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

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Cover Story (view full-size image) An overlay between Doppler Optical Coherence Tomography (Doppler OCT, color scale) and Optical [...] Read more.
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Open AccessArticle
Automatic Definition of an Anatomic Field of View for Volumetric Cardiac Motion Estimation at High Temporal Resolution
Appl. Sci. 2017, 7(7), 752; https://doi.org/10.3390/app7070752
Received: 7 June 2017 / Revised: 17 July 2017 / Accepted: 20 July 2017 / Published: 24 July 2017
Cited by 1 | Viewed by 1365 | PDF Full-text (2629 KB) | HTML Full-text | XML Full-text
Abstract
Fast volumetric cardiac imaging requires reducing the number of transmit events within a single volume. One way of achieving this is by limiting the field of view (FOV) of the recording to the myocardium when investigating cardiac mechanics. Although fully automatic solutions towards [...] Read more.
Fast volumetric cardiac imaging requires reducing the number of transmit events within a single volume. One way of achieving this is by limiting the field of view (FOV) of the recording to the myocardium when investigating cardiac mechanics. Although fully automatic solutions towards myocardial segmentation exist, translating that information in a fast ultrasound scan sequence is not trivial. In particular, multi-line transmit (MLT) scan sequences were investigated given their proven capability to increase frame rate (FR) while preserving image quality. The aim of this study was therefore to develop a methodology to automatically identify the anatomically relevant conically shaped FOV, and to translate this to the best associated MLT sequence. This approach was tested on 27 datasets leading to a conical scan with a mean opening angle of 19.7° ± 8.5°, while the mean “thickness” of the cone was 19° ± 3.4°, resulting in a frame rate gain of about 2. Then, to subsequently scan this conical volume, several MLT setups were tested in silico. The method of choice was a 10MLT sequence as it resulted in the highest frame rate gain while maintaining an acceptable cross-talk level. When combining this MLT scan sequence with at least four parallel receive beams, a total frame rate gain with a factor of approximately 80 could be obtained. As such, anatomical scan sequences can increase frame rate significantly while maintaining information of the relevant structures for functional myocardial imaging. Full article
(This article belongs to the Special Issue Ultrafast Ultrasound Imaging) Printed Edition available
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Open AccessArticle
Enhanced Adaptive Filtering Algorithm Based on Sliding Mode Control for Active Vibration Rejection of Smart Beam Structures
Appl. Sci. 2017, 7(7), 750; https://doi.org/10.3390/app7070750
Received: 3 July 2017 / Revised: 18 July 2017 / Accepted: 19 July 2017 / Published: 24 July 2017
Cited by 3 | Viewed by 1452 | PDF Full-text (7907 KB) | HTML Full-text | XML Full-text
Abstract
This article investigates vibration rejection for a continuous smart structure using piezoelectric bimorph patches. Such a structure has inherent nonlinearities, such as hysteresis and creep, and the whole system may experience unexpected disturbances, uncertainties, and noise from external sources. Thus, it is very [...] Read more.
This article investigates vibration rejection for a continuous smart structure using piezoelectric bimorph patches. Such a structure has inherent nonlinearities, such as hysteresis and creep, and the whole system may experience unexpected disturbances, uncertainties, and noise from external sources. Thus, it is very important to design the active control scheme carefully with adaptive filtering systems to deal with these conditions. An advanced adaptive filtering algorithm was developed based on the conventional least mean squares (LMS) method and sliding mode control for the active vibration rejection system. The sliding mode controller is applied to the standard LMS algorithm to overcome problems with misadjustment and excess error in an optimal manner. A numerical analysis and laboratory experiment show that the technique can significantly attenuate the vibration of the smart structure at different levels and broadband frequency spectra. In addition, unidentified impedance is chosen to change the distribution of the mass, and the robustness and the adaptivity of the proposed approach are verified. The experimental results show that the method can isolate impulse-type vibrations of at least 2.8 dB, even with the adjusted mass arrangement. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle
Ideal Operation of a Photovoltaic Power Plant Equipped with an Energy Storage System on Electricity Market
Appl. Sci. 2017, 7(7), 749; https://doi.org/10.3390/app7070749
Received: 22 June 2017 / Revised: 16 July 2017 / Accepted: 19 July 2017 / Published: 23 July 2017
Cited by 6 | Viewed by 1738 | PDF Full-text (4729 KB) | HTML Full-text | XML Full-text
Abstract
There is no natural inertia in a photovoltaic (PV) generator and changes in irradiation can be seen immediately at the output power. Moving cloud shadows are the dominant reason for fast PV power fluctuations taking place typically within a minute between 20 to [...] Read more.
There is no natural inertia in a photovoltaic (PV) generator and changes in irradiation can be seen immediately at the output power. Moving cloud shadows are the dominant reason for fast PV power fluctuations taking place typically within a minute between 20 to 100% of the clear sky value roughly 100 times a day, on average. Therefore, operating a utility scale grid connected PV power plant is challenging. Currently, in many regions, renewable energy sources such as solar and wind receive feed-in tariffs that ensure a certain price for the energy. On the other hand, electricity markets operate on a supply-demand principle and a typical imbalance settlement period is one hour. This paper presents the energy, power and corresponding requirements for an energy storage system in a solar PV power plant to feed the power to the grid meeting the electricity spot markets practices. An ideal PV energy production forecast is assumed to be available to define reference powers of the system for the studied imbalance settlement periods. The analysis is done for three different PV system sizes using the existing irradiance measurements of the Tampere University of Technology solar PV power station research plant. Full article
(This article belongs to the Special Issue Energy Saving)
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Open AccessArticle
A New Method for Haul Road Design in Open-Pit Mines to Support Efficient Truck Haulage Operations
Appl. Sci. 2017, 7(7), 747; https://doi.org/10.3390/app7070747
Received: 29 June 2017 / Revised: 14 July 2017 / Accepted: 20 July 2017 / Published: 23 July 2017
Cited by 2 | Viewed by 2659 | PDF Full-text (7122 KB) | HTML Full-text | XML Full-text
Abstract
The design of a haul road for an open-pit mine can significantly affect the cost associated with hauling ore and waste to the surface. This study proposes a new method for haul road design in open-pit mines to support efficient truck haulage operations. [...] Read more.
