Applied Sciences

13 pages, 1527 KiB

Open AccessArticle

Dynamic Optimization of Data Packet-based Communication for PLC Visual Monitoring

by Changjiang Ju, Genke Yang, Yu-Wang Chen and Changchun Pan

Appl. Sci. 2019, 9(8), 1721; https://doi.org/10.3390/app9081721 - 25 Apr 2019

Cited by 2 | Viewed by 3125

This paper presents a dynamic optimization solution for the data packet-based communication of programmable logic controller (PLC) visual monitoring, and the objective is to improve the communication efficiency between a supervisory computer and field PLCs in consideration of the network communication performance, such [...] Read more.

This paper presents a dynamic optimization solution for the data packet-based communication of programmable logic controller (PLC) visual monitoring, and the objective is to improve the communication efficiency between a supervisory computer and field PLCs in consideration of the network communication performance, such as network bandwidth, packet loss or retransmission rate, and human response delay. A nonlinear optimization model with constraints is formulated and solved analytically to obtain the minimized transmission time. Experimental results demonstrate that the proposed dynamic optimization can solve the practical industry problem in an efficient and effective manner, and it can provide useful guidance for the data packet-based communication setting of networked control systems. Full article

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

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9 pages, 1676 KiB

Open AccessArticle

Nonlinearity of Microwave Electric Field Coupled Rydberg Electromagnetically Induced Transparency and Autler-Townes Splitting

by Liping Hao, Yongmei Xue, Jiabei Fan, Yuechun Jiao, Jianming Zhao and Suotang Jia

Appl. Sci. 2019, 9(8), 1720; https://doi.org/10.3390/app9081720 - 25 Apr 2019

Cited by 7 | Viewed by 3793

Abstract

An electromagnetically induced transparency (EIT) of a cascade-three-level atom involving Rydberg level in a room-temperature cell, formed with a cesium 6

S_{1 / 2}

-6

P_{3 / 2}

-66

S_{1 / 2}

scheme, is employed to detect the Autler-Townes (AT) [...] Read more.

An electromagnetically induced transparency (EIT) of a cascade-three-level atom involving Rydberg level in a room-temperature cell, formed with a cesium 6

S_{1 / 2}

-6

P_{3 / 2}

-66

S_{1 / 2}

scheme, is employed to detect the Autler-Townes (AT) splitting resulted with a 15.21-GHz microwave field coupling the 66

S_{1 / 2}

→ 65

P_{1 / 2}

transition. Microwave field induced AT splitting,

f_{A T}

, is characterized by the distance of peak-to-peak of an EIT-AT spectrum. The

f_{A T}

dependence on the microwave Rabi frequency,

Ω_{M W}

, demonstrates two regions, the strong-coupling linear region,

f_{A T}

≈

Ω_{M W}

and the weak-coupling nonlinear region,

f_{A T}

≲

Ω_{M W}

. The

f_{A T}

dependencies on the probe and coupling Rabi frequency are also investigated. Using small probe- and coupling-laser, the Rabi frequency is found to enlarge the linear regime and decrease the uncertainty of the microwave field measurements. The measurements agree with the calculations based on a four-level atomic model. Full article

(This article belongs to the Special Issue Recent Advances in Statistical Optics and Plasmonics)

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26 pages, 4161 KiB

Open AccessArticle

Particle Swarm Optimization and Cuckoo Search-Based Approaches for Quadrotor Control and Trajectory Tracking

by Nada El Gmili, Mostafa Mjahed, Abdeljalil El Kari and Hassan Ayad

Appl. Sci. 2019, 9(8), 1719; https://doi.org/10.3390/app9081719 - 25 Apr 2019

Cited by 27 | Viewed by 4053

Abstract

This paper explores the full control of a quadrotor Unmanned Aerial Vehicles (UAVs) by exploiting the nature-inspired algorithms of Particle Swarm Optimization (PSO), Cuckoo Search (CS), and the cooperative Particle Swarm Optimization-Cuckoo Search (PSO-CS). The proposed PSO-CS algorithm combines the ability of social [...] Read more.

This paper explores the full control of a quadrotor Unmanned Aerial Vehicles (UAVs) by exploiting the nature-inspired algorithms of Particle Swarm Optimization (PSO), Cuckoo Search (CS), and the cooperative Particle Swarm Optimization-Cuckoo Search (PSO-CS). The proposed PSO-CS algorithm combines the ability of social thinking in PSO with the local search capability in CS, which helps to overcome the problem of low convergence speed of CS. First, the quadrotor dynamic modeling is defined using Newton-Euler formalism. Second, PID (Proportional, Integral, and Derivative) controllers are optimized by using the intelligent proposed approaches and the classical method of Reference Model (RM) for quadrotor full control. Finally, simulation results prove that PSO and PSO-CS are more efficient in tuning of optimal parameters for the quadrotor control. Indeed, the ability of PSO and PSO-CS to track the imposed trajectories is well seen from 3D path tracking simulations and even in presence of wind disturbances. Full article

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

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15 pages, 6090 KiB

Open AccessArticle

Medical Image Segmentation with Adjustable Computational Complexity Using Data Density Functionals

by Chien-Chang Chen, Meng-Yuan Tsai, Ming-Ze Kao and Henry Horng-Shing Lu

Appl. Sci. 2019, 9(8), 1718; https://doi.org/10.3390/app9081718 - 25 Apr 2019

Cited by 5 | Viewed by 3164

Abstract

Techniques of automatic medical image segmentation are the most important methods for clinical investigation, anatomic research, and modern medicine. Various image structures constructed from imaging apparatus achieve a diversity of medical applications. However, the diversified structures are also a burden of contemporary techniques. [...] Read more.

Techniques of automatic medical image segmentation are the most important methods for clinical investigation, anatomic research, and modern medicine. Various image structures constructed from imaging apparatus achieve a diversity of medical applications. However, the diversified structures are also a burden of contemporary techniques. Performing an image segmentation with a tremendously small size (<25 pixels by 25 pixels) or tremendously large size (>1024 pixels by 1024 pixels) becomes a challenge in perspectives of both technical feasibility and theoretical development. Noise and pixel pollution caused by the imaging apparatus even aggravate the difficulty of image segmentation. To simultaneously overcome the mentioned predicaments, we propose a new method of medical image segmentation with adjustable computational complexity by introducing data density functionals. Under this theoretical framework, several kernels can be assigned to conquer specific predicaments. A square-root potential kernel is used to smoothen the featured components of employed images, while a Yukawa potential kernel is applied to enhance local featured properties. Besides, the characteristic of global density functional estimation also allows image compression without losing the main image feature structures. Experiments on image segmentation showed successful results with various compression ratios. The computational complexity was significantly improved, and the score of accuracy estimated by the Jaccard index had a great outcome. Moreover, noise and regions of light pollution were mostly filtered out in the procedure of image compression. Full article

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

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15 pages, 1689 KiB

Open AccessArticle

The Effects of Dry, Humid and Wear Conditions on the Antimicrobial Efficiency of Triclosan-Containing Surfaces

by Abel Guillermo Ríos-Castillo, Carolina Ripolles-Avila and José Juan Rodríguez-Jerez

Appl. Sci. 2019, 9(8), 1717; https://doi.org/10.3390/app9081717 - 25 Apr 2019

Cited by 6 | Viewed by 3780

Abstract

This study evaluated the effects of triclosan-containing polyester surfaces under various conditions at concentrations of between 400 ppm and 850 ppm. Staphylococcus aureus was chosen for the tests because it rapidly develops resistance to many antimicrobial agents. The results show that dry and [...] Read more.

