Applied Sciences

17 pages, 3672 KiB

Open AccessArticle

Unveiling the Influence of Carbon Nanotube Diameter and Surface Modification on the Anchorage of L-Asparaginase

by Raquel O. Cristóvão, Rita A. M. Barros, João G. Pinho, Lília S. Teixeira, Márcia C. Neves, Mara G. Freire, Joaquim L. Faria, Valéria C. Santos-Ebinuma, Ana P. M. Tavares and Cláudia G. Silva

Appl. Sci. 2022, 12(17), 8924; https://doi.org/10.3390/app12178924 - 05 Sep 2022

Cited by 1 | Viewed by 2099

Abstract

L-asparaginase (ASNase, EC 3.5.1.1) is an amidohydrolase enzyme known for its anti-cancer properties, with an ever-increasing commercial value. Immobilization has been studied to improve the enzyme’s efficiency, enabling its recovery and reuse, enhancing its stability and half-life time. In this work, the effect [...] Read more.

L-asparaginase (ASNase, EC 3.5.1.1) is an amidohydrolase enzyme known for its anti-cancer properties, with an ever-increasing commercial value. Immobilization has been studied to improve the enzyme’s efficiency, enabling its recovery and reuse, enhancing its stability and half-life time. In this work, the effect of pH, contact time and enzyme concentration during the ASNase physical adsorption onto pristine and functionalized multi-walled carbon nanotubes (MWCNTs and f-MWCNTs, respectively) with different size diameters was investigated by maximizing ASNase relative recovered activity (RRA) and immobilization yield (IY). Immobilized ASNase reusability and kinetic parameters were also evaluated. The ASNase immobilization onto f-MWCNTs offered higher loading capacities, enhanced reusability, and improved enzyme affinity to the substrate, attaining RRA and IY of 100 and 99%, respectively, at the best immobilization conditions (0.4 mg/mL of ASNase, pH 8, 30 min of contact time). In addition, MWCNTs diameter proved to play a critical role in determining the enzyme binding affinity, as evidenced by the best results attained with f-MWCNTs with diameters of 10–20 nm and 20–40 nm. This study provided essential information on the impact of MWCNTs diameter and their surface functionalization on ASNase efficiency, which may be helpful for the development of innovative biomedical devices or food pre-treatment solutions. Full article

(This article belongs to the Special Issue Women in Materials Science)

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10 pages, 367 KiB

Open AccessArticle

Performance Analysis of Storage Systems in Edge Computing Infrastructures

by Antonios Makris, Ioannis Kontopoulos, Evangelos Psomakelis, Stylianos Nektarios Xyalis, Theodoros Theodoropoulos and Konstantinos Tserpes

Appl. Sci. 2022, 12(17), 8923; https://doi.org/10.3390/app12178923 - 05 Sep 2022

Cited by 5 | Viewed by 2056

Abstract

Edge computing constitutes a promising paradigm of managing and processing the massive amounts of data generated by Internet of Things (IoT) devices. Data and computation are moved closer to the client, thus enabling latency- and bandwidth-sensitive applications. However, the distributed and heterogeneous nature [...] Read more.

Edge computing constitutes a promising paradigm of managing and processing the massive amounts of data generated by Internet of Things (IoT) devices. Data and computation are moved closer to the client, thus enabling latency- and bandwidth-sensitive applications. However, the distributed and heterogeneous nature of the edge as well as its limited resource capabilities pose several challenges in implementing or choosing an efficient edge-enabled storage system. Therefore, it is imperative for the research community to contribute to the clarification of the purposes and highlight the advantages and disadvantages of various edge-enabled storage systems. This work aspires to contribute toward this direction by presenting a performance analysis of three different storage systems, namely MinIO, BigchainDB, and the IPFS. We selected these three systems as they have been proven to be valid candidates for edge computing infrastructures. In addition, as the three evaluated systems belong to different types of storage, we evaluated a wide range of storage systems, increasing the variability of the results. The performance evaluation is performed using a set of resource utilization and Quality of Service (QoS) metrics. Each storage system is deployed and installed on a Raspberry Pi (small single-board computers), which serves as an edge device, able to optimize the overall efficiency with minimum power and minimum cost. The experimental results revealed that MinIO has the best overall performance regarding query response times, RAM consumption, disk IO time, and transaction rate. The results presented in this paper are intended for researchers in the field of edge computing and database systems. Full article

(This article belongs to the Special Issue Cloud, Fog and Edge Computing in the IoT and Industry Systems)

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22 pages, 7949 KiB

Open AccessArticle

Target-Oriented High-Resolution and Wide-Swath Imaging with an Adaptive Receiving–Processing–Decision Feedback Framework

by Xu Zhan, Xiaoling Zhang, Wensi Zhang, Yuetonghui Xu, Jun Shi, Shunjun Wei and Tianjiao Zeng

Appl. Sci. 2022, 12(17), 8922; https://doi.org/10.3390/app12178922 - 05 Sep 2022

Cited by 2 | Viewed by 1182

Abstract

High-resolution and wide-swath (HRWS) synthetic aperture radar (SAR) is a promising technique for applications such as maritime surveillance. In the maritime environment, normally only a few targets such as ships are interested. However, before detecting them, considerable receiving resources and computation time are [...] Read more.

High-resolution and wide-swath (HRWS) synthetic aperture radar (SAR) is a promising technique for applications such as maritime surveillance. In the maritime environment, normally only a few targets such as ships are interested. However, before detecting them, considerable receiving resources and computation time are required to receive the echoes of the whole scene and process them to obtain imaging results. This is a heavy burden for online monitoring on platforms with limited resources. To address these issues, different from the concept of whole-scene-oriented imaging, we propose a target-oriented imaging concept, which is implemented by an adaptive receiving–processing–decision feedback framework with feedback connection. (1) To reduce receiving resource consumption, we propose a two-dimensional adaptive receiving module. It receives sub-band echoes of targets only through dechirping and subaperture decomposition in the range and azimuth directions, respectively. (2) To reduce computation time, we propose a target-oriented processing module. It processes subarea echoes of targets only through parallelly conducting inverse fast Fourier transform (IFFT) and back projection (BP) in the range and azimuth directions, respectively. (3) To allocate resources reasonably, we propose a decision module. It decides the necessary receiving window, bandwidth, and image resolution through constant false alarm rate (CFAR) detection. (4) To allocate resources adaptively, we connect three modules with a closed loop to enable feedback. This enables progressive target imaging and detection from rough to fine. Experimental results verify the feasibility of the proposed framework. Compared with the current one, for a typical scenario, at least 30% of the system’s resources and 99% of computation time are saved. Full article

(This article belongs to the Special Issue Computational Sensing and Imaging)

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13 pages, 14407 KiB

Open AccessArticle

The Mask Fitter, a Simple Method to Improve Medical Face Mask Adaptation Using a Customized 3D-Printed Frame during COVID-19: A Survey on Users’ Acceptability in Clinical Dentistry

by Alessandro Vichi, Dario Balestra, Cecilia Goracci, David R. Radford and Chris Louca

Appl. Sci. 2022, 12(17), 8921; https://doi.org/10.3390/app12178921 - 05 Sep 2022

Cited by 2 | Viewed by 1465

Abstract

COVID-19 has deeply impacted clinical strategies in dentistry and the use of surgical masks and respirators has become critical. They should adapt to the person’s facial anatomy, but this is not always easy to achieve. Bellus3D Company proposed to apply their face scan [...] Read more.