The design of a haul road for an open-pit mine can significantly affect the cost associated with hauling ore and waste to the surface. This study proposes a new method for haul road design in open-pit mines to support efficient truck haulage operations. The road layout in open-pit mines was optimized by using raster-based least-cost path analysis, and the resulting zigzag road sections were simplified by applying the Douglas-Peucker algorithm. In addition, the road layout was modified by reflecting the radius of curvature suggested in the road design guides. Finally, a three-dimensional model reflecting the results of the road design was created by combining the road layout modification result with the slope of the open-pit mine and the bench design result. The application of the proposed method to an area containing gold deposits made it possible to design a haul road for open-pit mines such that it supported efficient truck haulage operations; furthermore, the time required for truck movement along the road could be estimated. The proposed method is expected to be useful for planning and designing open-pit mines and to facilitate the improvement of the road design function of existing mining software applications. Full article
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Open AccessArticle
Aspect Ratio Evolution in Embedded, Surface, and Corner Cracks in Finite-Thickness Plates under Tensile Fatigue Loading
Appl. Sci. 2017, 7(7), 746; https://doi.org/10.3390/app7070746
Received: 28 April 2017 / Revised: 1 July 2017 / Accepted: 6 July 2017 / Published: 21 July 2017
Cited by 1 | Viewed by 1367 | PDF Full-text (2078 KB) | HTML Full-text | XML Full-text
Abstract
This article deals with the computational modelling of the fatigue crack aspect ratio evolution in embedded, surface, and corner cracks located in finite-thickness plates under tensile fatigue. The approach is based on the Paris law for fatigue propagation and an expression for the [...] Read more.
This article deals with the computational modelling of the fatigue crack aspect ratio evolution in embedded, surface, and corner cracks located in finite-thickness plates under tensile fatigue. The approach is based on the Paris law for fatigue propagation and an expression for the stress intensity factor (SIF) provided by Newman and Raju. Numerical results indicate that the crack path develops in such a manner that all flaws tend to reach similar aspect ratios, i.e., a preferential crack path does exist along which there is a one-to-one relationship between the aspect ratio and the relative crack depth (a sort of master curve in the matter of fatigue crack path evolution). Such a reference curve corresponds to that of a very superficial initial flaw with almost circular shape. The convergence (quicker or slower approach between fatigue crack paths starting from different initial defects) is higher for surface flaws than for corner cracks, and quicker for the latter than for embedded discontinuities. Corner defects increase their size faster than surface cracks, and the latter do the same quicker than the embedded ones. Full article
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Open AccessArticle
Study of Surfactant Additives for the Manufacture of Warm Mix Asphalt: From Laboratory Design to Asphalt Plant Manufacture
Appl. Sci. 2017, 7(7), 745; https://doi.org/10.3390/app7070745
Received: 20 June 2017 / Revised: 12 July 2017 / Accepted: 19 July 2017 / Published: 21 July 2017
Cited by 3 | Viewed by 1194 | PDF Full-text (2175 KB) | HTML Full-text | XML Full-text
Abstract
Warm Mix Asphalt (WMA), manufactured at a lower temperature than the traditional Hot Mix Asphalt (HMA), allows for important economic and environmental benefits when considered for application in roads. Nonetheless, despite the benefits, its application in pavement for roads is not as widespread [...] Read more.
Warm Mix Asphalt (WMA), manufactured at a lower temperature than the traditional Hot Mix Asphalt (HMA), allows for important economic and environmental benefits when considered for application in roads. Nonetheless, despite the benefits, its application in pavement for roads is not as widespread as desired from an environmental point of view; more in-depth studies to investigate its development and wider applicability are required. Thus, the present paper aims to contribute to the implementation of this cleaner technology to produce WMA (based on chemical additives) for its application in pavement for roads, including from the stage of the design of the material in the laboratory (by selecting the most appropriate manufacturing temperature and additive type and dosage) to its production in a conventional industrial plant for its use in a trial section. Results demonstrate that it is possible to reduce the manufacturing temperature of asphalt mixtures by using chemical additives, recording similar mechanical behaviour (or even superior) to conventional hot mixtures when specific studies are developed for the optimal design of the WMA. It was also shown that these mixtures could be produced in a conventional asphalt plant without implementing important changes in equipment, which implies a cost-effective solution that can readily be incorporated into traditional plant procedures. Full article
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Open AccessArticle
Performance Analysis of a Burst Transmission Mechanism Using Microsleep Operation for Green IEEE 802.11 WLANs
Appl. Sci. 2017, 7(7), 744; https://doi.org/10.3390/app7070744
Received: 16 June 2017 / Revised: 12 July 2017 / Accepted: 14 July 2017 / Published: 21 July 2017
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Abstract
This paper evaluates the performance of a burst transmission mechanism using microsleep operation to support high energy efficiency in IEEE 802.11 Wireless Local Area Networks (WLANs). This mechanism is an implementation of the IEEE 802.11ac Transmission Opportunity Power Save Mode (TXOP PSM). A [...] Read more.
