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Appl. Sci., Volume 11, Issue 24 (December-2 2021) – 591 articles

Cover Story (view full-size image): One of the urgent tasks of modern materials science is the search for new materials with improved optoelectronic properties for various applications of optoelectronics and photovoltaics. In this paper, using ab initio methods, we investigate the possibility of forming new types of van der Waals heterostructures based on monolayers of triangulated borophene, and monolayers of rhenium sulfide (ReS), and rhenium selenide (ReSe2), and predict their optoelectronic properties. The results of calculating the density of electronic states of the obtained supercells showed that the proposed types of heterostructures are characterized by a metallic type of conductivity.View this paper
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21 pages, 6127 KiB  
Review
Latest Advances in Common Signal Processing of Pulsed Thermography for Enhanced Detectability: A Review
by Yoonjae Chung, Seungju Lee and Wontae Kim
Appl. Sci. 2021, 11(24), 12168; https://doi.org/10.3390/app112412168 - 20 Dec 2021
Cited by 19 | Viewed by 4287
Abstract
Non-destructive testing (NDT) is a broad group of testing and analysis techniques used in science and industry to evaluate the properties of a material, structure, or system for characteristic defects and discontinuities without causing damage. Recently, infrared thermography is one of the most [...] Read more.
Non-destructive testing (NDT) is a broad group of testing and analysis techniques used in science and industry to evaluate the properties of a material, structure, or system for characteristic defects and discontinuities without causing damage. Recently, infrared thermography is one of the most promising technologies as it can inspect a large area quickly using a non-contact and non-destructive method. Moreover, thermography testing has proved to be a valuable approach for non-destructive testing and evaluation of structural stability of materials. Pulsed thermography is one of the active thermography technologies that utilizes external energy heating. However, due to the non-uniform heating, lateral heat diffusion, environmental noise, and limited parameters of the thermal imaging system, there are some difficulties in detecting and characterizing defects. In order to improve this limitation, various signal processing techniques have been developed through many previous studies. This review presents the latest advances and exhaustive summary of representative signal processing techniques used in pulsed thermography according to physical principles and thermal excitation sources. First, the basic concept of infrared thermography non-destructive testing is introduced. Next, the principle of conventional pulsed thermography and signal processing technologies for non-destructive testing are reviewed. Then, we review advances and recent advances in each signal processing. Finally, the latest research trends are reviewed. Full article
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11 pages, 3577 KiB  
Article
Recovery and Characterization of Orbital Angular Momentum Modes with Ghost Diffraction Holography
by Yanyan Huang, Vinu R.V., Ziyang Chen, Tushar Sarkar, Rakesh Kumar Singh and Jixiong Pu
Appl. Sci. 2021, 11(24), 12167; https://doi.org/10.3390/app112412167 - 20 Dec 2021
Cited by 2 | Viewed by 2635
Abstract
Orbital angular momentum (OAM) of optical vortex beams has been regarded as an independent physical dimension of light with predominant information-carrying potential. However, the presence of scattering environment and turbulent atmosphere scrambles the helical wavefront and destroys the orthogonality of modes in vortex [...] Read more.
Orbital angular momentum (OAM) of optical vortex beams has been regarded as an independent physical dimension of light with predominant information-carrying potential. However, the presence of scattering environment and turbulent atmosphere scrambles the helical wavefront and destroys the orthogonality of modes in vortex beam propagation. Here, we propose and experimentally demonstrate a new basis for the recovery of the OAM mode using a holographic ghost diffraction scheme. The technique utilizes the speckle field generated from a rotating diffuser for optical vortex mode encoding, and the fourth-order correlation of the speckle field for the efficient recovery of the associated modes. Furthermore, we successfully demonstrate the complex-field recovery of OAM modes by the adoption of a holography scheme in combination with the ghost diffraction system. We evaluate the feasibility of the approach by simulation and followed by experimental demonstration for the recovery of various sequentially encoded OAM modes. Finally, the efficacy of the recovered modes was quantitatively analyzed by an OAM mode analysis utilizing orthogonal projection scheme. Full article
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13 pages, 2989 KiB  
Article
Estimation of the Tapered Gutenberg-Richter Distribution Parameters for Catalogs with Variable Completeness: An Application to the Atlantic Ridge Seismicity
by Matteo Taroni, Jacopo Selva and Jiancang Zhuang
Appl. Sci. 2021, 11(24), 12166; https://doi.org/10.3390/app112412166 - 20 Dec 2021
Cited by 4 | Viewed by 2887
Abstract
The use of the tapered Gutenberg-Richter distribution in earthquake source models is rapidly increasing, allowing overcoming the definition of a hard threshold for the maximum magnitude. Here, we expand the classical maximum likelihood estimation method for estimating the parameters of the tapered Gutenberg-Richter [...] Read more.
The use of the tapered Gutenberg-Richter distribution in earthquake source models is rapidly increasing, allowing overcoming the definition of a hard threshold for the maximum magnitude. Here, we expand the classical maximum likelihood estimation method for estimating the parameters of the tapered Gutenberg-Richter distribution, allowing the use of a variable through-time magnitude of completeness. Adopting a well-established technique based on asymptotic theory, we also estimate the uncertainties relative to the parameters. Differently from other estimation methods for catalogs with a variable completeness, available for example for the classical truncated Gutenberg-Richter distribution, our approach does not need the assumption on the distribution of the number of events (usually the Poisson distribution). We test the methodology checking the consistency of parameter estimations with synthetic catalogs generated with multiple completeness levels. Then, we analyze the Atlantic ridge seismicity, using the global centroid moment tensor catalog, finding that our method allows better constraining distribution parameters, allowing the use more data than estimations based on a single completeness level. This leads to a sharp decrease in the uncertainties associated with the parameter estimation, when compared with existing methods based on a single time-independent magnitude of completeness. This also allows analyzing subsets of events, to deepen data analysis. For example, separating normal and strike-slip events, we found that they have significantly different but well-constrained corner magnitudes. Instead, without distinguishing for focal mechanism and considering all the events in the catalog, we obtain an intermediate value that is relatively less constrained from data, with an open confidence region. Full article
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13 pages, 3272 KiB  
Article
Differential Response of the Proteins Involved in Amino Acid Metabolism in Two Saccharomyces cerevisiae Strains during the Second Fermentation in a Sealed Bottle
by María del Carmen González-Jiménez, Juan Carlos Mauricio, Jaime Moreno-García, Anna Puig-Pujol, Juan Moreno and Teresa García-Martínez
Appl. Sci. 2021, 11(24), 12165; https://doi.org/10.3390/app112412165 - 20 Dec 2021
Cited by 2 | Viewed by 2516
Abstract
The traditional method for sparkling wine making consists of a second fermentation of a base wine followed by ageing in the same bottle that reaches the consumers. Nitrogen metabolism is the second most important process after carbon and takes place during wine fermentation [...] Read more.
