlines of vertical section (<span class="html-italic">Y =</span> 0): (<b>a</b>) Isolated prism; (<b>b</b>) Spacing ratio: 0.2; (<b>c-1</b>) Spacing ratio: 0.7 (Period 0 s–12 s); (<b>c-2</b>) Spacing ratio: 0.7 (Period 24 s–30 s); (<b>d</b>) Spacing ratio: 1.2.</p> Full article ">
16 pages, 2137 KiB  
Article
SFINet: Shuffle–and–Fusion Interaction Networks for Wind Power Forecasting
by Xu Zhang, Cheng Xiao and Tieling Zhang
Appl. Sci. 2022, 12(4), 2253; https://doi.org/10.3390/app12042253 - 21 Feb 2022
Cited by 2 | Viewed by 2375
Abstract
Wind energy is one of the most important renewable energy sources in the world. Accurate wind power prediction is of great significance for achieving reliable and economical power system operation and control. For this purpose, this paper is focused on wind power prediction [...] Read more.
Wind energy is one of the most important renewable energy sources in the world. Accurate wind power prediction is of great significance for achieving reliable and economical power system operation and control. For this purpose, this paper is focused on wind power prediction based on a newly proposed shuffle–and–fusion interaction network (SFINet). First, a channel shuffle is employed to promote the interaction between timing features. Second, an attention block is proposed to fuse the original features and shuffled features to further increase the model’s sequential modeling capability. Finally, the developed shuffle–and–fusion interaction network model is tested using real-world wind power production data. Based on the results verified, it was proven that the proposed SFINet model can achieve better performance than other baseline methods, and it can be easily implemented in the field without requiring additional hardware and software. Full article
(This article belongs to the Topic Machine and Deep Learning)
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<p>Typical deep-learning network structure for processing time series tasks [<a href="#B23-applsci-12-02253" class="html-bibr">23</a>,<a href="#B51-applsci-12-02253" class="html-bibr">51</a>,<a href="#B53-applsci-12-02253" class="html-bibr">53</a>,<a href="#B54-applsci-12-02253" class="html-bibr">54</a>].</p> Full article ">Figure 2
<p>The overall architecture of the Sample Convolution and Interaction Network (SCINet) [<a href="#B23-applsci-12-02253" class="html-bibr">23</a>].</p> Full article ">Figure 3
<p>Shuffle swap split-sequence features.</p> Full article ">Figure 4
<p>Fusion with channel attention.</p> Full article ">Figure 5
<p>The prediction comparison between SFINet and SCINet for different datasets.</p> Full article ">
17 pages, 6880 KiB  
Article
Research on the Flow and Transmission Performance of Magnetorheological Fluid between Two Discs
by Jin Huang, Wenjian Chen, Ruizhi Shu and Jing Wei
Appl. Sci. 2022, 12(4), 2252; https://doi.org/10.3390/app12042252 - 21 Feb 2022
Cited by 3 | Viewed by 1938
Abstract
The viscoplastic flow of magnetorheological fluid in a disc was analyzed based on the Navier–Stokes Momentum Equation, and the yielded and unyielded decomposition surfaces were obtained. For the shear-thinning phenomenon of magnetorheological fluid, the magnetorheological properties of the magnetorheological fluid were described based [...] Read more.
The viscoplastic flow of magnetorheological fluid in a disc was analyzed based on the Navier–Stokes Momentum Equation, and the yielded and unyielded decomposition surfaces were obtained. For the shear-thinning phenomenon of magnetorheological fluid, the magnetorheological properties of the magnetorheological fluid were described based on the Herschel–Bulkley model. Then, the relationship between torque, magnetic field, material, size and motion was established, and the magnetic field and working gap were optimized and analyzed. The results show that in the unyielding region, the magnetorheological fluid flows rigidly. In the yielding region, it flows as a viscous fluid. The degree of error of the proposed torque equation decreased gradually with the increase to current, as observed by experimental comparison. Full article
(This article belongs to the Special Issue Intelligent and Bionic Transmission in Machinery)
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<p>Structure diagram of an MR transmission. (<b>a</b>) Schematic diagram, (<b>b</b>) Structure diagram.</p> Full article ">Figure 2
<p>Circumferential flow of magnetorheological fluid (MRF) between two discs.</p> Full article ">Figure 3
<p>Rheological characteristic curve of MRF. (<b>a</b>) Magnetic curve of MRF-1, (<b>b</b>) characteristics of viscosity.</p> Full article ">Figure 4
<p>Equivalent model of transmission device.</p> Full article ">Figure 5
<p>Relationship between yield thickness and load torque.</p> Full article ">Figure 6
<p>Cloud diagram of magnetic field intensity and magnetic vector potential at 3A. (<b>a</b>) h = 1.0 mm with copper gaskets, (<b>b</b>) h = 1.0 mm without copper gaskets.</p> Full article ">Figure 7
<p>Relationship between current and magnetic field intensity. (<b>a</b>) h = 1.0 mm with copper gaskets, (<b>b</b>) h = 1.0 mm without copper gaskets.</p> Full article ">Figure 8
<p>Relationship between apparent viscosity and shear strain rate.</p> Full article ">Figure 9
<p>Flow of MRF in the working gap. (<b>a</b>) Plug flow coefficient of MRF, (<b>b</b>) flow velocity of MRF.</p> Full article ">Figure 10
<p>Flow of MRF in the working gap: (<b>a</b>) region E, (<b>b</b>) region C.</p> Full article ">Figure 11
<p>Flow of MRF under incomplete yielding: (<b>a</b>) flow distribution in the whole working gap, (<b>b</b>) flow velocity of MRF in region A.</p> Full article ">Figure 12
<p>MR transmission performance test bench: (<b>a</b>) control part, (<b>b</b>) testing part.</p> Full article ">Figure 13
<p>Internal structure of the MR transmission device.</p> Full article ">Figure 14
<p>Relationship between current and torque.</p> Full article ">Figure 15
<p>Relationship between current and output disk speed.</p> Full article ">
15 pages, 3965 KiB  
Article
Comparison of Achieved Rolling Resistance Values of Two Selected Tires on a Solid Surface
by Milan Helexa, Ján Kováč, Jozef Krilek, Ján Melicherčík and Tomáš Kuvik
Appl. Sci. 2022, 12(4), 2251; https://doi.org/10.3390/app12042251 - 21 Feb 2022
Cited by 5 | Viewed by 2352
Abstract
The article deals with measuring the rolling resistance of two tires Mitas TS04 6.00-16 6PR and Mitas TS05 10.0/75-15.3 10PR on a concrete surface. The measurement was performed in a soil test channel which had to be adjusted for the given purpose. The [...] Read more.
The article deals with measuring the rolling resistance of two tires Mitas TS04 6.00-16 6PR and Mitas TS05 10.0/75-15.3 10PR on a concrete surface. The measurement was performed in a soil test channel which had to be adjusted for the given purpose. The tires were compared with each other based on the results of the rolling resistance coefficient calculation. The obtained individual values were approximated by linear functions and subsequently subjected to a statistical analysis—a test of the agreement of the regression coefficients of the two basic sets. The results of this analysis showed that there is no statistically significant difference in the values of the achieved rolling resistance coefficients of the monitored tires, although there are differences between them in geometric dimensions and load capacity. The achieved results are basically confirmed by the results of other authors, especially by the fact that on a solid surface the values of the achieved rolling resistances can be reduced by increasing the inflation pressure of the tire. This increase cannot be spontaneous; however, it is always a compromise among the resistances achieved, the life of the tire and its adhesive properties. Full article
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<p>Non-driven wheel rolling on a rigid pad-force diagram.</p> Full article ">Figure 2
<p>Soil test channel without wheel drive installation. (<b>a</b>) Workplace layout, (<b>b</b>) general view of the equipment with weights and handling crane, (<b>c</b>) detailed view of the main frame with the tested tire, (<b>d</b>) auxiliary return winch. 1. Ground channel; 2. Side guide; 3. Main frame with wheel; 4. Guide frame; 5. Braking and winding device.</p> Full article ">Figure 3
<p>Force action when pulling a pneumatic wheel (measurement on a concrete surface). <span class="html-italic">F<sub>c</sub></span>—Total drag force, <span class="html-italic">F<sub>n</sub></span>—Normal tire force, <span class="html-italic">F<sub>v</sub></span>—Rolling resistance, <span class="html-italic">F<sub>mt</sub></span>—Friction resistance force in bearings, <span class="html-italic">F<sub>vv</sub></span>—Resistance force in guide frame guide.</p> Full article ">Figure 4
<p>The course of the recorded tensile resistance of the Mitas TS05 10.0/75-15.3 10PR tire at an inflation pressure of 100 kPa and a vertical load of 350 kg.</p> Full article ">Figure 5
<p>Example of statistical processing of tensile force sets-Mitas TS05 10.0/75-15.3 10PR tire, inflation pressure 100 kPa, vertical load 350 kg.</p> Full article ">Figure 6
<p>The process of measuring the rolling resistances of selected tires on the concrete surface of the laboratory. (<b>a</b>) View of the tested tire and concrete surface; (<b>b</b>) view of the main frame with the wheel; (<b>c</b>) location of the measuring apparatus on the guide frame; (<b>d</b>) general view of the experimental equipment.</p> Full article ">Figure 7
<p>Dependence of rolling resistance on tire inflation pressure at individual load levels—Mitas TS05 10.0/75-15.3 10PR.</p> Full article ">Figure 8
<p>Dependence of rolling resistance on tire inflation pressure at individual load levels—Mitas TS04 6.00-16 6PR.</p> Full article ">Figure 9
<p>Dependence of rolling resistance on tire load at individual inflation pressure levels—Mitas TS04 6.00-16 6PR.</p> Full article ">Figure 10
<p>Dependence of rolling resistance coefficients on tire inflation pressure-load 606 kg.</p> Full article ">Figure 11
<p>Dependence of rolling resistance coefficients on tire inflation pressure—load 478 kg.</p> Full article ">Figure 12
<p>Dependence of rolling resistance coefficients on tire inflation pressure—load 350 kg.</p> Full article ">Figure 13
<p>Dependence of rolling resistance coefficients on tire inflation pressure—load 222 kg.</p> Full article ">
27 pages, 39710 KiB  
Article
Comparative Analysis of Human Operators and Advanced Technologies in the Visual Inspection of Aero Engine Blades
by Jonas Aust and Dirk Pons
Appl. Sci. 2022, 12(4), 2250; https://doi.org/10.3390/app12042250 - 21 Feb 2022
Cited by 22 | Viewed by 4602
Abstract
Background—Aircraft inspection is crucial for safe flight operations and is predominantly performed by human operators, who are unreliable, inconsistent, subjective, and prone to err. Thus, advanced technologies offer the potential to overcome those limitations and improve inspection quality. Method—This paper compares the performance [...] Read more.
