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Appl. Sci., Volume 10, Issue 13 (July-1 2020) – 225 articles

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Open AccessReview
Developments, Trends, and Challenges in Optimization of Ship Energy Systems
Appl. Sci. 2020, 10(13), 4639; https://doi.org/10.3390/app10134639 (registering DOI) - 04 Jul 2020
Abstract
A review of developments, trends, and challenges in synthesis, design, and operation optimization of ship energy systems is presented in this article. For better understanding of the context of this review, pertinent terms are defined, including the three levels of optimization: synthesis, design, [...] Read more.
A review of developments, trends, and challenges in synthesis, design, and operation optimization of ship energy systems is presented in this article. For better understanding of the context of this review, pertinent terms are defined, including the three levels of optimization: synthesis, design, and operation (SDO). The static and dynamic optimization problems are stated mathematically in single- and multiobjective form. The need for intertemporal optimization is highlighted. The developments in ship energy systems optimization throughout the years is clearly presented by means of journal articles, giving the main characteristics of each article. After the review of what has been done up to now, ideas for future work are given. Further research needs for optimization of ship energy systems are mentioned: further development of methodology for synthesis optimization and SDO optimization, including transients, uncertainty, reliability, and maintenance scheduling. Hints are given for expansion of the system border in order to include aspects belonging to other disciplines, such as electrical and control engineering as well as hull and propulsor optimization, thus, opening a way to the holistic ship optimization. Full article
(This article belongs to the Special Issue Ship Energy Systems)
Open AccessArticle
Examining the Usefulness of Quality Scores for Generating Learning Object Recommendations in Repositories of Open Educational Resources
Appl. Sci. 2020, 10(13), 4638; https://doi.org/10.3390/app10134638 (registering DOI) - 04 Jul 2020
Abstract
Open educational resources (OER) can contribute to democratize education by providing effective learning experiences with lower costs. Nevertheless, the massive amount of resources currently available in OER repositories makes it difficult for teachers and learners to find relevant and high‑quality content, which is [...] Read more.
Open educational resources (OER) can contribute to democratize education by providing effective learning experiences with lower costs. Nevertheless, the massive amount of resources currently available in OER repositories makes it difficult for teachers and learners to find relevant and high‑quality content, which is hindering OER use and adoption. Recommender systems that use data related to the pedagogical quality of the OER can help to overcome this problem. However, studies analyzing the usefulness of these data for generating OER recommendations are very limited and inconclusive. This article examines the usefulness of using pedagogical quality scores for generating OER recommendations in OER repositories by means of a user study that compares the following four different recommendation approaches: a traditional content‑based recommendation technique, a quality‑based non‑personalized recommendation technique, a hybrid approach that combines the two previous techniques, and random recommendations. This user study involved 53 participants and 400 OER whose quality was evaluated by reviewers using the Learning Object Review Instrument (LORI). The main finding of this study is that pedagogical quality scores can enhance traditional content‑based OER recommender systems by allowing them to recommend OER with more quality without detriment to relevance. Full article
(This article belongs to the Special Issue Recommender Systems and Collaborative Filtering)
Open AccessArticle
The Buying Time Argument within the Solar Radiation Management Discourse
Appl. Sci. 2020, 10(13), 4637; https://doi.org/10.3390/app10134637 (registering DOI) - 04 Jul 2020
Abstract
In this article, we will establish a version of the buying time argument (BTA) in favor of Sulphur Aerosol Injection (SAI) Climate Engineering (CE). The idea is not to promote the deployment of such scheme, but rather to present the strongest possible argument [...] Read more.
In this article, we will establish a version of the buying time argument (BTA) in favor of Sulphur Aerosol Injection (SAI) Climate Engineering (CE). The idea is not to promote the deployment of such scheme, but rather to present the strongest possible argument pro SAI in order to look at its presuppositions, implications, critical points and uncertainties. In discussing BTA being the only morally sound argument in favor of SAI, the stakes and the overall framework will become visible. If, however, the strongest pro-SAI argument enables us to recognize some major flaws of this technology, this option should be disregarded. Full article
(This article belongs to the Special Issue Solar Radiation: Measurements and Modelling, Effects and Applications)
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Open AccessArticle
Microbiota in Waterlogged Archaeological Wood: Use of Next-Generation Sequencing to Evaluate the Risk of Biodegradation
Appl. Sci. 2020, 10(13), 4636; https://doi.org/10.3390/app10134636 (registering DOI) - 04 Jul 2020
Abstract
Waterlogged archaeological wood (WAW) is considered a precious material, first-hand account of past civilizations. Like any organic material, it is subjected to biodegradative action of microorganisms whose activity could be particularly fast and dangerous during the phases of excavation, storage and restoration. The [...] Read more.
Waterlogged archaeological wood (WAW) is considered a precious material, first-hand account of past civilizations. Like any organic material, it is subjected to biodegradative action of microorganisms whose activity could be particularly fast and dangerous during the phases of excavation, storage and restoration. The present work aimed to characterize the microorganisms present in WAW during these tricky periods to evaluate the biological risk it is exposed to. The bacterial and fungal communities inhabiting woods coming from two archaeological sites (Pisa and Naples) were investigated through Next-Generation Sequencing (NGS). High-throughput sequencing of extracted DNA fragments was performed using the reversible terminator-based sequencing chemistry with the Illumina MiSeq platform. The analyses revealed that the two archaeological sites showed distinct richness and biodiversity, as expected. In all the WAWs, the bacterial community harbored mainly Proteobacteria, whereas Bacteroidetes was well represented only in Naples communities and taxa belonging to the phyla Chloroflexi only in the Pisa site. Concerning the fungal community, the two sites were dominated by different phyla: Ascomycota for Naples samples and Basidiomycota for Pisa. Interestingly, most of the identified bacterial and fungal taxa have cellulolytic or ligninolytic ability. These results provide new and useful background information concerning the composition of WAW microbiota and the threat it represents for this precious material. Full article
Open AccessArticle
Effect of Diagonal Pattern Training on Trunk Function, Balance, and Gait in Stroke Patients
Appl. Sci. 2020, 10(13), 4635; https://doi.org/10.3390/app10134635 (registering DOI) - 04 Jul 2020
Abstract
Introduction: Trunk control disability commonly occurs after stroke. This study investigated the effect of diagonal pattern training in the sitting position to improve trunk control ability and gait performance. Method: 46 stroke patients were enrolled in this study. We used single plane training [...] Read more.
