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Appl. Sci., Volume 9, Issue 3 (February-1 2019)

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Open AccessArticle Effective Crack Damage Detection Using Multilayer Sparse Feature Representation and Incremental Extreme Learning Machine
Appl. Sci. 2019, 9(3), 614; https://doi.org/10.3390/app9030614
Received: 16 December 2018 / Revised: 28 January 2019 / Accepted: 3 February 2019 / Published: 12 February 2019
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Abstract
Detecting cracks within reinforced concrete is still a challenging problem, owing to the complex disturbances from the background noise. In this work, we advocate a new concrete crack damage detection model, based upon multilayer sparse feature representation and an incremental extreme learning machine [...] Read more.
Detecting cracks within reinforced concrete is still a challenging problem, owing to the complex disturbances from the background noise. In this work, we advocate a new concrete crack damage detection model, based upon multilayer sparse feature representation and an incremental extreme learning machine (ELM), which has both favorable feature learning and classification capabilities. Specifically, by cropping and using a sliding window operation and image rotation, a large number of crack and non-crack patches are obtained from the collected concrete images. With the existing image patches, the defect region features can be quickly calculated by the multilayer sparse ELM autoencoder networks. Then, the online incremental ELM classified network is used to recognize the crack defect features. Unlike the commonly-used deep learning-based methods, the presented ELM-based crack detection model can be trained efficiently without tediously fine-tuning the entire-network parameters. Moreover, according to the ELM theory, the proposed crack detector works universally for defect feature extraction and detection. In the experiments, when compared with other recently developed crack detectors, the proposed concrete crack detection model can offer outstanding training efficiency and favorable crack detecting accuracy. Full article
(This article belongs to the Special Issue Advanced Intelligent Imaging Technology)
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Open AccessArticle A Stochastic Deterioration Process Based Approach for Micro Switches Remaining Useful Life Estimation
Appl. Sci. 2019, 9(3), 613; https://doi.org/10.3390/app9030613
Received: 25 December 2018 / Revised: 29 January 2019 / Accepted: 8 February 2019 / Published: 12 February 2019
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Abstract
Real-time prediction of remaining useful life (RUL) is one of the most essential works in prognostics and health management (PHM) of the micro-switches. In this paper, a linear degradation model based on an inverse Kalman filter to imitate the stochastic deterioration process is [...] Read more.
Real-time prediction of remaining useful life (RUL) is one of the most essential works in prognostics and health management (PHM) of the micro-switches. In this paper, a linear degradation model based on an inverse Kalman filter to imitate the stochastic deterioration process is proposed. First, Bayesian posterior estimation and expectation maximization (EM) algorithm are used to estimate the stochastic parameters. Second, an inverse Kalman filter is delivered to solve the errors in the initial parameters. In order to improve the accuracy of estimating nonlinear data, the strong tracking filtering (STF) method is used on the basis of Bayesian updating Third, the effectiveness of the proposed approach is validated on an experimental data relating to micro-switches for the rail vehicle. Additionally, it proposes another two methods for comparison to illustrate the effectiveness of the method with an inverse Kalman filter in this paper. In conclusion, a linear degradation model based on an inverse Kalman filter shall deal with errors in RUL estimation of the micro-switches excellently. Full article
(This article belongs to the Special Issue Fault Detection and Diagnosis in Mechatronics Systems)
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Open AccessArticle Microencapsulation of Tomato (Solanum lycopersicum L.) Pomace Ethanolic Extract by Spray Drying: Optimization of Process Conditions
Appl. Sci. 2019, 9(3), 612; https://doi.org/10.3390/app9030612
Received: 15 January 2019 / Revised: 6 February 2019 / Accepted: 9 February 2019 / Published: 12 February 2019
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Abstract
Microencapsulation by spray-drying is a process used in the stabilization of active compounds from various natural sources, such as tomato by-products, with the purpose to be used as additives in the food industry. The aim of this work was to study the effects [...] Read more.
Microencapsulation by spray-drying is a process used in the stabilization of active compounds from various natural sources, such as tomato by-products, with the purpose to be used as additives in the food industry. The aim of this work was to study the effects of wall material and spray drying conditions on physicochemical properties of microcapsules loaded with lycopene rich extract from tomato pomace. The assays were carried out with ethanolic tomato pomace extract as core material and arabic gum or inulin as wall materials. A central composite rotatable design was used to evaluate the effect of drying air inlet temperature (110–200 °C) and concentration of arabic gum (5–35 wt %) or inulin (5–25 wt %) on the antioxidant activity, encapsulation efficiency, loading capacity, and drying yield. SEM images showed that the produced particles were in the category of skin-forming structures. The most suitable conditions, within the ranges studied, to obtain lycopene loaded microparticles were a biopolymer concentration of 10 wt % for both materials and an inlet temperature of 200 and 160 °C for arabic gum and inulin, respectively. Arabic gum and inulin possessed a good performance in the encapsulation of tomato pomace extract by spray drying. It is envisaged that the capsules produced have good potential to be incorporated in foods systems with diverse chemical and physical properties. Full article
(This article belongs to the Special Issue Synthesis and Application of Microcapsules)
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Open AccessArticle Development of Multi-Staged Adaptive Filtering Algorithm for Periodic Structure-Based Active Vibration Control System
Appl. Sci. 2019, 9(3), 611; https://doi.org/10.3390/app9030611
Received: 27 January 2019 / Revised: 7 February 2019 / Accepted: 9 February 2019 / Published: 12 February 2019
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Abstract
A digital adaptive filtering system is applied to various fields such as current disturbance, noise cancellation, and active vibration and noise control. The least mean squares (LMS) algorithm is widely adopted, owing to its simplicity and low computational burden. A limitation of the [...] Read more.
