Applied Sciences

13 pages, 3436 KiB

Open AccessArticle

Mono- and Bi-Molecular Adsorption of SF₆ Decomposition Products on Pt Doped Graphene: A First-Principles Investigation

by Yongqian Wu, Shaojian Song, Dachang Chen and Xiaoxing Zhang

Appl. Sci. 2018, 8(10), 2010; https://doi.org/10.3390/app8102010 - 22 Oct 2018

Cited by 5 | Viewed by 3610

Based on the first-principles of density functional theory, the SF₆ decomposition products including single molecule (SO₂F₂, SOF₂, SO₂), double homogenous molecules (2SO₂F₂, 2SOF₂, 2SO₂) and double [...] Read more.

Based on the first-principles of density functional theory, the SF₆ decomposition products including single molecule (SO₂F₂, SOF₂, SO₂), double homogenous molecules (2SO₂F₂, 2SOF₂, 2SO₂) and double hetero molecules (SO₂ and SOF₂, SO₂ and SO₂F₂, SOF₂ and SO₂F₂) adsorbed on Pt doped graphene were discussed. The adsorption parameters, electron transfer, electronic properties and energy gap was investigated. The adsorption of SO₂, SOF₂ and SO₂F₂ on the surface of Pt-doped graphene was a strong chemisorption process. The intensity of chemical interactions between the molecule and the Pt-graphene for the above three molecules was SO₂F₂ > SOF₂ > SO₂. The change of energy gap was also studied and according to the value of energy gap, the conductivity of Pt-graphene before and after adsorbing different gas molecules can be evaluated. Full article

(This article belongs to the Section Nanotechnology and Applied Nanosciences)

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10 pages, 4721 KiB

Open AccessArticle

Measurement of Super-Pressure Balloon Deformation with Simplified Digital Image Correlation

by Kazuki Koseki, Takuma Matsuo and Shuichi Arikawa

Appl. Sci. 2018, 8(10), 2009; https://doi.org/10.3390/app8102009 - 22 Oct 2018

Cited by 8 | Viewed by 4280

Abstract

A super pressure balloon (SPB) is an aerostatic balloon that can fly at a constant altitude for an extended period. Japan Aerospace Exploration Agency (JAXA) has been developing a light-weight, high strength balloon made of thin polyethylene films and diamond-shaped net with high [...] Read more.

A super pressure balloon (SPB) is an aerostatic balloon that can fly at a constant altitude for an extended period. Japan Aerospace Exploration Agency (JAXA) has been developing a light-weight, high strength balloon made of thin polyethylene films and diamond-shaped net with high tensile fibers. Previous investigations proved that strength requirements on SPB members are satisfied even though the net covering the SPB sometimes becomes damaged during the inflation test. This may be due to non-uniform expansion, which causes stress concentration, however, no method exists to confirm this hypothesis. In this study, we tested a new method called Simplified Digital Image Correlation method (SiDIC) to check if it can measure the displacement of the SPB by using a rubber balloon. After measuring the measurement accuracy of the Digital Image Correlation method (DIC) and SiDIC, we applied both DIC and SiDIC to a rubber balloon covered just with the net. Interestingly, SiDIC entailed a smaller amount of data but could measure the deformation more accurately than DIC. In addition, assuming the stress concentration, one part of the net was bonded to the balloon to restrict the deformation. SiDIC properly identified the undeformed region. Full article

(This article belongs to the Special Issue Advances in Digital Image Correlation (DIC))

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26 pages, 1052 KiB

Open AccessArticle

Business Process Configuration According to Data Dependency Specification

by Luisa Parody, María Teresa Gómez-López, Angel Jesús Varela-Vaca and Rafael M. Gasca

Appl. Sci. 2018, 8(10), 2008; https://doi.org/10.3390/app8102008 - 22 Oct 2018

Cited by 4 | Viewed by 3850

Abstract

Configuration techniques have been used in several fields, such as the design of business process models. Sometimes these models depend on the data dependencies, being easier to describe what has to be done instead of how. Configuration models enable to use a [...] Read more.

Configuration techniques have been used in several fields, such as the design of business process models. Sometimes these models depend on the data dependencies, being easier to describe what has to be done instead of how. Configuration models enable to use a declarative representation of business processes, deciding the most appropriate work-flow in each case. Unfortunately, data dependencies among the activities and how they can affect the correct execution of the process, has been overlooked in the declarative specifications and configurable systems found in the literature. In order to find the best process configuration for optimizing the execution time of processes according to data dependencies, we propose the use of Constraint Programming paradigm with the aim of obtaining an adaptable imperative model in function of the data dependencies of the activities described declarative. Full article

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11 pages, 3324 KiB

Open AccessArticle

Effects of Individual and Environmental Factors on GPS-Based Time Allocation in Urban Microenvironments Using GIS

by Audrius Dėdelė, Auksė Miškinytė, Irma Česnakaitė and Regina Gražulevičienė

Appl. Sci. 2018, 8(10), 2007; https://doi.org/10.3390/app8102007 - 22 Oct 2018

Cited by 4 | Viewed by 3350

Abstract

Time-activity patterns are an essential part of personal exposure assessment to various environmental factors. People move through different environments during the day and they have different daily activity patterns which are significantly influenced by individual characteristics and the residential environment. In this study, [...] Read more.

Time-activity patterns are an essential part of personal exposure assessment to various environmental factors. People move through different environments during the day and they have different daily activity patterns which are significantly influenced by individual characteristics and the residential environment. In this study, time spent in different microenvironments (MEs) were assessed for 125 participants for 7 consecutive days to evaluate the impact of individual characteristics on time-activity patterns in Kaunas, Lithuania. The data were collected with personal questionnaires and diaries. The global positioning system (GPS) sensor integrated into a smartphone was used to track daily movements and to assess time-activity patterns. The study results showed that behavioral and residential greenness have a statistically significant impact on time spent indoors. These results underline the high influence of the individual characteristics and environmental factors on time spent indoors, which is an important determinant for exposure assessment and health impact assessment studies. Full article

(This article belongs to the Section Environmental Sciences)

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13 pages, 4479 KiB

Open AccessArticle

Sparse Haar-Like Feature and Image Similarity-Based Detection Algorithm for Circular Hole of Engine Cylinder Head

by Wenzhang Zhou, Yong Chen and Siyuan Liang

Appl. Sci. 2018, 8(10), 2006; https://doi.org/10.3390/app8102006 - 22 Oct 2018

Cited by 3 | Viewed by 4355

Abstract

If the circular holes of an engine cylinder head are distorted, cracked, defective, etc., the normal running of the equipment will be affected. For detecting these faults with high accuracy, this paper proposes a detection method based on feature point matching, which can [...] Read more.

If the circular holes of an engine cylinder head are distorted, cracked, defective, etc., the normal running of the equipment will be affected. For detecting these faults with high accuracy, this paper proposes a detection method based on feature point matching, which can reduce the detection error caused by distortion and light interference. First, the effective and robust feature vectors of pixels are extracted based on improved sparse Haar-like features. Then we calculate the similarity and find the most similar matching point from the image. In order to improve the robustness to the illumination, this paper uses the method based on image similarity to map the original image, so that the same region under different illumination conditions has similar spatial distribution. The experiments show that the algorithm not only has high matching accuracy, but also has good robustness to the illumination. Full article

(This article belongs to the Special Issue Fault Detection and Diagnosis in Mechatronics Systems)

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33 pages, 18846 KiB

Open AccessArticle

Real-Time Whole-Body Imitation by Humanoid Robots and Task-Oriented Teleoperation Using an Analytical Mapping Method and Quantitative Evaluation

by Zhijun Zhang, Yaru Niu, Ziyi Yan and Shuyang Lin

Appl. Sci. 2018, 8(10), 2005; https://doi.org/10.3390/app8102005 - 22 Oct 2018

Cited by 25 | Viewed by 8299

Abstract

Due to the limitations on the capabilities of current robots regarding task learning and performance, imitation is an efficient social learning approach that endows a robot with the ability to transmit and reproduce human postures, actions, behaviors, etc., as a human does. Stable [...] Read more.