The traditional method for sparkling wine making consists of a second fermentation of a base wine followed by ageing in the same bottle that reaches the consumers. Nitrogen metabolism is the second most important process after carbon and takes place during wine fermentation by yeast. Amino acids are the most numerous nitrogen compounds released by this process. They contribute to the organoleptic properties of the wines and, therefore, to their sensory quality. The main objective of this study is to compare the differential proteomic response of amino acid metabolism, specifically their proteins and their interactions in the G1 strain (unconventional yeast) during sparkling wine production versus the conventional P29 strain. One of the new trends in winemaking is the improvement of the organoleptic diversity of wine. We propose the use of unconventional yeast that shows desirable characteristics for the industry. For this purpose, these two yeasts were grown at sealed bottle conditions for the second fermentation (Champenoise method). No differences were obtained in the middle of fermentation between the yeast strains. The number of proteins identified, and the relationships established, were similar, highlighting lysine metabolism. At the end of the second fermentation, the difference between each strain was remarkable. Hardly any proteins were identified in unconventional versus conventional yeast. However, in both strains, the metabolism of sulfur amino acids, methionine, and cysteine obtained a greater number of proteins involved in these processes. The release of these amino acids to the medium would allow the yeast to balance the internal redox potential by reoxidation of NADPH. This study is focused on the search for a more complete knowledge of yeast metabolism, specifically the metabolism of amino acids, which are key compounds during the second fermentation. Full article
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24 pages, 5241 KiB  
Article
Improvement of Wheat Grain Yield Prediction Model Performance Based on Stacking Technique
by Changchun Li, Yilin Wang, Chunyan Ma, Weinan Chen, Yacong Li, Jingbo Li, Fan Ding and Zhen Xiao
Appl. Sci. 2021, 11(24), 12164; https://doi.org/10.3390/app112412164 - 20 Dec 2021
Cited by 4 | Viewed by 2793
Abstract
Crop growth and development is a dynamic and complex process, and the essence of yield formation is the continuous accumulation of photosynthetic products from multiple fertility stages. In this study, a new stacking method for integrating multiple growth stages information was proposed to [...] Read more.
Crop growth and development is a dynamic and complex process, and the essence of yield formation is the continuous accumulation of photosynthetic products from multiple fertility stages. In this study, a new stacking method for integrating multiple growth stages information was proposed to improve the performance of the winter wheat grain yield (GY) prediction model. For this purpose, crop canopy hyperspectral reflectance and leaf area index (LAI) data were obtained at the jointing, flagging, anthesis and grain filling stages. In this case, 15 vegetation indices and LAI were used as input features of the elastic network to construct GY prediction models for single growth stage. Based on Stacking technique, the GY prediction results of four single growth stages were integrated to construct the ensemble learning framework. The results showed that vegetation indices coupled LAI could effectively overcome the spectral saturation phenomenon, the validated R2 of each growth stage was improved by 10%, 22.5%, 3.6% and 10%, respectively. The stacking method provided more stable information with higher prediction accuracy than the individual fertility results (R2 = 0.74), and the R2 of the model validation phase improved by 236%, 51%, 27.6%, and 12.1%, respectively. The study can provide a reference for GY prediction of other crops. Full article
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14 pages, 2785 KiB  
Article
From Feather to Adsorbent: Keratin Extraction, Chemical Modification, and Fe(III) Removal from Aqueous Solution
by Sujuan Pan, Changqing Wang, Yibo Wang and Rongmin Wang
Appl. Sci. 2021, 11(24), 12163; https://doi.org/10.3390/app112412163 - 20 Dec 2021
Viewed by 2466
Abstract
In this work, feather keratin was extracted from the waste feather of chicken via alkyd pretreatment and reduction method, the extraction rate is above 85%. The molecular weight and aggregation morphology of feather keratin in an aqueous environment were characterized by 18-angle laser [...] Read more.
In this work, feather keratin was extracted from the waste feather of chicken via alkyd pretreatment and reduction method, the extraction rate is above 85%. The molecular weight and aggregation morphology of feather keratin in an aqueous environment were characterized by 18-angle laser light scattering gel permeation chromatography and field emission transmission electron microscopy. The relationship between the structure and properties of feather keratin is discussed. The 1-(3-dimethylaminopropyl) -3-ethylcarbondiimide hydrochloride and N-hydroxysuccinimide were used as activation system and cross-linkage. The gallic acid was used as modification reagent and was bonded to feather keratin chains; meanwhile, feather keratin chains were cross-linked through covalent bonds obtained the novel adsorbent (named as GA-FK gel). The GA-FK gel was investigated by IR, SEM, TGA, XRD, and BET methods. The results indicated that GA molecules successfully bonded to feather keratin chains and cross-linked between feather keratin chains. The GA-FK gel was found to have a three-dimensional network structure with abundant mesopores. Its pore size range is 1.8~90 nm; average pore size is 19.6 nm. Its specific surface area is 7.17 m2·g−1. In addition, GA-FK gel was applied to remove Fe(III) in water. The maximum adsorption capacity was 319.0 mg·g−1. The adsorption process of GA-FK gel to Fe(III) presents a typical two-stage pattern accompanied with swelling. The adsorption kinetics of GA-FK gel to Fe(III) follows the quasi-second-order model, the adsorption isotherm follows the Freundlich model. Therefore, the adsorption mechanism is non-specific adsorption. Full article
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27 pages, 8710 KiB  
Article
Assessment of the Durability of Threaded Joints
by Žilvinas Bazaras, Mindaugas Leonavičius, Vaidas Lukoševičius and Laurencas Raslavičius
Appl. Sci. 2021, 11(24), 12162; https://doi.org/10.3390/app112412162 - 20 Dec 2021
Cited by 3 | Viewed by 2831
Abstract
The article deals with the determination of the resistance to cyclic loading of the threaded joints of pressure vessels and defective elements according to the failure mechanics criteria. Theoretical and experimental studies do not provide a sufficient basis for the existing calculation methods [...] Read more.
The article deals with the determination of the resistance to cyclic loading of the threaded joints of pressure vessels and defective elements according to the failure mechanics criteria. Theoretical and experimental studies do not provide a sufficient basis for the existing calculation methods for the cyclic strength of the threaded joints of pressure vessels. The short crack kinetics in the threaded joints, a shakedown in one of the joint elements of pressure vessels, i.e., in the bolt or stud, has not been studied sufficiently. The calculation methods designed and improved within the study were based on theoretical and experimental investigations and were simplified for convenient application to engineering practice. The findings could be used to investigate the shakedown of studs of a different cross-section with an initiating and propagating crack. Value: the developed model for the assessment of durability of the threaded joints covers the patterns of resistance to cyclic failure (limit states: crack initiation, propagation, final failure) and shakedown (limit states: progressive shape change and plastic failure). Analysis-based solutions of plastic failure conditions and progressive shape change were accurate (the result was reached using a two-sided approach; the solutions were obtained in view of the parameters of the cyclic failure process in the stud (bolt) and based on experimental investigations of the threaded joints). Full article
(This article belongs to the Special Issue Mechanical Engineering in Europe)
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12 pages, 312 KiB  
Article
Efficient Lattice-Based Cryptosystems with Key Dependent Message Security
by Bo Yang, Ruwei Huang and Jianan Zhao
Appl. Sci. 2021, 11(24), 12161; https://doi.org/10.3390/app112412161 - 20 Dec 2021
Cited by 1 | Viewed by 2082
Abstract
Key-dependent message (KDM) security is of great research significance, to better analyse and solve the potential security problems in complex application scenarios. Most of the current KDM security schemes are based on traditional hard mathematical problems, where the public key and ciphertext are [...] Read more.
