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Appl. Sci., Volume 7, Issue 7 (July 2017)

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Cover Story An overlay between Doppler Optical Coherence Tomography (Doppler OCT, color scale) and Optical [...] Read more.
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Editorial

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Open AccessEditorial Special Issue on Advances in Integrated Energy Systems Design, Control and Optimization
Appl. Sci. 2017, 7(7), 727; doi:10.3390/app7070727
Received: 7 July 2017 / Revised: 12 July 2017 / Accepted: 14 July 2017 / Published: 16 July 2017
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Abstract
In the face of climate change and resource scarcity, energy supply systems are on the verge of a major transformation, which mainly includes the introduction of new components and their integration into the existing infrastructures, new network configurations and reliable topologies, optimal design
[...] Read more.
In the face of climate change and resource scarcity, energy supply systems are on the verge of a major transformation, which mainly includes the introduction of new components and their integration into the existing infrastructures, new network configurations and reliable topologies, optimal design and novel operation schemes, and new incentives and business models. This revolution is affecting the current paradigm and demanding that energy systems be integrated into multi-carrier energy hubs [1]. [...] Full article

Research

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Open AccessArticle Modulational Instability in Linearly Coupled Asymmetric Dual-Core Fibers
Appl. Sci. 2017, 7(7), 645; doi:10.3390/app7070645
Received: 25 April 2017 / Revised: 12 June 2017 / Accepted: 13 June 2017 / Published: 22 June 2017
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Abstract
We investigate modulational instability (MI) in asymmetric dual-core nonlinear directional couplers incorporating the effects of the differences in effective mode areas and group velocity dispersions, as well as phase- and group-velocity mismatches. Using coupled-mode equations for this system, we identify MI conditions from
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We investigate modulational instability (MI) in asymmetric dual-core nonlinear directional couplers incorporating the effects of the differences in effective mode areas and group velocity dispersions, as well as phase- and group-velocity mismatches. Using coupled-mode equations for this system, we identify MI conditions from the linearization with respect to small perturbations. First, we compare the MI spectra of the asymmetric system and its symmetric counterpart in the case of the anomalous group-velocity dispersion (GVD). In particular, it is demonstrated that the increase of the inter-core linear-coupling coefficient leads to a reduction of the MI gain spectrum in the asymmetric coupler. The analysis is extended for the asymmetric system in the normal-GVD regime, where the coupling induces and controls the MI, as well as for the system with opposite GVD signs in the two cores. Following the analytical consideration of the MI, numerical simulations are carried out to explore nonlinear development of the MI, revealing the generation of periodic chains of localized peaks with growing amplitudes, which may transform into arrays of solitons. Full article
(This article belongs to the Special Issue Guided-Wave Optics)
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Open AccessArticle Algorithm for Reconstruction of 3D Images of Nanorice Particles from Diffraction Patterns of Two Particles in Independent Random Orientations with an X-ray Laser
Appl. Sci. 2017, 7(7), 646; doi:10.3390/app7070646
Received: 31 March 2017 / Revised: 8 June 2017 / Accepted: 8 June 2017 / Published: 23 June 2017
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Abstract
The method of angular correlations recovers quantities from diffraction patterns of randomly oriented particles, as expected to be measured with an X-ray free electron laser (XFEL), proportional to quadratic functions of the spherical harmonic expansion coefficients of the diffraction volume of a single
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The method of angular correlations recovers quantities from diffraction patterns of randomly oriented particles, as expected to be measured with an X-ray free electron laser (XFEL), proportional to quadratic functions of the spherical harmonic expansion coefficients of the diffraction volume of a single particle. We have previously shown that it is possible to reconstruct a randomly oriented icosahedral or helical virus from the average over all measured diffraction patterns of such correlations. We point out in this paper that a structure of even simpler particles of 50 Å or so in diameter and consisting of heavier atomic elements (to enhance scattering) that has been used as a test case for reconstructions from XFEL diffraction patterns can also be solved by this technique. Even though there has been earlier work on similar objects (prolate spheroids), one advantage of the present technique is its potential to also work with diffraction patterns not only due to single particles as has been suggested on the basis on nonoverlapping delta functions of angular scattering. Accordingly, we calculated from the diffraction patterns the angular momentum expansions of the pair correlations and triple correlations for general particle images and reconstructed those images in the standard way. Although the images looked pretty much the same, it is not totally clear to us that the angular correlations are exactly the same as different numbers of particles due to the possibility of constructive or destructive interference between the scattered waves from different particles. It is of course known that, for a large number of particles contributing to a diffraction parttern, the correlations converge to that of a single particle. It could be that the lack of perfect agreement between the images reconstructed with one and two particles is due to uncancelling constructive and destructive conditions that are not found in the case of solution scattering. Full article
(This article belongs to the Special Issue X-Ray Free-Electron Laser)
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Open AccessArticle An Evaluation of the Efficiency of Compartmented Alginate Fibres Encapsulating a Rejuvenator as an Asphalt Pavement Healing System
Appl. Sci. 2017, 7(7), 647; doi:10.3390/app7070647
Received: 19 April 2017 / Revised: 14 June 2017 / Accepted: 15 June 2017 / Published: 23 June 2017
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Abstract
This paper explores the potential methods for evaluating a healing system for asphalt pavements. The healing system under investigation involves compartmented calcium-alginate fibres encapsulating an asphalt binder healing agent (rejuvenator). This system presents a novel method of incorporating rejuvenators into asphalt pavement mixtures.
[...] Read more.
This paper explores the potential methods for evaluating a healing system for asphalt pavements. The healing system under investigation involves compartmented calcium-alginate fibres encapsulating an asphalt binder healing agent (rejuvenator). This system presents a novel method of incorporating rejuvenators into asphalt pavement mixtures. The compartmented fibres are used to distribute the rejuvenator throughout the pavement mixture, thereby overcoming some of the problems associated with alternate asphalt pavement healing methods, i.e., spherical capsules and hollow fibres. The asphalt healing efficiency methods to be evaluated in this paper include: (i) standard test methods for asphalt pavements, such as the Indirect Tensile Strength test and the 4 Point Bending Fatigue test; and (ii) alternative fracture tests such as the Semi Circular Bend test. The study employs fracture theory in order to evaluate the efficiency of the damage repair. The research findings demonstrate that including compartmented calcium-alginate fibres encapsulating a rejuvenator into an asphalt pavement mix does not significantly improve the healing properties of the asphalt pavement. Nevertheless, the findings indicate that, with further enhancement, compartmented calcium alginate fibres may present a promising new approach for the development of self-healing asphalt pavement systems. Additionally, the test results indicate that the 4 point bend fatigue test is the most suitable test for evaluating the performance of self healing asphalt pavements. Full article
(This article belongs to the Special Issue Self-Healing Asphalt)
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Open AccessArticle Non-Destructive Study of the Microstructural Effects of Sodium and Magnesium Sulphate Attack on Mortars Containing Silica Fume Using Impedance Spectroscopy
Appl. Sci. 2017, 7(7), 648; doi:10.3390/app7070648
Received: 17 May 2017 / Revised: 14 June 2017 / Accepted: 20 June 2017 / Published: 23 June 2017
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Abstract
The microstructural effects of exposure to a 15% magnesium sulphate, 15% sodium sulphate, and mixed solutions were observed in mortars with and without silica fume, using the non-destructive impedance spectroscopy technique. The non-destructive “Wenner” resistivity test and the classical mercury intrusion porosimetry were
[...] Read more.
The microstructural effects of exposure to a 15% magnesium sulphate, 15% sodium sulphate, and mixed solutions were observed in mortars with and without silica fume, using the non-destructive impedance spectroscopy technique. The non-destructive “Wenner” resistivity test and the classical mercury intrusion porosimetry were used as contrast techniques. The compressive strength of the mortars was also studied. In view of the results obtained, impedance spectroscopy was the most sensitive technique for detecting changes in the porous network of the studied mortars. The addition of silica fume results in a more refined microstructure and a higher compressive strength in mortars exposed to aggressive sulphate solutions. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Remaining Useful Life Prediction of Hybrid Ceramic Bearings Using an Integrated Deep Learning and Particle Filter Approach
Appl. Sci. 2017, 7(7), 649; doi:10.3390/app7070649
Received: 31 March 2017 / Revised: 7 June 2017 / Accepted: 20 June 2017 / Published: 23 June 2017
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Abstract
Bearings are one of the most critical components in many industrial machines. Predicting remaining useful life (RUL) of bearings has been an important task for condition-based maintenance of industrial machines. One critical challenge for performing such tasks in the era of the Internet
[...] Read more.
Bearings are one of the most critical components in many industrial machines. Predicting remaining useful life (RUL) of bearings has been an important task for condition-based maintenance of industrial machines. One critical challenge for performing such tasks in the era of the Internet of Things and Industrial 4.0, is to automatically process massive amounts of data and accurately predict the RUL of bearings. This paper addresses the limitations of traditional data-driven prognostics, and presents a new method that integrates a deep belief network and a particle filter for RUL prediction of hybrid ceramic bearings. Real data collected from hybrid ceramic bearing run-to-failure tests were used to test and validate the integrated method. The performance of the integrated method was also compared with deep belief network and particle filter-based approaches. The validation and comparison results showed that RUL prediction performance using the integrated method was promising. Full article
(This article belongs to the Special Issue Deep Learning Based Machine Fault Diagnosis and Prognosis)
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Open AccessArticle Effects of Fine Particles on Thermal Conductivity of Mixed Silica Sands
Appl. Sci. 2017, 7(7), 650; doi:10.3390/app7070650
Received: 17 April 2017 / Revised: 16 June 2017 / Accepted: 17 June 2017 / Published: 23 June 2017
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Abstract
The physical properties of granular materials (such as hydraulic, strength, and thermal properties) are largely dependent on their density (or porosity) and particle size distribution. In infrastructure design, the thermal properties of soils are now more important than in the past. However, our
[...] Read more.
The physical properties of granular materials (such as hydraulic, strength, and thermal properties) are largely dependent on their density (or porosity) and particle size distribution. In infrastructure design, the thermal properties of soils are now more important than in the past. However, our understanding of the thermal properties of mixed granular materials is still poor. In this study, the thermal conductivity of silica sands with different porosities and particle sizes was experimentally investigated, based on ASTM D5334-14. The thermal conductivity of granular materials is presented as a function of the porosity and proportion of fine particles. The thermal conductivity tends to be low when the porosity is high and the proportion of fine particles is low (and vice versa). When the fine particles are small enough to fill the pore body of the larger particles, the coordination number increases; thus, the thermal conductivity increases when the proportion of fine particles is high. Therefore, both the porosity and particle size distribution should be carefully considered when the thermal conductivity of mixed silica sand is evaluated. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Early Diagnosis of Dementia from Clinical Data by Machine Learning Techniques
Appl. Sci. 2017, 7(7), 651; doi:10.3390/app7070651
Received: 2 June 2017 / Revised: 20 June 2017 / Accepted: 20 June 2017 / Published: 23 June 2017
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Abstract
Dementia is the most prevalent degenerative disease in seniors in which progression can be prevented or delayed by early diagnosis. In this study, we proposed a two-layer model inspired by the method used in dementia support centers for the early diagnosis of dementia
[...] Read more.