Background—Aircraft inspection is crucial for safe flight operations and is predominantly performed by human operators, who are unreliable, inconsistent, subjective, and prone to err. Thus, advanced technologies offer the potential to overcome those limitations and improve inspection quality. Method—This paper compares the performance of human operators with image processing, artificial intelligence software and 3D scanning for different types of inspection. The results were statistically analysed in terms of inspection accuracy, consistency and time. Additionally, other factors relevant to operations were assessed using a SWOT and weighted factor analysis. Results—The results show that operators’ performance in screen-based inspection tasks was superior to inspection software due to their strong cognitive abilities, decision-making capabilities, versatility and adaptability to changing conditions. In part-based inspection however, 3D scanning outperformed the operator while being significantly slower. Overall, the strength of technological systems lies in their consistency, availability and unbiasedness. Conclusions—The performance of inspection software should improve to be reliably used in blade inspection. While 3D scanning showed the best results, it is not always technically feasible (e.g., in a borescope inspection) nor economically viable. This work provides a list of evaluation criteria beyond solely inspection performance that could be considered when comparing different inspection systems. Full article
(This article belongs to the Special Issue Advanced Digital Technologies for the Integration of Production and Maintenance)
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<p>Two types of engine blade inspections: (<b>a</b>) in-situ borescope inspection, (<b>b</b>) on-bench piece-part inspection.</p> Full article ">Figure 2
<p>Sample outputs of piece-part inspection software: (<b>a</b>) correctly detected nicks—true positive, (<b>b</b>) marked deposit and root radius—false positives, (<b>c</b>) missed bend—false negative, (<b>d</b>) missed airfoil dent—false negative. Software detections are indicated by red bounding boxes. Missed defects are highlighted by blue circles.</p> Full article ">Figure 3
<p>Sample output of borescope inspection software: (<b>a</b>) Correctly detected airfoil dents, (<b>b</b>) correctly detected leading edge dent, (<b>c</b>) detected deposit, (<b>d</b>) detected deposit and missed dent on leading edge, (<b>e</b>) missed nick on trailing edge, (<b>f</b>) missed dent in leading edge. Software detections are indicated by red bounding boxes. Missed defects are highlighted by blue circles.</p> Full article ">Figure 4
<p>Different visualisations of the 3D scanning result: (<b>a</b>) heat map indicating different degrees of deviation from reference model, (<b>b</b>) categorical visualisation of three severity levels, (<b>c</b>) categorical visualisation for accept/reject decisions. For illustration purposes only, this figure presents severe defects.</p> Full article ">Figure 5
<p>Scan results for different defect types: (<b>a</b>) tip curl, (<b>b</b>) airfoil dents, (<b>c</b>) nicks and dents.</p> Full article ">Figure 6
<p>Mean plot of inspection accuracy in piece-part inspection by defect type and for different inspection agents.</p> Full article ">Figure 7
<p>Mean plot of inspection accuracy in the borescope inspection by defect type and for different inspection agents.</p> Full article ">Figure 8
<p>Mean plot of inspection accuracy in the visual–tactile inspection by defect type and for different inspection agents.</p> Full article ">Figure 9
<p>Pairwise comparison of criteria for weighted factor analysis.</p> Full article ">Figure 10
<p>Weighted factor analysis for different inspection agents.</p> Full article ">
25 pages, 6611 KiB  
Article
Investigation of the Properties of a Five-Phase Induction Motor in the Introduction of New Fault-Tolerant Control
by Jakub Kellner, Slavomír Kaščák and Želmíra Ferková
Appl. Sci. 2022, 12(4), 2249; https://doi.org/10.3390/app12042249 - 21 Feb 2022
Cited by 4 | Viewed by 2044
Abstract
Multiphase electric motors in cooperation with power semiconductor converters belong to the future of electric drives. This is because of their better properties compared to three-phase motors, such as better fault tolerance. How a multiphase motor will behave in a fault state is [...] Read more.
Multiphase electric motors in cooperation with power semiconductor converters belong to the future of electric drives. This is because of their better properties compared to three-phase motors, such as better fault tolerance. How a multiphase motor will behave in a fault state is very important when using such motors in EV and HEV. This is the basis of the research in this article; we investigate the options for operating a five-phase motor in a fault condition in order to improve the drive qualities during fault operation. The complete mathematical expressions of the five-phase induction motor model in the normal operation as well as in fault operation and also the control modification to improve the properties of the drive are presented. The new five-phase field-oriented control is next described, which improves the drive qualities in four-phase operation and is the first fundamental aspect of the study. Another important aspect of the project is the development of a specific control on a real motor, followed by measurements of properties of a five-phase motor in normal and fault operation of one phase without and with control modification to enhance drive characteristics. The qualities and appropriateness of employing a five-phase motor as a drive in EV and HEV are then determined by comparing these results. Finally, a comparison of motor attributes is shown with and without control adjustment. Full article
(This article belongs to the Special Issue Electrical Machines for Automotive Applications: Dedicated Design Methods and Their Results, Power Electronics and Control)
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<p>The mechanical winding layout of a five-phase induction machine.</p> Full article ">Figure 2
<p>Possibilities of stator windings connection of five-phase induction machine: (<b>a</b>) star connection; (<b>b</b>) pentagon connection; (<b>c</b>) pentacle connection.</p> Full article ">Figure 3
<p>Phase diagram of a five-phase motor: (<b>a</b>) pentagon connection; (<b>b</b>) pentacle connection.</p> Full article ">Figure 4
<p>Graphical representation of the phase current adjustment during operation of a five-phase open-phase induction motor.</p> Full article ">Figure 5
<p>Scheme of vector control of a five-phase induction machine.</p> Full article ">Figure 6
<p>The fault-tolerant control scheme for a five-phase induction machine.</p> Full article ">Figure 7
<p>Currents required to ensure fault-tolerant control.</p> Full article ">Figure 8
<p>Measurement scheme of a five-phase induction motor in fault conditions.</p> Full article ">Figure 9
<p>Motor efficiency, rated torque 3.5 Nm.</p> Full article ">Figure 10
<p>Motor efficiency, constant torque 2 Nm.</p> Full article ">Figure 11
<p>Motor efficiency, constant torque 1 Nm.</p> Full article ">Figure 12
<p>Dependence of power on torque, constant motor speed 2500 rpm.</p> Full article ">Figure 13
<p>Dependence of power on torque, constant motor speed 1500 rpm.</p> Full article ">Figure 14
<p>Dependence of power on torque, constant motor speed 500 rpm.</p> Full article ">Figure 15
<p>Dependence of phase currents on torque, constant motor speed 2500 rpm.</p> Full article ">Figure 16
<p>Dependence of phase currents on torque, constant motor speed 1500 rpm.</p> Full article ">Figure 17
<p>Dependence of phase currents on torque, constant motor speed 500 rpm.</p> Full article ">Figure 18
<p>Torque ripple, normal operation, 2500 rpm, 3.5 Nm.</p> Full article ">Figure 19
<p>Torque ripple, one-phase fault operation, 2500 rpm, 3.5 Nm.</p> Full article ">Figure 20
<p>Torque ripple, edit: nonsymmetric current, 2500 rpm, 3.5 Nm.</p> Full article ">Figure 21
<p>Torque ripple, edit: symmetric current, 2500 rpm, 3.5 Nm.</p> Full article ">Figure 22
<p>Torque ripple dependence for constant nominal motor torque.</p> Full article ">Figure 23
<p>Measurement for normal operation: (<b>a</b>) stator currents; (<b>b</b>) transformation of measured <span class="html-italic">abcde</span> currents into <span class="html-italic">dq</span> system; (<b>c</b>) circle diagram.</p> Full article ">Figure 23 Cont.
<p>Measurement for normal operation: (<b>a</b>) stator currents; (<b>b</b>) transformation of measured <span class="html-italic">abcde</span> currents into <span class="html-italic">dq</span> system; (<b>c</b>) circle diagram.</p> Full article ">Figure 24
<p>Measurement for one-phase fault: (<b>a</b>) stator currents; (<b>b</b>) transformation of measured <span class="html-italic">abcde</span> currents into <span class="html-italic">dq</span> system; (<b>c</b>) circle diagram.</p> Full article ">Figure 25
<p>Measurement for editing of the control to nonsymmetrical currents: (<b>a</b>) stator currents; (<b>b</b>) transformation of measured <span class="html-italic">abcde</span> currents into <span class="html-italic">dq</span> system; (<b>c</b>) circle diagram.</p> Full article ">Figure 26
<p>Measurement for the editing of the control to symmetrical currents: (<b>a</b>) stator currents; (<b>b</b>) transformation of measured <span class="html-italic">abcde</span> currents into <span class="html-italic">dq</span> system; (<b>c</b>) circle diagram.</p> Full article ">Figure 27
<p>Measuring station from the measurement of a five-phase induction motor.</p> Full article ">
16 pages, 37298 KiB  
Article
Optimal Assistance Timing to Induce Voluntary Dorsiflexion Movements: A Preliminary Study in Healthy Participants
by Jing-Chen Hong, Kazuhiro Yasuda, Hiroki Ohashi and Hiroyasu Iwata
Appl. Sci. 2022, 12(4), 2248; https://doi.org/10.3390/app12042248 - 21 Feb 2022
Cited by 2 | Viewed by 2415
Abstract
Swing-phase dorsiflexion assistance with robotic ankle–foot orthosis could improve toe clearance and limb shortening such that compensatory movements are suppressed. However, facilitating voluntary effort under assistance remains a challenge. In our previous study, we examined assistance effects of swing-phase dorsiflexion with different delay [...] Read more.
