Editor's Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to authors, or important in this field. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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Article
Wear Resistance and Titanium Adhesion of Cathodic Arc Deposited Multi-Component Coatings for Carbide End Mills at the Trochoidal Milling of Titanium Alloy
Technologies 2020, 8(3), 38; https://doi.org/10.3390/technologies8030038 - 30 Jun 2020
Cited by 3 | Viewed by 2109
Abstract
The work was devoted to the study of the effectiveness of the application of multi-component coatings, TiN–Al/TiN, TiN–AlTiN/SiN, and CrTiN–AlTiN–AlTiCrN/SiN, obtained by cathodic arc deposition to increase the wear resistance of 6WH10F carbide end mills in trochoidal milling of titanium alloy. The surface [...] Read more.
The work was devoted to the study of the effectiveness of the application of multi-component coatings, TiN–Al/TiN, TiN–AlTiN/SiN, and CrTiN–AlTiN–AlTiCrN/SiN, obtained by cathodic arc deposition to increase the wear resistance of 6WH10F carbide end mills in trochoidal milling of titanium alloy. The surface morphology of the tool with coatings was studied using scanning electron microscopy, and surface roughness texture was estimated. Microhardness and elastic modulus of the coated carbide tool surface layer were determined by nanoindentation. The process of sticking titanium to the working surface of the tool and quantitative evaluation of end mill wear with multi-component coatings at the trochoidal strategy of milling titanium alloy was studied. The CrTiN–AlTiN–AlTiCrN/SiN coating showed the maximum value of the plasticity index at the level of 0.12. The maximum effect of reducing the wear rate was achieved when using a tool with a CrTiN –AlTiN–AlTiCrN/SiN coating when the operating time to failure of end mills was increased by 4.6 times compared to samples without coating, by 1.4 times compared with TiN–Al/TiN coating and 1.15 times compared with TiN–AlTiN/SiN coating. Full article
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Article
Evaluation of Epidemic-Based Information Dissemination in a Wireless Network Testbed
Technologies 2020, 8(3), 36; https://doi.org/10.3390/technologies8030036 - 28 Jun 2020
Viewed by 1827
Abstract
Information dissemination is an integral part of modern networking environments, such as Wireless Sensor Networks (WSNs). Probabilistic flooding, a common epidemic-based approach, is used as an efficient alternative to traditional blind flooding as it minimizes redundant transmissions and energy consumption. It shares some [...] Read more.
Information dissemination is an integral part of modern networking environments, such as Wireless Sensor Networks (WSNs). Probabilistic flooding, a common epidemic-based approach, is used as an efficient alternative to traditional blind flooding as it minimizes redundant transmissions and energy consumption. It shares some similarities with the Susceptible-Infected-Recovered (SIR) epidemic model, in the sense that the dissemination process and the epidemic thresholds, which achieve maximum coverage with the minimum required transmissions, have been found to be common in certain cases. In this paper, some of these similarities between probabilistic flooding and the SIR epidemic model are identified, particularly with respect to the epidemic thresholds. Both of these epidemic algorithms are experimentally evaluated on a university campus testbed, where a low-cost WSN, consisting of 25 nodes, is deployed. Both algorithm implementations are shown to be efficient at covering a large portion of the network’s nodes, with probabilistic flooding behaving largely in accordance with the considered epidemic thresholds. On the other hand, the implementation of the SIR epidemic model behaves quite unexpectedly, as the epidemic thresholds underestimate sufficient network coverage, a fact that can be attributed to implementation limitations. Full article
(This article belongs to the Special Issue Reviews and Advances in Internet of Things Technologies)
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Article
Investigation of Methods to Extract Fetal Electrocardiogram from the Mother’s Abdominal Signal in Practical Scenarios
Technologies 2020, 8(2), 33; https://doi.org/10.3390/technologies8020033 - 05 Jun 2020
Cited by 7 | Viewed by 2845
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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Article
Thermal and Visual Imaging to Assist with Juvenile Idiopathic Arthritis Examination of the Knees
Technologies 2020, 8(2), 30; https://doi.org/10.3390/technologies8020030 - 24 May 2020
Cited by 4 | Viewed by 2378
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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Article
Engineering Micropatterned Surfaces for Controlling the Evaporation Process of Sessile Droplets
Technologies 2020, 8(2), 29; https://doi.org/10.3390/technologies8020029 - 19 May 2020
Cited by 3 | Viewed by 2078
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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Article
A Zynq-Based Robotic System for Treatment of Contagious Diseases in Hospital Isolated Environment
Technologies 2020, 8(2), 28; https://doi.org/10.3390/technologies8020028 - 15 May 2020
Cited by 1 | Viewed by 2211
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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Article
Psychosocial Implications of Large-Scale Implementations of Solar Power in Malaysia
Technologies 2020, 8(2), 26; https://doi.org/10.3390/technologies8020026 - 14 May 2020
Cited by 2 | Viewed by 2114
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)
Article
Gate Sizing Methodology with a Novel Accurate Metric to Improve Circuit Timing Performance under Process Variations
Technologies 2020, 8(2), 25; https://doi.org/10.3390/technologies8020025 - 13 May 2020
Cited by 3 | Viewed by 1873
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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Article
An Interactive Real-Time Cutting Technique for 3D Models in Mixed Reality
Technologies 2020, 8(2), 23; https://doi.org/10.3390/technologies8020023 - 12 May 2020
Cited by 6 | Viewed by 2329
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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Article
Use Ultra-Wideband Discone Rectenna for Broadband RF Energy Harvesting Applications
Technologies 2020, 8(2), 21; https://doi.org/10.3390/technologies8020021 - 23 Apr 2020
Cited by 5 | Viewed by 2574
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
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Article
Recognition of Holoscopic 3D Video Hand Gesture Using Convolutional Neural Networks
Technologies 2020, 8(2), 19; https://doi.org/10.3390/technologies8020019 - 15 Apr 2020
Viewed by 3527
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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Article
Energy Conservation with Open Source Ad Blockers
Technologies 2020, 8(2), 18; https://doi.org/10.3390/technologies8020018 - 30 Mar 2020
Cited by 1 | Viewed by 6631
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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Article
ExerTrack—Towards Smart Surfaces to Track Exercises
Technologies 2020, 8(1), 17; https://doi.org/10.3390/technologies8010017 - 17 Mar 2020
Cited by 6 | Viewed by 2807
Abstract
The concept of the quantified self has gained popularity in recent years with the hype of miniaturized gadgets to monitor vital fitness levels. Smartwatches or smartphone apps and other fitness trackers are overwhelming the market. Most aerobic exercises such as walking, running, or [...] Read more.
The concept of the quantified self has gained popularity in recent years with the hype of miniaturized gadgets to monitor vital fitness levels. Smartwatches or smartphone apps and other fitness trackers are overwhelming the market. Most aerobic exercises such as walking, running, or cycling can be accurately recognized using wearable devices. However whole-body exercises such as push-ups, bridges, and sit-ups are performed on the ground and thus cannot be precisely recognized by wearing only one accelerometer. Thus, a floor-based approach is preferred for recognizing whole-body activities. Computer vision techniques on image data also report high recognition accuracy; however, the presence of a camera tends to raise privacy issues in public areas. Therefore, we focus on combining the advantages of ubiquitous proximity-sensing with non-optical sensors to preserve privacy in public areas and maintain low computation cost with a sparse sensor implementation. Our solution is the ExerTrack, an off-the-shelf sports mat equipped with eight sparsely distributed capacitive proximity sensors to recognize eight whole-body fitness exercises with a user-independent recognition accuracy of 93.5% and a user-dependent recognition accuracy of 95.1% based on a test study with 9 participants each performing 2 full sessions. We adopt a template-based approach to count repetitions and reach a user-independent counting accuracy of 93.6%. The final model can run on a Raspberry Pi 3 in real time. This work includes data-processing of our proposed system and model selection to improve the recognition accuracy and data augmentation technique to regularize the network. Full article
(This article belongs to the Collection Selected Papers from the PETRA Conference Series)
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Article
A New Simplified Model and Parameter Estimations for a HfO2-Based Memristor
Technologies 2020, 8(1), 16; https://doi.org/10.3390/technologies8010016 - 07 Mar 2020
Cited by 2 | Viewed by 2517
Abstract
The purpose of this paper was to propose a complete analysis and parameter estimations of a new simplified and highly nonlinear hafnium dioxide memristor model that is appropriate for high-frequency signals. For the simulations; a nonlinear window function previously offered by the author [...] Read more.