A digital adaptive filtering system is applied to various fields such as current disturbance, noise cancellation, and active vibration and noise control. The least mean squares (LMS) algorithm is widely adopted, owing to its simplicity and low computational burden. A limitation of the LMS algorithm with fixed step size is the trade-off between convergence speed and stability. Several studies have tried to overcome this limitation by varying the step size according to filter input and error; however, the related algorithms with variable step size have not been suitable for signals with complex frequency spectra. As the error decreases, the quality of the output signal deteriorates due to the increase in the higher-order components, depending on the characteristics of the algorithm. Therefore, a novel adaptive filtering algorithm was proposed to overcome these drawbacks. It increased the stability of the system by decreasing the step size using an exponential function. In addition, the error was reduced through normalization using the power of the input signal in the initial state, and the misadjustments in the system were adjusted properly by introducing an energy autocorrelation function of instantaneous error. Furthermore, a novel multi-staged adaptive LMS (MSA-LMS) algorithm was introduced and applied to active periodic structures. The proposed algorithm was validated by simulation and observed to be superior to the conventional LMS algorithms. The results of this study can be applied to active control systems for the reduction of vibration and noise signals with complex spectra in next-generation powertrains, such as hybrid and electric vehicles. Full article
(This article belongs to the Special Issue Active and Passive Noise Control)
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Open AccessArticle Generation and Propagation of a Hermite-Gaussian Correlated Schell-Model LG0l Beam
Appl. Sci. 2019, 9(3), 610; https://doi.org/10.3390/app9030610
Received: 4 January 2019 / Revised: 2 February 2019 / Accepted: 8 February 2019 / Published: 12 February 2019
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Abstract
A partially coherent beam under the combined action of a Hermite-Gaussian correlated function and vortex phase, named the HGCSMLG0l beam has been explored both theoretically and experimentally. The statistical properties, such as the intensity and distribution of the degree of coherence [...] Read more.
A partially coherent beam under the combined action of a Hermite-Gaussian correlated function and vortex phase, named the HGCSMLG0l beam has been explored both theoretically and experimentally. The statistical properties, such as the intensity and distribution of the degree of coherence (DOC) on propagation are analyzed in detail, based on the deduced equations. We find that the intensity is determined dominantly by the non-conventional correlated function when the coherence length is comparatively small and by vortex phase when the coherence length is large. The modulus of the DOC is not vulnerable to coherence width, rather, it is affected by both non-conventional correlated function and vortex phase. Our results are verified well by the experiment results. Full article
(This article belongs to the Special Issue Recent Advances in Statistical Optics and Plasmonics)
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Open AccessReview Silicon Waveguide Optical Isolator with Directly Bonded Magneto-Optical Garnet
Appl. Sci. 2019, 9(3), 609; https://doi.org/10.3390/app9030609
Received: 15 January 2019 / Revised: 31 January 2019 / Accepted: 3 February 2019 / Published: 12 February 2019
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Abstract
Silicon waveguide optical isolators were fabricated by direct bonding of magneto-optical (MO) garnet. The technique allowed efficient MO phase shift owing to the use of single-crystalline garnet and negligibly thin interlayer on the silicon core layer. A Mach–Zehnder interferometer (MZI) provided optical isolation [...] Read more.
Silicon waveguide optical isolators were fabricated by direct bonding of magneto-optical (MO) garnet. The technique allowed efficient MO phase shift owing to the use of single-crystalline garnet and negligibly thin interlayer on the silicon core layer. A Mach–Zehnder interferometer (MZI) provided optical isolation utilizing the MO phase shift. High isolation, wide bandwidth, and temperature-insensitive operations had been demonstrated by tailoring the MZI design. Also, transverse electric (TE)–transverse magnetic (TM) mode converters were integrated to control operating polarization. In this paper, we reviewed these progresses on silicon waveguide optical isolators. Full article
(This article belongs to the Special Issue Applications of Magneto-Optical Materials)
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Open AccessArticle Investigation of Hydrodynamic Forces for Floating Offshore Wind Turbines on Spar Buoys and Tension Leg Platforms with the Mooring Systems in Waves
Appl. Sci. 2019, 9(3), 608; https://doi.org/10.3390/app9030608
Received: 28 December 2018 / Revised: 1 February 2019 / Accepted: 4 February 2019 / Published: 12 February 2019
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Abstract
This study aims to develop a modularized simulation system to estimate dynamic responses of floating Offshore Wind Turbines (OWTs) based on the concepts of spar buoy and Tension Leg Platform (TLP) corresponding with two typical mooring lines. The modular system consists of the [...] Read more.
This study aims to develop a modularized simulation system to estimate dynamic responses of floating Offshore Wind Turbines (OWTs) based on the concepts of spar buoy and Tension Leg Platform (TLP) corresponding with two typical mooring lines. The modular system consists of the hydrodynamic simulator based the Cummins time domain equation, the Boundary Element Method (BEM) solver based on the 3D source distribution method, and an open-source visualization software ParaView to analyze the interaction between floating OWTs and waves. In order to realize the effects of mooring loads on the floating OWTs, the stiffness and damping matrices are applied to the quasi-static mooring system. The Response Amplitude Operators (RAOs) are compared between our predicted results and other published data to verify the modularized simulation system and understand the influence of mooring load on the motion responses in regular or irregular waves. It is also demonstrated that the quasi-static mooring system is applicable to different types of mooring lines as well as determining real-time motion responses. Eventually, wave load components at the resonance frequencies of different motion modes for selected floating OWTs would be present in the time domain. Full article
(This article belongs to the Special Issue Offshore Wind Energy)
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Open AccessArticle Fatigue Life of RC Bridge Decks Affected by Non-Uniformly Dispersed Stagnant Water
Appl. Sci. 2019, 9(3), 607; https://doi.org/10.3390/app9030607
Received: 19 January 2019 / Revised: 7 February 2019 / Accepted: 9 February 2019 / Published: 12 February 2019
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Abstract
Stagnant water on reinforced concrete (RC) decks reduces their life significantly compared to the case of dry states. Fully submerged states have been investigated as the most severe case, which is however rarely experienced in reality. Currently, it is possible to simulate concrete–water [...] Read more.