Dementia is the most prevalent degenerative disease in seniors in which progression can be prevented or delayed by early diagnosis. In this study, we proposed a two-layer model inspired by the method used in dementia support centers for the early diagnosis of dementia and using machine learning techniques. Data were collected from patients who received dementia screening from 2008 to 2013 at the Gangbuk-Gu center for dementia in the Republic of Korea. The data consisted of the patient’s gender, age, education, the Mini-Mental State Examination in the Korean version of the CERAD Assessment Packet (MMSE-KC) for dementia screening test, and the Korean version of the Consortium to Establish a Registry for Alzheimer’s Disease (CERAD-K) for the dementia precise test. In the proposed model, MMSE-KC data are initially classified into normal and abnormal. In the second stage, CERAD-K data are used to classify dementia and mild cognitive impairment. The performance of each algorithm is compared with that of Naive Bayes, Bayes Network, Begging, Logistic Regression, Random Forest, Support Vector Machine (SVM) and Multilayer Perceptron (MLP) using Precision, Recall and F-measure. Comparing the F-measure values of normal, mild cognitive impairment (MCI), and dementia, the MLP was the highest in the F-measure values of normal with 0.97, while the SVM appear to be the highest in MCI and dementia with 0.739. Using the proposed early diagnosis model for dementia reduces the time and economic burden and can help simplify the diagnosis method for dementia. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Fractal Prediction of Grouting Volume for Treating Karst Caverns along a Shield Tunneling Alignment
Appl. Sci. 2017, 7(7), 652; doi:10.3390/app7070652
Received: 8 May 2017 / Revised: 1 June 2017 / Accepted: 8 June 2017 / Published: 25 June 2017
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Abstract
Karst geology is common in China, and buried karst formations are widely distributed in Guangdong province. In the process of shield tunneling, the abundant water resources present in karst caverns could lead to the potential for high water ingress, and a subsequent in
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Karst geology is common in China, and buried karst formations are widely distributed in Guangdong province. In the process of shield tunneling, the abundant water resources present in karst caverns could lead to the potential for high water ingress, and a subsequent in situ stress change-induced stratum collapse. The development and distribution of karst caverns should therefore be identified and investigated prior to shield tunnel construction. Grouting is an efficient measure to stabilize karst caverns. The total volume of karst caverns along the shield tunneling alignment, and its relationship with the required volume of grouts, should be evaluated in the preliminary design phase. Conventionally, the total volume of karst caverns is empirically estimated based on limited geological drilling hole data; however, accurate results are rarely obtained. This study investigates the hydrogeology and engineering geology of Guangzhou, the capital of Guangdong province, and determines the fractal characteristics of the karst caverns along the tunnel section of Guangzhou metro line no. 9. The karst grouting coefficients (VR) were found to vary from 0.11 in the case of inadequate drilling holes to 1.1 in the case where adequate drilling holes are provided. A grouting design guideline was furthermore developed in this study for future projects in karst areas. Full article
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Open AccessArticle State-Population Narrowing Effect in Two-Photon Absorption for Intense Hard X-ray Pulses
Appl. Sci. 2017, 7(7), 653; doi:10.3390/app7070653
Received: 29 April 2017 / Revised: 16 June 2017 / Accepted: 21 June 2017 / Published: 24 June 2017
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Abstract
We report on studies of state-populations during the two-photon absorption process using intense X-ray pulses. The calculations were performed in a time-dependent manner using a simple three-level model expressed by coupled rate equations. We show that the proposed approach describes well the measured
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We report on studies of state-populations during the two-photon absorption process using intense X-ray pulses. The calculations were performed in a time-dependent manner using a simple three-level model expressed by coupled rate equations. We show that the proposed approach describes well the measured rates of X-rays excited in the one-photon and two-photon absorption processes, and allows detailed investigation of the state population dynamics during the course of the incident X-ray pulse. Finally, we demonstrate that the nonlinear interaction of X-ray pulses with atoms leads to a time-narrowing of state populations. This narrowing-effect is attributed to a quadratic incidence X-ray intensity dependence characteristic for nonlinear interactions of photons with matter. Full article
(This article belongs to the Special Issue X-Ray Free-Electron Laser)
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Open AccessArticle Modified Godard Timing Recovery for Non Integer Oversampling Receivers
Appl. Sci. 2017, 7(7), 655; doi:10.3390/app7070655
Received: 19 May 2017 / Revised: 18 June 2017 / Accepted: 21 June 2017 / Published: 24 June 2017
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Abstract
A timing recovery algorithm is introduced that operates with less than two samples per symbol and provides an enormous complexity reduction. The complexity reduction is due to a synergy with the already existing Fourier transforms in a coherent receiver, an avoidance of terms
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A timing recovery algorithm is introduced that operates with less than two samples per symbol and provides an enormous complexity reduction. The complexity reduction is due to a synergy with the already existing Fourier transforms in a coherent receiver, an avoidance of terms that are dominated by noise, and a complete elimination of multiplications. A simulation and an experiment with a single carrier modulation format show that the inherent timing jitter is, despite of the significant complexity reduction, comparable with the state of the art, and in particular outperforms the Godard algorithm for low roll-off factors. In addition, it is one of the few algorithms that operates with less than two samples per symbol in the frequency domain, and thus enables the lowest complexity in a receiver. Full article
(This article belongs to the Special Issue Optical Signal Processing: Advances and Perspectives)
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Open AccessArticle Higher‐Order Interactions in Quantum Optomechanics: Revisiting Theoretical Foundations
Appl. Sci. 2017, 7(7), 656; doi:10.3390/app7070656
Received: 15 May 2017 / Revised: 13 June 2017 / Accepted: 23 June 2017 / Published: 24 June 2017
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Abstract
The theory of quantum optomechanics is reconstructed from first principles by finding a Lagrangian from light’s equation of motion and then proceeding to the Hamiltonian. The nonlinear terms, including the quadratic and higher‐order interactions, do not vanish under any possible choice of canonical
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The theory of quantum optomechanics is reconstructed from first principles by finding a Lagrangian from light’s equation of motion and then proceeding to the Hamiltonian. The nonlinear terms, including the quadratic and higher‐order interactions, do not vanish under any possible choice of canonical parameters, and lead to coupling of momentum and field. The existence of quadratic mechanical parametric interaction is then demonstrated rigorously, which has been so far assumed phenomenologically in previous studies. Corrections to the quadratic terms are particularly significant when the mechanical frequency is of the same order or larger than the electromagnetic frequency. Further discussions on the squeezing as well as relativistic corrections are presented. Full article
(This article belongs to the Section Optics and Lasers)
Open AccessArticle Laser and Electron Beam Additive Manufacturing Methods of Fabricating Titanium Bone Implants
Appl. Sci. 2017, 7(7), 657; doi:10.3390/app7070657
Received: 26 May 2017 / Revised: 19 June 2017 / Accepted: 21 June 2017 / Published: 26 June 2017
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Abstract
Additive Manufacturing (AM) methods are generally used to produce an early sample or near net-shape elements based on three-dimensional geometrical modules. To date, publications on AM of metal implants have mainly focused on knee and hip replacements or bone scaffolds for tissue engineering.
[...] Read more.
Additive Manufacturing (AM) methods are generally used to produce an early sample or near net-shape elements based on three-dimensional geometrical modules. To date, publications on AM of metal implants have mainly focused on knee and hip replacements or bone scaffolds for tissue engineering. The direct fabrication of metallic implants can be achieved by methods, such as Selective Laser Melting (SLM) or Electron Beam Melting (EBM). This work compares the SLM and EBM methods used in the fabrication of titanium bone implants by analyzing the microstructure, mechanical properties and cytotoxicity. The SLM process was conducted in an environmental chamber using 0.4–0.6 vol % of oxygen to enhance the mechanical properties of a Ti-6Al-4V alloy. SLM processed material had high anisotropy of mechanical properties and superior UTS (1246–1421 MPa) when compared to the EBM (972–976 MPa) and the wrought material (933–942 MPa). The microstructure and phase composition depended on the used fabrication method. The AM methods caused the formation of long epitaxial grains of the prior β phase. The equilibrium phases (α + β) and non-equilibrium α’ martensite was obtained after EBM and SLM, respectively. Although it was found that the heat transfer that occurs during the layer by layer generation of the component caused aluminum content deviations, neither methods generated any cytotoxic effects. Furthermore, in contrast to SLM, the EBM fabricated material met the ASTMF136 standard for surgical implant applications. Full article
(This article belongs to the Special Issue Laser Processing for Bioengineering Applications)
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Open AccessArticle Characteristics of GMAW Narrow Gap Welding on the Armor Steel of Combat Vehicles
Appl. Sci. 2017, 7(7), 658; doi:10.3390/app7070658
Received: 3 February 2017 / Revised: 15 June 2017 / Accepted: 17 June 2017 / Published: 27 June 2017
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Abstract
The primary purpose of this investigation was to study the characteristics of the armor steel weldment of combat vehicles by using GMAW narrow gap welding (NGW). The results showed that the mechanical properties and residual stress distribution of NGW weldment were improved, compared
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The primary purpose of this investigation was to study the characteristics of the armor steel weldment of combat vehicles by using GMAW narrow gap welding (NGW). The results showed that the mechanical properties and residual stress distribution of NGW weldment were improved, compared with conventional X-groove weldment. Additionally, ballistic tests according to MIL-HDBK-1941 were carried out to verify the ballistic ability of NGW weldment and the result showed that the NGW process was qualified for welding the armor steel of combat vehicle. Full article
(This article belongs to the Special Issue Gas Metal Arc Welding)
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Open AccessArticle Differentiating Authentic Adenophorae Radix from Its Adulterants in Commercially-Processed Samples Using Multiplexed ITS Sequence-Based SCAR Markers
Appl. Sci. 2017, 7(7), 660; doi:10.3390/app7070660
Received: 10 April 2017 / Revised: 19 June 2017 / Accepted: 20 June 2017 / Published: 27 June 2017
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Abstract
Determining the precise botanical origin of a traditional herbal medicine is important for basic quality control. In both the Chinese and Korean herbal pharmacopoeia, authentic Adenophorae Radix is defined as the roots of Adenophora stricta and Adenophora triphylla. However, the roots of
[...] Read more.
Determining the precise botanical origin of a traditional herbal medicine is important for basic quality control. In both the Chinese and Korean herbal pharmacopoeia, authentic Adenophorae Radix is defined as the roots of Adenophora stricta and Adenophora triphylla. However, the roots of Codonopsis lanceolata, Codonopsis pilosula, and Glehnia littoralis are frequently distributed as Adenophorae Radix in Korean herbal markets. Unfortunately, correctly identifying dried roots is difficult using conventional methods because the roots of those species are morphologically similar. Therefore, we developed DNA-based markers for the identification of authentic Adenophorae Radix and its common adulterants in commercially-processed samples. To develop a reliable method to discriminate between Adenophorae Radix and its adulterants, we sequenced the nuclear ribosomal DNA internal transcribed spacers (nrDNA-ITS) and designed sequence-characterized amplified region (SCAR) primers specific to the authentic and adulterant species. Using these primers, we developed SCAR markers for each species and established a multiplex-PCR method that can authenticate the four herbal medicines in a single PCR reaction. Furthermore, we confirmed that commercially-processed herbal medicines, which often have degraded DNA, could be assessed with our method. Therefore, our method is a reliable genetic tool to protect against adulteration and to standardize the quality of Adenophorae Radix. Full article
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Open AccessArticle Double-Sided Terahertz Imaging of Multilayered Glass Fiber-Reinforced Polymer
Appl. Sci. 2017, 7(7), 661; doi:10.3390/app7070661
Received: 8 June 2017 / Revised: 20 June 2017 / Accepted: 21 June 2017 / Published: 27 June 2017
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Abstract
Polymer matrix composites (PMC) play important roles in modern industry. Increasing the number of such structures in aerospace, construction, and automotive applications enforces continuous monitoring of their condition. Nondestructive inspection of layered composite materials is much more complicated process than evaluation of homogenous,
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Polymer matrix composites (PMC) play important roles in modern industry. Increasing the number of such structures in aerospace, construction, and automotive applications enforces continuous monitoring of their condition. Nondestructive inspection of layered composite materials is much more complicated process than evaluation of homogenous, (mostly metallic) structures. Several nondestructive methods are utilized in this case (ultrasonics, shearography, tap testing, acoustic emission, digital radiography, infrared imaging) but none of them gives full description of evaluated structures. Thus, further development of NDT techniques should be studied. A pulsed terahertz method seems to be a good candidate for layered PMC inspection. It is based on picosecond electromagnetic pulses interacting with the evaluated structure. Differences of dielectric parameters enables detection of a particular layer in a layered material. In the case of multilayered structures, only layers close to surface can be detected. The response of deeper ones is averaged because of multiple reflections. In this paper a novel inspection procedure with a data processing algorithm is introduced. It is based on a double-sided measurement, acquired signal deconvolution, and data combining. In order to verify the application of the algorithm stress-subjected glass fiber-reinforced polymer (GFRP) was evaluated. The obtained results enabled detection and detailed analysis of delaminations introduced by stress treatment and proved the applicability of the proposed algorithm. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Analysis of Land Cover Classification Using Multi-Wavelength LiDAR System
Appl. Sci. 2017, 7(7), 663; doi:10.3390/app7070663
Received: 26 April 2017 / Revised: 22 June 2017 / Accepted: 26 June 2017 / Published: 28 June 2017
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Abstract
The airborne multi-wavelength light detection and ranging (LiDAR) system measures different wavelengths simultaneously and usually includes two or more active channels in infrared and green to acquire both topographic and hydrographic information. The reflected multi-wavelength energy can also be used to identify different
[...] Read more.