The purpose of this paper was to propose a complete analysis and parameter estimations of a new simplified and highly nonlinear hafnium dioxide memristor model that is appropriate for high-frequency signals. For the simulations; a nonlinear window function previously offered by the author together with a highly nonlinear memristor model was used. This model was tuned according to an experimentally recorded current–voltage relationship of a HfO2 memristor. This study offered an estimation of the optimal model parameters using a least squares algorithm in SIMULINK and a methodology for adjusting the model by varying its parameters overbroad ranges. The optimal values of the memristor model parameters were obtained after minimizing the error between the experimental and simulated current–voltage characteristics. A comparison of the obtained errors between the simulated and experimental current–voltage relationships was made. The error derived by the optimization algorithm was a little bit lower than that obtained by the used methodology. To avoid convergence problems; the step function in the considered model was replaced by a differentiable tangent hyperbolic function. A PSpice library model of the HfO2 memristor based on its mathematical model was created. The considered model was successfully applied and tested in a multilayer memristor neural network with bridge memristor–resistor synapses Full article
(This article belongs to the Special Issue MOCAST 2019: Modern Circuits and Systems Technologies on Electronics)
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Article
High Throughput Implementation of the Keccak Hash Function Using the Nios-II Processor
Technologies 2020, 8(1), 15; https://doi.org/10.3390/technologies8010015 - 10 Feb 2020
Cited by 2 | Viewed by 2849
Abstract
Presently, cryptographic hash functions play a critical role in many applications, such as digital signature systems, security communications, protocols, and network security infrastructures. The new standard cryptographic hash function is Secure Hash Algorithm 3 (SHA-3), which is not vulnerable to attacks. The Keccak [...] Read more.
Presently, cryptographic hash functions play a critical role in many applications, such as digital signature systems, security communications, protocols, and network security infrastructures. The new standard cryptographic hash function is Secure Hash Algorithm 3 (SHA-3), which is not vulnerable to attacks. The Keccak algorithm is the winner of the NIST competition for the adoption of the new standard SHA-3 hash algorithm. In this work, we present hardware throughput optimization techniques for the SHA-3 algorithm using the Very High Speed Integrated Circuit Hardware Description Language (VHDL) programming language for all output lengths in the Keccak hash function (224, 256, 384 and 512). Our experiments were performed with the Nios II processor on the FPGA Arria 10 GX (10AX115N2P45E1SG). We applied two architectures, one without custom instruction and one with floating point hardware 2. Finally, we compare the results with other existing similar designs and found that the proposed design with floating point 2 optimizes throughput (Gbps) compared to existing FPGA implementations. Full article
(This article belongs to the Special Issue MOCAST 2019: Modern Circuits and Systems Technologies on Electronics)
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Article
Demonstration of Reconfigurable BPFs with Wide Tuning Bandwidth Range Using 3λ/4 Open- and λ/2 Short- Ended Stubs
Technologies 2020, 8(1), 14; https://doi.org/10.3390/technologies8010014 - 03 Feb 2020
Viewed by 2458
Abstract
In this paper, two implementations of reconfigurable bandwidth bandpass filters (BPFs) are demonstrated both operating at a fixed center frequency of 2.4 GHz. The proposed reconfigurable bandwidth filters are based on a square ring resonator loaded with λg/4 open-ended stubs that [...] Read more.
In this paper, two implementations of reconfigurable bandwidth bandpass filters (BPFs) are demonstrated both operating at a fixed center frequency of 2.4 GHz. The proposed reconfigurable bandwidth filters are based on a square ring resonator loaded with λg/4 open-ended stubs that are permanently connected to the ring and converted to either 3λg/4 open-ended stubs or λg/2 short-ended stubs by means of positive-intrinsic-negative(PIN) diodes to implement two reconfigurable bandwidth states for each case. Due to the symmetrical nature of the design, even- and odd-mode analysis is used to derive the closed-form to describe the reconfigurable filters’ behavior. The switching between narrowband and wideband is achieved using PIN diodes. In the first implementation (λg/4 open-ended stubs to 3λg/4 open-ended stubs), a reconfigurable bandwidth bandpass filter is proposed where additional out-of-band transmission zeros are generated by integrating a λg/2 open-ended stub at the input port. In the second implementation (λg/4 open-ended stubs to λg/2 short-ended stubs), further improvement in the upper stopband is achieved by utilizing a pair of parallel coupled lines (PCLs) as feeding lines and a pair of λg/4 high impedance short-ended stubs implemented at the input and output ports. To verify the validity of the simulated results, the prototypes of the proposed reconfigurable filters were fabricated. For the first case, measured insertion loss is less than 1.8 dB with a switchable 3-dB fractional bandwidth (FBW) range from 28% to 54%. The measured results for the second case exhibit a low insertion loss of less than 1 dB and a 3-dB fractional bandwidth that can be switched from 34% to 75%, while the center frequency is kept constant at 2.4 GHz in both cases. Full article
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Article
A Parametric EIT System Spice Simulation with Phantom Equivalent Circuits
Technologies 2020, 8(1), 13; https://doi.org/10.3390/technologies8010013 - 01 Feb 2020
Cited by 8 | Viewed by 3511
Abstract
In this paper a number of LT Spice simulations have been carried out on an Electrical Impedance Tomography (EIT) system, which includes the whole analog and digital circuitry as well as the subject to be examined (phantom model). The aim of this study [...] Read more.
In this paper a number of LT Spice simulations have been carried out on an Electrical Impedance Tomography (EIT) system, which includes the whole analog and digital circuitry as well as the subject to be examined (phantom model). The aim of this study is to show how the analog and digital parts, the electrodes and the subject’s physical properties may impact the measurements and the quality of the reconstructed image. This could provide a useful tool for designing an EIT system. Special attention has been given to the current source’s output impedance and swing, to the noise produced by the circuits and to the Analog to Digital Converters (ADCs) resolution and sampling rate. Furthermore, some 3D phantom subjects have been modeled and simulated as equivalent circuits, merged with the EIT simulated hardware, in order to observe how changes on their properties interact with the whole circuitry and affect the final result. Observations show that mirrored current sources with z o u t > 350 k Ω and sufficiently high ADC acquisition sampling rate ( f s a m p l e 16 f i n ) can result to accurate impedance measurements and therefore quality image reconstruction within a frequency span of at least 10 to 100 kHz. Moreover, possible hardware failures (electrode disconnections and imbalanced contact impedances) can be detected with a simple examination of the first extracted image and measurement set, so that by direct modification of the reconstruction process, a corrected result can be obtained. Full article
(This article belongs to the Special Issue MOCAST 2019: Modern Circuits and Systems Technologies on Electronics)
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Article
Accelerometer and Magnetometer Joint Calibration and Axes Alignment
Technologies 2020, 8(1), 11; https://doi.org/10.3390/technologies8010011 - 23 Jan 2020
Cited by 6 | Viewed by 2858
Abstract
In this work, we propose an algorithm for joint calibration and axes alignment of a 3-axis accelerometer and a 3-axis magnetometer. The proposed algorithm applies when the two sensors are fixed on the same rigid platform. It achieves accurate calibration without requiring any [...] Read more.
In this work, we propose an algorithm for joint calibration and axes alignment of a 3-axis accelerometer and a 3-axis magnetometer. The proposed algorithm applies when the two sensors are fixed on the same rigid platform. It achieves accurate calibration without requiring any external piece of equipment like a turntable for the accelerometer or Gauss magnetic chamber and Maxwell coils setup for the magnetometer. The efficiency and accuracy of the proposed algorithm are evaluated using experimental data. Full article
(This article belongs to the Special Issue MOCAST 2019: Modern Circuits and Systems Technologies on Electronics)
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Article
Engineering Tests to Evaluate the Feasibility of an Emerging Solar Pavement Technology for Public Roads and Highways
Technologies 2020, 8(1), 9; https://doi.org/10.3390/technologies8010009 - 21 Jan 2020
Cited by 9 | Viewed by 4733
Abstract
Concrete and asphalt are the primary materials used to construct roadways for motor vehicles, paths for pedestrians and bicyclists, and runways for aircraft. Solar Roadways®, Inc. (SR) proposed a novel solar pavement technology (i.e., solar road panels (SRP)) as an alternative [...] Read more.
