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Appl. Sci., Volume 10, Issue 4 (February-2 2020) – 359 articles

Cover Story (view full-size image): Water bamboo (Zizania latifolia) is considered a delicacy in Taiwan. Almost 90% of yield of water bamboo is obtained from Puli township, Nantou. We investigated a light emitting diode (LED) lighting system applied to a water bamboo field during winter season at night, and the results indicated that this lighting system can prevent the stunting of water bamboo leaves and further assist growth. Compared with previous LED systems, in which the LED bulbs were placed directly above water bamboo leaves, our LED lighting system enables easy handling during harvest.View this paper.
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11 pages, 1660 KiB  
Article
Patent Analysis of the Critical Technology Network of Semiconductor Optical Amplifiers
by Shu-Hao Chang
Appl. Sci. 2020, 10(4), 1552; https://doi.org/10.3390/app10041552 - 24 Feb 2020
Cited by 6 | Viewed by 2869
Abstract
With the development of 5G, mobile communication, and optical communication technologies, semiconductor optical amplifiers (SOAs) have become an important research topic. However, most SOA-related studies have focused on a technical discussion or market research but have failed to indicate the critical SOA technologies [...] Read more.
With the development of 5G, mobile communication, and optical communication technologies, semiconductor optical amplifiers (SOAs) have become an important research topic. However, most SOA-related studies have focused on a technical discussion or market research but have failed to indicate the critical SOA technologies and the SOA technology development trends. Therefore, this study analyzes SOA patents and constructs a technology network for SOA patents. The results indicate that the critical SOA technologies are mainly used in lasers, semiconductor lasers, light guides, electromagnetic wave transmission communication other than radio-wave communication, and devices controlling light sources. Among the five critical SOA technologies, lasers (H01S3) account for the highest percentage at 22.21%. Consequently, the critical technologies do not focus on specific technology fields but have characteristics of multiple technology fields. In addition, considerable development has occurred in semiconductor lasers in recent years. Finally, patentee analysis indicates that for SOA technologies, the public sector and academia play relatively weak roles in early technology development or following technology development. However, with the rapid development of mobile communication and optical communication, the government of each country can consider investing additional R&D funds and resources in the future. This study constructs a network model for patent technologies to explore the development tendencies for SOA technologies. This model can be used as a reference for R&D resource management and the promotion of new technologies. Full article
(This article belongs to the Special Issue Applications of Semiconductor Optical Amplifiers II)
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16 pages, 6034 KiB  
Article
An Analytical Model for the Tension-Shear Coupling of Woven Fabrics with Different Weave Patterns under Large Shear Deformation
by Yanchao Wang, Weizhao Zhang, Huaqing Ren, Zhengming Huang, Furong Geng, Yongxiang Li and Zengyu Zhu
Appl. Sci. 2020, 10(4), 1551; https://doi.org/10.3390/app10041551 - 24 Feb 2020
Cited by 8 | Viewed by 3398
Abstract
It is essential to accurately describe the large shear behavior of woven fabrics in the composite preforming process. An analytical model is proposed to describe the shear behavior of fabrics with different weave patterns, in which tension-shear coupling is considered. The coupling is [...] Read more.
It is essential to accurately describe the large shear behavior of woven fabrics in the composite preforming process. An analytical model is proposed to describe the shear behavior of fabrics with different weave patterns, in which tension-shear coupling is considered. The coupling is involved in two parts, the friction between overlapped yarns and the in-plane transverse compression between two parallel yarns. By introducing the concept of inflection points of a yarn, the model is applicable for fabrics with different weave patterns. The analytical model is validated by biaxial tension-shear experiments. A parametric study is conducted to investigate the effects of external load, yarn geometry, and weave structure on the large shear behavior of fabrics. The developed model can reveal the physical mechanism of tension-shear coupling of woven fabrics. Moreover, the model has a high computational efficiency due to its explicit expressions, thus benefiting the material design process. Full article
(This article belongs to the Special Issue Composite Materials in Design Processes)
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32 pages, 2889 KiB  
Article
A Hybrid Double Forecasting System of Short Term Power Load Based on Swarm Intelligence and Nonlinear Integration Mechanism
by Ping Jiang and Ying Nie
Appl. Sci. 2020, 10(4), 1550; https://doi.org/10.3390/app10041550 - 24 Feb 2020
Cited by 7 | Viewed by 2355
Abstract
Accurate and reliable power load forecasting not only takes an important place in management and steady running of smart grid, but also has environmental benefits and economic dividends. Accurate load point forecasting can provide a guarantee for the daily operation of the power [...] Read more.
Accurate and reliable power load forecasting not only takes an important place in management and steady running of smart grid, but also has environmental benefits and economic dividends. Accurate load point forecasting can provide a guarantee for the daily operation of the power grid, and effective interval forecasting can further quantify the uncertainty of power load on this basis to provide dependable and precise load information. However, most of the previous work focuses on the deterministic point prediction of power load and rarely considers the interval prediction of power load, which makes the prediction of power load not comprehensive. In this study, a new double hybrid load forecasting system including point forecasting module and interval forecasting module is developed, which can make up for the shortcomings of incomplete analysis for the existing research. The point forecasting module adopts a nonlinear integration mechanism based on Back Propagation (BP) network optimized by Multi-objective Evolutionary Algorithm based on Decomposition (MOEA/D) to improve the accuracy of point prediction. A fuzzy clustering interval prediction method based on different data feature classification is successfully proposed which provides an effective tool for load uncertainty analysis. The experiment results show that the system not only has a good effect in accurately predicting power load, but also can analyze the uncertainty of the power load, which can be used as an effective technology of power system planning. Full article
(This article belongs to the Special Issue Artificial Neural Networks in Smart Grids)
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12 pages, 1701 KiB  
Article
A Robot Arm and Image-Guided Navigation Assisted Surgical System for Maxillary Repositioning in Orthognathic Surgery: A Phantom Skull-Based Trial
by Jeong Joon Han, Sang-Yoon Woo, Won-Jin Yi and Soon Jung Hwang
Appl. Sci. 2020, 10(4), 1549; https://doi.org/10.3390/app10041549 - 24 Feb 2020
Cited by 1 | Viewed by 3166
Abstract
This study aimed to present a simplified and safe method to reposition the bone segment with easy identification and removing bone interference using a robot arm and image-guided navigation and to assess the accuracy for maxillary orthognathic surgery on phantom skulls. A surgical [...] Read more.