COVID-19 has deeply impacted clinical strategies in dentistry and the use of surgical masks and respirators has become critical. They should adapt to the person’s facial anatomy, but this is not always easy to achieve. Bellus3D Company proposed to apply their face scan software, used with selected smartphones and tablets, to design and 3D-print a bespoke “Mask Fitter” to improve the sealing of surgical masks and respirators. Twenty dental staff participants were face scanned and a Mask Fitter for FFP2 respirators was designed and 3D-printed. Participants were asked to wear their Mask Fitter over one week and then completed a survey. Questions were asked about wearing comfort, sealing confidence, glasses or loupes fogging, both with and without the Mask Fitter. Dental staff gave positive feedback, with levels of comfort during daily use reported as similar with and without the Mask Fitter; and a higher confidence in achieving a proper seal, ranging from a 10% confidence rating of a proper seal without the Mask Fitter to 75% with the Mask Fitter. Moreover, fogging problems decreased considerably. The tested Mask Fitter device could represent an easy and low-cost procedure to improve the facial adaptation of the FFP2 respirator. Full article

(This article belongs to the Special Issue 3D Printed Materials Dentistry)

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15 pages, 4702 KiB

Open AccessArticle

Study on the Technology Trend Screening Framework Using Unsupervised Learning

by Junseok Lee, Sangsung Park and Juhyun Lee

Appl. Sci. 2022, 12(17), 8920; https://doi.org/10.3390/app12178920 - 05 Sep 2022

Cited by 2 | Viewed by 1427

Abstract

Outliers that deviate from a normal distribution are typically removed during the analysis process. However, the patterns of outliers are recognized as important information in the outlier detection method. This study proposes a technology trend screening framework based on a machine learning algorithm [...] Read more.

Outliers that deviate from a normal distribution are typically removed during the analysis process. However, the patterns of outliers are recognized as important information in the outlier detection method. This study proposes a technology trend screening framework based on a machine learning algorithm using outliers. The proposed method is as follows: first, we split the dataset by time into training and testing sets for training the Doc2Vec model. Next, we pre-process the patent documents using the trained model. The final outlier documents are selected from the preprocessed document data, through voting for the outlier documents extracted using the IQR, the three-sigma rule, and the Isolation Forest algorithm. Finally, the technical topics of the outlier documents extracted through the topic model are identified. This study analyzes the patent data on drones to describe the proposed method. Results show that, despite cumulative research on drone-related hardware and system technology, there is a general lack of research regarding the autonomous flight field. Full article

(This article belongs to the Special Issue Bayesian Statistics on Artificial Intelligence: Theory, Methods and Applications)

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16 pages, 6849 KiB

Open AccessArticle

Shear Wave Velocity Estimation Based on Deep-Q Network

by Xiaoyu Zhu and Hefeng Dong

Appl. Sci. 2022, 12(17), 8919; https://doi.org/10.3390/app12178919 - 05 Sep 2022

Cited by 2 | Viewed by 1144

Abstract

Geoacoustic inversion is important for seabed geotechnical applications. It can be formulated as a problem that seeks an optimal solution in a high-dimensional parameter space. The conventional inversion approach exploits optimization methods with a pre-defined search strategy whose hyperparameters need to be fine-tuned [...] Read more.

Geoacoustic inversion is important for seabed geotechnical applications. It can be formulated as a problem that seeks an optimal solution in a high-dimensional parameter space. The conventional inversion approach exploits optimization methods with a pre-defined search strategy whose hyperparameters need to be fine-tuned for a specific scenario. A framework based on the deep-Q network is proposed in this paper and the environment and agent configurations of the framework are specially defined for geoacoustic inversion. Unlike a conventional optimization method with a pre-defined search strategy, the proposed framework determines a flexible strategy by trial and error. The proposed framework is evaluated by two case studies for estimating the shear wave velocity profile. Its performance is compared with three global optimization methods commonly used in underwater geoacoustic inversion. The results demonstrate that the proposed framework performs the inversion more efficiently and accurately. Full article

(This article belongs to the Special Issue Advances in Artificial Intelligence: Machine Learning, Data Mining and Data Sciences)

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14 pages, 1857 KiB

Open AccessArticle

Potential Use of Fusarium Isolates as Biological Control Agents: Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) Case Study

by Spiridon Mantzoukas, Foteini Kitsiou, Ioannis Lagogiannis and Panagiotis A. Eliopoulos

Appl. Sci. 2022, 12(17), 8918; https://doi.org/10.3390/app12178918 - 05 Sep 2022

Cited by 3 | Viewed by 1379

Abstract

The cotton bollworm Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is a notorious agricultural pest with world-wide distribution, extreme polyphagy, high mobility and fecundity, facultative diapause, and significant resistance to chemical insecticides. Isolates from various Fusarium species were collected from soil, identified, and tested for [...] Read more.

The cotton bollworm Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is a notorious agricultural pest with world-wide distribution, extreme polyphagy, high mobility and fecundity, facultative diapause, and significant resistance to chemical insecticides. Isolates from various Fusarium species were collected from soil, identified, and tested for their entomopathogenicity against H. armigera larvae in field experiments. Fungi of the genus Fusarium are ubiquitous and include phytopathogenic as well as entomopathogenic strains. Seven Fusarium species were identified and tested, including: F. algeriense, F. chlamydosporum var. chlamydosporum, F. fujikuroi, F. longifundum, F. pseudoanthophilum, F.solani, and F. tonkinense. All the collected fungi demonstrated a notable insecticidal effect on H. armigera larvae in field conditions, while some proved to be significantly lethal. The larval mortality of H. armigera ranged from 10 (10³ conidia/mL) to 91% (10⁸ conidia/mL) after 9 days (216 h). Larval survival time in treated plants ranged from 95 h (10⁸ conidia/mL) to 208 h (10³ conidia/mL). According to our results, F. solani isolate displayed the highest toxicity against H. armigera larvae and could be considered as a promising biocontrol agent of this serious pest. Full article

(This article belongs to the Special Issue Biological and Chemical Control of Pests in Agriculture and Stored Environments)

23 pages, 6767 KiB

Open AccessArticle

Parametric Assessment of Surface Topography and Its Influence on Joint Tightness of Non-Separable Joints for Thin Wall Applications

by Nikodem Wróbel, Michał Rejek, Jolanta Królczyk, Mateusz Franka, Munish Kumar Gupta, Marcin Śliwiński and Grzegorz Królczyk

Appl. Sci. 2022, 12(17), 8917; https://doi.org/10.3390/app12178917 - 05 Sep 2022

Cited by 2 | Viewed by 1274

Abstract

This article describes the research carried out on six thin-walled groups of samples produced from the aluminum alloy 6060 T4 by a turning and milling operation. Additionally, the analysis of the surface topography was carried out, focusing on three-dimensional parameters, such as Sq [...] Read more.

