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Appl. Sci., Volume 9, Issue 5 (March-1 2019)

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Cover Story (view full-size image) The main character of this cover story is the human A3 Adenosine receptor, represented here in the [...] Read more.
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Open AccessArticle PRGF-Modified Collagen Membranes for Guided Bone Regeneration: Spectroscopic, Microscopic and Nano-Mechanical Investigations
Appl. Sci. 2019, 9(5), 1035; https://doi.org/10.3390/app9051035
Received: 6 February 2019 / Revised: 4 March 2019 / Accepted: 8 March 2019 / Published: 12 March 2019
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Abstract
The aim of our study was to evaluate the properties of different commercially available resorbable collagen membranes for guided bone regeneration, upon addition of plasma rich in growth factors (PRGF). The structural and morphological details, mechanical properties, and enzymatic degradation were investigated in [...] Read more.
The aim of our study was to evaluate the properties of different commercially available resorbable collagen membranes for guided bone regeneration, upon addition of plasma rich in growth factors (PRGF). The structural and morphological details, mechanical properties, and enzymatic degradation were investigated in a new approach, providing clinicians with new data in order to help them in a successful comparison and better selection of membranes with respect to their placement and working condition. Particular characteristics such as porosity, fiber density, and surface topography may influence the mechanical behavior and performances of the membranes, as revealed by SEM/AFM and nanoindentation measurements. The mechanical properties and enzymatic degradation of the membranes were analyzed in a comparative manner, before and after PRGF-modification. The changes in Young modulus values are correlated with the ultrastructural properties of each membrane type. The enzymatic (trypsin) degradation test also emphasized that PRGF-modified membranes exhibit a slower degradation compared to the native ones. Full article
(This article belongs to the Special Issue Development of Membranes for Oral and Maxillofacial Application)
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Open AccessArticle Biologically-Inspired Learning and Adaptation of Self-Evolving Control for Networked Mobile Robots
Appl. Sci. 2019, 9(5), 1034; https://doi.org/10.3390/app9051034
Received: 16 January 2019 / Revised: 26 February 2019 / Accepted: 5 March 2019 / Published: 12 March 2019
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Abstract
This paper presents a biologically-inspired learning and adaptation method for self-evolving control of networked mobile robots. A Kalman filter (KF) algorithm is employed to develop a self-learning RBFNN (Radial Basis Function Neural Network), called the KF-RBFNN. The structure of the KF-RBFNN is optimally [...] Read more.
This paper presents a biologically-inspired learning and adaptation method for self-evolving control of networked mobile robots. A Kalman filter (KF) algorithm is employed to develop a self-learning RBFNN (Radial Basis Function Neural Network), called the KF-RBFNN. The structure of the KF-RBFNN is optimally initialized by means of a modified genetic algorithm (GA) in which a Lévy flight strategy is applied. By using the derived mathematical kinematic model of the mobile robots, the proposed GA-KF-RBFNN is utilized to design a self-evolving motion control law. The control parameters of the mobile robots are self-learned and adapted via the proposed GA-KF-RBFNN. This approach is extended to address the formation control problem of networked mobile robots by using a broadcast leader-follower control strategy. The proposed pragmatic approach circumvents the communication delay problem found in traditional networked mobile robot systems where consensus graph theory and directed topology are applied. The simulation results and numerical analysis are provided to demonstrate the merits and effectiveness of the developed GA-KF-RBFNN to achieve self-evolving formation control of networked mobile robots. Full article
(This article belongs to the Special Issue Advanced Mobile Robotics)
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Open AccessFeature PaperReview Generation of Orbital Angular Momentum Modes Using Fiber Systems
Appl. Sci. 2019, 9(5), 1033; https://doi.org/10.3390/app9051033
Received: 30 January 2019 / Revised: 1 March 2019 / Accepted: 8 March 2019 / Published: 12 March 2019
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Abstract
Orbital angular momentum (OAM) beams, characterized by the helical phase wavefront, have received significant interest in various areas of study. There are many methods to generate OAM beams, which can be roughly divided into two types: spatial methods and fiber methods. As a [...] Read more.
Orbital angular momentum (OAM) beams, characterized by the helical phase wavefront, have received significant interest in various areas of study. There are many methods to generate OAM beams, which can be roughly divided into two types: spatial methods and fiber methods. As a natural shaper of OAM beams, the fibers exhibit unique merits, namely, miniaturization and a low insertion loss. In this paper, we review the recent advances in fiber OAM mode generation systems, in both the interior and exterior of the beams. We introduce the basic concepts of fiber modes and the generation and detection theories of OAM modes. In addition, fiber systems based on different nuclear devices are introduced, including the long-period fiber grating, the mode-selective coupler, microstructural optical fiber, and the photonic lantern. Finally, the key challenges and prospects for fiber OAM mode systems are discussed. Full article
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Open AccessArticle Effect of Carbon Nanotubes on Chloride Penetration in Cement Mortars
Appl. Sci. 2019, 9(5), 1032; https://doi.org/10.3390/app9051032
Received: 30 December 2018 / Revised: 25 February 2019 / Accepted: 1 March 2019 / Published: 12 March 2019
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Abstract
The study investigates the effect of carbon nanotubes on chloride penetration in nano-modified mortars and reports on the physical, electrical, and mechanical performance of the material. Mortars were artificially corroded and their surface electrical surface conductivity as well as flexural and compressive strength [...] Read more.
The study investigates the effect of carbon nanotubes on chloride penetration in nano-modified mortars and reports on the physical, electrical, and mechanical performance of the material. Mortars were artificially corroded and their surface electrical surface conductivity as well as flexural and compressive strength were measured. The influence of variable nanotube concentration in accelerated corrosion damage was evaluated. Nanotube concentration was found to significantly affect the permeability of the mortars; improvements in flexural and compressive response of mortars exposed to salt spray fog, compared to virgin specimens, were rationalized upon decreases in the apparent porosity of the materials due to filling of the pores with sodium chloride. Electrical resistivity was found to increase up to two orders of magnitude with respect to the surface value; above the percolation threshold, the property impressively increased up to five orders of magnitude. Full article
(This article belongs to the Special Issue Multi-Walled Carbon Nanotubes)
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Open AccessArticle MAG Welding Tests of Modern High Strength Steels with Minimum Yield Strength of 700 MPa
Appl. Sci. 2019, 9(5), 1031; https://doi.org/10.3390/app9051031
Received: 15 January 2019 / Revised: 4 March 2019 / Accepted: 6 March 2019 / Published: 12 March 2019
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Abstract
The modern high strength steel plates have an excellent combination of strength and toughness based on micro-alloying and complex microstructure. Retaining this combination of properties in the weld zone is a major challenge for applications in high-demanding structural construction. This work investigates the [...] Read more.