Key-dependent message (KDM) security is of great research significance, to better analyse and solve the potential security problems in complex application scenarios. Most of the current KDM security schemes are based on traditional hard mathematical problems, where the public key and ciphertext are not compact enough, and make the ciphertext size grow linearly with the degree of the challenge functions. To solve the above problems and the inefficient ciphertext operation, the authors propose a compact lattice-based cryptosystem with a variant of the RLWE problem, which applies an invertible technique to obtain the RLWE* problem. It remains hard after the modification from the RLWE problem. Compared with the ACPS scheme, our scheme further expands the set of challenge functions based on the affine function of the secret key, and the size of public key and ciphertext is O˜(n), which is independent of the challenge functions. In addition, this scheme enjoys a high level of efficiency, the cost of encryption and decryption is only ploylog(n) bit operations per message symbol, and we also prove that our scheme is KDM-CPA secure under the RLWE* assumption. Full article
20 pages, 3050 KiB  
Article
Ambulance Locations in a Tiered Emergency Medical System in a City
by Peter Jankovič and Ľudmila Jánošíková
Appl. Sci. 2021, 11(24), 12160; https://doi.org/10.3390/app112412160 - 20 Dec 2021
Cited by 5 | Viewed by 2980
Abstract
This paper deals with optimizing the location of ambulance stations in a two-tiered emergency medical system in an urban environment. Several variants of station distribution are calculated by different mathematical programming models and are evaluated by a detailed computer simulation model. A new [...] Read more.
This paper deals with optimizing the location of ambulance stations in a two-tiered emergency medical system in an urban environment. Several variants of station distribution are calculated by different mathematical programming models and are evaluated by a detailed computer simulation model. A new modification of the modular capacitated location model is proposed. Two ways of demand modelling are applied; namely, the aggregation of the ambient population and the aggregation of permanent residents at the street level. A case study of the city of Prešov, Slovakia is used to assess the models. The performance of the current and proposed sets of locations is evaluated using real historical data on ambulance trips. Computer simulation demonstrates that the modular capacitated location model, with the ambient population demand, significantly reduces the average response time to high-priority patients (by 79 s in the city and 62 s in the district) and increases the percentage of high-priority calls responded to within 8 min (by almost 4% in the city and 5% in the district). Our findings show that a significant improvement in the availability of the service can be achieved when ambulances are not accumulated at a few stations but rather spread over the city territory. Full article
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26 pages, 12978 KiB  
Article
Intelligent Robotic Palletizer System
by Jeng-Dao Lee, Chen-Huan Chang, En-Shuo Cheng, Chia-Chen Kuo and Chia-Ying Hsieh
Appl. Sci. 2021, 11(24), 12159; https://doi.org/10.3390/app112412159 - 20 Dec 2021
Cited by 3 | Viewed by 4372
Abstract
In the global wave of automation, logistics and manufacturing are indispensable and important industries. Among them, the related automatic warehousing system is even more urgently needed. There are quite a few cases of using robotic arms in the current industry cargo stacking operations. [...] Read more.
In the global wave of automation, logistics and manufacturing are indispensable and important industries. Among them, the related automatic warehousing system is even more urgently needed. There are quite a few cases of using robotic arms in the current industry cargo stacking operations. Traditional operations require engineers to plan the stacking path for the robotic arm. If the size of the object changes, it will take extra time to re-plan the work path. Therefore, in recent years, quite a lot of automatic palletizing software has been developed; however, none of it has a detection mechanism for stacking correctness and personnel safety. As a result, in this research, an intelligent robotic palletizer system is developed based on a self-developed symmetrical algorithm to stack the goods in a staggered arrangement to ensure the overall structure. Innovatively, it is proposed to check the arrangement status and warnings during the visual stack inspection to ensure the correctness of the stacking process. Besides, an AI algorithm is imported to ensure that personnel cannot enter the set dangerous area during the work of the robotic arm to improve safety during stacking. In addition to uploading the relevant data to the cloud database in real time, the stacking process combined database and vision system also provide users with real-time monitoring of system information. Full article
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17 pages, 38731 KiB  
Article
Development and Evaluation of Low-Damage Maize Snapping Mechanism Based on Deformation Energy Conversion
by Zhilong Zhang and Aijun Geng
Appl. Sci. 2021, 11(24), 12158; https://doi.org/10.3390/app112412158 - 20 Dec 2021
Cited by 2 | Viewed by 2212
Abstract
Reducing ear damage is the key to improving the quality of maize harvests. In order to reduce the impact and damage of the ear caused by the ear snapping mechanism, this paper proposes a method to convert ear deformation energy during collision into [...] Read more.
Reducing ear damage is the key to improving the quality of maize harvests. In order to reduce the impact and damage of the ear caused by the ear snapping mechanism, this paper proposes a method to convert ear deformation energy during collision into elastic potential energy in the ear snapping mechanism. According to the above method, a low-damage maize snapping mechanism was designed. In order to verify the feasibility of energy conversion in reducing damage, the dynamic model of the contact between the ear and the snapping plate was established, and a dynamic simulation analysis was carried out based on the finite element method (FEM). In order to obtain better parameters for the improved mechanism, a test rig was established, after which a performance test was carried out on the test rig. The results showed that the primary and secondary order that affected the ear damage rate was the rotational speed of the snapping roller, the spring stiffness and the forward speed. The data processing software Design Expert was used to optimize the parameters, it was concluded that when the rotational speed was 805 r·min−1, the forward speed was 1.29 m·s−1, the spring stiffness was 33.5 N·mm−1, the model predicted that the ear damage rate was 0.023%. Therefore, this paper could provide further reference for research into maize low-damage ear snapping technology. Full article
(This article belongs to the Section Agricultural Science and Technology)
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15 pages, 5657 KiB  
Article
Design and Implementation of New Coplanar FA Circuits without NOT Gate and Based on Quantum-Dot Cellular Automata Technology
by Mohsen Vahabi, Pavel Lyakhov, Ali Newaz Bahar and Khan A. Wahid
Appl. Sci. 2021, 11(24), 12157; https://doi.org/10.3390/app112412157 - 20 Dec 2021
Cited by 8 | Viewed by 3085
Abstract
The miniaturization of electronic devices and the inefficiency of CMOS technology due to the development of integrated circuits and its lack of responsiveness at the nanoscale have led to the acquisition of nanoscale technologies. Among these technologies, quantum-dot cellular automata (QCA) is considered [...] Read more.