The airborne multi-wavelength light detection and ranging (LiDAR) system measures different wavelengths simultaneously and usually includes two or more active channels in infrared and green to acquire both topographic and hydrographic information. The reflected multi-wavelength energy can also be used to identify different land covers based on physical properties of materials. This study explored the benefits of multi-wavelength LiDAR in object-based land cover classification, focusing on three major issues: (1) the evaluation of single- and multi-wavelength LiDARs for land cover classification; (2) the performance of spectral and geometrical features extracted from multi-wavelength LiDAR; and (3) the comparison of the vegetation index derived from active multi-wavelength LiDAR and passive multispectral images. The three-wavelength test data were acquired by Optech Titan in green, near-infrared, and mid-infrared channels, and the reference data were acquired from Worldview-3 image. The experimental results show that the multi-wavelength LiDAR provided higher accuracy than single-wavelength LiDAR in land cover classification, with an overall accuracy improvement rate about 4–14 percentage points. The spectral features performed better compared to geometrical features for grass, road, and bare soil classes, and the overall accuracy improvement is about 29 percentage points. The results also demonstrated the vegetation indices from Worldview-3 and Optech Titan have similar characteristics, with correlations reaching 0.68 to 0.89. Overall, the multi-wavelength LiDAR system improves the accuracy of land cover classification because this system provides more spectral information than traditional single-wavelength LiDAR. Full article
(This article belongs to the Special Issue Laser Scanning)
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Open AccessArticle Investigation of Depth and Injection Pressure Effects on Breakdown Pressure and Fracture Permeability of Shale Reservoirs: An Experimental Study
Appl. Sci. 2017, 7(7), 664; doi:10.3390/app7070664
Received: 23 April 2017 / Revised: 19 June 2017 / Accepted: 19 June 2017 / Published: 28 June 2017
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Abstract
The aim of this study was to identify the influence of reservoir depth on reservoir rock mass breakdown pressure and the influence of reservoir depth and injecting fluid pressure on the flow ability of reservoirs before and after the hydraulic fracturing process. A
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The aim of this study was to identify the influence of reservoir depth on reservoir rock mass breakdown pressure and the influence of reservoir depth and injecting fluid pressure on the flow ability of reservoirs before and after the hydraulic fracturing process. A series of fracturing tests was conducted under a range of confining pressures (1, 3, 5 and 7 MPa) to simulate various depths. In addition, permeability tests were conducted on intact and fractured samples under 1 and 7 MPa confining pressures to determine the flow characteristic variations upon fracturing of the reservoir, depending on the reservoir depth and injecting fluid pressure. N2 permeability was tested under a series of confining pressures (5, 10, 15, 20 and 25 MPa) and injection pressures (1–10 MPa). According to the results, shale reservoir flow ability for gas movement may reduce with increasing injection pressure and reservoir depth, due to the Klinkenberg phenomenon and pore structure shrinkage, respectively. The breakdown pressure of the reservoir rock linearly increases with increasing reservoir depth (confining pressure). Interestingly, 81% permeability reduction was observed in the fractured rock mass due to high (25 MPa) confinement, which shows the importance of proppants in the fracturing process. Full article
(This article belongs to the Section Energy)
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Open AccessFeature PaperArticle Auditory Distance Control Using a Variable-Directivity Loudspeaker
Appl. Sci. 2017, 7(7), 666; doi:10.3390/app7070666
Received: 19 April 2017 / Revised: 14 June 2017 / Accepted: 22 June 2017 / Published: 29 June 2017
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Abstract
The directivity of a sound source in a room influences the D/R ratio and thus the auditory distance. This study proposes various third-order beampattern pattern designs for a precise control of the D/R ratio. A comprehensive experimental study is conducted to investigate the
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The directivity of a sound source in a room influences the D/R ratio and thus the auditory distance. This study proposes various third-order beampattern pattern designs for a precise control of the D/R ratio. A comprehensive experimental study is conducted to investigate the hereby achieved effect on the auditory distance. Our first experiment auralizes the directivity variations using a virtual directional sound source in a virtual room using playback by a 24-channel loudspeaker ring. The experiment moreover shows the influence of room, source-listener distance, signal, and additional single-channel reverberation on the auditory distance. We verify the practical applicability of all the proposed beampattern pattern designs in a second experiment using a variable-directivity sound source in a real room. Predictions of experimental results are made with high accuracy, using room acoustical measures that typically predict the apparent source width. Full article
(This article belongs to the Special Issue Spatial Audio)
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Open AccessArticle Impact of Cryogenic Condition and Drill Diameter on Drilling Performance of CFRP
Appl. Sci. 2017, 7(7), 667; doi:10.3390/app7070667
Received: 4 April 2017 / Revised: 8 June 2017 / Accepted: 21 June 2017 / Published: 29 June 2017
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Abstract
Machining of carbon fiber-reinforced polymer (CFRP) is a rather hard task due to the inhomogeneity and anisotropy of this material. Several defects occur in the material when CFRP is machined and machining quality deteriorates owing to these material properties. In recent years, liquid
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Machining of carbon fiber-reinforced polymer (CFRP) is a rather hard task due to the inhomogeneity and anisotropy of this material. Several defects occur in the material when CFRP is machined and machining quality deteriorates owing to these material properties. In recent years, liquid nitrogen has been considered an environmentally safe, clean, and non-toxic coolant used to cut various materials in order to enhance machinability and prevent damage during machining. In this study, a new, eco-friendly cryogenic machining technique called dipped cryogenic machining was applied for the drilling of CFRP. This experimental study investigated the effect of feed rate and drill diameter on the thrust force, delamination factor, surface quality and drill wear. Machined surfaces were analyzed in detail using a scanning electron microscope and atomic force microscope. Results indicated that the drilling of CFRP with the dipped cryogenic machining approach greatly improved machinability by reducing the surface roughness of the drilled parts and tool wear. However, it increased the thrust force and delamination factor. Full article
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Open AccessArticle Adaptive Neuro-Fuzzy Inference System Model Based on the Width and Depth of the Defect in an Eddy Current Signal
Appl. Sci. 2017, 7(7), 668; doi:10.3390/app7070668
Received: 17 March 2017 / Revised: 24 June 2017 / Accepted: 25 June 2017 / Published: 29 June 2017
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Abstract
Non-destructive evaluation (NDE) plays an important role in many industrial fields, such as detecting cracking in steam generator tubing in nuclear power plants and aircraft. This paper investigates on the effect of the depth of the defect, width of the defect, and the
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Non-destructive evaluation (NDE) plays an important role in many industrial fields, such as detecting cracking in steam generator tubing in nuclear power plants and aircraft. This paper investigates on the effect of the depth of the defect, width of the defect, and the type of the material on the eddy current signal which is modeled by an adaptive neuro-fuzzy inference system (ANFIS). A total of 60 samples of artificial defects are located 20 mm parallel to the length of the block in each of the three types of material. A weld probe was used to inspect the block. The ANFIS model has three neurons in the input layer and one neuron in the output layer as the eddy current signal. The used design of experiments (DOE) software indicates that the model equations, which contain only linear and two-factor interaction terms, were developed to predict the percentage signal. This signal was validated through the use of the unseen data. The predicted results on the depth and width of defect significantly influenced the percentage of the signal (p < 0.0001) at the 95% confidence level. The ANFIS model proves that the deviation of the eddy current testing measurement was influenced by the width and depth of the defect less than the conductivity of the materials. Full article
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Open AccessArticle Sampietrini Stone Pavements: Distress Analysis Using Pavement Condition Index Method
Appl. Sci. 2017, 7(7), 669; doi:10.3390/app7070669
Received: 1 June 2017 / Revised: 20 June 2017 / Accepted: 27 June 2017 / Published: 29 June 2017
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Abstract
In several Italian cities, it is possible to find historical pavements such as the Sampietrini pavements, which are mainly located in the center of the city of Rome. The Sampietrini pavement is a particular road surface paved in natural stone with irregular sharp
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In several Italian cities, it is possible to find historical pavements such as the Sampietrini pavements, which are mainly located in the center of the city of Rome. The Sampietrini pavement is a particular road surface paved in natural stone with irregular sharp elements that are assembled by hand with the evident not plan effect. Because of their peculiarities, they are not suitable for streets where high speed is allowed. In many cases, high vibration and noise levels due to road traffic traveling on Sampietrini pavements are caused by inadequate maintenance, which is also affected by the absence of specific evaluation criteria regarding surface conditions and performances of Sampietrini pavements. It is not possible, in fact, to adopt common approaches developed to be used for flexible and rigid pavements, because they present completely different features and distresses. In this paper, to overpass this problem, a new evaluation criterion based on Pavement Condition Index (PCI) method established for block pavements is proposed. Furthermore, to fully characterize this kind of pavements, other analyses, i.e., International Roughness Index (IRI) and comfort level evaluation based on ISO 2631 standard, were also carried out. The results showed a good correlation between PCI and IRI approaches (R2 = 0.82), also highlighting that new or reconstructed Sampietrini pavements present not negligible roughness level. This aspect was also confirmed estimating the comfort level perceived by users traveling at several speeds (≤50 km/h). Finally, speed related threshold values to be adopted for PCI and IRI methods are proposed. The proposed method can be implemented by pavement managers in a PMS ad hoc for stone block paving and thus, it can be integrated with other equivalents methods of visual inspection based on PCI. Full article
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Open AccessArticle Ambient Light Rejection Using a Novel Average Voltage Tracking in Visible Light Communication System
Appl. Sci. 2017, 7(7), 670; doi:10.3390/app7070670
Received: 31 May 2017 / Revised: 23 June 2017 / Accepted: 26 June 2017 / Published: 29 June 2017
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Abstract
The quality of a received signal is one of the most important factors to be considered when designing a receiver for visible light communication (VLC) systems. Therefore, it is necessary to evaluate the robustness of the VLC receiver circuit in low-signal-to-noise ratio (SNR)
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The quality of a received signal is one of the most important factors to be considered when designing a receiver for visible light communication (VLC) systems. Therefore, it is necessary to evaluate the robustness of the VLC receiver circuit in low-signal-to-noise ratio (SNR) communication. The SNR is the quantity characterized by the ratio of the signal power to the noise power of the received signal. The noise generates an offset voltage and distorts the desired signal waveform. Thus, a low SNR makes it difficult to retrieve the data. Among the sources of noise, ambient light has the most negative impact on the VLC data signal. Therefore, the novel receiver proposed by us acts as an ambient light rejection circuit. As our average-voltage tracking circuit is insensitive to the sunlight and indoor fluorescent light, our design could be a solution to enhance the performance of low-SNR VLC systems. Several experiments are conducted using light of same intensity, but with different distances and semi-angles. Experimental results demonstrate that robust interference rejection is possible to send an error-free communication with an On-Off Keying modulation base on microcontroller up to 1 Mbps at an SNR of −2.7 dB. Full article
(This article belongs to the Special Issue Selected Papers from IEEE ICASI 2017)
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Open AccessArticle Numerical Calculation of the Performance of a Thermoacoustic System with Engine and Cooler Stacks in a Looped Tube
Appl. Sci. 2017, 7(7), 672; doi:10.3390/app7070672
Received: 3 February 2017 / Revised: 16 June 2017 / Accepted: 27 June 2017 / Published: 30 June 2017
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Abstract
The performance of a thermoacoustic system that is composed of a looped tube, an engine stack, a cooler stack, and four heat exchangers, is numerically investigated. Each stack has narrow flow channels, is sandwiched by two heat exchangers, and is located in the
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The performance of a thermoacoustic system that is composed of a looped tube, an engine stack, a cooler stack, and four heat exchangers, is numerically investigated. Each stack has narrow flow channels, is sandwiched by two heat exchangers, and is located in the looped tube. In order to provide a design guide, the performance of the system is numerically calculated by changing the following three parameters: the radius of the flow channels in the engine stack, the radius of the flow channels in the cooler stack, and the relative position of the cooler stack. It was found that when the three parameters are optimized, the efficiency of the engine stack reaches 75% of Carnot’s efficiency and the coefficient of the performance (COP) of the cooler stack is 53% of Carnot’s COP, whereas 33% of the acoustic power generated by the engine stack is utilized in the cooler stack. Full article
(This article belongs to the Special Issue Sciences in Heat Pump and Refrigeration)
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Open AccessArticle Numerical Predictions of Early Stage Turbulence in Oscillatory Flow across Parallel-Plate Heat Exchangers of a Thermoacoustic System
Appl. Sci. 2017, 7(7), 673; doi:10.3390/app7070673
Received: 19 April 2017 / Revised: 22 May 2017 / Accepted: 31 May 2017 / Published: 30 June 2017
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Abstract
This work focuses on the predictions of turbulent transition in oscillatory flow subjected to temperature gradients, which often occurs within heat exchangers of thermoacoustic devices. A two-dimensional computational fluid dynamics (CFD) model was developed in ANSYS FLUENT and validated using the earlier experimental
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This work focuses on the predictions of turbulent transition in oscillatory flow subjected to temperature gradients, which often occurs within heat exchangers of thermoacoustic devices. A two-dimensional computational fluid dynamics (CFD) model was developed in ANSYS FLUENT and validated using the earlier experimental data. Four drive ratios (defined as maximum pressure amplitude to mean pressure) were investigated: 0.30%, 0.45%, 0.65% and 0.83%. It has been found that the introduction of the turbulence model at a drive ratio as low as 0.45% improves the predictions of flow structure compared to experiments, which indicates that turbulent transition may occur at much smaller flow amplitudes than previously thought. In the current investigation, the critical Reynolds number based on the thickness of Stokes’ layer falls in the range between 70 and 100. The models tested included four variants of the RANS (Reynolds-Averaged Navier–Stokes) equations: k-ε, k-ω, shear-stress-transport (SST)-k-ω and transition-SST, the laminar model being used as a reference. Discussions are based on velocity profiles, vorticity plots, viscous dissipation and the resulting heat transfer and their comparison with experimental results. The SST-k-ω turbulence model and, in some cases, transition-SST provide the best fit of the velocity profile between numerical and experimental data (the value of the introduced metric measuring the deviation of the CFD velocity profiles from experiment is up to 43% lower than for the laminar model) and also give the best match in terms of calculated heat flux. The viscous dissipation also increases with an increase of the drive ratio. The results suggest that turbulence should be considered when designing thermoacoustic devices even in low-amplitude regimes in order to improve the performance predictions 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 Synergetic of PALSAR-2 and Sentinel-1A SAR Polarimetry for Retrieving Aboveground Biomass in Dipterocarp Forest of Malaysia
Appl. Sci. 2017, 7(7), 675; doi:10.3390/app7070675
Received: 15 April 2017 / Revised: 14 June 2017 / Accepted: 17 June 2017 / Published: 30 June 2017
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Abstract
Space borne synthetic aperture radar (SAR) data have become one of the primary sources for aboveground biomass (AGB) estimation of forests. However, studies have indicated that limitations occur when a single sensor system is employed, especially in tropical forests. Hence, there is potential