Due to the limitations on the capabilities of current robots regarding task learning and performance, imitation is an efficient social learning approach that endows a robot with the ability to transmit and reproduce human postures, actions, behaviors, etc., as a human does. Stable whole-body imitation and task-oriented teleoperation via imitation are challenging issues. In this paper, a novel comprehensive and unrestricted real-time whole-body imitation system for humanoid robots is designed and developed. To map human motions to a robot, an analytical method called geometrical analysis based on link vectors and virtual joints (GA-LVVJ) is proposed. In addition, a real-time locomotion method is employed to realize a natural mode of operation. To achieve safe mode switching, a filter strategy is proposed. Then, two quantitative vector-set-based methods of similarity evaluation focusing on the whole body and local links, called the Whole-Body-Focused (WBF) method and the Local-Link-Focused (LLF) method, respectively, are proposed and compared. Two experiments conducted to verify the effectiveness of the proposed methods and system are reported. Specifically, the first experiment validates the good stability and similarity features of our system, and the second experiment verifies the effectiveness with which complicated tasks can be executed. At last, an imitation learning mechanism in which the joint angles of demonstrators are mapped by GA-LVVJ is presented and developed to extend the proposed system. Full article

(This article belongs to the Special Issue Human Friendly Robotics)

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19 pages, 7166 KiB

Open AccessArticle

Condition Monitoring of Wind Turbine Blades Using Active and Passive Thermography

by Hadi Sanati, David Wood and Qiao Sun

Appl. Sci. 2018, 8(10), 2004; https://doi.org/10.3390/app8102004 - 22 Oct 2018

Cited by 48 | Viewed by 6037

Abstract

The failure of wind turbine blades is a major concern in the wind power industry due to the resulting high cost. It is, therefore, crucial to develop methods to monitor the integrity of wind turbine blades. Different methods are available to detect subsurface [...] Read more.

The failure of wind turbine blades is a major concern in the wind power industry due to the resulting high cost. It is, therefore, crucial to develop methods to monitor the integrity of wind turbine blades. Different methods are available to detect subsurface damage but most require close proximity between the sensor and the blade. Thermography, as a non-contact method, may avoid this problem. Both passive and active pulsed and step heating and cooling thermography techniques were investigated for different purposes. A section of a severely damaged blade and a small “plate” cut from the undamaged laminate section of the blade with holes of varying diameter and depth drilled from the rear to provide “known” defects were monitored. The raw thermal images captured by both active and passive thermography demonstrated that image processing was required to improve the quality of the thermal data. Different image processing algorithms were used to increase the thermal contrasts of subsurface defects in thermal images obtained by active thermography. A method called “Step Phase and Amplitude Thermography”, which applies a transform-based algorithm to step heating and cooling data was used. This method was also applied, for the first time, to the passive thermography results. The outcomes of the image processing on both active and passive thermography indicated that the techniques employed could considerably increase the quality of the images and the visibility of internal defects. The signal-to-noise ratio of raw and processed images was calculated to quantitatively show that image processing methods considerably improve the ratios. Full article

(This article belongs to the Special Issue Wind Turbine Aerodynamics)

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17 pages, 2849 KiB

Open AccessArticle

No-Reference Blurred Image Quality Assessment by Structural Similarity Index

by Haopeng Zhang, Bo Yuan, Bo Dong and Zhiguo Jiang

Appl. Sci. 2018, 8(10), 2003; https://doi.org/10.3390/app8102003 - 22 Oct 2018

Cited by 30 | Viewed by 5353

Abstract

No-reference (NR) image quality assessment (IQA) objectively measures the image quality consistently with subjective evaluations by using only the distorted image. In this paper, we focus on the problem of NR IQA for blurred images and propose a new no-reference structural similarity (NSSIM) [...] Read more.

No-reference (NR) image quality assessment (IQA) objectively measures the image quality consistently with subjective evaluations by using only the distorted image. In this paper, we focus on the problem of NR IQA for blurred images and propose a new no-reference structural similarity (NSSIM) metric based on re-blur theory and structural similarity index (SSIM). We extract blurriness features and define image blurriness by grayscale distribution. NSSIM scores an image quality by calculating image luminance, contrast, structure and blurriness. The proposed NSSIM metric can evaluate image quality immediately without prior training or learning. Experimental results on four popular datasets show that the proposed metric outperforms SSIM and well-matched to state-of-the-art NR IQA models. Furthermore, we apply NSSIM with known IQA approaches to blurred image restoration and demonstrate that NSSIM is statistically superior to peak signal-to-noise ratio (PSNR), SSIM and consistent with the state-of-the-art NR IQA models. Full article

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23 pages, 1039 KiB

Open AccessArticle

Side-Channel Vulnerabilities of Unified Point Addition on Binary Huff Curve and Its Countermeasure

by Sung Min Cho, Sunghyun Jin and HeeSeok Kim

Appl. Sci. 2018, 8(10), 2002; https://doi.org/10.3390/app8102002 - 22 Oct 2018

Cited by 6 | Viewed by 3153

Abstract

Unified point addition for computing elliptic curve point addition and doubling is considered to be resistant to simple power analysis. Recently, new side-channel attacks, such as recovery of secret exponent by triangular trace analysis and horizontal collision correlation analysis, have been successfully applied [...] Read more.

Unified point addition for computing elliptic curve point addition and doubling is considered to be resistant to simple power analysis. Recently, new side-channel attacks, such as recovery of secret exponent by triangular trace analysis and horizontal collision correlation analysis, have been successfully applied to elliptic curve methods to investigate their resistance to side-channel attacks. These attacks turn out to be very powerful since they only require leakage of a single power consumption trace. In this paper, using these side-channel attack analyses, we introduce two vulnerabilities of unified point addition on the binary Huff curve. Also, we propose a new unified point addition method for the binary Huff curve. Furthermore, to secure against these vulnerabilities, we apply an equivalence class to the side-channel atomic algorithm using the proposed unified point addition method. Full article

(This article belongs to the Special Issue Side Channel Attacks)

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The scheme of the experimental setup used for measuring power consumption. Full article ">Figure 2
A single power consumption trace of field multiplications for binary Huff curve software implementation on an ARM cortex-m4 processor. The power consumption trace is composed of subtraces corresponding to field multiplications. Full article ">Figure 3
Beginning of a field multiplication power consumption trace. Each w-bit multiplication subtrace in a field multiplication can be identified using simple power analysis (SPA) and cross-correlation. Full article ">Figure 4
Squared pairwise t-differences (SOST; line) and points of interest (POIs; red circle). (a) Points having higher SOST values than the heuristic threshold are chosen for HCCA’s POIs. (b) Unlike HCCA, ROSETTA’s POIs, upon which the output value of w-bit multiplication is processed, are chosen heuristically. Full article ">Figure 5
Results of the secret bit value guess by (a) HCCA and (b) ROSETTA. The blue line is the secret bit value guess and the horizontal red line is the threshold value for the secret bit value discrimination; points with a black circle indicate where the attack failed. Full article ">

9 pages, 976 KiB

Open AccessArticle

Quantification of the Transmission Properties of Anisotropic Metasurfaces Illuminated by Finite-Size Beams

by Mohamed Boutria, Abdoulaye Ndao and Fadi I. Baida

Appl. Sci. 2018, 8(10), 2001; https://doi.org/10.3390/app8102001 - 22 Oct 2018

Cited by 1 | Viewed by 2785

Abstract

The aim of this paper is to present an analytical method to quantitatively address the influence of a focusing illumination on the optical response properties of a metasurface illuminated by a finite-size beam. Most theoretical and numerical studies are performed by considering an [...] Read more.

The aim of this paper is to present an analytical method to quantitatively address the influence of a focusing illumination on the optical response properties of a metasurface illuminated by a finite-size beam. Most theoretical and numerical studies are performed by considering an infinite periodic structure illuminated by a plane wave. In practice, one deals with a finite-size illumination and structure. The combination of the angular spectrum expansion with a monomodal modal method is used to determine the beam size needed to acquire efficient properties of a metasurface that behaves as an anisotropic plate. Interesting results show that the beam-size can be as small as

5 \times 5

periods to recover the results of a plane wave. Other results also show that the beam-size can be used as an extrinsic parameter to enhance the anisotropic metasurface performance and to adjust its expected properties finely (birefringence and/or transmission coefficient). These findings are important for the design of real (finite) structures and can be adapted for experimental conditions to achieve optimized results and take full advantage of the metamaterial properties. Full article

(This article belongs to the Special Issue Sub-wavelength Optics)

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11 pages, 1892 KiB

Open AccessArticle

The Effect of Intermediate Principal Stress on Compressive Strength of Different Cement Content of Cement-Stabilized Macadam and Different Gradation of AC-13 Mixture

by Hong-xin Guan, Hao-qing Wang, Hao Liu, Jia-jun Yan and Miao Lin

Appl. Sci. 2018, 8(10), 2000; https://doi.org/10.3390/app8102000 - 22 Oct 2018

Cited by 12 | Viewed by 3290

Abstract

Since the effect of intermediate principal stress on the strength of pavement materials is not entirely clear so far, a proprietary true triaxial apparatus was developed to simulate the spatial status of principal stresses to conduct compressive strength tests on different gradations of [...] Read more.