This study aimed to present a simplified and safe method to reposition the bone segment with easy identification and removing bone interference using a robot arm and image-guided navigation and to assess the accuracy for maxillary orthognathic surgery on phantom skulls. A surgical system consists of a robot arm with specialized end-effector, and image-guided navigation including the optical tracking system. The end-effector was designed to reflect the surgical procedures including identification and removal of bone interference and repositioning of the bone segment. To evaluate the handling and accuracy of this system, 10 phantom-based experiments were conducted according to four surgical plans. Mean absolute deviations at the upper central incisor were 0.10 ± 0.15 mm medio-laterally, 0.05 ± 0.07 mm antero-posteriorly, and 0.12 ± 0.15 mm supero-inferiorly. There was no significant difference in deviations between anterior and posterior regions of the maxilla. The mean root mean square deviation was 0.18 ± 0.16 mm, and ranged from 0.05 mm to 0.54 mm. The robot arm and image-guided navigation assisted surgical system would be helpful to manage bone interferences and reposition bone segments with improved accuracy. Though further technological advances are necessary, this study may provide a basis for developing clinically applicable robot assisted system for orthognathic surgery. Full article
(This article belongs to the Section Applied Dentistry and Oral Sciences)
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12 pages, 4596 KiB  
Article
Parallel Load-Bearing and Damping System Design and Test for Satellite Vibration Suppression
by Shenyan Chen, Zihan Yang, Minxiao Ying, Yanwu Zheng, Yanjie Liu and Zhongwen Pan
Appl. Sci. 2020, 10(4), 1548; https://doi.org/10.3390/app10041548 - 24 Feb 2020
Cited by 7 | Viewed by 2811
Abstract
The traditional series-type satellite vibration suppression scheme significantly decreases satellite frequency, which leads to difficulty in controlling the amplitude. In the present work, a new parallel viscous damping scheme is adopted on the Payload Adaptor Fitting (PAF), which aims to integrate a load-bearing [...] Read more.
The traditional series-type satellite vibration suppression scheme significantly decreases satellite frequency, which leads to difficulty in controlling the amplitude. In the present work, a new parallel viscous damping scheme is adopted on the Payload Adaptor Fitting (PAF), which aims to integrate a load-bearing design and vibration reduction. The vibration amplitude and weight are the most important design requirements of the damping system. The Finite Element (FE) model of PAF was established. Through a series of analyses, the appropriate number and coefficient of dampers were determined. The damping force was calculated according to the damping coefficient and the relative velocity between the two ends of the damper. Based on the damping force and the installation dimensions, the damping rod was designed. The force–velocity test was carried out on the damping rod prototype, which showed its performance satisfies the requirements. With the topology optimization and sizing optimization technology, the light-weight supports were designed and manufactured. One damping rod and two supports were assembled as one set of dampers. Eight sets of dampers were installed on the PAF. Vibration tests were conducted on the damping state PAF. The results showed that the proposed system is effective at suppressing vibration and maintaining stiffness simultaneously. Full article
(This article belongs to the Special Issue State-of-the-Art on Vibroacoustics and Sound Radiation Control of Structures)
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15 pages, 23397 KiB  
Article
Comparative Performance Characterization of Mobile AR Frameworks in the Context of AR-Based Grocery Shopping Applications
by Juhwan Lee, Sangwon Hwang, Jisun Lee and Seungwoo Kang
Appl. Sci. 2020, 10(4), 1547; https://doi.org/10.3390/app10041547 - 24 Feb 2020
Cited by 8 | Viewed by 3702
Abstract
A number of Augmented Reality (AR) frameworks are now available and used to support the development of mobile AR applications. In this paper, we measure and compare the recognition performance of the commercial AR frameworks and identify potential issues that can occur in [...] Read more.
A number of Augmented Reality (AR) frameworks are now available and used to support the development of mobile AR applications. In this paper, we measure and compare the recognition performance of the commercial AR frameworks and identify potential issues that can occur in the real application environment. For experiments, we assume a situation in which a consumer purchases food products in a grocery store and consider an application scenario in which AR content related to the products is displayed on a smartphone screen by recognizing such products. We use four performance metrics to compare the performance of the selected AR frameworks, Vuforia, ARCore, and MAXST. Experimental results show that Vuforia is relatively superior to the others. The limitation of the AR frameworks is also identified when they are used in a real grocery store environment. Full article
(This article belongs to the Special Issue Applications of Virtual, Augmented, and Mixed Reality)
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15 pages, 1515 KiB  
Article
A Novel P300 Classification Algorithm Based on a Principal Component Analysis-Convolutional Neural Network
by Feng Li, Xiaoyu Li, Fei Wang, Dengyong Zhang, Yi Xia and Fan He
Appl. Sci. 2020, 10(4), 1546; https://doi.org/10.3390/app10041546 - 24 Feb 2020
Cited by 23 | Viewed by 3581
Abstract
Aiming at enhancing the classification accuracy of P300 Electroencephalogram signals in a non-invasive brain–computer interface system, a novel P300 electroencephalogram signals classification algorithm is proposed which is based on improved convolutional neural network. In the data preprocessing part, the proposed P300 classification algorithm [...] Read more.
