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Appl. Sci., Volume 7, Issue 3 (March 2017)

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Cover Story One of the major challenges in the laser-based additive manufacturing is the severe limitation on [...] Read more.
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Open AccessArticle Identification of Traditional She Medicine Shi-Liang Tea Species and Closely Related Species Using the ITS2 Barcode
Appl. Sci. 2017, 7(3), 195; doi:10.3390/app7030195
Received: 16 November 2016 / Revised: 25 January 2017 / Accepted: 10 February 2017 / Published: 23 February 2017
Cited by 1 | PDF Full-text (1415 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Traditional She medicine is part of China’s cultural heritage and has become remarkably popular worldwide. The Shi-Liang tea is made from the processed leaves of Chimonanthus salicifolius S. Y. Hu and Chimonanthus zhejiangensis M. C. Liu. To ensure the safety and efficacy of
[...] Read more.
Traditional She medicine is part of China’s cultural heritage and has become remarkably popular worldwide. The Shi-Liang tea is made from the processed leaves of Chimonanthus salicifolius S. Y. Hu and Chimonanthus zhejiangensis M. C. Liu. To ensure the safety and efficacy of Shi-Liang tea, we used DNA barcoding based on the internal transcribed spacer 2 (ITS2) of nuclear ribosomal DNA to distinguish the original plant sources of Shi-Liang tea from closely related species. All 71 ITS2 sequences were aligned by Clustal-W, and genetic distances were computed using MEGA 6.0 according to the Kimura 2-parameter model. The results indicated that the sequence lengths of ITS2 regions of the original plants of Shi-Liang tea and closely related species ranged from 256 bp to 260 bp. Interspecific genetic distances ranged from 0 to 0.078. The neighbor-joining (NJ) tree showed that the original plants of Shi-Liang tea species can be easily differentiated from closely related species. Distinct molecular differences were found between the secondary structures of ITS2 sequences from Shi-Liang tea and closely related species. The results in the present investigation suggested that the ITS2 could be an effective DNA marker to identify the original plants of Shi-Liang tea and their closely related species. These DNA barcodes can greatly benefit the supervision of the commercial circulation of She medicine. Full article
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Open AccessArticle Tuning Guidelines for an Adaptive-Gain Parabolic Sliding Mode Filter
Appl. Sci. 2017, 7(3), 209; doi:10.3390/app7030209
Received: 7 December 2016 / Revised: 2 February 2017 / Accepted: 16 February 2017 / Published: 23 February 2017
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Abstract
This paper quantitatively evaluates the performance of an adaptive-gain parabolic sliding mode filter (AG-PSMF), which is for removing noise in feedback control of mechatronic systems under different parameter values and noise intensities. The evaluation results show that, due to the nonlinearity of AG-PSMF,
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This paper quantitatively evaluates the performance of an adaptive-gain parabolic sliding mode filter (AG-PSMF), which is for removing noise in feedback control of mechatronic systems under different parameter values and noise intensities. The evaluation results show that, due to the nonlinearity of AG-PSMF, four performance measurements, i.e., transient time, overshoot magnitude, tracking error and computational time, vary widely under different conditions. Based on the evaluation results, the paper provides practical tuning guidelines for AG-PSMF to balance the tradeoff among the four measurements. The effectiveness of the guidelines is validated through numerical examples. Full article
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Open AccessArticle DeepGait: A Learning Deep Convolutional Representation for View-Invariant Gait Recognition Using Joint Bayesian
Appl. Sci. 2017, 7(3), 210; doi:10.3390/app7030210
Received: 3 January 2017 / Revised: 27 January 2017 / Accepted: 15 February 2017 / Published: 23 February 2017
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Abstract
Human gait, as a soft biometric, helps to recognize people through their walking. To further improve the recognition performance, we propose a novel video sensor-based gait representation, DeepGait, using deep convolutional features and introduce Joint Bayesian to model view variance. DeepGait is generated
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Human gait, as a soft biometric, helps to recognize people through their walking. To further improve the recognition performance, we propose a novel video sensor-based gait representation, DeepGait, using deep convolutional features and introduce Joint Bayesian to model view variance. DeepGait is generated by using a pre-trained “very deep” network “D-Net” (VGG-D) without any fine-tuning. For non-view setting, DeepGait outperforms hand-crafted representations (e.g., Gait Energy Image, Frequency-Domain Feature and Gait Flow Image, etc.). Furthermore, for cross-view setting, 256-dimensional DeepGait after PCA significantly outperforms the state-of-the-art methods on the OU-ISR large population (OULP) dataset. The OULP dataset, which includes 4007 subjects, makes our result reliable in a statistically reliable way. Full article
(This article belongs to the Special Issue Human Activity Recognition)
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Open AccessArticle A Nondestructive Real-Time Detection Method of Total Viable Count in Pork by Hyperspectral Imaging Technique
Appl. Sci. 2017, 7(3), 213; doi:10.3390/app7030213
Received: 10 November 2016 / Revised: 10 February 2017 / Accepted: 14 February 2017 / Published: 23 February 2017
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Abstract
A nondestructive method was developed for assessing total viable count (TVC) in pork during refrigerated storage by using hyperspectral imaging technique in this study. The hyperspectral images in the visible/near-infrared (VIS/NIR) region of 400–1100 nm were acquired for fifty pork samples, and their
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A nondestructive method was developed for assessing total viable count (TVC) in pork during refrigerated storage by using hyperspectral imaging technique in this study. The hyperspectral images in the visible/near-infrared (VIS/NIR) region of 400–1100 nm were acquired for fifty pork samples, and their VIS/NIR diffuse reflectance spectra were extracted from the images. The reference values of TVC in pork samples were determined by classical microbiological plating method. Both partial least square regression (PLSR) model and support vector machine regression model (SVR) of TVC were built for comparative analysis to achieve better results. Different transformation methods and filtering methods were applied to improve the models. The results show that both the optimized PLSR model and SVR model can predict the TVC very well, while the SVR model based on second derivation was better, which achieved with RP (correlation coefficient of prediction set) = 0.94 and SEP (standard error of prediction set) = 0.4570 log CFU/g in the prediction set. An image processing algorithm was then developed to transfer the prediction model to every pixel of the image of the entire sample; the visualizing map of TVC would be displayed in real-time during the detection process due to the simplicity of the model. The results demonstrated that hyperspectral imaging is a potential reliable approach for non-destructive and real-time prediction of TVC in pork. Full article
(This article belongs to the Special Issue Applications of Hyperspectral Imaging for Food and Agriculture)
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Open AccessArticle Dielectric and Impedance Analysis on the Electrical Response of Lead-Free Ba1−xCaxTi0.9Zr0.1O3 Ceramics at High Temperature Range
Appl. Sci. 2017, 7(3), 214; doi:10.3390/app7030214
Received: 22 December 2016 / Revised: 6 February 2017 / Accepted: 14 February 2017 / Published: 23 February 2017
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Abstract
Ba1−xCaxTi0.9Zr0.1O3 (x = 0.10, 0.15, 0.18) solid solutions were synthesized by the conventional solid-state method. A perovskite-type structure was determined using the X-ray diffraction (XRD) technique. The addition of Ca2+ reduced
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Ba1−xCaxTi0.9Zr0.1O3 (x = 0.10, 0.15, 0.18) solid solutions were synthesized by the conventional solid-state method. A perovskite-type structure was determined using the X-ray diffraction (XRD) technique. The addition of Ca2+ reduced the grain size (22.6, 17.9 and 13.3 μm, respectively) for all well-sintered ceramics (≈98%). Moreover, the stability temperature ranges for the tetragonal phase were promoted by displacing the ferroelectric-ferroelectric phase’s transition temperatures while TC was maintained (86 °C). The electrical performance of the material improved as the stoichiometric composition was positioned near the morphotropic phase boundary (x = 0.15): εr ≈ 16,500 (TC) at 1 kHz. For T > TC, a thermally activated relaxation process occurred. In addition, the bulk and grain boundary processes were responsible for the conduction mechanisms. The composition x = 0.15 showed an activation energy of Ea = 1.49 eV with a maximum conductivity of σmax = 2.48 × 10−2 S·cm−1 at 580 °C. Systematic studies at high temperature for dielectric properties were accomplished for analyzing electrical inhomogeneities associated with the grain, grain boundaries or surfaces, which are important for device design and a fundamental electrical characterization. Full article
(This article belongs to the Special Issue A Perspective on the Design of Lead-Free Piezoceramics)
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Open AccessArticle A Novel Denoising Method for an Acoustic-Based System through Empirical Mode Decomposition and an Improved Fruit Fly Optimization Algorithm
Appl. Sci. 2017, 7(3), 215; doi:10.3390/app7030215
Received: 5 January 2017 / Revised: 10 February 2017 / Accepted: 17 February 2017 / Published: 23 February 2017
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Abstract
Generally, the sound signal produced by transmission unit or cutting unit contains abundant information about the working state of a machine. The acoustic-based diagnosis system presents some distinct advantages in some severe conditions particularly due to its unique non-contact measurement and unlimited use
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Generally, the sound signal produced by transmission unit or cutting unit contains abundant information about the working state of a machine. The acoustic-based diagnosis system presents some distinct advantages in some severe conditions particularly due to its unique non-contact measurement and unlimited use at the installation site. However, the original acoustic signal collected from manufacture process is always polluted by various background noises. In order to eliminate noise components from machinery sound effectively, an empirical mode decomposition (EMD) threshold denoising method optimized by an improved fruit fly optimization algorithm (IFOA) is launched in this paper. The acoustic signal was first decomposed by the adaptive EMD to obtain a series of intrinsic mode functions (IMFs). Then, the soft threshold function was applied to shrink the IMF coefficients. While the threshold of each IMF was determined by statistical estimation and empirical value for traditional EMD denoising, the denoising effect was often not desired and time-consuming. To solve these disadvantages, fruit fly optimization algorithm (FOA) was introduced to search global optimal threshold of each IMF. Moreover, to enhance the group diversity during production of the next generation of fruit flies and balance the local and global searching ability, a variation coefficient and a disturbance coefficient was introduced to the basic FOA. Then, a piece of simulated acoustic signal produced by the train was applied to validate the proposed EMD and IFOA threshold denoising (EMD-IFOA). The simulation results, which decreased 35.40% and 18.92% in mean squared error (MSE) and percent root mean square difference (PRD) respectively, and increased 40.36% in signal-to-noise ratio improvement (SNRimp) compared with basic EMD denoising scheme at SNR = 5 dB, illustrated the effectiveness and superiority of the proposed approach. Finally, the proposed EMD-IFOA was conducted on an actual acoustic-based diagnosis system for cutting state recognition of the coal mining shearer to demonstrate the practical effect. Full article
(This article belongs to the Section Acoustics)
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Open AccessArticle Thermal and Fatigue Evaluation of Asphalt Mixtures Containing RAP Treated with a Bio-Agent
Appl. Sci. 2017, 7(3), 216; doi:10.3390/app7030216
Received: 31 December 2016 / Revised: 14 February 2017 / Accepted: 20 February 2017 / Published: 23 February 2017
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Abstract
Environment conservation and diminishing natural resources caused an increase in popularity of the application of renewable bio-origin resources for the construction of road pavement. Currently, there are known additions of bio-origin materials for bitumen modification. Such material is also used as a flux
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Environment conservation and diminishing natural resources caused an increase in popularity of the application of renewable bio-origin resources for the construction of road pavement. Currently, there are known additions of bio-origin materials for bitumen modification. Such material is also used as a flux additive for bitumen or as a rejuvenator once working with reclaimed asphalt pavement (RAP). This paper presents research dealing with asphalt mixtures with RAP modified with a bio-agent of rapeseed origin. The main idea of the conducted research was to apply more RAP content directly to the batch mix plant without extra RAP heating. The RAP used in this study was milled from a base asphalt layer; the addition of RAP stiffens new asphalt mixtures. A bio-agent, due to its fluxing action, was used to support the asphalt mixing process and to decrease the over-stiffening of the mixture caused by RAP addition. This research includes bitumen and mixture tests. For the bitumen study, three different bitumens (35/50, 50/70, and 70/100) were tested in a dynamic shear rheometer (DSR) for complex modulus G* and for phase angle |δ| in the temperature range 0–100 °C. The reference mixture and mixtures with 2.5% bio-agent were tested to assess the influence of RAP and the bio-agent addition on the asphalt mixture properties. Low temperature behavior (TSRST), stiffness, and fatigue resistance (4PB) were tested. Based on the bitumen test, it was determined that even a low rate of bio-agent (2.5%) beneficially changes bitumen properties at a low temperature; moreover, polymerization processes occurring in the second stage of the process improves bitumen properties at a high operational temperature. The research with these asphalt mixtures demonstrates that the bio-origin flux acts as a rejuvenator and allows for an application of 30% cold RAP. Thermal cracking resistance of the mixture with RAP and 2.5% bio-agent improved. The bio-agent removes unfavorable stiffening of RAP and increases the fatigue resistance of the asphalt mixture. Full article
(This article belongs to the Special Issue Advanced Asphalt Materials and Paving Technologies)
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Open AccessArticle Time Series Prediction Based on Adaptive Weight Online Sequential Extreme Learning Machine
Appl. Sci. 2017, 7(3), 217; doi:10.3390/app7030217
Received: 5 January 2017 / Accepted: 20 February 2017 / Published: 2 March 2017
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Abstract
A novel adaptive weight online sequential extreme learning machine (AWOS-ELM) is proposed for predicting time series problems based on an online sequential extreme learning machine (OS-ELM) in this paper. In real-world online applications, the sequentially coming data chunk usually possesses varying confidence coefficients,
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A novel adaptive weight online sequential extreme learning machine (AWOS-ELM) is proposed for predicting time series problems based on an online sequential extreme learning machine (OS-ELM) in this paper. In real-world online applications, the sequentially coming data chunk usually possesses varying confidence coefficients, and the data chunk with a low confidence coefficient tends to mislead the subsequent training process. The proposed AWOS-ELM can improve the training process by accessing the confidence coefficient adaptively and determining the training weight accordingly. Experiments on six time series prediction data sets have verified that the AWOS-ELM algorithm performs better in generalization performance, stability, and prediction ability than the OS-ELM algorithm. In addition, a real-world mechanical system identification problem is considered to test the feasibility and efficacy of the AWOS-ELM algorithm. Full article
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Open AccessArticle Modeling and Solving the Three Seaside Operational Problems Using an Object-Oriented and Timed Predicate/Transition Net
Appl. Sci. 2017, 7(3), 218; doi:10.3390/app7030218
Received: 20 November 2016 / Revised: 17 February 2017 / Accepted: 18 February 2017 / Published: 24 February 2017
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Abstract
Container terminals (CTs) play an essential role in the global transportation system. To deal with growing container shipments, a CT needs to better solve the three essential seaside operational problems; berth allocation problem (BAP), quay crane assignment problem (QCAP), and quay crane scheduling
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Container terminals (CTs) play an essential role in the global transportation system. To deal with growing container shipments, a CT needs to better solve the three essential seaside operational problems; berth allocation problem (BAP), quay crane assignment problem (QCAP), and quay crane scheduling problem (QCSP), which affect the performance of a CT considerably. In past studies, the three seaside operational problems have often been solved individually or partially, which is likely to result in poor overall system performance. However, solving the three seaside operational problems simultaneously is in fact a very complicated task. In this research, we dealt with the three seaside operational problems at the same time by using a novel high-level Petri net, termed an Object-Oriented and Timed Predicate/Transition Net (OOTPr/Tr net). After defining the three seaside operational problems formally, we integrated them as a three-level framework that was further transformed into an OOTPr/Tr net model. Then, using the Prolog programming language, we implemented this model as a simulation tool to find the best solution based on the various combinations of heuristic rules used. Full article
(This article belongs to the Special Issue Modeling, Simulation, Operation and Control of Discrete Event Systems)
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Open AccessArticle Robust Backstepping Control of Wing Rock Using Disturbance Observer
Appl. Sci. 2017, 7(3), 219; doi:10.3390/app7030219
Received: 5 January 2017 / Accepted: 20 February 2017 / Published: 24 February 2017
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Abstract
