Applied Sciences

20 pages, 7315 KiB

Open AccessFeature PaperArticle

The Effects of Camelina “Soheil” as a Novel Biodiesel Fuel on the Performance and Emission Characteristics of Diesel Engine

by Seyed Salar Hoseini, Gholamhassam Najafi, Barat Ghobadian, Talal Yusaf and Mohammad Taghi Ebadi

Appl. Sci. 2018, 8(6), 1010; https://doi.org/10.3390/app8061010 - 20 Jun 2018

Cited by 14 | Viewed by 5185

Abstract

In this research, a new cultivar of Camelina “Soheil” seed oil (CSO) was investigated as a novel feedstock for biodiesel production. Maximum oil content of CSO seed was about 29%. Physical and chemical characteristics of CSO were investigated. The biodiesel production process was [...] Read more.

In this research, a new cultivar of Camelina “Soheil” seed oil (CSO) was investigated as a novel feedstock for biodiesel production. Maximum oil content of CSO seed was about 29%. Physical and chemical characteristics of CSO were investigated. The biodiesel production process was optimized by using the response surface methodology (RSM) reaction parameters, including molar ratio (methanol to oil), reaction time, and concentration of catalyst are studied. The result showed that the conversion of biodiesel was 98.91% under the optimized conditions of 10.18:1 molar ratio and 1.15 wt % concentration of catalyst for a reaction time of 7.33 min. By investigating the properties of the fuel, it turned out that biodiesel from new cultivar of CSO oil complied with the limits prescribed in the ASTM D6751 standards, and that this seed oil could be introduced as a new feedstock for biodiesel production. Also, the performance and emission of a diesel engine were investigated with CSO biodiesel. All of the engine experiments were performed under the constant speed of 2100 rpm at loads of 0%, 25%, 50%, 75%, and 100%. Results indicated that by using the biodiesel-diesel blends, the brake power, and the CO₂ and NOx emissions increased, while the SFC and CO and UHC emissions decreased. Full article

(This article belongs to the Special Issue Renewable Fuels)

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17 pages, 2943 KiB

Open AccessArticle

Laboratory Evaluation on Performance of Compound-Modified Asphalt for Rock Asphalt/Styrene–Butadiene Rubber (SBR) and Rock Asphalt/Nano-CaCO₃

by Songtao Lv, Shuangshuang Wang, Tong Guo, Chengdong Xia, Jianglong Li and Gui Hou

Appl. Sci. 2018, 8(6), 1009; https://doi.org/10.3390/app8061009 - 20 Jun 2018

Cited by 32 | Viewed by 4869

Abstract

As a natural modifier of asphalt, rock asphalt has been widely used to improve its thermal stability and aging resistance. However, the thermal cracking resistance of asphalt modified by rock asphalt is unsatisfactory. In order to improve the thermal cracking resistance in low [...] Read more.

As a natural modifier of asphalt, rock asphalt has been widely used to improve its thermal stability and aging resistance. However, the thermal cracking resistance of asphalt modified by rock asphalt is unsatisfactory. In order to improve the thermal cracking resistance in low temperature, two kinds of modifiers—styrene–butadiene rubber (SBR) and nano-CaCO₃—were selected as the compound modifiers, and then implemented to improve the low-temperature performance of the binder. Then, compound asphalt modified by Buton rock asphalt (BRA) was chosen as the study subject. The thermal stability and aging resistance of asphalt modified by BRA, compound-modified asphalt by BRA/SBR, and compound-modified asphalt by BRA and nano-CaCO₃ were determined to identify whether the compound modifiers in the asphalt would have a negative effect on the thermal stability and aging resistance of the asphalt. The dynamic shear rheometer (DSR) test was employed to evaluate the thermal stability. The thin film oven test (TFOT) and pressure aging vessel (PAV) were adopted to determine the aging resistance. The viscoelastic characteristics of asphalt with and without modifiers were revealed to evaluate the low-temperature crack resistance of asphalt modified by compound modifiers. The bending beam rheometer (BBR) creep test was conducted in three test temperatures in order to determine the creep stiffness modulus of the BRA compound-modified asphalt. The viscoelastic model considering the damage caused by loading was established; then, the creep compliance and parameters of the viscoelastic damage model were implemented to evaluate the low-temperature performance of the compound-modified asphalt. The results show that the compound modifiers have little negative effects on the thermal stability and aging resistance of asphalt. The thermal crack resistance of the compound-modified asphalt by BRA/SBR was the best, followed by the compound-modified asphalt by BRA and nano-CaCO₃ within the three materials. The accuracy of forecasting the characteristics of compound-modified asphalt was improved by using the viscoelastic model and considering the damage effect. Full article

(This article belongs to the Special Issue Achievements and Prospects of Functional Pavement: Materials and Structures)

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Graphical abstract

17 pages, 3806 KiB

Open AccessArticle

Modelling Shear Induced Diffusion Based Particle Segregation: A Basis for Novel Separation Technology

by Ivon Drijer and Karin Schroën

Appl. Sci. 2018, 8(6), 1008; https://doi.org/10.3390/app8061008 - 20 Jun 2018

Cited by 8 | Viewed by 5028

Abstract

Shear induced diffusion (SID) based flow segregation is a technique that can be used for concentration and fractionation purposes, and it has the potential to become an economical and sustainable alternative for e.g., membrane separation. When compared to conventional microfiltration, problems related to [...] Read more.

Shear induced diffusion (SID) based flow segregation is a technique that can be used for concentration and fractionation purposes, and it has the potential to become an economical and sustainable alternative for e.g., membrane separation. When compared to conventional microfiltration, problems related to fouling and cleaning are expected to be minimal. To make the best use of the opportunities that this technique holds, detailed insights in flow and particle behavior are needed. Modelling this process allows for us to chart particle segregation in flow, as well as the effect of suspension removal through a pore and the restoration of the flow profile after the pore. As a starting point, we take the computation fluid dynamics (CFD) model that is presented in a previous study. A difference in channel height to particle diameter ratio influences the entrance length of the SID profile as well as its fully developed profile. When extracting liquid through one pore, particles are systematically transmitted at a lower concentration (59–78%) than is present in the bulk. The recovery lengths of the SID profile after the pore were short, and thus pores can be placed at realistic distances, which forms a good foundation for further design of this novel separation technology that will ultimately be applied for fractionation of particles taking relatively small differences in diffusive behavior as a starting point. Full article

(This article belongs to the Special Issue Modeling and Simulations for Membrane Processes of Industrial Interest)

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16 pages, 3009 KiB

Open AccessArticle

Modified LMS Strategies Using Internal Model Control for Active Noise and Vibration Control Systems

by Byeongil Kim and Jong-Yun Yoon

Appl. Sci. 2018, 8(6), 1007; https://doi.org/10.3390/app8061007 - 20 Jun 2018

Cited by 8 | Viewed by 4744

Abstract

Traditional adaptive filtering algorithms are non-recursive systems that cannot use a time-variant reference input in real time and are not appropriate for control signals with uncertainties and unanticipated conditions. The main purpose of this research is to design novel adaptive digital filtering algorithms [...] Read more.