The modern high strength steel plates have an excellent combination of strength and toughness based on micro-alloying and complex microstructure. Retaining this combination of properties in the weld zone is a major challenge for applications in high-demanding structural construction. This work investigates the weldability of three different modern high strength steel plates, with a thickness of 8 mm. Two of the test materials were produced by a thermo-mechanically controlled process (TMCP) and one by a quenching and tempering method (Q&T). Two-passes MAG (metal active gas) welding was used with four different heat inputs. The tests implemented on all the materials included tensile, hardness profiles (HV5), Charpy-V impact toughness tests, and microstructure analysis using scanning electron microscope (SEM). For one of the TMCP steels, some extended tests were conducted to define how the tensile properties change along the weld line. These tests included tensile tests with digital image correlation (DIC), and 3-point bending tests. The most notable differences in mechanical properties of the welds between the materials were observed in Charpy-V impact toughness tests, mostly at the vicinity of the fusion line, with the Q&T steel more prone to embrittlement of the heat affected zone (HAZ) than the TMCP steels. Microstructural analysis revealed carbide concentration combined with coarse bainitic structures in HAZ of Q&T steel, explaining the more severe embrittlement. During the tensile tests, the DIC measurements have shown a strain localization in the softest region of the HAZ. Increasing the heat input resulted in earlier localization of the strain and less maximum strength. The tensile properties along the weld line were investigated in all welding conditions, and the results emphasize relevant and systematic differences of the yield strength at the transient zones near the start and end of the weld compared with the intermediate stationary domain. Full article
(This article belongs to the Special Issue Welding of Steels)
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Open AccessReview Controlling the Oxygen Electrocatalysis on Perovskite and Layered Oxide Thin Films for Solid Oxide Fuel Cell Cathodes
Appl. Sci. 2019, 9(5), 1030; https://doi.org/10.3390/app9051030
Received: 13 February 2019 / Revised: 5 March 2019 / Accepted: 6 March 2019 / Published: 12 March 2019
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Abstract
Achieving the fast oxygen reduction reaction (ORR) kinetics at the cathode of solid oxide fuel cells (SOFCs) is indispensable to enhance the efficiency of SOFCs at intermediate temperatures. Mixed ionic and electronic conducting (MIEC) oxides such as ABO3 perovskites and Ruddlesden-Popper (RP) [...] Read more.
Achieving the fast oxygen reduction reaction (ORR) kinetics at the cathode of solid oxide fuel cells (SOFCs) is indispensable to enhance the efficiency of SOFCs at intermediate temperatures. Mixed ionic and electronic conducting (MIEC) oxides such as ABO3 perovskites and Ruddlesden-Popper (RP) oxides (A2BO4) have been widely used as promising cathode materials owing to their attractive physicochemical properties. In particular, oxides in forms of thin films and heterostructures have enabled significant enhancement in the ORR activity. Therefore, we aim to give a comprehensive overview on the recent development of thin film cathodes of SOFCs. We discuss important advances in ABO3 and RP oxide thin film cathodes for SOFCs. Our attention is also paid to the influence of oxide heterostructure interfaces on the ORR activity of SOFC cathodes. Full article
(This article belongs to the Special Issue Progress in Solid-Oxide Fuel Cell Technology)
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Open AccessArticle Research on the Influence of Backlash on Mesh Stiffness and the Nonlinear Dynamics of Spur Gears
Appl. Sci. 2019, 9(5), 1029; https://doi.org/10.3390/app9051029
Received: 26 December 2018 / Revised: 4 March 2019 / Accepted: 7 March 2019 / Published: 12 March 2019
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Abstract
In light of ignoring the effect of backlash on mesh stiffness in existing gear dynamic theory, a precise profile equation was established based on the generating processing principle. An improved potential energy method was proposed to calculate the mesh stiffness. The calculation result [...] Read more.
In light of ignoring the effect of backlash on mesh stiffness in existing gear dynamic theory, a precise profile equation was established based on the generating processing principle. An improved potential energy method was proposed to calculate the mesh stiffness. The calculation result showed that when compared with the case of ignoring backlash, the mesh stiffness with backlash had an obvious decrease in a mesh cycle and the rate of decline had a trend of decreasing first and then increasing, so a stiffness coefficient was introduced to observe the effect of backlash. The Fourier series expansion was employed to fit the mesh stiffness rather than time-varying mesh stiffness, and the stiffness coefficient was fitted with the same method. The time-varying mesh stiffness was presented in terms of the piecewise function. The single degree of freedom model was employed, and the fourth order Runge–Kutta method was utilized to investigate the effect of backlash on the nonlinear dynamic characteristics with reference to the time history chart, phase diagram, Poincare map, and Fast Fourier Transformation (FFT) spectrogram. The numerical results revealed that the gear system primarily performs a non-harmonic-single-periodic motion. The partially enlarged views indicate that the system also exhibits small-amplitude and low-frequency motion. For different cases of backlash, the low-frequency motion sometimes shows excellent periodicity and stability and sometimes shows chaos. It is of practical guiding significance to know the mechanisms of some unusual noises as well as the design and manufacture of gear backlash. Full article
(This article belongs to the Special Issue Optical High-speed Information Technology)
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Open AccessArticle Numerical and Experimental Investigation of Guided Wave Propagation in a Multi-Wire Cable
Appl. Sci. 2019, 9(5), 1028; https://doi.org/10.3390/app9051028
Received: 10 February 2019 / Revised: 2 March 2019 / Accepted: 5 March 2019 / Published: 12 March 2019
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Abstract
Ultrasonic guided waves (UGWs) have attracted attention in the nondestructive testing and structural health monitoring (SHM) of multi-wire cables. They offer such advantages as a single measurement, wide coverage of the acoustic field, and long-range propagation ability. However, the mechanical coupling of multi-wire [...] Read more.