Wing rock is a highly nonlinear phenomenon when the aircraft suffers undesired roll-dominated oscillatory at high angle of attack (AOA). Considering the strong nonlinear and unsteady aerodynamic characteristics, an uncertain multi-input and multi-output (MIMO) nonlinear wing rock model is studied, and system uncertainties,
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Wing rock is a highly nonlinear phenomenon when the aircraft suffers undesired roll-dominated oscillatory at high angle of attack (AOA). Considering the strong nonlinear and unsteady aerodynamic characteristics, an uncertain multi-input and multi-output (MIMO) nonlinear wing rock model is studied, and system uncertainties, unsteady aerodynamic disturbances and externaldisturbancesareconsideredinthedesignofwingrockcontrollaw. Tohandletheproblemof multipledisturbances,arobustcontrolschemeisproposedbasedontheextendedstateobserver(ESO) and the radial basis function neural network (RBFNN) technique. Considering that the effectiveness of actuators are greatly decreased at high AOA, the input saturation problem is also handled by constructing a corresponding auxiliary system. Based on the improved ESO and the auxiliary system, a robust backstepping control law is proposed for the wing rock control. In addition, the dynamic surface control (DSC) technique is introduced to avoid the tedious computations of time derivatives for the virtual control laws in the backstepping method. The stability of the closed-loop system is guaranteed via rigorously Lyapunov analysis. Finally, simulation results are presented to illustrate the effectiveness of the ESO and the proposed wing rock control approach. Full article
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Open AccessArticle Extended Backstepping Sliding Controller Design for Chattering Attenuation and Its Application for Servo Motor Control
Appl. Sci. 2017, 7(3), 220; doi:10.3390/app7030220
Received: 12 November 2016 / Revised: 10 February 2017 / Accepted: 14 February 2017 / Published: 27 February 2017
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Abstract
This paper presents a robust backstepping design for motion control in the presence of model uncertainties and exogenous disturbances. The main difficulty in dealing with motion control is to reduce the effect of friction, which exists in the moving mechanism and induces nonlinear
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This paper presents a robust backstepping design for motion control in the presence of model uncertainties and exogenous disturbances. The main difficulty in dealing with motion control is to reduce the effect of friction, which exists in the moving mechanism and induces nonlinear behavior. In this study, the friction dynamic is considered as the external disturbance, and the proposed backstepping control algorithm is integrated with the sliding mode control, so that the effect of matching disturbances can be eliminated. The proposed approach guarantees the system asymptotic stability, globally, without significant chatter. Therefore, the developed algorithm can be realized for practical manufacturing motion control stages. Experiments including positioning and tracking controls are conducted to demonstrate the feasibility of the proposed method. Full article
(This article belongs to the Special Issue Selected Papers from the 2016 International Conference on Inventions)
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Open AccessArticle Performance Comparison of Time-Frequency Distributions for Estimation of Instantaneous Frequency of Heart Rate Variability Signals
Appl. Sci. 2017, 7(3), 221; doi:10.3390/app7030221
Received: 20 December 2016 / Revised: 17 February 2017 / Accepted: 23 February 2017 / Published: 27 February 2017
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Abstract
The instantaneous frequency (IF) of a non-stationary signal is usually estimated from a time-frequency distribution (TFD). The IF of heart rate variability (HRV) is an important parameter because the power in a frequency band around the IF can be used for the interpretation
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The instantaneous frequency (IF) of a non-stationary signal is usually estimated from a time-frequency distribution (TFD). The IF of heart rate variability (HRV) is an important parameter because the power in a frequency band around the IF can be used for the interpretation and analysis of the respiratory rate but also for a more accurate analysis of heart rate (HR) signals. In this study, we compare the performance of five states of the art kernel-based time-frequency distributions (TFDs) in terms of their ability to accurately estimate the IF of HR signals. The selected TFDs include three widely used fixed kernel methods: the modified B distribution, the S-method and the spectrogram; and two adaptive kernel methods: the adaptive optimal kernel TFD and the recently developed adaptive directional TFD. The IF of the respiratory signal, which is usually easier to estimate as the respiratory signal is a mono-component with small amplitude variations with time, is used as a reference to examine the accuracy of the HRV IF estimates. Experimental results indicate that the most reliable estimates are obtained using the adaptive directional TFD in comparison to other commonly used methods such as the adaptive optimal kernel TFD and the modified B distribution. Full article
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Open AccessArticle Adsorption of Chromium (VI) on Calcium Phosphate: Mechanisms and Stability Constants of Surface Complexes
Appl. Sci. 2017, 7(3), 222; doi:10.3390/app7030222
Received: 4 December 2016 / Accepted: 7 February 2017 / Published: 28 February 2017
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Abstract
The adsorption of chromate on octacalcium phosphate (OCP) was investigated as a function of contact time, surface coverage, and solution pH [...] Full article
(This article belongs to the Special Issue Wastewater Treatment and Reuse Technologies)
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Open AccessArticle Existence, Stability and Dynamics of Nonlinear Modes in a 2D PartiallyPT Symmetric Potential
Appl. Sci. 2017, 7(3), 223; doi:10.3390/app7030223
Received: 3 January 2017 / Accepted: 21 February 2017 / Published: 27 February 2017
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Abstract
It is known that multidimensional complex potentials obeying parity-time(PT)symmetry may possess all real spectra and continuous families of solitons. Recently, it was shown that for multi-dimensional systems, these features can persist when the parity symmetry condition is relaxed so that the potential is
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It is known that multidimensional complex potentials obeying parity-time(PT)symmetry may possess all real spectra and continuous families of solitons. Recently, it was shown that for multi-dimensional systems, these features can persist when the parity symmetry condition is relaxed so that the potential is invariant under reflection in only a single spatial direction. We examine the existence, stability and dynamical properties of localized modes within the cubic nonlinear Schrödinger equation in such a scenario of partiallyPT-symmetric potential. Full article
(This article belongs to the Special Issue Guided-Wave Optics)
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Open AccessFeature PaperArticle Effects of the Distance from a Diffusive Surface on the Objective and Perceptual Evaluation of the Sound Field in a Small Simulated Variable-Acoustics Hall
Appl. Sci. 2017, 7(3), 224; doi:10.3390/app7030224
Received: 17 November 2016 / Revised: 21 February 2017 / Accepted: 23 February 2017 / Published: 28 February 2017
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Abstract
Simulations of the acoustic effects that diffusive surfaces have on the objective acoustic parameters and on sound perception have not yet been fully understood. To this end, acoustic simulations have been performed in Odeon in the model of a variable-acoustic concert hall. This
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Simulations of the acoustic effects that diffusive surfaces have on the objective acoustic parameters and on sound perception have not yet been fully understood. To this end, acoustic simulations have been performed in Odeon in the model of a variable-acoustic concert hall. This paper is presented as a follow-up study to a previous paper that dealt with in-field measurements only. As in measurements, a diffusive and a reflective condition of one of the lateral walls have been considered in the room models. Two modeling alternatives of the diffusive condition, that is, (a) a flat surface with high scattering coefficient applied; and (b) a triangular relief modeled including edge diffraction, have been investigated. Objective acoustic parameters, such as early decay time (EDT), reverberation time (T30), clarity (C80), definition (D50), and interaural cross correlation (IACC), have been compared between the two conditions. Moreover, an auditory experiment has been performed to determine the maximum distance from a diffusive surface at which the simulated acoustic scattering effects are still audible. Although the simulated objective results showed a good match with measured values, the subjective results showed that the differences between the diffuse and reflective conditions become significant when model (b) is used. Full article
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Open AccessArticle Enhanced Agarose and Xylan Degradation for Production of Polyhydroxyalkanoates by Co-Culture of Marine Bacterium, Saccharophagus degradans and Its Contaminant, Bacillus cereus
Appl. Sci. 2017, 7(3), 225; doi:10.3390/app7030225
Received: 21 December 2016 / Revised: 31 January 2017 / Accepted: 2 February 2017 / Published: 28 February 2017
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Abstract
Over reliance on energy or petroleum products has raised concerns both in regards to the depletion of their associated natural resources as well as their increasing costs. Bioplastics derived from microbes are emerging as promising alternatives to fossil fuel derived petroleum plastics. The
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Over reliance on energy or petroleum products has raised concerns both in regards to the depletion of their associated natural resources as well as their increasing costs. Bioplastics derived from microbes are emerging as promising alternatives to fossil fuel derived petroleum plastics. The development of a simple and eco-friendly strategy for bioplastic production with high productivity and yield, which is produced in a cost effective manner utilising abundantly available renewable carbon sources, would have the potential to result in an inexhaustible global energy source. Here we report the biosynthesis of bioplastic polyhydroxyalkanoates (PHAs) in pure cultures of marine bacterium, Saccharophagus degradans 2-40 (Sde 2-40), its contaminant, Bacillus cereus, and a co-culture of these bacteria (Sde 2-40 and B. cereus) degrading plant and algae derived complex polysaccharides. Sde 2-40 degraded the complex polysaccharides agarose and xylan as sole carbon sources for biosynthesis of PHAs. The ability of Sde 2-40 to degrade agarose increased after co-culturing with B. cereus. The association of Sde 2-40 with B. cereus resulted in increased cell growth and higher PHA production (34.5% of dry cell weight) from xylan as a carbon source in comparison to Sde 2-40 alone (22.7% of dry cell weight). The present study offers an innovative prototype for production of PHA through consolidated bioprocessing of complex carbon sources by pure and co-culture of microorganisms. Full article
(This article belongs to the Special Issue Polyhydroxyalkanoates and Their Applications)
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Open AccessArticle Optical Beam Deflection Based AFM with Integrated Hardware and Software Platform for an Undergraduate Engineering Laboratory
Appl. Sci. 2017, 7(3), 226; doi:10.3390/app7030226
Received: 19 December 2016 / Revised: 3 February 2017 / Accepted: 3 February 2017 / Published: 28 February 2017
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Abstract
Atomic force microscopy (AFM) has been used extensively in nanoscience research since its invention. Recently, many teaching laboratories in colleges, undergraduate institutions, and even high schools incorporate AFM as an effective teaching tool for nanoscience education. This paper presents an optical beam deflection
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Atomic force microscopy (AFM) has been used extensively in nanoscience research since its invention. Recently, many teaching laboratories in colleges, undergraduate institutions, and even high schools incorporate AFM as an effective teaching tool for nanoscience education. This paper presents an optical beam deflection (OBD) based atomic force microscope, designed specifically for the undergraduate engineering laboratory as a teaching instrument. An electronic module for signal conditioning was built with components that are commonly available in an undergraduate electronic laboratory. In addition to off-the-shelf mechanical parts and optics, the design of custom-built mechanical parts waskept as simple as possible. Hence, the overall cost for the setup is greatly reduced. The AFM controller was developed using National Instruments Educational Laboratory Virtual Instrumentation Suite (NI ELVIS), an integrated hardware and software platform which can be programmed in LabVIEW. A simple yet effective control algorithm for scanning and feedback control was developed. Despite the use of an educational platform and low-cost components from the undergraduate laboratory, the developed AFM is capable of performing imaging in constant-force mode with submicron resolution and at reasonable scanning speed (approximately 18 min per image). Therefore, the AFM is suitable to be used as an educational tool for nanoscience. Moreover, the construction of the system can be a valuable educational experience for electronic and mechanical engineering students. Full article
(This article belongs to the Special Issue Dimensional Micro and Nanometrology)
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Open AccessArticle Microstructure and Mechanical Properties of Ti-6Al-4V Fabricated by Vertical Wire Feeding with Axisymmetric Multi-Laser Source
Appl. Sci. 2017, 7(3), 227; doi:10.3390/app7030227
Received: 10 January 2017 / Revised: 22 February 2017 / Accepted: 23 February 2017 / Published: 28 February 2017
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Abstract
Vertical wire feeding with an axisymmetric multi-laser source (feeding the wire vertically into the molten pool) has exhibited great advantages over LAM (laser additive manufacturing) with paraxial wire feeding, which has an anisotropic forming problem in different scanning directions. This paper investigates the
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Vertical wire feeding with an axisymmetric multi-laser source (feeding the wire vertically into the molten pool) has exhibited great advantages over LAM (laser additive manufacturing) with paraxial wire feeding, which has an anisotropic forming problem in different scanning directions. This paper investigates the forming ability of vertical wire feeding with an axisymmetric multi-laser source, and the microstructure and mechanical properties of the fabricated components. It has been found that vertical wire feeding with an axisymmetric multi-laser source has a strong forming ability with no anisotropic forming problem when fabricating the complex parts in a three-axis machine tool. Most of the grains in the samples are equiaxed grains, and a small amount of short columnar grains exist which are parallel to each other. The microstructure of the fabricated samples exhibits a fine basket-weave structure and martensite due to the fast cooling rate which was caused by the small size of the molten pool and the additional heat dissipation from the feeding wire. The static tensile test shows that the average ultimate tensile strength is 1140 MPa in the scanning direction and 1115 MPa in the building direction, and the average elongation is about 6% in both directions. Full article
(This article belongs to the Special Issue Materials for 3D Printing)
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Open AccessArticle Dynamic Response of a Simplified Turbine Blade Model with Under-Platform Dry Friction Dampers Considering Normal Load Variation
Appl. Sci. 2017, 7(3), 228; doi:10.3390/app7030228
Received: 1 January 2017 / Accepted: 20 February 2017 / Published: 1 March 2017
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Abstract
Dry friction dampers are widely used to reduce vibration. The forced vibration response of a simplified turbine blade with a new kind of under-platform dry friction dampers is studied in this paper. The model consists of a clamped blade as two rigidly connected
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Dry friction dampers are widely used to reduce vibration. The forced vibration response of a simplified turbine blade with a new kind of under-platform dry friction dampers is studied in this paper. The model consists of a clamped blade as two rigidly connected beams and two dampers in the form of masses which are allowed to slide along the blade platform in the horizontal direction and vibrate with the blade platform in the vertical direction. The horizontal and vertical vibrations of the two dampers, and the horizontal and transverse platform vibrations are coupled by friction at the contact interfaces which is assumed to follow the classical discontinuous Coulomb’s law of friction. The vertical motion of the dampers leads to time-varying contact forces and can cause horizontal stick-slip motion between the contact surfaces. Due to the relative horizontal motion between the dampers and the blade platform, the vertical contact forces and the resultant friction forces act as moving loads. The Finite Element (FE) method and Modal Superposition (MS) method are applied to solve the dynamic response, together with an algorithm that can capture nonsmooth transitions from stick to slip and slip to stick. Quasi-periodic vibration is found even under harmonic excitation. Full article
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Open AccessArticle Influence of the Water-Cooled Heat Exchanger on the Performance of a Pulse Tube Refrigerator
Appl. Sci. 2017, 7(3), 229; doi:10.3390/app7030229
Received: 4 January 2017 / Revised: 8 February 2017 / Accepted: 23 February 2017 / Published: 28 February 2017
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Abstract
The water-cooled heat exchanger is one of the key components in a pulse tube refrigerator. Its heat exchange effectiveness directly influences the cooling performance of the refrigerator. However, effective heat exchange does not always result in a good performance, because excessively reinforced heat
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The water-cooled heat exchanger is one of the key components in a pulse tube refrigerator. Its heat exchange effectiveness directly influences the cooling performance of the refrigerator. However, effective heat exchange does not always result in a good performance, because excessively reinforced heat exchange can lead to additional flow loss. In this paper, seven different water-cooled heat exchangers were designed to explore the best configuration for a large-capacity pulse tube refrigerator. Results indicated that the heat exchanger invented by Hu always offered a better performance than that of finned and traditional shell-tube types. For a refrigerator with a working frequency of 50 Hz, the best hydraulic diameter is less than 1 mm. Full article
