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Appl. Sci., Volume 7, Issue 5 (May 2017)

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Cover Story (view full-size image) Imaging techniques based on light provide access to the microstructure of samples. Optical [...] Read more.
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Open AccessFeature PaperArticle Infrared Spectroscopy for Studying Structure and Aging Effects in Rhamnolipid Biosurfactants
Appl. Sci. 2017, 7(5), 533; https://doi.org/10.3390/app7050533
Received: 23 April 2017 / Revised: 18 May 2017 / Accepted: 19 May 2017 / Published: 22 May 2017
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Abstract
Biosurfactants are produced by microorganisms and represent amphiphilic compounds with polar and non-polar moieties; hence they can be used to stabilize emulsions, e.g., in the cosmetic and food sectors. Their structure and its changes when exposed to light and elevated temperature are yet
[...] Read more.
Biosurfactants are produced by microorganisms and represent amphiphilic compounds with polar and non-polar moieties; hence they can be used to stabilize emulsions, e.g., in the cosmetic and food sectors. Their structure and its changes when exposed to light and elevated temperature are yet to be fully understood. In this study, we demonstrate that attenuated total reflection infrared (ATR-IR) spectroscopy is a useful tool for the analysis of biosurfactants, using rhamnolipids produced by fermentation as an example. A key feature is that the analytical method does not require sample preparation despite the high viscosity of the purified natural product. Full article
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Open AccessArticle Joint Resource Allocation in Secure OFDMA-Based Networks Taking a Base Station as a Two-Way Relay
Appl. Sci. 2017, 7(5), 520; https://doi.org/10.3390/app7050520
Received: 21 March 2017 / Revised: 28 April 2017 / Accepted: 12 May 2017 / Published: 21 May 2017
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Abstract
Due to the broadcast nature of wireless media, all nodes in the coverage of a transmitter are capable of capturing its signals, thus wireless transmission is sensitive to wiretapping. Several existing schemes place an emphasis on secrecy rate improvement, under the protocols of
[...] Read more.
Due to the broadcast nature of wireless media, all nodes in the coverage of a transmitter are capable of capturing its signals, thus wireless transmission is sensitive to wiretapping. Several existing schemes place an emphasis on secrecy rate improvement, under the protocols of amplify-and-forward or decode-and-forward, when there are only relay users in the network. We set up a novel communication model in which normal and two-way relay users coexist in the same cell, taking the base station as a relay. Our objective is to maximize the total secrecy rate, taking subcarrier pairing, subcarrier assignment and power allocation into account, when there is one eavesdropper in one cell of the cellular network. Although this problem is very intricate, we reformulate it as a convex optimization problem by means of Lagrange duality. In order to reduce the computational complexity, equal power allocation is proposed. Lastly, the experimental results show the proposed resource allocation scheme can obtain a higher secrecy rate than traditional schemes. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessReview Surround by Sound: A Review of Spatial Audio Recording and Reproduction
Appl. Sci. 2017, 7(5), 532; https://doi.org/10.3390/app7050532
Received: 14 March 2017 / Revised: 9 May 2017 / Accepted: 11 May 2017 / Published: 20 May 2017
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Abstract
In this article, a systematic overview of various recording and reproduction techniques for spatial audio is presented. While binaural recording and rendering is designed to resemble the human two-ear auditory system and reproduce sounds specifically for a listener’s two ears, soundfield recording and
[...] Read more.
In this article, a systematic overview of various recording and reproduction techniques for spatial audio is presented. While binaural recording and rendering is designed to resemble the human two-ear auditory system and reproduce sounds specifically for a listener’s two ears, soundfield recording and reproduction using a large number of microphones and loudspeakers replicate an acoustic scene within a region. These two fundamentally different types of techniques are discussed in the paper. A recent popular area, multi-zone reproduction, is also briefly reviewed in the paper. The paper is concluded with a discussion of the current state of the field and open problems. Full article
(This article belongs to the Special Issue Spatial Audio) Printed Edition available
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Open AccessReview Molecular Dynamics of XFEL-Induced Photo-Dissociation, Revealed by Ion-Ion Coincidence Measurements
Appl. Sci. 2017, 7(5), 531; https://doi.org/10.3390/app7050531
Received: 24 March 2017 / Revised: 25 April 2017 / Accepted: 12 May 2017 / Published: 19 May 2017
Cited by 2 | PDF Full-text (3016 KB) | HTML Full-text | XML Full-text
Abstract
X-ray free electron lasers (XFELs) providing ultrashort intense pulses of X-rays have proven to be excellent tools to investigate the dynamics of radiation-induced dissociation and charge redistribution in molecules and nanoparticles. Coincidence techniques, in particular multi-ion time-of-flight (TOF) coincident experiments, can provide detailed
[...] Read more.
X-ray free electron lasers (XFELs) providing ultrashort intense pulses of X-rays have proven to be excellent tools to investigate the dynamics of radiation-induced dissociation and charge redistribution in molecules and nanoparticles. Coincidence techniques, in particular multi-ion time-of-flight (TOF) coincident experiments, can provide detailed information on the photoabsorption, charge generation, and Coulomb explosion events. Here we review several such recent experiments performed at the SPring-8 Angstrom Compact free electron LAser (SACLA) facility in Japan, with iodomethane, diiodomethane, and 5-iodouracil as targets. We demonstrate how to utilize the momentum-resolving capabilities of the ion TOF spectrometers to resolve and filter the coincidence data and extract various information essential in understanding the time evolution of the processes induced by the XFEL pulses. Full article
(This article belongs to the Special Issue X-Ray Free-Electron Laser) Printed Edition available
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Open AccessArticle Innovation of New Occlusion Devices for Cancers
Appl. Sci. 2017, 7(5), 530; https://doi.org/10.3390/app7050530
Received: 24 March 2017 / Revised: 27 April 2017 / Accepted: 9 May 2017 / Published: 19 May 2017
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Abstract
Liver cancer, a life-threatening disease, can be cured if found early. A common treatment for liver tumors that cannot be removed by surgery is hepatic artery embolization. It involves injecting small beads to block the blood flow towards cancer cells. In this paper,
[...] Read more.
