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Appl. Sci., Volume 8, Issue 8 (August 2018)

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Open AccessArticle Magneto-Optical Kerr Effect Driven by Spin Accumulation on Cu, Au, and Pt
Appl. Sci. 2018, 8(8), 1378; https://doi.org/10.3390/app8081378 (registering DOI)
Received: 18 July 2018 / Revised: 9 August 2018 / Accepted: 13 August 2018 / Published: 15 August 2018
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Abstract
The magneto-optical Kerr effect (MOKE) has recently been achieved on non-ferromagnetic metals by injecting spin currents. To use the magneto-optical Kerr effect as a quantitative tool, it is crucial to study the relationship between the Kerr rotation angle and the spin accumulation on
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The magneto-optical Kerr effect (MOKE) has recently been achieved on non-ferromagnetic metals by injecting spin currents. To use the magneto-optical Kerr effect as a quantitative tool, it is crucial to study the relationship between the Kerr rotation angle and the spin accumulation on non-ferromagnets. In this work, I measure a transient magneto-optical Kerr rotation on non-ferromagnetic metals of Cu, Au, and Pt driven by an ultrafast spin current from an adjacent ferromagnetic metal. Through comparing the measured Kerr rotation and the calculated spin accumulation, I determine the conversion ratio between the Kerr rotation and the spin accumulation to be: −4 × 10−9 (real part), −2.5 × 10−8 (real part), and −3 × 10−9 (imaginary part) rad m A−1 for Cu, Au, and Pt, respectively, at a wavelength of 784 nm. Full article
(This article belongs to the Special Issue Optics in Spintronic Materials)
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Open AccessArticle Engineering Properties of Controlled Low-Strength Materials Containing Bottom Ash of Municipal Solid Waste Incinerator and Water Filter Silt
Appl. Sci. 2018, 8(8), 1377; https://doi.org/10.3390/app8081377 (registering DOI)
Received: 26 July 2018 / Revised: 8 August 2018 / Accepted: 13 August 2018 / Published: 15 August 2018
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Abstract
The bottom ash of a municipal solid waste incinerator (MSWI) and water filter silt (WFS) were applied to a controlled low-strength material (CLSM) in the present study. The CLSM of the control group was composed of cement, water, and fine aggregates. WFS was
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The bottom ash of a municipal solid waste incinerator (MSWI) and water filter silt (WFS) were applied to a controlled low-strength material (CLSM) in the present study. The CLSM of the control group was composed of cement, water, and fine aggregates. WFS was first used as a fill material to replace 10% of the volume of natural fine aggregates in the CLSM. MSWI bottom ash was used to replace 0%, 25%, 50%, 75%, and 100% of the volume of the remaining natural fine aggregates with a water-cement ratio of 1.6. The engineering properties of freshness, hardening, and durability were examined. The results revealed that the slump flows of all of the mixture proportions ranged between 50 and 70 cm. The tube flow ranged between 20 and 30 cm, conforming to ASTM D6103 and construction regulations regarding CLSMs stipulated by the Water Resources Agency of the Ministry of Economic Affairs in Taiwan. Increases in the replacement amount of MSWI bottom ash prolonged the time required to achieve a resistance to penetration of 2.74 MPa. The diameter of the drop test ball was less than 7.6 cm, indicating that the mixture proportions had sufficient bearing capacity for successive construction. At an age of 28 d, the compressive strength did not exceed the 8.4 MPa prescribed in ASTM D4832. The ultrasonic pulse velocity and water absorption exhibited identical growth tendencies. In summary, using MSWI bottom ash to create CLSMs is feasible on the condition that the appropriate amount of WFS should be added. Full article
(This article belongs to the Section Materials)
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Open AccessReview Interface Engineering Strategies for Fabricating Nanocrystal-Based Organic–Inorganic Nanocomposites
Appl. Sci. 2018, 8(8), 1376; https://doi.org/10.3390/app8081376 (registering DOI)
Received: 9 July 2018 / Revised: 7 August 2018 / Accepted: 13 August 2018 / Published: 15 August 2018
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Abstract
Hybrid organic–inorganic nanocomposites have attracted considerable attention because they have the advantages of both conjugated polymers (CPs) and nanocrystals (NCs). Recent developments in the interfacial engineering of CP–NC organic–inorganic nanocomposites enabled the formation of an intimate contact between NCs and CPs, facilitating electronic
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Hybrid organic–inorganic nanocomposites have attracted considerable attention because they have the advantages of both conjugated polymers (CPs) and nanocrystals (NCs). Recent developments in the interfacial engineering of CP–NC organic–inorganic nanocomposites enabled the formation of an intimate contact between NCs and CPs, facilitating electronic interactions between these two constituents. To design CP–NC nanocomposites, several approaches have been introduced, including ligand refluxing, direct grafting methods, direct growth of NCs in proximity to CPs, and template-guided strategies. In this review, the general reactions of ligand exchange processes, purification methods, and characterization techniques have been briefly introduced. This is followed by a highlight of recent advances in the synthesis of hybrid CP–NC nanocomposites and newly developed inorganic surface treatments, as well as their applications. An outlook for future directions in this area is also presented. Full article
(This article belongs to the Section Nanotechnology and Applied Nanosciences)
Open AccessReview Mg-Based Hydrogen Absorbing Materials for Thermal Energy Storage—A Review
Appl. Sci. 2018, 8(8), 1375; https://doi.org/10.3390/app8081375 (registering DOI)
Received: 24 July 2018 / Revised: 8 August 2018 / Accepted: 9 August 2018 / Published: 15 August 2018
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Abstract
Utilization of renewable energy such as solar, wind, and geothermal power, appears to be the most promising solution for the development of sustainable energy systems without using fossil fuels. Energy storage, especially to store the energy from fluctuating power is quite vital for
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Utilization of renewable energy such as solar, wind, and geothermal power, appears to be the most promising solution for the development of sustainable energy systems without using fossil fuels. Energy storage, especially to store the energy from fluctuating power is quite vital for smoothing out energy demands with peak/off-peak hour fluctuations. Thermal energy is a potential candidate to serve as an energy reserve. However, currently the development of thermal energy storage (TES) by traditional physical means is restricted by the relatively low energy density, high temperature demand, and the great thermal energy loss during long-period storage. Chemical heat storage is one of the most promising alternatives for TES due to its high energy density, low energy loss, flexible temperature range, and excellent storage duration. A comprehensive review on the development of different types of Mg-based materials for chemical heat storage is presented here and the classic and state-of-the-art technologies are summarized. Some related chemical principles, as well as heat storage properties, are discussed in the context. Finally, some dominant factors of chemical heat storage materials are concluded and the perspective is proposed for the development of next-generation chemical heat storage technologies. Full article
