Applied Sciences

40 pages, 703 KiB

Open AccessEditorial

Acknowledgement to Reviewers of Applied Sciences in 2018

by Applied Sciences Editorial Office

Appl. Sci. 2019, 9(1), 210; https://doi.org/10.3390/app9010210 - 8 Jan 2019

Viewed by 9487

Abstract

Rigorous peer-review is the corner-stone of high-quality academic publishing [...] Full article

20 pages, 5212 KiB

Open AccessArticle

Some Applications of ANN to Solar Radiation Estimation and Forecasting for Energy Applications

by Gilles Notton, Cyril Voyant, Alexis Fouilloy, Jean Laurent Duchaud and Marie Laure Nivet

Appl. Sci. 2019, 9(1), 209; https://doi.org/10.3390/app9010209 - 8 Jan 2019

Cited by 84 | Viewed by 8352

Abstract

In solar energy, the knowledge of solar radiation is very important for the integration of energy systems in building or electrical networks. Global horizontal irradiation (GHI) data are rarely measured over the world, thus an artificial neural network (ANN) model was built to [...] Read more.

In solar energy, the knowledge of solar radiation is very important for the integration of energy systems in building or electrical networks. Global horizontal irradiation (GHI) data are rarely measured over the world, thus an artificial neural network (ANN) model was built to calculate this data from more available ones. For the estimation of 5-min GHI, the normalized root mean square error (nRMSE) of the 6-inputs model is 19.35%. As solar collectors are often tilted, a second ANN model was developed to transform GHI into global tilted irradiation (GTI), a difficult task due to the anisotropy of scattering phenomena in the atmosphere. The GTI calculation from GHI was realized with an nRMSE around 8% for the optimal configuration. These two models estimate solar data at time, t, from other data measured at the same time, t. For an optimal management of energy, the development of forecasting tools is crucial because it allows anticipation of the production/consumption balance; thus, ANN models were developed to forecast hourly direct normal (DNI) and GHI irradiations for a time horizon from one hour (h+1) to six hours (h+6). The forecasting of hourly solar irradiation from h+1 to h+6 using ANN was realized with an nRMSE from 22.57% for h+1 to 34.85% for h+6 for GHI and from 38.23% for h+1 to 61.88% for h+6 for DNI. Full article

(This article belongs to the Special Issue Applications of Artificial Neural Networks for Energy Systems)

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15 pages, 3823 KiB

Open AccessArticle

Laboratory and Field Experiments on the Effect of Vinyl Acetate Polymer-Reinforced Soil

by Zezhuo Song, Jin Liu, Yuxia Bai, Jihong Wei, Ding Li, Qiongya Wang, Zhihao Chen, Debi Prasanna Kanungo and Wei Qian

Appl. Sci. 2019, 9(1), 208; https://doi.org/10.3390/app9010208 - 8 Jan 2019

Cited by 32 | Viewed by 5953

Abstract

Soil stabilizer can enhance the soil properties, which can improve ecological environmental problems such as soil erosion and slope instability. This study investigates the water-related and mechanical properties of soil stabilization using a polymer soil stabilizer solution synthesized from vinyl acetate polymer. The [...] Read more.

Soil stabilizer can enhance the soil properties, which can improve ecological environmental problems such as soil erosion and slope instability. This study investigates the water-related and mechanical properties of soil stabilization using a polymer soil stabilizer solution synthesized from vinyl acetate polymer. The water properties test, mechanical properties test, durability test and seed growth test were carried out in the laboratory. Also, the effect of vinyl acetate polymer was verified by field tests. The results revealed that vinyl acetate polymer can enhance the water-retaining property, anti-erosion resistance, strength property and durability of soil, all of which increase with the increase of polymer concentration. At the same time, the polymer also has a certain promoting effect on vegetation growth. In addition, field tests proved that vinyl acetate polymer has good effects on soil engineering. These results could be applied as a reference for vinyl acetate polymer-improved soil engineering. Full article

(This article belongs to the Section Chemical and Molecular Sciences)

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17 pages, 2388 KiB

Open AccessArticle

Effect of Shear Connector Layout on the Behavior of Steel-Concrete Composite Beams with Interface Slip

by Xinggui Zeng, Shao-Fei Jiang and Donghua Zhou

Appl. Sci. 2019, 9(1), 207; https://doi.org/10.3390/app9010207 - 8 Jan 2019

Cited by 16 | Viewed by 10030

Abstract

In a steel-concrete composite beam (hereafter referred to as a composite beam), partial interaction between the concrete slab and the steel beam results in an appreciable increase in the beam deflections relative to full interaction behavior. Moreover, the distribution type of the shear [...] Read more.

In a steel-concrete composite beam (hereafter referred to as a composite beam), partial interaction between the concrete slab and the steel beam results in an appreciable increase in the beam deflections relative to full interaction behavior. Moreover, the distribution type of the shear connectors has a great impact on the degree of the composite action between the two components of the beam. To reveal the effect of shear connector layout in the performance of composite beams, on the basis of a developed one-dimensional composite beam element validated by the closed-form precision solutions and experimental results, this paper optimizes the layout of shear connectors in composite beams with partial interaction by adopting a stepwise uniform distribution of shear connectors to approximate the triangular distribution of the shear connector density without increasing the total number of shear connectors. Based on a comparison of all the different types of stepped rectangles distribution, this paper finally suggests the 3-stepped rectangles distribution of shear connectors as a reasonable and applicable optimal method. Full article

(This article belongs to the Special Issue Soft Computing Techniques in Structural Engineering and Materials)

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15 pages, 2438 KiB

Open AccessArticle

Investigation on Interference Test for Wells Connected by a Large Fracture

by Guofeng Han, Yuewu Liu, Wenchao Liu and Dapeng Gao

Appl. Sci. 2019, 9(1), 206; https://doi.org/10.3390/app9010206 - 8 Jan 2019

Cited by 6 | Viewed by 6177

Abstract

Pressure communication between adjacent wells is frequently encountered in multi-stage hydraulic fractured shale gas reservoirs. An interference test is one of the most popular methods for testing the connectivity of a reservoir. Currently, there is no practical analysis model of an interference test [...] Read more.