(This article belongs to the Special Issue Heat Transfer Processes in Oscillatory Flow Conditions)
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Open AccessArticle The Application of Homogenate and Filtrate from Baltic Seaweeds in Seedling Growth Tests
Appl. Sci. 2017, 7(3), 230; doi:10.3390/app7030230
Received: 5 January 2017 / Accepted: 17 February 2017 / Published: 28 February 2017
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Abstract
Algal filtrate and homogenate, obtained from Baltic seaweeds, were applied in seedling growth tests. Radish seeds were used in order to assess algal products phytotoxicity and their biostimulant effect on growth and nutrient uptake. Algal filtrate, at concentrations ranging from 5.0% to 100%
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Algal filtrate and homogenate, obtained from Baltic seaweeds, were applied in seedling growth tests. Radish seeds were used in order to assess algal products phytotoxicity and their biostimulant effect on growth and nutrient uptake. Algal filtrate, at concentrations ranging from 5.0% to 100% was used for seed soaking and as a liquid biostimulant (soil and foliar application). Algal homogenate was developed for seed coating. Algal filtrate and homogenate were also enriched with Zn(II) ions in order to examine the influence on metal ion complexation. The optimal doses of algal filtrate and homogenate, as well as soaking time were established. Multi-elemental analyses of the raw biomass, filtrate, homogenate, and radish were also performed using ICP-OES (Inductively Coupled Plasma—Optical Emission Spectrometry). The best results in terms of seedlings’ length and weight were obtained using clear filtrate at a concentration of 50% applied to the soil and for homogenate applied at a dose of 50 mg/g of seeds. Clear filtrate at a concentration of 50% used for seed soaking for one hour showed the best results. The applied algal products increased the content of elements in seedlings. Among the tested products, a concentration of 50% algal filtrate is recommended for future pot and field experiments. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle Heat Flow Characteristics of a Newly-Designed Cooling System with Multi-Fans and Thermal Baffle in the Wheel Loader
Appl. Sci. 2017, 7(3), 231; doi:10.3390/app7030231
Received: 19 December 2016 / Revised: 26 January 2017 / Accepted: 15 February 2017 / Published: 1 March 2017
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Abstract
In the traditional cooling case, there is usually one fan in charge of heat transfer and airflow for all radiators. However, this seems to be inappropriate, or even insufficient, for modern construction machinery, as its overall heat flow density is increasing but thermal
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In the traditional cooling case, there is usually one fan in charge of heat transfer and airflow for all radiators. However, this seems to be inappropriate, or even insufficient, for modern construction machinery, as its overall heat flow density is increasing but thermal distribution is becoming uneven. In order to ensure that the machine works in a better condition, this paper employs a new cooling system with multiple fans and an independent cooling region. Based on the thermal flow and performance requirements, seven fans are divided into three groups. The independent cooling region is segregated from the engine region by a thermal baffle to avoid heat flowing into the engine region and inducing an overheat phenomenon. The experiment validates the efficiency of the new cooling system and accuracy of simulation. After validation, the simulation then analyzes heat transfer and flow characteristics of the cooling system, changing with different cross-sections in different axis directions, as well as different distances of the fan central axes. Finally, thermal baffles are set among the fan groups and provided a better cooling effect. The research realizes a multi-fan scheme with an independent cooling region in a wheel loader, which is a new, but high-efficiency, cooling system and will lead to a new change of various configurations and project designs in future construction machinery. Full article
(This article belongs to the Special Issue Advances in Thermal System Analysis and Optimization)
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Open AccessArticle Enhanced Radiation Therapy of Gold Nanoparticles in Liver Cancer
Appl. Sci. 2017, 7(3), 232; doi:10.3390/app7030232
Received: 15 December 2016 / Revised: 17 February 2017 / Accepted: 22 February 2017 / Published: 1 March 2017
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Abstract
Gold nanoparticles (GNPs) were widely used in X-ray imaging and radiation therapy due to strong photoelectric effects and secondary electrons under high energy irradiation. As liver cancer is one of the most common forms of cancer, the use of GNPs could enhance liver
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Gold nanoparticles (GNPs) were widely used in X-ray imaging and radiation therapy due to strong photoelectric effects and secondary electrons under high energy irradiation. As liver cancer is one of the most common forms of cancer, the use of GNPs could enhance liver cancer radiotherapy. We synthesized polyethylene glycol (PEG)-coated GNPs of two different sizes by chemical reduction reaction. Blood stability, cellular uptake, cytotoxicity and radiation therapy were investigated. A 3–5 nm red shift of SPR caused by interactions between PEG-coated GNPs and plasma indicated their good stability. Cellular uptake assay showed that PEG-coated GNPs would enhance an appreciable uptake. GNPs preferred to combine with blood proteins, and thus induced the formation of 30–50 nm Au-protein corona. GNPs were endocytosed by cytoplasmic vesicles, localized in intracellular region, and presented concentration dependent cell viability. Clonogenic assay illustrated that the PEG-coated GNPs could sensitize two liver cancer cell lines to irradiation. Full article
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Open AccessArticle Numerical Analysis and Optimization on Piezoelectric Properties of 0–3 Type Piezoelectric Cement-Based Materials with Interdigitated Electrodes
Appl. Sci. 2017, 7(3), 233; doi:10.3390/app7030233
Received: 19 November 2016 / Revised: 15 February 2017 / Accepted: 23 February 2017 / Published: 1 March 2017
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Abstract
The health conditions of complicated concrete structures require intrinsic cement-based sensors with a fast sensing response and high accuracy. In this paper, static, modal, harmonic, and transient dynamic analyses for the 0–3 type piezoelectric cement-based material with interdigitated electrodes (IEPCM) wafer were investigated
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The health conditions of complicated concrete structures require intrinsic cement-based sensors with a fast sensing response and high accuracy. In this paper, static, modal, harmonic, and transient dynamic analyses for the 0–3 type piezoelectric cement-based material with interdigitated electrodes (IEPCM) wafer were investigated using the ANSYS finite element numerical approach. Optimal design of the IEPCM was further implemented with electrode distance (P), electrode width (W), and wafer density (H) as the main parameters. Analysis results show that the maximum stress and strain in the x-polarization direction of the IEPCM are 2.6 and 3.19 times higher than that in the y-direction, respectively; there exists no repetition frequency phenomenon for the IEPCM. These indicate 0–3 type IEPCM possesses good orthotropic features, and lateral driving capacity notwithstanding, a hysteresis effect exists. Allowing for the wafer width (Wp) of 1 mm, the optimal design of the IEPCM wafer arrives at the best physical values of H, W and P are 6.2, 0.73 and 1.02 mm respectively, whereas the corresponding optimal volume is 10.9 mm3. Full article
(This article belongs to the Special Issue Structural Health Monitoring (SHM) of Civil Structures)
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Open AccessArticle On the Impact of Particulate Matter Distribution on Pressure Drop of Wall-Flow Particulate Filters
Appl. Sci. 2017, 7(3), 234; doi:10.3390/app7030234
Received: 26 January 2017 / Revised: 20 February 2017 / Accepted: 24 February 2017 / Published: 2 March 2017
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Abstract
Wall-flow particulate filters are a required exhaust aftertreatment system to abate particulate matter emissions and meet current and incoming regulations applying worldwide to new generations of diesel and gasoline internal combustion engines. Despite the high filtration efficiency covering the whole range of emitted
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Wall-flow particulate filters are a required exhaust aftertreatment system to abate particulate matter emissions and meet current and incoming regulations applying worldwide to new generations of diesel and gasoline internal combustion engines. Despite the high filtration efficiency covering the whole range of emitted particle sizes, the porous substrate constitutes a flow restriction especially relevant as particulate matter, both soot and ash, is collected. The dependence of the resulting pressure drop, and hence the fuel consumption penalty, on the particulate matter distribution along the inlet channels is discussed in this paper taking as reference experimental data obtained in water injection tests before the particulate filter. This technique is demonstrated to reduce the particulate filter pressure drop without negative effects on filtration performance. In order to justify these experimental data, the characteristics of the particulate layer are diagnosed applying modeling techniques. Different soot mass distributions along the inlet channels are analyzed combined with porosity change to assess the new properties after water injection. Their influence on the subsequent soot loading process and regeneration is assessed. The results evidence the main mechanisms of the water injection at the filter inlet to reduce pressure drop and boost the interest for control strategies able to force the re-entrainment of most of the particulate matter towards the inlet channels’ end. Full article
(This article belongs to the Special Issue Internal Combustion Engines (ICE) for Ground Transport)
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Open AccessArticle A Timed Colored Petri Net Simulation-Based Self-Adaptive Collaboration Method for Production-Logistics Systems
Appl. Sci. 2017, 7(3), 235; doi:10.3390/app7030235
Received: 28 December 2016 / Accepted: 27 February 2017 / Published: 1 March 2017
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Abstract
Complex and customized manufacturing requires a high level of collaboration between production and logistics in a flexible production system. With the widespread use of Internet of Things technology in manufacturing, a great amount of real-time and multi-source manufacturing data and logistics data is
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Complex and customized manufacturing requires a high level of collaboration between production and logistics in a flexible production system. With the widespread use of Internet of Things technology in manufacturing, a great amount of real-time and multi-source manufacturing data and logistics data is created, that can be used to perform production-logistics collaboration. To solve the aforementioned problems, this paper proposes a timed colored Petri net simulation-based self-adaptive collaboration method for Internet of Things-enabled production-logistics systems. The method combines the schedule of token sequences in the timed colored Petri net with real-time status of key production and logistics equipment. The key equipment is made ‘smart’ to actively publish or request logistics tasks. An integrated framework based on a cloud service platform is introduced to provide the basis for self-adaptive collaboration of production-logistics systems. A simulation experiment is conducted by using colored Petri nets (CPN) Tools to validate the performance and applicability of the proposed method. Computational experiments demonstrate that the proposed method outperforms the event-driven method in terms of reductions of waiting time, makespan, and electricity consumption. This proposed method is also applicable to other manufacturing systems to implement production-logistics collaboration. Full article
(This article belongs to the Special Issue Modeling, Simulation, Operation and Control of Discrete Event Systems)
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Open AccessArticle Full-Field Optical Coherence Tomography as a Diagnosis Tool: Recent Progress with Multimodal Imaging
Appl. Sci. 2017, 7(3), 236; doi:10.3390/app7030236
Received: 20 January 2017 / Revised: 20 February 2017 / Accepted: 21 February 2017 / Published: 2 March 2017
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Abstract
Full-field optical coherence tomography (FF-OCT) is a variant of OCT that is able to register 2D en face views of scattering samples at a given depth. Thanks to its superior resolution, it can quickly reveal information similar to histology without the need to
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Full-field optical coherence tomography (FF-OCT) is a variant of OCT that is able to register 2D en face views of scattering samples at a given depth. Thanks to its superior resolution, it can quickly reveal information similar to histology without the need to physically section the sample. Sensitivity and specificity levels of diagnosis performed with FF-OCT are 80% to 95% of the equivalent histological diagnosis performances and could therefore benefit from improvement. Therefore, multimodal systems have been designed to increase the diagnostic performance of FF-OCT. In this paper, we will discuss which contrasts can be measured with such multimodal systems in the context of ex vivo biological tissue examination. We will particularly emphasize three multimodal combinations to measure the tissue mechanics, dynamics, and molecular content respectively. Full article
(This article belongs to the Special Issue Development and Application of Optical Coherence Tomography (OCT))
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Open AccessArticle Development of a Prolonged-Release Drug Delivery System with Magnolol Loaded in Amino-Functionalized Mesoporous Silica
Appl. Sci. 2017, 7(3), 237; doi:10.3390/app7030237
Received: 14 November 2016 / Revised: 26 January 2017 / Accepted: 27 February 2017 / Published: 2 March 2017
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Abstract
Magnolol (MG) is a small-molecule neolignan polyphenolic compound isolated from the genus Magnolia. The anti-inflammatory, anti-oxidative, anti-diabetic, anti-tumorgenic, anti-neurodegenerative, anti-depressant and anti-microbial properties of MG are well documented in recent literature. These fascinating multiple biological activities of MG encourage research about the
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Magnolol (MG) is a small-molecule neolignan polyphenolic compound isolated from the genus Magnolia. The anti-inflammatory, anti-oxidative, anti-diabetic, anti-tumorgenic, anti-neurodegenerative, anti-depressant and anti-microbial properties of MG are well documented in recent literature. These fascinating multiple biological activities of MG encourage research about the development of new delivery and administration approaches able to maximize its potential benefits. This study describes the amino-functionalization of the SBA-15 (Santa Barbara Amorphous) mesoporous matrix by post-synthesis grafting using APTES (3-aminopropyltriethoxysilane) and the characterization of amino-functionalized mesoporous silica SBA-15 loaded with MG in order to achieve modified drug delivery systems. The amino-functionalization of silica SBA-15 was carried out by grafting by refluxing in dry toluene. The powders obtained were characterized texturally by Brunauer-Emmett-Teller (BET) surface area analysis measurements and morphologically by scanning electron microscopy. MG loading degree in the nanoporous matrix was determined by the HPLC method at λ = 290 nm. Results showed that by grafting the amino groups in the silica SBA-15, we obtained amino-functionalized silica SBA-15 with an ordered structure, with specific surfaces and pore sizes that differ from the original matrix, which was reflected in the amount of MG immobilized and release kinetics profile. Full article
(This article belongs to the Section Nanotechnology and Applied Nanosciences)
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Open AccessArticle Prediction of Critical Currents for a Diluted Square Lattice Using Artificial Neural Networks
Appl. Sci. 2017, 7(3), 238; doi:10.3390/app7030238
Received: 30 December 2016 / Revised: 21 February 2017 / Accepted: 21 February 2017 / Published: 2 March 2017
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Abstract
Studying critical currents, critical temperatures, and critical fields carries substantial importance in the field of superconductivity. In this work, we study critical currents in the current–voltage characteristics of a diluted-square lattice on an Nb film. Our measurements are based on a commercially available
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Studying critical currents, critical temperatures, and critical fields carries substantial importance in the field of superconductivity. In this work, we study critical currents in the current–voltage characteristics of a diluted-square lattice on an Nb film. Our measurements are based on a commercially available Physical Properties Measurement System, which may prove time consuming and costly for repeated measurements for a wide range of parameters. We therefore propose a technique based on artificial neural networks to facilitate extrapolation of these curves for unforeseen values of temperature and magnetic fields. We demonstrate that our proposed algorithm predicts the curves with an immaculate precision and minimal overhead, which may as well be adopted for prediction in other types of regular and diluted lattices. In addition, we present a detailed comparison between three artificial neural networks architectures with respect to their prediction efficiency, computation time, and number of iterations to converge to an optimal solution. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Active Vibration Suppression of a Motor-Driven Piezoelectric Smart Structure Using Adaptive Fuzzy Sliding Mode Control and Repetitive Control
Appl. Sci. 2017, 7(3), 240; doi:10.3390/app7030240
Received: 28 December 2016 / Revised: 10 February 2017 / Accepted: 28 February 2017 / Published: 4 March 2017
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Abstract
In this paper, we report on the use of piezoelectric sensors and actuators for the active suppression of vibrations associated with the motor-driven rotation of thin flexible plate held vertically. Motor-driven flexible structures are multi-input multi-output systems. The design of active vibration-suppression controllers
