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Technologies
Volume 8
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Technologies, Volume 8, Issue 2 (June 2020) – 18 articles

Cover Story (view full-size image): We fabricated four microhole arrays with different arrangements, quantified by the parameter of “eccentricity” and evaluated the evaporation mode of the water droplets on these substrates. The results suggest that the evaporation mode is altered by changing the eccentricity of the micropatterned surfaces. Specifically, over 75% of the lifetime of droplets on the microhole arrays with non-zero eccentricity is in the constant contact line (CCL) mode while this value is around 40% for the droplets surrounded by those with zero eccentricity. These results can be partially explained by the quantification of contact angle hysteresis (CAH). Our findings play a significant role in any technology platform that contains micropatterned surfaces, where controlling the evaporation mode is desirable. View this paper
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35 pages, 27448 KiB  
Review
Unsupervised Domain Adaptation in Semantic Segmentation: A Review
by Marco Toldo, Andrea Maracani, Umberto Michieli and Pietro Zanuttigh
Technologies 2020, 8(2), 35; https://doi.org/10.3390/technologies8020035 - 21 Jun 2020
Cited by 121 | Viewed by 16021
Abstract
The aim of this paper is to give an overview of the recent advancements in the Unsupervised Domain Adaptation (UDA) of deep networks for semantic segmentation. This task is attracting a wide interest since semantic segmentation models require a huge amount of labeled [...] Read more.
The aim of this paper is to give an overview of the recent advancements in the Unsupervised Domain Adaptation (UDA) of deep networks for semantic segmentation. This task is attracting a wide interest since semantic segmentation models require a huge amount of labeled data and the lack of data fitting specific requirements is the main limitation in the deployment of these techniques. This field has been recently explored and has rapidly grown with a large number of ad-hoc approaches. This motivates us to build a comprehensive overview of the proposed methodologies and to provide a clear categorization. In this paper, we start by introducing the problem, its formulation and the various scenarios that can be considered. Then, we introduce the different levels at which adaptation strategies may be applied: namely, at the input (image) level, at the internal features representation and at the output level. Furthermore, we present a detailed overview of the literature in the field, dividing previous methods based on the following (non mutually exclusive) categories: adversarial learning, generative-based, analysis of the classifier discrepancies, self-teaching, entropy minimization, curriculum learning and multi-task learning. Novel research directions are also briefly introduced to give a hint of interesting open problems in the field. Finally, a comparison of the performance of the various methods in the widely used autonomous driving scenario is presented. Full article
(This article belongs to the Section Information and Communication Technologies)
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20 pages, 24478 KiB  
Article
Influence of WC-Based Pin Tool Profile on Microstructure and Mechanical Properties of AA1100 FSW Welds
by Abbas Tamadon, Arvand Baghestani and Mohammad Ebrahim Bajgholi
Technologies 2020, 8(2), 34; https://doi.org/10.3390/technologies8020034 - 15 Jun 2020
Cited by 24 | Viewed by 4811 | Correction
Abstract
The effect of various tungsten carbide (WC) pin tools and operating parameters on the material structure and properties of an AA1100 friction stir welding (FSW) weld were evaluated. Three different pin shapes were employed (conical, square and threaded). For each tool shape, welds [...] Read more.