This article describes the research carried out on six thin-walled groups of samples produced from the aluminum alloy 6060 T4 by a turning and milling operation. Additionally, the analysis of the surface topography was carried out, focusing on three-dimensional parameters, such as Sq, Ssk, Sku, Sp, Sv, Sz, Sa, Spd, and Spc. Moreover, the article contains the tests of the tightness of various types of surfaces with different clamping forces of the tested elements. Furthermore, an attempt was made to find significant representatives of the surface topography to obtain the smallest leakage between the mating surfaces. The maximum clamping force obtained in the tests between the pairs was 9060 N. Finally, it is worth mentioning that the presented surface tests can serve as the required parameters for joined elements in the production of non-detachable joints by, for example, clinching. Full article

(This article belongs to the Section Surface Sciences and Technology)

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12 pages, 2079 KiB

Open AccessCommunication

Bacterial Profile and Changes in the Protein–Peptide Fraction in Spontaneously Fermented Lens culinaris Medik.

by Katarzyna Skrzypczak, Katarzyna Michalak, Jakub Wyrostek, Ewa Jabłońska-Ryś, Aneta Sławińska, Wojciech Radzki and Waldemar Gustaw

Appl. Sci. 2022, 12(17), 8916; https://doi.org/10.3390/app12178916 - 05 Sep 2022

Cited by 1 | Viewed by 1216

Abstract

Pulses have desirable nutritional properties and a wide range of applications in the food industry as meat-free, casein-free, gluten-free, and functional food products. Unfortunately, the legume raw material contains some anti-nutrients and allergenic agents; nonetheless, fermentation processes may reduce some of these undesirable [...] Read more.

Pulses have desirable nutritional properties and a wide range of applications in the food industry as meat-free, casein-free, gluten-free, and functional food products. Unfortunately, the legume raw material contains some anti-nutrients and allergenic agents; nonetheless, fermentation processes may reduce some of these undesirable compounds. Therefore, the objective of the preliminary investigation was to determine the profile of bacteria occurring after spontaneous fermentation of Lens culinaris Medik. and detect changes in the protein–peptide pattern, including potential modifications of Len c3, i.e., a non-specific lipid-transfer protein (nsLTP) recognized as an important allergen. This study involved MALDI TOF/TOF, Illumina next-generation sequencing, and FT-IR spectroscopy analyses. Sixteen different species were identified in the plant-based material after 48-h spontaneous fermentation. The most abundant species were Lactococcus taiwanensis and Pediococcus pentosaceus (54.95% and 25.34%, respectively). The performed initial analysis revealed that after spontaneous fermentation had occurred the degradation of proteins (~10 kDa) and peptides (6–8 kDa), as well as the decomposition of proteins in the mass range that might be attributed to allergenic nsLTP. The preliminary findings encourage further research into the functional and technological properties of the isolated bacteria and in-depth analyses of the possibility of the removal of allergenic compounds from red lentils through fermentation carried out by the isolates. Full article

(This article belongs to the Special Issue Fermentation Technology in Food Production)

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11 pages, 31940 KiB

Open AccessCommunication

A Compact Broadband Planar Inverted-F Antenna with Dual-Resonant Modes

by Zhengya Qi, Xinhao Ding, Wenwen Yang and Jianxin Chen

Appl. Sci. 2022, 12(17), 8915; https://doi.org/10.3390/app12178915 - 05 Sep 2022

Cited by 3 | Viewed by 2135

Abstract

In this paper, a compact broadband planar inverted-F antenna (PIFA) with dual-resonant modes (TM_1/2,₂ and TM_3/2,₀) is proposed for 5G applications. By loading a pair of horizontal slots on the patch, the TM_3/2,0 mode can be shifted [...] Read more.

In this paper, a compact broadband planar inverted-F antenna (PIFA) with dual-resonant modes (TM_1/2,₂ and TM_3/2,₀) is proposed for 5G applications. By loading a pair of horizontal slots on the patch, the TM_3/2,0 mode can be shifted downward and combined with the TM_1/2,₂ mode, leading to a dual-mode operation. Meanwhile, another pair of slots, which are orthogonal to the previous pair, is introduced to improve the impedance matching of the antenna. Moreover, the substrate with a high dielectric constant is used in this design to achieve a compact antenna size. In order to verify the principle and the design method, an antenna prototype was fabricated and measured. Experimental results show that the PIFA has a good performance with a −10 dB impedance bandwidth of 14.5% (3.17–3.67 GHz), a peak gain of 6.23 dBi, a low cross-polarization level of −17.3 dB, and a compact size of 0.45 × 0.26 × 0.03 λ₀₁³ (λ₀₁ is the free-space wavelength at 3.5 GHz). The antenna is predicted to be suitable for 5G terminal applications. Full article

(This article belongs to the Special Issue Emerging Antenna and Radiofrequency Technologies for 5G and 6G Wireless Communications)

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43 pages, 35434 KiB

Open AccessReview

An Insight into the Integration of Distributed Energy Resources and Energy Storage Systems with Smart Distribution Networks Using Demand-Side Management

by Subhasis Panda, Sarthak Mohanty, Pravat Kumar Rout, Binod Kumar Sahu, Shubhranshu Mohan Parida, Hossam Kotb, Aymen Flah, Marcos Tostado-Véliz, Bdereddin Abdul Samad and Mokhtar Shouran

Appl. Sci. 2022, 12(17), 8914; https://doi.org/10.3390/app12178914 - 05 Sep 2022

Cited by 13 | Viewed by 3794

Abstract

Demand-side management (DSM) is a significant component of the smart grid. DSM without sufficient generation capabilities cannot be realized; taking that concern into account, the integration of distributed energy resources (solar, wind, waste-to-energy, EV, or storage systems) has brought effective transformation and challenges [...] Read more.

Demand-side management (DSM) is a significant component of the smart grid. DSM without sufficient generation capabilities cannot be realized; taking that concern into account, the integration of distributed energy resources (solar, wind, waste-to-energy, EV, or storage systems) has brought effective transformation and challenges to the smart grid. In this review article, it is noted that to overcome these issues, it is crucial to analyze demand-side management from the generation point of view in considering various operational constraints and objectives and identifying multiple factors that affect better planning, scheduling, and management. In this paper, gaps in the research and possible prospects are discussed briefly to provide a proper insight into the current implementation of DSM using distributed energy resources and storage. With the expectation of an increase in the adoption of various types of distributed generation, it is estimated that DSM operations can offer a valuable opportunity for customers and utility aggregators to become active participants in the scheduling, dispatch, and market-oriented trading of energy. This review of DSM will help develop better energy management strategies and reduce system uncertainties, variations, and constraints. Full article

(This article belongs to the Special Issue Renewable-Based Microgrids: Design, Control and Optimization)

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20 pages, 6160 KiB

Open AccessArticle

Roll Eccentricity Signal Detection and Its Engineering Application Based on SFFT-IAA

by Zhe Yang, Ding Liu and Gang Zheng

Appl. Sci. 2022, 12(17), 8913; https://doi.org/10.3390/app12178913 - 05 Sep 2022

Cited by 2 | Viewed by 1628

Abstract

The roll eccentricity signal is a weak and complex periodic signal that is difficult to be identified. To improve the detection accuracy of the roll eccentricity signal and to compensate effectively, this study proposed a roll eccentricity signal detection method by combining the [...] Read more.