This paper evaluates the performance of a burst transmission mechanism using microsleep operation to support high energy efficiency in IEEE 802.11 Wireless Local Area Networks (WLANs). This mechanism is an implementation of the IEEE 802.11ac Transmission Opportunity Power Save Mode (TXOP PSM). A device using the TXOP PSM-based mechanism can switch to a low-power sleep state for the time that another device transmits a burst of data frames to a third one. This operation is called microsleep and its feasibility strongly depends on the time and energy consumption that a device incurs in the transitions from and to the sleep state. This paper accounts for the impact of these transitions in the derivation of an analytical model to calculate the energy efficiency of the TXOP PSM-based mechanism under network saturation. Results obtained show that the impact of the transition requirements on the feasibility of microsleep operation can be significant depending on the selected system parameters, although it can be reduced by using burst transmissions. When microsleep operation is feasible, the TXOP PSM-based mechanism can improve the energy efficiency of other legacy mechanisms by up to 424% under high traffic loads. Full article
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Open AccessArticle
Laboratory Evaluation of Rejuvenating Agent on Reclaimed SBS Modified Asphalt Pavement
Appl. Sci. 2017, 7(7), 743; https://doi.org/10.3390/app7070743
Received: 13 June 2017 / Revised: 3 July 2017 / Accepted: 19 July 2017 / Published: 21 July 2017
Cited by 2 | Viewed by 1473 | PDF Full-text (9075 KB) | HTML Full-text | XML Full-text
Abstract
To evaluate the effect of rejuvenating agent on reclaimed SBS (styrene-butadiene-styrene) modified asphalt pavement (RSMAP) material, different tests of asphalt and mixtures were conducted. Firstly, the improvement effect of rejuvenating agents on the aged modified asphalt was tested at macroscopic and microscope level. [...] Read more.
To evaluate the effect of rejuvenating agent on reclaimed SBS (styrene-butadiene-styrene) modified asphalt pavement (RSMAP) material, different tests of asphalt and mixtures were conducted. Firstly, the improvement effect of rejuvenating agents on the aged modified asphalt was tested at macroscopic and microscope level. Then the properties of hot mix asphalt (HMA) with different RSMAP contents (0%, 30%, 50% and 70%) were evaluated by conducting freeze-thaw split, semi-circular bending (SCB) and dynamic modulus (DM). The results indicate that rejuvenating agent can recycle the properties of aged modified asphalt effectively. The initial phase structure of the aged modified asphalt is not changed by adding rejuvenating agents. Moreover, the SBS particles area ratio of modified asphalt blends is significantly correlated with tenacity as the proportion of rejuvenating agent increases. For mixtures, RSMAP is harmful to moisture susceptibility and low-temperature cracking resistance of recycled mixture, especially with high RSMAP content. Moreover, the two properties can be improved by adding rejuvenating agents, but the recycled mixtures with high RSMAP content are not easy to recover to HMA mixture level. In general, the rejuvenating agent has an effect on the stiffness of the recycled mixture, but this is effect not obvious. When loading frequency reaches a higher value, the DM of recycled mixtures and HMA mixture tend to be consistent including high RSMAP content. Full article
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Open AccessArticle
Cellular Automaton to Study the Impact of Changes in Traffic Rules in a Roundabout: A Preliminary Approach
Appl. Sci. 2017, 7(7), 742; https://doi.org/10.3390/app7070742
Received: 16 June 2017 / Revised: 16 July 2017 / Accepted: 18 July 2017 / Published: 21 July 2017
Cited by 6 | Viewed by 1800 | PDF Full-text (7227 KB) | HTML Full-text | XML Full-text
Abstract
The current article presents a roundabout traffic model based on cellular automata for computer simulation. The model takes into account various sizes of roundabouts, as well as various types and maximum speeds of vehicles. A realistic vehicle braking phase is presented which is [...] Read more.
The current article presents a roundabout traffic model based on cellular automata for computer simulation. The model takes into account various sizes of roundabouts, as well as various types and maximum speeds of vehicles. A realistic vehicle braking phase is presented which is adjusted to the kind of vehicle and weather conditions. It also analyses roundabout traffic options including where the various rules for entering and exiting a roundabout apply. Traffic rules are contained in respective traffic scenarios. The simulation results indicate that there is significant scope for roundabout traffic reorganisation, with a mind to increasing roundabout capacity. Full article
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Open AccessArticle
Application of Bender Elements Technique in Testing of Anthropogenic Soil—Recycled Concrete Aggregate and Its Mixture with Rubber Chips
Appl. Sci. 2017, 7(7), 741; https://doi.org/10.3390/app7070741
Received: 30 May 2017 / Revised: 10 July 2017 / Accepted: 17 July 2017 / Published: 21 July 2017
Cited by 2 | Viewed by 1141 | PDF Full-text (4926 KB) | HTML Full-text | XML Full-text
Abstract
This paper discusses the application of piezoceramic bender elements (BEs) for measurement of shear wave velocity in the time and frequency domain in a triaxial cell under different isotropic confinement. Different interpretation methods were used in the tests and their results were finally [...] Read more.