Swing-phase dorsiflexion assistance with robotic ankle–foot orthosis could improve toe clearance and limb shortening such that compensatory movements are suppressed. However, facilitating voluntary effort under assistance remains a challenge. In our previous study, we examined assistance effects of swing-phase dorsiflexion with different delay times after toe-off on a dorsiflexion-restricted gait with a high-dorsiflexion assistive system. Results showed that later dorsiflexion assistance could lead to an increase in the tibialis anterior’s surface electromyography but could also deteriorate compensatory movement. Thus, we concluded that there is a suitable assistance timing to simultaneously achieve voluntary effort and optimal gait. In the present research, we derived a method to identify a suitable dorsiflexion assistance delay time via a multiple linear regression analysis on ankle data of stroke patients with a pathological gait with insufficient dorsiflexion. With the identification method, an experiment was conducted on six healthy participants with restricted dorsiflexion. Results showed that the identified assistance timing improved the amplitude of the tibialis anterior’s surface electromyography while also suppressing limb shortening during circumduction and hip hiking. Although a practical study of stroke survivors is required, observations from this research indicate the potential to successfully induce voluntary efforts with the identified dorsiflexion assistance timing. Full article
(This article belongs to the Special Issue Assistive Technology: Biomechanics in Rehabilitation Engineering)
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<p>The high-dorsiflexion assistive system: (<b>a</b>) Photograph of the system; (<b>b</b>) system configuration.</p> Full article ">Figure 2
<p>(<b>a</b>) Control diagram; (<b>b</b>) system control in a gait cycle.</p> Full article ">Figure 3
<p>Assumed figure of ankle angle data for a stroke survivor with insufficient swing-phase dorsiflexion.</p> Full article ">Figure 4
<p>Ankle angle with assumed ideal assistance timing and explanatory variables.</p> Full article ">Figure 5
<p>The dorsiflexion-restricted orthosis.</p> Full article ">Figure 6
<p>(<b>a</b>) A photograph of markers placed on a participant; (<b>b</b>) the marker set in this research.</p> Full article ">Figure 7
<p>Evaluation indices indicating extent of circumduction, hip hiking, and limb shortening.</p> Full article ">Figure 8
<p>sEMG amplitude results.</p> Full article ">Figure 9
<p>Swing width results.</p> Full article ">Figure 10
<p>Hip hike results.</p> Full article ">Figure 11
<p>Limb shortening results.</p> Full article ">Figure 12
<p>Ankle dorsiflexion angle in the swing phase.</p> Full article ">Figure 13
<p>Indication of identified assistance timing of the participants.</p> Full article ">Figure 14
<p>Results of knee flexion angle in swing phase for Participants B and E.</p> Full article ">
27 pages, 97700 KiB  
Article
Geochemical Association Rules of Elements Mined Using Clustered Events of Spatial Autocorrelation: A Case Study in the Chahanwusu River Area, Qinghai Province, China
by Baoyi Zhang, Zhengwen Jiang, Yiru Chen, Nanwei Cheng, Umair Khan and Jiqiu Deng
Appl. Sci. 2022, 12(4), 2247; https://doi.org/10.3390/app12042247 - 21 Feb 2022
Cited by 5 | Viewed by 2246
Abstract
The spatial distribution of elements can be regarded as a numerical field of concentration values with a continuous spatial coverage. An active area of research is to discover geologically meaningful relationships among elements from their spatial distribution. To solve this problem, we proposed [...] Read more.
The spatial distribution of elements can be regarded as a numerical field of concentration values with a continuous spatial coverage. An active area of research is to discover geologically meaningful relationships among elements from their spatial distribution. To solve this problem, we proposed an association rule mining method based on clustered events of spatial autocorrelation and applied it to the polymetallic deposits of the Chahanwusu River area, Qinghai Province, China. The elemental data for stream sediments were first clustered into HH (high–high), LL (low–low), HL (high–low), and LH (low–high) groups by using local Moran’s I clustering map (LMIC). Then, the Apriori algorithm was used to mine the association rules among different elements in these clusters. More than 86% of the mined rule points are located within 1000 m of faults and near known ore occurrences and occur in the upper reaches of the stream and catchment areas. In addition, we found that the Middle Triassic granodiorite is enriched in sulfophile elements, e.g., Zn, Ag, and Cd, and the Early Permian granite quartz diorite (P1γδο) coexists with Cu and associated elements. Therefore, the proposed algorithm is an effective method for mining coexistence patterns of elements and provides an insight into their enrichment mechanisms. Full article
(This article belongs to the Topic Data Science and Knowledge Discovery)
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<p>Geological map of the study area, modified from [<a href="#B43-applsci-12-02247" class="html-bibr">43</a>].</p> Full article ">Figure 2
<p>Map of stream sediment geochemical sampling points.</p> Full article ">Figure 3
<p>Log-frequency distribution histogram of the 15 elements in the study area: (<b>a</b>) Au, (<b>b</b>) Sn, (<b>c</b>) Ag, (<b>d</b>) As, (<b>e</b>) Sb, (<b>f</b>) Bi, (<b>g</b>) Co, (<b>h</b>) Cu, (<b>i</b>) La, (<b>j</b>) Pb, (<b>k</b>) Zn, (<b>l</b>) W, (<b>m</b>) Mo, (<b>n</b>) Nb, and (<b>o</b>) Cd.</p> Full article ">Figure 4
<p>Average concentrations of main mineralization elements in bedrock, e.g., (<b>a</b>) the Baishahe Formation, (<b>b</b>) the Elashan Formation, (<b>c</b>) monzogranite, (<b>d</b>) alkali feldspar granite, (<b>e</b>) monzogranite porphyry, (<b>f</b>) granodiorite, (<b>g</b>) quartz granodiorite, and (<b>h</b>) quartz diorite and their corresponding overlaying stream sediments, modified from [<a href="#B43-applsci-12-02247" class="html-bibr">43</a>].</p> Full article ">Figure 5
<p>Algorithm for generating frequent itemsets.</p> Full article ">Figure 6
<p>Algorithm for extracting strong association rules based on frequent itemsets.</p> Full article ">Figure 7
<p>Voronoi diagrams of local Moran’s I indicators for major elements.</p> Full article ">Figure 8
<p>LISA significance map of local Moran’s I indicators for major elements.</p> Full article ">Figure 9
<p>Clustering map of local Moran’s I indicators for major elements.</p> Full article ">Figure 10
<p>Clustering map of bivariate local Moran’s I with mainly positive cross correlation.</p> Full article ">Figure 11
<p>Clustering map of bivariate local Moran’s I with mainly negative cross correlation.</p> Full article ">Figure 12
<p>(<b>a</b>) Association rule mining result, {Cu (HH)} ⇒ {Co (HH)}, and (<b>b</b>) bivariate spatial cross-correlation indicator, <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi mathvariant="normal">CuCo</mi> </mrow> </msub> </mrow> </semantics></math>, of Cu and Co.</p> Full article ">Figure 13
<p>(<b>a</b>) Association rule mining result, {As (HH)} ⇒ {Sb (HH)}, and (<b>b</b>) bivariate spatial cross-correlation indicator, <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi mathvariant="normal">AsSb</mi> </mrow> </msub> </mrow> </semantics></math>, of As and Sb.</p> Full article ">Figure 14
<p>Euclidean distance field of faults.</p> Full article ">Figure 15
<p>Number of mined rule points that are close to faults.</p> Full article ">Figure 16
<p>Rule {Cu (HH)} ⇒ {Co (HH)} points within 500 m and 1000 m of faults.</p> Full article ">Figure 17
<p>Rule {Zn (HH), Sb (HH)} ⇒ {Cd (HH)} points within 500 m and 1000 m of faults.</p> Full article ">Figure 18
<p>Rule {Cu (HH)} ⇒ {Co (HH)} points overlayed with streams and catchment areas.</p> Full article ">Figure 19
<p>Rule {Zn (HH), Sb (HH)} ⇒ {Cd (HH)} points overlayed with streams and catchment areas.</p> Full article ">Figure 20
<p>Total number of points and density of each mined rule in the main lithostrata.</p> Full article ">Figure 21
<p>Rule {As (HH)} ⇒ {Sb (HH)} overlayed with the main lithostrata.</p> Full article ">Figure 22
<p>Rule {Zn (HH), Ag (HH)} ⇒ {Cd (HH)} overlayed with the main lithostrata.</p> Full article ">Figure 23
<p>Rule {Cu (HH)} ⇒ {Co (HH)} overlayed with the main lithostrata.</p> Full article ">
17 pages, 2638 KiB  
Article
Comparing Polynomials and Neural Network to Modelling Injection Dosages in Modern CI Engines
by Tomasz Osipowicz, Karol Franciszek Abramek and Łukasz Mozga
Appl. Sci. 2022, 12(4), 2246; https://doi.org/10.3390/app12042246 - 21 Feb 2022
Cited by 1 | Viewed by 1571
Abstract
The article discusses the possibility of using computational methods for modelling the size of the injection doses. Polynomial and artificial intelligence methods were used for prediction. The aim of the research was to analyze whether it is possible to model the operating parameters [...] Read more.