Traditional adaptive filtering algorithms are non-recursive systems that cannot use a time-variant reference input in real time and are not appropriate for control signals with uncertainties and unanticipated conditions. The main purpose of this research is to design novel adaptive digital filtering algorithms based on internal model control (IMC). The new methods consist of a process model for the target plant so as to estimate its dynamic behavior for active vibration and noise attenuation schemes in order to improve the stability, robustness, and tracking performance. On the basis of on the existing least mean squares, the methods are combined with an internal model controller, or the whole adaptive filtering system could become a feedback control system structure based on IMC. The performances were validated in numerical simulations with various conditions that could have happened in realistic applications, and the results were compared with the original algorithms. This study shows that the active noise and vibration systems that are applied to vehicles, mechanical systems, and other targets are enhanced through improving the performance of conventional adaptive filtering algorithms and by using internal model control effectively. Full article

(This article belongs to the Special Issue Active and Passive Noise Control)

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9 pages, 2466 KiB

Open AccessArticle

Programmable Zoom Lens System with Two Spatial Light Modulators: Limits Imposed by the Spatial Resolution

by Jeffrey A. Davis, Trevor I. Hall, Ignacio Moreno, Jason P. Sorger and Don M. Cottrell

Appl. Sci. 2018, 8(6), 1006; https://doi.org/10.3390/app8061006 - 20 Jun 2018

Cited by 11 | Viewed by 4309

Abstract

In this work we present an experimental proof of concept of a programmable optical zoom lens system with no moving parts that can form images with both positive and negative magnifications. Our system uses two programmable liquid crystal spatial light modulators to form [...] Read more.

In this work we present an experimental proof of concept of a programmable optical zoom lens system with no moving parts that can form images with both positive and negative magnifications. Our system uses two programmable liquid crystal spatial light modulators to form the lenses composing the zoom system. The results included show that images can be formed with both positive and negative magnifications. Experimental results match the theory. We discuss the size limitations of this system caused by the limited spatial resolution and discuss how newer devices would shrink the size of the system. Full article

(This article belongs to the Special Issue Liquid Crystal on Silicon Devices: Modeling and Advanced Spatial Light Modulation Applications)

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15 pages, 2970 KiB

Open AccessArticle

The Use of Co-Precipitation to Produce Nano-Mn–Zn Ferrite ([Mn_xZn_1?x]Fe₂O₄) from Waste Batteries

by Yenchun Liu and Jarnchih Hsu

Appl. Sci. 2018, 8(6), 1005; https://doi.org/10.3390/app8061005 - 20 Jun 2018

Cited by 11 | Viewed by 4370

Abstract

This study uses pure materials or waste batteries to produce a nanoscale Mn–Zn ferrite. Acid is used to dissolve the battery into solution and then co-precipitation is used to produce nanoscale ferrite. When the calcination temperature in an air atmosphere exceeds 600 °C, [...] Read more.

This study uses pure materials or waste batteries to produce a nanoscale Mn–Zn ferrite. Acid is used to dissolve the battery into solution and then co-precipitation is used to produce nanoscale ferrite. When the calcination temperature in an air atmosphere exceeds 600 °C, α-Fe₂O₃ is generated and there is a decrease in the saturated magnetization. Using waste batteries to produce [Mn_0.54Zn_0.46]Fe₂O₄ at a pH of 10, the saturated magnetization is 62.85 M (emu/g), which is optimal. At a pH of 10, the particulate diameter is largest, at about 40 nm. The stronger the crystal phase of Mn–Zn ferrite, the greater is the saturated magnetization. The ferrite crystal phase is analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM) and a vibrating sample magnetometer (VSM). The stronger the crystal phase, the larger is the average particulate diameter. The magnetic properties, the particulate diameter and the magnetic flux density of ferrite powders that are prepared under different conditions are studied. [Mn_xZn_1−x]Fe₂O₄ ferrite powders can be used as an iron core and as resonance imaging materials. Full article

(This article belongs to the Section Materials Science and Engineering)

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22 pages, 15804 KiB

Open AccessArticle

Evaluation of the Implicit Gradient-Enhanced Regularization of a Damage-Plasticity Rock Model

by Magdalena Schreter, Matthias Neuner and Günter Hofstetter

Appl. Sci. 2018, 8(6), 1004; https://doi.org/10.3390/app8061004 - 20 Jun 2018

Cited by 23 | Viewed by 4736

Abstract

In the present publication, the performance of an implicit gradient-enhanced damage-plasticity model is evaluated with special focus on the prediction of complex failure modes such as shear failure. Hence, it complements studies on predominant mode I failure frequently found in the literature. To [...] Read more.

In the present publication, the performance of an implicit gradient-enhanced damage-plasticity model is evaluated with special focus on the prediction of complex failure modes such as shear failure. Hence, it complements studies on predominant mode I failure frequently found in the literature. To this end, an implicit gradient-enhanced damage-plasticity rock model is presented and validated by means of 2D and 3D finite element simulations of both laboratory tests on intact rock specimens as well as a large-scale structural benchmark related to failure of rock mass. Thereby, a wide range of loading conditions comprising unconfined and/or confined, tensile and/or compressive stress states is considered. The capability of the gradient-enhanced rock model for representing the mechanical response objectively with respect to the finite element discretization and realistically compared to measurement data is assessed. It is shown that complex failure modes and the respective load–displacement curves are predicted in a mesh-insensitive manner. Full article

(This article belongs to the Special Issue Computational Methods for Fracture)

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13 pages, 2211 KiB

Open AccessArticle

Stability of Cu-Precipitates in Al-Cu Alloys

by Torsten E. M. Staab, Paola Folegati, Iris Wolfertz and Martti J. Puska

Appl. Sci. 2018, 8(6), 1003; https://doi.org/10.3390/app8061003 - 20 Jun 2018

Cited by 8 | Viewed by 5547

Abstract

We present first principle calculations on formation and binding energies for Cu and Zn as solute atoms forming small clusters up to nine atoms in Al-Cu and Al-Zn alloys. We employ a density-functional approach implemented using projector-augmented waves and plane wave expansions. We [...] Read more.

We present first principle calculations on formation and binding energies for Cu and Zn as solute atoms forming small clusters up to nine atoms in Al-Cu and Al-Zn alloys. We employ a density-functional approach implemented using projector-augmented waves and plane wave expansions. We find that some structures, in which Cu atoms are closely packed on {100}-planes, turn out to be extraordinary stable. We compare the results with existing numerical or experimental data when possible. We find that Cu atoms precipitating in the form of two-dimensional platelets on {100}-planes in the fcc aluminum are more stable than three-dimensional structures consisting of the same number of Cu-atoms. The preference turns out to be opposite for Zn in Al. Both observations are in agreement with experimental observations. Full article

(This article belongs to the Special Issue Mechanical Behaviour of Aluminium Alloys)