Pressure communication between adjacent wells is frequently encountered in multi-stage hydraulic fractured shale gas reservoirs. An interference test is one of the most popular methods for testing the connectivity of a reservoir. Currently, there is no practical analysis model of an interference test for wells connected by large fractures. A one-dimensional equation of flow in porous media is established, and an analytical solution under the constant production rate is obtained using a similarity transformation. Based on this solution, the extremum equation of the interference test for wells connected by a large fracture is derived. The type-curve of pressure and the pressure derivative of an interference test of wells connected by a large fracture are plotted, and verified against interference test data. The extremum equation of wells connected by a large fracture differs from that for homogeneous reservoirs by a factor 2. Considering the difference of the flowing distance, it can be concluded that the pressure conductivity coefficient computed by the extremum equation of homogeneous reservoirs is accurate in the order of magnitude. On the double logarithmic type-curve, as time increases, the curves of pressure and the pressure derivative tend to be parallel straight lines with a slope of 0.5. When the crossflow of the reservoir matrix to the large fracture cannot be ignored, the slope of the parallel straight lines is 0.25. They are different from the type-curves of homogeneous and double porosity reservoirs. Therefore, the pressure derivative curve is proposed to diagnose the connection form of wells. Full article

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16 pages, 9347 KiB

Open AccessArticle

The Effect of Compactness on Laser Cutting of Cathode for Lithium-Ion Batteries Using Continuous Fiber Laser

by Dongkyoung Lee, Byungmoon Oh and Jungdon Suk

Appl. Sci. 2019, 9(1), 205; https://doi.org/10.3390/app9010205 - 8 Jan 2019

Cited by 20 | Viewed by 8866

Abstract

Lithium-Ion Batteries (LIB) are growing in popularity for many applications. Much research has been focusing on battery performance improvement. However, few studies have overcome the disadvantages of the conventional LIB manufacturing processes. Laser cutting of electrodes has been applied. However, the effect of [...] Read more.

Lithium-Ion Batteries (LIB) are growing in popularity for many applications. Much research has been focusing on battery performance improvement. However, few studies have overcome the disadvantages of the conventional LIB manufacturing processes. Laser cutting of electrodes has been applied. However, the effect of electrodes’ chemical, physical, and geometrical characteristics on the laser cutting has not been considered. This study proposes the effect of compression of cathode on laser cutting for lithium-ion batteries. The kerf width and top width of the specimens with laser irradiation are measured and the material removal energy is obtained. Observations of SEM photographs and absorptivity measurements are conducted. Increasing volume energies causes logarithmic increases in the kerf and top width. It is observed that the compressed cathode forms a wider kerf width than the uncompressed cathode under the same laser parameters. The top width of the uncompressed cathode is wider than the uncompressed cathode. The compression has a favorable effect on uniform cutting and selective removal of an active electrode. Full article

(This article belongs to the Special Issue High Capacity Electrode Materials for Advanced Lithium Ion Batteries)

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18 pages, 4712 KiB

Open AccessArticle

Analysis and Impact Evaluation of Missing Data Imputation in Day-ahead PV Generation Forecasting

by Taeyoung Kim, Woong Ko and Jinho Kim

Appl. Sci. 2019, 9(1), 204; https://doi.org/10.3390/app9010204 - 8 Jan 2019

Cited by 83 | Viewed by 8352

Abstract

Over the past decade, PV power plants have increasingly contributed to power generation. However, PV power generation widely varies due to environmental factors; thus, the accurate forecasting of PV generation becomes essential. Meanwhile, weather data for environmental factors include many missing values; for [...] Read more.

Over the past decade, PV power plants have increasingly contributed to power generation. However, PV power generation widely varies due to environmental factors; thus, the accurate forecasting of PV generation becomes essential. Meanwhile, weather data for environmental factors include many missing values; for example, when we estimated the missing values in the precipitation data of the Korea Meteorological Agency, they amounted to ~16% from 2015–2016, and further, 19% of the weather data were missing for 2017. Such missing values deteriorate the PV power generation prediction performance, and they need to be eliminated by filling in other values. Here, we explore the impact of missing data imputation methods that can be used to replace these missing values. We apply four missing data imputation methods to the training data and test data of the prediction model based on support vector regression. When the k-nearest neighbors method is applied to the test data, the prediction performance yields results closest to those for the original data with no missing values, and the prediction model’s performance is stable even when the missing data rate increases. Therefore, we conclude that the most appropriate missing data imputation for application to PV forecasting is the KNN method. Full article

(This article belongs to the Special Issue Applications of Artificial Neural Networks for Energy Systems)

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15 pages, 5236 KiB

Open AccessArticle

An Improved Skewness Balancing Filtering Algorithm Based on Thin Plate Spline Interpolation

by Penggen Cheng, Zhenyang Hui, Yuanping Xia, Yao Yevenyo Ziggah, Youjian Hu and Jing Wu

Appl. Sci. 2019, 9(1), 203; https://doi.org/10.3390/app9010203 - 8 Jan 2019

Cited by 15 | Viewed by 4135

Abstract

Most filtering algorithms suffer from complex parameter settings or threshold adjusting. To solve this problem, this paper proposes an improved skewness balancing filtering algorithm based on thin plate spline (TPS) interpolation. The proposed algorithm filters the nonground points in an iterative manner. A [...] Read more.

Most filtering algorithms suffer from complex parameter settings or threshold adjusting. To solve this problem, this paper proposes an improved skewness balancing filtering algorithm based on thin plate spline (TPS) interpolation. The proposed algorithm filters the nonground points in an iterative manner. A reference surface that reflects the fluctuation of the terrain is generated using the TPS interpolation method. Accordingly, the elevation difference from each point to the surface can be calculated. By applying the skewness balancing principle to these elevation differences, nonground points can be removed automatically. To verify the validity and robustness of the proposed method, the datasets provided by the International Society for Photogrammetry and Remote Sensing (ISPRS) were adopted. The experimental results show that this presented method can adapt to complex environments and achieve a higher filtering accuracy than the traditional skewness balancing algorithm. Moreover, in comparison with the other eight filtering methods tested by the ISPRS and four improved filtering methods proposed recently, the proposed method achieved an average total error of 5.39%, which is smaller than that of most of these other methods. Full article

(This article belongs to the Special Issue LiDAR and Time-of-flight Imaging)

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11 pages, 1046 KiB

Open AccessArticle

Regularization Factor Selection Method for l₁-Regularized RLS and Its Modification against Uncertainty in the Regularization Factor

by Junseok Lim and Seokjin Lee

Appl. Sci. 2019, 9(1), 202; https://doi.org/10.3390/app9010202 - 8 Jan 2019

Cited by 3 | Viewed by 3295

Abstract

This paper presents a new l₁-RLS method to estimate a sparse impulse response estimation. A new regularization factor calculation method is proposed for l₁-RLS that requires no information of the true channel response in advance. In addition, we also [...] Read more.