(This article belongs to the Special Issue Materials for Thermal Energy Storage)
Open AccessArticle Experimental Analysis of Pore and Permeability Characteristics of Coal by Low-Field NMR
Appl. Sci. 2018, 8(8), 1374; https://doi.org/10.3390/app8081374 (registering DOI)
Received: 21 July 2018 / Revised: 8 August 2018 / Accepted: 10 August 2018 / Published: 15 August 2018
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Abstract
On the basis of the complexity of the pore structure characteristics of a coal reservoir, coal samples with different ranks were selected to study the difference in pore structures and permeability using nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), mercury intrusion porosimetry
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On the basis of the complexity of the pore structure characteristics of a coal reservoir, coal samples with different ranks were selected to study the difference in pore structures and permeability using nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), and permeability measurement. Porosity and pore size distribution (PSD) above 20 nm can be analyzed by the improved NMR equation, and the results were basically consistent with that of SEM and MIP. The NMR spectra of the coal samples from the same location were close, but the difference between the coal samples from different locations was quite large, which indicated that the heterogeneity of a coal reservoir was strong. An empirical equation of movable fluid porosity was proposed, which can be used to evaluate the fluid migration characteristics of the coal reservoir, and the porosity of movable fluid mainly came from the contribution of fissures and micro-fissures. The average movable fluid porosity of the coal samples from the Chengzhuang (CZ) coal mine, Wuyang (WY) coal mine, and Yujialiang (YJL) coal mine was 1.37%, 0.67%, and 4.26%, respectively. Although the permeability is related to the NMR porosity and movable fluid porosity, it was difficult to establish a widely used mathematical equation correlating permeability and porosity based on the experimental data. Full article
(This article belongs to the Special Issue Nanotech for Oil and Gas)
Open AccessArticle Research on Residual Life Prediction for Electrical Connectors Based on Intermittent Failure and Hidden Semi-Markov Model
Appl. Sci. 2018, 8(8), 1373; https://doi.org/10.3390/app8081373 (registering DOI)
Received: 15 July 2018 / Revised: 11 August 2018 / Accepted: 13 August 2018 / Published: 15 August 2018
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Abstract
Based on the dynamic properties of electrical connector intermittent failure, the model and methods for residual life prediction for electrical connectors are studied in this paper. Firstly, the mechanism of electrical connector intermittent failure is analyzed, and the area enclosed by the contact
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Based on the dynamic properties of electrical connector intermittent failure, the model and methods for residual life prediction for electrical connectors are studied in this paper. Firstly, the mechanism of electrical connector intermittent failure is analyzed, and the area enclosed by the contact resistance curve and the fault threshold is defined as the generalized severity of intermittent failure to describe how severe the electrical connector’s intermittent failure is. Then, the Hidden Semi-Markov Model (HSMM) is introduced to build the residual life prediction model of the electrical connector. Further, the evaluation method of using the state and prediction method for residual life are studied. Finally, by carrying out the residual life prediction test, the effectiveness of the residual life prediction method for electrical connectors based on intermittent failure and HSMM is verified. Full article
(This article belongs to the Section Mechanical Engineering)
Open AccessArticle Feature Selection and Transfer Learning for Alzheimer’s Disease Clinical Diagnosis
Appl. Sci. 2018, 8(8), 1372; https://doi.org/10.3390/app8081372 (registering DOI)
Received: 25 July 2018 / Revised: 10 August 2018 / Accepted: 11 August 2018 / Published: 15 August 2018
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Abstract
Background and Purpose: A majority studies on diagnosis of Alzheimer’s Disease (AD) are based on an assumption: the training and testing data are drawn from the same distribution. However, in the diagnosis of AD and mild cognitive impairment (MCI), this identical-distribution assumption may
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Background and Purpose: A majority studies on diagnosis of Alzheimer’s Disease (AD) are based on an assumption: the training and testing data are drawn from the same distribution. However, in the diagnosis of AD and mild cognitive impairment (MCI), this identical-distribution assumption may not hold. To solve this problem, we utilize the transfer learning method into the diagnosis of AD. Methods: The MR (Magnetic Resonance) images were segmented using spm-Dartel toolbox and registrated with Automatic Anatomical Labeling (AAL) atlas, then the gray matter (GM) tissue volume of the anatomical region were computed as characteristic parameter. The information gain was introduced for feature selection. The TrAdaboost algorithm was used to classify AD, MCI, and normal controls (NC) data from Alzheimer’s Disease Neuroimaging Initiative (ADNI) database, meanwhile, the “knowledge” learned from ADNI was transferred to AD samples from local hospital. The classification accuracy, sensitivity and specificity were calculated and compared with four classical algorithms. Results: In the experiment of transfer task: AD to MCI, 177 AD and 40NC subjects were grouped as training data; 245 MCI and 45 remaining NC subjects were combined as testing data, the highest accuracy achieved 85.4%, higher than the other four classical algorithms. Meanwhile, feature selection that is based on information gain reduced the features from 90 to 7, controlled the redundancy efficiently. In the experiment of transfer task: ADNI to local hospital data, the highest accuracy achieved 93.7%, and the specificity achieved 100%. Conclusions: The experimental results showed that our algorithm has a clear advantage over classic classification methods with higher accuracy and less fluctuation. Full article
(This article belongs to the Section Applied Biosciences and Bioengineering)
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Open AccessEditorial Special Issue on Socio-Cognitive and Affective Computing
Appl. Sci. 2018, 8(8), 1371; https://doi.org/10.3390/app8081371 (registering DOI)
Received: 2 August 2018 / Accepted: 14 August 2018 / Published: 15 August 2018
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Abstract
Social cognition focuses on how people process, store, and apply information about other people and social situations. [...] Full article
(This article belongs to the Special Issue Socio-Cognitive and Affective Computing)
Open AccessArticle A Stackelberg Game Approach for Price Response Coordination of Thermostatically Controlled Loads
Appl. Sci. 2018, 8(8), 1370; https://doi.org/10.3390/app8081370 (registering DOI)
Received: 27 May 2018 / Revised: 26 July 2018 / Accepted: 1 August 2018 / Published: 15 August 2018
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Abstract
