Applied Sciences

16 pages, 474 KiB

Open AccessArticle

A Novel Approach to Fixed-Time Stabilization for a Class of Uncertain Second-Order Nonlinear Systems

by Chih-Chiang Chen and Guan-Shiun Chen

Appl. Sci. 2020, 10(1), 424; https://doi.org/10.3390/app10010424 - 6 Jan 2020

Cited by 4 | Viewed by 5248

This paper is concerned with the problem of fixed-time stabilization for a class of uncertain second-order nonlinear systems. By delicately introducing extra manipulations in the feedback domination and revamping the technique of adding a power integrator, a new approach is developed, by which [...] Read more.

This paper is concerned with the problem of fixed-time stabilization for a class of uncertain second-order nonlinear systems. By delicately introducing extra manipulations in the feedback domination and revamping the technique of adding a power integrator, a new approach is developed, by which a state feedback controller, together with a suitable Lyapunov function, which is critical for verifying fixed-time convergence, can be explicitly organized to render the closed-loop system fixed-time stable. The major novelty of this paper is attributed to a subtle strategy that offers a distinct perspective in controller design as well as stability analysis in the problem of fixed-time stabilization for nonlinear systems. Finally, the proposed approach is applied to the attitude stabilization of a spacecraft to demonstrate its merits and effectiveness. Full article

(This article belongs to the Special Issue Ships and Marine Structures)

► Show Figures

Figure 1

8 pages, 1225 KiB

Open AccessArticle

Mechanism of Corrosion in Porcelain Insulators and Its Effect on the Lifetime

by Taeyong Kim, Youn-Jung Lee, Simpy Sanyal, Jung-Wook Woo, In-Hyuk Choi and Junsin Yi

Appl. Sci. 2020, 10(1), 423; https://doi.org/10.3390/app10010423 - 6 Jan 2020

Cited by 14 | Viewed by 5852

Abstract

Porcelain insulators should be exchanged periodically, but their lifetime is not clearly defined. One factor that affects service life is corrosion occurring at the pin and cap—each of which is made of iron with a zinc coating. A number of porcelain insulators used [...] Read more.

Porcelain insulators should be exchanged periodically, but their lifetime is not clearly defined. One factor that affects service life is corrosion occurring at the pin and cap—each of which is made of iron with a zinc coating. A number of porcelain insulators used for different lengths of time in different locations are gathered, and the corrosion mechanisms of the cap and pin are investigated. The corrosion mechanism of the cap is mainly galvanic corrosion while that of the pin is primarily electrolytic and crevice corrosion as well as galvanic corrosion. Although time is an important factor in corrosion, it is found that corrosion is more influenced by geographical factors. Since the amount of acid rain and sea salt—each of which causes rapid rusting—is dependent on geographical factors, the location of where porcelain insulators are installed should be considered when predicting their lifetime. Theoretically, if there is only galvanic corrosion occurring, the expected lifetime is 56 years in an industrial area when the zinc coating has a thickness of 75 µm. Previous articles dealing with aging have predicted the maximum lifetime of porcelain insulators used in Korea to be approximately 30 years. To prolong the lifetime of porcelain insulators, further study is required in which the use of zinc alternatives, or waterproof coatings (in addition to the zinc coating), could be examined. Full article

► Show Figures

Figure 1

17 pages, 6793 KiB

Open AccessArticle

Synthesis of Benzoxazine-Based N-Doped Mesoporous Carbons as High-Performance Electrode Materials

by Haihan Zhang, Li Xu and Guoji Liu

Appl. Sci. 2020, 10(1), 422; https://doi.org/10.3390/app10010422 - 6 Jan 2020

Cited by 18 | Viewed by 4591

Abstract

In this work, nitrogen-doped carbon materials (NCMs) were prepared using aniline-phenol benzoxazine (BOZ) or aniline-cardanol benzoxazine as the carbon precursor and SBA-15 as the hard template. The effects of the carbonization temperature (700, 800, and 900 °C) and different nitrogen contents on the [...] Read more.

In this work, nitrogen-doped carbon materials (NCMs) were prepared using aniline-phenol benzoxazine (BOZ) or aniline-cardanol benzoxazine as the carbon precursor and SBA-15 as the hard template. The effects of the carbonization temperature (700, 800, and 900 °C) and different nitrogen contents on the electrochemical properties of carbon materials were investigated. The samples synthesized using aniline-phenol benzoxazine as precursors and treated at 900 °C (NCM-900) exhibited an excellent electrochemical performance. The specific capacitance was 460 F/g at a current density of 0.25 A/g and the cycle stability was excellent (96.1% retention rate of the initial capacitance after 2000 cycles) in a 0.5 M H₂SO₄ electrolyte with a three-electrode system. Furthermore, NCM-900 also exhibited a high specific capacitance, comparable energy/power densities, and excellent cycling stability using a symmetrical electrode system. The characterization of the morphology and structure of the materials suggests it possessed an ordered mesoporous structure and a large specific surface area. NCM-900 could thus be considered a promising electrode material for supercapacitors. Full article

(This article belongs to the Special Issue Advance Electrode Materials for Perovskite Solar Cells and Electrochemical Supercapacitor)

► Show Figures

Figure 1

12 pages, 3122 KiB

Open AccessArticle

A Deep Learning Model for Estimation of Patients with Undiagnosed Diabetes

by Kwang Sun Ryu, Sang Won Lee, Erdenebileg Batbaatar, Jae Wook Lee, Kui Son Choi and Hyo Soung Cha

Appl. Sci. 2020, 10(1), 421; https://doi.org/10.3390/app10010421 - 6 Jan 2020

Cited by 24 | Viewed by 6003

Abstract

A screening model for undiagnosed diabetes mellitus (DM) is important for early medical care. Insufficient research has been carried out developing a screening model for undiagnosed DM using machine learning techniques. Thus, the primary objective of this study was to develop a screening [...] Read more.

A screening model for undiagnosed diabetes mellitus (DM) is important for early medical care. Insufficient research has been carried out developing a screening model for undiagnosed DM using machine learning techniques. Thus, the primary objective of this study was to develop a screening model for patients with undiagnosed DM using a deep neural network. We conducted a cross-sectional study using data from the Korean National Health and Nutrition Examination Survey (KNHANES) 2013–2016. A total of 11,456 participants were selected, excluding those with diagnosed DM, an age < 20 years, or missing data. KNHANES 2013–2015 was used as a training dataset and analyzed to develop a deep learning model (DLM) for undiagnosed DM. The DLM was evaluated with 4444 participants who were surveyed in the 2016 KNHANES. The DLM was constructed using seven non-invasive variables (NIV): age, waist circumference, body mass index, gender, smoking status, hypertension, and family history of diabetes. The model showed an appropriate performance (area under curve (AUC): 80.11) compared with existing previous screening models. The DLM developed in this study for patients with undiagnosed diabetes could contribute to early medical care. Full article

(This article belongs to the Special Issue Data Technology Applications in Life, Diseases, and Health)

► Show Figures

Figure 1

9 pages, 4355 KiB

Open AccessArticle

Structural Colors Based on Amorphous Arrays Comprised Solely of Silica Particles

by Dae-San Choi, Ju-Hwan Choi and Chang-Yull Lee

Appl. Sci. 2020, 10(1), 420; https://doi.org/10.3390/app10010420 - 6 Jan 2020

Cited by 9 | Viewed by 4517

Abstract

In this study, structural colors were fabricated by producing an amorphous array with atypical silica particles. The colors were controlled by an array of silica particles with different sizes. In previous research, the process required inducement of the amorphous array, which was complex. [...] Read more.