This paper presents a new l₁-RLS method to estimate a sparse impulse response estimation. A new regularization factor calculation method is proposed for l₁-RLS that requires no information of the true channel response in advance. In addition, we also derive a new model to compensate for uncertainty in the regularization factor. The results of the estimation for many different kinds of sparse impulse responses show that the proposed method without a priori channel information is comparable to the conventional method with a priori channel information. Full article

(This article belongs to the Special Issue Modelling, Simulation and Data Analysis in Acoustical Problems)

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20 pages, 3311 KiB

Open AccessArticle

A Novel Heart Rate Robust Method for Short-Term Electrocardiogram Biometric Identification

by Di Wang, Yujuan Si, Weiyi Yang, Gong Zhang and Tong Liu

Appl. Sci. 2019, 9(1), 201; https://doi.org/10.3390/app9010201 - 8 Jan 2019

Cited by 29 | Viewed by 5546

Abstract

In the past decades, the electrocardiogram (ECG) has been investigated as a promising biometric by exploiting the subtle discrepancy of ECG signals between subjects. However, the heart rate (HR) for one subject may vary because of physical activities or strong emotions, leading to [...] Read more.

In the past decades, the electrocardiogram (ECG) has been investigated as a promising biometric by exploiting the subtle discrepancy of ECG signals between subjects. However, the heart rate (HR) for one subject may vary because of physical activities or strong emotions, leading to the problem of ECG signal variation. This variation will significantly decrease the performance of the identification task. Particularly for short-term ECG signal without many heartbeats, the hardly measured HR makes the identification task even more challenging. This study aims to propose a novel method suitable for short-term ECG signal identification. In particular, an improved HR-free resampling strategy is proposed to minimize the influence of HR variability during heartbeat processing. For feature extraction, the Principal Component Analysis Network (PCANet) is implemented to determine the potential difference between subjects. The proposed method is evaluated using a public ECG-ID database that contains various HR data for some subjects. Experimental results show that the proposed method is robust to HR change and can achieve high subject identification accuracy (94.4%) on ECG signals with only five heartbeats. Thus, the proposed method has the potential for application to systems that use short-term ECG signals for identification (e.g., wearable devices). Full article

(This article belongs to the Special Issue Advanced Biometrics with Deep Learning)

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21 pages, 1729 KiB

Open AccessArticle

Local, Story, and Global Ductility Evaluation for Complex 2D Steel Buildings: Pushover and Dynamic Analysis

by Mario D. Llanes-Tizoc, Alfredo Reyes-Salazar, Eden Bojorquez, Juan Bojorquez, Arturo Lopez-Barraza, J. Luz Rivera-Salas and Jose R. Gaxiola-Camacho

Appl. Sci. 2019, 9(1), 200; https://doi.org/10.3390/app9010200 - 8 Jan 2019

Cited by 10 | Viewed by 3690

Abstract

A numerical investigation regarding ductility evaluation of steel buildings with moment resisting steel frames is conducted. Bending (µ_Lϕ) and tension (µ_Lδ) local ductilities as well as story (µ_S) and global ductilities are studied. Global [...] Read more.

A numerical investigation regarding ductility evaluation of steel buildings with moment resisting steel frames is conducted. Bending (µ_Lϕ) and tension (µ_Lδ) local ductilities as well as story (µ_S) and global ductilities are studied. Global ductility is calculated as the mean values of story ductilities (µ_GS) and as the ratio of the maximum inelastic to yielding top displacements (µ_Gt). The ductility capacity is associated to drifts of about 5%. Ductility values significantly may vary with the strong motion, ductility definition, structural element, story number, type of analysis, and model. µ_Lϕ is much larger for beams than for columns. Even though the demands of µ_Lδ are considered an important issue they are less relevant than µ_Lϕ. µ_S is much smaller than µ_Lϕ for beams. µ_GS for dynamic analysis give reasonable values, but µ_Gt does not. µ_Lϕ, µ_S and µ_GS obtained from pushover are larger than those obtained from dynamic analysis and unlike the case of dynamic analysis, µ_Lϕ tend to increase with the story number showing an opposite trend. Considering that: µ_Gt for dynamic analysis results in unreasonable values, pushover analysis does not consider energy dissipation, the strong column–weak beam (SCWB) concept was followed in the model designs, and µ_Lδ is not relevant in framed steel buildings, the ratio (R_LG) of global to local ductility capacity is calculated as the ratio of µ_GS to µ_Lϕ of beams, for dynamic analysis. A value of 1/3 is proposed. Thus, if bending local ductility capacity is stated as the basis for the design, the global ductility capacity can be easily estimated. Full article

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21 pages, 2029 KiB

Open AccessArticle

Capacity Credit Evaluation of Correlated Wind Resources Using Vine Copula and Improved Importance Sampling

by Jilin Cai, Qingshan Xu, Minjian Cao and Yongbiao Yang

Appl. Sci. 2019, 9(1), 199; https://doi.org/10.3390/app9010199 - 8 Jan 2019

Cited by 5 | Viewed by 3617

Abstract

This paper concentrates on the capacity credit (CC) evaluation of wind energy, where a new method for constructing the joint distribution of wind speed and load is proposed. The method is based on the skew-normal mixture model (SNMM) and D-vine copulas, which is [...] Read more.