Concrete and asphalt are the primary materials used to construct roadways for motor vehicles, paths for pedestrians and bicyclists, and runways for aircraft. Solar Roadways®, Inc. (SR) proposed a novel solar pavement technology (i.e., solar road panels (SRP)) as an alternative material and energy source. SR performed load, traction, and impact testing to use SRPs in non-critical applications like parking lots. To use SRP in public roads, engineering tests including freeze/thaw, moisture absorption, heavy vehicle, and shear testing were accomplished on “SR3” prototypes. Testing was performed at Marquette University in the Engineering Materials and Structural Testing Laboratory and the SR Pilot Project area. Moisture absorption and freeze/thaw tests showed “SR3” resistant to extreme weather and moisture environments. Heavy vehicle testing revealed no physical damage to the “SR3” after approximately 989,457 equivalent single axle loads were continuously rolled over a prototype pavement. Shear testing was conducted to investigate “SR3” laminate structure properties. In all cases, electrical failure was defined when “SR3” photovoltaic voltage dropped to zero volts. The maximum shear stress and applied torque for “SR3”’ (S/N’s Paver 1, 002B, 007C, and 004B) were 1756 kPa, 1835 kPa, 1643 kPa, 2023 kPa; and 121.2 kN·m, 131.3 kN·m, 117.6 kN·m, 144.8 kN·m, respectively. In addition, the “SR3” “heartbeat” light emitting diode (LED) remained operational (i.e., indicates computer bus traffic) in all phases of shear testing. Overall, the results show “SR3” prototypes to be robust, resilient, and functional when subjected to “real-world” test conditions. Full article
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Article
The Importance of Introducing the OCTC Method to Undergraduate Students as a Tool for Circuit Analysis and Amplifier Design
Technologies 2020, 8(1), 7; https://doi.org/10.3390/technologies8010007 - 19 Jan 2020
Viewed by 3504
Abstract
The open-circuit-time-constant (OCTC) method is an approximate analytical computationally simple approach applicable to baseband amplifiers and cascades of them. It has a dual purpose: a) to estimate the dominant pole, and the −3dB bandwidth frequency, and b) to identify actual or parasitic component [...] Read more.
The open-circuit-time-constant (OCTC) method is an approximate analytical computationally simple approach applicable to baseband amplifiers and cascades of them. It has a dual purpose: a) to estimate the dominant pole, and the −3dB bandwidth frequency, and b) to identify actual or parasitic component values primarily responsible for this bandwidth guiding the designer in optimizing component values and circuit architecture. The present study focuses on the teaching of OCTC and the analysis of students’ depth of understanding. The OCTC module is part of the course “Electronics III” aimed towards advanced undergraduate students who are asked to solve two sets of problems analytically and simulate the circuits using LTspice and compare the results. The paper discusses students’ misconceptions and the evaluation of students’ performance via assignment grades, an anonymous sampling test and final exams (four exams during two academic years). A quantitative evaluation of the students’ perspective of the course is also presented based on two anonymous surveys, at the beginning and the end of the semester. According to the evaluation results, the proposed way of introducing the OCTC method along with the simulation exercises was beneficial for the students and improved their academic performance and attitude towards the course. Full article
(This article belongs to the Special Issue MOCAST 2019: Modern Circuits and Systems Technologies on Electronics)
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Article
A TensorFlow Extension Framework for Optimized Generation of Hardware CNN Inference Engines
Technologies 2020, 8(1), 6; https://doi.org/10.3390/technologies8010006 - 13 Jan 2020
Cited by 4 | Viewed by 4223
Abstract
The workloads of Convolutional Neural Networks (CNNs) exhibit a streaming nature that makes them attractive for reconfigurable architectures such as the Field-Programmable Gate Arrays (FPGAs), while their increased need for low-power and speed has established Application-Specific Integrated Circuit (ASIC)-based accelerators as alternative efficient [...] Read more.
The workloads of Convolutional Neural Networks (CNNs) exhibit a streaming nature that makes them attractive for reconfigurable architectures such as the Field-Programmable Gate Arrays (FPGAs), while their increased need for low-power and speed has established Application-Specific Integrated Circuit (ASIC)-based accelerators as alternative efficient solutions. During the last five years, the development of Hardware Description Language (HDL)-based CNN accelerators, either for FPGA or ASIC, has seen huge academic interest due to their high-performance and room for optimizations. Towards this direction, we propose a library-based framework, which extends TensorFlow, the well-established machine learning framework, and automatically generates high-throughput CNN inference engines for FPGAs and ASICs. The framework allows software developers to exploit the benefits of FPGA/ASIC acceleration without requiring any expertise on HDL development and low-level design. Moreover, it provides a set of optimization knobs concerning the model architecture and the inference engine generation, allowing the developer to tune the accelerator according to the requirements of the respective use case. Our framework is evaluated by optimizing the LeNet CNN model on the MNIST dataset, and implementing FPGA- and ASIC-based accelerators using the generated inference engine. The optimal FPGA-based accelerator on Zynq-7000 delivers 93% less memory footprint and 54% less Look-Up Table (LUT) utilization, and up to 10× speedup on the inference execution vs. different Graphics Processing Unit (GPU) and Central Processing Unit (CPU) implementations of the same model, in exchange for a negligible accuracy loss, i.e., 0.89%. For the same accuracy drop, the 45 nm standard-cell-based ASIC accelerator provides an implementation which operates at 520 MHz and occupies an area of 0.059 mm 2 , while the power consumption is ∼7.5 mW. Full article
(This article belongs to the Special Issue MOCAST 2019: Modern Circuits and Systems Technologies on Electronics)
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Article
SET Pulse Characterization and SER Estimation in Combinational Logic with Placement and Multiple Transient Faults Considerations
Technologies 2020, 8(1), 5; https://doi.org/10.3390/technologies8010005 - 10 Jan 2020
Cited by 4 | Viewed by 2731
Abstract
Integrated circuit susceptibility to radiation-induced faults remains a major reliability concern. The continuous downscaling of device feature size and the reduction in supply voltage in CMOS technology tend to worsen the problem. Thus, the evaluation of Soft Error Rate (SER) in the presence [...] Read more.
Integrated circuit susceptibility to radiation-induced faults remains a major reliability concern. The continuous downscaling of device feature size and the reduction in supply voltage in CMOS technology tend to worsen the problem. Thus, the evaluation of Soft Error Rate (SER) in the presence of multiple transient faults is necessary, since it remains an open research field. In this work, a Monte-Carlo simulation-based methodology is presented taking into consideration the masking mechanisms and placement information. The proposed SER estimation tool exploits the results of a Single Event Transient (SET) pulse characterization process with HSPICE to obtain an accurate assessment of circuit vulnerability to radiation. A new metric, called Glitch Latching Probability, which represents the impact of the masking effects on a SET, is introduced to identify gate sensitivity and, finally, experimental results on a set of ISCAS’ 89 benchmarks are presented. Full article
(This article belongs to the Special Issue MOCAST 2019: Modern Circuits and Systems Technologies on Electronics)
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Article
Integrating Animated Computational Fluid Dynamics into Mixed Reality for Building-Renovation Design
Technologies 2020, 8(1), 4; https://doi.org/10.3390/technologies8010004 - 29 Dec 2019
Cited by 7 | Viewed by 4338
Abstract
In advanced society, the existing building stock has a high demand for stock renovation, which gives existing buildings new lives, rather than building new ones. During the renovation process, it is necessary to simultaneously achieve architectural, facilities, structural, and environmental design in order [...] Read more.