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Configuration of Cu-atoms in 2D platelets on the <math display="inline"><semantics> <mrow> <mo>{</mo> <mn>100</mn> <mo>}</mo> </mrow> </semantics></math>-plane in fcc Al. The Cu and Al atoms are shown by red and grey spheres, respectively. The numbering indicates how the Cu-platelets were assumed to grow. The left and right patterns show the sequences 1 and 2 used in the calculations, respectively. Full article ">Figure 2
Energy gain during Cu-cluster growth for a supercell of 108 atoms in sequences 1 and 2. (left) The energy gain due to the last attached Cu atom, (right) the total energy gain per Cu atom in the growing cluster. Sequences 1 and 2 are explained in <a href="#applsci-08-01003-f001" class="html-fig">Figure 1</a>. Full article ">Figure 3
Energy gain during Cu-cluster growth. Results corresponding to supercells of 108, 128, and 192 atoms are compared. (left) Energy gain due to the last Cu atom attached, and (right) total energy gain per Cu-atom of a growing cluster. Sequence 1 is explained in <a href="#applsci-08-01003-f001" class="html-fig">Figure 1</a>. Full article ">Figure 4
Energy gain during Cu-cluster growth. The results corresponding to the supercells of 108, 128, and 192 atoms are compared. (left) Energy gain of the last Cu atom attached, (right) total energy gain per Cu-atom of a growing cluster. Sequence 2 is explained in <a href="#applsci-08-01003-f001" class="html-fig">Figure 1</a>. Full article ">Figure 5
Relaxation patterns of growing clusters. (left) Two copper atoms (red spheres) on 1NN position, (right) five Cu-atoms arranged as a platelet on the <math display="inline"><semantics> <mrow> <mo>{</mo> <mn>100</mn> <mo>}</mo> </mrow> </semantics></math>-plane. The Al atoms having two or more bonds to Cu-atoms are plotted in dark-grey color. The relaxation of the Al-layer above and below towards the Cu-atoms on the <math display="inline"><semantics> <mrow> <mo>{</mo> <mn>100</mn> <mo>}</mo> </mrow> </semantics></math>-plane clearly increases with the number of agglomerated Cu-aotms. Full article ">Figure 6
Total energies calculated by using static (atoms fixed) and relaxed configurations of a supercell of 108 atoms. Full article ">Figure 7
Binding energies of Zn atoms in 2D and 3D Zn clusters. (left) The binding energy for the last attached Zn atom. (right) The binding energy per Zn atom in the cluster. Full article ">

11 pages, 3396 KiB

Open AccessArticle

Manufacturing of Non-Stick Molds from Pre-Painted Aluminum Sheets via Single Point Incremental Forming

by Oscar Rodriguez-Alabanda, Miguel A. Narvaez, Guillermo Guerrero-Vaca and Pablo E. Romero

Appl. Sci. 2018, 8(6), 1002; https://doi.org/10.3390/app8061002 - 20 Jun 2018

Cited by 6 | Viewed by 4593

Abstract

The process of single point incremental formation (SPIF) awakens interest in the industry of mold manufacturing for the food industry. By means of SPIF, it is possible to generate short series of molds or mold prototypes at low cost. However, these industries require [...] Read more.

The process of single point incremental formation (SPIF) awakens interest in the industry of mold manufacturing for the food industry. By means of SPIF, it is possible to generate short series of molds or mold prototypes at low cost. However, these industries require such molds to be functional (non-sticky) and to have an adequate geometry accuracy. This study presents a technique that enables direct manufacturing of molds from pre-coated sheets with non-stick resins. It has also studied the influence of two technological variables in the process (feed-rate and pitch) for different geometrical parameters of the mold. Low values of these variables result in a lower overall error in the profile obtained. However, in order to obtain greater detail in particular parameters (angles, depth), it is necessary to use higher values of feed-rate and pitch. Full article

(This article belongs to the Special Issue Mechanical Behaviour of Aluminium Alloys)

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9 pages, 1064 KiB

Open AccessArticle

Automatic Bowel Motility Evaluation Technique for Noncontact Sound Recordings

by Ryunosuke Sato, Takahiro Emoto, Yuki Gojima and Masatake Akutagawa

Appl. Sci. 2018, 8(6), 999; https://doi.org/10.3390/app8060999 - 19 Jun 2018

Cited by 12 | Viewed by 4589

Abstract

Information on bowel motility can be obtained via magnetic resonance imaging (MRI)s and X-ray imaging. However, these approaches require expensive medical instruments and are unsuitable for frequent monitoring. Bowel sounds (BS) can be conveniently obtained using electronic stethoscopes and have recently been employed [...] Read more.

Information on bowel motility can be obtained via magnetic resonance imaging (MRI)s and X-ray imaging. However, these approaches require expensive medical instruments and are unsuitable for frequent monitoring. Bowel sounds (BS) can be conveniently obtained using electronic stethoscopes and have recently been employed for the evaluation of bowel motility. More recently, our group proposed a novel method to evaluate bowel motility on the basis of BS acquired using a noncontact microphone. However, the method required manually detecting BS in the sound recordings, and manual segmentation is inconvenient and time consuming. To address this issue, herein, we propose a new method to automatically evaluate bowel motility for noncontact sound recordings. Using simulations for the sound recordings obtained from 20 human participants, we showed that the proposed method achieves an accuracy of approximately 90% in automatic bowel sound detection when acoustic feature power-normalized cepstral coefficients are used as inputs to artificial neural networks. Furthermore, we showed that bowel motility can be evaluated based on the three acoustic features in the time domain extracted by our method: BS per minute, signal-to-noise ratio, and sound-to-sound interval. The proposed method has the potential to contribute towards the development of noncontact evaluation methods for bowel motility. Full article

(This article belongs to the Special Issue Modelling, Simulation and Data Analysis in Acoustical Problems)

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18 pages, 2757 KiB

Open AccessArticle

A Versatile Velocity Map Ion-Electron Covariance Imaging Spectrometer for High-Intensity XUV Experiments

by Linnea Rading, Jan Lahl, Sylvain Maclot, Filippo Campi, Hélène Coudert-Alteirac, Bart Oostenrijk, Jasper Peschel, Hampus Wikmark, Piotr Rudawski, Mathieu Gisselbrecht and Per Johnsson

Appl. Sci. 2018, 8(6), 998; https://doi.org/10.3390/app8060998 - 19 Jun 2018

Cited by 13 | Viewed by 6740

Abstract

We report on the design and performance of a velocity map imaging (VMI) spectrometer optimized for experiments using high-intensity extreme ultraviolet (XUV) sources such as laser-driven high-order harmonic generation (HHG) sources and free-electron lasers (FELs). Typically exhibiting low repetition rates and high single-shot [...] Read more.

We report on the design and performance of a velocity map imaging (VMI) spectrometer optimized for experiments using high-intensity extreme ultraviolet (XUV) sources such as laser-driven high-order harmonic generation (HHG) sources and free-electron lasers (FELs). Typically exhibiting low repetition rates and high single-shot count rates, such experiments do not easily lend themselves to coincident detection of photo-electrons and -ions. In order to obtain molecular frame or reaction channel-specific information, one has to rely on other correlation techniques, such as covariant detection schemes. Our device allows for combining different photo-electron and -ion detection modes for covariance analysis. We present the expected performance in the different detection modes and present the first results using an intense high-order harmonic generation (HHG) source. Full article

(This article belongs to the Special Issue Extreme Time Scale Photonics)

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16 pages, 2822 KiB

Open AccessArticle

Spatial Magnetic-Field Description Method Aimed at 2 × 25 kV Auto-Transformer Power Supply System in High-Speed Railway

by Yunchuan Deng, Ke Huang, Dongdong Su and Zhigang Liu

Appl. Sci. 2018, 8(6), 997; https://doi.org/10.3390/app8060997 - 19 Jun 2018

Cited by 4 | Viewed by 3451

Abstract

Complete and accurate spatial magnetic field description is the premise of effectively assessing the power supply capability of a high-speed railway (HSR). Its evaluation indicators are the current distributions and the integrated impedance of traction network. This paper proposes a spatial magnetic-field description [...] Read more.