This paper concentrates on the capacity credit (CC) evaluation of wind energy, where a new method for constructing the joint distribution of wind speed and load is proposed. The method is based on the skew-normal mixture model (SNMM) and D-vine copulas, which is used to model the marginal distribution and the correlation structure, respectively. Then a cross entropy based importance sampling (CE-IS) is improved to enhance the efficiency of the power system reliability assessment, which is a crucial part of the CC evaluation. After that, the proposed methods are adopted to combine with the secant method to develop a complete algorithm to calculate the CC of wind energy. Numerical tests are designed and carried out based on the IEEE-RTS 79 system and wind speed data obtained from four wind farms in Northwest China. In order to show the superiority of SNMM and D-vine copula, the goodness-of-fit is quantified by different statistics. Besides, the improved CE-IS method is validated by comparison with Monte Carlo sampling (MCS) and traditional CE-IS in the efficiency of reliability assessment. Finally, the proved methods are combined with the secant method to calculate the CC of four wind farms, which can provide information for wind farm planning. Full article

(This article belongs to the Special Issue Planning, Operation, and Control of Power Systems with Large-Scale Renewable Energy)

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17 pages, 1745 KiB

Open AccessArticle

Calibration for Sample-And-Hold Mismatches in M-Channel TIADCs Based on Statistics

by Xiangyu Liu, Hui Xu, Yinan Wang, Yingqiang Dai, Nan Li and Guiqing Liu

Appl. Sci. 2019, 9(1), 198; https://doi.org/10.3390/app9010198 - 8 Jan 2019

Cited by 7 | Viewed by 3525

Abstract

Time-interleaved analog-to-digital converter (TIADC) is a good option for high sampling rate applications. However, the inevitable sample-and-hold (S/H) mismatches between channels incur undesirable error and then affect the TIADC’s dynamic performance. Several calibration methods have been proposed for S/H mismatches which either need [...] Read more.

Time-interleaved analog-to-digital converter (TIADC) is a good option for high sampling rate applications. However, the inevitable sample-and-hold (S/H) mismatches between channels incur undesirable error and then affect the TIADC’s dynamic performance. Several calibration methods have been proposed for S/H mismatches which either need training signals or have less extensive applicability for different input signals and different numbers of channels. This paper proposes a statistics-based calibration algorithm for S/H mismatches in M-channel TIADCs. Initially, the mismatch coefficients are identified by eliminating the statistical differences between channels. Subsequently, the mismatch-induced error is approximated by employing variable multipliers and differentiators in several Richardson iterations. Finally, the error is subtracted from the original output signal to approximate the expected signal. Simulation results illustrate the effectiveness of the proposed method, the selection of key parameters and the advantage to other methods. Full article

(This article belongs to the Special Issue Selected Papers from the 2018 41st International Conference on Telecommunications and Signal Processing (TSP))

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18 pages, 3598 KiB

Open AccessArticle

Effect of the Nature and Relative Concentration of Substrate, Water Mineralization, and Storage Temperature on the Oxidants Produced by Lactoperoxidase and on Their Antifungal Activity against Penicillium expansum and Botrytis cinerea

by Françoise Bafort, Christian Damblon, Georges C. Lognay, Jean-Paul Barthelemy, Jean-Paul Perraudin and Mohamed Haïssam Jijakli

Appl. Sci. 2019, 9(1), 197; https://doi.org/10.3390/app9010197 - 8 Jan 2019

Cited by 2 | Viewed by 3800

Abstract

Lactoperoxidase is an enzyme that generates oxidants with antimicrobial activity in presence of a (pseudo)halogen and hydrogen peroxide, but various factors can drastically reduce the antimicrobial activity of the lactoperoxidase system. Spectroscopic, ionic chromatography, and ¹³C-NMR methods showed that the oxidants generated [...] Read more.

Lactoperoxidase is an enzyme that generates oxidants with antimicrobial activity in presence of a (pseudo)halogen and hydrogen peroxide, but various factors can drastically reduce the antimicrobial activity of the lactoperoxidase system. Spectroscopic, ionic chromatography, and ¹³C-NMR methods showed that the oxidants generated by lactoperoxidase are OSCN⁻ in the presence of SCN⁻ and I₂ in the presence of I⁻. Neither of them, however, inhibited Penicillium expansum, one of the causal agents of fruit mold. When a mixture of SCN⁻ and I⁻ was used, no OSCN⁻, OCN⁻, I₂, or interhalogen I₂SCN⁻ was produced. However, its long-term stability, NH₂-oxidizing capacity, and antifungal activity against P. expansum argue in favor of an I⁻-derived oxidant. Strongly mineralized water optimized enzyme-catalyzed reactions with higher oxidant production. Storage at 4 °C resulted in long-term stability and extended antifungal activity against P. expansum. The relative iodide/thiocyanate concentrations turned out to be important, as better in vitro inhibition of Botrytis cinerea, the causal agent of apples’s grey mold, was obtained with a high KI + KSCN concentration, a KI/KSCN ratio of 4.5, and a (KI + KSCN)/H₂O₂ ratio of 1. The nature of the substrates, their relative concentrations, the medium, and the storage temperature modifed the antifungal activity of lactoperoxidase. Full article

(This article belongs to the Section Chemical and Molecular Sciences)

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15 pages, 3893 KiB

Open AccessArticle

Leakage Detection of a Spherical Water Storage Tank in a Chemical Industry Using Acoustic Emissions

by Muhammad Sohaib, Manjurul Islam, Jaeyoung Kim, Duck-Chan Jeon and Jong-Myon Kim

Appl. Sci. 2019, 9(1), 196; https://doi.org/10.3390/app9010196 - 8 Jan 2019

Cited by 34 | Viewed by 6913

Abstract

Spherical storage tanks are used in various industries to store substances like gasoline, oxygen, waste water, and liquefied petroleum gas (LPG). Cracks in the storage tanks are unaccepted defects, as storage tanks can leak or spill the contained substance through these cracks. Leakage [...] Read more.

Spherical storage tanks are used in various industries to store substances like gasoline, oxygen, waste water, and liquefied petroleum gas (LPG). Cracks in the storage tanks are unaccepted defects, as storage tanks can leak or spill the contained substance through these cracks. Leakage from contained hazardous substances storage tanks can contaminate the environment and may lead to fatal accidents. Therefore, the ability to detect cracks from spherical storage tanks is necessary to avoid damage to the environment and to ensure public safety. In this paper, we present a crack detection case study of a spherical tank. The detection was performed using time-domain statistical features and a machine learning algorithm. The proposed method consists of (1) extraction of statistical features from the acoustic emissions (AE) acquired from the spherical tank, and (2) classification of the nonlinear data using a support vector machine (SVM). We evaluate the proposed algorithm with AE data obtained from the spherical tank, demonstrating that the algorithm effectively discriminates between normal and crack conditions. These results show that the proposed algorithm is effective for detecting cracks in spherical storage tanks. Full article

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

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15 pages, 2496 KiB

Open AccessArticle

Transmission Matrix Measurement of Multimode Optical Fibers by Mode-Selective Excitation Using One Spatial Light Modulator

by Stefan Rothe, Hannes Radner, Nektarios Koukourakis and Jürgen W. Czarske

Appl. Sci. 2019, 9(1), 195; https://doi.org/10.3390/app9010195 - 8 Jan 2019

Cited by 33 | Viewed by 6612

Abstract

Multimode fibers (MMF) are promising candidates to increase the data rate while reducing the space required for optical fiber networks. However, their use is hampered by mode mixing and other effects, leading to speckled output patterns. This can be overcome by measuring the [...] Read more.