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In this paper, we report on the use of piezoelectric sensors and actuators for the active suppression of vibrations associated with the motor-driven rotation of thin flexible plate held vertically. Motor-driven flexible structures are multi-input multi-output systems. The design of active vibration-suppression controllers for these systems is far more challenging than for flexible structures with a fixed end, due to the effects of coupling and nonlinear vibration behavior generated in structures with poor damping. To simplify the design of the controller and achieve satisfactory vibration suppression, we treated the coupling of vibrations caused by the rotary motion of the thin flexible plate as external disturbances and system uncertainties. We employed an adaptive fuzzy sliding mode control algorithm in the design of a single-input–single-output controller for the suppression of vibrations using piezoelectric sensors and actuators. We also used a repetitive control system to reduce periodic vibrations associated with the repetitive motions induced by the motor. Experimental results demonstrate that the hybrid intelligent control approach proposed in this study can suppress complex vibrations caused by modal excitation, coupling effects, and periodic external disturbances. Full article
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Open AccessArticle Multi-Temporal Remotely Sensed Data for Degradation Dynamics in Linxia Rangeland, Northwest China
Appl. Sci. 2017, 7(3), 241; doi:10.3390/app7030241
Received: 27 October 2016 / Revised: 17 December 2016 / Accepted: 23 January 2017 / Published: 3 March 2017
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Abstract
The importance of accurately monitoring rangeland degradation dynamics over decades is increasing in Linxia rangeland, the birthplace of the Yellow River in China. Since 2000, the Chinese government has implemented the “Grain for Green” program and enforced a grazing ban in Gansu province,
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The importance of accurately monitoring rangeland degradation dynamics over decades is increasing in Linxia rangeland, the birthplace of the Yellow River in China. Since 2000, the Chinese government has implemented the “Grain for Green” program and enforced a grazing ban in Gansu province, one of the most degraded provinces, to mitigate the problem of rangeland degradation. The effects of these policies are controversial and have become a topic of public concern. In this study, a grading system was established for the estimation of Linxia rangeland degradation. Degrees of rangeland degradation were interpreted and the spatio-temporal dynamics of the degraded rangeland through several study periods were mapped and monitored using the Linear Spectral Mixture Analysis method on Landsat Thematic Mapper (TM)/ETM+ (Enhanced Thematic Mapper Plus) images for the years of 1996, 2001, 2006, and 2011. The results demonstrated that the time around the year 2001 appeared to be a turning point of the rangeland degradation reversion course, as the rangeland degradation reversed significantly since 2001. From 1996 to 2001, the total degraded area in Linxia rangeland increased from 2922.01 km2 to 3048.48 km2 (+4.33%), and decreased by 4.54% to 2909.97 km2 in 2011; the non-degraded rangeland gradually increased from 602.74 km2 to 710.01 km2, an increase of 17.80%. Degraded rangeland vegetation was restored significantly during 2001–2011: the area of slightly degraded rangeland increased by 3.71% and 3.83% annually during 2001–2006 and 2006–2011 intervals, respectively, and the area of moderately and severely degraded rangeland decreased annually by 4.77% and 2.41% from 2001 to 2006, and 4.58% and 0.81% during 2006–2011, respectively. These results indicated that the “Grain for Green” program and grazing ban policy, together with other ecological impacting factors, helped reverse the rangeland degradation and promote the rehabilitation of rangeland vegetation. Full article
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Open AccessArticle Synthesis and Physical Properties of Polyhydroxyalkanoate Polymers with Different Monomer Compositions by Recombinant Pseudomonas putida LS46 Expressing a Novel PHA SYNTHASE (PhaC116) Enzyme
Appl. Sci. 2017, 7(3), 242; doi:10.3390/app7030242
Received: 23 December 2016 / Revised: 29 January 2017 / Accepted: 23 February 2017 / Published: 3 March 2017
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Abstract
A recombinant of Pseudomonas putida LS461 (deletion of the phaC1phaZphaC2 genes) was constructed by introducing cosmid JC123 carrying a novel phaC116 gene from a metagenomic clone. The resulting strain, P. putida LS46123, was able to synthesize polyhydroxyalkanoate (PHA) polymers with novel monomer
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A recombinant of Pseudomonas putida LS461 (deletion of the phaC1phaZphaC2 genes) was constructed by introducing cosmid JC123 carrying a novel phaC116 gene from a metagenomic clone. The resulting strain, P. putida LS46123, was able to synthesize polyhydroxyalkanoate (PHA) polymers with novel monomer compositions when cultured on glucose or free fatty acids, and accumulated PHAs from 9.24% to 27.09% of cell dry weight. The PHAs synthesized by P. putida LS46123 contained up to 50 mol % short chain length subunits (3-hydroxybutyrate and 3-hydroxyvalerate), with the remaining monomers consisting of various medium chain length subunits. The PhaC116 protein expressed by P. putida LS46123 had an amino acid sequence similarity of 45% with the PhaC1 protein of the parent strain, P. putida LS46. Predicted 3D structures of the PhaC116 proteins from P. putida LS46123 and P. putida LS46 revealed several differences in the numbers and locations of protein secondary structures. The physical and thermal properties of the novel polymers synthesized by P. putida LS46123 cultured with glucose or free fatty acids differed significantly from those produced by P. putida LS46 grown on the same substrates. PHA polymers with different subunit compositions, and hence different physical and thermal properties, can be tailor-made using novel PHA synthase for specific applications. Full article
(This article belongs to the Special Issue Polyhydroxyalkanoates and Their Applications)
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Open AccessArticle Reconstruction to Sensor Measurements Based on a Correlation Model of Monitoring Data
Appl. Sci. 2017, 7(3), 243; doi:10.3390/app7030243
Received: 19 January 2017 / Revised: 25 February 2017 / Accepted: 28 February 2017 / Published: 3 March 2017
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Abstract
A sensor failure will lead to sensor measurement distortion, and may reduce the reliability of the whole structure analysis. This paper studies the method of monitoring information reconstruction based on the correlation degree. For the faulty sensor, the correlation degree of the normal
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A sensor failure will lead to sensor measurement distortion, and may reduce the reliability of the whole structure analysis. This paper studies the method of monitoring information reconstruction based on the correlation degree. For the faulty sensor, the correlation degree of the normal response of this sensor and the measurements of the other sensors is calculated, which is also called the correlation degree of reconstructed variables and response variables. By comparing the correlation degrees, the response variables, which are needed to establish the correlation model, are determined. The correlation model between the reconstructed variables and the response variables is established by the partial least square method. The value of the correlation degrees between the reconstructed variables and the response variables, the amount of the monitoring data which is used to determine the coefficients of the correlation model, and the number of the response variables are used to discuss the influence factors of the reconstruction error. The stress measurements of structural health monitoring system of Shenzhen Bay Stadium is taken as an example, and the effectiveness of the method is verified and the practicability of the method is illustrated. Full article
(This article belongs to the Special Issue Structural Health Monitoring (SHM) of Civil Structures)
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Open AccessArticle Electronically Tunable Current Controlled Current Conveyor Transconductance Amplifier-Based Mixed-Mode Biquadratic Filter with Resistorless and Grounded Capacitors
Appl. Sci. 2017, 7(3), 244; doi:10.3390/app7030244
Received: 22 December 2016 / Revised: 27 February 2017 / Accepted: 1 March 2017 / Published: 4 March 2017
Cited by 1 | PDF Full-text (7508 KB) | HTML Full-text | XML Full-text
Abstract
A new electronically tunable mixed-mode biquadratic filter with three current controlled current conveyor transconductance amplifiers (CCCCTAs) and two grounded capacitors is proposed. With current input, the filter can realise lowpass (LP), bandpass (BP), highpass (HP), bandstop (BS) and allpass (AP) responses in current
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A new electronically tunable mixed-mode biquadratic filter with three current controlled current conveyor transconductance amplifiers (CCCCTAs) and two grounded capacitors is proposed. With current input, the filter can realise lowpass (LP), bandpass (BP), highpass (HP), bandstop (BS) and allpass (AP) responses in current mode and LP, BP and HP responses in transimpedance mode. With voltage input, the filter can realise LP, BP, HP, BS and AP responses in voltage and transadmittance modes. Other attractive features of the mixed-mode biquadratic filter are (1) the use of two grounded capacitors, which is ideal for integrated circuit implementation; (2) orthogonal control of the quality factor (Q) and resonance angular frequency (ωo) for easy electronic tenability; (3) low input impedance and high output impedance for current signals; (4) high input impedance for voltage signal; (5) avoidance of need for component-matching conditions; (6) resistorless and electronically tunable structure; (7) low active and passive sensitivities; and (8) independent control of the voltage transfer gains without affecting the parameters ωo and Q. Full article
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Open AccessArticle Development of a Staggered PCD End Mill for Carbon Fiber Reinforced Plastic
Appl. Sci. 2017, 7(3), 245; doi:10.3390/app7030245
Received: 23 December 2016 / Accepted: 27 February 2017 / Published: 3 March 2017
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Abstract
This work presents a PCD (polycrystalline diamond) end mill with a new staggered structure for the milling of CFRP (carbon fiber reinforced plastic). The magnitude and direction of cutting force is decreased and changed by side-edge re-configuration of the structure. The flute and
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This work presents a PCD (polycrystalline diamond) end mill with a new staggered structure for the milling of CFRP (carbon fiber reinforced plastic). The magnitude and direction of cutting force is decreased and changed by side-edge re-configuration of the structure. The flute and insert pocket of the staggered PCD end mill are designed considering the tool’s stiffness and welding process. The milling process and machining defects of the staggered PCD end mill are analyzed, and the structural parameters of the staggered PCD end mill are determined. The staggered PCD end mill is fabricated by the process of wire cutting, NC (Numerical Control) machining, high-frequency induction brazing, welding, grinding and passivation. Milling tests of multidirectional CFRP with the staggered PCD end mill is conducted on CNC (Computerized Numerical Control) milling machine. The milling force is measured by a dynamometer. A range analysis of the numerical results of milling force is conducted after milling test, and the influence of milling parameters on milling force is analyzed. A regression model of the milling force is built and verified by experiment. The effects of fiber cutting angle on milling force are obtained through milling CFRP with different fiber orientation angles. Full article
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Open AccessArticle Natural Convection Flow of Fractional Nanofluids Over an Isothermal Vertical Plate with Thermal Radiation
Appl. Sci. 2017, 7(3), 247; doi:10.3390/app7030247
Received: 27 November 2016 / Accepted: 1 March 2017 / Published: 3 March 2017
Cited by 2 | PDF Full-text (2105 KB) | HTML Full-text | XML Full-text
Abstract
The studies of classical nanofluids are restricted to models described by partial differential equations of integer order, and the memory effects are ignored. Fractional nanofluids, modeled by differential equations with Caputo time derivatives, are able to describe the influence of memory on the
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The studies of classical nanofluids are restricted to models described by partial differential equations of integer order, and the memory effects are ignored. Fractional nanofluids, modeled by differential equations with Caputo time derivatives, are able to describe the influence of memory on the nanofluid behavior. In the present paper, heat and mass transfer characteristics of two water-based fractional nanofluids, containing nanoparticles of CuO and Ag, over an infinite vertical plate with a uniform temperature and thermal radiation, are analytically and graphically studied. Closed form solutions are determined for the dimensionless temperature and velocity fields, and the corresponding Nusselt number and skin friction coefficient. These solutions, presented in equivalent forms in terms of the Wright function or its fractional derivatives, have also been reduced to the known solutions of ordinary nanofluids. The influence of the fractional parameter on the temperature, velocity, Nusselt number, and skin friction coefficient, is graphically underlined and discussed. The enhancement of heat transfer in the natural convection flows is lower for fractional nanofluids, in comparison to ordinary nanofluids. In both cases, the fluid temperature increases for increasing values of the nanoparticle volume fraction. Full article
(This article belongs to the Special Issue Recent Developments of Nanofluids)
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Open AccessArticle The Effects of Wet Compression by the Electronic Expansion Valve Opening on the Performance of a Heat Pump System
Appl. Sci. 2017, 7(3), 248; doi:10.3390/app7030248
Received: 9 January 2017 / Accepted: 1 March 2017 / Published: 3 March 2017
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Abstract
In this study, by controlling the Electronic Expansion Valve opening, the influence of wet compression on a heat pump system was experimentally investigated in different heating conditions. The results demonstrate that the discharge temperature decreased and the mass flow rate increased, due to
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In this study, by controlling the Electronic Expansion Valve opening, the influence of wet compression on a heat pump system was experimentally investigated in different heating conditions. The results demonstrate that the discharge temperature decreased and the mass flow rate increased, due to quality of the rising liquid droplets. It was also found that the heating capacity and power input of wet compression increased more than that of dry compression, with a superheat of 10 °C. The maximum COP (Coefficient of Performance) exists at a specific quality of ca. 0.94 to 0.90, as the power input in the region of wet compression is proportionally larger than the increase in the heating capacity, according to the decreasing quality. When the Entering Water Temperature of the Outdoor Heat Exchanger was 10 °C, 5 °C, and 0 °C, the COP increased by a maximum of ca. 12.4%, 10.6%, and 10.2%, respectively, in comparison to the superheat of 10 °C. In addition, the superheat at the discharge line is proposed as a proper controlling parameter to adjust the quality at the suction line, by varying the opening of the expansion valve during wet compression. Full article
(This article belongs to the Special Issue Sciences in Heat Pump and Refrigeration)
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Open AccessArticle A Measure Based on Beamforming Power for Evaluation of Sound Field Reproduction Performance
Appl. Sci. 2017, 7(3), 249; doi:10.3390/app7030249
Received: 16 January 2017 / Accepted: 27 February 2017 / Published: 3 March 2017
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Abstract
This paper proposes a measure to evaluate sound field reproduction systems with an array of loudspeakers. The spatially-averaged squared error of the sound pressure between the desired and the reproduced field, namely the spatial error, has been widely used, which has considerable problems
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This paper proposes a measure to evaluate sound field reproduction systems with an array of loudspeakers. The spatially-averaged squared error of the sound pressure between the desired and the reproduced field, namely the spatial error, has been widely used, which has considerable problems in two conditions. First, in non-anechoic conditions, room reflections substantially deteriorate the spatial error, although these room reflections affect human localization to a lesser degree. Second, for 2.5-dimensional reproduction of spherical waves, the spatial error increases consistently due to the difference in the amplitude decay rate, whereas the degradation of human localization performance is limited. The measure proposed in this study is based on the beamforming powers of the desired and the reproduced fields. Simulation and experimental results show that the proposed measure is less sensitive to room reflections and the amplitude decay than the spatial error, which is likely to agree better with the human perception of source localization. Full article
(This article belongs to the Special Issue Spatial Audio)
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Open AccessFeature PaperArticle Novel Composite Powders with Uniform TiB2 Nano-Particle Distribution for 3D Printing
Appl. Sci. 2017, 7(3), 250; doi:10.3390/app7030250
Received: 5 January 2017 / Revised: 3 February 2017 / Accepted: 16 February 2017 / Published: 6 March 2017
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Abstract
It is reported that the ductility and strength of a metal matrix composite could be concurrently improved if the reinforcing particles were of the size of nanometers and distributed uniformly. In this paper, we revealed that gas atomization solidification could effectively disperse TiB
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It is reported that the ductility and strength of a metal matrix composite could be concurrently improved if the reinforcing particles were of the size of nanometers and distributed uniformly. In this paper, we revealed that gas atomization solidification could effectively disperse TiB2 nanoparticles in the Al alloy matrix due to its fast cooling rate and the coherent orientation relationship between TiB2 particles and α-Al. Besides, nano-TiB2 led to refined equiaxed grain structures. Furthermore, the composite powders with uniformly embedded nano-TiB2 showed improved laser absorptivity. The novel composite powders are well suited for selective laser melting. Full article
(This article belongs to the Special Issue Materials for 3D Printing)
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Open AccessArticle Design and Testing of a Novel Building Integrated Cross Axis Wind Turbine
Appl. Sci. 2017, 7(3), 251; doi:10.3390/app7030251
Received: 31 December 2016 / Revised: 6 February 2017 / Accepted: 27 February 2017 / Published: 8 March 2017
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Abstract