Aiming at enhancing the classification accuracy of P300 Electroencephalogram signals in a non-invasive brain–computer interface system, a novel P300 electroencephalogram signals classification algorithm is proposed which is based on improved convolutional neural network. In the data preprocessing part, the proposed P300 classification algorithm used the Principal Component Analysis algorithm to not only remove the noise and artifacts in the data, but also increase the data processing speed. Furthermore, the proposed P300 classification algorithm employed the parallel convolution method to improve the traditional convolutional neural network framework, which can increase the network depth and improve the network’s ability to classify P300 electroencephalogram signals. The proposed algorithm was evaluated by two datasets (the dataset from the competition and the dataset from the laboratory). The results show that, in the dataset I, the proposed P300 classification algorithm could obtain accuracy rates higher than 95%, and achieve one of the best performances in four classification algorithms, while, in the dataset II, the proposed P300 classification algorithm can get accuracy rates higher than 90%, and is superior to the other three algorithms in all ten subjects. These demonstrated the effectiveness of the proposed algorithm. The proposed classification algorithm can be applied in the actual brain–computer interface systems to help people with disability in the daily lives. Full article
(This article belongs to the Special Issue Advanced Biometrics with Deep Learning)
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23 pages, 10430 KiB  
Article
Mechanical Properties of Concrete Pipes with Pre-Existing Cracks
by Zongyuan Zhang, Hongyuan Fang, Bin Li and Fuming Wang
Appl. Sci. 2020, 10(4), 1545; https://doi.org/10.3390/app10041545 - 24 Feb 2020
Cited by 8 | Viewed by 6127
Abstract
Concrete pipes are the most widely used municipal drainage pipes in China. When concrete pipes fall into years of disrepair, numerous problems appear. As one of the most common problems of concrete pipes, cracks impact on the deterioration of mechanical properties of pipes, [...] Read more.
Concrete pipes are the most widely used municipal drainage pipes in China. When concrete pipes fall into years of disrepair, numerous problems appear. As one of the most common problems of concrete pipes, cracks impact on the deterioration of mechanical properties of pipes, which cannot be ignored. In the current work, normal concrete pipes and those with pre-existing cracks are tested on a full scale under an external compressive load. The effects of the length, depth, and location of cracks on the bearing capacity and mechanical properties of the concrete pipes are quantitatively analyzed. Based on the full-scale tests, three-dimensional finite element models of normal and cracked concrete pipes are developed, and the measured results are compared with the data of the finite element analysis. It is clear that the test measurements are in good agreement with the simulation results; the bearing capacity of a concrete pipe is inversely proportional to the length and depth of the crack, and the maximum circumferential strain of the pipe occurs at the location of the crack. The strain of the concrete pipe also reveals three stages of elasticity, plasticity, and failure as the external load rises. Finally, when the load series reaches the limit of the failure load of the concrete pipe with pre-existing cracks, the pipe breaks along the crack position. Full article
(This article belongs to the Special Issue Advances on Structural Engineering)
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16 pages, 4360 KiB  
Article
Deep Learning Entrusted to Fog Nodes (DLEFN) Based Smart Agriculture
by Kyuchang Lee, Bhagya Nathali Silva and Kijun Han
Appl. Sci. 2020, 10(4), 1544; https://doi.org/10.3390/app10041544 - 24 Feb 2020
Cited by 21 | Viewed by 3493
Abstract
Colossal amounts of unstructured multimedia data are generated in the modern Internet of Things (IoT) environment. Nowadays, deep learning (DL) techniques are utilized to extract useful information from the data that are generated constantly. Nevertheless, integrating DL methods with IoT devices is a [...] Read more.
Colossal amounts of unstructured multimedia data are generated in the modern Internet of Things (IoT) environment. Nowadays, deep learning (DL) techniques are utilized to extract useful information from the data that are generated constantly. Nevertheless, integrating DL methods with IoT devices is a challenging issue due to their restricted computational capacity. Although cloud computing solves this issue, it has some problems such as service delay and network congestion. Hence, fog computing has emerged as a breakthrough way to solve the problems of using cloud computing. In this article, we propose a strategy that assigns a portion of the DL layers to fog nodes in a fog-computing-based smart agriculture environment. The proposed deep learning entrusted to fog nodes (DLEFN) algorithm decides the optimal layers of DL model to execute on each fog node, considering their available computing capacity and bandwidth. The DLEFN individually calculates the optimal layers for each fog node with dissimilar computational capacities and bandwidth. In a similar experimental environment, comparison results clearly showed that proposed method accommodated more DL application than other existing assignment methods and utilized resources efficiently while reducing network congestion and processing burden on the cloud. Full article
(This article belongs to the Section Computing and Artificial Intelligence)
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27 pages, 2204 KiB  
Review
Comparative Study of Sound Transmission Losses of Sandwich Composite Double Panel Walls
by Chukwuemeke William Isaac, Marek Pawelczyk and Stanislaw Wrona
Appl. Sci. 2020, 10(4), 1543; https://doi.org/10.3390/app10041543 - 24 Feb 2020
Cited by 36 | Viewed by 8875
Abstract
The increasing motivation behind the recently wide industrial applications of sandwich and composite double panel structures stems from their ability to absorb sounds more effectively. Meticulous selection of the geometrical and material constituents of both the core and panels of these structures can [...] Read more.
The increasing motivation behind the recently wide industrial applications of sandwich and composite double panel structures stems from their ability to absorb sounds more effectively. Meticulous selection of the geometrical and material constituents of both the core and panels of these structures can produce highly desirable properties. A good understanding of their vibro-acoustic response and emission index such as the sound transmission loss (STL) is, therefore, a requisite to producing optimal design. In this study, an overview of recent advances in STL of sandwich and composites double panels is presented. At first, some salient explanation of the various frequency and controlled regions are given. It then critically examines a number of parameter effects on the STL of sandwich and composite structures. Literatures on the numerical, analytical and experimental solutions of STL are systematically presented. Efficient and more reliable optimization problems that maximize the STL and minimize the objective functions capable of degrading the effectiveness of the structure to absorb sounds are also provided. Full article
(This article belongs to the Special Issue Noise Barriers)
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14 pages, 5607 KiB  
Article
Time-Varying Dynamic Analysis of a Helical-Geared Rotor-Bearing System with Three-Dimensional Motion Due to Shaft Deformation
by Ying-Chung Chen
Appl. Sci. 2020, 10(4), 1542; https://doi.org/10.3390/app10041542 - 24 Feb 2020
Cited by 6 | Viewed by 3096
Abstract
The rotordynamics of a helical-geared rotor-bearing system were investigated. A new dynamic model for a helical-geared rotor-bearing system, which takes into account three-dimensional (3-D) motion due to rotating shaft deformation, was proposed. The proposed model considers the time-varying effect, which in other models, [...] Read more.
