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Volume 9
Issue 15
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Appl. Sci., Volume 9, Issue 15 (August-1 2019) – 261 articles

Cover Story (view full-size image): In this study, a parabolic dish concentrator was investigated as a heat source for an organic Rankine cycle for power generation. Different types of cavity receivers were considered as solar working fluid, including hemispherical, cubical, and cylindrical with different nanofluids such as Al2O3/oil, CuO/oil, and SiO2/oil. The numerical model was validated using experimental data. Results show that compared to pure oil, the thermal efficiency of the cavity receivers increased slightly with the application of nanofluids. Furthermore, results showed that the cubical cavity receiver using oil/Al2O3 nanofluid was the most efficient choice for application as the investigated solar ORC’s heat source. View this paper.
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21 pages, 7404 KiB  
Article
Differences in Performance of Models for Heterogeneous Cores during Pulse Decay Tests
by Guofeng Han, Yang Chen, Min Liu and Xiaoli Liu
Appl. Sci. 2019, 9(15), 3206; https://doi.org/10.3390/app9153206 - 6 Aug 2019
Cited by 5 | Viewed by 2944
Abstract
Shale and fractured cores often exhibit dual-continuum medium characteristics in pulse decay testing. Dual-continuum medium models can be composed of different flow paths, interporosity flow patterns, and matrix shapes. Various dual-continuum medium models have been used by researchers to analyze the results of [...] Read more.
Shale and fractured cores often exhibit dual-continuum medium characteristics in pulse decay testing. Dual-continuum medium models can be composed of different flow paths, interporosity flow patterns, and matrix shapes. Various dual-continuum medium models have been used by researchers to analyze the results of pulse decay tests. But the differences in their performance for pulse decay tests have not been comprehensively investigated. The characteristics of the dual-permeability model and the dual-porosity model, the slab matrix, and the spherical matrix in pulse decay testing are compared by numerical modeling in this study. The pressure and pressure derivative curves for different vessel volumes, storativity ratios, interporosity flow coefficients, and matrix-fracture permeability ratios were compared and analyzed. The study found that these models have only a small difference in the interporosity flow stage, and the difference in the matrix shape is not important, and the matrix shape cannot be identified by pulse decay tests. When the permeability of the low permeability medium is less than 1% of the permeability of the high permeability medium, the difference between the dual-permeability model and the dual-porosity model can be ignored. The dual-permeability model approaches the pseudo-steady-state model as the interporosity flow coefficient and vessel volume increase. Compared with the dual-porosity model, the dual-permeability model has a shorter horizontal section of the pressure derivative in the interporosity flow stage. Finally, the conclusions were verified against a case study. This study advances the ability of pulse decay tests to investigate the properties of unconventional reservoir cores. Full article
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Figure 1
<p>Schematic diagram of the apparatus for pulse decay tests.</p> Full article ">Figure 2
<p>Schematic diagram of flow characteristics for dual-continuum medium models. (<b>a</b>) dual-porosity model. (<b>b</b>) dual-permeability model. (The blue arrows indicate the interporosity flow. The red arrows indicate the flow pathway of the system.).</p> Full article ">Figure 3
<p>Effect of vessel volume on the pulse decay test for dual-porosity cores. (<b>a</b>) Pressure history. (<b>b</b>) Pressure derivative.</p> Full article ">Figure 3 Cont.
<p>Effect of vessel volume on the pulse decay test for dual-porosity cores. (<b>a</b>) Pressure history. (<b>b</b>) Pressure derivative.</p> Full article ">Figure 4
<p>Effect of storativity ratio on pulse decay tests for dual-porosity cores. (<b>a</b>) Pressure history. (<b>b</b>) Pressure derivative.</p> Full article ">Figure 4 Cont.
<p>Effect of storativity ratio on pulse decay tests for dual-porosity cores. (<b>a</b>) Pressure history. (<b>b</b>) Pressure derivative.</p> Full article ">Figure 5
<p>Effect of interporosity flow coefficient on pulse decay tests for dual-porosity cores. (<b>a</b>) Pressure history. (<b>b</b>) Pressure derivative history.</p> Full article ">Figure 6
<p>Effect of vessel volumes on pulse decay tests for dual-permeability. (<b>a</b>) Pressure history. (<b>b</b>) Pressure derivative history.</p> Full article ">Figure 7
<p>Effect of the storativity ratio on pulse decay tests for dual-permeability cores. (<b>a</b>) Pressure history. (<b>b</b>) Pressure derivative history.</p> Full article ">Figure 8
<p>Effect of matrix-fracture permeability ratio on pulse decay tests for dual-permeability cores. (<b>a</b>) Pressure history for <span class="html-italic">λ</span> = 0.01. (<b>b</b>) Pressure derivative history <span class="html-italic">λ</span> = 0.01. (<b>c</b>) Pressure history for <span class="html-italic">λ</span> = 1. (<b>d</b>) Pressure derivative history for <span class="html-italic">λ</span> = 1.</p> Full article ">Figure 8 Cont.
<p>Effect of matrix-fracture permeability ratio on pulse decay tests for dual-permeability cores. (<b>a</b>) Pressure history for <span class="html-italic">λ</span> = 0.01. (<b>b</b>) Pressure derivative history <span class="html-italic">λ</span> = 0.01. (<b>c</b>) Pressure history for <span class="html-italic">λ</span> = 1. (<b>d</b>) Pressure derivative history for <span class="html-italic">λ</span> = 1.</p> Full article ">Figure 9
<p>Effect of the interporosity flow coefficient on pulse decay tests for dual-permeability cores (fixed matrix-fracture permeability ratio). (<b>a</b>) Pressure history. (<b>b</b>) Pressure derivative history.</p> Full article ">Figure 10
<p>Effect of interporosity flow coefficients on pulse decay test for dual-permeability cores (fixed matrix structure). (<b>a</b>) Pressure history. (<b>b</b>) Pressure derivative history.</p> Full article ">Figure 11
<p>Comparison between the numerical modeling results and experimental data of Cronin (2014) for (<b>a</b>) pressure histories and (<b>b</b>) pressure derivative histories.</p> Full article ">
14 pages, 8386 KiB  
Article
Preliminary Study on Greywater Treatment Using Nonwoven Textile Filters
by Marcin Spychała and Thanh Hung Nguyen
Appl. Sci. 2019, 9(15), 3205; https://doi.org/10.3390/app9153205 - 6 Aug 2019
Cited by 7 | Viewed by 3669
Abstract
The objective of the study was to evaluate the usefulness of novel nonwoven textile filter technology for greywater treatment. This technology had already been used on a lab scale for septic tank effluent treatment; however, this study is the first time it has [...] Read more.
The objective of the study was to evaluate the usefulness of novel nonwoven textile filter technology for greywater treatment. This technology had already been used on a lab scale for septic tank effluent treatment; however, this study is the first time it has been used for greywater treatment. The set-up period with septic tank effluent (STE) feeding was significantly shorter than that of greywater feeding. The average capacities of both filter types were practically the same: 1.0–1.4 cm d−1. The relatively high efficiencies of chemical oxygen demand (CODCr) and biochemical oxygen demand (BOD5) removal (58.8–71.6% and 56.7–79.8%, respectively) were obtained thanks to the relatively low filtration velocity and effective diffusion of atmospheric air into the greywater. The relatively high efficiency of total suspended solids (TSS) removal (67.0–88.4%) was obtained by reducing the effective pore size of the filtration layer due to high biomass concentration and accumulation of suspended solids. Thanks to hydrostatic pressure, the filters can work practically with very low energy consumption. The pollutants removal efficiencies were satisfactory in respect to simple construction and maintenance, low investment and operational costs. Full article
(This article belongs to the Special Issue Innovative Water and Wastewater Treatment Technologies for Supporting Global Sustainability 2020)
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<p>(<b>a</b>) Set I, (<b>b</b>) set II, and (<b>c</b>) scheme of nonwoven textile filter set (differences in dimensions between set I and set II and construction details are described in the main text of the article).</p> Full article ">Figure 2
<p>Chemical oxygen demand (COD<sub>Cr</sub>) removal efficiency in set I (<b>a</b>) and set II (<b>b</b>) during the experiment.</p> Full article ">Figure 3
<p>Chemical oxygen demand (COD<sub>Cr</sub>) inflow and outflow concentrations (<b>a</b>) and removal efficiencies (<b>b</b>) for set I.</p> Full article ">Figure 4
<p>Chemical oxygen demand (COD<sub>Cr</sub>) inflow and outflow concentrations (<b>a</b>) and removal efficiencies (<b>b</b>) for set II.</p> Full article ">Figure 5
<p>Biochemical oxygen demand (BOD<sub>5</sub>) removal efficiency in set I (<b>a</b>) and set II (<b>b</b>) during the experiment.</p> Full article ">Figure 6
<p>Biochemical oxygen demand (BOD<sub>5</sub>) inflow and outflow concentrations (<b>a</b>) and removal efficiencies (<b>b</b>) for set I.</p> Full article ">Figure 7
<p>Biochemical oxygen demand (BOD<sub>5</sub>) inflow and outflow concentrations (<b>a</b>) and removal efficiencies (<b>b</b>) for set II.</p> Full article ">Figure 8
<p>Total phosphorus (P<sub>tot</sub>) removal efficiency in set I (<b>a</b>) and set II (<b>b</b>) during the experiment.</p> Full article ">Figure 9
<p>Total phosphorus (P<sub>tot</sub>) inflow and outflow concentrations (<b>a</b>) and removal efficiencies (<b>b</b>) for set I.</p> Full article ">Figure 10
<p>Total phosphorus (P<sub>tot</sub>) inflow and outflow concentrations (<b>a</b>) and removal efficiencies (<b>b</b>) for set II.</p> Full article ">Figure 11
<p>Total suspended solids (TSS) removal efficiency in set I (<b>a</b>) and set II (<b>b</b>) during the experiment.</p> Full article ">Figure 12
<p>Total suspended solids (TSS) inflow and outflow concentrations (<b>a</b>) and removal efficiencies (<b>b</b>) for set I.</p> Full article ">Figure 13
<p>Total suspended solids (TSS) inflow and outflow concentrations (<b>a</b>) and removal efficiencies (<b>b</b>) for set II.</p> Full article ">
17 pages, 6905 KiB  
Article
Simulation Study of Low-Velocity Impact on Polyvinyl Butyral Laminated Glass Based on the Combined TCK-JH2 Model
by Demin Wei, Dong Li and Zongheng Zhang
Appl. Sci. 2019, 9(15), 3204; https://doi.org/10.3390/app9153204 - 6 Aug 2019
Cited by 7 | Viewed by 3993
Abstract
In this paper, both experimental tests and numerical simulations of Polyvinyl Butyral (PVB) laminated glass pane under low-speed impact were carried out. In order to accurately predict the responses of annealed glass under low-speed impact, a constitutive model combined of the Taylor–Chen–Kuszmaul (TCK) [...] Read more.
In this paper, both experimental tests and numerical simulations of Polyvinyl Butyral (PVB) laminated glass pane under low-speed impact were carried out. In order to accurately predict the responses of annealed glass under low-speed impact, a constitutive model combined of the Taylor–Chen–Kuszmaul (TCK) model and the Johnson-Holmquist Ceramic (JH2) model is proposed. In order to describe the tensile damage characteristic of annealed glass, a rate-dependent TCK model is employed. The JH2 model is adopted when the glass material is under compression. The velocity and force of impactor, deflection of central point of glass pane, and the cracking pattern are studied to verify the combined TCK-JH2 model. Furthermore, the effects of the thickness of glass layer and PVB interlayer are investigated. Full article
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<p>Impact loading testing machine setup.</p> Full article ">Figure 2
<p>Specimen with black and white stickers.</p> Full article ">Figure 3
<p>Finite element model of the drop-weight test: (<b>a</b>) parts of the model, (<b>b</b>) 1/4 mesh model.</p> Full article ">Figure 4
<p>Comparison of velocity-time curves between simulation results and experimental results of specimens: (<b>a</b>) LG-03114, (<b>b</b>) LG-06114, (<b>c</b>) LG-06076, and (<b>d</b>) LG-06038.</p> Full article ">Figure 5
<p>Comparison of force-time curves between simulation results and experimental results of specimens: (<b>a</b>) LG-03114, (<b>b</b>) LG-06114, (<b>c</b>) LG-06076, and (<b>d</b>) LG-06038.</p> Full article ">Figure 5 Cont.
<p>Comparison of force-time curves between simulation results and experimental results of specimens: (<b>a</b>) LG-03114, (<b>b</b>) LG-06114, (<b>c</b>) LG-06076, and (<b>d</b>) LG-06038.</p> Full article ">Figure 6
<p>Comparison of central-point deflection between simulation results and experimental results of specimens: (<b>a</b>) LG-03114, (<b>b</b>) LG-06114, (<b>c</b>) LG-06076, and (<b>d</b>) LG-06038.</p> Full article ">Figure 7
<p>Typical crack pattern of the test and simulation results: (<b>a</b>) experimental result and (<b>b</b>) numerical result.</p> Full article ">Figure 8
<p>Sequences of cracking of the numerical result of LG-03114 at: (<b>a</b>) 0 ms, (<b>b</b>) 2 ms, (<b>c</b>) 4 ms, (<b>d</b>) 6 ms, and (<b>e</b>) 8 ms.</p> Full article ">Figure A1
<p>Flow chart of details of implementation process of the combined TCK-JH2 model.</p> Full article ">Figure A1 Cont.
<p>Flow chart of details of implementation process of the combined TCK-JH2 model.</p> Full article ">Figure A1 Cont.
<p>Flow chart of details of implementation process of the combined TCK-JH2 model.</p> Full article ">
18 pages, 305 KiB  
Review
Entanglement and Phase-Mediated Correlations in Quantum Field Theory. Application to Brain-Mind States
by Shantena A. Sabbadini and Giuseppe Vitiello
Appl. Sci. 2019, 9(15), 3203; https://doi.org/10.3390/app9153203 - 6 Aug 2019
Cited by 29 | Viewed by 6089
Abstract
The entanglement phenomenon plays a central role in quantum optics and in basic aspects of quantum mechanics and quantum field theory. We review the dissipative quantum model of brain and the role of the entanglement in the brain-mind activity correlation and in the [...] Read more.
The entanglement phenomenon plays a central role in quantum optics and in basic aspects of quantum mechanics and quantum field theory. We review the dissipative quantum model of brain and the role of the entanglement in the brain-mind activity correlation and in the formation of assemblies of coherently-oscillating neurons, which are observed to appear in different regions of the cortex by use of EEG, ECoG, fNMR, and other observational methods in neuroscience. Full article
(This article belongs to the Special Issue Quantum Cooperativity in Neural Signaling)
11 pages, 2320 KiB  
Article
A Bench Evaluation Test for Refrigeration Oils in a Refrigeration System Using a Screw Compressor
by Weifeng Wu, Zhao Zhang, Xiaolin Wang, Liangwei Yang and Quanke Feng
Appl. Sci. 2019, 9(15), 3202; https://doi.org/10.3390/app9153202 - 6 Aug 2019
Cited by 1 | Viewed by 5120
Abstract
Refrigeration oil has a large effect on the performance of refrigeration systems. However, the physical and chemical indexes of fresh refrigeration oils often fail to reflect the actual operating characteristics, especially with respect to the degradation of refrigeration oils. In this paper, a [...] Read more.
Refrigeration oil has a large effect on the performance of refrigeration systems. However, the physical and chemical indexes of fresh refrigeration oils often fail to reflect the actual operating characteristics, especially with respect to the degradation of refrigeration oils. In this paper, a bench evaluation test of refrigeration oils was carried out to investigate the degradation of synthetic refrigeration oils used with the refrigerant R134a, in a purpose-built, full-scale refrigeration system utilizing a screw compressor. To accelerate the degradation process of the refrigeration oil, the discharge temperature at the exit of the compressor was turned to a high level. Comparison tests of a mature refrigeration oil type A and a newly developed oil type B were performed under the same working conditions with 500 h of operating time. The performance of the screw compressor and refrigeration system was analyzed. The abrasion of the screw rotors and carbon deposition at the discharge port was investigated. Results showed that the bench evaluation test successfully predicted the degradation process of the refrigeration oils. The evolution analysis of the refrigeration oil viscosity and acid value during the bench evaluation test indicated that 15% of the physical and chemical indexes for refrigeration oil drain were too strict. Research work in this paper showed a more practical method to evaluate the performance of refrigeration oils through the bench evaluation test. Full article
(This article belongs to the Section Mechanical Engineering)
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Figure 1
<p>A schematic diagram and a picture of the test bench.</p> Full article ">Figure 1 Cont.