The roll eccentricity signal is a weak and complex periodic signal that is difficult to be identified. To improve the detection accuracy of the roll eccentricity signal and to compensate effectively, this study proposed a roll eccentricity signal detection method by combining the sparse fast Fourier transform (SFFT) and the iterative adaptive approach (IAA). The proposed method can rapidly determine the frequency range of the roll eccentricity signal by using the SFFT. Then, it divides the frequency range into several small frequency bands. In each small frequency band, the frequency, amplitude, and phase angle of each harmonic component of the roll eccentricity signal were estimated by using IAA. The simulation results show that the proposed method can find all frequency components, and the frequency estimation accuracy is higher than 99.88%. Finally, the engineering application of this method and the eccentricity compensation control were investigated. In engineering applications, the proposed method can reduce the thickness fluctuation of the finished strip by 89.2%, and the product quality is improved significantly. The simulation results and engineering experiments show that the proposed method has an excellent effect on detecting and compensating roll eccentricity signals. Full article

(This article belongs to the Special Issue Selected Papers from FCPAE2022 and 4th International Conference on Artificial Intelligence and Advanced Manufacturing (AIAM2022))

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18 pages, 2790 KiB

Open AccessArticle

Implementation of Autonomous Mobile Robot in SmartFactory

by Radim Hercik, Radek Byrtus, Rene Jaros and Jiri Koziorek

Appl. Sci. 2022, 12(17), 8912; https://doi.org/10.3390/app12178912 - 05 Sep 2022

Cited by 15 | Viewed by 4327

Abstract

This study deals with the technology of autonomous mobile robots (AMR) and their implementation on the SmartFactory production line at the Technical University of Ostrava. The task of the mobile robot is to cooperate with the production line, take over the manufactured products, [...] Read more.

This study deals with the technology of autonomous mobile robots (AMR) and their implementation on the SmartFactory production line at the Technical University of Ostrava. The task of the mobile robot is to cooperate with the production line, take over the manufactured products, and then deliver them. The content also includes a description of the individual steps that were necessary to make the mobile robot operational, such as loading a virtual map of the space, creating a network for communication with the mobile robot, and programming it. The main part of the experiment deals with testing the accuracy of moving the mobile robot to each position and establishing communication between the production line and the mobile robot. A high accuracy is a necessity in this process. The result of the study is the configuration of the autonomous mobile robot. The repetitive precision of the approach of the autonomous mobile robot to a position is ±3 mm. Full article

(This article belongs to the Special Issue Trajectory Analysis, Positioning and Control of Mobile Robots)

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12 pages, 4530 KiB

Open AccessArticle

Cooling Performance of Fresh and Aged Automatic Transmission Fluids for Hybrid Electric Vehicles

by Noelia Rivera, José Luis Viesca, Alberto García, Jose I. Prado, Luis Lugo and Antolin Hernández Battez

Appl. Sci. 2022, 12(17), 8911; https://doi.org/10.3390/app12178911 - 05 Sep 2022

Cited by 5 | Viewed by 1588

Abstract

The cooling performance of automatic transmission fluids (ATFs) plays an important role in hybrid electrical vehicles, in which the electric motor (EM) is placed inside the transmission housing due to their mission of cooling the EM. The cooling performance of the ATFs depends [...] Read more.

The cooling performance of automatic transmission fluids (ATFs) plays an important role in hybrid electrical vehicles, in which the electric motor (EM) is placed inside the transmission housing due to their mission of cooling the EM. The cooling performance of the ATFs depends on their thermophysical properties, but these properties change with the oxidation of the ATFs. This work studies the influence of the oxidation of three ATFs (A, B, C) on their thermophysical properties, as well as on some figures-of-merit (FOMs) which are relevant for evaluating the cooling performance. The results indicated that the influence of the molecular structure on thermal conductivity and heat capacity is stronger than on density and viscosity, whereas the molecular structure hardly affects the FOMs of the fresh ATFs; ATFs B and C, formulated with base oils from API Group III, indicated better cooling performance than ATF A which was formulated with base oils from API Group I; the sensitivity to temperature of the variation with oxidation of the studied properties, including the FOMs, was almost null, except for ATF A; therefore, FOMs should be used to compare the cooling performance of ATFs for electric drivetrains instead of a single property, such as thermal conductivity. Full article

(This article belongs to the Section Applied Physics General)

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16 pages, 10267 KiB

Open AccessArticle

RGB-D Camera for 3D Laser Point Cloud Hole Repair in Mine Access Shaft Roadway

by Haoyu Tai, Yonghua Xia, Xiangrong He, Xuequn Wu, Chen Li, Min Yan, Xiali Kong and Minglong Yang

Appl. Sci. 2022, 12(17), 8910; https://doi.org/10.3390/app12178910 - 05 Sep 2022

Cited by 4 | Viewed by 1742

Abstract

With the rapid development of the geographic information service industry, point cloud data are widely used in various fields, such as architecture, planning, cultural relics protection, mining engineering, etc. Despite that there are many approaches to collecting point clouds, we are facing the [...] Read more.

With the rapid development of the geographic information service industry, point cloud data are widely used in various fields, such as architecture, planning, cultural relics protection, mining engineering, etc. Despite that there are many approaches to collecting point clouds, we are facing the problem of point cloud holes caused by the inability of a 3D laser scanner to collect data completely in the narrow space of the mine access shaft. Thus, this paper uses RGB-D cameras to collect data and reconstruct the hole in the point cloud. We used a 3D laser scanner and RGB-D depth camera to collect the 3D point cloud data of the access shaft roadway. The maximum error was 2.617 cm and the minimum error was 0.031 cm by measuring the distance between the feature points, which satisfied the visualization repair of the missing parts of the 3D laser scanner data collection. We used the FPTH + ICP algorithm, ISS + ICP algorithm, SVD + ICP algorithm, and 3D-NDT algorithm to perform registration and fusion of the processed 3D point cloud and the original point cloud and finally repaired the hole. The study results show that the ISS + ICP registration algorithm had the most matching points and the lowest RMSE value of 13.8524 mm. In addition, in the closed and narrow roadway, the RGB-D camera was light and easy to operate and the point data acquired by it had relatively high precision. The three-dimensional point cloud of the repaired access shaft roadway has a good fit and can meet the repair requirements. Full article

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20 pages, 3539 KiB

Open AccessArticle

Influence of Self-Compaction on the Airflow Resistance of Aerated Wheat Bulks (Triticum aestivum L., cv. ‘Pionier’)

by Iris Ramaj, Steffen Schock, Shkelqim Karaj and Joachim Müller

Appl. Sci. 2022, 12(17), 8909; https://doi.org/10.3390/app12178909 - 05 Sep 2022

Cited by 5 | Viewed by 1530

Abstract

Aeration is a key post-harvest grain processing operation that forces air through the pore volume of the grain bulk to establish favorable conditions to maintain grain quality and improve its storability. However, during storage, grain bulk experiences self-compaction due to its dead weight, [...] Read more.