Complete and accurate spatial magnetic field description is the premise of effectively assessing the power supply capability of a high-speed railway (HSR). Its evaluation indicators are the current distributions and the integrated impedance of traction network. This paper proposes a spatial magnetic-field description method for the auto-transformer (AT) power supply system. Due to the limitations of previous approaches, all the real loop circuits of the AT system are considered for structuring a loop circuit matrix. At first, different description processes are divided, respectively, into those for the right side and the left side of the load. Then, considering that two types of return conductors exist in an AT system, a certain current ratio deduced in existing studies is introduced. As the introduced current ratio of the left side of the load is approximate, an iterative scheme is adopted. By constantly adjusting current ratio to satisfy a constraint condition of circuit voltages, accurate traction network impedance is obtained. Last, in order to verify the effectiveness of the proposed description method, two real-life experiments in a Chinese HSR line are performed, which indicate that the proposed method can not only directly reflect complete and accurate current distribution, but also deduce the exact traction network integrated impedance. Full article

(This article belongs to the Section Energy Science and Technology)

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15 pages, 1675 KiB

Open AccessArticle

CO₂ Capture by Alkaline Solution for Carbonate Production: A Comparison between a Packed Column and a Membrane Contactor

by Israel Ruiz Salmón, Nicolas Cambier and Patricia Luis

Appl. Sci. 2018, 8(6), 996; https://doi.org/10.3390/app8060996 - 19 Jun 2018

Cited by 45 | Viewed by 10753

Abstract

A comparison between a traditional packed column and a novel membrane contactor used for CO₂ absorption with carbonate production is addressed in this paper. Membrane technology is generally characterized by a lower energy consumption, it offers an independent control of gas and [...] Read more.

A comparison between a traditional packed column and a novel membrane contactor used for CO₂ absorption with carbonate production is addressed in this paper. Membrane technology is generally characterized by a lower energy consumption, it offers an independent control of gas and liquid streams, a known interfacial area and avoids solvent dragging. Those advantages make it a potential substitute of conventional absorption towers. The effect of the concentration and the flow rates of both the flue gas (10–15% of CO₂) and the alkaline sorbent (NaOH, NaOH/Na₂CO₃) on the variation of the species present in the system, the mass transfer coefficient, and the CO₂ removal efficiency was evaluated. Under the studied operation conditions, the membrane contactor showed very competitive results with the conventional absorption column, even though the highest mass transfer coefficient was found in the latter technology. In addition, the membrane contactor offers an intensification factor higher than five due to its compactness and modular character. Full article

(This article belongs to the Special Issue Carbon Capture Utilization and Sequestration (CCUS))

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Experimental set ups for CO2 capture. Full article ">Figure 2
Evolution of inlet (a) and outlet (b) species concentration as a function of time in the packed column. CO2 and NaOH initial concentrations are 10% and 0.2 mol L−1, respectively; gas and liquid flow rates are 33 and 1 L min−1; respectively. Full article ">Figure 3
Evolution of inlet (a) and outlet (b) species concentration as a function of time in the membrane contactor. CO2 and NaOH initial concentrations are 10% and 0.2 mol L−1, respectively; gas and liquid flow rates are 6.5 and 1 L min−1; respectively. Full article ">Figure 4
Mass transfer coefficient in function of the NaOH flow rate for different flue gas flow rates in the two set ups. The CO2 and NaOH initial concentrations are 10% and 0.2 mol L−1, respectively, for all the cases except the experimental point corresponding to 23.7 L min−1 gas (membrane) and 3 L min−1 of NaOH flowrate, where it was used as 15% of CO2. Full article ">Figure 5
(a) Mass transfer coefficient in function of the NaOH initial concentration in the solvent for different CO2 concentrations in the flue gas in the two set ups; (b) CO2 removal efficiency. The solvent and the flue gas flow rates in the column and the membrane contactor are 5 and 33 L min−1 and 1 and 23.5 L min−1, respectively. Full article ">Figure 6
(a) Mass transfer coefficient in function of the %NaOH in the liquid solution in the two set ups; (b) Zoom of the bottom part of <a href="#applsci-08-00996-f006" class="html-fig">Figure 6</a>a. Full article ">Figure A1
Pressure drop as a function of the air flow rate for different liquid flow rates. Full article ">Figure A2
Pressure drop as a function of the gas flow rate for two configurations. Full article ">

14 pages, 3060 KiB

Open AccessArticle

Economic Evaluation of Smart PV Inverters with a Three-Operation-Phase Watt-Var Control Scheme for Enhancing PV Penetration in Distribution Systems in Taiwan

by Shih-Chieh Hsieh, Yih-Der Lee and Yung-Ruei Chang

Appl. Sci. 2018, 8(6), 995; https://doi.org/10.3390/app8060995 - 19 Jun 2018

Cited by 4 | Viewed by 5493

Abstract

The paper presents an economic evaluation, including a cost-benefit analysis and a sensitivity analysis, of smart photovoltaic (PV) inverters with a novel Watt-Var control scheme for enhancing PV penetration in distribution systems in Taiwan. The novel Watt-Var control scheme with three operation phases [...] Read more.

The paper presents an economic evaluation, including a cost-benefit analysis and a sensitivity analysis, of smart photovoltaic (PV) inverters with a novel Watt-Var control scheme for enhancing PV penetration in distribution systems in Taiwan. The novel Watt-Var control scheme with three operation phases is utilized to avoid the voltage violation problem during peak solar irradiation period and increase the PV real power injection, and thus can get higher PV penetration in distribution systems. To evaluate the benefit and cost of the PV investment project, the annual revenue of PV power sales, the initial capital investment cost for a PV project with or without a smart inverter, and the operating and maintenance (O&M) cost are taken into account. The paper demonstrates the analyses of net present value (NPV) and benefit-cost ratio (BCR) for the PV project. In addition, the paper also presents a sensitivity analysis to deal with the project uncertainty with respect to some affecting parameters. The analyzing results show that, under the feed-in tariffs (FITs) policy, with proper selection of PV and smart inverter capacities, the investment can be profitable, and the smart PV inverter can greatly enhance the PV penetration in distribution systems in Taiwan. These results can provide some useful information for making policy to encourage investment in solar PV industry. Full article

(This article belongs to the Special Issue Selected Papers from the 2017 International Conference on Inventions)

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11 pages, 3920 KiB

Open AccessArticle

Acoustic Improvement of Stator–Rotor Interaction with Nonuniform Trailing Edge Blowing

by Wenjie Wang and Peter J. Thomas

Appl. Sci. 2018, 8(6), 994; https://doi.org/10.3390/app8060994 - 19 Jun 2018

Cited by 3 | Viewed by 4110

Abstract

The results of unsteady-flow simulations and experiments are discussed to investigate active noise-reduction effects on the stator–rotor interaction in a single-stage low-speed compressor with nonuniform trailing edge blowing. It is found that for the investigated type of stator–rotor interaction noise, nonuniform trailing edge [...] Read more.