Introduction: Trunk control disability commonly occurs after stroke. This study investigated the effect of diagonal pattern training in the sitting position to improve trunk control ability and gait performance. Method: 46 stroke patients were enrolled in this study. We used single plane training and diagonal pattern training. Additionally, the subjects were randomly assigned to the experiment group (diagonal pattern training) and the control group (single plane training). Diagonal pattern training was modified with proprioceptive neuromuscular facilitation technique’s chopping and lifting pattern to create 10 movements. Results: the trunk impairment scale score, Berg balance scale score, 10 m walking test result, and gait significantly increased in the experiment group compared to the control group. Conclusions: diagonal pattern training can be regarded as a promising method to improve postural control and increase balance and gait in stroke patients Full article
(This article belongs to the Special Issue Physical Therapy and Health)
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Open AccessArticle
Preparation, Sinterability, Electrical Transport and Thermal Expansion of Perovskite-Type La0.8Ca0.2CrO3 Composites
Appl. Sci. 2020, 10(13), 4634; https://doi.org/10.3390/app10134634 (registering DOI) - 04 Jul 2020
Abstract
Perovskite-type was synthesized by two methods, the combustion method and conventional solid state reaction (SSR) method. The effect of synthesis methods on sinterability and physical properties of the ceramic were investigated. The results show that there are advantages of the combustion method in [...] Read more.
Perovskite-type was synthesized by two methods, the combustion method and conventional solid state reaction (SSR) method. The effect of synthesis methods on sinterability and physical properties of the ceramic were investigated. The results show that there are advantages of the combustion method in producing doped lanthanum chromites. Compared with the SSR method, the combustion method reduces the sintering temperature of La0.8Ca0.2CrO3, elevates the electronic conductivity and thermal expansion coefficient (TEC) of the ceramic, due to optimizing the microstructure. At the same densities level (–93%), the specimen synthesized by the combustion method reaches a superior electrical conductivity of 31.6 S·cm-1 and a compatible TEC of 10.7 × 10−6 K−1 at 800 °C. Full article
(This article belongs to the Special Issue 3D Nanostructured Materials and Devices)
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Open AccessArticle
Surveying and High-Resolution Topography of the Ochtiná Aragonite Cave Based on TLS and Digital Photogrammetry
Appl. Sci. 2020, 10(13), 4633; https://doi.org/10.3390/app10134633 (registering DOI) - 04 Jul 2020
Abstract
The Ochtiná Aragonite Cave (Slovakia, Central Europe) is a world-famous karst phenomenon of significant geological, geomorphological, and mineralogical values. Its specific origin is determined by particular lithological and hydrogeological conditions of the Ochtiná karst formed in lenses of Paleozoic crystalline limestones, partly metasomatically [...] Read more.
The Ochtiná Aragonite Cave (Slovakia, Central Europe) is a world-famous karst phenomenon of significant geological, geomorphological, and mineralogical values. Its specific origin is determined by particular lithological and hydrogeological conditions of the Ochtiná karst formed in lenses of Paleozoic crystalline limestones, partly metasomatically altered to ankerite and siderite. Although the cave is only 300 m long, it represents a combined labyrinth consisting in parallel tectonically controlled halls and passages, that are largely interconnected through transverse conduits of phreatic and epiphreatic morphology with many medium- and small-scale forms originated in slowly moving or standing water (flat solution ceilings, wall inward-inclined facets, water table notches, convectional cupolas, and spongework-like hollows). The highly dissected and irregular morphologies of the cave were surveyed with terrestrial laser scanning and digital photogrammetry. Both used surveying technologies proved to be suitable for quick and accurate mapping of the complicated cave pattern. While terrestrial laser scanning can provide a rapid survey of larger and more complex areas with results delivered directly in the field, digital photogrammetry is able to generate very high-resolution models with quality photo-texture for mapping of small-scale morphologies. Several data on cave morphometry were generated from terrestrial laser scanning (e.g., the area of cave ground plan, the peripheral surface of underground spaces, and their volume). The new detailed map, sections, and 3D model create an innovation platform for a more detailed study on the morphology and genesis of this unusual cave also for its environmental protection and use in tourism. Full article
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Open AccessArticle
Impact of Polycyclic Aromatic Hydrocarbons (PAHs) from an Asphalt Mix Plant in a Suburban Residential Area
Appl. Sci. 2020, 10(13), 4632; https://doi.org/10.3390/app10134632 (registering DOI) - 04 Jul 2020
Abstract
Polycyclic aromatic hydrocarbons (PAHs), an important class of hazardous airborne pollutants, are mutagenic and carcinogenic substances known to be released during the paving of asphalt. In this study, PAHs emitted from an asphalt mix plant were analyzed to investigate the effects on a [...] Read more.