Aeration is a key post-harvest grain processing operation that forces air through the pore volume of the grain bulk to establish favorable conditions to maintain grain quality and improve its storability. However, during storage, grain bulk experiences self-compaction due to its dead weight, which alters the bulk properties and impedes the uniform flow of air during aeration. Thus, this study focused on investigating the effect of self-compaction on the pressure drop ΔP of wheat bulk (Triticum aestivum L., cv. ‘Pionier’, X = 0.123 kg·kg⁻¹ d.b.) accommodated in a laboratory-scale bin (V_b = 0.62 m³) at a coherent set of airflow velocities v_a. Pressure drop ΔP was measured at bulk depths H_b of 1.0, 2.0, 3.0 and 3.4 m and storage times t of 1, 65, 164 and 236 h. For the semi-empirical characterization of the relationship between ΔP and v_a, the model of Matthies and Petersen was used, which was proficient in describing the experimental data with decent accuracy (R² = 0.990, RMSE = 68.67 Pa, MAPE = 12.50%). A tailored product factor k was employed for the specific grain bulk conditions. Results revealed a reduction of in-situ pore volume ε from 0.413 to 0.391 at bulk depths H_b of 1.0 to 3.4 m after 1 h storage time t and from 0.391 to 0.370 after 236 h storage time t, respectively. A disproportional increase of the pressure drop ΔP with bulk depth H_b and storage time t was observed, which was ascribed to the irreversible spatio-temporal behavior of self-compaction. The variation of pore volume ε was modeled and facilitated the development of a generalized model for predicting the relationship between ΔP and v_a. The relative importance of modeling parameters was evaluated by a sensitivity analysis. In conclusion, self-compaction has proven to have a significant effect on airflow resistance, therefore it should be considered in the analysis and modeling of cooling, aeration and low-temperature drying of in-store grain bulks. Full article

(This article belongs to the Special Issue Engineering of Smart Agriculture)

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39 pages, 1590 KiB

Open AccessArticle

Validation of a Wind Tunnel Propeller Dynamometer for Group 2 Unmanned Aircraft

by Muwanika Jdiobe, Kurt Rouser, Ryan Paul and Austin Rouser

Appl. Sci. 2022, 12(17), 8908; https://doi.org/10.3390/app12178908 - 05 Sep 2022

Cited by 1 | Viewed by 1898

Abstract

This paper presents an approach to validate a wind tunnel propeller dynamometer applicable to Group 2 unmanned aircraft. The intended use of such a dynamometer is to characterize propellers over a relevant range of sizes and operating conditions, under which such propellers are [...] Read more.

This paper presents an approach to validate a wind tunnel propeller dynamometer applicable to Group 2 unmanned aircraft. The intended use of such a dynamometer is to characterize propellers over a relevant range of sizes and operating conditions, under which such propellers are susceptible to low-Reynolds-number effects that can be challenging to experimentally detect in a wind tunnel. Even though uncertainty analysis may inspire confidence in dynamometer data, it is possible that a dynamometer design or experimental arrangement (e.g., configuration and instrumentation) is not able to detect significant propeller characteristics and may even impart artifacts in the results. The validation method proposed here compares analytical results from Blade Element Momentum Theory (BEMT) to experimental data to verify that a dynamometer captures basic propeller physics, as well as self-similar experimental results to verify that a dynamometer is able to resolve differences in propeller diameter and pitch. Two studies were conducted to verify that dynamometer experimental data match the performance predicted by BEMT. The first study considered three propellers with the same 18-inch (0.457 m) diameter and varied pitch from 10 to 14 inches (0.254 to 0.356 m). The second study held pitch constant and varied diameter from 14 to 18 inches (0.356 to 0.457 m). During testing, wind tunnel speeds ranged from 25 ft/s to 50 ft/s ( 7.62 to 15.24 m/s), and propeller rotational speeds varied from 1500 to 5500 revolutions per minute (RPM). Analytical results from a BEMT code were compared to available experimental data from previous work to show proper application of the code to predict performance. Dynamometer experimental results for thrust coefficient and propeller efficiency were then compared to BEMT results. Experimental results were consistent with the expected effect of varying pitch and diameter and were in close agreement with BEMT predictions, lending confidence that the dynamometer performed as expected and is dependable for future data collection efforts. The method used in this study is recommended for validating wind tunnel propeller dynamometers, especially for Group 2 unmanned aircraft, to ensure reliable performance data. Full article

(This article belongs to the Special Issue Unmanned Aerial Vehicles)

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18 pages, 6780 KiB

Open AccessArticle

Mechanical and Thermal Properties of Aluminum Matrix Composites Reinforced by In Situ Al₂O₃ Nanoparticles Fabricated via Direct Chemical Reaction in Molten Salts

by Liudmila A. Yolshina, Aleksander G. Kvashnichev, Dmitrii I. Vichuzhanin and Evgeniya O. Smirnova

Appl. Sci. 2022, 12(17), 8907; https://doi.org/10.3390/app12178907 - 05 Sep 2022

Cited by 4 | Viewed by 2357

Abstract

The development of novel methods for industrial production of metal-matrix composites with improved properties is extremely important. An aluminum matrix reinforced by “in situ” α-Al₂O₃ nanoparticles was fabricated via direct chemical reaction between molten aluminum and rutile TiO₂ nanopowder [...] Read more.

The development of novel methods for industrial production of metal-matrix composites with improved properties is extremely important. An aluminum matrix reinforced by “in situ” α-Al₂O₃ nanoparticles was fabricated via direct chemical reaction between molten aluminum and rutile TiO₂ nanopowder under the layer of molten salts at 700–800 °C in air atmosphere. Morphology, size, and distribution of the in situ particles, as well as the microstructure and mechanical properties of the composites were investigated by XRD, SEM, Raman spectra, and hardness and tensile tests. Synthesized aluminum–alumina composites with Al₂O₃ concentration up to 19 wt.% had a characteristic metallic luster, their surfaces were smooth without any cracks and porosity. The obtained results indicate that the “in situ” particles were mainly cube-shaped on the nanometer scale and uniform matrix distribution. The concentration of Al₂O₃ nanoparticles depended on the exposure time and initial precursor concentration, rather than on the synthesis temperature. The influence of the structure of the studied materials on their ultimate strength, yield strength, and plasticity under static loads was established. It is shown that under static uniaxial tension, the cast aluminum composites containing aluminum oxide nanoparticles demonstrated significantly increased tensile strength, yield strength, and ductility. The microhardness and tensile strength of the composite material were by 20–30% higher than those of the metallic aluminum. The related elongation increased three times after the addition of nano-α Al₂O₃ into the aluminum matrix. Composite materials of the Al-Al₂O₃ system could be easily rolled into thin and ductile foils and wires. They could be re-melted for the repeated application. Full article

(This article belongs to the Special Issue Metal-Based Composite Materials: Preparation, Structure, Properties, and Applications)

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18 pages, 2095 KiB

Open AccessArticle

A Fuzzy-Based Method for Objects Selection in Blockchain-Enabled Edge-IoT Platforms Using a Hybrid Multi-Criteria Decision-Making Model

by Bhaskar B. Gardas, Arash Heidari, Nima Jafari Navimipour and Mehmet Unal

Appl. Sci. 2022, 12(17), 8906; https://doi.org/10.3390/app12178906 - 05 Sep 2022

Cited by 17 | Viewed by 2028

Abstract

The broad availability of connected and intelligent devices has increased the demand for Internet of Things (IoT) applications that require more intense data storage and processing. However, cloud-based IoT systems are typically located far from end-users and face several issues, including high cloud [...] Read more.