In this paper, we study the demand response of the thermostatically controlled loads (TCLs) to control their set-point temperatures by considering the tradeoff between the electricity payment and TCL user’s comfort preference. Based upon the dynamics of the TCLs, we set up the
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In this paper, we study the demand response of the thermostatically controlled loads (TCLs) to control their set-point temperatures by considering the tradeoff between the electricity payment and TCL user’s comfort preference. Based upon the dynamics of the TCLs, we set up the relationship between the set-point temperature and the energy demand. Then, we define a discomfort function with respect to the associated energy demand which represents the discomfort level of the set-point temperature. More specifically, the system is equipped with a coordinator named electric energy control center (EECC) which can buy energy resources from the electricity market and sell them to TCL users. Due to the interaction between EECC and TCL users, we formulate the specific energy trading process as a one-leader multiple-follower Stackelberg game. As the main contributions of this work, we show the existence and uniqueness of the equilibrium for the underlying Stackelberg games, and develop a DR algorithm based on the so-called Backward Induction to achieve the equilibrium. Several numerical simulations are presented to verify the developed results in this work. Full article
(This article belongs to the Special Issue Smart Home and Energy Management Systems)
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Open AccessArticle Spatial Modelling of Gully Erosion Using GIS and R Programing: A Comparison among Three Data Mining Algorithms
Appl. Sci. 2018, 8(8), 1369; https://doi.org/10.3390/app8081369
Received: 13 July 2018 / Revised: 10 August 2018 / Accepted: 10 August 2018 / Published: 14 August 2018
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Abstract
Gully erosion triggers land degradation and restricts the use of land. This study assesses the spatial relationship between gully erosion (GE) and geo-environmental variables (GEVs) using Weights-of-Evidence (WoE) Bayes theory, and then applies three data mining methods—Random Forest (RF), boosted regression tree (BRT),
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Gully erosion triggers land degradation and restricts the use of land. This study assesses the spatial relationship between gully erosion (GE) and geo-environmental variables (GEVs) using Weights-of-Evidence (WoE) Bayes theory, and then applies three data mining methods—Random Forest (RF), boosted regression tree (BRT), and multivariate adaptive regression spline (MARS)—for gully erosion susceptibility mapping (GESM) in the Shahroud watershed, Iran. Gully locations were identified by extensive field surveys, and a total of 172 GE locations were mapped. Twelve gully-related GEVs: Elevation, slope degree, slope aspect, plan curvature, convergence index, topographic wetness index (TWI), lithology, land use/land cover (LU/LC), distance from rivers, distance from roads, drainage density, and NDVI were selected to model GE. The results of variables importance by RF and BRT models indicated that distance from road, elevation, and lithology had the highest effect on GE occurrence. The area under the curve (AUC) and seed cell area index (SCAI) methods were used to validate the three GE maps. The results showed that AUC for the three models varies from 0.911 to 0.927, whereas the RF model had a prediction accuracy of 0.927 as per SCAI values, when compared to the other models. The findings will be of help for planning and developing the studied region. Full article
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Open AccessReview A Brief History of Cloud Application Architectures
Appl. Sci. 2018, 8(8), 1368; https://doi.org/10.3390/app8081368
Received: 14 July 2018 / Revised: 24 July 2018 / Accepted: 27 July 2018 / Published: 14 August 2018
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Abstract
This paper presents a review of cloud application architectures and its evolution. It reports observations being made during a research project that tackled the problem to transfer cloud applications between different cloud infrastructures. As a side effect, we learned a lot about commonalities
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This paper presents a review of cloud application architectures and its evolution. It reports observations being made during a research project that tackled the problem to transfer cloud applications between different cloud infrastructures. As a side effect, we learned a lot about commonalities and differences from plenty of different cloud applications which might be of value for cloud software engineers and architects. Throughout the research project, we analyzed industrial cloud standards, performed systematic mapping studies of cloud-native application-related research papers, did action research activities in cloud engineering projects, modeled a cloud application reference model, and performed software and domain-specific language engineering activities. Two primary (and sometimes overlooked) trends can be identified. First, cloud computing and its related application architecture evolution can be seen as a steady process to optimize resource utilization in cloud computing. Second, these resource utilization improvements resulted over time in an architectural evolution of how cloud applications are being built and deployed. A shift from monolithic service-oriented architectures (SOA), via independently deployable microservices towards so-called serverless architectures, is observable. In particular, serverless architectures are more decentralized and distributed, and make more intentional use of separately provided services. In other words, a decentralizing trend in cloud application architectures is observable that emphasizes decentralized architectures known from former peer-to-peer based approaches. This is astonishing because, with the rise of cloud computing (and its centralized service provisioning concept), the research interest in peer-to-peer based approaches (and its decentralizing philosophy) decreased. However, this seems to change. Cloud computing could head into the future of more decentralized and more meshed services. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Detection of Gas-Solid Two-Phase Flow Based on CFD and Capacitance Method
Appl. Sci. 2018, 8(8), 1367; https://doi.org/10.3390/app8081367
Received: 15 July 2018 / Revised: 5 August 2018 / Accepted: 7 August 2018 / Published: 14 August 2018
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Abstract
Multiphase flow in annular channels is complex, particularly in the region where the flow direction abruptly changes between the inner pipe and the outer pipe, as the cases in horizontal drilling and pneumatic convey. Simplified models and experience are still the main sources
