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Appl. Sci., Volume 6, Issue 5 (May 2016)

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Open AccessArticle
Chord Recognition Based on Temporal Correlation Support Vector Machine
Appl. Sci. 2016, 6(5), 157; https://doi.org/10.3390/app6050157 - 19 May 2016
Cited by 3 | Viewed by 1981
Abstract
In this paper, we propose a method called temporal correlation support vector machine (TCSVM) for automatic major-minor chord recognition in audio music. We first use robust principal component analysis to separate the singing voice from the music to reduce the influence of the [...] Read more.
In this paper, we propose a method called temporal correlation support vector machine (TCSVM) for automatic major-minor chord recognition in audio music. We first use robust principal component analysis to separate the singing voice from the music to reduce the influence of the singing voice and consider the temporal correlations of the chord features. Using robust principal component analysis, we expect the low-rank component of the spectrogram matrix to contain the musical accompaniment and the sparse component to contain the vocal signals. Then, we extract a new logarithmic pitch class profile (LPCP) feature called enhanced LPCP from the low-rank part. To exploit the temporal correlation among the LPCP features of chords, we propose an improved support vector machine algorithm called TCSVM. We perform this study using the MIREX’09 (Music Information Retrieval Evaluation eXchange) Audio Chord Estimation dataset. Furthermore, we conduct comprehensive experiments using different pitch class profile feature vectors to examine the performance of TCSVM. The results of our method are comparable to the state-of-the-art methods that entered the MIREX in 2013 and 2014 for the MIREX’09 Audio Chord Estimation task dataset. Full article
(This article belongs to the Special Issue Audio Signal Processing) Printed Edition available
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Open AccessArticle
A Micro-Coordinate Measurement Machine (CMM) for Large-Scale Dimensional Measurement of Micro-Slits
Appl. Sci. 2016, 6(5), 156; https://doi.org/10.3390/app6050156 - 18 May 2016
Cited by 4 | Viewed by 2178
Abstract
This paper presents a micro-coordinate measuring machine (micro-CMM) for large-scale dimensional measurement of a micro-slit on a precision die coater by using a shear-mode micro-probe. A glass micro sphere with a nominal diameter of 52.3 μm was attached on one end of a [...] Read more.
This paper presents a micro-coordinate measuring machine (micro-CMM) for large-scale dimensional measurement of a micro-slit on a precision die coater by using a shear-mode micro-probe. A glass micro sphere with a nominal diameter of 52.3 μm was attached on one end of a tapered glass capillary tube as a probe tip ball. The micro-slit width of a slot die coater with a nominal slit width of 85 μm was measured by the micro-CMM. The probe tip was placed in the slit for the measurement. The effective working length of the probe was confirmed experimentally to be at least 1 mm. In order to measure the gap width uniformity over the entire slot die length of 200 mm, an air-bearing linear slide with a travelling stroke of 300 mm was employed in the micro-CMM to position the probe along the length direction of the slot die. The angular alignment error and the motion error of the air-bearing linear slide as well as those of the stages for positioning the probe along the direction perpendicular to the length direction of the slot die were investigated for evaluation of the expanded uncertainty of gap width measurement. Full article
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Open AccessArticle
Validation of a Mathematical Model for Green Algae (Raphidocelis Subcapitata) Growth and Implications for a Coupled Dynamical System with Daphnia Magna
Appl. Sci. 2016, 6(5), 155; https://doi.org/10.3390/app6050155 - 18 May 2016
Cited by 5 | Viewed by 1737
Abstract
Toxicity testing in populations probes for responses in demographic variables to anthropogenic or natural chemical changes in the environment. Importantly, these tests are primarily performed on species in isolation of adjacent tropic levels in their ecosystem. The development and validation of coupled species [...] Read more.
Toxicity testing in populations probes for responses in demographic variables to anthropogenic or natural chemical changes in the environment. Importantly, these tests are primarily performed on species in isolation of adjacent tropic levels in their ecosystem. The development and validation of coupled species models may aid in predicting adverse outcomes at the ecosystems level. Here, we aim to validate a model for the population dynamics of the green algae Raphidocelis subcapitata, a planktonic species that is often used as a primary food source in toxicity experiments for the fresh water crustacean Daphnia magna. We collected longitudinal data from three replicate population experiments of R. subcapitata. We used this data with statistical model comparison tests and uncertainty quantification techniques to compare the performance of four models: the Logistic model, the Bernoulli model, the Gompertz model, and a discretization of the Logistic model. Overall, our results suggest that the logistic model is the most accurate continuous model for R. subcapitata population growth. We then implement the numerical discretization showing how the continuous logistic model for algae can be coupled to a previously validated discrete-time population model for D. magna. Full article
(This article belongs to the Special Issue Dynamical Models of Biology and Medicine)
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Open AccessArticle
Development of a Method for Selection of Effective Singular Values in Bearing Fault Signal De-Noising
Appl. Sci. 2016, 6(5), 154; https://doi.org/10.3390/app6050154 - 18 May 2016
Cited by 7 | Viewed by 1352
Abstract
Singular value decomposition (SVD) is a widely used and powerful tool for signal extraction under noise. Noise attenuation relies on the selection of the effective singular value because these values are significant features of the useful signal. Traditional methods of selecting effective singular [...] Read more.