The broad availability of connected and intelligent devices has increased the demand for Internet of Things (IoT) applications that require more intense data storage and processing. However, cloud-based IoT systems are typically located far from end-users and face several issues, including high cloud server load, slow response times, and a lack of global mobility. Some of these flaws can be addressed with edge computing. In addition, node selection helps avoid common difficulties related to IoT, including network lifespan, allocation of resources, and trust in the acquired data by selecting the correct nodes at a suitable period. On the other hand, the IoT’s interconnection of edge and blockchain technologies gives a fresh perspective on access control framework design. This article provides a novel node selection approach for blockchain-enabled edge IoT that provides a quick and dependable node selection. Moreover, fuzzy logic to approximation logic was used to manage numerical and linguistic data simultaneously. In addition, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), a powerful tool for examining Multi-Criteria Decision-Making (MCDM) problems, is used. The suggested fuzzy-based technique employs three input criteria to select the correct IoT node for a given mission in IoT-edge situations. The outcomes of the experiments indicate that the proposed framework enhances the parameters under consideration. Full article

(This article belongs to the Special Issue Secure Provisioning Services in Cloud-Edge Systems)

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13 pages, 3352 KiB

Open AccessArticle

Surface Defect Detection of Rolled Steel Based on Lightweight Model

by Shunyong Zhou, Yalan Zeng, Sicheng Li, Hao Zhu, Xue Liu and Xin Zhang

Appl. Sci. 2022, 12(17), 8905; https://doi.org/10.3390/app12178905 - 05 Sep 2022

Cited by 7 | Viewed by 2005

Abstract

A lightweight rolled steel strip surface defect detection model, YOLOv5s-GCE, is proposed to improve the efficiency and accuracy of industrialized rolled steel strip defect detection. The Ghost module is used to replace the CBS structure in a part of the original YOLOv5s model, [...] Read more.

A lightweight rolled steel strip surface defect detection model, YOLOv5s-GCE, is proposed to improve the efficiency and accuracy of industrialized rolled steel strip defect detection. The Ghost module is used to replace the CBS structure in a part of the original YOLOv5s model, and the Ghost bottleneck is employed to replace the bottleneck structure in C3 to minimize the model’s size and make the network lightweight. The EIoU function is added to improve the accuracy of the regression of the prediction frame and accelerate its convergence. The CA (Coordinate Attention) attention method is implemented to reinforce critical feature channels and their position information, enabling the model to identify and find targets correctly. The experimental results demonstrate that the accuracy of YOLOv5s-GCE is 85.7%, which is 3.5% higher than that of the original network; the model size is 7.6 MB, which is 44.9% smaller than that of the original network; the number of model parameters and calculations are reduced by 47.1% and 48.8%, respectively; and the detection speed reached 58.8 fps. YOLOv5s-GCE meets the necessity for real-time identification of rolled steel flaws in industrial production compared to other common algorithms. Full article

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17 pages, 5653 KiB

Open AccessArticle

Superconducting Sub-Terahertz Oscillator with Continuous Frequency Tuning

by Maxim E. Paramonov, Lyudmila V. Filippenko, Fedor V. Khan, Oleg S. Kiselev and Valery P. Koshelets

Appl. Sci. 2022, 12(17), 8904; https://doi.org/10.3390/app12178904 - 05 Sep 2022

Cited by 1 | Viewed by 1476

Abstract

The development and approbation of a superconducting local oscillator based on a long Josephson junction made it possible to create a fully superconducting integrated receiver in sub-terahertz frequency range, which was successfully tested both on board a high-altitude balloon and in the laboratory. [...] Read more.

The development and approbation of a superconducting local oscillator based on a long Josephson junction made it possible to create a fully superconducting integrated receiver in sub-terahertz frequency range, which was successfully tested both on board a high-altitude balloon and in the laboratory. In order to expand the frequency range of a superconducting integrated local oscillator, it is necessary to ensure the continuous tuning of its frequency at an arbitrary bias current, including a so-called resonant mode regime. The resonant mode regime takes place for high-quality tunnel junctions with low leakage; in this regime, stable generation is possible only at Fiske steps, the distance in frequency between which is tens of GHz. A method for suppressing resonances has been proposed and implemented; this method is based on the introduction of normal metal layers into the region near the long Josephson junction. Modeling of the propagation of electromagnetic waves in the proposed integrated structure was carried out; experimental samples were fabricated, and their comprehensive study was performed. The complete suppression of resonances and the possibility of the continuous tuning of the frequency of a superconducting local oscillator in the range of 200–700 GHz have been demonstrated. The linewidth of the FFO radiation does not exceed 15 MHz over the entire frequency range, which makes it possible to implement the phase locked loop mode in an integrated receiver intended for spectral studies. Full article

(This article belongs to the Special Issue Applied Superconducting Electronics)

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25 pages, 8554 KiB

Open AccessArticle

A Quasi-Velocity-Based Tracking Controller for a Class of Underactuated Marine Vehicles

by Przemyslaw Herman

Appl. Sci. 2022, 12(17), 8903; https://doi.org/10.3390/app12178903 - 05 Sep 2022

Cited by 2 | Viewed by 1135

Abstract

This paper investigates the trajectory tracking control problem for underactuated underwater vehicles, for which a model is expressed in terms of quasi-velocities arising from the inertia matrix decomposition. The control approach takes into account non-modeled dynamics and external disturbances and is suitable for [...] Read more.

This paper investigates the trajectory tracking control problem for underactuated underwater vehicles, for which a model is expressed in terms of quasi-velocities arising from the inertia matrix decomposition. The control approach takes into account non-modeled dynamics and external disturbances and is suitable for symmetric vehicles. It is shown that such systems can be diagonalized using inertial quasi-velocities (IQVs). The strategy consists of the velocity controller and two adaptive integral sliding mode control algorithms. The proposed approach, introducing velocity transformation and using backstepping methods and integral sliding mode control, allows trajectory tracking for vehicles in described models with symmetric inertia matrix. Proof of the stability of the closed system was carried out using IQV. The proposed scheme has been verified on two 3 DOF models of underwater vehicles with thruster limitations. A brief discussion of the results is also given. Full article

(This article belongs to the Special Issue New Trends in Robotics, Automation and Mechatronics (RAM))

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25 pages, 2684 KiB

Open AccessArticle

Anomaly Detection Paradigm for Multivariate Time Series Data Mining for Healthcare

by Abdul Razaque, Marzhan Abenova, Munif Alotaibi, Bandar Alotaibi, Hamoud Alshammari, Salim Hariri and Aziz Alotaibi

Appl. Sci. 2022, 12(17), 8902; https://doi.org/10.3390/app12178902 - 05 Sep 2022

Cited by 6 | Viewed by 3116

Abstract

Time series data are significant, and are derived from temporal data, which involve real numbers representing values collected regularly over time. Time series have a great impact on many types of data. However, time series have anomalies. We introduce an anomaly detection paradigm [...] Read more.