This study evaluated the effects of triclosan-containing polyester surfaces under various conditions at concentrations of between 400 ppm and 850 ppm. Staphylococcus aureus was chosen for the tests because it rapidly develops resistance to many antimicrobial agents. The results show that dry and humid conditions have bacteriostatic activity that inhibits the growth of S. aureus, with a greater effect under dryness (p < 0.05). Further, concentrations as low as 400 ppm showed activities of 0.99 log₁₀ and 0.19 log₁₀ for dry and humid conditions, respectively. The study of the association between triclosan concentrations and bacterial inhibition showed a high correlation for dry (R² = 0.968) and humid conditions (R² = 0.986). Under wear conditions, triclosan showed a gradual reduction in its bacteriostatic activity due to successive washing/drying treatments (p < 0.05). Thus, the use of triclosan in low concentrations is suggested as achieving bacteriostatic activity. Moreover, its use can be considered as complementary to the cleaning and disinfection procedures carried out in the food industry. However, it must not replace them. Manufacturing processes must be improved to preserve the triclosan properties in the antimicrobial materials to control microorganisms involved in cross-contamination between surfaces and food. Full article

(This article belongs to the Special Issue Engineering Methods for Packaging Design of Perishable Products)

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15 pages, 588 KiB

Open AccessArticle

Selectively Connected Self-Attentions for Semantic Role Labeling

by Jaehui Park

Appl. Sci. 2019, 9(8), 1716; https://doi.org/10.3390/app9081716 - 25 Apr 2019

Cited by 2 | Viewed by 2831

Abstract

Semantic role labeling is an effective approach to understand underlying meanings associated with word relationships in natural language sentences. Recent studies using deep neural networks, specifically, recurrent neural networks, have significantly improved traditional shallow models. However, due to the limitation of recurrent updates, [...] Read more.

Semantic role labeling is an effective approach to understand underlying meanings associated with word relationships in natural language sentences. Recent studies using deep neural networks, specifically, recurrent neural networks, have significantly improved traditional shallow models. However, due to the limitation of recurrent updates, they require long training time over a large data set. Moreover, they could not capture the hierarchical structures of languages. We propose a novel deep neural model, providing selective connections among attentive representations, which remove the recurrent updates, for semantic role labeling. Experimental results show that our model performs better in accuracy compared to the state-of-the-art studies. Our model achieves 86.6 F1 scores and 83.6 F1 scores on the CoNLL 2005 and CoNLL 2012 shared tasks, respectively. The accuracy gains are improved by capturing the hierarchical information using the connection module. Moreover, we show that our model can be parallelized to avoid the repetitive updates of the model. As a result, our model reduces the training time by 62 percentages from the baseline. Full article

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

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20 pages, 10761 KiB

Open AccessArticle

The Method of Fundamental Solutions for Three-Dimensional Nonlinear Free Surface Flows Using the Iterative Scheme

by Cheng-Yu Ku, Jing-En Xiao and Chih-Yu Liu

Appl. Sci. 2019, 9(8), 1715; https://doi.org/10.3390/app9081715 - 25 Apr 2019

Cited by 2 | Viewed by 3258

Abstract

In this article, we present a meshless method based on the method of fundamental solutions (MFS) capable of solving free surface flow in three dimensions. Since the basis function of the MFS satisfies the governing equation, the advantage of the MFS is that [...] Read more.

In this article, we present a meshless method based on the method of fundamental solutions (MFS) capable of solving free surface flow in three dimensions. Since the basis function of the MFS satisfies the governing equation, the advantage of the MFS is that only the problem boundary needs to be placed in the collocation points. For solving the three-dimensional free surface with nonlinear boundary conditions, the relaxation method in conjunction with the MFS is used, in which the three-dimensional free surface is iterated as a movable boundary until the nonlinear boundary conditions are satisfied. The proposed method is verified and application examples are conducted. Comparing results with those from other methods shows that the method is robust and provides high accuracy and reliability. The effectiveness and ease of use for solving nonlinear free surface flows in three dimensions are also revealed. Full article

(This article belongs to the Special Issue Advances in Geohydrology: Methods and Applications)

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10 pages, 3148 KiB

Open AccessArticle

Performance of Retro-Reflective Building Envelope Materials with Fixed Glass Beads

by Jihui Yuan, Craig Farnham and Kazuo Emura

Appl. Sci. 2019, 9(8), 1714; https://doi.org/10.3390/app9081714 - 25 Apr 2019

Cited by 10 | Viewed by 3608

Abstract

Urban heat islands (UHI) are growing in size and intensity, which is partly attributable to the large amount of anthropogenic waste heat. Moreover, heat emitted from building exterior walls accounts for a large portion of the total anthropogenic waste heat. Thus, strategies and [...] Read more.

Urban heat islands (UHI) are growing in size and intensity, which is partly attributable to the large amount of anthropogenic waste heat. Moreover, heat emitted from building exterior walls accounts for a large portion of the total anthropogenic waste heat. Thus, strategies and technologies for preventing the emission of heat from building exterior walls are being pursued by researchers worldwide. Amongst these technologies, the potential of use of retro-reflective (RR) materials instead of diffuse highly reflective (HR) materials applied to building envelopes for UHI mitigation is being studied widely. However, RR materials haven’t been applied to building envelopes in practice due to their unproven weather resistance. In order to develop RR materials with high weather resistance for application to building envelopes, two types of micro glass beads with different refractive indices (1.5, 1.9) and five different colors of base layers were evaluated in this study. Their RR performance was measured by optical experiment and compared to two types of RR sheets commercially available in Japan. The results showed that the glass bead RR samples with a refractive index of 1.9 had much higher retro-reflectivity (better RR capacity) compared to those with a refractive index of 1.5. Full article

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

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23 pages, 786 KiB

Open AccessEditor’s ChoiceReview

Current Biomedical Applications of 3D Printing and Additive Manufacturing

by Pouyan Ahangar, Megan E Cooke, Michael H Weber and Derek H Rosenzweig

Appl. Sci. 2019, 9(8), 1713; https://doi.org/10.3390/app9081713 - 25 Apr 2019

Cited by 179 | Viewed by 17958

Abstract

Additive manufacturing (AM) has emerged over the past four decades as a cost-effective, on-demand modality for fabrication of geometrically complex objects. The ability to design and print virtually any object shape using a diverse array of materials, such as metals, polymers, ceramics and [...] Read more.