Singular value decomposition (SVD) is a widely used and powerful tool for signal extraction under noise. Noise attenuation relies on the selection of the effective singular value because these values are significant features of the useful signal. Traditional methods of selecting effective singular values (or selecting the useful components to rebuild the faulty signal) consist of seeking the maximum peak of the differential spectrum of singular values. However, owing to the small number of selected effective singular values, these methods lead to excessive de-noised effects. In order to get a more appropriate number of effective singular values, which preserves the components of the original signal as much as possible, this paper used a difference curvature spectrum of incremental singular entropy to determine the number of effective singular values. Then the position was found where the difference of two peaks in the spectrum declines in an infinitely large degree for the first time, and this position was regarded as the boundary of singular values between noise and a useful signal. The experimental results showed that the modified methods could accurately extract the non-stationary bearing faulty signal under real background noise. Full article
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Open AccessArticle
Simulation of Reservoir Sediment Flushing of the Three Gorges Reservoir Using an Artificial Neural Network
Appl. Sci. 2016, 6(5), 148; https://doi.org/10.3390/app6050148 - 18 May 2016
Cited by 10 | Viewed by 1437
Abstract
Reservoir sedimentation and its effect on the environment are the most serious world-wide problems in water resources development and utilization today. As one of the largest water conservancy projects, the Three Gorges Reservoir (TGR) has been controversial since its demonstration period, and sedimentation [...] Read more.
Reservoir sedimentation and its effect on the environment are the most serious world-wide problems in water resources development and utilization today. As one of the largest water conservancy projects, the Three Gorges Reservoir (TGR) has been controversial since its demonstration period, and sedimentation is the major concern. Due to the complex physical mechanisms of water and sediment transport, this study adopts the Error Back Propagation Training Artificial Neural Network (BP-ANN) to analyze the relationship between the sediment flushing efficiency of the TGR and its influencing factors. The factors are determined by the analysis on 1D unsteady flow and sediment mathematical model, mainly including reservoir inflow, incoming sediment concentration, reservoir water level, and reservoir release. Considering the distinguishing features of reservoir sediment delivery in different seasons, the monthly average data from 2003, when the TGR was put into operation, to 2011 are used to train, validate, and test the BP-ANN model. The results indicate that, although the sample space is quite limited, the whole sediment delivery process can be schematized by the established BP-ANN model, which can be used to help sediment flushing and thus decrease the reservoir sedimentation. Full article
(This article belongs to the Special Issue Applied Artificial Neural Network) Printed Edition available
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Open AccessArticle
Reduction of Liquid Bridge Force for 3D Microstructure Measurements
Appl. Sci. 2016, 6(5), 153; https://doi.org/10.3390/app6050153 - 16 May 2016
Cited by 4 | Viewed by 1829
Abstract
Recent years have witnessed an increased demand for a method for precise measurement of the microstructures of mechanical microparts, microelectromechanical systems, micromolds, optical devices, microholes, etc. This paper presents a measurement system for three-dimensional (3D) microstructures that use an optical fiber probe. This [...] Read more.
Recent years have witnessed an increased demand for a method for precise measurement of the microstructures of mechanical microparts, microelectromechanical systems, micromolds, optical devices, microholes, etc. This paper presents a measurement system for three-dimensional (3D) microstructures that use an optical fiber probe. This probe consists of a stylus shaft with a diameter of 2.5 µm and a glass ball with a diameter of 5 µm attached to the stylus tip. In this study, the measurement system, placed in a vacuum vessel, is constructed suitably to prevent adhesion of the stylus tip to the measured surface caused by the surface force resulting from the van der Waals force, electrostatic force, and liquid bridge force. First, these surface forces are analyzed with the aim of investigating the causes of adhesion. Subsequently, the effects of pressure inside the vacuum vessel on surface forces are evaluated. As a result, it is found that the surface force is 0.13 µN when the pressure inside the vacuum vessel is 350 Pa. This effect is equivalent to a 60% reduction in the surface force in the atmosphere. Full article
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Open AccessArticle
Superhydrophobic Surfaces Created by Elastic Instability of PDMS
Appl. Sci. 2016, 6(5), 152; https://doi.org/10.3390/app6050152 - 16 May 2016
Cited by 6 | Viewed by 2440
Abstract
Lotus flowers, rose petals, some plant leaves and insects have a naturally super-hydrophobic surface. In fact, the surface of a Lotus leaf is covered by micro and nano structures mixed with wax, which makes its surface superhydrophobic. In microfluidics, superhydrophobicity is an important [...] Read more.
Lotus flowers, rose petals, some plant leaves and insects have a naturally super-hydrophobic surface. In fact, the surface of a Lotus leaf is covered by micro and nano structures mixed with wax, which makes its surface superhydrophobic. In microfluidics, superhydrophobicity is an important factor in the rheometers on a chip. It is also sought in other complex fluids applications like the self-cleaning and the antibacterial materials. The wettability of the surface of solid support can be modified by altering its chemical composition. This means functionalizing the interface molecules to different chemical properties, and/or forming a thin film on the surface. We can also influence its texturing by changing its roughness. Despite considerable efforts during the last decade, superhydrophobic surfaces usually involve, among others, microfabrication processes, such as photolithography technique. In this study, we propose an original and simple method to create superhydrophobic surfaces by controlling elastic instability of poly-dimethylsiloxane (PDMS) films. Indeed, we demonstrate that the self-organization of wrinkles on top of non-wettable polymer surfaces leads to surperhydrophobic surfaces with contact angles exceeding 150°. We studied the transition Wenzel-Cassie, which indicated that the passage of morphology drops “impaled” to a type of morphology “fakir” were the strongest topographies. Full article
(This article belongs to the Special Issue Applications of Complex Fluids)
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Open AccessArticle
A Simple Predator-Prey Population Model with Rich Dynamics
Appl. Sci. 2016, 6(5), 151; https://doi.org/10.3390/app6050151 - 16 May 2016
Cited by 5 | Viewed by 2775
Abstract
A non-smooth switched harvest on predators is introduced into a simple predator-prey model with logistical growth of the prey and a bilinear functional response. If the density of the predator is below a switched value, the harvesting rate is linear; otherwise, it is [...] Read more.