Multimode fibers (MMF) are promising candidates to increase the data rate while reducing the space required for optical fiber networks. However, their use is hampered by mode mixing and other effects, leading to speckled output patterns. This can be overcome by measuring the transmission matrix (TM) of a multimode fiber. In this contribution, a mode-selective excitation of complex amplitudes is performed with only one phase-only spatial light modulator. The light field propagating through the fiber is measured holographically and is analyzed by a rapid decomposition method. This technique requires a small amount of measurements N, which corresponds to the degree of freedom of the fiber. The TM determines the amplitude and phase relationships of the modes, which allows us to understand the mode scrambling processes in the MMF and can be used for mode division multiplexing. Full article

(This article belongs to the Special Issue Liquid Crystal on Silicon Devices: Modeling and Advanced Spatial Light Modulation Applications)

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16 pages, 10593 KiB

Open AccessArticle

Acoustic Emission Characteristics During Rock Fragmentation Processes Induced by Disc Cutter under Different Water Content Conditions

by Qibin Lin, Ping Cao, Rihong Cao and Xiang Fan

Appl. Sci. 2019, 9(1), 194; https://doi.org/10.3390/app9010194 - 7 Jan 2019

Cited by 21 | Viewed by 4549

Abstract

Based on a properly modified testing platform and Physical Acoustics Corporation (PAC) Micro-II acoustic emission (AE) system, a series of sequential indentation tests on granite samples with five different water contents was conducted to investigate the effect of the water content on the [...] Read more.

Based on a properly modified testing platform and Physical Acoustics Corporation (PAC) Micro-II acoustic emission (AE) system, a series of sequential indentation tests on granite samples with five different water contents was conducted to investigate the effect of the water content on the rock fragmentation process induced by a tunnel boring machine (TBM) disc cutter. During these tests, the effects of the water content on the characteristics of the peak penetration force, AE events, consumed energy, rock chip volume, and specific energy were analyzed. The results showed that the AE events were associated with the whole second indentation process of the granite. Under conditions with the same water content, the peak penetration forces and the consumed energy were smaller than those in the first indentation force. Additionally, subsequent chips were formed more frequently than the first indentation chips. The specific energy was lower, which meant that the rock breaking efficiency was higher. With the increase in the water content, the acoustic emission events reduced. The peak penetration force and consumed energy decreased with the increase in the water content. The volume of the chips increased significantly as the water content increased. The specific energy was promoted by the increase of the water content and then by the increase in the rock-breaking efficiency of the TBM disc cutter. Full article

(This article belongs to the Special Issue Application of Acoustic Emission (AE) on Rock Samples)

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14 pages, 1629 KiB

Open AccessReview

Volume Holographic Optical Elements as Solar Concentrators: An Overview

by Maria Antonietta Ferrara, Valerio Striano and Giuseppe Coppola

Appl. Sci. 2019, 9(1), 193; https://doi.org/10.3390/app9010193 - 7 Jan 2019

Cited by 35 | Viewed by 6877

Abstract

Generally, to reduce the area of a photovoltaic cell, which is typically very expensive, solar concentrators based on a set of mirrors or mechanical structures are used. However, such solar concentrators have some drawbacks, as they need a tracking system to track the [...] Read more.

Generally, to reduce the area of a photovoltaic cell, which is typically very expensive, solar concentrators based on a set of mirrors or mechanical structures are used. However, such solar concentrators have some drawbacks, as they need a tracking system to track the sun’s position and also they suffer for the overheat due to the concentration of both light and heat on the solar cell. The fundamental advantages of volume holographic optical elements are very appealing for lightweight and cheap solar concentrators applications and can become a valuable asset that can be integrated into solar panels. In this paper, a review of volume holographic-based solar concentrators recorded on different holographic materials is presented. The physical principles and main advantages and disadvantages, such as their cool light concentration, selective wavelength concentrations and the possibility to implement passive solar tracking, are discussed. Different configurations and strategies are illustrated and the state-of-the-art is presented including commercially available systems. Full article

(This article belongs to the Special Issue Holography, 3D Imaging and 3D Display)

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18 pages, 708 KiB

Open AccessArticle

Overcoming Individual Discrepancies, a Learning Model for Non-Invasive Blood Glucose Measurement

by Weijie Liu, Anpeng Huang and Ping Wan

Appl. Sci. 2019, 9(1), 192; https://doi.org/10.3390/app9010192 - 7 Jan 2019

Cited by 2 | Viewed by 4404

Abstract

Non-invasive Glucose Measurement (NGM) technology makes great sense for the blood glucose management of patients with hyperglycemia or hypoglycemia. Individual Discrepancies (IDs), e.g., skin thickness and color, not only block the development of NGM, but also become the reason why NGM cannot be [...] Read more.

Non-invasive Glucose Measurement (NGM) technology makes great sense for the blood glucose management of patients with hyperglycemia or hypoglycemia. Individual Discrepancies (IDs), e.g., skin thickness and color, not only block the development of NGM, but also become the reason why NGM cannot be widely used. To solve this problem, our solution is designing an individual customized NGM model that can measure these discrepancies through multi-wavelength and tune parameters for glucose estimating. In this paper, an NGM prototype is designed, and a learning model for glucose estimating with automatically parameters tuning based on Independent Component Analysis (ICA) and Random Forest (RF) is presented. The clinic trial proves that the correlation coefficient between estimation and reference Blood Glucose Concentration (BGC) can reach 0.5 after merely 10 times of learning, and rise to 0.8 after about 60 times of learning. Full article

(This article belongs to the Section Mechanical Engineering)

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13 pages, 3981 KiB

Open AccessArticle

TOSCA-Based and Federation-Aware Cloud Orchestration for Kubernetes Container Platform

by Dongmin Kim, Hanif Muhammad, Eunsam Kim, Sumi Helal and Choonhwa Lee

Appl. Sci. 2019, 9(1), 191; https://doi.org/10.3390/app9010191 - 7 Jan 2019

Cited by 33 | Viewed by 8300

Abstract

Kubernetes, a container orchestration tool for automatically installing and managing Docker containers, has recently begun to support a federation function of multiple Docker container clusters. This technology, called Kubernetes Federation, allows developers to increase the responsiveness and reliability of their applications by distributing [...] Read more.