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Multiphase flow in annular channels is complex, particularly in the region where the flow direction abruptly changes between the inner pipe and the outer pipe, as the cases in horizontal drilling and pneumatic convey. Simplified models and experience are still the main sources of information. First, to understand the process more deeply, Computational Fluid Dynamics (CFD) package Fluent is used to simulate the gas-solid flow in the horizontal and the inclined sections of an annular pipe. Discrete Phase Model is adopted to calculate the trajectories of solid particles of different sizes at different air velocities. Also, the Two-Fluid model is used to simulate the sand flow in the inclined section for the case of air flow stoppage, for which an experiment is also conducted to verify the CFD simulation. Simulation results reveal the behaviour of the solid particles showing the dispersed spatial distribution of small particles near the entrance. On the other hand, larger particles manifest a distinct sedimented flow pattern along the bottom of the pipe. The density distribution of the particles over a pipe cross section is demonstrated at a variety of air velocities. The results also show that the large airspeed tends to generate swirls near the outlet of the inner pipe. In addition, Electrical Capacitance Tomography (ECT) technology is used to reconstruct the spatial distribution of particles, and the cross-correlation algorithm to detect velocity. Both the distribution and the velocity measurement by electric sensors agree reasonably well with the CFD predictions. The details revealed by CFD simulation and the mutual-verification between CFD simulation and the ECT method of this study could be valuable for the industry in drilling process control and equipment development. Full article
(This article belongs to the Special Issue Analysis and Simulation of Multiphase Flow in Porous Media)
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Open AccessArticle Increased Internal Porosity and Surface Area of Hydroxyapatite Accelerates Healing and Compensates for Low Bone Marrow Mesenchymal Stem Cell Concentrations in Critically-Sized Bone Defects
Appl. Sci. 2018, 8(8), 1366; https://doi.org/10.3390/app8081366
Received: 6 July 2018 / Revised: 3 August 2018 / Accepted: 6 August 2018 / Published: 14 August 2018
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Abstract
For clinical treatment of skeletal defects, osteoinductive scaffolds must have the ability to conform to the unique geometry of the injury site without sacrificing biologically favorable properties, including porosity. This investigation seeks to combine the osteoinductive properties of porous hydroxyapatite (HA) scaffolds with
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For clinical treatment of skeletal defects, osteoinductive scaffolds must have the ability to conform to the unique geometry of the injury site without sacrificing biologically favorable properties, including porosity. This investigation seeks to combine the osteoinductive properties of porous hydroxyapatite (HA) scaffolds with the beneficial handling characteristics of granules or putties, while evaluating the effects of mesenchymal stem cell (MSC) concentration on the composite grafts’ ability to regenerate bone in vivo. The results demonstrate that porous HA granules regenerate significantly larger volumes of bone compared to non-porous HA. Increased MSC concentrations in autologous bone marrow aspirate (BMA) contributed to greater bone regeneration. This effect was most predominant with non-porous HA. While the extent of bone regeneration using non-porous HA was strongly correlated with MSC concentration of the marrow, porous HA microparticles combined with autologous BMA were successful in faster treatment of critically-sized bone defects and with less dependence on the MSC concentration than non-porous HA. Full article
(This article belongs to the Section Applied Biosciences and Bioengineering)
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Open AccessArticle Numerical Research on the Mixture Mechanism of Polluted and Fresh Air at the Staggered Tunnel Portals
Appl. Sci. 2018, 8(8), 1365; https://doi.org/10.3390/app8081365
Received: 19 July 2018 / Revised: 9 August 2018 / Accepted: 10 August 2018 / Published: 13 August 2018
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Abstract
In longitudinal ventilation, circulating air is formed in portals for closely spaced twin tunnels, which causes mixing between the polluted air exhausted from one tunnel and the fresh air flow of another tunnel, thus leading to the rising costs of ventilation system construction
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In longitudinal ventilation, circulating air is formed in portals for closely spaced twin tunnels, which causes mixing between the polluted air exhausted from one tunnel and the fresh air flow of another tunnel, thus leading to the rising costs of ventilation system construction and operation. In this study, for the closely spaced tunnel with staggered inlet and outlet, the computational fluid dynamics (CFD) numerical simulation method was adopted to reveal flow characteristics of the circulating air as well as variation rules of the circulating air mixing ratio φc with tunnel structure and operation parameters. Results show that both reducing inlet air velocity and increasing outlet air velocity and lateral distance can reduce the impact of the negative-pressure zone at the tunnel entrance on the jet flow structure at the tunnel exit, thus weakening the circulating air. When the inlet is placed behind or aligned with the outlet (staggered distance ∆l ≤ 0), φc will increase linearly along with the increase of staggered distance; when the inlet is placed before the outlet (∆l > 0), φc will first increase and then decrease with the increase of staggered distance. An expression to predict circulating air mixing ratio was created by sections. The predictions show a good correlation with the measurements and indicate that the front slope gradient of the tunnel portal is also one of the factors affecting the circulating air mixing ratio. Full article
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Open AccessArticle Impact of the Temperature in the Evaluation of Battery Performances During Long-Term Cycling—Characterisation and Modelling
Appl. Sci. 2018, 8(8), 1364; https://doi.org/10.3390/app8081364
Received: 23 July 2018 / Revised: 6 August 2018 / Accepted: 8 August 2018 / Published: 13 August 2018
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Abstract
This paper presents the results regarding the thermal characterisation and modelling of high energy lithium-ion battery cells at both room (25 °C) and cycling (35 °C) temperatures. In this work two types of Nickel Manganese Cobalt (NMC) batteries are studied: a fresh (or
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This paper presents the results regarding the thermal characterisation and modelling of high energy lithium-ion battery cells at both room (25 °C) and cycling (35 °C) temperatures. In this work two types of Nickel Manganese Cobalt (NMC) batteries are studied: a fresh (or uncycled) and an aged (or cycled) battery cells. The ageing of the studied NMC battery cells is achieved by means of accelerated ageing tests (i.e., repetition of numerous charge and discharge cycles) at 35 °C cycling temperature. Temperature at the surface of the battery cells is characterised, with a set of three discharge current rates 0.3C (i.e., 6 A), 1C (i.e., 20 A) and 2C (i.e., 40 A), and the evolutions at three different locations on the surface of the battery cells namely, at the top, in the center and at the bottom regions are measured. In addition, temperature and ageing dependent electrochemical-thermal modelling of the uncycled and cycled battery cells is also successfully accomplished in case of both room and cycling temperatures. Numerical simulations were carried out in case of high 2C constant current rate, and the assessment of the modelling accuracy by comparison of the predicted battery cells voltage and temperature with respect to the experimental data is further presented. With this paper, thermal performances of battery cells prior and after long-term cycling are evaluated at the cycling temperature, next to the ambient temperature. Hence, thermal characterisation and modelling results are more closely reflecting that encountered by the battery cells in real cycling conditions, so that their performances are believed in this way to be more objectively evaluated. Full article