The results of unsteady-flow simulations and experiments are discussed to investigate active noise-reduction effects on the stator–rotor interaction in a single-stage low-speed compressor with nonuniform trailing edge blowing. It is found that for the investigated type of stator–rotor interaction noise, nonuniform trailing edge blowing has beneficial noise-reducing effects. The overall aim is to demonstrate that nonuniform trailing edge blowing can compensate momentum loss and reduce the axial thrust on rotor blades. The results illustrate how nonuniform trailing edge blowing influences the sound pressure level of the blade-passing frequencies and results in active noise reduction effects. The study was conducted using a trailing edge blowing system, a four-hole dynamic flow-field measurement system, and phase lock technology. The results obtained show that nonuniform trailing edge blowing leads to substantial noise-reduction effects, lowering sound levels by more than 10 dB with about 5‰ of inlet mass flow. Full article

(This article belongs to the Special Issue Active and Passive Noise Control)

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17 pages, 6090 KiB

Open AccessArticle

Optimal Configuration and Path Planning for UAV Swarms Using a Novel Localization Approach

by Weijia Wang, Peng Bai, Hao Li and Xiaolong Liang

Appl. Sci. 2018, 8(6), 1001; https://doi.org/10.3390/app8061001 - 19 Jun 2018

Cited by 15 | Viewed by 5037

Abstract

In localization estimation systems, it is well known that the sensor-emitter geometry can seriously impact the accuracy of the location estimate. In this paper, time-difference-of-arrival (TDOA) localization is applied to locate the emitter using unmanned aerial vehicle (UAV) swarms equipped with TDOA-based sensors. [...] Read more.

In localization estimation systems, it is well known that the sensor-emitter geometry can seriously impact the accuracy of the location estimate. In this paper, time-difference-of-arrival (TDOA) localization is applied to locate the emitter using unmanned aerial vehicle (UAV) swarms equipped with TDOA-based sensors. Different from existing studies where the variance of measurement noises is assumed to be independent and changeless, we consider a more realistic model where the variance is sensor-emitter distance-dependent. First, the measurements model and variance model based on signal-to-noise ratio (SNR) are considered. Then the Cramer–Rao low bound (CRLB) is calculated and the optimal configuration is analyzed via the distance rule and angle rule. The sensor management problem of optimizing UAVs trajectories is studied by generating a sequence of waypoints based on CRLB. Simulation results show that path optimization enhances the localization accuracy and stability. Full article

(This article belongs to the Special Issue Swarm Robotics)

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Graphical abstract
Full article ">Figure 1
3D plot of the information function <math display="inline"><semantics> <mrow> <mi>T</mi> <mi>r</mi> <mrow> <mo>(</mo> <mstyle mathvariant="bold" mathsize="normal"> <mi>J</mi> </mstyle> <mo>)</mo> </mrow> </mrow> </semantics></math> for three sensors. (a) The value of <math display="inline"><semantics> <mrow> <mi>T</mi> <mi>r</mi> <mrow> <mo>(</mo> <mstyle mathvariant="bold" mathsize="normal"> <mi>J</mi> </mstyle> <mo>)</mo> </mrow> </mrow> </semantics></math>; (b) The contour plot of <math display="inline"><semantics> <mrow> <mi>T</mi> <mi>r</mi> <mrow> <mo>(</mo> <mstyle mathvariant="bold" mathsize="normal"> <mi>J</mi> </mstyle> <mo>)</mo> </mrow> </mrow> </semantics></math>. Full article ">Figure 2
Optimal receiver geometries for (a) <math display="inline"><semantics> <mrow> <mi>M</mi> <mo>=</mo> <mn>3</mn> </mrow> </semantics></math> , (b) <math display="inline"><semantics> <mrow> <mi>M</mi> <mo>=</mo> <mn>3</mn> </mrow> </semantics></math>, (c) <math display="inline"><semantics> <mrow> <mi>M</mi> <mo>=</mo> <mn>5</mn> </mrow> </semantics></math>. Full article ">Figure 3
UAV path planning for localization based on CRLB (TDOA: time-difference-of-arrival; SDP: semidefinite programming; EKF: extended Kalman filter). Full article ">Figure 4
(a) Optimal paths without constraints. (b) Evolution of angle changes. (c) Straight-line paths. (d) Comparison of localization performance: optimal deployment and fixed deployment. Full article ">Figure 5
(a) Optimal paths with constraints. (b) Evolution of angle changes. (c) Comparison of localization performance: optimal deployment and fixed deployment. Full article ">Figure 6
Evolution of RMSE with different numbers of UAVs. Full article ">Figure 7
(a) Optimal paths for dynamic emitter location and tracking. (b) Comparison of localization performance: optimal deployment and fixed deployment. Full article ">

24 pages, 2133 KiB

Open AccessArticle

MPC and PSO Based Control Methodology for Path Tracking of 4WS4WD Vehicles

by Qifan Tan, Penglei Dai, Zhihao Zhang and Jay Katupitiya

Appl. Sci. 2018, 8(6), 1000; https://doi.org/10.3390/app8061000 - 19 Jun 2018

Cited by 52 | Viewed by 6887

Abstract

Four wheel steering and four wheel drive (4WS4WD) vehicles are over-actuated systems with superior performance. Considering the control problem caused by the system nonlinearity and over-actuated characteristics of the 4WS4WD vehicle, this paper presents two methods to enable a 4WS4WD vehicle to accurately [...] Read more.

Four wheel steering and four wheel drive (4WS4WD) vehicles are over-actuated systems with superior performance. Considering the control problem caused by the system nonlinearity and over-actuated characteristics of the 4WS4WD vehicle, this paper presents two methods to enable a 4WS4WD vehicle to accurately follow a predefined path as well as its reference trajectories including velocity and acceleration profiles. The methodologies are based on model predictive control (MPC) and particle swarm optimization (PSO), respectively. The MPC method generates the virtual inputs in the upper controller and then allocates the actual inputs in the lower controller using sequential quadratic programming (SQP), whereas the PSO method is proposed as a fully optimization based method for comparison. Both methods achieve optimization of the steering angles and wheel forces for each of four independent wheels simultaneously in real time. Simulation results achieved by two different controllers in following the reference path with varying disturbances are presented. Discussion about two methodologies is provided based on their theoretical analysis and simulation results. Full article

(This article belongs to the Special Issue Advanced Mobile Robotics)

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17 pages, 4442 KiB

Open AccessArticle

Study of the Wave Energy Propagation Patterns in the Western Black Sea

by Eugen Rusu

Appl. Sci. 2018, 8(6), 993; https://doi.org/10.3390/app8060993 - 17 Jun 2018

Cited by 16 | Viewed by 4192

Abstract

The most relevant patterns of the wave energy propagation in the western side of the Black Sea were assessed in the present work. The emphasis was put on the western side because this is also the most energetic part of the Black Sea. [...] Read more.

The most relevant patterns of the wave energy propagation in the western side of the Black Sea were assessed in the present work. The emphasis was put on the western side because this is also the most energetic part of the Black Sea. The assessments performed relate some recent results provided by a numerical wave modeling system based on the spectrum concept. The SWAN model (acronym for Simulating Waves Nearshore) was considered. This was implemented over the entire sea basin and focused with increasing resolution in the geographical space towards the Romanian nearshore. Furthermore, some data assimilation techniques have also been implemented, such that the results provided are accurate and reliable. Special attention was paid to the high, but not extreme, winter wave energy conditions. The cases considered are focused on the coastal waves generated by distant storms, which means the local wind has not very high values in the targeted areas. This also takes into account the fact that the configuration of the environmental matrix in the Black Sea is currently subjected to significant changes mainly due to the climate change. From this perspective, the present work illustrates some of the most recent patterns of wave energy propagation in the western side of the Black Sea, considering eight different SWAN computational domains. According to most of the recent evaluations, the nearshore of the Black Sea is characterized by an average wave power lower than 6 kW/m. The results of the present work show that there is a real tendency of the wave energy enhancement. This tendency, especially concerns the western side of the basin, where in the high conditions considered, values of the wave power about 10 times greater than the average have been noticed. Full article

(This article belongs to the Special Issue Sustainable Energy Systems Planning, Integration and Management)

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20 pages, 4950 KiB

Open AccessReview

Microfluidic Technology for Cell Manipulation

by Jae-Sung Kwon and Je Hoon Oh

Appl. Sci. 2018, 8(6), 992; https://doi.org/10.3390/app8060992 - 17 Jun 2018

Cited by 23 | Viewed by 6678

Abstract

Microfluidic techniques for cell manipulation have been constantly developed and integrated into small chips for high-performance bioassays. However, the drawbacks of each of the techniques often hindered their further advancement and their wide use in biotechnology. To overcome this difficulty, an examination and [...] Read more.