The article discusses the possibility of using computational methods for modelling the size of the injection doses. Polynomial and artificial intelligence methods were used for prediction. The aim of the research was to analyze whether it is possible to model the operating parameters of the fuel injector without knowing its internal dimensions and tribological associations. The black box method was used to make the model. This method is based on the analysis of input and output parameters and their correlation. The paper proposes a mathematical model determined on the basis of a polynomial and a neural network based on input and output parameters. The above models make it possible to predict the amount of fuel injection doses on the basis of their operating parameters. Modelling was performed in the Matlab environment. Calculating methods could support the diagnosis processes of fuel injectors. Fuel injection characteristic is non-linear. Study shows that it is possible to predict injection characteristic with high matching using polynomial and neural network. That way accelerates fuel injector work parameters research process. Fuel injector test basis on known its work areas. Mathematical modelling can calculate all injection area using few parameters. To modelling fuel injection dosages by neural network have been used back propagation and Levenberg—Marquardt algorithms. Full article
(This article belongs to the Special Issue Modeling and Simulation with Artificial Neural Network)
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<p>Black box calculating model.</p> Full article ">Figure 2
<p>Structure of the neuron.</p> Full article ">Figure 3
<p>A diagram of a neural network that allowed to create a brain that determines the dose of injectors depending on pressure and time.</p> Full article ">Figure 4
<p>Characteristics of injection doses depending on pressure and injection time. <span class="html-italic">X</span> axis—pressure [MPa], <span class="html-italic">Y</span> axis—injection time [µs], <span class="html-italic">Z</span> axis—injection dose [mm<sup>3</sup>/H].</p> Full article ">Figure 5
<p>Fuel dosages graph of a damaged injector (anomaly in the range of control times 525–625 μs at a system pressure 40–60 MPa) with an incorrect dosing area.</p> Full article ">Figure 6
<p>Fuel dosages graph of the tested injector.</p> Full article ">Figure 7
<p>Fuel dosages graph of the tested injector proposed by the authors—parameters measured on the STPiW 3 test bench.</p> Full article ">Figure 8
<p>Fuel dosages graph of the tested injector modelled with the use of a polynomial, proposed by the Authors.</p> Full article ">Figure 9
<p>Comparison of differences between measured and calculated by polynomial operational parameters of the tested injector.</p> Full article ">Figure 10
<p>Comparison of differences between the operating parameters measured and presented by the polynomial of the tested injector.</p> Full article ">Figure 11
<p>Fuel dosages graph of the tested injector modelled with the use of a neural network, proposed by the Authors.</p> Full article ">Figure 12
<p>Comparison of differences between the operating parameters measured and presented by the neural network of the tested injector.</p> Full article ">Figure 13
<p>Comparison of differences between the operating parameters measured and presented by the neural network of the tested injector.</p> Full article ">Figure 14
<p>Characteristics of the mean error between the output data from the test bench and the obtained from the neural network.</p> Full article ">Figure 15
<p>Injection dose size characteristics obtained from measurements on the test bench.</p> Full article ">Figure 16
<p>Injection dose size characteristics obtained as a result of the implementation of a neural network.</p> Full article ">Figure 17
<p>Piezoelectric crystals stack.</p> Full article ">
26 pages, 4898 KiB  
Article
The Behavior of Hybrid Fiber-Reinforced Concrete Elements: A New Stress-Strain Model Using an Evolutionary Approach
by Ali A. Abdulhameed, Alaa Hussein Al-Zuhairi, Salah R. Al Zaidee, Ammar N. Hanoon, Ahmed W. Al Zand, Mahir M. Hason and Haider A. Abdulhameed
Appl. Sci. 2022, 12(4), 2245; https://doi.org/10.3390/app12042245 - 21 Feb 2022
Cited by 27 | Viewed by 4679
Abstract
Several stress-strain models were used to predict the strengths of steel fiber reinforced concrete, which are distinctive of the material. However, insufficient research has been done on the influence of hybrid fiber combinations (comprising two or more distinct fibers) on the characteristics of [...] Read more.
Several stress-strain models were used to predict the strengths of steel fiber reinforced concrete, which are distinctive of the material. However, insufficient research has been done on the influence of hybrid fiber combinations (comprising two or more distinct fibers) on the characteristics of concrete. For this reason, the researchers conducted an experimental program to determine the stress-strain relationship of 30 concrete samples reinforced with two distinct fibers (a hybrid of polyvinyl alcohol and steel fibers), with compressive strengths ranging from 40 to 120 MPa. A total of 80% of the experimental results were used to develop a new empirical stress-strain model, which was accomplished through the application of the particle swarm optimization (PSO) technique. It was discovered in this investigation that the new stress-strain model predictions are consistent with the remaining 20% of the experimental stress-strain curves obtained. Case studies of hybrid–fiber–reinforced concrete constructions were investigated in order to better understand the behavior of such elements. The data revealed that the proposed model has the highest absolute relative error (ARE) frequencies (ARE 10%) and the lowest absolute relative error (ARE > 15%) frequencies (ARE > 15%). Full article
(This article belongs to the Special Issue Structural Application of Advanced Concrete Materials)
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<p>A diagrammatic illustration of the research approach.</p> Full article ">Figure 2
<p>Respective features of (<b>a</b>) Steel fiber and (<b>b</b>) polyvinyl alcohol fiber.</p> Full article ">Figure 3
<p>Concrete cubes samples.</p> Full article ">Figure 4
<p>Uniaxial compression tests setup.</p> Full article ">Figure 5
<p>The main concept of using PSO.</p> Full article ">Figure 6
<p>Flowchart of the proposed algorithm.</p> Full article ">Figure 7
<p>Compressive strength.</p> Full article ">Figure 8
<p>Maximum strain.</p> Full article ">Figure 9
<p>Stress-strain curves of cubic specimens with various fiber content percentages.</p> Full article ">Figure 9 Cont.
<p>Stress-strain curves of cubic specimens with various fiber content percentages.</p> Full article ">Figure 10
<p>Convergence of swarms of various sizes.</p> Full article ">Figure 11
<p>Using the proposed model, a comparison of predicted and experimental stress capacity.</p> Full article ">Figure 12
<p>Taylor diagrams of predicted versus observed standardized stress capacity using the PSO model (for 80% of the data).</p> Full article ">Figure 13
<p>The proposed model’s (ARE) distribution.</p> Full article ">Figure 14
<p>Taylor diagrams of predicted versus observed standardized stress capacity using the PSO model (for 20% of the data).</p> Full article ">Figure 15
<p>Typical boundary conditions of the suggested <span class="html-italic">3D FE</span> models. (<b>a</b>) Cube model. (<b>b</b>) <span class="html-italic">RC</span> column model.</p> Full article ">Figure 16
<p>The <span class="html-italic">CDP</span> of concrete FE model. (<b>a</b>) Under compression stresses. (<b>b</b>) under tension stresses.</p> Full article ">Figure 17
<p>Compression of the cubes ultimate compression strengths.</p> Full article ">Figure 18
<p>The failure mode of the <span class="html-italic">FE</span> cube model (Mix-17).</p> Full article ">Figure 19
<p>Cross-sectional details of RC columns specimens.</p> Full article ">Figure 20
<p>Compression of the ultimate axial load capacity of HFRC columns.</p> Full article ">Figure 21
<p>The failure mode of the FE HFRC model HC1.0–0.9.</p> Full article ">
13 pages, 4248 KiB  
Review
Some Practical Acoustic Design and Typical Control Strategies for Multichannel Active Noise Control
by Yijing Chu, Ming Wu, Hongling Sun, Jun Yang and Mingyang Chen
Appl. Sci. 2022, 12(4), 2244; https://doi.org/10.3390/app12042244 - 21 Feb 2022
Cited by 8 | Viewed by 2536
Abstract
Active noise control (ANC) systems usually involve a large number of loudspeakers and error microphones in order to achieve noise reduction over an extended region of space. Although fundamentals of ANC theory and principles of ANC methods have been well-established over the past [...] Read more.