Ultrasonic guided waves (UGWs) have attracted attention in the nondestructive testing and structural health monitoring (SHM) of multi-wire cables. They offer such advantages as a single measurement, wide coverage of the acoustic field, and long-range propagation ability. However, the mechanical coupling of multi-wire structures complicates the propagation behaviors of guided waves and signal interpretation. In this paper, UGW propagation in these waveguides is investigated theoretically, numerically, and experimentally from the perspective of dispersion and wave structure, contact acoustic nonlinearity (CAN), and wave energy transfer. Although the performance of all possible propagating wave modes in a multi-wire cable at different frequencies could be obtained by dispersion analysis, it is ineffective to analyze the frequency behaviors of the wave signals of a certain mode, which could be analyzed using the CAN effect. The CAN phenomenon of two mechanically coupled wires in contact was observed, which was demonstrated by numerical guided wave simulation and experiments. Additionally, the measured guided wave energy of wires located in different layers of an aluminum conductor steel-reinforced cable accords with the theoretical prediction. The model of wave energy distribution in different layers of a cable also could be used to optimize the excitation power of transducers and determine the effective monitoring range of SHM. Full article
(This article belongs to the Special Issue Ultrasonic Guided Waves)
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Open AccessArticle Selection of Optimal Hyperspectral Wavebands for Detection of Discolored, Diseased Rice Seeds
Appl. Sci. 2019, 9(5), 1027; https://doi.org/10.3390/app9051027
Received: 1 January 2019 / Revised: 26 February 2019 / Accepted: 5 March 2019 / Published: 12 March 2019
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Abstract
The inspection of rice grain that may be infected by seedborne disease is important for ensuring uniform plant stands in production fields as well as preventing proliferation of some seedborne diseases. The goal of this study was to use a hyperspectral imaging (HSI) [...] Read more.
The inspection of rice grain that may be infected by seedborne disease is important for ensuring uniform plant stands in production fields as well as preventing proliferation of some seedborne diseases. The goal of this study was to use a hyperspectral imaging (HSI) technique to find optimal wavelengths and develop a model for detecting discolored, diseased rice seed infected by bacterial panicle blight (Burkholderia glumae), a seedborne pathogen. For this purpose, the HSI data spanning the visible/near-infrared wavelength region between 400 and 1000 nm were collected for 500 sound and discolored rice seeds. For selecting optimal wavelengths to use for detecting diseased seed, a sequential forward selection (SFS) method combined with various spectral pretreatments was employed. To evaluate performance based on optimal wavelengths, support vector machine (SVM) and linear and quadratic discriminant analysis (LDA and QDA) models were developed for detection of discolored seeds. As a result, the violet and red regions of the visible spectrum were selected as key wavelengths reflecting the characteristics of the discolored rice seeds. When using only two or only three selected wavelengths, all of the classification methods achieved high classification accuracies over 90% for both the calibration and validation sample sets. The results of the study showed that only two to three wavelengths are needed to differentiate between discolored, diseased and sound rice, instead of using the entire HSI wavelength regions. This demonstrates the feasibility of developing a low cost multispectral imaging technology based on these selected wavelengths for non-destructive and high-throughput screening of diseased rice seed. Full article
(This article belongs to the Special Issue Applications of Hyperspectral Imaging for Food and Agriculture II)
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Open AccessReview A Systematic Review of Oxygen Therapy for the Management of Medication-Related Osteonecrosis of the Jaw (MRONJ)
Appl. Sci. 2019, 9(5), 1026; https://doi.org/10.3390/app9051026
Received: 22 January 2019 / Revised: 20 February 2019 / Accepted: 6 March 2019 / Published: 12 March 2019
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Abstract
Background: Medication-related osteonecrosis of the jaw (MRONJ) can be a life changing iatrogenic complication of antiresorptive and antiangiogenic drug therapy. It is most often associated with high doses of these medications that are used to prevent skeletal-related events in patients with cancer and [...] Read more.
Background: Medication-related osteonecrosis of the jaw (MRONJ) can be a life changing iatrogenic complication of antiresorptive and antiangiogenic drug therapy. It is most often associated with high doses of these medications that are used to prevent skeletal-related events in patients with cancer and bone pathologies. Unfortunately, managing MRONJ lesions has proven difficult and remains a major challenge for clinicians. Due to the lack of efficacy in treating MRONJ by surgical modalities (local debridement and free flap reconstruction), the nonsurgical management of MRONJ is still advocated to aid healing or avoid disease progression. The aim of this systematic review is to identify, analyse and understand the published evidence related to the success of oxygen therapies such as ozone (OT) and hyperbaric oxygen (HBO) in treating MRONJ. Material and methods: A multi-database (PubMed, MEDLINE, EMBASE, CINAHL and Cochrane CENTRAL) systematic search was performed by three authors. The identified articles were independently assessed for their risk of bias. Any type of study evaluating humans treated with antiresorptive and antiangiogenic drugs were considered. The aim is primarily to evaluate the success of OT and HBO in resolving MRONJ and secondarily to identify any improvements in quality of life (QoL), rate of complications, time-to-event and severity of side effects related to these treatments. Results: In total, just 13 studies were eligible for analysis. A pooled total of 313 patients (HBO group n = 82; OT group n = 231) described in these studies have shown good tolerance for oxygen therapies. Complete resolution of MRONJ was reported in 44.58% of OT patients but only 5.17% of the HBO group. Progression of MRONJ was reported only in the HBO studies in 10.34% of cases (6 patients). The quality of evidence was low or very low in all studies. This was due to limitations in how the studies were designed, run and reported. Conclusions: Based on the limited data available, it is difficult to suggest OT is better or worse than HBO or whether it is better than a placebo. As the level of evidence available is low, this necessitates larger well-designed trials to justify these interventions for patients affected by MRONJ. Full article
(This article belongs to the Section Applied Biosciences and Bioengineering)
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Open AccessArticle A Multi-Period Approach for the Optimal Energy Retrofit Planning of Street Lighting Systems
Appl. Sci. 2019, 9(5), 1025; https://doi.org/10.3390/app9051025
Received: 15 February 2019 / Revised: 5 March 2019 / Accepted: 7 March 2019 / Published: 12 March 2019
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Abstract
Investing in the optimal measures for improving the energy efficiency of urban street lighting systems has become strategic for the economic, technological and social development of cities. The decision-making process for the selection of the optimal set of interventions is not so straightforward. [...] Read more.
Investing in the optimal measures for improving the energy efficiency of urban street lighting systems has become strategic for the economic, technological and social development of cities. The decision-making process for the selection of the optimal set of interventions is not so straightforward. Several criticalities-such as difficulties getting access to credit for companies involved in street lighting systems refurbishment, budget constraints of municipalities, and unawareness of the actual energy and economic performance after a retrofitting intervention-require a decision-making approach that supports the city energy manager in selecting the optimal street lighting energy efficiency retrofitting solution while looking not only based on the available budget, but also based on the future savings in energy expenditures. In this context, the purpose of our research is to develop an effective decision-making model supporting the optimal multi-period planning of the street lighting energy efficiency retrofitting, which proves to be more effective and beneficial than the classical single-period approach and has never before been applied to the considered public lighting system context. The proposed methodology is applied to a real street lighting system in the city of Bari, Italy, showing the energy savings and financial benefit obtained through the proposed method. Numerical experiments are used to investigate and quantify the effects of using a multi-period planning approach instead of a single-period approach. Full article
(This article belongs to the Special Issue Smart Urban Lighting Systems)
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Open AccessArticle The Influence of Capacitance and Inductance Changes on Frequency Response of Transformer Windings
Appl. Sci. 2019, 9(5), 1024; https://doi.org/10.3390/app9051024
Received: 25 February 2019 / Revised: 7 March 2019 / Accepted: 8 March 2019 / Published: 12 March 2019
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Abstract
Frequency Response Analysis (FRA) is a test method used for assessment of mechanical condition of transformer active parts. Its biggest problem is the interpretation of test results, namely the relationship between scale of differences between compared curves and the decision for further operation [...] Read more.