Microfluidic techniques for cell manipulation have been constantly developed and integrated into small chips for high-performance bioassays. However, the drawbacks of each of the techniques often hindered their further advancement and their wide use in biotechnology. To overcome this difficulty, an examination and understanding of various aspects of the developed manipulation techniques are required. In this review, we provide the details of primary microfluidic techniques that have received much attention for bioassays. First, we introduce the manipulation techniques using a sole driving source, i.e., dielectrophoresis, electrophoresis, optical tweezers, magnetophoresis, and acoustophoresis. Next, we present rapid electrokinetic patterning, a hybrid opto-electric manipulation technique developed recently. It is introduced in detail along with the underlying physical principle, operating environment, and current challenges. This paper will offer readers the opportunity to improve existing manipulation techniques, suggest new manipulation techniques, and find new applications in biotechnology. Full article

(This article belongs to the Special Issue Microfluidics in Biology and Medicine)

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15 pages, 3916 KiB

Open AccessArticle

GNSS-Based Verticality Monitoring of Super-Tall Buildings

by Xingfu Zhang, Yongyi Zhang, Bofeng Li and Guangxin Qiu

Appl. Sci. 2018, 8(6), 991; https://doi.org/10.3390/app8060991 - 16 Jun 2018

Cited by 18 | Viewed by 6362

Abstract

In the construction of super-tall buildings, it is rather important to control the verticality. In general, a laser plummet is used to transmit coordinates of reference points from the ground layer-by-layer, which can effectively control the verticality of super-tall buildings. However, the errors [...] Read more.

In the construction of super-tall buildings, it is rather important to control the verticality. In general, a laser plummet is used to transmit coordinates of reference points from the ground layer-by-layer, which can effectively control the verticality of super-tall buildings. However, the errors in transmission will accumulate with increasing height and motion of the buildings in construction. This paper presents a global navigation satellite system (GNSS)-based method to check the results of laser plumbing. The method consists of four steps: (1) Computing the coordinate time series of monitoring points by adjusting the GNSS monitoring network observations at each epoch; (2) Analyzing the horizontal motion of super-tall buildings and its effect on vertical reference transmission; (3) Calculating the deflections of the vertical at the monitoring point using an Earth gravity field model and a geoid model. With deflections of the vertical, the static GNSS-measured coordinates are aligned to the same datum as used by the laser plummet; and (4) Finally, validating/checking the result of laser plumbing by comparing it with static GNSS results corrected by deflections of the vertical. A case study of a 438-m high building is tested in Guangzhou, China. The result demonstrates that the gross errors of baseline vectors can be eliminated effectively by GNSS network adjustment of the first step. The two-dimensional displacements can be measured at millimeter-level accuracy; the difference between the coordinates of the static GNSS measurement and laser plumbing is less than ±2.0 cm after correction with the deflections of the vertical, which meets the design requirement of ±3.0 cm according to the Technical Specification for Concrete Structures of Tall Buildings in China. Full article

(This article belongs to the Special Issue Structural Damage Detection and Health Monitoring)

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18 pages, 4263 KiB

Open AccessArticle

An Improved PSO Algorithm and Its Application in GNSS Ambiguity Resolution

by Xin Li, Jiming Guo and Jiyuan Hu

Appl. Sci. 2018, 8(6), 990; https://doi.org/10.3390/app8060990 - 16 Jun 2018

Cited by 8 | Viewed by 4282

Abstract

In this study, we proposed a novel method for global navigation satellite system (GNSS) ambiguity resolution (AR). The proposed method utilizes an improved particle swarm optimization (IPSO) algorithm to obtain the GNSS integer ambiguity with the double differenced (DD) float resolution and its [...] Read more.

In this study, we proposed a novel method for global navigation satellite system (GNSS) ambiguity resolution (AR). The proposed method utilizes an improved particle swarm optimization (IPSO) algorithm to obtain the GNSS integer ambiguity with the double differenced (DD) float resolution and its corresponding covariance matrix. First, we introduced population maturity to the standard PSO (SPSO) algorithm for the adaptive adjustment of inertia weight. Next, to improve the global convergence and robustness of the SPSO algorithm, we adopted population classification and constructed a Gauss mutation for the particle evolution process of the optimal population. Then, we applied the IPSO algorithm in the field of GNSS AR, called IPSO–AR. Finally, we evaluated the performance of the IPSO–AR algorithm under different DD ambiguity float resolutions with various dimensions and precisions. Numerical results showed that compared with the SPSO–AR algorithm, the IPSO–AR algorithm has a superior correct rate, but low efficiency. Under the appropriate parameter settings, the efficiency of the IPSO–AR algorithm is mainly dependent on the dimensions of DD ambiguity, whereas the correct rate of the IPSO–AR algorithm is mainly dependent on the precision of DD ambiguity. The proposed IPSO–AR algorithm has potential applications under the conditions of few visible satellites or constrained baseline length. Full article

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18 pages, 5642 KiB

Open AccessFeature PaperArticle

Ultraviolet Transient Absorption Spectrometer with Sub-20-fs Time Resolution

by Rocío Borrego-Varillas, Lucia Ganzer, Giulio Cerullo and Cristian Manzoni

Appl. Sci. 2018, 8(6), 989; https://doi.org/10.3390/app8060989 - 16 Jun 2018

Cited by 54 | Viewed by 9740

Abstract

We describe a transient absorption (TA) spectroscopy system in the ultraviolet (UV) spectral range, for the study of the ultrafast optical response of biomolecules. After reviewing the techniques for the generation and characterization of ultrashort UV pulses, we describe the experimental setup of [...] Read more.

We describe a transient absorption (TA) spectroscopy system in the ultraviolet (UV) spectral range, for the study of the ultrafast optical response of biomolecules. After reviewing the techniques for the generation and characterization of ultrashort UV pulses, we describe the experimental setup of our ultrabroadband UV TA spectrometer. The setup combines sub-20-fs UV pump pulses tunable between 3.35 and 4.7 eV, with broadband white-light-continuum probe pulses in the 1.7–4.6 eV range. Thanks to the broad tunability of the pump pulses in the UV spectral range, the extremely high temporal resolution and the broad spectral coverage of the probe, this TA system is a powerful and versatile tool for the study of many biomolecules. As an example of its potential, we apply the TA spectrometer to track ultrafast internal conversion processes in pyrene after excitation in the UV, and to resolve an impulsively excited molecular vibration with 85-fs period. Full article

(This article belongs to the Special Issue Femtosecond Light Sources and Their Applications in the Deep UV, Vacuum UV, and Extreme UV)

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16 pages, 2373 KiB

Open AccessArticle

An Off-Body Narrowband and Ultra-Wide Band Channel Model for Body Area Networks in a Ferryboat Environment

by Krzysztof K. Cwalina, Slawomir J. Ambroziak and Piotr Rajchowski

Appl. Sci. 2018, 8(6), 988; https://doi.org/10.3390/app8060988 - 16 Jun 2018

Cited by 12 | Viewed by 3744

Abstract

In the article an off-body narrowband and ultra-wide band channel model for body area networks in a ferryboat environment is described. Considering the limited number of publications there is a need to develop an off-body channel model, which will facilitate the design of [...] Read more.