<p>A schematic diagram and a picture of the test bench.</p> Full article ">Figure 2
<p>Discharge temperature of the compressor and refrigeration capacity of the system during the 500 h of operation (Oil A, mature synthetic oil; Oil B, newly developed synthetic oil; the vertical lines are the error bars).</p> Full article ">Figure 3
<p>Variation of the compressor efficiency, <span class="html-italic">η</span><sub>c</sub>, during the testing.</p> Full article ">Figure 4
<p>Oil viscosity evolution (Data at −100 h represents the fresh oil before loading into the system; data at 0 h represents the initial oil after loading into the system; the vertical lines refer to the error bars).</p> Full article ">Figure 5
<p>Acid value evolution (Data at −100 h represents the fresh oil before being loaded into the system, data at 0 h represents the new initial oil after being loaded into the system; the vertical lines refer to the error bars).</p> Full article ">Figure 6
<p>Abrasion of rotors.</p> Full article ">Figure 7
<p>Carbon deposition at the discharge port of the compressor.</p> Full article ">
24 pages, 3810 KiB  
Article
Microbial Induced Carbonate Precipitation Using a Native Inland Bacterium for Beach Sand Stabilization in Nearshore Areas
by Pahala Ge Nishadi Nayanthara, Anjula Buddhika Nayomi Dassanayake, Kazunori Nakashima and Satoru Kawasaki
Appl. Sci. 2019, 9(15), 3201; https://doi.org/10.3390/app9153201 - 6 Aug 2019
Cited by 40 | Viewed by 5503
Abstract
Microbial Induced Carbonate Precipitation (MICP) via urea hydrolysis is an emerging sustainable technology that provides solutions for numerous environmental and engineering problems in a vast range of disciplines. Attention has now been given to the implementation of this technique to reinforce loose sand [...] Read more.
Microbial Induced Carbonate Precipitation (MICP) via urea hydrolysis is an emerging sustainable technology that provides solutions for numerous environmental and engineering problems in a vast range of disciplines. Attention has now been given to the implementation of this technique to reinforce loose sand bodies in-situ in nearshore areas and improve their resistance against erosion from wave action without interfering with its hydraulics. A current study has focused on isolating a local ureolytic bacterium and assessed its feasibility for MICP as a preliminary step towards stabilizing loose beach sand in Sri Lanka. The results indicated that a strain belonging to Sporosarcina sp. isolated from inland soil demonstrated a satisfactory level of enzymatic activity at 25 °C and moderately alkaline conditions, making it a suitable candidate for target application. Elementary scale sand solidification test results showed that treated sand achieved an approximate strength of 15 MPa as determined by needle penetration device after a period of 14 days under optimum conditions. Further, Scanning Electron Microscopy (SEM) imagery revealed that variables such as grain size distribution, bacteria population, reactant concentrations and presence of other cations like Mg2+ has serious implications on the size and morphology of precipitated crystals and thus the homogeneity of the strength improvement. Full article
(This article belongs to the Special Issue Coastal Deposits: Environmental Implications, Mathematical Modeling and Technological Development)
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Figure 1
<p>Cementation mechanism of microbial induced carbonate precipitation (<b>a</b>) grain coating; (<b>b</b>) contact cementing; (<b>c</b>) matrix-supported; (<b>d</b>) pore-filling.</p> Full article ">Figure 2
<p>Relative abundance of ureolytic bacteria in different sampling locations.</p> Full article ">Figure 3
<p>Microbial induced carbonate precipitation capacity of isolated strains.</p> Full article ">Figure 4
<p>Variation of bacterial cell concentration of <span class="html-italic">Sporosarcina</span> sp. at different temperatures.</p> Full article ">Figure 5
<p>Variation of urease activity of <span class="html-italic">Sporosarcina</span> sp. at different temperatures.</p> Full article ">Figure 6
<p>Variation of urease activity of <span class="html-italic">Sporosarcina</span> sp. at different pH conditions.</p> Full article ">Figure 7
<p>Variation of local strength of microbial induced carbonate precipitation (MICP) treated sand under different bacteria and reactant concentrations.</p> Full article ">Figure 8
<p>(<b>a</b>) pH; (<b>b</b>) Ca<sup>2+</sup> measurements of the solution collected from the bottom of the sand.</p> Full article ">Figure 9
<p>SEM images of showing variation of crystal morphology for the samples treated under different bacteria and reactant concentrations: (<b>a</b>–<b>c</b>) 0.5 M cementation solution with bacteria injected twice; (<b>d</b>–<b>f</b>) 1.0 M cementation solution with bacteria injected only in the beginning.</p> Full article ">Figure 10
<p>Variation of microbial induced carbonate precipitation under different Mg<sup>2+</sup>/Ca<sup>2+</sup> molar ratios.</p> Full article ">Figure 11
<p>Scanning electron microscopy (SEM) images of microbial induced precipitate by <span class="html-italic">Sporosarcina</span> sp. with (<b>a</b>) Mg<sup>2+</sup>/Ca<sup>2+</sup> = 0.00; (<b>b</b>) Mg<sup>2+</sup>/Ca<sup>2+</sup> = 0.25; (<b>c</b>) Mg<sup>2+</sup>/Ca<sup>2+</sup> = 0.43; (<b>d</b>) Mg<sup>2+</sup>/Ca<sup>2+</sup> = 1.00.</p> Full article ">Figure 12
<p>X-ray diffraction (XRD) spectra of the microbial induced precipitate by <span class="html-italic">Sporosarcina</span> sp. with (<b>a</b>) Mg<sup>2+</sup>/Ca<sup>2+</sup> = 0.00; (<b>b</b>) Mg<sup>2+</sup>/Ca<sup>2+</sup> = 0.25; (<b>c</b>) Mg<sup>2+</sup>/Ca<sup>2+</sup> = 0.43; (<b>d</b>) Mg<sup>2+</sup>/Ca<sup>2+</sup> = 1.00.</p> Full article ">Figure 13
<p>Variation of local strength of MICP treated sand for different Mg<sup>2+</sup>/Ca<sup>2+</sup> molar ratios.</p> Full article ">Figure 14
<p>SEM images of variation in crystal morphology with different Mg<sup>2+</sup>/Ca<sup>2+</sup> molar ratios: (<b>a</b>,<b>b</b>) Mg<sup>2+</sup>/Ca<sup>2+</sup> = 0.00 and its closer view; (<b>c</b>) Mg<sup>2+</sup>/Ca<sup>2+</sup> = 0.25; (<b>d</b>) Mg<sup>2+</sup>/Ca<sup>2+</sup> = 0.43; (<b>e</b>,<b>f</b>); Mg<sup>2+</sup>/Ca<sup>2+</sup> = 1.00 and its closer view.</p> Full article ">
26 pages, 10048 KiB  
Article
Experimental Study on Energy Dissipation Performance and Failure Mode of Web-Connected Replaceable Energy Dissipation Link
by Zhanzhong Yin, Zhaosheng Huang, Hui Zhang and Dazhe Feng
Appl. Sci. 2019, 9(15), 3200; https://doi.org/10.3390/app9153200 - 6 Aug 2019
Cited by 10 | Viewed by 4566
Abstract
In the current design method of the eccentrically braced frame structure, the energy dissipation link and the frame beam are both designed as a whole. It is difficult to accurately assess the degree of damage through this method, and it is also hard [...] Read more.
In the current design method of the eccentrically braced frame structure, the energy dissipation link and the frame beam are both designed as a whole. It is difficult to accurately assess the degree of damage through this method, and it is also hard to repair or replace the energy dissipation link after strong seismic events. Meanwhile, the overall design approach will increase the project’s overall cost. In order to solve the above mentioned shortcomings, the energy dissipation link is designed as an independent component, which is separated from the frame beam. In this paper, the energy dissipation link is bolted to the web of the frame beam. Both finite element simulation and test study of eight groups of energy dissipation links have been completed to study their mechanical behaviors, and the energy dissipation links have been studied in the aspects of length, cross section, and stiffener spacing. The mechanical behaviors include the energy dissipation behavior, bearing capacity, stiffness, and plastic rotation angle. The results indicate clearly that the hysteretic loop of links in the test and finite element analysis is relatively full. By comparing the experimental and finite element simulation data, it can be found that the general shape and trend of hysteretic loop, skeleton curve, and stiffness degradation curve are basically the same. The experiment data explicitly shows that the energy dissipation link of web-connected displays good ductility and stable energy dissipation ability. In addition, the replaceable links possess good rotational capacity when the minimum rotation angle of each specimen in the test is 0.16 rad. The results of the experiment show that the energy dissipation capacity of the link is mainly related to the section size and the stiffening rib spacing of the link. The energy dissipation ability and deformation ability of the link is poorer as the section size becomes larger; meanwhile, these abilities are reduced with the decrease of the stiffening spacing. The experiment result shows that the damage and excessive inelastic deformations are concentrated in the link to avoid any issues for the rest of the surrounding elements, and the links can be easily and inexpensively replaced after strong seismic events. The results are thought provoking, as they provide a theoretical basis for the further study of the eccentrically braced frame structure with replaceable links of web-connected. In future work, the author aims to carry out his studies through optimized design methodology based on the yielding criterion. Full article
(This article belongs to the Special Issue Energy Dissipation and Vibration Control: Materials, Modeling, Algorithm and Devices)
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<p>Detail drawing of test specimen.</p> Full article ">Figure 2
<p>Test chart of steel properties.</p> Full article ">Figure 3
<p>Experimental setup. (<b>a</b>) Details of test setup; (<b>b</b>) Photo; and, (<b>c</b>) Roller.</p> Full article ">Figure 4
<p>The measurement arrangement of strain gauge and strain rosette.</p> Full article ">Figure 5
<p>Loading Protocol.</p> Full article ">Figure 6
<p>Failure modes of RSL-1. (<b>a</b>) vanished leather bulging; (<b>b</b>) vanished leather bulging; (<b>c</b>) flange bending; (<b>d</b>) lacquer skin bulging; (<b>e</b>) overall deformation increase; (<b>f</b>) vanished leather falls off; (<b>g</b>) web damaged.</p> Full article ">Figure 6 Cont.
<p>Failure modes of RSL-1. (<b>a</b>) vanished leather bulging; (<b>b</b>) vanished leather bulging; (<b>c</b>) flange bending; (<b>d</b>) lacquer skin bulging; (<b>e</b>) overall deformation increase; (<b>f</b>) vanished leather falls off; (<b>g</b>) web damaged.</p> Full article ">Figure 7
<p>Failure modes of RSL-2. (<b>a</b>) flange bending; (<b>b</b>) flange cured inward; (<b>c</b>) lacquer skin cracked; (<b>d</b>) specimen damaged.</p> Full article ">Figure 7 Cont.
<p>Failure modes of RSL-2. (<b>a</b>) flange bending; (<b>b</b>) flange cured inward; (<b>c</b>) lacquer skin cracked; (<b>d</b>) specimen damaged.</p> Full article ">Figure 8
<p>Failure modes of RSL-4. (<b>a</b>) flange bending; (<b>b</b>) vanished leather bulging; (<b>c</b>) flange bending; (<b>d</b>) flange bending.</p> Full article ">Figure 9
<p>Replacement of energy-dissipating links. (<b>a</b>) replacement of connection; (<b>b</b>) replacement of connection.</p> Full article ">Figure 10
<p>Measurement point number of RSL-1.</p> Full article ">Figure 11
<p>Hysteretic response of specimens.</p> Full article ">Figure 12
<p>Calculation diagram of energy dissipation coefficient.</p> Full article ">Figure 13
<p>Skeleton curves of specimens.</p> Full article ">Figure 14
<p>Test and finite element deformation comparison diagram. (<b>a</b>) bolt hole shear failure of test; (<b>b</b>) flange bending of test; (<b>c</b>) bolt hole shear failure of FEA; (<b>d</b>) flange bending of FEA.</p> Full article ">Figure 15
<p>Finite element model (<b>a</b>); Mesh division diagram (<b>b</b>); and, Finite element model constraint diagram (<b>c</b>).</p> Full article ">Figure 16
<p>Comparison of hysteretic curves between test and finite element analysis of RSL-7.</p> Full article ">Figure 17
<p>Stress cloud diagram of each specimen under cyclic load.</p> Full article ">Figure 17 Cont.
<p>Stress cloud diagram of each specimen under cyclic load.</p> Full article ">Figure 17 Cont.
<p>Stress cloud diagram of each specimen under cyclic load.</p> Full article ">
13 pages, 3084 KiB  
Article
Temporal Label Walk for Community Detection and Tracking in Temporal Network
by Zheliang Liu, Hongxia Wang, Lizhi Cheng, Wei Peng and Xiang Li
Appl. Sci. 2019, 9(15), 3199; https://doi.org/10.3390/app9153199 - 6 Aug 2019
Cited by 2 | Viewed by 3122
Abstract
The problem of temporal community detection is discussed in this paper. Main existing methods are either structure-based or incremental analysis. The difficulty of the former is to select a suitable time window. The latter needs to know the initial structure of networks and [...] Read more.