Additive manufacturing (AM) has emerged over the past four decades as a cost-effective, on-demand modality for fabrication of geometrically complex objects. The ability to design and print virtually any object shape using a diverse array of materials, such as metals, polymers, ceramics and bioinks, has allowed for the adoption of this technology for biomedical applications in both research and clinical settings. Current advancements in tissue engineering and regeneration, therapeutic delivery, medical device fabrication and operative management planning ensure that AM will continue to play an increasingly important role in the future of healthcare. In this review, we outline current biomedical applications of common AM techniques and materials. Full article

(This article belongs to the Special Issue Biocompatible Materials)

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20 pages, 436 KiB

Open AccessArticle

At the Nexus of Blockchain Technology, the Circular Economy, and Product Deletion

by Mahtab Kouhizadeh, Joseph Sarkis and Qingyun Zhu

Appl. Sci. 2019, 9(8), 1712; https://doi.org/10.3390/app9081712 - 25 Apr 2019

Cited by 137 | Viewed by 10801

Abstract

The circular economy (CE) is an emergent concept to rethink and redesign how our economy works. The concept recognizes effective and efficient economic functioning at multiple scales—governments and individuals, globally and locally; for businesses, large and small. CE represents a systemic shift that [...] Read more.

The circular economy (CE) is an emergent concept to rethink and redesign how our economy works. The concept recognizes effective and efficient economic functioning at multiple scales—governments and individuals, globally and locally; for businesses, large and small. CE represents a systemic shift that builds long-term resilience at multiple levels (macro, meso and micro); generating new business and economic opportunities while providing environmental and societal benefits. Blockchain, an emergent and critical technology, is introduced to the circular economy environment as a potential enabler for many circular economic principles. Blockchain technology supported information systems can improve circular economy performance at multiple levels. Product deletion, a neglected but critical effort in product management and product portfolio management, is utilized as an illustrative business scenario as to blockchain’s application in a circular economy research context. Product deletion, unlike product proliferation, has received minimal attention from both academics and practitioners. Product deletion decisions need to be evaluated and analyzed in the circular economy context. CE helps address risk aversion issues in product deletions such as inventory, waste and information management. This paper is the first to conceptualize the relationships amongst blockchain technology, product deletion and the circular economy. Many nuances of relationships are introduced in this study. Future evaluation and critical reflections are also presented with a need for a rigorous and robust research agenda to evaluate the multiple and complex relationships and interplay amongst technology, policy, commerce and the natural environment. Full article

(This article belongs to the Special Issue Advances in Blockchain Technology and Applications)

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21 pages, 5088 KiB

Open AccessArticle

Gaussian Process-Integrated State Space Model for Continuous Joint Angle Prediction from EMG and Interactive Force in a Human-Exoskeleton System

by Yan Zeng, Jiantao Yang and Yuehong Yin

Appl. Sci. 2019, 9(8), 1711; https://doi.org/10.3390/app9081711 - 25 Apr 2019

Cited by 14 | Viewed by 4651

Abstract

As one of the most direct indicators of the transparency between a human and an exoskeleton, interactive force has rarely been fused with electromyography (EMG) in the control of human-exoskeleton systems, the performances of which are largely determined by the accuracy of the [...] Read more.

As one of the most direct indicators of the transparency between a human and an exoskeleton, interactive force has rarely been fused with electromyography (EMG) in the control of human-exoskeleton systems, the performances of which are largely determined by the accuracy of the continuous joint angle prediction. To achieve intuitive and naturalistic human intent learning, a state space model (SSM) for continuous angle prediction of knee joint is developed. When the influence of the interactive force is often ignored in the existing models of human-exoskeleton systems, interactive force is applied as the measurement model output of the proposed SSM, and the EMG signal is used as the state model input signal to indicate muscle activation. The forward dynamics of joint motion and the human-machine interaction mechanism, i.e., the biomechanical interpretations of the interactive force generation mechanism, are derived as the bases for the state model and measurement model based on Hill’s muscle model and semiphenomenological (SP) muscular model, respectively. Gaussian process (GP)-based nonlinear autoregressive with the exogenous inputs (NARX) model and back-propagation neural network (BPNN) are applied to provide better adaptivity for the SSM in practical applications. Corresponding experimental results demonstrate the validity and superiority of the method. Full article

(This article belongs to the Special Issue Recent Advance and Future Trends in Rehabilitation and Nursing-Care Robots)

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14 pages, 4908 KiB

Open AccessArticle

A Telepresence System for Therapist-in-the-Loop Training for Elbow Joint Rehabilitation

by Songyuan Zhang, Qiang Fu, Shuxiang Guo and Yili Fu

Appl. Sci. 2019, 9(8), 1710; https://doi.org/10.3390/app9081710 - 25 Apr 2019

Cited by 14 | Viewed by 3587

Abstract

This paper proposes a new robotic rehabilitation training platform that is motivated by the requirement for adjusting the training strategy and intensity in a patient-specific manner. The platform is implemented for tele-rehabilitation and is comprised of a haptic device operated by therapists, a [...] Read more.

This paper proposes a new robotic rehabilitation training platform that is motivated by the requirement for adjusting the training strategy and intensity in a patient-specific manner. The platform is implemented for tele-rehabilitation and is comprised of a haptic device operated by therapists, a lightweight exoskeleton worn by patients and a visually shared model. Through the visually shared model, the motion of the therapist and patient are measured and mapped to the motion of the corresponding object. Thus, the force generated by the therapist can be transferred to the patient for delivering training, while real-time force feedback with high transparency can be provided to the therapist so they know the amount of force being applied to patients in real time. In particular, both assistive therapy in the early stages and resistive therapy in the later stages of stroke can be performed. The home-use exoskeleton device is specifically designed to be light-weight and compliant for safety. The patient-exoskeleton and therapist-haptic interaction performance is evaluated by observing the muscle activities and interaction force. Two volunteers were requested to imitate the process of the therapist-in-the-loop training to evaluate the proposed platform. Full article

(This article belongs to the Special Issue Recent Advance and Future Trends in Rehabilitation and Nursing-Care Robots)

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15 pages, 3236 KiB

Open AccessArticle

Field Study on the Waterstop of the Rodin Jet Pile Method in a Water-Rich Sandy Gravel Stratum

by Chengli Guan and Yuyou Yang

Appl. Sci. 2019, 9(8), 1709; https://doi.org/10.3390/app9081709 - 25 Apr 2019

Cited by 8 | Viewed by 4195

Abstract

Due to the increasing depths of underground urban construction, the surrounding environment and hydrogeological conditions are becoming increasingly complex, and conventional high-pressure rotary jet grouting has become unable to meet construction needs. At present, Rodin jet pile (RJP) ultra-high-pressure rotary jet grouting has [...] Read more.