This paper discusses the application of piezoceramic bender elements (BEs) for measurement of shear wave velocity in the time and frequency domain in a triaxial cell under different isotropic confinement. Different interpretation methods were used in the tests and their results were finally compared with each other. Two types of anthropogenic material were tested: pure Recycled Concrete Aggregate (RCA) and RCA-rubber chips mixtures (15% of rubber addition). Presented study is an attempt to describe dynamic properties, in terms of shear wave velocity (VS), of the aforementioned anthropogenic material using the technique commonly applied for natural soil. Although some research is currently being carried out, in order to evaluate physical, chemical and mechanical properties of RCA and rubber-soil mixtures, still little is known of their dynamic properties. Hence, this work will provide the experimental results of shear wave velocity of RCA and its modified version. The results show that tires chips significantly decrease the VS values of modified RCA. They help to reduce the near field effect, but the received parameters are more incoherent. The VS values were found to be influenced by interpretation technique, mean effective stress and wave’s propagation period. The maximum VS values were obtained mostly from the frequency domain method, although time domain analysis gives the results that are more coherent. Full article
(This article belongs to the Section Materials)
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Open AccessArticle
Thermal Performance of Concrete with Recycled Aggregates from CDW Plants
Appl. Sci. 2017, 7(7), 740; https://doi.org/10.3390/app7070740
Received: 21 June 2017 / Revised: 14 July 2017 / Accepted: 17 July 2017 / Published: 20 July 2017
Cited by 5 | Viewed by 1115 | PDF Full-text (3426 KB) | HTML Full-text | XML Full-text
Abstract
This investigation intends to analyse the thermal performance of concrete with recycled aggregates (RA) from construction and demolition waste (CDW) collected from several locations in Portugal. A total of 17 concrete mixes were analysed by means of thermal conductivity tests. Firstly, the composition [...] Read more.
This investigation intends to analyse the thermal performance of concrete with recycled aggregates (RA) from construction and demolition waste (CDW) collected from several locations in Portugal. A total of 17 concrete mixes were analysed by means of thermal conductivity tests. Firstly, the composition and characteristics of the aggregates (natural and recycled) used in the production of the concrete mixes were analysed thoroughly, by means of several physical and chemical tests. Later, in order to evaluate the thermal behaviour of the mixes, several tests were performed and their results analysed, both on the fresh-state (slump with the Abrams cone test, density and air content) and the hardened state (compressive strength and thermal conductivity). The analysis of the thermal behaviour showed that the use of RA improves the thermal performance of the concrete mixes. The extent of this change was shown to be quite variable depending on the origin of the RA used. Full article
(This article belongs to the Section Materials)
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Open AccessArticle
Measurements of Thermally-Induced Curvatures and Warpages of Printed Circuit Board during a Solder Reflow Process Using Strain Gauges
Appl. Sci. 2017, 7(7), 739; https://doi.org/10.3390/app7070739
Received: 22 June 2017 / Revised: 11 July 2017 / Accepted: 18 July 2017 / Published: 20 July 2017
Cited by 2 | Viewed by 1707 | PDF Full-text (7898 KB) | HTML Full-text | XML Full-text
Abstract
Measurements of the curvatures and warpages of a printed circuit board (PCB) during a thermal solder reflow process using strain gauges are proposed in this study. In the experiments, a shadow moiré is used for measuring the out-of-plane deformations (or warpage) of a [...] Read more.
Measurements of the curvatures and warpages of a printed circuit board (PCB) during a thermal solder reflow process using strain gauges are proposed in this study. In the experiments, a shadow moiré is used for measuring the out-of-plane deformations (or warpage) of a bi-material plate and a PCB with dual in-line memory module (DIMM) sockets during solder reflow heating, while the finite element method (FEM) is used to analyze the thermally-induced deformation of the PCB specimen for ensuring the validity of the measurement. Conventional strain gauges are employed to measure the strains (albeit as in-plane strain data) in both specimens during the solder reflow process. The results indicate that the strain gauge-measured strain data from the top and bottom surfaces of both specimens during the solder reflow can be converted into curvature data with specific equations, and even into global out-of-plane deformations or warpages with a proposed simple beam model. Such results are also consistent with those from the shadow moiré and FEM. Therefore, it has been proved that the strain gauge measurement associated with the simple beam model can provide a method for the real-time monitoring of PCB deformations or warpages with different temperatures during the solder reflow process. Full article
(This article belongs to the Special Issue Printed Electronics 2017)
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Open AccessArticle
Adaptive Global Fast Sliding Mode Control for Steer-by-Wire System Road Vehicles
Appl. Sci. 2017, 7(7), 738; https://doi.org/10.3390/app7070738
Received: 21 June 2017 / Revised: 11 July 2017 / Accepted: 13 July 2017 / Published: 19 July 2017
Cited by 4 | Viewed by 1801 | PDF Full-text (4867 KB) | HTML Full-text | XML Full-text
Abstract
A steer-by-wire (SbW) system, also known as a next-generation steering system, is one of the core elements of autonomous driving technology. Navigating a SbW system road vehicle in varying driving conditions requires an adaptive and robust control scheme to effectively compensate for the [...] Read more.
A steer-by-wire (SbW) system, also known as a next-generation steering system, is one of the core elements of autonomous driving technology. Navigating a SbW system road vehicle in varying driving conditions requires an adaptive and robust control scheme to effectively compensate for the uncertain parameter variations and external disturbances. Therefore, this article proposed an adaptive global fast sliding mode control (AGFSMC) for SbW system vehicles with unknown steering parameters. First, the cooperative adaptive sliding mode observer (ASMO) and Kalman filter (KF) are established to simultaneously estimate the vehicle states and cornering stiffness coefficients. Second, based on the best set of estimated dynamics, the AGFSMC is designed to stabilize the impact of nonlinear tire-road disturbance forces and at the same time to estimate the uncertain SbW system parameters. Due to the robust nature of the proposed scheme, it can not only handle the tire–road variation, but also intelligently adapts to the different driving conditions and ensures that the tracking error and the sliding surface converge asymptotically to zero in a finite time. Finally, simulation results and comparative study with other control techniques validate the excellent performance of the proposed scheme. Full article
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Open AccessFeature PaperArticle
Elastic Wave Measurement Using a MEMS AE Sensor
Appl. Sci. 2017, 7(7), 737; https://doi.org/10.3390/app7070737
Received: 28 April 2017 / Revised: 15 June 2017 / Accepted: 3 July 2017 / Published: 19 July 2017
Cited by 2 | Viewed by 1699 | PDF Full-text (4865 KB) | HTML Full-text | XML Full-text
Abstract
In recent years, with the continuing progress of aging social infrastructures such as bridges and tunnels, there has been high demand for the assessment of deterioration of their performance and conditions. Since current inspection methods for those structures have mainly relied on human [...] Read more.