The problem of temporal community detection is discussed in this paper. Main existing methods are either structure-based or incremental analysis. The difficulty of the former is to select a suitable time window. The latter needs to know the initial structure of networks and the changing of networks should be stable. For most real data sets, these conditions hardly prevail. A streaming method called Temporal Label Walk (TLW) is proposed in this paper, where the aforementioned restrictions are eliminated. Modularity of the snapshots is used to evaluate our method. Experiments reveal the effectiveness of TLW on temporal community detection. Compared with other static methods in real data sets, our method keeps a higher modularity with the increase of window size. Full article
(This article belongs to the Section Applied Physics General)
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Full article ">Figure 1
<p>Several different forms of data. (<b>a</b>) is the data used in structure-based methods, temporal data in a time window of size <math display="inline"><semantics> <mrow> <mo>Δ</mo> <mi>t</mi> </mrow> </semantics></math> is mixed to snapshot <math display="inline"><semantics> <msub> <mi>G</mi> <mn>0</mn> </msub> </semantics></math>. Incremental analysis in (<b>b</b>) knows the structure of network at the beginning and addition of nodes and edges (or delete) to change local structure so that the new communities grow. (<b>c</b>) is a real data set called <math display="inline"><semantics> <mrow> <mi>S</mi> <mi>t</mi> <mi>u</mi> <mi>d</mi> <mi>e</mi> <mi>n</mi> <mi>t</mi> <mi>s</mi> </mrow> </semantics></math> where it is hard finding community structure at any <math display="inline"><semantics> <msub> <mi>t</mi> <mi>i</mi> </msub> </semantics></math> and the information flow is spare when edges appear.</p> Full article ">Figure 2
<p>Mixing all 113 edges appear on 87 nodes on 27 June 2014. It is easy to find that nodes 1713 and 3 interact more frequently with other nodes.</p> Full article ">Figure 3
<p>Two different situations in temporal networks. (<b>a</b>) shows that two communities A and B share the same information exchange within community, the corresponding nodes are of the same importance but belong to different communities. (<b>b</b>) shows that nodes <span class="html-italic">u</span> and <span class="html-italic">v</span> are in different communities in the beginning and <span class="html-italic">v</span> sends a message to <span class="html-italic">u</span> at time <math display="inline"><semantics> <msub> <mi>t</mi> <mi>i</mi> </msub> </semantics></math>. If <span class="html-italic">v</span> sends a message to <span class="html-italic">u</span> again at <math display="inline"><semantics> <msub> <mi>t</mi> <mrow> <mi>i</mi> <mo>+</mo> <mn>1</mn> </mrow> </msub> </semantics></math>, as shown in (<b>c</b>), <span class="html-italic">u</span> will have a higher probability of belonging to B at <math display="inline"><semantics> <msub> <mi>t</mi> <mrow> <mi>i</mi> <mo>+</mo> <mn>2</mn> </mrow> </msub> </semantics></math> than those nodes inside A send a message to <span class="html-italic">u</span> at <math display="inline"><semantics> <msub> <mi>t</mi> <mrow> <mi>i</mi> <mo>+</mo> <mn>1</mn> </mrow> </msub> </semantics></math>, which is illustrated in (<b>d</b>).</p> Full article ">Figure 4
<p>Three nodes send messages to each other in 30 s. The order that three nodes periodically send information at each time is <math display="inline"><semantics> <mrow> <mn>1</mn> <mo>→</mo> <mn>2</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mn>2</mn> <mo>→</mo> <mn>3</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mn>3</mn> <mo>→</mo> <mn>1</mn> </mrow> </semantics></math>.</p> Full article ">Figure 5
<p>Label value of node 3 with non-normalization and normalization. The value increases exponentially without normalization (see (<b>a</b>)), but tends to be stable after normalization (see (<b>b</b>)).</p> Full article ">Figure 6
<p>Results of community detection with AP, Mini Batch K-means, and DBSCAN. The blue nodes and node 3 are in the same community. The orange nodes belong to community of node 1713. The division is only different in a few points.</p> Full article ">Figure 7
<p>Label value of node 525 from 16:06:47 to 23:58:51. The horizontal axis denotes the sequence of the interactions. This sequence starts from 0 and end at 97, indicating that there are 97 information interactions between nodes in this day.</p> Full article ">Figure 8
<p>Modularity of different methods from one day to three months.</p> Full article ">Figure 9
<p>Real-time running time of TLW and DABP.</p> Full article ">Figure 10
<p>Community structure of <math display="inline"><semantics> <mrow> <mi>S</mi> <mi>t</mi> <mi>u</mi> <mi>d</mi> <mi>e</mi> <mi>n</mi> <mi>t</mi> <mi>s</mi> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>F</mi> <mi>a</mi> <mi>c</mi> <mi>e</mi> <mi>b</mi> <mi>o</mi> <mi>o</mi> <mi>k</mi> </mrow> </semantics></math> in one day, one week, and one month, respectively. Nodes in black denote that they do not belong to any community obviously yet.</p> Full article ">Figure 11
<p>The effect of <math display="inline"><semantics> <mi>α</mi> </semantics></math> on the label value of node 3. The larger <math display="inline"><semantics> <mi>α</mi> </semantics></math> makes node 2 have more influence on node 3 than the others.</p> Full article ">Figure 12
<p>Three nodes send messages in turn. The order is <math display="inline"><semantics> <mrow> <mn>2</mn> <mover> <mo>⟶</mo> <msub> <mi>t</mi> <mrow> <mn>3</mn> <mi>k</mi> </mrow> </msub> </mover> <mn>1</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mn>1</mn> <mover> <mo>⟶</mo> <msub> <mi>t</mi> <mrow> <mn>3</mn> <mi>k</mi> <mo>+</mo> <mn>1</mn> </mrow> </msub> </mover> <mn>3</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mn>3</mn> <mover> <mo>⟶</mo> <msub> <mi>t</mi> <mrow> <mn>3</mn> <mi>k</mi> <mo>+</mo> <mn>2</mn> </mrow> </msub> </mover> <mn>2</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>k</mi> <mo>=</mo> <mn>0</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mo>⋯</mo> <mo>,</mo> <mi>n</mi> </mrow> </semantics></math>.</p> Full article ">Figure 13
<p>Fix <math display="inline"><semantics> <mi>β</mi> </semantics></math> and <span class="html-italic">c</span> respectively, and calculate the first component of <math display="inline"><semantics> <mrow> <msub> <mi>X</mi> <mn>3</mn> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> </mrow> </semantics></math>. Two parameters are set to 0.25, 0.5, 0.75 and 1. Smaller <span class="html-italic">c</span> and larger <math display="inline"><semantics> <mi>β</mi> </semantics></math> both have smaller peak value and larger valley value.</p> Full article ">
11 pages, 5267 KiB  
Article
An Improved Method for Estimating Renal Dimensions; Implications for Management of Kidney Disease
by Kristen Chao, Kimberly Liao, Maheen Khan, Christopher Shi, Jingsong Li, Itzhak D. Goldberg and Prakash Narayan
Appl. Sci. 2019, 9(15), 3198; https://doi.org/10.3390/app9153198 - 6 Aug 2019
Cited by 3 | Viewed by 3664
Abstract
Changes in renal dimensions, including total kidney volume, not only inform ongoing renal disease but also disease progression. Determination of renal dimensions can inform drug efficacy, is important for matching recipients with potential donors, and to inform debulking of renal tumors. Imaging of [...] Read more.
Changes in renal dimensions, including total kidney volume, not only inform ongoing renal disease but also disease progression. Determination of renal dimensions can inform drug efficacy, is important for matching recipients with potential donors, and to inform debulking of renal tumors. Imaging of kidney and application of the ellipse-based formula has become standard for estimating renal dimensions. Nevertheless, the existing ellipse-based formula underestimates renal dimensions including total kidney volume, regardless of the imaging modality used. Based on a model of murine kidney disease, this laboratory has previously proposed a modification to this formula which exhibits better estimation of renal dimensions. The present study sought to determine whether this modified formula is applicable to additional models of kidney disease. Kidneys were sourced from etiologically distinct murine and rat models of renal scarring. In each case, renal dimensions calculated using the existing ellipse-based formula was significantly lesser than the measured dimensions. By contrast, there was no difference between the measured dimensions and those calculated using the modified formula. In a model of polycystic kidney disease, total kidney volume calculated using the existing formula significantly underestimated measured kidney volume whereas use of the modified formula yielded a calculated kidney volume in excellent agreement with the measured volume. Use of this modified formula provides a better estimate of renal dimensions across a number of disease models. Full article
(This article belongs to the Section Applied Biosciences and Bioengineering)
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Full article ">Figure 1
<p>Renal parenchymal area. (<b>A</b>) An H&amp;E-stained coronal section (4×) superimposed on a 1 mm<sup>2</sup> grid from the left kidney of a male obese ZSF1 rat. (<b>B</b>) The same renal section with labeled axes: white horizontal line represents major axis (<span class="html-italic">a</span>), yellow vertical line representing minor axis (<span class="html-italic">b</span>). The orange/brown outline around the kidney (white arrow) represents the measured renal parenchymal area, <span class="html-italic">Am</span>. (<b>C</b>) Again, the same renal section but with the minor axis extended (<span class="html-italic">be</span>) past the hilum (red line) to meet the imaginary dashed bar.</p> Full article ">Figure 2
<p>Rat models of kidney disease. Representative photomicrograph (10×) of periodic acid Schiff-stained kidneys from a control (<b>A</b>) and a purumoycin aminonucleoside (PAN)-administered Sprague-Dawley (SD) rat. (<b>B</b>) Scarring of the glomerulus is clearly evident in the latter. Representative photomicrograph (4×) of Masson’s Trichrome-stained kidneys from an age-matched male SD rat (<b>C</b>) and an obese male ZSF1 rat (<b>D</b>). The ZSF1 rat exhibits scarring within the renal tubulointerstitium.</p> Full article ">Figure 3
<p>Left kidney parenchymal area in healthy and diseased rats. Left kidneys were sourced from adult male and female obese ZSF1 rats, adult male SD rats and adult male SD rats administered PAN and sliced coronally. (<b>A</b>) A scatter plot of <span class="html-italic">A</span>, the renal parenchymal area calculated using the existing ellipse-based formula vs. <span class="html-italic">Am</span>, the measured renal parenchymal area. (<b>B</b>) A scatter plot of <span class="html-italic">Ae</span>, the renal parenchymal area calculated using the modified ellipse-based formula with the extended minor axis vs. <span class="html-italic">Am</span>, the measured renal parenchymal area. (<b>C</b>) In coronal renal slices, <span class="html-italic">Am</span> is greater than <span class="html-italic">A</span> (*, <span class="html-italic">p</span> &lt; 0.01) but not different from <span class="html-italic">Ae</span>.</p> Full article ">Figure 4
<p>Right kidney parenchymal area in healthy and diseased rats. Right kidneys were sourced from adult male and female obese ZSF1 rats, adult male SD rats and adult male SD rats administered PAN and sliced coronally. (<b>A</b>) A scatter plot of <span class="html-italic">A</span>, the renal parenchymal area calculated using the existing ellipse-based formula vs. <span class="html-italic">Am</span>, the measured renal parenchymal area. (<b>B</b>) A scatter plot of <span class="html-italic">Ae</span>, the renal parenchymal area calculated using the modified ellipse-based formula with the extended minor axis vs. <span class="html-italic">Am</span>, the measured renal parenchymal area. (<b>C</b>) In coronal renal slices, <span class="html-italic">Am</span> is greater than <span class="html-italic">A</span> (*, <span class="html-italic">p</span> &lt; 0.01) but not different from <span class="html-italic">Ae</span>.</p> Full article ">Figure 5
<p>Aristolochic acid + NaCl-induced kidney disease in mice. Representative photomicrograph (4X) of Masson’s Trichrome-stained kidneys from a control CD-1 mouse (<b>A</b>) and an aristolochic acid + NaCl-administered CD-1 mouse (<b>B</b>). Renal interstitial scarring is clearly evident in the latter.</p> Full article ">Figure 6
<p>Renal parenchymal area in healthy and diseased mice (aristolochic acid + NaCl). Left and right kidneys were sourced from healthy adult male CD-1 mice or adult male CD-1 mice with aristolochic acid + NaCl nephropathy. (<b>A</b>) In coronal left kidney slices, <span class="html-italic">Am</span> is greater than <span class="html-italic">A</span> (*, <span class="html-italic">p</span> &lt; 0.01) but not different from <span class="html-italic">Ae</span>. (<b>B</b>) In coronal right kidney slices, <span class="html-italic">Am</span> is greater than <span class="html-italic">A</span> (*, <span class="html-italic">p</span> &lt; 0.01) but not different from <span class="html-italic">Ae</span>.</p> Full article ">Figure 7
<p>Streptocozocin (STZ) + NaCl-induced kidney disease in mice. Representative photomicrograph (4×) of Masson’s Trichrome-stained kidneys from a control 129/Sv mouse (<b>A</b>) and an STZ + NaCl-administered 129/Sv mouse (<b>B</b>). Acute tubular necrosis and renal interstitial scarring is clearly evident in the latter.</p> Full article ">Figure 8
<p>Renal parenchymal area in healthy and diseased mice (STZ + NaCl). Left and right kidneys were sourced from healthy adult male and female SV129 mice or adult male and female SV129 mice with diabetic nephropathy. (<b>A</b>) In coronal left kidney slices, <span class="html-italic">Am</span> is greater than <span class="html-italic">A</span> (*, <span class="html-italic">p</span> &lt; 0.01) but not different from <span class="html-italic">Ae</span>. (<b>B</b>) In coronal right kidney slices, <span class="html-italic">Am</span> is greater than <span class="html-italic">A</span> (*, <span class="html-italic">p</span> &lt; 0.01) but not different from <span class="html-italic">Ae</span>.</p> Full article ">Figure 9
<p>Measured vs. calculated total kidney volume (TKV). (<b>A</b>) An H&amp;E-stained coronal renal slice from a PCK rat. The major axis (<span class="html-italic">a</span>), minor axis (<span class="html-italic">b</span>), and extended minor axis are shown (<span class="html-italic">be</span>). (<b>B</b>) Kidney volume calculated using the existing formula was lower than measured TKV whereas kidney volume calculated using the modified formula was not different from the measured TKV (*, <span class="html-italic">p</span> &lt; 0.01 vs).</p> Full article ">
14 pages, 7235 KiB  
Article
Microtexture Performance of EAF Slags Used as Aggregate in Asphalt Mixes: A Comparative Study with Surface Properties of Natural Stones
by Rosolino Vaiana, Filippo Balzano, Teresa Iuele and Vincenzo Gallelli
Appl. Sci. 2019, 9(15), 3197; https://doi.org/10.3390/app9153197 - 6 Aug 2019
Cited by 26 | Viewed by 4007
Abstract
Steelmaking industries produce a large amount of solid wastes that need to be adequately managed in order to ensure environmental sustainability and reduce the impact of their disposal on earth pollution. Electric arc furnace (EAF) slags are those wastes deriving from secondary steelmaking [...] Read more.
Steelmaking industries produce a large amount of solid wastes that need to be adequately managed in order to ensure environmental sustainability and reduce the impact of their disposal on earth pollution. Electric arc furnace (EAF) slags are those wastes deriving from secondary steelmaking production; these slags can be re-used and recycled in many industrial applications such as the production of asphalt mixes. In this paper authors investigate the surface performance of EAF slags used as second-hand aggregate in asphalt mixes. In particular, slags behavior under polishing is compared to other types of aggregate commonly used for asphalt concrete such as limestone, basalt, and kinginzite. Several devices (skid tester, laser profilometer, polishing machine) were used to collect experimental data; the analysis of microtexture was carried out by comparing aggregate surface performance before and after polishing. Results show that EAF slags are positively comparable to basalt as concerns the polishing behavior; good correlations between skid resistance and some microtexture indicators are also carried out. Full article
(This article belongs to the Special Issue Asphalt Materials)
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<p>Selected aggregates: (<b>a</b>) Basalt (ID: R); (<b>b</b>) EAF slags (ID: A); (<b>c</b>) kinginzite (ID: K); (<b>d</b>) limestone (ID: C).</p> Full article ">Figure 2
<p>Specimen equipped with preset mask by profilometric alignments (longitudinal A-A, B-B; and crosswise C-C, D-D, E-E) for surface texture investigation.</p> Full article ">Figure 3
<p>Contactless laser profilometer.</p> Full article ">Figure 4
<p>Accelerated polishing machine: (<b>a</b>) revolving wheel; (<b>b</b>) polishing tire-wheel by corn emery.</p> Full article ">Figure 5
<p>(<b>a</b>) British pendulum skid tester; (<b>b</b>) specimen block on the base plate.</p> Full article ">Figure 6
<p>Average ΔBPN% (British Pendulum Number) for each aggregate after the accelerated polishing process.</p> Full article ">Figure 7
<p>Average Δ<span class="html-italic">R<sub>i</sub></span> for each aggregate after polishing.</p> Full article ">Figure 8
<p>Schematization of fragmentation phenomenon of the aggregate surfaces under polishing procedure.</p> Full article ">Figure 9
<p>Examples of profile segments from the examined aggregates before and after polishing process: (<b>a</b>) basalt; (<b>b</b>) EAF Slags; (<b>c</b>) kinginzite; (<b>d</b>) limestone.</p> Full article ">Figure 10
<p>Relationship between percentage variations of BPN and roughness descriptors: (<b>a</b>) ΔR<sub>A</sub> vs. ΔBPN; (<b>b</b>) ΔR<sub>Q</sub> vs. ΔBPN; (<b>c</b>) ΔR<sub>Z</sub> vs. ΔBPN; (<b>d</b>) R<sub>Q</sub> * and R<sub>Q</sub> vs. BPN * and BPN.</p> Full article ">
34 pages, 2566 KiB  
Review
Computer Vision in Autonomous Unmanned Aerial Vehicles—A Systematic Mapping Study
by Lidia María Belmonte, Rafael Morales and Antonio Fernández-Caballero
Appl. Sci. 2019, 9(15), 3196; https://doi.org/10.3390/app9153196 - 5 Aug 2019
Cited by 48 | Viewed by 9965
Abstract
Personal assistant robots provide novel technological solutions in order to monitor people’s activities, helping them in their daily lives. In this sense, unmanned aerial vehicles (UAVs) can also bring forward a present and future model of assistant robots. To develop aerial assistants, it [...] Read more.