Stagnant water on reinforced concrete (RC) decks reduces their life significantly compared to the case of dry states. Fully submerged states have been investigated as the most severe case, which is however rarely experienced in reality. Currently, it is possible to simulate concrete–water interactions for lifetime prediction of RC decks. In this study, fatigue lifetime is systematically computed for various locations of stagnant water at the upper layer of RC decks. It is found that the patterns of wet and dry areas have a great influence on the remaining fatigue life even though the same magnitude of cracking develops. Then, a hazard map for the wetting locations with regard to the remaining fatigue life is presented based on the systematically arranged simulation. Finally, a nonlinear correlation is introduced for fatigue life prediction based upon site inspected wetting locations, which can be detected by non-destructive testing technology. Full article
(This article belongs to the Special Issue Fatigue and Fracture of Non-metallic Materials and Structures)
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Open AccessArticle A Frequency–Power Droop Coefficient Determination Method of Mixed Line-Commutated and Voltage-Sourced Converter Multi-Infeed, High-Voltage, Direct Current Systems: An Actual Case Study in Korea
Appl. Sci. 2019, 9(3), 606; https://doi.org/10.3390/app9030606
Received: 10 December 2018 / Revised: 7 February 2019 / Accepted: 9 February 2019 / Published: 12 February 2019
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Abstract
Among the grid service applications of high-voltage direct current (HVDC) systems, frequency–power droop control for islanded networks is one of the most widely used schemes. In this paper, a new frequency-power droop coefficient determination method for a mixed line-commutated converter (LCC) and voltage-sourced [...] Read more.
Among the grid service applications of high-voltage direct current (HVDC) systems, frequency–power droop control for islanded networks is one of the most widely used schemes. In this paper, a new frequency-power droop coefficient determination method for a mixed line-commutated converter (LCC) and voltage-sourced converter (VSC)-based multi-infeed HVDC (MIDC) system is proposed. The proposed method is designed for the minimization of power loss. An interior-point method is used as an optimization algorithm to implement the proposed scheduling method, and the droop coefficients of the HVDCs are determined graphically using the Monte Carlo sampling method. Two test systems—the modified Institute of Electrical and Electronics Engineers (IEEE) 14-bus system and an actual Jeju Island network in Korea—were utilized for MATLAB simulation case studies, to demonstrate that the proposed method is effective for reducing power system loss during frequency control. Full article
(This article belongs to the Special Issue HVDC for Grid Services in Electric Power Systems)
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Open AccessFeature PaperReview Review of 3D Imaging by Coded Aperture Correlation Holography (COACH)
Appl. Sci. 2019, 9(3), 605; https://doi.org/10.3390/app9030605
Received: 25 December 2018 / Revised: 28 January 2019 / Accepted: 30 January 2019 / Published: 12 February 2019
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Abstract
Coded aperture correlation holography (COACH) is a relatively new technique to record holograms of incoherently illuminated scenes. In this review, we survey the main milestones in the COACH topic from two main points of view. First, we review the prime architectures of optical [...] Read more.
Coded aperture correlation holography (COACH) is a relatively new technique to record holograms of incoherently illuminated scenes. In this review, we survey the main milestones in the COACH topic from two main points of view. First, we review the prime architectures of optical hologram recorders in the family of COACH systems. Second, we discuss some of the key applications of these recorders in the field of imaging in general, and for 3D super-resolution imaging, partial aperture imaging, and seeing through scattering medium, in particular. We summarize this overview with a general perspective on this research topic and its prospective directions. Full article
(This article belongs to the Special Issue Holography, 3D Imaging and 3D Display)
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Open AccessArticle A Study on Affective Dimensions to Engine Acceleration Sound Quality Using Acoustic Parameters
Appl. Sci. 2019, 9(3), 604; https://doi.org/10.3390/app9030604
Received: 3 December 2018 / Revised: 7 February 2019 / Accepted: 8 February 2019 / Published: 12 February 2019
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Abstract
The technical performance of recent automobiles is highly progressed and standardized across different manufacturers. This study seeks to derive a semantic space of engine acceleration sound quality for end users and identify the relation with sound characteristics. For this study, two affective attributes: [...] Read more.
The technical performance of recent automobiles is highly progressed and standardized across different manufacturers. This study seeks to derive a semantic space of engine acceleration sound quality for end users and identify the relation with sound characteristics. For this study, two affective attributes: ‘refined’ and ‘powerful’, and eight acoustic parameters considering revolutions per minute were used to determine the correlation coefficient for those affective attributes. In the experiment, a total of 35 automobiles were selected. Each of the 3rd gear wide open throttle sounds was recorded and evaluated by 42 adult subjects with normal hearing ability and driving license. Their subjective evaluations were analyzed using factor analysis, independent t-test, correlation analysis, and regression analysis. The prediction models for the affective dimensions show distinct differences for the revolutions per minute. From the experiment, it was confirmed that the customers’ affective response can be predicted through the acoustic parameters. In addition, it was found that the initial revolutions per minute in the accelerated condition had the greatest influence on the affective response. This study can be a useful guideline to design engine acceleration sounds that satisfy customers’ affective experience. Full article
(This article belongs to the Special Issue Psychoacoustic Engineering and Applications)
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Open AccessArticle Synthesis of Poly(methyl methacrylate) Grafted Multiwalled Carbon Nanotubes via a Combination of RAFT and Alkyne-Azide Click Reaction
Appl. Sci. 2019, 9(3), 603; https://doi.org/10.3390/app9030603
Received: 28 December 2018 / Revised: 3 February 2019 / Accepted: 4 February 2019 / Published: 12 February 2019
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Abstract
An efficient synthesis route was developed for the preparation of multiwalled carbon nanotube (MWCNT) nanohybrids using azide-terminated poly(methyl methacrylate) (PMMA) via a combination of reversible addition fragmentation chain transfer (RAFT) and the click reaction. A novel azido-functionalized chain transfer agent (DMP-N3) [...] Read more.
An efficient synthesis route was developed for the preparation of multiwalled carbon nanotube (MWCNT) nanohybrids using azide-terminated poly(methyl methacrylate) (PMMA) via a combination of reversible addition fragmentation chain transfer (RAFT) and the click reaction. A novel azido-functionalized chain transfer agent (DMP-N3) was prepared and subsequently employed to mediate the RAFT polymerizations of methyl methacrylate (MMA). The RAFT polymerizations exhibited first-order kinetics and a linear molecular weight dependence with the conversion. The kinetic results show that the grafting percentage of PMMA on the MWCNTs surface grows along with the increase of the reaction time. Even at 50 °C, the grafting rate of azide-terminated PMMA is comparatively fast in the course of the click reaction, with the alkyne groups adhered to MWCNTs in less than 24 h. The successful functionalization of PMMA onto MWCNT was proved by FTIR, while TGA was employed to calculate the grafting degree of PMMA chains (the highest GP = 21.9%). Compared with the pristine MWCNTs, a thicker diameter of the MWCNTs-g-PMMA was observed by TEM, which confirmed the grafted PMMA chain to the surface of nanotubes. Therefore, the MWCNTs-g-PMMA could be dispersed and stably suspended in water. Full article
(This article belongs to the Special Issue Multi-Walled Carbon Nanotubes)
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Open AccessArticle Step-Pulse Modulation of Gain-Switched Semiconductor Pulsed Laser
Appl. Sci. 2019, 9(3), 602; https://doi.org/10.3390/app9030602
Received: 12 December 2018 / Revised: 2 February 2019 / Accepted: 8 February 2019 / Published: 12 February 2019
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Abstract
To improve the peak power and extinction ratio and produce ultra-short pulses, a novel approach is presented in this paper offers a highly effective modulated method for a gain-switched semiconductor laser by using step-pulse signal modulation. For the purpose of single pulse output, [...] Read more.