In the article an off-body narrowband and ultra-wide band channel model for body area networks in a ferryboat environment is described. Considering the limited number of publications there is a need to develop an off-body channel model, which will facilitate the design of radio links, both from the multimedia services provider and the security point of view, for body area networks in this atypical environment. A mobile heterogeneous measurement stand, using radio distance measurements, which consists of three types of devices: miniaturized mobile nodes, stationary reference nodes, and a data acquisition server, was developed. A detailed analysis of both radio channels’ parameters was carried out. An analysis of system loss for off-body communication, including mean system loss, large-scale fading (corresponding to body shadowing), and small-scale fading (associated with the multipath phenomenon), both for 868 MHz narrowband and for 6489 MHz ultra-wide band channels, was performed. A statistical analysis of the obtained system loss model parameters was also carried out; good fit to the empirical data is observed. Full article

(This article belongs to the Special Issue Body Area Networks)

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14 pages, 3100 KiB

Open AccessArticle

A Lattice-Based Group Authentication Scheme

by Jheng-Jia Huang, Yi-Fan Tseng, Qi-Liang Yang and Chun-I Fan

Appl. Sci. 2018, 8(6), 987; https://doi.org/10.3390/app8060987 - 15 Jun 2018

Cited by 4 | Viewed by 4364

Abstract

Authentication has been adopted in many areas, but most of these authentication schemes are built using traditional cryptographic primitives. It is widely believed that such primitives are not resistant to quantum algorithms. To deal with those quantum attacks, lattice-based cryptography was introduced by [...] Read more.

Authentication has been adopted in many areas, but most of these authentication schemes are built using traditional cryptographic primitives. It is widely believed that such primitives are not resistant to quantum algorithms. To deal with those quantum attacks, lattice-based cryptography was introduced by Ajtai in 1996. To the best of our knowledge, the existing lattice-based authentication schemes are based on a lattice-based public key encryption called NTRU: a ring-based public key cryptosystem, proposed by Hoffstein, Pipher, and Silverman in 1998. However, these schemes only support the case of a single user. In view of the aforementioned issue, we propose the first lattice-based group authentication scheme. The proposed scheme is secure against replay attacks and man-in-the-middle attacks. Moreover, compared with the existing lattice-based authentication schemes, ours provides the most efficient method to agree upon a session key among a group of users after mutual authentication. Full article

(This article belongs to the Special Issue Selected Papers from the 2017 International Conference on Inventions)

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Figure A1

Figure A1
The security model of group mutual authentication. Full article ">Figure A2
The security model of a secure session key. Full article ">Figure A3
The authenticity of the manager <math display="inline"><semantics> <mrow> <mrow> <mo>(</mo> <mrow> <msup> <mi>Q</mi> <mo>′</mo> </msup> <mo>></mo> <mn>1</mn> </mrow> <mo>)</mo> </mrow> </mrow> </semantics></math>. Full article ">Figure A4
The authenticity of the manager <math display="inline"><semantics> <mrow> <mrow> <mo>(</mo> <mrow> <msup> <mi>Q</mi> <mo>′</mo> </msup> <mo>=</mo> <mn>1</mn> </mrow> <mo>)</mo> </mrow> </mrow> </semantics></math>. Full article ">Figure A5
The authenticity of the user. Full article ">Figure A6
The session key security <math display="inline"><semantics> <mrow> <mrow> <mo>(</mo> <mrow> <msup> <mi>Q</mi> <mo>′</mo> </msup> <mo>></mo> <mn>1</mn> </mrow> <mo>)</mo> </mrow> </mrow> </semantics></math>. Full article ">Figure A7
The session key security <math display="inline"><semantics> <mrow> <mrow> <mo>(</mo> <mrow> <msup> <mi>Q</mi> <mo>′</mo> </msup> <mo>=</mo> <mn>1</mn> </mrow> <mo>)</mo> </mrow> </mrow> </semantics></math>. Full article ">

15 pages, 4562 KiB

Open AccessArticle

Anamorphic and Local Characterization of a Holographic Data Storage System with a Liquid-Crystal on Silicon Microdisplay as Data Pager

by Fco. Javier Martínez-Guardiola, Andrés Márquez, Eva M. Calzado, Sergio Bleda, Sergi Gallego, Inmaculada Pascual and Augusto Beléndez

Appl. Sci. 2018, 8(6), 986; https://doi.org/10.3390/app8060986 - 15 Jun 2018

Cited by 3 | Viewed by 3819

Abstract

In this paper, we present a method to characterize a complete optical Holographic Data Storage System (HDSS), where we identify the elements that limit the capacity to register and restore the information introduced by means of a Liquid Cristal on Silicon (LCoS) microdisplay [...] Read more.

In this paper, we present a method to characterize a complete optical Holographic Data Storage System (HDSS), where we identify the elements that limit the capacity to register and restore the information introduced by means of a Liquid Cristal on Silicon (LCoS) microdisplay as the data pager. In the literature, it has been shown that LCoS exhibits an anamorphic and frequency dependent effect when periodic optical elements are addressed to LCoS microdisplays in diffractive optics applications. We tested whether this effect is still relevant in the application to HDSS, where non-periodic binary elements are applied, as it is the case in binary data pages codified by Binary Intensity Modulation (BIM). To test the limits in storage data density and in spatial bandwidth of the HDSS, we used anamorphic patterns with different resolutions. We analyzed the performance of the microdisplay in situ using figures of merit adapted to HDSS. A local characterization across the aperture of the system was also demonstrated with our proposed methodology, which results in an estimation of the illumination uniformity and the contrast generated by the LCoS. We show the extent of the increase in the Bit Error Rate (BER) when introducing a photopolymer as the recording material, thus all the important elements in a HDSS are considered in the characterization methodology demonstrated in this paper. Full article

(This article belongs to the Special Issue Liquid Crystal on Silicon Devices: Modeling and Advanced Spatial Light Modulation Applications)

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14 pages, 6305 KiB

Open AccessFeature PaperArticle

Self-Powered Fast Brazing of Ti-6Al-4V Using Ni/Al Reactive Multilayer Films

by Denzel Bridges, Christopher Rouleau, Zachary Gosser, Cary Smith, Zhili Zhang, Kunlun Hong, Jinquan Cheng, Yoseph Bar-Cohen and Anming Hu

Appl. Sci. 2018, 8(6), 985; https://doi.org/10.3390/app8060985 - 15 Jun 2018

Cited by 14 | Viewed by 4627

Abstract

Self-powered brazing of Ti-6Al-4V was performed using Ni/Al reactive multilayer films (RMFs) as self-propagated heat resources. BAlSi-4 was first coated on Ti-6Al-4V by plasma welding, then alternating layers of Ni and Al were successfully deposited on BAlSi-4 up to 32.9 ?m thick with [...] Read more.

