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Appl. Sci., Volume 13, Issue 5 (March-1 2023) – 623 articles

Cover Story (view full-size image): Eating is considered as one of the most important activities of daily living (ADL). However, with the aging population and the rapid spread of chronic diseases, many patients require assistance from family members or professional caregivers to eat. As a result, various types of meal assistance robots (MAR) have been developed and introduced to address this issue. In this study, we propose a MAR system suitable for an Asian diet, which includes dishes that are easy to handle with chopsticks and soup. The system comprises an eating utensil that can alternate chopsticks and spoons and a food acquisition point estimator that recognizes the food area from the plate image and calculates the best location to acquire each dish. Additionally, we have developed a contactless user interface based on facial recognition to accommodate users with physical limitations. View this paper
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15 pages, 4092 KiB  
Article
Rhodospirillum rubrum L-Asparaginase Conjugates with Polyamines of Improved Biocatalytic Properties as a New Promising Drug for the Treatment of Leukemia
by Natalia V. Dobryakova, Dmitry D. Zhdanov, Nikolay N. Sokolov, Svetlana S. Aleksandrova, Marina V. Pokrovskaya and Elena V. Kudryashova
Appl. Sci. 2023, 13(5), 3373; https://doi.org/10.3390/app13053373 - 6 Mar 2023
Cited by 6 | Viewed by 2333
Abstract
L-asparaginase Rhodospirillum rubrum (RrA) is an enzyme (amidohydrolases; EC 3.5.1.1) that catalyzes the L-asparagine hydrolysis reaction to form L-aspartic acid. Due to the shortcomings of existing L-asparaginases from Esherichia coli (EcA) and Erwinia chrysanthemi (ErA), RrA may turn out to be a new [...] Read more.
L-asparaginase Rhodospirillum rubrum (RrA) is an enzyme (amidohydrolases; EC 3.5.1.1) that catalyzes the L-asparagine hydrolysis reaction to form L-aspartic acid. Due to the shortcomings of existing L-asparaginases from Esherichia coli (EcA) and Erwinia chrysanthemi (ErA), RrA may turn out to be a new promising drug for the treatment of leukemia. RrA has a low homology with EcA and ErA, which makes the enzyme potentially less immunogenic. RrA has pronounced antitumor activity on a number of leukemia cells. However, there is a need to improve the biocatalytic properties of the enzyme. So, in this study, the RrA conjugates with polyamines with different molecular architectures were developed to regulate the catalytic properties of the enzyme. Linear polyethyleneimine (PEI), branched polyethyleneimine, modified with polyethylene glycol (PEI-PEG), and spermine (Spm) were used to obtain conjugates with RrA. It was discovered by gel permeation chromatography that Spm allows the most active tetrameric form of RrA to be obtained and stabilized. Molecular docking was used to study the binding of spermine to RrA subunits. The activity of the RrA conjugates with Spm and PEI-PEG was 23–30% higher than the native enzyme. The pH optimum of the conjugates shifted from 9.0 to 8.5. The conjugates had higher stability: Spm and PEI-PEG reduced the inactivation constant (kin) more than two-fold upon incubation at 53 °C. The conjugate RrA-PEI-PEG reduced the accessibility of trypsin to the protein surface and reduced kin by eight times. The modification of RrA with polyamines made it possible to obtain enzyme preparations with improved biocatalytic properties. These conjugates represent interest for further study as potential therapeutic agents. Full article
(This article belongs to the Special Issue Functional Polymers: Synthesis, Properties and Applications)
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<p>The reaction scheme of RrA with Woodward’s reagent, polyamines, and resulting conjugates with polyamines.</p> Full article ">Figure 2
<p>Chromatograms obtained by gel filtration: (<b>a</b>) solutions of RrA and conjugate, RrA-PEI-PEG; (<b>b</b>) native RrA and conjugate, RrA-Spm. Protein concentration of the samples is 1 mg/mL; C(PEI-PEG) = 5 mg/mL.</p> Full article ">Figure 3
<p>IR spectra of the native enzyme compared with conjugates: (<b>a</b>) RrA-PEI-PEG; (<b>b</b>) RrA-Spm; (<b>c</b>) RrA-PEI. The concentration of RrA was 1 mg/mL, PEI-PEG was 1 mg/mL, Spm was 0.5 mg/mL, and PEI was 0.1 mg/mL. Conditions: PBS 10 mM, 22 °C.</p> Full article ">Figure 4
<p>CD spectra of the native enzyme and RrA-PEI-PEG, RrA-PEI, and RrA-Spm conjugates. C(RrA) = 1 mg/mL, 0,01 M PBS, 37 °C, pH 7.5.</p> Full article ">Figure 5
<p>Results of docking: (<b>a</b>) dimer RrA with spermine and L-Asparagine; (<b>b</b>) tetramer RrA with spermine and L-Asparagine. Structure of L-asparaginase <span class="html-italic">Rhodospirillum rubrum</span> imported from website <a href="https://www.uniprot.org" target="_blank">https://www.uniprot.org</a> (Q2RMX1, accessed on 9 December 2022). Asp and Glu residues are highlighted in yellow, spermine molecules are highlighted in lilac, substrate L-asparagine is highlighted in green (atomic balls), and residues included in the enzyme active center are highlighted in red.</p> Full article ">Figure 6
<p>pH dependence of activity for native RrA and its conjugates: 5 mM citrate phosphate–borate buffer, 37 °C.</p> Full article ">Figure 7
<p>(<b>a</b>) Thermal inactivation curves of the residual activity of native RrA and its conjugates after incubation at 53 °C for 60 min; (<b>b</b>) semilogarithmic time dependencies. The concentration of the enzyme for all samples was 1 mg/mL. A is the specific activity of the enzyme at time t, and A<sub>0</sub> is at t = 0.</p> Full article ">Figure 8
<p>Trypsinolysis curves (<b>a</b>) and semi-log dependences (<b>b</b>) of the residual activity of native RrA and its conjugates on the incubation time at 37 °C. The concentration of L-asparaginase in the samples was 1 mg/mL; the concentration of trypsin was 0.0025 mg/mL; PBS pH 7.5.</p> Full article ">
13 pages, 40176 KiB  
Article
On Pseudorandomness and Deep Learning: A Case Study
by Zahra Ebadi Ansaroudi, Rocco Zaccagnino and Paolo D’Arco
Appl. Sci. 2023, 13(5), 3372; https://doi.org/10.3390/app13053372 - 6 Mar 2023
Viewed by 1833
Abstract
Pseudorandomness is a crucial property that the designers of cryptographic primitives aim to achieve. It is also a key requirement in the calls for proposals of new primitives, as in the case of block ciphers. Therefore, the assessment of the property is an [...] Read more.
Pseudorandomness is a crucial property that the designers of cryptographic primitives aim to achieve. It is also a key requirement in the calls for proposals of new primitives, as in the case of block ciphers. Therefore, the assessment of the property is an important issue to deal with. Currently, an interesting research line is the understanding of how powerful machine learning methods are in distinguishing pseudorandom objects from truly random objects. Moving along such a research line, in this paper a deep learning-based pseudorandom distinguisher is developed and trained for two well-known lightweight ciphers, Speck and Simon. Specifically, the distinguisher exploits a convolutional Siamese network for distinguishing the outputs of these ciphers from random sequences. Experiments with different instances of Speck and Simon show that the proposed distinguisher highly able to distinguish between the two types of sequences, with an average accuracy of 99.5% for Speck and 99.6% for Simon. Hence, the proposed method could significantly impact the security of these cryptographic primitives and of the applications in which they are used. Full article
(This article belongs to the Special Issue Women in Cryptography)
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<p>A simple Siamese neural network architecture.</p> Full article ">Figure 2
<p>Our convolutional Siamese neural network architecture.</p> Full article ">Figure 3
<p>One-shot training and validation accuracy over epochs, for <tt>Speck</tt>, with a binary cross entropy loss. (<b>a</b>) With 200 samples, test accuracy <math display="inline"><semantics> <mrow> <mn>83</mn> <mo>%</mo> </mrow> </semantics></math>. (<b>b</b>) With 300 samples, test accuracy <math display="inline"><semantics> <mrow> <mn>91</mn> <mo>%</mo> </mrow> </semantics></math>.</p> Full article ">Figure 4
<p>One-shot training and validation accuracy over epochs, for <tt>Speck</tt>, with a contrastive loss, given the evaluation accuracy of <math display="inline"><semantics> <mrow> <mn>100</mn> <mo>%</mo> </mrow> </semantics></math>.</p> Full article ">Figure A1
<p>Speck round function.</p> Full article ">Figure A2
<p>Simon round function.</p> Full article ">
16 pages, 2912 KiB  
Article
Effect of Protective Coatings on Wooden Elements Exposed to a Small Ignition Initiator
by Stanislava Gašpercová, Iveta Marková, Miroslava Vandlíčková, Linda Makovická Osvaldová and Jozef Svetlík
Appl. Sci. 2023, 13(5), 3371; https://doi.org/10.3390/app13053371 - 6 Mar 2023
Cited by 5 | Viewed by 1762
Abstract
This paper presents the results of monitoring the behaviour of selected wood species exposed to a small ignition initiator. We specifically aimed to investigate the effect of retardant coating on the combustion process of the wood species spruce (Picea abies), red [...] Read more.
This paper presents the results of monitoring the behaviour of selected wood species exposed to a small ignition initiator. We specifically aimed to investigate the effect of retardant coating on the combustion process of the wood species spruce (Picea abies), red spruce (Larix decidua), Scots pine (Pinus sylvestris), ash (Fraxinus excelsior L.), beech (Fagus sylvatica), and oak (Quercus robur) when exposed to a small initiator of ignition. At the same time, we studied the effect of different types of fungicidal agents (based on N-(3-aminopropyl)-N-dodecylpropane-1,3-diamine; alkyl (C12–16) dimethylbenzyl ammonium chloride or 3-iodo-prop-2-inylbutylcarbamate) on the effectiveness of a flame retardant (containing ferric phosphate) applied to the selected fungicide-treated wood samples. The experimentally obtained mass-loss and flame-spread results were statistically evaluated using the QtiPlot software program. A significant dependence of mass loss and surface flame spread on wood species was the primary focus. It was only confirmed for the surface-flame-spread variable. The dependence of the effect of fungicide treatment on the effectiveness of the selected retardant was confirmed. Fungicidal coatings with the active ingredient alkyl/benzyl (C12–16) dimethylbenzyl ammonium chloride indicated the lowest mass loss rate and flame spread for all wood samples. Full article
(This article belongs to the Special Issue Application of Wood Composites III)
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<p>Oak sample in the process of applying protective coatings.</p> Full article ">Figure 2
<p>(<b>a</b>) Test chamber according to STN EN ISO 11925-2 [<a href="#B66-applsci-13-03371" class="html-bibr">66</a>]; (<b>b</b>) scheme of small flame test, EN ISO 11925-2 (sample size 0.09 × 0.25 m<sup>2</sup>) [<a href="#B62-applsci-13-03371" class="html-bibr">62</a>,<a href="#B66-applsci-13-03371" class="html-bibr">66</a>]; (<b>c</b>) demonstration of the experiment on a sample of SMR + HRP (retardant) in 30 s.</p> Full article ">Figure 3
<p>(<b>a</b>) Prepared experiment; (<b>b</b>) experiment at 10 s; (<b>c</b>) close-up of flame–sample contact at 20 s.</p> Full article ">Figure 4
<p>Dependence of mass change after application of a small flame initiator for 30 s and comparison of flame height for each wood sample.</p> Full article ">Figure 5
<p>Presentation of wood samples after the experiment. The order of wood species is sorted from left to right as follows: 1 row—SM (spruce) and SMR (red spruce); 2 row—JAS (ash) and BOR (pine); 3 row—DUB (oak) and BUK (beech).</p> Full article ">Figure 6
<p>Boxplot of the variance of mass loss for individual fungicide coatings. Legend: UN—untreated with fungicide coating, 2—untreated with fungicide coating, 3—Fun (red), 4—Boch Fun (green), 5—Boch (dark blue), 6—Nap (light blue), 7—Aqua (violet).</p> Full article ">Figure 7
<p>Mass loss obtained by small flame test and comparison of flame spreads in 30 s.</p> Full article ">Figure 8
<p>Boxplot to compare the flame spread for each fungicide coating. Legend: UN—untreated with fungicide coating, 2—untreated with fungicide coating, 3—Fun (red), 4—Boch Fun (green), 5—Boch (dark blue), 6—Nap (light blue), 7—Aqua (violet).</p> Full article ">
12 pages, 2287 KiB  
Article
Performance of Automated Oral Cancer Screening Algorithm in Tobacco Users vs. Non-Tobacco Users
by Susan Meishan Yang, Bofan Song, Cherie Wink, Mary Abouakl, Thair Takesh, Michelle Hurlbutt, Dana Dinica, Amber Davis, Rongguang Liang and Petra Wilder-Smith
Appl. Sci. 2023, 13(5), 3370; https://doi.org/10.3390/app13053370 - 6 Mar 2023
Cited by 3 | Viewed by 2772
Abstract
Oral non-neoplastic and neoplastic lesions have similar clinical manifestations, increasing the risk of inaccurate screening decisions that adversely affect oral cancer (OC) outcomes. Tobacco-use-related changes in the oral soft tissues may affect the accuracy of “smart” oral screening modalities. Because smoking is such [...] Read more.