Active noise control (ANC) systems usually involve a large number of loudspeakers and error microphones in order to achieve noise reduction over an extended region of space. Although fundamentals of ANC theory and principles of ANC methods have been well-established over the past 40 years, applications of this technology are facing new challenges. A larger quiet zone with better noise reduction performance is always desirable in a variety of real-life scenarios. This paper presents several important factors that affect the performance of multichannel ANC systems in some popular applications such as windows with natural ventilation and quiet-zone around heads. The factors affecting acoustic design include the reflection of a baffle plate, arrangement of error sensors in open areas, and so on. In addition, different control strategies are compared and analyzed, including centralized, decentralized, and distributed strategies. All these strategies are discussed from the signal processing side, which should be considered after a proper acoustic design. One of the important aims of this paper is to provide practical guidance for acoustic design and discuss several typical control strategies for multichannel ANC systems. Full article
(This article belongs to the Special Issue Application of Active Noise and Vibration Control)
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<p>Experimental setup in Tao’s 2017 paper [<a href="#B13-applsci-12-02244" class="html-bibr">13</a>]: (<b>a</b>) a 3-channel ANC system setup with a wooden plate as the reflecting surface; (<b>b</b>) a 3-channel ANC system setup in free field; (<b>c</b>) a configuration of a 2-channel ANC system; (<b>d</b>) a configuration of a 3-channel ANC system.</p> Full article ">Figure 2
<p>Optimal noise reduction with and without the wooden plate (<b>a</b>) measured results (<b>b</b>) simulation results. Figures are cited from Tao’s 2017 paper [<a href="#B13-applsci-12-02244" class="html-bibr">13</a>].</p> Full article ">Figure 3
<p>(<b>a</b>) Experimental setup; (<b>b</b>) experimental result of the control performance with or without a sphere. Figures are cited from Zou’s 2008 paper [<a href="#B17-applsci-12-02244" class="html-bibr">17</a>].</p> Full article ">Figure 4
<p>Control performance (<b>a</b>) with respect to a<sub>e</sub>, <span class="html-italic">f</span> = 250 Hz, a<sub>c</sub> = 1.22 m; (<b>b</b>) with respect to a<sub>c</sub>–a<sub>e</sub>, <span class="html-italic">f</span> = 250 Hz, a<sub>e</sub> = 0.38 m. Figures are cited from Zou’s 2007 paper [<a href="#B18-applsci-12-02244" class="html-bibr">18</a>].</p> Full article ">Figure 5
<p>(Color online) Photos of the experiment setup: (<b>a</b>) a panoramic view of the anechoic chamber, (<b>b</b>) evenly distributed error microphones, (<b>c</b>) single layer error microphones at the edge, and (<b>d</b>) double-layer error microphones at the edge. Figures are cited from Wang’s 2019 paper [<a href="#B24-applsci-12-02244" class="html-bibr">24</a>].</p> Full article ">Figure 6
<p>Cost functions and block diagrams of ANC systems with different control strategies: (<b>a</b>) centralized; (<b>b</b>) decentralized; and (<b>c</b>) distributed.</p> Full article ">Figure 7
<p>Convergence curves of the three methods with weighting factors of zero at (<b>a</b>) 130 Hz and (<b>b</b>) 200 Hz, where the step-sizes <span class="html-italic">μ</span><sub>1</sub> = 1 × 10<sup>−7</sup> and <span class="html-italic">μ</span><sub>2</sub> = 1 × 10<sup>−6</sup>. Figures are cited from Zhang’s 2019 paper [<a href="#B44-applsci-12-02244" class="html-bibr">44</a>].</p> Full article ">Figure 8
<p>The experimental facility of a panel–cavity system: aluminum panel with error sensors and nine collocated sensor–actuator pairs. Figure is cited from Yu’s 2015 paper [<a href="#B43-applsci-12-02244" class="html-bibr">43</a>].</p> Full article ">Figure 9
<p>The kinetic energy of the plate with the excitation of the loudspeaker in the cavity between 1 and 1 k Hz without control (dashed line), and when the two control loops (<b>a</b>), nine control loops (<b>b</b>) are implemented (solid line). Figures are cited from Yu’s 2015 paper [<a href="#B43-applsci-12-02244" class="html-bibr">43</a>].</p> Full article ">Figure 10
<p>Distributed network of node <span class="html-italic">k</span>: (<b>a</b>) an incremental structure where nodes update along a cyclic loop, and (<b>b</b>) a diffusion structure where nodes communicate within a neighborhood <math display="inline"><semantics> <mrow> <msub> <mi>N</mi> <mi>k</mi> </msub> </mrow> </semantics></math>. Node <span class="html-italic">k</span> collects the residue and reference data set {<span class="html-italic">e<sub>k</sub></span>(<span class="html-italic">n</span>), <b><span class="html-italic">x</span></b><span class="html-italic"><sub>k</sub></span>(<span class="html-italic">n</span>)} at time index <span class="html-italic">n</span>.</p> Full article ">Figure 11
<p>Learning curves of the norm of the estimate deviation to the Wiener solution v<sup>0</sup> and the deviation to the theoretical steady-state solution v<sup>inf</sup> under different settings. The number of node <span class="html-italic">K</span> = 10. <span class="html-italic">μ</span> and <span class="html-italic">r</span> are, respectively, the step-size and the radius that controls the difference between the primary paths. Figure is cited from Chu’s 2020 paper [<a href="#B48-applsci-12-02244" class="html-bibr">48</a>].</p> Full article ">Figure 12
<p>Learning curves of averaged global EMSE under different settings. <span class="html-italic">K</span> = 10. Figure is cited from Chu’s 2020 paper [<a href="#B48-applsci-12-02244" class="html-bibr">48</a>].</p> Full article ">Figure 13
<p>Global EMSE learning curves with different control strategies for the ANC controller: <span class="html-italic">µ</span> = 0.001, <span class="html-italic">r</span> = 0.01, <span class="html-italic">K</span> = 10 and the filter length <span class="html-italic">L</span> = 160. Figure is cited from Chu’s 2020 paper [<a href="#B48-applsci-12-02244" class="html-bibr">48</a>].</p> Full article ">
10 pages, 1116 KiB  
Article
Investigation of the Possibilities for Removal of Phenolic Toxic Compounds from Water by Nanoporous Carbon from Polymer By-Products
by Ivanka Stoycheva, Boyko Tsyntsarski, Bilyana Petrova, Georgi Georgiev, Temenuzhka Budinova, Nartzislav Petrov, Barbara Trzebicka, Slawomira Pusz, Bogumila Kumanek and Urszula Szeluga
Appl. Sci. 2022, 12(4), 2243; https://doi.org/10.3390/app12042243 - 21 Feb 2022
Cited by 2 | Viewed by 1600
Abstract
Nanoporous carbon is synthesized on the base of phenol-formaldehyde resin and polyolefin wax, a by-product from industrial production of polyethylene at low pressure. The adsrption of phenol derivates from aqueous solutions on obtained carbon material was studied. The adsorption capacity of the carbon [...] Read more.
Nanoporous carbon is synthesized on the base of phenol-formaldehyde resin and polyolefin wax, a by-product from industrial production of polyethylene at low pressure. The adsrption of phenol derivates from aqueous solutions on obtained carbon material was studied. The adsorption capacity of the carbon is related to the surface area and composition of the synthesized material, as well as to the nature of the adsorbent. The obtained adsorbent is characterized by high surface area and porosity, and it demonstrates high adsorption capacity towards aromatic compounds. All studied phenolic compounds show high affinity towards carbon, confirming that the retention mechanism occurs via non-specific interactions between the electronic density of the adsorbent and molecules of aromatic pollutants. Electrostatic interactions may also appear depending on pH of the solution pH and charge distribution of the carbons; and these effects has a strong influence on the final performance of the carbon. Full article
(This article belongs to the Special Issue Urban Chemical Pollution on Water Quality and Degradation Ways)
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<p>XRD pattern of obtained activated carbon (accuracy 0.5%).</p> Full article ">Figure 2
<p>N<sub>2</sub> adsorption isotherm (<b>a</b>) and pore size distribution (<b>b</b>) of activated carbon at −196 °C.</p> Full article ">Figure 3
<p>IR spectrum of activated carbon.</p> Full article ">Figure 4
<p>Equilibrium adsorption isotherms of pentachlorophenol, m-aminophenol and p-nitrophenol on carbon.</p> Full article ">Figure 5
<p>Effect of pH on penthachlorophenol removal. Conditions: time of treatment—60 min; activated carbon amount—0.1 g per 50 mL solution; penthachlorophenol concentration—0.03 g/L.</p> Full article ">
14 pages, 1359 KiB  
Article
Auditory Property-Based Features and Artificial Neural Network Classifiers for the Automatic Detection of Low-Intensity Snoring/Breathing Episodes
by Kenji Hamabe, Takahiro Emoto, Osamu Jinnouchi, Naoki Toda and Ikuji Kawata
Appl. Sci. 2022, 12(4), 2242; https://doi.org/10.3390/app12042242 - 21 Feb 2022
Viewed by 1761
Abstract
The definitive diagnosis of obstructive sleep apnea syndrome (OSAS) is made using an overnight polysomnography (PSG) test. This test requires that a patient wears multiple measurement sensors during an overnight hospitalization. However, this setup imposes physical constraints and a heavy burden on the [...] Read more.
The definitive diagnosis of obstructive sleep apnea syndrome (OSAS) is made using an overnight polysomnography (PSG) test. This test requires that a patient wears multiple measurement sensors during an overnight hospitalization. However, this setup imposes physical constraints and a heavy burden on the patient. Recent studies have reported on another technique for conducting OSAS screening based on snoring/breathing episodes (SBEs) extracted from recorded data acquired by a noncontact microphone. However, SBEs have a high dynamic range and are barely audible at intensities >90 dB. A method is needed to detect SBEs even in low-signal-to-noise-ratio (SNR) environments. Therefore, we developed a method for the automatic detection of low-intensity SBEs using an artificial neural network (ANN). However, when considering its practical use, this method required further improvement in terms of detection accuracy and speed. To accomplish this, we propose in this study a new method to detect low SBEs based on neural activity pattern (NAP)-based cepstral coefficients (NAPCC) and ANN classifiers. Comparison results of the leave-one-out cross-validation demonstrated that our proposed method is superior to previous methods for the classification of SBEs and non-SBEs, even in low-SNR conditions (accuracy: 85.99 ± 5.69% vs. 75.64 ± 18.8%). Full article
(This article belongs to the Topic Artificial Intelligence in Healthcare)
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<p>Flow chart of feature extraction based on the adopted auditory model.</p> Full article ">Figure 2
<p>Flow chart of the automatic snoring/breathing event (SBE) detection system proposed in this study.</p> Full article ">Figure 3
<p>Relationship between mean F1 score and number of dimensions of neural activity pattern-based cepstral coefficients (NAPCC) when sigmoid or mean normalizations were used: (<b>a</b>) Exp-1 and (<b>b</b>) Exp-2 results.</p> Full article ">Figure 4
<p>SBE detection results based on the proposed method: (<b>a</b>) 20 s of recorded data, (<b>b</b>) NAP output obtained by analyzing the recorded data, (<b>c</b>) trained MLP-ANN output results, (<b>d</b>) results of labeling by three annotators (1 for SBE sections, 0 for non-SBE sections).</p> Full article ">Figure 5
<p>F1 score of the subjects obtained via the proposed or our previous method. (<b>a</b>) Exp-1 and (<b>b</b>) Exp-2 cases.</p> Full article ">
19 pages, 3147 KiB  
Article
Toward ZEB: A Mathematical Programing-, Simulation-, and AHP-Based Comprehensive Framework for Building Retrofitting
by Sobhi Mejjaouli
Appl. Sci. 2022, 12(4), 2241; https://doi.org/10.3390/app12042241 - 21 Feb 2022
Cited by 3 | Viewed by 2071
Abstract
Because of their significant energy consumption and its economic and environmental impacts, existing buildings offer decision makers opportunities and challenges at the same time. In fact, there is a worldwide effort to improve the energy performance of the existing buildings as well as [...] Read more.