The prospect of harnessing wind energy in urban areas is not promising owing to low wind speeds and the turbulence caused by surrounding obstacles. However, these challenges can be overcome through an improved design of wind turbine that can operate efficiently in an
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The prospect of harnessing wind energy in urban areas is not promising owing to low wind speeds and the turbulence caused by surrounding obstacles. However, these challenges can be overcome through an improved design of wind turbine that can operate efficiently in an urban environment. This paper presents a novel design of a building integrated cross axis wind turbine (CAWT) that can operate under dual wind direction, i.e., horizontal wind and vertical wind from the bottom of the turbine. The CAWT consists of six horizontal blades and three vertical blades for enhancing its self-starting behavior and overall performance. The study employed a mock-up building model with gable rooftop where both of the developed CAWT and the conventional straight-bladed vertical axis wind turbine (VAWT) are mounted and tested on the rooftop. The height of the CAWT and the VAWT above the rooftop was varied from 100 to 250 mm under the same experimental conditions. The results obtained from the experimental study showed that there is significant improvement in the coefficient of power (Cp) and self-starting behavior of the building integrated CAWT compared to the straight-bladed VAWT. At 100 mm height, the Cp,max value of the CAWT increased by 266%, i.e., from 0.0345 to 0.1263, at tip speed ratio (TSR) (λ) of 1.1 and at wind speed of 4.5 m/s. Similar improvements in performance are also observed for all condition of CAWT heights above the rooftop where the CAWT outperformed the straight-bladed VAWT by 196%, 136% and 71% at TSR of 1.16, 1.08, and 1.12 for Y = 150, 200, and 250 mm, respectively. Moreover, the CAWT performs better at 10° pitch angle of the horizontal blade compared to other pitch angles. Full article
(This article belongs to the Section Energy)
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Open AccessFeature PaperArticle Synthesis of Injectable Alginate Hydrogels with Muscle-Derived Stem Cells for Potential Myocardial Infarction Repair
Appl. Sci. 2017, 7(3), 252; doi:10.3390/app7030252
Received: 15 December 2016 / Revised: 4 February 2017 / Accepted: 28 February 2017 / Published: 4 March 2017
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Abstract
Myocardial infarction (MI), caused by the occlusion of the left ventricular coronary artery, leads to the loss of cardiomyocytes and, potentially, heart failure. Cardiomyocytes in adult mammals proliferate at an extremely low rate and thus, a major challenge in MI treatment is supplementing
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Myocardial infarction (MI), caused by the occlusion of the left ventricular coronary artery, leads to the loss of cardiomyocytes and, potentially, heart failure. Cardiomyocytes in adult mammals proliferate at an extremely low rate and thus, a major challenge in MI treatment is supplementing exogenous cells and keeping them viable in MI areas. To address this challenge, injecting hydrogels encapsulating cells into MI areas, to compensate for the loss of cardiomyocytes, shows promise. This study synthesized two types of alginate hydrogels, based on self-crosslinking (SCL) and calcium ion crosslinking (Ca2+) in varying formulations. The hydrogels encapsulated living muscle-derived stem cells (MDSCs) and their performance was evaluated in terms of optimizing cell viability during the injection process, as well as the live/dead rate after long-term cultivation. The morphology of the hydrogel-encapsulated cells was characterized by scanning electronic microscopy (SEM) and live/dead cells were examined using an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide staining) assay. The mechanical properties of the hydrogels were also determined via a rheometer, to identify their influence on cell viability during the injection process and with respect to long-term cultivation. The SCL hydrogel with a 0.8% alginate and 20% gelatin formulation resulted in the highest cell viability during the injection process, and the Ca2+ hydrogel composed of 1.1% alginate and 20% gelatin maintained the highest cell survival rate after two months in culture. Full article
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Open AccessArticle Friction Factor Correlation for Regenerator Working in a Travelling-Wave Thermoacoustic System
Appl. Sci. 2017, 7(3), 253; doi:10.3390/app7030253
Received: 25 January 2017 / Revised: 27 February 2017 / Accepted: 2 March 2017 / Published: 5 March 2017
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Abstract
Regenerator is a porous solid structure which is important in the travelling-wave thermoacoustic system. It provides the necessary contact surface and thermal capacity for the working gas to undergo a thermodynamic cycle under acoustic oscillatory flow conditions. However, it also creates a pressure
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Regenerator is a porous solid structure which is important in the travelling-wave thermoacoustic system. It provides the necessary contact surface and thermal capacity for the working gas to undergo a thermodynamic cycle under acoustic oscillatory flow conditions. However, it also creates a pressure drop that could degrade the overall system performance. Ideally, in a travelling-wave system, the phase angle between oscillating pressure and velocity in the regenerator should be zero, or as close to zero as possible. In this study, the hydrodynamic condition of a regenerator has been investigated both experimentally (in a purpose-built rig providing a travelling-wave phasing) and numerically. A two-dimensional ANSYS FLUENT CFD model, capturing the important features of the experimental conditions, has been developed. The findings suggest that a steady-state correlation, commonly used in designing thermoacoustic systems, is applicable provided that the travelling-wave phase angle is maintained. However, for coarse mesh regenerators, the results show interesting “phase shifting” phenomena, which may limit the correlation validity. Current experimental and CFD studies are important for predicting the viscous losses in future models of thermoacoustic systems. Full article
(This article belongs to the Special Issue Heat Transfer Processes in Oscillatory Flow Conditions)
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Open AccessArticle A Visual Analytics Approach for Detecting and Understanding Anomalous Resident Behaviors in Smart Healthcare
Appl. Sci. 2017, 7(3), 254; doi:10.3390/app7030254
Received: 31 December 2016 / Revised: 25 February 2017 / Accepted: 27 February 2017 / Published: 7 March 2017
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Abstract
With the development of science and technology, it is possible to analyze residents’ daily behaviors for the purpose of smart healthcare in the smart home environment. Many researchers have begun to detect residents’ anomalous behaviors and assess their physical condition, but these approaches
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With the development of science and technology, it is possible to analyze residents’ daily behaviors for the purpose of smart healthcare in the smart home environment. Many researchers have begun to detect residents’ anomalous behaviors and assess their physical condition, but these approaches used by the researchers are often caught in plight caused by a lack of ground truth, one-sided analysis of behavior, and difficulty of understanding behaviors. In this paper, we put forward a smart home visual analysis system (SHVis) to help analysts detect and comprehend unusual behaviors of residents, and predict the health information intelligently. Firstly, the system classifies daily activities recorded by sensor devices in smart home environment into different categories, and discovers unusual behavior patterns of residents living in this environment by using various characteristics extracted from those activities and appropriate unsupervised anomaly detection algorithm. Secondly, on the basis of figuring out the residents’ anomaly degree of every date, we explore the daily behavior patterns and details with the help of several visualization views, and compare and analyze residents’ activities of various dates to find the reasons why residents act unusually. In the case study of this paper, we analyze residents’ behaviors that happened over two months and find unusual indoor behaviors and give health advice to the residents. Full article
(This article belongs to the Special Issue Smart Healthcare)
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Open AccessArticle Performance of a Supercritical CO2 Bottoming Cycle for Aero Applications
Appl. Sci. 2017, 7(3), 255; doi:10.3390/app7030255
Received: 31 December 2016 / Revised: 20 February 2017 / Accepted: 28 February 2017 / Published: 6 March 2017
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Abstract
By 2050, the evolutionary approach to aero engine research may no longer provide meaningful returns on investment, whereas more radical approaches to improving thermal efficiency and reducing emissions might still prove cost effective. One such radical concept is the addition of a secondary
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By 2050, the evolutionary approach to aero engine research may no longer provide meaningful returns on investment, whereas more radical approaches to improving thermal efficiency and reducing emissions might still prove cost effective. One such radical concept is the addition of a secondary power cycle that utilizes the otherwise largely wasted residual heat in the core engine’s exhaust gases. This could provide additional shaft power. Supercritical carbon dioxide closed-circuit power cycles are currently being investigated primarily for stationary power applications, but their high power density and efficiency, even for modest peak cycle temperatures, makes them credible bottoming cycle options for aero engine applications. Through individual geometric design and performance studies for each of the bottoming cycle’s major components, it was determined that a simple combined cycle aero engine could offer a 1.9% mission fuel burn benefit over a state-of-the-art geared turbofan for the year 2050. However, the even greater potential of more complex systems demands further investigation. For example, adding inter-turbine reheat (ITR) to the combined cycle is predicted to significantly improve the fuel burn benefit. Full article
(This article belongs to the Special Issue Gas Turbines Propulsion and Power)
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Open AccessArticle Understanding Hydrothermal Dechlorination of PVC by Focusing on the Operating Conditions and Hydrochar Characteristics
Appl. Sci. 2017, 7(3), 256; doi:10.3390/app7030256
Received: 26 December 2016 / Revised: 20 February 2017 / Accepted: 27 February 2017 / Published: 6 March 2017
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Abstract
To remove chlorine from chlorinated wastes efficiently, the hydrothermal treatment (HT) of PVC was investigated with a lower alkaline dosage in this work. Some typical operating conditions were investigated to find out the most important factor affecting the dechlorination efficiency (DE). The FTIR
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To remove chlorine from chlorinated wastes efficiently, the hydrothermal treatment (HT) of PVC was investigated with a lower alkaline dosage in this work. Some typical operating conditions were investigated to find out the most important factor affecting the dechlorination efficiency (DE). The FTIR technique was employed to detect the functional groups in PVC and hydrochars generated to reveal the possible pathways for chlorine removal. The results show that the HT temperature was a key parameter to control the dechlorination reaction rate. At a HT temperature of 240 °C, about 94.3% of chlorine could be removed from the PVC with 1% NaOH. The usage of NaOH was helpful for chlorine removal, while a higher dosage might also hinder this process because of the surface poisoning and coverage of free sites. To some extent, the DE was increased with the residence time. At a residence time of 30 min, the DE reached a maximum of 76.74%. A longer residence time could promote the generation of pores in hydrochar which is responsible for the reduction in DE because of the re-absorption of water-soluble chlorine. According to the FTIR results, the peak intensities of both C=CH and C=C stretching vibrations in hydrochar were increased, while the peak at around 3300 cm−1 representing the –OH group was not obvious, indicating that the dehydrochlorination (elimination reaction) was a main route for chlorine removal under these conditions studied in this work. Full article
(This article belongs to the Section Energy)
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Open AccessArticle Global Synchronization of Multichannel EEG   Based on Rényi Entropy in Children with Autism  Spectrum Disorder
Appl. Sci. 2017, 7(3), 257; doi:10.3390/app7030257
Received: 31 December 2016 / Accepted: 4 March 2017 / Published: 6 March 2017
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Abstract
Autism spectrum disorder (ASD) has been defined as a pervasive neurodevelopmental disorder, involving communication, social interaction and repetitive behaviors. Currently, it is still challenging to understand the differences of brain activity between ASD and healthy children. In this study, we propose calculating the
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Autism spectrum disorder (ASD) has been defined as a pervasive neurodevelopmental disorder, involving communication, social interaction and repetitive behaviors. Currently, it is still challenging to understand the differences of brain activity between ASD and healthy children. In this study, we propose calculating the Rényi entropy of the eigenvalues derived from the signal correlation matrix to measure the global synchronization in multichannel electroencephalograph (EEG) from 16 children with ASD (aged 8–12 years) and 16 age‐ and sex‐matched healthy controls at the resting state. The results indicate that there is a significantly diminished global synchronization from ASD to healthy control. The proposed method can help to reveal the intrinsic characteristics of multichannel EEG signals in children with ASD and aspects that distinguish them from healthy children. Full article
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Open AccessArticle Interactive Rhythm Learning System by Combining Tablet Computers and Robots
Appl. Sci. 2017, 7(3), 258; doi:10.3390/app7030258
Received: 30 December 2016 / Accepted: 4 March 2017 / Published: 7 March 2017
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Abstract
This study proposes a percussion learning device that combines tablet computers and robots. This device comprises two systems: a rhythm teaching system, in which users can compose and practice rhythms by using a tablet computer, and a robot performance system. First, teachers compose
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This study proposes a percussion learning device that combines tablet computers and robots. This device comprises two systems: a rhythm teaching system, in which users can compose and practice rhythms by using a tablet computer, and a robot performance system. First, teachers compose the rhythm training contents on the tablet computer. Then, the learners practice these percussion exercises by using the tablet computer and a small drum set. The teaching system provides a new and user-friendly score editing interface for composing a rhythm exercise. It also provides a rhythm rating function to facilitate percussion training for children and improve the stability of rhythmic beating. To encourage children to practice percussion exercises, a robotic performance system is used to interact with the children; this system can perform percussion exercises for students to listen to and then help them practice the exercise. This interaction enhances children’s interest and motivation to learn and practice rhythm exercises. The results of experimental course and field trials reveal that the proposed system not only increases students’ interest and efficiency in learning but also helps them in understanding musical rhythms through interaction and composing simple rhythms. Full article
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Open AccessArticle Coupled Effect of Expansion Ratio and Blade Loading on the Aerodynamics of a High-Pressure Gas Turbine
Appl. Sci. 2017, 7(3), 259; doi:10.3390/app7030259
Received: 31 January 2017 / Accepted: 1 March 2017 / Published: 7 March 2017
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Abstract
The need of a continuous improvement in gas turbine efficiency for propulsion and power generation, as well as the more demanding operating conditions and power control required to these machines, still ask for great efforts in the design and analysis of the high
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The need of a continuous improvement in gas turbine efficiency for propulsion and power generation, as well as the more demanding operating conditions and power control required to these machines, still ask for great efforts in the design and analysis of the high pressure section of the turbo-expander. To get detailed insights and improve the comprehension of the flow physics, a wide experimental campaign has been performed in the last ten years at Politecnico di Milano on the unsteady aerodynamics of a high-pressure turbine stage considering several operating conditions. This paper presents and discusses the experimental results obtained for the stage operating with different expansion ratios and rotor loading. The turbine stage under study is representative of a modern high-pressure turbine and can be operated in both subsonic and transonic conditions. The experimental tools applied for the current research represents the state of the art when unsteady investigations are foreseen. The detailed flow field, the blade–rows interaction and the overall performance are described and discussed; efforts have been devoted to the discussion of the various contribution to the overall stage efficiency. The direct effects of the expansion ratio, affecting the Reynolds and the Mach numbers, have been highlighted and quantified; similarly, the indirect effects, accounting for a change in the rotor loading, have been commented and quantified as well, thanks to a dedicated set of experiments where different rotor loadings at the same expansion ratio have been prescribed. Full article
(This article belongs to the Special Issue Gas Turbines Propulsion and Power)
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Open AccessArticle An IoT System for Remote Monitoring of Patients at Home
Appl. Sci. 2017, 7(3), 260; doi:10.3390/app7030260
Received: 18 December 2016 / Revised: 14 February 2017 / Accepted: 1 March 2017 / Published: 8 March 2017
Cited by 2 | PDF Full-text (5645 KB) | HTML Full-text | XML Full-text
Abstract
Application areas that utilize the concept of IoT can be broadened to healthcare or remote monitoring areas. In this paper, a remote monitoring system for patients at home in IoT environments is proposed, constructed, and evaluated through several experiments. To make it operable