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Space borne synthetic aperture radar (SAR) data have become one of the primary sources for aboveground biomass (AGB) estimation of forests. However, studies have indicated that limitations occur when a single sensor system is employed, especially in tropical forests. Hence, there is potential for improving estimates if two or more different sensor systems are used. Studies on integrating multiple sensor systems for estimation of AGB over Malaysia’s tropical forests are scarce. This study investigated the use of PALSAR-2 L-band and Sentinel-1A C-band SAR polarizations to estimates the AGB over 5.25 million ha of the lowland, hill, and upper hill forests in Peninsular Malaysia. Polarized images, i.e., HH–HV from PALSAR-2 and VV–VH from Sentinel-1A have been utilized to produce several variables for predictions of the AGB. Simple linear and multiple linear regression analysis was performed to identify the best predictor. The study concluded that although limitations exist in the estimates, the combination of all polarizations from both PALSAR-2 and Sentiel-1A SAR data able to increase the accuracy and reduced the root means square error (RMSE) up to 14 Mg ha−1 compared to the estimation resulted from single polarization. A spatially distributed map of AGB reported the total AGB within the study area was about 1.82 trillion Mg of the year 2016. Full article
(This article belongs to the Special Issue Polarimetric SAR Techniques and Applications)
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Open AccessArticle Risk Analysis of a Two-Level Supply Chain Subject to Misplaced Inventory
Appl. Sci. 2017, 7(7), 676; doi:10.3390/app7070676
Received: 14 April 2017 / Revised: 21 June 2017 / Accepted: 28 June 2017 / Published: 30 June 2017
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Abstract
Misplaced inventory is prevalent in retail stores and may lead to the overall poor performance of the supply chain. We explore the impact of misplaced inventory on a two-level supply chain, which consists of a risk-neutral supplier and a risk-averse retailer. The supplier
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Misplaced inventory is prevalent in retail stores and may lead to the overall poor performance of the supply chain. We explore the impact of misplaced inventory on a two-level supply chain, which consists of a risk-neutral supplier and a risk-averse retailer. The supplier decides the wholesale price to maximize her profit, whereas the retailer decides the order quantity to maximize his utility. Under the Conditional Value-at-Risk (CVaR) criterion, we formulate the problem as a Stackelberg game model and obtain the equilibrium solutions in three cases: (i) information asymmetry about inventory errors exists; (ii) the retailer shares information about inventory errors with the supplier; and (iii) in order to reduce misplaced inventory, the supply chain deploys Radio-Frequency Identification (RFID) technology. The benefits of information sharing and RFID implementation are explored. A revenue and cost sharing contract is proposed to coordinate the supply chain and to allocate the cost savings from RFID implementation among supply chain participants. Finally, we provide managerial insights for risk-averse decision makers that are considering investing in the RFID technology. Full article
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Open AccessArticle The Vertical Dynamic Properties of Flexible Footbridges under Bipedal Crowd Induced Excitation
Appl. Sci. 2017, 7(7), 677; doi:10.3390/app7070677
Received: 27 March 2017 / Revised: 14 June 2017 / Accepted: 16 June 2017 / Published: 1 July 2017
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Abstract
The excessive vibration of footbridges caused by walking pedestrians has generated great public concern in recent years. However, it has not been explored how crowd size quantitatively influences structural dynamic properties, including human dynamic properties. This paper provides an alternative method for understanding
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The excessive vibration of footbridges caused by walking pedestrians has generated great public concern in recent years. However, it has not been explored how crowd size quantitatively influences structural dynamic properties, including human dynamic properties. This paper provides an alternative method for understanding how crowds excite the excessive sway motion of a large-span structure when walking on it. In this study, pedestrians are modeled by a walking dynamic bipedal system. The crowd-structure system is established based on the bipedal model, for which the dynamic properties from pedestrians are considered. The vertical dynamic property equations of structure are calculated under crowd-induced vibration, based on the assumption of a uniformly distributed crowd. Through the proposed framework, the changes of frequency and damping of structure induced by walking pedestrians are studied. The increase of the crowd size can reduce structural frequency, but increase its damping. The impact tendency of crowd size on structural dynamic properties is consistent with measured results. This research provides insight as to how crowd size quantitatively influences the change of structural dynamic properties. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Effects of Tooth Breakage Size and Rotational Speed on the Vibration Response of a Planetary Gearbox
Appl. Sci. 2017, 7(7), 678; doi:10.3390/app7070678
Received: 1 April 2017 / Revised: 19 May 2017 / Accepted: 13 June 2017 / Published: 1 July 2017
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Abstract
A nonlinear dynamic model for a planetary gearbox with tooth breakage fault is built based on an improved rigid multibody model, and the effects of tooth breakage size and rotational speed on the vibration response of the planetary gearbox are investigated numerically and
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A nonlinear dynamic model for a planetary gearbox with tooth breakage fault is built based on an improved rigid multibody model, and the effects of tooth breakage size and rotational speed on the vibration response of the planetary gearbox are investigated numerically and experimentally. A time-varying mesh stiffness model of planetary gears with tooth breakage fault is established. Dynamic simulations of a healthy planetary gear and seven fault gears with different breakage sizes under several rotational speeds are carried out. Experiments for healthy, half tooth breakage fault and whole tooth breakage fault planetary gears under several rotational speeds are performed. Amplitude analysis, spectrum analysis and envelope spectrum analysis are applied on the numerical and experimental vibration signals. The dynamic model is validated by experiment. The analysis results reveal the resonance and modulation characteristics in the vibration response, and the law of the vibration changes with breakage size and rotational speed. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Numerical Investigation of Heat-Insulating Layers in a Cold Region Tunnel, Taking into Account Airflow and Heat Transfer
Appl. Sci. 2017, 7(7), 679; doi:10.3390/app7070679
Received: 30 March 2017 / Revised: 29 May 2017 / Accepted: 15 June 2017 / Published: 1 July 2017
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Abstract
In cold regions, heat-insulating layers play a crucial role in frost prevention in tunnels. This paper presents a numerical study on the anti-freezing behavior of a cold region tunnel (the Dege tunnel) with heat-insulating layers. A numerical model based on the temperature field
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In cold regions, heat-insulating layers play a crucial role in frost prevention in tunnels. This paper presents a numerical study on the anti-freezing behavior of a cold region tunnel (the Dege tunnel) with heat-insulating layers. A numerical model based on the temperature field coupling theory is firstly proposed and validated using field test data of the Dege tunnel. Subsequently, a comprehensive parametric study is carried out to investigate the influences of heat-insulating layers on the temperature characteristics of airflows inside the tunnel, the surrounding rock, and the tunnel lining. Furthermore, a numerical investigation based on the proposed numerical model is carried out to propose reasonable design parameters of heat-insulating layers for different velocities of mechanical ventilation, and different heat-insulating materials for cold region tunnels. The numerical results show that using the heat-insulating layer can effectively reduce the heat transfer between the surrounding rock and the airflow inside the tunnel. It is also found that the design parameters for the heat-insulating layer are greatly affected by the tunnel ventilation conditions and heat-insulating materials. Full article
(This article belongs to the Special Issue Advances in Thermal System Analysis and Optimization)
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Open AccessArticle Robust Co-Optimization to Energy and Reserve Joint Dispatch Considering Wind Power Generation and Zonal Reserve Constraints in Real-Time Electricity Markets
Appl. Sci. 2017, 7(7), 680; doi:10.3390/app7070680
Received: 10 April 2017 / Revised: 13 May 2017 / Accepted: 7 June 2017 / Published: 1 July 2017
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Abstract
This paper proposes an energy and reserve joint dispatch model based on a robust optimization approach in real-time electricity markets, considering wind power generation uncertainties as well as zonal reserve constraints under both normal and N-1 contingency conditions. In the proposed model,
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This paper proposes an energy and reserve joint dispatch model based on a robust optimization approach in real-time electricity markets, considering wind power generation uncertainties as well as zonal reserve constraints under both normal and N-1 contingency conditions. In the proposed model, the operating reserves are classified as regulating reserve and spinning reserve according to the response performance. More specifically, the regulating reserve is usually utilized to reduce the gap due to forecasting errors, while the spinning reserve is commonly adopted to enhance the ability for N-1 contingencies. Since the transmission bottlenecks may inhibit the deliverability of reserve, the zonal placement of spinning reserve is considered in this paper to improve the reserve deliverability under the contingencies. Numerical results on the IEEE 118-bus test system show the effectiveness of the proposed model. Full article
(This article belongs to the Section Energy)
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Open AccessArticle Observing Femtosecond Fragmentation Using Ultrafast X-ray-Induced Auger Spectra
Appl. Sci. 2017, 7(7), 681; doi:10.3390/app7070681
Received: 11 June 2017 / Revised: 26 June 2017 / Accepted: 28 June 2017 / Published: 1 July 2017
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Abstract
Molecules often fragment after photoionization in the gas phase. Usually, this process can only be investigated spectroscopically as long as there exists electron correlation between the photofragments. Important parameters, like their kinetic energy after separation, cannot be investigated. We are reporting on a
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Molecules often fragment after photoionization in the gas phase. Usually, this process can only be investigated spectroscopically as long as there exists electron correlation between the photofragments. Important parameters, like their kinetic energy after separation, cannot be investigated. We are reporting on a femtosecond time-resolved Auger electron spectroscopy study concerning the photofragmentation dynamics of thymine. We observe the appearance of clearly distinguishable signatures from thymine′s neutral photofragment isocyanic acid. Furthermore, we observe a time-dependent shift of its spectrum, which we can attribute to the influence of the charged fragment on the Auger electron. This allows us to map our time-dependent dataset onto the fragmentation coordinate. The time dependence of the shift supports efficient transformation of the excess energy gained from photoionization into kinetic energy of the fragments. Our method is broadly applicable to the investigation of photofragmentation processes. Full article
(This article belongs to the Special Issue X-Ray Free-Electron Laser)
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Open AccessArticle Computer Color Matching and Levelness of PEG-Based Reverse Micellar Decamethyl cyclopentasiloxane (D5) Solvent-Assisted Reactive Dyeing on Cotton Fiber
Appl. Sci. 2017, 7(7), 682; doi:10.3390/app7070682
Received: 7 June 2017 / Revised: 26 June 2017 / Accepted: 28 June 2017 / Published: 2 July 2017
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Abstract
The color matching and levelness of cotton fabrics dyed with reactive dye, in a non-aqueous environmentally-friendly medium of decamethylcyclopentasiloxane (D5), was investigated using the non-ionic surfactant reverse-micellar approach comprised of poly(ethylene glycol)-based surfactant. The calibration dyeing databases for both conventional water-based dyeing and
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The color matching and levelness of cotton fabrics dyed with reactive dye, in a non-aqueous environmentally-friendly medium of decamethylcyclopentasiloxane (D5), was investigated using the non-ionic surfactant reverse-micellar approach comprised of poly(ethylene glycol)-based surfactant. The calibration dyeing databases for both conventional water-based dyeing and D5-assisted reverse micellar dyeing were established, along with the dyeing of standard samples with predetermined concentrations. Computer color matching (CCM) was conducted by using different color difference formulae for both dyeing methods. Experimental results reveal that the measured concentrations were nearly the same as the expected concentrations for both methods. This indicates that the D5-assisted non-ionic reverse micellar dyeing approach can achieve color matching as good as the conventional dyeing system. The levelness of the dyed samples was measured according to the relative unlevelness indices (RUI), and the results reveal that the samples dyed by the D5 reverse micellar dyeing system can achieve good to excellent levelness comparable to that of the conventional dyeing system. Full article
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Open AccessArticle Data Mining Approaches for Landslide Susceptibility Mapping in Umyeonsan, Seoul, South Korea
Appl. Sci. 2017, 7(7), 683; doi:10.3390/app7070683
Received: 8 June 2017 / Revised: 26 June 2017 / Accepted: 27 June 2017 / Published: 2 July 2017
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Abstract
The application of data mining models has become increasingly popular in recent years in assessments of a variety of natural hazards such as landslides and floods. Data mining techniques are useful for understanding the relationships between events and their influencing variables. Because landslides
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The application of data mining models has become increasingly popular in recent years in assessments of a variety of natural hazards such as landslides and floods. Data mining techniques are useful for understanding the relationships between events and their influencing variables. Because landslides are influenced by a combination of factors including geomorphological and meteorological factors, data mining techniques are helpful in elucidating the mechanisms by which these complex factors affect landslide events. In this study, spatial data mining approaches based on data on landslide locations in the geographic information system environment were investigated. The topographical factors of slope, aspect, curvature, topographic wetness index, stream power index, slope length factor, standardized height, valley depth, and downslope distance gradient were determined using topographical maps. Additional soil and forest variables using information obtained from national soil and forest maps were also investigated. A total of 17 variables affecting the frequency of landslide occurrence were selected to construct a spatial database, and support vector machine (SVM) and artificial neural network (ANN) models were applied to predict landslide susceptibility from the selected factors. In the SVM model, linear, polynomial, radial base function, and sigmoid kernels were applied in sequence; the model yielded 72.41%, 72.83%, 77.17% and 72.79% accuracy, respectively. The ANN model yielded a validity accuracy of 78.41%. The results of this study are useful in guiding effective strategies for the prevention and management of landslides in urban areas. Full article
(This article belongs to the Special Issue Application of Artificial Neural Networks in Geoinformatics)
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Open AccessArticle Robustness Analysis of the Collective Nonlinear Dynamics of a Periodic Coupled Pendulums Chain
Appl. Sci. 2017, 7(7), 684; doi:10.3390/app7070684
Received: 2 June 2017 / Revised: 23 June 2017 / Accepted: 28 June 2017 / Published: 3 July 2017
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Abstract
Perfect structural periodicity is disturbed in presence of imperfections. The present paper is based on a realistic modeling of imperfections, using uncertainties, to investigate the robustness of the collective nonlinear dynamics of a periodic coupled pendulums chain. A generic discrete analytical model combining
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Perfect structural periodicity is disturbed in presence of imperfections. The present paper is based on a realistic modeling of imperfections, using uncertainties, to investigate the robustness of the collective nonlinear dynamics of a periodic coupled pendulums chain. A generic discrete analytical model combining multiple scales method and standing-wave decomposition is proposed. To propagate uncertainties through the established model, the generalized Polynomial Chaos Expansion is used and compared to the Latin Hypercube Sampling method. Effects of uncertainties are investigated on the stability and nonlinearity of two and three coupled pendulums chains. Results prove the satisfying approximation given by the generalized Polynomial Chaos Expansion for a significantly reduced computational time, with respect to the Latin Hypercube Sampling method. Dispersion analysis of the frequency responses show that the nonlinear aspect of the structure is strengthened, the multistability domain is wider, more stable branches are obtained and thus multimode solutions are enhanced. More fine analysis is allowed by the quantification of the variability of the attractors’ contributions in the basins of attraction. Results demonstrate benefits of presence of imperfections in such periodic structure. In practice, imperfections can be functionalized to generate energy localization suitable for several engineering applications such as vibration energy harvesting. Full article
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Open AccessArticle A 3D Human Skeletonization Algorithm for a Single Monocular Camera Based on Spatial–Temporal Discrete Shadow Integration
Appl. Sci. 2017, 7(7), 685; doi:10.3390/app7070685
Received: 8 May 2017 / Revised: 27 June 2017 / Accepted: 29 June 2017 / Published: 3 July 2017
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Abstract