Liver cancer, a life-threatening disease, can be cured if found early. A common treatment for liver tumors that cannot be removed by surgery is hepatic artery embolization. It involves injecting small beads to block the blood flow towards cancer cells. In this paper, we propose the world’s first nitinol spherical occlusion device, which can be deployed in the upstream of an artery to reduce the blood flow to the downstream cancer cells. Finite element models were developed to predict the device’s mechanical integrity during manufacturing and deployment. Computational fluid dynamics were applied to simulate the device’s clinical occlusion performance. Simulation results suggested that devices with a metal density of 14–27% would reduce the average blood flow rate by 30–50%. A conceptual prototype was first cut by pulsed-fiber optic laser, and a series of expansions and heat treatments were used to shape the device to its final geometry. Flow experiments were conducted for proof of concept, and results showed that the spherical occlusion device successfully reduced the flow as designed. The occlusion device with the metal density of 27% was able to reduce 44% of flow, which agreed well with the simulation results. Full article
(This article belongs to the Special Issue Selected Papers from the 2016 International Conference on Inventions)
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Open AccessArticle X-ray Pump–Probe Investigation of Charge and Dissociation Dynamics in Methyl Iodine Molecule
Appl. Sci. 2017, 7(5), 529; https://doi.org/10.3390/app7050529
Received: 26 April 2017 / Revised: 15 May 2017 / Accepted: 15 May 2017 / Published: 19 May 2017
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Abstract
Molecular dynamics is of fundamental interest in natural science research. The capability of investigating molecular dynamics is one of the various motivations for ultrafast optics. We present our investigation of photoionization and nuclear dynamics in methyl iodine (CH3I) molecule with an
[...] Read more.
Molecular dynamics is of fundamental interest in natural science research. The capability of investigating molecular dynamics is one of the various motivations for ultrafast optics. We present our investigation of photoionization and nuclear dynamics in methyl iodine (CH3I) molecule with an X-ray pump X-ray probe scheme. The pump–probe experiment was realized with a two-mirror X-ray split and delay apparatus. Time-of-flight mass spectra at various pump–probe delay times were recorded to obtain the time profile for the creation of high charge states via sequential ionization and for molecular dissociation. We observed high charge states of atomic iodine up to 29+, and visualized the evolution of creating these high atomic ion charge states, including their population suppression and enhancement as the arrival time of the second X-ray pulse was varied. We also show the evolution of the kinetics of the high charge states upon the timing of their creation during the ionization-dissociation coupled dynamics. We demonstrate the implementation of X-ray pump–probe methodology for investigating X-ray induced molecular dynamics with femtosecond temporal resolution. The results indicate the footprints of ionization that lead to high charge states, probing the long-range potential curves of the high charge states. Full article
(This article belongs to the Special Issue X-Ray Free-Electron Laser) Printed Edition available
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Open AccessArticle Artwork Identification for 360-Degree Panoramic Images Using Polyhedron-Based Rectilinear Projection and Keypoint Shapes
Appl. Sci. 2017, 7(5), 528; https://doi.org/10.3390/app7050528
Received: 24 February 2017 / Revised: 29 April 2017 / Accepted: 17 May 2017 / Published: 19 May 2017
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Abstract
With the increased development of 360-degree production technologies, artwork has recently been photographed without authorization. To prevent this infringement, we propose an artwork identification methodology for 360-degree images. We transform the 360-degree image into a three-dimensional sphere and wrap it with a polyhedron.
[...] Read more.
With the increased development of 360-degree production technologies, artwork has recently been photographed without authorization. To prevent this infringement, we propose an artwork identification methodology for 360-degree images. We transform the 360-degree image into a three-dimensional sphere and wrap it with a polyhedron. On the sphere, several points are located on the polyhedron to determine the width, height, and direction of the rectilinear projection. The 360-degree image is divided and transformed into several rectilinear projected images to reduce the adverse effects from the distorted panoramic image. We also propose a method for improving the identification precision of artwork located at a highly distorted position using the difference of keypoint shapes. After applying the proposed methods, identification precision is increased by 45% for artwork that is displayed on a 79-inch monitor in a seriously distorted position with features that were generated by scale-invariant feature transformations. Full article
(This article belongs to the Special Issue Holography and 3D Imaging: Tomorrows Ultimate Experience)
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Open AccessArticle Probing Dynamics in Colloidal Crystals with Pump-Probe Experiments at LCLS: Methodology and Analysis
Appl. Sci. 2017, 7(5), 519; https://doi.org/10.3390/app7050519
Received: 4 April 2017 / Revised: 4 May 2017 / Accepted: 8 May 2017 / Published: 19 May 2017
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Abstract
We present results of the studies of dynamics in colloidal crystals performed by pump-probe experiments using an X-ray free-electron laser (XFEL). Colloidal crystals were pumped with an infrared laser at a wavelength of 800 nm with varying power and probed by XFEL pulses
[...] Read more.