Oral non-neoplastic and neoplastic lesions have similar clinical manifestations, increasing the risk of inaccurate screening decisions that adversely affect oral cancer (OC) outcomes. Tobacco-use-related changes in the oral soft tissues may affect the accuracy of “smart” oral screening modalities. Because smoking is such a strong predictor of OC risk, it may overwhelm the impact of other variables on algorithm performance. The objective was to evaluate the screening accuracy in tobacco users vs. non-users of a previously developed prototype smartphone and machine-learning algorithm-based oral health screening modality. 318 subjects with healthy mucosa or oral lesions were allocated into either a “tobacco smoker” group or a “tobacco non-smoker” group. Next, intraoral autofluorescence (AFI) and polarized white light images (pWLI), risk factors as well as clinical signs and symptoms were recorded using the prototype screening platform. OC risk status as determined by the algorithm was compared with OC risk evaluation by an oral medicine specialist (gold standard). The screening platform achieved 80.0% sensitivity, 87.5% specificity, 83.67% agreement with specialist screening outcome in tobacco smokers, and 62.1% sensitivity, 82.9% specificity, 73.1% agreement with specialist screening outcome in non-smokers. Tobacco use should be carefully weighted as a variable in the architecture of any imaging-based screening algorithm for OC risk. Full article
(This article belongs to the Special Issue Artificial Intelligence Applied to Dentistry)
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<p>Flow diagram of the protocol.</p> Full article ">Figure 2
<p>Handheld intraoral scanner pen system designed and constructed by our team: (<b>a</b>) scanner pen with extended reach to improve intraoral access, (<b>b</b>) flexible tip permitting imaging access to all intraoral sites, including base of tongue and tonsillar region.</p> Full article ">Figure 3
<p>Non-specialist use of oral cancer screening platform in community setting.</p> Full article ">Figure 4
<p>Erythematous anterior tonsillar pillar in (<b>i</b>) smoker (left image pair), (<b>ii</b>) non-smoker (right image pair). Left side of each image pair (<b>a</b>): polarized white light image; Right side of each image pair (<b>b</b>): autofluorescence image. In the polarized white light image of smoker’s tissues (left image pair, left side (<b>i</b>(<b>a</b>)), note the thick, scaly hyperkeratinized surface layer, which exhibits strong backscattering in the autofluorescence image (left image pair, right side (<b>i</b>(<b>b</b>)) vs. the non-smoker’s tissues (right image pair (<b>ii</b>(<b>a</b>) and <b>ii</b>(<b>b</b>)).</p> Full article ">Figure 5
<p>Papillary hyperplasia in (<b>i</b>) smoker (left image pair), (<b>ii</b>) non-smoker (right image pair). Left side of each image pair (<b>a</b>): polarized white light image; right side of each image pair (<b>b</b>): autofluorescence image. In the polarized white light image of the smoker’s tissues (left image pair, left side (<b>i</b>(<b>a</b>)), note the thick, dry, red, fibrosed surface layer in the smoker’s tissues which shows considerably more backscattering in the autofluorescence image (left image pair, right side (<b>i</b>(<b>b</b>)) vs. the non-smoker’s tissues (right image pair (<b>ii</b>(<b>a</b>) and <b>ii</b>(<b>b</b>)).</p> Full article ">
14 pages, 2079 KiB  
Article
Antibacterial Activity of Tanacetum vulgare L. Extracts against Clinical Isolates of Bovine Mastitis
by Renāte Šukele, Ance Bārzdiņa, Rudīte Koka, Ingus Skadins, Līga Lauberte, Agnese Brangule, Liga Kovalcuka and Dace Bandere
Appl. Sci. 2023, 13(5), 3369; https://doi.org/10.3390/app13053369 - 6 Mar 2023
Cited by 5 | Viewed by 2483
Abstract
A bovine mastitis is an infectious disease, which is usually treated with antibiotics. Alternatively, herbal medicine has been proposed due to bacterial resistance. The aim of this study was to determine the antibacterial activity of the acetonic and ethanolic extracts of dried flowers [...] Read more.
A bovine mastitis is an infectious disease, which is usually treated with antibiotics. Alternatively, herbal medicine has been proposed due to bacterial resistance. The aim of this study was to determine the antibacterial activity of the acetonic and ethanolic extracts of dried flowers and leaves of Tanacetum vulgare L. against bovine mastitis-inducing clinical isolates such as Escherichia coli, Streptococcus agalactiae, Streptococcus uberis, Serratia liquefaciens, Staphylococcus aureus, and reference cultures of S. aureus and E. coli. The extracts of T. vulgare showed partial antibacterial activity against tested strains of S. aureus. The MIC and MBC values of a 70% ethanol extract of flowers (MIC = 3.4 mg/mL, MBC = 3.4–6.8 mg/mL) were lower than for the 70% ethanol extract of leaves (MIC = 15.7–31.4 mg/mL, MBC = 62.9–125.9 mg/mL). The flower extracts showed low activity against E. coli (MIC = 53.9 mg/mL, MBC = 53.9–107.8 mg/mL) and S. agalactiae (MIC, MBC = 53.9 mg/mL). T. vulgare leaf extracts had minimal antibacterial effects against Streptococcus strains (MIC = 31.4–62.9 mg/mL, MBC = 53.9–125.9 mg/mL) and Serratia liquefaciens (MIC, MBC = 125.9 mg/mL). However, flower extracts had a higher phenolic content that did not correlate with antibacterial effects. T. vulgare flower and leaf extracts could be combined to obtain broader antibacterial effects. Full article
(This article belongs to the Special Issue Antibacterial Activity of Plant Extracts)
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<p>Plant material extraction process.</p> Full article ">Figure 2
<p>Extract preparation process.</p> Full article ">Figure 3
<p>Antibacterial susceptibility for the bovine mastitis clinical isolates.</p> Full article ">Figure 4
<p>FTIR DRIFT spectra. (<b>A</b>) <span class="html-italic">T. vulgare</span> parts: flowers and leaves; (<b>B</b>) Extract in 70% acetone of <span class="html-italic">T. vulgare</span> parts: flowers and leaves; (<b>C</b>) Extract in 70%, 50%, and 30% ethanol of <span class="html-italic">T. vulgare</span> flowers.</p> Full article ">
19 pages, 3929 KiB  
Article
Combining Statistical, Displacement and Damage Analyses to Study Slow-Moving Landslides Interacting with Roads: Two Case Studies in Southern Italy
by Gaetano Pecoraro, Gianfranco Nicodemo, Rosa Menichini, Davide Luongo, Dario Peduto and Michele Calvello
Appl. Sci. 2023, 13(5), 3368; https://doi.org/10.3390/app13053368 - 6 Mar 2023
Cited by 5 | Viewed by 1809
Abstract
Slow-moving landslides are widespread natural hazards that can affect social and economic activities, causing damage to structures and infrastructures. This paper aims at proposing a procedure to analyze road damage induced by slow-moving landslides based on the joint use of landslide susceptibility maps, [...] Read more.
Slow-moving landslides are widespread natural hazards that can affect social and economic activities, causing damage to structures and infrastructures. This paper aims at proposing a procedure to analyze road damage induced by slow-moving landslides based on the joint use of landslide susceptibility maps, a road-damage database developed using Google Street View images and ground-displacement measurements derived from the interferometric processing of satellite SAR images. The procedure is applied to the municipalities of Vaglio Basilicata and Trivigno in the Basilicata region (southern Italy) following a matrix-based approach. First, a susceptibility analysis is carried out at the municipal scale, using data from landslide inventories and thematic information available over the entire municipalities. Then, the susceptibility index, the class of movement and the level of damage are calculated for the territorial units corresponding to the road corridors under investigation. Finally, the road networks are divided into stretches, each one characterized by a specific level of risk (or attention required) following the aggregation of the information provided by the performed analyses. The results highlight the importance of integrating all of these different approaches and data for obtaining quantitative information on the spatial and temporal behavior of slow-moving landslides affecting road networks. Full article
(This article belongs to the Special Issue New Frontiers in Natural Hazards and New Techniques)
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<p>Procedure to study the interaction between slow-moving landslides and the road network at the municipal level by combining information from susceptibility maps, DInSAR data analyses and damage surveys.</p> Full article ">Figure 2
<p>Aerial photos of Vaglio Basilicata (<b>a</b>,<b>c</b>) and Trivigno (<b>b</b>,<b>d</b>). (<b>a</b>,<b>c</b>) show the slow-moving landslides inventoried by the Interregional River Basin Authority of Basilicata and the spatial distribution of DInSAR velocities (road sections surveyed are marked in black) within the two municipalities. (<b>b</b>,<b>d</b>) focus on the main road stretches connecting highway SS407 Basentana to the two city centers. The insets show the location of the two municipalities within the Basilicata region.</p> Full article ">Figure 3
<p>Receiver operating characteristic curves for the landslide susceptibility zoning maps obtained applying different focal statistic characteristic dimensions for Vaglio Basilicata (<b>a</b>) and Trivigno (<b>b</b>).</p> Full article ">Figure 4
<p>Landslide susceptibility maps at the municipal scale defined employing focal statistics techniques with characteristic dimension equal to 7. Slow-moving landslides recorded in the two test areas are also reported. The inset shows the location of the two municipalities within the Basilicata region.</p> Full article ">Figure 5
<p>Maps of the slow-moving landslides for Vaglio Basilicata (<b>a</b>) and Trivigno (<b>c</b>) distinguished according to the average DInSAR-derived velocity values with close-up view of yearly V<sub>LOS</sub> of analyzed coherent DInSAR benchmarks and assumed as indicators of a state of movement for the TZU<sub>road</sub> in Vaglio Basilicata (<b>b</b>) and Trivigno (<b>d</b>).</p> Full article ">Figure 6
<p>Maps of damaged road stretches with severity levels resulting from the damage classification using Google Street View imagery dated August 2021 for Vaglio Basilicata (<b>a</b>) and March 2021 for Trivigno (<b>b</b>). Percentages of damaged road distinguished according to the four (D0–D3) damage severity levels are also reported (<b>c</b>).</p> Full article ">Figure 7
<p>Excerpts of maps produced by the procedure in two small portions of the study area in Vaglio Basilicata (<b>a</b>) and Trivigno (<b>b</b>). The tables below report the correlation matrices obtained for the classification carried out over the entire territory of the two study areas.</p> Full article ">Figure 8
<p>Classification of the investigated stretches of roads in different levels of risk and attention resulting from the application of the proposed methodology in two study areas of the municipalities of Vaglio Basilicata (<b>a</b>) and Trivigno (<b>b</b>).</p> Full article ">
43 pages, 2308 KiB  
Review
A Survey of Handover Management in Mobile HetNets: Current Challenges and Future Directions
by Aziz Ur Rehman, Mardeni Bin Roslee and Tiang Jun Jiat
Appl. Sci. 2023, 13(5), 3367; https://doi.org/10.3390/app13053367 - 6 Mar 2023
Cited by 23 | Viewed by 5869
Abstract
With the rapid growth of data traffic and mobile devices, it is imperative to provide reliable and stable services during mobility. Heterogeneous Networks (HetNets) and dense networks have been identified as potential solutions to address the upcoming capacity crunch, but they also pose [...] Read more.
With the rapid growth of data traffic and mobile devices, it is imperative to provide reliable and stable services during mobility. Heterogeneous Networks (HetNets) and dense networks have been identified as potential solutions to address the upcoming capacity crunch, but they also pose significant challenges related to handover optimization. This paper presents a comprehensive review of recent handover decision algorithms in HetNets, categorizing them based on their decision techniques and summarizing their input parameters, techniques, and performance evaluations. Our study highlights the technical challenges and opportunities related to handovers in HetNets and dense cellular networks and provides key findings from recent studies. The significance of this survey is to provide a comprehensive overview of handover decision algorithms in HetNets and dense cellular networks, which can aid in the development of more advanced handover optimization approaches. Full article
(This article belongs to the Section Electrical, Electronics and Communications Engineering)
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<p>Mobile Cellular Generations with their Applications.</p> Full article ">Figure 2
<p>Outline of the Article.</p> Full article ">Figure 3
<p>A simple HetNets scenario.</p> Full article ">Figure 4
<p>HOs scenario in HetNets.</p> Full article ">Figure 5
<p>Handover decision and description of Handover Control Parameters.</p> Full article ">Figure 6
<p>Illustration of Velocity Aware Handovers in HetNets.</p> Full article ">Figure 7
<p>Basic illustration of RSRP based Handovers in HetNets.</p> Full article ">Figure 8
<p>Schemetic Diagram of Fuzzy Logic-based Handovers in HetNets.</p> Full article ">Figure 9
<p>Schemetic Diagram of Metaheuristic-based Handovers in HetNets.</p> Full article ">Figure 10
<p>Schemetic Diagram of Machine Learning/Deep Learning-based Handovers in HetNets.</p> Full article ">Figure 11
<p>A Basic Illustration of Spatial Information-based Handovers in HetNets.</p> Full article ">
14 pages, 1687 KiB  
Article
External Beam IBA Measurements for Cultural Heritage
by Massimo Chiari
Appl. Sci. 2023, 13(5), 3366; https://doi.org/10.3390/app13053366 - 6 Mar 2023
Cited by 7 | Viewed by 1789
Abstract
Ion beam analysis (IBA) methods refer to a set of analytical techniques based on the interactions of energetic ions, produced by a particle accelerator, with matter. The result of such interactions is the emission of characteristic radiation, X and gamma rays, and charged [...] Read more.
Ion beam analysis (IBA) methods refer to a set of analytical techniques based on the interactions of energetic ions, produced by a particle accelerator, with matter. The result of such interactions is the emission of characteristic radiation, X and gamma rays, and charged particles, which, upon detection, provide valuable information on the absolute concentration and depth distribution of the elements in the bombarded material. Moreover, IBA techniques can be performed while maintaining the object to be investigated at atmospheric pressure, without placing it in vacuum, in an analysis chamber, with the impinging ion beam extracted from the in-vacuum beamline of the accelerator, avoiding the need of invasive sampling and greatly easing the object positioning, thus allowing precious and big or large artefacts to be studied. This feature has opened the way for applications of IBA techniques for compositional analysis in cultural heritage studies, providing detailed and complete information about elemental compositions and depth distributions of analysed materials that are otherwise difficult or impossible for other analytical techniques. In this paper, the basic principles of the main IBA techniques applied to cultural heritage, namely, particle induced X-ray emission (PIXE), particle induced Gamma-ray emission (PIGE), and Rutherford or elastic backscattering spectrometry (RBS/EBS), will be recalled, and specific and practical details on how these techniques can be used for analysing cultural heritage objects with external beam set-ups will be provided. Full article
(This article belongs to the Special Issue Non-destructive Techniques for Cultural Heritage Characterization)
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<p>PIXE spectra of an emerald obtained with 3 MeV protons, collected simultaneously with a small area SDD for low-Z elements (Na-Ca) and a large area SDD with 450 mm Mylar foil as absorber for mid- and high-Z elements (Sc-Pb). The spectra are normalised by the proton beam charge accumulated during the measurement.</p> Full article ">Figure 2
<p>Comparison of PIXE spectra of a NIST 1412 glass obtained with 3 MeV protons, collected with a 150 mm<sup>2</sup>, 450 μm thick SDD and with a traditional 80 mm<sup>2</sup>, 5 mm thick Si(Li) detector. The spectra are normalised by the proton beam charge accumulated during the measurements.</p> Full article ">Figure 3
<p>On the left, comparison between PIXE spectra of a tintype at three different proton energies, namely, 2, 3, and 4 MeV; the reported beam energies refer to the effective values at the sample surface, after traversing the beam exit window and about 1 cm path in external atmosphere. The spectra are normalised by the proton beam charge accumulated during the measurements. On the right, the apparent composition ratios of the main metallic elements as a function of the different proton beam energies.</p> Full article ">Figure 4
<p>PIGE spectrum of a topaz obtained with 3 MeV protons, showing gamma-ray lines of F, Na, Al, Mg, and Si. The spectrum is normalised by the proton beam charge accumulated during the measurement.</p> Full article ">Figure 5
<p>Experimental (open squares) and simulated (full line) RBS spectra obtained with 3 MeV protons. On the left, lead-white paint layer covered with about 15 μm thick varnish. On the right, 525 nm thick gold leaf laid on wood by a bole clay. The partial spectra of the detected elements (C, O, Fe, Pb, and Au), and the contribution of He from the helium flowing are shown as dashed lines.</p> Full article ">Figure 6
<p>External beam IBA measurements of a presumed oil gilding on brass with 3 MeV protons. (<b>a</b>) Experimental (red symbols) and simulated (blue line) EBS spectra. (<b>b</b>) Comparison of experimental (red) and fitted (light blue) X-ray peak areas from PIXE, for main and trace elements. (<b>c</b>) Fitted structure of the sample showing the elemental depth distribution.</p> Full article ">Figure 7
<p>RBS spectrum of 2.5 MeV protons backscattered from Si and N in a 500 nm thick silicon nitride extraction window for beam normalization purposes. In the inset, a correlation between the area of the Si RBS peak and the integrated beam charge.</p> Full article ">
24 pages, 5437 KiB  
Article
A Comprehensive Methodology for the Statistical Characterization of Solar Irradiation: Application to the Case of Morocco
by Naoufal Bouhorma, Helena Martín, Jordi de la Hoz and Sergio Coronas
Appl. Sci. 2023, 13(5), 3365; https://doi.org/10.3390/app13053365 - 6 Mar 2023
Cited by 2 | Viewed by 2254
Abstract
The prediction and characterization of solar irradiation relies mostly on either the use of complex models or on complicated mathematical techniques, such as artificial neural network (ANN)-based algorithms. This mathematical complexity might hamper their use by businesses and project developers when assessing the [...] Read more.