Three-dimensional (3D) human skeleton extraction is a powerful tool for activity acquirement and analyses, spawning a variety of applications on somatosensory control, virtual reality and many prospering fields. However, the 3D human skeletonization relies heavily on RGB-Depth (RGB-D) cameras, expensive wearable sensors and
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Three-dimensional (3D) human skeleton extraction is a powerful tool for activity acquirement and analyses, spawning a variety of applications on somatosensory control, virtual reality and many prospering fields. However, the 3D human skeletonization relies heavily on RGB-Depth (RGB-D) cameras, expensive wearable sensors and specific lightening conditions, resulting in great limitation of its outdoor applications. This paper presents a novel 3D human skeleton extraction method designed for the monocular camera large scale outdoor scenarios. The proposed algorithm aggregates spatial–temporal discrete joint positions extracted from human shadow on the ground. Firstly, the projected silhouette information is recovered from human shadow on the ground for each frame, followed by the extraction of two-dimensional (2D) joint projected positions. Then extracted 2D joint positions are categorized into different sets according to activity silhouette categories. Finally, spatial–temporal integration of same-category 2D joint positions is carried out to generate 3D human skeletons. The proposed method proves accurate and efficient in outdoor human skeletonization application based on several comparisons with the traditional RGB-D method. Finally, the application of the proposed method to RGB-D skeletonization enhancement is discussed. Full article
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Open AccessArticle Bonded-Particle Model with Nonlinear Elastic Tensile Stiffness for Rock-Like Materials
Appl. Sci. 2017, 7(7), 686; doi:10.3390/app7070686
Received: 24 April 2017 / Revised: 13 June 2017 / Accepted: 27 June 2017 / Published: 4 July 2017
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Abstract
The bonded-particle model (BPM) is a very efficient numerical method in dealing with initiation and propagation of cracks in rocks and can model the fracture processes and most of macro parameters of rocks well. However, typical discrete element method (DEM) underestimates the ratio
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The bonded-particle model (BPM) is a very efficient numerical method in dealing with initiation and propagation of cracks in rocks and can model the fracture processes and most of macro parameters of rocks well. However, typical discrete element method (DEM) underestimates the ratio of the uniaxial compressive strength to the tensile strength (UCS/TS). In this paper, a new DEM method with a nonlinear elastic tensile model embedded in BPM is proposed, which is named as nonlinear elastic tensile bonded particle model (NET-BPM). The relationships between micro parameters in NET-BPM and macro parameters of specimens are investigated by simulating uniaxial compression tests and direct tension tests. The results show that both the shape coefficient of the nonlinear elastic model and the bond width coefficient are important in predicting the value of UCS/TS, whose value ranging from 5 to 45 was obtained in our simulations. It is shown that the NET-BPM model is able to reproduce the nonlinear behavior of hard rocks such as Lac du Bonnet (LDB) granite and the quartzite under tension and the ratio of compressive Young’s modulus to tensile Young’s modulus higher than 1.0. Furthermore, the stress-strain curves in the simulations of LDB granite and the quartzite with NET-BPM model are in good agreement with the experimental results. NET-BPM is proved to be a very suitable method for modelling the deformation and fracture of rock-like materials. Full article
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Open AccessArticle Frequency Regulation of Power Systems with Self-Triggered Control under the Consideration of Communication Costs
Appl. Sci. 2017, 7(7), 688; doi:10.3390/app7070688
Received: 9 April 2017 / Revised: 29 June 2017 / Accepted: 30 June 2017 / Published: 4 July 2017
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Abstract
In control systems of power grids, conveying observations to controllers and obtaining control outputs depend greatly on communication and computation resources. Particularly for large-scale systems, the costs of computation and communication (cyber costs) should not be neglected. This paper proposes a self-triggered frequency
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In control systems of power grids, conveying observations to controllers and obtaining control outputs depend greatly on communication and computation resources. Particularly for large-scale systems, the costs of computation and communication (cyber costs) should not be neglected. This paper proposes a self-triggered frequency control system for a power grid to reduce communication costs. An equation for obtaining the triggering time is derived, and an approximation method is proposed to reduce the computation cost of triggering time. In addition, the communication cost of frequency triggering is measured quantitatively and proportionally. The defined cost function considers both physical cost (electricity transmission cost) and communication cost (control signal transmission cost). The upper bound of cost is estimated. According to the estimated upper bound of cost, parameters of the controller are investigated by using the proposed optimization algorithm to guarantee the high performance of the system. Finally, the proposed self-triggered power system is simulated to verify its efficiency and effectiveness. Full article
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Open AccessArticle Switched 4-to-1 Transimpedance Combining Amplifier for Receiver Front-End Circuit of Static Unitary Detector-Based LADAR System
Appl. Sci. 2017, 7(7), 689; doi:10.3390/app7070689
Received: 3 June 2017 / Revised: 23 June 2017 / Accepted: 30 June 2017 / Published: 4 July 2017
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Abstract
Laser detection and ranging (LADAR) systems are commonly used to acquire real-time three-dimensional (3D) images using the time-of-flight of a short laser pulse. A static unitary detector (STUD)-based LADAR system is a simple method for obtaining real-time high-resolution 3D images. In this study,
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Laser detection and ranging (LADAR) systems are commonly used to acquire real-time three-dimensional (3D) images using the time-of-flight of a short laser pulse. A static unitary detector (STUD)-based LADAR system is a simple method for obtaining real-time high-resolution 3D images. In this study, a switched 4-to-1 transimpedance combining amplifier (TCA) is implemented as a receiver front-end readout integrated circuit for the STUD-based LADAR system. The 4-to-1 TCA is fabricated using a standard 0.18 μm complementary metal-oxide-semiconductor (CMOS) technology, and it consists of four independent current buffers, a two-stage signal combiner, a balun, and an output buffer in one single integrated chip. In addition, there is a switch on each input current path to expand the region of interest with multiple photodetectors. The core of the TCA occupies an area of 92 μm × 68 μm, and the die size including I/O pads is 1000 μm × 840 μm. The power consumption of the fabricated chip is 17.8 mW for a supplied voltage of 1.8 V and a transimpedance gain of 67.5 dBΩ. The simulated bandwidth is 353 MHz in the presence of a 1 pF photodiode parasitic capacitance for each photosensitive cell. Full article
(This article belongs to the Section Optics and Lasers)
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Open AccessArticle Discrimination of Aortic and Pulmonary Components from the Second Heart Sound Using Respiratory Modulation and Measurement of Respiratory Split
Appl. Sci. 2017, 7(7), 690; doi:10.3390/app7070690
Received: 15 June 2017 / Revised: 3 July 2017 / Accepted: 3 July 2017 / Published: 4 July 2017
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Abstract
The second heart sound consists of aortic and pulmonary components. Analysis on the changes of the second heart sound waveform in respiration shows that the aortic component has little variation and the delay of the pulmonary component is modulated by respiration. This paper
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The second heart sound consists of aortic and pulmonary components. Analysis on the changes of the second heart sound waveform in respiration shows that the aortic component has little variation and the delay of the pulmonary component is modulated by respiration. This paper proposes a novel model to discriminate the aortic and pulmonary components using respiratory modulation. It is found that the aortic component could be simply extracted by averaging the second heart sounds over respiratory phase, and the pulmonary component could be extracted by subtraction. Hence, the split is measured by the timing difference of the two components. To validate the measurement, the method is applied to simulated second heart sounds with known varying splits. The simulation results show that the aortic and pulmonary components can be successfully extracted and the measured splits are close to the predefined splits. The method is further evaluated by data collected from 12 healthy subjects. Experimental results show that the respiratory split can be accurately measured. The minimum split generally occurs at the end of expiration and the split value is about 20 ms. Meanwhile, the maximum split is about 50 ms at the end of inspiration. Both the trend of split varying with respect to respiratory phase and the numerical range of split varying are comparable to the results disclosed by previous physiologists. The proposed method is compared to the two previous well known methods. The most attractive advantage of the proposed method is much less complexity. This method has potential applications in monitoring heart hemodynamic response to respiration. Full article
(This article belongs to the Special Issue Smart Healthcare)
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Open AccessArticle Emotion-Based Classification and Indexing for Wallpaper and Textile
Appl. Sci. 2017, 7(7), 691; doi:10.3390/app7070691
Received: 24 May 2017 / Revised: 22 June 2017 / Accepted: 28 June 2017 / Published: 5 July 2017
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Abstract
This study, based on human emotions and visual impression, develops a novel framework of classification and indexing for wallpaper and textiles. This method allows users to obtain a number of similar images that can be corresponded to a specific emotion by indexing through
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This study, based on human emotions and visual impression, develops a novel framework of classification and indexing for wallpaper and textiles. This method allows users to obtain a number of similar images that can be corresponded to a specific emotion by indexing through a reference image or an emotional keyword. In addition, a predefined color–emotion model is applied to deal with the transference between emotions and colors in the paper. Besides color and emotion, the other significant feature for indexing is texture. Therefore, two features—the main colors (the representative colors) and the foreground complexity of a color image—are adopted in the method. The foreground complexity (a pattern complexity) is also called the texture of the pattern in an image. Another contribution of this study is the new algorithms of Touch Four Sides (TFS) and Touch Up Sides (TUS), which can aid in extracting an accurate background and foreground for color images. The potential applications of this study can support non-professionals in finding suitable color-combinations based on emotions for many applications with the transference between emotions and colors, and to imitate the professional operation of the color matching such as interior design, product design, advertising design, image retrieval and other relative applications. Full article
(This article belongs to the Special Issue Selected Papers from IEEE ICASI 2017)
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Open AccessArticle Inoculation with Glomus mosseae Improves the Growth and Salvianolic Acid B Accumulation of Continuously Cropped Salvia miltiorrhiza
Appl. Sci. 2017, 7(7), 692; doi:10.3390/app7070692
Received: 23 April 2017 / Revised: 14 June 2017 / Accepted: 21 June 2017 / Published: 5 July 2017
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Abstract
Salvia miltiorrhiza (S. miltiorrhiza) Bunge is one of the most economically important medicinal crops in China. In traditional Chinese medicine, its root is used as an important ingredient in formulas for treatment of atherosclerosis-related disorders. The continuous cropping of S. miltiorrhiza
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Salvia miltiorrhiza (S. miltiorrhiza) Bunge is one of the most economically important medicinal crops in China. In traditional Chinese medicine, its root is used as an important ingredient in formulas for treatment of atherosclerosis-related disorders. The continuous cropping of S. miltiorrhiza increases the proportion of dried seedlings and decreases the biomass of the shoots and roots and the contents of active components. In this study, three field experiments were conducted to investigate the effects of Glomus mosseae (G. mosseae) inoculation on the growth and contents of active ingredients and nutrients in continuously cropped S. miltiorrhiza. The results showed that inoculation with G. mosseae increased the shoot biomass of S. miltiorrhiza by 48.1% and the root biomass by 39.2%, and decreased the dried seedling rate by nearly 75%. Inoculation with G. mosseae also increased the salvianolic acid B concentration by 21.9% in the shoots and 9.2% in the roots of S. miltiorrhiza, and also significantly increased Mn concentration in the roots and shoots (by 65.1% and 93.4%, respectively) and Fe concentration in the roots (by 75%). The accumulation of salvianolic acid B, Mn, and Fe in G. mosseae inoculated S. miltiorrhiza may be a mechanism that imparts tolerance to continuous cropping. Inoculation of S. miltiorrhiza with G. mosseae can serve as an effective approach of biocontrol to improve the performance of continuously cropped S. miltiorrhiza. Full article
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Open AccessArticle Economic Analysis for Collapse Hazard Areas
Appl. Sci. 2017, 7(7), 693; doi:10.3390/app7070693
Received: 23 May 2017 / Revised: 26 June 2017 / Accepted: 2 July 2017 / Published: 5 July 2017
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Abstract
In order to improve the quality assurance of collapse hazard zone projects, the economic effect of these projects in hazardous areas was analyzed. Ten areas were selected for the analysis to consider historical disaster records, and their effects were analyzed using a benefit/cost
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In order to improve the quality assurance of collapse hazard zone projects, the economic effect of these projects in hazardous areas was analyzed. Ten areas were selected for the analysis to consider historical disaster records, and their effects were analyzed using a benefit/cost (B/C) analysis. The benefit was estimated using the human and material losses in the damage hazard zones and the cost was assumed with the total project cost. Analysis results indicate the B/C ratio is larger than 1 in the difference range, depending on factors such as analysis period and discount rates. According to the analysis results, the average B/C of the ten projects is 3.5. The project implies that a disaster management project in hazardous areas will yield positive investment effects. The results of this study can be applied for improving the ways investment priorities for collapse hazard zones are determined. Full article
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Open AccessArticle Mechanical and Permeability Characteristics of Latex-Modified Fiber-Reinforced Roller-Compacted Rapid-Hardening-Cement Concrete for Pavement Repair
Appl. Sci. 2017, 7(7), 694; doi:10.3390/app7070694
Received: 9 May 2017 / Revised: 20 June 2017 / Accepted: 29 June 2017 / Published: 5 July 2017
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Abstract
This study evaluated the effects of reinforcement fibers on the mechanical characteristics, chloride ion penetration properties and abrasion resistance of roller-compacted latex-modified fiber-reinforced rapid-hardening-cement concrete (RCLMFRRHCC) for use in the emergency repair of concrete pavements. The reinforcement fibers tested included macro synthetic fibers
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This study evaluated the effects of reinforcement fibers on the mechanical characteristics, chloride ion penetration properties and abrasion resistance of roller-compacted latex-modified fiber-reinforced rapid-hardening-cement concrete (RCLMFRRHCC) for use in the emergency repair of concrete pavements. The reinforcement fibers tested included macro synthetic fibers (a structural fiber) as well as PVA (polyvinyl alcohol) and natural Jute fibers (non-structural fibers). In the experiment, compressive strength, flexural strength, splitting tensile strength, chloride ion penetrating properties, abrasion resistance tests and impact resistance tests were performed. Test results were compared with traffic open standards of concrete for concrete pavement emergency repair. RCLMFRRHCC satisfied all traffic open standards for concrete emergency repair. Mixes with reinforcement fibers showed superior results to the mix without, in terms of compressive strength, flexural strength, splitting tensile strength, chloride ion penetration resistance, abrasion resistance and impact resistance. With regard to the reinforcement fibers, the compressive strength, flexural strength, splitting tensile strength, and impact resistance of the mix with macro synthetic fiber showed improved results as a structural fiber compared to mixes containing natural jute and PVA fibers, namely the non-structural fibers. However, using the reinforcement fiber type had little effect on chloride ion penetration resistance or abrasion resistance. Thus, the addition of reinforcement fibers was effective in improving the performance of RCLMFRRHCC. The use of macro synthetic fibers improved the mechanical characteristics of concrete. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Design of 4 × 1 Power Beam Combiner Based on MultiCore Photonic Crystal Fiber
Appl. Sci. 2017, 7(7), 695; doi:10.3390/app7070695
Received: 14 June 2017 / Revised: 2 July 2017 / Accepted: 3 July 2017 / Published: 5 July 2017
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Abstract
A novel concept of 4 × 1 power beam combiner based on multicore photonic crystal fiber is described. The light coupling obtained by integrating small air-holes in the multicore photonic crystal fiber (PCF) structure allows light coupling between coherent laser sources to the