Because of their significant energy consumption and its economic and environmental impacts, existing buildings offer decision makers opportunities and challenges at the same time. In fact, there is a worldwide effort to improve the energy performance of the existing buildings as well as the new ones to achieve zero-energy buildings. In this paper, a framework for retrofitting existing buildings to help achieve the goal of zero-energy buildings is presented. The framework details the different steps required to develop and implement a successful retrofitting plan for both residential and commercial buildings. This includes data collection, life cycle cost calculation, building simulation, and multi-criteria decision making using the analytic hierarchy process (AHP). At the end of the paper, a case study is detailed to show the different steps necessary to select a successful retrofitting plan that reflects the decision maker’s objectives. The case study resulted in a retrofitting plan that offers a yearly energy savings of 30% and a payback period of 2.2 years. Full article
(This article belongs to the Special Issue Zero Energy Buildings: From Building Energy Simulation to Indoor Environment Monitoring)
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<p>Three-dimensional representation of the residential building.</p> Full article ">Figure 2
<p>Energy consumption (in Kwh) before retrofitting.</p> Full article ">Figure 3
<p>Energy consumption (in Kwh) after retrofitting (Plan 1).</p> Full article ">Figure 4
<p>The effect of budget (in SR) on energy savings.</p> Full article ">Figure 5
<p>The effect of budget (in SR) on ROI.</p> Full article ">Figure 6
<p>The effect of budget (in SR) on the payback period (in years).</p> Full article ">Figure A1
<p></p> Full article ">
14 pages, 1406 KiB  
Article
Inhibition of Peroxidation Potential and Protein Oxidative Damage by Metal Mangiferin Complexes
by Alberto J. Nuñez-Selles, Lauro Nuevas-Paz and Gregorio Martínez-Sánchez
Appl. Sci. 2022, 12(4), 2240; https://doi.org/10.3390/app12042240 - 21 Feb 2022
Cited by 1 | Viewed by 1783
Abstract
Background: Metal coordination complexes of polyphenolic compounds have been claimed to have better antioxidant and protection against protein oxidative damage effects than the isolated ligands. Whereas flavonoids have been extensively studied, xanthones such as mangiferin are lacking extensive research. Methods: Cu (II), Zn [...] Read more.
Background: Metal coordination complexes of polyphenolic compounds have been claimed to have better antioxidant and protection against protein oxidative damage effects than the isolated ligands. Whereas flavonoids have been extensively studied, xanthones such as mangiferin are lacking extensive research. Methods: Cu (II), Zn (II), and Se (IV) mangiferin complexes were synthesized with different stoichiometric ratios. Products were isolated by preparative chromatography and subjected to spectral analysis by FT-IR, HPLC-DAD, and HPLC-ESI-MS. The inhibition effects on peroxidation potential and protein oxidative damage were determined for all the metal–MF complexes. Results: Eight metal–MF complexes were isolated. Cu (II)–MF complexes did not improve MF antioxidant/protective effects; Zn (II) complexes (stoichiometric ratio 1:2) antioxidant/protective effects had no significant differences to MF; Zn (II)– and Se (IV)–MF complexes (stoichiometric ratio 1:3) showed the best inhibition effects on peroxidation potential (49.06% and 32.08%, respectively), and on the protection against protein oxidative damage (14.49% and 20.81%, respectively). Conclusions: The antioxidant/protective effects of Se (IV)– and Zn (II)–MF coordination complexes were significantly improved as compared to isolated MF, when the reaction between the metal salt and MF was performed with a stoichiometric ratio 1:3. Full article
(This article belongs to the Special Issue Protective Effects of Edible and Medicinal Plant Extracts against Oxidative Stress)
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<p>(<b>A</b>). Isotopic peak cluster of Cu (II)–MF complex [M − H]<sup>−</sup> ion, Peak 2. (<b>B</b>). Isotopic peak cluster of Zn (II)–MF complex [M − H]<sup>−</sup> ion, Peak 3. (<b>C</b>). Isotopic peak cluster of Se (IV)–MF complex [M − H]<sup>−</sup> ion, Peak 4.</p> Full article ">Figure 2
<p>FT-IR spectra of mangiferin and selenium (IV)-mangiferin complexes in the region between 800 and 1800 cm<sup>−1</sup>. The appearance of bands at 817.6 cm<sup>−1</sup> for Peak 3, ratio 1:2 (<b>A</b>) and 817.8 cm<sup>−1</sup> for Peak 4, ratio 1:3 (<b>B</b>) indicated the formation of metal–oxygen bonds of Se (IV)-mangiferin complexes. The same occurred for all metal–mangiferin complexes described herein.</p> Full article ">Figure 3
<p>Determination of the inhibition of the peroxidation potential and the protein degradation by metal–mangiferin complexes. (<b>A</b>). Percentage of inhibition of lipid peroxidation; (<b>B</b>). Percentage of inhibition of protein degradation. Inhibition values as percentages against the control sample (for mangiferin) or mangiferin (complexes). Legend: Cu (1:2) P2, copper complex 1:2 Chromatographic peak 2; Cu (1:2) P3, copper complex 1:2 Chromatographic peak 3; Zn (1:2) P2, zinc complex 1:2 Chromatographic peak 2; Zn (1:2) P3 zinc complex 1:2 Chromatographic peak 3; Zn (1:3) P4 zinc complex 1:3 Chromatographic peak 4; Se (1:2) P3, selenium complex 1:2 Chromatographic peak 3; Se (1:3) P4, selenium complex 1:3 Chromatographic peak 4. Different letters mean significant variation (<span class="html-italic">p</span>&gt;0.05).</p> Full article ">
19 pages, 4456 KiB  
Article
Mesenchymal Stromal Cells (MSCs) Isolated from Various Tissues of the Human Arthritic Knee Joint Possess Similar Multipotent Differentiation Potential
by Mike Wagenbrenner, Konrad Poker, Tizian Heinz, Marietta Herrmann, Konstantin Horas, Regina Ebert, Susanne Mayer-Wagner, Boris M. Holzapfel, Maximilian Rudert, Andre F. Steinert and Manuel Weißenberger
Appl. Sci. 2022, 12(4), 2239; https://doi.org/10.3390/app12042239 - 21 Feb 2022
Viewed by 1798
Abstract
(1) Background: The mesenchymal stromal cells (MSCs) of different tissue origins are applied in cell-based chondrogenic regeneration. However, there is a lack of comparability determining the most suitable cell source for the tissue engineering (TE) of cartilage. The purpose of this study was [...] Read more.
(1) Background: The mesenchymal stromal cells (MSCs) of different tissue origins are applied in cell-based chondrogenic regeneration. However, there is a lack of comparability determining the most suitable cell source for the tissue engineering (TE) of cartilage. The purpose of this study was to compare the in vitro chondrogenic potential of MSC-like cells from different tissue sources (bone marrow, meniscus, anterior cruciate ligament, synovial membrane, and the infrapatellar fat pad removed during total knee arthroplasty (TKA)) and define which cell source is best suited for cartilage regeneration. (2) Methods: MSC-like cells were isolated from five donors and expanded using adherent monolayer cultures. Differentiation was induced by culture media containing specific growth factors. Transforming growth factor (TGF)-ß1 was used as the growth factor for chondrogenic differentiation. Osteogenesis and adipogenesis were induced in monolayer cultures for 27 days, while pellet cell cultures were used for chondrogenesis for 21 days. Control cultures were maintained under the same conditions. After, the differentiation period samples were analyzed, using histological and immunohistochemical staining, as well as molecularbiological analysis by RT-PCR, to assess the expression of specific marker genes. (3) Results: Plastic-adherent growth and in vitro trilineage differentiation capacity of all isolated cells were proven. Flow cytometry revealed the clear co-expression of surface markers CD44, CD73, CD90, and CD105 on all isolated cells. Adipogenesis was validated through the formation of lipid droplets, while osteogenesis was proven by the formation of calcium deposits within differentiated cell cultures. The formation of proteoglycans was observed during chondrogenesis in pellet cultures, with immunohistochemical staining revealing an increased relative gene expression of collagen type II. RT-PCR proved an elevated expression of specific marker genes after successful differentiation, with no significant differences regarding different cell source of native tissue. (4) Conclusions: Irrespective of the cell source of native tissue, all MSC-like cells showed multipotent differentiation potential in vitro. The multipotent differentiation capacity did not differ significantly, and chondrogenic differentiation was proven in all pellet cultures. Therefore, cell suitability for cell-based cartilage therapies and tissue engineering is given for various tissue origins that are routinely removed during total knee arthroplasty (TKA). This study might provide essential information for the clinical tool of cell harvesting, leading to more flexibility in cell availability. Full article
(This article belongs to the Special Issue Osteoarthritis and Cartilage Regeneration: From Pathophysiology to Novel Therapeutic Approaches)
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<p>Cumulative population doublings of cells derived from all native tissues, between isolation and after primary passage, pictured as median ± standard deviation (error bars). Cells derived from bone marrow (BM), hyaline cartilage, the meniscus, the anterior cruciate ligament (ACL), the synovial membrane (SM), and the infrapatellar fat pad (IPF) were counted, following primary isolation from all six native tissues. After primary passage and before initiating the following experiments, cells were harvested and counted again. Cumulative population doubling (CPD) was calculated using the formula CPD = log10/(N/N0) × 3.33. N was the number of cells at the end of passage one, and N0 was the number of cells derived from primary isolation of native tissues. The median of CPD is pictured, respectively. Error bars picture the standard deviation.</p> Full article ">Figure 2