Personal assistant robots provide novel technological solutions in order to monitor people’s activities, helping them in their daily lives. In this sense, unmanned aerial vehicles (UAVs) can also bring forward a present and future model of assistant robots. To develop aerial assistants, it is necessary to address the issue of autonomous navigation based on visual cues. Indeed, navigating autonomously is still a challenge in which computer vision technologies tend to play an outstanding role. Thus, the design of vision systems and algorithms for autonomous UAV navigation and flight control has become a prominent research field in the last few years. In this paper, a systematic mapping study is carried out in order to obtain a general view of this subject. The study provides an extensive analysis of papers that address computer vision as regards the following autonomous UAV vision-based tasks: (1) navigation, (2) control, (3) tracking or guidance, and (4) sense-and-avoid. The works considered in the mapping study—a total of 144 papers from an initial set of 2081—have been classified under the four categories above. Moreover, type of UAV, features of the vision systems employed and validation procedures are also analyzed. The results obtained make it possible to draw conclusions about the research focuses, which UAV platforms are mostly used in each category, which vision systems are most frequently employed, and which types of tests are usually performed to validate the proposed solutions. The results of this systematic mapping study demonstrate the scientific community’s growing interest in the development of vision-based solutions for autonomous UAVs. Moreover, they will make it possible to study the feasibility and characteristics of future UAVs taking the role of personal assistants. Full article
(This article belongs to the Section Computing and Artificial Intelligence)
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<p>Systematic mapping process.</p> Full article ">Figure 2
<p>Systematic search consort diagram.</p> Full article ">Figure 3
<p>Classification scheme.</p> Full article ">Figure 4
<p>Examples of vision-based tasks. (<b>a</b>) visual navigation: <b>a.1</b> (reprinted from [<a href="#B19-applsci-09-03196" class="html-bibr">19</a>] under the terms of the Creative Commons Attribution License), <b>a.2</b> (reprinted by permission from Springer Nature: [<a href="#B30-applsci-09-03196" class="html-bibr">30</a>], Copyright 2012); (<b>b</b>) vision-based control: <b>b.1</b> (reprinted from [<a href="#B31-applsci-09-03196" class="html-bibr">31</a>] under the terms of the Creative Commons Attribution License), <b>b.2</b> (reprinted from [<a href="#B32-applsci-09-03196" class="html-bibr">32</a>] by permission from Taylor &amp; Francis Ltd); (<b>c</b>) vision-based tracking/guidance: <b>c.1</b> (illustration of a target tracking mission, e.g. [<a href="#B33-applsci-09-03196" class="html-bibr">33</a>]), <b>c.2</b> (reprinted from [<a href="#B34-applsci-09-03196" class="html-bibr">34</a>], Copyright 2010, with permission from Elsevier); (<b>d</b>) vision-based sense-and-avoid: <b>d.1</b> (reprinted from [<a href="#B29-applsci-09-03196" class="html-bibr">29</a>] under the terms of the Creative Commons Attribution License), <b>d.2</b> (reprinted from [<a href="#B35-applsci-09-03196" class="html-bibr">35</a>] by permission from John Wiley and Sons).</p> Full article ">Figure 5
<p>Classes of Unmanned Aerial Vehicles (UAVs): Examples of commercial and prototype aircraft. (<b>a</b>) fixed-wing UAV: <b>a.1</b> Sig rascal model (reprinted from [<a href="#B53-applsci-09-03196" class="html-bibr">53</a>] by permission from American Society of Civil Engineers), <b>a.2</b> fixed-wing platform (reprinted from [<a href="#B38-applsci-09-03196" class="html-bibr">38</a>] under the terms of the Creative Commons Attribution License); (<b>b</b>) rotatory-wing UAV: <b>b.1</b> Yamaha Rmax helicopter (reprinted from [<a href="#B54-applsci-09-03196" class="html-bibr">54</a>] under the terms of the Creative Commons Attribution License), <b>b.2</b> experimental platform based on an Ascending Technologies Pelican quadrotor (reprinted from [<a href="#B35-applsci-09-03196" class="html-bibr">35</a>] by permission from John Wiley and Sons); (<b>c</b>) flapping-wing UAV: <b>c.1</b> Robo Raven V (reprinted from [<a href="#B55-applsci-09-03196" class="html-bibr">55</a>] under the terms of the Creative Commons Attribution License), <b>c.2</b> Carbonsail Ornithopter kit (reprinted from [<a href="#B49-applsci-09-03196" class="html-bibr">49</a>] under the terms of the Creative Commons Attribution License); (<b>d</b>) airship: <b>d.1</b> Airship ACC – 15X developed by CS AERO (<a href="https://www.csaero.cz/en" target="_blank">https://www.csaero.cz/en</a>), <b>d.2</b> Skye drone developed by AEROTAIN (<a href="http://www.aerotain.com/" target="_blank">http://www.aerotain.com/</a>).</p> Full article ">Figure 6
<p>Classes of vision system and examples of configurations (location and orientation). (<b>a.1</b>) monocular (reprinted from [<a href="#B67-applsci-09-03196" class="html-bibr">67</a>] under the terms of the Creative Commons Attribution License); (<b>a.2</b>) multi-camera (reprinted by permission from Springer Nature: [<a href="#B68-applsci-09-03196" class="html-bibr">68</a>], Copyright 2014); (<b>a.3</b>) stereo (reprinted by permission from Springer Nature: [<a href="#B69-applsci-09-03196" class="html-bibr">69</a>], Copyright 2011); (<b>b.1</b>) on board camera pointing downward (reprinted by permission from Springer Nature: [<a href="#B18-applsci-09-03196" class="html-bibr">18</a>], Copyright 2015); (<b>b.2</b>) on board stereo camera pointing forward (reprinted by permission from Springer Nature: [<a href="#B70-applsci-09-03196" class="html-bibr">70</a>], Copyright 2013); (<b>b.3</b>) on ground stereo camera pointing toward the UAV (reprinted from [<a href="#B66-applsci-09-03196" class="html-bibr">66</a>] under the terms of the Creative Commons Attribution License.)</p> Full article ">Figure 7
<p>Annual trend of publications.</p> Full article ">Figure 8
<p>Quartile distribution of the number of journals and papers according to Journal Citation Reports (year 2017).</p> Full article ">Figure 9
<p>Category distribution over the database.</p> Full article ">Figure 10
<p>Annual trend per category.</p> Full article ">Figure 11
<p>UAV class distribution over the database.</p> Full article ">Figure 12
<p>Annual trend per UAV class.</p> Full article ">Figure 13
<p>UAV class distribution over the categories.</p> Full article ">Figure 14
<p>Vision system class distribution over the database.</p> Full article ">Figure 15
<p>Annual trend per vision system.</p> Full article ">Figure 16
<p>Vision system distribution over the categories.</p> Full article ">Figure 17
<p>Validation process distribution over the database.</p> Full article ">Figure 18
<p>Papers per validation process.</p> Full article ">Figure 19
<p>Papers per flight conditions.</p> Full article ">
10 pages, 789 KiB  
Article
Online Knowledge Learning Model Based on Gravitational Field Theory
by Wenfei Ji, Tonghai Jiang, Meng Wang, Xinyu Tang, Guang Chen and Shan Yang
Appl. Sci. 2019, 9(15), 3195; https://doi.org/10.3390/app9153195 - 5 Aug 2019
Viewed by 3151
Abstract
Currently, low-dimensional embedded representation learning models are the mainstream approach in knowledge representation research, due to ease of calculation and ability to utilize the spatial relationship between knowledge areas, which benefit from static knowledge learning. However, these models cannot update and learn knowledge [...] Read more.
Currently, low-dimensional embedded representation learning models are the mainstream approach in knowledge representation research, due to ease of calculation and ability to utilize the spatial relationship between knowledge areas, which benefit from static knowledge learning. However, these models cannot update and learn knowledge online. Although using update strategies to update the knowledge base has been proposed by some scholars, this still requires retraining of knowledge and does not use the previous learning parameters and models. TransOnLine, an online knowledge learning method based on the theory of gravitational field, inspired by the fact that the forces acting on two objects in a gravitational field are only related to the distances between objects, rebalances the knowledge space caused by new knowledge through dynamic programming via introducing the spatial energy function and energy transfer function to solve the above problems. TransOnLine can reuse the parameters and models of previous learning. Experiments show that the performance of the TransOnLine method is close to state-of-the-art methods, and it is suitable for online learning and updating a relational-intensive knowledge base. Full article
(This article belongs to the Section Computing and Artificial Intelligence)
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<p>This is a figure for the energy of changed knowledge absorbed by knowledge in space.</p> Full article ">Figure 2
<p>The result of TransOnLine compared with TransE. (<b>a</b>) The result of head prediction where step <span class="html-italic">l</span> = 1; (<b>b</b>) the result of tail prediction where step <span class="html-italic">l</span> = 1; (<b>c</b>) the result of TransOnline with different steps <span class="html-italic">l</span>.</p> Full article ">Figure 3
<p>The results of DRA on the learned vectors. (<b>a</b>) DRA result where <span class="html-italic">l</span> = 2; (<b>b</b>) DRA result where <span class="html-italic">l</span> = 3.</p> Full article ">
18 pages, 6346 KiB  
Article
Integration of Reversible Heat Pumps in Trigeneration Systems for Low-Temperature Renewable District Heating and Cooling Microgrids
by Luca Urbanucci, Daniele Testi and Joan Carles Bruno
Appl. Sci. 2019, 9(15), 3194; https://doi.org/10.3390/app9153194 - 5 Aug 2019
Cited by 6 | Viewed by 4240
Abstract
District heating and cooling networks based on trigeneration systems and renewable energy technologies are widely acknowledged as an energy efficient and environmentally benign solution. These energy systems generally include back-up units, namely fossil-fuel boilers and electric chillers, to enhance system flexibility and cover [...] Read more.
District heating and cooling networks based on trigeneration systems and renewable energy technologies are widely acknowledged as an energy efficient and environmentally benign solution. These energy systems generally include back-up units, namely fossil-fuel boilers and electric chillers, to enhance system flexibility and cover peak energy demand. On the other hand, 4th generation district heating networks are characterized by low-temperature water distribution to improve energy and exergy efficiencies. Moreover, reversible heat pumps are a versatile technology, capable of providing both heating and cooling, alternately. In this paper, the integration of reversible heat pumps as single back-up units in hybrid renewable trigeneration systems serving low-energy micro-district heating and cooling networks is investigated. A detailed modeling of the system is provided, considering part-load and ambient condition effects on the performance of the units. Size and annual operation of the proposed system are optimized in a case study, namely a large office building located in Pisa (Italy), by means of a genetic algorithm-based procedure. A comparison with the conventional trigeneration system is performed in terms of economic and environmental perspectives. Results show that the integration of reversible heat pumps is an economically viable solution capable of reducing by 7% the equivalent annual cost, increasing the installed power of renewables up to 23%, and lowering by 11% carbon dioxide emissions, compared to the energy system with conventional back-up units. Full article
(This article belongs to the Special Issue Urban District Heating and Cooling Technologies)
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<p>Schematics of the compared energy systems.</p> Full article ">Figure 2
<p>Part-load efficiencies of the ICE.</p> Full article ">Figure 3
<p>Part-load correction factors for the absorption chiller, reversible heat pump, and electric chiller.</p> Full article ">Figure 4
<p>Optimization procedure.</p> Full article ">Figure 5
<p>Hourly energy demand data of the case study.</p> Full article ">Figure 6
<p>Sankey diagrams of the annual electricity balance for (<b>a</b>) traditional and (<b>b</b>) novel configurations.</p> Full article ">Figure 7
<p>Sankey diagrams of the annual thermal energy balances for (<b>a</b>) traditional and (<b>b</b>) novel configurations.</p> Full article ">Figure 8
<p>Optimal operation: electricity flows in a typical winter week.</p> Full article ">Figure 9
<p>Optimal operation: heating demand and load shares in a typical week.</p> Full article ">Figure 10
<p>Optimal operation: electricity flows in a typical summer week.</p> Full article ">Figure 11
<p>Optimal operation: cooling demand and load shares in a typical week.</p> Full article ">
16 pages, 2604 KiB  
Article
An EKF-Based Method and Experimental Study for Small Leakage Detection and Location in Natural Gas Pipelines
by Qingmin Hou and Weihang Zhu
Appl. Sci. 2019, 9(15), 3193; https://doi.org/10.3390/app9153193 - 5 Aug 2019
Cited by 8 | Viewed by 3767
Abstract
Small leaks in natural gas pipelines are hard to detect, and there are few studies on this problem in the literature. In this paper, a method based on the extended Kalman filter (EKF) is proposed to detect and locate small leaks in natural [...] Read more.
Small leaks in natural gas pipelines are hard to detect, and there are few studies on this problem in the literature. In this paper, a method based on the extended Kalman filter (EKF) is proposed to detect and locate small leaks in natural gas pipelines. First, the method of a characteristic line is used to establish a discrete model of transient pipeline flow. At the same time, according to the basic idea of EKF, a leakage rate is distributed to each segment of the discrete model to obtain a model with virtual multi-point leakage. As such, the virtual leakage rate becomes a component of the state variables in the model. Secondly, system noise and measurement noise are considered, and the optimal hydraulic factors such as leakage rate are estimated using EKF. Finally, by using the idea of an equivalent pipeline, the actual leakage rate is calculated and the location of leakage on the pipeline is assessed. Simulation and experimental results show that this method can consistently predict the leakage rate and location and is sensitive to small leakages in a natural gas pipeline. Full article
(This article belongs to the Special Issue Recent Advances in Structural Health Monitoring and Nondestructive Testing in Civil Engineering)
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<p>A real leakage in a continuous pipeline model.</p> Full article ">Figure 2
<p>Virtual multi-point leakages in a discrete pipeline model.</p> Full article ">Figure 3
<p>Discretization for virtual multi-point leakage in a pipeline.</p> Full article ">Figure 4
<p>Pressure simulation data.</p> Full article ">Figure 5
<p>Estimated leak rate using simulation data. EKF: extended Kalman filter.</p> Full article ">Figure 6
<p>Estimated leak location using simulation data.</p> Full article ">Figure 7
<p>The system diagram of the gas pipeline leak detection experiment testbed.</p> Full article ">Figure 8
<p>Photos of the gas pipeline leak detection testbed.</p> Full article ">Figure 9
<p>Estimated leakage rate using experimental data.</p> Full article ">Figure 10
<p>Estimated leak position using experimental data.</p> Full article ">
14 pages, 4415 KiB  
Article
Short-Term Forecasting of Power Production in a Large-Scale Photovoltaic Plant Based on LSTM
by Mingming Gao, Jianjing Li, Feng Hong and Dongteng Long
Appl. Sci. 2019, 9(15), 3192; https://doi.org/10.3390/app9153192 - 5 Aug 2019
Cited by 41 | Viewed by 4907
Abstract
Photovoltaic (PV) power is attracting more and more concerns. Power output prediction, as a necessary technical requirement of PV plants, closely relates to the rationality of power grid dispatch. If the accuracy of power prediction in PV plants can be further enhanced by [...] Read more.