Due to the increasing depths of underground urban construction, the surrounding environment and hydrogeological conditions are becoming increasingly complex, and conventional high-pressure rotary jet grouting has become unable to meet construction needs. At present, Rodin jet pile (RJP) ultra-high-pressure rotary jet grouting has been widely used as a grouting reinforcement method for deep and large foundations in silty soils, fine sands and clay strata; however, there have been no successful applications in a sandy gravel stratum with high water content (namely, water-rich sandy gravel stratum). Therefore, this paper uses the ventilating shaft in a section of the Beijing Metro as the construction background to carry out field tests on the RJP ultra-high-pressure rotary jet grouting method and waterstop in a water-rich sandy gravel stratum. Through a series of experiments monitoring the formation deformation and pore water pressure and exposing the pile diameter, pile occlusion, pile strength, and permeability of the test pile construction process, it is believed that, for the RJP ultra-high-pressure construction method in a water-rich sandy gravel stratum, reliable jet solidification can occur, the joint between jets can be achieved, the solid strength can reach 10 MPa or higher, and the permeability coefficient can reach 10⁻⁸ cm/s. Therefore, RJP ultra-high-pressure rotary jet grouting can be applied as a waterstop method in water-rich sandy gravel stratum. Full article

(This article belongs to the Section Civil Engineering)

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20 pages, 17840 KiB

Open AccessArticle

Brain-Like Navigation Scheme based on MEMS-INS and Place Recognition

by Chong Shen, Xiaochen Liu, Huiliang Cao, Yuchen Zhou, Jun Liu, Jun Tang, Xiaoting Guo, Haoqian Huang and Xuemei Chen

Appl. Sci. 2019, 9(8), 1708; https://doi.org/10.3390/app9081708 - 25 Apr 2019

Cited by 54 | Viewed by 4129

Abstract

Animals have certain cognitive competence about the environment so they can correct their navigation errors. Inspired by the excellent navigational behavior of animals, this paper proposes a brain-like navigation scheme to improve the accuracy and intelligence of Micro-Electro-Mechanical System based Inertial Navigation Systems [...] Read more.

Animals have certain cognitive competence about the environment so they can correct their navigation errors. Inspired by the excellent navigational behavior of animals, this paper proposes a brain-like navigation scheme to improve the accuracy and intelligence of Micro-Electro-Mechanical System based Inertial Navigation Systems (MEMS-INS). The proposed scheme employs vision to acquire external perception information as an absolute reference to correct the position errors of INS, which is established by analyzing the navigation and error correction mechanism of rat brains. In addition, to improve the place matching speed and precision of the system for visual scene recognition, this paper presents a novel place recognition algorithm that combines image scanline intensity (SI) and grid-based motion statistics (GMS) together which is named the SI-GMS algorithm. The proposed SI-GMS algorithm can effectively reduce the influence of uncertain environment factors on the recognition results, such as pedestrians and vehicles. It solves the problem that the matching result will occasionally go wrong when simply using the scanline intensity (SI) algorithm, or the slow matching speed when simply using grid-based motion statistics (GMS) algorithm. Finally, an outdoor Unmanned Aerial Vehicle (UAV) flight test is carried out. Based on the reference information from the high-precision GPS device, the results illustrate the effectiveness of the scheme in error correction of INS and the algorithm in place recognition. Full article

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19 pages, 11269 KiB

Open AccessArticle

Distributed Kernel Extreme Learning Machines for Aircraft Engine Failure Diagnostics

by Junjie Lu, Jinquan Huang and Feng Lu

Appl. Sci. 2019, 9(8), 1707; https://doi.org/10.3390/app9081707 - 25 Apr 2019

Cited by 15 | Viewed by 3032

Abstract

Kernel extreme learning machine (KELM) has been widely studied in the field of aircraft engine fault diagnostics due to its easy implementation. However, because its computational complexity is proportional to the training sample size, its application in time-sensitive scenarios is limited. Therefore, in [...] Read more.

Kernel extreme learning machine (KELM) has been widely studied in the field of aircraft engine fault diagnostics due to its easy implementation. However, because its computational complexity is proportional to the training sample size, its application in time-sensitive scenarios is limited. Therefore, in the case of largescale samples, the original KELM is difficult to meet the real-time requirements of aircraft engine onboard condition. To address this shortcoming, a novel distributed kernel extreme learning machines (DKELMs) algorithm is proposed in this paper. The distributed subnetwork is adopted to reduce the computational complexity, and then the likelihood probability and Dempster-Shafer (DS) evidence theory is used to design the fusion scheme to ensure the accuracy after fusion is not reduced. Afterwards, the verification on the benchmark datasets shows that the algorithm can greatly reduce the computational complexity and improve the real-time performance of the original KELM algorithm without sacrificing the accuracy of the model. Finally, the performance estimation and fault pattern recognition experiments of an aircraft engine show that, compared with the original KELM algorithm and support vector machine (SVM) algorithm, the proposed algorithm has the best performance considering both real-time capability and model accuracy. Full article

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

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19 pages, 1697 KiB

Open AccessArticle

Characterization and Determination of the Toxicological Risk of Biochar Using Invertebrate Toxicity Tests in the State of Aguascalientes, México

by Felix Flesch, Pia Berger, Daniel Robles-Vargas, Gustavo Emilio Santos-Medrano and Roberto Rico-Martínez

Appl. Sci. 2019, 9(8), 1706; https://doi.org/10.3390/app9081706 - 25 Apr 2019

Cited by 16 | Viewed by 4396

Abstract

Following a quantitative analysis of adequate feedstock, comprising 11 woody biomass species, four biochars were generated using a Kon-Tiki flame curtain kiln in the state of Aguascalientes, Mexico. Despite the high quality (certified by European Biochar Certificate), the biochars contain substantial quantities of [...] Read more.