In this study, structural colors were fabricated by producing an amorphous array with atypical silica particles. The colors were controlled by an array of silica particles with different sizes. In previous research, the process required inducement of the amorphous array, which was complex. Meanwhile, in this paper, we proposed a simple one-step process. First, spherical silica nanoparticles were synthesized using the sol-gel process of the Stöber method. Atypical silica particles that induced an amorphous array were produced by adding a small amount of phenol-formaldehyde resin. Subsequently, the colloidal silica was converted to a powder using a convection oven. The characteristics of the synthesized silica particles were confirmed using a scanning electron microscope (SEM). All the synthesized silica powders obtained structural colors. Finally, the silica powders were dispersed in deionized (DI) water and coated on a glass slide. We confirmed that the silica particles showed different structural colors depending on the size of the particles. We also found that the color was highly independent of the viewing angle. Full article

(This article belongs to the Special Issue Selected Papers from the ICMR 2019)

► Show Figures

Figure 1

24 pages, 10040 KiB

Open AccessArticle

Laboratory Evaluation of the Permeability Durability of Utilization of Oil Shale Waste as Fine Aggregate in Open Grade Friction Course in Seasonal Frozen Regions

by Wei Guo, Xuedong Guo, Xing Chen, Yingsong Li, Zhun Li, Yin An and Wenting Dai

Appl. Sci. 2020, 10(1), 419; https://doi.org/10.3390/app10010419 - 6 Jan 2020

Cited by 2 | Viewed by 2776

Abstract

Open graded friction course (OGFC), as a highly permeable mixture, has the characteristics of good friction and splash-and-spray reduction during rainstorms. The limitations of the use of such mixtures include the fact that they are affected by poor durability, including strength and permeability [...] Read more.

Open graded friction course (OGFC), as a highly permeable mixture, has the characteristics of good friction and splash-and-spray reduction during rainstorms. The limitations of the use of such mixtures include the fact that they are affected by poor durability, including strength and permeability durability issues. In a previous study, oil shale waste, as a fine aggregate in the mixture (with a particle size less than 4.75 mm), could effectively improve the overall properties of OGFC, but the permeability durability was not clear. Thus, a comprehensive investigation of the permeability durability of oil shale waste as a fine aggregate is essential to achieving a better understanding in order to promote its engineering application. In this paper, the long-term permeability when using oil shale waste as a fine aggregate in OGFC was systematically investigated based on a self-developed laboratory physical clogging procedure. The test results illustrated the effectiveness of the utilization of oil shale waste as a fine aggregate in terms of permeability durability. A comprehensive index of the clogging coefficient containing mass, porosity and permeability coefficient was proposed based on gray relation entropy theory, the physical clogging model of COF-OGFC (OGFC containing oil shale waste filler) was established and the clogging speed of COF-OGFC was quantified based on the Mistcherlich growth model. The analysis showed that there is an essential difference in the clogging behavior of permeable pavement in the spring and summer. The maximum clogging degree of the permeable pavement in summer is about 40% higher than that in spring, while the clogging rate is much lower than in the spring, at only about 14%, which indicates that the clogging behavior of permeable asphalt pavement in spring is mostly in the rapid clogging mode, and that in summer is mostly in a slow deposition clogging mode. Moreover, the test results showed that the most important influences on the spring clogging behavior of COF-OGFC were the sandy clogging materials and particle sizes ranging from 150 μm to 1180 μm, which can be used to provide a reference for the design of anti-slip sand. Full article

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

► Show Figures

Figure 1

20 pages, 5093 KiB

Open AccessArticle

Object Detection Based on Multiple Information Fusion Net

by Yanni Zhang, Jun Kong, Miao Qi, Yunpeng Liu, Jianzhong Wang and Yinghua Lu

Appl. Sci. 2020, 10(1), 418; https://doi.org/10.3390/app10010418 - 6 Jan 2020

Cited by 15 | Viewed by 3961

Abstract

Object detection has been playing a significant role in computer vision for a long time, but it is still full of challenges. In this paper, we propose a novel object detection framework based on relationship among different objects and the scene-level information of [...] Read more.

Object detection has been playing a significant role in computer vision for a long time, but it is still full of challenges. In this paper, we propose a novel object detection framework based on relationship among different objects and the scene-level information of the whole image to cope with the problem that some strongly correlated objects are difficult to be recognized. Our motivation is to enrich the semantics of object detection feature by a scene-level information branch and a relationship branch. There are three important changes of our framework over traditional detection methods: representation of relationship, scene-level information as the prior knowledge and the fusion of the above two information. Extensive experiments are carried out on PASCAL VOC and MS COCO databases. The experimental results show that the detection performance can be improved by introducing relationship and scene-level information, and our proposed model achieve better performance than several classical and state-of-the-art methods. Full article

(This article belongs to the Section Computing and Artificial Intelligence)

► Show Figures

Figure 1

15 pages, 2075 KiB

Open AccessArticle

Probiotic Characteristics and Antifungal Activity of Lactobacillus plantarum and Its Impact on Fermentation of Italian Ryegrass at Low Moisture

by Karnan Muthusamy, Ilavenil Soundharrajan, Srigopalram Srisesharam, Dahye Kim, Palaniselvam Kuppusamy, Kyung Dong Lee and Ki Choon Choi

Appl. Sci. 2020, 10(1), 417; https://doi.org/10.3390/app10010417 - 6 Jan 2020

Cited by 18 | Viewed by 6362

Abstract

The study aimed to investigate probiotic characteristics, and low moisture silage fermentation capability of selected lactic acid bacteria (LAB) isolated from Alfalfa (Medicago sativa L). Morphological and physiological properties, carbohydrates fermentation, enzymes, and organic acids production, anti-fungal activity, antibiotic sensitivity patterns, and [...] Read more.