The rotordynamics of a helical-geared rotor-bearing system were investigated. A new dynamic model for a helical-geared rotor-bearing system, which takes into account three-dimensional (3-D) motion due to rotating shaft deformation, was proposed. The proposed model considers the time-varying effect, which in other models, is considered constant. The system equations of motion were obtained by applying Lagrange’s equation, and the dynamic responses were computed by the fourth-order Runge–Kutta method. The time-varying dynamic responses of the helix angle, transverse pressure angle, gear pair center distance, and total contact ratio were investigated. The numerical results show that the time-varying effect is an important factor in gear vibration analysis and cannot be neglected when the helical geared rotor-bearing system has a lower stiffness. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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15 pages, 1655 KiB  
Article
Evaluation of Machinery Readiness Using Semi-Markov Processes
by Andrzej Świderski, Anna Borucka, Małgorzata Grzelak and Leszek Gil
Appl. Sci. 2020, 10(4), 1541; https://doi.org/10.3390/app10041541 - 24 Feb 2020
Cited by 22 | Viewed by 2920
Abstract
This article uses Markov and semi-Markov models as some of the most popular tools to estimate readiness and reliability. They allow to evaluate of both individual elements as well as entire systems—including production systems—as multi-state structures. To be able to distinguish states with [...] Read more.
This article uses Markov and semi-Markov models as some of the most popular tools to estimate readiness and reliability. They allow to evaluate of both individual elements as well as entire systems—including production systems—as multi-state structures. To be able to distinguish states with varying degrees of technical readiness in complicated and complex objects (systems) allows to determine their individual impact on the tasks performed, as well as on the total reliability. The application of the Markov process requires, for the process dwell times in the individual states, to be random variables of exponential distribution and the fulfilling Markov’s property of the independence of these states. Omitting these assumptions may lead to erroneous results, which was the authors’ intention to show. The article presents a comparison of the results of the examination of the process of non-parametric distribution with an analysis in which its exponential form was (groundlessly) assumed. Significantly different results were obtained. The aim was to draw attention to the inconsistencies obtained and to the importance of a preliminary assessment of the data collected for examination. The diagnostics of the machine readiness operating in the studied production company was additionally performed. This allowed to evaluate its operational potential, especially in the context of solving process optimization problems. Full article
(This article belongs to the Special Issue Design and Management of Manufacturing Systems)
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17 pages, 1386 KiB  
Article
Monolitic Hybrid Transmitter-Receiver Lens for Rotary On-Axis Communications
by René Kirrbach, Michael Faulwaßer, Tobias Schneider, Philipp Meißner, Alexander Noack and Frank Deicke
Appl. Sci. 2020, 10(4), 1540; https://doi.org/10.3390/app10041540 - 24 Feb 2020
Cited by 5 | Viewed by 3058
Abstract
High-speed rotary communication links exhibit high complexity and require challenging assembly tolerances. This article investigates the use of optical wireless communications (OWC) for on-axis rotary communication scenarios. First, OWC is compared with other state-of-the-art technologies. Different realization approaches for bidirectional, full-duplex links are [...] Read more.
High-speed rotary communication links exhibit high complexity and require challenging assembly tolerances. This article investigates the use of optical wireless communications (OWC) for on-axis rotary communication scenarios. First, OWC is compared with other state-of-the-art technologies. Different realization approaches for bidirectional, full-duplex links are discussed. For the most promising approach, a monolithic hybrid transmitter-receiver lens is designed by ray mapping methodology. Ray tracing simulations are used to study the alignment-depended receiver power level and to determine the effect of optical crosstalk. Over a distance of 12.5 m m , the lens achieves an optical power level at the receiver of − 16.2 dBm to − 8.7 dBm even for misalignments up to 3 m m . Full article
(This article belongs to the Special Issue Modern Applications in Optics and Photonics: From Sensing and Analytics to Communication)
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16 pages, 360 KiB  
Article
Memory Efficient Implementation of Modular Multiplication for 32-bit ARM Cortex-M4
by Hwajeong Seo
Appl. Sci. 2020, 10(4), 1539; https://doi.org/10.3390/app10041539 - 24 Feb 2020
Cited by 7 | Viewed by 3766
Abstract
In this paper, we present scalable multi-precision multiplication implementation and scalable multi-precision squaring implementation for 32-bit ARM Cortex-M4 microcontrollers. For efficient computation and scalable functionality, we present optimized Multiplication and ACcumulation (MAC) techniques for the target microcontrollers. In particular, we present the 64-bit [...] Read more.
In this paper, we present scalable multi-precision multiplication implementation and scalable multi-precision squaring implementation for 32-bit ARM Cortex-M4 microcontrollers. For efficient computation and scalable functionality, we present optimized Multiplication and ACcumulation (MAC) techniques for the target microcontrollers. In particular, we present the 64-bit wise MAC operation with the Unsigned Long Multiply with Accumulate Accumulate (UMAAL) instruction. The MAC is used to perform column-wise multiplication/squaring (i.e., product-scanning) with general-purpose registers in an optimal way. Second, the squaring algorithm is further optimized through an efficient doubling routine together with an optimized product-scanning method. Finally, the proposed implementations achieved a very small memory footprint and high scalability to cover algorityms ranging from well-known public key cryptography (i.e., Rivest–Shamir–Adleman (RSA) and Elliptic Curve Cryptography (ECC)) to post-quantum cryptography (i.e., Supersingular Isogeny Key Encapsulation (SIKE)). All SIKE round 2 protocols were evaluated with the proposed modular reduction implementations. The results demonstrate that the scalable implementation can achieve the smallest code size together with a reasonable performance. Full article
(This article belongs to the Special Issue Side Channel Attacks and Countermeasures)
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29 pages, 4614 KiB  
Review
Edge Couplers in Silicon Photonic Integrated Circuits: A Review
by Xin Mu, Sailong Wu, Lirong Cheng and H.Y. Fu
Appl. Sci. 2020, 10(4), 1538; https://doi.org/10.3390/app10041538 - 24 Feb 2020
Cited by 116 | Viewed by 25025
Abstract
Silicon photonics has drawn increasing attention in the past few decades and is a promising key technology for future daily applications due to its various merits including ultra-low cost, high integration density owing to the high refractive index of silicon, and compatibility with [...] Read more.