Photovoltaic (PV) power is attracting more and more concerns. Power output prediction, as a necessary technical requirement of PV plants, closely relates to the rationality of power grid dispatch. If the accuracy of power prediction in PV plants can be further enhanced by forecasting, stability of power grid will be improved. Therefore, a 1-h-ahead power output forecasting based on long-short-term memory (LSTM) networks is proposed. The forecasting output of the model is based on the time series of 1-h-ahead numerical weather prediction to reveal the spatio-temporal characteristic. The comprehensive meteorological conditions, including different types of season and weather conditions, were considered in the model, and parameters of LSTM models were investigated simultaneously. Analysis of prediction result reveals that the proposed model leads to a superior prediction performance compared with traditional PV output power predictions. The accuracy of output power prediction is enhanced by 3.46–13.46%. Full article
(This article belongs to the Special Issue Latest Trends in Renewable Energy Systems and PV Based DC Microgrids)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Annual newly installed capacity of PV (2011–2017).</p> Full article ">Figure 2
<p>General overview of recurrent neural networks.</p> Full article ">Figure 3
<p>A LSTM (long short-term memory) unit in the first layer for time step (t).</p> Full article ">Figure 4
<p>Flowchart of PV power forecasting design.</p> Full article ">Figure 5
<p>Diagram of PV power forecasting using LSTM.</p> Full article ">Figure 6
<p>Solar irradiation (SI), air temperature (AT), relative humidity (RH), wind speed (WS), and PV power (P).</p> Full article ">Figure 7
<p>The four seasons’ periods over diurnal variations in irradiance (spring: 12.3 h; summer: 14.7 h; autumn: 12.7 h; winter: 10.2 h).</p> Full article ">Figure 8
<p>Photovoltaic system power output under different weather conditions.</p> Full article ">Figure 9
<p>Comparison of training results of different algorithms and actual values in summer (from 1 June to 31 July 2017).</p> Full article ">Figure 10
<p>Short-term PV power forecasting in spring by various algorithms. (<b>a</b>): the general forecasting power trend of three days (<b>b</b>): the trend in the first 5 hours in (a) (<b>c</b>): the trend from 28th to 32th hour in (a).</p> Full article ">Figure 11
<p>Short-term PV power forecasting in summer by various algorithms.</p> Full article ">Figure 12
<p>Short-term PV power forecasting in autumn by various algorithms.</p> Full article ">Figure 13
<p>Short-term PV power forecasting in winter by various algorithms.</p> Full article ">
8 pages, 521 KiB  
Communication
Differential Efficacy of Two Dental Implant Decontamination Techniques in Reducing Microbial Biofilm and Re-Growth onto Titanium Disks In Vitro
by Aida Meto, Enrico Conserva, Francesco Liccardi, Bruna Colombari, Ugo Consolo and Elisabetta Blasi
Appl. Sci. 2019, 9(15), 3191; https://doi.org/10.3390/app9153191 - 5 Aug 2019
Cited by 12 | Viewed by 3324
Abstract
Dental implants are crucial therapeutic devices for successful substitution of missing teeth. Failure cases are mainly pathogen-associated events, allowing clinical progression toward peri-mucositis or peri-implantitis. The aim of this study was to compare the performance of two mechanical decontamination systems, Nickel-Titanium brush (Brush) [...] Read more.
Dental implants are crucial therapeutic devices for successful substitution of missing teeth. Failure cases are mainly pathogen-associated events, allowing clinical progression toward peri-mucositis or peri-implantitis. The aim of this study was to compare the performance of two mechanical decontamination systems, Nickel-Titanium brush (Brush) and Air-Polishing system with 40 µm bicarbonate powder (BIC-40), by means of a novel bioluminescence-based model that measures microbial load in real time. Briefly, 30 disks were contaminated using the bioluminescent Pseudomonas aeruginosa strain (BLI-P. aeruginosa), treated with Brush (30 s rounds, for 90 s) or BIC-40 (30 s, at 5 mm distance) procedure, and then assessed for microbial load, particularly, biofilm removal and re-growth. Our results showed that Brush and BIC-40 treatment reduced microbial load of about 1 and more than 3 logs, respectively. Furthermore, microbial re-growth onto Brush-treated disks rapidly occurred, while BIC-40-treated disks were slowly recolonized, reaching levels of microbial load consistently below those observed with the controls. In conclusion, we provide evidence on the good performance of BIC-40 as titanium device-decontamination system, the clinical implication for such findings will be discussed. Full article
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<p><span class="html-italic">P. aeruginosa</span> biofilm formation onto Titanium disks and residual microbial load, following Ni-Ti brush and AirPol BIC-40 decontamination treatments. Microbial load was assessed on treated and untreated disks, by bioluminescence assay; the results are given as RLU/s and number of viable cells (CFU/disk).</p> Full article ">Figure 2
<p>Kinetic evaluation of <span class="html-italic">P. aeruginosa</span> biofilm re-growth onto titanium disks, following decontamination by Ni-Ti Brush and AirPol BIC-40 systems. Microbial load was kinetically assessed on treated and untreated disks, by bioluminescence assay. The results are expressed as microbial load ratio between treated and untreated disks. The ratio = 1 (dotted line) indicates superimposable microbial load in treated and untreated groups.</p> Full article ">
16 pages, 2003 KiB  
Article
Pursuer’s Control Strategy for Orbital Pursuit-Evasion-Defense Game with Continuous Low Thrust Propulsion
by Junfeng Zhou, Lin Zhao, Jianhua Cheng, Shuo Wang and Yipeng Wang
Appl. Sci. 2019, 9(15), 3190; https://doi.org/10.3390/app9153190 - 5 Aug 2019
Cited by 11 | Viewed by 4086
Abstract
This paper studies the orbital pursuit-evasion-defense problem with the continuous low thrust propulsion. A control strategy for the pursuer is proposed based on the fuzzy comprehensive evaluation and the differential game. First, the system is described by the Lawden’s equations, and simplified by [...] Read more.
This paper studies the orbital pursuit-evasion-defense problem with the continuous low thrust propulsion. A control strategy for the pursuer is proposed based on the fuzzy comprehensive evaluation and the differential game. First, the system is described by the Lawden’s equations, and simplified by introducing the relative state variables and the zero effort miss (ZEM) variables. Then, the objective function of the pursuer is designed based on the fuzzy comprehensive evaluation, and the analytical necessary conditions for the optimal control strategy are presented. Finally, a hybrid method combining the multi-objective genetic algorithm and the multiple shooting method is proposed to obtain the solution of the orbital pursuit-evasion-defense problem. The simulation results show that the proposed control strategy can handle the orbital pursuit-evasion-defense problem effectively. Full article
(This article belongs to the Special Issue Control and Soft Computing)
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<p>The local-vertical local-horizontal (LVLH) coordinate system.</p> Full article ">Figure 2
<p>The position of each player changing with time in (<b>a</b>) x-axis, (<b>b</b>) y-axis, and (<b>c</b>) z-axis.</p> Full article ">Figure 3
<p>The distance between the pursuer and the defender changing with time.</p> Full article ">Figure 4
<p>The curves of the control variable of each player with time in (<b>a</b>) x-axis, (<b>b</b>) y-axis, and (<b>c</b>) z-axis.</p> Full article ">Figure 5
<p>The curves of zero-control miss distance with time in (<b>a</b>) x-axis, (<b>b</b>) y-axis, and (<b>c</b>) z-axis.</p> Full article ">Figure 6
<p>The position of each player changing over time in (<b>a</b>) x-axis, (<b>b</b>) y-axis, and (<b>c</b>) z-axis.</p> Full article ">Figure 7
<p>The distance between the pursuer and the defender changing over time.</p> Full article ">Figure 8
<p>The control variable of each player changing over time in (<b>a</b>) x-axis, (<b>b</b>) y-axis, and (<b>c</b>) z-axis.</p> Full article ">Figure 9
<p>The position of each player changing over time in (<b>a</b>) x-axis, (<b>b</b>) y-axis, and (<b>c</b>) z-axis.</p> Full article ">Figure 10
<p>The control variable of each player changing over time in (<b>a</b>) x-axis, (<b>b</b>) y-axis, and (<b>c</b>) z-axis.</p> Full article ">Figure 11
<p>The position of each player changing with time in (<b>a</b>) x-axis, (<b>b</b>) y-axis, and (<b>c</b>) z-axis.</p> Full article ">Figure 12
<p>The control variable of each player changing over time in (<b>a</b>) x-axis, (<b>b</b>) y-axis, and (<b>c</b>) z-axis.</p> Full article ">
9 pages, 1668 KiB  
Communication
Toward Creating a Portable Impedance-Based Nondestructive Testing Method for Debonding Damage Detection of Composite Structures
by Wongi S. Na and Ki-Tae Park
Appl. Sci. 2019, 9(15), 3189; https://doi.org/10.3390/app9153189 - 5 Aug 2019
Cited by 2 | Viewed by 2742
Abstract
Debonding detection of composite structures is a vital task as such damage weakens the structure leading to a failure. As adhesive bonding is a more preferable choice over the conventional mechanical fastening method, detecting debonding as early as possible could minimize the overall [...] Read more.
Debonding detection of composite structures is a vital task as such damage weakens the structure leading to a failure. As adhesive bonding is a more preferable choice over the conventional mechanical fastening method, detecting debonding as early as possible could minimize the overall maintenance costs. For this reason, a vast amount of research in the nondestructive testing field is being conducted as we speak. However, most of the methods may require well-trained experts or heavy equipment. In this study, the piezoelectric (PZT) material-based method known as the electromechanical impedance technique is investigated to seek the possibility of making the technique very cheap and portable by temporarily attaching the sensor. Furthermore, ANSYS simulation studies using smaller PZT patches as small as 0.1 mm × 0.1 mm are simulated to investigate the impedance signatures acquired from the simulations. The results show the possibility of using smaller PZT patches compared to the conventional PZT sizes of 10 mm × 10 mm for a successful damage identification process. Full article
(This article belongs to the Special Issue Nondestructive Testing in Composite Materials)
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<p>Experimental setup for the piezoelectric (PZT)–metal transducer experiment.</p> Full article ">Figure 2
<p>Impedance signature results for: (<b>a</b>) Debonding experiment; (<b>b</b>) re-attachable performance of the PZT–metal transducer.</p> Full article ">Figure 3
<p>Root-mean-square deviation (RMSD) values for the debonding experiment and total removal of the bottom plate for Test 1.</p> Full article ">Figure 4
<p>ANSYS FEM model: (<b>a</b>) PZT–metal; (<b>b</b>) mesh with 1096 elements.</p> Full article ">Figure 5
<p>Impedance signature of the PZT–metal transducer before structure attachment: (<b>a</b>) By experiment; (<b>b</b>) by simulation.</p> Full article ">Figure 6
<p>FEM model for smaller PZT sizes: (<b>a</b>) 0.1 mm PZT; (<b>b</b>) 1 mm PZT; (<b>c</b>) 5 mm PZT; (<b>d</b>) 5 mm PZT with thicker metal plate.</p> Full article ">Figure 7
<p>Simulation results for the impedance signatures of the four FEM models.</p> Full article ">
14 pages, 3093 KiB  
Letter
Active Vibration Control of Rib Stiffened Plate by Using Decentralized Velocity Feedback Controllers with Inertial Actuators
by Xiyue Ma, Lei Wang and Jian Xu
Appl. Sci. 2019, 9(15), 3188; https://doi.org/10.3390/app9153188 - 5 Aug 2019
Cited by 8 | Viewed by 3209
Abstract
Active control of low frequency vibration and sound radiation from a rib stiffened plate has great practical significance as this structure is widely applied in engineering, such as aircraft or ship fuselage shells. This paper presents an investigation on the performance of active [...] Read more.
Active control of low frequency vibration and sound radiation from a rib stiffened plate has great practical significance as this structure is widely applied in engineering, such as aircraft or ship fuselage shells. This paper presents an investigation on the performance of active vibration control of the rib stiffened plate by using decentralized velocity feedback controllers with inertial actuators. A simple modeling approach in frequency domain is proposed in this research to calculate the control performance. The theoretical model of vibrating response of the ribbed plate and the velocity feedback controllers is first established. Then, as an important part, the influences of the control gain and the number of the decentralized unit on the control performance are investigated. Results obtained demonstrate that—similar to that of the unribbed plate case—appropriately choosing the number of the unit and their feedback gains can achieve good control results. Too many units or very high feedback gains will not bring further noise reduction. Full article
(This article belongs to the Special Issue Energy Dissipation and Vibration Control: Materials, Modeling, Algorithm and Devices)
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<p>Systemic model: (<b>a</b>) active orthogonally rib stiffened plate; (<b>b</b>) the coupling effects between the base plate and the rib for the vertical rib; (<b>c</b>) the coupling effects for the horizontal rib.</p> Full article ">Figure 2
<p>The sketch of the decentralized system.</p> Full article ">Figure 3
<p>The arrangement of the feedback loops.</p> Full article ">Figure 4
<p>Schematic of the inertial actuator. (<b>a</b>) Schematic of a concept inertial actuator; (<b>b</b>) inertial actuator model.</p> Full article ">Figure 5
<p>The block diagram of the closed-loop system.</p> Full article ">Figure 6
<p>The locations and coordinates of the feedback loops.</p> Full article ">Figure 7
<p>The kinetic energy of the ribbed plate before and after control using seven feedback loops with different control gain.</p> Full article ">Figure 8
<p>The radiated sound power of the ribbed plate before and after control using seven feedback loops with different control gain.</p> Full article ">Figure 9
<p>The kinetic energy of the ribbed plate before and after control with different number of feedback loops.</p> Full article ">Figure 10
<p>The radiated sound power of the ribbed plate before and after control with different number of feedback loops.</p> Full article ">
24 pages, 7272 KiB  
Article
Multi-Media and Multi-Band Based Adaptation Layer Techniques for Underwater Sensor Networks
by Delphin Raj K M, Sun-Ho Yum, Eunbi Ko, Soo-Young Shin, Jung-Il Namgung and Soo-Hyun Park
Appl. Sci. 2019, 9(15), 3187; https://doi.org/10.3390/app9153187 - 5 Aug 2019
Cited by 15 | Viewed by 4947
Abstract
In the last few decades, underwater communication systems have been widely used for the development of navy, military, business, and safety applications, etc. However, in underwater communication systems, there are several challenging issues, such as limitations in bandwidth, propagation delay, 3D topology, media [...] Read more.
In the last few decades, underwater communication systems have been widely used for the development of navy, military, business, and safety applications, etc. However, in underwater communication systems, there are several challenging issues, such as limitations in bandwidth, propagation delay, 3D topology, media access control, routing, resource utilization, and power constraints. Underwater communication systems work under severe channel conditions such as ambient noise, frequency selectivity, multi-path and Doppler shifts. In order to collect and transmit the data in effective ways, multi-media/multi-band-based adaptation layer technology is proposed in this paper. The underwater communication scenario comprises of Unmanned Underwater Vehicles (UUVs), Surface gateways, sensor nodes, etc. The transmission of data starts from sensor nodes to surface gateway in a hierarchical manner through multiple channels. In order to provide strong and reliable communication underwater, the adaptation layer uses a multi-band/multi-media approach for transferring data. Hence, in this paper, existing techniques for splitting the band such as Orthogonal Frequency-Division Multiple Access (OFDMA), Frequency-Division Multiple Access (FDMA), or Orthogonal Frequency-Division Multiplexing (OFDM) are used for splitting the frequency band, and the medium selection mechanism is proposed to carry the signal through different media such as Acoustic, Visible Light Communication (VLC), and Infrared (IR) signals in underwater. For the channel selection mechanism, two phases are involved: 1. Finding the distance of near and far nodes using Manhattan method, and 2. Medium selection and data transferring algorithm for choosing different media. Full article
(This article belongs to the Special Issue Underwater Acoustic Communications and Networks)
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<p>General underwater architecture and communication technologies.</p> Full article ">Figure 2
<p>Communication scheme of the OFDM approach.</p> Full article ">Figure 3
<p>Protocol stack design for multi-band/multi-media techniques.</p> Full article ">Figure 4
<p>MAC extension and adaptation layer.</p> Full article ">Figure 5
<p>Physical layer components and workflow.</p> Full article ">Figure 6
<p>Medium selection design scheme inside adaptation layer.</p> Full article ">Figure 7
<p>Nearby nodes distance calculation using Manhattan method.</p> Full article ">Figure 8
<p>Far-away node distance calculation using Manhattan method.</p> Full article ">Figure 9
<p>Medium selection mechanism.</p> Full article ">Figure 10
<p>Surveillance using the multi-media mechanism.</p> Full article ">Figure 11
<p>Source to sink node routing using the medium selection mechanism.</p> Full article ">Figure 12
<p>Multi-media modem setup and operation.</p> Full article ">Figure 13
<p>Multi-media and multi-band modem setup and operations.</p> Full article ">Figure 14
<p>Pure water test using a small water tank.</p> Full article ">Figure 15
<p>Salty water test using large water tank.</p> Full article ">Figure 16
<p>Open seabed test.</p> Full article ">
10 pages, 2239 KiB  
Article
Effect of Pore Characteristics in Polyvinylidene Fluoride/Fumed Silica Membranes on Mass Flux in Solar-Assisted Evaporation Applications
by Mona Bahman, Maryam AlNahyan, Ibrahim Mustafa and Faisal AlMarzooqi
Appl. Sci. 2019, 9(15), 3186; https://doi.org/10.3390/app9153186 - 5 Aug 2019
Cited by 6 | Viewed by 3291
Abstract
Although important, very little has been demonstrated in the literature to experimentally demonstrate the effects of porosities and pore size on the evaporation flux in polymeric membranes. Additionally, we suspect that a batch-mode setup, i.e., stagnant water, could cause a build-up of heat [...] Read more.