In recent years, with the continuing progress of aging social infrastructures such as bridges and tunnels, there has been high demand for the assessment of deterioration of their performance and conditions. Since current inspection methods for those structures have mainly relied on human resources, it is important to reduce their increasing maintenance cost. One of the key methods for achieving effective maintenance without expensive human costs is to use sensors to discriminate between healthy and unhealthy conditions. In this paper, a MEMS (micro electro mechanical systems) wideband frequency sensor, which is referred to as a super acoustic (SA) sensor, is evaluated through the pencil lead break (PLB) test. Due to its wideband frequency characteristics, the SA sensor is expected to be a promising alternative to the existing vibration sensors, including acoustic emission (AE) sensors. Several PLB signals were generated on an aluminum plate (5 mm thick), and propagating Lamb waves were detected by both AE and SA sensors. SA sensors were able to identify the location of PLB sources on the plate by measuring time differences between each sensor. By comparing the wave spectrums of both the AE and SA sensors analyzed by wavelet transform, the applicability of SA sensor for AE measurement is verified. Full article
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Open AccessArticle
Synthesis, Characterization, and Antibacterial Activities of High-Valence Silver Propamidine Nanoparticles
Appl. Sci. 2017, 7(7), 736; https://doi.org/10.3390/app7070736
Received: 20 June 2017 / Revised: 12 July 2017 / Accepted: 15 July 2017 / Published: 18 July 2017
Cited by 2 | Viewed by 1412 | PDF Full-text (1477 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Diabetic foot ulcer (DFU) is becoming more serious concern as it affects 95% of diabetic patients worldwide. It has been shown that the Staphylococcus aureus and other Gram-negative microorganisms are the main reasons behind this disease. Though many antibiotics are presently used to [...] Read more.
Diabetic foot ulcer (DFU) is becoming more serious concern as it affects 95% of diabetic patients worldwide. It has been shown that the Staphylococcus aureus and other Gram-negative microorganisms are the main reasons behind this disease. Though many antibiotics are presently used to treat the DFU, due to increased bacterial resistance, new alternative therapies are always welcome. To address this alarming issue, we have designed and synthesized the high-valence silver propamidine (Ag(II)PRO) complex as well as nanoparticles and characterized both by usual spectroscopic methods. The reverse microemulsion technique has been applied to synthesize Ag(II)PRO nanoparticles and its antibacterial activity has been compared with zero-valence silver nanoparticles (AgNPs) with similar size. The antibacterial efficacies of Ag(II)PRO nanoparticles and AgNPs were tested against Gram-negative and Gram -positive organisms responsible for DFU. The newly synthesized high-valence Ag(II)PRO nanoparticles showed higher antibacterial activity compared to silver-only nanoparticles (AgNPs). This study concludes that the high-valence Ag(II)PRO nanoparticles show better antibacterial activity than AgNPs and they may serve as the next generation therapeutic agent for the diabetic wound care. Full article
(This article belongs to the Section Nanotechnology and Applied Nanosciences)
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Open AccessArticle
Seismic Vulnerability Assessment of a Shallow Two-Story Underground RC Box Structure
Appl. Sci. 2017, 7(7), 735; https://doi.org/10.3390/app7070735
Received: 8 June 2017 / Revised: 8 July 2017 / Accepted: 14 July 2017 / Published: 18 July 2017
Cited by 5 | Viewed by 1695 | PDF Full-text (4170 KB) | HTML Full-text | XML Full-text
Abstract
Tunnels, culverts, and subway stations are the main parts of an integrated infrastructure system. Most of them are constructed by the cut-and-cover method at shallow depths (mainly lower than 30 m) of soil deposits, where large-scale seismic ground deformation can occur with lower [...] Read more.
Tunnels, culverts, and subway stations are the main parts of an integrated infrastructure system. Most of them are constructed by the cut-and-cover method at shallow depths (mainly lower than 30 m) of soil deposits, where large-scale seismic ground deformation can occur with lower stiffness and strength of the soil. Therefore, the transverse racking deformation (one of the major seismic ground deformation) due to soil shear deformations should be included in the seismic design of underground structures using cost- and time-efficient methods that can achieve robustness of design and are easily understood by engineers. This paper aims to develop a simplified but comprehensive approach relating to vulnerability assessment in the form of fragility curves on a shallow two-story reinforced concrete underground box structure constructed in a highly-weathered soil. In addition, a comparison of the results of earthquakes per peak ground acceleration (PGA) is conducted to determine the effective and appropriate number for cost- and time-benefit analysis. The ground response acceleration method for buried structures (GRAMBS) is used to analyze the behavior of the structure subjected to transverse seismic loading under quasi-static conditions. Furthermore, the damage states that indicate the exceedance level of the structural strength capacity are described by the results of nonlinear static analyses (or so-called pushover analyses). The Latin hypercube sampling technique is employed to consider the uncertainties associated with the material properties and concrete cover owing to the variation in construction conditions. Finally, a large number of artificial ground shakings satisfying the design spectrum are generated in order to develop the seismic fragility curves based on the defined damage states. It is worth noting that the number of ground motions per PGA, which is equal to or larger than 20, is a reasonable value to perform a structural analysis that produces satisfactory fragility curves. Full article
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Open AccessArticle
Three Dimensional Digital Sieving of Asphalt Mixture Based on X-ray Computed Tomography
Appl. Sci. 2017, 7(7), 734; https://doi.org/10.3390/app7070734
Received: 30 June 2017 / Revised: 11 July 2017 / Accepted: 12 July 2017 / Published: 18 July 2017
Cited by 1 | Viewed by 1457 | PDF Full-text (3610 KB) | HTML Full-text | XML Full-text
Abstract
In order to perform three-dimensional digital sieving based on X-ray computed tomography images, the definition of digital sieve size (DSS) was proposed, which was defined as the minimum length of the minimum bounding squares of all possible orthographic projections of an aggregate. The [...] Read more.