The study aimed to investigate probiotic characteristics, and low moisture silage fermentation capability of selected lactic acid bacteria (LAB) isolated from Alfalfa (Medicago sativa L). Morphological and physiological properties, carbohydrates fermentation, enzymes, and organic acids production, anti-fungal activity, antibiotic sensitivity patterns, and probiotic characteristics (acidic and bile salt tolerances, hydrophobicity and aggregations natures) of LAB were examined. 16SrRNA sequencing was carried out to identify isolated strains. The identified strains Lactobacillus plantarum (KCC-37) and Lactobacillus plantarum (KCC-38) showed intense antifungal activity, survival tolerant in acidic and bile salt environments, cell surface and auto aggregations ability, enzymes and organic acids productions. At ensiled condition, KCC-37 and KCC-38 enhanced acidification of Italian ryegrass silages by producing a higher amount of lactic acid, a key acid for indicating silage quality with less extent to acetic acid and succinic acid at low moisture level than non-inoculated silages. Notably, the addition of mixed strains of KCC-37 and KCC-38 more potentially enhanced acidification of silage and organic acid productions than the single-culture inoculation. The overall data suggested that these strains could be used as an additive for improving the quality of the fermentation process in low moisture silage with significant probiotic characteristics. Full article

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

► Show Figures

Figure 1

12 pages, 1585 KiB

Open AccessFeature PaperArticle

Interface Crack Approaching a Three-Material Joint

by Jelena M. Djoković, Ružica R. Nikolić, Robert Ulewicz and Branislav Hadzima

Appl. Sci. 2020, 10(1), 416; https://doi.org/10.3390/app10010416 - 6 Jan 2020

Cited by 4 | Viewed by 2992

Abstract

The problem of an interface crack that approaches a three-material joint with two interfaces is analyzed in this paper. Two possible cases are considered: the crack that lies at the interface between materials A and B, approaching the joint of materials A, B, [...] Read more.

The problem of an interface crack that approaches a three-material joint with two interfaces is analyzed in this paper. Two possible cases are considered: the crack that lies at the interface between materials A and B, approaching the joint of materials A, B, and C, deflects into the interface between materials A and C or into the interface between materials B and C. Analysis is performed within restrictions imposed by the linear elastic fracture mechanics (LEFM), linear elastic behavior of materials, and the small plastic zone around the crack tip, based on the crack deflection criterion proposed by He and Hutchinson. That criterion is applied in this paper to a joint of the three homogeneous isotropic materials. The energy release rates for the crack deflection into one interface or the other are compared to each other, and, based on this comparison, a conclusion is drawn as to which of the two interfaces the crack would deflect. If the value of the ratio of the energy release rates G_BC/G_AC is greater than the ratio of the corresponding fracture toughnesses of the two interfaces, the crack will deflect into the BC interface. If this ratio is smaller than the ratio of the corresponding fracture toughnesses, the crack will deflect into the AC interface. Knowing the ratio of energy release rates for deflection into one interface or the other can be used for designing the interface, namely for prediction of the direction of further crack propagation. Full article

(This article belongs to the Special Issue Fatigue Fractures and Simulations of Structural Materials and Engineering Structures)

► Show Figures

Figure 1

15 pages, 2941 KiB

Open AccessArticle

Data-Driven Design Solution of a Mismatch Problem between the Specifications of the Multi-Function Console in a Jangbogo Class Submarine and the Anthropometric Dimensions of South Koreans Users

by Jihwan Lee, Namwoo Cho, Myung Hwan Yun and Yushin Lee

Appl. Sci. 2020, 10(1), 415; https://doi.org/10.3390/app10010415 - 6 Jan 2020

Cited by 5 | Viewed by 4316

Abstract

The naval multi-function console provides various types of information to the operator. It is equipment that is key for submarine navigation, and fatal human errors can occur due to the mismatch between the console specifications and the operator’s body size. This study proposes [...] Read more.

The naval multi-function console provides various types of information to the operator. It is equipment that is key for submarine navigation, and fatal human errors can occur due to the mismatch between the console specifications and the operator’s body size. This study proposes a method for deriving console specifications suitable for the body size of Korean users. The seat height, seat width, seat depth, upper edge of backrest, and worktable height were selected as the target design variables. Using six anthropometric dimensions, a mismatch equation for each target design variable was developed. Anthropometric measures of 2027 Korean males were obtained, and the optimal specifications of the console were derived via an algorithmic approach. As a result, the match rate, considering all the target design variables, was improved from 2.57% to 76.96%. In previous studies and standards, the optimal console specifications were suggested based on the anthropometric data of a specific percentile of users, and it was impossible to quantitatively confirm the suitability of the console design for the target users. However, the method used in this study calculated the match rate using the mismatch equation devised for comfortable use of the console and a large amount of anthropometric data that represented the user population, and therefore the improvement effect of the recommended specification can be directly identified when compared to the current specifications. Moreover, the methodology and results of this study could be used for deciding the specifications of multi-function consoles in several fields, including nuclear power plants or disaster situation rooms. Full article

(This article belongs to the Special Issue Computer-Aided Manufacturing and Design)

► Show Figures

Figure 1

21 pages, 6489 KiB

Open AccessArticle

Crosslinked Facilitated Transport Membranes Based on Carboxymethylated NFC and Amine-Based Fixed Carriers for Carbon Capture, Utilization, and Storage Applications

by Benjamin Dhuiège, Elsa Lasseuguette, Marie-Christine Brochier-Salon, Maria-Chiara Ferrari and Karim Missoum

Appl. Sci. 2020, 10(1), 414; https://doi.org/10.3390/app10010414 - 6 Jan 2020

Cited by 8 | Viewed by 4194

Abstract

Herein, we report the performances of crosslinked facilitated transport membranes based on carboxymethylated nanofibrils of cellulose (cmNFC) and polyvinylamine (PVAm) with the use of 3-(2-Aminoethylamino) propyltrimethoxysilane (AEAPTMS) as second fixed carrier for CO₂ selectivity and permeability. The grafting of AEAPTMS on cmNFC [...] Read more.

Herein, we report the performances of crosslinked facilitated transport membranes based on carboxymethylated nanofibrils of cellulose (cmNFC) and polyvinylamine (PVAm) with the use of 3-(2-Aminoethylamino) propyltrimethoxysilane (AEAPTMS) as second fixed carrier for CO₂ selectivity and permeability. The grafting of AEAPTMS on cmNFC was optimized by following the hydrolysis/condensation kinetics by ²⁹Si Nuclear Magnetic Resonance (NMR) analyses and two different strategies of the process of membrane production were investigated. In optimized conditions, around 25% of the -COOH functions from cmNFC have crosslinked with PVAm. The crosslinked membranes were less sensitive to liquid water and the crystallinity of PVAm was tuned by the conditions of the membrane elaboration. In both processes, CO₂ selectivity and permeability were enhanced especially at high water vapor concentration by the use of PVAm and AEAPTMS suggesting the existence of a facilitation effect due to amine-CO₂ interaction, while the mechanical integrity of the swollen membranes remained intact. Full article

(This article belongs to the Special Issue Preparation, Characterization and Modelling of Advanced Membranes)

► Show Figures

Figure 1

15 pages, 1023 KiB

Open AccessArticle

An Automated Refactoring Approach to Improve IoT Software Quality

by Yang Zhang, Shuai Shao, Minghan Ji, Jing Qiu, Zhihong Tian, Xiaojiang Du and Mohsen Guizani

Appl. Sci. 2020, 10(1), 413; https://doi.org/10.3390/app10010413 - 6 Jan 2020

Cited by 5 | Viewed by 3470

Abstract

Internet of Things (IoT) software should provide good support for IoT devices as IoT devices are growing in quantity and complexity. Communication between IoT devices is largely realized in a concurrent way. How to ensure the correctness of concurrent access becomes a big [...] Read more.