Silicon photonics has drawn increasing attention in the past few decades and is a promising key technology for future daily applications due to its various merits including ultra-low cost, high integration density owing to the high refractive index of silicon, and compatibility with current semiconductor fabrication process. Optical interconnects is an important issue in silicon photonic integrated circuits for transmitting light, and fiber-to-chip optical interconnects is vital in application scenarios such as data centers and optical transmission systems. There are mainly two categories of fiber-to-chip optical coupling: off-plane coupling and in-plane coupling. Grating couplers work under the former category, while edge couplers function as in-plane coupling. In this paper, we mainly focus on edge couplers in silicon photonic integrated circuits. We deliver an introduction to the research background, operation mechanisms, and design principles of silicon photonic edge couplers. The state-of-the-art of edge couplers is reviewed according to the different structural configurations of the device, while identifying the performance, fabrication feasibility, and applications. In addition, a brief comparison between edge couplers and grating couplers is conducted. Packaging issues are also discussed, and several prospective techniques for further improvements of edge couplers are proposed. Full article
(This article belongs to the Special Issue Advances on New Silicon-Integrating Devices: From the Technology of Silicon to the Technology with Silicon)
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13 pages, 8416 KiB  
Article
Experimental Investigations on the Effects of Fatigue Crack in Urban Metro Welded Bogie Frame
by Wenjing Wang, Jinyi Bai, Shengchuan Wu, Jing Zheng and Pingyu Zhou
Appl. Sci. 2020, 10(4), 1537; https://doi.org/10.3390/app10041537 - 24 Feb 2020
Cited by 23 | Viewed by 3506
Abstract
The welded bogie frame is the critical safety part of the urban metro vehicle. This paper focuses on finding out the factors inducing the fatigue cracks initiated from the positioning block weld toe of metro bogie frame. Fracture morphology and metallographic analysis were [...] Read more.
The welded bogie frame is the critical safety part of the urban metro vehicle. This paper focuses on finding out the factors inducing the fatigue cracks initiated from the positioning block weld toe of metro bogie frame. Fracture morphology and metallographic analysis were conducted to identify the failure modes, and on-track tests about the dynamic stress at the positioning block weld toe and vibration acceleration were performed. The typical signals of dynamic stress and acceleration were analyzed from time and frequency domain. The relationship between wheel polygon, rail corrugation, running speed and dynamic stress in amplitude and frequency are investigated in details. Research results show that the micro cracks induced by welding at the weld toe of positioning block propagate to the spring sleeve under relatively high alternating dynamic stress, which is strongly influenced by the wheel polygon, rail corrugation and the train running speed. Full article
(This article belongs to the Special Issue Fracture and Fatigue Assessments of Structural Components)
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14 pages, 5171 KiB  
Article
A Differential Measurement System for Surface Topography Based on a Modular Design
by Fang Cheng, Jingwu Zou, Hang Su, Yin Wang and Qing Yu
Appl. Sci. 2020, 10(4), 1536; https://doi.org/10.3390/app10041536 - 24 Feb 2020
Cited by 8 | Viewed by 3152
Abstract
In this paper, a novel design of a surface topography measurement system is proposed, to address the challenge of accurate measurement in a relatively large area. This system was able to achieve nanometer-scale accuracy in a measurement range of 100 mm × 100 [...] Read more.
In this paper, a novel design of a surface topography measurement system is proposed, to address the challenge of accurate measurement in a relatively large area. This system was able to achieve nanometer-scale accuracy in a measurement range of 100 mm × 100 mm. The high accuracy in a relatively large area was achieved by implementing two concepts: (1) A static coordinate system was configured to minimize the Abbe errors. (2) A differential measurement configuration was developed by setting up a confocal sensor and a film interferometry module to separate the motion error. In order to accommodate the differential measurement probes from both sides of the central stage and ensure the system rigidity with balanced supports, separate linear guides were introduced in this system. Therefore, the motion Degree of Freedom (DoF) was analyzed in order to address the challenge of an over-constrained mechanism due to multiple kinematic pairs. An optimal configuration and a quick assembly process were proposed accordingly. The experimental results presented in this paper showed that the proposed modular measurement system was able to achieve 10 nm accuracy in measuring the surface roughness and 100 nm accuracy in measuring the step height in the range of 100 mm × 100 mm. In summary, the novel concept of this study is the build of a high-accuracy system with conventional mechanical components. Full article
(This article belongs to the Special Issue Manufacturing Metrology)
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25 pages, 7534 KiB  
Article
Novel Image State Ensemble Decomposition Method for M87 Imaging
by Timothy Ryan Taylor, Chun-Tang Chao and Juing-Shian Chiou
Appl. Sci. 2020, 10(4), 1535; https://doi.org/10.3390/app10041535 - 24 Feb 2020
Cited by 3 | Viewed by 2491
Abstract
This paper proposes a new method of image decomposition with a filtering capability. The image state ensemble decomposition (ISED) method has generative capabilities that work by removing a discrete ensemble of quanta from an image to provide a range of filters and images [...] Read more.
This paper proposes a new method of image decomposition with a filtering capability. The image state ensemble decomposition (ISED) method has generative capabilities that work by removing a discrete ensemble of quanta from an image to provide a range of filters and images for a single red, green, and blue (RGB) input image. This method provides an image enhancement because ISED is a spatial domain filter that transforms or eliminates image regions that may have detrimental effects, such as noise, glare, and image artifacts, and it also improves the aesthetics of the image. ISED was used to generate 126 images from two tagged image file (TIF) images of M87 taken by the Spitzer Space Telescope. Analysis of the images used various full and no-reference quality metrics as well as histograms and color clouds. In most instances, the no-reference quality metrics of the generated images were shown to be superior to those of the two original images. Select ISED images yielded previously unknown galactic structures, reduced glare, and enhanced contrast, with good overall performance. Full article
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19 pages, 805 KiB  
Article
An Overview of the Origins and Effectiveness of Commercial Fitness Equipment and Sectoral Corporate Settings: A Critical Review of Literature
by Silvio Addolorato, Jerónimo García-Fernández, Leonor Gallardo and Jorge García-Unanue
Appl. Sci. 2020, 10(4), 1534; https://doi.org/10.3390/app10041534 - 24 Feb 2020
Cited by 4 | Viewed by 5554
Abstract
Research Question: Fitness equipment is a worldwide ever-growing phenomenon and its usage is nowadays popular both in human routines and academic investigations. Research Methods: This paper is a literature review aiming fitness equipment in relation to all the available findings connected to the [...] Read more.