In advanced society, the existing building stock has a high demand for stock renovation, which gives existing buildings new lives, rather than building new ones. During the renovation process, it is necessary to simultaneously achieve architectural, facilities, structural, and environmental design in order to accomplish a healthy, comfortable, and energy-saving indoor environment, prevent delays in problem-solving, and achieve a timely feedback process. This study tackled the development of an integrated system for stock renovation by considering computational fluid dynamics (CFD) and mixed reality (MR) in order to allow the simultaneous design of a building plan and thermal environment. The CFD analysis enables simulation of the indoor thermal environment, including the entire thermal change process. The MR system, which can be operated by voice command and operated on head-mounted display (HMD), enables intuitive visualization of the thermal change process and, in a very efficient manner, shows how different renovation projects perform for various stakeholders. A prototype system is developed with Unity3D engine and HoloLens HMD. In the integrated system, a new CFD visualization method generating 3D CFD animation sequence for the MR system is proposed that allows stakeholders to consider the entirety of changes in the thermal environment. Full article
(This article belongs to the Special Issue Computer-Aided Architectural Design)
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Article
Time Jitter, Turbulence and Chromatic Dispersion in Underwater Optical Wireless Links
Technologies 2020, 8(1), 3; https://doi.org/10.3390/technologies8010003 - 22 Dec 2019
Cited by 3 | Viewed by 3371
Abstract
The performance of an underwater optical wireless communication link is investigated by taking into account—for the first time and to the best of our knowledge—the simultaneous influence of the chromatic dispersion, the time jitter and the turbulence effects, by assuming chirped longitudinal Gaussian [...] Read more.
The performance of an underwater optical wireless communication link is investigated by taking into account—for the first time and to the best of our knowledge—the simultaneous influence of the chromatic dispersion, the time jitter and the turbulence effects, by assuming chirped longitudinal Gaussian pulse propagation as information carriers. The estimation procedure is presented and a novel probability density function is extracted in order to describe the irradiance fluctuations at the receiver side. Furthermore, the availability of the link is investigated by means of its probability of fade and various numerical results are presented using typical parameters for the underwater optical wireless communication systems. Full article
(This article belongs to the Section Information and Communication Technologies)
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Communication
Needleless Electrospinning of a Chitosan Lactate Aqueous Solution: Influence of Solution Composition and Spinning Parameters
Technologies 2020, 8(1), 2; https://doi.org/10.3390/technologies8010002 - 19 Dec 2019
Cited by 2 | Viewed by 3223
Abstract
The biological activity of chitosan determines its broad application as a biopolymer for non-woven wound dressings fabricated by electrospinning. The electrospinning process is affected by a large number of different factors that complicate its optimization. In the present work, the electrospinning of chitosan [...] Read more.
The biological activity of chitosan determines its broad application as a biopolymer for non-woven wound dressings fabricated by electrospinning. The electrospinning process is affected by a large number of different factors that complicate its optimization. In the present work, the electrospinning of chitosan lactate was carried out using a needleless technique from water solutions of different compositions. Surface response methodology was used to evaluate the effects of the concentration of chitosan, polyethylene oxide, and ethanol on solution properties, such as viscosity, surface tension, and conductivity, as well as the process characteristics and fiber quality. The viscosity of the spinning solution is determined by the polymer concentration as well as by the interpolymer interactions. The addition of ethanol to the spinning solutions effectively decreases the solution surface tension and conductivity, while increasing the volatility of the solvent, to provide more intense fiber spinning. Atomic force microscopy revealed that the chitosan lactate fibers were obtained without defects and with a narrow thickness distribution. The spinning parameters, voltage, distance between electrodes, and rotation speed of the spinning electrode had insignificant influences on the fiber diameter during needleless electrospinning. Full article
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Article
Incremental and Multi-Task Learning Strategies for Coarse-To-Fine Semantic Segmentation
Technologies 2020, 8(1), 1; https://doi.org/10.3390/technologies8010001 - 18 Dec 2019
Cited by 3 | Viewed by 4040
Abstract
The semantic understanding of a scene is a key problem in the computer vision field. In this work, we address the multi-level semantic segmentation task where a deep neural network is first trained to recognize an initial, coarse, set of a few classes. [...] Read more.
The semantic understanding of a scene is a key problem in the computer vision field. In this work, we address the multi-level semantic segmentation task where a deep neural network is first trained to recognize an initial, coarse, set of a few classes. Then, in an incremental-like approach, it is adapted to segment and label new objects’ categories hierarchically derived from subdividing the classes of the initial set. We propose a set of strategies where the output of coarse classifiers is fed to the architectures performing the finer classification. Furthermore, we investigate the possibility to predict the different levels of semantic understanding together, which also helps achieve higher accuracy. Experimental results on the New York University Depth v2 (NYUDv2) dataset show promising insights on the multi-level scene understanding. Full article
(This article belongs to the Special Issue Computer Vision and Image Processing Technologies)
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Article
An Inverse Pheromone Approach in a Chaotic Mobile Robot’s Path Planning Based on a Modified Logistic Map
Technologies 2019, 7(4), 84; https://doi.org/10.3390/technologies7040084 - 06 Dec 2019
Cited by 11 | Viewed by 2877
Abstract
One major topic in the research of path planning of autonomous mobile robots is the fast and efficient coverage of a given terrain. For this purpose, an efficient method for covering a given workspace is proposed, based on chaotic path planning. The method [...] Read more.
One major topic in the research of path planning of autonomous mobile robots is the fast and efficient coverage of a given terrain. For this purpose, an efficient method for covering a given workspace is proposed, based on chaotic path planning. The method is based on a chaotic pseudo random bit generator that is generated using a modified logistic map, which is used to generate a chaotic motion pattern. This is then combined with an inverse pheromone approach in order to reduce the number of revisits in each cell. The simulated robot under study has the capability to move in four or eight directions. From extensive simulations performed in Matlab, it is derived that motion in eight directions gives superior results. Especially, with the inclusion of pheromone, the coverage percentage can significantly be increased, leading to better performance. Full article
(This article belongs to the Special Issue MOCAST 2019: Modern Circuits and Systems Technologies on Electronics)
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Article
Compensation for Geometrical Deviations in Additive Manufacturing
Technologies 2019, 7(4), 83; https://doi.org/10.3390/technologies7040083 - 02 Dec 2019
Cited by 7 | Viewed by 3580
Abstract
The design of additive manufacturing processes, especially for batch production in industrial practice, is of high importance for the propagation of new additive manufacturing technology. Manual redesign procedures of the additive manufactured parts based on discrete measurement data or numerical meshes are error [...] Read more.
The design of additive manufacturing processes, especially for batch production in industrial practice, is of high importance for the propagation of new additive manufacturing technology. Manual redesign procedures of the additive manufactured parts based on discrete measurement data or numerical meshes are error prone and hardly automatable. To achieve the required final accuracy of the parts, often, various iterations are necessary. To address these issues, a data-driven geometrical compensation approach is proposed that adapts concepts from forming technology. The measurement information of a first calibration cycle of manufactured parts is the basis of the approach. Through non-rigid transformations of the part geometry, a new shape for the subsequent additive manufacturing process was derived in a systematic way. Based on a purely geometrical approach, the systematic portion of part deviations can be compensated. The proposed concept is presented first and was applied to a sample fin-shaped part. The deviation data of three manufacturing cycles was utilised for validation and verification. Full article
(This article belongs to the Special Issue Reviews and Advances in Materials Processing)
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Article
3D Model Generation on Architectural Plan and Section Training through Machine Learning
Technologies 2019, 7(4), 82; https://doi.org/10.3390/technologies7040082 - 15 Nov 2019
Cited by 4 | Viewed by 4434
Abstract
Machine learning, especially the GAN (Generative Adversarial Network) model, has been developed tremendously in recent years. Since the NVIDIA Machine Learning group presented the StyleGAN in December 2018, it has become a new way for designers to make machines learn different or similar [...] Read more.