The prediction and characterization of solar irradiation relies mostly on either the use of complex models or on complicated mathematical techniques, such as artificial neural network (ANN)-based algorithms. This mathematical complexity might hamper their use by businesses and project developers when assessing the solar resource. In this study, a simple but comprehensive methodology for characterizing the solar resource for a project is presented. It is based on the determination of the best probability distribution function (PDF) of the solar irradiation for a specific location, assuming that the knowledge of statistical techniques may be more widely extended than other more complex mathematical methods. The presented methodology was tested on 23 cities across Morocco, given the high interest in solar investments in the country. As a result, a new database for solar irradiation values depending on historical data is provided for Morocco. The results show the great existing variety of PDFs for the solar irradiation data at the different months and cities, which demonstrates the need for undertaking a proper characterization of the irradiation when the assessment of solar energy projects is involved. When it is simply needed to embed the radiation uncertainty in the analysis, as is the case of the techno-economic valuation of solar energy assets, the presented methodology can reach this objective with much less complexity and less demanding input data. Moreover, its application is not limited to solar resource assessment, but can also be easily used in other fields, such as meteorology and climate change studies. Full article
(This article belongs to the Special Issue Solar Power Technology for Electricity Generation)
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<p>CSP capacity installed in the MENA region. Source: own elaboration based on [<a href="#B3-applsci-13-03365" class="html-bibr">3</a>].</p> Full article ">Figure 2
<p>Characterization of solar irradiation in the scientific literature, dealing with either daily (H), average daily (<math display="inline"><semantics> <mrow> <mover> <mi mathvariant="normal">H</mi> <mo>¯</mo> </mover> </mrow> </semantics></math>), hourly (I) or average hourly (<math display="inline"><semantics> <mrow> <mover> <mi mathvariant="normal">I</mi> <mo>¯</mo> </mover> </mrow> </semantics></math>) global, beam (<sub>b</sub>) and diffuse (<sub>d</sub>) values. Source: own elaboration.</p> Full article ">Figure 3
<p>Flow chart of the proposed methodology. Source: own elaboration.</p> Full article ">Figure 4
<p>Climatic zones of Morocco. Source: own elaboration based on [<a href="#B57-applsci-13-03365" class="html-bibr">57</a>].</p> Full article ">Figure 5
<p>Monthly irradiation values within the analyzed time intervals comparing pairs of databases and linear regression for the validation of data. Source: own elaboration.</p> Full article ">Figure 6
<p>Categorization of the DNI and GHI data according to the month and considered city. Source: own elaboration.</p> Full article ">Figure 7
<p>Step-by-step calculation for distribution fitting. Source: own elaboration.</p> Full article ">Figure 8
<p>Step-by-step calculation of the Anderson–Darling (AD) test. Source: own elaboration.</p> Full article ">Figure 9
<p>Bar chart with the rate of appearance of the PDFs in each month per climatic zone (DNI case). Source: own elaboration.</p> Full article ">Figure 10
<p>Example of the extreme value, normal and kernel PDFs’ fitting test results for the month of October at Nador, December at Kenitra and March at Tetouan (DNI case). Source: own elaboration.</p> Full article ">Figure 11
<p>Bar chart with the rate of appearance of the PDFs in each month per climatic zone (GHI case). Source: own elaboration.</p> Full article ">Figure 12
<p>Examples of the extreme value, normal and kernel PDFs’ fitting test results for the month of February in Ifrane, the month of October in Nador and the month of March in Tetouan (GHI case). Source: own elaboration.</p> Full article ">Figure 13
<p>Basic structure of the Monte Carlo simulation algorithm for testing the PDFs. Source: own elaboration.</p> Full article ">Figure 14
<p>Evolution of the GHI average for October in Rabat according to the number of samples obtained in the Monte Carlo simulation. Source: own elaboration.</p> Full article ">
20 pages, 4377 KiB  
Article
Active Disturbance Rejection Optimization Control for SOFCs in Offshore Wind Power
by Zhixuan Pan, Jia Liu, Jing Liu, Xiaoge Ning, Zheng Qin and Lulu He
Appl. Sci. 2023, 13(5), 3364; https://doi.org/10.3390/app13053364 - 6 Mar 2023
Cited by 1 | Viewed by 1532
Abstract
With the development of offshore wind power (OWP)-based hydrogen production technology, hydrogen fuel cells play a critical role in buffering the mismatch between energy supply and demand in OWP systems. Benefitting from high efficiency, cleanliness, and nontoxicity, solid oxide fuel cells (SOFCs) have [...] Read more.
With the development of offshore wind power (OWP)-based hydrogen production technology, hydrogen fuel cells play a critical role in buffering the mismatch between energy supply and demand in OWP systems. Benefitting from high efficiency, cleanliness, and nontoxicity, solid oxide fuel cells (SOFCs) have been extensively investigated. However, OWP-based SOFC systems are characterized by strong nonlinearity and uncertainty and are vulnerable to disturbance, which leads to appreciable fluctuations and even instability to the system output voltage. Since conventional PID control schemes cannot achieve favorable performance, a more advanced control method is imperative. In response, this paper proposes a linear active disturbance rejection control (LADRC) method to reduce the influence of disturbance and ensure the stability of SOFC systems. In addition, an improved firefly algorithm (IFA) was adopted to optimize LADRC parameters. A step inertia weight was introduced, and a random generation mechanism was adopted to replace 30% of individuals with low luminous degrees. Using optimized LADRC parameters, a series of Monte Carlo experiments were carried out to verify the system’s robustness. The experimental results show that the overshoot of the LADRC method optimized by the IFA can be reduced by 5.7% compared with the traditional PID controller, i.e., the influence of the voltage disturbance can be well suppressed. Full article
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<p>Block diagram of offshore wind SOFC system structure.</p> Full article ">Figure 2
<p>Partial model block diagram of SOFC system.</p> Full article ">Figure 3
<p>Block diagram of second-order LADRC controller structure.</p> Full article ">Figure 4
<p>Flow chart of the IFA-LADRC control scheme.</p> Full article ">Figure 5
<p>LADRC structure diagram of SOFC system.</p> Full article ">Figure 6
<p>Convergence curve.</p> Full article ">Figure 7
<p>Step response curve.</p> Full article ">Figure 8
<p>Voltage rise and fall response curve. (<b>a</b>) PID controller control. (<b>b</b>) LADRC controller control.</p> Full article ">Figure 9
<p>Magnification of the stepup and stepdown response curves of two controllers. (<b>a</b>) PID controller boost response curves. (<b>b</b>) PID controller buck response curves. (<b>c</b>) LADRC controller boost response curves. (<b>d</b>) LADRC controller buck response curves.</p> Full article ">Figure 9 Cont.
<p>Magnification of the stepup and stepdown response curves of two controllers. (<b>a</b>) PID controller boost response curves. (<b>b</b>) PID controller buck response curves. (<b>c</b>) LADRC controller boost response curves. (<b>d</b>) LADRC controller buck response curves.</p> Full article ">Figure 10
<p>Voltage rise and fall response curves under different controllers.</p> Full article ">Figure 11
<p>Voltage rise and fall response curves under different controllers. (<b>a</b>) Comparison of PID and LADRC boost voltage. (<b>b</b>) Comparison of PID and LADRC stepdown.</p> Full article ">Figure 12
<p>Monte Carlo experiment of (<b>a</b>) FA-PID and (<b>b</b>) IFA-PID control methods, wherein the lines in different colors denote system voltage outputs after the addition of a random disturbance within [20%, −20%].</p> Full article ">Figure 13
<p>Monte Carlo experiment of (<b>a</b>) FA-LADRC and (<b>b</b>) IFA-LADRC control methods, wherein the lines in different colors denote system voltage outputs after the addition of a random disturbance within [20%, −20%] (the same below).</p> Full article ">Figure 14
<p>Performance indicators of four control methods under Monte Carlo simulation.</p> Full article ">
13 pages, 2355 KiB  
Article
Neural Image Analysis for the Determination of Total and Volatile Solids in a Composted Sewage Sludge and Maize Straw Mixture
by Sebastian Kujawa, Gniewko Niedbała, Wojciech Czekała and Katarzyna Pentoś
Appl. Sci. 2023, 13(5), 3363; https://doi.org/10.3390/app13053363 - 6 Mar 2023
Cited by 2 | Viewed by 1822
Abstract
Waste management is one of most important challenges in environmental protection. Much effort is put into the development of waste treatment methods for further use. A serious problem is the treatment of municipal sewage sludge. One method that is useful for this substrate [...] Read more.
Waste management is one of most important challenges in environmental protection. Much effort is put into the development of waste treatment methods for further use. A serious problem is the treatment of municipal sewage sludge. One method that is useful for this substrate is composting. However, it is reasonable to compost a sewage sludge mixed with other substrates, such as maize straw. To carry out the composting process properly, it is necessary to control some parameters, including the total solids and volatile solids content in the composted mixture. In this paper, a method for the determination of the total solids and volatile solids content based on image analysis and neural networks was proposed. Image analysis was used for the determination of the colour and texture parameters. The three additional features describing the composted material were percentage of sewage sludge, type of maize straw, and stage of compost maturity. The neural models were developed based on various combinations of the input parameters. For both the total solids and volatile solids content, the most accurate models were obtained using all input parameters, including 30 parameters for image colour and texture and three features describing the composted material. The uncertainties of the developed models, expressed by the MAPE error, were 2.88% and 0.59%, respectively, for the prediction of the total solids and volatile solids content. Full article
(This article belongs to the Section Agricultural Science and Technology)
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<p>The photographic chambers used in the study.</p> Full article ">Figure 2
<p>Example images taken at the beginning (<b>left</b>) and the end (<b>right</b>) of each composting experiment ((<b>a</b>)—experiment 1; (<b>b</b>)—experiment 2; (<b>c</b>)—experiment 3; (<b>d</b>)—experiment 4; (<b>e</b>)—experiment 5; (<b>f</b>)—experiment 6; (<b>g</b>)—experiment 7; (<b>h</b>)—experiment 8).</p> Full article ">Figure 2 Cont.
<p>Example images taken at the beginning (<b>left</b>) and the end (<b>right</b>) of each composting experiment ((<b>a</b>)—experiment 1; (<b>b</b>)—experiment 2; (<b>c</b>)—experiment 3; (<b>d</b>)—experiment 4; (<b>e</b>)—experiment 5; (<b>f</b>)—experiment 6; (<b>g</b>)—experiment 7; (<b>h</b>)—experiment 8).</p> Full article ">Figure 3
<p>Results of the linear regression (<b>a</b>) and error histogram (<b>b</b>) for the test dataset and the MLP 33-10-1 TS10 model for the prediction of the total solids content.</p> Full article ">Figure 4
<p>Results of the linear regression (<b>a</b>) and error histogram (<b>b</b>) for the test dataset and the MLP 33-10-1 VS10 model for the prediction of the volatile solids content.</p> Full article ">
18 pages, 4753 KiB  
Article
Simplified Calculation of Shear Rotations for First-Order Shear Deformation Theory in Deep Bridge Beams
by Seyyedbehrad Emadi, Haiying Ma, Jose Antonio Lozano-Galant and Jose Turmo
Appl. Sci. 2023, 13(5), 3362; https://doi.org/10.3390/app13053362 - 6 Mar 2023
Cited by 3 | Viewed by 2154
Abstract
Nodal rotations are produced by bending and shear effects and bending rotations can be easily calculated using Euler–Bernoulli’s stiffness matrix method. Nevertheless, shear rotations are traditionally neglected, as their effects are practically negligible in most structures. This assumption might lead to significant errors [...] Read more.
Nodal rotations are produced by bending and shear effects and bending rotations can be easily calculated using Euler–Bernoulli’s stiffness matrix method. Nevertheless, shear rotations are traditionally neglected, as their effects are practically negligible in most structures. This assumption might lead to significant errors in the simulation of the rotations in some structures, as well as the wrong identification of the mechanical properties in inverse analysis. Despite its important role, no other works studying the calculation of shear rotations in deep beams were found in the literature. To fill this gap, after illustrating the errors of commercial software regarding calculating the rotations in deep beams, this study proposed a simple and intuitive method to calculate shear rotations in both isostatic and statically redundant beams. The new method calculates the shear rotation for all segments separately and introduces the result to the total rotation of the structure. This method can be applied to find the shear rotation in a redundant structure as well. A parametric study was carried out to calculate slenderness ratios to determine in what structural systems the shear rotations can be neglected. In addition, the errors in the inverse analysis of deep beams were parametrically studied to determine the role of shear rotation in different structural systems. Finally, to validate the application of the method in actual structures, a construction stage of a composite bridge was analyzed. Full article
(This article belongs to the Special Issue Advanced Structural Health Monitoring: From Theory to Applications II)
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<p>Support rotation of a beam support according to Euler–Bernoulli’s (<b>a</b>) and Timoshenko’s beam theories (<b>b</b>).</p> Full article ">Figure 2
<p>Example 1: simply supported structure: (<b>a</b>) finite element model and (<b>b</b>) cross-section.</p> Full article ">Figure 3
<p>Example 1: (<b>a</b>) vertical deflections and (<b>b</b>) rotations.</p> Full article ">Figure 4
<p>Flow chart to calculate the actual rotations in beams.</p> Full article ">Figure 5
<p>Example 2: continuous beam with and without shear effects: (<b>a</b>) vertical deflections, (<b>b</b>) shear diagrams, (<b>c</b>) rotations obtained with the commercial software, and (<b>d</b>) rotations including shear effects.</p> Full article ">Figure 6
<p>Parametric analysis of the slenderness ratio on example 1: (<b>a</b>) bending (<span class="html-italic">w<sub>b</sub></span><sub>,1</sub>) and shear (<span class="html-italic">w<sub>s</sub></span><sub>,1</sub>) rotations at node 1 and (<b>b</b>) percentage error of rotations in node 1 when ws,1 was neglected.</p> Full article ">Figure 7
<p>Parametric analysis of the effect of the slenderness ratio on example 2: (<b>a</b>) bending (<span class="html-italic">w<sub>b</sub></span><sub>,1</sub>) and shear (<span class="html-italic">w<sub>s</sub></span><sub>,1</sub>) rotations at node 1 and (<b>b</b>) percentage error of rotations in node 1 when <span class="html-italic">w<sub>s</sub></span><sub>,1</sub> was neglected.</p> Full article ">Figure 8
<p>Parametric analysis of the effect of the slenderness ratio on a cantilever beam with a concentrated load: (<b>a</b>) bending (<span class="html-italic">w<sub>b</sub></span><sub>,3</sub>) and shear (<span class="html-italic">w<sub>s</sub></span><sub>,3</sub>) rotations at node 3 and (<b>b</b>) percentage error of rotations in node 3 when ws,3 was neglected.</p> Full article ">Figure 9
<p>Percentage error between the estimated inertia using the OM method <math display="inline"><semantics> <mrow> <mover accent="true"> <mrow> <mi>I</mi> </mrow> <mo>¯</mo> </mover> </mrow> </semantics></math> with the actual one <span class="html-italic">I</span> for three beams in terms of the slenderness (<span class="html-italic">L</span>/<span class="html-italic">h</span> ratio).</p> Full article ">Figure 10
<p>Example of application: (<b>a</b>) Yunbao Bridge under construction [<a href="#B52-applsci-13-03362" class="html-bibr">52</a>] and (<b>b</b>) a sketch of the analyzed construction stage.</p> Full article ">Figure 10 Cont.