(This article belongs to the Special Issue Green Energy and Applications)
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Open AccessArticle Acoustic Scene Classification Using Efficient Summary Statistics and Multiple Spectro-Temporal Descriptor Fusion
Appl. Sci. 2018, 8(8), 1363; https://doi.org/10.3390/app8081363
Received: 12 February 2018 / Revised: 29 July 2018 / Accepted: 9 August 2018 / Published: 13 August 2018
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Abstract
This paper presents a novel approach for acoustic scene classification based on efficient acoustic feature extraction using spectro-temporal descriptors fusion. Grounded on the finding in neuroscience—“auditory system summarizes the temporal details of sounds using time-averaged statistics to understand acoustic scenes”, we devise an
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This paper presents a novel approach for acoustic scene classification based on efficient acoustic feature extraction using spectro-temporal descriptors fusion. Grounded on the finding in neuroscience—“auditory system summarizes the temporal details of sounds using time-averaged statistics to understand acoustic scenes”, we devise an efficient computational framework for sound scene classification by using multipe time-frequency descriptors fusion with discriminant information enhancement. To characterize rich information of sound, i.e., local structures on the time-frequency plane, we adopt 2-dimensional local descriptors. A more critical issue raised in how to logically ‘summarize’ those local details into a compact feature vector for scene classification. Although ‘time-averaged statistics’ is suggested by the psychological investigation, directly computing time average of local acoustic features is not a logical way, since arithmetic mean is vulnerable to extreme values which are anticipated to be generated by interference sounds which are irrelevant to the scene category. To tackle this problem, we develop time-frame weighting approach to enhance sound textures as well as to suppress scene-irrelevant events. Subsequently, robust acoustic feature for scene classification can be efficiently characterized. The proposed method had been validated by using Rouen dataset which consists of 19 acoustic scene categories with 3029 real samples. Extensive results demonstrated the effectiveness of the proposed scheme. Full article
(This article belongs to the Special Issue Computational Acoustic Scene Analysis)
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Open AccessArticle Antibacterial and Antifungal Activities of Proteins Extracted from Seven Different Snails
Appl. Sci. 2018, 8(8), 1362; https://doi.org/10.3390/app8081362
Received: 19 July 2018 / Revised: 3 August 2018 / Accepted: 11 August 2018 / Published: 13 August 2018
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Abstract
Snails have been used both as a food and as a treatment for a variety of medicinal conditions. In this study, seven different snail proteins were evaluated for their antimicrobial activity. Fresh water and land snails of seven different live species were collected
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Snails have been used both as a food and as a treatment for a variety of medicinal conditions. In this study, seven different snail proteins were evaluated for their antimicrobial activity. Fresh water and land snails of seven different live species were collected and identified. Crude proteins were extracted from seven different snails. The extracted proteins were estimated using Bradford’s method and snail proteins were displayed using a sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) analysis. The seven different snail proteins were evaluated for their antimicrobial activity against various pathogenic bacterial and fungal cultures by agar well diffusion method and MIC (Minimum Inhibitory Concentration). One of the most active, crude proteins was from land snail Cryptozona bistrialis and its protein was capable of completely inhibiting the development of pathogenic bacterial and fungal cultures. This study shows that the land snail C. bistrialis proteins could be used as an antibiotic in biomedical research. Full article
(This article belongs to the Section Applied Biosciences and Bioengineering)
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Open AccessArticle Fire Behavior of U-shaped Steel Beams Filled with Demolished Concrete Lumps and Fresh Concrete
Appl. Sci. 2018, 8(8), 1361; https://doi.org/10.3390/app8081361
Received: 3 July 2018 / Revised: 3 August 2018 / Accepted: 10 August 2018 / Published: 13 August 2018
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Abstract
To reuse waste concrete in a more straightforward and simplified way, a new kind of structural member containing fresh concrete (FC) and demolished concrete lumps (DCLs) distinctly larger than conventional recycled aggregates has been proposed. Previous research has shown that, at room temperature,
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To reuse waste concrete in a more straightforward and simplified way, a new kind of structural member containing fresh concrete (FC) and demolished concrete lumps (DCLs) distinctly larger than conventional recycled aggregates has been proposed. Previous research has shown that, at room temperature, the mechanical performance of the U-shaped steel beams filled with DCLs and FC is similar to that of the U-shaped steel beams filled with FC alone. This research explores the fire behavior of the U-shaped steel beams filled with DCLs and FC. Five specimens including three beams filled with DCLs and FC and two reference beams filled with FC alone were tested in fire. The experimental parameters included the replacement ratio of DCLs, the longitudinal reinforcement ratio, the load ratio, and the thickness of fire insulation. Based on the test results, numerical models in which the thermal resistance at the interface between the U-shaped steel and the in-filled concrete is considered are developed using SAFIR to determine the thermal and structural responses of the specimens. Lastly, parametric studies are carried out preliminarily to investigate the effects of some parameters on the fire resistance of such beams. It is found that the replacement ratio of DCLs within a range of 0% to 33% has a very limited effect on the temperature distribution, structural response, and fire resistance of the specimens, that embedding longitudinal reinforcements can significantly increase the fire resistance of such beams, that the interface thermal resistance can generate a temperature drop of up to 280 °C at the interface between the U-shaped steel and the in-filled concrete, and that the numerical models are capable of predicting the thermal and structural responses of such beams. Full article
(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)
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Open AccessArticle Design & Manufacture of a High-Performance Bicycle Crank by Additive Manufacturing
Appl. Sci. 2018, 8(8), 1360; https://doi.org/10.3390/app8081360
Received: 17 July 2018 / Revised: 7 August 2018 / Accepted: 7 August 2018 / Published: 13 August 2018
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Abstract
A new practical workflow for the laser Powder Bed Fusion (PBF) process, incorporating topological design, mechanical simulation, manufacture, and validation by computed tomography is presented, uniquely applied to a consumer product (crank for a high-performance racing bicycle), an approach that is tangible and