We present results of the studies of dynamics in colloidal crystals performed by pump-probe experiments using an X-ray free-electron laser (XFEL). Colloidal crystals were pumped with an infrared laser at a wavelength of 800 nm with varying power and probed by XFEL pulses at an energy of 8 keV with a time delay up to 1000 ps. The positions of the Bragg peaks, and their radial and azimuthal widths were analyzed as a function of the time delay. The spectral analysis of the data did not reveal significant enhancement of frequencies expected in this experiment. This allowed us to conclude that the amplitude of vibrational modes excited in colloidal crystals was less than the systematic error caused by the noise level. Full article
(This article belongs to the Special Issue X-Ray Free-Electron Laser) Printed Edition available
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Open AccessArticle Application of Pulsed Laser-TIG Hybrid Heat Source in Root Welding of Thick Plate Titanium Alloys
Appl. Sci. 2017, 7(5), 527; https://doi.org/10.3390/app7050527
Received: 17 March 2017 / Revised: 23 April 2017 / Accepted: 26 April 2017 / Published: 18 May 2017
Cited by 4 | PDF Full-text (5328 KB) | HTML Full-text | XML Full-text
Abstract
Laser-TIG (tungsten inert gas) hybrid welding process is applied to produce stable back beads in the first layer during one-side multilayer welding. To explain why stable back beads can be formed, a comparison is conducted between single TIG and laser-TIG hybrid welding. Results
[...] Read more.
Laser-TIG (tungsten inert gas) hybrid welding process is applied to produce stable back beads in the first layer during one-side multilayer welding. To explain why stable back beads can be formed, a comparison is conducted between single TIG and laser-TIG hybrid welding. Results indicate that during laser action the arc column is enhanced and deflected to the keyhole, which changes the spatial distribution of plasma by strong attraction. The keyhole plasma possesses extreme electric conductivity. After laser action, the enhanced arc is restituted, the low energy density arc acts on the molten pool, and the bottom of the molten pool is solidified to prevent its collapse. The heat and force are redistributed over the top of molten pool under the alternative action of the enhanced arc and original arc. In this case the thermal distribution and mechanical situation in the molten pool must be more balanced and reasonable, and the back bead appearance is continuous, stable and uniform. This process gives high quality and efficient root welding of the thick plate. Full article
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Open AccessArticle Combined Operation of Electrical Loads, Air Conditioning and Photovoltaic-Battery Systems in Smart Houses
Appl. Sci. 2017, 7(5), 525; https://doi.org/10.3390/app7050525
Received: 11 April 2017 / Revised: 9 May 2017 / Accepted: 11 May 2017 / Published: 18 May 2017
Cited by 2 | PDF Full-text (4745 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a novel Energy Management System (EMS) is proposed for a hybrid energy system with photovoltaic (PV) and energy storage system for a smart house. The EMS is designed to control the shiftable loads, the air conditioning and the electric storage
[...] Read more.
In this paper, a novel Energy Management System (EMS) is proposed for a hybrid energy system with photovoltaic (PV) and energy storage system for a smart house. The EMS is designed to control the shiftable loads, the air conditioning and the electric storage system. The aim is to reduce the electrical energy consumption cost without compromising the end-user comfort. Monte Carlo Simulation (MCS) is used to estimate the optimal size of the hybrid system considering energy saving and investment costs. Simulations results confirm the effectiveness of the proposed EMS in decreasing the electrical energy consumption and costs. The proposed method for the sizing of the hybrid system is also able to select the best size of the PV-battery system in smart houses. Full article
(This article belongs to the Special Issue Smart Home and Energy Management Systems)
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Open AccessReview Adhesion Promoters in Bituminous Road Materials: A Review
Appl. Sci. 2017, 7(5), 524; https://doi.org/10.3390/app7050524
Received: 19 April 2017 / Revised: 10 May 2017 / Accepted: 15 May 2017 / Published: 18 May 2017
Cited by 4 | PDF Full-text (996 KB) | HTML Full-text | XML Full-text
Abstract
This review focuses on certain classes of organic compounds known variously in the specific literature of asphalt as adhesion promoters, antistripping agents, wetting agents, antistrips, or adhesion agents. These kinds of organic additives are currently formulated to enhance the bitumen coating of mineral
[...] Read more.
This review focuses on certain classes of organic compounds known variously in the specific literature of asphalt as adhesion promoters, antistripping agents, wetting agents, antistrips, or adhesion agents. These kinds of organic additives are currently formulated to enhance the bitumen coating of mineral aggregates and improve the workability of asphalt mixtures. In this review, the term “adhesion promoters” includes both synthetic organic compounds as well as those extracted from natural resources, mixed in trace amounts to bitumen. Their main role is to alter the interfacial energy, so that the presence of water, even in trace, does not weaken the bitumen-aggregate bond and tends to favor adhesion. The report also considers the chemical functionalities that play a predominant role in bonding, as well as the effects of surface modification of the aggregate due to the presence of adhesion promoters in pre-blended bituminous mixtures. Although bitumen is widely used in road pavement construction and the discussion is mainly addressed to the improvement of adhesion in road materials, adhesion and wetting properties can also represent a general issue in various bitumen-based industrial products. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Intensified Pozzolanic Reaction on Kaolinite Clay-Based Mortar
Appl. Sci. 2017, 7(5), 522; https://doi.org/10.3390/app7050522
Received: 20 February 2017 / Revised: 12 May 2017 / Accepted: 16 May 2017 / Published: 18 May 2017
Cited by 5 | PDF Full-text (5758 KB) | HTML Full-text | XML Full-text
Abstract
The objective of this study is to develop and characterize kaolinite clay-based structural mortar. The pozzolanic reaction induced from two mineral additives, i.e., calcium hydroxide and silica fume (SF), and the physical filling effect from SF, were found to be effective on the
[...] Read more.