A non-smooth switched harvest on predators is introduced into a simple predator-prey model with logistical growth of the prey and a bilinear functional response. If the density of the predator is below a switched value, the harvesting rate is linear; otherwise, it is constant. The model links the well studied predator-prey model with constant harvesting to that with a proportional harvesting rate. It is shown that when the net reproductive number for the predator is greater than unity, the system is permanent and there may exist multiple positive equilibria due to the effects of the switched harvest, a saddle-node bifurcation, a limit cycle, and the coexistence of a stable equilibrium and a unstable circled inside limit cycle and a stable circled outside limit cycle. When the net reproductive number is less than unity, a backward bifurcation from a positive equilibrium occurs, which implies that the stable predator-extinct equilibrium may coexist with two coexistence equilibria. In this situation, reducing the net reproductive number to less than unity is not enough to enable the predator to go extinct. Numerical simulations are provided to illustrate the theoretical results. It seems that the model possesses new complex dynamics compared to the existing harvesting models. Full article
(This article belongs to the Special Issue Dynamical Models of Biology and Medicine)
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Open AccessReview
State of the Art of Tactile Micro Coordinate Metrology
Appl. Sci. 2016, 6(5), 150; https://doi.org/10.3390/app6050150 - 16 May 2016
Cited by 11 | Viewed by 1964
Abstract
Micro parts are increasingly found in a number of industrial products. They often have complex geometrical features in the millimeter to micrometer range which are not accessible or difficult to measure by conventional coordinate measuring machines or by optical microscopy techniques. In the [...] Read more.
Micro parts are increasingly found in a number of industrial products. They often have complex geometrical features in the millimeter to micrometer range which are not accessible or difficult to measure by conventional coordinate measuring machines or by optical microscopy techniques. In the last years, several concepts of tactile micro coordinate measuring machines have been developed in research laboratories and were partly commercialized by industry. The major challenges were related to the development of innovative micro probes, to the requirements for traceability and to the performance assessment at reduced measurement uncertainty. This paper presents a review on state of the art developments of micro coordinate measuring machines and 3D micro probes in the last 20 years, as far as these were qualified in a comparable way, with a special emphasis on research conducted by the Federal Institute of Metrology METAS in this field. It outlines the accuracy limitations for the probe head including the probing element and for the geometrical errors of the machine axes. Finally, the achieved performances are summarized and the challenges for further research are addressed. Full article
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Open AccessArticle
Mathematical Modeling of Bacteria Communication in Continuous Cultures
Appl. Sci. 2016, 6(5), 149; https://doi.org/10.3390/app6050149 - 16 May 2016
Cited by 3 | Viewed by 1823
Abstract
Quorum sensing is a bacterial cell-to-cell communication mechanism and is based on gene regulatory networks, which control and regulate the production of signaling molecules in the environment. In the past years, mathematical modeling of quorum sensing has provided an understanding of key components [...] Read more.
Quorum sensing is a bacterial cell-to-cell communication mechanism and is based on gene regulatory networks, which control and regulate the production of signaling molecules in the environment. In the past years, mathematical modeling of quorum sensing has provided an understanding of key components of such networks, including several feedback loops involved. This paper presents a simple system of delay differential equations (DDEs) for quorum sensing of Pseudomonas putida with one positive feedback plus one (delayed) negative feedback mechanism. Results are shown concerning fundamental properties of solutions, such as existence, uniqueness, and non-negativity; the last feature is crucial for mathematical models in biology and is often violated when working with DDEs. The qualitative behavior of solutions is investigated, especially the stationary states and their stability. It is shown that for a certain choice of parameter values, the system presents stability switches with respect to the delay. On the other hand, when the delay is set to zero, a Hopf bifurcation might occur with respect to one of the negative feedback parameters. Model parameters are fitted to experimental data, indicating that the delay system is sufficient to explain and predict the biological observations. Full article
(This article belongs to the Special Issue Dynamical Models of Biology and Medicine)
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Open AccessArticle
Physical and Degradable Properties of Mulching Films Prepared from Natural Fibers and Biodegradable Polymers
Appl. Sci. 2016, 6(5), 147; https://doi.org/10.3390/app6050147 - 12 May 2016
Cited by 14 | Viewed by 2061
Abstract
The use of plastic film in agriculture has the serious drawback of producing vast quantities of waste. In this work, films were prepared from natural fibers and biodegradable polymers as potential substitutes for the conventional non-biodegradable plastic film used as mulching material in [...] Read more.
The use of plastic film in agriculture has the serious drawback of producing vast quantities of waste. In this work, films were prepared from natural fibers and biodegradable polymers as potential substitutes for the conventional non-biodegradable plastic film used as mulching material in agricultural production. The physical properties (e.g., mechanical properties, heat preservation, water permeability, and photopermeability) and degradation characteristics (evaluated by micro-organic culture testing and soil burial testing) of the films were studied in both laboratory and field tests. The experimental results indicated that these fiber/polymer films exhibited favorable physical properties that were sufficient for use in mulching film applications. Moreover, the degradation degree of the three tested films decreased in the following order: fiber/starch (ST) film > fiber/poly(vinyl alcohol) (PVA) film > fiber/polyacrylate (PA) film. The fiber/starch and fiber/PVA films were made from completely biodegradable materials and demonstrated the potential to substitute non-biodegradable films. Full article
(This article belongs to the Section Materials)
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Open AccessReview
A Review of Physical and Perceptual Feature Extraction Techniques for Speech, Music and Environmental Sounds
Appl. Sci. 2016, 6(5), 143; https://doi.org/10.3390/app6050143 - 12 May 2016
Cited by 28 | Viewed by 3509
Abstract
Endowing machines with sensing capabilities similar to those of humans is a prevalent quest in engineering and computer science. In the pursuit of making computers sense their surroundings, a huge effort has been conducted to allow machines and computers to acquire, process, analyze [...] Read more.