<p>Example of application: (<b>a</b>) Yunbao Bridge under construction [<a href="#B52-applsci-13-03362" class="html-bibr">52</a>] and (<b>b</b>) a sketch of the analyzed construction stage.</p> Full article ">Figure 11
<p>Yunbao Bridge: (<b>a</b>) cross-section and (<b>b</b>) finite element model (FEM).</p> Full article ">Figure 12
<p>Loading case: (<b>a</b>) loads from the formwork traveler and (<b>b</b>) modeled loading case.</p> Full article ">Figure 13
<p>Yunbao bridge analysis: (<b>a</b>) vertical deflections, (<b>b</b>) shear diagram, and (<b>c</b>) rotations with and without shear effects.</p> Full article ">Figure 13 Cont.
<p>Yunbao bridge analysis: (<b>a</b>) vertical deflections, (<b>b</b>) shear diagram, and (<b>c</b>) rotations with and without shear effects.</p> Full article ">
15 pages, 2020 KiB  
Article
Consistency of Water Vapour Pressure and Specific Heat Capacity Values for Modelling Clay-Based Engineered Barriers
by Laura Asensio, Gema Urraca and Vicente Navarro
Appl. Sci. 2023, 13(5), 3361; https://doi.org/10.3390/app13053361 - 6 Mar 2023
Cited by 1 | Viewed by 1872
Abstract
The aim of this study is to assess the consistency in the modelling of thermo-hydraulic problems in clay-based engineered barriers. This study focuses on two aspects: the modelling of vapour pressure as a function of temperature, and the specific heat capacities of liquid [...] Read more.
The aim of this study is to assess the consistency in the modelling of thermo-hydraulic problems in clay-based engineered barriers. This study focuses on two aspects: the modelling of vapour pressure as a function of temperature, and the specific heat capacities of liquid water and water vapour in relation to the enthalpy of vaporisation and the internal energy of liquid water and water vapour. Regarding the first aspect, several formulations of the saturated vapour pressure have been inspected, evaluating their accuracy and information provided in the temperature range from 0 to 150 °C. Regarding the second aspect, the enthalpy of vaporisation and the internal energy of water were used to assess the consistency of pairs of specific heat capacity values in the same temperature range. Values from the literature were also inspected. An accurate and simple enough expression for the saturated water vapour pressure with temperature has been identified as the optimal option for modelling. Recommendations on specific heat capacity constant values for liquid water and vapour are suggested to maximise consistency in the studied temperature range. However, the loss of accuracy in the enthalpy or internal energy of vaporisation associated with the inspected specific heat capacity pairs is limited. Full article
(This article belongs to the Special Issue Geomaterials: Latest Advances in Materials for Construction and Engineering Applications)
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<p>Saturated water vapour pressure as a function of temperature in the temperature range 0–150 °C for the different formulations analysed, Equations (1)–(8) [<a href="#B4-applsci-13-03361" class="html-bibr">4</a>,<a href="#B5-applsci-13-03361" class="html-bibr">5</a>,<a href="#B6-applsci-13-03361" class="html-bibr">6</a>,<a href="#B7-applsci-13-03361" class="html-bibr">7</a>,<a href="#B8-applsci-13-03361" class="html-bibr">8</a>,<a href="#B9-applsci-13-03361" class="html-bibr">9</a>,<a href="#B10-applsci-13-03361" class="html-bibr">10</a>,<a href="#B11-applsci-13-03361" class="html-bibr">11</a>,<a href="#B12-applsci-13-03361" class="html-bibr">12</a>]. Note that the results of Equations (2) and (3) practically overlap with the reference values of Equation (1).</p> Full article ">Figure 2
<p>Relative error in the saturated water vapour pressure, <span class="html-italic">RE</span><sub>pv0</sub>, with respect to the reference, Equation (1) [<a href="#B4-applsci-13-03361" class="html-bibr">4</a>], as a function of temperature for the different formulations analysed. Equations (2)–(8) [<a href="#B5-applsci-13-03361" class="html-bibr">5</a>,<a href="#B6-applsci-13-03361" class="html-bibr">6</a>,<a href="#B7-applsci-13-03361" class="html-bibr">7</a>,<a href="#B8-applsci-13-03361" class="html-bibr">8</a>,<a href="#B9-applsci-13-03361" class="html-bibr">9</a>,<a href="#B10-applsci-13-03361" class="html-bibr">10</a>,<a href="#B11-applsci-13-03361" class="html-bibr">11</a>,<a href="#B12-applsci-13-03361" class="html-bibr">12</a>].</p> Full article ">Figure 3
<p>Model selection results from information criteria for <span class="html-italic">n</span> = 3. Akaike weights <span class="html-italic">Aw</span> from the Akaike information criterion (blue), and posterior model probabilities <span class="html-italic">Bp</span> from the Bayesian information criterion (orange).</p> Full article ">Figure 4
<p>(<b>a</b>) Enthalpy of vaporisation Δ<span class="html-italic">h</span><sub>LV</sub>, and (<b>b</b>) difference in internal energy between vapour and liquid water Δ<span class="html-italic">u</span><sub>LV</sub>, for temperatures between 0 and 150 °C. Markers: reference values from [<a href="#B13-applsci-13-03361" class="html-bibr">13</a>]. Line and equation: best linear fit.</p> Full article ">Figure 5
<p>Specific heat capacity <span class="html-italic">c</span> of liquid (L, solid lines) water and water vapour (V, dashed lines) for the temperature range 0–150 °C, at the minimum between saturation pressure and 100 kPa, for isochoric (vol, black) and isobaric (p, blue outline) conditions. All values from the NIST [<a href="#B13-applsci-13-03361" class="html-bibr">13</a>].</p> Full article ">Figure 6
<p>Difference in specific heat capacity between liquid water and vapour as a function of temperature. Solid lines: reference values [<a href="#B13-applsci-13-03361" class="html-bibr">13</a>] for (<b>a</b>) isobaric and (<b>b</b>) isochoric conditions; dotted and dashed lines: identified <span class="html-italic">b</span> and <span class="html-italic">b</span>′ coefficients and the literature values in <a href="#applsci-13-03361-t002" class="html-table">Table 2</a> [<a href="#B7-applsci-13-03361" class="html-bibr">7</a>,<a href="#B12-applsci-13-03361" class="html-bibr">12</a>,<a href="#B14-applsci-13-03361" class="html-bibr">14</a>,<a href="#B15-applsci-13-03361" class="html-bibr">15</a>,<a href="#B16-applsci-13-03361" class="html-bibr">16</a>,<a href="#B17-applsci-13-03361" class="html-bibr">17</a>].</p> Full article ">Figure 7
<p>Values of (<b>a</b>) Δ<span class="html-italic">h</span><sub>LV</sub> and (<b>b</b>) Δ<span class="html-italic">u</span><sub>LV</sub> computed with Equations (22) and (24), respectively, for specific heat capacity pairs that maximise error, from the literature (solid grey lines, values from [<a href="#B12-applsci-13-03361" class="html-bibr">12</a>,<a href="#B14-applsci-13-03361" class="html-bibr">14</a>], Δ<span class="html-italic">h</span><sub>LV</sub>, and [<a href="#B17-applsci-13-03361" class="html-bibr">17</a>], Δ<span class="html-italic">u</span><sub>LV</sub>) and from reference values (dashed orange lines). Reference Δ<span class="html-italic">h</span><sub>LV</sub> and Δ<span class="html-italic">u</span><sub>LV</sub> [<a href="#B13-applsci-13-03361" class="html-bibr">13</a>] in blue markers.</p> Full article ">Figure 8
<p>Relative error in Δ<span class="html-italic">h</span><sub>LV</sub> and Δ<span class="html-italic">u</span><sub>LV</sub> at 150 °C using specific heat capacity pairs from reference values [<a href="#B13-applsci-13-03361" class="html-bibr">13</a>] at temperatures 0–150 °C.</p> Full article ">
12 pages, 1155 KiB  
Article
A Walkway from Crayfish to Oligochitosan
by Evgeniya A. Bezrodnykh, Oxana V. Vyshivannaya, Boris B. Berezin, Inesa V. Blagodatskikh and Vladimir E. Tikhonov
Appl. Sci. 2023, 13(5), 3360; https://doi.org/10.3390/app13053360 - 6 Mar 2023
Cited by 3 | Viewed by 1664
Abstract
Edible crayfish are an object of local fishing and artificial breeding in many countries. This industry is very promising in terms of production of healthy foods and byproducts, such as biologically active polyaminosaccharide—chitosan and its derivatives. However, crayfishing is far from being at [...] Read more.
Edible crayfish are an object of local fishing and artificial breeding in many countries. This industry is very promising in terms of production of healthy foods and byproducts, such as biologically active polyaminosaccharide—chitosan and its derivatives. However, crayfishing is far from being at the level at which it could be. This laboratory scale protocol describes a walkway from crayfish Actacus leptodactylus to chitin, chitosan, and oligochitosan hydrochloride, with the main emphasis on the way of getting rid of the impurities (residual heavy metals, proteins and other residues) commonly present in commercial chitosan and its derivatives, as well as the characterization of the products by means of inductively-coupled plasma mass spectrometry (ICP-MS), energy-dispersive X-ray spectroscopy (EDXS), protein and elemental analysis, proton magnetic resonance spectroscopy (1H NMR), and chromatography methods. The protocol includes the preparation of crude shell waste; the extraction of proteins from crude shell waste and preparation of deproteinated shell waste, demineralization and decolorization of the deproteinated crayfish shell waste, deacetylation of chitin, and depolymerization of chitosan. EDXS shows the presence of Al and Si residues in chitin is found when the deproteination of crayfish waste is carried out in an alumosilicate glass vessel. In contrast, these residues are absent when deproteination is carried out in the borosilicate glass flask. Analytical data show that the content of residues in chitosan and oligochitosan hydrochloride meets pharmaceutical requirements. The study demonstrates crayfish waste a promising for the purification of chitosan, for the preparation of pharmaceutical grade oligochitosan hydrochloride, and can improve commercialization of crayfishes. Full article
(This article belongs to the Special Issue Functional Polymers: Synthesis, Properties and Applications)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Alkaline (1–4) and acidified (5–8) extracts: SC extract (1,5), DPS extract (2,6), DDS extract (3,7), and chitosan extract (4,8).</p> Full article ">Figure 2
<p>(<b>a</b>)—EDX spectrum of chitin-AlSiG; (<b>b</b>)—EDX spectrum of chitin-BSiG.</p> Full article ">Figure 3
<p>(<b>a</b>)—EDX analysis of chitosan; (<b>b</b>)—EDX spectrum of oligochitosan.</p> Full article ">Figure 4
<p>HP-SEC elution profiles of chitosan (1) and oligochitosan (2).</p> Full article ">Figure 5
<p><sup>1</sup>H-NMR spectrum of crayfish chitosan (red) and oligochitosan (green).</p> Full article ">
21 pages, 7001 KiB  
Article
Voice Interaction Recognition Design in Real-Life Scenario Mobile Robot Applications
by Shih-An Li, Yu-Ying Liu, Yun-Chien Chen, Hsuan-Ming Feng, Pi-Kang Shen and Yu-Che Wu
Appl. Sci. 2023, 13(5), 3359; https://doi.org/10.3390/app13053359 - 6 Mar 2023
Cited by 14 | Viewed by 4609
Abstract
This paper designed a voice interactive robot system that can conveniently execute assigned service tasks in real-life scenarios. It is equipped without a microphone where users can control the robot with spoken commands; the voice commands are then recognized by a well-trained deep [...] Read more.
This paper designed a voice interactive robot system that can conveniently execute assigned service tasks in real-life scenarios. It is equipped without a microphone where users can control the robot with spoken commands; the voice commands are then recognized by a well-trained deep neural network model of automatic speech recognition (ASR), which enables the robot to execute and complete the command based on the navigation of a real-time simultaneous localization and mapping (SLAM) algorithm. The voice interaction recognition model is divided into two parts: (1) speaker separation and (2) ASR. The speaker separation is applied by a deep-learning system consisting of eight convolution layers, one LSTM layer, and two fully connected (FC) layers to separate the speaker’s voice. This model recognizes the speaker’s voice as a referrer that separates and holds the required voiceprint and removes noises from other people’s voiceprints. Its automatic speech recognition uses the novel sandwich-type conformer model with a stack of three layers, and combines convolution and self-attention to capture short-term and long-term interactions. Specifically, it contains a multi-head self-attention module to directly convert the voice data into text for command realization. The RGB-D vision-based camera uses a real-time appearance-based mapping algorithm to create the environment map and replace the localization with a visional odometer to allow the robot to navigate itself. Finally, the proposed ASR model was tested to check if the desired results will be obtained. Performance analysis was applied to determine the robot’s environment isolation and voice recognition abilities. The results showed that the practical robot system successfully completed the interactive service tasks in a real environment. This experiment demonstrates the outstanding performance with other ASR methods and voice control mobile robot systems. It also verified that the designed voice interaction recognition system enables the mobile robot to execute tasks in real-time, showing that it is a convenient way to complete the assigned service applications. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2021)
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<p>Speaker separation system architecture diagram.</p> Full article ">Figure 2
<p>Speaker-Encoder Architecture Diagram.</p> Full article ">Figure 3
<p>Voice filter architecture diagram.</p> Full article ">Figure 4
<p>Voice filter model train flow chart.</p> Full article ">Figure 5
<p>SDR vector diagram.</p> Full article ">Figure 6
<p>Conformer model structure.</p> Full article ">Figure 7
<p>Conformer blocks.</p> Full article ">Figure 8
<p>Post-norm residual unit.</p> Full article ">Figure 9
<p>Multi-head self-attention module.</p> Full article ">Figure 10
<p>Pre-norm residual unit.</p> Full article ">Figure 11
<p>Convolution module.</p> Full article ">Figure 12
<p>Feed-forward module.</p> Full article ">Figure 13
<p>The related SDR value with the amount dataset of 921 people.</p> Full article ">Figure 14
<p>The related SDR value with the amount dataset of 1200 people.</p> Full article ">Figure 15
<p>Flow chart of the RTAB-based SLAM.</p> Full article ">Figure 16
<p>Flow chart of the loop closure detection by RTAB-map.</p> Full article ">Figure 17
<p>Simulation for feature-matching result.</p> Full article ">Figure 18
<p>Sequential actions of a real mobile robot for different service tasks.</p> Full article ">Figure 18 Cont.