Since the effect of intermediate principal stress on the strength of pavement materials is not entirely clear so far, a proprietary true triaxial apparatus was developed to simulate the spatial status of principal stresses to conduct compressive strength tests on different gradations of AC-13, different cement contents of cement-stabilized macadam. With the same minimum principal stress, the triaxial compressive strengths of cube specimens under different intermediate principal stresses were compared. The results indicate that, as the intermediate principal stress increases, the compressive strength of the specimen increases and then decreases; different gradations of AC-13 do not show much difference in triaxial compressive strength while different cement contents of cement-stabilized macadam indicate considerable difference. Analysis results suggest significant effect of intermediate principal stress on the compressive strength of pavement materials: for AC-13, the coarser the gradation, the greater the effect of intermediate principal strength on its strength; for cement-stabilized Macadam, the higher the cement content, the greater the effect of intermediate principal stress. Strength model analysis results suggest that Double-Shear-Corner Model is more suitable to characterize cement-stabilized macadam’s strength performance compared to the Mohr–Coulomb model and Double-Shear Model. Full article

(This article belongs to the Special Issue Achievements and Prospects of Functional Pavement: Materials and Structures)

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12 pages, 1976 KiB

Open AccessArticle

Effects of Silk-Worm Excrement Biochar Combined with Different Iron-Based Materials on the Speciation of Cadmium and Lead in Soil

by Pengyang Bian, Jingjing Zhang, Chaolan Zhang, He Huang, Qun Rong, Haixia Wu, Xue Li, Mengmeng Xu, Yu Liu and Siwei Ren

Appl. Sci. 2018, 8(10), 1999; https://doi.org/10.3390/app8101999 - 22 Oct 2018

Cited by 11 | Viewed by 4088

Abstract

A 56d incubation experiment was conducted to explore the effects of the silk-worm excrement biochar (500 °C, BC) combined with different iron-based materials (FeCl₃, FeSO_4, and reduced iron powder) on the speciation of cadmium (Cd) and lead (Pb) in a [...] Read more.

A 56d incubation experiment was conducted to explore the effects of the silk-worm excrement biochar (500 °C, BC) combined with different iron-based materials (FeCl₃, FeSO_4, and reduced iron powder) on the speciation of cadmium (Cd) and lead (Pb) in a contaminated soil. Application rate of BC and iron-based materials is 1% (W/W) and 0.2% (W/W) of the soil, respectively. At the same time, the soil physicochemical properties, such as pH, cation exchange capacity (CEC), and the structure of soil, were determined in order to explore the influence mechanism of amendments to forms of Cd and Pb in soil. The results show that the stabilization effects on Cd is (BC + FeSO₄) > (BC + FeCl₃) > (BC + Fe) > (BC) and Pb is (BC + Fe) > (BC + FeSO₄) > (BC + FeCl₃) > (BC) at the end of incubation, compared with the effect of the control group. The treatment of (BC + FeSO₄) is the most effective in terms of the stabilization of Cd and Pb, which makes the percentages of organic-bound and residual Cd and Pb increase by 40.90% and 23.51% respectively. In addition, with different ways of treatment, the pH value and CEC of soil see a remarkable increase by 1.65–2.01 units and 2.01–2.58 cmol·kg⁻¹ respectively. X-ray diffraction (XRD) patterns show that the soil imprisons Cd and Pb in different mineral phases. As such the treatment of (BC + FeSO₄) can significantly improve soil environment, increase soil pH value & CEC and exert a relatively good stabilization effect on both Cd and Pb. Full article

(This article belongs to the Special Issue Sustainable Environmental Remediation)

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7 pages, 241 KiB

Open AccessArticle

Self-Consistent Derivation of the Modified Gross–Pitaevskii Equation with Lee–Huang–Yang Correction

by Luca Salasnich

Appl. Sci. 2018, 8(10), 1998; https://doi.org/10.3390/app8101998 - 21 Oct 2018

Cited by 12 | Viewed by 3922

Abstract

We consider a dilute and ultracold bosonic gas of weakly-interacting atoms. Within the framework of quantum field theory, we derive a zero-temperature modified Gross–Pitaevskii equation with beyond-mean-field corrections due to quantum depletion and anomalous density. This result is obtained from the stationary equation [...] Read more.

We consider a dilute and ultracold bosonic gas of weakly-interacting atoms. Within the framework of quantum field theory, we derive a zero-temperature modified Gross–Pitaevskii equation with beyond-mean-field corrections due to quantum depletion and anomalous density. This result is obtained from the stationary equation of the Bose–Einstein order parameter coupled to the Bogoliubov–de Gennes equations of the out-of-condensate field operator. We show that, in the presence of a generic external trapping potential, the key steps to get the modified Gross–Pitaevskii equation are the semiclassical approximation for the Bogoliubov–de Gennes equations, a slowly-varying order parameter and a small quantum depletion. In the uniform case, from the modified Gross–Pitaevskii equation, we get the familiar equation of state with Lee–Huang–Yang correction. Full article

(This article belongs to the Special Issue Optical Properties of Confined Quantum Systems)

15 pages, 3460 KiB

Open AccessArticle

Residual Stress in Laser Welding of TC4 Titanium Alloy Based on Ultrasonic laser Technology

by Yu Zhan, Enda Zhang, Yiming Ge and Changsheng Liu

Appl. Sci. 2018, 8(10), 1997; https://doi.org/10.3390/app8101997 - 20 Oct 2018

Cited by 22 | Viewed by 4887

Abstract

Laser welding is widely used in titanium alloy welding due to its high energy density, small heat affected zone, and rapid processing ability. However, problems with laser welding, such as deformation and cracking caused by residual stress, need to be resolved. In this [...] Read more.

Laser welding is widely used in titanium alloy welding due to its high energy density, small heat affected zone, and rapid processing ability. However, problems with laser welding, such as deformation and cracking caused by residual stress, need to be resolved. In this paper, the residual stress in laser welding of TC4 titanium alloy was studied using an ultrasonic laser. The residual stress in titanium alloy plates is considered a plane stress state. A pre-stress loading method is proposed and acoustoelastic coefficients are obtained. Based on the known acoustoelastic coefficients, the transverse and longitudinal residual stresses in laser welding are measured using an ultrasonic laser. The results show that longitudinal residual stress is greater than the transverse stress. The distribution regularity of the residual stress is similar to normal welding, but the tensile stress zone is much narrower. Then, the influence of heat input and welding speed on residual stress is discussed. With increasing heat input, the welding zone widens, and the peak value of the residual stress increases. A higher welding speed should be chosen when the welding power is constant. This research has important significance for the measurement and control of residual stress in the laser welding process. Full article

(This article belongs to the Special Issue Laser Ultrasonics)

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24 pages, 2350 KiB

Open AccessReview

A Brief Review of Specialty Optical Fibers for Brillouin-Scattering-Based Distributed Sensors

by Peter Dragic and John Ballato

Appl. Sci. 2018, 8(10), 1996; https://doi.org/10.3390/app8101996 - 20 Oct 2018

Cited by 26 | Viewed by 5816

Abstract

Specialty optical fibers employed in Brillouin-based distributed sensors are briefly reviewed. The optical and acoustic waveguide properties of silicate glass optical fiber first are examined with the goal of constructing a designer Brillouin gain spectrum. Next, materials and their effects on the relevant [...] Read more.