Frequency Response Analysis (FRA) is a test method used for assessment of mechanical condition of transformer active parts. Its biggest problem is the interpretation of test results, namely the relationship between scale of differences between compared curves and the decision for further operation of the given transformer. Very often visible differences between two FRA curves do not mean that there is a deformation in the winding. The cause of the curve shift may come from other elements of the transformer that influence inductive or capacitive parameters. This paper takes under consideration the influence of both capacitance and inductance changes on transformer frequency response (FR). The analysis is performed with the computer model of a transformer and also some experimental results are presented, showing the influence of capacitance and inductance changes on the FR of real transformers. The results of research showed that this influence may lead to misleading effects on the shape of FR characteristics. The paper presents an analysis that can be used in the assessment of FRA measurement, especially in the case of uncertain data comparison results. Full article
(This article belongs to the Special Issue Power System Reliability)
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Open AccessArticle Rheological Characteristics Evaluation of Bitumen Composites Containing Rock Asphalt and Diatomite
Appl. Sci. 2019, 9(5), 1023; https://doi.org/10.3390/app9051023
Received: 13 January 2019 / Revised: 28 February 2019 / Accepted: 6 March 2019 / Published: 12 March 2019
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Abstract
Previous studies have showed that rock asphalt (RA) or diatomite were used to modify the petroleum bitumen. This paper presents the findings from a study conducted to evaluate the potential impact of RA and diatomite on the rheological characteristics of bitumen composites. RA [...] Read more.
Previous studies have showed that rock asphalt (RA) or diatomite were used to modify the petroleum bitumen. This paper presents the findings from a study conducted to evaluate the potential impact of RA and diatomite on the rheological characteristics of bitumen composites. RA and diatomite with three different dosages were added into the petroleum bitumen: 18% RA, 13% RA+7% diatomite, and 16% RA+9% diatomite by weight. The rheological characteristics of the RA and diatomite modified bitumens were evaluated in this study. The tests conducted included temperature sweep and frequency sweep tests with a dynamic shear rheometer (DSR), a Brookfield rotation viscosity test, and a scanning electron microscope test. The research showed that the addition of RA and diatomite to petroleum bitumen considerably increased the apparent viscosity, dynamic shear modulus, and rutting resistance in bitumen specimens. However, the DSR test indicated a slight reduction in the fatigue performance of composites made of RA and diatomite modified bitumens. Overall, RA and diatomite are good modifiers for petroleum bitumen for a performance improvement. Full article
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Open AccessArticle Optimal Design of Hybrid PV-Battery System in Residential Buildings: End-User Economics, and PV Penetration
Appl. Sci. 2019, 9(5), 1022; https://doi.org/10.3390/app9051022
Received: 1 February 2019 / Revised: 6 March 2019 / Accepted: 8 March 2019 / Published: 12 March 2019
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Abstract
This paper proposes an optimal design for hybrid grid-connected Photovoltaic (PV) Battery Energy Storage Systems (BESSs). A smart grid consisting of PV generation units, stationary Energy Storage Systems (ESSs), and domestic loads develops a multi-objective optimization algorithm. The optimization aims at minimizing the [...] Read more.
This paper proposes an optimal design for hybrid grid-connected Photovoltaic (PV) Battery Energy Storage Systems (BESSs). A smart grid consisting of PV generation units, stationary Energy Storage Systems (ESSs), and domestic loads develops a multi-objective optimization algorithm. The optimization aims at minimizing the Total Cost of Ownership (TCO) and the Voltage Deviation (VD) while considering the direct and indirect costs for the prosumer, and the system stability with regard to intermittent PV generation. The optimal solution for the optimization of the PV-battery system sizing with regard to economic viability and the stability of operation is found while using the Genetic Algorithm (GA) with the Pareto front. In addition, a fuzzy logic-based controller is developed to schedule the charging and discharging of batteries while considering the technical and economic aspects, such as battery State of Charge (SoC), voltage profile, and on/off-peak times to shave the consumption peaks. Thus, a hybrid approach that combines a Fuzzy Logic Controller (FLC) and the GA is developed for the optimal sizing of the combined Renewable Energy Sources (RESs) and ESSs, resulting in reductions of approximately 4% and 17% for the TCO and the VD, respectively. Furthermore, a sensitivity cost-effectiveness analysis of the complete system is conducted to highlight and assess the profitability and the high dependency of the optimal system configuration on battery prices. Full article
(This article belongs to the Special Issue Intelligent Energy Management of Electrical Power Systems)
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Open AccessArticle Analysis of Life Cycle Environmental Impact of Recycled Aggregate
Appl. Sci. 2019, 9(5), 1021; https://doi.org/10.3390/app9051021
Received: 31 December 2018 / Revised: 21 February 2019 / Accepted: 22 February 2019 / Published: 12 March 2019
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Abstract
This study assessed the influence of matter discharged during the production (dry/wet) of recycled aggregate on global warming potential (GWP) and acidification potential (AP), eutrophication potential (EP), ozone depletion potential (ODP), biotic resource depletion potential (ADP), photochemical ozone creation potential (POCP) using the [...] Read more.