Endowing machines with sensing capabilities similar to those of humans is a prevalent quest in engineering and computer science. In the pursuit of making computers sense their surroundings, a huge effort has been conducted to allow machines and computers to acquire, process, analyze and understand their environment in a human-like way. Focusing on the sense of hearing, the ability of computers to sense their acoustic environment as humans do goes by the name of machine hearing. To achieve this ambitious aim, the representation of the audio signal is of paramount importance. In this paper, we present an up-to-date review of the most relevant audio feature extraction techniques developed to analyze the most usual audio signals: speech, music and environmental sounds. Besides revisiting classic approaches for completeness, we include the latest advances in the field based on new domains of analysis together with novel bio-inspired proposals. These approaches are described following a taxonomy that organizes them according to their physical or perceptual basis, being subsequently divided depending on the domain of computation (time, frequency, wavelet, image-based, cepstral, or other domains). The description of the approaches is accompanied with recent examples of their application to machine hearing related problems. Full article
(This article belongs to the Special Issue Audio Signal Processing) Printed Edition available
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Open AccessArticle
A Self-Paced P300 Healthcare Brain-Computer Interface System with SSVEP-Based Switching Control and Kernel FDA + SVM-Based Detector
Appl. Sci. 2016, 6(5), 142; https://doi.org/10.3390/app6050142 - 12 May 2016
Cited by 53 | Viewed by 2161
Abstract
This paper presents a novel brain-computer interface (BCI)-based healthcare control system, which is based on steady-state visually evoked potential (SSVEP) and P300 of electroencephalography (EEG) signals. The proposed system is composed of two modes, a brain switching mode and a healthcare function selection [...] Read more.
This paper presents a novel brain-computer interface (BCI)-based healthcare control system, which is based on steady-state visually evoked potential (SSVEP) and P300 of electroencephalography (EEG) signals. The proposed system is composed of two modes, a brain switching mode and a healthcare function selection mode. The switching mode can detect whether a user has the intent to activate the function selection mode by detecting SSVEP in an ongoing EEG. During the function selection mode, the user is able to select any functions that he/she wants to activate through a healthcare control panel, and the function selection is done by detecting P300 in the user’s EEG signals. The panel provides 25 functions representing 25 frequently performed activities of daily life. Therefore, users with severe motor disabilities can activate the system and any functions in a self-paced manner, achieving the goal of autonomous healthcare. To achieve high P300 detection accuracy, a novel P300 detector based on kernel Fisher’s discriminant analysis (kernel FDA) and support vector machine (SVM) is also proposed. Experimental results, carried out on five subjects, show that the proposed BCI system achieves high SSVEP detection (93%) and high P300 detection (95.5%) accuracies, meaning that the switching mode has a high sensitivity, and the function selection mode has the ability to accurately detect the functions that the users want to trigger. More important, only three electrodes (Oz, Cz, and Pz) are required to measure EEG signals, enabling the system to have good usability in practical use. Full article
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Open AccessArticle
Tests and Analysis of the Compressive Performance of an Integrated Masonry Structure of a Brick-Stem-Insulating Layer
Appl. Sci. 2016, 6(5), 146; https://doi.org/10.3390/app6050146 - 11 May 2016
Cited by 2 | Viewed by 1497
Abstract
This paper proposes, for low buildings, an integrated wall structure of a brick-stem-insulating layer, which plays a major part in both heat preservation and force bearing. The research team has tested the thermal performance of the structure, the results of which are satisfying. [...] Read more.
This paper proposes, for low buildings, an integrated wall structure of a brick-stem-insulating layer, which plays a major part in both heat preservation and force bearing. The research team has tested the thermal performance of the structure, the results of which are satisfying. To further study the force-bearing performance, the paper carries out compressive tests of specimens of different structural design, with two types of bricks, i.e., clay and recycled concrete bricks; three types of stems, i.e., square-shaped wood, square-shaped steel pipe and circular steel pipe; and one type of insulating layer, i.e., fly ash masonry blocks. Afterward, the force bearing performance, damage that occurred, compressive deformation and ductility of all of the specimens are compared. On the sideline, the structure is applied in the construction of a pilot residence project, yielding favorable outcomes. The results indicate that in comparison with a brick wall with an insulating layer sandwiched in between, the integrated wall structure of bricks and fly ash blocks is a more preferable choice in terms of compressive performance and ductility. The integrated wall structure of brick-stem-fly ash blocks delivers much better performance to this end. Note that regarding the stem’s contribution to compressive strength, circular steel pipe is highest, followed by square-shaped steel pipe and then square-shaped wood. The compressive performance of the sandwiched blocks surpasses that of the two brick wall pieces combined by a large margin. Full article
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Open AccessArticle
Failure Mode Analysis and Dynamic Response of a Coal Mine Refuge Chamber with a Gas Explosion
Appl. Sci. 2016, 6(5), 145; https://doi.org/10.3390/app6050145 - 11 May 2016
Cited by 3 | Viewed by 1636
Abstract
A gas and coal dust explosion is potential hazard in majority coal mines. A coal mine mobile refuge chamber is a new class of device for miners those who are unable to escape after an accident which can provide basic survival conditions. In [...] Read more.
A gas and coal dust explosion is potential hazard in majority coal mines. A coal mine mobile refuge chamber is a new class of device for miners those who are unable to escape after an accident which can provide basic survival conditions. In this paper, in order to study the propagation law of an underground methane/air mixture explosive wave, and check the failure mode of a coal mine mobile refuge chamber, a full-sized underground tunnel model and a refuge chamber model have been established in ANSYS/LS-DYNA (LSTC, R7.0.0, Livermore, CA, USA, 2014). The simulation results show that the reflected wave pressure on the front surface of the refuge chamber was about twice as high than the incident wave. The pressure on various locations of the chamber was also analyzed. When the peak pressure of the explosive shockwave reached 0.64 MPa, the maximum displacement and stress occur at the center of the front door and the joint of stiffeners and the front plate, respectively. Most parts of the coal mine mobile refuge chamber were in a plastic failure state and the refuge chamber could be defined as damaged. The front door, the front plate, the connecting flange, and the stiffeners on each side were the primary key components. In the end, suggestions were proposed for the refuge chamber. Full article
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Open AccessArticle
Simulation Model for Correction and Modeling of Probe Head Errors in Five-Axis Coordinate Systems
Appl. Sci. 2016, 6(5), 144; https://doi.org/10.3390/app6050144 - 11 May 2016
Cited by 8 | Viewed by 1562
Abstract
Simulative methods are nowadays frequently used in metrology for the simulation of measurement uncertainty and the prediction of errors that may occur during measurements. In coordinate metrology, such methods are primarily used with the typical three-axis Coordinate Measuring Machines (CMMs), and lately, also [...] Read more.