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A novel concept of 4 × 1 power beam combiner based on multicore photonic crystal fiber is described. The light coupling obtained by integrating small air-holes in the multicore photonic crystal fiber (PCF) structure allows light coupling between coherent laser sources to the central core. The beam propagation method (BPM) and coupled mode theory were used for analyzing the proposed device. Simulation results show that four coherent fiber laser sources of 1 µm in a multicore PCF structure can be combined into one source after 2.6 mm light propagation, with a power efficiency of 99.6% and bandwidth of 220 nm. In addition, a higher 8 × 1 ratio combiner was demonstrated, based on the proposed device. Thus, the device can be very useful to combine beams. Full article
(This article belongs to the Special Issue Solid State Lasers Materials, Technologies and Applications)
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Open AccessArticle IoT and iTV for Interconnection, Monitoring, and Automation of Common Areas of Residents
Appl. Sci. 2017, 7(7), 696; doi:10.3390/app7070696
Received: 1 June 2017 / Revised: 30 June 2017 / Accepted: 30 June 2017 / Published: 6 July 2017
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Abstract
Internet and, in particular, computer networks have become a key issue in our daily lives, due to the birth of wireless technologies. Internet of Things (IoT) aims to integrate sensors and actuators in daily objects, maximizing miniaturization and minimizing the economic cost of
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Internet and, in particular, computer networks have become a key issue in our daily lives, due to the birth of wireless technologies. Internet of Things (IoT) aims to integrate sensors and actuators in daily objects, maximizing miniaturization and minimizing the economic cost of these hardware components. The purpose is to connect these components to the Internet through wireless and fixed networks, and thereby produce information in real time which is then stored for later processing. On the other hand, Interactive TV (iTV) combines traditional TV with interactivity similar to that of the Internet and the personal computer. The evolution of TV technology has brought computing power to this device, offering services apart from the traditional ones, making it a device capable of running applications and maximizing its networking potential. This work presents a framework that includes and integrates a wireless sensor network, an IoT platform, and a real interactive TV application. It covers the deployment and communication of the wireless sensor network through the interoperability of data, to final consumption, through a real interactive television application. It has been tested within a residential community to provide real-time information, in order to improve the quality of life of its inhabitants. In addition, it incorporates the possibility of analyzing this information to establish processes with the objective of reducing energy consumption, thus improving sustainability and contributing to the efficient use of existing resources. The proposed framework serves as the basis for any deployment of similar characteristics. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Experimental Study on the Physical Simulation of Water Invasion in Carbonate Gas Reservoirs
Appl. Sci. 2017, 7(7), 697; doi:10.3390/app7070697
Received: 6 June 2017 / Revised: 27 June 2017 / Accepted: 29 June 2017 / Published: 7 July 2017
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Abstract
Water invasion in carbonate gas reservoirs often results in excessive water production, which limits the economic life of gas wells. This is influenced by reservoir properties and production parameters, such as aquifer, fracture, permeability and production rate. In this study, seven full diameter
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Water invasion in carbonate gas reservoirs often results in excessive water production, which limits the economic life of gas wells. This is influenced by reservoir properties and production parameters, such as aquifer, fracture, permeability and production rate. In this study, seven full diameter core samples with dissolved pores and fractures were designed and an experimental system of water invasion in gas reservoirs with edge and bottom aquifers was established to simulate the process of water invasion. Then the effects of the related reservoir properties and production parameters were investigated. The results show that the edge and bottom aquifers supply the energy for gas reservoirs with dissolved pores, which delays the decline of bottom-hole pressure. The high water aquifer defers the decline of water invasion in the early stage while the big gas production rate accelerates water influx in gas reservoirs. The existence of fractures increases the discharge area of gas reservoirs and the small water influx can result in a substantial decline in recovery factor. With the increase of permeability, gas production rate has less influence on recovery factor. These results can provide insights into a better understanding of water invasion and the effects of reservoir properties and production parameters so as to optimize the production in carbonate gas reservoirs. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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Open AccessArticle Preparation of Titania on Stainless Steel by the Spray-ILGAR Technique as Active Photocatalyst under UV Light Irradiation for the Decomposition of Acetaldehyde
Appl. Sci. 2017, 7(7), 698; doi:10.3390/app7070698
Received: 31 May 2017 / Revised: 21 June 2017 / Accepted: 27 June 2017 / Published: 6 July 2017
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Abstract
One of the methods used to produce buffer layers for thin film solar cells is the Spray ion layer gas reaction (SPRAY-ILGAR). This method has exhibited astonishing efficiencies in the fabrication of homogenous compact metal chalcogenide films. The same approach can be applied
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One of the methods used to produce buffer layers for thin film solar cells is the Spray ion layer gas reaction (SPRAY-ILGAR). This method has exhibited astonishing efficiencies in the fabrication of homogenous compact metal chalcogenide films. The same approach can be applied in the preparation of photocatalyst on a substrate, in order to acquire a homogeneous and durable layer. In this work, the Spray-ILGAR technique has been utilized in the preparation of titania photocatalysts on stainless steel, which was carried out at Helmholtz-Zentrum Berlin for Materials and Energy, in Berlin, Germany. The characterizations and photocatalytic testing of the synthesized materials were then done at the Institute of Catalysis, Hokkaido University. The scanning electron microscopy (SEM) analysis showed that the titania was dispersed uniformly on top of the stainless steel, with a very durable and strong attachment. It was also found that the concentration of the titania on stainless steel can be easily varied by changing the concentration of the titania-precursor solution. Higher concentrations will result in a more compact and dense layer, while lowering the concentration of the precursor solution produces a less dense layer of TiO2. Apart from that, different temperatures did not change the distribution of the samples much. The photocatalytic activity of the synthesized materials was determined in terms of the photocatalytic decomposition of acetaldehyde under ultra violet (UV) light irradiation. The photocatalytic testing results proved that the samples can completely degrade acetaldehyde under UV irradiation. The heating temperature played a crucial role, as the sample prepared by with heating temperature of 550 °C, concentration of titania-precursor of 6.83 mM and a spraying time of 12 min showed the best results, requiring only 35 min to fully degrade 500 ppm of acetaldehyde. Full article
(This article belongs to the Special Issue Selected Papers from IEEE ICASI 2017)
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Open AccessArticle An Energy Demodulation Based Fiber Optic Sensing System for Landslide Early-Warning
Appl. Sci. 2017, 7(7), 699; doi:10.3390/app7070699
Received: 24 March 2017 / Revised: 5 June 2017 / Accepted: 9 June 2017 / Published: 7 July 2017
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Abstract
To help reduce the impact of geo-hazards, an innovative landslide early-warning technology based on an energy demodulation-based fiber optic sensing (FOS-LW for short) technology, is introduced in this paper. FOS-LW measures the energy change in a sensing fiber at the segment of micro-bending,
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To help reduce the impact of geo-hazards, an innovative landslide early-warning technology based on an energy demodulation-based fiber optic sensing (FOS-LW for short) technology, is introduced in this paper. FOS-LW measures the energy change in a sensing fiber at the segment of micro-bending, which can be caused by landslide movements, and automatically raises an alarm as soon as the measured signal intensity in the fiber reaches a pre-set threshold. Based on the sensing of micro-bending losses in the fiber optics, a two-event sensing algorithm has been developed for the landslide early-warning. The feasibility of the FOS-LW technology is verified through laboratory simulation and field tests. The result shows that FOS-LW has some unique features—such as the graded alarm, real-time responses, remote monitoring, low cost and passive optical network—and can be applied in the early-warning of landslides. Full article
(This article belongs to the Special Issue Distributed Optical Fiber Sensors)
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Open AccessArticle Integrated Optical Content Addressable Memories (CAM) and Optical Random Access Memories (RAM) for Ultra-Fast Address Look-Up Operations
Appl. Sci. 2017, 7(7), 700; doi:10.3390/app7070700
Received: 30 May 2017 / Revised: 3 July 2017 / Accepted: 4 July 2017 / Published: 7 July 2017
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Abstract
Electronic Content Addressable Memories (CAM) implement Address Look-Up (AL) table functionalities of network routers; however, they typically operate in the MHz regime, turning AL into a critical network bottleneck. In this communication, we demonstrate the first steps towards developing optical CAM alternatives to
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Electronic Content Addressable Memories (CAM) implement Address Look-Up (AL) table functionalities of network routers; however, they typically operate in the MHz regime, turning AL into a critical network bottleneck. In this communication, we demonstrate the first steps towards developing optical CAM alternatives to enable a re-engineering of AL memories. Firstly, we report on the photonic integration of Semiconductor Optical Amplifier-Mach Zehnder Interferometer (SOA-MZI)-based optical Flip-Flop and Random Access Memories on a monolithic InP platform, capable of storing the binary prefix-address data-bits and the outgoing port information for next hop routing, respectively. Subsequently the first optical Binary CAM cell (B-CAM) is experimentally demonstrated, comprising an InP Flip-Flop and a SOA-MZI Exclusive OR (XOR) gate for fast search operations through an XOR-based bit comparison, yielding an error-free 10 Gb/s operation. This is later extended via physical layer simulations in an optical Ternary-CAM (T-CAM) cell and a 4-bit Matchline (ML) configuration, supporting a third state of the “logical X” value towards wildcard bits of network subnet masks. The proposed functional CAM and Random Access Memories (RAM) sub-circuits may facilitate light-based Address Look-Up tables supporting search operations at 10 Gb/s and beyond, paving the way towards minimizing the disparity with the frantic optical transmission linerates, and fast re-configurability through multiple simultaneous Wavelength Division Multiplexed (WDM) memory access requests. Full article
(This article belongs to the Special Issue Applications of Semiconductor Optical Amplifiers)
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Open AccessFeature PaperArticle Investigation of Catalytic Effects and Compositional Variations in Desorption Characteristics of LiNH2-nanoMgH2
Appl. Sci. 2017, 7(7), 701; doi:10.3390/app7070701
Received: 9 June 2017 / Revised: 28 June 2017 / Accepted: 4 July 2017 / Published: 7 July 2017
PDF Full-text (3943 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
LiNH2 and a pre-processed nanoMgH2 with 1:1 and 2:1 molar ratios were mechano-chemically milled in a high-energy planetary ball mill under inert atmosphere, and at room temperature and atmospheric pressure. Based on the thermogravimetric analysis (TGA) experiments, 2LiNH2-nanoMgH2
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LiNH2 and a pre-processed nanoMgH2 with 1:1 and 2:1 molar ratios were mechano-chemically milled in a high-energy planetary ball mill under inert atmosphere, and at room temperature and atmospheric pressure. Based on the thermogravimetric analysis (TGA) experiments, 2LiNH2-nanoMgH2 demonstrated superior desorption characteristics when compared to the LiNH2-nanoMgH2. The TGA studies also revealed that doping 2LiNH2-nanoMgH2 base material with 2 wt. % nanoNi catalyst enhances the sorption kinetics at lower temperatures. Additional investigation of different catalysts showed improved reaction kinetics (weight percentage of H2 released per minute) of the order TiF3 > nanoNi > nanoTi > nanoCo > nanoFe > multiwall carbon nanotube (MWCNT), and reduction in the on-set decomposition temperatures of the order nanoCo > TiF3 > nanoTi > nanoFe > nanoNi > MWCNT for the base material 2LiNH2-nanoMgH2. Pristine and catalyst-doped 2LiNH2-nanoMgH2 samples were further probed by X-ray diffraction, Fourier transform infrared spectroscopy, transmission and scanning electron microscopies, thermal programmed desorption and pressure-composition-temperature measurements to better understand the improved performance of the catalyst-doped samples, and the results are discussed. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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Open AccessArticle Evaluation of Aging Resistance of Graphene Oxide Modified Asphalt
Appl. Sci. 2017, 7(7), 702; doi:10.3390/app7070702
Received: 19 June 2017 / Revised: 28 June 2017 / Accepted: 4 July 2017 / Published: 7 July 2017
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Abstract
Graphene oxide (GO) has a unique layered structure with excellent gas and liquid blocking properties. It is widely used in many areas, such as gas sensors, carbon-based electronics, impermeable membranes, and polymeric composite materials. In order to evaluate whether GO (1% and 3%
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Graphene oxide (GO) has a unique layered structure with excellent gas and liquid blocking properties. It is widely used in many areas, such as gas sensors, carbon-based electronics, impermeable membranes, and polymeric composite materials. In order to evaluate whether GO (1% and 3% by weight of asphalt) can improve the aging resistance performance of the asphalt, 80/100 penetration grade asphalt (90 A) and styrene–butadiene–styrene modified asphalt (SBS MA) were used to prepare the GO modified asphalt by the melt blending method. The surface morphology of the GO was analyzed by scanning electron microscope (SEM). The UV aging test was conducted to simulate the aging during the service period. After UV aging test, the physical performances of GO-modified asphalts were tested, and the IC=O and IS=O increments were tested by Fourier transform infrared spectroscopy (FTIR) to evaluate the aging resistance performance of the GO modified asphalt. In addition, the rheological properties of GO modified asphalts were studied using a dynamic shear rheometer (DSR). The SEM analysis indicated that the GO exhibits many shared edges, and no agglomeration phenomenon was found. With respect to the physical performance test, the FTIR and the DSR results show that GO can improve the UV aging resistance performance of 90 A and SBS MA. In addition, the analysis indicated that the improvement effect of 3% GO is better than the 1% GO. The testing on the rheological properties of the modified asphalt indicated that the GO can also improve the thermo-oxidative aging resistance performance of asphalt. Full article
(This article belongs to the Special Issue Advanced Asphalt Materials and Paving Technologies)
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Open AccessArticle An Improved Distribution Policy with a Maintenance Aspect for an Urban Logistic Problem
Appl. Sci. 2017, 7(7), 703; doi:10.3390/app7070703
Received: 30 May 2017 / Revised: 30 June 2017 / Accepted: 5 July 2017 / Published: 7 July 2017
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Abstract
In this paper, we present an improved distribution plan supporting an urban distribution center (UDC) to solve the last mile problem of urban freight. This is motivated by the need of UDCs to satisfy daily demand in time under a high service level
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In this paper, we present an improved distribution plan supporting an urban distribution center (UDC) to solve the last mile problem of urban freight. This is motivated by the need of UDCs to satisfy daily demand in time under a high service level in allocated urban areas. Moreover, these demands could not be satisfied in individual cases because the delivery rate can be less than daily demand and/or affected by random failure or maintenance actions of vehicles. The scope of our work is to focus on a UDC, which needs to satisfy demands in a finite horizon. To that end, we consider a distribution policy on two sequential plans, a distribution plan correlated to a maintenance plan using a subcontracting strategy with several potential urban distribution centers (UDCs) and performing preventive maintenance to ensure deliveries for their allocated urban area. The choice of subcontractor will depend on distance, environmental and availability criteria. In doing so, we define a mathematical model for searching the best distribution and maintenance plans using a subcontracting strategy. Moreover, we consider delay for the next periods with an expensive penalty. Finally, we present a numerical example illustrating the benefits of our approach. Full article
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Open AccessArticle Creation of Optimal Frequency for Electrostatic Force Microscopy Using Direct Digital Synthesizer
Appl. Sci. 2017, 7(7), 704; doi:10.3390/app7070704
Received: 19 May 2017 / Revised: 29 June 2017 / Accepted: 5 July 2017 / Published: 8 July 2017
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Abstract
Electrostatic force microscopy (EFM) is a useful technique when measuring the surface electric potential of a substrate regardless of its topography. Here, we have developed a frequency detection method for alternating current (AC) bias in EFM. Instead of an internal lock-in amplifier (LIA)
[...] Read more.