This study assessed the influence of matter discharged during the production (dry/wet) of recycled aggregate on global warming potential (GWP) and acidification potential (AP), eutrophication potential (EP), ozone depletion potential (ODP), biotic resource depletion potential (ADP), photochemical ozone creation potential (POCP) using the ISO 14044 (LCA) standard. The LCIA of dry recycled aggregate was 2.94 × 10−2 kg-CO2eq/kg, 2.93 × 10−5 kg-SO2eq/kg, 5.44 × 10−6 kg-PO43eq/kg, 4.70 × 10−10 kg-CFC11eq/kg, 1.25 × 10−5 kg-C2H4eq/kg, and 1.60 × 10−5 kg-Antimonyeq/kg, respectively. The environmental impact of recycled aggregate (wet) was up to 16~40% higher compared with recycled aggregate (dry); the amount of energy used by impact crushers while producing wet recycled aggregate was the main cause for this result. The environmental impact of using recycled aggregate was found to be up to twice as high as that of using natural aggregate, largely due to the greater simplicity of production of natural aggregate requiring less energy. However, ADP was approximately 20 times higher in the use of natural aggregate because doing so depletes natural resources, whereas recycled aggregate is recycled from existing construction waste. Among the life cycle impacts assessment of recycled aggregate, GWP was lower than for artificial light-weight aggregate but greater than for slag aggregate. Full article
(This article belongs to the Special Issue New Trends in Recycled Aggregate Concrete)
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Open AccessArticle Large-Scale Whale-Call Classification by Transfer Learning on Multi-Scale Waveforms and Time-Frequency Features
Appl. Sci. 2019, 9(5), 1020; https://doi.org/10.3390/app9051020
Received: 27 January 2019 / Revised: 6 March 2019 / Accepted: 7 March 2019 / Published: 12 March 2019
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Abstract
Whale vocal calls contain valuable information and abundant characteristics that are important for classification of whale sub-populations and related biological research. In this study, an effective data-driven approach based on pre-trained Convolutional Neural Networks (CNN) using multi-scale waveforms and time-frequency feature representations is [...] Read more.
Whale vocal calls contain valuable information and abundant characteristics that are important for classification of whale sub-populations and related biological research. In this study, an effective data-driven approach based on pre-trained Convolutional Neural Networks (CNN) using multi-scale waveforms and time-frequency feature representations is developed in order to perform the classification of whale calls from a large open-source dataset recorded by sensors carried by whales. Specifically, the classification is carried out through a transfer learning approach by using pre-trained state-of-the-art CNN models in the field of computer vision. 1D raw waveforms and 2D log-mel features of the whale-call data are respectively used as the input of CNN models. For raw waveform input, windows are applied to capture multiple sketches of a whale-call clip at different time scales and stack the features from different sketches for classification. When using the log-mel features, the delta and delta-delta features are also calculated to produce a 3-channel feature representation for analysis. In the training, a 4-fold cross-validation technique is employed to reduce the overfitting effect, while the Mix-up technique is also applied to implement data augmentation in order to further improve the system performance. The results show that the proposed method can improve the accuracies by more than 20% in percentage for the classification into 16 whale pods compared with the baseline method using groups of 2D shape descriptors of spectrograms and the Fisher discriminant scores on the same dataset. Moreover, it is shown that classifications based on log-mel features have higher accuracies than those based directly on raw waveforms. The phylogeny graph is also produced to significantly illustrate the relationships among the whale sub-populations. Full article
(This article belongs to the Section Acoustics and Vibrations)
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Open AccessReview The Growth Methods and Field Emission Studies of Low-Dimensional Boron-Based Nanostructures
Appl. Sci. 2019, 9(5), 1019; https://doi.org/10.3390/app9051019
Received: 31 January 2019 / Revised: 25 February 2019 / Accepted: 6 March 2019 / Published: 12 March 2019
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Abstract
Based on the morphology characteristics, low-dimensional (LD) nanostructures with high aspect ratio can be usually divided into nanowire, nanocone, nanotube, nanorod, nanoribbon, nanobelt and so on. Among numerous LD nanostructures, boron-based nanostructures attracted much interest in recent years because they have high melting-point, [...] Read more.
Based on the morphology characteristics, low-dimensional (LD) nanostructures with high aspect ratio can be usually divided into nanowire, nanocone, nanotube, nanorod, nanoribbon, nanobelt and so on. Among numerous LD nanostructures, boron-based nanostructures attracted much interest in recent years because they have high melting-point, large electric and thermal conductivity, and low work function. Compared to traditional thermal emission, field emission (FE) has notable advantages, such as lower power dissipation, longer working life, room-temperature operation, higher brightness and faster switching speed. Most studies reveal they have lower turn-on and threshold fields as well as high current density, which are believed as ideal cold cathode nanomaterials. In this review, we will firstly introduce the growth methods of LD boron-based nanostructures (boron monoelement and rare-earth metal hexaboride). Then, we will discuss their FE properties and applications. At last, the conclusions and outlook will be summarized based on the above studies. Full article
(This article belongs to the Special Issue Field Emission from Graphene and other Nanostructures)
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Open AccessArticle Influence of Initial Phase Modulation on the Sensitivity of the Optical Fiber Sagnac Acoustic Emission Sensor
Appl. Sci. 2019, 9(5), 1018; https://doi.org/10.3390/app9051018
Received: 26 January 2019 / Revised: 1 March 2019 / Accepted: 6 March 2019 / Published: 12 March 2019
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Abstract
Improving the phase sensitivity of the optical fiber Sagnac sensor is very important for accurately detecting weak signals of acoustic emission. Theoretical analysis shows that the initial phase of the sensor is π under ideal conditions, and the maximum phase sensitivity is obtained [...] Read more.
Improving the phase sensitivity of the optical fiber Sagnac sensor is very important for accurately detecting weak signals of acoustic emission. Theoretical analysis shows that the initial phase of the sensor is π under ideal conditions, and the maximum phase sensitivity is obtained when the bias phase is π/2. In this work, an experimental system was built with an aluminum alloy plate as the experimental object. The initial phase of the sensor was modulated by a Y-branch waveguide, and the fitting curve of the experimental data was in good agreement with the curve of the numerical simulation. Moreover, our experiments show there was a single value for the bias phase of π/2, which significantly deviated from the theoretical value. The results show that the greatest phase sensitivity of the sensor not only could be increased by nearly nine times through modulating the initial phase, but also could suppress the harmonic interferences in the sensing system. This study can provide a useful reference for improving the phase sensitivity of the optical fiber Sagnac AE sensor in practical applications. Full article
(This article belongs to the Special Issue Recent Progress in Fiber Optic Sensors: Bringing Light to Measurement)
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Open AccessArticle Cracking Behavior of RC Beams Strengthened with Different Amounts and Layouts of CFRP
Appl. Sci. 2019, 9(5), 1017; https://doi.org/10.3390/app9051017
Received: 4 February 2019 / Revised: 7 March 2019 / Accepted: 7 March 2019 / Published: 12 March 2019
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Abstract
The bending and shear behavior of RC beams strengthened with Carbon Fiber-Reinforced Polymers (CFRP) is the primary objective of this paper, which is focused on the failure mechanisms and on the moment-curvature response prior-to, and post, strengthening with different amounts and layouts of [...] Read more.