The objective of this study is to develop and characterize kaolinite clay-based structural mortar. The pozzolanic reaction induced from two mineral additives, i.e., calcium hydroxide and silica fume (SF), and the physical filling effect from SF, were found to be effective on the enhancement of structural properties. Based on several preliminary experiments, 7:3 ratio of kaolinite clay/calcium hydroxide was selected as a basic binder. Then, the amount of SF was chosen as 0%, 7.5%, and 15% of the total binder to consider both the chemical and physical effects. The results showed that compressive strengths of samples with 7.5% and 15% SF are significantly increased by approximately 200% and 350%, respectively, at 28 days compared to the sample without SF. However, based on the results of the sample with 15% SF, it is found that excessive addition of SF causes long-term strength loss, possibly owing to micro cracks. With the careful consideration on this long-term behavior, this suggested new mix design can be further extended to develop sustainable structural materials using natural minerals or waste materials with nonbinding properties. Full article
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Open AccessArticle Human-Like Walking with Heel Off and Toe Support for Biped Robot
Appl. Sci. 2017, 7(5), 499; https://doi.org/10.3390/app7050499
Received: 31 March 2017 / Revised: 4 May 2017 / Accepted: 5 May 2017 / Published: 18 May 2017
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Abstract
The under-actuated foot rotation that the heel of the stance leg lifts off the ground and the body rotates around the stance toe is an important feature in human walking. However, it is absent in the realized walking gait for the majority of
[...] Read more.
The under-actuated foot rotation that the heel of the stance leg lifts off the ground and the body rotates around the stance toe is an important feature in human walking. However, it is absent in the realized walking gait for the majority of biped robots because of the difficulty and complexity in the control it brings about. In this paper, a hybrid control approach aiming to integrate the main characteristics of human walking into a simulated seven-link biped robot is presented and then verified with simulations. The bipedal robotic gait includes a fully actuated single support phase with the stance heel supporting the body, an under-actuated single support phase, with the stance toe supporting the body, and an instantaneous double support phase when the two legs exchange their roles. The walking controller combines virtual force control and foot placement control, which are applied to the stance leg and the swing leg, respectively. The virtual force control assumes that there is a virtual force which can generate the desired torso motion on the center of mass of the torso link, and then the virtual force is applied through the real torques on each actuated joint of the stance leg to create the same effect that the virtual force would have created. The foot placement control uses a path tracking controller to follow the predefined trajectory of the swing foot when walking forward. The trajectories of the torso and the swing foot are generated based on the cart-cable model. Co-simulations in Adams and MATLAB show that the desired gait is achieved with a biped robot under the action of the proposed method. Full article
(This article belongs to the Special Issue Bio-Inspired Robotics)
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Open AccessReview The Role of the Cerebellum in Unconscious and Conscious Processing of Emotions: A Review
Appl. Sci. 2017, 7(5), 521; https://doi.org/10.3390/app7050521
Received: 30 January 2017 / Revised: 9 May 2017 / Accepted: 12 May 2017 / Published: 17 May 2017
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Abstract
Studies from the past three decades have demonstrated that there is cerebellar involvement in the emotional domain. Emotional processing in humans requires both unconscious and conscious mechanisms. A significant amount of evidence indicates that the cerebellum is one of the cerebral structures that
[...] Read more.
Studies from the past three decades have demonstrated that there is cerebellar involvement in the emotional domain. Emotional processing in humans requires both unconscious and conscious mechanisms. A significant amount of evidence indicates that the cerebellum is one of the cerebral structures that subserve emotional processing, although conflicting data has been reported on its function in unconscious and conscious mechanisms. This review discusses the available clinical, neuroimaging, and neurophysiological data on this issue. We also propose a model in which the cerebellum acts as a mediator between the internal state and external environment for the unconscious and conscious levels of emotional processing. Full article
(This article belongs to the Special Issue Sub- and Unconscious Information Processing in the Human Brain)
Open AccessArticle An Efficient Compensation Method for Limited-View Photoacoustic Imaging Reconstruction Based on Gerchberg–Papoulis Extrapolation
Appl. Sci. 2017, 7(5), 505; https://doi.org/10.3390/app7050505
Received: 29 March 2017 / Revised: 8 May 2017 / Accepted: 9 May 2017 / Published: 17 May 2017
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Abstract
The reconstruction for limited-view scanning, though often the case in practice, has remained a difficult issue for photoacoustic imaging (PAI). The incompleteness of sampling data will cause serious artifacts and fuzziness in those missing views and it will heavily affect the quality of
[...] Read more.
The reconstruction for limited-view scanning, though often the case in practice, has remained a difficult issue for photoacoustic imaging (PAI). The incompleteness of sampling data will cause serious artifacts and fuzziness in those missing views and it will heavily affect the quality of the image. To solve the problem of limited-view PAI, a compensation method based on the Gerchberg–Papoulis (GP) extrapolation is applied into PAI. Based on the known data, missing detectors elements are estimated and the image in the missing views is then compensated using the Fast Fourier Transform (FFT). To accelerate the convergence speed of the algorithm, the total variation (TV)-based iterative algorithm is incorporated into the GP extrapolation-based FFT-utilized compensation method (TV-GPEF). The effective variable splitting and Barzilai–Borwein based method is adopted to solve the optimization problem. Simulations and in vitro experiments for both limited-angle circular scanning and straight-line scanning are conducted to validate the proposed algorithm. Results show that the proposed algorithm can greatly suppress the artifacts caused by the missing views and enhance the edges and the details of the image. It can be indicated that the proposed TV-GPEF algorithm is efficient for limited-view PAI. Full article
(This article belongs to the Special Issue Biomedical Photoacoustic and Thermoacoustic Imaging)
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Open AccessArticle Swirling Gas Jet-Assisted Laser Trepanning for a Galvanometer-Scanned CO2 Laser
Appl. Sci. 2017, 7(5), 502; https://doi.org/10.3390/app7050502
Received: 24 March 2017 / Revised: 30 April 2017 / Accepted: 6 May 2017 / Published: 17 May 2017
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Abstract
Laser-drilled hole arrays are part of an important field that aim to improve efficiency without affecting the quality of laser-drilled holes. In this paper, a swirling gas jet was implemented to assist with laser trepanning for a galvanometer scanned CO2 laser. The
[...] Read more.