Machine learning, especially the GAN (Generative Adversarial Network) model, has been developed tremendously in recent years. Since the NVIDIA Machine Learning group presented the StyleGAN in December 2018, it has become a new way for designers to make machines learn different or similar types of architectural photos, drawings, and renderings, then generate (a) similar fake images, (b) style-mixing images, and (c) truncation trick images. The author both collected and created input image data, and specially made architectural plan and section drawing inputs with a clear design purpose, then applied StyleGAN to train specific networks on these datasets. With the training process, we could look into the deep relationship between these input architectural plans or sections, then generate serialized transformation images (truncation trick images) to form the 3D (three-dimensional) model with a decent resolution (up to 1024 × 1024 × 1024 pixels). Though the results of the 3D model generation are difficult to use directly in 3D spatial modeling, these unexpected 3D forms still could inspire new design methods and greater possibilities of architectural plan and section design. Full article
(This article belongs to the Special Issue Computer-Aided Architectural Design)
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Communication
AFM Characterization of Stir-Induced Micro-Flow Features within the AA6082-T6 BFSW Welds
Technologies 2019, 7(4), 80; https://doi.org/10.3390/technologies7040080 - 07 Nov 2019
Cited by 11 | Viewed by 3260
Abstract
Bobbin Friction Stir Welding (BFSW) is a thermomechanical process containing severe plastic deformation by mechanical stirring and Dynamic Recrystallization (DRX) during recooling. Here we report the three-dimensional characteristics of the micro-flow patterns within the aluminium weld structure. The Surface topography observations by Atomic [...] Read more.
Bobbin Friction Stir Welding (BFSW) is a thermomechanical process containing severe plastic deformation by mechanical stirring and Dynamic Recrystallization (DRX) during recooling. Here we report the three-dimensional characteristics of the micro-flow patterns within the aluminium weld structure. The Surface topography observations by Atomic Force Microscopy (AFM) show the stirred-induced microstructural evolution where the rearrangement of dislocations at the sub-grain scale, and the subsequent High- and Low-Angle Grain Boundaries (HAGBs, LAGBs) exhibit specific alterations in grain size and morphology of the weld texture. The dislocations interaction in different regions of the weld structure also was observed in correlation to the thermomechanical behaviour of the BFSW process. These micro-flow observations within the weld breadth give a new insight into the thermomechanical characteristics of the FSW process during the stirring action where the plastic flow has a key role in the formation of the weld region distinct from the base metal. Full article
(This article belongs to the Special Issue Reviews and Advances in Materials Processing)
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Article
An Improved Calculation Model for the Prediction of the Wear of Coated Electrical Contacts
Technologies 2019, 7(4), 77; https://doi.org/10.3390/technologies7040077 - 31 Oct 2019
Cited by 2 | Viewed by 3023
Abstract
To connect terminals in a cyber–physical system, large quantities of electrical contacts are used. In order to guarantee a high reliability of the system, the lifetime of the electrical contacts should be very long. Thus, it is of great importance to understand the [...] Read more.
To connect terminals in a cyber–physical system, large quantities of electrical contacts are used. In order to guarantee a high reliability of the system, the lifetime of the electrical contacts should be very long. Thus, it is of great importance to understand the failure mechanism and then to predict the lifetime of the electrical contacts. For the applications under high thermal and/or mechanical loads, noble plating is a good choice, considering its inertness to oxidation. For noble plating, one of the most critical failure mechanisms is the fretting wear. Wear debris generated in the contact area, acting as the third bodies, will greatly influence the further wear behavior and electrical performance. In this study, the state of the art regarding third bodies is firstly reviewed, and then the influence of the third bodies on the wear and electrical performance is investigated, from the aspects of lifetime and the element distributions in contact area. Finally, an example of prediction of the wear of noble plating is shown with the consideration of the third bodies. Based on this study, by involving the third bodies, the wear of noble plating can be predicted with a higher accuracy. Full article
(This article belongs to the Special Issue Microswitching Technologies)
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Article
From Undesired Flaws to Esthetic Assets: A Digital Framework Enabling Artistic Explorations of Erroneous Geometric Features of Robotically Formed Molds
Technologies 2019, 7(4), 78; https://doi.org/10.3390/technologies7040078 - 31 Oct 2019
Cited by 1 | Viewed by 3213
Abstract
Until recently, digital fabrication research in architecture has aimed to eliminate manufacturing errors. However, a novel notion has just been established—intentional computational infidelity. Inspired by this notion, we set out to develop means than can transform the errors in fabrication from an undesired [...] Read more.
Until recently, digital fabrication research in architecture has aimed to eliminate manufacturing errors. However, a novel notion has just been established—intentional computational infidelity. Inspired by this notion, we set out to develop means than can transform the errors in fabrication from an undesired complication to a creative opportunity. We carried out design experiment-based investigations, which culminated in the construction of a framework enabling fundamental artistic explorations of erroneous geometric features of robotically formed molds. The framework consists of digital processes, assisting in the explorations of mold errors, and physical processes, enabling the inclusion of physical feedback in digital explorations. Other complementary elements embrace an implementation workflow, an enabling digital toolset and a visual script demonstrating how imprecise artistic explorations can be included within the computational environment. Our framework application suggests that the exploration of geometrical errors aids the emergence of unprecedented design features that would not have arisen if error elimination were the ultimate design goal. Our conclusion is that welcoming error into the design process can reinstate the role of art, craft, and material agency therein. This can guide the practice and research of architectural computing onto a new territory of esthetic and material innovation. Full article
(This article belongs to the Special Issue Computer-Aided Architectural Design)
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Article
Analysis of a Chaotic System with Line Equilibrium and Its Application to Secure Communications Using a Descriptor Observer
Technologies 2019, 7(4), 76; https://doi.org/10.3390/technologies7040076 - 24 Oct 2019
Cited by 9 | Viewed by 3159
Abstract
In this work a novel chaotic system with a line equilibrium is presented. First, a dynamical analysis on the system is performed, by computing its bifurcation diagram, continuation diagram, phase portraits and Lyapunov exponents. Then, the system is applied to the problem of [...] Read more.
In this work a novel chaotic system with a line equilibrium is presented. First, a dynamical analysis on the system is performed, by computing its bifurcation diagram, continuation diagram, phase portraits and Lyapunov exponents. Then, the system is applied to the problem of secure communication. We assume that the transmitted signal is an additional state. For this reason, the nonlinear system is rewritten in a rectangular descriptor form and then an observer is constructed for achieving synchronization and input reconstruction. If we assume some rank conditions (on the nonlinearities and the solvability of a linear matrix inequality (LMI)) on the system matrices then the observer synchronization can be feasible. We evaluate and demonstrate our approach with specific numerical results. Full article
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Article
Open Source Waste Plastic Granulator
Technologies 2019, 7(4), 74; https://doi.org/10.3390/technologies7040074 - 14 Oct 2019
Cited by 7 | Viewed by 10325
Abstract
In order to accelerate deployment of distributed recycling by providing low-cost feed stocks of granulated post-consumer waste plastic, this study analyzes an open source waste plastic granulator system. It is designed, built, and tested for its ability to convert post-consumer waste, 3D printed [...] Read more.
In order to accelerate deployment of distributed recycling by providing low-cost feed stocks of granulated post-consumer waste plastic, this study analyzes an open source waste plastic granulator system. It is designed, built, and tested for its ability to convert post-consumer waste, 3D printed products and waste into polymer feedstock for recyclebots of fused particle/granule printers. The technical specifications of the device are quantified in terms of power consumption (380 to 404 W for PET and PLA, respectively) and particle size distribution. The open source device can be fabricated for less than $2000 USD in materials. The experimentally measured power use is only a minor contribution to the overall embodied energy of distributed recycling of waste plastic. The resultant plastic particle size distributions were found to be appropriate for use in both recyclebots and direct material extrusion 3D printers. Simple retrofits are shown to reduce sound levels during operation by 4dB-5dB for the vacuum. These results indicate that the open source waste plastic granulator is an appropriate technology for community, library, maker space, fab lab, or small business–based distributed recycling. Full article
(This article belongs to the Section Innovations in Materials Processing)
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Article
Psychosocial Impact of Powered Wheelchair, Users’ Satisfaction and Their Relation to Social Participation
Technologies 2019, 7(4), 73; https://doi.org/10.3390/technologies7040073 - 10 Oct 2019
Cited by 2 | Viewed by 3424
Abstract
Several studies showed positive effects of assistive technologies on psychosocial impact and participation of adults with mobility impairments. The purpose of this study was to assess the psychosocial and participation impact of powered wheelchairs. Participants were thirty persons with disabilities who use powered [...] Read more.