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A new practical workflow for the laser Powder Bed Fusion (PBF) process, incorporating topological design, mechanical simulation, manufacture, and validation by computed tomography is presented, uniquely applied to a consumer product (crank for a high-performance racing bicycle), an approach that is tangible and adoptable by industry. The lightweight crank design was realised using topology optimisation software, developing an optimal design iteratively from a simple primitive within a design space and with the addition of load boundary conditions (obtained from prior biomechanical crank force–angle models) and constraints. Parametric design modification was necessary to meet the Design for Additive Manufacturing (DfAM) considerations for PBF to reduce build time, material usage, and post-processing labour. Static testing proved performance close to current market leaders with the PBF manufactured crank found to be stiffer than the benchmark design (static load deflection of 7.0 ± 0.5 mm c.f. 7.67 mm for a Shimano crank at a competitive mass (155 g vs. 175 g). Dynamic mechanical performance proved inadequate, with failure at 2495 ± 125 cycles; the failure mechanism was consistent in both its form and location. This research is valuable and novel as it demonstrates a complete workflow from design, manufacture, post-treatment, and validation of a highly loaded PBF manufactured consumer component, offering practitioners a validated approach to the application of PBF for components with application outside of the accepted sectors (aerospace, biomedical, autosports, space, and power generation). Full article
(This article belongs to the Special Issue 3D Printing of Metals)
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Open AccessArticle Study on the Dynamic Mechanical Properties of Viscoelastic Materials Based on Asymmetrical Sandwich Beams
Appl. Sci. 2018, 8(8), 1359; https://doi.org/10.3390/app8081359
Received: 11 July 2018 / Revised: 4 August 2018 / Accepted: 8 August 2018 / Published: 13 August 2018
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Abstract
A modified estimation method for the dynamic mechanical properties of viscoelastic materials via asymmetrical sandwich specimens is presented. In contrast to the traditional vibrating cantilever beam test method (VCBTM), the proposed method allows asymmetrical base beams in sandwich specimens. Based on the complex
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A modified estimation method for the dynamic mechanical properties of viscoelastic materials via asymmetrical sandwich specimens is presented. In contrast to the traditional vibrating cantilever beam test method (VCBTM), the proposed method allows asymmetrical base beams in sandwich specimens. Based on the complex stiffness method, complex parameters are introduced for general sandwich configurations. Calculation formulas for loss factor and shear modulus of the core material are presented. The effectiveness of this approach is validated numerically and experimentally by analysis of one symmetrical sandwich beam specimen and two specimens with asymmetrical thicknesses and materials. It is shown that dynamic mechanical parameters of the core material can be obtained regardless of sandwiches’ symmetry. The proposed method breaks the symmetrical criteria for sandwich specimens and may provide a wider application to measure viscoelastic materials’ dynamic properties. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle An Improved Analytical Algorithm on Main Cable System of Suspension Bridge
Appl. Sci. 2018, 8(8), 1358; https://doi.org/10.3390/app8081358
Received: 11 July 2018 / Revised: 4 August 2018 / Accepted: 7 August 2018 / Published: 13 August 2018
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Abstract
This paper develops an improved analytical algorithm on the main cable system of suspension bridge. A catenary cable element is presented for the nonlinear analysis on main cable system that is subjected to static loadings. The tangent stiffness matrix and internal force vector
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This paper develops an improved analytical algorithm on the main cable system of suspension bridge. A catenary cable element is presented for the nonlinear analysis on main cable system that is subjected to static loadings. The tangent stiffness matrix and internal force vector of the element are derived explicitly based on the exact analytical expressions of elastic catenary. Self-weight of the cables can be directly considered without any approximations. The effect of pre-tension of cable is also included in the element formulation. A search algorithm with the penalty factor is introduced to identify the initial components for convergence with high precision and fast speed. Numerical examples are presented and discussed to illustrate the accuracy and efficiency of the proposed analytical algorithm. Full article
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Open AccessArticle Development of an Internet of Things Based Electrochemical Microfluidic System for Free Calcium Detection
Appl. Sci. 2018, 8(8), 1357; https://doi.org/10.3390/app8081357
Received: 20 July 2018 / Revised: 6 August 2018 / Accepted: 7 August 2018 / Published: 13 August 2018
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Abstract
This paper represents the design, fabrication, and implementation of an Internet of Things (IoT)-based electrochemical microfluidic system for free calcium concentration detection with a 3D printing technique. Free calcium solutions with desired concentrations between 0 and 40 µM can be obtained. The solutions
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This paper represents the design, fabrication, and implementation of an Internet of Things (IoT)-based electrochemical microfluidic system for free calcium concentration detection with a 3D printing technique. Free calcium solutions with desired concentrations between 0 and 40 µM can be obtained. The solutions were used to calibrate the system by using an impedance analyzer for monitoring the impedance change to determine the operating frequency. Continuously, an IoT enabled point of care device was used for real-time detection and to send signals to the cloud for sharing. The relationship between the concentration and reactance are y = 1.3812 Lgx + 0.9809 at a wavelength of 450 Hz, with an R2 of 0.9719. We measured the calcium concentration changing from 39.8 µM to 1.35 µM (nearly real-time) by the PoC device and showed the concentration changes resulting with time on the cell phone app. The results depicted in this paper provide a strong platform for the precise and real-time monitoring of different biomedical samples. Full article
(This article belongs to the Section Applied Biosciences and Bioengineering)
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Open AccessArticle Efficiency of Cassava Production in China: Empirical Analysis of Field Surveys from Six Provinces
Appl. Sci. 2018, 8(8), 1356; https://doi.org/10.3390/app8081356
Received: 13 July 2018 / Revised: 5 August 2018 / Accepted: 10 August 2018 / Published: 13 August 2018
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Abstract
Cassava is becoming increasingly important as an industrial raw material in China. However, an insufficient supply of cassava raw materials and the expanding demand for cassava in downstream-processing industries restricts the development of the cassava industry in China. This paper studies how to