The miniaturization of electronic devices and the inefficiency of CMOS technology due to the development of integrated circuits and its lack of responsiveness at the nanoscale have led to the acquisition of nanoscale technologies. Among these technologies, quantum-dot cellular automata (QCA) is considered one of the possible replacements for CMOS technology because of its extraordinary advantages, such as higher speed, smaller area, and ultra-low power consumption. In arithmetic and comparative circuits, XOR logic is widely used. The construction of arithmetic logic circuits using AND, OR, and NOT logic gates has a higher design complexity. However, XOR gate design has a lower design complexity. Hence, the efficient and optimized XOR logic gate is very important. In this article, we proposed a new XOR gate based on cell-level methodology, with the expected output achieved by the influence of the cells on each other; this design method caused less delay. However, this design was implemented without the use of inverter gates and crossovers, as well as rotating cells. Using the proposed XOR gate, two new full adder (FA) circuits were designed. The simulation results indicate the advantage of the proposed designs compared with previous structures. Full article
(This article belongs to the Special Issue Advanced Compound Semiconductor)
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26 pages, 3885 KiB  
Article
Exploring Methane Emission Drivers in Wetlands: The Cases of Massaciuccoli and Porta Lakes (Northern Tuscany, Italy)
by Stefania Venturi, Franco Tassi, Jacopo Cabassi, Antonio Randazzo, Marta Lazzaroni, Francesco Capecchiacci, Barbara Vietina and Orlando Vaselli
Appl. Sci. 2021, 11(24), 12156; https://doi.org/10.3390/app112412156 - 20 Dec 2021
Cited by 4 | Viewed by 2870
Abstract
Wetlands are hotspots of CH4 emissions to the atmosphere, mainly sustained by microbial decomposition of organic matter in anoxic sediments. Several knowledge gaps exist on how environmental drivers shape CH4 emissions from these ecosystems, posing challenges in upscaling efforts to estimate [...] Read more.
Wetlands are hotspots of CH4 emissions to the atmosphere, mainly sustained by microbial decomposition of organic matter in anoxic sediments. Several knowledge gaps exist on how environmental drivers shape CH4 emissions from these ecosystems, posing challenges in upscaling efforts to estimate global emissions from waterbodies. In this work, CH4 and CO2 diffusive fluxes, along with chemical and isotopic composition of dissolved ionic and gaseous species, were determined from two wetlands of Tuscany (Italy): (i) Porta Lake, a small wetland largely invaded by Phragmites australis reeds experiencing reed die-back syndrome, and (ii) Massaciuccoli Lake, a wide marsh area including open-water basins and channels affected by seawater intrusion and eutrophication. Both wetlands were recognized as net sources of CH4 to the atmosphere. Our data show that the magnitude of CH4 diffusive emission was controlled by CH4 production and consumption rates, being mostly governed by (i) water temperature and availability of labile carbon substrates and (ii) water column depth, wind exposure and dissolved O2 contents, respectively. This evidence suggests that the highest CH4 diffusive fluxes were sustained by reed beds, providing a large availability of organic matter supporting acetoclastic methanogenesis, with relevant implications for global carbon budget and future climate models. Full article
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26 pages, 8760 KiB  
Article
Research in Sustainable Energy Systems at the Department of Management and Engineering during the First 15 Years of 2000
by Giacomo Bagarella, Filippo Busato, Francesco Castellotti, Andrea D’Ascanio, Renato Lazzarin, Fabio Minchio, Daniele Nardotto, Marco Noro and Lorenzo Zamboni
Appl. Sci. 2021, 11(24), 12155; https://doi.org/10.3390/app112412155 - 20 Dec 2021
Viewed by 2954
Abstract
At the Department of Management and Engineering (DTG) of the University of Padova (Italy), the research team led by Prof. Renato Lazzarin, formed by the authors, worked during the first fifteen years of the millennium on different topics focused on sustainable technologies for [...] Read more.
At the Department of Management and Engineering (DTG) of the University of Padova (Italy), the research team led by Prof. Renato Lazzarin, formed by the authors, worked during the first fifteen years of the millennium on different topics focused on sustainable technologies for energy production and utilization in buildings. Both experimental and theoretical/modeling studies were carried out, all sharing the evaluation of energy performance and sustainability: From the life cycle assessment and life cycle cost of building insulation materials in Italy, to the measurement of energy performance of a green roof, to the experimental measurement of different photovoltaic/thermal modules, to the development of a simulation software for direct and indirect evaporative cooling techniques, to the evaluation of different energy savings techniques for refrigeration and air conditioning in supermarkets, to an extensive analysis of the urban heat island effect in the city of Padova. The paper summarizes the main theoretical and experimental approaches, providing the methods adopted in each line of research. The main results of the studies conducted during the fifteen-year period are described and commented on, some of which were a well-established reference for the following literature. Full article
(This article belongs to the Special Issue New Challenges in the Control of Renewable Energy Sources)
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19 pages, 3928 KiB  
Article
A Macro–Micro Damage Model for Rock under Compression Loading
by Zhixiong Peng, Yawu Zeng, Xi Chen and Shufan Cheng
Appl. Sci. 2021, 11(24), 12154; https://doi.org/10.3390/app112412154 - 20 Dec 2021
Cited by 3 | Viewed by 2362
Abstract
Rock damage caused by its microcrack growth has a great influence on the deformation and strength properties of rock under compressive loading. Considering the interaction of wing cracks and the additional stress caused by rock bridge damage, a new calculation model for the [...] Read more.
Rock damage caused by its microcrack growth has a great influence on the deformation and strength properties of rock under compressive loading. Considering the interaction of wing cracks and the additional stress caused by rock bridge damage, a new calculation model for the mode-I stress intensity factor at wing crack tip was proposed in this study. The proposed calculation model for the stress intensity factor can not only accurately predict the cracking angle of wing crack, but can also simulate the whole range of variation of wing crack length from being extremely short to very long. Based on the modified stress intensity factor, a macro–micro damage model for rock materials was also established by combining the relationship between microcrack growth and macroscopic strain. The proposed damage model was verified with the results from the conventional triaxial compression test of sandstone sample. The results show that the proposed damage model can not only continuously simulate the stress-strain curves under different confining pressures, but also can better predict the peak strength. Furthermore, the sensitivities of initial crack size, crack friction coefficient, fracture toughness, initial damage and parameter m on the stress-strain relationship are discussed. The results can provide a theoretical reference for understanding the effect of microcrack growth on the progressive failure of rock under the compressive loading. Full article
(This article belongs to the Section Civil Engineering)
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16 pages, 8819 KiB  
Article
Analysis of Long-Term Prestress Loss in Prestressed Concrete (PC) Structures Using Fiber Bragg Grating (FBG) Sensor-Embedded PC Strands
by Sung-Tae Kim, Young-Soo Park, Chul-Hwan Yoo, Soobong Shin and Young-Hwan Park
Appl. Sci. 2021, 11(24), 12153; https://doi.org/10.3390/app112412153 - 20 Dec 2021
Cited by 3 | Viewed by 2072
Abstract
This study aims to develop a prestressed concrete steel (PC) strand with an embedded optical Fiber Bragg Grating (FBG) sensor, which has been developed by the Korea Institute of Civil Engineering and Building Technology since 2013. This new strand is manufactured by replacing [...] Read more.