Time series data are significant, and are derived from temporal data, which involve real numbers representing values collected regularly over time. Time series have a great impact on many types of data. However, time series have anomalies. We introduce an anomaly detection paradigm called novel matrix profile (NMP) to solve the all-pairs similarity search problem for time series data in the healthcare. The proposed paradigm inherits the features from two state-of-the-art algorithms: Scalable Time series Anytime Matrix Profile (STAMP) and Scalable Time-series Ordered-search Matrix Profile (STOMP). The proposed NMP caches the output in an easy-to-access fashion for single- and multidimensional data. The proposed NMP can be used on large multivariate data sets and generates approximate solutions of high quality in a reasonable time. It is implemented on a Python platform. To determine its effectiveness, it is compared with the state-of-the-art matrix profile algorithms, i.e., STAMP and STOMP. The results confirm that the proposed NMP provides higher accuracy than the compared algorithms. Full article

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12 pages, 2606 KiB

Open AccessArticle

Using a Pair of Different-Sized Spheres to Calibrate Radar Data in the Microwave Anechoic Chamber

by Jiangkun Gong, Jun Yan, Deren Li, Huiping Hu and Deyong Kong

Appl. Sci. 2022, 12(17), 8901; https://doi.org/10.3390/app12178901 - 05 Sep 2022

Viewed by 1490

Abstract

Traditional radar calibration methods often use one standard sphere as the standard calibration object, but researchers seldom discuss the size and the material content of the calibration sphere. We propose using a pair of different-sized spheres to verify the standard method. In a [...] Read more.

Traditional radar calibration methods often use one standard sphere as the standard calibration object, but researchers seldom discuss the size and the material content of the calibration sphere. We propose using a pair of different-sized spheres to verify the standard method. In a microwave anechoic chamber, the simulated and measured results show that the radar cross-section (RCS) values of two spheres with radii of 0.15 m and 0.05 m in the Mie region differ from their physical cross-sections in the optic region, and only in the optic region, their difference of RCS value (i.e., 9.5424 dB) can be approximately equal to the theoretical one (i.e., 9.6803 dB). Thus, radar calibration should be conducted in the same scattering region for both the calibration object and the calibrated target. The use of two different-sized spheres can aid in three applications: (1) verifying the scattering regions, (2) searching the pure area in the microwave anechoic chamber, and (3) locating the positions of the targets in the range profiles. Full article

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8 pages, 1398 KiB

Open AccessArticle

Evaluation of Body Posture during Class II Functional Treatment with Fränkel II: A Longitudinal Study

by Francesco Caroccia, Chiara Lopes, Rossana Pipitone, Gianmaria D’Addazio, Francesco Moscagiuri and Michele D’Attilio

Appl. Sci. 2022, 12(17), 8900; https://doi.org/10.3390/app12178900 - 05 Sep 2022

Viewed by 1694

Abstract

The aim of the current study was to evaluate the changes in body posture in pubertal subjects characterized by Skeletal Class II with mandibular retrusion pre- and post-Fränkel II (FR-2). The treatment of Skeletal Class II with functional therapy has been already correlated [...] Read more.

The aim of the current study was to evaluate the changes in body posture in pubertal subjects characterized by Skeletal Class II with mandibular retrusion pre- and post-Fränkel II (FR-2). The treatment of Skeletal Class II with functional therapy has been already correlated with changes in cervical posture, but no previous studies investigated the possible relation with the posture of the whole body. This is an observational longitudinal study conducted on 17 Caucasian subjects (6 males, 11 female) with average age 10.7 ± 3.5. Posturostabilometric evaluation was performed before the beginning of the orthodontic treatment (t0), after 12 ± 2 months (t1) and after 24 ± 3 months at the end of the treatment with FR-2 (t2). The following stabilometric parameters were extracted: weight distribution (WD), bar torsion angle (BTA), and barycenter (Xmm). Both WD (p = 0.0154) and BTA (p = 0.0003) showed a significant improvement during the treatment with Friedman test and ANOVA test, respectively, showing how the overall balance and weight distribution of the body can benefit from a functional therapy with jaw advancement. The posturostabilometric platform can be considered a functional indicator of therapy effectiveness because it shows the improving trend of the parameters. Future research is needed, based on the promising results obtained in the current study. Full article

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

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19 pages, 4586 KiB

Open AccessArticle

Acoustic Propagation Characteristics of Unsaturated Porous Media Containing CO₂ and Oil

by Yujuan Qi, Xiumei Zhang and Lin Liu

Appl. Sci. 2022, 12(17), 8899; https://doi.org/10.3390/app12178899 - 05 Sep 2022

Viewed by 1260

Abstract

Carbon dioxide geological utilization and storage (CGUS) is an effective way to mitigate climate warming. In this paper, we resorted to Lo’s model to analyze the dispersion and attenuation characteristics of unsaturated porous media. Based on this, we analyzed the sensitivity of the [...] Read more.

Carbon dioxide geological utilization and storage (CGUS) is an effective way to mitigate climate warming. In this paper, we resorted to Lo’s model to analyze the dispersion and attenuation characteristics of unsaturated porous media. Based on this, we analyzed the sensitivity of the first compressional wave (P1) and the shear wave (S) to various physical parameters. In addition, the modified models of live oil’s velocity and density were proposed, which were verified by experimental data under the consideration of CO₂ dissolution. It is shown that the velocities and attenuations of P1 and S waves are influenced by various parameters, especially CO₂ saturation and pore fluid parameters, such as density and velocity. In particular, with increasing CO₂ saturation, the sensitivity of P1 velocity decreases, while that of the S velocity increases. Better monitoring results can be achieved by combining P1 and S waves. Finally, the acoustic response was analyzed under the modified model. With the increase in CO₂ saturation, the P1 velocity decreases, while the S velocity becomes almost constant and then linearly increases, with the trend changing at the critical saturation. The study provides a more precise basis for monitoring the security of CO₂ injection in CGUS. Full article

(This article belongs to the Topic Carbon Capture, Storage and Utilisation Technologies (CCS/CCU))

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22 pages, 1693 KiB

Open AccessReview

Arabic Automatic Speech Recognition: A Systematic Literature Review

by Amira Dhouib, Achraf Othman, Oussama El Ghoul, Mohamed Koutheair Khribi and Aisha Al Sinani

Appl. Sci. 2022, 12(17), 8898; https://doi.org/10.3390/app12178898 - 05 Sep 2022

Cited by 12 | Viewed by 5911

Abstract

Automatic Speech Recognition (ASR), also known as Speech-To-Text (STT) or computer speech recognition, has been an active field of research recently. This study aims to chart this field by performing a Systematic Literature Review (SLR) to give insight into the ASR studies proposed, [...] Read more.