Laser-drilled hole arrays are part of an important field that aim to improve efficiency without affecting the quality of laser-drilled holes. In this paper, a swirling gas jet was implemented to assist with laser trepanning for a galvanometer scanned CO2 laser. The proposed swirling gas jet is based on laser trepanning. This swirling gas jet nozzle was composed of four inlet tubes to produce the flow of the vortex. Then, the plume particles were excluded, and spatter on the surface of the workpiece decreased. Thus, this approach can mitigate the problem of overcooling. This study manipulated the appropriate parameter settings, which were simulated by computational fluid dynamics software ANSYS CFX. The proposed swirling gas jet can be used with galvanometer-based scanner systems to keep the laser beam from interference by spatter. In addition, a hollow position of the vortex was achieved by using the four inlet tubes, which resulted in pressure asymmetry in the nozzle and velocity distribution on the surface of the workpiece. The experiment verified that the depth of processing could be enhanced by 110% when trepanning at a scanning speed of 30 mm/s, and that the removal of volume could be enhanced by 71% in trepanning at a diameter of 1 mm by using a swirl assistant compared with a non-assisted condition. Furthermore, the material removal rate of the swirling jet increases when the machining area of the galvanometer-based scanner is larger. Full article
(This article belongs to the Special Issue Selected Papers from the 2016 International Conference on Inventions)
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Open AccessFeature PaperArticle Construction and Commissioning of PAL-XFEL Facility
Appl. Sci. 2017, 7(5), 479; https://doi.org/10.3390/app7050479
Received: 23 March 2017 / Revised: 20 April 2017 / Accepted: 26 April 2017 / Published: 17 May 2017
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Abstract
The construction of Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL), a 0.1-nm hard X-ray free-electron laser (FEL) facility based on a 10-GeV S-band linear accelerator (LINAC), is achieved in Pohang, Korea by the end of 2016. The construction of the 1.11 km-long building
[...] Read more.
The construction of Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL), a 0.1-nm hard X-ray free-electron laser (FEL) facility based on a 10-GeV S-band linear accelerator (LINAC), is achieved in Pohang, Korea by the end of 2016. The construction of the 1.11 km-long building was completed by the end of 2014, and the installation of the 10-GeV LINAC and undulators started in January 2015. The installation of the 10-GeV LINAC, together with the undulators and beamlines, was completed by the end of 2015. The commissioning began in April 2016, and the first lasing of the hard X-ray FEL line was achieved on 14 June 2016. The progress of the PAL-XFEL construction and its commission are reported here. Full article
(This article belongs to the Special Issue X-Ray Free-Electron Laser) Printed Edition available
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Open AccessArticle Fire Damage Assessment of Reinforced Concrete Structures Using Fuzzy Theory
Appl. Sci. 2017, 7(5), 518; https://doi.org/10.3390/app7050518
Received: 30 March 2017 / Revised: 4 May 2017 / Accepted: 9 May 2017 / Published: 16 May 2017
Cited by 2 | PDF Full-text (5271 KB) | HTML Full-text | XML Full-text
Abstract
Once a reinforced concrete (RC) structure is damaged by fire, the fire damage assessment should proceed to take appropriate post-fire actions, including the decision-making of whether it can be repaired for reuse or not. Since the assessment results of current fire damage diagnosis
[...] Read more.
Once a reinforced concrete (RC) structure is damaged by fire, the fire damage assessment should proceed to take appropriate post-fire actions, including the decision-making of whether it can be repaired for reuse or not. Since the assessment results of current fire damage diagnosis methods, however, highly depend on the subjective judgment of inspectors, it is hard to ensure their objectiveness and reliability. This study, therefore, aims to develop a new fire damage diagnosis system (FDDS) based on fuzzy theory that can provide objective and comprehensive evaluation results by considering all of the damage conditions observed from the inspection on RC structural members exposed to fire. In addition, the FDDS was applied to an actual fire-damaged case reported by the Architectural Institute of Japan (AIJ, 2009), and it appears that the proposed method provides a reasonable estimation on the fire damage grade of the fire-damaged RC members. Full article
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Open AccessFeature PaperConcept Paper Sintering of Two Viscoelastic Particles: A Computational Approach
Appl. Sci. 2017, 7(5), 516; https://doi.org/10.3390/app7050516
Received: 31 March 2017 / Revised: 2 May 2017 / Accepted: 10 May 2017 / Published: 16 May 2017
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Abstract
Selective laser sintering (SLS) is a high-resolution additive manufacturing fabrication technique. To fully understand the process, we developed a computational model, using the finite element method, to solve the flow problem of sintering two viscoelastic particles. The flow is assumed to be isothermal
[...] Read more.
Selective laser sintering (SLS) is a high-resolution additive manufacturing fabrication technique. To fully understand the process, we developed a computational model, using the finite element method, to solve the flow problem of sintering two viscoelastic particles. The flow is assumed to be isothermal and the particles to be in a liquid state, where their rheology is described using the Giesekus and XPP constitutive models. In this work, we assess the parameters that define this problem, such as the initial geometry, the Deborah number and other dimensionless parameters present in the rheological models. In particular, the conformation tensor is considered, which is a measure for the polymeric strain and plays an important role in the crystallization kinetics of semicrystalline polymers like polyamide 12, usually used in SLS. Full article
(This article belongs to the Special Issue Materials for 3D Printing)
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Open AccessFeature PaperArticle Detection of Pitting in Gears Using a Deep Sparse Autoencoder
Appl. Sci. 2017, 7(5), 515; https://doi.org/10.3390/app7050515
Received: 15 March 2017 / Revised: 5 May 2017 / Accepted: 12 May 2017 / Published: 16 May 2017
Cited by 3 | PDF Full-text (4238 KB) | HTML Full-text | XML Full-text
Abstract
In this paper; a new method for gear pitting fault detection is presented. The presented method is developed based on a deep sparse autoencoder. The method integrates dictionary learning in sparse coding into a stacked autoencoder network. Sparse coding with dictionary learning is
[...] Read more.