Polycyclic aromatic hydrocarbons (PAHs), an important class of hazardous airborne pollutants, are mutagenic and carcinogenic substances known to be released during the paving of asphalt. In this study, PAHs emitted from an asphalt mix plant were analyzed to investigate the effects on a suburban residential area. Black carbon, organic carbon, elemental carbon, and PAHs in fine particulate matter (PM2.5) were analyzed in a village near the asphalt mix plant. The results of wind direction analysis revealed that the village was meteorologically affected by emissions from the asphalt mix plant. PAHs in PM2.5 ranged from 0.51 to 60.73 ng/m3, with an average of 11.54 ng/m3. Seasonal PAHs were highest in winter, followed in order by spring, autumn, and summer. The diagnostic ratios between PAHs indicate that the source of PAHs could be incomplete combustion of petrogenic origin. The maximum black carbon concentration in the intensive periods reaches up to 14.17 μg/m3 during mix plant operation periods. Seasonal ∑BaPTEF values based on Toxic Equivalence Factor were: winter (2.284 ng/m3), spring (0.575 ng/m3), autumn (0.550 ng/m3), and summer (0.176 ng/m3). The values are about 6.5 times higher than the concentration in another background area and more than three times higher than those in the capital city, Seoul, in the Republic of Korea. In conclusion, primary emissions from the point source can be considered the major contributor to pollution in the residential area. Full article
(This article belongs to the Special Issue Air Pollution II)
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Open AccessArticle
Analysis of Carbon Dioxide Concentration Prediction Model and Diffusion Tendency of Expiratory by Simultaneous Multipoint Sensing
Appl. Sci. 2020, 10(13), 4631; https://doi.org/10.3390/app10134631 (registering DOI) - 04 Jul 2020
Abstract
Recent indoor air quality studies show that even 1000 parts per million (ppm) concentration of Carbon Dioxide (CO2) has an adverse effect on human intellectual activities. Therefore, it is required to keep the CO2 concentration below a certain value in [...] Read more.
Recent indoor air quality studies show that even 1000 parts per million (ppm) concentration of Carbon Dioxide (CO2) has an adverse effect on human intellectual activities. Therefore, it is required to keep the CO2 concentration below a certain value in a room. In this study, in order to analyze the diffusion tendency of carbon dioxide by breathing, we constructed a simultaneous multi-point sensing system equipped with a carbon dioxide concentration sensor to measure indoor environment. Furthermore, it was evaluated whether the prediction model can be effectively used by comparing the prediction value by the model and the actually measured value from the sensor. The experimental results showed that CO2 by exhaled breathing diffuses evenly throughout the room regardless of the sensor’s relative positions to the human test subjects. The existing model is sufficiently accurate in a room which has above at least a 0.67 cycle/h ventilation cycle. However, there is a large gap between the measured and the model’s predicted values in a room with a low ventilation cycle, and that suggests a measurement with a sensor still is necessary to precisely monitor the indoor air quality. Full article
Open AccessArticle
Identification of Optimal Process Parameter Settings Based on Manufacturing Performance for Fused Filament Fabrication of CFR-PEEK
Appl. Sci. 2020, 10(13), 4630; https://doi.org/10.3390/app10134630 (registering DOI) - 03 Jul 2020
Viewed by 151
Abstract
Fused filament fabrication (FFF) has been proven to be an effective additive manufacturing technique for carbon fiber reinforced polyether–ether–ketone (CFR-PEEK) due to its practicality in use. However, the relationships between the process parameters and their trade-offs in manufacturing performance have not been extensively [...] Read more.
Fused filament fabrication (FFF) has been proven to be an effective additive manufacturing technique for carbon fiber reinforced polyether–ether–ketone (CFR-PEEK) due to its practicality in use. However, the relationships between the process parameters and their trade-offs in manufacturing performance have not been extensively studied for CFR-PEEK although they are essential to identify the optimal parameter settings. This study therefore investigates the impact of critical FFF parameters (i.e., layer thickness, build orientation, and printing speed) on the manufacturing performance (i.e., printing time, dimensional accuracy, and material cost) of CFR-PEEK outputs. A full factorial design of the experiments is performed for each of the three sample designs to identify the optimal parameter combinations for each performance measure. In addition, multiple response optimization was used to derive optimal parameter settings for the overall performance. The results show that the optimal parameter settings depend on the performance measures regardless of the designs, and that the layer thickness plays a critical role in the performance trade-offs. In addition, lower layer thickness, horizontal orientation, and higher speed form the optimal settings to maximize the overall performance. The findings from this study indicate that FFF parameter settings for CFR-PEEK should be identified through multi-objective decision making that involves conflicts between the operational objectives for the parameter settings. Full article
(This article belongs to the Special Issue Design and Management of Manufacturing Systems)
Open AccessFeature PaperReview
Multi-Omics Technologies Applied to Tuberculosis Drug Discovery
Appl. Sci. 2020, 10(13), 4629; https://doi.org/10.3390/app10134629 (registering DOI) - 03 Jul 2020
Viewed by 156
Abstract
Multi-omics strategies are indispensable tools in the search for new anti-tuberculosis drugs. Omics methodologies, where the ensemble of a class of biological molecules are measured and evaluated together, enable drug discovery programs to answer two fundamental questions. Firstly, in a discovery biology approach, [...] Read more.
Multi-omics strategies are indispensable tools in the search for new anti-tuberculosis drugs. Omics methodologies, where the ensemble of a class of biological molecules are measured and evaluated together, enable drug discovery programs to answer two fundamental questions. Firstly, in a discovery biology approach, to find new targets in druggable pathways for target-based investigation, advancing from target to lead compound. Secondly, in a discovery chemistry approach, to identify the mode of action of lead compounds derived from high-throughput screens, progressing from compound to target. The advantage of multi-omics methodologies in both of these settings is that omics approaches are unsupervised and unbiased to a priori hypotheses, making omics useful tools to confirm drug action, reveal new insights into compound activity, and discover new avenues for inquiry. This review summarizes the application of Mycobacterium tuberculosis omics technologies to the early stages of tuberculosis antimicrobial drug discovery. Full article
(This article belongs to the Special Issue Tuberculosis Drug Discovery and Development 2019)
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Open AccessArticle
Self-Adaptive Global-Best Harmony Search Algorithm-Based Airflow Control of a Wells-Turbine-Based Oscillating-Water Column
Appl. Sci. 2020, 10(13), 4628; https://doi.org/10.3390/app10134628 (registering DOI) - 03 Jul 2020
Viewed by 114
Abstract
The Harmony Search algorithm has attracted a lot of interest in the past years because
of its simplicity and efficiency. This led many scientists to develop various variants for many
applications. In this paper, four variants of the Harmony search algorithm were implemented [...] Read more.