The effect of various tungsten carbide (WC) pin tools and operating parameters on the material structure and properties of an AA1100 friction stir welding (FSW) weld were evaluated. Three different pin shapes were employed (conical, square and threaded). For each tool shape, welds were generated for a set of tool (revolutions per minute, RPM) (710, 1120 and 1400) and advancing speeds (150, 250 and 400 mm/min). Weld samples were tested for mechanical strength by tensile testing. Morphology was examined using optical microscopy, and weld composition with scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). No weld contamination from the tools was observed. However, a number of structural defects, inherent to the FSW process, were observed (including tunnel voids, kissing bonds and swirling lines). These defects, associated with the stirring action, could not be eliminated. The results show how the operating parameters may be optimized to produce stronger welds. Full article
(This article belongs to the Special Issue Reviews and Advances in Materials Processing)
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15 pages, 4125 KiB  
Article
Investigation of Methods to Extract Fetal Electrocardiogram from the Mother’s Abdominal Signal in Practical Scenarios
by Sadaf Sarafan, Tai Le, Amir Mohammad Naderi, Quoc-Dinh Nguyen, Brandon Tiang-Yu Kuo, Tadesse Ghirmai, Huy-Dung Han, Michael P. H. Lau and Hung Cao
Technologies 2020, 8(2), 33; https://doi.org/10.3390/technologies8020033 - 5 Jun 2020
Cited by 24 | Viewed by 6348
Abstract
Monitoring of fetal electrocardiogram (fECG) would provide useful information about fetal wellbeing as well as any abnormal development during pregnancy. Recent advances in flexible electronics and wearable technologies have enabled compact devices to acquire personal physiological signals in the home setting, including those [...] Read more.
Monitoring of fetal electrocardiogram (fECG) would provide useful information about fetal wellbeing as well as any abnormal development during pregnancy. Recent advances in flexible electronics and wearable technologies have enabled compact devices to acquire personal physiological signals in the home setting, including those of expectant mothers. However, the high noise level in the daily life renders long-entrenched challenges to extract fECG from the combined fetal/maternal ECG signal recorded in the abdominal area of the mother. Thus, an efficient fECG extraction scheme is a dire need. In this work, we intensively explored various extraction algorithms, including template subtraction (TS), independent component analysis (ICA), and extended Kalman filter (EKF) using the data from the PhysioNet 2013 Challenge. Furthermore, the modified data with Gaussian and motion noise added, mimicking a practical scenario, were utilized to examine the performance of algorithms. Finally, we combined different algorithms together, yielding promising results, with the best performance in the F1 score of 92.61% achieved by an algorithm combining ICA and TS. With the data modified by adding different types of noise, the combination of ICA–TS–ICA showed the highest F1 score of 85.4%. It should be noted that these combined approaches required higher computational complexity, including execution time and allocated memory compared with other methods. Owing to comprehensive examination through various evaluation metrics in different extraction algorithms, this study provides insights into the implementation and operation of state-of-the-art fetal and maternal monitoring systems in the era of mobile health. Full article
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26 pages, 3694 KiB  
Review
Electrical Discharge Machining Non-Conductive Ceramics: Combination of Materials
by Marina A. Volosova, Anna A. Okunkova, Sergey V. Fedorov, Khaled Hamdy and Mariya A. Mikhailova
Technologies 2020, 8(2), 32; https://doi.org/10.3390/technologies8020032 - 28 May 2020
Cited by 31 | Viewed by 7174
Abstract
One of the promising processing methods for non-conductive structural and functional ceramics based on ZrO2, Al2O3, and Si3N4 systems is electrical discharge machining with the assistance of an auxiliary electrode that can be presented [...] Read more.