In this paper; a new method for gear pitting fault detection is presented. The presented method is developed based on a deep sparse autoencoder. The method integrates dictionary learning in sparse coding into a stacked autoencoder network. Sparse coding with dictionary learning is viewed as an adaptive feature extraction method for machinery fault diagnosis. An autoencoder is an unsupervised machine learning technique. A stacked autoencoder network with multiple hidden layers is considered to be a deep learning network. The presented method uses a stacked autoencoder network to perform the dictionary learning in sparse coding and extract features from raw vibration data automatically. These features are then used to perform gear pitting fault detection. The presented method is validated with vibration data collected from gear tests with pitting faults in a gearbox test rig and compared with an existing deep learning-based approach. Full article
(This article belongs to the Special Issue Deep Learning Based Machine Fault Diagnosis and Prognosis)
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Open AccessArticle Development of Green Geopolymer Using Agricultural and Industrial Waste Materials with High Water Absorbency
Appl. Sci. 2017, 7(5), 514; https://doi.org/10.3390/app7050514
Received: 21 February 2017 / Revised: 17 April 2017 / Accepted: 18 April 2017 / Published: 16 May 2017
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Abstract
Geopolymer is a promising porous material that can be used for evaporative cooling applications. Developing a greener geopolymer using agricultural and industrial wastes is a promising research area. In this study, we utilize rice husk (RH), rice husk ash (RHA), metakaolin (MK), ground
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Geopolymer is a promising porous material that can be used for evaporative cooling applications. Developing a greener geopolymer using agricultural and industrial wastes is a promising research area. In this study, we utilize rice husk (RH), rice husk ash (RHA), metakaolin (MK), ground granulated blast furnace slag (GGBS), and palm oil fuel ash (POFA) to prepare geopolymer pastes, with alkali liquid as an activator. Many geopolymer samples have been prepared as per the Design of Experimental software (DOE), and its corresponding response surface mode and central composite design and later they were characterized. The samples were cured in an oven for 2 h at 80 °C, and thereafter stored at room temperature (~25–30 °C) prior to being tested for its water absorption and compressive strength. The effect of the different composition of precursors on water absorption, density, porosity, and the compressive strength of the prepared geopolymers have been investigated. The results showed that the compressive strength of geopolymers is directly proportional to the ratio of the alkali liquid. Post-optimization, the best geopolymer paste mixture was confirmed to contain 10% of RH, 15% RHA, 35% MK, 10% POFA and 30% of GGBS, with 72% desirability for maximum water absorption (~38%) and compressive strength (4.9 MPa). The results confirmed its applicability for evaporative cooling. Full article
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Open AccessArticle Advanced Emergency Braking Control Based on a Nonlinear Model Predictive Algorithm for Intelligent Vehicles
Appl. Sci. 2017, 7(5), 504; https://doi.org/10.3390/app7050504
Received: 31 December 2016 / Revised: 1 May 2017 / Accepted: 8 May 2017 / Published: 16 May 2017
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Abstract
Focusing on safety, comfort and with an overall aim of the comprehensive improvement of a vision-based intelligent vehicle, a novel Advanced Emergency Braking System (AEBS) is proposed based on Nonlinear Model Predictive Algorithm. Considering the nonlinearities of vehicle dynamics, a vision-based longitudinal vehicle
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Focusing on safety, comfort and with an overall aim of the comprehensive improvement of a vision-based intelligent vehicle, a novel Advanced Emergency Braking System (AEBS) is proposed based on Nonlinear Model Predictive Algorithm. Considering the nonlinearities of vehicle dynamics, a vision-based longitudinal vehicle dynamics model is established. On account of the nonlinear coupling characteristics of the driver, surroundings, and vehicle itself, a hierarchical control structure is proposed to decouple and coordinate the system. To avoid or reduce the collision risk between the intelligent vehicle and collision objects, a coordinated cost function of tracking safety, comfort, and fuel economy is formulated. Based on the terminal constraints of stable tracking, a multi-objective optimization controller is proposed using the theory of non-linear model predictive control. To quickly and precisely track control target in a finite time, an electronic brake controller for AEBS is designed based on the Nonsingular Fast Terminal Sliding Mode (NFTSM) control theory. To validate the performance and advantages of the proposed algorithm, simulations are implemented. According to the simulation results, the proposed algorithm has better integrated performance in reducing the collision risk and improving the driving comfort and fuel economy of the smart car compared with the existing single AEBS. Full article
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Open AccessFeature PaperArticle On the Visualization of Gas Metal Arc Welding Plasma and the Relationship Between Arc Length and Voltage
Appl. Sci. 2017, 7(5), 503; https://doi.org/10.3390/app7050503
Received: 18 March 2017 / Revised: 25 April 2017 / Accepted: 9 May 2017 / Published: 15 May 2017
Cited by 1 | PDF Full-text (2696 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this article, the camera settings for high-speed imaging of the arc, metal transfer, and weld pool in gas metal arc welding (GMAW) are investigated. The results show that by only changing camera exposure times and the selection of narrow bandpass filters, images
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In this article, the camera settings for high-speed imaging of the arc, metal transfer, and weld pool in gas metal arc welding (GMAW) are investigated. The results show that by only changing camera exposure times and the selection of narrow bandpass filters, images that reveal features of the arc such as the iron vapor-dominated region, metal transfer and weld pool behavior can be produced without the need for external light sources. Using the images acquired, the arc length was measured and the relationship between arc length and arc voltage is discussed. The results show that for low values of current, the measured welding voltage increases with increasing arc length; however, for high current values, the arc voltage increases even though the measured arc length becomes shorter. It is suggested that the increase in arc voltage for high values of welding current is due to the increased evaporation of the wire electrode which decreases the plasma temperature and consequently the arc plasma electrical conductivity. Full article