Automatic Speech Recognition (ASR), also known as Speech-To-Text (STT) or computer speech recognition, has been an active field of research recently. This study aims to chart this field by performing a Systematic Literature Review (SLR) to give insight into the ASR studies proposed, especially for the Arabic language. The purpose is to highlight the trends of research about Arabic ASR and guide researchers with the most significant studies published over ten years from 2011 to 2021. This SLR attempts to tackle seven specific research questions related to the toolkits used for developing and evaluating Arabic ASR, the supported type of the Arabic language, the used feature extraction/classification techniques, the type of speech recognition, the performance of Arabic ASR, the existing gaps facing researchers, along with some future research. Across five databases, 38 studies met our defined inclusion criteria. Our results showed different open-source toolkits to support Arabic speech recognition. The most prominent ones were KALDI, HTK, then CMU Sphinx toolkits. A total of 89.47% of the retained studies cover modern standard Arabic, whereas 26.32% of them were dedicated to different dialects of Arabic. MFCC and HMM were presented as the most used feature extraction and classification techniques, respectively: 63% of the papers were based on MFCC and 21% were based on HMM. The review also shows that the performance of Arabic ASR systems depends mainly on different criteria related to the availability of resources, the techniques used for acoustic modeling, and the used datasets. Full article

(This article belongs to the Special Issue Automatic Speech Recognition)

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2 pages, 199 KiB

Open AccessEditorial

Special Issue on Applied Engineering to Lean Manufacturing and Production Systems 2020

by Jorge Luis García-Alcaraz and Cuauhtémoc Sánchez Ramírez

Appl. Sci. 2022, 12(17), 8897; https://doi.org/10.3390/app12178897 - 05 Sep 2022

Cited by 1 | Viewed by 1013

Abstract

At the end of 2018, a call for papers was made for the Special Issue called “Applied Engineering to Lean Manufacturing Production Systems”, whose objective was to bring together different articles with industrial applications of the different lean manufacturing (LM) tool theories for [...] Read more.

At the end of 2018, a call for papers was made for the Special Issue called “Applied Engineering to Lean Manufacturing Production Systems”, whose objective was to bring together different articles with industrial applications of the different lean manufacturing (LM) tool theories for problem-solving and case studies that improve the indices of the production systems [...] Full article

(This article belongs to the Special Issue Applied Engineering to Lean Manufacturing and Production Systems 2020)

23 pages, 8751 KiB

Open AccessArticle

Simulation Study of the Capture and Purification Performance of Exhaust Fume Systems in Chinese Commercial Kitchens—Case Study in Tianjin

by Awen Zhang, Na Deng, Zhengwei Long, Ruisen Hao, Changyu Shen and Guoqing Cao

Appl. Sci. 2022, 12(17), 8896; https://doi.org/10.3390/app12178896 - 05 Sep 2022

Viewed by 1515

Abstract

A Chinese commercial kitchen fume exhaust (CCKEF) system mainly consists of a wall-mounted canopy hood, air duct and terminal electrostatic purifiers, the capture and purification performance of which should be guaranteed to obtain satisfactory indoor and outdoor air environment in engineering applications. However, [...] Read more.

A Chinese commercial kitchen fume exhaust (CCKEF) system mainly consists of a wall-mounted canopy hood, air duct and terminal electrostatic purifiers, the capture and purification performance of which should be guaranteed to obtain satisfactory indoor and outdoor air environment in engineering applications. However, few studies have focused on the operation performance of CCKEF systems. This study was aimed at providing a simulation method to investigate the operation performance of such systems. The simulation model of a representative CCKEF system was established using CFD software and validated with measured temperature, air velocity and purification efficiency with a deviation within 10%. The validated model was used to predict the indoor air environment and purification efficiency of the CCKEF system under different working conditions. The results showed that the temperature of transfer air from adjacent rooms had a greater impact on the thermal environment of the cooking area than the surface temperature of stoves. The exhaust air volume had a significant influence on both the indoor air environment and purification efficiency. CCKEF system was suggested to be operated at the optimum airflow according to the simultaneous coefficient of stoves as the energy consumption of the system can be saved by 3.75%. Full article

(This article belongs to the Section Applied Thermal Engineering)

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14 pages, 4543 KiB

Open AccessArticle

Generation of High-Density Pulsed Gas–Liquid Discharge Plasma Using Floating Electrode Configuration at Atmospheric Pressure

by Shuqi Li, Yunhu Liu, Hao Yuan, Jianping Liang, Min Zhang, Yao Li and Dezheng Yang

Appl. Sci. 2022, 12(17), 8895; https://doi.org/10.3390/app12178895 - 05 Sep 2022

Cited by 3 | Viewed by 1569

Abstract

In this paper, a high-density gas–liquid discharge plasma is obtained combined with nanosecond pulse voltage and a floating electrode. The discharge images, the waveforms of pulse voltage and discharge current, and the optical emission spectra are recorded. Gas temperature and electron density are [...] Read more.

In this paper, a high-density gas–liquid discharge plasma is obtained combined with nanosecond pulse voltage and a floating electrode. The discharge images, the waveforms of pulse voltage and discharge current, and the optical emission spectra are recorded. Gas temperature and electron density are calculated by the optical emission spectra of N₂ (C³Π_u → B³Π_g) and the Stark broadening of H_α, respectively. The emission intensities of N₂ (C³Π_u → B³Π_g),

N_{2}^{+}

(B²Σ → X²Π), OH (A²Σ → X²Π), O (3p⁵P → 3s⁵S⁰), He (3d³D → 3p³

P_{2}^{0}

), gas temperature, and electron density are acquired by optical emission spectra to discuss plasma characteristics varying with spatial distribution, discharge gap, and gas flow rate. The spatial distributions of discharge characteristics, including gas temperature, electron density, and emission intensities of N₂ (C³Π_u → B³Π_g),

N_{2}^{+}

(B²Σ → X²Π), OH (A²Σ → X²Π), O (3p⁵P → 3s⁵S⁰), and He (3d³D → 3p³

P_{2}^{0}

), are presented. It is found that a high-density discharge plasma with the electron density of 2.2 × 10¹⁵ cm⁻³ and low gas temperature close to room temperature is generated. While setting the discharge gap distance at 10 mm, the discharge area over liquid surface has the largest diameter of 20 mm; under the same conditions, electron density is in the order of 10¹⁵ cm⁻³, and gas temperature is approximately 330 K. In addition, the discharge plasma characteristics are not kept consistent in the axial direction, in which the emission intensities of

N_{2}^{+}

(B²Σ → X²Π), N₂ (C³Π_u → B³Π_g), OH (A²Σ → X²Π), and gas temperature increased near the liquid surface. As the discharge gap is enlarged, the gas temperature increases, whereas the electron density remains almost constant. Moreover, as the gas flow rate was turned up, the electron density increased and the gas temperature was kept constant at 320 K. Full article

(This article belongs to the Special Issue Plasma Technology and Its Applications)

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