Specialty optical fibers employed in Brillouin-based distributed sensors are briefly reviewed. The optical and acoustic waveguide properties of silicate glass optical fiber first are examined with the goal of constructing a designer Brillouin gain spectrum. Next, materials and their effects on the relevant Brillouin scattering properties are discussed. Finally, optical fiber configurations are reviewed, with attention paid to fibers for discriminative or other enhanced sensing configurations. The goal of this brief review is to reinforce the importance of fiber design to distributed sensor systems, generally, and to inspire new thinking in the use of fibers for this sensing application. Full article

(This article belongs to the Special Issue Optical Correlation-domain Distributed Fiber Sensors)

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Refractive index profile (RIP) for a conventional step-index optical fiber. Full article ">Figure 2
RIP and longitudinal acoustic velocity profile for the fiber of the example. Full article ">Figure 3
Simulated Brillouin gain spectrum (BGS) calculated (1534 nm) from the profiles in <a href="#applsci-08-01996-f002" class="html-fig">Figure 2</a>. The positions of the longitudinal mode interactions are also shown. The insets plot the LP01 optical mode intensity (red) and the acoustic displacement uz(r) (blue). Vertical dashed lines in the insets delineate the core region. Full article ">Figure 4
Simulated refractive index of binary germanosilicate as a function of the GeO2 concentration (in mol %) for a base density of 3650 km/m3 (blue curve). The effect of raising or lowering the density in the model affects the curvature of the functions. Full article ">Figure 5
gB for the binary phosphosilicate glass as a function of mol % of P2O5 relative to that of pure SiO2 in units of dB. An absolute minimum is observed in the plot. Even a few mol % of P2O5 can cause a significant drop in gB. Full article ">Figure 6
Brillouin spectral width simulation for pure silica at wavelengths of 633 nm and 1534 nm. Far from the peak, the spectral width is proportional to νB2. The spectral width is proportional to the acoustic attenuation coefficient. Full article ">Figure 7
Example of a BGS tailored to have two acoustic mode interactions of similar strength. The responses of the modes to changes in T or ε differ. This illustration may represent a typical fiber whose temperature or applied strain has been increased in going from the blue to the red curve. Full article ">Figure 8
Example acoustic and refractive index profiles for the equalization of Brillouin gain between the L01 and higher order acoustic modes. In this configuration, the optical and acoustic boundaries are decoupled [<a href="#B138-applsci-08-01996" class="html-bibr">138</a>]. Full article ">

31 pages, 14005 KiB

Open AccessArticle

An Image-Based Fall Detection System for the Elderly

by Kun-Lin Lu and Edward T.-H. Chu

Appl. Sci. 2018, 8(10), 1995; https://doi.org/10.3390/app8101995 - 20 Oct 2018

Cited by 30 | Viewed by 9415

Abstract

Due to advances in medical technology, the elderly population has continued to grow. Elderly healthcare issues have been widely discussed—especially fall accidents—because a fall can lead to a fracture and have serious consequences. Therefore, the effective detection of fall accidents is important for [...] Read more.

Due to advances in medical technology, the elderly population has continued to grow. Elderly healthcare issues have been widely discussed—especially fall accidents—because a fall can lead to a fracture and have serious consequences. Therefore, the effective detection of fall accidents is important for both elderly people and their caregivers. In this work, we designed an Image-based FAll Detection System (IFADS) for nursing homes, where public areas are usually equipped with surveillance cameras. Unlike existing fall detection algorithms, we mainly focused on falls that occur while sitting down and standing up from a chair, because the two activities together account for a higher proportion of falls than forward walking. IFADS first applies an object detection algorithm to identify people in a video frame. Then, a posture recognition method is used to keep tracking the status of the people by checking the relative positions of the chair and the people. An alarm is triggered when a fall is detected. In order to evaluate the effectiveness of IFADS, we not only simulated different fall scenarios, but also adopted YouTube and Giphy videos that captured real falls. Our experimental results showed that IFADS achieved an average accuracy of 95.96%. Therefore, IFADS can be used by nursing homes to improve the quality of residential care facilities. Full article

(This article belongs to the Special Issue Advanced Intelligent Imaging Technology)

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14 pages, 4406 KiB

Open AccessArticle

Co-Occurrence Network of High-Frequency Words in the Bioinformatics Literature: Structural Characteristics and Evolution

by Taoying Li, Jie Bai, Xue Yang, Qianyu Liu and Yan Chen

Appl. Sci. 2018, 8(10), 1994; https://doi.org/10.3390/app8101994 - 20 Oct 2018

Cited by 24 | Viewed by 7651

Abstract

The subjects of literature are the direct expression of the author’s research results. Mining valuable knowledge helps to save time for the readers to understand the content and direction of the literature quickly. Therefore, the co-occurrence network of high-frequency words in the bioinformatics [...] Read more.

The subjects of literature are the direct expression of the author’s research results. Mining valuable knowledge helps to save time for the readers to understand the content and direction of the literature quickly. Therefore, the co-occurrence network of high-frequency words in the bioinformatics literature and its structural characteristics and evolution were analysed in this paper. First, 242,891 articles from 47 top bioinformatics periodicals were chosen as the object of the study. Second, the co-occurrence relationship among high-frequency words of these articles was analysed by word segmentation and high-frequency word selection. Then, a co-occurrence network of high-frequency words in bioinformatics literature was built. Finally, the conclusions were drawn by analysing its structural characteristics and evolution. The results showed that the co-occurrence network of high-frequency words in the bioinformatics literature was a small-world network with scale-free distribution, rich-club phenomenon and disassortative matching characteristics. At the same time, the high-frequency words used by authors changed little in 2–3 years but varied greatly in four years because of the influence of the state-of-the-art technology. Full article

(This article belongs to the Special Issue Applied Sciences Based on and Related to Computer and Control)

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15 pages, 5388 KiB

Open AccessArticle

Characterization of Human Dermal Papilla Cells in Alginate Spheres

by Nanda Maya Mali, Yong-Hee Kim, Jung Min Park, Donghyun Kim, Wook Heo, Buu Le Dao, Jeong Ok Lim and Ji Won Oh

Appl. Sci. 2018, 8(10), 1993; https://doi.org/10.3390/app8101993 - 19 Oct 2018

Cited by 12 | Viewed by 7327

Abstract

Maintenance of trichogenecity of dermal papilla cells (DPCs) have been a problem during cell therapy for androgenic alopecia, as they lose their regenerative potential in in vitro culture. Various spheroid culture techniques are used to increase and maintain trichogenecity of these cells. However, [...] Read more.

Maintenance of trichogenecity of dermal papilla cells (DPCs) have been a problem during cell therapy for androgenic alopecia, as they lose their regenerative potential in in vitro culture. Various spheroid culture techniques are used to increase and maintain trichogenecity of these cells. However, there are some critical drawbacks in these methods. Applying a hydrocell plate for sphere formation or hanging drop methods by hand would be difficult to control the size and cell density inside it. It would be difficult to commercialize or mass production for clinical therapy. In aim to address and overcome these drawbacks, we have introduced alginate sphere. The alginate sphere of DPCs were prepared by electrospinning at different voltages to control the size of sphere. Then the obtained alginate spheres were evaluated for cellular dynamics and density of DPCs under different conditions. In this study, we found that DPCs do not proliferate in alginate sphere. However, the number of DPCs were maintained and found to be in dormant state. Further, the dormant DPCs in the alginate sphere have upregulated DPC signature genes (SOX2, ALPL, WIF1, Noggin, BMP4 and VCAN) and proliferative capacity. Thus, we speculate that alginate sphere environment maintains the dormancy of DPCs with increased trichogenecity. Full article

(This article belongs to the Special Issue Synthesis and Application of Microcapsules)