To improve the peak power and extinction ratio and produce ultra-short pulses, a novel approach is presented in this paper offers a highly effective modulated method for a gain-switched semiconductor laser by using step-pulse signal modulation. For the purpose of single pulse output, then the effects on the output from the gain-switched semiconductor laser are studied by simulating single mode rate equation when changing the amplitude and width of the modulated signal. The results show that the proposed method can effectively accelerate the accumulation speed of the population inversion and we can acquire the output pulse with higher peak power and shorter width. Compared with the traditional rectangular wave modulation, this method is advantageous to obtain a high gain switching effect by increasing the second modulation current and reduce the pulse width to saturation at the best working point. It can be incorporated as a practical and cost-effective approach for many fields which need high extinction ratio short pulse, such as the optical time domain reflectometry. Full article
(This article belongs to the Special Issue Ultrafast Laser Pulses)
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Open AccessArticle In Vitro Probiotic Potential of Lactic Acid Bacteria Isolated from Aguamiel and Pulque and Antibacterial Activity Against Pathogens
Appl. Sci. 2019, 9(3), 601; https://doi.org/10.3390/app9030601
Received: 18 January 2019 / Revised: 1 February 2019 / Accepted: 8 February 2019 / Published: 12 February 2019
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Abstract
Probiotics can act as a natural barrier against several pathogens, such Helicobacter pylori, a bacterium linked to stomach cancer. The aim of the present study was to isolate and identify lactic acid bacteria (LAB) from pulque and aguamiel, and evaluate their probiotic [...] Read more.
Probiotics can act as a natural barrier against several pathogens, such Helicobacter pylori, a bacterium linked to stomach cancer. The aim of the present study was to isolate and identify lactic acid bacteria (LAB) from pulque and aguamiel, and evaluate their probiotic potential and antimicrobial effect on Escherichia coli, Staphylococcus aureus, and Helicobacter pylori. Ten isolates were selected and evaluated for in vitro resistance to antibiotics and gastrointestinal conditions, and antimicrobial activity against E. coli and S. aureus and the effect on H. pylori strains. 16S rRNA identification was performed. Ten potential probiotic isolates were confirmed as belonging to the genera Lactobacillus and Pediococcus. All the strains were susceptible to clinical antibiotics, except to vancomycin. Sixty percent of the isolates exhibited antimicrobial activity against E. coli and S. aureus. The growth of H. pylori ATCC 43504 was suppressed by all the LAB, and the urease activity from all the H. pylori strains was inhibited, which may decrease its chances for survival in the stomach. The results suggest that LAB isolated from pulque and aguamiel could be an option to establish a harmless relationship between the host and H. pylori, helping in their eradication therapy. Full article
(This article belongs to the Section Applied Biosciences and Bioengineering)
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Open AccessArticle Numerical Study on Dynamic-Stall Characteristics of Finite Wing and Rotor
Appl. Sci. 2019, 9(3), 600; https://doi.org/10.3390/app9030600
Received: 19 December 2018 / Revised: 4 February 2019 / Accepted: 5 February 2019 / Published: 12 February 2019
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Abstract
To study the three-dimensional effects on the dynamic-stall characteristics of a rotor blade, the unsteady flowfields of the finite wing and rotor were simulated under dynamic-stall conditions, respectively. Unsteady Reynolds-averaged Navier–Stokes (URANS) equations coupled with a third-order Roe–MUSCL spatial discretization scheme were chosen [...] Read more.
To study the three-dimensional effects on the dynamic-stall characteristics of a rotor blade, the unsteady flowfields of the finite wing and rotor were simulated under dynamic-stall conditions, respectively. Unsteady Reynolds-averaged Navier–Stokes (URANS) equations coupled with a third-order Roe–MUSCL spatial discretization scheme were chosen as the governing equations to predict the three-dimensional flowfields. It is indicated from the simulated results of a finite wing that dynamic stall would be restricted near the wing tip due to the influence of the wing-tip vortex. By comparing the simulated results of the finite wing with the spanwise flow, it is indicated that the spanwise flow would arouse vortex accumulation. Consequently, the dynamic stall is restricted near the wing root and aggravated near the wing tip. By comparing the simulated results of a rotor in forward flight, it is indicated that the dynamic stall of the rotor would be inhibited due to the effects of the spanwise flow and Coriolis force. This work fills the gap regarding the insufficient three-dimensional dynamic stall of a helicopter rotor, and could be used to guide rotor airfoil shape design in the future. Full article
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Open AccessArticle Optimizing the Preparation of Semi-Crystalline Paraffin/Poly(Urea-Formaldehyde) Microcapsules for Thermal Energy Storage
Appl. Sci. 2019, 9(3), 599; https://doi.org/10.3390/app9030599
Received: 5 January 2019 / Revised: 6 February 2019 / Accepted: 8 February 2019 / Published: 12 February 2019
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Paraffin, the most common phase change material, has been widely utilized as the core component in thermal energy storage in the form of microcapsules. In this study, semi-crystalline paraffin is capsulated into a poly(urea-formaldehyde) (PUF) shell by a two-step polymerization process. To obtain [...] Read more.