One of the promising processing methods for non-conductive structural and functional ceramics based on ZrO2, Al2O3, and Si3N4 systems is electrical discharge machining with the assistance of an auxiliary electrode that can be presented in the form of conductive films with a thickness up to 4–10 µm or nanoparticles - granules, tubes, platelets, multidimensional particles added in the working zone as a free poured powder the proper concentration of which can be provided by ultrasound emission or by dielectric flows or as conductive additives in the structure of nanocomposites. However, the described experimental approaches did not reach the production market and industry. It is related mostly to the chaotic development of the knowledge and non-systematized data in the field when researchers often cannot ground their choice of the material for auxiliary electrodes, assisting powders, or nano additives or they cannot explain the nature of processes that were observed in the working tank during experiments when their results are not correlated to the measured specific electrical conductivity of the electrodes, particles, ceramic workpieces or nanocomposites but depends on something else. The proposed review includes data on the main electrophysical and chemical properties of the components in the presence of heat when the temperature in the interelectrode gap reaches 10,000 °C, and the systematization of data on ceramic pressing methods, including spark plasma sintering, the chemical reactions that occur in the interelectrode gap during sublimation of primary (brass and copper) and auxiliary electrodes made of transition metals Ti, Cr, Co, and carbon, auxiliary electrodes made of metals with low melting point Zn, Ag, Au, Al, assisting powder of oxide ceramics TiO2, CeO2, SnO2, ITO, conductive additives Cu, W, TiC, WC, and components of Al2O3 and Zr2O workpieces in interaction with the dielectric fluid - water and oil/kerosene medium. Full article
(This article belongs to the Special Issue Reviews and Advances in Materials Processing)
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23 pages, 1936 KiB  
Review
The Influence of Smart Manufacturing towards Energy Conservation: A Review
by Shane Terry, Hao Lu, Ismail Fidan, Yunbo Zhang, Khalid Tantawi, Terry Guo and Bahram Asiabanpour
Technologies 2020, 8(2), 31; https://doi.org/10.3390/technologies8020031 - 25 May 2020
Cited by 39 | Viewed by 9028
Abstract
Today, the current trends of manufacturing are towards the adaptation and implementation of smart manufacturing, which is a new initiative to turn the traditional factories into profitable innovation facilities. However, the concept and technologies are still in a state of infancy, since many [...] Read more.
Today, the current trends of manufacturing are towards the adaptation and implementation of smart manufacturing, which is a new initiative to turn the traditional factories into profitable innovation facilities. However, the concept and technologies are still in a state of infancy, since many manufacturers around the world are not fully knowledgeable about the benefits of smart manufacturing compared to their current practices. This article reviews several aspects of smart manufacturing and introduces its advantages in terms of energy-saving and production efficiency. This article also points out that some areas need further research so that smart manufacturing can be shaped better. Full article
(This article belongs to the Section Innovations in Materials Processing)
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18 pages, 2379 KiB  
Article
Thermal and Visual Imaging to Assist with Juvenile Idiopathic Arthritis Examination of the Knees
by Harriet Nwaizu, Reza Saatchi, Daniel Philip Hawley and Oliver Ward
Technologies 2020, 8(2), 30; https://doi.org/10.3390/technologies8020030 - 24 May 2020
Cited by 6 | Viewed by 4557
Abstract
Juvenile idiopathic arthritis (JIA) causes inflammation of the joints, and it is frequently associated with their pain and stiffness. Its timely diagnosis is important to avoid its progressive damage to the bones and cartilage. Increases in the joint’s temperature and redness could be [...] Read more.
Juvenile idiopathic arthritis (JIA) causes inflammation of the joints, and it is frequently associated with their pain and stiffness. Its timely diagnosis is important to avoid its progressive damage to the bones and cartilage. Increases in the joint’s temperature and redness could be indicators of active JIA, hence their accurate quantification could assist with diagnosis. Thermal and visual images of the knees in 20 JIA participants (age: mean = 11.2 years, standard deviation = 2.3 years) were studied. The median temperature of knees with active inflammation was 3.198% higher than that of inactive knees. This difference, examined by a Wilcoxon signed-rank test, was statistically significant (p = 0.0078). In six out of the eight participants who had one active inflamed knee, thermal imaging identified the corresponding knee as warmer. In 16 out of 20 participants, the knee identified as warmer by thermal imaging was also identified as having a greater colour change by visual imaging as compared to their respective reference regions. The devised methods could accurately quantify the colour and temperature of the knees. It was concluded that thermal and visual imaging methods can be valuable in examining JIA. Further studies involving a larger number of participants and more detailed explorations would be needed prior to clinical application. Full article
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10 pages, 2229 KiB  
Article
Engineering Micropatterned Surfaces for Controlling the Evaporation Process of Sessile Droplets
by Navid Kashaninejad, Nam-Trung Nguyen and Weng Kong Chan
Technologies 2020, 8(2), 29; https://doi.org/10.3390/technologies8020029 - 19 May 2020
Cited by 4 | Viewed by 3869
Abstract
Controlling the evaporation process of a droplet is of the utmost importance for a number of technologies. Also, along with the advances of microfabrication, micropatterned surfaces have emerged as an important technology platform to tune the wettability and other surface properties of various [...] Read more.