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Application areas that utilize the concept of IoT can be broadened to healthcare or remote monitoring areas. In this paper, a remote monitoring system for patients at home in IoT environments is proposed, constructed, and evaluated through several experiments. To make it operable in IoT environments, a protocol conversion scheme between ISO/IEEE 11073 protocol and oneM2M protocol, and a Multiclass Q-learning scheduling algorithm based on the urgency of biomedical data delivery to medical staff are proposed. In addition, for the sake of patients’ privacy, two security schemes are proposed—the separate storage scheme of data in parts and the Buddy-ACK authorization scheme. The experiment on the constructed system showed that the system worked well and the Multiclass Q-learning scheduling algorithm performs better than the Multiclass Based Dynamic Priority scheduling algorithm. We also found that the throughputs of the Multiclass Q-learning scheduling algorithm increase almost linearly as the measurement time increases, whereas the throughputs of the Multiclass Based Dynamic Priority algorithm increase with decreases in the increasing ratio. Full article
(This article belongs to the Special Issue Smart Healthcare)
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Open AccessArticle The Effect of EN Ratio and Current on Microstructural and Mechanical Properties of Weld Joined by AC-GMAW on Square Groove Butt Joints
Appl. Sci. 2017, 7(3), 261; doi:10.3390/app7030261
Received: 24 January 2017 / Accepted: 3 March 2017 / Published: 7 March 2017
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Abstract
In the present work, the effect of welding current and electrode negative (EN) ratio on microstructure and mechanical properties of square groove butt joint produced by alternating current gas metal arc welding (AC-GMAW) process has been investigated. The experiments were conducted using different
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In the present work, the effect of welding current and electrode negative (EN) ratio on microstructure and mechanical properties of square groove butt joint produced by alternating current gas metal arc welding (AC-GMAW) process has been investigated. The experiments were conducted using different combination of welding current ranging from 150 A to 250 A with three distinct EN ratios i.e., 0%, 30% and 50% on 5 mm thick steel plates at a constant joint gap of 1 mm and welding speed of 10 mm/s. The effect of current and EN ratio on welding soundness was evaluated through optical microscopy, tensile tests and micro-hardness mapping. The results revealed that, at higher values of currents, an increase in EN ratio resulted an increase in penetration depth. It was found that at a current of 250 A and a 50% EN ratio, the deep penetration was obtained. Tensile test results showed that the tensile strength properties improved with increasing current. Furthermore, the micro-hardness distribution was not strikingly affected by changing the EN ratio. Full article
(This article belongs to the Special Issue Gas Metal Arc Welding)
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Open AccessArticle Application of Electrical Resistivity Data Sets for the Evaluation of the Pollution Concentration Level within Landfill Subsoil
Appl. Sci. 2017, 7(3), 262; doi:10.3390/app7030262
Received: 13 December 2016 / Revised: 24 February 2017 / Accepted: 1 March 2017 / Published: 9 March 2017
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Abstract
The paper presents complex analyses of geophysical site investigation results. The electrical resistivity method was used to investigate the potential pollutant migration pathways within areas of existing and former landfill sites. For the purpose of the present study, there were four municipal waste
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The paper presents complex analyses of geophysical site investigation results. The electrical resistivity method was used to investigate the potential pollutant migration pathways within areas of existing and former landfill sites. For the purpose of the present study, there were four municipal waste landfills and one industrial landfill chosen for further comprehensive analyses. The landfill bottom was isolated using geomembrane liner. However, ground water monitoring results revealed that the base was not leakage-free. Another two landfills were established in the past, when no containment systems were legally required. The geoelectrical investigation was the final part of an overall analytical assessment of the contaminated sites. The study was aimed at pollution spatial migration analyses and the interpretation of results, for further design of the reclamation and restoration plans. A clear correlation between pollution indicators such as salt compounds and electrical resistivity, allow aerial analyses and the precise determination of contaminated zones. The research results presented in the paper have been recently obtained and concern a period from 2010 to 2015. Full article
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Open AccessArticle In Situ Measurement of Alkali Metals in an MSW Incinerator Using a Spontaneous Emission Spectrum
Appl. Sci. 2017, 7(3), 263; doi:10.3390/app7030263
Received: 24 December 2016 / Revised: 28 February 2017 / Accepted: 6 March 2017 / Published: 9 March 2017
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Abstract
This paper presents experimental investigations of the in situ diagnosis of the alkali metals in the municipal solid waste (MSW) flame of an industrial grade incinerator using flame emission spectroscopy. The spectral radiation intensities of the MSW flame were obtained using a spectrometer.
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This paper presents experimental investigations of the in situ diagnosis of the alkali metals in the municipal solid waste (MSW) flame of an industrial grade incinerator using flame emission spectroscopy. The spectral radiation intensities of the MSW flame were obtained using a spectrometer. A linear polynomial fitting method is proposed to uncouple the continuous spectrum and the characteristic line. Based on spectra processing and a non-gray emissivity model, the flame temperature, emissivity, and intensities of the emission of alkali metals were calculated by means of measuring the spectral radiation intensities of the MSW flame. Experimental results indicate that the MSW flame contains alkali metals, including Na, K, and even Rb, and it demonstrates non-gray characteristics in a wavelength range from 500 nm to 900 nm. Peak intensities of the emission of the alkali metals were found to increase when the primary air was high, and the measured temperature varied in the same way as the primary air. The temperature and peak intensities of the lines of emission of the alkali metals may be used to adjust the primary airflow and to manage the feeding of the MSW to control the alkali metals in the MSW flame. It was found that the peak intensity of the K emission line had a linear relationship with the peak intensity of the Na emission line; this correlation may be attributed to their similar physicochemical characteristics in the MSW. The variation trend of the emissivity of the MSW flame and the oxygen content in the flue gas were almost opposite because the increased oxygen content suppressed soot formation and decreased soot emissivity. These results prove that the flame emission spectroscopy technique is feasible for monitoring combustion in the MSW incinerator in situ. Full article
(This article belongs to the Special Issue Optics and Spectroscopy for Fluid Characterization)
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Open AccessArticle Determination of Boron, Phosphorus, and Molybdenum Content in Biosludge Samples by Microwave Plasma Atomic Emission Spectrometry (MP-AES)
Appl. Sci. 2017, 7(3), 264; doi:10.3390/app7030264
Received: 7 December 2016 / Revised: 3 March 2017 / Accepted: 3 March 2017 / Published: 8 March 2017
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Abstract
A novel analytical method for accurate determination of boron (B), phosphorous (P), and molybdenum (Mo) content in biosludge samples based on a relatively recent analytical technique, microwave plasma atomic emission spectrometry (MP-AES), is developed in the present work. Microwave assisted acid digestion method
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A novel analytical method for accurate determination of boron (B), phosphorous (P), and molybdenum (Mo) content in biosludge samples based on a relatively recent analytical technique, microwave plasma atomic emission spectrometry (MP-AES), is developed in the present work. Microwave assisted acid digestion method is utilized to extract B, P, and Mo from biosludge. To demonstrate the reliability and accuracy of the present MP-AES method, its results are compared with those obtained using two well-established techniques, i.e., flame atomic absorption spectrometry (FAAS) and inductively coupled plasma optical emission spectrometry (ICP-OES). Matrix variation in the MP-AES technique is found to result in minimal changes. Precision and accuracy of the developed method are demonstrated using replicate analyses of certified sewage sludge reference material, EnviroMAT (BE-1). The limit of quantification and detection of B, P, and Mo in the extracts are determined; the linear regression coefficient was greater than 0.998 for all the three techniques. Analytical wavelengths are selected according to the sensitivity and interference effects. The results obtained in this work demonstrate the potential of MP-AES technique for the determination of B, P, and Mo content in biosludge, which achieved lower detection limits, higher accuracy, and better reproducibility as compared to other techniques. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle Robust and Agile System against Fault and Anomaly Traffic in Software Defined Networks
Appl. Sci. 2017, 7(3), 266; doi:10.3390/app7030266
Received: 10 December 2016 / Revised: 1 March 2017 / Accepted: 2 March 2017 / Published: 8 March 2017
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Abstract
The main advantage of software defined networking (SDN) is that it allows intelligent control and management of networking though programmability in real time. It enables efficient utilization of network resources through traffic engineering, and offers potential attack defense methods when abnormalities arise. However,
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The main advantage of software defined networking (SDN) is that it allows intelligent control and management of networking though programmability in real time. It enables efficient utilization of network resources through traffic engineering, and offers potential attack defense methods when abnormalities arise. However, previous studies have only identified individual solutions for respective problems, instead of finding a more global solution in real time that is capable of addressing multiple situations in network status. To cover diverse network conditions, this paper presents a comprehensive reactive system for simultaneously monitoring failures, anomalies, and attacks for high availability and reliability. We design three main modules in the SDN controller for a robust and agile defense (RAD) system against network anomalies: a traffic analyzer, a traffic engineer, and a rule manager. RAD provides reactive flow rule generation to control traffic while detecting network failures, anomalies, high traffic volume (elephant flows), and attacks. The traffic analyzer identifies elephant flows, traffic anomalies, and attacks based on attack signatures and network monitoring. The traffic engineer module measures network utilization and delay in order to determine the best path for multi-dimensional routing and load balancing under any circumstances. Finally, the rule manager generates and installs a flow rule for the selected best path to control traffic. We implement the proposed RAD system based on Floodlight, an open source project for the SDN controller. We evaluate our system using simulation with and without the aforementioned RAD modules. Experimental results show that our approach is both practical and feasible, and can successfully augment an existing SDN controller in terms of agility, robustness, and efficiency, even in the face of link failures, attacks, and elephant flows. Full article
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Open AccessArticle Numerical and Experimental Study on Enhancing Performance of the Stand Fan
Appl. Sci. 2017, 7(3), 267; doi:10.3390/app7030267
Received: 5 October 2016 / Revised: 26 February 2017 / Accepted: 2 March 2017 / Published: 8 March 2017
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Abstract
To meet humans’ need of enhancing the quality of life, the high-performance stand fan has become an essential appliance in every family. On the other hand, energy saving can not only solve the problem of environment protection, but also can reduce the cost
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To meet humans’ need of enhancing the quality of life, the high-performance stand fan has become an essential appliance in every family. On the other hand, energy saving can not only solve the problem of environment protection, but also can reduce the cost of energy consumption. However, the aerodynamic performance and flow characteristics of the stand fan are rarely investigated and analyzed in a systematical manner. Therefore, this research intends to investigate the physical mechanism of the flow pattern and identify the design parameters of the stand fan by combining numerical and experimental methods. First of all, both the structure and performance of a commercial 14-inch stand fan are chosen for analysis and are set as the reference for the fan. The stand fan can be divided into the impeller and the protective cover. Clearly, the impeller blades have a great influence on the fan performance, so they are the first design target. In this work, CFD (computational fluid dynamics) software Fluent (version 14.5, ANSYS Inc., Canonsburg, PA, USA, 2012) is used to analyze and observe the corresponding influences on flow fields and aerodynamic performance by changing the design parameters such as the setting, twist, and inclination angles. Then, the protective cover is studied, improved and integrated with the designed impeller to further enhance the performance of the fan. The protective cover is modified by varying the spacing between the blade tip and cover, as well as varying the shape and angle of ribs to improve the fan’s flow field and performance. Finally, the optimal fan mockup is made via CNC (computer numerical control) technology. Also, its acoustics and performance have been measured to validate the accuracy and reliability of the numerical simulation. The testing results show that the optimally designed stand fan is better than the reference fan with a significant 54% increase in max flow rate. In addition, it has more uniform velocity distribution compared with the reference fan to achieve a comfortable feeling for the human body. In summary, this research successfully establishes a reliable and systematic scheme to design the stand fan. Also, the corresponding performance influences caused by those important parameters are analyzed and summarized to serve as the design reference for the stand fan. Full article
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Open AccessArticle Hyperspectral Imaging as a Rapid Quality Control Method for Herbal Tea Blends
Appl. Sci. 2017, 7(3), 268; doi:10.3390/app7030268
Received: 11 January 2017 / Revised: 21 February 2017 / Accepted: 1 March 2017 / Published: 8 March 2017
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Abstract
In South Africa, indigenous herbal teas are enjoyed due to their distinct taste and aroma. The acclaimed health benefits of herbal teas include the management of chronic diseases such as hypertension and diabetes. Quality control of herbal teas has become important due to
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In South Africa, indigenous herbal teas are enjoyed due to their distinct taste and aroma. The acclaimed health benefits of herbal teas include the management of chronic diseases such as hypertension and diabetes. Quality control of herbal teas has become important due to the availability of different brands of varying quality and the production of tea blends. The potential of hyperspectral imaging as a rapid quality control method for herbal tea blends from rooibos (Aspalathus linearis), honeybush (Cyclopia intermedia), buchu (Agathosma Betulina) and cancerbush (Sutherlandia frutescens) was investigated. Hyperspectral images of raw materials and intact tea bags were acquired using a sisuChema shortwave infrared (SWIR) hyperspectral pushbroom imaging system (920–2514 nm). Principal component analysis (PCA) plots showed clear discrimination between raw materials. Partial least squares discriminant analysis (PLS-DA) models correctly predicted the raw material constituents of each blend and accurately determined the relative proportions. The results were corroborated independently using ultra-high performance liquid chromatography coupled to mass spectrometry (UHPLC-MS). This study demonstrated the application of hyperspectral imaging coupled with chemometric modelling as a reliable, rapid and non-destructive quality control method for authenticating herbal tea blends and to determine relative proportions in a tea bag. Full article
(This article belongs to the Special Issue Applications of Hyperspectral Imaging for Food and Agriculture)
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Open AccessArticle Researching a Fuzzy- and Performance-Based Optimization Method for the Life-Cycle Cost of SRHPC Frame Structures
Appl. Sci. 2017, 7(3), 269; doi:10.3390/app7030269
Received: 29 December 2016 / Revised: 29 January 2017 / Accepted: 7 February 2017 / Published: 8 March 2017
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Abstract
In order to solve two problems with the traditional optimization method of steel reinforced high strength high performance concrete (SRHPC) frame structures, a fuzzy mathematics and performance-based optimization method for the life-cycle cost of SRHPC frame structures is proposed. In the optimization program,
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In order to solve two problems with the traditional optimization method of steel reinforced high strength high performance concrete (SRHPC) frame structures, a fuzzy mathematics and performance-based optimization method for the life-cycle cost of SRHPC frame structures is proposed. In the optimization program, quantitative seismic performance indicators of SRHPC frame structures are determined according to the experimental results of SRHPC columns. Furthermore, by considering the fuzzy reliability of structures under each performance level, the life-cycle optimization model of SRHPC frame structures can be established. In order to solve the problem of too many variables and constraints in the optimization process, a two-step optimization method is proposed. Finally, an optimization example is carried out through the MATLAB program to demonstrate the feasibility of this model. Full article
(This article belongs to the Special Issue Structural Health Monitoring (SHM) of Civil Structures)
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Open AccessArticle Theory of Regions for Control Synthesis without Computing Reachability Graph
Appl. Sci. 2017, 7(3), 270; doi:10.3390/app7030270
Received: 11 January 2017 / Accepted: 3 March 2017 / Published: 9 March 2017
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Abstract
This paper addresses the design of Petri net (PN) supervisor using the theory of regions for forbidden state problem with a set of general mutual exclusion constraints. In fact, as any method of supervisory control based on reachability graph, the theory of regions