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Figure 1
The culture characteristics of human DPCs and alginate spheres. (A) Human hair follicle in vivo (red arrow showed dermal papilla in hair bulb region). (B,C) Isolated human dermal papillae in vivo. (D) Five days after cultivation of the human dermal papilla (red arrow-dermal papilla and blue arrow-explant cells from dermal papilla). (E) Passage 3 of human DPCs. (100 ×). (F) Conventional 2D culture state of human DPCs with CMDil. (G) Alginate sphere form of human DPCs with CMDil. (H) Cellular morphology after electrospinning. (I) The maximal size of the alginate spheres with human DPCs. (J) Tear drop shape of alginate with human DPCs. Scale bars in (A–G,J): 100 µm, (H,I) 500 µm. Full article ">Figure 2
Short-term and long-term cultivation of dermal papilla alginate spheres in different sizes. (A–D) Different sizes of alginate spheres with human DPCs. (A) Small size (100–200 µm). (B) Middle size (300–500 µm) (C) Moderate size (500–1000 µm) (D) Large size (more than 1500 µm). (E) Live cell number in different sizes of alginate spheres. (F) The number of total cells included live and dead cells in different size of alginate spheres. (G) The ratio of live cells to total cells in different sizes of alginate spheres. (H) The distribution of cell numbers in different sizes of alginate spheres. (I–K) Live cell number in small-size, middle size and moderate size respectively. (L) Normalized live cell number with the volume of the alginate spheres in different sizes of spheres. (Cell number/mm3). Note. *: p-value <0.05, **: p-value <0.01, compared to day 0 (control). Red color: Small size (100–200 µm), green color: Middle size (300–500 µm), Blue color: Moderate size (500–1000 µm). Scale bar: 100 µm. Full article ">Figure 3
Short-term and long-term cultivation of dermal papilla alginate spheres with different cellular densities. (A–D): Different densities of alginate spheres. (A) low density, (B) middle density, (C) moderate density and (D) high density of human DPCs in alginate spheres. (E) The live cell number per alginate sphere at different cellular densities. (F) The total cells included both the live cells and dead cells per alginate sphere at different cellular densities. (G) The ratio of live cells to total cells per alginate sphere at different cellular densities. (H–K): The live cell number with low density (H), middle density (I), moderate density (J), high density (K) of cells in a sphere (Cell number/mm3). Note. *: p-value <0.05, **: p-value <0.01. Compared to day 0 (control) as assessed by t-test. Scale bars: A–D: 100 µm. Full article ">Figure 4
Cultivation of explants and cellular convergence rate of dermal papilla alginate spheres. (A–C) Colony forming properties of alginate spheres with human DPCs. (D,E) CMDil trace of cell culture from alginate sphere explants of human DPCs: light microscopy (D) and fluorescent microscopy (E). The subpanel of (D) is tone-modulated to show the diluted cells originated from CMDil retaining cells. The normalized live cell number with the volume of alginate spheres at different cellular densities (F) and different sizes (H). (G) The normalized live cell number with the volume of alginate sphere of different cellular densities at day 70, day 80 and day 90. (I) The normalized live cell number with the volume of alginate spheres under every experimental condition. Full article ">Figure 5
The gene expression level of dermal papilla alginate spheres by qPCR. The human dermal papilla cell marker genes expressed in different passage state and alginate spheres, cultivate in different days. Note. P1, P3, P10: passage state 1, 3 and 10 respectively. D10, D50, D80: post-spherical formation day 10, 50 and 80 respectively. Full article ">Figure 6
The figure showed the human dermal papilla in vivo, in vitro culture (2D) and alginate spheres (3D) and their characteristics of stemness, dormancy and proliferation state. Full article ">

22 pages, 7352 KiB

Open AccessArticle

A Total Crop-Diagnosis Platform Based on Deep Learning Models in a Natural Nutrient Environment

by YiNa Jeong, SuRak Son, SangSik Lee and ByungKwan Lee

Appl. Sci. 2018, 8(10), 1992; https://doi.org/10.3390/app8101992 - 19 Oct 2018

Cited by 5 | Viewed by 3593

Abstract

This paper proposes a total crop-diagnosis platform (TCP) based on deep learning models in a natural nutrient environment, which collects the weather information based on a farm’s location information, diagnoses the collected weather information and the crop soil sensor data with a deep [...] Read more.

This paper proposes a total crop-diagnosis platform (TCP) based on deep learning models in a natural nutrient environment, which collects the weather information based on a farm’s location information, diagnoses the collected weather information and the crop soil sensor data with a deep learning technique, and notifies a farm manager of the diagnosed result. The proposed TCP is composed of 1 gateway and 2 modules as follows. First, the optimized farm sensor gateway (OFSG) collects data by internetworking sensor nodes which use Zigbee, Wi-Fi and Bluetooth protocol and reduces the number of sensor data fragmentation times through the compression of a fragment header. Second, the data storage module (DSM) stores the collected farm data and weather data in a farm central server. Third, the crop self-diagnosis module (CSM) works in the cloud server and diagnoses by deep learning whether or not the status of a farm is in good condition for growing crops according to current weather and soil information. The TCP performance shows that the data processing rate of the OFSG is increased by about 7% compared with existing sensor gateways. The learning time of the CSM is shorter than that of the long short-term memory models (LSTM) by 0.43 s, and the success rate of the CSM is higher than that of the LSTM by about 7%. Therefore, the TCP based on deep learning interconnects the communication protocols of various sensors, solves the maximum data size that sensor can transfer, predicts in advance crop disease occurrence in an external environment, and helps to make an optimized environment in which to grow crops. Full article

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15 pages, 1545 KiB

Open AccessArticle

Imaging Material Texture of As-Deposited Selective Laser Melted Parts Using Spatially Resolved Acoustic Spectroscopy

by Rikesh Patel, Matthias Hirsch, Paul Dryburgh, Don Pieris, Samuel Achamfuo-Yeboah, Richard Smith, Roger Light, Steve Sharples, Adam Clare and Matt Clark

Appl. Sci. 2018, 8(10), 1991; https://doi.org/10.3390/app8101991 - 19 Oct 2018

Cited by 34 | Viewed by 6052

Abstract

Additive manufacturing (AM) is a production technology where material is accumulated to create a structure, often through added shaped layers. The major advantage of additive manufacturing is in creating unique and complex parts for use in areas where conventional manufacturing reaches its limitations. [...] Read more.

Additive manufacturing (AM) is a production technology where material is accumulated to create a structure, often through added shaped layers. The major advantage of additive manufacturing is in creating unique and complex parts for use in areas where conventional manufacturing reaches its limitations. However, the current class of AM systems produce parts that contain structural defects (e.g., cracks and pores) which is not compatible with certification in high value industries. The probable complexity of an AM design increases the difficulty of using many non-destructive evaluation (NDE) techniques to inspect AM parts—however, a unique opportunity exists to interrogate a part during production using a rapid surface based technique. Spatially resolved acoustic spectroscopy (SRAS) is a laser ultrasound inspection technique used to image material microstructure of metals and alloys. SRAS generates and detects `controlled’ surface acoustic waves (SAWs) using lasers, which makes it a non-contact and non-destructive technique. The technique is also sensitive to surface and subsurface voids. Work until now has been on imaging the texture information of selective laser melted (SLM) parts once prepared (i.e., polished with

R_{a} < 0.1

μ

m)—the challenge for performing laser ultrasonics in-process is measuring waves on the rough surfaces present on as-deposited parts. This paper presents the results of a prototype SRAS system, developed using the rough surface ultrasound detector known as speckle knife edge detector (SKED)—texture images using this setup of an as-deposited Ti64 SLM sample, with a surface roughness of

S_{a} \approx 6

μ

m, were obtained. Full article

(This article belongs to the Special Issue Laser Ultrasonics)

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20 pages, 1272 KiB

Open AccessArticle

Practical Quantum Bit Commitment Protocol Based on Quantum Oblivious Transfer

by Yaqi Song and Li Yang

Appl. Sci. 2018, 8(10), 1990; https://doi.org/10.3390/app8101990 - 19 Oct 2018

Cited by 7 | Viewed by 3496

Abstract

Oblivious transfer (OT) and bit commitment (BC) are two-party cryptographic protocols which play crucial roles in the construction of various cryptographic protocols. We propose three practical quantum cryptographic protocols in this paper. We first construct a practical quantum random oblivious transfer (R-OT) protocol [...] Read more.