<p>Sequential actions of a real mobile robot for different service tasks.</p> Full article ">Figure 18 Cont.
<p>Sequential actions of a real mobile robot for different service tasks.</p> Full article ">
15 pages, 2803 KiB  
Article
Dehydrated Sauerkraut Juice in Bread and Meat Applications and Bioaccessibility of Total Phenol Compounds after In Vitro Gastrointestinal Digestion
by Liene Jansone, Zanda Kruma, Kristine Majore and Solvita Kampuse
Appl. Sci. 2023, 13(5), 3358; https://doi.org/10.3390/app13053358 - 6 Mar 2023
Cited by 4 | Viewed by 1827
Abstract
The aim of this study was to evaluate dehydrated sauerkraut juice (DSJ) in bread and meat applications and investigate bioaccessibility (BAC) of TPC in the analyzed products. In current research, sauerkraut juice, dehydrated sauerkraut juice, and bread and meat products prepared with dehydrated [...] Read more.
The aim of this study was to evaluate dehydrated sauerkraut juice (DSJ) in bread and meat applications and investigate bioaccessibility (BAC) of TPC in the analyzed products. In current research, sauerkraut juice, dehydrated sauerkraut juice, and bread and meat products prepared with dehydrated sauerkraut juice were analyzed. For all of the samples, total phenol content, antiradical activity by ABTS+, bioaccessibility, and volatile compound profile were determined. Additionally, sensory evaluation was performed to evaluate the degree of liking bread and meat with dehydrated sauerkraut juice. The addition of DSJ increased TPC in bread and meat samples. The bioaccessibility was higher for the control samples compared to DSJ samples. It exceeded 1 and is considered as good. DSJ did not promote bioaccessibility. Benzaldehyde was the highest peak area for the Bread DSJ and Meat DSJ samples, giving a roasted peanut and almond aroma. There were no significant differences in degree of liking for structure, taste, and aroma between the control bread and the Bread DSJ, while Meat DSJ was more preferable in sensory evaluation. DSJ could be used in food applications, but further research is necessary. Full article
(This article belongs to the Special Issue Effects of Processing on Food Composition, Nutritional Value and Sensory Quality)
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<p>Bioaccessibility index (BAC) of the sauerkraut juice (SJ) and dehydrated sauerkraut juice (DSJ) based on TPC and ABTS<sup>+</sup> scavenging activity after in vitro digestion.</p> Full article ">Figure 2
<p>The percentage of volatile compound peak areas in sauerkraut and dehydrated sauerkraut juice.</p> Full article ">Figure 3
<p>Bioaccessibility index (BAC) of the bread samples based on TPC and ABTS<sup>+</sup> scavenging activity after in vitro digestion.</p> Full article ">Figure 4
<p>The percentage of volatile compound peak areas in the bread samples.</p> Full article ">Figure 5
<p>Hedonic evaluation of the bread samples. * Value in brackets present mean value of hedonic evaluation and the same letter along the values shows that the difference between the means between two samples is not statistically significant.</p> Full article ">Figure 6
<p>Bioaccessibility index (BAC) of the meat samples based on TPC and ABTS<sup>+</sup> compound activity after in vitro digestion.</p> Full article ">Figure 7
<p>The percentage of volatile compound peak areas in the meat samples.</p> Full article ">Figure 8
<p>Hedonic evaluation of the meat samples. The same letter along the values shows that the difference between the means of two samples is not statistically significant.</p> Full article ">
10 pages, 1138 KiB  
Article
Audio Feedback with the Use of a Smartphone in Sailing Training among Windsurfers
by Jacek Tarnas, Magdalena Cyma-Wejchenig, Nina Schaffert and Rafał Stemplewski
Appl. Sci. 2023, 13(5), 3357; https://doi.org/10.3390/app13053357 - 6 Mar 2023
Cited by 1 | Viewed by 1734
Abstract
The open-water training conditions in sailing sports limit the coach’s ability to provide instructions. Auditory feedback provided using a smartphone application in real-time seems to be a promising tool in the training process. The aim of the study was to assess the usefulness [...] Read more.
The open-water training conditions in sailing sports limit the coach’s ability to provide instructions. Auditory feedback provided using a smartphone application in real-time seems to be a promising tool in the training process. The aim of the study was to assess the usefulness of a smartphone application created to support tactical decisions via an auditory display. Thirteen successful windsurfers competing in RS:X class took part in the study. The results, collected with the use of a questionnaire, related to the technical and aesthetic aspects of the functions as well as decision-making assistance of the application during upwind sailing races. Most of the competitors positively evaluated application function (54–85%). Real-time information about the deviation from the set course and information about potential tack change due to a changed wind direction were statistically significantly more helpful for less experienced windsurfers (rho = −0.68 and rho = −0.78, respectively) and those with lower sports level (rho = −0.63 and rho = −0.65, respectively). It can be concluded that the use of sound feedback in the conditions of training on-water in sailing has potential, primarily for younger and less experienced competitors. Quantitative evaluations of the sailing performance should be considered in further research on the functionality of the application. Full article
(This article belongs to the Special Issue Wearables and Smartphone Applications in Sports)
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<p>A shift in the optimal courses as a result of change in wind direction. (<b>A</b>) the line of wind direction is aligned with the line between the start and windward buoy; (<b>B</b>) the line of wind direction is a shift of 20° from the line between the start and windward buoy. W1, W2—direction of the example wind.</p> Full article ">Figure 2
<p>Examples of variants of windsurfing board courses, depending on the moment of the last tack. 1—windsurfer took the optimal course thanks to a sound message (“Layline”); 2—windsurfer overstepped layline.</p> Full article ">Figure 3
<p>Placing the smartphone on the mast.</p> Full article ">Figure 4
<p>Percentage distribution of positive, neutral, and negative answers connected to technical (<b>A</b>) and usefulness (<b>B</b>) aspects of app functions.</p> Full article ">
13 pages, 5024 KiB  
Article
Effectiveness of High-Damping Rubber (HDR) Damper and Tuned Mass—HDR Damper in Suppressing Stay-Cable Vibration
by Yichao Xu, Changzhao Li, Yu Cheng and Yufeng Zhang
Appl. Sci. 2023, 13(5), 3356; https://doi.org/10.3390/app13053356 - 6 Mar 2023
Cited by 1 | Viewed by 2155
Abstract
High-damping rubber (HDR) dampers have the advantages of convenience for various shapes of pressure blocks, aesthetic installation, easy maintenance, temperature stability, etc.; thus, they present good application prospects in the vibration reduction of stay cables. Hence, a model of a taut cable equipped [...] Read more.
High-damping rubber (HDR) dampers have the advantages of convenience for various shapes of pressure blocks, aesthetic installation, easy maintenance, temperature stability, etc.; thus, they present good application prospects in the vibration reduction of stay cables. Hence, a model of a taut cable equipped with two types of HDR damper—i.e., HDR damper and tuned mass–high-damping rubber damper (TM-HDR-D)—is established herein. Then, based on this theoretical model, the effect of each damper acting alone and in combination on the cable’s additional modal damping is studied. Finally, an actual cable of a cable-stayed bridge is used to study the effectiveness of two dampers for practical engineering. The results show that, when the TM-HDR-D has a small mass, the total additional modal damping of the cable approximates the superposition of the respective effects of the two dampers. The damping effect of HDR mainly depends on its stiffness and installation position; meanwhile, the damping contribution of TM-HDR-D is mainly related to its tuning frequency and installation position. In practical engineering, the smaller installation mass of TM-HDR-D can make up for the lack of damping enhancement of the cable-end HDR damper. Full article
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<p>Model diagram of a taut cable with an HDR damper and a TM-HDR-D.</p> Full article ">Figure 2
<p>Modal damping curves of a cable with a single HDR damper for (<b>a</b>) different loss factor <span class="html-italic">φ</span> (<span class="html-italic">x</span><sub>1</sub>/<span class="html-italic">L</span> = 0.02) and (<b>b</b>) different location <span class="html-italic">x</span><sub>1</sub>/<span class="html-italic">L</span>.</p> Full article ">Figure 3
<p>Modal damping of a cable with a single TM-HDR-D versus damper location <span class="html-italic">x</span><sub>2</sub>/<span class="html-italic">L</span> (<span class="html-italic">φ</span> = 0.5): (<b>a</b>) mode 1 (<span class="html-italic">ρ</span> = 1); (<b>b</b>) mode 2 (<span class="html-italic">ρ</span> = 0.5).</p> Full article ">Figure 4
<p>First modal damping of a cable with a single TM-HDR-D versus the frequency ratio <math display="inline"> <semantics> <mi>ρ</mi> </semantics> </math> (<math display="inline"> <semantics> <mrow> <msub> <mi>x</mi> <mn>2</mn> </msub> <mo>/</mo> <mi>L</mi> <mo>=</mo> <mn>0.5</mn> <mo> </mo> <mo>,</mo> <mi>φ</mi> <mo>=</mo> <mn>0.5</mn> </mrow> </semantics> </math>).</p> Full article ">Figure 5
<p>First modal damping of a cable with two dampers versus the HDR damper stiffness <math display="inline"> <semantics> <mrow> <msub> <mover accent="true"> <mi>K</mi> <mo>¯</mo> </mover> <mn>1</mn> </msub> </mrow> </semantics> </math> (<math display="inline"> <semantics> <mrow> <mi>φ</mi> <mo>=</mo> <mn>0.5</mn> <mo>,</mo> <mo> </mo> <mi>ρ</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mo> </mo> <msub> <mi>x</mi> <mn>2</mn> </msub> <mo>/</mo> <mi>L</mi> </mrow> </semantics> </math> = 0.5), with (<b>a</b>) <math display="inline"> <semantics> <mrow> <msub> <mi>x</mi> <mn>1</mn> </msub> <mo>/</mo> <mi>L</mi> </mrow> </semantics> </math> = 0.02 and (<b>b</b>) <math display="inline"> <semantics> <mrow> <msub> <mi>x</mi> <mn>1</mn> </msub> <mo>/</mo> <mi>L</mi> </mrow> </semantics> </math> = 0.05.</p> Full article ">Figure 6
<p>Modal shapes of cables with different dampers.</p> Full article ">Figure 7
<p>Second modal damping of a cable with two dampers versus the HDR damper stiffness <math display="inline"> <semantics> <mrow> <msub> <mover accent="true"> <mi>K</mi> <mo>¯</mo> </mover> <mn>1</mn> </msub> </mrow> </semantics> </math> (<math display="inline"> <semantics> <mrow> <mi>φ</mi> <mo>=</mo> <mn>0.5</mn> <mo>,</mo> <mo> </mo> <mi>ρ</mi> <mo>=</mo> <mn>0.5</mn> <mo>,</mo> <mo> </mo> <msub> <mi>x</mi> <mn>2</mn> </msub> <mo>/</mo> <mi>L</mi> </mrow> </semantics> </math> = 0.25), with (<b>a</b>) <math display="inline"> <semantics> <mrow> <msub> <mi>x</mi> <mn>1</mn> </msub> <mo>/</mo> <mi>L</mi> </mrow> </semantics> </math> = 0.02 and (<b>b</b>) <math display="inline"> <semantics> <mrow> <msub> <mi>x</mi> <mn>1</mn> </msub> <mo>/</mo> <mi>L</mi> </mrow> </semantics> </math> = 0.05.</p> Full article ">Figure 8
<p>First modal damping of a cable with two dampers versus the TM-HDR-D location <math display="inline"> <semantics> <mrow> <msub> <mi>x</mi> <mn>2</mn> </msub> <mo>/</mo> <mi>L</mi> </mrow> </semantics> </math> (<math display="inline"> <semantics> <mrow> <mi>φ</mi> <mo>=</mo> <mn>0.5</mn> <mo>,</mo> <mo> </mo> <mi>ρ</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics> </math>), with (<b>a</b>) <math display="inline"> <semantics> <mrow> <msub> <mi>x</mi> <mn>1</mn> </msub> <mo>/</mo> <mi>L</mi> </mrow> </semantics> </math> = 0.02 and (<b>b</b>) <math display="inline"> <semantics> <mrow> <msub> <mi>x</mi> <mn>1</mn> </msub> <mo>/</mo> <mi>L</mi> </mrow> </semantics> </math> = 0.05.</p> Full article ">Figure 9
<p>Second modal damping of a cable with two dampers versus the TM-HDR-D location <math display="inline"> <semantics> <mrow> <msub> <mi>x</mi> <mn>2</mn> </msub> <mo>/</mo> <mi>L</mi> </mrow> </semantics> </math> (<math display="inline"> <semantics> <mrow> <mi>φ</mi> <mo>=</mo> <mn>0.5</mn> <mo>,</mo> <mo> </mo> <mi>ρ</mi> <mo>=</mo> <mn>0.5</mn> </mrow> </semantics> </math>), with (<b>a</b>) <math display="inline"> <semantics> <mrow> <msub> <mi>x</mi> <mn>1</mn> </msub> <mo>/</mo> <mi>L</mi> <mo> </mo> </mrow> </semantics> </math> = 0.02 and (<b>b</b>) <math display="inline"> <semantics> <mrow> <msub> <mi>x</mi> <mn>1</mn> </msub> <mo>/</mo> <mi>L</mi> <mo> </mo> </mrow> </semantics> </math> = 0.05.</p> Full article ">Figure 10
<p>Dampers’ design targeting the cable’s first vibration mode (<math display="inline"> <semantics> <mrow> <mi>φ</mi> <mo>=</mo> <mn>0.5</mn> <mo>,</mo> <msub> <mi>x</mi> <mn>1</mn> </msub> <mo>/</mo> <mi>L</mi> <mo>=</mo> <mn>0.02</mn> <mo> </mo> <mo>,</mo> <mi>ρ</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics> </math>): (<b>a</b>) parameter optimization of the HDR damper; (<b>b</b>) location parameter optimization of the TM-HDR-D.</p> Full article ">Figure 11
<p>Dampers’ design targeting the first two cable vibration modes (<math display="inline"> <semantics> <mrow> <mi>M</mi> <mo>=</mo> <mn>70</mn> <mrow> <mtext> </mtext> <mi>kg</mi> </mrow> <mo>,</mo> <mtext> </mtext> <mi>φ</mi> <mo>=</mo> <mn>0.5</mn> <mo>,</mo> <mo> </mo> <msub> <mi>x</mi> <mn>1</mn> </msub> <mo>/</mo> <mi>L</mi> <mo>=</mo> <mn>0.02</mn> </mrow> </semantics> </math>) with different frequency ratios: (<b>a</b>) <math display="inline"> <semantics> <mrow> <mi>ρ</mi> <mo>=</mo> <mn>0.7</mn> </mrow> </semantics> </math>; (<b>b</b>) <math display="inline"> <semantics> <mrow> <mi>ρ</mi> <mo>=</mo> <mn>0.8</mn> </mrow> </semantics> </math>; (<b>c</b>) <math display="inline"> <semantics> <mrow> <mi>ρ</mi> <mo>=</mo> <mn>0.9</mn> </mrow> </semantics> </math>.</p> Full article ">
17 pages, 19304 KiB  
Article
Structural Design of Aerostatic Bearing Based on Multi-Objective Particle Swarm Optimization Algorithm
by Biqing Ye, Guixin Yu, Yidong Zhang and Gang Li
Appl. Sci. 2023, 13(5), 3355; https://doi.org/10.3390/app13053355 - 6 Mar 2023
Cited by 2 | Viewed by 1592
Abstract
Aerostatic bearings are considered crucial components that can improve the measurement accuracy of ground simulation tests of space equipment. A structural optimization design method is proposed to enhance the static performance of aerostatic bearings. A mathematical model which can quickly calculate the aerostatic [...] Read more.