(This article belongs to the Special Issue Gas Metal Arc Welding)
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Open AccessArticle A Fast Motion Parameters Estimation Method Based on Cross-Correlation of Adjacent Echoes for Wideband LFM Radars
Appl. Sci. 2017, 7(5), 500; https://doi.org/10.3390/app7050500
Received: 15 April 2017 / Revised: 7 May 2017 / Accepted: 9 May 2017 / Published: 15 May 2017
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Abstract
In wideband radar systems, the performance of motion parameters estimation can significantly affect the performance of object detection and the quality of inverse synthetic aperture radar (ISAR) imaging. Although the traditional motion parameters estimation methods can reduce the range migration (RM) and Doppler
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In wideband radar systems, the performance of motion parameters estimation can significantly affect the performance of object detection and the quality of inverse synthetic aperture radar (ISAR) imaging. Although the traditional motion parameters estimation methods can reduce the range migration (RM) and Doppler frequency migration (DFM) effects in ISAR imaging, the computational complexity is high. In this paper, we propose a new fast non-parameter-searching method for motion parameters estimation based on the cross-correlation of adjacent echoes (CCAE) for wideband LFM signals. A cross-correlation operation is carried out for two adjacent echo signals, then the motion parameters can be calculated by estimating the frequency of the correlation result. The proposed CCAE method can be applied directly to the stretching system, which is commonly adopted in wideband radar systems. Simulation results demonstrate that the new method can achieve better estimation performances, with much lower computational cost, compared with existing methods. The experimental results on real radar datasets are also evaluated to verify the effectiveness and superiority of the proposed method compared to the state-of-the-art existing methods. Full article
(This article belongs to the Special Issue Selected Papers from IEEE ICASI 2017)
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Open AccessArticle Facile Synthesis of α-MnO2 with a 3D Staghorn Coral-like Micro-Structure Assembled by Nano-Rods and Its Application in Electrochemical Supercapacitors
Appl. Sci. 2017, 7(5), 511; https://doi.org/10.3390/app7050511
Received: 22 March 2017 / Revised: 20 April 2017 / Accepted: 11 May 2017 / Published: 13 May 2017
PDF Full-text (3513 KB) | HTML Full-text | XML Full-text
Abstract
Abstract: Manganese oxides with an alpha crystal structure are synthesized via combined solid-state reaction and wet chemical processing, which is a simple and inexpensive synthetic route easy for mass production. The effects of the synthetic reaction duration and the temperature of acid
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Abstract: Manganese oxides with an alpha crystal structure are synthesized via combined solid-state reaction and wet chemical processing, which is a simple and inexpensive synthetic route easy for mass production. The effects of the synthetic reaction duration and the temperature of acid treatments on crystal structure, morphology, and electrochemical capacitive properties of α-MnO2 are discussed. It is evidenced that the samples treated in acid for a longer time at 25 °C display the uniform nanorods that are aggregated to form micro-buildings with fine features on the surface of rods. This microstructure possesses large surface areas and more active sites that are easy to access electrochemically, leading to a better electrochemical capacitive performance. We expected that these results would provide the practical information for shape- and morphology-controlled synthesis for nanostructured functional materials in supercapacitor applications. Full article
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Open AccessReview A State of the Art Review of Modal-Based Damage Detection in Bridges: Development, Challenges, and Solutions
Appl. Sci. 2017, 7(5), 510; https://doi.org/10.3390/app7050510
Received: 1 April 2017 / Revised: 4 May 2017 / Accepted: 9 May 2017 / Published: 13 May 2017
Cited by 2 | PDF Full-text (316 KB) | HTML Full-text | XML Full-text
Abstract
Traditionally, damage identification techniques in bridges have focused on monitoring changes to modal-based Damage Sensitive Features (DSFs) due to their direct relationship with structural stiffness and their spatial information content. However, their progression to real-world applications has not been without its challenges and
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Traditionally, damage identification techniques in bridges have focused on monitoring changes to modal-based Damage Sensitive Features (DSFs) due to their direct relationship with structural stiffness and their spatial information content. However, their progression to real-world applications has not been without its challenges and shortcomings, mainly stemming from: (1) environmental and operational variations; (2) inefficient utilization of machine learning algorithms for damage detection; and (3) a general over-reliance on modal-based DSFs alone. The present paper provides an in-depth review of the development of modal-based DSFs and a synopsis of the challenges they face. The paper then sets out to addresses the highlighted challenges in terms of published advancements and alternatives from recent literature. Full article
Open AccessArticle Immobilized TiO2-Polyethylene Glycol: Effects of Aeration and pH of Methylene Blue Dye
Appl. Sci. 2017, 7(5), 508; https://doi.org/10.3390/app7050508
Received: 24 February 2017 / Revised: 2 May 2017 / Accepted: 4 May 2017 / Published: 12 May 2017
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Abstract
Immobilized TiO2 and immobilized TiO2-polyethylene glycol (TiO2/PEG) films have been prepared via brush coating method. The formulation of immobilized TiO2 film was prepared by mixing distilled water with P25, while the formulation containing P25 combined with 8%
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Immobilized TiO2 and immobilized TiO2-polyethylene glycol (TiO2/PEG) films have been prepared via brush coating method. The formulation of immobilized TiO2 film was prepared by mixing distilled water with P25, while the formulation containing P25 combined with 8% PEG in distilled water was used in preparing immobilized TiO2/PEG. A double sided adhesive tape (DSAT) was stacked onto a glass surface prior to coating with the formulations and annealing by a thermal treatment at 100 °C for 15 min. The photocatalytic activity of immobilized photocatalysts was evaluated under photodegradation of methylene blue (MB). It was observed that immobilized TiO2/PEG has showed a higher rate of photocatalytic activity compared to immobilize TiO2. The X-ray photoelectron spectroscopy and Fourier transform infrared (FT-IR) spectra of immobilized TiO2/PEG sample proved that the existence of C=O led to enhanced photoactivity efficiency under normal light and visible light irradiations. The photocatalytic activity performance of immobilized TiO2/PEG was the highest at 75 mL·min−1 aeration rate and pH 11 of MB dye. The correlation between of all these parameters was investigated in this study. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle A New Health Assessment Index of Tunnel Lining Based on the Digital Inspection of Surface Cracks