Several studies showed positive effects of assistive technologies on psychosocial impact and participation of adults with mobility impairments. The purpose of this study was to assess the psychosocial and participation impact of powered wheelchairs. Participants were thirty persons with disabilities who use powered wheelchairs with diverse medical conditions. The Quebec User Evaluation of Satisfaction with Assistive Technology, the Psychosocial Impact of Assistive Devices Scale and the Activities and Participation Profile Related to Mobility were used, in addition to demographic, clinical and wheelchair related questions. The participants were satisfied with both the assistive technology and related services, with the lowest satisfaction scores belonging to those who had been using their wheelchairs for a longer period of time. We noticed significant restrictions in participation mostly among persons with longer wheelchair utilization. The most satisfied were the ones with better performance in terms of social participation. Psychosocial scores showed a positive impact with higher adaptability among persons who transitioned from a manual compared to those who already had a powered wheelchair. There was a positive psychosocial impact and therefore an increase in quality of life of its users. Full article
(This article belongs to the Section Assistive Technologies)
Article
Convolution of Barker and Golay Codes for Low Voltage Ultrasonic Testing
Technologies 2019, 7(4), 72; https://doi.org/10.3390/technologies7040072 - 10 Oct 2019
Cited by 5 | Viewed by 3476
Abstract
Ultrasonic Testing (UT) is one of the most important technologies in Non-Detective Testing (NDT) methods. Recently, Barker code and Golay code pairs as coded excitation signals have been applied in ultrasound imaging system with improved quality. However, the signal-to-noise ratio (SNR) of existing [...] Read more.
Ultrasonic Testing (UT) is one of the most important technologies in Non-Detective Testing (NDT) methods. Recently, Barker code and Golay code pairs as coded excitation signals have been applied in ultrasound imaging system with improved quality. However, the signal-to-noise ratio (SNR) of existing UT system based on Barker code or Golay code can be influenced under high high attenuation materials or noisy conditions. In this paper, we apply the convolution of Barker and Golay codes as coded excitation signals for low voltage UT devices that combines the advantages of Barker code and Golay code together. There is no need to change the hardware of UT system in this method. The proposed method has been analyzed theoretically and then in extensive simulations. The experimental results demonstrated that the main lobe level of the code produced by convolution of Barker code and Golay code pairs is much higher than the simple pulse and the main lobe of the combined code is higher than the traditional Barker code, sidelobe is the same as the baker code that constitutes this combined code. So the peak sidelobe level (PSL) of the combined code is lower than the traditional Barker code. Equipped with this, UT devices can be applied in low voltage situations. Full article
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Article
A Cold-Pressing Method Combining Axial and Shear Flow of Powder Compaction to Produce High-Density Iron Parts
Technologies 2019, 7(4), 70; https://doi.org/10.3390/technologies7040070 - 24 Sep 2019
Cited by 2 | Viewed by 3476
Abstract
Highly performance methods for cold pressing (cold die forging) of preforms from iron powder with subsequent heat treatment and producing ready parts made of powder are described in the paper. These methods allow fabricating parts with smooth surfaces and improved mechanical characteristics—porosity, tensile [...] Read more.
Highly performance methods for cold pressing (cold die forging) of preforms from iron powder with subsequent heat treatment and producing ready parts made of powder are described in the paper. These methods allow fabricating parts with smooth surfaces and improved mechanical characteristics—porosity, tensile strength. Application of the traditional design set-up with a single-axial loading is restricted to high stresses in the dies to deform the preforms that lead to cracks formation. New powder compaction schemes by applying active friction forces (shear-enhanced compaction) make it possible to unload dies and produce high-quality parts by cold pressing. The scheme allows moving the die in the direction of the material flow with a velocity that exceeds the material flow velocity. Full article
(This article belongs to the Special Issue Processing and Fabrication of Advanced Materials)
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Transient Contact Opening Forces in a MEMS Switch Using Au/MWCNT Composite
Technologies 2019, 7(4), 69; https://doi.org/10.3390/technologies7040069 - 23 Sep 2019
Cited by 1 | Viewed by 3031
Abstract
Most failures in micro electromechanical system (MEMS) switches can be attributed to the degradation of contact surfaces and sticking contacts. A wear-tolerant composite contact material, composed of a Au film supported by multi walled carbon nanotubes (Au/MWCNT), has been engineered to provide wear [...] Read more.
Most failures in micro electromechanical system (MEMS) switches can be attributed to the degradation of contact surfaces and sticking contacts. A wear-tolerant composite contact material, composed of a Au film supported by multi walled carbon nanotubes (Au/MWCNT), has been engineered to provide wear resistance and enhanced switching lifetime with conductive properties close to pure Au. Switching lifetimes of billions of cycles have been demonstrated, representing greatly increased performance over thin film Au. Below the arcing threshold (~12 V) the wear mechanism has been shown to be a combination of the fine transfer of contact material by the molten metal bridge (MMB) phenomenon and a delamination of the Au. In this study, the composite contact is hot switched at low current DC conditions (4 V DC and 20 mA) while the contact force is measured at the micro Newton scale in nanosecond resolution. The characteristic voltage waveform associated with the MMB is observed with forces detected as the contact softens, melts, and separates. The presence of a delamination event (DE) is also observed, where the contact opens abruptly with no MMB phenomenon apparent. The DE contact openings are associated with a transient peak force of 21.6 ± 2.3 µN while the MMBs are linked to a lower peak force of 18.1 ± 2.5 µN. Full article
(This article belongs to the Special Issue Microswitching Technologies)
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Article
Validation of Different Filters for Center of Pressure Measurements by a Cross-Section Study
Technologies 2019, 7(4), 68; https://doi.org/10.3390/technologies7040068 - 20 Sep 2019
Cited by 4 | Viewed by 3595
Abstract
The measurement of the center of pressure (CoP) is one of the most frequently used quantitative methods for quantifying postural performance. Due to the complexity and the high biological variability of the postural control loop, a large number of different methods and parameters [...] Read more.
The measurement of the center of pressure (CoP) is one of the most frequently used quantitative methods for quantifying postural performance. Due to the complexity and the high biological variability of the postural control loop, a large number of different methods and parameters have been established to describe the CoP process. Furthermore, the methodological conditions such as the foot position, visual condition, sampling duration, and the data processing also have a relevant influence on the measurement results. In addition, there are various methods for recording the pressure curve, which differ in particular with regard to the filters used, the frequencies, and measurement times. The aim of the present study was the methodical comparison between different digital filters, measurement frequencies and times, and their effects on the CoP process based on a healthy reference group. The data acquisition was done with LabVIEW and the data storage was organized in a subject oriented data structure. Based on the presented results it could be seen that with a different dominant frequency in the spectrum of the group of test persons, certain filter types are required for the processing of CoP data. In the sampling range from 300 Hz to 1 kHz in the bipedal stand and 600 Hz to 1 kHz in the monopedal stand, the choice of measurement frequency had no influence on the filter result. Full article
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Article
Evaluation of Wirelessly Transmitted Video Quality Using a Modular Fuzzy Logic System
Technologies 2019, 7(3), 67; https://doi.org/10.3390/technologies7030067 - 14 Sep 2019
Cited by 5 | Viewed by 3554
Abstract
Video transmission over wireless computer networks is increasingly popular as new applications emerge and wireless networks become more widespread and reliable. An ability to quantify the quality of a video transmitted using a wireless computer network is important for determining network performance and [...] Read more.