This study aims to develop a prestressed concrete steel (PC) strand with an embedded optical Fiber Bragg Grating (FBG) sensor, which has been developed by the Korea Institute of Civil Engineering and Building Technology since 2013. This new strand is manufactured by replacing the steel core of the normal PC strand with a carbon-fiber-reinforced polymer (CFRP) rod with excellent tensile strength and durability. Because this new strand is manufactured using the pultrusion method, which is a composite material manufacturing process, with an optical fiber sensor embedded in the inner center of the CFRP Rod, it ensures full composite action as well as proper function of the sensor. In this study, a creep test for maintaining a constant load and a relaxation test for maintaining a constant displacement were performed on the proposed sensor-type PC strand. Each of the two tests was conducted for more than 1000 h, and the long-term performance verification of the sensor-type PC strand was only completed by comparing the performance with that of a normal PC strand. The test specimens were fabricated by applying an optical fiber sensor-embedded PC strand, which had undergone long-term performance verification tests, to a reinforced concrete beam. Depending on whether grout was injected in the duct, the specimens were classified into composite and non-composite specimens. A hydraulic jack was used to prestress the fabricated beam specimens, and the long-term change in the prestress force was observed for more than 1600 days using the embedded optical fiber sensor. The experimental results were compared with the analytical results to determine the long-term prestress loss obtained through finite-element analysis based on various international standards. Full article
(This article belongs to the Section Civil Engineering)
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16 pages, 4595 KiB  
Article
Experimental Investigation on the Behavior of Gravelly Sand Reinforced with Geogrid under Cyclic Loading
by Jia-Quan Wang, Zhen-Chao Chang, Jian-Feng Xue, Zhi-Nan Lin and Yi Tang
Appl. Sci. 2021, 11(24), 12152; https://doi.org/10.3390/app112412152 - 20 Dec 2021
Cited by 4 | Viewed by 2257
Abstract
In view of the dynamic response of geogrid-reinforced gravel under high-speed train load, this paper explores the dynamic characteristics of geogrid-reinforced gravel under semi-sine wave cyclic loading. A number of large scale cyclic triaxial tests were performed on saturated gravelly soil reinforced with [...] Read more.
In view of the dynamic response of geogrid-reinforced gravel under high-speed train load, this paper explores the dynamic characteristics of geogrid-reinforced gravel under semi-sine wave cyclic loading. A number of large scale cyclic triaxial tests were performed on saturated gravelly soil reinforced with geogrid to study the influence of the number of reinforcement layers and loading frequencies on the dynamic responses of reinforced gravelly sand subgrade for high speed rail track. The variation of cumulative axial and volumetric strains, excess pore pressure and resilient modulus with number of loading cycles, loading frequency, and reinforcement arrangement are analyzed. The test results reveal that the cumulative axial strain decreases as the number of reinforcement layers increases, but increases with loading frequency. The resilience modulus increases with the number of reinforcement layers, but decreases as the loading frequency increases. The addition of geogrid can reduce the excess pore water pressure of the sample, but it can slightly enhance the rubber mold embedding effect of the sand sample. As the loading frequency increases, the rubber mold embedding effect gradually weakens. Full article
(This article belongs to the Special Issue Advances in Geosynthetics)
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12 pages, 7719 KiB  
Article
Monolithic 3D Inverter with Interface Charge: Parameter Extraction and Circuit Simulation
by Tae Jun Ahn, Sung Kyu Lim and Yun Seop Yu
Appl. Sci. 2021, 11(24), 12151; https://doi.org/10.3390/app112412151 - 20 Dec 2021
Cited by 2 | Viewed by 1908
Abstract
We have simulated a monolithic three-dimensional inverter (M3DINV) structure by considering the interfacial trap charges generated thermally during the monolithic three-dimensional integration process. We extracted the SPICE model parameters from M3DINV structures with two types of inter-layer dielectric thickness TILD (=10,100 nm) [...] Read more.
We have simulated a monolithic three-dimensional inverter (M3DINV) structure by considering the interfacial trap charges generated thermally during the monolithic three-dimensional integration process. We extracted the SPICE model parameters from M3DINV structures with two types of inter-layer dielectric thickness TILD (=10,100 nm) using the extracted interface trap charge distribution of the previous study. Logic circuits, such as inverters (INVs), ring oscillators (ROs), a 2 to 1 multiplexer (MUX), and D flip-flop and 6-transistor static random-access memory (6T SRAM) containing M3DINVs, were simulated using the extracted model parameters, and simulation results both with and without interface trap charges were compared. The extracted model parameters reflected current reduction, threshold voltage increase, and subthreshold swing (SS) degradation due to the interface trap charge. HSPICE simulation results of the fanout-3 (FO3) ring oscillator considering the interface trap charges showed a 20% reduction in frequency and a 30% increase in propagation delay compared to those without the interface trap charges. The propagation delays of the 2 × 1 MUX and D flip-flop with the interface trap charges were approximately 78.2 and 39.6% greater, respectively, than those without the interface trap charges. The retention static noise margin (SNM) of the SRAM increased by 16 mV (6.4%) and the read static noise margin (SNM) of SRAM decreased by 43 mV (35.8%) owing to the interface trap charge. The circuit simulation results revealed that the propagation delay increases owing to the interface trap charges. Therefore, it is necessary to fully consider the propagation delay of the logic circuit due to the generated interface trap charges when designing monolithic 3D integrated circuits. Full article
(This article belongs to the Special Issue Device Modeling for TCAD and Circuit Simulation)
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10 pages, 2327 KiB  
Article
Improving the Energy Efficiency of an Existing Building by Dynamic Numerical Simulation
by Lelia Letitia Popescu, Razvan Stefan Popescu and Tiberiu Catalina
Appl. Sci. 2021, 11(24), 12150; https://doi.org/10.3390/app112412150 - 20 Dec 2021
Cited by 5 | Viewed by 2036
Abstract
Nowadays, the enhancement of the existing building stock energy performance is a priority. To promote building energy renovation, the European Committee asks Member States to define retrofit strategies, finding cost-effective solutions. This research aims to investigate the relationship between the initial characteristics of [...] Read more.