Following a quantitative analysis of adequate feedstock, comprising 11 woody biomass species, four biochars were generated using a Kon-Tiki flame curtain kiln in the state of Aguascalientes, Mexico. Despite the high quality (certified by European Biochar Certificate), the biochars contain substantial quantities of hazardous substances, such as polycyclic aromatic hydrocarbons, polychlorinated dibenzo-p-dioxins and dibenzofurans, polychlorinated biphenyls, and heavy metals, which can induce adverse effects if wrongly applied to the environment. To assess the toxicity of biochars to non-target organisms, toxicity tests with four benthic and zooplanktonic invertebrate species, the ciliate Paramecium caudatum, the rotifer Lecane quadridentata, and the cladocerans Daphnia magna and Moina macrocopa were performed using biochar elutriates. In acute and chronic toxicity tests, no acute toxic effect to ciliates, but significant lethality to rotifers and cladocerans was detected. This lethal toxicity might be due to ingestion/digestion by enzymatic/mechanic processes of biochar by cladocerans and rotifers of toxic substances present in the biochar. No chronic toxicity was found where biochar elutriates were mixed with soil. These data indicate that it is instrumental to use toxicity tests to assess biochars’ toxicity to the environment, especially when applied close to sensitive habitats, and to stick closely to the quantitative set-point values. Full article

(This article belongs to the Special Issue Biochar: Productions, Properties and Applications)

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17 pages, 4499 KiB

Open AccessArticle

Effect of Intercritical Quenching Temperature of Cu-Containing Low Alloy Steel of Long Part Forging for Offshore Applications

by Yuta Honma, Gen Sasaki and Kunihiko Hashi

Appl. Sci. 2019, 9(8), 1705; https://doi.org/10.3390/app9081705 - 25 Apr 2019

Cited by 6 | Viewed by 2953

Abstract

In our previous study, intercritical quenching from the dual-phase region of ferrite and austenite regions, which is called lamellarizing (L) treatment, brought a clear improvement of balance between the strength and toughness of Cu-containing low alloy steel based on American Society for Testing [...] Read more.

In our previous study, intercritical quenching from the dual-phase region of ferrite and austenite regions, which is called lamellarizing (L) treatment, brought a clear improvement of balance between the strength and toughness of Cu-containing low alloy steel based on American Society for Testing and Materials (ASTM) A707 5L grade. Moreover, the results imply that the reverse transformation behavior during L treatment is very important in order to optimize the L treatment temperature. Hence, the purpose of this paper is to clarify the mechanism by which L treatment improves the mechanical properties in terms of reverse transformation behavior. Additionally, offshore structures require good weldability, because the structures generally have a lot of weld joints. Therefore, weldability was also investigated in this study. The investigation revealed that coarse Cu precipitates are observed in the not-transformed α phase, so the strength tendency in relation to the L treatment temperature is relevant to the area ratio of the not-transformed α phase and the transformed γ phase during L treatment. From the in situ electron back scatter diffraction (EBSD) results, it is believed to be possible to enhance the mechanical properties of Cu-containing low alloy steel by controlling the area ratio of the reverse-transformed gamma phase and selecting the appropriate L treatment temperature. Furthermore, the long part forging of Cu-containing low alloy steel has a good weldability, since the maximum hardness of the heat-affected zone (HAZ) is less than 300 HV, and the HAZ of steel has a good crack tip opening displacement (CTOD) property with less than 2.3 kJ/mm of heat input of GTAW. Full article

(This article belongs to the Special Issue Recent Trends in Advanced High-Strength Steels)

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11 pages, 1642 KiB

Open AccessArticle

Synthesis, Tyrosinase Inhibiting Activity and Molecular Docking of Fluorinated Pyrazole Aldehydes as Phosphodiesterase Inhibitors

by Vesna Rastija, Harshad Brahmbhatt, Maja Molnar, Melita Lončarić, Ivica Strelec, Mario Komar and Valentina Pavić

Appl. Sci. 2019, 9(8), 1704; https://doi.org/10.3390/app9081704 - 25 Apr 2019

Cited by 4 | Viewed by 3731

Abstract

A series of fluorinated 4,5-dihydro-1H-pyrazole derivatives were synthesized in the reaction of corresponding acetophenone and different aldehydes followed by the second step synthesis of desired compounds from synthesized chalcone, hydrazine hydrate, and formic acid. Structures of all compounds were confirmed by [...] Read more.

A series of fluorinated 4,5-dihydro-1H-pyrazole derivatives were synthesized in the reaction of corresponding acetophenone and different aldehydes followed by the second step synthesis of desired compounds from synthesized chalcone, hydrazine hydrate, and formic acid. Structures of all compounds were confirmed by both ¹H and ¹³C NMR and mass spectrometry. Antibacterial properties of compounds were tested on four bacterial strains, Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus. Among synthesized compounds, the strongest inhibitor of monophenolase activity of mushroom tyrosinase (32.07 ± 3.39%) was found to be 5-(2-chlorophenyl)-3-(4-fluorophenyl)-4,5-dihydro-1H-pyrazole-1-carbaldehyde. The PASS program has predicted the highest probable activity for the phosphodiesterase inhibition. To shed light on molecular interactions between the synthesized compounds and phosphodiesterase, all compounds were docked into the active binding site. The obtained results showed that the compound with the dimethoxyphenyl ring could be potent as an inhibitor of phosphodiesterase, which interacts in PDE5 catalytic domain of the enzyme. Key interactions are bidentate hydrogen bond (H-bond) with the side-chain of Gln817 and van der Waals interactions of the dimethoxyphenyl ring and pyrazole ring with hydrophobic clamp, which contains residuals, Val782, Phe820, and Tyr612. Interactions are similar to the binding mode of the inhibitor sildenafil, the first oral medicine for the treatment of male erectile dysfunction. Full article

(This article belongs to the Special Issue The Design, Synthesis, and Biological Evaluation of Compounds with Medicinal Value)

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20 pages, 20442 KiB

Open AccessArticle

Quantitative Assessment of the Environmental Impacts of Dredging and Dumping Activities at Sea

by Doan Quang Tri, Jaya Kandasamy and Nguyen Cao Don

Appl. Sci. 2019, 9(8), 1703; https://doi.org/10.3390/app9081703 - 25 Apr 2019

Cited by 6 | Viewed by 3804

Abstract

The dumping of dredge materials often raises concerns about the release of pollutants to the marine environment. Wind data from the Global Forecast System (GFS) model was used to simulate the wind-wave propagation from offshore in a two-dimensional (2D) model during September and [...] Read more.