Simulative methods are nowadays frequently used in metrology for the simulation of measurement uncertainty and the prediction of errors that may occur during measurements. In coordinate metrology, such methods are primarily used with the typical three-axis Coordinate Measuring Machines (CMMs), and lately, also with mobile measuring systems. However, no similar simulative models have been developed for five-axis systems in spite of their growing popularity in recent years. This paper presents the numerical model of probe head errors for probe heads that are used in five-axis coordinate systems. The model is based on measurements of material standards (standard ring) and the use of the Monte Carlo method combined with select interpolation methods. The developed model may be used in conjunction with one of the known models of CMM kinematic errors to form a virtual model of a five-axis coordinate system. In addition, the developed methodology allows for the correction of identified probe head errors, thus improving measurement accuracy. Subsequent verification tests prove the correct functioning of the presented model. Full article
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Open AccessArticle
Coupling Motion and Energy Harvesting of Two Side-by-Side Flexible Plates in a 3D Uniform Flow
Appl. Sci. 2016, 6(5), 141; https://doi.org/10.3390/app6050141 - 10 May 2016
Cited by 5 | Viewed by 2016
Abstract
The fluid-structure interaction problems of two side-by-side flexible plates with a finite aspect ratio in a three-dimensional (3D) uniform flow are numerically studied. The plates’ motions are entirely passive under the force of surrounding fluid. By changing the aspect ratio and transverse distance, [...] Read more.
The fluid-structure interaction problems of two side-by-side flexible plates with a finite aspect ratio in a three-dimensional (3D) uniform flow are numerically studied. The plates’ motions are entirely passive under the force of surrounding fluid. By changing the aspect ratio and transverse distance, the coupling motions, drag force and energy capture performance are analyzed. The mechanisms underlying the plates’ motion and flow characteristics are discussed systematically. The adopted algorithm is verified and validated by the simulation of flow past a square flexible plate. The results show that the plate’s passive flapping behavior contains transverse and spanwise deformation, and the flapping amplitude is proportional to the aspect ratio. In the side-by-side configuration, three distinct coupling modes of the plates’ motion are identified, including single-plate mode, symmetrical flapping mode and decoupled mode. The plate with a lower aspect ratio may suffer less drag force and capture less bending energy than in the isolated situation. The optimized selection for obtaining higher energy conversion efficiency is the plate flapping in single-plate mode, especially the plate with a higher aspect ratio. The findings of this work provide several new physical insights into the understanding of fish schooling and are expected to inspire the developments of underwater robots or energy harvesters. Full article
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Open AccessArticle
Two-Polarisation Physical Model of Bowed Strings with Nonlinear Contact and Friction Forces, and Application to Gesture-Based Sound Synthesis
Appl. Sci. 2016, 6(5), 135; https://doi.org/10.3390/app6050135 - 10 May 2016
Cited by 6 | Viewed by 1859
Abstract
Recent bowed string sound synthesis has relied on physical modelling techniques; the achievable realism and flexibility of gestural control are appealing, and the heavier computational cost becomes less significant as technology improves. A bowed string sound synthesis algorithm is designed, by simulating two-polarisation [...] Read more.
Recent bowed string sound synthesis has relied on physical modelling techniques; the achievable realism and flexibility of gestural control are appealing, and the heavier computational cost becomes less significant as technology improves. A bowed string sound synthesis algorithm is designed, by simulating two-polarisation string motion, discretising the partial differential equations governing the string’s behaviour with the finite difference method. A globally energy balanced scheme is used, as a guarantee of numerical stability under highly nonlinear conditions. In one polarisation, a nonlinear contact model is used for the normal forces exerted by the dynamic bow hair, left hand fingers, and fingerboard. In the other polarisation, a force-velocity friction curve is used for the resulting tangential forces. The scheme update requires the solution of two nonlinear vector equations. The dynamic input parameters allow for simulating a wide range of gestures; some typical bow and left hand gestures are presented, along with synthetic sound and video demonstrations. Full article
(This article belongs to the Special Issue Audio Signal Processing) Printed Edition available
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Open AccessArticle
Dynamical Systems for Audio Synthesis: Embracing Nonlinearities and Delay-Free Loops
Appl. Sci. 2016, 6(5), 134; https://doi.org/10.3390/app6050134 - 10 May 2016
Cited by 3 | Viewed by 1646
Abstract
Many systems featuring nonlinearities and delay-free loops are of interest in digital audio, particularly in virtual analog and physical modeling applications. Many of these systems can be posed as systems of implicitly related ordinary differential equations. Provided each equation in the network is [...] Read more.