Aerostatic bearings are considered crucial components that can improve the measurement accuracy of ground simulation tests of space equipment. A structural optimization design method is proposed to enhance the static performance of aerostatic bearings. A mathematical model which can quickly calculate the aerostatic bearing capacity and gas consumption is established, and the influence of structural parameters on bearing performance is analyzed using simulation software. By comparing the convergence time and convergence results of the algorithm using different initialization methods, the Latin hypercube initialization method is selected instead of the random initialization method. The multi-objective particle swarm optimization algorithm is used to obtain the optimal solution set distributed in the objective space. It is found that the optimized structural parameters meet the requirements of improving the capacity and reducing gas consumption, which verifies the method’s effectiveness in designing the structural parameters of aerostatic bearings. Full article
(This article belongs to the Special Issue Structural Optimization Methods and Applications)
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<p>(<b>a</b>) Structure diagram of aerostatic bearing; (<b>b</b>) orifice distribution diagram.</p> Full article ">Figure 2
<p>Sketch of gas film in the circumferential direction.</p> Full article ">Figure 3
<p>Simulation process.</p> Full article ">Figure 4
<p>(<b>a</b>) Gas film flow filed meshing (1/2 model); (<b>b</b>) orifice meshing densification; (<b>c</b>) meshing layering.</p> Full article ">Figure 5
<p>Relationship between bearing capacity and eccentricity [<a href="#B29-applsci-13-03355" class="html-bibr">29</a>].</p> Full article ">Figure 6
<p>Influence of orifice diameter on (<b>a</b>) bearing capacity and (<b>b</b>) gas consumption.</p> Full article ">Figure 7
<p>Influence of orifice position on (<b>a</b>) bearing capacity and (<b>b</b>) gas consumption.</p> Full article ">Figure 8
<p>Influence of average film thickness on (<b>a</b>) bearing capacity and (<b>b</b>) gas consumption.</p> Full article ">Figure 9
<p>Influence of the number of orifices on (<b>a</b>) bearing capacity and (<b>b</b>) gas consumption.</p> Full article ">Figure 10
<p>Distribution of (<b>a</b>) Latin hypercube and (<b>b</b>) random initialization.</p> Full article ">Figure 11
<p>Pareto solutions obtained using (<b>a</b>) Latin hypercube and (<b>b</b>) random initialization.</p> Full article ">Figure 12
<p>Pareto solutions obtained using (<b>a</b>) Latin hypercube and (<b>b</b>) random initialization after the 60th generation.</p> Full article ">Figure 13
<p>Pareto solutions obtained after the 60th generation.</p> Full article ">Figure 14
<p>Performance metrics of the multi-objective optimization algorithm.</p> Full article ">
33 pages, 2975 KiB  
Review
Use of Phase Change Materials for Food Applications—State of the Art in 2022
by Harald Mehling
Appl. Sci. 2023, 13(5), 3354; https://doi.org/10.3390/app13053354 - 6 Mar 2023
Cited by 22 | Viewed by 5829
Abstract
The availability of food to a growing world population is a matter of concern for decades. Despite that, post-harvest losses are large in many countries, due to insufficient food preservation. And recently rising prices for fossil energies additionally increase food cost, thus increase [...] Read more.
The availability of food to a growing world population is a matter of concern for decades. Despite that, post-harvest losses are large in many countries, due to insufficient food preservation. And recently rising prices for fossil energies additionally increase food cost, thus increase the demand for energy efficiency. Probably the first application of phase change materials (PCM) ever was the use of ice for food storage, for preservation. Related to that is the use of ice for transport, and for fast cool down in food processing. The result of a desktop study shows the range of food applications of PCM, the advantages using PCM, and the state-of-the-art, meaning past and ongoing R&D, also including existing commercial products. The overview covers food processing, e.g., industrial process cooling and heating, local pre-cooling of harvested food, solar drying and cooking, for storage and transport e.g., solar cold rooms, fridges, display coolers, trucks and containers, and for food production specifically greenhouses and water purification. PCM are used in many real applications as commercial products, and in many other applications their advantages are proven. Regarding future R&D, the overview also identifies potential for improvement, possibly even of commercial products. Full article
(This article belongs to the Special Issue The Application of Phase Change Materials in Heat Storage)
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<p>Ideal phase change: heating and cooling T(t), as well as h(T) and c<sub>p</sub>(T).</p> Full article ">Figure 2
<p>Overview on food applications, specifically thermal ones.</p> Full article ">Figure 3
<p>1000 L bulk milk cooler with ice storage (source: Inficold).</p> Full article ">Figure 4
<p>Mobile solar-driven freezer/pre-cooler (source: Phase Change Material Products Ltd.).</p> Full article ">Figure 5
<p>Solar dryer with PCM, for drying agriculture produce (source: PLUSS Advanced Technologies Ltd.).</p> Full article ">Figure 6
<p>Approach to cool frozen food production, storage, and distribution facilities (source: Viking Cold Solutions™ Inc.).</p> Full article ">Figure 7
<p>Solar cold room (source: PLUSS Advanced Technologies Ltd.).</p> Full article ">Figure 8
<p>Freezer/cooler (source: PLUSS Advanced Technologies Ltd.).</p> Full article ">Figure 9
<p>Display/retail freezer/cooler (source: PLUSS Advanced Technologies Ltd.) and PCM-based cold battery as thermal backup for retail freezers (source: RGEES, Arden, NC, USA).</p> Full article ">Figure 10
<p>PronGO<sup>®</sup> bag and box (source: both PLUSS Advanced Technologies Ltd.) and va-Q-tainer for large volumes (source: va-Q-tec AG, Würzburg, Germany).</p> Full article ">Figure 11
<p>PCM filled metallic plates mounted in a van for cooling (source: both PLUSS Advanced Technologies Ltd.).</p> Full article ">
27 pages, 4589 KiB  
Review
Bond Characterization in Cementitious Material Binders Using Fourier-Transform Infrared Spectroscopy
by Moruf Olalekan Yusuf
Appl. Sci. 2023, 13(5), 3353; https://doi.org/10.3390/app13053353 - 6 Mar 2023
Cited by 42 | Viewed by 7927
Abstract
Fourier-transform infrared (FTIR) spectroscopy is a fast and simple technique for functional group identification. This work provides a review and insight into the application and interpretation of FTIR spectroscopy for cementitious binders that comprise ordinary Portland cement, alkaline-activated binders, geopolymers, and material characterization [...] Read more.
Fourier-transform infrared (FTIR) spectroscopy is a fast and simple technique for functional group identification. This work provides a review and insight into the application and interpretation of FTIR spectroscopy for cementitious binders that comprise ordinary Portland cement, alkaline-activated binders, geopolymers, and material characterization for civil engineering material applications. This technique can be used to identify different compounds and a moiety of bond vibrations in inorganic molecules such as Si-O, -OH, H-O-H (water), C-O (carbonate or carbonation), aluminosilicate (Si-O-T, where T is Al or Si), and S-O (sulfate or gypsum) found in hydrated cement, alkaline binders, and geopolymers. The prominent bands include those representing carbonation (CO32− 1390–1475 cm−1), calcium carbonate (871, 1792–2516 cm−1), hydroxylation and water molecules (1607, 3400–3650 cm−1), strength skeletal framework compositions or Al-Si substitutions, silicate organization (C-A-S-H, N-A-S-H, or C-S-H (950–1055 cm−1), and sulfate (600–680, 1080–1100 cm−1). Some of the factors that could affect the spectra bands include elemental displacement due to changes in molar mass, activated temperature, pH, activator concentration, w/b ratio, Ca/Si ratio, Si/Al ratio, and the silica modulus (SiO2/Na2O) of the activators used in the binder synthesis. The method could be used for destructive and non-destructive testing on paste sample by using transmission and attenuated total reflectance methods, respectively. Full article
(This article belongs to the Special Issue Construction Materials: Characterization, Structure and Durability)
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<p>Mechanism of FTIR Interferometer (Ref. [<a href="#B16-applsci-13-03353" class="html-bibr">16</a>] and used under copyright permission through <a href="http://delloyd.50megs.com/newfolder/copyright.html" target="_blank">http://delloyd.50megs.com/newfolder/copyright.html</a>, accessed on 3 December 2022).</p> Full article ">Figure 2
<p>Vibration modes in FTIR spectroscopy “(From Ref. [<a href="#B21-applsci-13-03353" class="html-bibr">21</a>] and used under Creative Commons CC-BY license.)”.</p> Full article ">Figure 3
<p>FTIR spectra of anhydrous cement phases (From Elsevier Ref. [<a href="#B53-applsci-13-03353" class="html-bibr">53</a>] and used with permission).</p> Full article ">Figure 4
<p>Aluminosilicate (Si-O-T) band due to an increment in C/S ratios (<b>a</b>) Si/Al = 1 and (<b>b</b>) Si/Al = 2 (From Wiley Ref. [<a href="#B74-applsci-13-03353" class="html-bibr">74</a>] with copyright permission).</p> Full article ">Figure 5
<p>Vibration bands in OPC, AAS, and geopolymer binders (From Elsevier Ref. [<a href="#B63-applsci-13-03353" class="html-bibr">63</a>] and used with copyright permission).</p> Full article ">Figure 6
<p>FTIR spectra of zeolite <b>A</b> and associated phases obtained by hydrothermal synthesis: (a) unreacted metakaolin, (b) 1.0M NaOH, (c) 1.5M NaOH, (d) 2.0M NaOH, (e) 2.5M NaOH, (f) 3.0M NaOH, (g) 3.5M NaOH, (h) 4.0M NaOH, and (i) commercial zeolite A (Fluka No. 69836) (From JAAUBA Ref. [<a href="#B77-applsci-13-03353" class="html-bibr">77</a>] and used under Creative Commons CC-BY license).</p> Full article ">Figure 7
<p>Si-O-T asymmetric vibration band with silica modulus, N-NaOH activator, and both (NaOH+Na<sub>2</sub>SiO<sub>3</sub>) in W50 such that Na<sub>2</sub>O/SiO<sub>2</sub> = 0.69 (From Elsevier Ref. [<a href="#B79-applsci-13-03353" class="html-bibr">79</a>] and used with copyright permission).</p> Full article ">Figure 8
<p>FTIR spectra in ordinary Portlandite cement (From IntechOpen Ref. [<a href="#B58-applsci-13-03353" class="html-bibr">58</a>] and used under Creative Commons CC-BY license).</p> Full article ">Figure 9
<p>The effect of Al on Si-O-T band asymmetric stretching in an alkaline binder (From Elsevier Ref. [<a href="#B30-applsci-13-03353" class="html-bibr">30</a>] and used with permission).</p> Full article ">Figure 10
<p>The role of aluminum in the asymmetric stretching of Si-O-T (in NC, NA2, and NA4 containing Al(NO<sub>3</sub>)<sub>3</sub>). From Elsevier Ref. [<a href="#B65-applsci-13-03353" class="html-bibr">65</a>] and used with permission.</p> Full article ">Figure 11
<p>The effect of NiO<sub>2</sub>/SiO<sub>2</sub> on Si-O-T asymmetric vibrations in FTIR for (<b>a</b>) OH/HOH and (<b>b</b>) Si-O-T bands (From ACS Ref. [<a href="#B45-applsci-13-03353" class="html-bibr">45</a>] and used with permission).</p> Full article ">Figure 12
<p>Sulfuric acid attack of palm oil fuel ash/slag alkaline binders (From JMCE Ref. [<a href="#B100-applsci-13-03353" class="html-bibr">100</a>] and used with permission).</p> Full article ">Figure 13
<p>Effect of a sulfate attack on a Si-O-T band (From RILEM Ref. [<a href="#B66-applsci-13-03353" class="html-bibr">66</a>] and used with permission).</p> Full article ">Figure 14
<p>The effect of a sulfate attack on a Si-O-T band (From Elsevier Ref. [<a href="#B28-applsci-13-03353" class="html-bibr">28</a>] and used with permission).</p> Full article ">Figure 15
<p>Variation in the vibration of molecular water due to a sulfate attack (a) control, (b) 5% sodium sulfate exposure, (c) 5% magnesium sulfate exposure, and (d) combination (From Elsevier Ref. [<a href="#B86-applsci-13-03353" class="html-bibr">86</a>] and used with permission).</p> Full article ">
11 pages, 599 KiB  
Article
Method for the Quantification of mHealth Related Physical Activity Intensity Using Consumer Mobile Sensors
by Jean-Baptiste Tylcz, Max Schreiber, Dominik Michalski, Joseph Classen and Galina Ivanova
Appl. Sci. 2023, 13(5), 3352; https://doi.org/10.3390/app13053352 - 6 Mar 2023
Viewed by 1347
Abstract
Daily physical activity is one of the key factors to improve health and support the prevention of a variety of chronic diseases e.g., hypertension, depression or acute events such as strokes. Self-monitoring by the patients has shown to improve adherence to care and [...] Read more.