Kubernetes, a container orchestration tool for automatically installing and managing Docker containers, has recently begun to support a federation function of multiple Docker container clusters. This technology, called Kubernetes Federation, allows developers to increase the responsiveness and reliability of their applications by distributing and federating container clusters to multiple service areas of cloud service providers. However, it is still a daunting task to manually manage federated container clusters across all the service areas or to maintain the entire topology of cloud applications at a glance. This research work proposes a method to automatically form and monitor Kubernetes Federation, given application topology descriptions in TOSCA (Topology and Orchestration Specification for Cloud Applications), by extending the orchestration tool that automatizes the modeling and instantiation of cloud applications. It also demonstrates the successful federation of the clusters according to the TOSCA specifications and verifies the auto-scaling capability of the configured system through a scenario in which the servers of a sample application are deployed and federated. Full article

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9 pages, 3657 KiB

Open AccessCommunication

Fabrication of Hydrophobic Coatings Using Sugarcane Bagasse Waste Ash as Silica Source

by Sriharan Natarajan, Senthil Thottipalayam Subramaniyam and Vignesh Kumaravel

Appl. Sci. 2019, 9(1), 190; https://doi.org/10.3390/app9010190 - 7 Jan 2019

Cited by 9 | Viewed by 5160

Abstract

Eco-friendly hydrophobic coatings were fabricated on tiles via the drop-casting process. Sugarcane bagasse waste ash (SBA) was used as a silica source and dimethyldiethoxysilane (DMDEOS) was used as a surface functionalizing agent. The elemental composition of SBA was measured using X-ray fluorescence (XRF) [...] Read more.

Eco-friendly hydrophobic coatings were fabricated on tiles via the drop-casting process. Sugarcane bagasse waste ash (SBA) was used as a silica source and dimethyldiethoxysilane (DMDEOS) was used as a surface functionalizing agent. The elemental composition of SBA was measured using X-ray fluorescence (XRF) and energy-dispersive spectroscopy (EDS) techniques. The surface morphology of SBA was analyzed through the field-emission scanning electron microscopy (FESEM) technique. The surface wettability of SBA coated tiles was evaluated by determining the static water contact angle (WCA). XRF studies showed that the impurities were removed, and the silica content was enriched by the acid treatment. SBA coated tiles showed good hydrophobicity with a WCA of 135°. The high hydrophobicity of the coated tiles may be attributed to the increase of surface roughness by SBA. Moreover, the SBA coating was successfully tested on various substrates such as tiles, brick, glass, and cotton cloth. SBA coated glass substrate was more durable compared to other substrates at normal room temperature. Full article

(This article belongs to the Section Chemical and Molecular Sciences)

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18 pages, 9600 KiB

Open AccessArticle

The Heat Transfer Analysis of an Acting-type Heat Retention Panel used in a Hot Rolling Process

by Jiin-Yuh Jang, Jin-Wei Guo and Chih-Chung Chang

Appl. Sci. 2019, 9(1), 189; https://doi.org/10.3390/app9010189 - 7 Jan 2019

Cited by 4 | Viewed by 6149

Abstract

In the hot strip rolling process, improvement of the mechanical properties of the strip steel has been a focus for a long time. After rough rolling, high temperature transfer bars are transported by conveyors through the heat retention panel in order to decrease [...] Read more.

In the hot strip rolling process, improvement of the mechanical properties of the strip steel has been a focus for a long time. After rough rolling, high temperature transfer bars are transported by conveyors through the heat retention panel in order to decrease the temperature difference between the head and the tail of the transfer bars. During the heat retention process, the temperature distribution of the transfer bars have a great influence on the mechanical properties of strip steel. A three-dimensional numerical model of a traditional passive heat retention panel is developed to investigate the temperature difference between the head and the tail of the transfer bars. A comparison with the in-situ data from a steel company in Taiwan shows that the present model works well for the prediction of temperature values of the head and the tail and temperature differences of the transfer bars. Based on the developed model, a three-dimensional numerical model of the acting-type heat retention panel is constructed in order to predict whether the temperature difference decreases during the heat retention process. Full article

(This article belongs to the Section Energy Science and Technology)

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25 pages, 7254 KiB

Open AccessFeature PaperEditor’s ChoiceReview

A Review: Thermal Stability of Methylammonium Lead Halide Based Perovskite Solar Cells

by Tanzila Tasnim Ava, Abdullah Al Mamun, Sylvain Marsillac and Gon Namkoong

Appl. Sci. 2019, 9(1), 188; https://doi.org/10.3390/app9010188 - 7 Jan 2019

Cited by 186 | Viewed by 19515

Abstract

Perovskite solar cells have achieved photo-conversion efficiencies greater than 20%, making them a promising candidate as an emerging solar cell technology. While perovskite solar cells are expected to eventually compete with existing silicon-based solar cells on the market, their long-term stability has become [...] Read more.