<p>Flow cytometry analysis of the expression of surface antigens on cells isolated from all six tissues of one single patient. Cells from bone marrow (<b>a</b>), hyaline cartilage (<b>b</b>), the meniscus (<b>c</b>), the anterior cruciate ligament (ACL) (<b>d</b>), the synovial membrane (SM) (<b>e</b>), and the infrapatellar fat pad (IPF) (<b>f</b>) were examined for the co-expression of surface antigens cluster of differentiation (CD)44, CD73 (CD44/CD73), CD90, and CD105 (CD90/CD105). The results were pictured using the FlowJo 10.5.3 software by FlowJo, LLC. While almost all cells (≥95%) were positive for the surface markers CD44, CD90, and CD105, the percentage of CD73+ cells ranged from about 13–99%, depending on the donor tissue.</p> Full article ">Figure 3
<p>Histological assay of adipogenesis in mesenchymal stromal cells after 27 days in adherent monolayer cell cultures. For inducing adipogenesis monolayer cultures containing cells from bone marrow, hyaline cartilage, the meniscus, the anterior cruciate ligament (ACL), the synovial membrane (SM), and the infrapatellar fat pad (IPF) were incubated with adipogenic differentiation medium for 27 days (d). Controls were maintained in cell culture medium under the same conditions. Both native, unstained tissue samples (<b>a</b>) and oil red O stainings (<b>b</b>) from control and differentiated samples were compared. Adipogenic assays were performed with all samples (five donors, six different MSC population each), and we show one representative donor of each staining. Representative samples were captured at low (100×; black bar = 200 μm) and high (200×; black bar = 150 μm) magnification.</p> Full article ">Figure 4
<p>Scattered dot plots picturing the changes in relative gene expression of specific marker genes as median ± upper and lower quartile and highest and lowest values (error bars), as measured by semiquantitative RT-PCR in mesenchymal progenitor cells at the end of the respective differentiation period. Cells derived from bone marrow, hyaline cartilage, the meniscus, the anterior cruciate ligament (ACL), the synovial membrane (SM), and the infrapatellar fat pad (IFP) were incubated in adipogenic, osteogenic (27 days (d)) and chondrogenic (21 d) differentiation medium. The median of the changes of the relative expression of the adipogenic (<b>a</b>) marker genes—lipoproteinlipase (encoded by LPL) and proliferator-activated receptor γ (encoded by PPARG2)—the osteogenic (<b>b</b>) marker genes—collagen type Ia2 (encoded by COL1A2), alkaline phosphatase (encoded by ALP), and osteocalcin (encoded by OC)—as well as the chondrogenic (<b>c</b>) marker genes—aggrecan (encoded by AGN), collagen type IIa1 (encoded by COL2A1), and sex-determining region Y-box 9 (encoded by SOX9)—are pictured, respectively. Box plots picture the upper and lower quartiles and error bars picture the respective highest and lowest values of changes in the relative expression of specific marker genes. Cell cultures treated with standard cell culture medium served as negative controls. Elongation factor 1α (encoded by EEF1A1) was used as the housekeeping gene and internal controls. The expression of respective marker genes in undifferentiated control cultures served as a baseline value, which differentiated cultures were compared against, and was pictured as a dashed line (value = 1). Differentiation assays were performed with all samples (five donors, six different MSC population each), and we show one representative donor of each staining.</p> Full article ">Figure 5
<p>Histological assay of osteogenesis in cells after 21 days in adherent monolayer cell cultures. Induced osteogenesis monolayer cultures, containing cells from bone marrow (BM), hyaline cartilage, the meniscus, the anterior cruciate ligament (ACL), the synovial membrane (SM), and the infrapatellar fat pad (IFP) were incubated with osteogenic differentiation medium for 27 days (d). Controls were maintained in cell culture medium under the same conditions. Both native, unstained tissue samples (<b>a</b>) and alizarin red S stainings (<b>b</b>) from control and differentiated samples were compared. Osteogenic assays were performed with all samples (five donors, six different MSC population each), and we show one representative donor of each staining. Representative samples were captured at low (100×; black bar = 200 μm) and high (200×; black bar = 150 μm) magnification.</p> Full article ">Figure 6
<p>Histological and immunohistochemical analysis of chondrogenesis in cell-pellets after 21 d of pellet culture. Induced chondrogenesis pellets, containing cells from bone marrow (BM), hyaline cartilage, the meniscus, the anterior cruciate ligament (ACL), the synovial membrane (SM) and the infrapatellar fat pad (IFP), were incubated with chondrogenic differentiation medium for 21 days (d). Controls were maintained in cell culture medium under the same conditions. After 21 d, alcian blue staining (<b>a</b>) was performed for the detection of proteoglycans. Immunohistochemical stainings of collagen type II (COL II) (<b>b</b>) and collagen type X (COL X) (<b>c</b>) were performed on pellet sections cells from BM (1), hyaline cartilage (2), the meniscus (3), the ACL (4), the SM (5), and the IPF (6) after incubation in chondrogenic differentiation medium for 21 d. Positive staining for COL II (b) and COL X (c) appeared brown. Chondrogenic assays were performed with all samples (five donors, six different MSC population each), and we show one representative donor of each staining. Representative samples were captured at low (50×; black bar = 300 μm) and high (200×; black bar = 300 μm) magnification.</p> Full article ">
17 pages, 6697 KiB  
Article
A New Methodology for Type Synthesis of Planar Linkages for Exoskeletons up to Five Angular Outputs
by Mahmoud Helal, Abdulaziz H. Alghtani, Jong Wan Hu and Hasan Eleashy
Appl. Sci. 2022, 12(4), 2238; https://doi.org/10.3390/app12042238 - 21 Feb 2022
Viewed by 2062
Abstract
Mechanical linkage systems are a very important issue for exoskeleton design to meet the required number of angular outputs. In this paper, a new methodology is developed for type synthesis of planar linkages to establish a complete set of one degree of freedom [...] Read more.
Mechanical linkage systems are a very important issue for exoskeleton design to meet the required number of angular outputs. In this paper, a new methodology is developed for type synthesis of planar linkages to establish a complete set of one degree of freedom (DOF) planar linkages with up to five angular outputs. Modified graphical representation is introduced for a four-bar mechanism as the initial angular output linkage. Then, a computerized procedure is presented to generate multiple angular outputs graphically by adding RRR dyads with parallel and series connections using Visual C++. A complete database of planar linkages with up to five angular outputs is successfully constructed. That helps designers to select the proper linkage for a given number of angular outputs. Some case studies have been discussed to validate the importance and efficiency of the proposed methodology that can be extended to generate linkage systems with any number of angular outputs for general robotic applications. Full article
(This article belongs to the Section Mechanical Engineering)
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<p>Representation of a four-bar mechanism. (<b>a</b>) Kinematic structure of a four-bar mechanism; (<b>b</b>) graph representation of a four-bar mechanism; (<b>c</b>) modified graph representation of a four-bar mechanism.</p> Full article ">Figure 2
<p>Generation of newer angular outputs using parallel connection.</p> Full article ">Figure 3
<p>Generation of angular outputs using series connection method. (<b>a</b>) Initial topology with Ni outputs; (<b>b</b>) adding newer angular outputs and cut links.</p> Full article ">Figure 4
<p>Generation of two angular output motions. (<b>a</b>) Initial linkage having one output; (<b>b</b>) new output ‘link-5’ is added; (<b>c</b>) available topologies having two outputs; (<b>d</b>) corresponding linkage diagrams.</p> Full article ">Figure 4 Cont.
<p>Generation of two angular output motions. (<b>a</b>) Initial linkage having one output; (<b>b</b>) new output ‘link-5’ is added; (<b>c</b>) available topologies having two outputs; (<b>d</b>) corresponding linkage diagrams.</p> Full article ">Figure 5
<p>Generation of three angular outputs using parallel connection. (<b>a</b>) Initial linkage having two outputs; (<b>b</b>) new output ‘link 7’ is added; (<b>c</b>) available topologies of three outputs with parallel connection; (<b>d</b>) corresponding linkage diagrams for topologies P2 and P4.</p> Full article ">Figure 6
<p>Generation of three angular outputs using series connection. (<b>a</b>) Initial graphical topology having two outputs; links: 4, 5; (<b>b</b>) new output ‘link-7’ is added; (<b>c</b>) all available topologies of three outputs with series connection.</p> Full article ">Figure 7
<p>Using eight-bar linkage as exoskeleton for finger rehabilitation. (<b>a</b>) Selected graph from presented database; (<b>b</b>) corresponding linkage diagram; (<b>c</b>) equivalent exoskeleton linkage introduced by [<a href="#B21-applsci-12-02238" class="html-bibr">21</a>]; (<b>d</b>) desired motion for finger introduced by [<a href="#B21-applsci-12-02238" class="html-bibr">21</a>]; (e) resulting eight-bar linkage introduced by [<a href="#B21-applsci-12-02238" class="html-bibr">21</a>].</p> Full article ">Figure 8
<p>Using eight-bar linkage as exoskeleton for leg rehabilitation. (<b>a</b>) Selected graph from presented database; (<b>b</b>) corresponding linkage diagram; (<b>c</b>) equivalent exoskeleton linkage; (<b>d</b>) Lower limb joints.</p> Full article ">Figure 8 Cont.
<p>Using eight-bar linkage as exoskeleton for leg rehabilitation. (<b>a</b>) Selected graph from presented database; (<b>b</b>) corresponding linkage diagram; (<b>c</b>) equivalent exoskeleton linkage; (<b>d</b>) Lower limb joints.</p> Full article ">Figure 9
<p>Exoskeleton design procedures.</p> Full article ">Figure A1
<p>A complete set of eight-bar linkage topologies with three angular outputs using parallel connection.</p> Full article ">Figure A2
<p>A complete set of ten-bar linkage topologies with four angular outputs using parallel connection.</p> Full article ">Figure A2 Cont.