Paraffin, the most common phase change material, has been widely utilized as the core component in thermal energy storage in the form of microcapsules. In this study, semi-crystalline paraffin is capsulated into a poly(urea-formaldehyde) (PUF) shell by a two-step polymerization process. To obtain the microcapsule with good morphology and high latent heat, sodium chloride and crosslinker (a mixture of ammonium chloride and resorcinol with a weight ratio of 1:1) are incorporated and their addition amounts were optimized through differential scanning calorimetry (DSC) and SEM. The optimized microcapsules were obtained by adding 4 wt% sodium chloride, and 0.25 wt% crosslinker exhibits a diameter of several microns and a melting enthalpy of 110 J/g. This detailed study shows that sodium chloride strongly affects the morphology of paraffin emulsion by enlarging droplets, widening the size distribution, and enhancing the stability, which should be attributed to the enhancement of electric double layer strength. In addition, sodium chloride can weaken the Zeta potential of prepolymer and provides more opportunity for prepolymer to deposit on the surface of emulsion droplets. The two components in crosslinker play different roles in the polymerization process. Ammonium chloride reacts with prepolymers and reduces the pH of system, which can accelerate the curing process, while resorcinol probably participates in polymerization as a comonomer. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle Influence of ZrO2 Nanoparticles on the Microstructural Development of Cement Mortars with Limestone Aggregates
Appl. Sci. 2019, 9(3), 598; https://doi.org/10.3390/app9030598
Received: 11 December 2018 / Revised: 23 January 2019 / Accepted: 4 February 2019 / Published: 12 February 2019
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Abstract
In this research, the effect of the addition of zirconium oxide-synthesized nanoparticles on the microstructural development and the physical–mechanical properties of cement mortars with limestone aggregates was studied. Zirconia nanoparticles were synthesized using the co-precipitation method. According to XRD analysis, a mixture of [...] Read more.
In this research, the effect of the addition of zirconium oxide-synthesized nanoparticles on the microstructural development and the physical–mechanical properties of cement mortars with limestone aggregates was studied. Zirconia nanoparticles were synthesized using the co-precipitation method. According to XRD analysis, a mixture of tetragonal (t) and monoclinic (m) zirconia phases was obtained, with average crystallite sizes around 15.18 and 17.79 nm, respectively. Based on the ASTM standards, a mixture design was obtained for a coating mortar with a final sand/cement ratio of 1:2.78 and a water/cement ratio of 0.58. Control mortars and mortars with ZrO2 additions were analyzed for two stages of curing of the mortar—7 and 28 days. According to SEM analysis, mortars with ZrO2 revealed a microstructure with a high compaction degree and an increase in compressive strength of 9% on the control mortars. Due to the aggregates’ characteristics, adherence with the cement paste in the interface zone was increased. It is suggested that the reinforcing effect of ZrO2 on the mortars was caused by the effect of nucleation sites in the main phase C–S–H and the inhibition of the growth of large CH crystals, and the filler effect generated by the nanometric size of the particles. This produced a greater compaction volume, suggesting that faults are probably originated in the aggregates. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Bin2Vec: A Better Wafer Bin Map Coloring Scheme for Comprehensible Visualization and Effective Bad Wafer Classification
Appl. Sci. 2019, 9(3), 597; https://doi.org/10.3390/app9030597
Received: 3 January 2019 / Revised: 30 January 2019 / Accepted: 6 February 2019 / Published: 11 February 2019
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Abstract
A wafer bin map (WBM), which is the result of an electrical die-sorting test, provides information on which bins failed what tests, and plays an important role in finding defective wafer patterns in semiconductor manufacturing. Current wafer inspection based on WBM has two [...] Read more.
A wafer bin map (WBM), which is the result of an electrical die-sorting test, provides information on which bins failed what tests, and plays an important role in finding defective wafer patterns in semiconductor manufacturing. Current wafer inspection based on WBM has two problems: good/bad WBM classification is performed by engineers and the bin code coloring scheme does not reflect the relationship between bin codes. To solve these problems, we propose a neural network-based bin coloring method called Bin2Vec to make similar bin codes are represented by similar colors. We also build a convolutional neural network-based WBM classification model to reduce the variations in the decisions made by engineers with different expertise by learning the company-wide historical WBM classification results. Based on a real dataset with a total of 27,701 WBMs, our WBM classification model significantly outperformed benchmarked machine learning models. In addition, the visualization results of the proposed Bin2Vec method makes it easier to discover meaningful WBM patterns compared with the random RGB coloring scheme. We expect the proposed framework to improve both efficiencies by automating the bad wafer classification process and effectiveness by assigning similar bin codes and their corresponding colors on the WBM. Full article
(This article belongs to the Section Electrical, Electronics and Communications Engineering)
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Open AccessArticle Experimental Study on Mechanical Properties, Energy Dissipation Characteristics and Acoustic Emission Parameters of Compression Failure of Sandstone Specimens Containing En Echelon Flaws
Appl. Sci. 2019, 9(3), 596; https://doi.org/10.3390/app9030596
Received: 3 January 2019 / Revised: 1 February 2019 / Accepted: 5 February 2019 / Published: 11 February 2019
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Abstract
To further understand the fracture behavior of rock materials containing en echelon flaws and determine precursor information for the final collapse of damaged mineral assemblies under compression, a series of uniaxial compression experiments using a loading system, an acoustic emission system and a [...] Read more.
To further understand the fracture behavior of rock materials containing en echelon flaws and determine precursor information for the final collapse of damaged mineral assemblies under compression, a series of uniaxial compression experiments using a loading system, an acoustic emission system and a video camera was conducted on sandstone specimens containing en echelon flaws. The mechanical properties, energy dissipation characteristics and acoustic emission parameters of compression failure of selected specimens were successively analyzed. The results showed that crack initiation was accompanied by a stress drop, step-like characteristics on the energy consumption curve and increased crackling noises, which were used as early warning signals before the final collapse happened. In addition, we used the histogram statistics method and maximum likelihood method to analyze the distribution of acoustic emission energy and determined that the acoustic emission energy distributions of sandstone specimens containing en echelon flaws followed a power law. With the progress of the experiment, the optimum exponents changed in different stages and gradually decreased as failure was approached, which could also be used as an early warning signal before the final collapse happened. This paper may provide some theoretical basis for monitoring and warning about the collapse and instability of engineering rock masses containing en echelon flaws. Full article
(This article belongs to the Section Applied Physics)
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Open AccessArticle Potential of Workshop Measurement Positioning System to Measure Oscillation Frequencies of Rigid Structures
Appl. Sci. 2019, 9(3), 595; https://doi.org/10.3390/app9030595
Received: 7 November 2018 / Revised: 17 January 2019 / Accepted: 22 January 2019 / Published: 11 February 2019
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Abstract
A workshop measuring and positioning system (wMPS) is a large three-dimensional (3D) coordinate-measurement system based on optoelectronic scanning. It is capable of large-range coverage, high measurement accuracy and frequency, and multi-task synchronous measurement. Existing geodetic instruments cannot measure the intrinsic parameters of strong [...] Read more.