Perovskite solar cells have achieved photo-conversion efficiencies greater than 20%, making them a promising candidate as an emerging solar cell technology. While perovskite solar cells are expected to eventually compete with existing silicon-based solar cells on the market, their long-term stability has become a major bottleneck. In particular, perovskite films are found to be very sensitive to external factors such as air, UV light, light soaking, thermal stress and others. Among these stressors, light, oxygen and moisture-induced degradation can be slowed by integrating barrier or interface layers within the device architecture. However, the most representative perovskite absorber material, CH₃NH₃PbI₃ (MAPbI₃), appears to be thermally unstable even in an inert environment. This poses a substantial challenge for solar cell applications because device temperatures can be over 45 °C higher than ambient temperatures when operating under direct sunlight. Herein, recent advances in resolving thermal stability problems are highlighted through literature review. Moreover, the most recent and promising strategies for overcoming thermal degradation are also summarized. Full article

(This article belongs to the Special Issue Next Generation Photovoltaic Solar Cells)

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48 pages, 20797 KiB

Open AccessFeature PaperReview

Brillouin Optical Correlation-Domain Technologies Based on Synthesis of Optical Coherence Function as Fiber Optic Nerve Systems for Structural Health Monitoring

by Kazuo Hotate

Appl. Sci. 2019, 9(1), 187; https://doi.org/10.3390/app9010187 - 7 Jan 2019

Cited by 49 | Viewed by 7370

Abstract

Brillouin optical correlation-domain technologies are reviewed as “fiber optic nerve systems” for the health monitoring of large structures such as buildings, bridges, and aircraft bodies. The Brillouin scattering property is used as a sensing mechanism for strain and/or temperature. Continuous lightwaves are used [...] Read more.

Brillouin optical correlation-domain technologies are reviewed as “fiber optic nerve systems” for the health monitoring of large structures such as buildings, bridges, and aircraft bodies. The Brillouin scattering property is used as a sensing mechanism for strain and/or temperature. Continuous lightwaves are used in the technologies, and their optical coherence properties are synthesized to realize position-selective measurement. This coherence manipulation technology is called the “synthesis of optical coherence function (SOCF)”. By utilizing SOCF technologies, stimulated Brillouin scattering is generated position-selectively along the fiber, which is named “Brillouin optical correlation domain analysis (BOCDA)”. Spontaneous Brillouin scattering, which takes place at any portion along the fiber, can also be measured position-selectively by the SOCF technology. This is called “Brillouin optical correlation domain reflectometry (BOCDR)”. When we use pulsed lightwaves that have the position information, sensing performances, such as the spatial resolution, are inherently restricted due to the Brillouin scattering nature. However, in the correlation-domain technologies, such difficulties can be reduced. Superior performances have been demonstrated as distribution-sensing mechanisms, such as a 1.6-mm high spatial resolution, a fast measurement speed of 5000 points/s, and a 7000-με strain dynamic range, individually. The total performance of the technologies is also discussed in this paper. A significant feature of the technologies is their random accessibility to discrete multiple points that are selected arbitrarily along the fiber, which is not realized by the time domain pulsed-lightwave technologies. Discriminative and distributed strain/temperature measurements have also been realized using both the BOCDA technology and Brillouin dynamic grating (BDG) phenomenon, which are associated with the stimulated Brillouin scattering process. In this paper, the principles, functions, and applications of the SOCF, BOCDA, BOCDR, and BDG-BOCDA systems are reviewed, and their historical aspects are also discussed. Full article

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

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13 pages, 3186 KiB

Open AccessArticle

Enhancing the Performance of Motive Power Lead-Acid Batteries by High Surface Area Carbon Black Additives

by Hai-Yan Hu, Ning Xie, Chen Wang, Fan Wu, Ming Pan, Hua-Fei Li, Ping Wu, Xiao-Di Wang, Zheling Zeng, Shuguang Deng, Marvin H. Wu, K. Vinodgopal and Gui-Ping Dai

Appl. Sci. 2019, 9(1), 186; https://doi.org/10.3390/app9010186 - 7 Jan 2019

Cited by 30 | Viewed by 6757

Abstract

The effects of carbon black specific surface area and morphology were investigated by characterizing four different carbon black additives and then evaluating the effect of adding them to the negative electrode of valve-regulated lead–acid batteries for electric bikes. Low-temperature performance, larger current discharge [...] Read more.

The effects of carbon black specific surface area and morphology were investigated by characterizing four different carbon black additives and then evaluating the effect of adding them to the negative electrode of valve-regulated lead–acid batteries for electric bikes. Low-temperature performance, larger current discharge performance, charge acceptance, cycle life and water loss of the batteries with carbon black were studied. The results show that the addition of high-performance carbon black to the negative plate of lead–acid batteries has an important effect on the cycle performance at 100% depth-of-discharge conditions and the cycle life is 86.9% longer than that of the control batteries. The excellent performance of the batteries can be attributed to the high surface area carbon black effectively inhibiting the sulfation of the negative plate surface and improving the charge acceptance of the batteries. Full article

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

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13 pages, 7740 KiB

Open AccessArticle

Design of Synchronized Large-Scale Chaos Random Number Generators and Its Application to Secure Communication

by Teh-Lu Liao, Pei-Yen Wan and Jun-Juh Yan

Appl. Sci. 2019, 9(1), 185; https://doi.org/10.3390/app9010185 - 7 Jan 2019

Cited by 14 | Viewed by 4666

Abstract

This paper is concerned with the design of synchronized large-scale chaos random number generators (CRNGs) and its application to secure communication. In order to increase the diversity of chaotic signals, we firstly introduce additional modulation parameters in the original chaotic Duffing map system [...] Read more.

This paper is concerned with the design of synchronized large-scale chaos random number generators (CRNGs) and its application to secure communication. In order to increase the diversity of chaotic signals, we firstly introduce additional modulation parameters in the original chaotic Duffing map system to modulate the amplitude and DC offset of the chaotic states. Then according to the butterfly effect, we implement modulated Duffing map systems with different initial values by using the microcontroller and complete the design of large-scale CRNGs. Next, a discrete sliding mode scheme is proposed to solve the synchronization problem of the master-slave large-scale CRNGs. Finally, we integrate the aforementioned results to implement an innovative secure communication system. Full article

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

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9 pages, 2081 KiB

Open AccessArticle

Line Beam Scanning-Based Ultra-Fast THz Imaging Platform

by Huachuan Huang, Qiao Liu, Yi Zou, Liguo Zhu, Zhenhua Li and Zeren Li

Appl. Sci. 2019, 9(1), 184; https://doi.org/10.3390/app9010184 - 7 Jan 2019

Cited by 7 | Viewed by 3535

Abstract

In order to realize rapid THz detecting and imaging, a line beam scanning-based ultra-fast THz imaging platform is designed combining simple optical components and lightweight mechanical system. The designed THz imaging platform has the resolution of 12 mm, the scanning angle range of [...] Read more.