The Harmony Search algorithm has attracted a lot of interest in the past years because
of its simplicity and efficiency. This led many scientists to develop various variants for many
applications. In this paper, four variants of the Harmony search algorithm were implemented and
tested to optimize the control design of the Proportional-Integral-derivative (PID) controller in a
proposed airflow control scheme. The airflow control strategy has been proposed to deal with
the undesired stalling phenomenon of the Wells turbine in an Oscillating Water Column (OWC).
To showcase the effectiveness of the Self-Adaptive Global Harmony Search (SGHS) algorithm over
traditional tuning methods, a comparative study has been carried out between the optimized PID,
the traditionally tuned PID and the uncontrolled OWC system. The results of optimization showed
that the Self-Adaptive Global Harmony Search (SGHS) algorithm adapted the best to the problem of
the airflow control within the wave energy converter. Moreover, the OWC performance is superior
when using the SGHS-tuned PID. Full article
Open AccessArticle
Quality Control of the Continuous Hot Pressing Process of Medium Density Fiberboard Using Fuzzy Failure Mode and Effects Analysis
Appl. Sci. 2020, 10(13), 4627; https://doi.org/10.3390/app10134627 (registering DOI) - 03 Jul 2020
Viewed by 115
Abstract
In this paper, a fuzzy failure mode and effects analysis (FMEA) method is proposed by combining fault theory and a failure analysis method. The method addresses the problem of board thickness control failure and the problem of thickness deviation defect blanking, which can [...] Read more.
In this paper, a fuzzy failure mode and effects analysis (FMEA) method is proposed by combining fault theory and a failure analysis method. The method addresses the problem of board thickness control failure and the problem of thickness deviation defect blanking, which can occur during continuous hot pressing (CHP) process, which is one of the most important processes in the production of medium-density fiberboard (MDF). The method combines the fault analysis with the Hamming code method and using the Hamming code to calculate and represent the cylinder array of the continuous hot-pressed thickness control execution unit to analyze and process the potential fixed thickness failure modes in MDF hot press production, and then summarizes the decision rules for controlling the board thickness and the level of sheet deviation. By combining the fuzzy FMEA method of the Hamming code and the logical OR operation of the experimental analysis, the method of thickness deviation and recognition control fault information for the CHP of MDF, which is proposed in this paper, permits the increase of the number of error levels, which makes optimization for controller more convenient and improves the efficiency to recognize errors. Full article
(This article belongs to the Section Computing and Artificial Intelligence)
Open AccessFeature PaperReview
Lignin to Materials: A Focused Review on Recent Novel Lignin Applications
Appl. Sci. 2020, 10(13), 4626; https://doi.org/10.3390/app10134626 (registering DOI) - 03 Jul 2020
Viewed by 117
Abstract
In recent decades, advancements in lignin application include the synthesis of polymers, dyes, adhesives and fertilizers. There has recently been a shift from perceiving lignin as a waste product to viewing lignin as a potential raw material for valuable products. More recently, considerable [...] Read more.
In recent decades, advancements in lignin application include the synthesis of polymers, dyes, adhesives and fertilizers. There has recently been a shift from perceiving lignin as a waste product to viewing lignin as a potential raw material for valuable products. More recently, considerable attention has been placed in sectors, like the medical, electrochemical, and polymer sectors, where lignin can be significantly valorized. Despite some technical challenges in lignin recovery and depolymerization, lignin is viewed as a promising material due to it being biocompatible, cheap, and abundant in nature. In the medical sector, lignins can be used as wound dressings, pharmaceuticals, and drug delivery materials. They can also be used for electrochemical energy materials and 3D printing lignin–plastic composite materials. This review covers the recent research progress in lignin valorization, specifically focusing on medical, electrochemical, and 3D printing applications. The technoeconomic assessment of lignin application is also discussed. Full article
(This article belongs to the Special Issue Biorefinery: Current Status, Challenges, and New Strategies)
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Open AccessArticle
Structural Behavior of Large-Scale I-Beams with Combined Textile and CFRP Reinforcement
Appl. Sci. 2020, 10(13), 4625; https://doi.org/10.3390/app10134625 (registering DOI) - 03 Jul 2020
Viewed by 111
Abstract
With the innovative composite material carbon-reinforced concrete, thin-walled, high-performance components can be realized. A combination of carbon fiber reinforced polymer (CFRP) bars and non-metallic textile grids is advantageous as it exploits the full potential of the high-performance materials to reduce dead loads, increases [...] Read more.
With the innovative composite material carbon-reinforced concrete, thin-walled, high-performance components can be realized. A combination of carbon fiber reinforced polymer (CFRP) bars and non-metallic textile grids is advantageous as it exploits the full potential of the high-performance materials to reduce dead loads, increases durability, and extends lifespan. For new components with such mixed reinforcement, applicable design concepts and engineering rules are necessary to accurately determine the structural and deformation behavior. To validate models and detailing rules previously developed, three large carbon reinforced concrete I-beams were designed and tested to failure with a realistic line load. CFRP bars served as principal bending reinforcement, whereas shear and flange reinforcement consisted of textile grids. Results showed that existing models for bending using variation of strain distribution as well as non-linear finite-element analysis predicted the flexural behavior of structural components with mixed reinforcement in ultimate limit state (ULS) appropriately. Yet, calculation of shear capacity requires further studies to determine textile reinforcement contribution and estimate reduction for concrete strength in reinforced compression struts. For serviceability limit state (SLS), three methods for determination of deflection delivered good results. In future, a rethinking is required with regard to the ductility and robustness of CFRP-reinforced concrete components. In this respect, pronounced cracking as well as the large ultimate strain and deflection compensate for the lacking yield capacity of the reinforcement. Full article
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Open AccessArticle
Impact of Historical Software Metric Changes in Predicting Future Maintainability Trends in Open-Source Software Development
Appl. Sci. 2020, 10(13), 4624; https://doi.org/10.3390/app10134624 (registering DOI) - 03 Jul 2020
Viewed by 96
Abstract
Software maintenance is one of the key stages in the software lifecycle and it includes a variety of activities that consume the significant portion of the costs of a software project. Previous research suggest that future software maintainability can be predicted, based on [...] Read more.