A workshop measuring and positioning system (wMPS) is a large three-dimensional (3D) coordinate-measurement system based on optoelectronic scanning. It is capable of large-range coverage, high measurement accuracy and frequency, and multi-task synchronous measurement. Existing geodetic instruments cannot measure the intrinsic parameters of strong rigid structures. Thus, this study conducted experiments to explore the feasibility of the wMPS to measure the intrinsic parameters of rigid structures. A test bed was established using a reverse-engineering method to simulate the oscillation frequency of the structure. Displacement data, which changed with the time series through the fast Fourier transformation method, were analyzed to determine the feasibility and range of the wMPS in measuring intrinsic parameters of the structure. The experimental results demonstrated that the wMPS can measure the vibrational frequency up to 9 Hz with a 3-mm amplitude and up to 4 Hz with a 30-mm amplitude. Full article
(This article belongs to the Special Issue Structural Damage Detection and Health Monitoring)
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Open AccessArticle A Web Service for Evaluating the Level of Speech in Korean
Appl. Sci. 2019, 9(3), 594; https://doi.org/10.3390/app9030594
Received: 18 January 2019 / Revised: 7 February 2019 / Accepted: 8 February 2019 / Published: 11 February 2019
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Abstract
Speaking is a way for humans to communicate with others using language. The ability to speak according to the speaker is very diverse. In general, language skills improve as intelligence improves. Therefore, it is known that the analysis of a speaker’s utterances is [...] Read more.
Speaking is a way for humans to communicate with others using language. The ability to speak according to the speaker is very diverse. In general, language skills improve as intelligence improves. Therefore, it is known that the analysis of a speaker’s utterances is a good tool to evaluate the intellectual maturity of the speaker. Until recently, these evaluations have been done manually based on the experience of a handful of experts, but this approach is not only time consuming and costly, but also highly subjective. In this paper, we propose a Korean automatic speech analysis system based on Natural Language Processing (NLP) and web service to solve this problem. For this study, we constructed a web service based on Django to respond to the requests of various users. When a user delivered a transcription file of utterances to the server via the web, the server analyzed the speech ability of the speaker based on various indicators. The server compared the transcription file with the language ability indicators of persons of the same age as the speaker and displayed the result immediately to the user. In this study, we used KoNLPy, a Korean language-processing tool. The automatic speech analysis service analyzed not only the overall language ability of the speaker but also individual domains such as sentence completion ability and vocabulary ability. In addition, a faster and immediate service was made possible without sacrificing accuracy as compared to human analysis. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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Open AccessArticle Influence of Multiple Factors on the Wettability and Surface Free Energy of Leaf Surface
Appl. Sci. 2019, 9(3), 593; https://doi.org/10.3390/app9030593
Received: 26 December 2018 / Revised: 6 February 2019 / Accepted: 8 February 2019 / Published: 11 February 2019
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Abstract
The wettability of plant leaves directly reflects leaf hydrophilicity, which is the key factor that influences the adhesion of liquid pesticide as well as affects plant protection products (PPP) efficacy. Generally, the wettability of leaf surface is quantified by the contact angle and [...] Read more.
The wettability of plant leaves directly reflects leaf hydrophilicity, which is the key factor that influences the adhesion of liquid pesticide as well as affects plant protection products (PPP) efficacy. Generally, the wettability of leaf surface is quantified by the contact angle and surface free energy (SFE), which are mainly dependent on leaf surface properties, liquid properties and other spraying parameters. Therefore, the aim of this paper was to investigate the SFE of rice and rape leaves with the variation of leaf status, leaf surface, and probe liquid as well as the influence of droplet falling height, solid surface, and PPP concentration on the wettability. The results showed that: (1) the dispersive components of SFE of rice and rape account for a large proportion which are closely related to their hydrophobicity—the abaxial of rape new leaf and the adaxial of rape old leaf are easier to wet comparing with rice and rape leaves in other statuses; (2) the increase of droplet falling height had a significant effect on improving the wettability between wax surface and adjuvant solution, while it had little improving effect on the wettability between wax surface and water; (3) the wettability of different solid surface varied greatly, and the order of wettability from good to bad is water-sensitive paper (WSP), wax, rape leaf, and rice leaf; (4) the effect of PPP concentration on the leaf surface wettability is significant, the contact angle decreased with the increase of PPP concentration, and the wettability of microemulsion is better than that of suspending agent and wettable powder. In conclusion, the SFE and wettability of crop leaf surface determine the suitable type of PPP, studying the influence of multiple factors on leaf surface wettability can provide a reliable reference for providing scientific guidance as well as improving the effective utilization of PPP. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle Equivalence of RABBITT and Streaking Delays in Attosecond-Time-Resolved Photoemission Spectroscopy at Solid Surfaces
Appl. Sci. 2019, 9(3), 592; https://doi.org/10.3390/app9030592
Received: 19 December 2018 / Revised: 1 February 2019 / Accepted: 6 February 2019 / Published: 11 February 2019
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Abstract
The dynamics of the photoelectric effect in solid-state systems can be investigated via attosecond-time-resolved photoelectron spectroscopy. This article provides a comparison of delay information accessible by the two most important techniques, attosecond streaking spectroscopy and reconstruction of attosecond beating by interference of two-photon [...] Read more.