In order to perform three-dimensional digital sieving based on X-ray computed tomography images, the definition of digital sieve size (DSS) was proposed, which was defined as the minimum length of the minimum bounding squares of all possible orthographic projections of an aggregate. The corresponding program was developed to reconstruct aggregate structure and to obtain DSS. Laboratory experiments consisting of epoxy-filled aggregate specimens were conducted to investigate the difference between mechanical sieve analysis and the digital sieving technique. It was suggested that concave surface of aggregate was the possible reason for the disparity between DSS and mechanical sieve size. A comparison between DSS and equivalent diameter was also performed. Moreover, the digital sieving technique was adopted to evaluate the gradation of stone mastic asphalt mixtures. The results showed that the closest proximity of the laboratory gradation curve was achieved by calibrated DSS, among gradation curves based on calibrated DSS, un-calibrated DSS and equivalent diameter. Full article
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Open AccessArticle
Development of a Modelling and Simulation Method for Residential Electricity Consumption Analysis in a Community Microgrid System
Appl. Sci. 2017, 7(7), 733; https://doi.org/10.3390/app7070733
Received: 22 June 2017 / Revised: 7 July 2017 / Accepted: 11 July 2017 / Published: 17 July 2017
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Abstract
There is an increasing number of microgrid applications for power system networks at different voltage levels. Community microgrid systems are also being encouraged in order to increase energy efficiency, reduce electricity bills, and alleviate the reliability problem with respect to power delivery for [...] Read more.
There is an increasing number of microgrid applications for power system networks at different voltage levels. Community microgrid systems are also being encouraged in order to increase energy efficiency, reduce electricity bills, and alleviate the reliability problem with respect to power delivery for local residential users. Understanding electricity information can help in effective management and control of various energy sources operated in community microgrid systems. This paper thus aims to develop a simulation-based electricity analysis scheme for a real community microgrid configuration using a proposed modelling methodology, simulation mechanisms, and a power balancing control strategy under the MATLAB environment. Simulation results considering different weather conditions report the observed performance of electricity analysis. In addition, calculations of electricity bills depending on two electricity rates are discussed, representing the benefits of electricity bill reduction when electricity users accepted the power supply from community microgrid systems. Full article
(This article belongs to the Special Issue Selected Papers from IEEE ICASI 2017)
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Open AccessFeature PaperReview
Widely-Tunable Ring-Resonator Semiconductor Lasers
Appl. Sci. 2017, 7(7), 732; https://doi.org/10.3390/app7070732
Received: 27 June 2017 / Revised: 7 July 2017 / Accepted: 12 July 2017 / Published: 17 July 2017
Cited by 6 | Viewed by 1844 | PDF Full-text (7897 KB) | HTML Full-text | XML Full-text
Abstract
Chip-scale widely-tunable lasers are important for both communication and sensing applications. They have a number of advantages, such as size, weight, and cost compared to mechanically tuned counterparts. Furthermore, they allow for integration in more complex integrated photonic chips to realize added functionality. [...] Read more.
Chip-scale widely-tunable lasers are important for both communication and sensing applications. They have a number of advantages, such as size, weight, and cost compared to mechanically tuned counterparts. Furthermore, they allow for integration in more complex integrated photonic chips to realize added functionality. Here we give an extensive overview of such lasers realized by utilizing ring resonators inside the laser cavity. Use of ring resonators for tuning allows for wide-tunability by exploiting the Vernier effect, and at the same time improves the laser linewidth, as effective cavity length is increased at ring resonance. In this review, we briefly introduce basic concepts of laser tuning using ring resonators. Then, we study a number of laser cavity configurations that utilize two ring resonators, and compare their tuning performance. We introduce a third ring resonator to the laser cavity, study three different cavity configurations utilizing three ring resonators, and select the optimal one, for which we show that laser tuning is straightforward, provided there are monitor photodetectors on-chip. Finally, we give a literature overview showing superior linewidth performance of ring-based widely-tunable lasers. Full article
(This article belongs to the Section Optics and Lasers)
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Open AccessReview
A Review on Nanocomposite Materials for Rechargeable Li-ion Batteries
Appl. Sci. 2017, 7(7), 731; https://doi.org/10.3390/app7070731
Received: 15 June 2017 / Revised: 8 July 2017 / Accepted: 12 July 2017 / Published: 17 July 2017
Cited by 7 | Viewed by 2547 | PDF Full-text (8265 KB) | HTML Full-text | XML Full-text
Abstract
Li-ion batteries are the key enabling technology in portable electronics applications, and such batteries are also getting a foothold in mobile platforms and stationary energy storage technologies recently. To accelerate the penetration of Li-ion batteries in these markets, safety, cost, cycle life, energy [...] Read more.