Software maintenance is one of the key stages in the software lifecycle and it includes a variety of activities that consume the significant portion of the costs of a software project. Previous research suggest that future software maintainability can be predicted, based on various source code aspects, but most of the research focuses on the prediction based on the present state of the code and ignores its history. While taking the history into account in software maintainability prediction seems intuitive, the research empirically testing this has not been done, and is the main goal of this paper. This paper empirically evaluates the contribution of historical measurements of the Chidamber & Kemerer (C&K) software metrics to software maintainability prediction models. The main contribution of the paper is the building of the prediction models with classification and regression trees and random forest learners in iterations by adding historical measurement data extracted from previous releases gradually. The maintainability prediction models were built based on software metric measurements obtained from real-world open-source software projects. The analysis of the results show that an additional amount of historical metric measurements contributes to the maintainability prediction. Additionally, the study evaluates the contribution of individual C&K software metrics on the performance of maintainability prediction models. Full article
Open AccessArticle
Effect of Three Polysaccharides (Inulin, and Mucilage from Chia and Flax Seeds) on the Survival of Probiotic Bacteria Encapsulated by Spray Drying
Appl. Sci. 2020, 10(13), 4623; https://doi.org/10.3390/app10134623 (registering DOI) - 03 Jul 2020
Viewed by 132
Abstract
Chia seed mucilage (CM), flaxseed mucilage (FM), and inulin (INL) were used as encapsulating agents to evaluate the possibility of increasing the survival of Lactobacillus casei var. rhamnosus, renamed recently to Lacticaseibacillus rhamnosus, after spray drying. Moreover, the viability of encapsulated [...] Read more.
Chia seed mucilage (CM), flaxseed mucilage (FM), and inulin (INL) were used as encapsulating agents to evaluate the possibility of increasing the survival of Lactobacillus casei var. rhamnosus, renamed recently to Lacticaseibacillus rhamnosus, after spray drying. Moreover, the viability of encapsulated L. rhamnosus was determined during the 250 day storage period at 4 °C. In a second stage, the conditions that maximized the survival of L. rhamnosus were evaluated on other probiotic bacteria (Lactiplantibacillus plantarum, Bifidobacterium infantis, and Bifidobacterium longum). Additionally, the viability of encapsulated probiotics during the 60 day storage period at 4 and 25 °C was evaluated. The conditions that maximize the survival of L. rhamnosus (90%) predicted by a face-centered central composite design were 14.4% w/v of maltodextrin, 0.6% w/v of CM, and 90 °C of inlet air temperature. Additionally, under these encapsulating conditions, the survival of L. plantarum, B. infantis, and B. longum was 95%, 97%, and 96%, respectively. The probiotic viability improved during storage at 4 °C but decreased at 25 °C. The highest viability values obtained for probiotics during spray drying and during storage suggest a thermoprotector effect of CM, which would ensure an optimal probiotic efficacy in the product, thus promoting its utilization in the food industry. Full article
(This article belongs to the Section Food Science and Technology)
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Open AccessArticle
Exploiting a Deep Neural Network for Efficient Transmit Power Minimization in a Wireless Powered Communication Network
Appl. Sci. 2020, 10(13), 4622; https://doi.org/10.3390/app10134622 (registering DOI) - 03 Jul 2020
Viewed by 107
Abstract
In this paper, we propose a learning-based solution for resource allocation in a wireless powered communication network (WPCN). We provide a study and analysis of a deep neural network (DNN) which can reasonably effectively approximate the iterative optimization algorithm for resource allocation in [...] Read more.
In this paper, we propose a learning-based solution for resource allocation in a wireless powered communication network (WPCN). We provide a study and analysis of a deep neural network (DNN) which can reasonably effectively approximate the iterative optimization algorithm for resource allocation in the WPCN. In this scheme, the deep neural network provides an optimized solution for transmitting power with different channel coefficients. The proposed deep neural network accepts the channel coefficient as an input and outputs minimized power for this channel in the WPCN. The DNN learns the relationship between input and output and gives a fairly accurate approximation for the transmit power optimization iterative algorithm. We exploit the sequential parametric convex approximation (SPCA) iterative algorithm to solve the optimization problem for transmit power in the WPCN. The proposed approach ensures the quality of service (QoS) of the WPCN by managing user throughput and by keeping harvested energy levels above a defined threshold. Through numerical results and simulations, it is verified that the proposed scheme can best approximate the SPCA iterative algorithms with low computational time consumption. Full article
(This article belongs to the Section Electrical, Electronics and Communications Engineering)
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Open AccessArticle
Precision Auto-Focusing Apparatus Based on Long-Working-Distance, Wide-Spectrum Microscope
Appl. Sci. 2020, 10(13), 4621; https://doi.org/10.3390/app10134621 (registering DOI) - 03 Jul 2020
Viewed by 102
Abstract
A mirror-based Schwarzschild microscope with a wide spectrum and a long working distance was investigated to perform precise assemblage of detectors. We employed a gradient square method to construct the evaluation function for realizing accurate quantitative analysis of image defocusing. By imaging a [...] Read more.