Controlling the evaporation process of a droplet is of the utmost importance for a number of technologies. Also, along with the advances of microfabrication, micropatterned surfaces have emerged as an important technology platform to tune the wettability and other surface properties of various fundamental and applied applications. Among the geometrical parameters of these micropatterns, it is of great interest to investigate whether the arrangement of the patterns would affect the evaporation process of a sessile liquid droplet. To address this question, we fabricated four microhole arrays with different arrangements, quantified by the parameter of “eccentricity”. The results suggested that, compared to smooth substrates, the evaporation mode was not only affected by engineering the microhole arrays, but also by the eccentricity of these micropatterns. The values of contact angle hysteresis (CAH) were used to quantify and test this hypothesis. The CAH could partially explain the different evaporation modes observed on the microhole arrays with zero and non-zero values of eccentricity. That is, on microhole arrays with zero eccentricity, CAH of water droplets was comparatively low (less than 20 ° ). Consistently, during the evaporation, around 60% of the life span of the droplet was in the mixed evaporation mode. Increasing the eccentricity of the microhole arrays increases the values of CAH to above 20 ° . Unlike the increasing trend of CAH, the evaporation modes of sessile droplets on the microhole array with non-zero values of eccentricity were almost similar. Over 75% of the life span of droplets on these surfaces was in constant contact line (CCL) mode. Our findings play a significant role in any technology platform containing micropatterned surfaces, where controlling the evaporation mode is desirable. Full article
(This article belongs to the Section Innovations in Materials Processing)
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17 pages, 13338 KiB  
Article
A Zynq-Based Robotic System for Treatment of Contagious Diseases in Hospital Isolated Environment
by Christos Paparizos, Nikolaos Tsafas and Michael Birbas
Technologies 2020, 8(2), 28; https://doi.org/10.3390/technologies8020028 - 15 May 2020
Cited by 4 | Viewed by 4311
Abstract
The rapid evolution of smart assisted living operations in combination with the blooming of commercial robots calls for the use of robotic based systems. Specifically, certain circumstances such as the handling of critical, contagious virus outbreaks like the recent novel Coronavirus epidemic can [...] Read more.
The rapid evolution of smart assisted living operations in combination with the blooming of commercial robots calls for the use of robotic based systems. Specifically, certain circumstances such as the handling of critical, contagious virus outbreaks like the recent novel Coronavirus epidemic can be benefited by an assisting mobile robot system controlled remotely, complementing measures like the isolation of patients from medical stuff. Within this context, the robotic-based solution to be employed needs to be easy to deploy, able to manufacture with low cost, and able to operate with ease by non-trained personnel. Also, to address the needs of existing hospitals, traditional or smart ones, as well as the temporary risk management facilities in, for example, quarantined cities, ease of integration in terms of size and infrastructure requirements is a must. In this work, the design and implementation of a robotic chassis bearing an arm manipulator is presented, addressing all these needs efficiently. Special attention has been given to the ease of teleoperation with minimal need for equipment and expertise, utilizing a Leap Motion virtual reality sensor which outweighs Microsoft’s Kinect capabilities. Furthermore, a reconfigurable hardware and software integrated system has been used to control the communication, algorithm processing and motion control utilizing a Xilinx Zynq system on chip (SoC). Full article
(This article belongs to the Special Issue MOCAST 2019: Modern Circuits and Systems Technologies on Electronics)
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14 pages, 782 KiB  
Article
Comparison of Time Delay Estimation Methods Used for Fast Pipeline Leak Localization in High-Noise Environment
by Georgios-Panagiotis Kousiopoulos, Georgios-Napoleon Papastavrou, Dimitrios Kampelopoulos, Nikolaos Karagiorgos and Spiros Nikolaidis
Technologies 2020, 8(2), 27; https://doi.org/10.3390/technologies8020027 - 14 May 2020
Cited by 14 | Viewed by 4159
Abstract
Pipeline networks are one of the most efficient and extensively used means for transporting fluid products. However, they suffer from a serious problem that threatens their normal and secure operation, which is the occurrence of leaks. In this article, an acoustic technique for [...] Read more.