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Cassava is becoming increasingly important as an industrial raw material in China. However, an insufficient supply of cassava raw materials and the expanding demand for cassava in downstream-processing industries restricts the development of the cassava industry in China. This paper studies how to increase the scale of cassava planting and promoting cassava production efficiency using output-oriented Data Envelopment Analysis (DEA) modeling. Overall Technical Efficiency (OTE), Pure Technical Efficiency (PTE), and Scale Efficiencies (SE) of the cassava-production system in the major cassava production areas of China are calculated using Variable Returns to Scale (VRS). Results reveal that, in addition to the Guangdong province, the OTE of Guangxi, Hainan, Fujian, Yunnan, and Jiangxi is inefficient, with an OTE of less than 1. The largest cassava-planting province, Guangxi, has the lowest SE with 0.551. The PTE of Guangxi is close to the minimum with 0.344. The OTE of Guangxi is also the lowest among the five provinces with 0.190. This study also presents ways to improve production efficiency. Results reveal that Guangxi has a large ratio of transverse adjustment on average. In the Guangxi province, 1.70% of the service cost and 1.72% of the labor cost need to be eliminated to keep the current output scale. Meanwhile, service and labor costs need to be reduced by 3164.85 and 3209.92, respectively, to achieve the best production efficiency. Further industrialization and large-scale cassava cultivation, increased yield, and strengthened cooperation with the Association of South East Asian Nations (ASEAN) and Africa are suggested as policy options to improve the cassava system in China. Full article
(This article belongs to the Section Environmental and Sustainable Science and Technology)
Open AccessArticle A Trajectory Planning Method for Polishing Optical Elements Based on a Non-Uniform Rational B-Spline Curve
Appl. Sci. 2018, 8(8), 1355; https://doi.org/10.3390/app8081355
Received: 10 July 2018 / Revised: 1 August 2018 / Accepted: 10 August 2018 / Published: 12 August 2018
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Abstract
Optical polishing can accurately correct the surface error through controlling the dwell time of the polishing tool on the element surface. Thus, the precision of the trajectory and the dwell time (the runtime of the trajectory) are important factors affecting the polishing quality.
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Optical polishing can accurately correct the surface error through controlling the dwell time of the polishing tool on the element surface. Thus, the precision of the trajectory and the dwell time (the runtime of the trajectory) are important factors affecting the polishing quality. This study introduces a systematic interpolation method for optical polishing using a non-uniform rational B-spline (NURBS). A numerical method for solving all the control points of NURBS was proposed with the help of a successive over relaxation (SOR) iterative theory, to overcome the problem of large computation. Then, an optimisation algorithm was applied to smooth the NURBS by taking the shear jerk as the evaluation index. Finally, a trajectory interpolation scheme was investigated for guaranteeing the precision of the trajectory runtime. The experiments on a prototype showed that, compared to the linear interpolation method, there was an order of magnitude improvement in interpolation, and runtime, errors. Correspondingly, the convergence rate of the surface error of elements improved from 37.59% to 44.44%. Full article
(This article belongs to the Special Issue Advanced Mobile Robotics)
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Open AccessArticle Inverse Analysis of Cellulose by Using the Energy-Based Method and a Rotational Rheometer
Appl. Sci. 2018, 8(8), 1354; https://doi.org/10.3390/app8081354
Received: 25 July 2018 / Revised: 7 August 2018 / Accepted: 10 August 2018 / Published: 12 August 2018
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Abstract
Biological and polymer-type materials usually show a complicated deformation behavior. This behavior can be modeled by using a nonlinear material equation; however, the determination of coefficients in such a material equation is challenging. We exploit representation theorems in continuum mechanics and construct nonlinear
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Biological and polymer-type materials usually show a complicated deformation behavior. This behavior can be modeled by using a nonlinear material equation; however, the determination of coefficients in such a material equation is challenging. We exploit representation theorems in continuum mechanics and construct nonlinear material equations for cellulose in an oscillatory rheometer experiment. The material parameters are obtained by using the energy-based method that generates a linear regression fit even in the case of a highly nonlinear material equation. This method allows us to test different nonlinear material equations and choose the simplest material model capable of representing the nonlinear response over a broad range of frequencies and amplitudes. We present the strategy, determine the parameters for cellulose, discuss the complicated stress-strain response and make the algorithm publicly available to encourage its further use. Full article
(This article belongs to the Section Materials)
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Open AccessArticle The Comparative Study on Cutting Performance of Different-Structure Milling Cutters in Machining CFRP
Appl. Sci. 2018, 8(8), 1353; https://doi.org/10.3390/app8081353
Received: 24 July 2018 / Revised: 31 July 2018 / Accepted: 9 August 2018 / Published: 12 August 2018
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Abstract
Carbon fiber reinforced plastic (CFRP) is typically hard to process, because it is easy for it to generate processing damage such as burrs, tears, delamination, and so on in the machining process. Consequently, this restricts its wide spread application. This paper conducted a
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Carbon fiber reinforced plastic (CFRP) is typically hard to process, because it is easy for it to generate processing damage such as burrs, tears, delamination, and so on in the machining process. Consequently, this restricts its wide spread application. This paper conducted a comparative experiment on the cutting performance of the two different-structure milling cutters, with a helical staggered edge and a rhombic edge, in milling carbon fiber composites; analyzed the wear morphologies of the two cutting tools; and thus acquired the effect of the tool structure on the machined surface quality and cutting force. The results indicated that in the whole cutting, the rhombic milling cutter with a segmented cutting edge showed better wear resistance and a more stable machined surface quality. It was not until a large area of coating shedding occurred, along with chip clogging, that the surface quality decreased significantly. At the stage of coating wear, the helical staggered milling cutter with an alternately arranged continuous cutting edge showed better machined surface quality, but when the coating fell off, its machined surface quality began to reveal damage such as groove, tear, and fiber pullout. Meanwhile, burrs occurred at the edge and the cutting force obviously increased. By contrast, for the rhombic milling cutter, both the surface roughness and cutting force increased relatively slowly. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Novel Bionanocellulose/κ-Carrageenan Composites for Tissue Engineering
Appl. Sci. 2018, 8(8), 1352; https://doi.org/10.3390/app8081352
Received: 26 June 2018 / Revised: 1 August 2018 / Accepted: 9 August 2018 / Published: 12 August 2018