The dynamics of the photoelectric effect in solid-state systems can be investigated via attosecond-time-resolved photoelectron spectroscopy. This article provides a comparison of delay information accessible by the two most important techniques, attosecond streaking spectroscopy and reconstruction of attosecond beating by interference of two-photon transitions (RABBITT) at solid surfaces, respectively. The analysis is based on simulated time-resolved photoemission spectra obtained by solving the time-dependent Schrödinger equation in a single-active-electron approximation. We show a continuous transition from the few-cycle RABBITT regime to the streaking regime as two special cases of laser-assisted photoemission. The absolute delay times obtained by both methods agree with each other, within the uncertainty limits for kinetic energies >10 eV. Moreover, for kinetic energies >10 eV, both streaking delay time and RABBITT delay time coincide with the classical time of flight for an electron propagating from the emitter atom to the bulk-vacuum interface, with only small deviations of less than 4 as due to quantum mechanical interference effects. Full article
(This article belongs to the Special Issue Attosecond Science and Technology: Principles and Applications)
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Open AccessArticle Three-Dimensional Reconstruction Method for Machined Surface Topography Based on Gray Gradient Constraints
Appl. Sci. 2019, 9(3), 591; https://doi.org/10.3390/app9030591
Received: 17 January 2019 / Revised: 1 February 2019 / Accepted: 2 February 2019 / Published: 11 February 2019
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Abstract
In the modern engineering field, recovering the machined surface topography is important for studying mechanical product function and surface characteristics by using the shape from shading (SFS)-based reconstruction method. However, due to the limitations of many constraints and oversmoothing, the existing SFS-based reconstruction [...] Read more.
In the modern engineering field, recovering the machined surface topography is important for studying mechanical product function and surface characteristics by using the shape from shading (SFS)-based reconstruction method. However, due to the limitations of many constraints and oversmoothing, the existing SFS-based reconstruction methods are not suitable for machined surface topography. This paper presents a new three-dimensional (3D) reconstruction method of machined surface topography. By combining the basic principle of SFS and the analytic method, the analytic model of a surface gradient is established using the gray gradient as a constraint condition. By efficiently solving the effect of quantization errors and ambiguity of the gray scale on reconstruction accuracy using a wavelet denoising algorithm and image processing technology, the reconstruction algorithm is implemented for machined surface topography. Experimental results on synthetic images and machined surface topography images show that the proposed algorithm can accurately and efficiently recover the 3D shape of machined surface topography. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Provision of Ancillary Services from an Aggregated Portfolio of Residential Heat Pumps on the Dutch Frequency Containment Reserve Market
Appl. Sci. 2019, 9(3), 590; https://doi.org/10.3390/app9030590
Received: 28 December 2018 / Revised: 3 February 2019 / Accepted: 5 February 2019 / Published: 11 February 2019
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Abstract
This study investigates the technical and financial potential of an aggregation of residential heat pumps to deliver demand response (DR) services to the Dutch Frequency Containment Reserve (FCR) market. To determine this potential, a quantitative model was developed to simulate a heat pump [...] Read more.
This study investigates the technical and financial potential of an aggregation of residential heat pumps to deliver demand response (DR) services to the Dutch Frequency Containment Reserve (FCR) market. To determine this potential, a quantitative model was developed to simulate a heat pump switching process. The model utilizes historical frequency and heat pump data as input to determine the optimal weekly bid size considering the regulations and fine regime of the FCR market. These regulations are set by the Dutch Transmission System Operator (TSO). Two strategies were defined that can be employed by an aggregator to select the optimal bid size; the ‘always available’ scenario and the ‘always reliable’ scenario. By using the availability and reliability as constraints in the model, the effects of TSO regulations on the potential for FCR are accurately assessed. Results show a significant difference in bid size and revenue of the strategies. In the ‘always available’ scenario, the average resultant bid size is 1.7 MW, resulting in €0.22 revenue per heat pump (0.5kWp) per week. In the ‘always reliable’ scenario, the average resultant bid size is 7.9 MW, resulting in €1.00 revenue per heat pump per week on average in the period 03-10-2016–24-04-2017. This is based on a simulation of 20,000 heat pumps with a total capacity of 1 MWp. Results show a large difference in potential between the two strategies. Since the strategies are based on TSO-regulations and strategic choices by the aggregator, both seem to have a strong influence on the financial potential of FCR provision. In practice, this study informs organizations that provide FCR with knowledge about different bidding strategies and their market impact. Full article
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Open AccessArticle Evaluation of the Electromyography Test for the Analysis of the Aerobic-Anaerobic Transition in Elite Cyclists during Incremental Exercise
Appl. Sci. 2019, 9(3), 589; https://doi.org/10.3390/app9030589
Received: 13 December 2018 / Revised: 21 January 2019 / Accepted: 29 January 2019 / Published: 11 February 2019
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Abstract
(1) Background: The aim of this study was to investigate the validity and reliability of surface electromyography (EMG) for automatic detection of the aerobic and anaerobic thresholds during an incremental continuous cycling test using 1 min exercise periods in elite cyclists. (2) Methods: [...] Read more.
(1) Background: The aim of this study was to investigate the validity and reliability of surface electromyography (EMG) for automatic detection of the aerobic and anaerobic thresholds during an incremental continuous cycling test using 1 min exercise periods in elite cyclists. (2) Methods: Sixteen well-trained cyclists completed an incremental exercise test (25 W/1 min) to exhaustion. Surface bipolar EMG signals were recorded from the vastus lateralis, vastus medialis, biceps femoris, and gluteus maximus, and the root mean square (RMS) were assessed. The multi-segment linear regression method was used to calculate the first and second EMG thresholds (EMGT1 and EMGT2). During the test, gas exchange data were collected to determine the first and second ventilatory thresholds (VT1 and VT2). (3) Results: Two breakpoints (thresholds) were identified in the RMS EMG vs. time curve for all muscles in 75% of participants. The two breakpoints, EMGT1 and EMGT2, were detected at around 70%–80% and 90%–95% of VO2MAX, respectively. No significant differences were found between the means of VT1 and EMGT1 for the vastii and biceps femoris muscles (p > 0.05). There were no significant differences between means of EMGT2 and VT2 (p > 0.05). (4) Conclusions: It is concluded that the multi-segment linear regression algorithm is a valid non-invasive method for analyzing the aerobic-anaerobic transition during incremental tests with 1 min stage durations. Full article
(This article belongs to the Section Applied Biosciences and Bioengineering)
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Open AccessArticle An Artificial Bee Colony Algorithm Based on a Multi-Objective Framework for Supplier Integration
Appl. Sci. 2019, 9(3), 588; https://doi.org/10.3390/app9030588
Received: 6 December 2018 / Revised: 29 January 2019 / Accepted: 4 February 2019 / Published: 11 February 2019
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Abstract
Modern day industries strive to obtain long-term supplier integrations (SI) with potentially stronger supplier groups, to achieve fast and reliable production. This paper studies the process of selecting vendors, while simultaneously considering the aspects of random factors, multiple criteria, and efficiently reaching optimal [...] Read more.