Pipeline networks are one of the most efficient and extensively used means for transporting fluid products. However, they suffer from a serious problem that threatens their normal and secure operation, which is the occurrence of leaks. In this article, an acoustic technique for the localization of leaks in pipelines placed in the high-noise environment of an oil refinery is described. This technique is based on the estimation of the time delay between the moments at which an acoustic signal produced by a leak reaches two sensors mounted on the external surface of the pipeline at a certain distance between them. For this reason, three different time delay estimation methods, based on the cross-correlation procedure, are studied in this article. These methods are tested for their accuracy in the estimation of the leak position, as well as for their ability to work with measurements of short duration and the results are compared. This is important because the acquisition duration affects directly the response time of the leak localization system, which is a crucial parameter for the targeted applications. Finally, an algorithm for fast and accurate identification of the leak point is proposed. Full article
(This article belongs to the Special Issue MOCAST 2019: Modern Circuits and Systems Technologies on Electronics)
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16 pages, 234 KiB  
Article
Psychosocial Implications of Large-Scale Implementations of Solar Power in Malaysia
by Ai Ni Teoh, Yun Ii Go and Tze Chuen Yap
Technologies 2020, 8(2), 26; https://doi.org/10.3390/technologies8020026 - 14 May 2020
Cited by 2 | Viewed by 3865
Abstract
The present study aimed to investigate the psychosocial impacts of large-scale solar (LSS) power projects. There were 225 participants (n = 109 women, n = 3 did not indicate gender) participated in our study by completing a series of questionnaires. We found that [...] Read more.
The present study aimed to investigate the psychosocial impacts of large-scale solar (LSS) power projects. There were 225 participants (n = 109 women, n = 3 did not indicate gender) participated in our study by completing a series of questionnaires. We found that participants who lived farther from the LSS power project location and those who viewed the project as being impactful were optimistic about the benefits LSS power projects could bring. Our participants also demonstrated support for renewable energy development in Malaysia. These findings may provide important implications for the implementation and execution of LSS power projects and policies. Full article
(This article belongs to the Section Environmental Technology)
15 pages, 1077 KiB  
Article
Gate Sizing Methodology with a Novel Accurate Metric to Improve Circuit Timing Performance under Process Variations
by Zahira Perez-Rivera, Esteban Tlelo-Cuautle and Victor Champac
Technologies 2020, 8(2), 25; https://doi.org/10.3390/technologies8020025 - 13 May 2020
Cited by 4 | Viewed by 3784
Abstract
The impact of process variations on circuit performance has become more critical with the technological scaling, and the increasing level of integration of integrated circuits. The degradation of the performance of the circuit means economic losses. In this paper, we propose an efficient [...] Read more.