Although important, very little has been demonstrated in the literature to experimentally demonstrate the effects of porosities and pore size on the evaporation flux in polymeric membranes. Additionally, we suspect that a batch-mode setup, i.e., stagnant water, could cause a build-up of heat in the system, influencing the evaporation mass-flux mechanism, and jeopardizing the ability to attain a real correlation between evaporation and effects of pore characteristics. Herein, we fabricate polyvinylidene fluoride membranes containing variable amounts of a Fumed Silica additive to achieve membranes with variable properties, and we investigate the change in the performance of the solar-assisted thin-film evaporation utilizing an in-house built continuous flow evaporation setup (to avoid heat build-up effects in the bulk of the water and demonstrate a continuous flow system). Our membrane design approach had two important advantages: (1) the achievement of similar heat transfer and solar absorbance properties and (2) the achievement of variable pore sizes and volume porosities. We show that the mass flux increased as the mean pore size decreased, indicating that the mode of mass transfer occurred due to the thin-film region of the meniscus from the small fluid velocities near the interface, and we attribute the results to the increase in the capillary pumping effects through the mesoporous channels as they get thinner. Full article
(This article belongs to the Section Nanotechnology and Applied Nanosciences)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Fabrication of PVDF/FS membranes; (<b>a</b>) a fixed amount of PVDF was first added into a beaker, (<b>b</b>) variable ratios of FS and DMAc were added, (<b>c</b>) stirred for 8 h, (<b>d</b>) sonicated for 10 min in a sonication bath to remove all bubbles, (<b>e</b>) membranes were cast on a non-woven support layer, (<b>f</b>) the cast layer was exposed for 2 min at 70% humidity after which it was immersed in a coagulation bath, and (<b>g</b>) the membrane was air-dried for 24 h at 25 °C.</p> Full article ">Figure 2
<p>Schematic of the experimental setup illustrating the data acquisition and the connections of the device.</p> Full article ">Figure 3
<p>SEM images of the fabricated membranes. The results show that the FS particles agglomerated more as the amount of FS content added increased. The results also indicate that different contents of FS resulted in variable pore sizes, where the PVDF-FS4 and the PVDF-FS7 resembled the lowest and the largest pore sizes, respectively.</p> Full article ">Figure 4
<p>(<b>a</b>) Contact angles (<b>b</b>) Porosity and Mean flow pore diameter, and (<b>c</b>) absorbance measurements for our PVDF-FS membranes. The results show that the PVDF-FS4 membrane resembled the lowest contact angle, the smallest mean pore diameter, and the largest volume porosity, indicating that there was an optimal FS content value to achieve the desired properties. All membranes showed similar absorbance behavior over all of the wavelengths studied.</p> Full article ">Figure 5
<p>(<b>a</b>) Recorded mass flux over time with and without solar irradiation, (<b>b</b>) Calculated amount of flux driven solely due to 1 sun of solar irradiation, (<b>c</b>) Change in temperature showing that the heat accumulation due to heat transfer properties was negligible. The results indicate that all of our membranes were stable over 6 h, and that the PVDF-FS4 exhibited the highest performance as compared to the PVDF-FS3, PVDF-FS5, PVDF-FS7, and PVDF membranes.</p> Full article ">
17 pages, 15790 KiB  
Article
Analysis of a Main Cabin Ventilation System in a Jack-Up Offshore Platform Part I: Numerical Modelling
by Yingchun Xie, Zepeng Zheng, Huibin Wang, Zhen Xu, Guijie Liu, Reza Malekian and Zhixiong Li
Appl. Sci. 2019, 9(15), 3185; https://doi.org/10.3390/app9153185 - 5 Aug 2019
Cited by 4 | Viewed by 4153
Abstract
This work aims to measure the thermodynamics of a main cabin ventilation system in a JU-2000E jack-up offshore platform. A three-dimensional (3D) physical model of the ventilation system was established, and the computational fluid dynamics (CFD) software (ANSYS FLUENT) was used to calculate [...] Read more.
This work aims to measure the thermodynamics of a main cabin ventilation system in a JU-2000E jack-up offshore platform. A three-dimensional (3D) physical model of the ventilation system was established, and the computational fluid dynamics (CFD) software (ANSYS FLUENT) was used to calculate the model thermodynamics. Numerical analysis was performed to investigate the influence mechanisms of the ventilation factors such as ventilation temperature and volume on the ventilation performance. The analysis results demonstrate that (1) top-setting of the exhaust vents is more effective than the side-setting in terms of high temperature reduction, (2) small ventilation temperature and volume can improve the ventilation efficiency, and (3) proper shutdown selection of the backup diesel engine can enhance the ventilation performance. Furthermore, the effect of humidity for the ventilation air was investigated. Lastly, an experimental platform was developed based on the simulation model. Experimental tests were carried out to evaluate the shutdown selection of the backup engine and have shown consistent results to that of the simulation model. The findings of this study provide valuable guidance in designing the ventilation system in the JU-2000E jack-up offshore platform. Full article
(This article belongs to the Special Issue Fault Diagnosis of Rotating Machine)
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<p>Three-dimensional model of the main cabin of the offshore platform.</p> Full article ">Figure 2
<p>(<b>a</b>) Overall layout of engine room; (<b>b</b>) Details of the diesel engine module; (<b>c</b>) Ventilation design; (<b>d</b>) Exhaust gas passage.</p> Full article ">Figure 2 Cont.
<p>(<b>a</b>) Overall layout of engine room; (<b>b</b>) Details of the diesel engine module; (<b>c</b>) Ventilation design; (<b>d</b>) Exhaust gas passage.</p> Full article ">Figure 3
<p>Shutdown order: (<b>a</b>) overview, (<b>b</b>) left side, (<b>c</b>) middle side, and (<b>d</b>) right side.</p> Full article ">Figure 4
<p>Four different arrangements of the exhaust vent: (<b>a</b>) left side arrangement, (<b>b</b>) left-right sides arrangement, (<b>c</b>) left-side and left-roof arrangement, and (<b>d</b>) left-side and right-roof arrangement.</p> Full article ">Figure 5
<p>Cloud and streamline maps of the high-temperature distributions (&gt;55 °C). Volume sizes of the four arrangements are: (<b>a</b>) 589.1 m<sup>3</sup>, (<b>b</b>) 645.3 m<sup>3</sup>, (<b>c</b>) 418.7 m<sup>3</sup>, and (<b>d</b>) 593.9 m<sup>3</sup>.</p> Full article ">Figure 5 Cont.
<p>Cloud and streamline maps of the high-temperature distributions (&gt;55 °C). Volume sizes of the four arrangements are: (<b>a</b>) 589.1 m<sup>3</sup>, (<b>b</b>) 645.3 m<sup>3</sup>, (<b>c</b>) 418.7 m<sup>3</sup>, and (<b>d</b>) 593.9 m<sup>3</sup>.</p> Full article ">Figure 6
<p>High-temperature region and air outlet–exhaust vent pressure ratio.</p> Full article ">Figure 7
<p>High-temperature volumes above 50 and 55 °C, and temperature streamlines between 45 and 60 °C in the conditions of (<b>a</b>) ventilation temperature 45 °C with 0.75 nominal ventilation volume, (<b>b</b>) 45 °C with nominal volume, and (<b>c</b>) 45 °C with 1.25 nominal volume.</p> Full article ">Figure 7 Cont.
<p>High-temperature volumes above 50 and 55 °C, and temperature streamlines between 45 and 60 °C in the conditions of (<b>a</b>) ventilation temperature 45 °C with 0.75 nominal ventilation volume, (<b>b</b>) 45 °C with nominal volume, and (<b>c</b>) 45 °C with 1.25 nominal volume.</p> Full article ">Figure 8
<p>High-temperature volumes above 50 and 55 °C, and temperature streamlines between 45 and 60 °C in the conditions of (<b>a</b>) ventilation temperature 40 °C with 0.75 nominal volume, (<b>b</b>) 40 °C with nominal volume, and (<b>c</b>) 40 °C with 1.25 nominal volume.</p> Full article ">Figure 9
<p>High-temperature volumes above 50 and 55 °C, and temperature streamlines between 45 and 60 °C in the conditions of (<b>a</b>) ventilation temperature 35 °C with 0.75 nominal volume, (<b>b</b>) 35 °C with nominal volume, and (<b>c</b>) 35 °C with 1.25 nominal volume.</p> Full article ">Figure 9 Cont.
<p>High-temperature volumes above 50 and 55 °C, and temperature streamlines between 45 and 60 °C in the conditions of (<b>a</b>) ventilation temperature 35 °C with 0.75 nominal volume, (<b>b</b>) 35 °C with nominal volume, and (<b>c</b>) 35 °C with 1.25 nominal volume.</p> Full article ">Figure 10
<p>High-temperature volumes above 50 and 55 °C, and temperature streamlines between 45 and 60 °C with different spray cooling settings in <a href="#applsci-09-03185-t005" class="html-table">Table 5</a>: (<b>a</b>) 30% RH, (<b>b</b>) 50% RH, (<b>c</b>) 70% RH, and (<b>d</b>) 90% RH.</p> Full article ">Figure 11
<p>Diagram and image of the experimental platform.</p> Full article ">Figure 12
<p>Images of (<b>a</b>) heating sources and engine models, (<b>b</b>) engine thermal pack, and (<b>c</b>) axial flow ventilator.</p> Full article ">Figure 13
<p>Images of (<b>a</b>) digital vortex flowmeter, (<b>b</b>) connection of vortex flowmeter and ventilator, and (<b>c</b>) thermal Infrared Imager.</p> Full article ">Figure 14
<p>Illustration of (<b>a</b>) distribution of temperature sensors, (<b>b</b>) sensor locations, and (<b>c</b>) a PT100 temperature sensor.</p> Full article ">Figure 15
<p>Images of (<b>a</b>) temperature display, (<b>b</b>) voltage-controlled power source, (<b>c</b>) digital wattmeter and (<b>d</b>) intelligent pressure anemoscope.</p> Full article ">Figure 16
<p>Installation of the DY-100 digital vortex flowmeter.</p> Full article ">
21 pages, 7307 KiB  
Article
A Virtual Impedance Control Strategy for Improving the Stability and Dynamic Performance of VSC–HVDC Operation in Bidirectional Power Flow Mode
by Yuye Li, Kaipei Liu, Xiaobing Liao, Shu Zhu and Qing Huai
Appl. Sci. 2019, 9(15), 3184; https://doi.org/10.3390/app9153184 - 5 Aug 2019
Cited by 12 | Viewed by 4128
Abstract
It is a common practice that one converter controls DC voltage and the other controls power in two-terminal voltage source converter (VSC)–based high voltage DC (HVDC) systems for AC gird interconnection. The maximum transmission power from a DC-voltage-controlled converter to a power-controlled converter [...] Read more.
It is a common practice that one converter controls DC voltage and the other controls power in two-terminal voltage source converter (VSC)–based high voltage DC (HVDC) systems for AC gird interconnection. The maximum transmission power from a DC-voltage-controlled converter to a power-controlled converter is less than that of the opposite transmission direction. In order to increase the transmission power from a DC-voltage-controlled converter to a power-controlled converter, an improved virtual impedance control strategy is proposed in this paper. Based on the proposed control strategy, the DC impedance model of the VSC–HVDC system is built, including the output impedance of two converters and DC cable impedance. The stability of the system with an improved virtual impedance control is analyzed in Nyquist stability criterion. The proposed control strategy can improve the transmission capacity of the system by changing the DC output impedance of the DC voltage-controlled converter. The effectiveness of the proposed control strategy is verified by simulation. The simulation results show that the proposed control strategy has better dynamic performance than traditional control strategies. Full article
(This article belongs to the Special Issue HVDC for Grid Services in Electric Power Systems)
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Figure 1

Figure 1
<p>VSC–HVDC used in AC grid interconnection.</p> Full article ">Figure 2
<p>System and phase-locked loop (PLL) references.</p> Full article ">Figure 3
<p>Control structure of the converters.</p> Full article ">Figure 4
<p>DC-link voltage and the active power of the VSC–HVDC system.</p> Full article ">Figure 5
<p>Proposed control structure of the converters.</p> Full article ">Figure 6
<p>Frequency response of the impedance and verification. The solid line represents the model prediction, and the black points denote the simulation. (<b>a</b>) Disturbance signal testing. (<b>b</b>) Impedance of the DC voltage-controlled converter (<b>c</b>). Impedance of the power-controlled converter.</p> Full article ">Figure 7
<p>Equivalent model of the VSC–HVDC system.</p> Full article ">Figure 8
<p>(<b>a</b>) Nichols plots of <span class="html-italic">T<sub>m</sub></span> when transmission power is ±500 MW. (<b>b</b>) Impedance frequency responses of <span class="html-italic">Z<sub>dc</sub></span><sub>1</sub> and <span class="html-italic">Z<sub>dc</sub></span><sub>2</sub> when transmission power is ±500 MW.</p> Full article ">Figure 8 Cont.
<p>(<b>a</b>) Nichols plots of <span class="html-italic">T<sub>m</sub></span> when transmission power is ±500 MW. (<b>b</b>) Impedance frequency responses of <span class="html-italic">Z<sub>dc</sub></span><sub>1</sub> and <span class="html-italic">Z<sub>dc</sub></span><sub>2</sub> when transmission power is ±500 MW.</p> Full article ">Figure 9
<p>Impedance frequency responses of <span class="html-italic">Z<sub>dc</sub></span><sub>1</sub> and <span class="html-italic">Z<sub>dc</sub></span><sub>2</sub> under different equivalent virtual impedance values (<b>a</b>) <span class="html-italic">R<sub>eq</sub></span> and (<b>b</b>) <span class="html-italic">L<sub>eq</sub>.</span></p> Full article ">Figure 10
<p>Nichols plots of <span class="html-italic">T<sub>m</sub></span> under different equivalent virtual impedance values (<b>a</b>) <span class="html-italic">R<sub>eq</sub></span>; (<b>b</b>) <span class="html-italic">L<sub>eq</sub></span>.</p> Full article ">Figure 11
<p>Nichols plots of <span class="html-italic">T<sub>m</sub></span> under different DC cable lengths.</p> Full article ">Figure 12
<p>Nichols plots of <span class="html-italic">T<sub>m</sub></span> under different DC side capacities.</p> Full article ">Figure 13
<p>Nichols plots of <span class="html-italic">T<sub>m</sub></span> under a different grid impedance.</p> Full article ">Figure 14
<p>DC-link voltage and active power of the VSC–HVDC system under different DC cable lengths.</p> Full article ">Figure 15
<p>DC-link voltage and active power of the VSC–HVDC system under different DC side capacity.</p> Full article ">Figure 16
<p>DC-link voltage and active power of the VSC–HVDC system (<b>a</b>) under the proposed control strategy and traditional control strategy [<a href="#B13-applsci-09-03184" class="html-bibr">13</a>] and (<b>b</b>) under the proposed control strategy with different virtual impedance parameters.</p> Full article ">Figure 17
<p>DC-link voltage and active power of the VSC–HVDC system under the proposed control strategy and traditional virtual impedance.</p> Full article ">Figure 18
<p>DC-link voltage and active power of the VSC–HVDC system under different gird impedance.</p> Full article ">
29 pages, 1152 KiB  
Review
Perspectives and Challenges in Robotic Neurorehabilitation
by Riccardo Iandolo, Francesca Marini, Marianna Semprini, Matteo Laffranchi, Maddalena Mugnosso, Amel Cherif, Lorenzo De Michieli, Michela Chiappalone and Jacopo Zenzeri
Appl. Sci. 2019, 9(15), 3183; https://doi.org/10.3390/app9153183 - 5 Aug 2019
Cited by 87 | Viewed by 12427
Abstract
The development of robotic devices for rehabilitation is a fast-growing field. Nowadays, thanks to novel technologies that have improved robots’ capabilities and offered more cost-effective solutions, robotic devices are increasingly being employed during clinical practice, with the goal of boosting patients’ recovery. Robotic [...] Read more.