The dumping of dredge materials often raises concerns about the release of pollutants to the marine environment. Wind data from the Global Forecast System (GFS) model was used to simulate the wind-wave propagation from offshore in a two-dimensional (2D) model during September and October 2016. The calibration and validation of the 2D model showed a high conformity in both the phases and amplitude between the observed and simulated data. The 2D mud transport simulation results of three scenarios showed that the concentration of suspended material in the third scenario tested (scenario 3) was greater than 0.004 kg/m³ in the low tide, spreading to a 9 km² area, and in the high tide, the concentration was 0.004 kg/m³ in a 6 km² area. Finally, the results of 2D particle tracking (PT) showed changes in the seabed due to the concentration of dredged material, and its dump (approximately 180 days) increased from 0.08 m to 0.16 m in 2.85 ha. In scenario 3, the element block moved quite far—approximately 2.9 km—from the dredge position. Therefore, the simulation results were qualified, as the dredging position situated far from the sea is significantly affected by the direction and velocity of wave-wind in the dredging position. Full article

(This article belongs to the Special Issue Coastal Deposits: Environmental Implications, Mathematical Modeling and Technological Development)

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23 pages, 24190 KiB

Open AccessArticle

Robot Swarm Navigation and Victim Detection Using Rendezvous Consensus in Search and Rescue Operations

by Gustavo A. Cardona and Juan M. Calderon

Appl. Sci. 2019, 9(8), 1702; https://doi.org/10.3390/app9081702 - 25 Apr 2019

Cited by 67 | Viewed by 7560

Abstract

Cooperative behaviors in multi-robot systems emerge as an excellent alternative for collaboration in search and rescue tasks to accelerate the finding survivors process and avoid risking additional lives. Although there are still several challenges to be solved, such as communication between agents, power [...] Read more.

Cooperative behaviors in multi-robot systems emerge as an excellent alternative for collaboration in search and rescue tasks to accelerate the finding survivors process and avoid risking additional lives. Although there are still several challenges to be solved, such as communication between agents, power autonomy, navigation strategies, and detection and classification of survivors, among others. The research work presented by this paper focuses on the navigation of the robot swarm and the consensus of the agents applied to the victims detection. The navigation strategy is based on the application of particle swarm theory, where the robots are the agents of the swarm. The attraction and repulsion forces that are typical in swarm particle systems are used by the multi-robot system to avoid obstacles, keep group compact and navigate to a target location. The victims are detected by each agent separately, however, once the agents agree on the existence of a possible victim, these agents separate from the general swarm by creating a sub-swarm. The sub-swarm agents use a modified rendezvous consensus algorithm to perform a formation control around the possible victims and then carry out a consensus of the information acquired by the sensors with the aim to determine the victim existence. Several experiments were conducted to test navigation, obstacle avoidance, and search for victims. Additionally, different situations were simulated with the consensus algorithm. The results show how swarm theory allows the multi-robot system navigates avoiding obstacles, finding possible victims, and settling down their possible use in search and rescue operations. Full article

(This article belongs to the Special Issue Advanced Mobile Robotics)

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14 pages, 1634 KiB

Open AccessArticle

Application of Quasi-Phase Matching Concept for Enhancement of High-Order Harmonics of Ultrashort Laser Pulses in Plasmas

by R. A. Ganeev, S. Y. Stremoukhov, A. V. Andreev and A. S. Alnaser

Appl. Sci. 2019, 9(8), 1701; https://doi.org/10.3390/app9081701 - 25 Apr 2019

Cited by 14 | Viewed by 3077

Abstract

Novel methods of coherent short-wavelength sources generation require thorough analysis for their further amendments and practical implementations. In this work, we report on the quasi-phase matching (QPM) of high-order harmonics generation during the propagation of single- and two-color femtosecond pulses through multi-jet plasmas, [...] Read more.

Novel methods of coherent short-wavelength sources generation require thorough analysis for their further amendments and practical implementations. In this work, we report on the quasi-phase matching (QPM) of high-order harmonics generation during the propagation of single- and two-color femtosecond pulses through multi-jet plasmas, which allows the enhancement of groups of harmonics in different ranges of extreme ultraviolet. The role of the number of coherent zones; sizes of plasma jets and the distance between them; plasma formation conditions, and the characteristics of the fundamental radiation on the harmonic efficiency at quasi-phase matching (QPM) conditions are analyzed. We demonstrate the ~40× enhancement factor of the maximally-enhanced harmonic with respect to the one generated at ordinary conditions in the imperforated plasma. Full article

(This article belongs to the Special Issue Ultrafast Laser Pulses)

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19 pages, 2089 KiB

Open AccessFeature PaperReview

A Way towards Reliable Predictive Methods for the Prediction of Physicochemical Properties of Chemicals Using the Group Contribution and other Methods

by Robert J. Meier

Appl. Sci. 2019, 9(8), 1700; https://doi.org/10.3390/app9081700 - 24 Apr 2019

Cited by 5 | Viewed by 3200

Abstract

Physicochemical properties of chemicals as referred to in this review include, for example, thermodynamic properties such as heat of formation, boiling point, toxicity of molecules and the fate of molecules whenever undergoing or accelerating (catalytic) a chemical reaction and therewith about chemical equilibrium, [...] Read more.

Physicochemical properties of chemicals as referred to in this review include, for example, thermodynamic properties such as heat of formation, boiling point, toxicity of molecules and the fate of molecules whenever undergoing or accelerating (catalytic) a chemical reaction and therewith about chemical equilibrium, that is, the equilibrium in chemical reactions. All such properties have been predicted in literature by a variety of methods. However, for the experimental scientist for whom such predictions are of relevance, the accuracies are often far from sufficient for reliable application We discuss current practices and suggest how one could arrive at better, that is sufficiently accurate and reliable, predictive methods. Some recently published examples have shown this to be possible in practical cases. In summary, this review focuses on methodologies to obtain the required accuracies for the chemical practitioner and process technologist designing chemical processes. Finally, something almost never explicitly mentioned is the fact that whereas for some practical cases very accurate predictions are required, for other cases a qualitatively correct picture with relatively low correlation coefficients can be sufficient as a valuable predictive tool. Requirements for acceptable predictive methods can therefore be significantly different depending on the actual application, which are illustrated using real-life examples, primarily with industrial relevance. Furthermore, for specific properties such as the octanol-water partition coefficient more close collaboration between research groups using different methods would greatly facilitate progress in the field of predictive modelling. Full article

(This article belongs to the Special Issue Models for Predicting the Thermodynamic Data Necessary for Process Design)

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11 pages, 2109 KiB

Open AccessArticle

A Correction Method of Mixed Pesticide Content Prediction in Apple by Using Raman Spectra

by Yan Li, Yankun Peng, Jianwei Qin and Kuanglin Chao

Appl. Sci. 2019, 9(8), 1699; https://doi.org/10.3390/app9081699 - 24 Apr 2019

Cited by 3 | Viewed by 2829

Abstract

In the study, a new correction method was applied to reduce error during Raman spectral detection on mixed pesticide residue in apples. Combined with self-built pesticide residues detection system by Raman spectroscopy and the application of surface enhancement technology, rapid real-time qualitative and [...] Read more.