Nowadays, the enhancement of the existing building stock energy performance is a priority. To promote building energy renovation, the European Committee asks Member States to define retrofit strategies, finding cost-effective solutions. This research aims to investigate the relationship between the initial characteristics of an existing residential buildings and different types of retrofit solutions in terms of final/primary energy consumption and CO2 emissions. A multi-objective optimization has been carried out using experimental data in DesignBuilder dynamic simulation tool. Full article
(This article belongs to the Topic Soft Computing)
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17 pages, 5322 KiB  
Article
Development of an Online Detection Setup for Dissolved Gas in Transformer Insulating Oil
by Yang Chen, Zhentao Wang, Zhao Li, Hongquan Zheng and Jingmin Dai
Appl. Sci. 2021, 11(24), 12149; https://doi.org/10.3390/app112412149 - 20 Dec 2021
Cited by 13 | Viewed by 2490
Abstract
The type and concentration of dissolved gases in transformer insulating oil are used to assess transformer conditions. In this paper, an online detection setup for measuring the concentration of multicomponent gases dissolved in transformer insulating oil is developed, which consists of an oil-gas [...] Read more.
The type and concentration of dissolved gases in transformer insulating oil are used to assess transformer conditions. In this paper, an online detection setup for measuring the concentration of multicomponent gases dissolved in transformer insulating oil is developed, which consists of an oil-gas separation system and an optical system for acquiring the transformer status in real time. The oil-gas separation system uses low pressure, constant temperature, and low-frequency stirring as working conditions for degassing large-volume oil samples based on modified headspace degassing. The optical system uses tunable diode laser absorption spectroscopy (TDLAS) to determine the gas concentration. Six target gases (methane, ethylene, ethane, acetylene, carbon monoxide, and carbon dioxide) were detected by three near-infrared lasers (1569, 1684, and 1532 nm). The stability of the optical system was improved by the common optical path formed by time-division multiplexing (TDM) technology. The calibration experiments show that the second harmonics and the concentrations of the six gases are linear. A comparison experiment with gas chromatography (GC) demonstrates that the error of acetylene reaches the nL/L level, while the other gases reach the μL/L level. The data conforms to the power industry testing standards, and the state of the transformer is analyzed by the detected six characteristic gases. The setup provides an effective basis for the online detection of dissolved gas in transformer insulating oil. Full article
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21 pages, 714 KiB  
Article
WAMs Based Eigenvalue Space Model for High Impedance Fault Detection
by Gian Paramo and Arturo S. Bretas
Appl. Sci. 2021, 11(24), 12148; https://doi.org/10.3390/app112412148 - 20 Dec 2021
Cited by 7 | Viewed by 1906
Abstract
High impedance faults present unique challenges for power system protection engineers. The first challenge is the detection of the fault, given the low current magnitudes. The second challenge is to locate the fault to allow corrective measures to be taken. Corrective actions are [...] Read more.
High impedance faults present unique challenges for power system protection engineers. The first challenge is the detection of the fault, given the low current magnitudes. The second challenge is to locate the fault to allow corrective measures to be taken. Corrective actions are essential as they mitigate safety hazards and equipment damage. The problem of high impedance fault detection and location is not a new one, and despite the safety and reliability implications, relatively few efforts have been made to find a general solution. This work presents a hybrid data driven and analytical-based model for high impedance fault detection in distribution systems. The first step is to estimate a state space model of the power line being monitored. From the state space model, eigenvalues are calculated, and their dynamic behavior is used to develop zones of protection. These zones of protection are generated analytically using machine learning tools. High impedance faults are detected as they drive the eigenvalues outside of their zones. A metric called eigenvalue drift coefficient was formulated in this work to facilitate the generalization of this solution. The performance of this technique is evaluated through case studies based on the IEEE 5-Bus system modeled in Matlab. Test results are encouraging indicating potential for real-life applications. Full article
(This article belongs to the Special Issue Intelligent Fault Diagnosis of Power System)
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29 pages, 4747 KiB  
Article
Collaborative Workplace Design: A Knowledge-Based Approach to Promote Human–Robot Collaboration and Multi-Objective Layout Optimization
by Andrea Rega, Castrese Di Marino, Agnese Pasquariello, Ferdinando Vitolo, Stanislao Patalano, Alessandro Zanella and Antonio Lanzotti
Appl. Sci. 2021, 11(24), 12147; https://doi.org/10.3390/app112412147 - 20 Dec 2021
Cited by 13 | Viewed by 3476
Abstract
The innovation-driven Industry 5.0 leads us to consider humanity in a prominent position as the center of the manufacturing field even more than Industry 4.0. This pushes us towards the hybridization of manufacturing plants promoting a full collaboration between humans and robots. However, [...] Read more.
The innovation-driven Industry 5.0 leads us to consider humanity in a prominent position as the center of the manufacturing field even more than Industry 4.0. This pushes us towards the hybridization of manufacturing plants promoting a full collaboration between humans and robots. However, there are currently very few workplaces where effective Human–Robot Collaboration takes place. Layout designing plays a key role in assuring safe and efficient Human–Robot Collaboration. The layout design, especially in the context of collaborative robotics, is a complex problem to face, since it is related to safety, ergonomics, and productivity aspects. In the current work, a Knowledge-Based Approach (KBA) is adopted to face the complexity of the layout design problem. The framework resulting from the KBA allows for developing a modeling paradigm that enables us to define a streamlined approach for the layout design. The proposed approach allows for placing resource within the workplace according to a defined optimization criterion, and also ensures compliance with various standards. This approach is applied to an industrial case study in order to prove its feasibility. A what-if analysis is performed by applying the proposed approach. Changing three control factors (i.e., minimum distance, robot speed, logistic space configuration) on three levels, in a Design of Experiments, 27 layout configurations of the same workplace are generated. Consequently, the inputs that most affect the layout design are identified by means of an Analysis of Variance (ANOVA). The results show that only one layout is eligible to be the best configuration, and only two out of three control factors are very significant for the designing of the HRC workplace layout. Hence, the proposed approach enables the designing of standard compliant and optimized HRC workplace layouts. Therefore, several alternatives of the layout for the same workplace can be easily generated and investigated in a systematic manner. Full article
(This article belongs to the Special Issue Focus on Integrated Collaborative Systems for Smart Factory)
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15 pages, 4229 KiB  
Article
Architectural Simulation of Hybrid Energy Harvesting: A Design Experiment in Lanzarote Island
by Ho Soon Choi
Appl. Sci. 2021, 11(24), 12146; https://doi.org/10.3390/app112412146 - 20 Dec 2021
Cited by 2 | Viewed by 1830
Abstract
This study conducts research on an architectural design based on energy harvesting technology. The research subject is a pergola-style structure to be built in a square in Arrecife, the Spanish territory of Lanzarote Island. The architectural design based on the energy harvesting technology [...] Read more.