Many systems featuring nonlinearities and delay-free loops are of interest in digital audio, particularly in virtual analog and physical modeling applications. Many of these systems can be posed as systems of implicitly related ordinary differential equations. Provided each equation in the network is itself an explicit one, straightforward numerical solvers may be employed to compute the output of such systems without resorting to linearization or matrix inversions for every parameter change. This is a cheap and effective means for synthesizing delay-free, nonlinear systems without resorting to large lookup tables, iterative methods, or the insertion of fictitious delay and is therefor suitable for real-time applications. Several examples are shown to illustrate the efficacy of this approach. Full article
(This article belongs to the Special Issue Audio Signal Processing) Printed Edition available
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Open AccessArticle
A Novel Image Alignment Algorithm Based on Rotation-Discriminating Ring-Shifted Projection for Automatic Optical Inspection
Appl. Sci. 2016, 6(5), 140; https://doi.org/10.3390/app6050140 - 09 May 2016
Cited by 1 | Viewed by 1875
Abstract
This paper proposes a novel image alignment algorithm based on rotation-discriminating ring-shifted projection for automatic optical inspection. This new algorithm not only identifies the location of the template image within an inspection image but also provides precise rotation information during the template-matching process [...] Read more.
This paper proposes a novel image alignment algorithm based on rotation-discriminating ring-shifted projection for automatic optical inspection. This new algorithm not only identifies the location of the template image within an inspection image but also provides precise rotation information during the template-matching process by using a novel rotation estimation scheme, the so-called ring-shifted technique. We use a two stage framework with an image pyramid searching technique for realizing the proposed image alignment algorithm; in the first stage, the similarity based on hybrid projection transformation with the image pyramid searching technique is employed for quick selection and location of the candidates in the inspection image. In the second stage, the rotation angle of the object is estimated by a novel ring-shifted technique. The estimation is performed only for the most likely candidate which is the one having the highest similarity in the first stage. The experimental results show that the proposed method provides accurate estimation for template matching with arbitrary rotations and is applicable in various environmental conditions. Full article
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Open AccessArticle
Single Cell Chemotactic Responses of Helicobacter pylori to Urea in a Microfluidic Chip
Appl. Sci. 2016, 6(5), 139; https://doi.org/10.3390/app6050139 - 07 May 2016
Cited by 3 | Viewed by 1508
Abstract
Helicobacter pylori is a spiral-shaped bacterium that grows in the human digestive tract; it infects ~50% of the global population. H. pylori induce inflammation, gastroenteritis, and ulcers, which is associated with significant morbidity and may be linked to stomach cancer in certain individuals. [...] Read more.
Helicobacter pylori is a spiral-shaped bacterium that grows in the human digestive tract; it infects ~50% of the global population. H. pylori induce inflammation, gastroenteritis, and ulcers, which is associated with significant morbidity and may be linked to stomach cancer in certain individuals. Motility is an essential virulence factor for H. pylori, allowing it to migrate toward and invade the epithelial lining of the stomach to shelter it from the harsh environment of the stomach. H. pylori senses pH gradients and use polar flagella to move towards the epithelium where the pH approaches neutrality. However, its chemotaxis behaviors are incompletely understood. Previous in vitro tests examining the response of H. pylori to chemical gradients have been subjected to substantial limitations. To more accurately mimic/modulate the cellular microenvironment, a nanoporous microfluidic device was used to monitor the real time chemotactic activity of single cell of H. pylori in response to urea. The results showed that microfluidic method is a promising alternative for accurate studying of chemotactic behavior of H. pylori, the application of which may also be extended in the studies of other bacteria. Full article
(This article belongs to the Special Issue Nanomanufacturing of Biomedical Systems and Devices)
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Open AccessArticle
Effect of Islanding and Telecontrolled Switches on Distribution System Reliability Considering Load and Green-Energy Fluctuations
Appl. Sci. 2016, 6(5), 138; https://doi.org/10.3390/app6050138 - 07 May 2016
Cited by 7 | Viewed by 1765
Abstract
To improve electrical distribution network reliability, some portions of the network could operate in autonomous mode, provided that the related technical issues are addressed. More specifically, when there is not a path from those portions to the primary substation due to a fault [...] Read more.
To improve electrical distribution network reliability, some portions of the network could operate in autonomous mode, provided that the related technical issues are addressed. More specifically, when there is not a path from those portions to the primary substation due to a fault in the network, such portions could be disconnected from the main network and supplied by local generation only. Such a mode of operation is known as “intentional islanding” and its effectiveness, in terms of adequacy, depends on the ability of the local generation to meet the island’s load. In fact, the ratio between the available local generation and load demand can frequently change during islanding due to load variations and, especially, due to the strongly irregular behavior of the primary energy sources of renewable generators. This paper proposes an analytical formulation to assess local generation adequacy during intentional islanding, accounting for the aforementioned variations. More specifically, the fluctuations of load and green-energy generators during islanding are modeled by means of Markov chains, whose output quantities are encompassed in the proposed analytical formulation. Such a formulation is used by the analytical equations of load points’ outage rate and duration. The evaluation of the reliability indices accounts for a protection scheme based on an appropriate communication infrastructure. Therefore, a brief overview on the telecommunications technologies has been presented with reference to their suitability for the specific application. In particular, distribution network safety issues have been considered as the main concern. The results show that neglecting load and generation fluctuations leads to a strong overestimation of the ability of distributed generators to meet the island load. Through a case study it is observed that the error on the load point outage rate is greater than the one affecting the outage duration. Full article
(This article belongs to the Special Issue Smart Grid: Convergence and Interoperability)
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Open AccessArticle
Tracking a Driver’s Face against Extreme Head Poses and Inference of Drowsiness Using a Hidden Markov Model
Appl. Sci. 2016, 6(5), 137; https://doi.org/10.3390/app6050137 - 07 May 2016
Cited by 8 | Viewed by 2487
Abstract
This study presents a new method to track driver’s facial states, such as head pose and eye-blinking in the real-time basis. Since a driver in the natural driving condition moves his head in diverse ways and his face is often occluded by his [...] Read more.