In the study, a new correction method was applied to reduce error during Raman spectral detection on mixed pesticide residue in apples. Combined with self-built pesticide residues detection system by Raman spectroscopy and the application of surface enhancement technology, rapid real-time qualitative and quantitative analysis of deltamethrin and acetamiprid residues in apples could be applied effectively. In quantitative analysis, compared with the intensity value of characteristic peaks of single pesticide with same concentration, the intensity value of characteristic peaks of the two pesticides decreased after mixing the pesticides, which affected the results severely. By comparing the difference in the intensity of characteristic peaks of single and mixed pesticides, a correction method was proposed to eliminate the influence of pesticides mixture. Characteristic peak intensity values of gradient concentration pesticide from 100 mg·kg⁻¹ to 10⁻³ mg·kg⁻¹ and Lagrangian interpolation were applied in the correction method. And a smooth surface was applied to describe the correction coefficient of characteristic peak intensity. Through detecting the characteristic peak intensity values of the mixed pesticide, correction coefficient would be obtained. Then real values of the peak intensity of pesticides and the content of each component of the mixed pesticide would be acquired by the correction method. Correlation coefficient of model validation exceeded 0.88 generally and Root Mean Square Error also decreased obviously after correction, which proved the reliability of the method. Full article

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

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27 pages, 11391 KiB

Open AccessArticle

Transient Temperature Field Model of Wear Land on the Flank of End Mills: A Focus on Time-Varying Heat Intensity and Time-Varying Heat Distribution Ratio

by Jianbiao Du, Caixu Yue, Xianli Liu, Steven Y. Liang, Lihui Wang, Haining Gao and Hengshuai Li

Appl. Sci. 2019, 9(8), 1698; https://doi.org/10.3390/app9081698 - 24 Apr 2019

Cited by 5 | Viewed by 3341

Abstract

Modelling methods for the transient temperature field of wear land on the flank of end mills have been proposed to address the challenges of inaccurate prediction in the temperature field of end mills during the high-speed peripheral milling of Ti6Al4V that is a [...] Read more.

Modelling methods for the transient temperature field of wear land on the flank of end mills have been proposed to address the challenges of inaccurate prediction in the temperature field of end mills during the high-speed peripheral milling of Ti6Al4V that is a titanium alloy. A transient temperature rise model of wear land on the flank of end mills was constructed under the influence of heat sources in the primary shearing zone (PSZ), rake-chip zone (RCZ), flank-workpiece zone (FWZ), and dissipating heat source. Then the transient temperature field model of wear land on the flank of end mills was constructed. Finally, the transient temperature field model of wear land on the flank of end mills was constructed. Comparison of simulation result and experimental data verified the accuracy of the model. In sum, the proposed model may provide a temperature model support for future studies of flank wear rate in end mill modeling. Full article

(This article belongs to the Section Mechanical Engineering)

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14 pages, 5418 KiB

Open AccessArticle

Automatic Association of Scents Based on Visual Content

by Amany Al Luhaybi, Fahad Alqurashi, Georgios Tsaramirsis and Seyed M. Buhari

Appl. Sci. 2019, 9(8), 1697; https://doi.org/10.3390/app9081697 - 24 Apr 2019

Cited by 7 | Viewed by 3336

Abstract

Although olfaction can enhance the user’s experience in virtual environments, the approach is not widely utilized by virtual contents. This is because the olfaction displays are either not aware of the content in the virtual world or they are application specific. Enabling wide [...] Read more.

Although olfaction can enhance the user’s experience in virtual environments, the approach is not widely utilized by virtual contents. This is because the olfaction displays are either not aware of the content in the virtual world or they are application specific. Enabling wide context awareness is possible through the use of image recognition via machine learning. Screenshots from the virtual worlds can be analyzed for the presence of virtual scent emitters, allowing the olfactory display to respond by generating the corresponding smells. The Convolutional Neural Network (CNN), using Inception Model for image recognition was used for training the system. To evaluate the performance of the accuracy of the model, we trained it on a computer game called Minecraft. The results and performance of the model was 97% accurate, while in some cases the accuracy reached 99%. Full article

(This article belongs to the Special Issue Augmented Reality: Current Trends, Challenges and Prospects)

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15 pages, 5934 KiB

Open AccessArticle

Fault Diagnosis of a Helical Gearbox Based on an Adaptive Empirical Wavelet Transform in Combination with a Spectral Subtraction Method

by Peng Wang and Chang-Myung Lee

Appl. Sci. 2019, 9(8), 1696; https://doi.org/10.3390/app9081696 - 24 Apr 2019

Cited by 13 | Viewed by 3589

Abstract

Fault characteristic extraction is attracting a great deal of attention from researchers for the fault diagnosis of rotating machinery. Generally, when a gearbox is damaged, accurate identification of the side-band features can be used to detect the condition of the machinery equipment to [...] Read more.

Fault characteristic extraction is attracting a great deal of attention from researchers for the fault diagnosis of rotating machinery. Generally, when a gearbox is damaged, accurate identification of the side-band features can be used to detect the condition of the machinery equipment to reduce financial losses. However, the side-band feature of damaged gears that are constantly disturbed by strong jamming is embedded in the background noise. In this paper, a hybrid signal-processing method is proposed based on a spectral subtraction (SS) denoising algorithm combined with an empirical wavelet transform (EWT) to extract the side-band feature of gear faults. Firstly, SS is used to estimate the real-time noise information, which is used to enhance the fault signal of the helical gearbox from a vibration signal with strong noise disturbance. The empirical wavelet transform can extract amplitude-modulated/frequency-modulated (AM-FM) components of a signal using different filter bands that are designed in accordance with the signal properties. The fault signal is obtained by building a flexible gear for a helical gearbox with ADAMS software. The experiment shows the feasibility and availability of the multi-body dynamics model. The spectral subtraction-based adaptive empirical wavelet transform (SS-AEWT) method was applied to estimate the gear side-band feature for different tooth breakages and the strong background noise. The verification results show that the proposed method gives a clearer indication of gear fault characteristics with different tooth breakages and the different signal-noise ratio (SNR) than the conventional EMD and LMD methods. Finally, the fault characteristic frequency of a damaged gear suggests that the proposed SS-AEWT method can accurately and reliably diagnose faults of a gearbox. Full article

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17 pages, 2911 KiB

Open AccessArticle

Timbre Preferences in the Context of Mixing Music

by Felix A. Dobrowohl, Andrew J. Milne and Roger T. Dean

Appl. Sci. 2019, 9(8), 1695; https://doi.org/10.3390/app9081695 - 24 Apr 2019

Cited by 5 | Viewed by 3594

Abstract

Mixing music is a highly complex task. This is exacerbated by the fact that timbre perception is still poorly understood. As a result, few studies have been able to pinpoint listeners’ preferences in terms of timbre. In order to investigate timbre preference in [...] Read more.