The bending and shear behavior of RC beams strengthened with Carbon Fiber-Reinforced Polymers (CFRP) is the primary objective of this paper, which is focused on the failure mechanisms and on the moment-curvature response prior-to, and post, strengthening with different amounts and layouts of the CFRP reinforcement. Seven reinforced concrete beams were tested in 4-point bending, one without any CFRP reinforcement (control beam, Specimen C1), four with the same amount of CFRP in flexure but with different layouts of the reinforcement for shear (Specimens B1–B4), and two with extra reinforcement in bending, with and without reinforcement in shear (Specimens B6 and B5, respectively). During each test, the load and the mid-span deflection were monitored, as well as the crack pattern. The experimental results indicate that: (a) increasing the CFRP reinforcement above certain levels does not necessarily increase the bearing capacity; (b) the structural performance can be optimized through an appropriate combination of CFRP flexural and shear reinforcement; and (c) bond properties at the concrete–CFRP interface play a vital role, as the failure is very often triggered by the debonding of the CFRP strips. The experimental values were also verified analytically and a close agreement between the analytical and experimental values was achieved. Full article
(This article belongs to the Special Issue Fatigue and Fracture of Non-metallic Materials and Structures)
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Open AccessArticle Cut-Price Fabrication of Free-standing Porous Carbon Nanofibers Film Electrode for Lithium-ion Batteries
Appl. Sci. 2019, 9(5), 1016; https://doi.org/10.3390/app9051016
Received: 28 January 2019 / Revised: 21 February 2019 / Accepted: 28 February 2019 / Published: 12 March 2019
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Abstract
Freestanding thin film electrodes are competitive candidate materials for high-performance energy stockpile equipment due to their self-supporting structure and because they lack any polymer binder or conductive additive. In our work, a porous carbon nanofiber film (PCNF) electrode has been synthesized via a [...] Read more.
Freestanding thin film electrodes are competitive candidate materials for high-performance energy stockpile equipment due to their self-supporting structure and because they lack any polymer binder or conductive additive. In our work, a porous carbon nanofiber film (PCNF) electrode has been synthesized via a convenient and low-cost electrospinning approach and the following carbonization and air etching process. The obtained PCNF electrode sample shows a high reversible capacity (1138 mAh g−1 at 0.1 C), remarkable rate capacity (101.2 mAh g−1 at 15 C), and superior cycling stability with a lower capacity decay rate of ~0.013% each cycle upon 1000 cycles (278 mAh g−1 at 5 C). The prominent electrochemical performance of PCNF can be put down to the stable self-supporting conductive structure and the porous feature in each carbon nanofiber, which will significantly promote the transfer tempo of Li-ion and electron and relieve the large volume change during inserting lithium ion. More interestingly, this work exhibits a low-cost and primitive strategy to fabricate thin film anode for lithium-ion batteries. Full article
(This article belongs to the Section Nanotechnology and Applied Nanosciences)
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Open AccessArticle Study on Low-Speed Steering Resistance Torque of Vehicles Considering Friction between Tire and Pavement
Appl. Sci. 2019, 9(5), 1015; https://doi.org/10.3390/app9051015
Received: 25 December 2018 / Revised: 14 February 2019 / Accepted: 7 March 2019 / Published: 12 March 2019
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Abstract
Electric power steering (EPS) systems under existing vehicle power systems cannot provide enough power for heavy-duty commercial vehicles under pivot or low-speed steering conditions. To solve this problem, the paper proposes an EPS system that is based on the hybrid power system constituted [...] Read more.
Electric power steering (EPS) systems under existing vehicle power systems cannot provide enough power for heavy-duty commercial vehicles under pivot or low-speed steering conditions. To solve this problem, the paper proposes an EPS system that is based on the hybrid power system constituted by the vehicle power system and the supercapacitor in parallel. In order to provide a theoretical basis for the intervention and withdrawal mechanisms of a super-capacitor in the new EPS, the law of steering resistance torque at a low or extremely low vehicle speed should be explored. Firstly, the finite element model of tire/pavement was established to conduct the simulation and calculation of the low-speed steering friction force between the tire and pavement, and to obtain the fitting expression of the equivalent steering friction coefficient with the running speed of the tire. Secondly, the expression of the steering friction torque was deduced based on the calculus theory and mathematical model of the low-speed steering resistance torque, including the steering friction torque and aligning torques, established to conduct the simulation of the equivalent resistance torque applied on a steering column under low-speed condition. Subsequently, the real vehicle experiments were carried out and comparisons of the experimental results and simulation results was performed. The consistency indicated that the model of low-speed steering resistance torque had a high accuracy. Finally, the law of low-speed steering resistance torque with a vehicle speed and steering wheel angle were analyzed according to the 3D surface plot drawn from the simulation results. Full article
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Open AccessArticle Enhancement of the Oil Absorption Capacity of Poly(Lactic Acid) Nano Porous Fibrous Membranes Derived via a Facile Electrospinning Method
Appl. Sci. 2019, 9(5), 1014; https://doi.org/10.3390/app9051014
Received: 25 January 2019 / Revised: 25 February 2019 / Accepted: 5 March 2019 / Published: 12 March 2019
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Abstract
Oil spilling has been a serious problem in the world for a long time, which can bring toxic substances to marine life. A large number of researchers around the world have introduced many measures to address this problem. One of the effective methods [...] Read more.
Oil spilling has been a serious problem in the world for a long time, which can bring toxic substances to marine life. A large number of researchers around the world have introduced many measures to address this problem. One of the effective methods to remove oil from the oil/water mixture is to absorb oil from the mixture. Here, we prepared porous poly(lactic acid) (PLA) membranes using the electrospinning approach with different sized syringe needles, and used these membranes to absorb oil from the top of the water. It was found that the diameter of the needle has a big impact on the size and structure of the pores on the PLA fibers. The oil absorption capacity of membranes increases with a decreasing needle diameter due to the increased pore volume and specific surface area. The highest absorption capacity reached was 42.38 g/g for vacuum pump oil, 28.17 g/g for peanut oil, and 6.74 g/g for diesel oil. Full article
(This article belongs to the Special Issue Electrospinning Technology: Control of Morphology for Nanostructure)
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Open AccessReview Nano-Structured Demineralized Human Dentin Matrix to Enhance Bone and Dental Repair and Regeneration
Appl. Sci. 2019, 9(5), 1013; https://doi.org/10.3390/app9051013
Received: 3 February 2019 / Revised: 25 February 2019 / Accepted: 1 March 2019 / Published: 12 March 2019
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Abstract
Demineralized dentin matrix (DDM), derived from human teeth, is an excellent scaffold material with exciting bioactive properties to enhance bone and dental tissue engineering efficacy. In this article, first the nano-structure and bioactive components of the dentin matrix were reviewed. Then the preparation [...] Read more.