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This paper addresses the design of Petri net (PN) supervisor using the theory of regions for forbidden state problem with a set of general mutual exclusion constraints. In fact, as any method of supervisory control based on reachability graph, the theory of regions suffers from a technical obstacle in control synthesis, which is the necessity of computing the graph at each iteration step. Moreover, based on the reachability graph, which may contain a large number of states, with respect to the structural size of the system, the computation of PN controllers becomes harder and even impossible. The main contribution of this paper, compared to previous works, is the development of a control synthesis method in order to decrease significantly the computation cost of the PN supervisor. Thus, based on PN properties and mathematical concepts, the proposed methodology provides an optimal PN supervisor for bounded Petri nets following the interpretation of the theory of regions. Finally, case studies are solved by CPLEX software to compare our new control policy with previous works which use the theory of regions for control synthesis. Full article
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Open AccessArticle Magnetohydrodynamic Nanoliquid Thin Film Sprayed on a Stretching Cylinder with Heat Transfer
Appl. Sci. 2017, 7(3), 271; doi:10.3390/app7030271
Received: 31 January 2017 / Revised: 27 February 2017 / Accepted: 3 March 2017 / Published: 10 March 2017
Cited by 5 | PDF Full-text (762 KB) | HTML Full-text | XML Full-text
Abstract
The magnetohydrodynamic thin film nanofluid sprayed on a stretching cylinder with heat transfer is explored. The spray rate is a function of film size. Constant reference temperature is used for the motion past an expanding cylinder. The sundry behavior of the magnetic nano
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The magnetohydrodynamic thin film nanofluid sprayed on a stretching cylinder with heat transfer is explored. The spray rate is a function of film size. Constant reference temperature is used for the motion past an expanding cylinder. The sundry behavior of the magnetic nano liquid thin film is carefully noticed which results in to bring changes in the flow pattern and heat transfer. Water-based nanofluids like Al 2 O 3 -H 2 O and CuO-H 2 O are investigated under the consideration of thin film. The basic constitutive equations for the motion and transfer of heat of the nanofluid with the boundary conditions have been converted to nonlinear coupled differential equations with physical conditions by employing appropriate similarity transformations. The modeled equations have been computed by using HAM (Homotopy Analysis Method) and lead to detailed expressions for the velocity profile and temperature distribution. The pressure distribution and spray rate are also calculated. The comparison of HAM solution predicts the close agreement with the numerical method solution. The residual errors show the authentication of the present work. The CuO-H 2 O nanofluid results from this study are compared with the experimental results reported in the literature showing high accuracy especially, in investigating skin friction coefficient and Nusselt number. The present work discusses the salient features of all the indispensable parameters of spray rate, velocity profile, temperature and pressure distributions which have been displayed graphically and illustrated. Full article
(This article belongs to the Special Issue Recent Developments of Nanofluids)
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Open AccessArticle Self-Fitting Algorithm for Digital Hearing Aid Based on Interactive Evolutionary Computation and Expert System
Appl. Sci. 2017, 7(3), 272; doi:10.3390/app7030272
Received: 13 January 2017 / Accepted: 7 March 2017 / Published: 9 March 2017
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Abstract
The traditional hearing aid fitting method, which mainly relies on the audiologist, is timeconsuming and messy. To improve this situation, a self-fitting algorithm based on an improved interactive evolutionary computation (IEC) algorithm and expert system, which enables the patients to fit the hearing
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The traditional hearing aid fitting method, which mainly relies on the audiologist, is timeconsuming and messy. To improve this situation, a self-fitting algorithm based on an improved interactive evolutionary computation (IEC) algorithm and expert system, which enables the patients to fit the hearing aid by themselves, is proposed. The algorithm takes the band gain as the fitting target and uses the patient’s subjective evaluation to iteratively update the algorithm parameters based on the improved IEC algorithm. In addition, a real-time updated expert system is constructed to assist in the optimization of the initial and iterative parameters of the fitting based on the patient’s audiogram and personal information. To verify the performance of the algorithm, a self-fitting software for the hearing aid is designed. Through this software, the test signal is generated for the patient to evaluate the audio quality on a five-level scale. Based on the evaluation results, the algorithm iteratively optimizes the algorithm parameters until the patient is satisfied with the generated audio. Compared with the fitting algorithm based on Gaussian processes algorithm or the interactive evolutionary algorithm, the average subjective speech recognition rate of the proposed algorithm increase at least 11%. The average recognition rate for environmental sound is also improved by at least 2.9%. In addition, the fitting time of the proposed algorithm is shortened by at least 10 min compared to others two algorithms. Full article
(This article belongs to the Section Acoustics)
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Open AccessArticle Aqueous-Organic Phase Transfer of Gold and Silver Nanoparticles Using Thiol-Modified Oleic Acid
Appl. Sci. 2017, 7(3), 273; doi:10.3390/app7030273
Received: 10 February 2017 / Accepted: 6 March 2017 / Published: 9 March 2017
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Abstract
The handling of metallic nanoparticles often requires their dispersion into several polar and nonpolar solvents. Solid-phase stages or polymer-based ligands are commonly required to complete the transfer. The construction of a thiol ligand based in oleic acid, and its ability to efficiently assist
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The handling of metallic nanoparticles often requires their dispersion into several polar and nonpolar solvents. Solid-phase stages or polymer-based ligands are commonly required to complete the transfer. The construction of a thiol ligand based in oleic acid, and its ability to efficiently assist in gold and silver nanoparticle aqueous–organic phase transfer is reported. After the transfer, the particles are completely dispersed in an organic solvent, preserving their diameter and morphology, as confirmed by ultraviolet–visible spectroscopy and scanning transmission electron micrographs. Full article
(This article belongs to the Section Nanotechnology and Applied Nanosciences)
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Open AccessArticle Gear Wear Process Monitoring Using a Sideband Estimator Based on Modulation Signal Bispectrum
Appl. Sci. 2017, 7(3), 274; doi:10.3390/app7030274
Received: 6 February 2017 / Revised: 7 March 2017 / Accepted: 8 March 2017 / Published: 10 March 2017
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Abstract
As one of the most common gear failure modes, tooth wear can produce nonlinear modulation sidebands in the vibration frequency spectrum. However, limited research has been reported in monitoring the gear wear based on vibration due to the lack of tools which can
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As one of the most common gear failure modes, tooth wear can produce nonlinear modulation sidebands in the vibration frequency spectrum. However, limited research has been reported in monitoring the gear wear based on vibration due to the lack of tools which can effectively extract the small sidebands. In order to accurately monitor gear wear progression in a timely fashion, this paper presents a gear wear condition monitoring approach based on vibration signal analysis using the modulation signal bispectrum-based sideband estimator (MSB-SE) method. The vibration signals are collected using a run-to-failure test of gearbox under an accelerated test process. MSB analysis was performed on the vibration signals to extract the sideband information. Using a combination of the peak value of MSB-SE and the coherence of MSB-SE, the overall information of gear transmission system can be obtained. Based on the amplitude of MSB-SE peaks, a dimensionless indicator is proposed to assess the effects of gear tooth wear. The results demonstrated that the proposed indicator can be used to accurately and reliably monitor gear tooth wear and evaluate the wear severity. Full article
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Open AccessArticle A Comparative Study of Additively Manufactured Thin Wall and Block Structure with Al-6.3%Cu Alloy Using Cold Metal Transfer Process
Appl. Sci. 2017, 7(3), 275; doi:10.3390/app7030275
Received: 31 December 2016 / Accepted: 1 March 2017 / Published: 10 March 2017
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Abstract
In order to build a better understanding of the relationship between depositing mode and porosity, microstructure, and properties in wire + arc additive manufacturing (WAAM) 2319-Al components, several Al-6.3%Cu deposits were produced by WAAM technique with cold metal transfer (CMT) variants, pulsed CMT
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In order to build a better understanding of the relationship between depositing mode and porosity, microstructure, and properties in wire + arc additive manufacturing (WAAM) 2319-Al components, several Al-6.3%Cu deposits were produced by WAAM technique with cold metal transfer (CMT) variants, pulsed CMT (CMT-P) and advanced CMT (CMT-ADV). Thin walls and blocks were selected as the depositing paths to make WAAM samples. Porosity, microstructure and micro hardness of these WAAM samples were investigated. Compared with CMT-P and thin wall mode, CMT-ADV and block process can effectively reduce the pores in WAAM aluminum alloy. The microstructure varied with different depositing paths and CMT variants. The micro hardness value of thin wall samples was around 75 HV from the bottom to the middle, and gradually decreased toward the top. Meanwhile, the micro hardness value ranged around 72–77 HV, and varied periodically in block samples. The variation in micro hardness is consistent with standard microstructure characteristics. Full article
(This article belongs to the Special Issue Gas Metal Arc Welding)
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Open AccessArticle A Truly Second-Order and Unconditionally Stable Thermal Lattice Boltzmann Method
Appl. Sci. 2017, 7(3), 277; doi:10.3390/app7030277
Received: 7 February 2017 / Revised: 5 March 2017 / Accepted: 9 March 2017 / Published: 11 March 2017
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Abstract
An unconditionally stable thermal lattice Boltzmann method (USTLBM) is proposed in this paper for simulating incompressible thermal flows. In USTLBM, solutions to the macroscopic governing equations that are recovered from lattice Boltzmann equation (LBE) through Chapman–Enskog (C-E) expansion analysis are resolved in a
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An unconditionally stable thermal lattice Boltzmann method (USTLBM) is proposed in this paper for simulating incompressible thermal flows. In USTLBM, solutions to the macroscopic governing equations that are recovered from lattice Boltzmann equation (LBE) through Chapman–Enskog (C-E) expansion analysis are resolved in a predictor–corrector scheme and reconstructed within lattice Boltzmann framework. The development of USTLBM is inspired by the recently proposed simplified thermal lattice Boltzmann method (STLBM). Comparing with STLBM which can only achieve the first-order of accuracy in time, the present USTLBM ensures the second-order of accuracy both in space and in time. Meanwhile, all merits of STLBM are maintained by USTLBM. Specifically, USTLBM directly updates macroscopic variables rather than distribution functions, which greatly saves virtual memories and facilitates implementation of physical boundary conditions. Through von Neumann stability analysis, it can be theoretically proven that USTLBM is unconditionally stable. It is also shown in numerical tests that, comparing to STLBM, lower numerical error can be expected in USTLBM at the same mesh resolution. Four typical numerical examples are presented to demonstrate the robustness of USTLBM and its flexibility on non-uniform and body-fitted meshes. Full article
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Open AccessArticle The Reduction of Vertical Interchannel Crosstalk: The Analysis of Localisation Thresholds for Natural Sound Sources
Appl. Sci. 2017, 7(3), 278; doi:10.3390/app7030278
Received: 8 February 2017 / Revised: 1 March 2017 / Accepted: 10 March 2017 / Published: 14 March 2017
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Abstract
In subjective listening tests, natural sound sources were presented to subjects as vertically-oriented phantom images from two layers of loudspeakers, ‘height’ and ‘main’. Subjects were required to reduce the amplitude of the height layer until the position of the resultant sound source matched
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In subjective listening tests, natural sound sources were presented to subjects as vertically-oriented phantom images from two layers of loudspeakers, ‘height’ and ‘main’. Subjects were required to reduce the amplitude of the height layer until the position of the resultant sound source matched that of the same source presented from the main layer only (the localisation threshold). Delays of 0, 1 and 10 ms were applied to the height layer with respect to the main, with vertical stereophonic and quadraphonic conditions being tested. The results of the study showed that the localisation thresholds obtained were not significantly affected by sound source or presentation method. Instead, the only variable whose effect was significant was interchannel time difference (ICTD). For ICTD of 0 ms, the median threshold was −9.5 dB, which was significantly lower than the −7 dB found for both 1 and 10 ms. The results of the study have implications both for the recording of sound sources for three-dimensional (3D) audio reproduction formats and also for the rendering of 3D images. Full article
(This article belongs to the Special Issue Spatial Audio)
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Open AccessArticle A Finite Element Investigation into the Impact Performance of an Open-Face Motorcycle Helmet with Ventilation Slots
Appl. Sci. 2017, 7(3), 279; doi:10.3390/app7030279
Received: 11 January 2017 / Revised: 6 March 2017 / Accepted: 6 March 2017 / Published: 16 March 2017
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Abstract
Motorcycle helmets are essential for reducing the risk of head injuries in the event of an impact. However, during the design of helmets, a compromise must be made between user safety and user comfort. Accordingly, the present study proposes a novel open-face helmet
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Motorcycle helmets are essential for reducing the risk of head injuries in the event of an impact. However, during the design of helmets, a compromise must be made between user safety and user comfort. Accordingly, the present study proposes a novel open-face helmet design, in which the helmet features three ventilation slots in the upper-head region. Finite element analysis (FEA) models were constructed for both a prototype helmet design, and three traditional helmet designs (full-face, open-face, and half-face helmets). In simulating the proposed open-face helmet, this study considered three different ventilation slot widths, namely 8, 14, and 18 mm. The simulation results showed that of all the helmet designs, the half-face helmet resulted in the greatest headform acceleration (303 G). The internal ventilation helmet achieved a lower peak acceleration than that of the full-face helmet. By contrast, the proposed open-face helmet with ventilation slots resulted in the lowest acceleration, irrespective of the ventilation slot width. The 8-mm ventilation slot width resulted in the optimal impact performance level (i.e., a peak headform acceleration of 160 G). Overall, the results suggest that the proposed open-face helmet design with ventilation slots provides a promising solution for ensuring both user protection and user comfort in warm climates. Full article
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Open AccessArticle A New Engine Fault Diagnosis Method Based on Multi-Sensor Data Fusion
Appl. Sci. 2017, 7(3), 280; doi:10.3390/app7030280
Received: 29 January 2017 / Revised: 1 March 2017 / Accepted: 9 March 2017 / Published: 14 March 2017
Cited by 1 | PDF Full-text (658 KB) | HTML Full-text | XML Full-text
Abstract
Fault diagnosis is an important research direction in modern industry. In this paper, a new fault diagnosis method based on multi-sensor data fusion is proposed, in which the Dempster–Shafer (D–S) evidence theory is employed to model the uncertainty. Firstly, Gaussian types of fault
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Fault diagnosis is an important research direction in modern industry. In this paper, a new fault diagnosis method based on multi-sensor data fusion is proposed, in which the Dempster–Shafer (D–S) evidence theory is employed to model the uncertainty. Firstly, Gaussian types of fault models and test models are established by observations of sensors. After the models are determined, the intersection area between test model and fault models is transformed into a set of BPAs (basic probability assignments), and a weighted average combination method is used to combine the obtained BPAs. Finally, through some given decision making rules, diagnostic results can be obtained. The proposed method in this paper is tested by the Iris data set and actual measurement data of the motor rotor, which verifies the effectiveness of the proposed method. Full article
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Open AccessArticle Optimal Scheduling of Industrial Task-Continuous Load Management for Smart Power Utilization
Appl. Sci. 2017, 7(3), 281; doi:10.3390/app7030281
Received: 9 November 2016 / Revised: 27 February 2017 / Accepted: 9 March 2017 / Published: 14 March 2017
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Abstract
In the context of climate change and energy crisis around the world, an increasing amount of attention has been paid to developing clean energy and improving energy efficiency. The penetration of distributed generation (DG) is increasing rapidly on the user’s side of an
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In the context of climate change and energy crisis around the world, an increasing amount of attention has been paid to developing clean energy and improving energy efficiency. The penetration of distributed generation (DG) is increasing rapidly on the user’s side of an increasingly intelligent power system. This paper proposes an optimization method for industrial task-continuous load management in which distributed generation (including photovoltaic systems and wind generation) and energy storage devices are both considered. To begin with, a model of distributed generation and an energy storage device are built. Then, subject to various constraints, an operation optimization problem is formulated to maximize user profit, renewable energy efficiency, and the local consumption of distributed generation. Finally, the effectiveness of the method is verified by comparing user profit under different power modes. Full article