Video transmission over wireless computer networks is increasingly popular as new applications emerge and wireless networks become more widespread and reliable. An ability to quantify the quality of a video transmitted using a wireless computer network is important for determining network performance and its improvement. The process requires analysing the images making up the video from the point of view of noise and associated distortion as well as traffic parameters represented by packet delay, jitter and loss. In this study a modular fuzzy logic based system was developed to quantify the quality of video transmission over a wireless computer network. Peak signal to noise ratio, structural similarity index and image difference were used to represent the user’s quality of experience (QoE) while packet delay, jitter and percentage packet loss ratio were used to represent traffic related quality of service (QoS). An overall measure of the video quality was obtained by combining QoE and QoS values. Systematic sampling was used to reduce the number of images processed and a novel scheme was devised whereby the images were partitioned to more sensitively localize distortions. To further validate the developed system, a subjective test involving 25 participants graded the quality of the received video. The image partitioning significantly improved the video quality evaluation. The subjective test results correlated with the developed fuzzy logic approach. The video quality assessment developed in this study was compared against a method that uses spatial efficient entropic differencing and consistent results were observed. The study indicated that the developed fuzzy logic approaches could accurately determine the quality of a wirelessly transmitted video. Full article
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A Bayesian Study of the Dynamic Effect of Comorbidities on Hospital Outcomes of Care for Congestive Heart Failure Patients
Technologies 2019, 7(3), 66; https://doi.org/10.3390/technologies7030066 - 13 Sep 2019
Cited by 2 | Viewed by 3019
Abstract
Comorbidities can have a cumulative effect on hospital outcomes of care, such as the length of stay (LOS), and hospital mortality. This study examines patients hospitalized with congestive heart failure (CHF), a life-threatening condition, which, when it coexists with a burdened disease profile, [...] Read more.
Comorbidities can have a cumulative effect on hospital outcomes of care, such as the length of stay (LOS), and hospital mortality. This study examines patients hospitalized with congestive heart failure (CHF), a life-threatening condition, which, when it coexists with a burdened disease profile, the risk for negative hospital outcomes increases. Since coexisting conditions co-interact, with a variable effect on outcomes, clinicians should be able to recognize these joint effects. In order to study CHF comorbidities, we used medical claims data from the Centers for Medicare and Medicaid Services (CMS). After extracting the most frequent cluster of CHF comorbidities, we: (i) Calculated, step-by-step, the conditional probabilities for each disease combination inside this cluster; (ii) estimated the cumulative effect of each comorbidity combination on the LOS and hospital mortality; and (iii) constructed (a) Bayesian, scenario-based graphs, and (b) Bayes-networks to visualize results. Results show that, for CHF patients, different comorbidity constructs have a variable effect on the LOS and hospital mortality. Therefore, dynamic comorbidity risk assessment methods should be implemented for informed clinical decision making in an ongoing effort for quality of care improvements. Full article
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Article
Data-Driven Recognition and Extraction of PDF Document Elements
Technologies 2019, 7(3), 65; https://doi.org/10.3390/technologies7030065 - 11 Sep 2019
Cited by 2 | Viewed by 4390
Abstract
In the age of digitalization, the collection and analysis of large amounts of data is becoming increasingly important for enterprises to improve their businesses and processes, such as the introduction of new services or the realization of resource-efficient production. Enterprises concentrate strongly on [...] Read more.
In the age of digitalization, the collection and analysis of large amounts of data is becoming increasingly important for enterprises to improve their businesses and processes, such as the introduction of new services or the realization of resource-efficient production. Enterprises concentrate strongly on the integration, analysis and processing of their data. Unfortunately, the majority of data analysis focuses on structured and semi-structured data, although unstructured data such as text documents or images account for the largest share of all available enterprise data. One reason for this is that most of this data is not machine-readable and requires dedicated analysis methods, such as natural language processing for analyzing textual documents or object recognition for recognizing objects in images. Especially in the latter case, the analysis methods depend strongly on the application. However, there are also data formats, such as PDF documents, which are not machine-readable and consist of many different document elements such as tables, figures or text sections. Although the analysis of PDF documents is a major challenge, they are used in all enterprises and contain various information that may contribute to analysis use cases. In order to enable their efficient retrievability and analysis, it is necessary to identify the different types of document elements so that we are able to process them with tailor-made approaches. In this paper, we propose a system that forms the basis for structuring unstructured PDF documents, so that the identified document elements can subsequently be retrieved and analyzed with tailor-made approaches. Due to the high diversity of possible document elements and analysis methods, this paper focuses on the automatic identification and extraction of data visualizations, algorithms, other diagram-like objects and tables from a mixed document body. For that, we present two different approaches. The first approach uses methods from the area of deep learning and rule-based image processing whereas the second approach is purely based on deep learning. To train our neural networks, we manually annotated a large corpus of PDF documents with our own annotation tool, of which both are being published together with this paper. The results of our extraction pipeline show that we are able to automatically extract graphical items with a precision of 0.73 and a recall of 0.8. For tables, we reach a precision of 0.78 and a recall of 0.94. Full article
(This article belongs to the Section Information and Communication Technologies)
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Article
Surface Hardening of Massive Steel Products in the Low-pressure Glow Discharge Plasma
Technologies 2019, 7(3), 62; https://doi.org/10.3390/technologies7030062 - 28 Aug 2019
Cited by 2 | Viewed by 3321
Abstract
A process vacuum chamber is filled with a homogeneous plasma of glow discharge with electrostatic electron confinement, which is used for surface hardening of massive products. At the current of 2–20 A and the gas pressure ranging from 0.1 to 1 Pa the [...] Read more.
A process vacuum chamber is filled with a homogeneous plasma of glow discharge with electrostatic electron confinement, which is used for surface hardening of massive products. At the current of 2–20 A and the gas pressure ranging from 0.1 to 1 Pa the discharge voltage amounts to 350–500 V. When a bias voltage of 2 kV is applied to an immersed in the plasma hollow cylinder with a mass of 15 kg, electrical power spent on heating it by accelerated ions exceeds by an order of magnitude the power spent on the discharge maintenance. The massive cylinder is heated up to 700 °C for 15 min. When argon mixture with nitrogen (30%) is used, the nitriding for 3h results in an increase in the surface hardness from 400 up to 1000 HV50 and the nitrided layer thickness grows to ~100 μm. The nitriding rate is enhanced by a high degree of nitrogen dissociation due to decomposition by fast electrons and surface structural defects due to bombardment by high-energy ions. Full article
(This article belongs to the Special Issue Processing and Fabrication of Advanced Materials)
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Article
Advanced Solutions Aimed at the Monitoring of Falls and Human Activities for the Elderly Population
Technologies 2019, 7(3), 59; https://doi.org/10.3390/technologies7030059 - 20 Aug 2019
Cited by 3 | Viewed by 3310
Abstract
Ageing is a global phenomenon which is pushing the scientific community forward the development of innovative solutions in the context of Active and Assisted Living (AAL). Among functionality to be implemented, a major role is covered by falls and human activities monitoring. In [...] Read more.
Ageing is a global phenomenon which is pushing the scientific community forward the development of innovative solutions in the context of Active and Assisted Living (AAL). Among functionality to be implemented, a major role is covered by falls and human activities monitoring. In this paper, main technological solutions to cope with the aforementioned needs are briefly introduced. A specific focus is given on solutions for Falls recognition and classification. A case of study is presented, where a classification methodology based on an event-driven correlation paradigm and an advanced threshold-based classifier is addressed. The receiver operating characteristic (ROC) theory is used to properly define thresholds’ values while, in order to properly assess performances of the classification methodology proposed, dedicated metrics are suggested, such as sensitivity and specificity. The solution proposed shows an average Sensitivity of 0.97 and an average Specificity of 0.99. Full article
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Article
Effects of the Infill Density on the Mechanical Properties of Nylon Specimens Made by Filament Fused Fabrication
Technologies 2019, 7(3), 57; https://doi.org/10.3390/technologies7030057 - 16 Aug 2019
Cited by 25 | Viewed by 4225
Abstract
Additive manufacturing of polymer products over the past decade has become widespread in various areas of industry. Using the fused filament fabrication (FFF) method, one of the most technologically simple methods of additive manufacturing, it is possible to produce parts from a large [...] Read more.