Oblivious transfer (OT) and bit commitment (BC) are two-party cryptographic protocols which play crucial roles in the construction of various cryptographic protocols. We propose three practical quantum cryptographic protocols in this paper. We first construct a practical quantum random oblivious transfer (R-OT) protocol based on the fact that non-orthogonal states cannot be reliably distinguished. Then, we construct a fault-tolerant one-out-of-two oblivious transfer (

O T_{1}^{2}

) protocol based on the quantum R-OT protocol. Afterwards, we propose a quantum bit commitment (QBC) protocol which executes the fault-tolerant

O T_{1}^{2}

several times. Mayers, Lo and Chau (MLC) no-go theorem proves that QBC protocol cannot be unconditionally secure. However, we find that computing the unitary transformation of no-go theorem attack needs so many resources that it is not realistically implementable. We give a definition of physical security for QBC protocols and prove that the practical QBC we proposed is physically secure and can be implemented in the real world. Full article

(This article belongs to the Special Issue Optical High-speed Information Technology)

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The error rate of Protocol 2 changing with the size of sets. Full article ">Figure 2
The probability that an honest Bob gets conclusive bit changing with <math display="inline"><semantics> <mi>μ</mi> </semantics></math>. Full article ">Figure 3
The probability that a malicious Bob gets a conclusive bit changing with <math display="inline"><semantics> <mi>μ</mi> </semantics></math>. Full article ">Figure 4
The difference between an honest Bob’s probability of obtaining a conclusive bit and half of a malicious Bob’s probability of obtaining a conclusive bit changing with <math display="inline"><semantics> <mi>μ</mi> </semantics></math>. Full article ">Figure 5
The solid line denotes the probability of an honest Bob obtains i conclusive bits when <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>800</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>μ</mi> <mo>=</mo> <mn>5</mn> </mrow> </semantics></math>. It can be seen that an honest Bob can obtain more than 259 conclusive bits with a great probability. The dashed line denotes the probability of a malicious Bob obtains <math display="inline"><semantics> <mrow> <mi>i</mi> <mo>+</mo> <mn>259</mn> </mrow> </semantics></math> conclusive bits. Full article ">

20 pages, 6345 KiB

Open AccessArticle

Viscosity and Waterproofing Performance Evaluation of Synthetic Polymerized Rubber Gel (SPRG) after Screw Mixing

by Dong Soo Ahn, Kyu Hwan Oh, Jin Sang Park and Sang Keun Oh

Appl. Sci. 2018, 8(10), 1989; https://doi.org/10.3390/app8101989 - 19 Oct 2018

Cited by 7 | Viewed by 4241

Abstract

As opposed to asphalt emulsion waterproofing membrane, Synthetic Rubber Polymer Gel (SPRG) waterproofing materials are not heated prior to installation in concrete structures. SPRG materials are typically required to undergo a screw-mixing process to temporarily reduce the high viscosity and facilitate membrane installation [...] Read more.

As opposed to asphalt emulsion waterproofing membrane, Synthetic Rubber Polymer Gel (SPRG) waterproofing materials are not heated prior to installation in concrete structures. SPRG materials are typically required to undergo a screw-mixing process to temporarily reduce the high viscosity and facilitate membrane installation on a concrete surface. However, there is no standard regulation on the duration of screw-mixing time during SPRG construction. Reported construction cases indicate that SPRG are left under constant screw mixing and are reused after hours or days of rest without being replaced with fresh products. When installed in this condition, SPRGs are subject to waterproofing performance degradation. In this study, SPRG viscosity properties are measured after five different screw-mixing procedures (no screw mixing, 10, 20, 30 and 60 min) and are set to rest in storage (2 h, 1, 2, 3, and 7 days). Specimens prepared under the respective screw mixing and storage times are evaluated for their changes in waterproofing properties through a series of ISO TS 16774 standard evaluation methods. A correlative comparison of the property evaluation results is presented to provide the changes to SPRG property and waterproofing performance. These results are then used to propose a general guideline for selecting optimal screw-mixing time with respect to maintaining adequate waterproofing performance and the viscosity recovery property of SPRG. Full article

(This article belongs to the Section Materials Science and Engineering)

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20 pages, 7511 KiB

Open AccessArticle

Investigation on Coal Fragmentation by High-Velocity Water Jet in Drilling: Size Distributions and Fractal Characteristics

by Songqiang Xiao, Zhaolong Ge, Yiyu Lu, Zhe Zhou, Qian Li and Lei Wang

Appl. Sci. 2018, 8(10), 1988; https://doi.org/10.3390/app8101988 - 19 Oct 2018

Cited by 23 | Viewed by 3985

Abstract

Water jet drilling (WJD) technology is a highly efficient method to extract coalbed methane from reservoirs with low permeability. It is crucial to efficiently remove the coal fragments while drilling. In this study, to disclose coal fragmentation features and size distributions under water [...] Read more.

Water jet drilling (WJD) technology is a highly efficient method to extract coalbed methane from reservoirs with low permeability. It is crucial to efficiently remove the coal fragments while drilling. In this study, to disclose coal fragmentation features and size distributions under water jet impact in drilling, the image processing method was utilized to obtain the geometric dimensions of coal fragments. The size distributions, morphologies and fractal characteristics of coal fragmentation were studied based on generalized extreme value distribution and fractal theory. The effects of the jet impact velocity and coal strength on the fragmentation features were analyzed. The results show that fine particles dominate the coal fragments in WJD for coal seams with various strengths. In experiments conducted at the Fengchun coal mine, owing to the higher coal strength of the M7 coal seam, the fragmentation degree of coal subjected to water jets during WJD is lower in the M7 coal steam than in the M8 coal seam, which results in a large dominant fragment size and small fractal dimension under the same impact energy. It was found that the higher the jet impact velocity is, the higher the quantity of fragments generated from WJD and the smaller the particle size. The NUM-based cumulative probability distribution curves of coal fragments are more intensive in the range of relatively small particle sizes and then become sparser with the increase in particle size. When the impact velocity increases, (i) the size distribution curves move toward smaller particle sizes, and the dominant fragment size decreases; (ii) the shape (major axis/minor axis) of coal fragments move toward the upper left, and the curve shape for a high impact velocity attains unity more quickly; and (iii) the fractal dimension value increases linearly. In addition, the fractal dimensions are obviously affected by the dominant fragment size; they increase with the decrease in the dominant fragment size. This study can provide a basis for further research on coal fragment transportation in WJD and parameter selection for discharging coal fragments during drilling for CBM development. Full article

(This article belongs to the Special Issue Green Energy and Applications)

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18 pages, 3410 KiB

Open AccessArticle

Evaluation of a Smart System for the Optimization of Logistics Performance of a Pruning Biomass Value Chain

by Techane Bosona, Girma Gebresenbet, Sven-Olof Olsson, Daniel Garcia and Sonja Germer

Appl. Sci. 2018, 8(10), 1987; https://doi.org/10.3390/app8101987 - 19 Oct 2018

Cited by 5 | Viewed by 4371

Abstract

The paper presents a report on the performance evaluation of a newly developed smart logistics system (SLS). Field tests were conducted in Spain, Germany, and Sweden. The evaluation focused on the performance of a smart box tool (used to capture information during biomass [...] Read more.

The paper presents a report on the performance evaluation of a newly developed smart logistics system (SLS). Field tests were conducted in Spain, Germany, and Sweden. The evaluation focused on the performance of a smart box tool (used to capture information during biomass transport) and a web-based information platform (used to monitor the flow of agricultural pruning from farms to end users and associated information flow). The tests were performed following a product usability testing approach, considering both qualitative and quantitative parameters. The detailed performance evaluation included the following: systematic analysis of 41 recordable parameters (stored in a spreadsheet database), analysis of feedback and problems encountered during the tests, and overall quality analysis applying the product quality model adapted from ISO/IEC FDIS 9126-1 standard. The data recording and storage and the capability to support product traceability and supply chain management were found to be very satisfactory, while assembly of smart box components (mainly the associated cables), data transferring intervals, and manageability could be improved. From the data retrieved during test activities, in more than 95% of the parameters within 41 columns, the expected values were displayed correctly. Some errors were observed, which might have been caused mainly by barriers that could hinder proper data recording and transfer from the smart box to the central database. These problems can be counteracted and the performance of the SLS can be improved so that it can be upgraded to be a marketable tool that can promote sustainable biomass-to-energy value chains. Full article

(This article belongs to the Special Issue Sustainable Energy Systems Planning, Integration and Management)

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19 pages, 5168 KiB

Open AccessArticle

Detectability of Delamination in Concrete Structure Using Active Infrared Thermography in Terms of Signal-to-Noise Ratio

by Jungwon Huh, Van Ha Mac, Quang Huy Tran, Ki-Yeol Lee, Jong-In Lee and Choonghyun Kang

Appl. Sci. 2018, 8(10), 1986; https://doi.org/10.3390/app8101986 - 19 Oct 2018

Cited by 22 | Viewed by 6856

Abstract

Detecting subsurface delamination is a difficult and vital task to maintain the durability and serviceability of concrete structure for its whole life cycle. The aim of this work was to obtain better knowledge of the effect of depth, heating time, and rebar on [...] Read more.