Electrostatic force microscopy (EFM) is a useful technique when measuring the surface electric potential of a substrate regardless of its topography. Here, we have developed a frequency detection method for alternating current (AC) bias in EFM. Instead of an internal lock-in amplifier (LIA) for EFM that only detects ωe and e, we have used other LIAs that can amplify the amplitude of specific frequency by direct digital synthesizer (DDS), that finds the optimal frequency of surface charge images. In order to confirm the performance of the proposed methods, the electrical properties of lead zirconate titanate (PZT) and triglycine sulfate (TGS) samples were measured. In addition, we compared the performances of the frequency-detection method and the conventional EFM method. Ultimately, enhanced images could be achieved using the frequency-detection method. The optimal modulated frequency-shift for force–gradient measurements was found to be 2 kHz. Additionally, we have shown that it is possible to use a hard cantilever (K = 42 N/m, 330 kHz). Therefore, we expect that this technique can be applied to measure the electrical properties of bio-molecular films. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Collinear FAST CARS for Chemical Mapping of Gases
Appl. Sci. 2017, 7(7), 705; doi:10.3390/app7070705
Received: 12 May 2017 / Revised: 1 July 2017 / Accepted: 2 July 2017 / Published: 8 July 2017
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Abstract
We examine the concentration dependence of the Coherent Anti-Stokes Raman Scattering (CARS) signal obtained for gas mixtures at various conditions using the Femtosecond Adaptive Spectroscopic Technique (FAST). We use the CARS signal of the Q-branch vibrational oscillation of molecular oxygen (1556 cm−1
[...] Read more.
We examine the concentration dependence of the Coherent Anti-Stokes Raman Scattering (CARS) signal obtained for gas mixtures at various conditions using the Femtosecond Adaptive Spectroscopic Technique (FAST). We use the CARS signal of the Q-branch vibrational oscillation of molecular oxygen (1556 cm−1) to confirm the quadratic dependence of the coherent signal on the number of molecules in a test volume. In addition, we demonstrate multi-shot FAST CARS imaging of a gas flow in free space by raster-scanning the area of interest. Full article
(This article belongs to the Special Issue Optics and Spectroscopy for Fluid Characterization)
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Open AccessArticle A Si-αTCP Scaffold for Biomedical Applications: An Experimental Study Using the Rabbit Tibia Model
Appl. Sci. 2017, 7(7), 706; doi:10.3390/app7070706
Received: 5 June 2017 / Revised: 29 June 2017 / Accepted: 6 July 2017 / Published: 8 July 2017
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Abstract
We herein hypothesize that bioceramics with an appropriate architecture made of Si-αtricalcium phosphate (Si-αTCP) meet the biocompatibility and biological safety requirements for bone grafting applications. Polyurethane sponges were used as templates, soaked with ceramic slurry at different ratios and sintered at 1400 °C
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We herein hypothesize that bioceramics with an appropriate architecture made of Si-αtricalcium phosphate (Si-αTCP) meet the biocompatibility and biological safety requirements for bone grafting applications. Polyurethane sponges were used as templates, soaked with ceramic slurry at different ratios and sintered at 1400 °C for 3 h at heating and cooling rates of 5 °C/min. Four critical size defects of 6 mm Ø were created in 15 NZ tibias. Three working times were established as 15, 30 and 60 days. A highly porous Si-αTCP scaffold with micro and macropores and pore interconnectivity was produced by the polymer replication method. Considerably more bone formation took place in the pores and the periphery of the implant for the Si-αTCP scaffolds than for the control group. The ceramic scaffold (68.32% ± 1.21) generated higher bone-to-implant contact (BIC) percentage values (higher quality, closer contact) than the control group, according to the histomorphometric analysis, and defect closure was significant compared with the control group. The highest percentages of BIC and bone formation were found after 60 days of implantation. These results suggest that the Si-αTCP scaffold is advantageous for initial bone regeneration. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Vibration Control Design for a Plate Structure with Electrorheological ATVA Using Interval Type-2 Fuzzy System
Appl. Sci. 2017, 7(7), 707; doi:10.3390/app7070707
Received: 16 May 2017 / Revised: 30 June 2017 / Accepted: 3 July 2017 / Published: 8 July 2017
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Abstract
This study presents vibration control using actively tunable vibration absorbers (ATVA) to suppress vibration of a thin plate. The ATVA is made of a sandwich hollow structure embedded with electrorheological fluid (ERF). ERF is considered to be one of the most important smart
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This study presents vibration control using actively tunable vibration absorbers (ATVA) to suppress vibration of a thin plate. The ATVA is made of a sandwich hollow structure embedded with electrorheological fluid (ERF). ERF is considered to be one of the most important smart fluids and it is suitable to be embedded in a smart structure due to its controllable rheological property. ERF’s apparent viscosity can be controlled in response to the electric field and the change is reversible in 10 microseconds. Therefore, the physical properties of the ERF-embedded smart structure, such as the stiffness and damping coefficient, can be changed in response to the applied electric field. A mathematical model is difficult to be obtained to describe the exact characteristics of the ERF embedded ATVA because of the nonlinearity of ERF’s viscosity. Therefore, a fuzzy modeling and experimental validations of ERF-based ATVA from stationary random vibrations of thin plates are presented in this study. Because Type-2 fuzzy sets generalize Type-1 fuzzy sets so that more modeling uncertainties can be handled, a semi-active vibration controller is proposed based on Type-2 fuzzy sets. To investigate the different performances by using different types of fuzzy controllers, the experimental measurements employing both type-1 fuzzy and interval type-2 fuzzy controllers are implemented by the Compact RIO embedded system. The fuzzy modeling framework and solution methods presented in this work can be used for design, performance analysis, and optimization of ATVA from varying harmonic vibration of thin plates. Full article
(This article belongs to the Special Issue Selected Papers from the 2016 International Conference on Inventions)
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Open AccessArticle Potential Model Overfitting in Predicting Soil Carbon Content by Visible and Near-Infrared Spectroscopy
Appl. Sci. 2017, 7(7), 708; doi:10.3390/app7070708
Received: 13 June 2017 / Revised: 5 July 2017 / Accepted: 5 July 2017 / Published: 8 July 2017
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Abstract
Soil spectroscopy is known as a rapid and cost-effective method for predicting soil properties from spectral data. The objective of this work was to build a statistical model to predict soil carbon content from spectral data by partial least squares regression using a
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Soil spectroscopy is known as a rapid and cost-effective method for predicting soil properties from spectral data. The objective of this work was to build a statistical model to predict soil carbon content from spectral data by partial least squares regression using a limited number of soil samples. Soil samples were collected from two soil orders (Andisol and Ultisol), where the dominant land cover is native Nothofagus forest. Total carbon was analyzed in the laboratory and samples were scanned using a spectroradiometer. We found evidence that the reflectance was influenced by soil carbon content, which is consistent with the literature. However, the reflectance was not useful for building an appropriate regression model. Thus, we report here intriguing results obtained in the calibration process that can be confusing and misinterpreted. For instance, using the Savitzky–Golay filter for pre-processing spectral data, we obtained R2 = 0.82 and root-mean-squared error (RMSE) = 0.61% in model calibration. However, despite these values being comparable with those of other similar studies, in the cross-validation procedure, the data showed an unusual behavior that leads to the conclusion that the model overfits the data. This indicates that the model should not be used on unobserved data. Full article
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Open AccessArticle Transmission Power Determination Based on Power Amplifier Operations in Large-Scale MIMO-OFDM Systems
Appl. Sci. 2017, 7(7), 709; doi:10.3390/app7070709
Received: 29 April 2017 / Revised: 22 June 2017 / Accepted: 7 July 2017 / Published: 9 July 2017
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Abstract
This paper presents a method to determine transmission power based on power amplifier (PA) operations in order to improve the energy efficiency (EE) of a large-scale (LS) Multiple Input Multiple Output (MIMO)-OFDM system, which is a multi-carrier multiple antenna system with a large
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This paper presents a method to determine transmission power based on power amplifier (PA) operations in order to improve the energy efficiency (EE) of a large-scale (LS) Multiple Input Multiple Output (MIMO)-OFDM system, which is a multi-carrier multiple antenna system with a large amount of transmitter (TX) antennas. Regarding the EE improvement, we propose two kinds of PA operation schemes: increasing the effective TX power (ITXP) and reducing the PA power consumption (RPC) assuming that a reduction of peak-to-average power ratio is applied in the appropriate manner. Closed-form expressions of relative EE are derived for both schemes, and the relative EE of the ITXP scheme is shown to depend on the precoding method that is applied to reduce the inter-user interference, while that of the RPC scheme is independent of the precoding method. The relative EE difference between the ITXP and the RPC schemes is also shown to rely on the occupation ratio of the PA power consumption over the total power consumption. Thus, the EE can remarkably improve by selecting the appropriate scheme based on the circumstances. The results of a simulation also validate the derived closed-form expression of the relative EE. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Experimental Study of Vibration Isolation Characteristics of a Geometric Anti-Spring Isolator
Appl. Sci. 2017, 7(7), 711; doi:10.3390/app7070711
Received: 12 June 2017 / Revised: 28 June 2017 / Accepted: 6 July 2017 / Published: 10 July 2017
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Abstract
In order to realize low-frequency vibration isolation, a novel geometric anti-spring isolator consisting of several cantilever blade springs are developed in this paper. The optimal design parameters of the geometric anti-spring isolator for different nonlinear geometric parameters are theoretically obtained. The transmissibility characteristic
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In order to realize low-frequency vibration isolation, a novel geometric anti-spring isolator consisting of several cantilever blade springs are developed in this paper. The optimal design parameters of the geometric anti-spring isolator for different nonlinear geometric parameters are theoretically obtained. The transmissibility characteristic of the geometric anti-spring isolator is investigated through mathematical simulation. A geometric anti-spring isolator with a nonlinear geometric parameter of 0.92 is designed and its vibration isolation performance and nonlinearity characteristic is experimentally studied. The experiment results show that the designed isolator has good low-frequency vibration isolation performance, of which the initial isolation frequency is less than 3.6 Hz when the load weight is 21 kg. The jump phenomena of the response of the isolator under linear frequency sweep excitation are observed, and this result demonstrates that the geometric anti-spring isolator has a complex nonlinearity characteristics with the increment of excitation amplitude. This research work provides a theoretical and experimental basis for the application of the nonlinear geometric anti-spring low-frequency passive vibration isolation technology in engineering practice. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Simulating the Effects of the Airborne Lidar Scanning Angle, Flying Altitude, and Pulse Density for Forest Foliage Profile Retrieval
Appl. Sci. 2017, 7(7), 712; doi:10.3390/app7070712
Received: 20 April 2017 / Revised: 3 July 2017 / Accepted: 4 July 2017 / Published: 10 July 2017
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Abstract
Foliage profile is a key biophysical parameter for forests. Airborne Light Detection and Ranging is an effective tool for vegetation parameter retrieval. Data acquisition conditions influence the estimation of biophysical parameters. To acquire accurate foliage profiles at the lowest cost, we used simulations
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Foliage profile is a key biophysical parameter for forests. Airborne Light Detection and Ranging is an effective tool for vegetation parameter retrieval. Data acquisition conditions influence the estimation of biophysical parameters. To acquire accurate foliage profiles at the lowest cost, we used simulations to explore the effects of data acquisition conditions on forest foliage profile retrieval. First, a 3-D forest scene and the airborne small-footprint full-waveform LiDAR data were simulated by the DART model. Second, the foliage profile was estimated from LiDAR data based on a Geometric Optical and Radiative Transfer model. Lastly, the effects of the airborne LiDAR scanning angle, flying altitude, and pulse density on foliage profile retrieval were explored. The results indicated that the scanning angle was an important factor in the foliage profile retrieval, and the optimal scanning angle was 20°. The optimal scanning angle was independent of flying altitude and pulse density, and combinations of multiple scanning angles could improve the accuracy of the foliage profile estimation. The flying altitude and pulse density had little influence on foliage profile retrieval at plot level and could be ignored. In general, our study provides reliable information for selecting the optimal instrument operational parameters to acquire more accurate foliage profiles and minimize data acquisition costs. Full article
(This article belongs to the Special Issue Laser Scanning)
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Open AccessArticle Member Discrete Element Method for Static and Dynamic Responses Analysis of Steel Frames with Semi-Rigid Joints
Appl. Sci. 2017, 7(7), 714; doi:10.3390/app7070714
Received: 27 May 2017 / Revised: 6 July 2017 / Accepted: 7 July 2017 / Published: 11 July 2017
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Abstract
In this paper, a simple and effective numerical approach is presented on the basis of the Member Discrete Element Method (MDEM) to investigate static and dynamic responses of steel frames with semi-rigid joints. In the MDEM, structures are discretized into a set of
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In this paper, a simple and effective numerical approach is presented on the basis of the Member Discrete Element Method (MDEM) to investigate static and dynamic responses of steel frames with semi-rigid joints. In the MDEM, structures are discretized into a set of finite rigid particles. The motion equation of each particle is solved by the central difference method and two adjacent arbitrarily particles are connected by the contact constitutive model. The above characteristics means that the MDEM is able to naturally handle structural geometric nonlinearity and fracture. Meanwhile, the computational framework of static analysis is consistent with that of dynamic analysis, except the determination of damping. A virtual spring element with two particles but without actual mass and length is used to simulate the mechanical behaviors of semi-rigid joints. The spring element is not directly involved in the calculation, but is employed only to modify the stiffness coefficients of contact elements at the semi-rigid connections. Based on the above-mentioned concept, the modified formula of the contact element stiffness with consideration of semi-rigid connections is deduced. The Richard-Abbort four-parameter model and independent hardening model are further introduced accordingly to accurately capture the nonlinearity and hysteresis performance of semi-rigid connections. Finally, the numerical approach proposed is verified by complex behaviors of steel frames with semi-rigid connections such as geometric nonlinearity, snap-through buckling, dynamic responses and fracture. The comparison of static and dynamic responses obtained using the modified MDEM and those of the published studies illustrates that the modified MDEM can simulate the mechanical behaviors of semi-rigid connections simply and directly, and can accurately effectively capture the linear and nonlinear behaviors of semi-rigid connections under static and dynamic loading. Some conclusions, as expected, are drawn that structural bearing capacity under static loading will be overestimated if semi-rigid connections are ignored; when the frequency of dynamic load applied is close to structural fundamental frequency, hysteresis damping of nonlinear semi-rigid connections can cause energy dissipation compared to rigid and linear semi-rigid connections, thus avoiding the occurrence of resonance. Additionally, fracture analysis also indicates that semi-rigid steel frames possess more anti-collapse capacity than that with rigid steel frames. Full article