The impact of process variations on circuit performance has become more critical with the technological scaling, and the increasing level of integration of integrated circuits. The degradation of the performance of the circuit means economic losses. In this paper, we propose an efficient statistical gate-sizing methodology for improving circuit speed in the presence of independent intra-die process variations. A path selection method, a heuristic, two coarse selection metrics, and one fine selection metric are part of the new proposed methodology. The fine metric includes essential concepts like the derivative of the standard deviation of delay, a path segment analysis, the criticality, the slack-time, and area. The proposed new methodology is applied to ISCAS Benchmark circuits. The average percentage of optimization in the delay is 12%, the average percentage of optimization in the delay standard deviation is 27.8%, the average percentage in the area increase is less than 5%, and computing time is up to ten times less than using analytical methods like Lagrange Multipliers. Full article
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11 pages, 1487 KiB  
Article
Modeling Pneumonia-Induced Bloodstream Infection Using Graph Theory to Estimate Hospital Mortality
by Dimitrios Zikos and Maria Athanasopoulou
Technologies 2020, 8(2), 24; https://doi.org/10.3390/technologies8020024 - 13 May 2020
Viewed by 3603
Abstract
Hospital-acquired pneumonia (HAP) bloodstream infections comprise a major cause of crude hospital mortality. This is a cross-sectional study that used claims data from the Centers for Medicare and Medicaid Services (N = 565,875). The study objective is to represent the progression of [...] Read more.
Hospital-acquired pneumonia (HAP) bloodstream infections comprise a major cause of crude hospital mortality. This is a cross-sectional study that used claims data from the Centers for Medicare and Medicaid Services (N = 565,875). The study objective is to represent the progression of pneumonia-induced bloodstream infections using graph theory principles, where each path of the graph represents a different scenario of bloodstream-infection progression, and aims to further estimate the likelihood if hospital death for each path. To disseminate the results, the study makes available a prototype applet to navigate various paths of the graph interactively. Bayesian probabilities were calculated for each scenario, and multivariate logistic regression was conducted to estimate the adjusted OR for inpatient death after controlling for patient age, sex, and comorbidities. The mortality rate ranged from 4.99% for patients admitted with community pneumonia without bloodstream infection and reached 63.18% for cases admitted with bloodstream infection that progressed to hospital septicemia, sepsis, and septic shock. The prototype applet can be used to unfold bloodstream infection events and their associated risk for mortality and could be used in university curricula to assist educators in helping students understand the progression of pneumonia-induced bloodstream infections in a data-driven way. Full article
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14 pages, 2932 KiB  
Article
An Interactive Real-Time Cutting Technique for 3D Models in Mixed Reality
by Paolo Caligiana, Alfredo Liverani, Alessandro Ceruti, Gian Maria Santi, Giampiero Donnici and Francesco Osti
Technologies 2020, 8(2), 23; https://doi.org/10.3390/technologies8020023 - 12 May 2020
Cited by 15 | Viewed by 6223
Abstract
This work describes a Mixed Reality application useful to modify and cut virtual objects. A digital simulation of surgical operations is presented. Following this approach, surgeons can test all the designed solutions of the preoperative stage in a Mixed Reality environment. High precision [...] Read more.
This work describes a Mixed Reality application useful to modify and cut virtual objects. A digital simulation of surgical operations is presented. Following this approach, surgeons can test all the designed solutions of the preoperative stage in a Mixed Reality environment. High precision in surgery applications can be achieved thanks to the new methodology. The presented solution is hands free and does not need the use of a mouse or computer’s keyboard: it is based on HoloLens, Leap Motion device and Unity. A new cutting algorithm has been developed in order to handle multiple objects and speed up the cut with complex meshes and preserve geometry quality. A case study presents the cut of several bones in order to simulate surgeon’s operations. A reduction in cut time compared to the original method is noticed, together with a high flexibility of the tool and a good fidelity of the geometry. Moreover, all the object fragments generated from the algorithm are available for manipulation and new cuts. Full article
(This article belongs to the Special Issue Computer Vision and Image Processing Technologies)
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16 pages, 2146 KiB  
Article
Comparison of Different Hydrotalcite Solid Adsorbents on Adsorptive Desulfurization of Liquid Fuel Oil
by Mozammel Mazumder, Rajib Das, Md Symon Jahan Sajib, Andrew Jewel Gomes, Mohammad Islam, Thinesh Selvaratnam and Ashiqur Rahman
Technologies 2020, 8(2), 22; https://doi.org/10.3390/technologies8020022 - 27 Apr 2020
Cited by 3 | Viewed by 4606
Abstract
With increasingly stringent environmental regulations, desulfurization for gasoline oil production has become an important issue. Nowadays, desulfurization technologies have become an integral part of environmental catalysis studies. It is also important for processing of fuel for fuel-cells, which has a strict requirement for [...] Read more.