Research Question: Fitness equipment is a worldwide ever-growing phenomenon and its usage is nowadays popular both in human routines and academic investigations. Research Methods: This paper is a literature review aiming fitness equipment in relation to all the available findings connected to the complete product life-cycle phases. Results and Findings: Manufacturing industries, which are active realities of the sector, have not been a major concern for sport researchers within the production applicability sub-field. Past root hypotheses, the current state of the art and future guideline applications are addressed. Selected articles were categorised chronologically, by journal, by geographic area and, extensively, by content. Five thematic areas were included: (1) historical background, (2) creation stages, (3) product features, (4) innovation paths and (5) sectoral environments and marketing processes. Implications: By means of the provided findings, there is an opportunity to widen approaches to study fitness equipment that could be extended to the sector’s enterprise applications and methods of work. Full article
(This article belongs to the Section Materials Science and Engineering)
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17 pages, 3843 KiB  
Article
Analysis of the Composite Boring Bar Dynamic Characteristics Considering Shear Deformation and Rotational Inertia
by Chunjin Zhang, Yongsheng Ren, Shujuan Ji and Jinfeng Zhang
Appl. Sci. 2020, 10(4), 1533; https://doi.org/10.3390/app10041533 - 24 Feb 2020
Cited by 6 | Viewed by 2803
Abstract
A boring bar is a tool used to install cutters and transfer power during boring. Because the boring bar in a narrow workspace is usually slender, chatter often occurs in the boring process. To improve the chatter stability of the boring bar, researchers [...] Read more.
A boring bar is a tool used to install cutters and transfer power during boring. Because the boring bar in a narrow workspace is usually slender, chatter often occurs in the boring process. To improve the chatter stability of the boring bar, researchers have designed composite material boring bars with high dynamic stiffness to meet the requirements of high-speed boring. However, the effect of the shear deformation and rotational inertia were ignored. In this paper, a model of a composite boring bar considering shear deformation and rotational inertia is established based on the Adomian Modified Decomposition Method (AMDM). The dynamic characteristics, such as the vibration mode shapes, natural frequency, and chatter stability of the composite boring bar considering the shear deformation and rotational inertia, are analyzed comprehensively. The analysis results show that, when the shear deformation and rotational inertia are considered, the composite boring bar can exhibit different vibration mode shapes. Moreover, the natural frequencies and the cutting depth will be reduced. The results are helpful to improve the understanding about dynamic characteristics of the composite boring bar, and to provide guidance for designing of boring bars. Moreover, accurate adjustment of the cutting speed and depth in CNC boring can be based on the analysis results. Full article
(This article belongs to the Special Issue Vibration Control for Machining Vibration)
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15 pages, 14292 KiB  
Article
Numerical Investigations on the Blade Tip Clearance Excitation Forces in an Unshrouded Turbine
by Yang Pan, Qi Yuan, Gongge Huang, Jiawei Gu, Pu Li and Guangyu Zhu
Appl. Sci. 2020, 10(4), 1532; https://doi.org/10.3390/app10041532 - 24 Feb 2020
Cited by 4 | Viewed by 2456
Abstract
The purpose of this study was to investigate the characteristics of the blade tip excitation forces represented as the rotordynamic coefficients (stiffness and damping coefficients) in an unshrouded turbine using the three-dimensional computational fluid dynamic (CFD) numerical method. The blade geometrical parameters were [...] Read more.
The purpose of this study was to investigate the characteristics of the blade tip excitation forces represented as the rotordynamic coefficients (stiffness and damping coefficients) in an unshrouded turbine using the three-dimensional computational fluid dynamic (CFD) numerical method. The blade geometrical parameters were based on a SNECMA transonic experimental rig. The simulations were performed by solving the compressible Reynolds-averaged Navier–Stokes (RANS) equations. The multi-frequency elliptical whirling orbit model and an improved mesh deformation method based on the transient analysis were utilized. The effects of operating conditions on the rotordynamic coefficients and the unsteady flow were also found. The results show that the positive direct stiffness, which confirmed the direct force contribution in the tip excitation forces and the cross-coupling stiffness, were dependent on the whirling frequencies. Damping effects were shown to be negligible. The rotational speed, inlet flow angle, eccentric ratio (ER), and mean tip clearance had impacts on the stiffness, and some effects of these variables on the rotordynamic coefficients were found to be frequency dependent. Additionally, increasing the rotor eccentricity and the mean tip clearance led to the nonuniformity of the circumferential pressure distributions. Full article
(This article belongs to the Special Issue Computational Fluid Mechanics and Heat Transfer)
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18 pages, 11937 KiB  
Article
Body-Part-Aware and Multitask-Aware Single-Image-Based Action Recognition
by Bhishan Bhandari, Geonu Lee and Jungchan Cho
Appl. Sci. 2020, 10(4), 1531; https://doi.org/10.3390/app10041531 - 24 Feb 2020
Cited by 11 | Viewed by 3642
Abstract
Action recognition is an application that, ideally, requires real-time results. We focus on single-image-based action recognition instead of video-based because of improved speed and lower cost of computation. However, a single image contains limited information, which makes single-image-based action recognition a difficult problem. [...] Read more.