Demineralized dentin matrix (DDM), derived from human teeth, is an excellent scaffold material with exciting bioactive properties to enhance bone and dental tissue engineering efficacy. In this article, first the nano-structure and bioactive components of the dentin matrix were reviewed. Then the preparation methods of DDM and the resulting properties were discussed. Next, the efficacy of DDM as a bone substitute with in vitro and in vivo properties were analyzed. In addition, the applications of DDM in tooth regeneration with promising results were described, and the drawbacks and future research needs were also discussed. With the extraction of growth factors from DDM and the nano-structural properties of DDM, previous studies also broadened the use of DDM as a bioactive carrier for growth factor delivery. In addition, due to its excellent physical and biological properties, DDM was also investigated for incorporation into other biomaterials design and fabrication, yielding great enhancements in hard tissue regeneration efficacy. Full article
(This article belongs to the Special Issue Nanomaterials for Bone Tissue Engineering)
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Open AccessArticle Using Computer Simulation to Investigate Which Joint Angle Changes Have the Most Effect on Ball Release Speed in Overarm Throwing
Appl. Sci. 2019, 9(5), 999; https://doi.org/10.3390/app9050999
Received: 31 December 2018 / Revised: 9 February 2019 / Accepted: 5 March 2019 / Published: 11 March 2019
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Abstract
Efficient throwing mechanics is predicated on a pitcher’s ability to perform a sequence of movements of body segments, which progresses from the legs, pelvis, and trunk to the smaller, distal arm segments. Each segment plays a vital role in achieving maximum ball velocity [...] Read more.
Efficient throwing mechanics is predicated on a pitcher’s ability to perform a sequence of movements of body segments, which progresses from the legs, pelvis, and trunk to the smaller, distal arm segments. Each segment plays a vital role in achieving maximum ball velocity at ball release. The perturbation of one joint angle has an effect on the ball release speed. An eight-segment angle-driven simulation model of the trunk, upper limbs and ball was developed to determine which joint angle changes have the most influence on ball release speed in overarm throwing for an experienced pitcher. Fifteen overarm throwing trials were recorded, and the joint angle time histories of each trial were input into the simulation model. Systematically replacing each joint angle time history with a constant value showed that overarm throwing was sensitive (≥5 m/s effect on ball release speed) to trunk extension/flexion and upper arm external/internal rotation, and very sensitive (≥10 m/s effect) to forearm extension/flexion. Computer simulation allows detailed analysis and complete control to investigate contributions to performance, and the key joint angle changes for overarm throwing were identified in this analysis. Full article
(This article belongs to the Special Issue Computer Science in Sport)
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Open AccessArticle Optimal Design of a Tower Type SCR-deNOx Facility for a 1000 MW Coal-Fired Power Plant Based on CFD Simulation and FMT Validation
Appl. Sci. 2019, 9(5), 1012; https://doi.org/10.3390/app9051012
Received: 12 February 2019 / Revised: 4 March 2019 / Accepted: 7 March 2019 / Published: 11 March 2019
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Abstract
Selective catalytic reduction (SCR) is one of the most efficient methods to reduce NOx emissions from coal-fired power plants. This paper deals with an optimal design tower type SCR-deNOx facility for a 1000 MW coal-fired power plant. Combined with computational fluid [...] Read more.
Selective catalytic reduction (SCR) is one of the most efficient methods to reduce NOx emissions from coal-fired power plants. This paper deals with an optimal design tower type SCR-deNOx facility for a 1000 MW coal-fired power plant. Combined with computational fluid dynamics (CFD), the configuration of the baffles geometry was studied with spatial constraints. Flow field was regulated at the ammonia injection grid (AIG) with the dual aim of reducing difficulties in implementing the non-uniformed ammonia (NH3) injection strategy and achieving a more homogeneous distribution at the catalyst entrance. A flow model test (FMT) was carried out at a laboratory scale to verify the design results. The results of the flow model test are in good agreement with the computational fluid dynamics. It is indicated that small-sized baffles are recommended for installation at the upstream side of the facility as the optimal design and ability to regulate the flow field at the ammonia injection grid makes it an effective way to deal with spatial constraints. This paper provides a good reference for optimizing the tower type SCR-deNOx facilities with spatial constraints. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle The Development of a Soft Robot Hand with Pin-Array Structure
Appl. Sci. 2019, 9(5), 1011; https://doi.org/10.3390/app9051011
Received: 20 February 2019 / Revised: 5 March 2019 / Accepted: 6 March 2019 / Published: 11 March 2019
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Abstract
This paper proposes a soft robot hand with pin-array structure and self-adaptive function, CTSA-II hand, where CTSA is the Cluster tube self-adaption. The CTSA-II hand is designed with a quite concise structure and consists of bases, a pin array, a spring array, and [...] Read more.
This paper proposes a soft robot hand with pin-array structure and self-adaptive function, CTSA-II hand, where CTSA is the Cluster tube self-adaption. The CTSA-II hand is designed with a quite concise structure and consists of bases, a pin array, a spring array, and a membrane. When the CTSA-II hand grasps an object, the pins will slide along the trajectory to conform to the profile of the object under the reaction force applied by the object, and thus the outer membrane will form a specific shape, and then the vacuum drives the CTSA-II hand to grasp the object. Theoretical analysis shows that the CTSA-II hand can generate enough grasping force and get good stability. Moreover, the optimization of its structure is achieved by studying the effects of specific parameters. The capture experimental results of the prototype show that the CTSA-II hand can realize self-adaptive grasping of different sizes and shapes with a high degree of fit and a high success rate. A series of research experiments show the influence of various factors on the grasping force, which verifies the results of the theoretical analysis with the CTSA-II hand. Compared to the traditional robot hand, the CTSA-II hand has good crawl performance, concise structure, small volume, and easy assembly. Full article
(This article belongs to the Special Issue Soft Robotics: New Design, Control, and Application)
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Open AccessArticle An Automatic Modulation Recognition Method with Low Parameter Estimation Dependence Based on Spatial Transformer Networks
Appl. Sci. 2019, 9(5), 1010; https://doi.org/10.3390/app9051010
Received: 7 February 2019 / Revised: 5 March 2019 / Accepted: 7 March 2019 / Published: 11 March 2019
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Abstract
Recently, automatic modulation recognition has been an important research topic in wireless communication. Due to the application of deep learning, it is prospective of using convolution neural networks on raw in-phase and quadrature signals in developing automatic modulation recognition methods. However, the errors [...] Read more.