A mirror-based Schwarzschild microscope with a wide spectrum and a long working distance was investigated to perform precise assemblage of detectors. We employed a gradient square method to construct the evaluation function for realizing accurate quantitative analysis of image defocusing. By imaging a resolution target that corresponded to 228 line pairs per mm, the validity and imaging ability of the system was proven. The results of repeated focusing tests yielded a standard deviation of 0.75 μm, which indicated high performance accuracy for the focusing system. The proposed system has potential applications in industrial inspection and focusing detection. Full article
(This article belongs to the Section Optics and Lasers)
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Open AccessFeature PaperArticle
A Box-Behnken Design for Optimal Green Extraction of Compounds from Olive Leaves That Potentially Activate the AMPK Pathway
Appl. Sci. 2020, 10(13), 4620; https://doi.org/10.3390/app10134620 - 03 Jul 2020
Viewed by 127
Abstract
Olive leaves contain bioactive compounds that have been shown to activate AMP-activated protein kinase (AMPK), which decreases intracellular lipid accumulation. Microwave-assisted extraction (MAE) is a green extraction technique that is frequently used in the recovery of phenolic compounds from plants. Thus, in this [...] Read more.
Olive leaves contain bioactive compounds that have been shown to activate AMP-activated protein kinase (AMPK), which decreases intracellular lipid accumulation. Microwave-assisted extraction (MAE) is a green extraction technique that is frequently used in the recovery of phenolic compounds from plants. Thus, in this study, a Box-Behnken design was used to optimize MAE conditions such as temperature, percentage of ethanol and extraction time to obtain the maximum content of total compounds and compounds that activate AMPK. To this end, all extracts were characterized by High-Performance Liquid Chromatography Coupled to Electrospray Ionization Time-of-Flight Mass Spectrometry (HPLC-ESI-TOF-MS). The optimum conditions to obtain the highest content of total compounds were 123 °C, 100% of ethanol/water (v/v) and 23 min, whereas the optimum conditions for the highest amount of compounds that activate AMPK were 111 °C, 42% of ethanol/water (v/v) and 23 min. Thus, a multi-analysis by desirability was carried out to establish MAE optimal conditions for both responses. The optimum conditions were 111 °C, 100% EtOH and 23 min with a desirability of 0.97, which means that the responses are close to their individual optimal values. As a result, the olive leaf extract obtained at these optimal MAE conditions has great potential to be effective in the treatment of obesity. Full article
(This article belongs to the Special Issue Sustainable Technologies for the Revalorization of Agro-Food Residues)
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Open AccessArticle
Modeling and Identification of an Industrial Robot with a Selective Modal Approach
Appl. Sci. 2020, 10(13), 4619; https://doi.org/10.3390/app10134619 - 03 Jul 2020
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Abstract
The stiffness properties of industrial robots are very important for many industrial applications, such as automatic robotic assembly and material removal processes (e.g., machining and deburring). On the one hand, in robotic assembly, joint compliance can be useful for compensating dimensional errors in [...] Read more.
The stiffness properties of industrial robots are very important for many industrial applications, such as automatic robotic assembly and material removal processes (e.g., machining and deburring). On the one hand, in robotic assembly, joint compliance can be useful for compensating dimensional errors in the parts to be assembled; on the other hand, in material removal processes, a high Cartesian stiffness of the end-effector is required. Moreover, low frequency chatter vibrations can be induced when low-stiffness robots are used, with an impairment in the quality of the machined surface. In this paper, a compliant joint dynamic model of an industrial robot has been developed, in which joint stiffness has been experimentally identified using a modal approach. First, a novel method to select the test configurations has been developed, so that in each configuration the mode of vibration that chiefly involves only one joint is excited. Then, experimental tests are carried out in the selected configurations in order to identify joint stiffness. Finally, the developed dynamic model of the robot is used to predict the variation of the natural frequencies in the workspace. Full article
(This article belongs to the Special Issue Advances in Mechanical Systems Dynamics 2020)
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Open AccessReview
Reversible Hydrogen Storage Using Nanocomposites
Appl. Sci. 2020, 10(13), 4618; https://doi.org/10.3390/app10134618 (registering DOI) - 03 Jul 2020
Viewed by 171
Abstract
In the field of energy storage, recently investigated nanocomposites show promise in terms of high hydrogen uptake and release with enhancement in the reaction kinetics. Among several, carbonaceous nanovariants like carbon nanotubes (CNTs), fullerenes, and graphitic nanofibers reveal reversible hydrogen sorption characteristics at [...] Read more.
In the field of energy storage, recently investigated nanocomposites show promise in terms of high hydrogen uptake and release with enhancement in the reaction kinetics. Among several, carbonaceous nanovariants like carbon nanotubes (CNTs), fullerenes, and graphitic nanofibers reveal reversible hydrogen sorption characteristics at 77 K, due to their van der Waals interaction. The spillover mechanism combining Pd nanoparticles on the host metal-organic framework (MOF) show room temperature uptake of hydrogen. Metal or complex hydrides either in the nanocomposite form and its subset, nanocatalyst dispersed alloy phases illustrate the concept of nanoengineering and nanoconfinement of particles with tailor-made properties for reversible hydrogen storage. Another class of materials comprising polymeric nanostructures such as conducting polyaniline and their functionalized nanocomposites are versatile hydrogen storage materials because of their unique size, high specific surface-area, pore-volume, and bulk properties. The salient features of nanocomposite materials for reversible hydrogen storage are reviewed and discussed. Full article
(This article belongs to the Special Issue Clean Energy and Fuel Storage 2020)
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Open AccessArticle
Influence of Pressure on Gas/Liquid Interfacial Area in a Tray Column
Appl. Sci. 2020, 10(13), 4617; https://doi.org/10.3390/app10134617 - 03 Jul 2020
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Abstract
The influence of pressure on the gas/liquid interfacial area is investigated in the pressure range of 0.2–0.3 MPa by using a tray column test rig. A simulated waste gas, which consisted of 30% CO2 and 70% air, was used in this study. [...] Read more.