The development of robotic devices for rehabilitation is a fast-growing field. Nowadays, thanks to novel technologies that have improved robots’ capabilities and offered more cost-effective solutions, robotic devices are increasingly being employed during clinical practice, with the goal of boosting patients’ recovery. Robotic rehabilitation is also widely used in the context of neurological disorders, where it is often provided in a variety of different fashions, depending on the specific function to be restored. Indeed, the effect of robot-aided neurorehabilitation can be maximized when used in combination with a proper training regimen (based on motor control paradigms) or with non-invasive brain machine interfaces. Therapy-induced changes in neural activity and behavioral performance, which may suggest underlying changes in neural plasticity, can be quantified by multimodal assessments of both sensorimotor performance and brain/muscular activity pre/post or during intervention. Here, we provide an overview of the most common robotic devices for upper and lower limb rehabilitation and we describe the aforementioned neurorehabilitation scenarios. We also review assessment techniques for the evaluation of robotic therapy. Additional exploitation of these research areas will highlight the crucial contribution of rehabilitation robotics for promoting recovery and answering questions about reorganization of brain functions in response to disease. Full article
(This article belongs to the Special Issue Rehabilitation Robotics: Recent Advancements and New Perspectives about Training and Assessment of Sensorimotor Functions)
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<p>Lateral view of WristBot during combined movements in the flexion–extension and pronation–supination DOFs (degrees of freedom) (<b>A</b>) and movements in the radial–ulnar deviation DOF (<b>B</b>); posterior–lateral view of the handle of WristBot (<b>C</b>) and a frontal view of the device connected to the case, with the integrated PC and electronic control unit (<b>D</b>).</p> Full article ">Figure 2
<p>Fronto-lateral view of the Twin exoskeleton (<b>A</b>), lateral view (<b>B</b>) with a particular focus on the hip joint (motor and electromechanical interface), fronto-lateral view (<b>C</b>) of the pelvis module highlighting the pelvis structural element and the backpack containing the battery, and posterior view (<b>D</b>). Written informed consent was obtained from the subject depicted in the panels.</p> Full article ">
23 pages, 8472 KiB  
Article
The Spatial Perspective in Post-Earthquake Evaluation to Improve Mitigation Strategies: Geostatistical Analysis of the Seismic Damage Applied to a Real Case Study
by Salvador García-Ayllón, Antonio Tomás and José Luis Ródenas
Appl. Sci. 2019, 9(15), 3182; https://doi.org/10.3390/app9153182 - 5 Aug 2019
Cited by 11 | Viewed by 5221
Abstract
The analysis of damage in cities after an earthquake to implement mitigation strategies of seismic risk is a complex job that is usually full of uncertainties. Numerous variables affect the final result of the observable damage in a set of buildings in an [...] Read more.
The analysis of damage in cities after an earthquake to implement mitigation strategies of seismic risk is a complex job that is usually full of uncertainties. Numerous variables affect the final result of the observable damage in a set of buildings in an urban area. The use of methodologies capable of providing global explanations beyond the traditional unidisciplinary approach of disciplines, such as structural analysis, earthquake engineering, geotechnics, or seismology, can be very useful for improving the behavior of our cities against earthquakes. This article presents geostatistical post-earthquake analysis, an innovative approach in this field of research based on GIS spatial statistical tools to evaluate the importance of the different variables after an earthquake that may have caused damage in a city. This new framework will be applied to analyze, from a geostatistical perspective, the damage levels observed in the city of Lorca (Spain) after the earthquake of 2011; a case study where various studies have proposed different measures to mitigate the impact of future earthquakes as a consequence of focusing on different phenomena as the main variable for the damage produced. A bivariate GIS assessment will allow spatial correlation of the problems detected from a statistical point of view (inadequate design of buildings, age of the real estate stock, inefficient urban planning configurations, geological risk, etc.) and the different levels of damage that the technicians who participated in the post-earthquake phase evaluated in the city. The results obtained will allow one to hierarchize the importance of the different detected phenomena to prepare the city better against future earthquakes and to elaborate an improved seismic mitigation strategy. Full article
(This article belongs to the Special Issue Evaluation and Mitigation of Seismic Risk for Existing Buildings, Structures, and Infrastructures)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Scope of action of the earthquake in Spain (<b>a</b>) and in the Region of Murcia (<b>b</b>). Location of the city of Lorca and epicenter of the earthquake (<b>c</b>).</p> Full article ">Figure 2
<p>Map of seismic hazard in Spain (source: NCSE-02 [<a href="#B17-applsci-09-03182" class="html-bibr">17</a>], city of Lorca marked in yellow).</p> Full article ">Figure 3
<p>Examples of the soft story phenomena that occurred in Lorca in 2011 after the quake.</p> Full article ">Figure 4
<p>Effect of short columns in different buildings of the city of Lorca after the quake.</p> Full article ">Figure 5
<p>(<b>a</b>) Discretized model of the values of the amplification coefficient C, and (<b>b</b>) spatial model of the classification coefficient of the land superimposed with different levels of damage to buildings (data taken from previous work [<a href="#B22-applsci-09-03182" class="html-bibr">22</a>]).</p> Full article ">Figure 6
<p>(<b>a</b>) Pounding phenomenon of a collapsed building over another damaged area, and (<b>b</b>) pounding effect of a floor-column as a result of the unevenness in the street that generates different heights for the floors of neighboring buildings (source: authors).</p> Full article ">Figure 7
<p>(<b>a</b>) Spatial distribution of vulnerability index <span class="html-italic">I<sub>v−b</sub></span> according to the criteria in previous work [<a href="#B9-applsci-09-03182" class="html-bibr">9</a>]. (<b>b</b>) Example of the effects of inadequate seismic design in the architectural configuration of buildings linked to long unbraced parapets on the roofs (data taken from previous work [<a href="#B12-applsci-09-03182" class="html-bibr">12</a>]).</p> Full article ">Figure 8
<p>GIS cadastral database of buildings of Lorca considering different levels of damage.</p> Full article ">Figure 9
<p>Spatial distribution of (<b>a</b>) PGA and (<b>b</b>) PP during the Lorca earthquake (data taken from previous work [<a href="#B28-applsci-09-03182" class="html-bibr">28</a>]).</p> Full article ">Figure 10
<p>Example of report filled in following during the earthquake. Source is authors of this work.</p> Full article ">Figure 11
<p>Spatial distribution of the final situation of buildings used to elaborate the database.</p> Full article ">Figure 12
<p>Hot spot spatial analysis for LISA bivariate results for (<b>a</b>) <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>S</mi> <mi>S</mi> </mrow> </msub> </mrow> </semantics></math> - <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>L</mi> <mi>D</mi> <mi>B</mi> </mrow> </msub> <mtext> </mtext> </mrow> </semantics></math>, (<b>b</b>) <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>S</mi> <mi>C</mi> </mrow> </msub> </mrow> </semantics></math> - <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>L</mi> <mi>D</mi> <mi>B</mi> </mrow> </msub> <mtext> </mtext> </mrow> </semantics></math>, (<b>c</b>) <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>S</mi> <mi>A</mi> <mi>C</mi> </mrow> </msub> </mrow> </semantics></math> - <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>L</mi> <mi>D</mi> <mi>B</mi> </mrow> </msub> <mtext> </mtext> </mrow> </semantics></math>, (<b>d</b>) <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>I</mi> <mi>U</mi> <mi>C</mi> </mrow> </msub> </mrow> </semantics></math> - <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>L</mi> <mi>D</mi> <mi>B</mi> </mrow> </msub> </mrow> </semantics></math>, (<b>e</b>) <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>I</mi> <mi>A</mi> <mi>R</mi> <mi>S</mi> <mi>D</mi> </mrow> </msub> </mrow> </semantics></math> - <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>L</mi> <mi>D</mi> <mi>B</mi> </mrow> </msub> </mrow> </semantics></math>, (<b>f</b>) <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>B</mi> <mi>A</mi> </mrow> </msub> </mrow> </semantics></math> - <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>L</mi> <mi>D</mi> <mi>B</mi> </mrow> </msub> </mrow> </semantics></math>, and (<b>g</b>) <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>S</mi> <mi>F</mi> </mrow> </msub> </mrow> </semantics></math> - <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>L</mi> <mi>D</mi> <mi>B</mi> </mrow> </msub> <mtext> </mtext> </mrow> </semantics></math>.</p> Full article ">Figure 12 Cont.
<p>Hot spot spatial analysis for LISA bivariate results for (<b>a</b>) <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>S</mi> <mi>S</mi> </mrow> </msub> </mrow> </semantics></math> - <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>L</mi> <mi>D</mi> <mi>B</mi> </mrow> </msub> <mtext> </mtext> </mrow> </semantics></math>, (<b>b</b>) <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>S</mi> <mi>C</mi> </mrow> </msub> </mrow> </semantics></math> - <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>L</mi> <mi>D</mi> <mi>B</mi> </mrow> </msub> <mtext> </mtext> </mrow> </semantics></math>, (<b>c</b>) <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>S</mi> <mi>A</mi> <mi>C</mi> </mrow> </msub> </mrow> </semantics></math> - <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>L</mi> <mi>D</mi> <mi>B</mi> </mrow> </msub> <mtext> </mtext> </mrow> </semantics></math>, (<b>d</b>) <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>I</mi> <mi>U</mi> <mi>C</mi> </mrow> </msub> </mrow> </semantics></math> - <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>L</mi> <mi>D</mi> <mi>B</mi> </mrow> </msub> </mrow> </semantics></math>, (<b>e</b>) <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>I</mi> <mi>A</mi> <mi>R</mi> <mi>S</mi> <mi>D</mi> </mrow> </msub> </mrow> </semantics></math> - <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>L</mi> <mi>D</mi> <mi>B</mi> </mrow> </msub> </mrow> </semantics></math>, (<b>f</b>) <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>B</mi> <mi>A</mi> </mrow> </msub> </mrow> </semantics></math> - <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>L</mi> <mi>D</mi> <mi>B</mi> </mrow> </msub> </mrow> </semantics></math>, and (<b>g</b>) <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>S</mi> <mi>F</mi> </mrow> </msub> </mrow> </semantics></math> - <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>L</mi> <mi>D</mi> <mi>B</mi> </mrow> </msub> <mtext> </mtext> </mrow> </semantics></math>.</p> Full article ">Figure 13
<p>Triangular simulation (Kernel rounded) of the overlapping levels in the geostatistical correlations High-High (HH) and Low-Low (LL) of the pairs <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>S</mi> <mi>C</mi> </mrow> </msub> </mrow> </semantics></math> (“short columns-damage level”) and <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mrow> <mi>I</mi> <mi>U</mi> <mi>C</mi> </mrow> </msub> </mrow> </semantics></math> (“urban configurations-damage level”).</p> Full article ">
15 pages, 12177 KiB  
Article
New Implant Macrogeometry to Improve and Accelerate the Osseointegration: An In Vivo Experimental Study
by Sergio Alexandre Gehrke, Jaime Aramburú Júnior, Leticia Pérez-Díaz, Tiago Luis Eirles Treichel, Berenice Anina Dedavid, Piedad N. De Aza and Juan Carlos Prados-Frutos
Appl. Sci. 2019, 9(15), 3181; https://doi.org/10.3390/app9153181 - 5 Aug 2019
Cited by 16 | Viewed by 5291
Abstract
A new implant design with healing chambers in the threads was analyzed and compared with a conventional implant macrogeometry, both implants models with and without surface treatment. Eighty conical implants were prepared using commercially pure titanium (grade IV) by the company Implacil De [...] Read more.
A new implant design with healing chambers in the threads was analyzed and compared with a conventional implant macrogeometry, both implants models with and without surface treatment. Eighty conical implants were prepared using commercially pure titanium (grade IV) by the company Implacil De Bortoli (São Paulo, Brazil). Four groups were performed, as described below: Group 1 (G1), traditional conical implants with surface treatment; group 2 (G2), traditional conical implants without surface treatment (machined surface); group 3 (G3), new conical implant design with surface treatment; group 4 (G4), new conical implant design without surface treatment. The implants were placed in the two tibias (n = 2 implants per tibia) of twenty New Zealand rabbits determined by randomization. The animals were euthanized after 15 days (Time 1) and 30 days (Time 2). The parameters evaluated were the implant stability quotient (ISQ), removal torque values (RTv), and histomorphometric evaluation to determine the bone to implant contact (%BIC) and bone area fraction occupancy (BAFO%). The results showed that the implants with the macrogeometry modified with healing chambers in the threads produced a significant enhancement in the osseointegration, accelerating this process. The statistical analyses of ISQ and RTv showed a significative statistical difference between the groups in both time periods of evaluation (p ≤ 0.0001). Moreover, an important increase in the histological parameters were found for groups G3 and G4, with significant statistical differences to the BIC% (in the Time 1 p = 0.0406 and in the Time 2 p < 0.0001) and the BAFO% ((in the Time 1 p = 0.0002 and in the Time 2 p = 0.0045). In conclusion, the result data showed that the implants with the new macrogeometry, presenting the healing chambers in the threads, produced a significant enhancement in the osseointegration, accelerating the process. Full article
(This article belongs to the Special Issue Current Trends in Biomaterial Scaffolds)
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<p>Schematic image of the space created after drilling to generate the healing chamber inside of the threads to facilitate the osseointegration.</p> Full article ">Figure 2
<p>Representative image of the implants and thread closed: (<b>a</b>) Traditional conical implant macrogeometry and (<b>b</b>) new conical implant macrogeometry.</p> Full article ">Figure 3
<p>Representative SEM images of the two surface models used in both implant macrogeometry: (<b>a</b>) Without treatment (machined surface) and (<b>b</b>) with surface treatment.</p> Full article ">Figure 3 Cont.
<p>Representative SEM images of the two surface models used in both implant macrogeometry: (<b>a</b>) Without treatment (machined surface) and (<b>b</b>) with surface treatment.</p> Full article ">Figure 4
<p>Representative schematic image of the drill sequence used for the osteotomy in all groups.</p> Full article ">Figure 5
<p>Representative image of both tibias after the soft tissue was retrieved and removed.</p> Full article ">Figure 6
<p>Implant stability measurement in two directions: (<b>a</b>) Proximo-distal and (<b>b</b>) in antero-posterior.</p> Full article ">Figure 7
<p>Image of the torque machine used for the torque removal measurements.</p> Full article ">Figure 8
<p>Line graph showing the ISQ evolution on the different times in each group. Time 1 = immediately at the installation; Time 2 = 15 days after the installation; Time 3 = 30 days after the installation.</p> Full article ">Figure 9
<p>Bar graph showing the RTv values on the two times in each group.</p> Full article ">Figure 10
<p>Representative images of the groups 15 days after the implantations. (<b>a</b>) G1 group, (<b>b</b>) G2 group, (<b>c</b>) G3 group, (<b>d</b>) G4 group. Images obtained by light microscopy with magnification of 10×.</p> Full article ">Figure 11
<p>Representative images of the groups 30 days after the implantations. (<b>a</b>) G1 group, (<b>b</b>) G2 group, (<b>c</b>) G3 group, (<b>d</b>) G4 group. Images obtained by light microscopy with magnification of 10×.</p> Full article ">Figure 12
<p>Bar graph of the BIC% mean and standard deviation in the two times proposed.</p> Full article ">Figure 13
<p>Bar graph of the BAFO% mean and standard deviation in the two times proposed.</p> Full article ">Figure 14
<p>Schematic image to show the bone compression during the implant installation (red arrows) and decompression (green arrows) on the healing chambers. (<b>a</b>) Conventional threads design and (<b>b</b>) new threads design with healing chambers.</p> Full article ">
22 pages, 19723 KiB  
Article
Seismic Vulnerability Assessment of Hybrid Mold Transformer Based on Dynamic Analyses
by Ngoc Hieu Dinh, Joo-Young Kim, Seung-Jae Lee and Kyoung-Kyu Choi
Appl. Sci. 2019, 9(15), 3180; https://doi.org/10.3390/app9153180 - 5 Aug 2019
Cited by 8 | Viewed by 4848
Abstract
In the present study, the seismic vulnerability of a hybrid mold transformer was investigated using a dynamic analytical approach incorporating the experimental results of shaking table tests. The analytical model consisted of linear springs and plastic beam elements, and it has six degrees [...] Read more.