This study conducts research on an architectural design based on energy harvesting technology. The research subject is a pergola-style structure to be built in a square in Arrecife, the Spanish territory of Lanzarote Island. The architectural design based on the energy harvesting technology developed in this research utilizes solar energy. To install a solar panel on the roof of the pergola, the optimal tilt angle from January to December was derived by using a function that considered the latitude and solar declination value of the study site, and the amount of renewable energy generation was calculated. The architectural design based on energy harvesting also utilizes wind power. To transform wind power into renewable energy, piezoelectric materials that trigger renewable energy with the micro-vibrations generated by wind power are applied to the architectural design. The amount of energy generation was calculated considering the wind power and wind direction in the location where the pergola should be built; in addition, this calculation used information from prior studies on piezoelectric materials. This article is significant, as it has developed an architectural design where hybrid energy harvesting technology that utilizes two types of natural energy (solar and wind) is applied to a building façade. Full article
(This article belongs to the Special Issue New Type Solar Energy Materials and Devices)
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16 pages, 690 KiB  
Article
Improving Multi-Label Learning by Correlation Embedding
by Jun Huang, Qian Xu, Xiwen Qu, Yaojin Lin and Xiao Zheng
Appl. Sci. 2021, 11(24), 12145; https://doi.org/10.3390/app112412145 - 20 Dec 2021
Cited by 4 | Viewed by 2343
Abstract
In multi-label learning, each object is represented by a single instance and is associated with more than one class labels, where the labels might be correlated with each other. As we all know, exploiting label correlations can definitely improve the performance of a [...] Read more.
In multi-label learning, each object is represented by a single instance and is associated with more than one class labels, where the labels might be correlated with each other. As we all know, exploiting label correlations can definitely improve the performance of a multi-label classification model. Existing methods mainly model label correlations in an indirect way, i.e., adding extra constraints on the coefficients or outputs of a model based on a pre-learned label correlation graph. Meanwhile, the high dimension of the feature space also poses great challenges to multi-label learning, such as high time and memory costs. To solve the above mentioned issues, in this paper, we propose a new approach for Multi-Label Learning by Correlation Embedding, namely MLLCE, where the feature space dimension reduction and the multi-label classification are integrated into a unified framework. Specifically, we project the original high-dimensional feature space to a low-dimensional latent space by a mapping matrix. To model label correlation, we learn an embedding matrix from the pre-defined label correlation graph by graph embedding. Then, we construct a multi-label classifier from the low-dimensional latent feature space to the label space, where the embedding matrix is utilized as the model coefficients. Finally, we extend the proposed method MLLCE to the nonlinear version, i.e., NL-MLLCE. The comparison experiment with the state-of-the-art approaches shows that the proposed method MLLCE has a competitive performance in multi-label learning. Full article
(This article belongs to the Topic Machine and Deep Learning)
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9 pages, 549 KiB  
Article
Biomechanical Analysis of Running in Shoes with Different Heel-to-Toe Drops
by Masen Zhang, Huijuan Shi, Hui Liu and Xinglong Zhou
Appl. Sci. 2021, 11(24), 12144; https://doi.org/10.3390/app112412144 - 20 Dec 2021
Cited by 4 | Viewed by 5059
Abstract
The heel-to-toe drop of running shoes is a key parameter influencing lower extremity kinematics during running. Previous studies testing running shoes with lower or larger drops generally used minimalist or maximalist shoes, where the factors outside of the drop may lead to the [...] Read more.
The heel-to-toe drop of running shoes is a key parameter influencing lower extremity kinematics during running. Previous studies testing running shoes with lower or larger drops generally used minimalist or maximalist shoes, where the factors outside of the drop may lead to the observed changes in running biomechanics. Therefore, our aim was to compare the strike patterns, impact force, and lower extremity biomechanics when running in shoes that varied only in their drops. Eighteen habitual rearfoot strikers performed trials wearing running shoes with four drop conditions: 15 mm, 10 mm, 5 mm, and without a drop. Three-dimensional (3D) tracks of the reflective markers and impact force were synchronously collected using a video graphic acquisition system and two force plates. The biomechanical parameters were compared among the four drop conditions using one-way ANOVA of repeated measures. A greater foot inclination angle (p = 0.001, ηp2 = 0.36) at initial contact and a lower vertical loading rate (p = 0.002, ηp2 = 0.32) during the standing phase were found when running in shoes with large drops compared with running in shoes without a drop. Running in shoes with large drops, as opposed to without, significantly increased the peak knee extension moment (p = 0.002, ηp2 = 0.27), but decreased the peak ankle eversion moment (p = 0.001, ηp2 = 0.35). These findings suggest that the heel-to-toe drop of running shoes significantly influences the running pattern and the loading on lower extremity joints. Running shoes with large drops may be disadvantageous for runners with knee weakness and advantageous for runners with ankle weakness. Full article
(This article belongs to the Special Issue Biomechanics in Sport Performance and Injury Preventing)
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16 pages, 4168 KiB  
Article
Constant-Current, Constant-Voltage Operation of a Dual-Bridge Resonant Converter: Modulation, Design and Experimental Results
by Jiaqi Wu, Xiaodong Li, Shengzhi Zhou, Song Hu and Hao Chen
Appl. Sci. 2021, 11(24), 12143; https://doi.org/10.3390/app112412143 - 20 Dec 2021
Cited by 5 | Viewed by 1986
Abstract
To meet the requirements of charging the mainstream rechargeable batteries, in this work, a dual-bridge resonant converter (DBRC) is operated as a battery charger. Thanks to the features of this topology, the required high efficiency can be achieved with a wide range of [...] Read more.
To meet the requirements of charging the mainstream rechargeable batteries, in this work, a dual-bridge resonant converter (DBRC) is operated as a battery charger. Thanks to the features of this topology, the required high efficiency can be achieved with a wide range of battery voltage and current by using different modulation variables. Firstly, a typical charging process including constant-voltage stage and constant-current stage is indicated. Then, two different modulation methods of the DBRC are proposed, both of which can realize constant-voltage charging and constant-current charging. Method I adopts phase-shift modulation with constant switching frequency while Method II adopts varying frequency modulation. Furthermore, as guidance for practical application, the design principles and detailed design procedures of the DBRC are customized for the two modulation methods respectively in order to reduce the switching loss and conduction loss. Consequently, the full soft-switching operation with low rms tank current is achieved under the two modulation methods, which contributes to the high efficiency of the whole charging process. At last extensive simulation and experimental tests on a lab prototype converter are performed, which prove the feasibility and effectiveness of the proposed modulation strategies. Full article
(This article belongs to the Special Issue Resonant Converter in Power Electronics Technology)
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16 pages, 2731 KiB  
Article
Development and Evaluation of a Child Vaccination Chatbot Real-Time Consultation Messenger Service during the COVID-19 Pandemic
by Yeong-Joo Hong, Meihua Piao, Jeongeun Kim and Jae-Ho Lee
Appl. Sci. 2021, 11(24), 12142; https://doi.org/10.3390/app112412142 - 20 Dec 2021
Cited by 14 | Viewed by 3655
Abstract
The decreased rate of children’s vaccination has resulted in outbreaks of vaccine-preventable diseases, and vaccination hesitancy is being brought about by the uncertainty caused by the continuing COVID-19 pandemic. With this study, we aimed to assess the efficacy of a child vaccination chatbot [...] Read more.