With increasingly stringent environmental regulations, desulfurization for gasoline oil production has become an important issue. Nowadays, desulfurization technologies have become an integral part of environmental catalysis studies. It is also important for processing of fuel for fuel-cells, which has a strict requirement for sulfur content for internal combustion engines. In this study, we focused on the preparation and characterization of magnesium hydroxide/aluminum supported NiO, ZnO, ZrO2, NiO-ZnO, NiO-ZrO2, adsorbents for the adsorptive desulfurization of liquid fuels. These hydrotalcite adsorbents were prepared by co-precipitation method and used for adsorption of thiophene (in n-pentane, as model fuel) and dibenzothiophene at ambient temperature and pressure. The physicochemical behaviors of the fresh adsorbents such as structure, composition, and bonding modes were determined using X-ray diffraction (XRD), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), energy dispersive X-Ray analysis (EDAX), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). The sulfur concentration in the mixture (thiophene and n-pentane) was measured by UV-Vis spectrophotometry. The percentages of thiophene removal and the adsorption capacity (mg of sulfur per g of adsorbent) of the five adsorbents were compared. The adsorption performance confirmed that NiO-ZrO2 and NiO-ZnO adsorbents are more efficient in removing thiophene/dibenzothiophene than that of three other adsorbents. The qualitative studies using XPS confirmed the efficient adsorption nature of modified hydrotalcite adsorbents on dibenzothiophene. Full article
(This article belongs to the Special Issue Reviews and Advances in Materials Processing)
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13 pages, 3765 KiB  
Article
Use Ultra-Wideband Discone Rectenna for Broadband RF Energy Harvesting Applications
by Manolis G. Tampouratzis, Demosthenes Vouyioukas, Dimitrios Stratakis and Traianos Yioultsis
Technologies 2020, 8(2), 21; https://doi.org/10.3390/technologies8020021 - 23 Apr 2020
Cited by 16 | Viewed by 6871
Abstract
In this study, a broadband Radio Frequency (RF) energy harvester implementation is presented. The system uses a broadband discone antenna, which can operate efficiently in a broad frequency spectrum, including LTE, DCS 1800 and UMTS 2100 cellular frequency bands. The system is able [...] Read more.
In this study, a broadband Radio Frequency (RF) energy harvester implementation is presented. The system uses a broadband discone antenna, which can operate efficiently in a broad frequency spectrum, including LTE, DCS 1800 and UMTS 2100 cellular frequency bands. The system is able to harvest energy from various electromagnetic field sources, thus has the potential to efficiently charge a storage energy element in a short time. The prototype broadband RF energy harvester was tested in the laboratory and also in a typical urban environment. Full article
(This article belongs to the Special Issue MOCAST 2019: Modern Circuits and Systems Technologies on Communications)
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13 pages, 6117 KiB  
Article
Demonstration of the Effect of Centre of Mass Height on Postural Sway Using Accelerometry for Balance Analysis
by Oseikhuemen Osemekhian Davis Ojie, Reza Saatchi and Mahdieh Saatchi
Technologies 2020, 8(2), 20; https://doi.org/10.3390/technologies8020020 - 22 Apr 2020
Cited by 4 | Viewed by 5229
Abstract
The effect of center of mass (COM) height on stand-still postural sway analysis was studied. For this purpose, a measurement apparatus was set up that included an accelerometry device attached to a rod: three plumb lines, positioned at 50, 75 and 100 cm [...] Read more.