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Open AccessArticle Application of a High-Power Reversible Converter in a Hybrid Traction Power Supply System
Appl. Sci. 2017, 7(3), 282; doi:10.3390/app7030282
Received: 24 December 2016 / Revised: 25 February 2017 / Accepted: 7 March 2017 / Published: 14 March 2017
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Abstract
A high-power reversible converter can achieve a variety of functions, such as recovering regenerative braking energy, expanding traction power capacity, and improving an alternating current (AC) grid power factor. A new hybrid traction power supply scheme, which consists of a high-power reversible converter
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A high-power reversible converter can achieve a variety of functions, such as recovering regenerative braking energy, expanding traction power capacity, and improving an alternating current (AC) grid power factor. A new hybrid traction power supply scheme, which consists of a high-power reversible converter and two 12-pulse diode rectifiers, is proposed. A droop control method based on load current feed-forward is adopted to realize the load distribution between the reversible converter and the existing 12-pulse diode rectifiers. The direct current (DC) short-circuit characteristics of the reversible converter is studied, then the relationship between the peak fault current and the circuit parameters is obtained from theoretical calculations and validated by computer simulation. The first two sets of 2 MW reversible converters have been successfully applied in Beijing Metro Line 10, the proposed hybrid application scheme and coordinated control strategy are verified, and 11.15% of average energy-savings is reached. Full article
(This article belongs to the Special Issue Energy Saving)
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Open AccessArticle Development of a Preliminary Design Method for Subsonic Splittered Blades in Highly Loaded Axial-Flow Compressors
Appl. Sci. 2017, 7(3), 283; doi:10.3390/app7030283
Received: 31 January 2017 / Revised: 8 March 2017 / Accepted: 10 March 2017 / Published: 14 March 2017
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Abstract
This paper presents a model for predicting the reference minimum-loss incidence and deviation angles of a blade arrangement with splitter vanes, which is probably a solution for future ultra-highly loaded axial compressor designs. The motivation of the modeling is to guide the blading
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This paper presents a model for predicting the reference minimum-loss incidence and deviation angles of a blade arrangement with splitter vanes, which is probably a solution for future ultra-highly loaded axial compressor designs. The motivation of the modeling is to guide the blading design in splittered compressor design processes where the additional splitter vanes must be specially considered. The development of the model is based on a blade performance database from systematic numerical simulations. Basic correlations of the model are firstly proposed, which consider dominant blade geometry parameters related to blade loading, including camber angle and solidity. Secondly, geometric and aerodynamic corrections about orientation parameter, blade maximum thickness, inlet Mach number, and three-dimensional (3D) effects are empirically incorporated into the basic correlations. Eventually, a subsonic 3D splittered rotor is designed using the correlations coupled with the corrections obtained from the validation of the model. The results indicate that the model is able to achieve a good agreement within an error band of ±1.0° for the predictions of both reference minimum-loss incidence and deviation angles, and the rotor designed using the model accomplishes the desired work input and flow deflection. Full article
(This article belongs to the Special Issue Gas Turbines Propulsion and Power)
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Open AccessArticle Construction of Compact Finite Difference Schemes by Classic Differential Quadrature
Appl. Sci. 2017, 7(3), 284; doi:10.3390/app7030284
Received: 20 February 2017 / Revised: 10 March 2017 / Accepted: 10 March 2017 / Published: 14 March 2017
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Abstract
Using classic differential quadrature formulae and uniform grids, this paper systematically constructs a variety of high-order finite difference schemes, and some of these schemes are consistent with the so-called boundary value methods. The derived difference schemes enjoy the same stability and accuracy properties
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Using classic differential quadrature formulae and uniform grids, this paper systematically constructs a variety of high-order finite difference schemes, and some of these schemes are consistent with the so-called boundary value methods. The derived difference schemes enjoy the same stability and accuracy properties with correspondent differential quadrature methods but have a simpler form of calculation; thus, they can be seen as a compact format of classic differential quadrature methods. Through systematic Fourier stability analysis, the characteristics such as the dissipation, dispersion and resolution of the different schemes were studied and compared. Full article
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Open AccessArticle Physics of Prestall Propagating Disturbances in Axial Compressors and Their Potential as a Stall Warning Indicator
Appl. Sci. 2017, 7(3), 285; doi:10.3390/app7030285
Received: 31 January 2017 / Revised: 3 March 2017 / Accepted: 8 March 2017 / Published: 14 March 2017
PDF Full-text (4798 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Axial compressors in aero engines are prone to suffering a breakdown of orderly flow when operating at the peak of the pressure rise characteristic. The damaging potential of separated flows is why a safe distance has to be left between every possible operating
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Axial compressors in aero engines are prone to suffering a breakdown of orderly flow when operating at the peak of the pressure rise characteristic. The damaging potential of separated flows is why a safe distance has to be left between every possible operating point and an operating point at which stall occurs. During earlier investigations of stall inception mechanisms, a new type of prestall instability has been found. In this study, it could be demonstrated that the prestall instability characterised by discrete flow disturbances can be clearly assigned to the subject of “Rotating Instabilities”. Propagating disturbances are responsible for the rise in blade passing irregularity. If the mass flow is reduced successively, the level of irregularity increases until the prestall condition devolves into rotating stall. The primary objective of the current work is to highlight the basic physics behind these prestall disturbances by complementary experimental and numerical investigations. Before reaching the peak of the pressure rise characteristic flow, disturbances appear as small vortex tubes with one end attached to the casing and the other attached to the suction surface of the rotor blade. These vortex structures arise when the entire tip region is affected by blockage and at the same time the critical rotor incidence is not exceeded in this flow regime. Furthermore, a new stall indicator was developed by applying statistical methods to the unsteady pressure signal measured over the rotor blade tips, thus granting a better control of the safety margin. Full article
(This article belongs to the Special Issue Gas Turbines Propulsion and Power)
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Open AccessArticle Optical Coherence Tomography (OCT) for Time-Resolved Imaging of Alveolar Dynamics in Mechanically Ventilated Rats
Appl. Sci. 2017, 7(3), 287; doi:10.3390/app7030287
Received: 19 January 2017 / Revised: 8 March 2017 / Accepted: 10 March 2017 / Published: 15 March 2017
Cited by 1 | PDF Full-text (1998 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Though artificial ventilation is an essential life-saving treatment, the mechanical behavior of lung tissue at the alveolar level is still unknown. Therefore, we need to understand the tissue response during artificial ventilation at this microscale in order to develop new and more protective
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Though artificial ventilation is an essential life-saving treatment, the mechanical behavior of lung tissue at the alveolar level is still unknown. Therefore, we need to understand the tissue response during artificial ventilation at this microscale in order to develop new and more protective ventilation methods. Optical coherence tomography (OCT) combined with intravital microscopy (IVM) is a promising tool for visualizing lung tissue dynamics with a high spatial and temporal resolution in uninterruptedly ventilated rats. We present a measurement setup using a custom-made animal ventilator and a gating technique for data acquisition of time-resolved sequences. Full article
(This article belongs to the Special Issue Development and Application of Optical Coherence Tomography (OCT))
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Open AccessArticle An Explicit Approach Toward Modeling Thermo-Coupled Deformation Behaviors of SMPs
Appl. Sci. 2017, 7(3), 289; doi:10.3390/app7030289
Received: 25 December 2016 / Revised: 9 February 2017 / Accepted: 23 February 2017 / Published: 16 March 2017
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Abstract
A new elastoplastic J2-flow models with thermal effects is proposed toward simulating thermo-coupled finite deformation behaviors of shape memory polymers. In this new model, an elastic potential evolving with development of plastic flow is incorporated to characterize the stress-softening effect at
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A new elastoplastic J 2 -flow models with thermal effects is proposed toward simulating thermo-coupled finite deformation behaviors of shape memory polymers. In this new model, an elastic potential evolving with development of plastic flow is incorporated to characterize the stress-softening effect at unloading and, moreover, thermo-induced plastic flow is introduced to represent the strain recovery effect at heating. It is shown that any given test data for both effects may be accurately simulated by means of direct and explicit procedures. Numerical examples for model predictions compare well with test data in literature. Full article
(This article belongs to the Section Materials)
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Open AccessFeature PaperArticle Ultrasonic Techniques for Air Void Size Distribution and Property Evaluation in Both Early-Age and Hardened Concrete Samples
Appl. Sci. 2017, 7(3), 290; doi:10.3390/app7030290
Received: 19 January 2017 / Revised: 6 March 2017 / Accepted: 8 March 2017 / Published: 16 March 2017
PDF Full-text (3832 KB) | HTML Full-text | XML Full-text
Abstract
Entrained air voids can improve the freeze-thaw durability of concrete, and also affect its mechanical and transport properties. Therefore, it is important to measure the air void structure and understand its influence on concrete performance for quality control. This paper aims to measure
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Entrained air voids can improve the freeze-thaw durability of concrete, and also affect its mechanical and transport properties. Therefore, it is important to measure the air void structure and understand its influence on concrete performance for quality control. This paper aims to measure air void structure evolution at both early-age and hardened stages with the ultrasonic technique, and evaluates its influence on concrete properties. Three samples with different air entrainment agent content were specially prepared. The air void structure was determined with optimized inverse analysis by achieving the minimum error between experimental and theoretical attenuation. The early-age sample measurement showed that the air void content with the whole size range slightly decreases with curing time. The air void size distribution of hardened samples (at Day 28) was compared with American Society for Testing and Materials (ASTM) C457 test results. The air void size distribution with different amount of air entrainment agent was also favorably compared. In addition, the transport property, compressive strength, and dynamic modulus of concrete samples were also evaluated. The concrete transport decreased with the curing age, which is in accordance with the air void shrinkage. The correlation between the early-age strength development and hardened dynamic modulus with the ultrasonic parameters was also evaluated. The existence of clustered air voids in the Interfacial Transition Zone (ITZ) area was found to cause severe compressive strength loss. The results indicated that this developed ultrasonic technique has potential in air void size distribution measurement, and demonstrated the influence of air void structure evolution on concrete properties during both early-age and hardened stages. Full article
(This article belongs to the Special Issue Advanced Asphalt Materials and Paving Technologies)
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Open AccessArticle Surface Improvement of Halloysite Nanotubes
Appl. Sci. 2017, 7(3), 291; doi:10.3390/app7030291
Received: 30 December 2016 / Revised: 14 February 2017 / Accepted: 24 February 2017 / Published: 16 March 2017
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Abstract
A novel development on halloysite-polyvinyl alcohol (HNTs-PVA) nanocomposites has been conducted using malonic acid (MA) by crosslinking PVA and HNTs. PVA-MA crosslinking produces smooth surfaces, which play an important role in enhancing the properties of HNTs-PVA nanocomposite. The crystallographic structures of crosslinked HNTs-PVA
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A novel development on halloysite-polyvinyl alcohol (HNTs-PVA) nanocomposites has been conducted using malonic acid (MA) by crosslinking PVA and HNTs. PVA-MA crosslinking produces smooth surfaces, which play an important role in enhancing the properties of HNTs-PVA nanocomposite. The crystallographic structures of crosslinked HNTs-PVA show almost no change as depicted by the X-ray diffraction (XRD)-2θ-peak, suggesting that MA has no or little influence on the crystallographic structure of the HNTs-PVA. Images taken by field emission scanning electron microscope (FESEM) suggest possible effects of MA on the morphology and internal features of HNTs-PVA by reducing the agglomeration of HNTs, which is considered a decisive step in improving the surface qualities of HNTs. Investigating the samples using the Brunauer–Emmelt–Teller (BET) technique showed that the surface area was increased by about 10 times, reaching the second highest recorded results compared to the HNTs, which could be considered a breakthrough step in enhancing the properties of HNTs-PVA due to MA crosslinking. Full article
(This article belongs to the Special Issue Surface Modification of Halloysite Nanotubes)
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Open AccessArticle Birch Bark Dry Extract by Supercritical Fluid Technology: Extract Characterisation and Use for Stabilisation of Semisolid Systems
Appl. Sci. 2017, 7(3), 292; doi:10.3390/app7030292
Received: 31 December 2016 / Revised: 1 March 2017 / Accepted: 3 March 2017 / Published: 16 March 2017
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Abstract
Triterpene compounds like betulin, betulinic acid, erythrodiol, oleanolic acid and lupeol are known for many pharmacological effects. All these substances are found in the outer bark of birch. Apart from its pharmacological effects, birch bark extract can be used to stabilise semisolid systems.
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Triterpene compounds like betulin, betulinic acid, erythrodiol, oleanolic acid and lupeol are known for many pharmacological effects. All these substances are found in the outer bark of birch. Apart from its pharmacological effects, birch bark extract can be used to stabilise semisolid systems. Normally, birch bark extract is produced for this purpose by extraction with organic solvents. Employing supercritical fluid technology, our aim was to develop a birch bark dry extract suitable for stabilisation of lipophilic gels with improved properties while avoiding the use of toxic solvents. With supercritical carbon dioxide, three different particle formation methods from supercritical solutions have been tested. First, particle deposition was performed from a supercritical solution in an expansion chamber. Second, the Rapid Expansion of Supercritical Solutions (RESS) method was used for particle generation. Third, a modified RESS-procedure, forming the particles directly into the thereby gelated liquid, was developed. All three methods gave yields from 1% to 5.8%, depending on the techniques employed. The triterpene composition of the three extracts was comparable: all three gave more stable oleogels compared to the use of an extract obtained by organic solvent extraction. Characterizing the rheological behaviour of these gels, a faster gelling effect was seen together with a lower concentration of the extract required for the gel formation with the supercritical fluid (SCF)-extracts. This confirms the superiority of the supercritical fluid produced extracts with regard to the oleogel forming properties. Full article
(This article belongs to the Special Issue The Applications of Supercritical Carbon Dioxide)
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Open AccessArticle Two- and Three-Photon Partial Photoionization Cross Sections of Li+, Ne8+ and Ar16+ under XUV Radiation
Appl. Sci. 2017, 7(3), 294; doi:10.3390/app7030294
Received: 14 February 2017 / Revised: 7 March 2017 / Accepted: 9 March 2017 / Published: 17 March 2017
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Abstract
In this work, we present the photon energy dependence of the two- and three-photon cross sections of the two-electron Li+, Ne8+ and Ar16+ ions, following photoionization from their ground state. The expressions for the cross sections are based on
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In this work, we present the photon energy dependence of the two- and three-photon cross sections of the two-electron Li+, Ne8+ and Ar16+ ions, following photoionization from their ground state. The expressions for the cross sections are based on the lowest-order (non-vanishing) perturbation theory for the electric field, while the calculations are made with the use of an ab initio configuration interaction method. The ionization cross section is dominated by pronounced single photon resonances in addition to peaks associated with doubly excited resonances. In the case of two-photon ionization, and in the non-resonant part of the cross section, we find that the 1D ionization channel overwhelms the 1S one. We also observe that, as one moves from the lowest atomic number ion, namely Li+, to the highest atomic number ion, namely Ar16+, the cross sections generally decrease. Full article