The decreased rate of children’s vaccination has resulted in outbreaks of vaccine-preventable diseases, and vaccination hesitancy is being brought about by the uncertainty caused by the continuing COVID-19 pandemic. With this study, we aimed to assess the efficacy of a child vaccination chatbot based on changes in variables such as vaccination information, motivation, self-efficacy, and vaccination behavioral intention. From 30 January to 15 February 2020, 65 parents raising children ≤35 months old who were expected to be vaccinated within three months participated in the trial through online recruitment. Participants were randomly assigned to either the experimental group (n = 34) or the control group (n = 31) and were followed up with over a period of 12 weeks. During this period, both groups of participants were provided with vaccination schedule reminders. The experimental group were additionally provided with vaccination-related information and motivation boosters by a chatbot (real-time consultation messenger service); the control group was provided the same information by brochure. Comparing both groups, the experimental group that used the chatbot scored higher on vaccination information, motivation, self-efficacy, and vaccination behavioral intention than the control group. This suggests that the chatbot provided useful and timely information to parents, increasing vaccination motivation, self-efficacy, and vaccination rates. This study provides evidence that chatbots are useful tools to encourage immunization through the provision of reminders and real-time consultation messenger services during the global health crisis and beyond. Full article
(This article belongs to the Section Robotics and Automation)
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20 pages, 7735 KiB  
Article
Analysis and Evaluation on Residual Strength of Pipelines with Internal Corrosion Defects in Seasonal Frozen Soil Region
by Xiaoli Li, Guitao Chen, Xiaoyan Liu, Jing Ji and Lianfu Han
Appl. Sci. 2021, 11(24), 12141; https://doi.org/10.3390/app112412141 - 20 Dec 2021
Cited by 3 | Viewed by 2201
Abstract
In order to study the residual strength of buried pipelines with internal corrosion defects in seasonally frozen soil regions, we established a thermo-mechanical coupling model of a buried pipeline under differential frost heave by using the finite element elastoplastic analysis method. The material [...] Read more.
In order to study the residual strength of buried pipelines with internal corrosion defects in seasonally frozen soil regions, we established a thermo-mechanical coupling model of a buried pipeline under differential frost heave by using the finite element elastoplastic analysis method. The material nonlinearity and geometric nonlinearity were considered as the basis of analysis. Firstly, the location of the maximum Mises equivalent stress in the inner wall of the buried non-corroded pipeline was determined. Furthermore, the residual strength of the buried pipeline with corrosion defects and the stress state of internal corrosion area in the pipeline under different defect parameters was analyzed by the orthogonal design method. Based on the data results of the finite element simulation calculation, the prediction formula of residual strength of buried pipelines with internal corrosion defects was obtained by SPSS (Statistical Product and Service Solutions) fitting. The prediction results were analyzed in comparison with the evaluation results of B31G, DNV RP-F101 and the experimental data of hydraulic blasting. The rationality of the finite element model and the accuracy of the fitting formula were verified. The results show that the effect degree of main factors on residual strength was in order of corrosion depth, corrosion length, and corrosion width. when the corrosion length exceeds 600 mm, which affects the influence degree of residual strength will gradually decrease. the prediction error of the fitting formula is small and the distribution is uniform, it can meet the prediction requirements of failure pressure of buried pipelines with internal corrosion defects in seasonally frozen soil regions. This method may provide some useful theoretical reference for the simulation real-time monitoring and safety analysis in the pipeline operation stage. Full article
(This article belongs to the Special Issue Women in Civil Engineering)
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15 pages, 3744 KiB  
Article
A Novel Method for Field Measurement of Ankle Joint Stiffness in Hopping
by Sanubar Ghorbani Faal, Elham Shirzad, Ali Sharifnezhad, Mojtaba Ashrostaghi and Roozbeh Naemi
Appl. Sci. 2021, 11(24), 12140; https://doi.org/10.3390/app112412140 - 20 Dec 2021
Cited by 1 | Viewed by 1651
Abstract
Stiffness of ankle joint has been investigated in a wide range of biomechanical studies with a focus on the improvement of performance and reduction in the risk of injury. However, measuring ankle joint stiffness (AJS) using the existing conventional methodologies requires sophisticated equipment [...] Read more.
Stiffness of ankle joint has been investigated in a wide range of biomechanical studies with a focus on the improvement of performance and reduction in the risk of injury. However, measuring ankle joint stiffness (AJS) using the existing conventional methodologies requires sophisticated equipment such as force plate and motion analyses systems. This study presents a novel method for measuring AJS during a hopping task with no force or motion measurement system. Also the validity of the proposed new method was investigated by comparing the results against those obtained using conventional method in which motion capture and force plate data are used. Twelve participants performed the controlled hopping task at 2.2 Hz, on a force platform, and six high speed cameras recorded the movement. To calculate the AJS in both methods, the lower extremity was modeled as a three linked rigid segments robot with three joints. In the new method, the contact time and flight time were used to calculate ground reaction force, and inverse kinematic and inverse dynamic approaches were used to calculate the ankle kinematic and kinetic. The AJS calculated using the new method was compared against the results of conventional method as the reference. The calculated AJS using this new method (506.47 ± 177.84 N·m/rad) showed a significant correlation (r = 0.752) with the AJS calculated using conventional method (642.39 ± 185.96 N·m/rad). The validation test showed a mean difference of −24.76% using Bland–Altman plot. The presented method can be used as a valid, and low-cost tool for assessing AJS in the field in low resource settings. Full article
(This article belongs to the Special Issue Biomechanics in Sport Performance and Injury Preventing)
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22 pages, 13947 KiB  
Article
Experimental Study on Airflow and Temperature Predicting in a Double Skin Façade in Hot and Cold Seasons in Romania
by Monica Lilioara Cherecheș, Nelu Cristian Cherecheș, Adrian Alexandru Ciobanu, Sebastian Valeriu Hudișteanu, Emilian Florin Țurcanu, Aurelia Bradu and Cătălin George Popovici
Appl. Sci. 2021, 11(24), 12139; https://doi.org/10.3390/app112412139 - 20 Dec 2021
Cited by 4 | Viewed by 1922
Abstract
In the context of energy conservation and sustainable development, building design should take into account the energy efficiency criteria by using renewable energy sources. Double-skin facades (DSF) represent innovative energy-efficient techniques that have gained increasing interest worldwide. The present study reports the results [...] Read more.
In the context of energy conservation and sustainable development, building design should take into account the energy efficiency criteria by using renewable energy sources. Double-skin facades (DSF) represent innovative energy-efficient techniques that have gained increasing interest worldwide. The present study reports the results of an experimental campaign performed on a full-scale double-skin façade using the in-situ measurement methodology. The thermodynamic behavior of the façade is studied under real exterior climatic conditions in Romania in hot and cold seasons, and performance indicators in terms of pre-heating efficiency and dynamic insulation efficiency were determined. Three summer periods are analyzed corresponding to the outdoor air curtain scenario for three ventilation modes in naturally or mechanically ventilated single-story DSF. Results revealed that the third ventilation scenario, which combines horizontal and vertical openings, gives the best efficiency of 71.3% in the double skin façade functioning. During the cold season, the channel façade behaved like a thermal buffer between the building and the exterior air, ensuring the thermal energy for partial or integral heating of the building. Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)
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