Internet of Things (IoT) software should provide good support for IoT devices as IoT devices are growing in quantity and complexity. Communication between IoT devices is largely realized in a concurrent way. How to ensure the correctness of concurrent access becomes a big challenge to IoT software development. This paper proposes a general refactoring framework for fine-grained read–write locking and implements an automatic refactoring tool to help developers convert built-in monitors into fine-grained ReentrantReadWriteLocks. Several program analysis techniques, such as visitor pattern analysis, alias analysis, and side-effect analysis, are used to assist with refactoring. Our tool is tested by several real-world applications including HSQLDB, Cassandra, JGroups, Freedomotic, and MINA. A total of 1072 built-in monitors are refactored into ReentrantReadWriteLocks. The experiments revealed that our tool can help developers with refactoring for ReentrantReadWriteLocks and save their time and energy. Full article

(This article belongs to the Special Issue Cognitive Computing with Big Data System over Secure Internet of Things )

► Show Figures

Figure 1

18 pages, 7238 KiB

Open AccessArticle

A Bio-Inspired Flapping Wing Rotor of Variant Frequency Driven by Ultrasonic Motor

by Si Chen, Le Wang, Shijun Guo, Chunsheng Zhao and Mingbo Tong

Appl. Sci. 2020, 10(1), 412; https://doi.org/10.3390/app10010412 - 6 Jan 2020

Cited by 19 | Viewed by 5466

Abstract

By combining the flapping and rotary motion, a bio-inspired flapping wing rotor (FWR) is a unique kinematics of motion. It can produce a significantly greater aerodynamic lift and efficiency than mimicking the insect wings in a vertical take-off and landing (VTOL). To produce [...] Read more.

By combining the flapping and rotary motion, a bio-inspired flapping wing rotor (FWR) is a unique kinematics of motion. It can produce a significantly greater aerodynamic lift and efficiency than mimicking the insect wings in a vertical take-off and landing (VTOL). To produce the same lift, the FWR’s flapping frequency, twist angle, and self-propelling rotational speed is significantly smaller than the insect-like flapping wings and rotors. Like its opponents, however, the effect of variant flapping frequency (VFF) of a FWR, during a flapping cycle on its aerodynamic characteristics and efficiency, remains to be evaluated. A FWR model is built to carry out experimental work. To be able to vary the flapping frequency rapidly during a stroke, an ultrasonic motor (USM) is used to drive the FWR. Experiment and numerical simulation using computational fluid dynamics (CFD) are performed in a VFF range versus the usual constant flapping frequency (CFF) cases. The measured lifting forces agree very well with the CFD results. Flapping frequency in an up-stroke is smaller than a down-stroke, and the negative lift and inertia forces can be reduced significantly. The average lift of the FWR where the motion in VFF is greater than the CFF, in the same input motor power or equivalent flapping frequency. In other words, the required power for a VFF case to produce a specified lift is less than a CFF case. For this FWR model, the optimal installation angle of the wings for high lift and efficiency is found to be 30° and the Strouhal number of the VFF cases is between 0.3–0.36. Full article

(This article belongs to the Special Issue IWPMA (International Workshop on Piezoelectric Materials and Applications in Actuators) 2019)

► Show Figures

Figure 1

5 pages, 156 KiB

Open AccessEditorial

Special Issue on Optical Communications and Networking: Prospects in Industrial Applications

by Zhongqi Pan, Qiang Wang, Yang Yue, Hao Huang and Changjing Bao

Appl. Sci. 2020, 10(1), 411; https://doi.org/10.3390/app10010411 - 6 Jan 2020

Viewed by 2105

Abstract

In the past two decades, Internet traffic has increased by over 10,000 times by taking advantage of both efficient information processing technology in the electronic domain and efficient transmission technology in the optical domain, which are the foundation of today’s Internet infrastructure [...] [...] Read more.

In the past two decades, Internet traffic has increased by over 10,000 times by taking advantage of both efficient information processing technology in the electronic domain and efficient transmission technology in the optical domain, which are the foundation of today’s Internet infrastructure [...] Full article

(This article belongs to the Special Issue Optical Communications and Networking: Prospects in Industrial Applications)

17 pages, 5377 KiB

Open AccessArticle

Calculation and Analysis of Wind Turbine Health Monitoring Indicators Based on the Relationships with SCADA Data

by Fan Zhang, Zejun Wen, Deshun Liu, Jie Jiao, Hengzheng Wan and Bing Zeng

Appl. Sci. 2020, 10(1), 410; https://doi.org/10.3390/app10010410 - 6 Jan 2020

Cited by 20 | Viewed by 3633

Abstract

This paper proposes an evaluation index of wind turbine generator operating health based on the relationships with SCADA (Supervisory Control and Data Acquisition) data. First, the relationship among the data from a wind turbine SCADA system is thoroughly analyzed. Then, a time based [...] Read more.

This paper proposes an evaluation index of wind turbine generator operating health based on the relationships with SCADA (Supervisory Control and Data Acquisition) data. First, the relationship among the data from a wind turbine SCADA system is thoroughly analyzed. Then, a time based sliding window model is used to process the SCADA data by the bin method, and a running state model of the wind turbine is established by data fitting. Taking the normal operation state model of the wind turbine as the standard reference and based on the Euclidean distance between the state model curve and the standard model curve, the health index of the wind turbine operation state is proposed. Finally, using SCADA data from two 2 MW direct-drive wind turbines as examples for analysis and discussion, the results show that: (1) health indicators have good stability and sensitivity to wind turbine operating conditions; (2) the width of the data window in the sliding window model must cover all operating conditions of the wind turbine to ensure that the health index depicts the operating state of the wind turbine; (3) the data window width, window increment, and data fitting modeling all affect the health indicators, and thus, the selection of the sliding window model parameters and the data relationship modeling methods should consider the accuracy and real-time performance of the health indicators; and (4) the data acquisition cycle does not affect the health indicators. Once the basic characteristics of the data relations are known, direct data fitting modeling is more efficient than bin preprocessing modeling. Full article

(This article belongs to the Special Issue Wind Power Technologies)

► Show Figures

Figure 1

22 pages, 614 KiB

Open AccessArticle

FMNISCF: Fine-Grained Multi-Domain Network Interconnection Security Control Framework

by Bo Lu, Ruohan Cao, Luyao Tian, Hao Wang and Yueming Lu

Appl. Sci. 2020, 10(1), 409; https://doi.org/10.3390/app10010409 - 6 Jan 2020

Viewed by 2394

Abstract

The integrated air-ground multi-domain network provides users with a set of shared infrastructures. Security policies can be defined flexibly in the context of multi-domain network semantics. The packet filter module in the security gateway can run efficiently, which is an urgent requirement in [...] Read more.