Modern day industries strive to obtain long-term supplier integrations (SI) with potentially stronger supplier groups, to achieve fast and reliable production. This paper studies the process of selecting vendors, while simultaneously considering the aspects of random factors, multiple criteria, and efficiently reaching optimal solutions to improve the SI. A framework was developed that consists of three layers of expert opinions, supplier requirements, and multi-objective bee colony optimization. The model factors affecting the SI decision were explored from the comprehensive relevant literature, and these factors were shortlisted and prioritized. Routines for the modeled framework were coded by using the proposed algorithms which were implemented for a real-world problem from a manufacturing small and medium enterprise (SME) in Pakistan. Optimization of SI was carried out on an archived artificial bee colony (AABC). Its effectiveness was also evaluated by comparison with simple artificial bee colony (ABC) and particle swarm algorithms. The methodologically calculated results, obtained from simulation of a mathematically reinforced optimization framework, are highly beneficial for the industry, as well as local and international suppliers. A detailed and in-depth evaluation of suppliers was provided by the sensitivity analysis, which presented a more rigorous authentication and elaboration of the results. The presented framework is the first of its kind for the SMEs of Pakistan and can be applied with little modification to other industries. Full article
(This article belongs to the Section Computing and Artificial Intelligence)
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Open AccessArticle Effect of Cell-Free Supernatant from Aeromonas sobria on the Spoilage of Shewanella putrefaciens in Pacific White Shrimp (Litopenaeus vannamei) with the Influence of Temperature Fluctuation
Appl. Sci. 2019, 9(3), 587; https://doi.org/10.3390/app9030587
Received: 21 November 2018 / Revised: 14 January 2019 / Accepted: 20 January 2019 / Published: 11 February 2019
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Abstract
The objective of this study was to evaluate the effect of cell-free supernatant (CFS) from Aeromonas sobria on the growth and spoilage potential of Shewanella putrefaciens in Pacific white shrimp (Litopenaeus vannamei) during cold chain logistics, including transportation, retailing, and domestic [...] Read more.
The objective of this study was to evaluate the effect of cell-free supernatant (CFS) from Aeromonas sobria on the growth and spoilage potential of Shewanella putrefaciens in Pacific white shrimp (Litopenaeus vannamei) during cold chain logistics, including transportation, retailing, and domestic storage. It was shown that the quality of shrimps deteriorated in the cold chain logistics over time. The temperature fluctuation during the experimental period favored the growth of S. putrefaciens, increased the total volatile basic nitrogen (TVB-N) and biogenic amine value, and decreased the sensory quality of shrimps. The application of CFS resulted in the decline on the growth of S. putrefaciens after the early stationary phase stored at a cold condition. It is concluded that the application of CFS can inhibit microbial growth and the spoilage potential of S. putrefaciens and offset the quality deterioration of shrimp exposed to temperature fluctuation during cold chain logistics. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle Experimental Evaluation of Screw Pullout Force and Adjacent Bone Damage According to Pedicle Screw Design Parameters in Normal and Osteoporotic Bones
Appl. Sci. 2019, 9(3), 586; https://doi.org/10.3390/app9030586
Received: 14 November 2018 / Revised: 3 January 2019 / Accepted: 1 February 2019 / Published: 11 February 2019
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Abstract
This paper proposes an optimum design of the pedicle screw with respect to bone density and variables of the screw design. First, pedicle screws are designed and manufactured with design variables including the core diameter and conical angle that affect the pullout force [...] Read more.
This paper proposes an optimum design of the pedicle screw with respect to bone density and variables of the screw design. First, pedicle screws are designed and manufactured with design variables including the core diameter and conical angle that affect the pullout force of the pedicle screw. Variables of bone density are also classified into two groups, namely grade 10 (0.16 g/cc) with osteoporotic bone density and grade 20 (0.32 g/cc) with normal bone density. The effect of each parameter on the pullout force and relationship between the pullout force and screw designs are investigated. Furthermore, bone damage after fixation failure or insertion in the patient body is considered separately from the pullout strength. Therefore, cross sectional images of the artificial bone are observed to analyze the degree of damage after the pullout test of the pedicle screw by using micro-CT (computed tomography). The region and degree of bone damage are quantitatively analyzed. The effects of the core diameter and conical angle of the pedicle screw on the pulling force, bone damage, and fracture behavior are analyzed via the aforementioned experiments and analysis. An optimal pedicle screw design is suggested based on the experimental results. Full article
(This article belongs to the Section Materials)
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Open AccessReview New Insights into the Symbiotic Relationship between Orchids and Fungi
Appl. Sci. 2019, 9(3), 585; https://doi.org/10.3390/app9030585
Received: 8 January 2019 / Revised: 31 January 2019 / Accepted: 6 February 2019 / Published: 11 February 2019
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Abstract
Mycorrhizas play an important role in plant growth and development. In mycorrhizal symbioses, fungi supply soil mineral nutrients, such as nitrogen and phosphorus, to their host plants in exchange for carbon resources. Plants gain as much as 80% of mineral nutrient requirements from [...] Read more.
Mycorrhizas play an important role in plant growth and development. In mycorrhizal symbioses, fungi supply soil mineral nutrients, such as nitrogen and phosphorus, to their host plants in exchange for carbon resources. Plants gain as much as 80% of mineral nutrient requirements from mycorrhizal fungi, which form associations with the roots of over 90% of all plant species. Orchid seeds lack endosperms and contain very limited storage reserves. Therefore, the symbiosis with mycorrhizal fungi that form endomycorrhizas is essential for orchid seed germination and protocorm development under natural conditions. The rapid advancement of next-generation sequencing contributes to identifying the orchid and fungal genes involved in the orchid mycorrhizal symbiosis and unraveling the molecular mechanisms regulating the symbiosis. We aim to update and summarize the current understanding of the mechanisms on orchid-fungus symbiosis, and the main focus will be on the nutrient exchange between orchids and their fungal partners. Full article
(This article belongs to the Section Applied Biosciences and Bioengineering)
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