In order to realize rapid THz detecting and imaging, a line beam scanning-based ultra-fast THz imaging platform is designed combining simple optical components and lightweight mechanical system. The designed THz imaging platform has the resolution of 12 mm, the scanning angle range of ±10.5°, the scanning speed of 0.17 s/frame, and the scanning range of 2 m × 0.8 m; moreover, it can realize rapid human body THz imaging and distinguish metallic objects. Considering its high-quality performance in THz imaging and detecting, it is believed the proposed line beam scanning-based ultra-fast THz imaging platform can be used in the future in various safe screening applications. Full article

(This article belongs to the Section Optics and Lasers)

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17 pages, 4492 KiB

Open AccessArticle

Analysis of Six Active Power Control Strategies of Interconnected Grids with VSC-HVDC

by Sungyoon Song, Minhan Yoon and Gilsoo Jang

Appl. Sci. 2019, 9(1), 183; https://doi.org/10.3390/app9010183 - 6 Jan 2019

Cited by 8 | Viewed by 4920

Abstract

In this paper, the generator angle stability of several active power control schemes of a voltage-source converter (VSC)-based high-voltage DC (HVDC) is evaluated for two interconnected AC systems. Excluding frequency control, there has been no detailed analysis of interconnected grids depending upon the [...] Read more.

In this paper, the generator angle stability of several active power control schemes of a voltage-source converter (VSC)-based high-voltage DC (HVDC) is evaluated for two interconnected AC systems. Excluding frequency control, there has been no detailed analysis of interconnected grids depending upon the converter power control, so six different types of active power control of the VSC-HVDC are defined and analyzed in this paper. For each TSO (transmission system operator), the applicable schemes of two kinds of step control and four kinds of ramp-rate control with a droop characteristic are included in this research. Furthermore, in order to effectively evaluate the angle stability, the Generators-VSC Interaction Factor (GVIF) index is newly implemented to distinguish the participating generators (PGs) group which reacts to the converter power change. As a result, the transient stabilities of the two power systems are evaluated and the suitable active power control strategies are determined for two TSOs. Simulation studies are performed using the PSS^®E program to analyze the power system transient stability and various active power control schemes of the VSC-HVDC. The results provide useful information indicating that the ramp-rate control shows a more stable characteristic than the step-control for interconnected grids; thus, a converter having a certain ramp-rate slope similar to that of the other generator shows more stable results in several cases. Full article

(This article belongs to the Special Issue HVDC for Grid Services in Electric Power Systems)

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18 pages, 10533 KiB

Open AccessArticle

Investigation into the Water Jet Erosion Efficiency of Hydrate-Bearing Sediments Based on the Arbitrary Lagrangian-Eulerian Method

by Chen Chen, Dongbin Pan, Lin Yang, Han Zhang, Bing Li, Chengcai Jin, Xitong Li, Yong Cheng and Xiuping Zhong

Appl. Sci. 2019, 9(1), 182; https://doi.org/10.3390/app9010182 - 6 Jan 2019

Cited by 29 | Viewed by 3820

Abstract

As an innovative way to exploit marine natural gas hydrates (NGH), the solid fluidization exploitation method is to erode hydrate-bearing sediment (HBS) into fine particles by a water jet and transport the particles to an offshore platform. To investigate the water jet erosion [...] Read more.

As an innovative way to exploit marine natural gas hydrates (NGH), the solid fluidization exploitation method is to erode hydrate-bearing sediment (HBS) into fine particles by a water jet and transport the particles to an offshore platform. To investigate the water jet erosion efficiency of HBS under various work parameters, such as jet velocity, standoff distance, and nozzle diameter, the Arbitrary Lagrangian–Eulerian (ALE) method was adopted to establish numerical models based on the characteristics of HBS in the South China Sea, and orthogonal experiments were performed to optimize the work parameters. The results show that the water jet erosion efficiency of HBS increases with the increase in jet velocity and nozzle diameter, however it decreases with the increase in standoff distance. The jet velocity is the most significant factor for the erosion efficiency and there exists a threshold velocity which describes the minimum jet velocity required to erode HBS. In addition, comprehensive analysis of the results of the orthogonal experiments indicates that, when the jet velocity is 150 m·s⁻¹, the standoff distance is 0.5 cm, and the nozzle diameter is 2.5 mm, the maximum erosion volume can be obtained, which is 6.0329 cm³. This research provides valuable theoretical support for the solid fluidization exploitation of marine NGH. Full article

(This article belongs to the Section Energy Science and Technology)

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14 pages, 2879 KiB

Open AccessReview

Rehabilitative Ultrasound Imaging Evaluation in Physiotherapy: Piloting a Systematic Review

by Samuel Fernández Carnero, José Luis Arias Buria, Juan Nicolás Cuenca Zaldivar, Alejandro Leal Quiñones, Cesar Calvo-Lobo and Carlos Martin Saborido

Appl. Sci. 2019, 9(1), 181; https://doi.org/10.3390/app9010181 - 6 Jan 2019

Cited by 14 | Viewed by 6620

Abstract

Background: Research of ultrasound use in physiotherapy and daily practice has led to its use as an everyday tool. Methods: The aims were: (1) Checking the proposed systematic review protocol methodology; (2) evaluating the evidence from the last five years; and (3) coordinating [...] Read more.

Background: Research of ultrasound use in physiotherapy and daily practice has led to its use as an everyday tool. Methods: The aims were: (1) Checking the proposed systematic review protocol methodology; (2) evaluating the evidence from the last five years; and (3) coordinating the work of the team of reviewers in performing a complete systematic review. Thus, this is a pilot study prior to a full systematic review. The findings in databases related to health sciences with the meta-search engine Discovery EBSCO, Covidence, and Revman were used. Inclusion and exclusion criteria were described for eligibility. Results: Search provided 1029 references regarding the lumbar region on ultrasound scans. Of these, 33 were duplicates. After Covidence, 996 studies were left for screening. A full-text reading brought one randomized clinical trial (RCT). Conclusions: Validity and reliability references were found. The most suitable points were novice versus expert, and ultrasound versus electromyography (EMG) with just one RCT cohort, and observational and case reports. The lines of investigation increasingly endorsed the validity of using ultrasound in physiotherapy. Post-acquisition image analysis could also be a future line of research. Full article

(This article belongs to the Special Issue Ultrasound Technology for Clinical Diagnosis and Decisions Making)

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Appl. Sci., Volume 9, Issue 1 (January-1 2019) – 210 articles

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