The integrated air-ground multi-domain network provides users with a set of shared infrastructures. Security policies can be defined flexibly in the context of multi-domain network semantics. The packet filter module in the security gateway can run efficiently, which is an urgent requirement in this network environment. The framework combined with multi-domain network semantics implements the transformation into rules. It replaces the traditional manual method of configuring rules. The framework supports the whole life cycle management of rules from generation state and distribution state to execution state. In the aspect of security, the map security and semantic security are analyzed and optimized, respectively. Finally, through a series of experiments, compared with iptables/DPDK-IPFW/BSD-IPFW/BSD-pfsense, the high efficiency of the scheme is verified. Full article

(This article belongs to the Section Electrical, Electronics and Communications Engineering)

► Show Figures

Graphical abstract

14 pages, 3718 KiB

Open AccessArticle

Modelling a Segmented Skutterudite-Based Thermoelectric Generator to Achieve Maximum Conversion Efficiency

by Aminu Yusuf and Sedat Ballikaya

Appl. Sci. 2020, 10(1), 408; https://doi.org/10.3390/app10010408 - 6 Jan 2020

Cited by 17 | Viewed by 4424

Abstract

Thermoelectric generator (TEG) modules generally have a low conversion efficiency. Among the reasons for the lower conversion efficiency is thermoelectric (TE) material mismatch. Hence, it is imperative to carefully select the TE material and optimize the design before any mass-scale production of the [...] Read more.

Thermoelectric generator (TEG) modules generally have a low conversion efficiency. Among the reasons for the lower conversion efficiency is thermoelectric (TE) material mismatch. Hence, it is imperative to carefully select the TE material and optimize the design before any mass-scale production of the modules. Here, with the help of Comsol-Multiphysics (5.3) software, TE materials were carefully selected and the design was optimized to achieve a higher conversion efficiency. An initial module simulation (32 couples) of unsegmented skutterudite Ba_0.1Yb_0.2Fe_0.1Co_3.9Sb₁₂ (n-type) and Ce_0.5Yb_0.5Fe_3.25Co_0.75Sb₁₂ (p-type) TE materials was carried out. At the temperature gradient T∆ = 500 K, a maximum simulated conversion efficiency of 9.2% and a calculated efficiency of 10% were obtained. In optimization via segmentation, the selection of TE materials, considering compatibility factor (s) and ZT, was carefully done. On the cold side, Bi₂Te₃ (n-type) and Sb₂Te₃ (p-type) TE materials were added as part of the segmentation, and at the same temperature gradient, an open circuit voltage of 6.2 V matched a load output power of 45 W, and a maximum simulated conversion efficiency of 15.7% and a calculated efficiency of 17.2% were achieved. A significant increase in the output characteristics of the module shows that the segmentation is effective. The TEG shows promising output characteristics. Full article

(This article belongs to the Special Issue Nanostructured Thermoelectrics; Synthesis, Processing and Applications)

► Show Figures

Figure 1

15 pages, 2265 KiB

Open AccessArticle

Determining Whether Tennis Benefits the Updating Function in Young Children: A Functional Near-Infrared Spectroscopy Study

by Yinghui Lai, Zhipeng Wang, Guang H. Yue and Changhao Jiang

Appl. Sci. 2020, 10(1), 407; https://doi.org/10.3390/app10010407 - 6 Jan 2020

Cited by 14 | Viewed by 3560

Abstract

This study aimed at investigating the behavioral and neuro-electrical impacts of a coordinative exercise intervention on the updating function of the working memory (WM) in young children. Children in the experimental group was tested on the 1-back working memory task before and after [...] Read more.

This study aimed at investigating the behavioral and neuro-electrical impacts of a coordinative exercise intervention on the updating function of the working memory (WM) in young children. Children in the experimental group was tested on the 1-back working memory task before and after a coordinative exercise program that involved a 60 min session twice per week for eight weeks (totally 16 sessions), while the control group underwent routine classroom activities with the same WM tests. The results showed that the hit rates of performing the 1-back task increased significantly in the experimental group compared with that of the control group. The experimental group demonstrated a larger decrease in both reaction time and false alarm rates from pre-test to post-test than the control group. Physical fitness improved after exercise intervention in the experimental group. Neural adaptations due to the exercise training were evaluated using functional near-infrared spectroscopy (fNIRS) and the results indicated that the experimental group experienced a greater cortical oxygenated hemoglobin (Oxy-Hb) increase in the prefrontal area after the intervention than the control group. These results suggest that coordinative exercises are beneficial for improving WM as well as reaction time and physical fitness in young children. Full article

(This article belongs to the Special Issue Diffuse Optical Spectroscopy: Advances Towards Widespread Applications)

► Show Figures

Figure 1

21 pages, 4050 KiB

Open AccessArticle

A Time Correlation Based Clustering Method for a Design of a Transformable Product

by Jinpu Zhang, Guozhong Cao, Qingjin Peng, Runhua Tan, Huangao Zhang and Wei Liu

Appl. Sci. 2020, 10(1), 406; https://doi.org/10.3390/app10010406 - 5 Jan 2020

Viewed by 2414

Abstract

A single-function product cannot meet various needs of different users when the product user or use environment changes. A transformable product with multiple functions can meet different needs of users. It is critical to determine product functions that a transformable product should have [...] Read more.

A single-function product cannot meet various needs of different users when the product user or use environment changes. A transformable product with multiple functions can meet different needs of users. It is critical to determine product functions that a transformable product should have in the product design. However, it is a challenge to decide required functional components of a transformable product in the design process. A clustering method is proposed in this paper using undirected graphs for segmentations of needs in the time dimension. A need-based function model is built to form product function chains based on cost of the function transition distance between different function chains. Undirected graphs of the function chains are constructed according to the similarity of product functions. The interrelated subgraphs are then used to form multiple functions of a transformable product based on segmentations. A wheelchair is developed as an example to verify the proposed method. The method improves the design process of transformable products accurately and effectively. Full article

(This article belongs to the Section Mechanical Engineering)

► Show Figures

Figure 1

21 pages, 10134 KiB

Open AccessArticle

Kinetics and Optimization by Response Surface Methodology of Aerobic Bioremediation. Geoelectrical Parameter Monitoring

by Carla Maria Raffa, Fulvia Chiampo, Alberto Godio, Andrea Vergnano, Francesca Bosco and Barbara Ruffino

Appl. Sci. 2020, 10(1), 405; https://doi.org/10.3390/app10010405 - 5 Jan 2020

Cited by 12 | Viewed by 3286

Abstract

This study aimed to investigate the kinetics of an aerobic bioremediation process of diesel oil removal by indigenous microorganisms, and to define the optimal operative conditions by means of response surface methodology. This was carried out by setting up a series of microcosms [...] Read more.