Appl. Sci. 2017, 7(5), 507; https://doi.org/10.3390/app7050507
Received: 28 March 2017 / Revised: 26 April 2017 / Accepted: 9 May 2017 / Published: 12 May 2017
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Abstract
The stability assessment of aged tunnel linings are mainly evaluated based on the visual inspection, and the Tunnel-lining Crack Index (TCI) is one of the most widely used tunnel lining health assessment indexes in Japan. However, the intersection and distribution of cracks, which
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The stability assessment of aged tunnel linings are mainly evaluated based on the visual inspection, and the Tunnel-lining Crack Index (TCI) is one of the most widely used tunnel lining health assessment indexes in Japan. However, the intersection and distribution of cracks, which could influence the stability of tunnel lining greatly, were not considered in TCI. A new method was proposed for the health assessment of tunnel lining, which evaluated the lining states according to the fractal dimension of cracks. Based on the machine vision-based method, the crack image could be extracted efficiently. The fractal dimension of lining cracks in one span could be obtained in a few minutes. A series of comparative tests and field tests were conducted to evaluate the validity of this new method. The comparative tests confirmed that fractal dimension was able to characterize the density, width, and distribution of cracks. The intersection of cracks, which would increase the risk of lining collapse, could also increase the fractal dimension. The fractal dimensions of tunnel lining cracks were obtained according to the digital inspection test of Hidake Tunnel in Japan for all the 65 spans. Moreover, the TCI was obtained through statistical methods. The correlation between fractal dimension and TCI of tunnel lining was studied. The significance of the new evaluation index is that it can identify the unusual spans of tunnel lining and provide a basis for further internal testing. As a complement to the conventional visual inspection method, the fractal dimension of the cracks is a promising health assessment index. Full article
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Open AccessArticle Design of a Binocular Pupil and Gaze Point Detection System Utilizing High Definition Images
Appl. Sci. 2017, 7(5), 498; https://doi.org/10.3390/app7050498
Received: 1 March 2017 / Revised: 4 May 2017 / Accepted: 8 May 2017 / Published: 11 May 2017
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Abstract
This study proposes a novel binocular pupil and gaze detection system utilizing a remote full high definition (full HD) camera and employing LabVIEW. LabVIEW is inherently parallel and has fewer time-consuming algorithms. Many eye tracker applications are monocular and use low resolution cameras
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This study proposes a novel binocular pupil and gaze detection system utilizing a remote full high definition (full HD) camera and employing LabVIEW. LabVIEW is inherently parallel and has fewer time-consuming algorithms. Many eye tracker applications are monocular and use low resolution cameras due to real-time image processing difficulties. We utilized the computer’s direct access memory channel for rapid data transmission and processed full HD images with LabVIEW. Full HD images make easier determinations of center coordinates/sizes of pupil and corneal reflection. We modified the camera so that the camera sensor passed only infrared (IR) images. Glints were taken as reference points for region of interest (ROI) area selection of the eye region in the face image. A morphologic filter was applied for erosion of noise, and a weighted average technique was used for center detection. To test system accuracy with 11 participants, we produced a visual stimulus set up to analyze each eye’s movement. Nonlinear mapping function was utilized for gaze estimation. Pupil size, pupil position, glint position and gaze point coordinates were obtained with free natural head movements in our system. This system also works at 2046 × 1086 resolution at 40 frames per second. It is assumed that 280 frames per second for 640 × 480 pixel images is the case. Experimental results show that the average gaze detection error for 11 participants was 0.76° for the left eye, 0.89° for right eye and 0.83° for the mean of two eyes. Full article
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Open AccessFeature PaperReview The State-of-the-Art on Framework of Vibration-Based Structural Damage Identification for Decision Making
Appl. Sci. 2017, 7(5), 497; https://doi.org/10.3390/app7050497
Received: 10 April 2017 / Revised: 2 May 2017 / Accepted: 4 May 2017 / Published: 11 May 2017
Cited by 6 | PDF Full-text (525 KB) | HTML Full-text | XML Full-text
Abstract
Research on detecting structural damage at the earliest possible stage has been an interesting topic for decades. Among them, the vibration-based damage detection method as a global technique is especially pervasive. The present study reviewed the state-of-the-art on the framework of vibration-based damage
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Research on detecting structural damage at the earliest possible stage has been an interesting topic for decades. Among them, the vibration-based damage detection method as a global technique is especially pervasive. The present study reviewed the state-of-the-art on the framework of vibration-based damage identification in different levels including the prediction of the remaining useful life of structures and the decision making for proper actions. This framework consists of several major parts including the detection of damage occurrence using response-based methods, building reasonable structural models, selecting damage parameters and constructing objective functions with sensitivity analysis, adopting optimization techniques to solve the problem, predicting the remaining useful life of structures, and making decisions for the next actions. For each part, the commonly used methods were reviewed and the merits and drawbacks were summarized to give recommendations. This framework is aimed to guide the researchers and engineers to implement step by step the structure damage identification using vibration measurements. Finally, the future research work in this field is recommended. Full article
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