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Open AccessArticle Reduction of Hexavalent Chromium Using Sorbaria sorbifolia Aqueous Leaf Extract
Appl. Sci. 2017, 7(7), 715; doi:10.3390/app7070715
Received: 19 June 2017 / Revised: 5 July 2017 / Accepted: 6 July 2017 / Published: 11 July 2017
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Abstract
Aqueous plant leaves extract (PLE) of an abundant shrub, Sorbaria sorbifolia, was explored for the reduction of hexavalent chromium, Cr(VI), to trivalent chromium, Cr(III). The effect of contact time, pH, PLE quantity, ionic strength, hardness, temperature and effective initial Cr(VI) ion concentration
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Aqueous plant leaves extract (PLE) of an abundant shrub, Sorbaria sorbifolia, was explored for the reduction of hexavalent chromium, Cr(VI), to trivalent chromium, Cr(III). The effect of contact time, pH, PLE quantity, ionic strength, hardness, temperature and effective initial Cr(VI) ion concentration were tested; Cr(VI) reduction followed the pseudo-first order rate kinetics and maximum reduction was observed at pH 2. Significantly, Cr(VI) reduction efficacies varied from 97 to 66% over the pH range of 2 to 10, which bodes well for PLE to be used for the reduction of Cr(VI) also at a higher pH. PLE-mediated Cr(VI) reduction displays considerable efficiency at various ionic strengths; however, hardness strongly affects the reduction ability. Higher temperature significantly enhances the Cr(VI) reduction. This study reveals the potential use of PLE as a green reducing agent in aqueous extract for the efficient reduction of Cr(VI) to Cr(III). Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle Numerical Study on Dynamic Response of a Horizontal Layered-Structure Rock Slope under a Normally Incident Sv Wave
Appl. Sci. 2017, 7(7), 716; doi:10.3390/app7070716
Received: 7 April 2017 / Revised: 30 June 2017 / Accepted: 4 July 2017 / Published: 11 July 2017
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Abstract
Several post-earthquake investigations have indicated that the slope structure plays a leading role in the stability of rock slopes under dynamic loads. In this paper, the dynamic response of a horizontal layered-structure rock slope under harmonic Sv wave is studied by making use
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Several post-earthquake investigations have indicated that the slope structure plays a leading role in the stability of rock slopes under dynamic loads. In this paper, the dynamic response of a horizontal layered-structure rock slope under harmonic Sv wave is studied by making use of the Fast Lagrangian Analysis of Continua method (FLAC). The suitability of FLAC for studying wave transmission across rock joints is validated through comparison with analytical solutions. After parametric studies on Sv wave transmission across the horizontal layered-structure rock slope, it is found that the acceleration amplification coefficient η, which is defined as the ratio of the acceleration at the monitoring point to the value at the toe, wavily increases with an increase of the height along the slope surface. Meanwhile, the fluctuation weakens with normalized joint stiffness K increasing and enhances with normalized joint spacing ξ increasing. The acceleration amplification coefficient of the slope crest ηcrest does not monotonously increase with the increase of ξ, but decreases with the increase of K. Additionally, ηcrest is more sensitive to ξ compared to K. From the contour figures, it can also be found that the contour figures of η take on rhythm, and the effects of ξ on the acceleration amplification coefficient are more obvious compared to the effects on K. Full article
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Open AccessArticle Investigation into the Vibrational Responses of Cylinder Liners in an IC Engine Fueled with Biodiesel
Appl. Sci. 2017, 7(7), 717; doi:10.3390/app7070717
Received: 21 April 2017 / Revised: 27 June 2017 / Accepted: 4 July 2017 / Published: 13 July 2017
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Abstract
The paper presents a study of the relationship between the combustion behavior and vibration response of internal combustion (IC) engines fueled with biodiesel based on finite element modelling along with experimental evaluation. An improved finite element (FE) model is established and validated to
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The paper presents a study of the relationship between the combustion behavior and vibration response of internal combustion (IC) engines fueled with biodiesel based on finite element modelling along with experimental evaluation. An improved finite element (FE) model is established and validated to predict the dynamic responses of cylinder liners with respect to two main sources: combustion shock and piston side thrust. Based on the validated FE model, the response characteristics of the cylinder liner in an IC engine fueled with biodiesel and its causal relationship with excitation sources have been predicted. Due to the lower calorific value of biodiesel, a greater amount of fuel is injected into the combustion chamber to maintain power outputs, which results in a prolonged combustion duration and subsequent higher overall vibration levels, compared with that of diesel. The advanced ignition of biodiesel is the main cause to the compound effect on the coupling of piston side-thrust force, thereby resulting in a nonlinear increase in the root mean square (RMS) of local vibration response close to the combustion top dead center (TDC). These key findings provides insight understandings for not only biodiesel combustion diagnostics but also more accurate diagnostics of fossil diesel based on nonintrusive vibrations. Full article
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Open AccessArticle Permeability and Stiffness Assessment of Paved and Unpaved Roads with Geocomposite Drainage Layers
Appl. Sci. 2017, 7(7), 718; doi:10.3390/app7070718
Received: 10 June 2017 / Revised: 7 July 2017 / Accepted: 9 July 2017 / Published: 13 July 2017
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Abstract
Poor subsurface drainage is frequently identified as a factor leading to the accelerated damage of roadway systems. Geocomposite drainage layers offer an alternative to traditional methods but have not been widely evaluated, especially in terms of the impact of changes on both drainage
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Poor subsurface drainage is frequently identified as a factor leading to the accelerated damage of roadway systems. Geocomposite drainage layers offer an alternative to traditional methods but have not been widely evaluated, especially in terms of the impact of changes on both drainage capacity and stiffness. In this study, both paved and unpaved test sections with and without an embedded geocomposite drainage layer were constructed and tested. The geocomposite layers were installed directly beneath the roadway surface layers to help the rapid drainage of any infiltrated water and thus prevent water entering the underlying foundation materials. The laboratory, field, and numerical analysis results showed that the geocomposite layers increased the permeability of roadway systems by two to three orders of magnitude and that it can effectively prevent the surface and foundation materials from becoming saturated during heavy rainfall events. For the stiffness of the sections, the paved sections with and without a geocomposite layer showed that the composite modulus values measured at the surface were more reflective of the foundation layer support conditions beneath the geocomposite layer than the geocomposite layer itself. The unpaved road section with the geocomposite layer yielded lower composite modulus values than the control section but showed overall better road surface conditions after a rain event due to the improved subsurface drainage condition. Full article
(This article belongs to the Special Issue Advanced Asphalt Materials and Paving Technologies)
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Open AccessArticle Analysis on the Accuracy of Intraoral Scanners: The Effects of Mandibular Anterior Interdental Space
Appl. Sci. 2017, 7(7), 719; doi:10.3390/app7070719
Received: 20 June 2017 / Revised: 7 July 2017 / Accepted: 10 July 2017 / Published: 13 July 2017
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Abstract
In this study, we evaluated the effects of mandibular anterior interdental space on the accuracy of intraoral scanners. Four models of mandibular arch with varying distances of anterior interdental space were analyzed; incisors were evenly spaced out between the two canines by 0
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In this study, we evaluated the effects of mandibular anterior interdental space on the accuracy of intraoral scanners. Four models of mandibular arch with varying distances of anterior interdental space were analyzed; incisors were evenly spaced out between the two canines by 0 mm, 1 mm, 3 mm, and 5 mm. The full arch of each model was scanned 10 times with iTero® and Trios®. The images were superimposed with those from the reference scanner (Sensable S3) and compared using Geomagic Verify. Statistical analysis was conducted using a t-test, paired t-test, and one-way analysis of variance (ANOVA). Differences in the accuracy of images were statistically significant according to both iTero® and Trios®; a greater deviation was noted with increasing anterior interdental space (p < 0.05). Upon dividing the lower arch into five sections, larger deviation was observed with iTero® in the molar area, except in the model with 1 mm space. With Trios®, the largest deviation was observed in the right molar area in all models. The maximum deviations of intermolar width were 0.66 mm and 0.76 mm in iTero® and Trios®, respectively. This comparison suggests that Trios® demonstrates a higher accuracy than iTero® in all models and in all sections of the arch. However, the mean deviations indicate that both iTero® and Trios® are clinically acceptable. Full article
(This article belongs to the Special Issue Laser Scanning)
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Open AccessFeature PaperArticle SwissFEL: The Swiss X-ray Free Electron Laser
by , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , and
Appl. Sci. 2017, 7(7), 720; doi:10.3390/app7070720
Received: 13 June 2017 / Revised: 29 June 2017 / Accepted: 30 June 2017 / Published: 14 July 2017
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Abstract
The SwissFEL X-ray Free Electron Laser (XFEL) facility started construction at the Paul Scherrer Institute (Villigen, Switzerland) in 2013 and will be ready to accept its first users in 2018 on the Aramis hard X-ray branch. In the following sections we will summarize
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The SwissFEL X-ray Free Electron Laser (XFEL) facility started construction at the Paul Scherrer Institute (Villigen, Switzerland) in 2013 and will be ready to accept its first users in 2018 on the Aramis hard X-ray branch. In the following sections we will summarize the various aspects of the project, including the design of the soft and hard X-ray branches of the accelerator, the results of SwissFEL performance simulations, details of the photon beamlines and experimental stations, and our first commissioning results. Full article
(This article belongs to the Special Issue X-Ray Free-Electron Laser)
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Open AccessArticle The New Concept of Nano-Device Spectroscopy Based on Rabi–Bloch Oscillations for THz-Frequency Range
Appl. Sci. 2017, 7(7), 721; doi:10.3390/app7070721
Received: 21 June 2017 / Revised: 9 July 2017 / Accepted: 10 July 2017 / Published: 14 July 2017
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Abstract
We considered one-dimensional quantum chains of two-level Fermi particles coupled via the tunneling driven both by ac and dc fields in the regimes of strong and ultrastrong coupling. The frequency of ac field is matched with the frequency of the quantum transition. Based
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We considered one-dimensional quantum chains of two-level Fermi particles coupled via the tunneling driven both by ac and dc fields in the regimes of strong and ultrastrong coupling. The frequency of ac field is matched with the frequency of the quantum transition. Based on the fundamental principles of electrodynamics and quantum theory, we developed a general model of quantum dynamics for such interactions. We showed that the joint action of ac and dc fields leads to the strong mutual influence of Rabi- and Bloch oscillations, one to another. We focused on the regime of ultrastrong coupling, for which Bloch- and Rabi-frequencies are significant values of the frequency of interband transition. The Hamiltonian was solved numerically, with account of anti-resonant terms. It manifests by the appearance of a great number of narrow high-amplitude resonant lines in the spectra of tunneling current and dipole moment. We proposed the new concept of terahertz (THz) spectroscopy, which is promising for different applications in future nanoelectronics and nano-photonics. Full article
(This article belongs to the Special Issue Nanophotonics)
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Open AccessArticle Phase Change Material Selection for Thermal Processes Working under Partial Load Operating Conditions in the Temperature Range between 120 and 200 °C
Appl. Sci. 2017, 7(7), 722; doi:10.3390/app7070722
Received: 15 June 2017 / Revised: 9 July 2017 / Accepted: 10 July 2017 / Published: 14 July 2017
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Abstract
In some processes, latent heat thermal energy storage (TES) systems might work under partial load operating conditions (the available thermal energy source is discontinuous or insufficient to completely charge the phase change material (PCM)). Therefore, there is a need to study how these
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In some processes, latent heat thermal energy storage (TES) systems might work under partial load operating conditions (the available thermal energy source is discontinuous or insufficient to completely charge the phase change material (PCM)). Therefore, there is a need to study how these conditions affect the discharge process to design a control strategy that can benefit the user of these systems. The aim of this paper is to show and perform at laboratory scale the selection of a PCM, with a phase change temperature between 120 and 200 °C, which will be further used in an experimental facility. Beyond the typical PCM properties, sixteen PCMs are studied here from the cycling and thermal stability point of view, as well as from the health hazard point of view. After 100 melting and freezing cycles, seven candidates out of the sixteen present a suitable cycling stability behaviour and five of them show a maximum thermal-stable temperature higher than 200 °C. Two final candidates for the partial loads approach are found in this temperature range, named high density polyethylene (HDPE) and adipic acid. Full article
(This article belongs to the Special Issue Phase Change Material (PCM) 2017)
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Open AccessFeature PaperArticle Comparison of Microencapsulated Phase Change Materials Prepared at Laboratory Containing the Same Core and Different Shell Material
Appl. Sci. 2017, 7(7), 723; doi:10.3390/app7070723
Received: 16 June 2017 / Revised: 6 July 2017 / Accepted: 11 July 2017 / Published: 14 July 2017
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Abstract
Microencapsulated Phase Change Materials (MPCM) are widely used in active and passive systems for thermal energy storage. To evaluate the strength of a proper shell/PCM system, comparisons were performed between laboratory-prepared MPCM samples produced by in situ polymerization with a phase change temperature
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Microencapsulated Phase Change Materials (MPCM) are widely used in active and passive systems for thermal energy storage. To evaluate the strength of a proper shell/PCM system, comparisons were performed between laboratory-prepared MPCM samples produced by in situ polymerization with a phase change temperature of 50 °C and a particle size of around 1–2 μm with tetracosane as PCM, and polystyrene (PS) and poly (methyl methacrylate) (PMMA) as shells. Evaluation of mechanical performance was performed for different samples by means of Atomic Force Microscopy (AFM) at different temperatures (23 °C and 60 °C) and with different encapsulation ratios (1:3 and 1:1, shell:core) in order to compare their properties with the PCM below and above its phase change. Evaluations of the Effective Young’s modulus (E) and deformation properties were performed for both types of MPCM. For an encapsulation mass ratio of 1:3, PS has better mechanical properties because, when increasing the temperature, the E decreases less than with PMMA. In the comparison between PS/tetracosane systems with different encapsulation mass ratios (1:3 and 1:1), E values were higher for the 1:3 encapsulation mass ratio at both temperatures under study. This means that, in terms of mechanical and thermal properties, the best combination core/shell/encapsulation mass ratio is PS/tetracosane/1:3. Full article
(This article belongs to the Special Issue Phase Change Material (PCM) 2017)
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Open AccessArticle Calculation of the Center of Mass Position of Each Link of Multibody Biped Robots
Appl. Sci. 2017, 7(7), 724; doi:10.3390/app7070724
Received: 26 May 2017 / Revised: 4 July 2017 / Accepted: 10 July 2017 / Published: 14 July 2017