<p>A complete set of ten-bar linkage topologies with four angular outputs using parallel connection.</p> Full article ">Figure A2 Cont.
<p>A complete set of ten-bar linkage topologies with four angular outputs using parallel connection.</p> Full article ">Figure A3
<p>Some of ten-bar linkage topologies with four angular outputs using series connection.</p> Full article ">Figure A4
<p>Some of the twelve-bar linkage topologies with five angular outputs using parallel connection.</p> Full article ">
26 pages, 12747 KiB  
Article
Design of Particle Dampers for Laser Powder Bed Fusion
by Tobias Ehlers and Roland Lachmayer
Appl. Sci. 2022, 12(4), 2237; https://doi.org/10.3390/app12042237 - 21 Feb 2022
Cited by 14 | Viewed by 3036
Abstract
Additively manufactured particle dampers can significantly improve component damping. However, if designed incorrectly, the damping can be worsened. For the design of additively manufactured particle dampers, there are not yet sufficient design rules and models to describe the effect due to numerous design [...] Read more.
Additively manufactured particle dampers can significantly improve component damping. However, if designed incorrectly, the damping can be worsened. For the design of additively manufactured particle dampers, there are not yet sufficient design rules and models to describe the effect due to numerous design parameters. The research question answered in this paper describes how the effect of particle damping can be characterised as a function of excitation force and excitation frequency for different cavity sizes. To characterise the effect of particle damping, a 33 full factorial test plan is constructed, and the damping is determined experimentally. It is shown that the damping can be reliably evaluated with the circle-fit method. The effect of particle damping is investigated for beams made of AlSi10Mg, 1.2709 and Ti6Al4V. As a result, a positive effect of the particle damping in a frequency range from 500 to 30,000 Hz and partly up to the 9th bending mode can be proven. It is shown that, for the first bending mode, there is an optimum at approx. 2000 Hz. For the optimum, the increase of the damping for the tool steel 1.2709 to 28 and for the aluminium alloy AlSi10Mg to 18 can be proven. Full article
(This article belongs to the Topic Additive Manufacturing)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Laser powder bed fusion of a particle damped gear, reprinted with permission from ref. [<a href="#B7-applsci-12-02237" class="html-bibr">7</a>]. Copyright Elsevier.</p> Full article ">Figure 2
<p>Schematic diagram of an additive manufactured particle damper, according to [<a href="#B7-applsci-12-02237" class="html-bibr">7</a>].</p> Full article ">Figure 3
<p>Frequency response function (FRF) left, circle-fit right, reprinted with permission from ref. [<a href="#B7-applsci-12-02237" class="html-bibr">7</a>]. Copyright Elsevier.</p> Full article ">Figure 4
<p>Flow chart to characterise the effect of particle damping.</p> Full article ">Figure 5
<p>Schematic representation of a particle filled beam on the building platform.</p> Full article ">Figure 6
<p>Test setup for the characterization of particle damping, reprinted with permission from ref. [<a href="#B7-applsci-12-02237" class="html-bibr">7</a>]. Copyright Elsevier.</p> Full article ">Figure 7
<p>Frequency dependent damping of fully-fused (solid) beams, parameter 1, 12, 15, 18, 42, 45, 48, 51, 54, 57, 60, 63.</p> Full article ">Figure 8
<p>Frequency response functions and force-dependent damping characteristics (1st, 3rd and 5th mode) Left: outer dimensions: 05 × 05 × 200 mm<sup>3</sup>, parameter 15–17, material: AlSi10Mg, right: outer dimensions: 4.2 × 4.2 × 169 mm<sup>3</sup>, parameter 46–48, material: 1.2709.</p> Full article ">Figure 9
<p>CT scan of a powder-filled beam made from 1.2709, outer dimensions: 8.4 × 8.4 × 169 mm<sup>3</sup>, parameter 43, material: 1.2709.</p> Full article ">Figure 10
<p>Frequency response functions and force-dependent damping characteristics (1st, 3rd and 5th mode) Left: outer dimensions: 10 × 10 × 200 mm<sup>3</sup>, parameter 12–14, material: AlSi10Mg, right: outer dimensions: 8.4 × 8.4 × 169 mm<sup>3</sup>, parameter 43–45, material: 1.2709.</p> Full article ">Figure 11
<p>Force-dependent damping characteristics 5th mode, outer dimensions: 8.4 × 8.4 × 169 mm<sup>3</sup>, parameter 43–45, material: 1.2709.</p> Full article ">Figure 12
<p>Frequency response functions and force-dependent damping characteristics (1st and 3rd mode) Left: outer dimensions: 20 × 20 × 200 mm<sup>3</sup>, parameter 1, 23 and 25, material: AlSi10Mg, right: outer dimensions: 16.9 × 16.9 × 169 mm<sup>3</sup>, parameter 40–42, material: 1.2709.</p> Full article ">Figure 13
<p>Frequency response functions and force-dependent damping characteristics (1st and 3rd mode) Left: outer dimensions: 20 × 20 × 150 mm<sup>3</sup>, parameter 18–20, material: AlSi10Mg, right: outer dimensions: 16.9 × 16.9 × 126 mm<sup>3</sup>, parameter 49–51, material: 1.2709.</p> Full article ">Figure 14
<p>Force-dependent damping characteristics—1st mode, parameter 40–42, material: 1.2709, outer dimensions: 20 × 20 × 200 mm<sup>3</sup>, left: one hit per excitation force, right: five hits per excitation force.</p> Full article ">Figure 15
<p>Frequency-dependent damping factor.</p> Full article ">Figure 16
<p>Mechanical model for laser beam melted particle dampers.</p> Full article ">
16 pages, 6678 KiB  
Article
Single-Phase, Bidirectional, 7.7 kW Totem Pole On-Board Charging/Discharging Infrastructure
by Vinit Kumar and KangHyun Yi
Appl. Sci. 2022, 12(4), 2236; https://doi.org/10.3390/app12042236 - 21 Feb 2022
Cited by 8 | Viewed by 4288
Abstract
In the present scenario of the fossil fuel crisis, a shift from conventional transportation to electric vehicles (EVs) is the goal, and it is necessary to make it economically feasible. Developing an efficient charger with mid-range power level may successfully resolve this problem. [...] Read more.
In the present scenario of the fossil fuel crisis, a shift from conventional transportation to electric vehicles (EVs) is the goal, and it is necessary to make it economically feasible. Developing an efficient charger with mid-range power level may successfully resolve this problem. In this direction, an EV charging infrastructure has been proposed to achieve grid-to-vehicle (G2V) charging, with vehicle-to-grid (V2G) capability. In G2V mode, the proposed infrastructure consists of an on-board, single-phase, 7.7 kW totem pole converter in continuous conduction mode to achieve high-power factor correction (PFC). Additionally, instead of conventional Si power MOSFET, an SiC-based converter is introduced to lower the switching losses at high switching frequency with smaller filters. Using an SiC-based converter leads to increased efficiency (more than 98%) and reduced total harmonic distortion (less than 5%), making the system economical. Simultaneously, to make the system more economical, the proposed converter works as an inverter to feedback the power to the grid in V2G mode. Furthermore, to analyse the feasibility, the proposed infrastructure has been simulated and its performance is validated using the simpower tool in MATLAB/Simulink environment. Full article
(This article belongs to the Special Issue 5th Anniversary of Energy Section—Recent Advances in Energy)
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Figure 1

Figure 1
<p>A bidirectional charging infrastructure.</p> Full article ">Figure 2
<p>Circuit diagram of the bidirectional charging/discharging infrastructure.</p> Full article ">Figure 3
<p>Block diagram of grid-to-vehicle charging control.</p> Full article ">Figure 4
<p>Grid-side bidirectional totem pole PFC control in G2V mode.</p> Full article ">Figure 5
<p>Battery-side bidirectional converter control in buck/charging mode.</p> Full article ">Figure 6
<p>Block diagram of vehicle-to-grid or discharging control.</p> Full article ">Figure 7
<p>Battery-side bidirectional DC-DC converter control in boost/discharging mode.</p> Full article ">Figure 8
<p>Grid-side bidirectional totem pole inverter control in V2G mode.</p> Full article ">Figure 9
<p>Dynamic performance of the input voltage and current in G2V mode.</p> Full article ">Figure 10
<p>Performance curve of the PF in G2V mode.</p> Full article ">Figure 11
<p>Performance curve of the active and reactive power in G2V mode.</p> Full article ">Figure 12
<p>THD in input current during G2V mode.</p> Full article ">Figure 13
<p>Efficiency of the totem pole PFC w.r.t. input power.</p> Full article ">Figure 14
<p>Dynamic performance of the DC-link voltage.</p> Full article ">Figure 15
<p>Dynamic performance of EV battery’s voltage, current, and SoC during G2V and V2G mode.</p> Full article ">Figure 16
<p>EV batteries power during G2V and V2G mode.</p> Full article ">Figure 17
<p>Dynamic performance of the output voltage and current in V2G mode.</p> Full article ">Figure 18
<p>THD in output current during V2G mode.</p> Full article ">Figure 19
<p>Performance curve of the PF in V2G mode.</p> Full article ">Figure 20
<p>Performance curve of the active and reactive power in V2G mode.</p> Full article ">
3 pages, 171 KiB  
Editorial
Robotic Platforms for Assistance to People with Disabilities
by Carlos A. Jara and Juan A. Corrales
Appl. Sci. 2022, 12(4), 2235; https://doi.org/10.3390/app12042235 - 21 Feb 2022
Cited by 1 | Viewed by 2059
Abstract
People with congenital and/or acquired disabilities constitute a great number of dependents in today’s society [...] Full article
(This article belongs to the Special Issue Robotic Platforms for Assistance to People with Disabilities)
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