Action recognition is an application that, ideally, requires real-time results. We focus on single-image-based action recognition instead of video-based because of improved speed and lower cost of computation. However, a single image contains limited information, which makes single-image-based action recognition a difficult problem. To get an accurate representation of action classes, we propose three feature-stream-based shallow sub-networks (image-based, attention-image-based, and part-image-based feature networks) on the deep pose estimation network in a multitasking manner. Moreover, we design the multitask-aware loss function, so that the proposed method can be adaptively trained with heterogeneous datasets where only human pose annotations or action labels are included (instead of both pose and action information), which makes it easier to apply the proposed approach to new data on behavioral analysis on intelligent systems. In our extensive experiments, we showed that these streams represent complementary information and, hence, the fused representation is robust in distinguishing diverse fine-grained action classes. Unlike other methods, the human pose information was trained using heterogeneous datasets in a multitasking manner; nevertheless, it achieved 91.91% mean average precision on the Stanford 40 Actions Dataset. Moreover, we demonstrated the proposed method can be flexibly applied to multi-labels action recognition problem on the V-COCO Dataset. Full article
(This article belongs to the Special Issue Computing and Artificial Intelligence for Visual Data Analysis)
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3 pages, 155 KiB  
Editorial
Special Issue on Advances in Digital Image Correlation (DIC)
by Jean-Noël Périé and Jean-Charles Passieux
Appl. Sci. 2020, 10(4), 1530; https://doi.org/10.3390/app10041530 - 24 Feb 2020
Cited by 8 | Viewed by 2408
Abstract
Digital Image Correlation (DIC) has become the most popular full field measurement technique in experimental mechanics [...] Full article
(This article belongs to the Special Issue Advances in Digital Image Correlation (DIC))
13 pages, 5754 KiB  
Article
Analysis of the DC Bias Effects on the UHV Autotransformer with Rated Load Based on a Reduced-Scale Model Experiment
by Bing Li, Zezhong Wang, Mingyang Li and Suxin Guo
Appl. Sci. 2020, 10(4), 1529; https://doi.org/10.3390/app10041529 - 24 Feb 2020
Cited by 3 | Viewed by 2857
Abstract
The DC bias of transformers as a result of geomagnetically induced currents (GIC), monopole operation of high voltage direct current (HVDC) transmission and the increasing power electronic devices in the power grid, creates a high magnitude of fundamental and harmonic components in winding [...] Read more.
The DC bias of transformers as a result of geomagnetically induced currents (GIC), monopole operation of high voltage direct current (HVDC) transmission and the increasing power electronic devices in the power grid, creates a high magnitude of fundamental and harmonic components in winding currents, reactive power, and vibro-acoustic noise. For transformers with large capacity, it is very expensive and difficult to carry out an in-depth DC bias effects investigation on a practical equipment, especially for the ultra-high voltage (UHV) transformer. In this paper, a reduced-scale model (RSM) based on the principle of identical saturation degree is proposed, and the equivalent relationship of DC bias current is obtained. Furthermore, the DC bias platform with the RSM is established, experiments have been conducted to analyze the characteristics of the transformer under DC bias. It turns out from the experiments that the current of high voltage side and excitation are less tolerated to the DC bias current, the distortion occurs during the first half of the cycle and peaking at the quarter. Besides, the no-load loss and total harmonic distortion (THD) increase significantly with an increasing DC bias. The results of the characteristics of RSM with load under DC bias may provide great services in protecting and reducing the DC bias effects on the UHV transformer in actual operation. Full article
(This article belongs to the Section Electrical, Electronics and Communications Engineering)
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15 pages, 2244 KiB  
Article
Harmonics Consequences on Drive Systems with Induction Motor
by Horia Gheorghe Beleiu, Virgil Maier, Sorin Gheorghe Pavel, Iulian Birou, Constantin Sorin Pică and Pompei Cosmin Dărab
Appl. Sci. 2020, 10(4), 1528; https://doi.org/10.3390/app10041528 - 24 Feb 2020
Cited by 28 | Viewed by 4504
Abstract
In the case of adjustable drives systems with an induction motor (IM), a harmonic regime is manifested, whose knowledge and analysis are always necessary. However, most studies are focused on specific drive systems, the results of these works being valid only for drive [...] Read more.
In the case of adjustable drives systems with an induction motor (IM), a harmonic regime is manifested, whose knowledge and analysis are always necessary. However, most studies are focused on specific drive systems, the results of these works being valid only for drive systems of the same type. The objective of the present paper was to determine the harmonics consequences not only on the technical characteristics of the IM but also on the power supply as well as on the mechanical drive system. Thus, by initiating a methodology for estimating the consequences of each voltage harmonic separately, the aim was to substantiate a generally applicable method, which allows the evaluation, for any application, of the overall effects of the harmonics. The main feature of the method used in this paper was the consideration of the presence of voltage harmonics in the stator voltage of the IM, of certain frequencies and with certain levels, and the determination of all the electrical and mechanical consequences on the model of the drive system. It has been found that the harmonics of the IM affects the power quality (PQ) of the power supply, having significant influences also on the mechanical part of the drive system. Full article
(This article belongs to the Section Energy Science and Technology)
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26 pages, 8582 KiB  
Article
Consistent Time-to-Failure Tests and Analyses of Adhesive Anchor Systems
by Krešimir Ninčević, Ioannis Boumakis, Stefan Meissl and Roman Wan-Wendner
Appl. Sci. 2020, 10(4), 1527; https://doi.org/10.3390/app10041527 - 24 Feb 2020
Cited by 13 | Viewed by 2949
Abstract
Motivated by tunnel accidents in the recent past, several investigations into the sustained load behavior of adhesive anchors have been initiated. Nevertheless, the reliable lifetime prediction of bonded anchor systems based on a relatively short testing period still represents an unsolved challenge due [...] Read more.
Motivated by tunnel accidents in the recent past, several investigations into the sustained load behavior of adhesive anchors have been initiated. Nevertheless, the reliable lifetime prediction of bonded anchor systems based on a relatively short testing period still represents an unsolved challenge due to the complex nonlinear viscoelastic behavior of concrete and adhesives alike. This contribution summarizes the results of a comprehensive experimental investigation and systematically carried out time-to-failure analysis performed on bonded anchors under sustained tensile load. Two different adhesive materials that find widespread application in the building industry were used, one epoxy and one vinylester based. Performed experiments include full material characterizations of concrete and the adhesives, bonded anchor pull-out tests at different loading rates, and time-to-failure sustained load tests. All anchor tests are performed in a confined configuration with close support. After a thorough review of available experimental data and analysis methods in the literature, the experimental data are presented with the main goal to (i) provide guidance for the analysis of load versus time-to-failure test data, and (ii) to derive a set of recommendations for efficient time-to-failure tests having in mind the needs associated with different analysis techniques. Finally, a new approach based on a sigmoid function, previously used only for concrete, is for the first time applied to bonded anchors systems and compared to the established regression models. Full article
(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)
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14 pages, 3149 KiB  
Article
Comparative Study of the Use of Different Sizes of an Ergonomic Instrument Handle for Laparoscopic Surgery
by Juan A. Sánchez-Margallo, Alfonso González González, Lorenzo García Moruno, J. Carlos Gómez-Blanco, J. Blas Pagador and Francisco M. Sánchez-Margallo
Appl. Sci. 2020, 10(4), 1526; https://doi.org/10.3390/app10041526 - 24 Feb 2020
Cited by 11 | Viewed by 5648
Abstract
Previous studies have shown that the handle design of laparoscopic instruments is crucial to surgical performance and surgeon’s ergonomics. In this study, four different sizes of an ergonomic laparoscopic handle design were tested in a blind and randomized fashion with twelve surgeons. They [...] Read more.