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Abstract
In this work, novel bacterial cellulose/κ-carrageenan (BNC/κ-Car) composites, being potential scaffolds for tissue engineering (TE), and outperforming the two polymers when used as scaffolds separately, were for the first time obtained using an in situ method, based on the stationary culture of bacteria
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In this work, novel bacterial cellulose/κ-carrageenan (BNC/κ-Car) composites, being potential scaffolds for tissue engineering (TE), and outperforming the two polymers when used as scaffolds separately, were for the first time obtained using an in situ method, based on the stationary culture of bacteria Komagateibacter xylinus E25. The composites were compared with native BNC in terms of the morphology of fibers, chemical composition, crystallinity, tensile and compression strength, water holding capacity, water retention ratio and swelling properties. Murine chondrogenic ATDC5 cells were applied to assess the utility of the BNC/κ-Car composites as potential scaffolds. The impact of the composites on the cells viability, chondrogenic differentiation, and expression patterns of Col1α1, Col2α1, Runx2, and Sox9, which are indicative of ATDC5 chondrogenic differentiation, was determined. None of the composites obtained in this study caused the chondrocyte hypertrophy. All of them supported the differentiation of ATDC5 cells to more chondrogenic phenotype. Full article
(This article belongs to the Special Issue Bacterial Cellulose Composites)
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Open AccessArticle Optimized Multiport DC/DC Converter for Vehicle Drivetrains: Topology and Design Optimization
Appl. Sci. 2018, 8(8), 1351; https://doi.org/10.3390/app8081351
Received: 20 June 2018 / Revised: 7 August 2018 / Accepted: 9 August 2018 / Published: 11 August 2018
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Abstract
DC/DC Multiport Converters (MPC) are gaining interest in the hybrid electric drivetrains (i.e., vehicles or machines), where multiple sources are combined to enhance their capabilities and performances in terms of efficiency, integrated design and reliability. This hybridization will lead to more complexity and
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DC/DC Multiport Converters (MPC) are gaining interest in the hybrid electric drivetrains (i.e., vehicles or machines), where multiple sources are combined to enhance their capabilities and performances in terms of efficiency, integrated design and reliability. This hybridization will lead to more complexity and high development/design time. Therefore, a proper design approach is needed to optimize the design of the MPC as well as its performance and to reduce development time. In this research article, a new design methodology based on a Multi-Objective Genetic Algorithm (MOGA) for non-isolated interleaved MPCs is developed to minimize the weight, losses and input current ripples that have a significant impact on the lifetime of the energy sources. The inductor parameters obtained from the optimization framework is verified by the Finite Element Method (FEM) COMSOL software, which shows that inductor weight of optimized design is lower than that of the conventional design. The comparison of input current ripples and losses distribution between optimized and conventional designs are also analyzed in detailed, which validates the perspective of the proposed optimization method, taking into account emerging technologies such as wide bandgap semiconductors (SiC, GaN). Full article
(This article belongs to the Special Issue Plug-in Hybrid Electric Vehicle (PHEV))
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Open AccessFeature PaperArticle Novel Transient Power Control Schemes for BTB VSCs to Improve Angle Stability
Appl. Sci. 2018, 8(8), 1350; https://doi.org/10.3390/app8081350
Received: 20 June 2018 / Revised: 7 August 2018 / Accepted: 8 August 2018 / Published: 11 August 2018
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Abstract
This paper proposes two novel power control strategies to improve the angle stability of generators using a Back-to-Back (BTB) system-based voltage source converter (VSC). The proposed power control strategies have two communication systems: a bus angle monitoring system and a special protection system
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This paper proposes two novel power control strategies to improve the angle stability of generators using a Back-to-Back (BTB) system-based voltage source converter (VSC). The proposed power control strategies have two communication systems: a bus angle monitoring system and a special protection system (SPS), respectively. The first power control strategy can emulate the behaviour of the ac transmission to improve the angle stability while supporting the ac voltage at the primary level of the control structure. The second power control scheme uses an SPS signal to contribute stability to the power system under severe contingencies involving the other generators. The results for the proposed control scheme were validated using the PSS/E software package with a sub-module written in the Python language, and the simple assistant power control with two communication systems is shown to improve the angle stability. In conclusion, BTB VSCs can contribute their power control strategies to ac grid in addition to offering several existing advantages, which makes them applicable for use in the commensurate protection of large ac grid. Full article
(This article belongs to the Special Issue HVDC for Grid Services in Electric Power Systems)
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Open AccessArticle Partial Block Scheme and Adaptive Update Model for Kernelized Correlation Filters-Based Object Tracking
Appl. Sci. 2018, 8(8), 1349; https://doi.org/10.3390/app8081349
Received: 30 May 2018 / Revised: 6 August 2018 / Accepted: 7 August 2018 / Published: 10 August 2018
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Abstract
In visual object tracking, the dynamic environment is a challenging issue. Partial occlusion and scale variation are typical challenging problems. We present a correlation-based object tracking based on the discriminative model. To attenuate the influence by partial occlusion, partial sub-blocks are constructed from
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In visual object tracking, the dynamic environment is a challenging issue. Partial occlusion and scale variation are typical challenging problems. We present a correlation-based object tracking based on the discriminative model. To attenuate the influence by partial occlusion, partial sub-blocks are constructed from the original block, and each of them operates independently. The scale space is employed to deal with scale variation using a feature pyramid. We also present an adaptive update model with a weighting function to calculate the frame-adaptive learning rate. Theoretical analysis and experimental results demonstrate that the proposed method can robustly track drastic deformed objects. The sparse update reduces the computational cost for real-time tracking. Although the partial block scheme generation increases the computational cost, we present a novel sparse update approach to reduce the computational cost drastically for real-time tracking. The experiments were performed on a variety of sequences, and the proposed method exhibited better performance compared with the state-of-the-art trackers. Full article
(This article belongs to the Special Issue Advanced Intelligent Imaging Technology)
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