Self-powered brazing of Ti-6Al-4V was performed using Ni/Al reactive multilayer films (RMFs) as self-propagated heat resources. BAlSi-4 was first coated on Ti-6Al-4V by plasma welding, then alternating layers of Ni and Al were successfully deposited on BAlSi-4 up to 32.9 ?m thick with e-beam deposition. The joint microstructure was investigated and the AlNi and Ni₅Al₃ phases were identified in the RMF. The cause for the two phases was determined to be differences in the diffusivity of Ni and Al, ultrafast brazing time, and faster cooling at the interface between brazing filler metal and the RMF. The maximum temperature of 683 °C was reached in the brazed joint, with a total RMF thickness of 135 ?m, which is more than sufficient to melt the BAlSi-4 brazing material. The maximum bonding strength obtained was 10.6 MPa, with a self-power brazing procedure conducted in a minute. It is possible to further improve the bonding strength by using more ductile RMFs and/or modifying the bonding interface configuration. Full article

(This article belongs to the Special Issue Selected Papers from the NMJ2018)

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22 pages, 22964 KiB

Open AccessArticle

A Novel Approach for Outdoor Fall Detection Using Multidimensional Features from A Single Camera

by Myeongseob Ko, Suneung Kim, Mingi Kim and Kwangtaek Kim

Appl. Sci. 2018, 8(6), 984; https://doi.org/10.3390/app8060984 - 15 Jun 2018

Cited by 10 | Viewed by 4783

Abstract

In the past few years, it has become increasingly important to automatically detect falls and provide feedback in emergency situations. To meet these demands, fall detection studies have been undertaken using various methods ranging from wearable devices to vision-based methods. However, each method [...] Read more.

In the past few years, it has become increasingly important to automatically detect falls and provide feedback in emergency situations. To meet these demands, fall detection studies have been undertaken using various methods ranging from wearable devices to vision-based methods. However, each method has its own limitations and one common limitation that is prevalent in almost all fall detection studies is that they are restricted to indoor environments. Therefore, we focused on a more dynamic and complex outdoor environment. We used two-dimensional features and Rao-Blackwellized Particle Filtering for human detection and tracking, and extracted three-dimensional features from depth images estimated by the supervised learning method from single input images. As we used the methods in combination, we could distinguish a series of states in which a person falls more precisely and then successfully perform fall detection under dynamic and complex scenes. In this study, we solved the initialization problem, the main constraint of existing tracking studies, by applying the particle swarm optimization method to the human detection system. In addition, we avoided using the background reference image feature for image segmentation due to its vulnerability towards dynamic outdoor changes. The experimental results show a reliable and robust performance for the proposed method and suggest the possibility of effective application to the pre-existing surveillance systems. Full article

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16 pages, 5440 KiB

Open AccessArticle

A Modified Polynomial Expansion Algorithm for Solving the Steady-State Allen-Cahn Equation for Heat Transfer in Thin Films

by Chih-Wen Chang, Chein-Hung Liu and Cheng-Chi Wang

Appl. Sci. 2018, 8(6), 983; https://doi.org/10.3390/app8060983 - 15 Jun 2018

Cited by 8 | Viewed by 4364

Abstract

Meshfree algorithms offer a convenient way of solving nonlinear steady-state problems in arbitrary plane areas surrounded by complicated boundary shapes. The simplest of these is the polynomial expansion approach. However, it is rarely utilized as a primary tool for this purpose because of [...] Read more.

Meshfree algorithms offer a convenient way of solving nonlinear steady-state problems in arbitrary plane areas surrounded by complicated boundary shapes. The simplest of these is the polynomial expansion approach. However, it is rarely utilized as a primary tool for this purpose because of its rather ill-conditioned behavior. A well behaved polynomial expansion algorithm is presented in this paper which can be more effectively used to solve the steady-state Allen-Cahn (AC) equation for heat transfer in thin films. In this method, modified polynomial expansion was used to cope with each iteration of the steady-state Allen-Cahn equation to produce nonlinear algebraic equations where multiple scales are automatically determined by the collocation points. These scales can largely decrease the condition number of the coefficient matrix in each nonlinear system, so that the iteration process converges very quickly. The numerical solutions were found to be accurate and stable against moderate noise to better than 7.5%. Computational results verified the method and showed the steady-state Allen-Cahn equation for heat transfer in thin films could easily be resolved for several arbitrary plane domains. Full article

(This article belongs to the Special Issue Selected Papers from the 2017 International Conference on Inventions)

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8 pages, 1778 KiB

Open AccessArticle

Active Color Control in a Metasurface by Polarization Rotation

by Minkyung Kim, Inki Kim, Jaehyuck Jang, Dasol Lee, Ki Tae Nam and Junsuk Rho

Appl. Sci. 2018, 8(6), 982; https://doi.org/10.3390/app8060982 - 15 Jun 2018

Cited by 49 | Viewed by 6739

Abstract

Generating colors by employing metallic nanostructures has attracted intensive scientific attention recently, because one can easily realize higher spatial resolution and highly robust colors compared to conventional pigment. However, since the scattering spectra and thereby the resultant colors are determined by the nanostructure [...] Read more.

Generating colors by employing metallic nanostructures has attracted intensive scientific attention recently, because one can easily realize higher spatial resolution and highly robust colors compared to conventional pigment. However, since the scattering spectra and thereby the resultant colors are determined by the nanostructure geometries, only one fixed color can be produced by one design and a whole new sample is required to generate a different color. In this paper, we demonstrate active metasurface, which shows a range of colors dependent on incident polarization by selectively exciting three different plasmonic nanorods. The metasurface, which does not include any tunable materials or external stimuli, will be beneficial in real-life applications especially in the display applications. Full article

(This article belongs to the Special Issue Photonic Metamaterials)

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14 pages, 742 KiB

Open AccessArticle

Comparing Deep Learning and Classical Machine Learning Approaches for Predicting Inpatient Violence Incidents from Clinical Text

by Vincent Menger, Floor Scheepers and Marco Spruit

Appl. Sci. 2018, 8(6), 981; https://doi.org/10.3390/app8060981 - 15 Jun 2018

Cited by 50 | Viewed by 9294

Abstract

Machine learning techniques are increasingly being applied to clinical text that is already captured in the Electronic Health Record for the sake of delivering quality care. Applications for example include predicting patient outcomes, assessing risks, or performing diagnosis. In the past, good results [...] Read more.

Machine learning techniques are increasingly being applied to clinical text that is already captured in the Electronic Health Record for the sake of delivering quality care. Applications for example include predicting patient outcomes, assessing risks, or performing diagnosis. In the past, good results have been obtained using classical techniques, such as bag-of-words features, in combination with statistical models. Recently however Deep Learning techniques, such as Word Embeddings and Recurrent Neural Networks, have shown to possibly have even greater potential. In this work, we apply several Deep Learning and classical machine learning techniques to the task of predicting violence incidents during psychiatric admission using clinical text that is already registered at the start of admission. For this purpose, we use a novel and previously unexplored dataset from the Psychiatry Department of the University Medical Center Utrecht in The Netherlands. Results show that predicting violence incidents with state-of-the-art performance is possible, and that using Deep Learning techniques provides a relatively small but consistent improvement in performance. We finally discuss the potential implication of our findings for the psychiatric practice. Full article

(This article belongs to the Special Issue Data Analytics in Smart Healthcare)

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