Mixing music is a highly complex task. This is exacerbated by the fact that timbre perception is still poorly understood. As a result, few studies have been able to pinpoint listeners’ preferences in terms of timbre. In order to investigate timbre preference in a music production context, we let participants mix multiple individual parts of musical pieces (bassline, harmony, and arpeggio parts, all sounded with a synthesizer) by adjusting four specific timbral attributes of the synthesizer (lowpass, sawtooth/square wave oscillation blend, distortion, and inharmonicity). After participants mixed all parts of a musical piece, they were asked to rate multiple mixes of the same musical piece. Listeners showed preferences for their own mixes over random, fixed sawtooth, or expert mixes. However, participants were unable to identify their own mixes. Despite not being able to accurately identify their own mixes, participants consistently preferred the mix they thought to be their own, regardless of whether or not this mix was indeed their own. Correlations and cluster analysis of the participants’ mixing settings show most participants behaving independently in their mixing approaches and one moderate sized cluster of participants who are actually rather similar. In reference to the starting-settings, participants applied the biggest changes to the sound with the inharmonicity manipulation (measured in the perceptual distance) despite often mentioning that they do not find this manipulation particularly useful. The results show that listeners have a consistent, yet individual timbre preference and are able to reliably evoke changes in timbre towards their own preferences. Full article

(This article belongs to the Special Issue Psychoacoustic Engineering and Applications)

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19 pages, 6099 KiB

Open AccessArticle

Labeling Strategy for Evaluating the Performance of Thin Asphalt Wearing Courses

by Lívia Garcia-Gil and Rodrigo Miró

Appl. Sci. 2019, 9(8), 1694; https://doi.org/10.3390/app9081694 - 24 Apr 2019

Cited by 2 | Viewed by 2551

Abstract

Traditional design procedures of asphalt mixtures are based on volumetric parameters and the compliance with the mechanical performance, while functional properties receive less attention. Additionally, even though the potential of sustainable technologies is proven, this is not sufficiently reflected in the technical specifications [...] Read more.

Traditional design procedures of asphalt mixtures are based on volumetric parameters and the compliance with the mechanical performance, while functional properties receive less attention. Additionally, even though the potential of sustainable technologies is proven, this is not sufficiently reflected in the technical specifications and their use is not widely spread. In order to face these challenges, the development of a useful tool that allows infrastructure managers an easy evaluation of the mechanical, functional, and environmental performance and the pursuit of balance between properties will encourage the optimization of road surfaces. The aim of this research is to develop a multi-labeling scheme for asphalt mixtures for thin wearing courses according to their mechanical, functional, and environmental attributes. In particular, the study focuses on the Spanish case, because all the collected data belong to the Spanish road network; however, the approached methodology is flexible enough to be adjusted to the requirements of individual countries. The findings in this research show promise because the developed labeling scheme allows not only the assignation of performance labels to any asphalt mixture based on its properties, but also the comparison of features between different asphalt mixtures. Full article

(This article belongs to the Special Issue Asphalt Materials)

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13 pages, 8610 KiB

Open AccessArticle

A New Ultrasound Speckle Reduction Algorithm Based on Superpixel Segmentation and Detail Compensation

by Yang Chen, Ming Zhang, Hong-Mei Yan, Yong-Jie Li and Kai-Fu Yang

Appl. Sci. 2019, 9(8), 1693; https://doi.org/10.3390/app9081693 - 24 Apr 2019

Cited by 6 | Viewed by 3719

Abstract

Speckle is a kind of noise commonly found in ultrasound images (UIs). Although traditional local operation-based methods, such as bilateral filtering, perform well in de-noising normal natural images with suitable parameters, these methods may break local correlations and, hence, their performance will be [...] Read more.

Speckle is a kind of noise commonly found in ultrasound images (UIs). Although traditional local operation-based methods, such as bilateral filtering, perform well in de-noising normal natural images with suitable parameters, these methods may break local correlations and, hence, their performance will be highly degraded when applied to UIs with high levels of speckle noise. In this work, we propose a new method, based on superpixel segmentation and detail compensation, to reduce UI speckle noise. In particular, considering that superpixel segmentation has the advantage of adhering accurately to the boundaries of objects or local structures, we propose a superpixel version of bilateral filtering to better protect the local structure during de-noising. Additionally, a human visual system (HVS)-inspired strategy for spatial compensation is introduced, in order to recover sophisticated edges as much as possible while weakening the high-frequency noise. Experiments on synthetic images and real UIs of different organs show that, compared to other methods, the proposed strategy can reduce ultrasound speckle noise more effectively. Full article

(This article belongs to the Section Optics and Lasers)

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16 pages, 8565 KiB

Open AccessArticle

The Causal Connection between CO₂ Emissions and Agricultural Productivity in Pakistan: Empirical Evidence from an Autoregressive Distributed Lag Bounds Testing Approach

by Abdul Rehman, Ilhan Ozturk and Deyuan Zhang

Appl. Sci. 2019, 9(8), 1692; https://doi.org/10.3390/app9081692 - 24 Apr 2019

Cited by 82 | Viewed by 6065

Abstract

The rapid agricultural development and mechanization of agronomic diligence has led to a significant growth in energy consumption and CO₂ emission. Agriculture has a dominant contribution to boosting the economy of any country. In this paper, we demonstrate carbon dioxide emissions’ association [...] Read more.

The rapid agricultural development and mechanization of agronomic diligence has led to a significant growth in energy consumption and CO₂ emission. Agriculture has a dominant contribution to boosting the economy of any country. In this paper, we demonstrate carbon dioxide emissions’ association with cropped area, energy use, fertilizer offtake, gross domestic product per capita, improved seed distribution, total food grains and water availability in Pakistan for the period of 1987-2017. We employed Augmented Dickey-Fuller and Phillips-Perron unit root tests to examine the variables’ stationarity. An autoregressive distributed lag (ARDL) bounds testing technique to cointegration was applied to demonstrate the causality linkage among study variables from the evidence of long-run and short-run analyses. The long-run evidence reveals that cropped area, energy usage, fertilizer offtake, gross domestic product per capita and water availability have a positive and significant association with carbon dioxide emissions, while the analysis results of improved seed distribution and total food grains have a negative association with carbon dioxide emissions in Pakistan. Overall, the long-run effects are stronger than the short-run dynamics, in terms of the impact of explanatory variables on carbon dioxide emission, thus making the findings heterogeneous. Possible initiatives should be taken by the government of Pakistan to improve the agriculture sector and also introduce new policies to reduce the emissions of carbon dioxide. Full article

(This article belongs to the Section Applied Biosciences and Bioengineering)

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