This study presents a new method to track driver’s facial states, such as head pose and eye-blinking in the real-time basis. Since a driver in the natural driving condition moves his head in diverse ways and his face is often occluded by his hand or the wheel, it should be a great challenge for the standard face models. Among many, Active Appearance Model (AAM), and Active Shape Model (ASM) are two favored face models. We have extended Discriminative Bayesian ASM by incorporating the extreme pose cases, called it Pose Extended—Active Shape model (PE-ASM). Two face databases (DB) are used for the comparison purpose: one is the Boston University face DB and the other is our custom-made driving DB. Our evaluation indicates that PE-ASM outperforms ASM and AAM in terms of the face fitting against extreme poses. Using this model, we can estimate the driver’s head pose, as well as eye-blinking, by adding respective processes. Two HMMs are trained to model temporal behaviors of these two facial features, and consequently the system can make inference by enumerating these HMM states whether the driver is drowsy or not. Result suggests that it can be used as a driver drowsiness detector in the commercial car where the visual conditions are very diverse and often tough to deal with. Full article
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Open AccessArticle
A Simple Method for the Evaluation of the Pulse Width of an Ultraviolet Femtosecond Laser Used in Two-Photon Ionization Mass Spectrometry
Appl. Sci. 2016, 6(5), 136; https://doi.org/10.3390/app6050136 - 06 May 2016
Viewed by 1681
Abstract
A simple method was proposed for on-site evaluation of the pulse width of an ultraviolet femtosecond laser coupled with a mass spectrometer. This technique was based on measurement of a two-photon ionization signal in mass spectrometry by translation of the prism in the [...] Read more.
A simple method was proposed for on-site evaluation of the pulse width of an ultraviolet femtosecond laser coupled with a mass spectrometer. This technique was based on measurement of a two-photon ionization signal in mass spectrometry by translation of the prism in the pulse compressor of the femtosecond laser. The method was applied to optical pulses that were emitted at wavelengths of 267, 241, and 219 nm; the latter two pulses were generated by four-wave Raman mixing using the third harmonic emission of a Ti:sapphire laser (267 nm) in hydrogen gas. The measurement results show that this approach is useful for evaluation of the pulse width of the ultraviolet femtosecond laser used in mass spectrometry for trace analysis of organic compounds. Full article
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Open AccessReview
All About Audio Equalization: Solutions and Frontiers
Appl. Sci. 2016, 6(5), 129; https://doi.org/10.3390/app6050129 - 06 May 2016
Cited by 26 | Viewed by 4261
Abstract
Audio equalization is a vast and active research area. The extent of research means that one often cannot identify the preferred technique for a particular problem. This review paper bridges those gaps, systemically providing a deep understanding of the problems and approaches in [...] Read more.
Audio equalization is a vast and active research area. The extent of research means that one often cannot identify the preferred technique for a particular problem. This review paper bridges those gaps, systemically providing a deep understanding of the problems and approaches in audio equalization, their relative merits and applications. Digital signal processing techniques for modifying the spectral balance in audio signals and applications of these techniques are reviewed, ranging from classic equalizers to emerging designs based on new advances in signal processing and machine learning. Emphasis is placed on putting the range of approaches within a common mathematical and conceptual framework. The application areas discussed herein are diverse, and include well-defined, solvable problems of filter design subject to constraints, as well as newly emerging challenges that touch on problems in semantics, perception and human computer interaction. Case studies are given in order to illustrate key concepts and how they are applied in practice. We also recommend preferred signal processing approaches for important audio equalization problems. Finally, we discuss current challenges and the uncharted frontiers in this field. The source code for methods discussed in this paper is made available at https://code.soundsoftware.ac.uk/projects/allaboutaudioeq. Full article
(This article belongs to the Special Issue Audio Signal Processing) Printed Edition available
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Open AccessArticle
Influence of Immersion Conditions on The Tensile Strength of Recycled Kevlar®/Polyester/Low-Melting-Point Polyester Nonwoven Geotextiles through Applying Statistical Analyses
Appl. Sci. 2016, 6(5), 133; https://doi.org/10.3390/app6050133 - 05 May 2016
Cited by 3 | Viewed by 2026
Abstract
The recycled Kevlar®/polyester/low-melting-point polyester (recycled Kevlar®/PET/LPET) nonwoven geotextiles are immersed in neutral, strong acid, and strong alkali solutions, respectively, at different temperatures for four months. Their tensile strength is then tested according to various immersion periods at various temperatures, [...] Read more.
The recycled Kevlar®/polyester/low-melting-point polyester (recycled Kevlar®/PET/LPET) nonwoven geotextiles are immersed in neutral, strong acid, and strong alkali solutions, respectively, at different temperatures for four months. Their tensile strength is then tested according to various immersion periods at various temperatures, in order to determine their durability to chemicals. For the purpose of analyzing the possible factors that influence mechanical properties of geotextiles under diverse environmental conditions, the experimental results and statistical analyses are incorporated in this study. Therefore, influences of the content of recycled Kevlar® fibers, implementation of thermal treatment, and immersion periods on the tensile strength of recycled Kevlar®/PET/LPET nonwoven geotextiles are examined, after which their influential levels are statistically determined by performing multiple regression analyses. According to the results, the tensile strength of nonwoven geotextiles can be enhanced by adding recycled Kevlar® fibers and thermal treatment. Full article
(This article belongs to the Section Materials)
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Open AccessArticle
Innovative Methodology for Multi-View Point Cloud Registration in Robotic 3D Object Scanning and Reconstruction
Appl. Sci. 2016, 6(5), 132; https://doi.org/10.3390/app6050132 - 05 May 2016
Cited by 13 | Viewed by 2785
Abstract
The paper is concerned with the problem of multi-view three-dimensional (3D) point cloud registration. A novel global registration method is proposed to accurately register two series of scans into an object model underlying 3D imaging digitization by using the proposed oriented bounding box [...] Read more.