Detecting subsurface delamination is a difficult and vital task to maintain the durability and serviceability of concrete structure for its whole life cycle. The aim of this work was to obtain better knowledge of the effect of depth, heating time, and rebar on the detectability capacity of delamination. Experimental tests were carried out on a concrete specimen in the laboratory using Long Pulsed Thermography (LPT). Six halogen lamps and a long wavelength infrared camera with a focal plane array of 640 × 480 pixels were used as the heat source and infrared detector, respectively. The study focused on the embedded imitation delaminations with the size of 10 cm × 10 cm × 1 cm, located at depths varying from 1 to 8 cm. The signal-to-noise ratio (SNR) was applied as a criterion to assess the detectability of delamination. The results of this study indicate that as the provided heating time climbed, the SNR increased, and the defect could be identified more clearly. On the other hand, when using the same heating regime, a shallow delamination displayed a higher SNR than a deeper one. The moderate fall of the SNR in the case of imitating defect located below reinforced steel was also observed. The absolute contrast was monitored to determine the observation time, and the nondimensional prefactor k was empirically proposed to predict the depth of delamination. The mean absolute percentage error (MAPE) was used to quantitatively evaluate the difference between forecasted and real depth, which evaluation confirmed the high reliability of the estimated value of the prefactor k. Full article

(This article belongs to the Special Issue Nondestructive Testing and Imaging Based on Electromagnetic Fields and Waves)

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26 pages, 7619 KiB

Open AccessArticle

Effective Implementation of Edge-Preserving Filtering on CPU Microarchitectures

by Yoshihiro Maeda, Norishige Fukushima and Hiroshi Matsuo

Appl. Sci. 2018, 8(10), 1985; https://doi.org/10.3390/app8101985 - 19 Oct 2018

Cited by 20 | Viewed by 6135

Abstract

In this paper, we propose acceleration methods for edge-preserving filtering. The filters natively include denormalized numbers, which are defined in IEEE Standard 754. The processing of the denormalized numbers has a higher computational cost than normal numbers; thus, the computational performance of edge-preserving [...] Read more.

In this paper, we propose acceleration methods for edge-preserving filtering. The filters natively include denormalized numbers, which are defined in IEEE Standard 754. The processing of the denormalized numbers has a higher computational cost than normal numbers; thus, the computational performance of edge-preserving filtering is severely diminished. We propose approaches to prevent the occurrence of the denormalized numbers for acceleration. Moreover, we verify an effective vectorization of the edge-preserving filtering based on changes in microarchitectures of central processing units by carefully treating kernel weights. The experimental results show that the proposed methods are up to five-times faster than the straightforward implementation of bilateral filtering and non-local means filtering, while the filters maintain the high accuracy. In addition, we showed effective vectorization for each central processing unit microarchitecture. The implementation of the bilateral filter is up to 14-times faster than that of OpenCV. The proposed methods and the vectorization are practical for real-time tasks such as image editing. Full article

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10 pages, 4454 KiB

Open AccessArticle

Thermoresponsive Behavior of Magnetic Nanoparticle Complexed pNIPAm-co-AAc Microgels

by Su-Kyoung Lee, Yongdoo Park and Jongseong Kim

Appl. Sci. 2018, 8(10), 1984; https://doi.org/10.3390/app8101984 - 19 Oct 2018

Cited by 9 | Viewed by 6106

Abstract

Characterization of responsive hydrogels and their enhancement with novel moieties have improved our understanding of functional materials. Hydrogels coupled with inorganic nanoparticles have been sought for novel types of responsive materials, but the efficient routes for the formation and the responsivity of complexed [...] Read more.

Characterization of responsive hydrogels and their enhancement with novel moieties have improved our understanding of functional materials. Hydrogels coupled with inorganic nanoparticles have been sought for novel types of responsive materials, but the efficient routes for the formation and the responsivity of complexed materials remain for further investigation. Here, we report that responsive poly(N-isopropylacrylamide-co-acrylic acid) (pNIPAm-co-AAc) hydrogel microparticles (microgels) are tunable by varying composition of co-monomer and crosslinker as well as by their complexation with magnetic nanoparticles in aqueous dispersions. Our results show that the hydrodynamic diameter and thermoresponsivity of microgels are closely related with the composition of anionic co-monomer, AAc and crosslinker, N,N′-Methylenebisacrylamide (BIS). As a composition of hydrogels, the higher AAc increases the swelling size of the microgels and the volume phase transition temperature (VPTT), but the higher BIS decreases the size with no apparent effect on the VPTT. When the anionic microgels are complexed with amine-modified magnetic nanoparticles (aMNP) via electrostatic interaction, the microgels decrease in diameter at 25 °C and shift the volume phase transition temperature (VPTT) to a higher temperature. Hysteresis on the thermoresponsive behavior of microgels is also measured to validate the utility of aMNP-microgel complexation. These results suggest a simple, yet valuable route for development of advanced responsive microgels, which hints at the formation of soft nanomaterials enhanced by inorganic nanoparticles. Full article

(This article belongs to the Special Issue Nanocomposite Hydrogels for Biomedical Applications)

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Graphical abstract
Full article ">Figure 1
TEM image of Zn0.4Fe2.6O4 nanoparticles (left panel) and silica coated Zn0.4Fe2.6O4 nanoparticles (right panel). The average sizes of the nanoparticles are 13 nm ± 1.1 nm and 21 nm ± 1.5 nm, respectively. Full article ">Figure 2
pNIPAm-co-AAc microgel (a) and its thermoresponsive behavior (b). Amine-functionalized magnetic nanoparticle (aMNP) enhanced microgel via electrostatic coupling (c) and its temperature dependent volume change (d). Full article ">Figure 3
TEM images of aMNP complexed pNIPAm-co-AAc microgel. Low magnification (left) and high magnification (right). Note that dark circles represent aMNP incorporated to microgels. Full article ">Figure 4
The zeta potential value and the hydrodynamic size for 10% AAc (acrylic acid), 2% BIS (N,N′-Methylenebisacrylamide) microgels upon 0.6, 1.2, 1.8, and 2.4 μg of aMNP additions. Note that zeta potential values of aMNP and microgels were measured as 19 mV and −18 mV, respectively. Full article ">Figure 5
Hydrodynamic diameter of 5% (□), 10% (○), and 20% (△) AAc (a) or 0% (□), 2% (○), and 5% (△) BIS microgels (b) upon the addition of 0.6 μg of aMNP aliquots. The hydrodynamic diameter of microgels measured by dynamic light scattering (DLS) at 25 °C. Full article ">Figure 6
The hydrodynamic diameter (nm) of 5% (□), 10% (○), and 20% (△) AAc microgels without (a) and with (b) aMNP complexation and 0% (□), 2% (○), and 5% (△) BIS microgels without (c) and with (d) aMNP complexation at 25 °C and 50 °C in cooling and heating cycles, respectively. Note that each measurement was performed after 15 min of equilibration time at the cycles. Full article ">Figure 7
The hydrodynamic diameter (nm) of 5% (□), 10% (○), and 20% (△) AAc microgels without (a) and with (b) aMNP complexation and 0% (□), 2% (○), and 5% (△) BIS microgels without (c) and with (d) aMNP complexation in temperature ramp from 25 to 55 °C at one degree intervals. Full article ">

16 pages, 2406 KiB

Open AccessFeature PaperArticle

Modeling Power Generation and Energy Efficiencies in Air-Cathode Microbial Fuel Cells Based on Freter Equations

by Hongjian Lin, Sarah (Xiao) Wu and Jun Zhu

Appl. Sci. 2018, 8(10), 1983; https://doi.org/10.3390/app8101983 - 19 Oct 2018

Cited by 13 | Viewed by 3497

Abstract

The model proposed in this study was based on the assumption that the biomass attached to the anode served as biocatalysts for microbial fuel cell (MFC) exoelectrogenesis, and this catalytic effect was quantified by the exchange current density of anode. By modifying the [...] Read more.