In the present study, the seismic vulnerability of a hybrid mold transformer was investigated using a dynamic analytical approach incorporating the experimental results of shaking table tests. The analytical model consisted of linear springs and plastic beam elements, and it has six degrees of freedom simulating the hybrid mold transformer. The dynamic characteristics of the analytical model were determined based on the shaking table tests. The reliability of the analytical model was verified by comparing the test results and analytical results. In order to assess the seismic vulnerability, three critical damage states observed during the shaking table tests were investigated by incorporating the three performance levels specified in ASCE 41-17. Comprehensive dynamic analyses were performed with a set of twenty earthquakes in consideration of the variation of the uncertain parameters (such as the effective stiffness and coil mass) of the mold transformer. Based on the analytical results, fragility curves were established to predict the specified exceedance probability of the mold transformer according to the performance levels. Full article
(This article belongs to the Special Issue Evaluation and Mitigation of Seismic Risk for Existing Buildings, Structures, and Infrastructures)
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<p>Configurations and details of prototype hybrid mold transformer.</p> Full article ">Figure 2
<p>Details of components in analytical model.</p> Full article ">Figure 3
<p>Complete analytical model used in analysis program.</p> Full article ">Figure 4
<p>Input ground motion time histories used in dynamic analyses.</p> Full article ">Figure 5
<p>Comparison of acceleration time history responses between analytical and experimental results for AC156_25.</p> Full article ">Figure 6
<p>Comparison of acceleration time history responses between analytical and experimental results for AC156_50.</p> Full article ">Figure 7
<p>Comparison of acceleration time history responses between analytical and experimental results for AC156_100.</p> Full article ">Figure 8
<p>Comparison of analytical and experimental results after Fourier-transform (FT) analyses.</p> Full article ">Figure 9
<p>Comparison of displacement–time history responses in Y-direction between analytical and experimental results.</p> Full article ">Figure 10
<p>Comparison of maximum displacement of the mold transformer between analytical and experimental results.</p> Full article ">Figure 11
<p>Flowchart of seismic vulnerability assessment process.</p> Full article ">Figure 12
<p>Response spectrum of selected ground motions.</p> Full article ">Figure 13
<p>Magnitude versus closet ruptured distance of selected ground motions.</p> Full article ">Figure 14
<p>Magnitude versus peak ground acceleration (PGA) of selected ground motions.</p> Full article ">Figure 15
<p>Critical damage states observed during the shaking table tests.</p> Full article ">Figure 16
<p>Correlation between damage states and performance levels of the mold transformer.</p> Full article ">Figure 17
<p>Variation of critical dynamic responses according to PGA obtained from analytical results.</p> Full article ">Figure 18
<p>Characteristics of Friuli_Italy-01 earthquake (Y and Z-directions).</p> Full article ">Figure 19
<p>Effect of coil mass variation on dynamic responses according to PGA.</p> Full article ">Figure 20
<p>Effect of variation of effective translational stiffness on dynamic responses according to PGA.</p> Full article ">Figure 21
<p>Effect of coil mass variation on fragility curves of the mold transformer.</p> Full article ">Figure 22
<p>Effect of variation of effective translational stiffness on fragility curves of the mold transformer.</p> Full article ">Figure 23
<p>Effect of variation of effective rotational stiffness on fragility curves of the mold transformer.</p> Full article ">Figure 24
<p>Fragility curves for different damage states of the mold transformer.</p> Full article ">Figure 25
<p>Differences in the probability of exceedance between analytical data and the fitted model of different damage states.</p> Full article ">
8 pages, 241 KiB  
Article
Essential Oil Compositions and Antifungal Activity of Sunflower (Helianthus) Species Growing in North Alabama
by Sims K. Lawson, Layla G. Sharp, Chelsea N. Powers, Robert L. McFeeters, Prabodh Satyal and William N. Setzer
Appl. Sci. 2019, 9(15), 3179; https://doi.org/10.3390/app9153179 - 5 Aug 2019
Cited by 16 | Viewed by 6050
Abstract
Helianthus species are North American members of the Asteraceae, several of which have been used as traditional medicines by Native Americans. The aerial parts of two cultivars of Helianthus annuus, “Chianti” and “Mammoth”, and wild-growing H. strumosus, were collected from locations [...] Read more.
Helianthus species are North American members of the Asteraceae, several of which have been used as traditional medicines by Native Americans. The aerial parts of two cultivars of Helianthus annuus, “Chianti” and “Mammoth”, and wild-growing H. strumosus, were collected from locations in north Alabama. The essential oils were obtained by hydrodistillation and analyzed by gas chromatography—mass spectrometry. The Helianthus essential oils were dominated by monoterpene hydrocarbons, in particular α-pinene (50.65%, 48.91%, and 58.65%, respectively), sabinene (6.81%, 17.01%, and 1.91%, respectively), β-pinene (5.79%, 3.27%, and 4.52%, respectively), and limonene (7.2%, 7.1%, and 3.8%, respectively). The essential oils were screened against three opportunistic pathogenic fungal species, Aspergillus niger, Candida albicans, and Cryptococcus neoformans. The most sensitive fungus was C. neoformans with minimum inhibitory concentration (MIC) values of 78, 156, and 78 μg/mL, respectively. Full article
(This article belongs to the Special Issue Biological Activity and Applications of Natural Compounds)
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18 pages, 711 KiB  
Article
On Sharing an FIB Table in Named Data Networking
by Ju Hyoung Mun and Hyesook Lim
Appl. Sci. 2019, 9(15), 3178; https://doi.org/10.3390/app9153178 - 5 Aug 2019
Cited by 9 | Viewed by 3327
Abstract
As a new networking paradigm, Named Data Networking (NDN) technology focuses on contents, and content names are used as identifiers for forwarding and routing, as opposed to IP addresses in the current Internet. NDN routers forward packets by looking up a Forwarding Information [...] Read more.
As a new networking paradigm, Named Data Networking (NDN) technology focuses on contents, and content names are used as identifiers for forwarding and routing, as opposed to IP addresses in the current Internet. NDN routers forward packets by looking up a Forwarding Information Base (FIB), each entry of which has a name prefix and output faces. An FIB should have the information to forward Interest packets for any contents. Hence, the size of an FIB would be excessively large in NDN routers, and the traffic for building an FIB would be significant. In order to reduce the traffic associated with building an FIB table and memory requirement for storing an FIB table, this paper proposes a new efficient method which combines the routing of network connectivity and the building of a forwarding engine using Bloom filters. We propose to share the summary of an FIB using a Bloom filter rather than to advertise each name prefix. The forwarding engine of the proposed scheme is a combination of Bloom filters, and hence the memory requirement of the forwarding can be much smaller than the regular FIB. Simulation results using ndnSIM under real network topologies show that the proposed method can achieve nearly the same performance as the conventional link state algorithm with 6–8% of the traffic for distributing the connectivity information and 5–9% of the memory consumption. Full article
(This article belongs to the Special Issue Intelligent Centralized and Distributed Secure Edge Computing for Internet of Things Applications)
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Full article ">Figure 1
<p>An example of two Bloom filter union, where the size of the Bloom filters, the number of hash indices, and the used hash functions are identical.</p> Full article ">Figure 2
<p>An example of the proposed scheme. The nodes connected to other networks, <math display="inline"><semantics> <msub> <mi>r</mi> <mn>3</mn> </msub> </semantics></math>, <math display="inline"><semantics> <msub> <mi>r</mi> <mn>6</mn> </msub> </semantics></math>, and <math display="inline"><semantics> <msub> <mi>r</mi> <mn>7</mn> </msub> </semantics></math>, only have the FIB table and the connectivity information is carried in S-BF.</p> Full article ">Figure 3
<p>An example of building an F-BF. A node has <span class="html-italic">n</span> F-BFs, where <span class="html-italic">n</span> is the number of faces, and the F-BF which dedicated for face <span class="html-italic">i</span> is denoted as F-BF[i]. Whenever a new S-BF arrives, the F-BF of the incoming face is updated by bitwise-ORing the incoming S-BF and the existing F-BF.</p> Full article ">Figure 4
<p>An example of F-BFs merging-to reduce the time for querying F-BF[i], where <math display="inline"><semantics> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> <mo>⋯</mo> <mi>n</mi> </mrow> </semantics></math>. F-BFs are merged into one functional Bloom filter [<a href="#B19-applsci-09-03178" class="html-bibr">19</a>,<a href="#B26-applsci-09-03178" class="html-bibr">26</a>].</p> Full article ">Figure 5
<p>Packet handling procedure [<a href="#B5-applsci-09-03178" class="html-bibr">5</a>], where the upper part illustrates the <span class="html-italic">Interest</span> packet handling procedure and the lower part describes the <span class="html-italic">Data</span> packet handling procedure.</p> Full article ">Figure 6
<p>The average number of hop count under the various sizes of Bloom filters. As the size of Bloom filters grows, the data retrieval is performed along the optimal path.</p> Full article ">Figure 7
<p>The number of <span class="html-italic">Interest</span> packets under the various sizes of Bloom filters. As the size of the Bloom filters gets larger, the number of multicasts decreases.</p> Full article ">Figure 7 Cont.
<p>The number of <span class="html-italic">Interest</span> packets under the various sizes of Bloom filters. As the size of the Bloom filters gets larger, the number of multicasts decreases.</p> Full article ">Figure 8
<p>Memory requirements based on Equation (<a href="#FD4-applsci-09-03178" class="html-disp-formula">4</a>) and (<a href="#FD5-applsci-09-03178" class="html-disp-formula">5</a>). As the size of the Bloom filter grows, the memory requirement for the Bloom filter naturally increases, but the number of auxiliary FIB entries decreases. In all topologies, the memory usages are minimal when the size of the Bloom filter is 2048 bits.</p> Full article ">Figure 9
<p>Comparison in average hop count. The proposed scheme can achieve the near optimal packet delivery in all four topologies.</p> Full article ">Figure 10
<p>Comparison in the normalized number of <span class="html-italic">Interest</span> packets. The proposed scheme uses only about 1% more <span class="html-italic">Interest</span> packets than the <span class="html-italic">shortest path</span>, while simple <span class="html-italic">flooding</span> consumes up to almost twice the number of <span class="html-italic">Interest</span> packets.</p> Full article ">Figure 11
<p>Comparison in memory consumption (<math display="inline"><semantics> <mrow> <mi>M</mi> <mi>e</mi> <msub> <mi>m</mi> <mn>2</mn> </msub> </mrow> </semantics></math>). The proposed work consumes only 5–9% of the memory consumed by the <span class="html-italic">shortest path</span>, of which routers have the complete knowledge of all name prefixes.</p> Full article ">Figure 12
<p>Comparison in traffic for routing (MB). The traffic used for the proposed work is much smaller than <span class="html-italic">shortest path</span>, which is about 6–8% of the traffic of the <span class="html-italic">shortest path</span>.</p> Full article ">
21 pages, 1942 KiB  
Article
Design of Interactions for Handheld Augmented Reality Devices Using Wearable Smart Textiles: Findings from a User Elicitation Study
by Vijayakumar Nanjappan, Rongkai Shi, Hai-Ning Liang, Haoru Xiao, Kim King-Tong Lau and Khalad Hasan
Appl. Sci. 2019, 9(15), 3177; https://doi.org/10.3390/app9153177 - 5 Aug 2019
Cited by 13 | Viewed by 5977
Abstract
Advanced developments in handheld devices’ interactive 3D graphics capabilities, processing power, and cloud computing have provided great potential for handheld augmented reality (HAR) applications, which allow users to access digital information anytime, anywhere. Nevertheless, existing interaction methods are still confined to the touch [...] Read more.
Advanced developments in handheld devices’ interactive 3D graphics capabilities, processing power, and cloud computing have provided great potential for handheld augmented reality (HAR) applications, which allow users to access digital information anytime, anywhere. Nevertheless, existing interaction methods are still confined to the touch display, device camera, and built-in sensors of these handheld devices, which suffer from obtrusive interactions with AR content. Wearable fabric-based interfaces promote subtle, natural, and eyes-free interactions which are needed when performing interactions in dynamic environments. Prior studies explored the possibilities of using fabric-based wearable interfaces for head-mounted AR display (HMD) devices. The interface metaphors of HMD AR devices are inadequate for handheld AR devices as a typical HAR application require users to use only one hand to perform interactions. In this paper, we aim to investigate the use of a fabric-based wearable device as an alternative interface option for performing interactions with HAR applications. We elicited user-preferred gestures which are socially acceptable and comfortable to use for HAR devices. We also derived an interaction vocabulary of the wrist and thumb-to-index touch gestures, and present broader design guidelines for fabric-based wearable interfaces for handheld augmented reality applications. Full article
(This article belongs to the Special Issue Augmented Reality: Current Trends, Challenges and Prospects)
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<p>(<b>a</b>) Fabric-based prototype used in our study for righthanded participants. Three soft foam buttons (two on the sides of the index finger on proximal and middle phalanges, and one on the palmar side of the index proximal phalange) were glued to a fingerless hand glove design. (<b>b</b>) Illustrates the finger joints on the index finger. (<b>c</b>–<b>e</b>) Sample gestures supported by in-house developed prototype: (<b>c</b>) wrist only; (<b>d</b>) touch only; and (<b>e</b>) touch and wrist.</p> Full article ">Figure 2
<p>A participant is performing a gesture while wearing the fabric-based prototype on the right hand and holding the handheld augmented reality (HAR) device on the left hand. Two cameras were used the capture the entire process.</p> Full article ">Figure 3
<p>Variety of gestures performed by our participants using one hand (right hand) while holding the device on the other hand: (<b>a</b>) wrist gestures and (<b>b</b>) thumb-to-index touch gestures.</p> Full article ">Figure 4
<p>Frequency distribution of complexity of gestures in each category. Simple gestures were highly preferred for discrete tasks.</p> Full article ">Figure 5
<p>Observed percentages of wrist and touch gestures for HAR interactions. Button one was highly preferred for both simple and complex gestures. Simple wrist gestures were preferred for continuous tasks and simple touch gestures for discrete tasks (shows a clear influence of prior experience).</p> Full article ">Figure 6
<p>Frequency distribution of action types in the preferred gesture set for 27 tasks. Tap action was highly preferred for the camera tasks.</p> Full article ">Figure 7
<p>User-preferred gesture set for HAR interactions. Simple touch gestures: (<b>a</b>) tap button one, (<b>b</b>) tap button two, (<b>c</b>) tap button three, (<b>d</b>) hold button two, (<b>e</b>) hold button three; Simple wrist gestures: (<b>f</b>) downward flexion, (<b>g</b>) upward extension, (<b>h</b>) leftward flexion, (<b>i</b>) rightward extension; Complex gestures: (<b>j</b>) hold button one and downward flexion, (<b>k</b>) hold button two and downward flexion, (<b>l</b>) hold button two and leftward flexion, (<b>m</b>) hold button two and rightward extension.</p> Full article ">
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