The effect of center of mass (COM) height on stand-still postural sway analysis was studied. For this purpose, a measurement apparatus was set up that included an accelerometry device attached to a rod: three plumb lines, positioned at 50, 75 and 100 cm to an end of the rod, each supported a plumb bob. Using a vice mechanism, the rod was inclined from vertical (0 degree inclination) in steps of 5 degrees to 90 degrees. For each inclination, the corresponding inclination angle was manually measured by a protractor and the positions of the three plumb bobs on the ground surface were also manually measured using a tape measure. Algebraic operations were used to calculate the inclination angle and the associated displacements of the plumb bobs on the ground surface from the accelerometry data. For each inclination angle, the manual and accelerometry calculated ground displacement were close. The height of COM, where the measurement was taken, affected the projected displacement on the ground surface. The COM height had a nonlinear double-effect relationship with sway as it can affect both the angle and projected sway. Normalization of the COM height was used to reduce this effect for comparison purposes. Full article
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23 pages, 7486 KiB  
Article
Recognition of Holoscopic 3D Video Hand Gesture Using Convolutional Neural Networks
by Norah Alnaim, Maysam Abbod and Rafiq Swash
Technologies 2020, 8(2), 19; https://doi.org/10.3390/technologies8020019 - 15 Apr 2020
Cited by 6 | Viewed by 9471
Abstract
The convolutional neural network (CNN) algorithm is one of the efficient techniques to recognize hand gestures. In human–computer interaction, a human gesture is a non-verbal communication mode, as users communicate with a computer via input devices. In this article, 3D micro hand gesture [...] Read more.
The convolutional neural network (CNN) algorithm is one of the efficient techniques to recognize hand gestures. In human–computer interaction, a human gesture is a non-verbal communication mode, as users communicate with a computer via input devices. In this article, 3D micro hand gesture recognition disparity experiments are proposed using CNN. This study includes twelve 3D micro hand motions recorded for three different subjects. The system is validated by an experiment that is implemented on twenty different subjects of different ages. The results are analysed and evaluated based on execution time, training, testing, sensitivity, specificity, positive and negative predictive value, and likelihood. The CNN training results show an accuracy as high as 100%, which present superior performance in all factors. On the other hand, the validation results average about 99% accuracy. The CNN algorithm has proven to be the most accurate classification tool for micro gesture recognition. Full article
(This article belongs to the Special Issue Computer Vision and Image Processing Technologies)
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13 pages, 2774 KiB  
Article
Energy Conservation with Open Source Ad Blockers
by Joshua M. Pearce
Technologies 2020, 8(2), 18; https://doi.org/10.3390/technologies8020018 - 30 Mar 2020
Cited by 3 | Viewed by 56656
Abstract
Internet-related electricity consumption is rising rapidly as global Internet users spend more than 6.5 h per day online. Open source ad blockers have the potential to reduce the time and thus electricity spent using computers by eliminating ads during Internet browsing and video [...] Read more.
Internet-related electricity consumption is rising rapidly as global Internet users spend more than 6.5 h per day online. Open source ad blockers have the potential to reduce the time and thus electricity spent using computers by eliminating ads during Internet browsing and video streaming. In this study, three open source ad blockers are tested against a no-ad blocker control. Page load time is recorded for browsing a representative selection of the globally most-accessed websites, and the time spent watching ads on videos is quantified for both trending and non-trending content. The results show that page load time dropped 11% with AdBlock+, 22.2% with Privacy Badger, and 28.5% with uBlock Origin. Thus, uBlock Origin has the potential to save the average global Internet user more than 100 h annually. The energy conserved if everyone in the United States used the open source ad blocker would save over 36 Americans lives per year if it were to offset coal-fired electricity generated-based pollution. In the United States, if all Internet users enabled Privacy Badger on their computers, Americans would save more than $91 million annually. Globally, uBlock Origin could save consumers more than $1.8 billion/year. Open source ad blockers are a potentially effective technology for energy conservation. Full article
(This article belongs to the Section Information and Communication Technologies)
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