Previous studies have shown that the handle design of laparoscopic instruments is crucial to surgical performance and surgeon’s ergonomics. In this study, four different sizes of an ergonomic laparoscopic handle design were tested in a blind and randomized fashion with twelve surgeons. They performed three laparoscopic tasks in order to analyze the influence of handle size. Execution time, wrist posture, and finger and palm pressure were evaluated during the performance of each task. The results show a significant reduction in the time required to complete the eye-manual coordination task using the appropriate handle. The incorrectly sized handle resulted in a rise in palm pressure and a reduction in the force exerted by the thumb during the transfer task. In the hand-eye coordination task, the use of the right handle size led to an increase in middle finger pressure. In general, surgeons had an ergonomically adequate wrist flexion in all tasks and an acceptable radio-ulnar deviation during the transfer task using the ergonomic instrument handle. Surgeons found it comfortable the use of the ergonomic handle. Therefore, the use of an appropriately sized instrument handle allows surgeons to improve ergonomics and surgical performance during the laparoscopic practice. Full article
(This article belongs to the Special Issue Engineering for Surgery)
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23 pages, 886 KiB  
Article
Deep Learning for EEG-Based Preference Classification in Neuromarketing
by Mashael Aldayel, Mourad Ykhlef and Abeer Al-Nafjan
Appl. Sci. 2020, 10(4), 1525; https://doi.org/10.3390/app10041525 - 24 Feb 2020
Cited by 96 | Viewed by 13938
Abstract
The traditional marketing methodologies (e.g., television commercials and newspaper advertisements) may be unsuccessful at selling products because they do not robustly stimulate the consumers to purchase a particular product. Such conventional marketing methods attempt to determine the attitude of the consumers toward a [...] Read more.
The traditional marketing methodologies (e.g., television commercials and newspaper advertisements) may be unsuccessful at selling products because they do not robustly stimulate the consumers to purchase a particular product. Such conventional marketing methods attempt to determine the attitude of the consumers toward a product, which may not represent the real behavior at the point of purchase. It is likely that the marketers misunderstand the consumer behavior because the predicted attitude does not always reflect the real purchasing behaviors of the consumers. This research study was aimed at bridging the gap between traditional market research, which relies on explicit consumer responses, and neuromarketing research, which reflects the implicit consumer responses. The EEG-based preference recognition in neuromarketing was extensively reviewed. Another gap in neuromarketing research is the lack of extensive data-mining approaches for the prediction and classification of the consumer preferences. Therefore, in this work, a deep-learning approach is adopted to detect the consumer preferences by using EEG signals from the DEAP dataset by considering the power spectral density and valence features. The results demonstrated that, although the proposed deep-learning exhibits a higher accuracy, recall, and precision compared with the k-nearest neighbor and support vector machine algorithms, random forest reaches similar results to deep learning on the same dataset. Full article
(This article belongs to the Special Issue Ubiquitous Technologies for Emotion Recognition)
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6 pages, 183 KiB  
Editorial
Special Issue “Plasma Technology for Biomedical Applications”
by Emilio Martines
Appl. Sci. 2020, 10(4), 1524; https://doi.org/10.3390/app10041524 - 24 Feb 2020
Cited by 5 | Viewed by 2468
Abstract
The use of plasmas for biomedical applications in encountering a growing interest, especially in the framework of so-called “plasma medicine”, which aims at exploiting the action of low-power, atmospheric pressure plasmas for therapeutic purposes [...] Full article
(This article belongs to the Special Issue Plasma Technology for Biomedical Applications)
14 pages, 2981 KiB  
Article
Experimental and Numerical Investigations on the Local Direct Leakage Process of Rotary Regenerative Air Preheater
by Hua Zhu, Dechao Li, Henglin Pu, Limin Wang, Yang He, Yufan Bu and Defu Che
Appl. Sci. 2020, 10(4), 1523; https://doi.org/10.3390/app10041523 - 23 Feb 2020
Cited by 7 | Viewed by 2785
Abstract
An inherent defect of the operating rotary air preheaters (RAPH) is known as leakage, which seriously hinders the efficient and safe operation of RAPH. It is significant for the estimation of the direct leakage to determine the effects of different structure parameters of [...] Read more.
An inherent defect of the operating rotary air preheaters (RAPH) is known as leakage, which seriously hinders the efficient and safe operation of RAPH. It is significant for the estimation of the direct leakage to determine the effects of different structure parameters of sealing sheets and different operation parameters of a RAPH. A direct leakage set-up was built and a three-dimensional numerical model was established to explore the local direct air leaking process of rotary regenerative air preheater and study the effects of geometrical and operational parameters on the leakage. The numerical simulation using the transition k-kl-ω turbulence model was verified by the experimental results. The results show that the local direct air leakage mainly depends on the total pressure difference between the two sides of the seal instead of the one-side pressure. The air leakage can be significantly reduced by narrowing the leakage gap. The increase in the number of sealing sheets can reduce the air leakage own to the increase in the leakage resistance. The increase in the spacing between the adjacent sealing sheets can enlarge the recirculation zone and increase the energy loss of mainstream, greatly reducing the local direct air leakage. Due to the different size recirculation zone formation and streamline curvature induced by sealing sheet, the effect of bending angle on the direct air leakage varies. To obtain lower leakage rate, it is recommended for the rotor of tri-sectional air preheater to pass through flue gas section, secondary-air section, and primary-air section in sequence. Full article
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