Li-ion batteries are the key enabling technology in portable electronics applications, and such batteries are also getting a foothold in mobile platforms and stationary energy storage technologies recently. To accelerate the penetration of Li-ion batteries in these markets, safety, cost, cycle life, energy density and rate capability of the Li-ion batteries should be improved. The Li-ion batteries in use today take advantage of the composite materials already. For instance, cathode, anode and separator are all composite materials. However, there is still plenty of room for advancing the Li-ion batteries by utilizing nanocomposite materials. By manipulating the Li-ion battery materials at the nanoscale, it is possible to achieve unprecedented improvement in the material properties. After presenting the current status and the operating principles of the Li-ion batteries briefly, this review discusses the recent developments in nanocomposite materials for cathode, anode, binder and separator components of the Li-ion batteries. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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Open AccessArticle
Optimized Neural Architecture for Automatic Landslide Detection from High‐Resolution Airborne Laser Scanning Data
Appl. Sci. 2017, 7(7), 730; https://doi.org/10.3390/app7070730
Received: 29 June 2017 / Revised: 11 July 2017 / Accepted: 13 July 2017 / Published: 16 July 2017
Cited by 13 | Viewed by 1904 | PDF Full-text (10456 KB) | HTML Full-text | XML Full-text
Abstract
An accurate inventory map is a prerequisite for the analysis of landslide susceptibility, hazard, and risk. Field survey, optical remote sensing, and synthetic aperture radar techniques are traditional techniques for landslide detection in tropical regions. However, such techniques are time consuming and costly. [...] Read more.
An accurate inventory map is a prerequisite for the analysis of landslide susceptibility, hazard, and risk. Field survey, optical remote sensing, and synthetic aperture radar techniques are traditional techniques for landslide detection in tropical regions. However, such techniques are time consuming and costly. In addition, the dense vegetation of tropical forests complicates the generation of an accurate landslide inventory map for these regions. Given its ability to penetrate vegetation cover, high-resolution airborne light detection and ranging (LiDAR) has been used to generate accurate landslide maps. This study proposes the use of recurrent neural networks (RNN) and multi-layer perceptron neural networks (MLP-NN) in landscape detection. These efficient neural architectures require little or no prior knowledge compared with traditional classification methods. The proposed methods were tested in the Cameron Highlands, Malaysia. Segmentation parameters and feature selection were respectively optimized using a supervised approach and correlation-based feature selection. The hyper-parameters of network architecture were defined based on a systematic grid search. The accuracies of the RNN and MLP-NN models in the analysis area were 83.33% and 78.38%, respectively. The accuracies of the RNN and MLP-NN models in the test area were 81.11%, and 74.56%, respectively. These results indicated that the proposed models with optimized hyper-parameters produced the most accurate classification results. LiDAR-derived data, orthophotos, and textural features significantly affected the classification results. Therefore, the results indicated that the proposed methods have the potential to produce accurate and appropriate landslide inventory in tropical regions such as Malaysia. Full article
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Open AccessArticle
Data-Foraging-Oriented Reconnaissance Based on Bio-Inspired Indirect Communication for Aerial Vehicles
Appl. Sci. 2017, 7(7), 729; https://doi.org/10.3390/app7070729
Received: 31 May 2017 / Revised: 9 July 2017 / Accepted: 12 July 2017 / Published: 16 July 2017
Cited by 1 | Viewed by 1619 | PDF Full-text (991 KB) | HTML Full-text | XML Full-text
Abstract
In recent years, aerial vehicles have allowed exploring scenarios with harsh conditions. These can conduct reconnaissance tasks in areas that change periodically and have a high spatial and temporal resolution. The objective of a reconnaissance task is to survey an area and retrieve [...] Read more.
In recent years, aerial vehicles have allowed exploring scenarios with harsh conditions. These can conduct reconnaissance tasks in areas that change periodically and have a high spatial and temporal resolution. The objective of a reconnaissance task is to survey an area and retrieve strategic information. The aerial vehicles, however, have inherent constraints in terms of energy and transmission range due to their mobility. Despite these constraints, the Data Foraging problem requires the aerial vehicles to exchange information about profitable data sources. In Data Foraging, establishing a single path is not viable because of dynamic conditions of the environment. Thus, reconnaissance must be focused on periodically searching profitable environmental data sources, as some animals perform foraging. In this work, a data-foraging-oriented reconnaissance algorithm based on bio-inspired indirect communication for aerial vehicles is presented. The approach establishes several paths that overlap to identify valuable data sources. Inspired by the stigmergy principle, the aerial vehicles indirectly communicate through artificial pheromones. The aerial vehicles traverse the environment using a heuristic algorithm that uses the artificial pheromones as feedback. The solution is formally defined and mathematically evaluated. In addition, we show the viability of the algorithm by simulations which have been tested through various statistical hypothesis. Full article
(This article belongs to the Special Issue Bio-Inspired Robotics) Printed Edition available
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Open AccessArticle
Effects of Radial Gap Ratio between Impeller and Vaned Diffuser on Performance of Centrifugal Compressors
Appl. Sci. 2017, 7(7), 728; https://doi.org/10.3390/app7070728
Received: 3 April 2017 / Revised: 10 July 2017 / Accepted: 11 July 2017 / Published: 16 July 2017
Cited by 4 | Viewed by 2099 | PDF Full-text (12276 KB) | HTML Full-text | XML Full-text
Abstract
A high-performance centrifugal compressor is needed for numerous industry applications nowadays. The radial gap ratio between the impeller and the diffuser vanes plays an important role in the improvement of the compressor performance. In this paper, the effects of the radial gap ratio [...] Read more.