The model proposed in this study was based on the assumption that the biomass attached to the anode served as biocatalysts for microbial fuel cell (MFC) exoelectrogenesis, and this catalytic effect was quantified by the exchange current density of anode. By modifying the Freter model and combining it with the Butler–Volmer equation, this model could adequately describe the processes of electricity generation, substrate utilization, and the suspended and attached biomass concentrations, at both batch and continuous operating modes. MFC performance is affected by the operating variables such as initial substrate concentration, external resistor, influent substrate concentration, and dilution rate, and these variables were revealed to have complex interactions by data simulation. The external power generation and energy efficiency were considered as indices for MFC performance. The simulated results explained that an intermediate initial substrate concentration (about 100 mg/L under this reactor configuration) needed to be chosen to achieve maximum overall energy efficiency from substrate in the batch mode. An external resistor with the value approximately that of the internal resistance, boosted the power generation, and a resistor with several times of that of the internal resistance achieved better overall energy efficiency. At continuous mode, dilution rate significantly impacted the steady-state substrate concentration level (thus substrate removal efficiency and rate), and attached biomass could be fully developed when the influent substrate concentration was equal to or higher than 100 mg/L at any dilution rate of the tested range. Overall, this relatively simple model provided a convenient way for evaluating and optimizing the performance of MFC reactors by regulating operating parameters. Full article

(This article belongs to the Special Issue Microbial Fuel Cells)

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A schematic of organic substrate and energy flow in a microbial fuel cell. Full article ">Figure 2
Electrochemical parameters estimation and validation; (A) the electrode potential during polarization experiment; (B,C) model validation for experimental data from another identical microbial fuel cell (MFC) reactor (B for Uext, and C for Pext); and (D) comparison of the simulated and experimental Uext during inoculation stage. Full article ">Figure 3
Simulated time-course profiles of process variables at different initial substrate concentration. (A) the substrate concentration; (B) suspended biomass concentration; (C) attached biomass concentration, and (D) the external voltage Uext. Full article ">Figure 4
Simulated polarization curves at different moments of inoculation. Attached bacteria concentration reached a plateau value after about 2 d, and the polarization curves did not change much thereafter. Full article ">Figure 5
Simulated batch performance of MFC with 100 mg L−1 initial substrate at different external resistors. (A) substrate concentration; (B) suspended biomass concentration; (C) external voltage; and (D) power generation. Full article ">Figure 6
Process variables and MFC performance predicted at steady state under different dilution rates and influent substrate concentrations. (A) steady state substrate concentration; (B) suspended biomass concentration; (C) attached biomass concentration, and (D) the overall energy efficiency ηext. Full article ">Figure 7
Simulated MFC performance at steady state under different electrical currents (or external resistors), dilution rates and influent substrate concentrations. (A) steady state power density; (B) MFC cell energy efficiency; (C) overall energy efficiency at Sin = 100 mg L−1; and (D) Sin = 2400 mg L−1; (E) effluent substrate concentration at Sin = 100 mg L−1; and (F) Sin = 2400 mg L−1. Full article ">

26 pages, 10071 KiB

Open AccessArticle

Aerodynamic Force and Comprehensive Mechanical Performance of a Large Wind Turbine during a Typhoon Based on WRF/CFD Nesting

by Shitang Ke, Wenlin Yu, Jiufa Cao and Tongguang Wang

Appl. Sci. 2018, 8(10), 1982; https://doi.org/10.3390/app8101982 - 19 Oct 2018

Cited by 16 | Viewed by 4281

Abstract

Compared with normal wind, typhoons may change the flow field surrounding wind turbines, thus influencing their wind-induced responses and stability. The existing typhoon theoretical model in the civil engineering field is too simplified. To address this problem, the WRF (Weather Research Forecasting) model [...] Read more.

Compared with normal wind, typhoons may change the flow field surrounding wind turbines, thus influencing their wind-induced responses and stability. The existing typhoon theoretical model in the civil engineering field is too simplified. To address this problem, the WRF (Weather Research Forecasting) model was introduced for high-resolution simulation of the Typhoon “Nuri” firstly. Secondly, the typhoon field was analyzed, and the wind speed profile of the boundary layer was fitted. Meanwhile, the normal wind speed profile with the same wind speed of the typhoon speed profile at the gradient height of class B landform in the code was set. These two wind speed profiles were integrated into the UDF (User Defined Function). On this basis, a five-MW wind turbine in Shenzhen was chosen as the research object. The action mechanism of speed was streamlined and turbulence energy surrounding the wind turbine was disclosed by microscale CFD (Computational Fluid Dynamics) simulation. The influencing laws of a typhoon and normal wind on wind pressure distribution were compared. Finally, key attention was paid to analyzing the structural response, buckling stability, and ultimate bearing capacity of the wind turbine system. The research results demonstrated that typhoons increased the aerodynamic force and structural responses, and decreased the overall buckling stability and ultimate bearing capacity of the wind turbine. Full article

(This article belongs to the Special Issue Wind Turbine Aerodynamics)

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20 pages, 2013 KiB

Open AccessArticle

Convolutional Neural Network-Based Remote Sensing Images Segmentation Method for Extracting Winter Wheat Spatial Distribution

by Chengming Zhang, Shuai Gao, Xiaoxia Yang, Feng Li, Maorui Yue, Yingjuan Han, Hui Zhao, Ya’nan Zhang and Keqi Fan

Appl. Sci. 2018, 8(10), 1981; https://doi.org/10.3390/app8101981 - 19 Oct 2018

Cited by 14 | Viewed by 4257

Abstract

When extracting winter wheat spatial distribution by using convolutional neural network (CNN) from Gaofen-2 (GF-2) remote sensing images, accurate identification of edge pixel is the key to improving the result accuracy. In this paper, an approach for extracting accurate winter wheat spatial distribution [...] Read more.

When extracting winter wheat spatial distribution by using convolutional neural network (CNN) from Gaofen-2 (GF-2) remote sensing images, accurate identification of edge pixel is the key to improving the result accuracy. In this paper, an approach for extracting accurate winter wheat spatial distribution based on CNN is proposed. A hybrid structure convolutional neural network (HSCNN) was first constructed, which consists of two independent sub-networks of different depths. The deeper sub-network was used to extract the pixels present in the interior of the winter wheat field, whereas the shallower sub-network extracts the pixels at the edge of the field. The model was trained by classification-based learning and used in image segmentation for obtaining the distribution of winter wheat. Experiments were performed on 39 GF-2 images of Shandong province captured during 2017–2018, with SegNet and DeepLab as comparison models. As shown by the results, the average accuracy of SegNet, DeepLab, and HSCNN was 0.765, 0.853, and 0.912, respectively. HSCNN was equally as accurate as DeepLab and superior to SegNet for identifying interior pixels, and its identification of the edge pixels was significantly better than the two comparison models, which showed the superiority of HSCNN in the identification of winter wheat spatial distribution. Full article

(This article belongs to the Special Issue Machine Learning Techniques Applied to Geoscience Information System and Remote Sensing)

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Network architecture of the Hybrid Structure Convolutional Neural Network (HSCNN): (a) input; (b) inner-CNN; (c) inner-layers; (d) inner-encoder; (e) inner-classifier; (f) edge-CNN; (g) edge-layers; (h) edge-encoder; (i) edge-classifier; (j) vote function; (k) output. Full article ">Figure 2
Image-label pair example: (a) original image; and (b) labels. Full article ">Figure 3
Segmentation results for Gaofen-2 (GF-2) images: (a) original images; (b) ground truth, (c) results of SegNet corresponding to the images in (a); (d) errors of SegNet; (e) results of DeepLab; (f) errors of DeepLab; (g) results of HSCNN; and (h) errors of HSCNN. Full article ">Figure 3 Cont.
Segmentation results for Gaofen-2 (GF-2) images: (a) original images; (b) ground truth, (c) results of SegNet corresponding to the images in (a); (d) errors of SegNet; (e) results of DeepLab; (f) errors of DeepLab; (g) results of HSCNN; and (h) errors of HSCNN. Full article ">Figure 4
Distribution of the probability differences for the inner wheat pixels. Full article ">Figure 5
Distribution of the probability differences for the edge wheat pixels. Full article ">Figure 6
Distribution of the probability differences for the inner wheat pixels. Full article ">Figure 7
Distribution of the probability differences for the edge wheat pixels. Full article ">

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Appl. Sci., Volume 8, Issue 10 (October 2018) – 305 articles

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