This study aimed to investigate the kinetics of an aerobic bioremediation process of diesel oil removal by indigenous microorganisms, and to define the optimal operative conditions by means of response surface methodology. This was carried out by setting up a series of microcosms (200 g of soil), polluted with the same diesel oil concentration (70 g·kg⁻¹ of soil), but with different water contents (u%) and carbon to nitrogen (C/N) ratios. The process was monitored by: (1) residual diesel oil concentration, to measure the removal efficiency, and (2) fluorescein production, to check the microbial activity. These two parameters were the objective variables used for the analysis of variance (ANOVA) and response surface methodology (RSM). The results allowed the interactions between u% and C/N to be defined and the optimal range to be adopted for each. The process kinetics was modeled with first- and second-order reaction rates; slightly better results were achieved for the second-order model in terms of parameter variability. Biological processes like degradation may have effects on dielectric properties of soil; an open-ended coaxial cable was used to measure the dielectric permittivity of microcosm matrices at the start and after 130 days of bioremediation. The evolution of the real and the imaginary components of dielectric permittivity provided results that supported the evidence of a biodegradation process in progress. Full article

(This article belongs to the Special Issue Advances in Bioremediation of Wastewaters and Contaminated Soils)

► Show Figures

Figure 1

15 pages, 2911 KiB

Open AccessArticle

Quantitative Analysis of Melanosis Coli Colonic Mucosa Using Textural Patterns

by Chung-Ming Lo, Chun-Chang Chen, Yu-Hsuan Yeh, Chun-Chao Chang and Hsing-Jung Yeh

Appl. Sci. 2020, 10(1), 404; https://doi.org/10.3390/app10010404 - 5 Jan 2020

Cited by 4 | Viewed by 5351

Abstract

Melanosis coli (MC) is a disease related to long-term use of anthranoid laxative agents. Patients with clinical constipation or obesity are more likely to use these drugs for long periods. Moreover, patients with MC are more likely to develop polyps, particularly adenomatous polyps. [...] Read more.

Melanosis coli (MC) is a disease related to long-term use of anthranoid laxative agents. Patients with clinical constipation or obesity are more likely to use these drugs for long periods. Moreover, patients with MC are more likely to develop polyps, particularly adenomatous polyps. Adenomatous polyps can transform to colorectal cancer. Recognizing multiple polyps from MC is challenging due to their heterogeneity. Therefore, this study proposed a quantitative assessment of MC colonic mucosa with texture patterns. In total, the MC colonoscopy images of 1092 person-times were included in this study. At the beginning, the correlations among carcinoembryonic antigens, polyp texture, and pathology were analyzed. Then, 181 patients with MC were extracted for further analysis while patients having unclear images were excluded. By gray-level co-occurrence matrix, texture patterns in the colorectal images were extracted. Pearson correlation analysis indicated five texture features were significantly correlated with pathological results (p < 0.001). This result should be used in the future to design an instant help software to help the physician. The information of colonoscopy and image analystic data can provide clinicians with suggestions for assessing patients with MC. Full article

(This article belongs to the Special Issue Image Processing Techniques for Biomedical Applications)

► Show Figures

Figure 1

9 pages, 3265 KiB

Open AccessArticle

Enhancing the Desalination Performance of Capacitive Deionization Using a Layered Double Hydroxide Coated Activated Carbon Electrode

by Jaehan Lee, Seoni Kim, Nayeong Kim, Choonsoo Kim and Jeyong Yoon

Appl. Sci. 2020, 10(1), 403; https://doi.org/10.3390/app10010403 - 5 Jan 2020

Cited by 18 | Viewed by 4505

Abstract

Capacitive deionization (CDI) is a promising desalination technology because of its simple, high energy efficient, and eco-friendly process. Among several factors that can affect the desalination capacitance of CDI, wettability of the electrode is considered one of the important parameters. However, various carbon [...] Read more.

Capacitive deionization (CDI) is a promising desalination technology because of its simple, high energy efficient, and eco-friendly process. Among several factors that can affect the desalination capacitance of CDI, wettability of the electrode is considered one of the important parameters. However, various carbon materials commonly have a hydrophobic behavior that disturbs the ion transfer between the bulk solution and the surface of the electrode. In this study, we fabricated a layered double hydroxide (LDH) coated activated carbon electrode using an in-situ growth method to enhance the wettability of the surface of the carbon electrode. The well-oriented and porous LDH layer resulted in a better wettability of the activated carbon electrode, attributing to an enhanced capacitance compared with that of the uncoated activated carbon electrode. Furthermore, from the desalination tests of the CDI system, the LDH coated carbon electrode showed a higher salt adsorption capacity (13.9 mg/g) than the uncoated carbon electrode (11.7 mg/g). Thus, this enhanced desalination performance suggests that the improvement in the wettability of the carbon electrode by the LDH coating provides facile ion transfer between the electrode and electrolyte. Full article

(This article belongs to the Special Issue Water Desalination Powered by Renewable Energy)

► Show Figures

Figure 1

16 pages, 2372 KiB

Open AccessArticle

Study on Water Saving Potential and Net Profit of Zea mays L.: The Role of Surface Mulching with Micro-Spray Irrigation

by Zhaoquan He, Xue Shang and Tonghui Zhang

Appl. Sci. 2020, 10(1), 402; https://doi.org/10.3390/app10010402 - 5 Jan 2020

Cited by 5 | Viewed by 3178

Abstract

Water shortage threatens agricultural sustainability in Horqin Sandy Land, northeast China. To explore the effects of various surface mulching patterns with micro-spray irrigation on the yield, water consumption (ET_c), and water-saving potential of maize (Zea mays L.), we used three [...] Read more.

Water shortage threatens agricultural sustainability in Horqin Sandy Land, northeast China. To explore the effects of various surface mulching patterns with micro-spray irrigation on the yield, water consumption (ET_c), and water-saving potential of maize (Zea mays L.), we used three treatments: straw mulching (JG), organic fertilizer mulching (NF), and no mulching (WG; control). In each treatment, plants were supplied with 500 mm of total water (irrigation plus precipitation) during the entire growing season and were irrigated with the amount of total water supply minus precipitation. Yield and water use efficiency (WUE) showed a significant negative correlation with water saving potential per unit yield (P_y) and water saving potential per unit area (S_p), which were also consistent with their relationships in the function model. Meanwhile, a remarkably positive correlation occurred between yield, WUE, and net economic profit, respectively. The JG treatment, which was mainly affected by light and temperature production potential (Y_c), grain yield, and ET_c, showed the lowest P_y (0.16 m³ kg⁻¹) and S_p (2572.31 m³ hm⁻²), and the maximum increase in yield, WUE, and net economic profit, extending to 16,178.40 kg hm⁻², 3.25 kg m⁻³, 17,610.09 yuan hm⁻², respectively, which were significantly higher than those in NF and WG, (p <0.05). Thus, straw mulching with micro-spray irrigation was the best treatment for maximizing yield and WUE. Organic manure mulching and no mulching need further investigation, as these showed high P_y and S_p, which were together responsible for lower WUE. Full article

(This article belongs to the Special Issue New Trends in Environmental Engineering, Agriculture, Food Production, and Analysis)

► Show Figures

Graphical abstract

11 pages, 1779 KiB

Open AccessArticle

Virtual Bone Augmentation in Atrophic Mandible to Assess Optimal Implant-Prosthetic Rehabilitation—A Finite Element Study

by Sînziana Anca Butnaru-Moldoveanu, Florin Munteanu and Norina Consuela Forna

Appl. Sci. 2020, 10(1), 401; https://doi.org/10.3390/app10010401 - 5 Jan 2020

Cited by 5 | Viewed by 3829

Abstract

The scope of our study was to analyze the impact of implant prosthetic rehabilitation, in bilateral terminal partial edentulism with mandibular bone atrophy, and potential benefits of mandibular bone augmentation through finite element analysis. A 3D mandible model was made using patient-derived cone-beam [...] Read more.