Daily physical activity is one of the key factors to improve health and support the prevention of a variety of chronic diseases e.g., hypertension, depression or acute events such as strokes. Self-monitoring by the patients has shown to improve adherence to care and thus leads to general improvement of health conditions. However, precise physical activity detection and quantification may involve heavy or expensive sensors and often-complex computations. Other types of bottlenecks, such as proprietary algorithms or machine learning methods, which often do not meet requirements of medical use cases due to a lack in transparency and requested levels of accuracy and robustness, motivated the work presented here. In this paper, we propose the adaptation of the Euclidean norm minus one method, which was already demonstrated as relevant for physical activity intensity discrimination. The main modification stands in the use of a gravity estimate to countervail imprecise sensors, which allows using the metric with low sampled wrist accelerometer data, collected with off-the-shelf smartwatches in daily live environments. As proof of concept, the proposed algorithm was evaluated on a reference data set acquired on healthy subjects. The method shows the ability to discriminate between low, moderate, and high intensity activities. Full article
(This article belongs to the Section Biomedical Engineering)
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<p>The gravitational acceleration estimation <math display="inline"><semantics> <msub> <mi>g</mi> <mrow> <mi>e</mi> <mi>s</mi> <mi>t</mi> </mrow> </msub> </semantics></math> is computed as the median of the low-pass filtered (in blue) ENMEG (<math display="inline"><semantics> <mrow> <mi>E</mi> <mo>[</mo> <mi>k</mi> <mo>]</mo> </mrow> </semantics></math>, in black) considered between the boundary <math display="inline"><semantics> <mrow> <mo>[</mo> <mn>0.9</mn> <mo>,</mo> <mn>1.1</mn> <mo>]</mo> </mrow> </semantics></math> (in grey).</p> Full article ">Figure 2
<p>Illustration of how the thresholds <math display="inline"><semantics> <msub> <mi>τ</mi> <mi>i</mi> </msub> </semantics></math> with <math display="inline"><semantics> <mrow> <mi>i</mi> <mo>∈</mo> <mo>{</mo> <mn>1</mn> <mo>,</mo> <mn>2</mn> <mo>,</mo> <mn>3</mn> <mo>}</mo> </mrow> </semantics></math> are estimated for each subject, by searching for the minimum histogram count of <math display="inline"><semantics> <mover> <mi>E</mi> <mo>¯</mo> </mover> </semantics></math> within the range <math display="inline"><semantics> <msub> <mi>R</mi> <mi>i</mi> </msub> </semantics></math>.</p> Full article ">Figure 3
<p>Raw accelerometers data from subject 3 along axis x, y and z and the corresponding averaged ENMEG signal <math display="inline"><semantics> <mover> <mi>E</mi> <mo>¯</mo> </mover> </semantics></math> plotted on a logarithmic scale for better reading in blue, the regular ENMO (without gravity estimation) is displayed as reference in dashed green, the doted lines are the activity thresholds. The involved activities were, in order: resting, desk working, walking, running, resting, walking and desk working.</p> Full article ">
16 pages, 5954 KiB  
Article
Interference Mitigation for Metro Train Location Based on Karhunen–Loeve Decomposition
by Xiwen Deng, Zhongliang Deng, Jingrong Liu, Zhenke Ding and Zhichao Zhang
Appl. Sci. 2023, 13(5), 3351; https://doi.org/10.3390/app13053351 - 6 Mar 2023
Cited by 1 | Viewed by 1470
Abstract
We propose a communication positioning integrated signal (CPIS) to achieve sub-meter positioning of metro trains. However, the electromagnetic environment of metro trains is complex, and the interference of radio frequency signals will reduce the accuracy of train positioning and affect the safe operation [...] Read more.
We propose a communication positioning integrated signal (CPIS) to achieve sub-meter positioning of metro trains. However, the electromagnetic environment of metro trains is complex, and the interference of radio frequency signals will reduce the accuracy of train positioning and affect the safe operation of trains. In this paper, an interference mitigation method for metro train positioning based on Karhunen–Loeve decomposition is proposed. The signal is orthogonally expanded, and the eigenvalues of the interference signal are obtained according to the distribution characteristics of the eigenvalues. The reconstructed interference signal is then subtracted from the received signal to achieve interference suppression. The experimental results demonstrate the effectiveness of the method in interference scenarios. Full article
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<p>The structure of the CPIS base station.</p> Full article ">Figure 2
<p>Two modes of interference. (<b>a</b>) The interfering signal source is stationary relative to the train positioning terminal; (<b>b</b>) The interfering signal source moves relative to the train positioning terminal.</p> Full article ">Figure 3
<p>The structure of the train positioning terminal.</p> Full article ">Figure 4
<p>The processing of KL decomposition algorithm.</p> Full article ">Figure 5
<p>The positioning signal is decomposed in KL with narrow-band interference (NBI) and interference-free (NI).</p> Full article ">Figure 6
<p>Test environment.</p> Full article ">Figure 7
<p>MSE of different interference mitigation algorithms under single-tone interference.</p> Full article ">Figure 8
<p>Histogram of eigenvalue distribution.</p> Full article ">Figure 9
<p>MSE of different interference mitigation algorithms under pulse signal interference.</p> Full article ">Figure 10
<p>Mitigation performance of KL algorithm under pulse interference with different duty cycle.</p> Full article ">Figure 11
<p>CAF of the waveform with PRN = 19. (<b>a</b>) CAF waveform before interference mitigation is performed; (<b>b</b>) In the chirp signal interference scenario, the waveform of CAF after interference mitigation is performed. JSNR = 30 dB.</p> Full article ">Figure 12
<p>Performance of different L in KL algorithm.</p> Full article ">Figure 13
<p>MSE of different interference mitigation algorithms under chrip signal interference.</p> Full article ">Figure 14
<p>Comparison of positioning accuracy of different algorithms in three jamming scenarios.</p> Full article ">
15 pages, 8601 KiB  
Article
Design of Low-Power ECG Sampling and Compression Circuit
by Zuoqin Zhao, Yufei Nai, Zhiguo Yu, Xin Xu, Xiaoyang Cao and Xiaofeng Gu
Appl. Sci. 2023, 13(5), 3350; https://doi.org/10.3390/app13053350 - 6 Mar 2023
Cited by 3 | Viewed by 1644
Abstract
Compressed Sensing (CS) has been applied to electrocardiogram monitoring in wireless sensor networks, but existing sampling and compression circuits consume too much hardware. This paper proposes a low-power and small-area sampling and compression circuit with an Analog-to-Digital Converter (ADC) and a CS module. [...] Read more.
Compressed Sensing (CS) has been applied to electrocardiogram monitoring in wireless sensor networks, but existing sampling and compression circuits consume too much hardware. This paper proposes a low-power and small-area sampling and compression circuit with an Analog-to-Digital Converter (ADC) and a CS module. The ADC adopts split capacitors to reduce hardware consumption and uses a calibration technique to decrease offset voltage. The CS module uses an approximate addition calculation for compression and stores the compressed data in pulsed latches. The proposed addition completes the accurate calculation of the high part and the approximate calculation of the low part. In a 55 nm CMOS process, the ADC has an area of 0.011 mm2 and a power consumption of 0.214 μW at 10 kHz. Compared with traditional design, the area and power consumption of the proposed CS module are reduced by 19.5% and 31.7%, respectively. The sampling and compression circuit area is 0.325 mm2, and the power consumption is 2.951 μW at 1.2 V and 100 kHz. The compressed data are reconstructed with a percentage root mean square difference of less than 2%. The results indicate that the proposed circuit has performance advantages of hardware consumption and reconstruction quality. Full article
(This article belongs to the Section Electrical, Electronics and Communications Engineering)
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<p>The sensor node structure.</p> Full article ">Figure 2
<p>The compression and storage structure.</p> Full article ">Figure 3
<p>The structure of SAR ADC.</p> Full article ">Figure 4
<p>The approximate addition calculation.</p> Full article ">Figure 5
<p>The storage units: (<b>a</b>) master–slave register; (<b>b</b>) pulsed latch.</p> Full article ">Figure 6
<p>The structure of the sampling and compression circuit.</p> Full article ">Figure 7
<p>The PRD of reconstruction signal of ten Records for two different calculation methods.</p> Full article ">Figure 8
<p>The Monte-Carlo simulation of the calibrated comparator.</p> Full article ">Figure 9
<p>The PVT simulation of the SAR ADC.</p> Full article ">Figure 10
<p>The Monte-Carlo simulation of the SAR ADC.</p> Full article ">Figure 11
<p>The functional simulation of the sampling and compression circuit.</p> Full article ">Figure 12
<p>The layout of the sampling and compression circuit.</p> Full article ">Figure 13
<p>The reconstruction results of the compressed data.</p> Full article ">
19 pages, 5423 KiB  
Article
Design and Implementation of an Active Vibration Control Algorithm Using Servo Actuator Control Installed in Series with a Spring-Damper
by Soo-Min Kim, Dae W. Kim and Moon K. Kwak
Appl. Sci. 2023, 13(5), 3349; https://doi.org/10.3390/app13053349 - 6 Mar 2023
Cited by 2 | Viewed by 5893
Abstract
The membrane-type air spring can be used to suppress lateral vibration of a vibration isolation table. However, compared to voice coil actuators, pneumatic actuators are difficult to use for precise vibration control, because servo valves have nonlinear dynamic characteristics. Therefore, actuators, such as [...] Read more.
The membrane-type air spring can be used to suppress lateral vibration of a vibration isolation table. However, compared to voice coil actuators, pneumatic actuators are difficult to use for precise vibration control, because servo valves have nonlinear dynamic characteristics. Therefore, actuators, such as voice coil actuators, can be placed in parallel with air springs, allowing force-type actuators to provide additional force to the system. These actuators generate force. In the case of a ball-screw mechanism device or a linear servomotor, it is an actuator that generates displacement. These actuators are represented as serial active systems. Serial active systems are structurally simpler than parallel active systems. However, there are very few studies on vibration isolation systems using serial active systems compared to parallel active systems. As the two are different types of systems, a new control algorithm suitable for the serial active system is needed. This study proposes a system in which an actuator capable of accurately controlling displacement is connected in series with a support spring-damper. A new active vibration control algorithm for the proposed control system is also developed, which is termed the position input and position output. The proposed control algorithm uses the displacement of the system as an input and outputs the desired displacement of the actuator installed in series with the damper and spring. The proposed control algorithm increases the damping at the target frequency and reduces the response of the system. Numerical studies and experiments were conducted on the single-degree-of-freedom and multi-degree-of-freedom systems. The results show the efficacy of the proposed control system and the novel control algorithm for the vibration suppression of the lateral vibration of a vibration isolation table. Full article
(This article belongs to the Special Issue Active Vibration and Noise Control)
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<p>Vibration control systems. (<b>a</b>) Passive system; (<b>b</b>) Semi-active system; (<b>c</b>) Parallel active system; (<b>d</b>) Serial active system.</p> Full article ">Figure 2
<p>Bode diagram for the proposed compensator. (<b>a</b>) Magnitude; (<b>b</b>) Phase.</p> Full article ">Figure 3
<p>Block diagram of the closed-loop system.</p> Full article ">Figure 4
<p>The Bode diagram of the closed-loop system. (<b>a</b>) Magnitude; (<b>b</b>) Phase.</p> Full article ">Figure 5
<p>Free vibration simulation.</p> Full article ">Figure 6
<p>The time history of displacement.</p> Full article ">Figure 7
<p>Experimental testbed.</p> Full article ">Figure 8
<p>Wiring diagram.</p> Full article ">Figure 9
<p>Simulink block diagram for the PIPO controller.</p> Full article ">Figure 10
<p>Free vibration experiment.</p> Full article ">Figure 11
<p>Free vibration response when the controller is turned on in the middle of the time.</p> Full article ">Figure 12
<p>Multi-degree-of-freedom model.</p> Full article ">Figure 13
<p>The bode diagram of the closed-loop system. (<b>a</b>) Magnitude; (<b>b</b>) Phase.</p> Full article ">Figure 14
<p>Free vibration experiment (the first mode excited).</p> Full article ">Figure 15
<p>Impulse time-response of the closed-loop system.</p> Full article ">Figure 16
<p>Experimental two-story building model.</p> Full article ">Figure 17
<p>Block diagram for the closed-loop system.</p> Full article ">Figure 18
<p>Simulink block diagram.</p> Full article ">Figure 19
<p>Free vibration experiment (the first mode excited).</p> Full article ">Figure 20
<p>Free vibration experiment (the second mode excited).</p> Full article ">
19 pages, 794 KiB  
Article
Temporal Extraction of Complex Medicine by Combining Probabilistic Soft Logic and Textual Feature Feedback
by Jinguang Gu, Daiwen Wang, Danyang Hu, Feng Gao and Fangfang Xu
Appl. Sci. 2023, 13(5), 3348; https://doi.org/10.3390/app13053348 - 6 Mar 2023
Cited by 1 | Viewed by 1597
Abstract
In medical texts, temporal information describes events and changes in status, such as medical visits and discharges. According to the semantic features, it is classified into simple time and complex time. The current research on time recognition usually focuses on coarse-grained simple time [...] Read more.
In medical texts, temporal information describes events and changes in status, such as medical visits and discharges. According to the semantic features, it is classified into simple time and complex time. The current research on time recognition usually focuses on coarse-grained simple time recognition while ignoring fine-grained complex time. To address this problem, based on the semantic concept of complex time in Clinical Time Ontology, we define seven basic features and eleven extraction rules and propose a complex medical time-extraction method. It combines probabilistic soft logic and textual feature feedback. The framework consists of two parts: (a) text feature recognition based on probabilistic soft logic, which is based on probabilistic soft logic for negative feedback adjustment; (b) complex medical time entity recognition based on text feature feedback, which is based on the text feature recognition model in (a) for positive feedback adjustment. Finally, the effectiveness of our approach is verified in text feature recognition and complex temporal entity recognition experimentally. In the text feature recognition task, our method shows the best F1 improvement of 18.09% on the Irregular Instant Collection type corresponding to utterance l17. In the complex medical temporal entity recognition task, the F1 metric improves the most significantly, by 10.42%, on the Irregular Instant Collection type. Full article
(This article belongs to the Special Issue Natural Language Processing (NLP) and Applications)
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<p>A medical record fragment containing temporal text with overlapping text features. In the figure, both blue and red fonts are time entities. * is used as a substitute for Chinese characters involving private information.</p> Full article ">Figure 2
<p>A medical record fragment containing temporal text with a large span of features described. In the figure, both blue and red fonts are time entities. * is used as a substitute for Chinese characters involving private information.</p> Full article ">Figure 3
<p>The overall framework of PSLF-CTR. The blue part is the structure of PSL-TRF model.</p> Full article ">Figure 4
<p>The PSL-TFR model structure.</p> Full article ">Figure 5
<p>The PSLF-CTR model structure.</p> Full article ">Figure 6
<p>The number of various types of time in the datasets.</p> Full article ">Figure 7
<p>The effect of <math display="inline"><semantics> <mi>λ</mi> </semantics></math> an <math display="inline"><semantics> <mi>α</mi> </semantics></math> taking value on model <span class="html-italic">F1</span>. (<b>a</b>) <math display="inline"><semantics> <mi>λ</mi> </semantics></math> taking the value on the PSL-TFR model, (<b>b</b>) <math display="inline"><semantics> <mi>α</mi> </semantics></math> taking the value on the PSLF-CTR model.</p> Full article ">
23 pages, 2315 KiB  
Article
A Flexible Session-Based Recommender System for e-Commerce
by Michail Salampasis, Alkiviadis Katsalis, Theodosios Siomos, Marina Delianidi, Dimitrios Tektonidis, Konstantinos Christantonis, Pantelis Kaplanoglou, Ifigeneia Karaveli, Chrysostomos Bourlis and Konstantinos Diamantaras
Appl. Sci. 2023, 13(5), 3347; https://doi.org/10.3390/app13053347 - 6 Mar 2023
Cited by 10 | Viewed by 4171
Abstract
Research into session-based recommendation systems (SBSR) has attracted a lot of attention, but each study focuses on a specific class of methods. This work examines and evaluates a large range of methods, from simpler statistical co-occurrence methods to embeddings and SotA deep learning [...] Read more.