Additive manufacturing of polymer products over the past decade has become widespread in various areas of industry. Using the fused filament fabrication (FFF) method, one of the most technologically simple methods of additive manufacturing, it is possible to produce parts from a large number of different materials, including wear-resistant nylon. The novelty of the work is properties investigation of ±45° filling configuration with different filling degree for nylon, as well as calculating the effect of infill on the strength characteristics, excluding the shell. This article reflects the process of manufacturing samples from nylon using FFF technology with various internal topologies, as well as tensile tests. The analysis of the obtained results is performed and the relationship between the structure of the sample and the limit of its strength is established. To calculate real filling degree and the effect of internal filling on the strength characteristics of the specimen, it is proposed to use a method based on the geometric and mass parameters. The FFF method is promising for developing methods for producing a composite material. The results of this article can be useful in choosing the necessary manufacturing parameters. Full article
(This article belongs to the Special Issue Reviews and Advances in Materials Processing)
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Article
Choreographic Pattern Analysis from Heterogeneous Motion Capture Systems Using Dynamic Time Warping
Technologies 2019, 7(3), 56; https://doi.org/10.3390/technologies7030056 - 16 Aug 2019
Cited by 3 | Viewed by 3400
Abstract
The convention for the safeguarding of Intangible Cultural Heritage (ICH) by UNESCO highlights the equal importance of intangible elements of cultural heritage to tangible ones. One of the most important domains of ICH is folkloric dances. A dance choreography is a time-varying 3D [...] Read more.
The convention for the safeguarding of Intangible Cultural Heritage (ICH) by UNESCO highlights the equal importance of intangible elements of cultural heritage to tangible ones. One of the most important domains of ICH is folkloric dances. A dance choreography is a time-varying 3D process (4D modelling), which includes dynamic co-interactions among different actors, emotional and style attributes, and supplementary elements, such as music tempo and costumes. Presently, research focuses on the use of depth acquisition sensors, to handle kinesiology issues. The extraction of skeleton data, in real time, contains a significant amount of information (data and metadata), allowing for various choreography-based analytics. In this paper, a trajectory interpretation method for Greek folkloric dances is presented. We focus on matching trajectories’ patterns, existing in a choreographic database, to new ones originating from different sensor types such as VICON and Kinect II. Then, a Dynamic Time Warping (DTW) algorithm is proposed to find out similarities/dissimilarities among the choreographic trajectories. The goal is to evaluate the performance of the low-cost Kinect II sensor for dance choreography compared to the accurate but of high-cost VICON-based choreographies. Experimental results on real-life dances are carried out to show the effectiveness of the proposed DTW methodology and the ability of Kinect II to localize dances in 3D space. Full article
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Article
A Cellular Automata Model of the Relationship between Adverse Events and Regional Infrastructure Development in an Active War Theater
Technologies 2019, 7(3), 54; https://doi.org/10.3390/technologies7030054 - 07 Aug 2019
Viewed by 3483
Abstract
This study presents a cellular automata (CA) model to assist decision-makers in understanding the effects of infrastructure development projects on adverse events in an active war theater. The adverse events are caused by terrorist activities that primarily target the civilian population in countries [...] Read more.
This study presents a cellular automata (CA) model to assist decision-makers in understanding the effects of infrastructure development projects on adverse events in an active war theater. The adverse events are caused by terrorist activities that primarily target the civilian population in countries such as Afghanistan. In the CA-based model, cells in the same neighborhood synchronously interact with one another to determine their next states, and small changes in iteration yield to complex formations of adverse event risks. The results demonstrate that the proposed model can help in the evaluation of infrastructure development projects in relation to changes in the reported adverse events, as well as in the identification of the geographical locations, times, and impacts of such developments. The results also show that infrastructure development projects have different impacts on the reported adverse events. The CA modeling approach can be used to support decision-makers in allocating infrastructure development funds to stabilize active war regions with higher adverse event risks. Such models can also improve the understanding of the complex interactions between infrastructure development projects and adverse events. Full article
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Article
The Effect of the Terminal Functional Groups on Fluoropolymer on Electrowetting Device Performance
Technologies 2019, 7(3), 52; https://doi.org/10.3390/technologies7030052 - 27 Jul 2019
Cited by 2 | Viewed by 3530
Abstract
Electrowetting on dielectric (EWOD) devices were fabricated using two hydrophobic organic fluoropolymers, comprising CYTOP (a product name) having different chemical structures only at the terminal functional groups. These devices were subsequently characterized by applying a range of direct current (DC) voltages. The data [...] Read more.
Electrowetting on dielectric (EWOD) devices were fabricated using two hydrophobic organic fluoropolymers, comprising CYTOP (a product name) having different chemical structures only at the terminal functional groups. These devices were subsequently characterized by applying a range of direct current (DC) voltages. The data demonstrated that the EWOD performance was dramatically improved upon incorporating a CYTOP polymer having highly polar terminal functional groups, as compared to a polymer having terminal groups with lower polarity. The new finding about the positive effect of highly polar terminal functional groups on the enhancement of EWOD was exhibited through various careful experiments, changing only the quantitative amount of polar terminal functional groups while keeping other factors constant (thickness, substrate, etc.). Full article
(This article belongs to the Special Issue Smart Systems (SmaSys2018))
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Article
A Self-Deformation Robot Design Incorporating Bending-Type Pneumatic Artificial Muscles
Technologies 2019, 7(3), 51; https://doi.org/10.3390/technologies7030051 - 23 Jul 2019
Cited by 4 | Viewed by 4092
Abstract
With robots becoming closer to humans in recent years, human-friendly robots made of soft materials provide a new line of research interests. We designed and developed a soft robot that can move via self-deformation toward the practical application of monitoring children and the [...] Read more.
With robots becoming closer to humans in recent years, human-friendly robots made of soft materials provide a new line of research interests. We designed and developed a soft robot that can move via self-deformation toward the practical application of monitoring children and the elderly on a daily basis. The robot’s structure was built out of flexible frames, which are bending-type pneumatic artificial muscles (BPAMs). We first provide a description and discussion on the nature of BPAM, followed by static characteristics experiment. Although the BPAM theoretical model shares a similar tendency with the experimental results, the actual BPAMs moved along the depth direction. We then proposed and demonstrated an effective locomotion method for the robot and calculated its locomotion speed by measuring its drive time and movement distance. Our results confirmed the reasonability of the robot’s speed for monitoring children and the elderly. Nevertheless, during the demonstration, some BPAMs were bent sharply by other activated BPAMs as the robot was driving, leaving a little damage on these BPAMs. This will be addressed in our future work. Full article
(This article belongs to the Special Issue Smart Systems (SmaSys2018))
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Article
ThingsLocate: A ThingSpeak-Based Indoor Positioning Platform for Academic Research on Location-Aware Internet of Things
Technologies 2019, 7(3), 50; https://doi.org/10.3390/technologies7030050 - 16 Jul 2019
Cited by 8 | Viewed by 4482
Abstract
Seamless location awareness is considered a cornerstone in the successful deployment of the Internet of Things (IoT). Support for IoT devices in indoor positioning platforms and, vice versa, availability of indoor positioning functions in IoT platforms, are however still in their early stages, [...] Read more.
Seamless location awareness is considered a cornerstone in the successful deployment of the Internet of Things (IoT). Support for IoT devices in indoor positioning platforms and, vice versa, availability of indoor positioning functions in IoT platforms, are however still in their early stages, posing a significant challenge in the study and research of the interaction of indoor positioning and IoT. This paper proposes a new indoor positioning platform, called ThingsLocate, that fills this gap by building upon the popular and flexible ThingSpeak cloud service for IoT, leveraging its data input and data processing capabilities and, most importantly, its native support for cloud execution of Matlab code. ThingsLocate provides a flexible, user-friendly WiFi fingerprinting indoor positioning service for IoT devices, based on Received Signal Strength Indicator (RSSI) information. The key components of ThingsLocate are introduced and described: RSSI channels used by IoT devices to provide WiFi RSSI data, an Analysis app estimating the position of the device, and a Location channel to publish such estimate. A proof-of-concept implementation of ThingsLocate is then introduced, and used to show the possibilities offered by the platform in the context of graduate studies and academic research on indoor positioning for IoT. Results of an experiment enabled by ThingsLocate with limited setup and no coding effort are presented, focusing on the impact of using different devices and different positioning algorithms on positioning accuracy. Full article
(This article belongs to the Special Issue Technology Advances on IoT Learning and Teaching)
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