Recently, automatic modulation recognition has been an important research topic in wireless communication. Due to the application of deep learning, it is prospective of using convolution neural networks on raw in-phase and quadrature signals in developing automatic modulation recognition methods. However, the errors introduced during signal reception and processing will greatly deteriorate the classification performance, which affects the practical application of such methods. Therefore, we first analyze and quantify the errors introduced by signal detection and isolation in noncooperative communication through a baseline convolution neural network. In response to these errors, we then design a signal spatial transformer module based on the attention model to eliminate errors by a priori learning of signal structure. By cascading a signal spatial transformer module in front of the baseline classification network, we propose a method that can adaptively resample the signal capture to adjust time drift, symbol rate, and clock recovery. Besides, it can also automatically add a perturbation on the signal carrier to correct frequency offset. By applying this improved model to automatic modulation recognition, we obtain a significant improvement in classification performance compared with several existing methods. Our method significantly improves the prospect of the application of automatic modulation recognition based on deep learning under nonideal synchronization. Full article
(This article belongs to the Special Issue Advances in Deep Learning)
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Open AccessArticle Image Shadow Removal Using End-To-End Deep Convolutional Neural Networks
Appl. Sci. 2019, 9(5), 1009; https://doi.org/10.3390/app9051009
Received: 9 January 2019 / Revised: 20 February 2019 / Accepted: 5 March 2019 / Published: 11 March 2019
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Abstract
Image degradation caused by shadows is likely to cause technological issues in image segmentation and target recognition. In view of the existing shadow removal methods, there are problems such as small and trivial shadow processing, the scarcity of end-to-end automatic methods, the neglecting [...] Read more.
Image degradation caused by shadows is likely to cause technological issues in image segmentation and target recognition. In view of the existing shadow removal methods, there are problems such as small and trivial shadow processing, the scarcity of end-to-end automatic methods, the neglecting of light, and high-level semantic information such as materials. An end-to-end deep convolutional neural network is proposed to further improve the image shadow removal effect. The network mainly consists of two network models, an encoder–decoder network and a small refinement network. The former predicts the alpha shadow scale factor, and the latter refines to obtain sharper edge information. In addition, a new image database (remove shadow database, RSDB) is constructed; and qualitative and quantitative evaluations are made on databases such as UIUC, UCF and newly-created databases (RSDB) with various real images. Using the peak signal-to-noise ratio (PSNR) and the structural similarity (SSIM) for quantitative analysis, the algorithm has a big improvement on the PSNR and the SSIM as opposed to other methods. In terms of qualitative comparisons, the network shadow has a clearer and shadow-free image that is consistent with the original image color and texture, and the detail processing effect is much better. The experimental results show that the proposed algorithm is superior to other algorithms, and it is more robust in subjective vision and objective quantization. Full article
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Open AccessArticle Efficient Demulsification of Acidic Oil-In-Water Emulsions with Silane-Coupled Modified TiO2 Pillared Montmorillonite
Appl. Sci. 2019, 9(5), 1008; https://doi.org/10.3390/app9051008
Received: 28 January 2019 / Revised: 5 March 2019 / Accepted: 5 March 2019 / Published: 11 March 2019
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Abstract
Emulsified pickling waste liquid, derived from cleaning oily hardware, cause serious environmental and ecological issues. In this work, a series of grafted (3-aminopropyl)triethoxysilane (APTES) TiO2 pillared montmorillonite (Mt), Ti-Mt-APTES, are prepared and characterized for their assessment in demulsification of acidic oil-in-water emulsion. [...] Read more.
Emulsified pickling waste liquid, derived from cleaning oily hardware, cause serious environmental and ecological issues. In this work, a series of grafted (3-aminopropyl)triethoxysilane (APTES) TiO2 pillared montmorillonite (Mt), Ti-Mt-APTES, are prepared and characterized for their assessment in demulsification of acidic oil-in-water emulsion. After titanium hydrate is introduced through ion exchange, montmorillonite is modified by hydrophobic groups coming from APTES. The Ti-Mt-APTES in acidic oil-in-water emulsion demulsification performance and mechanism are studied. Results show that the prepared Ti-Mt-APTES has favorable demulsification performance. The Ti-Mt-APTES demulsification efficiency (ED) increased to an upper limit value when the mass ratio of APTES to the prepared TiO2 pillared montmorillonite (Ti-Mt) (RA/M) was 0.10 g/g, and the 5 h is the optimal continuous stirring time for breaking the acidic oil-in-water emulsion by Ti-Mt-APTES. The ED increased to 94.8% when 2.5 g/L of Ti-Mt-APTES is added into the acidic oil-in-water emulsion after 5 h. An examination of the demulsification mechanism revealed that amphiphilicity and electrostatic interaction both played vital roles in oil-in-water separation. It is demonstrated that Ti-Mt-APTES is a promising, economical demulsifier for the efficient treatment of acidic oil-in-water emulsions. Full article
(This article belongs to the Special Issue New Materials and Techniques for Environmental Science)
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Open AccessArticle Application of Hybrid PCM Thermal Energy Storages with and without Al Foams in Solar Heating/Cooling and Ground Source Absorption Heat Pump Plant: An Energy and Economic Analysis
Appl. Sci. 2019, 9(5), 1007; https://doi.org/10.3390/app9051007
Received: 14 February 2019 / Revised: 5 March 2019 / Accepted: 6 March 2019 / Published: 11 March 2019
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Abstract
The use of phase change materials (PCM) can be considered an effective way to improve the energy storage capabilities of hybrid water thermal energy storage (TESs) in solar heating and cooling plants. However, due to a few shortcomings, their use is still limited. [...] Read more.
The use of phase change materials (PCM) can be considered an effective way to improve the energy storage capabilities of hybrid water thermal energy storage (TESs) in solar heating and cooling plants. However, due to a few shortcomings, their use is still limited. This paper aims to give a direct estimation of the considerable advantages achievable by means of these hybrid TESs by simulating the annual performance of an existing gymnasium building located in northern Italy. The solar heating/cooling and ground source absorption heat pump plant is simulated using Trnsys. A validated type allows for the simulation of the hybrid water TESs, and also includes the possibility to use aluminum foams to enhance the heat transfer capabilities of the paraffin waxes used as PCM. This paper presents an optimization of the plant design from both energy and economic points of view by considering different cases: all three tanks modeled as sensible (water) storage, or one of the tanks modeled as PCM storage, or as enhanced PCM with metal foam. Full article
(This article belongs to the Special Issue Advanced Applications of Phase Change Materials)
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