The influence of pressure on the gas/liquid interfacial area is investigated in the pressure range of 0.2–0.3 MPa by using a tray column test rig. A simulated waste gas, which consisted of 30% CO2 and 70% air, was used in this study. Distilled water was employed as an absorbent. The temperature of the inlet water was 19 °C. The inlet volumetric flow rate of water was 0.17 m3/h. Two series of experiments were performed; the first series was performed at inlet gas flow rate 15 Nm3/h, whereas the second series was at 20 Nm3/h of inlet gas flow rate. The results showed that the gas/liquid interfacial area decreases when the total pressure is increased. The effect of pressure on the gas/liquid interfacial area at high inlet volumetric gas flow rates is more significant than at low inlet volumetric gas flow rates. The authors studied the effect of decreasing the interfacial area on the performance of a tray column for CO2 capture. Full article
Open AccessArticle
Strength Characteristics and Slope Stability Analysis of Expansive Soil with Filled Fissures
Appl. Sci. 2020, 10(13), 4616; https://doi.org/10.3390/app10134616 - 03 Jul 2020
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Abstract
Fissured expansive soils were widely distributed in the South-to-North Water Transfer Project. Most of the fissures were filled with clay, which controlled the stability of the slope. With the method of layered filling—bevel cutting—refilling and a modular design idea, the sample with a [...] Read more.
Fissured expansive soils were widely distributed in the South-to-North Water Transfer Project. Most of the fissures were filled with clay, which controlled the stability of the slope. With the method of layered filling—bevel cutting—refilling and a modular design idea, the sample with a filled fissure preparation device for triaxial test was designed. After setting the filled fissures of gray-green clay in the expansive soil, triaxial tests were carried out for the samples with no filled fissures and with filled fissures with inclination angles of 15°, 30°, and 45°. Then, considering the spatial distribution and the strength of the filled fissures in the slope, the stability analysis method for the expansive soil slope with filled fissures was proposed. The stability of a typical slope in Nanyang was analyzed. The results show that the c of expansive soil with filled fissures was about 12 to 15 kPa and the φ was 3° to 6°. Filled fissures had an attenuation effect on the strength of the expansive soil. The larger the inclination of filled fissures, the more significant the effect of soil strength attenuation. The fissured slope stability was controlled by the filled fissures. The sliding surface was affected by the vertical fissures on the top of the slope and the slow-inclined long-large fissures in the slope, and the shape of the sliding surface was a broken line, which was basically consistent with the actual landslide. Full article
(This article belongs to the Section Earth Sciences and Geography)
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Open AccessArticle
Mosaicplasty versus Matrix-Assisted Autologous Chondrocyte Transplantation for Knee Cartilage Defects: A Long-Term Clinical and Imaging Evaluation
Appl. Sci. 2020, 10(13), 4615; https://doi.org/10.3390/app10134615 - 03 Jul 2020
Viewed by 127
Abstract
Different surgical procedures have been proposed over the past few years to treat cartilage lesions. The aim of this study was to compare mosaicplasty and matrix-assisted autologous chondrocyte transplantation (MACT) at long-term follow-up. Forty-three patients were included: 20 mosaicplasty and 23 MACT. Patients [...] Read more.
Different surgical procedures have been proposed over the past few years to treat cartilage lesions. The aim of this study was to compare mosaicplasty and matrix-assisted autologous chondrocyte transplantation (MACT) at long-term follow-up. Forty-three patients were included: 20 mosaicplasty and 23 MACT. Patients were evaluated before and 12 years after surgery with the International Knee Documentation Committee (IKDC) subjective and objective scores for symptoms and function, and with the Tegner score for activity level. Magnetic Resonance Imaging (MRI) was used to evaluate repair tissue with the MOCART 2.0 score. Mosaicplasty and MACT showed good clinical and MRI results (IKDC subjective score 75.3 ± 21.8 and 81.8 ± 13.0, both p < 0.0005). Mosaicplasty presented a 10% reoperation rate and a 25% overall failure rate, while no failures were documented in MACT (p = 0.016). While size did not influence the results in the MACT group, mosaicplasty presented lower IKDC objective and Tegner scores in lesions bigger than 2 cm2 (p = 0.031 and p = 0.014, respectively). Mosaicplasty and MACT presented both satisfactory clinical and MRI results at long-term follow-up. However, for larger lesions, MACT presented better subjective and objective outcomes, as well as less failures, which should be considered when choosing the most suitable treatment for patients affected by knee cartilage lesions. Full article
Open AccessArticle
A Multiple Criteria Decision Analysis Framework for Dispersed Group Decision-Making Contexts
Appl. Sci. 2020, 10(13), 4614; https://doi.org/10.3390/app10134614 - 03 Jul 2020
Viewed by 134
Abstract
To support Group Decision-Making processes when participants are dispersed is a complex task. The biggest challenges are related to communication limitations that impede decision-makers to take advantage of the benefits associated with face-to-face Group Decision-Making processes. Several approaches that intend to aid dispersed [...] Read more.
To support Group Decision-Making processes when participants are dispersed is a complex task. The biggest challenges are related to communication limitations that impede decision-makers to take advantage of the benefits associated with face-to-face Group Decision-Making processes. Several approaches that intend to aid dispersed groups attaining decisions have been applied to Group Decision Support Systems. However, strategies to support decision-makers in reasoning, understanding the reasons behind the different recommendations, and promoting the decision quality are very limited. In this work, we propose a Multiple Criteria Decision Analysis Framework that intends to overcome those limitations through a set of functionalities that can be used to support decision-makers attaining more informed, consistent, and satisfactory decisions. These functionalities are exposed through a microservice, which is part of a Consensus-Based Group Decision Support System and is used by autonomous software agents to support decision-makers according to their specific needs/interests. We concluded that the proposed framework greatly facilitates the definition of important procedures, allowing decision-makers to take advantage of deciding as a group and to understand the reasons behind the different recommendations and proposals. Full article
(This article belongs to the Special Issue Multi-Agent Systems 2020)
Open AccessReview
Italian-Style Opera Houses: A Historical Review
Appl. Sci. 2020, 10(13), 4613; https://doi.org/10.3390/app10134613 - 03 Jul 2020
Viewed by 116
Abstract
Attending an opera involves a multi-sensory evaluation (acoustical, visual, and more), cultural background and other emotional parameters. The present work aims to investigate the historical development of Italian-style opera houses, from the 16th century until today. Called “Italian” due to their origin, they [...] Read more.