The paper is concerned with the problem of multi-view three-dimensional (3D) point cloud registration. A novel global registration method is proposed to accurately register two series of scans into an object model underlying 3D imaging digitization by using the proposed oriented bounding box (OBB) regional area-based descriptor. A robot 3D scanning strategy is nowadays employed to generate the complete set of point cloud of physical objects by using 3D robot multi-view scanning and data registration. The automated operation has to successively digitize view-dependent area-scanned point cloud from complex-shaped objects by simultaneous determination of the next best robot pose and multi-view point cloud registration. To achieve this, the OBB regional area-based descriptor is employed to determine an initial transformation matrix and is then refined employing the iterative closest point (ICP) algorithm. The key technical breakthrough can resolve the commonly encountered difficulty in accurately merging two neighboring area-scanned images when no coordinate reference exists. To verify the effectiveness of the strategy, the developed method has been verified through some experimental tests for its registration accuracy. Experimental results have preliminarily demonstrated the feasibility and applicability of the developed method. Full article
(This article belongs to the Special Issue Selected Papers from the 2015 International Conference on Inventions)
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Open AccessArticle
Thermal Analysis and Flame-Retarded Mechanism of Composites Composed of Ethylene Vinyl Acetate and Layered Double Hydroxides Containing Transition Metals (Mn, Co, Cu, Zn)
Appl. Sci. 2016, 6(5), 131; https://doi.org/10.3390/app6050131 - 04 May 2016
Cited by 7 | Viewed by 2183
Abstract
The effects of transition metals on the hydrophobicity of nano–structured layered double hydroxides (LDHs) and the compatibility of LDHs/ethylene vinyl acetate (EVA) composites have seldom been reported. NiMgAl–LDHs slightly surface–modified with stearate and doped with transition metal cations (Mn2+, Co2+ [...] Read more.
The effects of transition metals on the hydrophobicity of nano–structured layered double hydroxides (LDHs) and the compatibility of LDHs/ethylene vinyl acetate (EVA) composites have seldom been reported. NiMgAl–LDHs slightly surface–modified with stearate and doped with transition metal cations (Mn2+, Co2+, Cu2+, Zn2+) are investigated. Compared to the pure EVA, not only were the maximal degradation–rate temperatures (Tmax) of the ethylene–based chains enhanced, but also the smoke production rate (SPR) and the production rate of CO (COP) were sharply decreased for all the composites. Most importantly, a new flame retardant mechanism was found, namely the peak heat release rate (pk-HRR) time, which directly depends on the peak production rate of CO2 (pk-CO2) time for EVA and all composites by cone calorimeter test. Moreover, the Mn–doped LDH S–NiMgAl–Mn shows more uniform dispersion and better interfacial compatibility in the EVA matrix. The cone calorimetric residue of S–NiMgAl–Mn/EVA has the intumescent char layer and the compact metal oxide layer. Therefore, S–NiMgAl–Mn/EVA shows the lowest pk-HRR and the longest pk-HRR time among all the composites. Full article
(This article belongs to the Section Materials)
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Open AccessArticle
Development of Intelligent Fuzzy Controller for a Two-Axis Solar Tracking System
Appl. Sci. 2016, 6(5), 130; https://doi.org/10.3390/app6050130 - 03 May 2016
Cited by 8 | Viewed by 2590
Abstract
This paper proposes the development of a two-axis sun tracking solar energy system using fuzzy logic as intelligent quality policy. To achieve maximum efficiency for solar panels, it is necessary to follow the sun’s path in the sky. Therefore, the architecture for the [...] Read more.
This paper proposes the development of a two-axis sun tracking solar energy system using fuzzy logic as intelligent quality policy. To achieve maximum efficiency for solar panels, it is necessary to follow the sun’s path in the sky. Therefore, the architecture for the two-axis sun tracking solar energy system uses software to control the hardware. The hardware comprises (i) solar cells; (ii) lead-acid batteries; (iii) a gear box; (iv) a stepping motor; and (v) a light detection circuit, while the software comprises (i) a detection system; (ii) a fuzzy tracking controller; and (iii) a database system. A fuzzy logic controller is designed as the software architecture of the system to decide the timing for tracking the sun. The nearest position that results in receiving direct sunlight is obtained from the database. Our system is fully automatic in a changing environment and takes into account meteorological changes and the effects of the external environment arising from a malfunction. This approach reduces the number of starting motors and results in smaller energy loss in cloudy, cloud mask, or unstable weather conditions. Full article
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Open AccessArticle
Psychoacoustic Approaches for Harmonic Music Mixing
Appl. Sci. 2016, 6(5), 123; https://doi.org/10.3390/app6050123 - 03 May 2016
Cited by 5 | Viewed by 2399
Abstract
The practice of harmonic mixing is a technique used by DJs for the beat-synchronous and harmonic alignment of two or more pieces of music. In this paper, we present a new harmonic mixing method based on psychoacoustic principles. Unlike existing commercial DJ-mixing software, [...] Read more.
The practice of harmonic mixing is a technique used by DJs for the beat-synchronous and harmonic alignment of two or more pieces of music. In this paper, we present a new harmonic mixing method based on psychoacoustic principles. Unlike existing commercial DJ-mixing software, which determines compatible matches between songs via key estimation and harmonic relationships in the circle of fifths, our approach is built around the measurement of musical consonance. Given two tracks, we first extract a set of partials using a sinusoidal model and average this information over sixteenth note temporal frames. By scaling the partials of one track over ±6 semitones (in 1/8th semitone steps), we determine the pitch-shift that maximizes the consonance of the resulting mix. For this, we measure the consonance between all combinations of dyads within each frame according to psychoacoustic models of roughness and pitch commonality. To evaluate our method, we conducted a listening test where short musical excerpts were mixed together under different pitch shifts and rated according to consonance and pleasantness. Results demonstrate that sensory roughness computed from a small number of partials in each of the musical audio signals constitutes a reliable indicator to yield maximum perceptual consonance and pleasantness ratings by musically-trained listeners. Full article
(This article belongs to the Special Issue Audio Signal Processing) Printed Edition available
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