The scope of our study was to analyze the impact of implant prosthetic rehabilitation, in bilateral terminal partial edentulism with mandibular bone atrophy, and potential benefits of mandibular bone augmentation through finite element analysis. A 3D mandible model was made using patient-derived cone-beam computed tomography (CBCT) images, presenting a bilateral terminal edentation and mandibular atrophy. A virtual simulation of bone augmentation was then made. Implant-supported restorations were modeled for each edentulous area. Forces corresponding to the pterygoid and the masseter muscles, as well as mastication conditions for each quadrant, were applied. The resorbed mandible presented high values of strain and stress. A considerable variation between strain values among the two implant sites in each quadrant was found. In the augmented model, values of strain and stress showed a uniformization in both quadrants. Virtually increasing bone mass in the resorbed areas of the mandible showed that enabling larger implants drastically reduces strain and stress values in the implant sites. Also, although ridge height difference between the two quadrants was kept even after bone augmentation, there is a uniformization of the strain values between the two implant sites in each of the augmented mandible quadrants. Full article

(This article belongs to the Section Applied Dentistry and Oral Sciences)

► Show Figures

Figure 1

20 pages, 3137 KiB

Open AccessArticle

Nanofiltration of Simulated Acid Mine Drainage: Effect of pH and Membrane Charge

by Ye Wee Siew, Karina Listiarini Zedda and Svetlozar Velizarov

Appl. Sci. 2020, 10(1), 400; https://doi.org/10.3390/app10010400 - 5 Jan 2020

Cited by 25 | Viewed by 4702

Abstract

Acid mine drainage (AMD) is a severe form of environmental pollution that has the potential to contaminate surface and ground waters by introducing heavy metals and lowering the pH. The feasibility of using nanofiltration (NF) as a potentially attractive and cost-effective remediation method [...] Read more.

Acid mine drainage (AMD) is a severe form of environmental pollution that has the potential to contaminate surface and ground waters by introducing heavy metals and lowering the pH. The feasibility of using nanofiltration (NF) as a potentially attractive and cost-effective remediation method to treat acid mine drainage was investigated in this study. The performance of an acid-stable NF membrane focusing on the effects of the water pH and membrane charge on ion rejection was systematically studied. A single salt solution experiment showed that Mg, Cu, and Mn containing species were highly rejected at above 97%. Below the membrane iso-electric point (IEP), Mn showed an increased rejection of 99%, while Mg and Mn rejections were relatively constant within the investigated pH range of pH 2 to 7. Rejection of monovalent Cl⁻ decreased with increasing concentration of an accompanying divalent SO₄²⁻, showing that Donnan related effects are more prominent at higher ionic concentrations. The sulfate rejection decreased drastically below pH 3 due to the formation of HSO₄⁻, which permeated through the membrane, which can be utilized as a way of separation of the metals from the accompanying sulfur-containing compounds. For mixed salt solutions, rejection of silicate dropped from 52% to 38% when magnesium sulfate was added, owing to shielding of the membrane surface charge by Mg²⁺ ions. The NF process performance with a simulated AMD solution was found to be similar to that with model salt solution experiments, both in terms of ion rejection values and general pH-dependent rejection trends. The results obtained can be used as a fast preliminary tool for evaluating the feasibility of using NF for treating AMD with a given ionic composition and pH. Full article

(This article belongs to the Section Environmental Sciences)

► Show Figures

Figure 1

12 pages, 4062 KiB

Open AccessArticle

A 24.88 nV/√Hz Wheatstone Bridge Readout Integrated Circuit with Chopper-Stabilized Multipath Operational Amplifier

by Kwonsang Han, Hyungseup Kim, Jaesung Kim, Donggeun You, Hyunwoo Heo, Yongsu Kwon, Junghoon Lee and Hyoungho Ko

Appl. Sci. 2020, 10(1), 399; https://doi.org/10.3390/app10010399 - 5 Jan 2020

Cited by 9 | Viewed by 7905

Abstract

This paper proposes a low noise readout integrated circuit (IC) with a chopper-stabilized multipath operational amplifier suitable for a Wheatstone bridge sensor. The input voltage of the readout IC changes due to a change in input resistance, and is efficiently amplified using a [...] Read more.

This paper proposes a low noise readout integrated circuit (IC) with a chopper-stabilized multipath operational amplifier suitable for a Wheatstone bridge sensor. The input voltage of the readout IC changes due to a change in input resistance, and is efficiently amplified using a three-operational amplifier instrumentation amplifier (IA) structure with high input impedance and adjustable gain. Furthermore, a chopper-stabilized multipath structure is applied to the operational amplifier, and a ripple reduction loop (RRL) in the low frequency path (LFP) is employed to attenuate the ripple generated by the chopper stabilization technique. A 12-bit successive approximation register (SAR) analog-to-digital converter (ADC) is employed to convert the output voltage of the three-operational amplifier IA into digital code. The Wheatstone bridge readout IC is manufactured using a standard 0.18 µm complementary metal-oxide-semiconductor (CMOS) technology, drawing 833 µA current from a 1.8 V supply. The input range and the input referred noise are ±20 mV and 24.88 nV/√Hz, respectively. Full article

(This article belongs to the Special Issue Selected Papers from IMETI 2018)

► Show Figures

Figure 1

17 pages, 362 KiB

Open AccessArticle

Performance Analysis of Maximal Risk Evaluation Formulas for Spectrum-Based Fault Localization

by Tingting Wu, Yunwei Dong, Man Fai Lau, Sebastian Ng, Tsong Yueh Chen and Mingyue Jiang

Appl. Sci. 2020, 10(1), 398; https://doi.org/10.3390/app10010398 - 5 Jan 2020

Cited by 6 | Viewed by 2460

Abstract

The effectiveness analysis of risk evaluation formulas has become a significant research area in spectrum-based fault localization (SBFL). The risk evaluation formula is designed and widely used to evaluate the likelihood of a program spectrum to be faulty. There are numerous empirical and [...] Read more.