A high-performance centrifugal compressor is needed for numerous industry applications nowadays. The radial gap ratio between the impeller and the diffuser vanes plays an important role in the improvement of the compressor performance. In this paper, the effects of the radial gap ratio on a high-pressure ratio centrifugal compressor are investigated using numerical simulations. The performance and the flow field are compared for six different radial gap ratios and five rotational speeds. The minimal radial gap ratio was 1.04 and the maximal was 1.14. Results showed that reducing the radial gap ratio decreases the choke mass flow rate. For the tip-speed Mach number (impeller inlet) with Mu < 1, the pressure recovery and the loss coefficients are not sensitive to the radial gap ratio. However, for Mu ≥ 1, the best radial gap ratio is 1.08 for the pressure recovery and the loss coefficients. Furthermore, the impeller pressure ratio and efficiency are reduced by increasing the radial gap ratio. Finally, the compressor efficiency was compared for different radial gap ratios. For Mu < 1, the radial gap ratio does not have noticeable effects. In comparison, the radial gap ratio of 1.08 has the best performance for Mu ≥ 1. Full article
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Open AccessEditorial
Special Issue on Advances in Integrated Energy Systems Design, Control and Optimization
Appl. Sci. 2017, 7(7), 727; https://doi.org/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
Open AccessArticle
Evaluating the Impact of the Sudden Collapse of Major Freeway Connectors on Rapid Transit and Adjacent Freeway Systems: San Francisco Bay Area Case Study
Appl. Sci. 2017, 7(7), 726; https://doi.org/10.3390/app7070726
Received: 14 June 2017 / Revised: 8 July 2017 / Accepted: 12 July 2017 / Published: 15 July 2017
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Abstract
The early Sunday morning collapse of two sections of the multi-level freeway interchange, known as the MacArthur Maze, resulted in a month-long closure of the interchange, which connects several major California cities: San Francisco, Oakland, and Berkeley. This paper evaluates the impacts of [...] Read more.
The early Sunday morning collapse of two sections of the multi-level freeway interchange, known as the MacArthur Maze, resulted in a month-long closure of the interchange, which connects several major California cities: San Francisco, Oakland, and Berkeley. This paper evaluates the impacts of this unplanned, extended closure on Bay Area Rapid Transit (BART) and the remaining freeway system based on empirical data and reports on the findings. Among the findings were that BART was instrumental in keeping commuters moving during the freeway repair. In addition, ridership counts at some stations remained significantly elevated after the repairs were completed. This may be due to the fact that many of the riders using those BART stations had not previously traveled via transit and, having discovered its convenience and benefits during the repair phase, continued to use BART even after the repairs. The impact of the closure on BART demand was not uniform across the stations. Full article
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Open AccessArticle
Broadening of Light Coupling to Waveguide Modes in Solar Cells by Disordered Grating Textures
Appl. Sci. 2017, 7(7), 725; https://doi.org/10.3390/app7070725
Received: 20 June 2017 / Revised: 13 July 2017 / Accepted: 13 July 2017 / Published: 15 July 2017
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Abstract
We investigated the light coupling to waveguide modes in nanophotonic thin-film solar cells exhibiting a tailored disordered grating texture by rigorous optical simulations. Such disordered nanophotonic light trapping concepts have demonstrated enhanced short-circuit current density compared to ordered nanophotonic thin-film solar cells. This [...] Read more.
We investigated the light coupling to waveguide modes in nanophotonic thin-film solar cells exhibiting a tailored disordered grating texture by rigorous optical simulations. Such disordered nanophotonic light trapping concepts have demonstrated enhanced short-circuit current density compared to ordered nanophotonic thin-film solar cells. This observation is commonly explained by a spectral broadening of the resonant light coupling to waveguide modes. In this work, we investigated the origin of this spectral broadening. We identified two basic mechanisms that lead to a spectral broadening of the light coupling to waveguide modes: (1) the broadening of the wave vector transferred by the disordered interface texture and (2) the broadening of the waveguide mode due to the distortion of the wave guiding absorber layer. Depending on the type of disorder, the contribution from each of the mechanisms varies. Full article
(This article belongs to the Special Issue Light Management for Optoelectronics)
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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; https://doi.org/10.3390/app7070724
Received: 26 May 2017 / Revised: 4 July 2017 / Accepted: 10 July 2017 / Published: 14 July 2017
Cited by 1 | Viewed by 1316 | PDF Full-text (2213 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a novel method to determine the center of mass position of each link of human-like multibody biped robots is proposed. A first formulation to determine the total center of mass position has been tested in other works on a biped [...] Read more.
In this paper, a novel method to determine the center of mass position of each link of human-like multibody biped robots is proposed. A first formulation to determine the total center of mass position has been tested in other works on a biped platform with human-like dimensions. In this paper, the formulation is optimized and extended, and it is able to give as output the center of mass positions of each link of the platform. The calculation can be applied to different types of robots. The optimized formulation is validated using a simulated biped robot in MATLAB. Full article
(This article belongs to the Special Issue Bio-Inspired Robotics) Printed Edition available
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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; https://doi.org/10.3390/app7070723
Received: 16 June 2017 / Revised: 6 July 2017 / Accepted: 11 July 2017 / Published: 14 July 2017
Cited by 3 | Viewed by 1285 | PDF Full-text (3203 KB) | HTML Full-text | XML Full-text
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 [...] Read more.
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
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; https://doi.org/10.3390/app7070722
Received: 15 June 2017 / Revised: 9 July 2017 / Accepted: 10 July 2017 / Published: 14 July 2017
Cited by 8 | Viewed by 1941 | PDF Full-text (2322 KB) | HTML Full-text | XML Full-text
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 [...] Read more.
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 AccessArticle
The New Concept of Nano-Device Spectroscopy Based on Rabi–Bloch Oscillations for THz-Frequency Range
Appl. Sci. 2017, 7(7), 721; https://doi.org/10.3390/app7070721
Received: 21 June 2017 / Revised: 9 July 2017 / Accepted: 10 July 2017 / Published: 14 July 2017
Cited by 2 | Viewed by 1349 | PDF Full-text (11008 KB) | HTML Full-text | XML Full-text
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 [...] Read more.
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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