Attending an opera involves a multi-sensory evaluation (acoustical, visual, and more), cultural background and other emotional parameters. The present work aims to investigate the historical development of Italian-style opera houses, from the 16th century until today. Called “Italian” due to their origin, they developed thanks to the mutual influence of the genre and the building characteristics. Furthermore, the acoustics of historical opera houses is now considered as intangible cultural heritage, so it should be known and preserved. The paper addressed the state-of-the-art literature—most of which was proposed in Italian—which can be driven easily by the sharing of historical and contemporary knowledge. Full article
(This article belongs to the Special Issue Advances in Architectural Acoustics)
Open AccessArticle
Classification of Photoplethysmographic Signal Quality with Deep Convolution Neural Networks for Accurate Measurement of Cardiac Stroke Volume
Appl. Sci. 2020, 10(13), 4612; https://doi.org/10.3390/app10134612 - 03 Jul 2020
Viewed by 128
Abstract
As photoplethysmographic (PPG) signals are comprised of numerous pieces of important physiological information, they have been widely employed to measure many physiological parameters. However, only a high-quality PPG signal can provide a reliable physiological assessment. Unfortunately, PPG signals are easily corrupted by motion [...] Read more.
As photoplethysmographic (PPG) signals are comprised of numerous pieces of important physiological information, they have been widely employed to measure many physiological parameters. However, only a high-quality PPG signal can provide a reliable physiological assessment. Unfortunately, PPG signals are easily corrupted by motion artifacts and baseline drift during recording. Although several rule-based algorithms have been developed for evaluating the quality of PPG signals, few artificial intelligence-based algorithms have been presented. Thus, this study aims to classify the quality of PPG signals by using two two-dimensional deep convolution neural networks (DCNN) when the PPG pulse is used to measure cardiac stroke volume (SV) by impedance cardiography. An image derived from a PPG pulse and its differential pulse is used as the input to the two DCNN models. To quantify the quality of individual PPG pulses, the error percentage of the beat-to-beat SV measured by our device and medis® CS 2000 synchronously is used to determine whether the pulse quality is high, middle, or low. Fourteen subjects were recruited, and a total of 3135 PPG pulses (1342 high quality, 73 middle quality, and 1720 low quality) were obtained. We used a traditional DCNN, VGG-19, and a residual DCNN, ResNet-50, to determine the quality levels of the PPG pulses. Their results were all better than the previous rule-based methods. The accuracies of VGG-19 and ResNet-50 were 0.895 and 0.925, respectively. Thus, the proposed DCNN may be applied for the classification of PPG quality and be helpful for improving the SV measurement in impedance cardiography. Full article
Open AccessFeature PaperArticle
Thermal Performance of a Massive Wall in the Mediterranean Climate: Experimental and Analytical Research
Appl. Sci. 2020, 10(13), 4611; https://doi.org/10.3390/app10134611 - 03 Jul 2020
Viewed by 143
Abstract
In the Mediterranean climate, indoor overheating and, thus, excessive use of cooling systems represents one of the main problems both for the occupants' health and energy consumption. In order to limit this problem, an appropriate design or energy retrofitting of the building envelope [...] Read more.
In the Mediterranean climate, indoor overheating and, thus, excessive use of cooling systems represents one of the main problems both for the occupants' health and energy consumption. In order to limit this problem, an appropriate design or energy retrofitting of the building envelope is of utmost importance. The predominance of massive buildings in the Italian territory and the need to comply with Italian regulations often leads technicians to not optimal energy saving solutions. To this purpose, this experimental research was conducted on a mockup building, located in Fabriano and characterized by high thermal mass walls (W0) and two different external insulating systems: Cork based lightweight plaster (W1) and Extruded polystyrene foam panel (XPS) (W2). Furthermore, a virtual model in TRNSYS, a transient simulation software, was used to compare analytical and simulated values. Results show that W2 undergoes a higher level of thermal stress than W1, due to higher peaks in the external surface temperature and larger fluctuations in daily temperature. Therefore, a high value of thermal resistance of the external insulation and low value of external areal heat capacity on a massive building causes external surface overheating problems, thus, not representing the optimal construction solution. Full article
(This article belongs to the Special Issue Impact Assessment of Climate Change on Buildings)
Open AccessArticle
Fiber-Optic Bragg Gratings for Temperature and Pressure Measurements in Isotope Production Targets for Nuclear Medicine
Appl. Sci. 2020, 10(13), 4610; https://doi.org/10.3390/app10134610 - 03 Jul 2020
Viewed by 144
Abstract
A Bragg grating inscribed into an inorganic optical fiber was tested in proton and neutron fields up to doses of 472 Gy. Observation showed that radiation had no effect on the performance of the Fiber Bragg Grating (FBG) used as a gauge measuring [...] Read more.
A Bragg grating inscribed into an inorganic optical fiber was tested in proton and neutron fields up to doses of 472 Gy. Observation showed that radiation had no effect on the performance of the Fiber Bragg Grating (FBG) used as a gauge measuring temperature and pressure. The FBG sensor was subsequently employed to measure the temperature and pressure inside a liquid isotope production target for nuclear medicine. The fiber Bragg grating measured the temperature and pressure of a water target as a 12 MeV proton beam impinged on it in real time and was tested with beam currents of up to 20 µA. Full article
(This article belongs to the Special Issue Beam Diagnostics for Medical Application)
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