Research into session-based recommendation systems (SBSR) has attracted a lot of attention, but each study focuses on a specific class of methods. This work examines and evaluates a large range of methods, from simpler statistical co-occurrence methods to embeddings and SotA deep learning methods. This paper analyzes theoretical and practical issues in developing and evaluating methods for SBSR in e-commerce applications, where user profiles and purchase data do not exist. The major tasks of SBRS are reviewed and studied, namely: prediction of next-item, next-basket and purchase intent. For physical retail shopping where no information about the current session exists, we treat the previous baskets purchased by the user as previous sessions drawn from a loyalty system. Mobile application scenarios such as push notifications and calling tune recommendations are also presented. Recommender models using graphs, embeddings and deep learning methods are studied and evaluated in all SBRS tasks using different datasets. Our work contributes a number of very interesting findings. Among all tested models, LSTMs consistently outperform other methods of SBRS in all tasks. They can be applied directly because they do not need significant fine-tuning. Additionally, they naturally model the dynamic browsing that happens in e-commerce web applications. On the other hand, another important finding of our work is that graph-based methods can be a good compromise between effectiveness and efficiency. Another important conclusion is that a “temporal locality principle” holds, implying that more recent behavior is better suited for prediction. In order to evaluate these systems further in realistic environments, several session-based recommender methods were integrated into an e-shop and an A/B testing method was applied. The results of this A/B testing are in line with the experimental results, which represents another important contribution of this paper. Finally, important parameters such as efficiency, application of business rules, re-ranking issues, and the utilization of hybrid methods are also considered and tested, providing comprehensive useful insights into SBRS and facilitating the transferability of this research work to other domains and recommendation scenarios. Full article
(This article belongs to the Special Issue Data Analysis and Mining)
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<p>The methodology of a flexible recommendation system. It involves the use cases of “e-commerce”, “web services” and “physical retail store” (yellow boxes). The relevant tasks for each case are shown in blue boxes. They are the prediction of the next item in an online session, the prediction of the intent to purchase, and the prediction of the next basket. The arrows indicate the relationship between the tasks and the corresponding use cases. The methods used to solve these tasks are shown in the green boxes. These include recurrent neural networks and graph-based methods using either statistical co-occurrence analysis or node similarity assessments. The methods are in turn based on the representation of the data. The representation can be used to make additional determinations.</p> Full article ">Figure 2
<p>LSTM design in the next-item task.</p> Full article ">Figure 3
<p>LSTM architecture used in the last-basket task.</p> Full article ">Figure 4
<p>Operation of our purchase intent method with the sliding window running from the start to the end of each session to obtain instances for training purposes.</p> Full article ">Figure 5
<p>Parameters determining a push notification policy.</p> Full article ">Figure 6
<p>Number of clicks produced by each recommender method.</p> Full article ">Figure 7
<p>Click-through rate achieved by our recommender method.</p> Full article ">
12 pages, 2759 KiB  
Communication
Multi-Objective Parametric Optimization Design for Mirrors Combined with Non-Dominated Sorting Genetic Algorithm
by Lu Sun, Bao Zhang, Ping Wang, Zhihong Gan, Pengpeng Han and Yijian Wang
Appl. Sci. 2023, 13(5), 3346; https://doi.org/10.3390/app13053346 - 6 Mar 2023
Cited by 2 | Viewed by 1579
Abstract
The process of intelligent multi-objective parametric optimization design for mirrors is discussed in detail in this paper, with the error of the mirror surface shape and the total mass being examined as the optimization objectives. The establishment of complex objective functions for solving [...] Read more.
The process of intelligent multi-objective parametric optimization design for mirrors is discussed in detail in this paper, with the error of the mirror surface shape and the total mass being examined as the optimization objectives. The establishment of complex objective functions for solving the optimization problem of the mirror surface shape error was realized, and manual modification of the model was avoided. Moreover, combining this with a non-dominated sorting genetic algorithm (NSGA) helped the Pareto front move towards an ideal optimal set of solutions. To verify the effectiveness of the proposed method, an aluminum alloy mirror with an aperture of 140 mm was taken as an example. The Pareto optimal solution set of the mass and surface shape error under 1 g gravity was obtained for finding the required solution and satisfying the optimization goal. In addition, this method is applicable to other complex structural design problems. Full article
(This article belongs to the Special Issue Advanced Optoelectronic Devices and Systems)
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<p>Optimization flowchart.</p> Full article ">Figure 2
<p>Data interaction diagram.</p> Full article ">Figure 3
<p>Fundamental structure of the mirror.</p> Full article ">Figure 4
<p>Pareto optimal solutions.</p> Full article ">Figure 5
<p>Surface shape error in X direction.</p> Full article ">Figure 6
<p>Surface shape error in Y direction.</p> Full article ">Figure 7
<p>Surface shape error in Z direction.</p> Full article ">
21 pages, 801 KiB  
Article
Does Context Matter? Effective Deep Learning Approaches to Curb Fake News Dissemination on Social Media
by Jawaher Alghamdi, Yuqing Lin and Suhuai Luo
Appl. Sci. 2023, 13(5), 3345; https://doi.org/10.3390/app13053345 - 6 Mar 2023
Cited by 12 | Viewed by 2856
Abstract
The prevalence of fake news on social media has led to major sociopolitical issues. Thus, the need for automated fake news detection is more important than ever. In this work, we investigated the interplay between news content and users’ posting behavior clues in [...] Read more.
The prevalence of fake news on social media has led to major sociopolitical issues. Thus, the need for automated fake news detection is more important than ever. In this work, we investigated the interplay between news content and users’ posting behavior clues in detecting fake news by using state-of-the-art deep learning approaches, such as the convolutional neural network (CNN), which involves a series of filters of different sizes and shapes (combining the original sentence matrix to create further low-dimensional matrices), and the bidirectional gated recurrent unit (BiGRU), which is a type of bidirectional recurrent neural network with only the input and forget gates, coupled with a self-attention mechanism. The proposed architectures introduced a novel approach to learning rich, semantical, and contextual representations of a given news text using natural language understanding of transfer learning coupled with context-based features. Experiments were conducted on the FakeNewsNet dataset. The experimental results show that incorporating information about users’ posting behaviors (when available) improves the performance compared to models that rely solely on textual news data. Full article
(This article belongs to the Special Issue Text Mining, Machine Learning, and Natural Language Processing)
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<p>BERT<math display="inline"><semantics> <msub> <mrow/> <mrow> <mi>b</mi> <mi>a</mi> <mi>s</mi> <mi>e</mi> </mrow> </msub> </semantics></math>-CNN-BiGRU-ATT architecture.</p> Full article ">Figure 2
<p>BERT<math display="inline"><semantics> <msub> <mrow/> <mrow> <mi>b</mi> <mi>a</mi> <mi>s</mi> <mi>e</mi> </mrow> </msub> </semantics></math>-BiGRU-CNN-ATT architecture.</p> Full article ">Figure 3
<p>BERT<math display="inline"><semantics> <msub> <mrow/> <mrow> <mi>b</mi> <mi>a</mi> <mi>s</mi> <mi>e</mi> </mrow> </msub> </semantics></math>-CNN-BiLSTM architecture.</p> Full article ">Figure 4
<p>Confusion matrix of BERT<math display="inline"><semantics> <msub> <mrow/> <mrow> <mi>b</mi> <mi>a</mi> <mi>s</mi> <mi>e</mi> </mrow> </msub> </semantics></math>-CNN-BiGRU-ATT in PolitiFact.</p> Full article ">Figure 5
<p>Confusion matrix of BERT<math display="inline"><semantics> <msub> <mrow/> <mrow> <mi>b</mi> <mi>a</mi> <mi>s</mi> <mi>e</mi> </mrow> </msub> </semantics></math>-BiGRU-CNN-ATT in PolitiFact.</p> Full article ">Figure 6
<p>Confusion Matrix of BERT<math display="inline"><semantics> <msub> <mrow/> <mrow> <mi>b</mi> <mi>a</mi> <mi>s</mi> <mi>e</mi> </mrow> </msub> </semantics></math>-CNN-BiGRU in PolitiFact.</p> Full article ">Figure 7
<p>Performance comparisons (%) of all models in PolitiFact.</p> Full article ">Figure 8
<p>Confusion matrix of BERT<math display="inline"><semantics> <msub> <mrow/> <mrow> <mi>b</mi> <mi>a</mi> <mi>s</mi> <mi>e</mi> </mrow> </msub> </semantics></math>-CNN-BiGRU-ATT in GossipCop.</p> Full article ">Figure 9
<p>Confusion Matrix of BERT<math display="inline"><semantics> <msub> <mrow/> <mrow> <mi>b</mi> <mi>a</mi> <mi>s</mi> <mi>e</mi> </mrow> </msub> </semantics></math>-BiGRU-CNN-ATT in GossipCop.</p> Full article ">Figure 10
<p>Confusion matrix of BERT<math display="inline"><semantics> <msub> <mrow/> <mrow> <mi>b</mi> <mi>a</mi> <mi>s</mi> <mi>e</mi> </mrow> </msub> </semantics></math>-CNN-BiGRU in GossipCop.</p> Full article ">Figure 11
<p>Performance comparisons (%) of all models in GossipCop.</p> Full article ">Figure 12
<p>Confusion matrix of BERT<math display="inline"><semantics> <msub> <mrow/> <mrow> <mi>b</mi> <mi>a</mi> <mi>s</mi> <mi>e</mi> </mrow> </msub> </semantics></math>-CNN-BiGRU-ATT in PolitiFact w/o user posting behavior features.</p> Full article ">Figure 13
<p>Confusion matrix of BERT<math display="inline"><semantics> <msub> <mrow/> <mrow> <mi>b</mi> <mi>a</mi> <mi>s</mi> <mi>e</mi> </mrow> </msub> </semantics></math>-BiGRU-CNN-ATT in PolitiFact w/o user posting behavior features.</p> Full article ">Figure 14
<p>Confusion matrix of BERT<math display="inline"><semantics> <msub> <mrow/> <mrow> <mi>b</mi> <mi>a</mi> <mi>s</mi> <mi>e</mi> </mrow> </msub> </semantics></math>-CNN-BiGRU in PolitiFact w/o user posting behavior features.</p> Full article ">Figure 15
<p>Confusion matrix of BERT<math display="inline"><semantics> <msub> <mrow/> <mrow> <mi>b</mi> <mi>a</mi> <mi>s</mi> <mi>e</mi> </mrow> </msub> </semantics></math>-CNN-BiGRU-ATT in GossipCop w/o user posting behavior features.</p> Full article ">Figure 16
<p>Confusion matrix of BERT<math display="inline"><semantics> <msub> <mrow/> <mrow> <mi>b</mi> <mi>a</mi> <mi>s</mi> <mi>e</mi> </mrow> </msub> </semantics></math>-BiGRU-CNN-ATT in GossipCop w/o user posting behavior features.</p> Full article ">Figure 17
<p>Confusion matrix of BERT<math display="inline"><semantics> <msub> <mrow/> <mrow> <mi>b</mi> <mi>a</mi> <mi>s</mi> <mi>e</mi> </mrow> </msub> </semantics></math>-CNN-BiGRU in GossipCop w/o user posting behavior features.</p> Full article ">Figure 18
<p>Performance comparisons (%) of models in PolitiFact w/o user posting behavior features.</p> Full article ">Figure 19
<p>Performance comparisons (%) of models in GossipCop w/o user posting behavior features.</p> Full article ">
17 pages, 2862 KiB  
Article
A Research on Fault Diagnosis of a USV Thruster Based on PCA and Entropy
by Ki-Beom Choo, Hyunjoon Cho, Jung-Hyeun Park, Jiafeng Huang, Dongwook Jung, Jihyeong Lee, Sang-Ki Jeong, Jongsu Yoon, Jinhun Choo and Hyeung-Sik Choi
Appl. Sci. 2023, 13(5), 3344; https://doi.org/10.3390/app13053344 - 6 Mar 2023
Cited by 6 | Viewed by 1912
Abstract
This study focuses on faults in the thrusters of unmanned surface vehicles, which are fatal to the integrity of their missions. As for the fault conditions, the breakage of the thruster blade and the entanglement of floating objects were selected, and a data-driven [...] Read more.
This study focuses on faults in the thrusters of unmanned surface vehicles, which are fatal to the integrity of their missions. As for the fault conditions, the breakage of the thruster blade and the entanglement of floating objects were selected, and a data-driven method was used to diagnose the faults. In the data-driven method, it is important to select the sensitive fault feature. In this study, vibration, current consumption, rotational speed and input voltage were selected as fault features. An experiment was conducted in an engineering water tank to obtain and analyze data on fault conditions to verify the validity of the selected features. In addition, a new fault diagnosis algorithm combining principal component analysis and Shannon entropy was applied for analyzing the correlations among fault features. This algorithm reduces the dimensionality of data while preserving their structure and characteristics, and diagnoses faults by quantifying entropy values. A fault is detected by comparing the entropy value and a predetermined threshold value, and is diagnosed by analyzing the entropy value and visualized 2D or 3D principal component results. Moreover, the fault diagnosis performance of the unmanned surface vehicle’s thruster was verified by analyzing the results for each fault condition. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2021)
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Figure 1

Figure 1
<p>General procedure of fault diagnosis.</p> Full article ">Figure 2
<p>Materials for reproducing various fault conditions. Clockwise from top left: thin rope, thick rope, net, 3 cm breakage blade, 2 cm breakage blade and 1 cm breakage blade.</p> Full article ">Figure 3
<p>Vibration generated by mass unbalance.</p> Full article ">Figure 4
<p>Configuration of the USV and fault diagnosis system. (<b>a</b>) The configuration of the USV; (<b>b</b>) The configuration of the fault diagnosis system.</p> Full article ">Figure 5
<p>Fault conditions applied in experiments.</p> Full article ">Figure 6
<p>Vibration data for each condition.</p> Full article ">Figure 7
<p>Current and RPM data for each condition. (<b>a</b>) Current data for each condition; (<b>b</b>) RPM data for each condition.</p> Full article ">Figure 8
<p>Fault diagnosis algorithm based on PCA and entropy.</p> Full article ">Figure 9
<p>Visualized 3D PCA result of the normal condition.</p> Full article ">Figure 10
<p>Visualized 3D PCA results for fault conditions associated significant data changes. (<b>a</b>) Thick-rope entanglement condition; (<b>b</b>) Net entanglement condition.</p> Full article ">Figure 11
<p>Visualized 3D PCA results for cases with small changes in data under fault conditions. (<b>a</b>) One-centimeter breakage condition; (<b>b</b>) Two-centimeter breakage condition; (<b>c</b>) Three-centimeter breakage condition; (<b>d</b>) Thin-rope entanglement condition.</p> Full article ">Figure 12
<p>Visualized 2D PCA results for cases with small changes in data under fault conditions (vibration and current planes). (<b>a</b>) One-centimeter breakage condition; (<b>b</b>) Two-centimeter breakage condition; (<b>c</b>) Three-centimeter breakage condition; (<b>d</b>) Thin-rope entanglement condition.</p> Full article ">
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