The effectiveness analysis of risk evaluation formulas has become a significant research area in spectrum-based fault localization (SBFL). The risk evaluation formula is designed and widely used to evaluate the likelihood of a program spectrum to be faulty. There are numerous empirical and theoretical studies to investigate and compare the performance between sixty risk evaluation formulas. According to previous research, these sixty risk evaluation formulas together form a partially ordered set. Among them, nine formulas are maximal. These nine formulas can further be grouped into five maximal risk evaluation formula groups so that formulas in the same group have the same performance. Moreover, previous research showed that we cannot theoretically compare formulas across these five maximal formula groups. However, experimental data “suggests” that a maximal formula in one group could outperform another one (from a different group) more frequently, though not always. This inspired us to further investigate the performance between any two maximal formulas in different maximal formula groups. Our approach involves two major steps. First, we propose a new condition to compare between two different maximal formulas. Based on this new condition, we present five different scenarios under which a formula performs better than another. This is different from the condition suggested by the previous theoretical study. We performed an empirical study to compare different maximal formulas using our condition. Our results showed that among two maximal risk evaluation formulas, it is feasible to identify one that can outperform the others more frequently. Full article

► Show Figures

Figure 1

10 pages, 1343 KiB

Open AccessArticle

Acute Effects of Midsole Bending Stiffness on Lower Extremity Biomechanics during Layup Jumps

by Zhiqiang Zhu, Weijie Fu, En Shao, Lu Li, Linjie Song, Wei Wang and Yu Liu

Appl. Sci. 2020, 10(1), 397; https://doi.org/10.3390/app10010397 - 5 Jan 2020

Cited by 8 | Viewed by 3454

Abstract

Purpose: This study aims to investigate the acute effects of shoe midsole stiffness on the joint biomechanics of the lower extremities during specific basketball movements. Methods: Thirty participants wearing stiff midsole shoes (SS) and control shoes (CS) performed layup jumps (LJs) while the [...] Read more.

Purpose: This study aims to investigate the acute effects of shoe midsole stiffness on the joint biomechanics of the lower extremities during specific basketball movements. Methods: Thirty participants wearing stiff midsole shoes (SS) and control shoes (CS) performed layup jumps (LJs) while the kinematics and ground reaction forces were simultaneously collected via the Vicon motion capture system and Kistler force plates. Furthermore, the joint angles, range of motion (ROM), joint power, joint energy, and jump height were calculated. Results: No significant differences were observed between SS and CS conditions for both jump height and the metatarsophalangeal (MTP) joint biomechanics except that the minimum angular velocity of the MTP joint was significantly lower in SS the condition. However, the ROM in the ankle joint was significantly greater in the SS condition than in the CS condition (p < 0.05). Additionally, the maximum plantarflexion power, energy absorption (EA), and energy generation (EG) in the ankle joint were significantly greater in the SS condition than in the CS condition (p < 0.05). Compared with the CS condition, jump height in the SS condition did not increase. Conclusion: During a single LJ, the longitudinal midsole stiffness did not influence the jump height and MTP joint biomechanical patterns but significantly increased the maximum power, EA, and EG during the push-off phase of the ankle joint. These preliminary results indicate that wearing SS could change the ankle joint mechanical patterns by modulating the lower extremity kinetic chain, and may enhance muscle strength in the ankle. Full article

(This article belongs to the Special Issue Applied Biomechanics in Sport, Rehabilitation and Ergonomy)

► Show Figures

Figure 1

15 pages, 3026 KiB

Open AccessArticle

Heterogeneous Defect Prediction Based on Transfer Learning to Handle Extreme Imbalance

by Kaiyuan Jiang, Yutong Zhang, Haibin Wu, Aili Wang and Yuji Iwahori

Appl. Sci. 2020, 10(1), 396; https://doi.org/10.3390/app10010396 - 5 Jan 2020

Cited by 6 | Viewed by 3111

Abstract

Software systems are now ubiquitous and are used every day for automation purposes in personal and enterprise applications; they are also essential to many safety-critical and mission-critical systems, e.g., air traffic control systems, autonomous cars, and Supervisory Control And Data Acquisition (SCADA) systems. [...] Read more.

Software systems are now ubiquitous and are used every day for automation purposes in personal and enterprise applications; they are also essential to many safety-critical and mission-critical systems, e.g., air traffic control systems, autonomous cars, and Supervisory Control And Data Acquisition (SCADA) systems. With the availability of massive storage capabilities, high speed Internet, and the advent of Internet of Things devices, modern software systems are growing in both size and complexity. Maintaining a high quality of such complex systems while manually keeping the error rate at a minimum is a challenge. This paper proposed a heterogeneous defect prediction method considering class extreme imbalance problem in real software datasets. In the first stage, Sampling with the Majority method (SWIM) based on Mahalanobis Distance is used to balance the dataset to reduce the influence of minority samples in defect data. Due to the negative impact of uncorrelated features on the classification algorithm, the second stage uses ensemble learning and joint similarity measurement to select the most relevant and representative features between the source project and the target project. The third phase realizes the transfer learning from the source project to the target project in the Grassmann manifold space. Our experiments, conducted using nine projects of three public domain software defect libraries and compared with four existing advanced methods to verify the effectiveness of the proposed method in this paper. The experimental results indicate that the proposed method is more accurate in terms of Area under curve (AUC). Full article

(This article belongs to the Special Issue Wireless Sensor Networks in Smart Environments)

► Show Figures

Figure 1

10 pages, 1558 KiB

Open AccessArticle

Dispersion Measurement of Electro-Optic Coefficient γ₂₂ of Lithium Niobate Based on Photoelastic Modulation

by Kewu Li, Shuang Wang, Xie Han and Zhibin Wang

Appl. Sci. 2020, 10(1), 395; https://doi.org/10.3390/app10010395 - 4 Jan 2020

Cited by 8 | Viewed by 3572

Abstract

A novel method for determining the electro-optic (EO) coefficient

γ_{22}

of lithium niobate and its dispersion using photoelastic modulation is presented. A spectroscopic polarimetry was constructed with the photoelastic modulator (PEM), and a monochromator was selected to automatically scan the wavelength of [...] Read more.

A novel method for determining the electro-optic (EO) coefficient

γ_{22}

of lithium niobate and its dispersion using photoelastic modulation is presented. A spectroscopic polarimetry was constructed with the photoelastic modulator (PEM), and a monochromator was selected to automatically scan the wavelength of a light source. Phase retardation induced by an EO sample was loaded into the modulation signals to demodulate the EO coefficients. The PEM and data processing were controlled in the same field programmable gate array (FPGA), and the DC and harmonic terms were extracted simultaneously by employing digital phase-locked technology. An experimental system was built to analyze the principle of this scheme in detail. After the modulation phase retardation amplitude of the PEM was precisely calibrated, the EO coefficient

γ_{22}

of a Y-cut lithium niobate crystal plate was measured in the spectral range from 0.42 to 0.8 µm. The experimental results demonstrated that the measurement sensitivity of the system was

1.1 \times 10^{- 14} m / V

for a sampling time of 198.9 ms. Plotting the measured results against the light wavelength, the dispersion of the EO coefficients was obtained similar to the Cauchy dispersion formula

γ_{22} = 5.31 \times 10^{- 12} + \frac{4.071 \times 10^{- 13}}{λ^{2}} + \frac{7.184 \times 10^{- 14}}{λ^{4}}

in the visible light range. This method is suitable for studying dispersion of the EO coefficients of crystals as well as of thin films and two-dimensional materials. Full article

(This article belongs to the Section Optics and Lasers)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Appl. Sci., Volume 10, Issue 1 (January-1 2020) – 424 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI